Otoplasty is a commonly performed surgical procedure that restores the ideal position of the pinna. Although the pinna is a well-recognized component of the auditory apparatus, no studies have assessed the audiological effects of this procedure. We sought to quantify the impact of pinna repositioning on speech intelligibility and reception.t-tests for both pinna positions.Eighteen adults with normal hearing and pinnae were recruited and the pinna positions were randomized in each participant. Intracanal acoustical analysis was performed to calculate the Speech Intelligibility Index (SII). Hearing In Noise Test (HINT) with two azimuth speaker arrangement was also performed. The outcome measures were compared using paired The SII significantly improved with the pinna in forward position . HINT thresholds also improved with the pinna forward .Pinna position affects audiological performance, in both speech intelligibility and speech reception in noise. These are novel findings that may impact the informed consent process and decision to treat for patients undergoing otoplasty. Protruding ears, or prominotia, is the most common congenital deformity of the head and neck, with an incidence as high as 5 percent in certain populations . The speMany studies have described the “ideal” position of the outer ear -4. In adProtrusion of the pinna is typically measured along a hypothetical plane drawn from the lateral helical margin to the mastoid scalp. From the scalp, the helical rim at the superior pole normally projects laterally 10 to 12 mm, at the midpoint 16 to 18 mm, and at the lobule 20 to 22 mm . The aurThe pinna is a well-recognized component of the auditory system, with the ability to shape the incoming acoustic signal. Several studies have demonstrated that the shape of the pinna affects spatial localization, mainly in the vertical plane -13. In eThe literature on otoplasty has concentrated on technical considerations with numerous articles focusing on various surgical methods to correct the outstanding ear ,4,15. InIn this study, we investigated the effects of pinna position changes on speech intelligibility and reception in normal hearing adult subjects. We used the Hearing in Noise Test (HINT) materials to assess speech comprehension. To understand the acoustic effects, we also examined the pinna to external ear canal transfer function, and how it is changed by pinna position, and what the impact of this would be on the calculated speech intelligibility index (SII), and to see if this agreed with the measured HINT for different pinna positions.There are two ways that changing pinna position may affect speech comprehension in background noise. When speech and noise are presented together in space, the signal to noise (S/N) level required to understand speech is higher than if the noise and speech are separated, this is known as spatial release from masking . This isThe study protocol was reviewed and approved by the local Institutional Review Board.Seventeen adults with normal hearing and normal pinna shape and position were recruited. The participants were medical students and residents enrolled at Dalhousie University  or ear research laboratory employees. All potential candidates were given a brief explanation of the study, screened for a history of hearing loss, then invited to participate. If agreeable, they were given a study information sheet and asked to sign an informed consent form. Participants were not offered remuneration for their involvement.®) soft band was placed around the head, behind the left auricle  was measured from the lateral aspect of the helical rim to the mastoid skin at the mid-level  of the outer ear using a surgical caliper.For each subject, tests were performed four times: twice each with the pinna in “neutral” or their native position and “forward” or protruded position. To simulate a protruding pinna position, a bone-anchored hearing aid  was used to measure the sound pressure in the ear canal in both pinna positions, and to calculate the SII in accordance with ANSI S3.5, 1997, R2007. The SII is the predicted speech intelligibility, based on audibility of the speech signal at different frequencies. The SII was calculated by the Verifit software on the basis of the sound pressure level induced by a 12.8 second speech signal  measured within 5 mm of the tympanic membrane, with the left pinna in both neutral and forward position. The order was randomized using Microsoft Excel for Mac 2011  by using the rand function.In a soundproof booth, the Audioscan Verifit VF was positioned five feet from a wall to avoid reflections. The sensor was appropriately calibrated using the standard Verifit procedure. The volunteer was positioned in a chair three feet directly in front of the Verifit, and an insert microphone was placed in their left ear, once each with the pinna in neutral and forward positions. The placement of the distal probe tip was confirmed with otoscopy.As eluded to above, the SII provides an estimate of predicted speech intelligibility on the basis of the level of speech above background noise, and hearing thresholds (i.e. speech audibility) in a number of importance-weighted frequency bands (ANSI S3.5-1997). Because the measurements were made with normally hearing subjects in a sound-attenuating booth, speech levels were much higher than hearing thresholds and background noise levels were negligible. As a consequence, small differences in speech power levels resulting from changes in pinna position would not change the SII estimate due to ceiling effects. However, real-world listening rarely takes place in such quiet environments and many individuals have some degree of hearing loss, so small changes in speech audibility resulting from pinna position differences could affect speech audibility, and hence intelligibility. In order to improve the sensitivity of the SII to small changes in level, the subjects’ hearing threshold was set to 40 dB HL at all audiometric frequencies for the SII calculation. This means, the audibility and predicted speech comprehension was calculated for a person whose hearing threshold was assumed to be 40 dB HL.The stimulus level was set to 65 dB SPL(A) and the ear canal sound pressure for the 12.8 second stimulus was measured in each subject four times; twice with the pinna in each position.The HINT is a standardized test for assessing speech perception in noise, and can be used for measuring the improvement in speech perception that occurs when noise and speech come from different directions instead of the same direction  . During In the present study, the HINT test was performed on each subject with the left pinna in neutral and forward positions, with the speech presented at 45° to the left, and the noise presented at left 45° (coincident with speech) and left 135° (90° separated from speech) in different conditions. The right pinna was unaltered and not occluded. Phillips and colleagues  found a The sound booth was arranged with speakers located at 45° and 135° left from the patient’s midline .Speech tests were performed in both pinna positions, and with background noise either coming from the same speaker (i.e. speech and noise both at -45° to the subject), and with speech at -45° and noise at -135° (i.e. noise from in front or behind the variably cupped pinna). As mentioned above, the pinna acted as a shield to the noise in the -135° condition, and a baffle in the -45° condition. The four subtests performed were thus, HINT score with speech at -45° and:- Test A: Pinna neutral, noise at -45°- Test B: Pinna neutral, noise at -135°- Test C: Pinna forward, noise at -45°- Test D: Pinna forward, noise at -135°The order of the subtests was randomized for each subject. The subjects were not pre-informed of the direction of the noise before each randomized subtest. Blinding the subject to their pinna position was not possible due to the tactile nature of the softband.During each subtest, the noise was introduced at 65 dB SPL(A) and kept constant at this level. The first sentence list was introduced at 65 dB SPL(A) as well, while the subsequent three sentences were introduced at 5 dB louder if the subject failed to successfully repeat the initial list, or less by 5 dB if they were successful. The remaining 16 sentences were increased or decreased by 2 dB depending on the ability to correctly repeat sentences. The S/N level at which 50% correct responses were obtained was recorded.after tests 4 through 20 was calculated, as per the standard HINT scoring protocol. The HINT threshold (dB S/N) for each subtest was calculated as mean sentence level (dB) minus 65 dB SPL(A). It is important to appreciate that even small changes in the S/N ratio in this test can translate to large changes in sentence recognition scores  by pinna position was examined by t-tests.SII was also compared to HINT data using paired, two-tailed ® softband, as expected . The increase was statistically significant (p = 0.0000).Seventeen volunteers  were recruited. Their baseline demographics are outlined in Table p < 0.001). The SII data are summarized in Table The calculated SII significantly improved with the pinna in forward position   . Similarly, with noise at -45°, pinna forward position had a lower (better) 0.77 dB S/N ratio . These data are summarized in Table With noise at -135°, the measured HINT S/N ratio with the pinna forward was 1.35 dB better compared to when the pinna was in the neutral position  with noise at -135°, so that subjects showed good intra-subject correlation in the two conditions. This relationship is demonstrated in Figure r = 0.38) but not statistically significant (p = 0.13).The Pearson correlation between HINT with pinna forward and neutral positions for individual subjects was strong    was compared with the change in SII between pinna positions. When the HINT noise was introduced at -45°, there was not a significant correlation  Figure . Similar) Figure .The treatment of prominent ears with otoplasty is a relatively common procedure. The International Society of Aesthetic Plastic Surgery estimated that over 242,000 otoplasties were performed worldwide in 2010 . At highBy the age of 5 years, the growth of the cartilaginous pinna is almost complete . This coWhile Down syndrome and Turner syndrome may be associated with both prominent ears and conductive hearing loss, prominent ears are not generally thought to be associated with hearing issues. As well, many surgeons who perform otoplasties are unaware of any hearing related consequences with respect to the protruding ears. Thus, prominent ears in a child is not in itself an indication for any type of audiometric evaluation. This has led to the absence of any studies being conducted in this particular area.In this surrogate study, we investigated the effects of temporary changes in the forward position of the pinna on speech intelligibility and reception in normal hearing adult subjects. While otoplasty is more commonly performed in children, adults are more cooperative and reliable subjects; they are better to accommodate a long battery of audiologic tests. While it is unlikely that the purely acoustic effects of pinna position vary from adults to children, further testing in a pediatric population is necessary to confirm the present results.Although the function of hearing has traditionally been considered unimportant and unaltered in otoplasty procedures, this has simply been an assumption. As hearing and speech development occurs early in life and since otoplasty is performed mainly in young children, it may be important to understand how, if at all, this procedure may affect auditory function.If “normalizing” the shape of the ear is found to affect auditory perception, this may have consequences to the child functioning in noisy environments, and maybe something further to consider in the informed consent, and risk/benefit assessment.The shape of the pinna is thought to contribute to vertical sound localization in humans by providing monaural spectral cues. Hofman and Opstal  used pinOur findings demonstrate a statistically significant difference in speech intelligibility. However, it is difficult to precisely quantify the degree of noticeable change in a real world scenario. It is likely to be small in the practical sense. Furthermore , there may be an adaptability to the changes in hearing after otoplasty surgery, which may affect long-term outcomes. Potential adaptation might occur in a manner similar to Hofman and Opstal’s vertical sound localization study  previousAgain, we found that a pinna in forward position results in a statistically significant improvement in speech intelligibility when the speech is introduced at -45° from anterior. Further investigation may find that a forward pinna may be disadvantageous for understanding speech introduced from behind. Yet, in most real world scenarios, the sound source of interest is in the front hemifield (e.g. facing your conversation partner). We chose to focus on this more likely test condition, but it is important to acknowledge that there may be scenarios in which improved rear speech intelligibility may be beneficial with the pinna in non-protruded position .This is the first study to assess any aspect of auditory function with respect to changes in pinna position. Future research may investigate children undergoing the actual otoplasty procedure, to assess both the immediate auditory effect and the long-term hearing function and possible adaption.During conduction of the SII and HINT tests, neither the tester nor subjects were blinded to pinna position.For cases of otoplasty where a conchomastoid suture is placed, there may be slight narrowing of the external auditory canal meatus. This possible effect was not reproduced in the study population and therefore, may confer the results ungeneralizable to those patients who receive the conchomastoid suture. Yet the incidence of significant meatal stenosis after otoplasty is extremely rare and therefore, this particular effect is deemed to be negligible.Pinna position changes affected audiological performance, in both speech intelligibility and speech reception in noise, in our study population. These are novel findings that should warrant further research and may possibly impact the informed consent process for patients undergoing otoplasty.Accepted for publication for the Journal of Otolaryngology-Head and Neck Surgery, October 2012.Accepted for presentation at the 2012 Poliquin Resident Research Competition, Canadian Society of Otolaryngology – Head and Neck Surgery’s 66th Annual Meeting, Toronto, Ontario, Canada, May 2012.The authors declare that they have no competing interests.PH, SJA, MLM and MB were involved in the study design, data analysis and interpretation. MLM and JRL carried out the experiments. All authors read and approved the final manuscript.


