Multilinguals have to control their languages constantly to produce accurate verbal output. They have to inhibit possible lexical competitors not only from the target language, but also from non-target languages. Bilinguals’ training in inhibiting incongruent or irrelevant information has been used to endorse the so-called bilingual advantage in executive functions, assuming a transfer effect from language inhibition to domain-general inhibitory skills. Recent studies have suggested that language control may rely on language-specific inhibitory control mechanisms. In the present study, unbalanced highly proficient bilinguals completed a rapid naming multi-inhibitory task in two languages. The task assessed three types of inhibitory processes: inhibition of the non-target language, inhibition of lexical competitors, and inhibition of erroneous auditory feedback. The results showed an interaction between lexical competition and erroneous auditory feedback, but no interactions with the inhibition of the non-target language. The results suggested that different subcomponents of language inhibition are involved during bilingual language production. Multilinguals have to manage different languages to control verbal speech on an everyday basis. They have to select the language that is needed at every specific moment and suppress interference from the situationally irrelevant languages. This mechanism is commonly referred to as language control and it has been associated with the use of a complex set of inhibitory control mechanisms see . BroadlyResearch has shown that language inhibition may be required during bilingual speech production e.g.,  and compFurthermore, even within bilingual speech production, multiple types of linguistic conflict may be present that may be governed by different forms of inhibitory control mechanisms. The current study therefore assessed whether different types of interfering linguistic information are suppressed through a general inhibitory control mechanism or distinct mechanisms. To this end, we asked a group of highly proficient yet unbalanced Spanish-Basque bilinguals to complete a verbal production task either in their native language (Spanish) or in their non-native language (Basque), while parametrically manipulating other additional inhibitory demands . While these three manipulations differ in many ways, they share one important component: the presence of interfering information that needs to be suppressed in order to correctly complete the task. In the current study, we explored the possible additive or interactive nature of the different types of interfering information in the context of a Rapid Automatized Naming (RAN) task see  in whichnon-target language inhibition.The first task manipulation concerned the use of the first or second language. It is widely assumed that multilingual speakers have to inhibit phonological and lexical competitors from the non-target language during speech production, so that speaking in one language requires lexical inhibition. According to Levelt’s model of word production , a technique that was initially developed to explore the importance of auditory feedback in speech production. The DAF is a technique in which speakers hear their own speech production through headphones, but with a short and artificially inserted lag between the actual production and its reproduction. Speech is normally inhibited using auditory feedback inhibition, which occurs online, with a very short delay. When the perception of speech is delayed – in this case artificially by playing back the sound with a delay – this auditory feedback inhibition becomes more costly and less efficient. Therefore, the auditory perceptual lag disturbs speech production, leading to disfluent utterances. The DAF technique facilitates understanding how production is achieved by exploring erroneous Some previous studies have suggested a relationship between auditory feedback and domain-general control processes. Adaptation to altered auditory feedback can be modulated by attentional load e.g.,  and netwThe precise way in which language proficiency impacts speech production under DAF is still a matter of debate. It is assumed that until a certain proficiency level is acquired in a non-native language (L2), the impact of the DAF technique is larger in that language than in the native one (L1). Several studies have shown an interaction between language dominance and erroneous auditory feedback inhibition, reporting longer speech latencies in L2 than in L1 e.g., . These rIn the current study, DAF was used to assess whether the demands of inhibiting the delayed feedback could cause a processing bottleneck for other inhibitory demands during speech production in the context of a RAN task. The RAN task was originally designed to assess reading competence by naming pictures as fast as possible see . Thus, tWe created a multilingual RAN-like picture naming task where three types of language inhibition mechanisms could be required across conditions: non-target language inhibition, lexical inhibition of the preponderant responses and the competitors, and erroneous auditory feedback inhibition. We conceived an experimental design that allowed for observing how the system performs as a whole and whether these three variants of inhibitory processes at play during multilinguals’ speech production interact with each other. Firstly, highly proficient bilingual participants were asked to name the pictures of the RAN either in their native language (Spanish) or in their non-native language (Basque), thus requiring non-target language inhibition to complete the different trials of the RAN scenario.Furthermore, an additional artificial inhibitory demand was included in the experimental design, aimed at mimicking some of the lexical inhibitory processes that need to be carried out by multilinguals while producing speech. Multilinguals and language learners have to inhibit preponderant words from the native language that may interfere with the correct utterance in the non-native language . This is an everyday, constant demand for bilinguals, and in the context of the current experiment, we artificially created a similar demand with the aim of recreating a natural aspect of bilinguals’ day-to-day interactions. We asked participants to substitute the name of certain pictures for that of some digits  in increasing order of difficulty, parametrically varying the number of to-be-replaced elements. Finally, auditory feedback demands were manipulated by including trials in which participants perceived their own speech without or with an artificial delay (DAF).Thus, the aim of this study was to investigate how language inhibition works in multilingual speakers, particularly assessing whether distinct linguistic inhibitory processes that are at play during speech production interact with each other. By means of our multi-layered picture naming RAN-like task, we intended to tax the system and to evoke the use of large amounts of inhibitory resources, highlighting their independent effects and the interdependent interactions between them. The results of the current study will help us elucidating the extent to which language control mechanisms in multilingual speech production rely on a general mechanism of language control, or alternatively, on different subcomponents of language control. If the three types of inhibitory mechanisms interact with each other, this would suggest that language control relies at least partly on a shared inhibitory control mechanism. On the other hand, and in line with Sternberg’s Additive Factors Method M age = 23 years, SD = 3 years; 33 females) were native Spanish speakers, who acquired Basque early in life . Three participants were excluded from analyses due to a high error rate (more than 35% errors in each matrix). All participants  were used to create different matrices for the rapid naming task. The images were taken from the MultiPic database . While nThe structure of the experiment and the order of conditions were as follows. Each participant completed eight blocks. Four blocks were completed in Spanish and four in Basque. Furthermore, two of the four blocks were completed without DAF and the other two with DAF  for each language. Each semantic category occurred once in each of these conditions, so that each participant completed the same semantic category twice in each language, once with and once without DAF . The same software was also used to collect the verbal responses, which were recorded from the onset of the presentation of each matrix to the moment in which the participant pressed the space bar to indicate that she had finished naming the items. Participants wore a headset throughout the experiment and they were instructed to name the items of each matrix as if they were reading a text , as fast as they could and trying not to make errors. Delayed auditory feedback time was set to 200 ms for the DAF condition in accordance with previous studies  and to 0Each matrix in each block was preceded by a screen specifying the instructions and conditions about the auditory feedback (delayed vs. immediate), the assigned language (L1 vs. L2), and the number of lexical substitutions that they had to do . Participants were instructed whether there would be a delay in auditory feedback to avoid the disruptive effect of the delay being larger at the beginning of the task due it being a surprise. Participants were familiarized with the pictures’ names before performing the rapid naming task in the two languages and they practiced the lexical substitution with fruit matrices before the experiment started.p-value can only say that there was no evidence for an effect, but it does not support the absence of an effect. By reporting Bayes Factors (BF), we show the ratio of the probability that the data were observed under the null hypothesis  vs. the probability of observing the data under the alternative hypothesis . For instance, a BF01 of 5 indicates that the observed data were five times more likely to have occurred under the null than alternative hypothesis. Bayesian analyses were conducted with JASP 0.8.5 using Bayesian repeated measures ANOVA with 100,000 samples. As we were interested in the interactions between the three different manipulations, we compared the model with the three main effects of Language, Auditory Feedback, and Lexical Replacements to a model including those three main effects plus, (a) the interaction between Language and Auditory Feedback; (b) the interaction between Language and Lexical replacements; and (c) the interaction between Auditory Feedback and Lexical Replacements.Data were analyzed in two ways. Firstly, we performed a three way ANOVA testing the effects of Language (L1| L2), Auditory Feedback (immediate| delayed), and Lexical Replacements  on the naming latencies. As we aimed to examine whether different types of linguistic conflict interacted or not, we furthermore analyzed the data using Bayesian analysis. In the case of a null effect, a M = 1.05 errors per matrix, SD = 1.30; range: 0.17–2.17). Besides, it is likely that any effects of production errors are also observable in the naming latencies since participants corrected themselves when making a mistake, thus requiring more time to complete the matrix.We exclusively focused on the naming latencies given that the average number of errors was fairly low  than blocks completed in Spanish , F = 9.30, p < 0.004, 1. Regarding the effect of Auditory Feedback, blocks that had to be named under the DAF condition