Enjoyment of music is an important part of life that may be degraded for people with hearing impairments, especially those using cochlear implants. The ability to follow separate lines of melody is an important factor in music appreciation. This ability relies on effective auditory streaming, which is much reduced in people with hearing impairment, contributing to difficulties in music appreciation. The aim of this study was to assess whether visual cues could reduce the subjective difficulty of segregating a melody from interleaved background notes in normally hearing listeners, those using hearing aids, and those using cochlear implants.Normally hearing listeners (N = 20), hearing aid users (N = 10), and cochlear implant users (N = 11) were asked to rate the difficulty of segregating a repeating four-note melody from random interleaved distracter notes. The pitch of the background notes was gradually increased or decreased throughout blocks, providing a range of difficulty from easy (with a large pitch separation between melody and distracter) to impossible (with the melody and distracter completely overlapping). Visual cues were provided on half the blocks, and difficulty ratings for blocks with and without visual cues were compared between groups. Visual cues reduced the subjective difficulty of extracting the melody from the distracter notes for normally hearing listeners and cochlear implant users, but not hearing aid users.Simple visual cues may improve the ability of cochlear implant users to segregate lines of music, thus potentially increasing their enjoyment of music. More research is needed to determine what type of acoustic cues to encode visually in order to optimise the benefits they may provide. Auditory sensation can often be partially restored in people with hearing impairment. When the impairment is mild to severe, amplification via a hearing aid (HA) can be sufficient. For the profoundly deaf, a cochlear implant (CI) is required. A CI is a neural prosthesis that directly stimulates the auditory nerve, bypassing missing or diseased cochlear hair cells. Cochlear implants are successful in restoring speech perception in most individuals Music often contains many such streams – for instance a melody and harmony played on a single instrument, or multiple melodies played by the same or separate instruments. Much of the skill of the composer is in manipulating the perception of these streams, and the ability to interpret them separately is vital to the appreciation of music. The capacity to separate and group auditory streams is called auditory stream segregation A hearing aid processes and amplifies sound signals, and delivers acoustic stimulation to the eardrum via a small loudspeaker in or near the ear canal. The type of signal processing applied varies between devices and prescribed fittings, but can include peak-limiting, amplitude compression, non-linear gain, frequency shifting, and many types of noise reduction algorithms. The application and adjustment of these parameters can have a significant effect on music perception and appreciation et al.To our knowledge there are no published studies investigating stream segregation using non-speech stimuli in hearing-impaired listeners while they are using their hearing aids. However there have been several investigations, in un-aided listeners, of the effect of hearing loss itself on the ability to separate auditory streams. In a melody recognition task conducted with hearing-impaired (HI) and normally-hearing (NH) listeners, de Laat and Plomp Most contemporary CIs operate by converting the amplitude envelopes of the outputs of a series of between 16 and 22 bandpass filters into current levels, which are sent to an electrode array within the cochlea. As only the amplitude envelopes are encoded, most spectral detail is discarded, and the sensation of pitch is mainly elicited by manipulating the region of the cochlea stimulated by different electrodes , was conducted at the Bionics Institute in Melbourne, Australia, and was approved by the Human Research Ethics Committee of the Royal Victorian Eye and Ear Hospital (Project 09-880H). Written, informed consent was obtained from all participants prior to participation in the study.A total of forty-two participants were recruited. Twenty participants with normal hearing  were recruited through a combination of social networks and advertisements on the Bionics Institute website. All these participants had been part of other studies involving streaming rating judgments, and were not musically trained based on a self-report musical aptitude scale Eleven CI users  were recruited from the Cochlear Implant Clinic at the Royal Victorian Eye and Ear Hospital in Melbourne, Australia. All participants had profound post-lingual sensorineural hearing loss of hereditary or unknown origin in both ears. All participants had a minimum of three years experience with their CI, and the standard everyday program was selected on their sound processor. No adjustments were made to program, gain, or sensitivity settings during the testing session. If a hearing aid was prescribed for the contralateral ear, it was switched off and replaced by an ear plug. One participant, CI_11, had bilateral cochlear implants, both of these were switched on and operating as usual. Age, sex, and cochlear implant details are shown in Ten HA users  were recruited from local hearing aid clinics. All HA users had bilateral aids, and both were switched on, using their normal everyday programs. All HA users had a minimum of 2 years experience with their HAs. Age, sex and HA details are shown in Recent work has emphasised the development of objective, performance-based measures of auditory streaming obligatory streaming occurs minimum difference that allowed participants to start to segregate the streams. Thus, the task in the current experiment was designed to measure the fission boundary (FB) Performance-based tasks such as those mentioned above generally measure the temporal coherence boundary  running MAX/MSP 5 software  through an M-AUDIO  48-kHz 24-bit Firewire sound card. Each note consisted of a 180 ms complex tone with 10 harmonics. Each successive harmonic was attenuated by 3 dB, and each note included a 30 ms raised-cosine onset and 10 ms offset. The notes were played from a loudspeaker  positioned on a stand at the listener's ear height, 1 m from the listener's head. Each note was equalised in loudness to 65 phons according to a loudness model The visual cue was also generated with MAX/MSP 5. It consisted of a musical stave with the 4-note target melody depicted in standard musical notation see . Each noThe pattern of electrical stimulation for the 4-note melody, delivered acoustically to the participants own sound processor, was recorded for each CI participant using RFstatistics . An example from one participant is shown in In the subjective difficulty rating task, the four-note target melody spanned 8 semitones, while the distracter note pitches were randomly chosen from a 12-semitone wide range of notes. The target melody pitches see  were G, Conditions with and without visual cues see , where tThe participants were asked to rate the difficulty of perceiving the four-note melody continuously throughout each block using a variable slider on a midi controller (EDIROL U33). The slider was labeled from 0 (no difficulty hearing melody) to 10 (impossible to hear melody). The slider was initialized at the 0 position for INC blocks and at the 10 position for DEC blocks. Participants were instructed to move the slider to the “10” position if the melody was impossible to perceive and to the “0” position if the melody could be easily perceived, and to start moving the slider to reflect their perceived difficulty level as soon as the block began. The position of the slider (encoded with 128 possible difficulty levels) was recorded for each melody repetition and stored for later analysis.The level of the distractor was changed gradually and monotonically, rather than in a randomised fashion, in order to minimise the streaming build-up effect To quantify the effect of the visual cues on difficulty ratings, the difference between Vision and No-Vision blocks was calculated. This difference, corresponding to the reduction in difficulty provided by the visual cue, is shown as a function of distracter note level in F  =  4.3, p = .05, 2r  = .004, with difficulty ratings in INC blocks generally lower than in DEC blocks. There were no significant interactions of Direction with either Level or Vision. As this effect had only borderline statistical significance, and was not important for interpreting the results, it was collapsed and the analysis was re-run The main factor Group was highly significant, F = 25.7, p<.0001, 2r = .021, as well as the main factor Level, F = 656.7, p<.0001, 2r = .93. There was a significant Group x Level x Vision three-way interaction, F = 4.0, p = .03, r2 = .002. The interaction was decomposed using Tukey HSD tests. Means across all levels are plotted in p<.001), and HA users (p<.001). There were significant differences between Vision and No-Vision blocks for the NH ( p = .007) and CI (p = .02) groups, but not for HA users.In order to assess overall effects of the distracter separation level, the visual cue and direction of the distracter (INC vs DEC blocks), difficulty ratings were averaged across the two repeats for each condition, and submitted to a repeated measures mixed GLM, with a continuous within-subjects factor of Level (20 distracter note separation levels), categorical within-subjects factors of Vision , and Direction (INC and DEC blocks), and a between-subjects factor of Group . The rating data were expected to follow a psychometric function with the level that was modelled as: rating  =  1/(1+exp(a*level+b)). Therefore the rating scores were transformed as: rating'  =  log(1/rating -1) in order to have a linear relationship between the rating and the level. Results were bounded to .01 and .99 prior to transformation in order to avoid infinite points. There was a small and borderline significant main effect of Direction, Our previous research The present study employed a musical stream segregation paradigm, where participants were asked to continuously rate the subjective difficulty of segregating a simple four-note melody from a background of interleaved random distracter notes. As the distracter notes increased in pitch towards the melody notes, difficulty ratings generally increased monotonically. This result replicates our previous study The main finding from the current study was that the presentation of a simple visual cue significantly reduced the subjective difficulty of segregating a simple 4-note melody from a background of interleaved random distracter notes in normal-hearing listeners and those using a cochlear implant, but the effect was weaker and more variable in hearing aid users.et al.segregated auditory perception. The visual cue thus acted to resolve an ambiguous auditory sequence.There is now a large body of literature describing how congruent audio-visual stimuli of many different types are recognised faster and detected more accurately at near-threshold levels than either the visual or auditory stimulus alone The effect of visual stimuli on auditory processing has also been described at low levels in the brain. It has been shown that visual cues presented at the same time as auditory stimuli can reduce reaction times et al.When the visual cues were present, the grand mean difficulty rating for CI users was not significantly different to normal-hearing listeners without the benefit of the visual cue . Whetherreduction in difficulty ratings for the HA users is that the complex harmonic stimuli may have introduced additional perceptual cues dependant on F0: as F0 increases, the higher harmonics in the stimuli may be relatively more attenuated in the HA group compared to the NH group, thus introducing a change in timbre. This cue could be used in addition to pitch to perform the streaming task Hearing aid users in the current study reported overall difficulty ratings that were no higher than the in NH group. Indeed, although the difference was not statistically significant, the mean difficulty ratings in both the Visual and Non-Visual conditions were slightly lower than in the NH group . This waet al.Unlike the NH group and the CI users, HA users in the current study gained only a small and statistically insignificant benefit from the visual cues. The result cannot be explained by floor effects, as when the distracter notes were overlapping the melody, the HA group still reported high levels of difficulty in extracting the melody. Given previous research showing that hearing-impaired listeners gain benefit from visual cues in speech perception One intriguing result from the current study was that while CI users did report more difficulty extracting the melody than normally hearing listeners and hearing aid users see , their oMelody recognition tasks, such as that conducted by Singh, Kong and Zeng In the current study however, veridical recognition of the melody was not required. To maintain ecological validity, complex tones with ten harmonics (with a slope of 3dB/octave), were presented via loudspeaker in free-field conditions. The pattern across electrodes tended to be different for each note . A video screenshot showing the stimulus display in no-vision blocks. The video is an example of an INC block with no visual stimulus, where the range of possible distracter notes gradually increases towards the melody, making it gradually more difficult to segregate the melody from distracter notes. The rate of change of the distracter note range has been increased to shorten the length of the demo video.(MP4)Click here for additional data file.File S2Stimulus display (vision). A video screenshot showing the stimulus display in no-vision blocks. The video is an example of an INC block with the visual stimulus, where the range of possible distracter notes gradually increases towards the melody, making it gradually more difficult to segregate the melody from distracter notes. The rate of change of the distracter note range has been increased to shorten the length of the demo video.(MP4)Click here for additional data file.