required more time  than blocks that did not include any DAF  = 57.26, p < 0.001, F = 38.73, p < 0.001, M = 21.88 s, SD = 4.60 to trials requiring 3 substitutions   = 3.67, p = 0.014, t(52) = 5.28, p < 0.001, Cohen’s d = 0.726; 1 substitution: t(52) = 6.95, p < 0.001, Cohen’s d = 0.956; 2 substitutions: t(52) = 6.76, p < 0.001, Cohen’s d = 0.929; 3 substitutions: t(52) = 2.83, p < 0.006, Cohen’s d = 0.390). Importantly, there was no interaction between Language and Auditory Feedback, F = 0.20, p = 0.653, F = 1.32, p = 0.270, F = 0.41, p = 0.750, The three main effects were significant. For the effect of Language, blocks that were named in Basque  yielded longer reaction times (01 was 37.85 (± 2.65%), suggesting that model without an interaction fits the data around 38 times better than a model with this interaction term included. Similarly, for the model including the Language × Auditory Feedback interaction, the BF01 was 8.76 (± 1.71%), suggesting that the model without such interaction accounts for the data nearly 9 times better than the model with the interaction. Thus, both analyses suggested that there was no interaction between Language and Auditory Feedback or Lexical Replacements. Regarding the interaction between Lexical Replacements and Auditory Feedback, while the p-value showed a significant interaction, the Bayes Factor analysis showed some evidence against an interaction with a BF01 of 4.25 (± 4.18%).We then conducted Bayesian analyses in which we compared models including the main effects only to the model including the main effects plus the interaction of interest. For the model including the interaction between Language and Lexical Replacements, the BFThe aim of the study was to explore how distinct types of language inhibition that are typically needed by multilingual speakers to efficiently produce speech  interact with each other during completion of a rapid naming task. Our main interest was to examine whether these different processes rely on the same linguistic inhibitory system or whether, alternatively, several types of different and independent linguistic inhibitory mechanisms underlie each of the distinct processes. To this end, we designed a highly demanding rapid naming task to allow us to observe how the inhibitory system(s) work(s) while multitasking.In accordance with previous findings and as predicted, our results revealed main effects in all the three variables of interest. Firstly, participants exhibited longer naming times overall in L2 (Basque) as compared to L1 (Spanish), in line with the bulk of preceding evidence at this regard e.g., . Second,against this interaction). The negative impact of the DAF partially decreased as the lexical competition increased , potentially suggesting that both may tap into similar inhibitory resources. This interaction could also be understood in terms of a plateau effect in the three-replacement condition when the maximal taxation of cognitive resources is reached. However, none of these effects significantly interacted with the language at use (native vs. non-native), and the relative independence of this effect speaks for a certain degree of separation or autonomy of the different types of inhibitory mechanisms that multilinguals may use and require.Interestingly, only two of the constructs associated with different inhibitory demands interacted with each other in the classic factorial analysis of variance  did not interact with either lexical competition or auditory feedback alteration. This suggests that inhibitory mechanisms used to suppress the non-target language are not identical to the inhibition mechanisms used to accomplish suppression of erroneous auditory feedback or lexical competitors. The latter manipulation may also have introduced an increase in working memory load, which could explain the main effect of lexical competitors that was observed. However, beyond the working memory component related to remembering which replacement to use, the task also required inhibition of the word that could not be used . Thus, if the inhibitory component of lexical competition is related to the type of control used in language inhibition, we should have observed an interaction. Instead, and in line with Sternberg’s Additive Factors Method Previous studies have already suggested that language inhibition may be based on its own specific and independent resources see . Our resOn the other hand, our data are less compatible with previous studies suggesting that language inhibition is at least partly related to the inhibition mechanisms used in other  tasks e.g., . HoweverThe absence of an interaction between inhibition of the delayed, erroneous auditory feedback and inhibition of the non-target language is line with a previous study  showing supporting rather than unequivocally implying distinct inhibitory control processes.This study suggests that multilinguals do not rely on one unique inhibitory system to produce speech in one of the known languages, but rather that they rely on a set of different mechanisms that operate separately. As said, the interpretation that additive factors can reflect independent processes is in line with Sternberg’s Additive Factors Method The three manipulations used in our study were not only tapping into inhibitory control, but are also likely to recruit other forms of cognitive control . While it is perfectly possible that the three manipulations were different enough not to recruit a shared inhibitory control mechanism, it should be considered that the three of them required the inhibition of interfering information . We believe that if different types of inhibitory control are governed by a common inhibitory control mechanism, these three specific forms of resistance to linguistic interference would be expected to tap into this general mechanism.Our results open up the possibility to think about how the inhibitory system is further divided into domain-specific sub-mechanisms that do not necessarily work at par. These distinct mechanisms should be explored in more detail in order to better understand how they work and relate to each other in an interactive fashion, and specifically, how they are used by multilinguals to efficiently face the highly demanding communicative scenarios they encounter in their daily life. Furthermore, brain imaging techniques could be used to shed more light on the possible differences between or overlap in the spatial and temporal characteristics of different types of inhibitory control. We tentatively propose that the debate on the generality or specificity of the language-related inhibitory mechanisms should be moved to a new arena, leaving aside the simplistic dichotomy between language-specific inhibition and domain-general inhibition. The current study suggests that the different inhibitory processes that mediate multilingual speech production are somewhat independent from each other, probably referring to diverse inhibitory modules. Some of these mechanisms, such as the inhibitory control of erroneous auditory feedback and the inhibition of competing lexical representations, could tap into similar inhibitory resources. However, other mechanisms, such as the set of inhibitory processes applied to control for the interference from the non-target language, seem to be independent. Together, these results make us think of a series of inhibitory modules that go beyond a unitary conception of language-specific inhibitory mechanisms.In sum, these findings demonstrate that some of the mechanisms related to language control require allocating particular and independent inhibitory resources that remain unaffected by the concurrent requirement of other inhibitory mechanisms. This suggests that multilingual language control builds on a set of specific inhibitory mechanisms that are not shared by other cognitive or even other language processes. Future studies will help us elucidating the precise nature and role of these seemingly independent inhibitory processes, and the way in which they are acquired, developed and trained in multilingual contexts.MB, CM, and JD designed the study. MB and JD created the materials and experimental protocols. MB collected the data, analyzed the data under the supervision of all the authors, and drafted the manuscript. All authors provided critical comments on the manuscript before submission.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.


Solanum tuberosum L.) tuber that encompasses multiple differentially phosphorylated isoforms. In this study, temporal changes in the phosphorylation status of patatin isoforms and their involvement in patatin mobilization are investigated using phosphoproteomic methods based on targeted two-dimensional electrophoresis (2-DE). High-resolution 2-DE profiles of patatin isoforms were obtained in four sequential tuber life cycle stages of Kennebec cultivar: endodormancy, bud break, sprouting and plant growth. In-gel multiplex identification of phosphorylated isoforms with Pro-Q Diamond phosphoprotein-specific stain revealed an increase in the number of phosphorylated isoforms after the tuber endodormancy stage. In addition, we found that the phosphorylation status of patatin isoforms significantly changed throughout the tuber life cycle (P < 0.05) using the chemical method of protein dephosphorylation with hydrogen fluoride-pyridine (HF-P) coupled to 2-DE. More specifically, patatin phosphorylation increased by 32% from endodormancy to the tuber sprouting stage and subsequently decreased together with patatin degradation. Patatin isoforms were not randomly mobilized because highly phosphorylated Kuras-isoforms were preferably degraded in comparison to less phosphorylated non-Kuras isoforms. These results lead us to conclude that patatin is mobilized by a mechanism dependent on the phosphorylation status of specific isoforms.The role of the protein phosphorylation mechanism in the mobilization of vegetative storage proteins (VSPs) is totally unknown. Patatin is the major VSP of the potato ( Arabidopsis thaliana suggest that a complex crosstalk of protein kinases, phosphatases and phytohormones are mainly involved in the regulatory networks modulating the phosphorylation status of SSPs  × 100, in which X and Y are the 2-DE spot volumes from untreated and treated tuber protein extracts with HF-P, respectively [The phosphorylation rate for each protein spot was quantified by the coefficient ectively . Non-parectively . BootstrIn this study, we have provided, for the first time, confident evidence of qualitative and quantitative temporal changes in the phosphorylation status of patatin isoforms. It is also the first study on this subject in VSPs. Our data revealed that isoforms with major extent of phosphorylation accumulated progressively from endodormancy up to reaching the tuber sprouting stage. The joint analysis of previously published proteomic studies in distinct SSPs showed similar dynamic temporal patterns. These temporal patterns acquired their full meaning when our observations showed that highly phosphorylated isoforms were preferably degraded immediately after the onset of tuber sprouting. Similar results have been reported in the mobilization of the major common bean storage protein. Therefore, the evidence available suggests that degradation of storage proteins dependent on the status of phosphorylation of specific isoforms might be a general mobilization mechanism involving both VSPs and SSPs. Further research is clearly required to assess the signaling networks that trigger and regulate these complex processes.


Bacterial production (BP) of 0.03–0.6 μg C L−1 h−1 was observed in surface ice and increased in concert with glacier algal abundances, indicating that heterotrophic bacteria consume algal-derived dissolved organic carbon. However, BP remained at least 28 times lower than net primary production, indicating inefficient carbon cycling by heterotrophic bacteria and net accumulation of carbon in surface ice throughout the ablation season. Across the supraglacial environment, cryoconite sediment BP was at least four times greater than surface ice, confirming that cryoconite holes are the true “hot spots” of heterotrophic bacterial activity.Current research into bacterial dynamics on the Greenland Ice Sheet (GrIS) is biased toward cryoconite holes, despite this habitat covering less than 8% of the ablation (melt) zone surface. In contrast, the expansive surface ice, which supports wide-spread Streptophyte micro-algal blooms thought to enhance surface melt, has been relatively neglected. This study aims to understand variability in bacterial abundance and production across an ablation season on the GrIS, in relation to micro-algal bloom dynamics. Bacterial abundance reached 3.3 ± 0.3 × 10 This allowed us the capture bacterial dynamics at different growth phases of the algal bloom during the relatively short ablation season . All samn = 3 snow pits were dug at the primary ice camp location using a clean metal shovel, and discrete snow pack layers  transferred into sterile Whirl-Pak bags. During the early ablation season, i.e., shortly after the retreat of the snowline (see n = 2), were sampled using a KOVACS ice corer . Ice cores were sectioned using a clean hand saw into visually discrete layers . In contrast, during the middle and late ablation periods, surface ice was categorized as following 2 sections were categorized as containing a low, medium, or high coverage of glacier algae  were counted. For all snow and ice samples, enumeration of glacier algal abundance was performed using a Fuchs-Rosenthal hemocytometer  on a Leica DM 2000 epifluorescence microscope.To enumerate bacterial abundance, 15 ml subsamples were taken from all melted snow and ice samples following homogenization and fixed with 25% glutaraldehyde at 2% final concentration. For cryoconite sediment, a small subsample was removed and placed with 1 ml of Milli-Q water into a 2 ml Eppendorf tube, and fixed with glutaraldehyde as above. All fixed snow, ice, and cryoconite sediment samples were transported back to the University of Bristol under chilled conditions. Bacterial abundance was determined from 1 ml of snow and ice samples or approximately 100 mg (wet mass) of cryoconite sediment by epifluorescence microscopy following staining with 4′, 6-diamidino-2-phenylindole  at a final concentration of 10 μg ml−1 . Prior t−1 . The sta3H-leucine using the microcentrifuge method .Bacterial production within all snow, ice, and cryoconite sediment samples was estimated by the incorporation of e method . For snog for 20 min and the supernatant aspirated. Each sample was washed twice, first with 1.5 ml of 100% TCA followed by 1.5 ml of 80% ethanol. After washing, samples were left for 24 h to allow the ethanol to evaporate. Cryoconite sediment samples were weighed to determine the dry weight of the sediment used in the incubation for normalization of rates. All samples were analyzed by liquid scintillation counting . Disintegrations per minute (DPM) were corrected using a linear relationship between sediment weight of cryoconite and the DPM.Samples were transported back to the University of Bristol and processed after −1) to area (m−2) after 2 of surface ice sampled. Similarly, bacterial production in cryoconite sediment (g−1) was converted to units of area (m−2) using mean cryoconite mass across a square meter (255 g m−2) from a study site at a similar distance from the ice margin as our primary field camp, reported by To estimate bacterial production, the DPM from killed controls were subtracted from live samples and converted to bacterial production (BP) after Post Hoc Tukey HSD was performed on all significant ANOVA analyses. Least squares linear regression was applied to examine the relationships between bacterial and algal abundance, and bacterial production.All analyses and plotting of data were performed using R v.3.4.1 . Levene’3 cells ml−1 . From the mid to late ablation period, bacterial abundance increased significantly in ice with a high algal coverage , reaching an overall maximum of 3.3 ± 0.3 × 105 cells ml−1 by the end of the ablation period.Bacterial abundance in the snowpack environment (prior to the retreat of the snowline) averaged 5.5 ± 0.6 × 10lls ml−1 , with noAncylonema nordenskiöldii and Mesotaenium berggrenii, consistent with the findings of 2 cells ml−1 were found in ice cores, with no significant difference in glacier algal abundance between different core sections. In the exposed bare ice surface during the early ablation period, glacier algal abundance was an order of magnitude greater than abundance in ice cores, averaging 2.1 ± 0.8 × 103 cells ml−1. As with bacterial abundance, glacier algal abundance was significantly different between ice surfaces visually categorized as containing a low, medium or high algal coverage . No significant relationship was apparent between glacier algal and bacterial abundance in snow pack, surface ice, or sub-surface ice environments prior to snow-line retreat or during the early ablation period. However, during both the mid and late ablation periods, significant linear relationships were apparent between glacier algal and bacteria abundance . As a comparison to the ice surface, bacterial abundance was determined within cryoconite sediment. Abundances were found to average 3.0 ± 1.0 × 107 cells g−1 (dry weight) during the mid-ablation period and 1.8 ± 0.3 × 107 cells g−1 (dry weight) during the late ablation period. Unlike the ice surface, there was no significant change in bacterial abundance in cryoconite across the ablation season.Comparative monitoring of glacier algal assemblages demonstrated the presence of two main species, −1 h−1) in snow pack, surface ice, and sub-surface ice sampled prior to snow line retreat and during the early ablation period , with maximal BP apparent in areas of medium algal coverage (0.50 ± 0.12 μg C L−1 h−1). In contrast to bacterial abundance, no significant change in BP was observed in surface ice with high algal coverage from the mid to late ablation period, with cell normalized rates of activity (data not shown) decreasing by approximately 96% over this period.Bacterial production (BP) was negligible  during the mid-ablation period, with a significant increase  to 0.02 ± 0.002 μg C g−1 h−1 apparent during the late period. At the cellular level, BP in cryoconite sediment increased from an average of 1.0 ± 0.5 fg C cell−1 h−1 during mid-ablation to 2.8 ± 0.3 fg C cell−1 h−1 by the end of the ablation period. Cryoconite sediment accounts for approximately 2.30 ± 0.80 and 5.1 ± 0.51 μg C m−2 h−1 of bacterial production across the ice sheet surface during the mid and late ablation period respectively, representing at least a ~ four-fold greater BP in cryoconite sediment than in surface ice containing a high algal coverage.Bacterial production in cryoconite sediment was negligible , demonstrating the development of bacterial communities from pre-snow line retreat, to the end of the ablation period, in tandem with glacier algal bloom monitoring. Overall, our data demonstrate that bacteria in the surface ice are likely consuming organic carbon produced by blooms of glacier algae; however, carbon cycling by heterotrophic bacteria in surface ice is significantly less efficient than in cryoconite sediment.2–103 cells ml−1; At the start of the ablation season, snow samples contained bacteria at abundances comparable with those previously reported for snow from the south western GrIS (10in situ photosynthesis) sources, with varying levels of bioavailability  35 times higher than BP , likely Consistent with the mid-ablation period, the highest abundances of bacteria were observed in areas with high algal coverage during the late ablation period. However, BP in surface ice with a high algal coverage was substantially lower than during the mid-ablation period with rates of NPP 260 times greater than BP . We suggBacterial production measured in cryoconite sediment was found to be lower than BP previously recorded on other Arctic glaciers . This liOur estimates of BP across a representative square meter of the supraglacial environment indicate that bacterial heterotrophic production in cryoconite holes is four times greater than in the surface ice, despite these habitats accounting for less than 8% of the GrIS ablation zone . BacteriDespite the potential influence on carbon cycling within the supraglacial environment, bacterial abundance, and activity within surface ice on the Greenland Ice Sheet has been largely understudied by the scientific community. This study aimed to identify spatial and temporal trends in the abundance and activity of heterotrophic bacteria within the supraglacial environment. Our results indicate that bacteria are spatially heterogeneous across the surface ice environment with influxes of cells from aeolian deposition as well as melting surface ice. The significant linear relationship between bacterial and algal abundances suggests organic carbon produced by glacier algae is being consumed; however, our study indicates that net primary production significantly exceeds bacterial production. This suggests that the remineralization of carbon by heterotrophic bacteria is inefficient on the surface ice, compared to cryoconite holes, and organic carbon accumulates within the surface ice. The fate of this organic carbon is currently unclear; however, several studies indicate extensive carbon export from ice sheets, which could stimulate bacterial production in downstream environments .The datasets generated for this study are available on request to the corresponding author.MN, CW, AA, and MY conceived and designed the study. CW, AA, MT, EP, AH, and the Black and Bloom group collected samples and conducted leucine incubations on the ice sheet. CW provided algal counts for the mid and late ablation periods. MN conducted bacterial counts and was aided by CW with leucine analysis. MN wrote the paper with inputs from CW, AA, and MY, and all authors reviewed the final manuscript.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.