CI users were best able to discern rhythm changes (p < 0.01) and to remember musical pieces (p < 0.01). Contrary to expectations, abilities to hear cues in music improved as the age at implantation increased (p < 0.01). Because the children implanted at older ages also had better low frequency hearing prior to cochlear implantation and were able to use this hearing by wearing hearing aids. Access to early acoustical hearing in the lower frequency ranges appears to establish a base for music perception, which can be accessed with later electrical CI hearing.Cochlear implants (CIs) electrically stimulate the auditory nerve providing children who are deaf with access to speech and music. Because of device limitations, it was hypothesized that children using CIs develop abnormal perception of musical cues. Perception of pitch and rhythm as well as memory for music was measured by the children’s version of the Montreal Battery of Evaluation of Amusia (MBEA) in 23 unilateral CI users and 22 age-matched children with normal hearing. Children with CIs were less accurate than their normal hearing peers ( Around the globe, music forms an integral part of society and culture, however, much of the acoustical information in music is unavailable to those with significant hearing loss or deafness without the aid of an auditory prosthesis. Cochlear implants (CIs) are neuroprosthetic devices that bypass the dysfunctional cochlea and directly stimulate the auditory nerve with electrical pulses. Children with congenital or acquired deafness who use CIs develop speech and language skills required for oral communication , but their listening is impaired when the same melody is presented in an instrumental version only  and was not supporting speech and language development. Most importantly, hearing aid use in some children yielded poorer speech perception skills than those achieved by many children using CIs Somers, . As a reTwenty-three children and adolescents participated in the present study. They had used unilateral CIs for a mean(SD) duration of 6.4(3.4) years (CI group) and were between the ages of 7–16 years [mean(SD) = 12.5(2.7) years] and 22 age-matched typically developing control children with typical hearing .t(10) = 1.3, p = 0.21].The CI group consisted of 15 children and adolescents using right unilateral CIs, and eight children using left CIs. All CI children attended mainstream classrooms and used oral communication. Twenty-one CI participants used Nucleus 24 devices, 2 participants used Nucleus 22 devices, and 1 had an Advanced Bionics device. There were eight children in each group who had participated in musical training (35% of CI group and 36% of NH group). The duration of training was mean(SD) = 1.5(1.3) years for the eight children in the CI group and mean(SD) = 3.0(2.8) for the eight children in the NH group; these durations were not significantly different from one another . We suggest that children with better residual hearing had greater access to sound prior to implantation and thus delayed seeking a cochlear implant. This is shown by a strongly positive correlation between duration of hearing aid use and the age at CI activation  and, as shown in Figure r = 0.68, p = 0.002). These older children were also more likely to retain better residual hearing in the unimplanted ear after cochlear implantation .As expected, there was a negative association between pre-implant aided responses at 250 Hz and age at CI activation , which is a standardized measure of music perception originally developed for evaluating amusia in adults  are used to make the test as musically engaging as possible.The children’s version of the MBEA  which meant that the music stimuli would be inaudible on that side. The other seven children had less severe hearing loss at 250 and 500 Hz .Musical stimuli were presented in a sound-proof booth and played through a laptop computer and an external speaker (UHL Studio Monitor 4406). Musical stimuli were in the range of 60–65 dB SPL as measured by a sound level meter placed in the approximate position of the participants head and played at a fixed volume for all participants. Participants were seated at a fixed distance, zero degrees azimuth to the speaker. No changes were made to their cochlear implant settings and none of the children wore a hearing aid in the opposite ear. Most of the children had severe to profound hearing loss in the unimplanted ear  with a between group analysis to compare data from the CI and NH groups. Second, effects of CI participant demographics on MBEA scores were assessed using linear regression models. Along with age at CI implantation [mean(SD) = 5.5(2.9) years], independent variables included in regression analyses were duration of deafness and degree of residual hearing. Effects of pre-implant hearing were confirmed by repeated measures ANOVA across subtest scores with a between group analysis of CI children with and without useable residual low frequency hearing (usable hearing at 250 Hz defined by thresholds of <40 dB HL with hearing aids).We first examined whether children using CIs were able to detect differences in pitch and rhythm in music as well as their age-matched hearing peers. Group performance on MBEA tests are shown in Figure p > 0.05) between the left and right unilateral CI groups. As a result, the two CI groups were combined. Repeated measures ANOVAs were conducted with MBEA tests  as within-subjects factors, group (CI and NH) as the between-subjects factor, and duration of musical training as a co-variate. Analyses revealed a significant main effect of MBEA tests, F = 7.4, p = 0.005, a significant effect of group, F = 31.5, p = < 0.0001, and a significant interaction effect of MBEA tests and group, F = 3.9, p = 0.04. There was no significant effect of music training F = 0.24, p = 0.63 nor significant interaction between music training and test, F = 3.9, p = 0.90. Post hoc analyses of simple effects for significant interaction showed that the CI group performed significantly less accurately across MBEA tests when compared to the NH group (p < 0.001). Within group analyses using repeated measures ANOVA with post hoct-testing indicated that, as hypothesized, the CI group performed most accurately on the Rhythm Contour and least accurately on the Scale test . The NH group also performed least accurately on the Scale test .The CI group consisted of both left and right unilateral users. The determining factors for implanting the right ear vs. left ear are varied, including whether or not there is an intact cochlear nerve on one side vs. the other. In order to address the potential confound of the ear implanted, statistical analyses were conducted using a repeated measures ANOVA design to determine group differences within the CI group between left unilateral and right unilateral CI groups. No statistically significant differences were detected  and only for unaided thresholds at 250 Hz not 500, 1000, 2000, or 4000 Hz . As shown in Figure r < |0.30|, p > 0.05).The most obvious possible reason for improved scores in some children using CIs could be their use of residual hearing in the unimplanted ear. Yet, residual hearing on that side was only significantly correlated with scores on the Rhythm Test  and, in multiple linear regression, age at CI activation continued to be significant (p < 0.05) whereas duration of CI use was not (p > 0.05). Rather, the positive effects of age reflected increased hearing aid use with better hearing thresholds prior to cochlear implantation; a repeated measures ANOVA indicated that children with aided thresholds at 250 Hz of better than 40 dB HL prior to implantation had significantly better subtest scores than children with poorer pre-implant hearing, F = 5.9, p = 0.03. As shown in Figure r = −0.52, p = 0.024), Rhythm , and Incidental Memory  tests. A significant relationship was also found on the MBEA total score .This was opposite to our expectations and could not be explained by longer periods of implant use in the older group since none of these scores were significantly related to duration of implant use . Superior performance on rhythm relative to pitch perception is consistent with previous studies in adult CI users . Nonetheless, the CI group was able to automatically encode, retain, and retrieve complex auditory input without prompts.Another area of relative strength shown by the CI group was their performance on the Incidental Memory test on the MBEA, which was significantly better than other tests , although still significantly below the control group on this task. This indicates that these children had some ability to retain memory for melodies. This finding appears to be unique to children using CI as compared to adult CI users, who have been shown to perform poorly on the memory test of the adult version of the MBEA task  than others.We found that outcomes on the MBEA Total and the Interval and Rhythm tests improve as the age of cochlear implantation increases. This appeared to counter evidence that children implanted at older ages generally achieve poorer speech perception skills than their peers implanted at younger ages . Rather, children with better access to acoustical hearing prior to cochlear implantation (aided thresholds at 250 Hz <40 dB HL) had significantly improved scores compared to children with poorer pre-implant hearing. This suggests that having greater access to acoustical hearing in the lower frequency range  during early development enhances the perception of music with later cochlear implant use. Effects were found on the MBEA in general and, in particular, to tests of Interval, Rhythm, and Incidental Memory. Effects of pre-implant hearing on the Interval test, in particular, might be explained by development of auditory pathways through acoustical stimulation which can then be accessed with electrical stimulation. These findings are consistent with improved music perception in adults with post-lingual onset of deafness compared to children who have been deaf from young ages (Jung et al., Access to acoustic input prior to implantation also appears to help children using CIs to remember melodic information. Memory for music is essential for deriving pleasure from music, and individuals often like familiar songs over novel songs. Children using CIs are known to take pleasure from music, are involved in musical activities (Gfeller et al., A remarkable demonstration of neural plasticity is the acquisition of sound perception in an otherwise silent brain in deaf individuals fitted with cochlear implant devices. The present findings suggest that exposure to early acoustical auditory experience enhances the perception of music with electrical hearing, especially for detecting differences in rhythm, and memorizing melodies. Even though children using CIs typically performed significantly poorer than their hearing peers in detecting musical cues some were able to perceive these cues better than others. Those children who had more access to acoustical hearing in the low frequency regions through their pre-implant hearing aids, used their hearing aids for a longer duration of time, received their implants at older ages, showed the best skills. This speaks to the importance of acoustic input for auditory development and suggests that these developing pathways can adapt to the new electrical input provided by a cochlear implant.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Osteogenesis imperfecta (OI) is the most common heritable disorder of connective tissue. It is associated with fractures following relatively minor injury, blue sclerae, dentinogenesis imperfecta, increased joint mobility, short stature, and hearing loss. Structures in the otic capsule and inner ear share in the histologic features common to other skeletal tissues. OI is due to mutations involving several genes, the most commonly involved are the COL1A1 or COL1A2 genes which are responsible for the synthesis of the proalpha-1 and proalpha-2 polypeptide chains that form the type I collagen triple helix. A genotype/phenotype relationship to hearing loss has not been established in OI. Hearing loss is commonly found in OI with prevalence rates ranging from 50 to 92% in some studies. Hearing loss in OI may be conductive, mixed, or sensorineural and is more common by the second or third decade. Treatment options such as hearing aids, stapes surgery, and cochlear implants are discussed. Osteogenesis imperfecta (OI) is the most common of the heritable disorders of bone as first defined by McKusick in 1956 [The hallmark of OI is the occurrence of fractures with relatively minor injury. Blue sclerae, dentinogenesis imperfecta, increased joint mobility, and short stature are common to the 8 phenotypes that are currently recognized . As showType I collagen is the most abundant protein in the body. OI is the result of mutations involving several genes responsible for the synthesis or intracellular processing of type I collagen (COL1). To date, 7 genes have been implicated as causative in OI , 3. NineAs noted above, disordered type I collagen synthesis affects multiple organs in addition to bone. Blue sclerae result from altered light reflectance in the presence of abnormal scleral collagen . CornealThere is limited information about the histopathology of the temporal bone in OI. Berger et al. examined the histopathologic findings in 8 temporal bones from 5 patients with type III osteogenesis imperfecta . EvidencComputerized tomography (CT) of the temporal bone in an OI type I patient demonstrated otic capsule demineralization that appeared to progress as hearing diminished . Band-liHearing loss is a significant clinical feature in many patients with OI. In national surveys of hearing loss in OI, prevalence rates of hearing loss of 46%  to 57.9%It is frequently reported that conductive hearing loss is found in younger patients with OI, whereas sensorineural hearing loss is found more in older patients with OI , 23, 28. Several investigators have reported that hearing loss is infrequent in OI until the 2nd or 3rd decade of life, increasing with advancing age , 21, 28. The etiology of sensorineural hearing loss in OI has not been definitively determined but may be a consequence of atrophy of the cochlear hair cells and the stria vascularis as well as from abnormal bone formation in the cochlea and surrounding structures . PatientHearing loss is very common in older patients with OI and in one recent study in older patients (Mean age = 44 years) with OI, 87% of ears had some degree of hearing loss . In youn Conductive hearing loss is typically reported as the initial manifestation of hearing loss in OI , 17, 19.S, B, and C) [D pattern is more commonly found [D pattern is often associated with ossicular discontinuity although it can also be consistent with atrophic scarring of the tympanic membrane. The use of only a low-frequency probe tone in these studies may explain the poor test performance of tympanometry clinically [As noted recently, measurement of hearing loss and the determination of etiology of the hearing loss presents some challenges in OI . The use, and C) . In contly found . The typinically , 19. Theinically .Treatment of hearing loss in OI can be divided into categories based on the severity of the hearing loss and the etiology. As noted above, the loss can be conductive , sensorineural , or a combination of both. The degree of hearing loss helps determine if any intervention is necessary, and if so, what that intervention should be.Conductive hearing loss theoretically can be fully corrected. In people without OI, that is unfortunately not always possible. In people with OI, the percentages that are not correctable are higher.Fluid in the middle ear causes loss of hearing by limiting ear drum and ossicle motion. This occurs commonly in young children but can occur at any age. Common causes include Eustachian tube dysfunction, colds, ear infections, and allergies. When treatment of the underlying cause does not resolve the fluid, ventilation tubes can be placed. The incidence of serous otitis may be higher in OI. But the treatment outcomes are the same.OI can cause deformity of the ossicles described earlier. These deformities can lead to a conductive hearing loss from ossicular fracture and stapes footplate fixation. Surgical correction is usually possible, but results of such surgery are significantly worse than similar surgery in non-OI series reports . StapedeTreatment for sensorineural hearing loss in people with OI is similar to people without OI. Hearing aids can help manage sensorineural, conductive, and mixed  hearing loss. Since hearing aids amplify the sound going into the ear, the amount of the loss is more important than the cause of the loss. However, it should be noted that individuals with sensorineural hearing loss typically have greater problems with speech recognition and loudness processing than is the case with conductive hearing loss. Fitting a person with OI with a hearing aid is the same as fitting someone without OI. 2–11% of patients with OI will have hearing deterioration such that hearing aids will no longer be useful. Cochlear implants provide an option for restoring hearing –47. TheyThis is an alternative treatment for conductive hearing loss and single-sided deafness. It requires one normal functioning inner ear. It also requires that the titanium implant osseointegrates into the bone. A hearing aid is then attached to the implant to directly stimulate the bone. This vibration is sent to the inner ear to stimulate hearing by bypassing the ossicles. This is the same integration technology used with some dental implants. Since many patients with OI develop bilateral sensorineural hearing loss, they may not be a candidate for the BAHA anyway. With the high percentage of people with sensorineural hearing loss, the number of qualified BAHA candidates will be low. To date, no data on the use of this implant in OI is available.Implantable hearing aids are starting to make their way into the option list for treating hearing loss. These devices drive the ossicular chain directly rather than amplifing the sound through air. They are attached to the ossicles surgically. Given the fragility of the ossicles in OI, they may not be a good option. However, beneficial results of Vibrant SoundBridge implantation in combination with stapedectomy have recently been reported in a small sample of three patients with OI .


Prenatal ultrasound exams have become increasingly frequent. Although no serious adverse effects are known, the public health implications would be enormous should adverse effects on auditory development be shown. This study looks to establish a possible correlation between hearing loss and increased prenatal ultrasound exposure.Retrospective cohort analysis.Tertiary academic referral center.A retrospective review of 100 children undergoing newborn hearing screening was conducted. Extensive data collection was performed, and this data was analyzed for a potential correlation between failure of newborn hearing screening and increased prenatal ultrasound exposure, as well as for a potential correlation of other variables with hearing loss.Postnatal hearing outcomes.rd trimester ultrasound exams as well as a younger gestational age at birth were all found to be significantly associated with a higher likelihood of passing the newborn hearing screen (p<0.001 for each). No other factors were found to reach statistical significance.A higher number of both total and 3Our results show that there is no correlation between a higher level of prenatal ultrasound exposure and hearing loss. Indeed, infants who had more prenatal ultrasounds in the third trimester were more likely to pass their screening hearing exams. The finding that children receiving more prenatal ultrasounds have a higher likelihood of passing newborn hearing screens serves as an excellent reminder of the classic statistics rule that correlation does not imply causation. Ultrasonography (US) now has a wide range of clinical uses and has become virtually indispensable in many areas of medicine. The development of prenatal US represents one of the greater achievements in the field of obstetrics. However, despite the widespread prevalence of prenatal US, it is not entirely clear whether US waves are free of risk to the developing fetus. Because of the increasing use of this imaging modality, the public health implications of any potential adverse effects are enormous. These concerns are even more important in light of the fact that routine US screening of the fetus has not been shown to improve perinatal morbidity ,2, despiOnly a small number of studies have investigated the immediate and long-term effects of US on fetal development. Links have been proposed between increased US exposure and handedness -6, neuroAfter appropriate Institutional Review Board approval, a retrospective chart review was conducted, using CPT codes for newborn hearing screening over the time period 01/01/2007 to 12/31/2010. Records were reviewed of both children and mothers for fifty children found to have normal (passed) newborn hearing screens and also for 50 children with abnormal (failed) newborn hearing screens.Hearing screens conducted in the well-newborn nursery were conducted as distortion-product otoacoustic emissions (DPOAE) and those conducted in the neonatal intensive care unit were done as auditory brainstem response (ABR) tests. Data collected included the number of prenatal US exams in each trimester, perinatal and pregnancy complications, gestational age at birth, presence of perinatal hypoxia at birth, maternal substance abuse, maternal age at birth, presence of otologic abnormalities at birth, use of ototoxic medications prenatally or postnatally, comorbidities, birth condition, post-natal course, family history of hearing loss, APGAR scores at 1 and 5 minutes, type and degree of documented hearing loss when available, and length of follow-up. To allow statistical comparison, we classified obstetrical events using the McNeil-Sjostrom Obsterics Complication Scale, which is an established systematic evaluation and weighting of several hundred specific somatic conditions and events during pregnancy, labor-delivery, and the prenatal period ,13. We uDemographics of both the hearing screen failures and control group are summarized in Table Using the non-parametric Wilcoxon Rank-Sums test, there was found to be a significant difference in both total number of ultrasounds (p<0.001 respectively) and ultrasounds in the third trimester (p<0.001) between patients with and without failed hearing screens  and a younger gestational age at birth (p<0.001) were significantly associated with a higher likelihood of passing the newborn hearing screen . A waiver of informed consent was granted for the study.The authors declare that they have no competing interests.CFH - Institution Review Board approval process, literature search, data collection, drafted the manuscript. PMW - data interpretation and statistical analysis, CAH - Institution Review Board approval process and manuscript revision JCB - study design and manuscript revision. All authors read and approved the final manuscript.