Over the past 34 Million years, the Antarctic continental shelf has gradually deepened due to ice sheet loading, thermal subsidence, and erosion from repeated glaciations. The deepening that is recorded in the sedimentary deposits around the Antarctic margin indicates that after the mid-Miocene Climate Optimum (≈15 Ma), Antarctic Ice Sheet (AIS) dynamical response to climate conditions changed. We explore end-members for maximum AIS extent, based on ice-sheet simulations of a late-Pleistocene and a mid-Miocene glaciation. Fundamental dynamical differences emerge as a consequence of atmospheric forcing, eustatic sea level and continental shelf evolution. We show that the AIS contributed to the amplification of its own sensitivity to ocean forcing by gradually expanding and eroding the continental shelf, that probably changed its tipping points through time. The lack of past topographic and bathymetric reconstructions implies that so far, we still have an incomplete understanding of AIS fast response to past warm climate conditions, which is crucial to constrain its future evolution. The lack of detailed knowledge of the modern subglacial morphology, especially in key sectors of the AIS, induces large uncertainties in the prediction of the Marine Ice Sheet instability of highly sensitive outlet glaciers or ice shelves around Antarctica5. Reconstructing past seabed morphology around, and subglacial topography beneath, Antarctica is even more challenging6. Past ice sheet reconstructions provide useful information on the response of the AIS to warm and cold climate fluctuations of different magnitudes. However, uncertainties in the AIS contribution to past sea level changes or other forcing mechanisms during key periods, such as the middle Miocene, the middle Pliocene or the Last Interglacial, are still large7. A previous study8 using a reconstruction of the Eocene-Oligocene topography, proposed that a terrestrial West Antarctic Ice Sheet (WAIS), grounded mostly above sea level, was able to form much earlier than previously thought because of the shallower topography. Other numerical reconstructions of the mid -Pliocene (3 Ma) and present-day AIS volumes also account for the uncertainties linked with bedrock reconstruction9. In particular, recent simulations of the AIS forced with Miocene climate conditions and using an idealized mid-Miocene bathymetry2 show that grounded ice volumes and AIS vulnerability to marine instabilities are strongly influenced by the reconstructed subglacial topography. Similarly, simulated transient expansion of the AIS during the last glacial cycle occurs faster on shallower bathymetries that are shallower than today. Those simulations also show that the timing of expansion depends on the interplay between the magnitude of inland accumulation, ocean warming and calving3.On geological timescales, the dynamic changes of the AIS are likely to be the result of the combination of global climate cooling, the expansion and deepening of the continental shelf, and changes in ocean circulation and temperature. Although the extent of the AIS is primarily determined by the orbital configuration of a given time periodDetermining when continental margins deepened sufficiently to change the AIS dynamics and how the ice sheet reacted subsequently to atmospheric and oceanic condition changes is important in identifying useful analogues to future climate change. In this study, we use an ice-sheet model to investigate the impact that the gradual deepening of the Antarctic continental margin had on both Miocene and Pleistocene AIS response to changes in ocean forcing. We show that the AIS amplified its own sensitivity to ocean forcing, by gradually eroding the continental margins. Our results also show that eustatic sea level fall and glacial-isostatic adjustment (GIA) modulate the capability of the ice sheet to pin on bathymetric highs and that the importance of pinning points increases with the deepening of the continental margins. Finally, our simulations show a gradual expansion of the cold-based ice area from the middle Miocene to the Pleistocene that causes fundamental differences in the AIS dynamics. We conclude that as a result of the gradual deepening of the continental margins, ocean forcing became a first-order factor in the AIS expansion and retreat after the middle Miocene.3. Partial regional reconstructions of the mid-Miocene glacial paleo-bathymetry exist though, for example for the Ross Sea10 or for the Weddell Sea11. Both reconstructions suggest that large progradation of the continental shelf occurred until about the mid-Miocene Climate Optimum . Subsequent glaciations caused a widespread erosional event, documented in several locations around Antarctica, that led to the truncation of the stratal units that were deposited before the MCO. This event is dated around 16.7–14.2 Ma in the Ross Sea12 encompassing the entire MCO, and around 15 Ma in the Weddell Sea11. Those reconstructions  to derive two solutions of mid-Miocene topography and bathymetry at 15 Ma  and on the ice-free isostatically relaxed present-day topography and bathymetry BEDMAP216 (RBEDMAP2 hereafter). See Methods for more details.In the absence of pan-Antarctic paleo-topography and paleo-bathymetry reconstructions for the middle-Miocene, previous studies investigating the impact of past subglacial topography on AIS dynamics artificially increased or decreased elevation Ma Fig. . These a19, the comparison between reconstructed mid-Miocene paleo-bathymetry in the Weddell Sea11 and in the Ross Sea10 and our interpolated mid-Miocene bathymetries reveals that DEEP_MIO is in better agreement with data-based reconstructions than SHALLOW_MIO  as boundary conditions for ice sheet simulations to test the impact of the gradual deepening and expansion of the continental shelf on the AIS dynamics and its response to mid-Miocene and late-Pleistocene glacial climate conditions as well as to different sub-ice-shelf melting and calving conditions.The first mid-Miocene topography, SHALLOW_MIO, assumes that most of the deepening of WAIS and of East Antarctica (EAIS) marine basins, including the filling and expansion of the outer-most margins, occurs after the MCO . It therefore still has very shallow bathymetry (most of West Antarctica is emerged) and relatively-smaller continental shelves at 15 Ma Fig. . ConversMIO Fig. . The MCO2 concentration dropped21, leading to a gradual global climate cooling, marked by a major step in its evolution at the Plio-Pleistocene transition, about 3 Ma. Higher atmospheric CO2 concentration during mid-Miocene glacials (>280 ppm), combined with major oceanic and atmospheric circulation changes, led to mid-Miocene glaciations that were characterized by warmer and wetter conditions than during the late-Pleistocene glaciations when CO2 concentrations were significantly lower (<200 ppm)  Fig. . To expl2, characterized by a CO2 atmospheric concentration of 500 ppm and orbital parameters set for interglacial-like conditions . A second series of spin-ups is computed using late-Pleistocene atmospheric forcing, in our case the last interglacial climate at 125 ka22 . For each of the four topographies, the glacial advances of the AIS  are branched on those initial interglacial spin-ups  and late-Pleistocene LGM climate23  to force the ice-sheet simulations. Note that mid-Miocene and late-Pleistocene climate conditions have been generated with different climate models.Interglacial ice-sheet equilibrium spin-ups  are carried out for each of the four topographies. A first series of spin-ups is performed under mid-Miocene interglacial climate conditions25 impose 0 m/yr in their glacial simulations, recent ocean modeling of the LGM26 shows that ocean water nearby the AIS margins is not at freezing point everywhere which is why we impose a minimal sub-ice-shelf melt rates over the continental shelf. Calving thickness thresholds are prescribed based on literature estimates varying between 150 meters27 and 200 meters28. These studies agree on the fact that the re-expansion of the AIS after a collapse is almost impossible if the calving threshold remains larger than 150 meters. Therefore, in our simulations we test intermediate ad-hoc calving threshold values of 120 meters and 160 meters  are carried out Fig. . In the 26 show that, despite global cold climate conditions, sub-ice-shelf melt rates in the vicinity of the Antarctic continental shelf break remain relatively high, close to present-day values, and penetration of warm Circum Polar Deep Water on the continental shelf occurs only in specific locations of the continental shelf edge. Therefore, in a second group of simulations  and eustatic sea level prescribed at 70 meters below present-day global mean sea level from a previous study2  and eustatic sea level set at −120 m   are carried out: (1) mid-Miocene glaciation  ful29) Fig. ; (3) a s29) Fig. . Thereby29) Fig. , and the29) Fig. . Those sOur results show that the gradual deepening of the outer continental shelf from EOT to RBEDMAP2 induces an overall gradual decrease in ice volume along with increasing calving and sub-ice-shelf melting. This is particularly marked for DEEP_MIO and RBEDMAP2 in all three sets of simulations Fig. . This deIn general, the Miocene wet climate leads to higher simulated ice volumes than under the dry late-Pleistocene glacial climate conditions Fig. . But as 31. In our ice sheet model, GIA follows an Elastic-Lithosphere-Relaxing-Astenosphere (ELRA) parameterization32, which is a simplified version of the fully self-gravitational GIA theory used in recent studies31. Nevertheless, the ELRA has been shown to satisfactorily capture the essential effect of GIA32 and is enough to illustrate the first order feedback between GIA, bathymetry and ice dynamics. In our mid-Miocene simulations, inhibiting GIA (black bars) yields lower ice volumes and reduces the sensitivity to ocean forcing . It has been recently shown that the fast rebound of the lithosphere in specific areas can partly compensate for the Marine Ice Sheet Instability by increasing the bed elevation, thereby providing new pinning points to the ice sheeting Fig. , which p33. In our ice -sheet model, the presence of saturated sediments is used as a trigger to accelerate basal velocities (see Methods). As a result, in our mid-Miocene and late-Pleistocene simulations the acceleration of the ice flow leads to a smaller grounded ice volume  ges Fig. . SHALLOWges Fig.  and thusAIS Fig. , which pAIS Fig. . Seismic ges Fig.elf Fig. . This isFirst noticeable continental shelf filling and deepening around the MCO  than over SHALLOW_MIO. Deeper marine basins also enhance ice streams activity and as a result of elevated basal friction, the amount of basal meltwater increases compared to that simulated over SHALLOW_MIO  MCO Fig. . In DEEPMCO Fig. . SteeperMIO Fig. . The redMIO Fig. . This isMid to late Miocene gradual climate cooling  but using the late-Pleistocene glacial atmospheric forcing with low CO2 . Although synoptic circulation may have changed between late Miocene and late Pleistocene, the simulations illustrate the first order impact of low CO2 on the AIS dynamics over a bathymetry not as deep as today. With the cooling and drying of atmospheric forcing, the sensitivity of the entire WAIS, and that of the EAIS at Wilkes and Aurora Basins to ocean forcing increases substantially compared with previous steps  ing Fig. . After teps Fig. . This hiAIS Fig. . With thAIS Fig. . As a coPlio/Pleistocene glaciations  ons Fig. . With deons Fig. . No furtons Fig.  since pr19. Stratigraphic analysis from the western Ross Sea35, Aurora basin37 and from Wilkes Land38 document the turning point from a wet-based regime with a large sediment supply to a polar regime of the AIS with lower sediment supply during the late Miocene. Our simulations show a substantial spatial and quantitative reduction in erosion potential between the middle Miocene and the late Pleistocene along with AIS dynamical changes that possibly occurred between Fig. 34 and from the ANDRILL sediment core records19. The main difference in