The complete genomic sequence of a new H9N2 avian influenza virus (AIV), isolated in northwestern China, was determined. Sequence and phylogenetic analyses based on the sequences of eight genomic segments revealed that the isolate is phylogenetically related to the Y280-like sublineage. During the last decade, H9N2 avian influenza viruses (AIVs) have circulated worldwide in poultry and caused economic losses in the poultry industry in many countries , 2. AsiaIn this study, the full-length sequences of eight genomic segments of a new H9N2 AIV isolate, A/chicken/Shaanxi/11/2012 (H9N2), were determined. Sequence and phylogenetic analyses indicated that the isolate is phylogenetically related to the Y280-like sublineage. In the present study, we found that the hemagglutinin (HA), neuraminidase (NA), and nonstructural (NS) genes of the new isolate share 92 to 98.0% nucleotide homologies with those of the H9N2 AIVs. More importantly, the nucleoprotein (NP) gene is closely related to that of the H5N1 AIVs isolated in eastern China. The matrix (M) gene has 92.0 to 93.1% nucleotide similarity with a H6N1 virus isolated from Guangzhou province in 2004, indicating that complicated reassortments of AIVs occurred in China.335RSSRGLF341 sequences at the cleavage site in the HA protein indicate that the isolate is a low-pathogenic type (LPAIV) (The (LPAIV) . Seven p (LPAIV) . Two ami (LPAIV) . H9N2 AI (LPAIV) . InteresThe new isolate does not contain the mutation E62K or D701N  in the RThe GenBank accession numbers of the new H9N2 AIV isolate from Shaanxi province are shown in


Horizontal gene transfer (HGT) is a major factor in the evolution of prokaryotes. An intriguing question is whether HGT is maintained during evolution of prokaryotes owing to its adaptive value or is a byproduct of selection driven by other factors such as consumption of extracellular DNA (eDNA) as a nutrient. One hypothesis posits that HGT can restore genes inactivated by mutations and thereby prevent stochastic, irreversible deterioration of genomes in finite populations known as Muller’s ratchet. To examine this hypothesis, we developed a population genetic model of prokaryotes undergoing HGT via homologous recombination. Analysis of this model indicates that HGT can prevent the operation of Muller’s ratchet even when the source of transferred genes is eDNA that comes from dead cells and on average carries more deleterious mutations than the DNA of recipient live cells. Moreover, if HGT is sufficiently frequent and eDNA diffusion sufficiently rapid, a subdivided population is shown to be more resistant to Muller’s ratchet than an undivided population of an equal overall size. Thus, to maintain genomic information in the face of Muller’s ratchet, it is more advantageous to partition individuals into multiple subpopulations and let them “cross-reference” each other’s genetic information through HGT than to collect all individuals in one population and thereby maximize the efficacy of natural selection. Taken together, the results suggest that HGT could be an important condition for the long-term maintenance of genomic information in prokaryotes through the prevention of Muller’s ratchet. The model was analyzed under the assumption that is most unfavorable to the hypothesized advantage of HGT, namely, that variation in fitness is attributed solely to variation in death rates, and the fittest individuals do not contribute their genomes to the eDNA pool. The results show that, even under this assumption, HGT can prevent the operation of Muller’s ratchet by causing a continual generation of the least-loaded class  from more-loaded classes. Moreover, the prevention of Muller’s ratchet by HGT is substantially more efficient in a subdivided population than in a panmictic population of an equal overall size, provided that the diffusion of eDNA is sufficiently rapid.We analyzed a simple evolutionary model of finite prokaryotic populations undergoing HGT. Our model is based on the infinite population model studied by Definitions for the symbols used in this article can be found in The model consists of two components: a population of prokaryotic cells and a pool of eDNA. The population undergoes a standard mutation-selection process (Wright-Fisher model) as well as HGT, through which cells acquire alleles randomly drawn from the eDNA pool. The eDNA pool gains input from the population due to natural cell death and also undergoes spontaneous decay. The details of each of these processes are described in the sections to follow.N. The genome was modeled as l loci (haploid), each representing a genomic segment that could be replaced by one recombination event i. This simplified model was adopted so that the effect of HGT on Muller’s ratchet could be assessed without confounding the additional effects caused by epistasis  (denoted as N) were varied to explore the behavior of the model.The population dynamics was modeled as the discrete-generation Wright-Fisher process with fixed population size s and sN . Thus, iU per generation. Beneficial mutations were ignored because we were concerned with the possible deterioration or maintenance of initially well-adapted genomes, for which the frequency of beneficial mutations is likely to be rare  recombination. Because homologous recombination is much more frequent than nonhomologous recombination .HGT generally can be categorized into homologous recombination and illegitimate .Prokaryotic cells can release their genomic DNA into the extracellular environment either actively by fratricide, suicide, or DNA secretion, or passively by natural death. However, the model assumed that genomic DNA was released only by natural cell death in order to consider the simplest and most unfavorable condition for the putative advantage of HGT  was jn is the number of cells with j mutations, and j mutations normalized by the fitness of the least-loaded class, i.e., mLLC is the number of mutations in the least-loaded class . The fraction (probability) of cells dying per unit time is D0)fi, where D0 is the probability that an individual of the least-loaded class dies). Thus, the normalized contribution to the eDNA pool by a cell with i mutations is D0 to zero maximizes the number of mutations in the genomes of dead cells , leading to the expression i shown previously. Note that assuming εi is more unfavorable to the hypothesized advantage of HGT than assuming i when The aforementioned assumption on εRedfield , which ci.e., how synchronous the genetic content of the eDNA pool is relative to that of the population  from locus i present in the eDNA pool. In each generation, deDNAije . Then, N cells were randomly chosen with replacement from the population of the current generation with the probability εi. All alleles in the genomes of the chosen cells were added to the eDNA pool, leading to the increase of ije.With the aforementioned assumptions, the dynamics of the eDNA pool was simulated as follows. The state of the eDNA pool was described by the vector Dpop and Ns/4 trials where Ns is the size of a subpopulation (Ns = N/16). Each subpopulation had its own pool of eDNA that exchanged alleles with the four nearest-neighbor pools via diffusion. The copy number of each allele diffusing out of a pool was defined as a fraction DeDNA/4 per direction per generation .The simplest version of the model assumed that the population is genetically isolated from other populations. However, to investigate the effect of genetic exchange between semi-isolated populations, we also considered an extended model in which the population was subdivided into 16 subpopulations of an equal size. The subpopulations were arranged in a two-dimensional square grid (4 × 4 subpopulations) with toroidal boundaries. Each subpopulation exchanged individuals with the four nearest-neighbor subpopulations via random migration. The number of migrants between each pair of neighboring subpopulations was drawn from the binomial distribution with the success probability The dynamics of the model in one generation was simulated in four steps, in the following order:1.The Wright-Fisher process. In this step, the population of the current generation died and was replaced by that of the next generation.2.Production and decay of the eDNA pools.3.Diffusion of both the microbial populations and eDNA.4.Mutation and HGT.k is a non-negative integer . Thus, it is beneficial to know through which of these processes the accumulation of mutations occurs in the model. Thus, we first analyzed the model in the absence of HGT . The results of the analysis essentially confirmed the conclusion of With HGT disabled, the model is known to have the following family of stationary distributions  integer . A finitutations . In genemLLC and the number of mutations fixed in the population (mfix) increase over time in a very similar fashion (mLLC − mfix) is at most one. Each increase in mLLC is followed by an increase in mfix with a delay of approximately a few thousand generations before the next increase occurs to mLLC  always precedes the fixation of a mutation , one but the least-loaded class becomes the new least-loaded class by definition, so that the value of l genotypes (one mutation in one of the l loci), whose frequencies roughly equal to each other  of the least-loaded class ;Extinction of the least-loaded class due to stochasticity  before the previous cycle undergoes the fixation of a mutation . Moreover, the dynamics of mfix also is delayed with respect to the decrease of i.e., step 2) is a sequential process, in that gene diversity is consecutively lost in different genotype classes distinguished by the number of mutations  far exceeds the number of segregating mutations in the least-loaded class (mLLC − mfix). This situation is in stark contrast with the result with a diploid, sexual model that assumes no recombination and weak dominance, which shows that the number of fixed mutations is much smaller than the number of segregating mutations . In this case, assuming a very large population, the average number of mutations in the eDNA pool per l loci  can be approximated by U/s + 1, where U/s is the average number of mutations in the population at the steady state with mLLC = 0 (File S1). Because the mean number of mutations in the eDNA pool is greater than that in the population, HGT on average introduces more deleterious mutations into the population than it removes and so decreases the steady-state population size of the least-loaded class.We next examined the effect of HGT on Muller’s ratchet. For simplicity, a rapid turnover of eDNA was assumed by setting mfix /Δt as a function of r (HGT rate) for different combinations of N and i.e., Δmfix /Δt = 0) if its frequency is sufficiently high .To assess the net effect of HGT on Muller’s ratchet, we measured the rate of mutation accumulation Δtly high . Moreovee of HGT  . The total population size N = n0 + n1 was constant. The value of n0 at time t + 1 was drawn from a binomial distribution with N trials and success probability p′ defined as follows:p = n0/N and t, s′ is the fitness effect of mutation, U is the mutation rate from n0 to n1 (back mutations ignored), r01 and r10 are the rates of HGT. For simplicity, HGT was assumed to