ice volume between middle Miocene and late Pleistocene is computed over the Pacific sector of the EAIS (including Prydz Bay). Changes in seaway configurations from the Miocene to today (primarily the opening of the Bering Strait and the closure of Panama) might have induced changes in atmospheric and oceanic teleconnections originating in the Pacific and been responsible for moisture advection over the Pacific sector of Antarctica39.The expansion of the cold-based area, according to geological evidence might have started during the MCTOur simulations clearly show that the evolution of the deepening and expansion of the continental margins influences the dynamical states of the AIS, independently from the atmospheric forcing Fig. . AtmosphThe interplay between atmospheric and oceanic conditions, sea level and bed morphology has a transient nature. In the present study, we used steady-state climate forcing to our ice-sheet simulations. It is likely that, in transient ice sheet simulations some compensation occurs between the atmospheric forcing and the oceanic sub-shelf melting that could have dampened the sensitivity to the various oceanic forcing tested in our study. Spatial resolution in our simulations is low, 40 km, and increasing resolution would probably induce different AIS dynamical behaviors since a more resolved subglacial topography would present different pining areas. Nevertheless, we maintain that our simulations show the primary mechanisms and interplay between the evolution of the subglacial topography, the deepening of continental shelf and the atmospheric and oceanic forcing. With these simulations, we show that the AIS contributed to the amplification of its own sensitivity to climatic conditions (atmosphere + ocean) by gradually eroding the continental margins, which likely changed its tipping points through time. The lack of past topographic reconstructions implies that we still have an imprecise idea of AIS response to past climate evolution, which is crucial to determine the AIS future evolution.3 or assumed a linear evolution of the bed elevation through time2. Here, we use the global δ18O stack13 to derive two solutions of mid-Miocene topography at 15 Ma  and the relaxed present-day subglacial topography BEDMAP216 (RBEDMAP2). We assume that the δ18O evolution is representative of the glacial erosion and marine sedimentation occurring around Antarctica . This implies that continental-margin expansion is representative of sedimentation rates (as a first-order approximation) but mostly bounded to climate evolution. The first mid-Miocene topography, i.e., SHALLOW_MIO, implies that most of the deepening occurs after the Miocene Climatic Optimum  and thus signifies shallow bathymetry, i.e., mostly emerged topography more limited continental shelves than today  is the normalized δ18O time serie such that α(tMa34) = 0 and α(t0) = 1  = −0.10. Conversely, the second topography DEEP_MIO implies that part of the deepening happened before the MCO and exhibits broader continental shelves and deeper marine basins than SHALLOW_MIO  is reversed in time compared to the first subglacial topography solution such that α_rev(t) = α(tMa34 − t). At 15 Ma, α_rev(tMa15) = 0.65. We thus have four different topographies and bathymetries, EOT, SHALLOW_MIO, DEEP_MIO and RBEDMAP2, each representing successive gradual deepening of the continental shelves through time.At 15 Ma, MIO Fig. :3\docume41. The grounded part uses the Shallow Ice Approximation42 (SIA) whereas ice shelves and ice streams are treated using the Shallow Shelf Approximation43 (SSA). The ice shelf and ice stream formulation in GRISLI allows for a more realistic calculation of the growth of the ice sheet and ice shelves by allowing horizontal velocities to evolve freely and reach rapid basal sliding, particularly for the advance of ice onto the shallow continental shelves45. Isostasy is calculated by means of the Elastic-Lithosphere-Flexural-Asthenosphere model32 and seismic-based geothermal heat fluxes map is prescribed over the Antarctic domain46. To account for anisotropy in GRISLI, two enhancements factors are prescribed, one for grounded ice, handled with the SIA (ESIA), and one for ice shelves, handled with the SSA (ESSA). Usually, ESIA is larger than 1, while ESSA is lower than 1. In GRISLI, a simple basal hydrology scheme checks for the presence of both basal sediments and basal meltwater to trigger an acceleration of the ice flow by applying the SSA instead of the SIA approximation47. Our standard simulations do not include this effect. To test the impact of a basal sediment on the AIS dynamics, a basal sediments thickness map48 is prescribed as a boundary condition on the subglacial topography in an additional set of simulations. Calving occurs at the ice shelf front at a prescribed thickness HCOUP if the upstream ice flux cannot maintain the ice shelf balance. Basal melting under the ice shelves takes a prescribed uniform value that can vary with depth or follow a quadratic depth-temperature relationship following49. Atmospheric forcing is downscaled on the ice-sheet model grid and corrected by means of a standard lapse rate (6.5 °C) and precipitation correction factor (0.07% C−1). The ablation is calculated using the semi-empirical Positive Degree Day method50 (PDD) and up to 60% of the surface melt is able to refreeze. Surface mass balance is kept fixed for the entire simulations. The ice-sheet model is run on a 40-km horizontal cartesian rectangular regular grid using the polar stereographic projection . Unless otherwise stated, we use the default parameters listed in Supplementary Table GRISLI is a 3D-thermo-mechanical ice sheet - ice stream - ice shelf model, able to simulate both grounded and floating iceSupplementary Information


In recent years, many of these features have begun to melt entirely for the first time, producing urgent threats to traditional management techniques, the viability of summer pastures, and reindeer health. The melting ice is also exposing fragile organic archaeological materials that had previously been contained in the patch. We present the results of horseback survey of ice patches in Baruun Taiga special protected area, providing the first archaeological insights from the region. Results reveal new evidence of historic tool production and wild resource use for fishing or other activities, and indicate that ice patches are likely to contain one of the few material records of premodern domestic reindeer use in Mongolia and lower Central Asia. The area’s ancient ice appears to be rapidly melting due to changing climate and warming summer temperatures, putting both cultural heritage and traditional reindeer herding at extreme risk in the years to come.In interior Eurasia, high mountain zones are crucial to pastoral subsistence, providing seasonally productive pastures and abundant wild resources. In some areas of northern Mongolia, mountainous tundra zones also support a low-latitude population of domestic reindeer herders–a lifestyle whose origins are poorly characterized in the archaeological record of early Mongolia. Traditionally, reindeer pastoralists make significant seasonal use of  Montane environments in the dry steppe function as important loci of animal and plant biodiversity for hunting, fishing, and gathering, as well as focal points for diverse kinds of pastoral activity. In dryland regions of Central Asia, precipitation is scarce and highly seasonal; orographic precipitation generated by mountain topography is crucial to pasture growth (Frachetti 2008). Improved rain and pasture reliability of montane zones enables herders to practice vertical seasonal movements over short geographic distances into alpine summer pastures, where the well-watered forage can sustain larger populations of heavier, more water dependent livestock, as well as the cold-adapted yak (Bos grunniens) and the reindeer (Rangifer tarandus), which are found only in northern Mongolia. Owing to these unique ecological roles, montane regions in Mongolia appear to have been hotspots for the region’s earliest herding economies during the early Bronze Age .In the cold, dry, and harsh environs of the Eurasian steppes, mountain regions have played a key role in herding lifeways both now and in the past -while contemporary climate warming threatens both pastoral adaptations and the region’s fragile archaeological record. In contemporary Mongolia, most rural residents make their living through specialized, seasonally-mobile herding of domestic livestock. Across most of the region, the key herding animals are known the In recent years, consideration of paleoenvironmental proxies alongside archaeological data has revealed close links between climate processes important pastoral social developments in northeast Asia. For example, changes in temperature and precipitation regimes have been linked to the initial transition to herding from hunting and gathering , the adoHigh altitude tundra zones found in northern Mongolia’s Sayan Mountains  are partPerennial deposits of snow and ice, known as ice patches, provide a promising avenue for answering these critical questions. These non-glacial accumulations often occur on north-facing slopes in high latitude and high altitude regions. Ice patches are distinguished by the fact that they do not melt completely during the summer months. Because of their perennial nature, ice patches play a crucial role in summer subsistence for many plant and animal taxa, providing thermal relief for wild reindeer , reprievDukha).These people settled in the region when Tuva was annexed into the Soviet Union during World War II—although nearby areas may have been used by the Dukha for centuries [Nestled alongside the large Darkhad Depression  to the wenturies . Today, enturies . Most ofThe study area, known as Mengebulag, a large tundra valley and popular summer pasture for Tsaatan reindeer herders located above 2000 masl within Baruun Taiga in the Sayan Mountains along the western lip of the Darkhad Depression. On a preliminary visit to the region in 2017, we identified ice patches between 1850–2580 masl in the vicinity of 51° N. Verbal discussions with residents indicated that during the summers of 2016–2018, previously permanent patches in Mengebulag melted for the very first time in collective memory . RecogniDuring 2018 fieldwork at Mengebulag, we conducted systematic archaeological survey for material culture associated with pre-modern use of tundra zones in the Darkhad region. We also conducted informal interviews with eight local families living in summer pastures at Mengebulag, with the aim understanding A) the role ice patches play in contemporary reindeer herding, wild resource gathering, and subsistence; B) recent trends in ice melt extent and its impact on domestic reindeer; and C) ethnographic interpretation of organic artifacts recovered from ice patch localities in the Mengebulag area.During informal ethnographic interviews with three families at their summer camps in the Mengebulag area , we asketh, 2018 –with authorization from the Baruun Taiga Special Protected Area . During late July and early August, 2018, we visited 11 ice patches in our study area identified through melt-season satellite imagery, along with two ice-free, former patch areas identified to us by ethnographic informants. Ice patch locations in the Mengebulag area were identified using 2016 and 2017 melt-season (July and August) satellite imagery from Google Earth and the NASA Earth Science Data Observatory. Ice patch permanence was assessed through discussion with area residents, who verbally assessed whether a given patch was perennial or melted during the summer., we conducted full-coverage horseback and pedestrian survey of the margins of 11 permanent ice patches at Mengebulag  issued to the Northern Mongolia Archaeology Project and the National Museum of Mongolia from the Mongolian Ministry of Education, Culture, Science, and Sport on May 4ngebulag . Pedestrhttp://calib.org/CALIBomb/), using northern hemisphere Zone 1 from Hua et al [We sampled exterior wood shavings from organic