convert n0 into n1 at rate r01 and, conversely, n1 into n0 at rate r10. The effect of eDNA was implicitly incorporated into the model by the choice of parameters r01 and r10 as follows. If r01 and r10 satisfy the following condition, HGT decreases the steady-state level of n0 compared with the steady-state level reached in the absence of HGT :n1 into n0, whereas the right-hand side is that of n0 into n1, when n0 and n1 are set to the steady-state level achieved in the absence of HGT).To understand why HGT can prevent Muller’s ratchet despite its average deleterious effect due to the high mutation load of eDNA that comes from dead cells, we considered the following simple Wright-Fisher model. The model assumed two populations: the population of the least-loaded class n0. The mean time to extinction of n0, which is a proxy for Δmfix/Δt in the full model, was measured as a function of r01 and r10 for different combinations of N and U′ values. The results show that HGT increases the mean time to extinction of n0 whether or not HGT decreases the steady state level of n0, as long as the per-generation production of the least-loaded class by HGT . We thus hypothesized that, in the full model, HGT prevents Muller’s ratchet most effectively when the probability of HGT producing the least-loaded class is maximized. This probability can be approximated by the probability P10 that an HGT event transforms one but the least-loaded class . P10 takes the maximum value when File S1). The non-monotonic dependency of P10 on l can be intuitively understood as follows: decreasing l can decrease P10 because it increases the probability that an allele randomly drawn from the eDNA pool contains a mutation that is not carried by the least-loaded class . However, increasing l also can decrease P10 because it decreases the probability that HGT occurs to the very locus in which one but the least-loaded class has the mutation not carried by the least-loaded class. Therefore, P10 takes the maximum value at an intermediate value of l. By contrast, the probability P01 that HGT introduces one or more mutations in the least-loaded class is File S1), which is a monotonically decreasing function of l because increasing l decreases the probability that an allele randomly drawn from the eDNA pool contains mutations. Thus, the aforementioned hypothesis can be reformulated as follows: Δmfix/Δt reaches the minimum value when l assumes the value mfix/Δt as a function of l for various combinations of N and mfix/Δt takes the minimum value when the value of l is on the same order of magnitude as Next, and sn¯0 . The resN = 106 and 105 Finally, the simplified model shows that  and 105 . The valTaken together, the consistency of the results indicates that the simplified model captures, at least qualitatively, the mechanism by which HGT prevents Muller’s ratchet in the full model. Namely, HGT can prevent Muller’s ratchet even if it decreases the steady-state population size of the least-loaded class because it can hinder the extinction of the least-loaded class by continually generating it from the more-loaded classes.i.e., once a good allele is lost), HGT cannot undo it because the only source of HGT in the model is eDNA derived from the members of the same population. However, slow turnover of eDNA can delay the loss of good alleles from the eDNA pool and thereby might help HGT prevent the accumulation of mutations.We further investigated the effect of the eDNA turnover rate on the ability of HGT to prevent Muller’s ratchet. As described previously, the accumulation of mutations in the model is initiated by a click of Muller’s ratchet followed by the fixation of a mutation. Once a mutation is fixed  by more than three orders of magnitude (deDNA < 10−3), a condition that appears to be unrealistic in natural environments  in locus k, and j from locus k in the eDNA pool. qeDNA indicates the potential of the eDNA pool to remove deleterious mutations in the genomes of the least-loaded class . qeDNA was measured in the absence of HGT for various values of deDNA. The results show that, in the slow ratchet regime (qeDNA closely follows that of deDNA ≥ 10−2) (deDNA ≤ 10−3), the decay of qeDNA lags behind the decline of qeDNA significantly. Because the decrease of deDNA must be <10−3 to cause any significant effect.To understand why such a severe condition applied, we measured the “quality” of eDNA defined as  ≥ 10−2) . When eDof HmLLC . This reqeDNA no more closely follows the dynamics of qeDNA to decrease to zero when eDNA turnover is rapid .The aforementioned argument might imply that the effect of slow eDNA turnover could be more significant if the population size of the least-loaded class is small. However, this turns out not to be the case. In the fast ratchet regime  in a model incorporating population subdivision . mfix measured within each subpopulation. For simplicity, all subpopulations were assumed to share a common eDNA pool . The results show that, in the absence of HGT (r = 0), the system becomes more prone to Muller’s ratchet , the dependency of Dpop is non-monotonic: the system initially becomes more prone to Muller’s ratchet as Dpop decreases, but becomes less so as Dpop decreases further, with the position of the maximum Dpop axis shifting as a function of r , in the fast ratchet regime (Dpop (≤10−5) than at greater values of Dpop (≥10−1) for which the system can be considered well-mixed (Dpop within the accuracy of the simulations (Dpop for other combinations of N and File S1). Taken together, these results indicate that the advantage of population subdivision can outweigh the associated disadvantage, provided that the frequency of HGT is sufficiently high, and subpopulations share a common eDNA pool.To address the aforementioned question, we measured ecreases . This ouion of r . The comll-mixed . In the ulations . In addiykix is the frequency of allele i in locus k in the least-loaded class of subpopulation y (the least-loaded class was defined separately for each subpopulation). The average gene diversity within subpopulations SH is defined as the average SyH over all subpopulations (weighted by the population size of the least-loaded class in each subpopulation). The average gene diversity in the entire population TH is defined similarly with ykxi replaced by the frequency of an allele in the least-loaded classes from all subpopulations combined together. The average gene diversity between subpopulations was defined as TH − SH . The time averages of TH and SH after or near saturation were obtained as a function of Dpop  and the “toxicity” of the eDNA pool defined as qeDNA and teDNA were calculated for each subpopulation and averaged over subpopulations using the population sizes of the least-loaded classes as weights). teDNA indicates the potential of the eDNA pool to introduce deleterious mutations in the genomes of the least-loaded class. Note that the difference teDNA − qeDNA is equal to the average number of mutations introduced  by one HGT event occurring to an individual of the least-loaded classes. Thus, − qeDNA can be interpreted as the contribution to the average number of mutations introduced by HGT by those HGT events that decrease the number of mutations, whereas teDNA as the contribution by those events that increase the number of mutations. Simulations show that the values of qeDNA and teDNA increase and then saturate over time except for Dpop = 0 . The time averages of qeDNA and teDNA after saturation were obtained as a function of Dpop in the absence of HGT . The result shows that population subdivision increases the number of mutations removed by an HGT event (qeDNA) as well as the number of mutations introduced by an HGT event (teDNA), thus confirming the expectation  number of mutations introduced by an HGT event (teDNA − qeDNA). In other words, population subdivision increases the conversion of the least-loaded class by HGT in the direction of both increasing and decreasing the number of mutations without changing the magnitude and direction of the net conversion. According to the simplified Wright-Fisher model described before, removal of mutations by HGT (r10) has a greater influence on the extinction of the least-loaded class than introduction of mutations by HGT (r01). Although r10 and r01 are concerned with HGT occurring in different genotypes, they are analogous to qeDNA and teDNA, respectively. This analogy points to the advantage of increasing qeDNA and teDNA with teDNA − qeDNA kept constant to prevent Muller’s ratchet.The increase in the number of segregating mutations is expected to drive an increase in the number of mutations that are introduced or removed by HGT events. To test this expectation, we measured the quality of the eDNA pool defined above (ectation . MoreoveDpop = 10−5 (subdivided population) and Dpop = 10−1 (well-mixed population) for various combinations of deDNA and DeDNA values. As expected, the results show that Dpop = 10−5 than for Dpop = 10−1 when deDNA is sufficiently small or DeDNA is sufficiently large .Whether population subdivision is advantageous or disadvantageous depends on the combination of parameters. To examine what appears to be the most important aspect of this parameter dependence, we next considered the finite diffusion of eDNA. To this end, the value of ly large . The valThe results presented here suggest that HGT can prevent the operation of Muller’s ratchet in prokaryotic populations, even if on average HGT introduces more deleterious mutations than it removes. The avoidance of Muller’s ratchet via transformation and recombination with eDNA might appear somewhat paradoxical because on average eDNA is expected to carry more deleterious mutations than the DNA in live prokaryotic cells. Indeed, it has been long recognized that “sex with dead cells” is a dubious proposition  is intuitively clear because it delays elimination of high-fitness alleles from the population and so increases the chance that these alleles offset Muller’s ratchet via HGT. However, the simulations show that, for this effect to be substantial, the characteristic lifetime of eDNA should exceed the generation time by orders of magnitude  subpopulations and let them “cross-reference” each other’s genetic information through recombination rather than collect all individuals in one population and thereby maximize the efficacy of natural selection. Note, however, that although population subdivision can be beneficial, it is not necessary for HGT to prevent Muller’s ratchet.i.e., biased associations on chromosomes between beneficial and deleterious alleles) which arises from genetic drift (the Hill-Robertson effect) or synergetic epistasis (TH > 0 and SH ≈ 0 when Dpop ≈ 0). In addition, the results show that the rate of mutation accumulation itself can be lower in a subdivided population than in an undivided population, despite the disadvantage of population subdivision due to enhanced drift. This conclusion does not immediately follow from the previous findings because the fact that negative linkage disequilibrium increases the benefit of recombination (compared with no recombination) does not necessarily mean that negative linkage disequilibrium is beneficial in preventing the accumulation of mutations in the presence of recombination.How do these findings relate to the previous population genetics studies on the advantage of recombination? Previous studies have shown that recombination is beneficial (compared with no recombination) when a population suffers from the reduced efficacy of natural selection because of negative linkage disequilibrium  display genetic divergence as great as that between strains sampled from different geographical areas  and high frequency of null alleles . However, bacteria are also known to go through frequent population bottlenecks under stress conditions  and indue.g., To conclude, the results of the modeling study described here indicate that HGT can prevent the operation of Muller’s ratchet, and this effect can be enhanced by population subdivision. Thus, through preventing the action of Muller’s ratchet, HGT could be a necessary condition for the long-term survival of prokaryotic populations. The benefits of HGT for prokaryotes certainly are not limited to the prevention of Muller’s ratchet and additionally include acquisition of novel genes and functions (see,


Aging results in a loss of sensory function, and the effects of hearing impairment can be especially devastating due to reduced communication ability. Older adults with hearing loss report that speech, especially in noisy backgrounds, is uncomfortably loud yet unclear. Hearing loss results in an unbalanced neural representation of speech: the slowly-varying envelope is enhanced, dominating representation in the auditory pathway and perceptual salience at the cost of the rapidly-varying fine structure. We hypothesized that older adults with hearing loss can be trained to compensate for these changes in central auditory processing through directed attention to behaviorally-relevant speech sounds. To that end, we evaluated the effects of auditory-cognitive training in older adults (ages 55–79) with normal hearing and hearing loss. After training, the auditory training group with hearing loss experienced a reduction in the neural representation of the speech envelope presented in noise, approaching levels observed in normal hearing older adults. No changes were noted in the control group. Importantly, changes in speech processing were accompanied by improvements in speech perception. Thus, central processing deficits associated with hearing loss may be partially remediated with training, resulting in real-life benefits for everyday communication. Hearing loss is associated with reduced quality of life in older adults, affecting social and emotional well-being  participants (ages 55–79) for a study examining training for speech-in-noise processing. Pure-tone audiometric thresholds were obtained bilaterally at octave intervals 0.125–8 kHz and at 3 and 6 kHz. No left/right asymmetries or interaural click-evoked auditory brainstem response Wave V differences (≥0.2 ms) were noted. No participants had a history of neurologic conditions and all participants had normal IQs  was presented in alternating polarities, allowing for the creation of responses comprised of both the sum and the difference of the two polarities  were entered as dependent variables in the MANOVA to represent the envelope, as these lower frequency spectral peaks dominate the envelope-following FFR. The H3–H6 amplitudes from the subtracted polarities (H3SUB–H6SUB) were entered as dependent variables to represent the TFS, which is more prominent in relatively higher frequencies in the FFR. A repeated measures ANOVA was used to compare envelope-dominated (F0ADD–H2ADD) and TFS-dominated (H3SUB–H6SUB) frequency encoding, QuickSIN SNR scores, and memory and attention measures before and after training.A Multivariate Analysis of Variance (MANOVA) was used to assess hearing group differences in the envelope and TFS. The F0ADD and H2ADD) than participants with normal hearing   in the older adults with hearing loss   = 4.351, p = 0.023], with a significant reduction in envelope encoding (F0ADD to H2ADD) occurring within the auditory training group  but not the active control group   = 0.803, p = 0.459] and no changes in either group   = 2.239, p = 0.117], there was a hearing group × test session interaction in the auditory training group  that was not present in the active control group   did not change for either hearing impaired or normal hearing participants of either training group   = 5.191, p = 0.027], with improvement noted in the auditory training group  but not in the active control group . This change was largely driven by the improvement in performance in the auditory training group with hearing loss ; the improvement in the normal-hearing group was not significant . Neither hearing group in the active control group changed with training . There was a decrease in the QuickSIN of 1.22 dB in the auditory training group with hearing loss—given four lists, this number is below the 1.9 dB necessary for a critical difference between conditions with an 95% confidence interval , there was a significant training group × test session interaction , with improvements in the auditory training group  but not the active control group . For memory, however, the changes were only significant in the group with normal hearing  but not in the group with hearing loss  and neither hearing group in the active control group changed .Similarly, for short-term memory there was a significant training group × test session interaction , with improvements in the auditory training group  but not the active control group . In this case, there were significant improvements for both the subgroups with normal hearing  and with hearing loss of the auditory training group . Again, there were no changes for members of either hearing subgroup of the active control group . See Figure auditory training and active control, groups.Finally, for attention, there was a significant training group × test session interaction [oup [F1, 5 = 17.94Here we show that the imbalance in neurophysiological processing of speech cues associated with hearing loss is malleable and reversible with training in older adults. The results are summarized as follows: first, compared to normal hearing individuals, older adults with hearing loss have excessively large envelope encoding of speech in noise. Second, training that targets the CV transition reduces envelope representation in individuals with hearing loss to levels in line with those of normal-hearing individuals. Finally, the training-induced changes in neurophysiology are accompanied by gains in speech-in-noise perception, attention, and short-term memory, although it should be noted that the change in speech-in-noise perception was modest, and would not be considered clinically significant (Killion et al., Our results confirm previous findings of exaggerated representation of envelope cues in animal and human models of sensorineural hearing loss (Kale and Heinz, 0 is correlated with behavioral pitch discrimination, (Krishnan et al., The results of our study contrast with those of two previous studies that found training-induced increases in envelope coding in normal-hearing young adults using different types of training: pitch discrimination training (Carcagno and Plack, We propose, therefore, that the training effects in this study were influenced by neural mechanisms specific to older adults with hearing loss. Both aging (Turner et al., Our training was designed to strengthen sensory function through attention to meaningful sound; specifically, focusing attention on CV transitions in speech may drive top-down modulation, which occurred in five of the six training modules. Animal models have demonstrated that directed attention to behaviorally-relevant stimuli is necessary for neural and behavioral plasticity (Fritz et al., A number of questions remain unanswered. We did not include anyone in our study who wore hearing aids, because hearing aids themselves may induce plasticity in auditory processing (Munro et al., Finally, although neither envelope nor TFS representation changed in the normal hearing group, this group did experience changes in attention and short-term memory. Therefore, we assume the normal-hearing participants experienced training-induced biological changes that were not observed using the current envelope/TFS technique. The lack of observed improvement in memory in the group with hearing loss may be due to the auditory nature of our assessment measure. Although the presentation level was adjusted to a comfortable volume for each participant, it may be that peripheral hearing loss limited performance, even in the post-training session, given the known effects of hearing loss on verbal short-term memory (McCoy et al., These results have implications for management of hearing loss problems in older adults. Although provision of audibility is a necessary foundation for the treatment of hearing difficulties, we assert that auditory training is just as important. The combination of amplification and auditory training may lead to improved speech clarity in noise without distortion from, overamplification.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Tenebrio molitor (L.) (Coleoptera: Tenebrionidae) larvae as bait. Overall, of the larvae exposed to soil, 171 (20%) hosted Beauveria bassiana  Vuillemin , 25 (3%) hosted Metarhizium anisopliae (Metschnikoff) Sorokin  and 1 (0.1%) hosted lsaria (=Paecilomyces) sp. . B. bassiana was significantly more frequent on larvae exposed to oak forest soil. M. anisopliae was significantly more frequent on larvae exposed to agricultural soil. From the infected bait insects, 93 isolates of B. bassiana and 24 isolates of M. anisopliae were obtained. Strains were tested for their infectivity against Cuban laurel thrips, Gynaikothrips uzeli Zimmerman (Thysanoptera: Phlaeothripidae) and the greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae). B. bassiana isolates caused the highest mortality on thrips ; both fungal species caused similarly high mortality levels against whiteflies (75%) after 6 days. Large amounts of germplasm of entomopathogenic fungi, fundamentally B. bassiana and M. anisopliae, exist in the habitats sampled; pathogenicity varied among strains, and some strains possessed significant virulence. Soils in these habitats are reservoirs of diverse strains with potential for use in biocontrol.Entomopathogenic fungi were collected from soil in four adjacent habitats  in Saltillo, México using the insect bait method with  Beauveria, Conidiobolus, Metarhizium and Isaria (=Paecilomyces) are commonly found in soil  Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin  are natural enemies of a wide range of insects and both fungi have a cosmopolitan distribution , Isaria fumosorosea Wize (=Paecilomyces fumosoroseus) and B. bassiana . These entomopathogenic fungi can suppress and provide good control of pests in greenhouse and field crops  bean leaf foliage treated with conidia.Much effort has been put into research on the development of ld crops  and seveld crops  showed tIt is increasingly recognized that the biodiversity of agroecosystems delivers significant services, such as biological control of pests, to agricultural production . The conin situ.Projects in biological