artifacts for radiocarbon dating at the University of Oxford Radiocarbon Accelerator facility. We calibrated our measurements using the program CALIBomb . Informants suggest the ground may be drying out, and they point to the fact that while horses are commonly used near the Mengebulag camps today, just a few years ago this was impossible because of the swampy ground that was typical of the area. Many herders complained of declining pasture quality leading to bad health and even animal loss and death. When asked which criteria are most significant for pastoral use, one informant suggested that proximity to suitable camp locations and pasture was most important–and that these have been most severely affected by recent summer melting. On the basis of these interviews and observations, it appears that ice patch melting has a variety of negative outcomes for the viability of reindeer herding that may directly threaten this already vulnerable economic system .At five of the patches studied using archaeological survey, we recovered plant and animal materials, presumably non-cultural in origin, emerging directly from the melting ice. Although not directly related to human activity, these finds demonstrate the presence of interpretable paleoecological material , right iAt the site of Khets Davaa, we discovered a number of organic wooden artifacts exhibiting cultural modification from an ice-free patch location that (according to informants) melted completely for the first time in 2016–17. Although the site is today unwooded and above the tree line, we recovered several pieces of cylindrical, unmodified wood that appear to be “manuports” brought to the site through human activity. In addition, we recovered three artifacts exhibiting cultural modification. The first of these is a stick ~2.5 cm in diameter, exhibiting cut marks along the bottom margin, probably produced by a metal hatchet . One posth century, as a means of producing a strong yet flexible joint . Such behaviors are also noted among the semi-domesticated reindeer of the Saami people in northern Scandinavia and wild caribou of North America ,22–26. IAccess to fresh water for humans reindeer is also an important function provided by ice patches that is threatened by summer warming. Several informants described proximity to suitable pasture and camp locations as the most important factor in determining patch use for pastoral purposes, and indicated that those closest to camp were subjected to the most severe recent melting e.g. . PastoraThe use of new pastures in the Darkhad region is also prohibited by regulations governing the area’s “strictly protected” conservation zones. Despite receiving financial state support for increasing their herds, with these restrictions in place, current pastures suffer increasing degradation due to larger herd sizes. In 2018 conversations, informants mentioned that lichen and plants eaten by reindeer typically need three years to fully recover—meaning that restricted mobility has dire consequences for pastured degradation. Under these paired socioeconomic and ecological circumstances, ice patches appear even more important for the Tsaatan and their reindeer. Other patch qualities, beyond those explicitly mentioned by informants  may also be important, as well as influenced by the melting process. As continued warming is anticipated in the future, we expect that ongoing melting of ice patches will cause new sources of stress and disease for livestock , reducing the viability of summer pastures threatening the sustainability of reindeer pastoralism.Our archaeological survey provides support for the idea that ice patches contain key insights into the role of mountain zones in the poorly understood history of domestic reindeer in Mongolia. Our investigation identified one patch that showed extensive use by modern reindeer, as evidenced by a large amount of previously frozen dung, hair, and other organic material. Future investigation of this patch and others yielding plant and animal material during peak summer melt, paired with radiocarbon dating and more nuanced paleoecological analysis, may provide important new data necessary to reconstruct the antiquity of domestic reindeer use in northern Mongolia.Moreover, the discovery of at least two artifacts shows that taiga environments were exploited by Tsaatan people for acquiring wild resources–possibly fish–after their arrival to the region in the mid-20th century. The radiocarbon dates suggest the most likely period for the deposition of the artifacts was the early 1960’s during the Soviet-era collectivization period, or in the late 1970’s. Ethnographers have documented the former interval as a particularly harsh transition for the Dukha people, and a period during which traditional hunting practices were largely banned, and reindeer herding was not supported under state-run livestock policies . During Ice patch melting in the region is part of a larger global phenomenon . Our resWhile the emergence of pastoral economies in Central Asia was one of the most important economic transitions in human history, many of the dynamics underlying this transition are poorly understood. This is particularly true of the archaeological record of high-mountain zones. Strong circumstantial evidence suggests that these areas may have been crucial to the early development of herding lifeways; however, due to their environmental and depositional characteristics, these areas retain little direct evidence of how they were used in the deep past. In Mongolia, mountain zones host unique species of domestic animals (reindeer and yak), that provide the economic foundation of some modern lifeways, but evidence of the process by which they were domesticated is almost absent from the archaeological record.Our investigations in northern Mongolia indicate that persistent snow and ice patches–long known to be important loci for reindeer hunting–play a central role in modern reindeer pastoralism. The degradation and loss of these features in summer pastures threaten the viability of this herding lifestyle. Archaeological surveys and ethnographic research of ice patches in one important tundra zone in Mongolia’s Darkhad Basin provide the first direct material evidence of exploitation of this region in the mid-twentieth century, and suggest that contemporary melting exceeds levels seen in at least half a century. Culturally modified wood recovered from a melting ice patch suggest use of the area for summer pastures and travel corridors in modern times (as well as for wild resource gathering such as fishing) in the mid-20th Century, after documented migration to the region from southern Russia. While future research may yield important cultural and paleoenvironmental material relevant to understanding the deeper chronology of reindeer domestication and pastoral use of high altitudes, ice patches and the material they contain are urgently threatened by warming temperature and climate change.


Ice sheets repeatedly advanced into the central North Sea, south of ~60°N, from 2.53 Ma ago onward moving over slippery beds with low slung profiles. Geometries of Early Pleistocene [2.58 to 0.78 million years (Ma) ago] ice sheets in northwest Europe are poorly constrained but are required to improve our understanding of past ocean-atmosphere-cryosphere coupling. Ice sheets are believed to have changed in their response to orbital forcing, becoming, from about 1.2 Ma ago, volumetrically larger and longer-lived. We present a multiproxy data set for the North Sea, extending to over a kilometer below the present-day seafloor, which demonstrates spatially extensive glaciation of the basin from the earliest Pleistocene. Ice sheets repeatedly entered the North Sea, south of 60°N, in water depths of up to ~250 m from 2.53 Ma ago and subsequently grounded in the center of the basin, in deeper water, from 1.87 Ma ago. Despite lower global ice volumes, these ice sheets were near comparable in spatial extent to those of the Middle and Late Pleistocene but possibly thinner and moving over slippery  beds. Northwest (NW) Europe is a critical region for understanding past, present, and future ocean-atmosphere-cryosphere coupling, as it is adjacent to the North Atlantic, where, for example, meltwater inputs can affect the ocean conveyor  (7), aftDuring the Pliocene to Early Pleistocene, the North Sea was a long (~600 km), narrow (<200 km), and deep (up to ~400 m) marine inlet  construcWe present new, detailed subsurface mapping here, from a basin-scale 3D seismic reflection data set  Atlantic. River discharge into the North Sea, from continental Europe, Scandinavia, and Great Britain, would have forced a buoyant surface current to flow out of the basin, with return inflow at depth. This surface current would have limited the potential for icebergs to enter from the North Atlantic  and 3A. The bathymetry of the North Sea during the Early Pleistocene (SU1) provides the second, independent, line of evidence. The new basin-scale mapping identified a shallow bathymetric lip, south of 60°N, which limited the draft of any North Atlantic icebergs that could have potentially entered the North Sea . The TWTIn summary, the first iceberg scours are recorded, at the latest, during MIS 100  are diagnostic for the presence of grounded ice streams, the drainage arteries of ice sheets  (27). FlCores recovered from three wells between 878 to 965 m below the seafloor during the exploration and appraisal phases of the Aviat gas field, show a buried, ice-proximal, subaqueous fan  and 4 9 is overlAnalyses show that the cored sediments are dominated by detrital quartz and feldspar with clays accounting for, on average, 22% by weight. Scanning electron microscopy (SEM) micrographs show that feldspars and hornblende are invariably fresh in appearance  thick . The seiThe regional seismic mapping presented above has been tied chronostratigraphically to borehole data in the southern North Sea and forms the dating framework. Seismic horizons defining the prograding clinoforms in the SE of the central North Sea have been traced back across the shelf and tied into the most detailed Plio-Pleistocene chronology for the North Sea (see Methods)  and BIIS-FIS affect atmospheric circulation, controlling the trajectory of the polar frontal jet stream (PFJS) . ConstraSuch an extensive BIIS and FIS in the North Sea from the beginning of the Pleistocene provide direct support for the low-slung ice sheet concept associated with the LIS  or a smaller accumulation area ratio  in comparison to a thicker ice sheet with the same footprint (fig. S5). This can be achieved by either reducing ablation (lowering air temperatures) or enhancing accumulation (precipitation) or some combination of both. Compared with the Late Pleistocene, air temperatures in the Early Pleistocene appear higher , after which the gamma ray signal begins to decline (fig. S7)  and changes in ocean bottom water temperature (a 1°C decrease in temperature increases the δ18O of precipitated carbonate by +0.25 per mil and is independently derived from the Mg/Ca ratio) , increasing through the MPT and into the large cycles of the Middle and Late Pleistocene. Sources of error in δ18O-Mg/Ca–derived IV-SL are mainly related to diagenetic and seawater chemistry changes, such as Mg/Ca ratio. The evidence presented here on the spatial extent of the BIIS and FIS adds to that from North America  would be in keeping with the terrestrial evidence of ice sheet extent in North America and Europe.It is important at this point to consider the impact of the findings presented above for ongoing research investigating the veracity of the ice volume/sea-level (IV-SL) interpretations from stacked records  dated using magnetostratigraphy and an additional age, ~2.35 Ma ago, dated using palynology correlated to the global oxygen isotope curve in borehole A15-03 in the southern North Sea , we mapped the entire Pleistocene sedimentary succession in the North Sea and along the mid-Norwegian margin, including the North Sea Fan, which is a key area for determining iceberg flux into the North Sea.−1  intermediate complexity climate model   and 10 (1500 m × 1000 m 300 m) . In addiAviat cores were described as they were split, with both cut halves being consulted where necessary. A purely descriptive lithofacies scheme, which defines lithology and sedimentary structures without inferring depositional setting, was used. Subsequently, the depositional model for the cored interval was developed, taking account of all cored intervals, regional seismic interpretations, and in situ and offset well data. Well 22/7a-6Z is deviated, so the core has been used to provide generalized directions of water flow, from ripple climbing directions, and glaciotectonic kinematics, from folds and faults.Mineralogical descriptions on Aviat core samples were undertaken both visually (thin sections and SEM) and analytically [x-ray diffraction and energy-dispersive x-ray (EDX)] throughout the cored intervals. The combination of mineralogy and texture from the EDX-SEM analyses provided the assessment of grain freshness, interpretation of the grain history, and by default relative age of the weathering-susceptible minerals.Volumetric micropaleontological analyses on Aviat core samples were undertaken, applying a uniform and consistent approach to microfossil picking and counting. For all samples, a standard volume was processed, with known splits picked for microfossils. For faunal comparisons, all foraminifera were picked before normalizing back to unity.The palynological analysis involved a count of the dominant palynomorphs with a subsequent scanning of the slide for additional taxa. A counting method was applied, which attempted to overcome the “blanketing” effect of dominant taxa. The palynomorph count was undertaken on both the >30 μm and the 10 to 30 μm sieve fraction slides with all taxa being recorded, including their relative abundances. Nannofossil counting was conducted along a measured traverse within a concentrated smear slide. The length of the traverse is variable depending on fossil recovery. Following completion of counting, the slide was scanned to detect the presence of rare marker species not previously identified. Individual species counts were normalized to a standard traverse length of 50 mm (≡300 fields of view) to accurately represent variations in the absolute abundance of each species. None of the micro- and nanopaleontological and palynological data were used for paleoenvironmental interpretation, although water depth estimations accord with those determined from the backstripped rebounded crust and eustatic sea-level curve (Hypothetical geometries of the BIIS and FIS are presented in


This study was performed to evaluate whether hot temperature and rumen-protected fat (RPF) supplementation affect growth performance, rumen characteristics, and serum metabolites in growing stage of Korean cattle steers.Twenty Korean cattle steers  were divided into a conventional control diet group (n = 10) and a 0.8% RPF supplementation group (n = 10). Steers were fed 1.5% BW of a concentrate diet and 4 kg of tall fescue hay for 16 weeks .3-N, and volatile fatty acid concentrations, whereas the C2:C3 ratio was affected (p<0.05) by month.The mean temperature-humidity index (THI) was higher (p<0.001) in P1 (76.8), P2 (76.3), and P3 (75.9) than in P4 (50.9). The mean THI of P1–3 were within the alert heat stress (HS) category range according to previously reported categories for feedlot cattle, and the mean THI of P4 was under the thermo-neutral range. Neither month nor RPF supplementation affected (p>0.05) average daily gain and gain to feed ratio. Month and RPF supplementation affected concentrations of glucose, albumin, and high-density lipoprotein (HDL); those of albumin and glucose tended to decrease (p<0.10), but HDL concentration increased (p<0.01) by RPF supplementation. Neither month nor RPF affected (p>0.05) ruminal pH, NHKorean cattle may not have been significantly affected by alert HS during the growing stage. Growth performance was higher during hotter months, although some changes in blood metabolites were observed. The RPF supplementation affected some blood lipids and carbohydrate metabolites but did not affect growth performance. Animal productivity  is affected by various factors, including genetic, management, nutritional, and environmental factors . Heat stSeveral studies have attempted to determine optimal nutrition to decrease HS and cold stress and increase animal productivity, including dietary fat supplementation –16. RumiAll experimental procedures involving animals were approved by the Seoul National University Institutional Animal Care and Use Committee (SNUIACUC), Republic of Korea, and conducted in accordance with the Animal Experimental Guidelines of the SNUIACUC. This study was conducted at the University Animal Farm of the College of Agriculture and Life Sciences, Pyeongchang Campus of Seoul National University, South Korea.Twenty Korean cattle steers were used in a feedlot trial; these steers had an average age of 10.7±0.09 months and weight of 230.4±4.09 kg. The steers were fed commercial growing stage concentrate using an automatic feeding station  and timothy hay, following a conventional feeding program. Drinking water was provided freely. During a 2-week adaptation period before the experiment, all animals were fed an experimental control concentrate  and timothy hay (5 kg/d/head). Steers were assigned to one of two treatments: control and RPF supplementation. The RPF is prilled form of palm oil, as described , and purThe chemical compositions  of the concentrate and timothy were determined using the Association of Official Analytical Chemists (AOAC) method . The neug at 4°C for 15 min and stored at −80°C until analysis.Blood was collected before feeding (after 9 h of fasting) at approximately 09:00 on the start date and at 4-week intervals thereafter. Blood was collected via jugular venipuncture with a non-heparinized vacutainer . Serum was separated by centrifugation at 1,500×Ambient (inside of the barn) and climate (outside of the barn) temperatures, and relative humidity inside and outside the barn, were recorded at 1-h intervals using four HOBO data loggers . Monthly average values of minimum, mean, and maximum temperatures and humidity values were calculated using daily data. The THI (modified from ) was calThe experimental farm was covered by a roof and both side doors were closed; thus, the animals were raised indoors. Steers could access the feeding station and roughage bucket freely, but they were not allowed to move outside the barn. As such, we ignored any effects of rain, direct sunlight, or wind. Thus, humidity and temperature, subsumed within the THI, were the major climate factors in this study.3-N) analysis. NH3-N concentrations were determined using a modified colorimetric method [Following blood collection, rumen fluid was collected after 3 h of feeding using the oral stomach tube method, as described by Shen et al . Rumen fc method . The VFAAnalytical reagents for albumin, glucose, triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein, cholesterol, glutamic oxaloacetic transaminase (GOT), and glutamic pyruvate transaminase (GPT) were purchased from JW Medical . Analytical reagents for non-esterified fatty acid (NEFA) analysis were purchased from Wako Pure Chemical . All parameters were analyzed using an automated chemistry analyzer . All analyses were validated in our laboratory, as previously reported .Differences in climate parameters among months were analyzed using one-way analysis of variance (ANOVA). Differences in growth performance, blood parameters, and rumen fluid parameters due to month and dietary treatment were analyzed using repeated-measures two-way ANOVA. The statistical model included month, diet, and their interaction. Significance was determined at a level of p<0.05. All statistical tests were performed using the R Studio for Windows software .The mean  and maximum  indoor THI in July (P1), August (P2), and September (P3) were higher (p<0.001) than those in October  in P4 than in P1, reflecting animal age. The daily concentrate intake was higher (p = 0.03) in P4 than in P1 . In this3-N and all VFA parameters  were unchanged (p>0.05) by temperature or RPF supplementation  by temperature or RPF supplementation. Ruminal NHentation . The C2:entation . SimilarCirculating glucose was lower (p<0.001) under hotter conditions and was decreased (p = 0.08) by RPF supplementation . PreviouBlood HDL, TG, and cholesterol concentrations were lower (p<0.05) during hotter periods than in thermo-neutral periods . SimilarBlood GPT concentrations were lower (p<0.05) during hotter periods than in the thermo-neutral period; however, they were not affected (p>0.05) by RPF supplementation . As in o3-N, and VFA concentrations were not significantly affected by HS conditions or RPF supplementation, although the C2:C3 ratio differed between months. Blood parameters were more sensitive to HS conditions than to rumen parameters. Serum TG, cholesterol, HDL, and glucose were lower under hotter conditions, and other serum parameters such as NEFA, GOT, and GPT were affected by month. Serum glucose, HDL, and albumin were affected by RPF supplementation. Thus, Korean cattle in growing stage may not be significantly affected by HS conditions, although rumen fermentation and blood parameters were partially affected in the current study. RPF supplementation did not affect growth performance or major rumen VFA concentrations; however, RPF supplementation affected glucose and HDL concentrations. Further research is warranted to determine which HS conditions significantly affect the growth performance of Korean cattle during the growing stage.Growth performance (average daily gain and G:F ratio) did not worsen during hotter months. Rumen fermentation parameters such as ruminal pH, NH


We are studying the chemical quality of dissolved organic nitrogen (DON) in a high-elevation watershed in the Colorado Front Range. Samples were collected over the 2000 snowmelt runoff season at two sites across an alpine/subalpine ecotone to understand how the transition between the lightly vegetated alpine and forested reaches of the catchment influences the chemical character of DON. Samples were analyzed approximately weekly for dissolved organic material (DOM) content and chemical character. A subset of samples was analyzed for the elemental content of fulvic and hydrophilic acids. Concentrations of DON at both sites were highest in the spring at the initiation of snowmelt, decreased during snowmelt, and increased again during the late summer and fall. In contrast, concentrations of dissolved organic carbon (DOC) peaked on the ascending limb of the hydrograph and declined to seasonal minima on the descending limb of the hydrograph. The ratio of DOC:DON showed a seasonal shift at both sites with high values (40 to 55) during peak runoff in early summer and lower values (15 to 25) during low flows late in the runoff season. These results indicate that there was a seasonal change in the relative N content of DOM at both sites. Chemical fractionation of DOC showed that there were temporal and longitudinal changes in the chemical character of DOC. At the alpine site, the fulvic acid content of DOC decreased from 57% in June to 35% in September. The change in fulvic acid was less pronounced at the forested site, from 66% in June to 54% in September. Elemental analysis of fulvic and hydrophilic acids indicated that hydrophilic acids were N rich compared to fulvic acids. Additionally, fulvic and hydrophilic acids isolated at the alpine site had a lower C:N ratio than those isolated at the forested site. Similarly, the C:N ratio of organic acids at both sites was lower in September than in June during peak runoff. These differences appear to be a result of changes in both DOM precursor material and hydrologic flowpaths. Using C:N ratios of fulvic and hydrophilic acids, we estimate that nonhumic material carried between 54 to 73% of the organic N in surface water at the alpine site and 44 to 58% of the organic N in surface water at the subalpine site.