control of insects with fungi must consider the availability and acquisition cost of virulent strains from germplasm collections, and the regulation and legal restrictions to the transport and release of exotic entomopathogenic fungal strains outdoors. In this respect, the deployment ofthese fungi in agriculture is not straightforward, especially for developing countries. In order to circumvent these restrictions, it is important to explore local environments to detect promising, virulent fungal strains The objectives of the present study were to explore diverse habitats as potential sources of local strains of entomopathogenic fungi virulent against important pests. Specifically, this study aims to explore the distribution of entomopathogenic fungi in soils from four adjacent habitats in the Chihuahuan desert of Saltillo, México, and to evaluate the virulence of some of these strains against selected insect hosts: whiteflies and thrips.The study was conducted at localities in the municipality of Saltillo, Coahuila, Mexico. This area is located in the southeastern state of Coahuila, centered at 25°31′ N, 101°37′ W, 1600 m above sea level (MASL). Soil classification follows that by the Government of Saltillo . Soil saQuercus taeda Liebmann and Quercus saltillensis (Trelease)  at 25° 21′ 12.85″ N, 100° 59′ 39.11″ W, 1962 MASL; the soil type was regosol.1. Forest of the endemic oaks, Capsicum anuum L.), tomato (Solanum lycopersicon L.); also cabbage (Brassica oleracea var. viridis L.), prickly pear (Opuntia ficus-indica (L.) Mill.), wheat (Triticum aestivum L.) and corn (Zea mays L.)) located at 25° 21′ 24.61″ N, 101° 02′ 16.25″ W, 1749 MASL; the soil type was xerosol.2. Agricultural soil (plots of pepper (Larrea tridentata (Sessé & Mociño ex DC.) Coville) , lechuguilla (Agave lechuguilla Torr). , and catclaw (Acacia spp.)  located at 25° 20′ 53.56″ N, 101° 01′ 11″ W, 1834 MASL; the soil type was litosol.3. Chaparral of creosote bush   located at 25° 20′ 15.87″ N, 101° 01′ 32.90″ W, 1870 MASL; the soil type was litosol (2008).4. Exotic pine reforestation (Tenebrio molitor L. (Coleoptera: Tenebrionidae) were used. Larvae were pooled from the laboratory colony and larvae purchased at pet stores. Extensive observations (previous to and concurrent with these tests) of these larvae incubated in moist chambers indicated that they were free of fungal entomopathogens.At each of the four habitats, 14 locations were randomly chosen including a minimum distance of 10 m between them. Five samples were taken around each location producing 70 soil samples/habitat and a total of 280 soil samples. Using hand shovels, soil samples (about 200 g) were collected at a depth of at least 5 cm until filling >90% of 500 ml plastic cups. Shovels were cleaned with 70% ethanol between points. In the laboratory 30 ml of nonchlorinated, purified water was added to soil samples. The samples were left standing for 30 minutes to let the soil sample absorb the water. After 30 minutes the insect baits (three larvae) were placed in the cups. Last and penultimate larval instars of the mealworm, Galleria bait method  with high moisture provided by a moist cotton ball and incubated for up to 15 days at room temperature.Isolation of the entomopathogenic fungi was achieved using the t method  modifiedwww.bd.com). Isolates growing on PDAY were identified microscopically  on bait insects was transferred with a sterile microbiology loop to agar media (potato dextrose agar plates plus 1% yeast extract)  (Hemiptera: Aleyrodidae) were collected from mallow, Malva sylvestris (L.) , false dandelion Pyrrohopappus sp. , and tomato at greenhouses in the Universidad Autónoma Agraria Antonio Narro (UAAAN). Tomato plants were grown for whitefly production in the greenhouse at 20° C ± 2° C. Cuban laurel thrips, Gynaikothrips uzeli Zimmerman (Thysanoptera: Phlaeothripidae), adults were collected from their host plant, Ficus benjamina (L.)  in the cities of Matamoros, Tamaulipas, and Monterrey, Nuevo León.Whiteflies, B. bassiana isolates were B18C2, C14D, D40E1, B8C1, C2B1, C32B1, D17B1, and D20E. The M. anisopliae isolates were B62B2, D5E1, and D5E2. Different fungi were used for the two insect species based solely on availability of cultures in the laboratory. Conidia obtained on solid medium were removed with a sterile spatula, and suspended in sterile purified drinking water with Tween 80 at 0.02%. The suspension was filtered through three layers of t-shirt cotton cloth and adjusted to a concentration of 1×107 conidia/ml, using a Neubauer haemocytometer. Control insects were immersed in Tween 80 at 0.02% in water. For bioassays, insects were immersed in spore suspensions (see below).All the isolates were cultured on PDAY, with no more than two transfers from the insect host at 25° C ± 1 for 15 days and a 12 h photophase under diffuse fluorescent light. Isolates showing clearly abundant sporulation on agar plates were selected for bioassays. Cultures were less than 60 days old when used. The It was not possible to perform (viability) germination test on the conidial suspensions used in these experiments. However, fungal suspensions prepared from cultures as described consistently have at least 50% germination and usually >90%  and three M. anisopliae isolates . Each isolate (treatment) consisted of four repetitions and each repetition included 65 second-instar nymphs. Tomato leaves infested with whitefly nymphs were immersed for 5 seconds in suspensions of fungal spores and excess liquid was drained off. Control insects were immersed in Tween 80 at 0.02% in water, without spores. Inoculated nymphs on excised leaves were placed in Petri dishes with a moist cotton ball. Mortality of insects was assessed at 3, 5 and 6 days after inoculation, under the dissecting microscope.Nymphs of B. bassiana can show different responses. They were identified by: a dehydrated, shriveled aspect with sparse mycelium colonization; abundant mycelium colonization; and/or red pigments produced by the fungal mycelium  were used. Due to lack of insects M. anisopliae was not tested against thrips. Each treatment (isolate) was replicated four times; each replicate included 20 Cuban laurel thrips adults. Adult thrips were picked up with a soft hairbrush and placed in a fungal suspension for less than 5 seconds, then quickly transferred with the brush (blotting excess free water first from insects) to 50 ml cups with a moist cotton ball. Each cup held 20 thrips. Insect mortality was assessed 3, 5, and 6 days after inoculation, under the dissecting microscope.Six 2 test, using the number of infected insects in the agricultural  habitat as baseline for comparisons with the habitats sampled (www.statsoft.com).The number of infected insects was compared among habitats by the χ sampled . To asse sampled . PercentB. bassiana and 25 isolates of M. anisopliae were isolated on potato dextrose agar (PDA) (each isolate from one infected insect).From the soil samples, 93 isolates of B. bassiana and M. anisopliae in Saltillo, Coahuila, Mexico, confirms their reported widespread distribution in soils worldwide  of the 840 incubated larvae; B. bassiana was isolated from 171 (20.4%) of larvae, and M. anisopliae from 25 (3%) (The entomopathogenic fungi  25 (3%) .2 = 63.27, p< 0.001). Most of the infected insects were obtained from oak forest soil (51.4%), followed by chaparral (18.0%), agricultural soil (16.2%) and pine reforestation (7.1%) . B. bassiana was significantly more abundant than M. anisopliae in all habitats (p<0.001) with the exception of agricultural plots, where there were not significant differences in number among both fungi .There were significant differences in frequency of fungi (number of infected insects) among habitats (χn (7.1%) . Individth fungi . Across B. bassiana isolates, isolate B18C2 caused 50% mortality (p<0.01) and 76% mortality after 5 and 6 days respectively (p<0.0001) . Quesada et al. ; they found that all their isolates were pathogenic for two whitefly species (Bemisia tabaci and T. vaporariorum). In their work, mortality rates (8 days afterinoculation) reached up to 85%.In the bioassays against whitefly nymphs, there were essentially no significant differences among the fungi across isolates and species . Out of <0.0001) . M. anisa et al.  used 25 B. bassiana  (p<0.01). After 5 days, isolate B18C2 (the most active) caused 62.5% mortality (p<0.005); after 6 days, it caused 81.3% mortality (p<0.001); both values were significantly different from those of most isolates , 60% mortality by 5 days (p<0.01) and 70% mortality by 6 days (p<0.001).On the other hand, there were rather large, significant differences in the mortality of thrips exposed to different strains of bassiana . Out of isolates . The secB. bassiana and M. anisopliae isolates did not cause significant mortality, at least initially; the relative activity of the isolates and the ranking of the mortality caused by them changed over time after inoculation in bioassays.Some B. bassiana and M. anisopliae obtained from the sampled habitats (B. bassiana against thrips. M. anisopliae strains were rather homogeneous in their killing effect and there were not great differences on virulence against whitefly (T. vaporariorum) among isolates of B. bassiana and M. anisopliae , and two species of hyperparasitic fungi including 3 specimens of Syspastospora sp. and 1 specimen of Calcarisporium sp., both parasitizing B. bassiana. Two larvae infected with the entomopathogenic nematode Steinernema sp. were also found.Not shown in the tables, but also recovered from larvae exposed in the oak forest were one isolate of the entomopathogenic fungus, B. bassiana and M. anisopliae often occurred in the soil of natural habitats and their presence was not significantly different between regions. However, the fact that B. bassiana is more frequent in natural habitats and M. anisopliae is more common in soils from cultivated habitats has been observed in several previous studies  areas puts B. bassiana at a disadvantage in those soils. In contrast, M. anisopliae conidia are capable of longer-term persistence in the absence of arthropod hosts and have a higher survival in the soil than B. bassiana .The presence of diverse fungal entomopathogens has been documented in tropical and temperate forests of Mexico and worldwide ; these fa priori reason to expect these isolates to show specific activity towards the tested insects. The differences in virulence observed among strains make it essential to evaluate fungal isolates before their use in biological control projects (These results show that considerable quantities of germplasm (strains) of entomopathogenic fungi exist in the Mexican habitats sampled, especially natural ones. This germplasm  is accessible for use in biological control of insect pests, locally or regionally. The fungi collected in this work include isolates with significant pathogenicity against the important pests tested (Hemiptera and Thysanoptera), and possibly against other insect pests as well, since there is no projects .In summary, the biodiversity, biocontrol, and natural products aspects make persuasive arguments supporting conservation of natural ecosystems and of biological resources like these fungi.