The versatility of the interferometric nitrocellulose-based sensing surface was demonstrated since the limit of detections for BICELLs and ImmunoCAP® were 0.7 and 0.35 kU/L, respectively.Food allergy is a common disease worldwide with over 6% of the population (200–250 million people) suffering from any food allergy nowadays. The most dramatic increase seems to be happening in children and young people. Therefore, improvements in the diagnosis efficiency of these diseases are needed. Immunoglobulin type E (IgE) biomarker determination in human serum is a typical in vitro test for allergy identification. In this work, we used a novel biosensor based on label-free photonic transducers called BICELLs (Biophotonic Sensing Cells) for IgE detection. These BICELLs have a thin film of nitrocellulose over the sensing surface, they can be vertical optically interrogated, and are suitable for being integrated on a chip. The BICELLs sensing surface sizes used were 100 and 800 µm in diameter. We obtained calibration curves with IgE standards by immobilizating anti-IgE antibodies and identified with standard IgE calibrators in minute sample amounts (3 µL). The results, in similar assay format, were compared with commercially available ImmunoCAP Food allergy is an immune-based disease that has become a serious health concern worldwide. The prevalence and severity of food allergy has dramatically increased in both developed and developing countries in the last 15 years ,3. Thus,Current diagnostic methods for food allergies might be classified in three levels . The firCommercial in vitro tests use immunochemical techniques based on immobilization of the allergen on solid phase or over different surfaces, such as microplates, microarrays, capsules, and membranes. The sample (human serum) is incubated over the surface, waiting for the IgE binding of those components to which the patient is sensitized. After that, the binding is visualized through the optical signal that is developed by means of a labeled secondary antibody with enzymes, fluorophores, or gold nanoparticles. A relevant limitation of these techniques is the difficulty of standardization of the allergens used in diagnosis when food extracts are used ,11,12. AThe point-of-care (PoC) devices are an innovative cost-effective alternative able to solve some of the aforementioned limitations . HoweverConsidering the abovementioned reasons, we proposed the use of a cost-effective label-free detection system as an outstanding alternative to in vitro CRD tests. Our diagnostic system was based on disposable biochips with the capability of implementing hundreds of our patented biosensing sites (Biophotonic Sensing Cells (BICELLs) ) on them®. We obtained calibration curves for two different sizes of BICELLs 100 and 800 µm in diameter. We biofunctionalized BICELLs with anti-IgE antibodies and measured increasing levels of IgE molecules in the recognition step. The minute amount of sample required was 3 µL for BICELL. We accomplished the recognition response curve by optical readout with the already tested methodology of a novel label-free point-of-care (PoC) reader [In this study, as proof of concept for allergy biomarker detection, we compared our IgE calibration curves with the in vitro “gold standard” for the analysis of specific immunoglobulins in human serum samples, the ImmunoCAP) reader , and com2 and SU-8 photoresist  [We used integrated biochips that were made up of three interferometric Biophotonic Sensing Cells (BICELLs). BICELLs are based on a Fabry-Perot interferometer (FPI), and its optical label-free biosensing capability is enhanced by adding a thin film of nitrocellulose over the two interferometric layers of SiOMA, USA) ,26. We hMA, USA) .We used a 4″, p-doped, <100> Si wafer  with a 140 nm thermal oxide on top as substrate for fabricating our BICELL interferometer. A 420 nm thin layer of SU8 2000.5 resist was spun onto the substrate by a conventional spin coating technique. Prior to SU8 exposure using a standard optical mask aligner, a 30′@115 °C soft bake in a hot plate was performed. We used an exposure time of 80’ to pattern both 800 and 100 µm BICELLs, followed by a crosslinking bake of 5’@115 °C and development. To create the last layer of the biosensor, the nitrocellulose was spun over the SU8 cells and exposed by deep ultraviolet (DUV) with a quartz mask, inversely copied from the mask used in the first lithography step, and immersed in AR-600-55  developer, rinsed distilled-water and dried with N2.Once the integrated biochips were fabricated, vinyl stickers and glass substrates accomplished the final kit packaging, as shown in 0sig and area C from 1sig and area B). ref and area A from In order to accomplish our methodology, we obtained the Increased Relative Optical Power (IROP) signal in both type of BICELLs with the optical interrogation PoC reader already mentioned. The theoretical sensing principle behind this system has been previously explained in detail ,29. BrieWe used the label-free PoC reader and the readout optical method to optically interrogate BICELLs. The optical response of the PoC is the ΔIROP (%) value obtained as the quotient of the optical power of two interferometers: the signal and the reference interferometers ,28 (Equa0 at 0 nm of biofilm thickness and the IROP1 at a given biofilm thickness. Equation (1) comes from Reference [Equation (1): ΔIROP equation. ΔIROP is the difference between the IROPeference .® equipment (model UniCAP 100 E), where fluorescence immunoassays were developed. Briefly, we incubated increasing concentration of IgE calibrators  over cellulose CAPs functionalized with an anti-IgE monoclonal antibody . For the next steps, we added secondary labeled antibody-β-galactosidase anti-IgE-, and after, the substrate solution  for fluorescence development. Finally, we added a stop solution , and the signal assay was measured. The total time fir the processing assay was 2.5 h. All the reagents and solutions were purchased from Thermo Fisher Scientific/Phadia, Uppsala, Sweden. The measurements were performed in duplicate (n = 2 caps).We performed the reference IgE calibration curves with ImmunoCAPThe UNICAP built a curve for the low IgE concentration range (0.35–100 KU/L) and another for higher IgE ranges (2–5000 KU/L). The IgE calibrators were human IgE biomolecules at increasing concentrations in a pH 7 buffer.®. We biofunctionalized BICELLs with an anti-human IgE, which was a mouse monoclonal antibody . We used ProteinA  as a linker between nitrocellulose and anti-IgE to help anti-IgE to be correctly oriented. Bindings were accomplished using strong electrostatic forces (nitrocellulose-ProteinA) and by using affinity in the pair ProteinA-anti-IgE through a long time of incubation. We used Bovine Serum Albumin (BSA)  as a blocking agent to prevent nonspecific binding on the remaining binding surface. Finally, we measured the recognition response in increasing levels of human IgEs molecules provided by ImmunoCAP® calibrators  and compared both recognition responses .We developed an oriented immunoassay model based on the pair anti-IgE/IgE to evaluate the standard calibrators in our system and compare it with ImmunoCAPThe immobilization and recognition steps for both sensing surfaces (800 and 100 µm) are shown in 2O for ProteinA, 20 mL of PBS-T and 10 mL of H2O for anti-IgE, and 60 mL of PBS-T and 30 mL of H2O for BSA.We established the immobilization stage for the oriented antibody by incubating ProteinA . Kits were then incubated with anti-IgE , and blocked with BSA . The cleaning protocol applied was 30 mL of H® IgE calibrators. First, we performed accumulative immunoassays with increasing concentrations of calibrators in the range of 2–5000 kU/L  for 800 µm BICELLs, and second, we used calibrators in the range of 0.7–1000 kU/L  for 100 µm BICELLs. We incubated 3 µL/cell for 20 min at 36 °C in a humid environment, and then applied the cleaning protocol established . The measurements were performed in 13 biochips (n = 39 BICELLs) with 6 and 7 biochips for 800 and 100 µm BICELLs, respectively. The immobilization stage took 15 h 30 min (incubation and data processing) and each step of the accumulative assay took just 40 min (20 min and 20 min of incubation and processing). The total time of the assays was 19 h 30 min and 20 h 50 min for 2–5000 kU/L and 0.7–1000 kU/L, respectively.We developed a recognition protocol for accumulative immunoassays by incubating different concentrations of ImmunoCAPWe implemented two control experiments: a negative control to check the non-affinity between BSA and IgE, and a negative control to study the selectivity of the sensing system, for 800 and 100 μm BICELLs, respectively. We accomplished BSA control by immobilizing BSA  on the surface and identified with a 10 kU/L IgE calibrator (3 µL/cell for 20 min at 36 °C in a humid environment). We also included a negative control for surface selectivity by immobilizing aIgE in the same conditions as for non-control experiments at the immobilization stage, and performing a recognition step with protein MMP9  in a concentration of 75 ng/mL  for further studies , and theorted in ,32).BICELLs are interferometric biotransducers whose optical response changes when some biological reaction occurs on their surfaces. In the absence of a label, when a biological component is immobilized or recognized on the sensing surface of a BICELL, the biological reaction is directly detected by reading a change in the refractive index of the surface . The optWe obtained the calibration curve by measuring the ΔIROP (%) response for different concentrations of IgE calibrators. In order to analyze analyte-receptor recognition reactions, we evaluated the ΔIROP (%) in each step of the immunoassay. Taking into account that the interferometric signal came from the biomolecules adsorbed on the surface of BICELLs, there was a great interest in avoiding nonspecific binding onto them. Indeed, we accomplished a label-free recognition step due to the effort made to fully cover BICELL surfaces with anti-IgE and BSA molecules at the biofunctionalization stage. Experimental results illustrated that the interferometric peak decreased as the biomolecules concentration increased. In this work, we proved the biosensing surface with BICELLs of 800 µm, and then we reduced the size to 100 µm to enhance their sensibility. Such a size reduction allowed us to have a recognition step in lower concentrations of IgEs. It is important to remark that the ΔIROP (%) signal in calibration curves represents the difference between ΔIROP (%) at the specific concentration in the recognition stage and the ΔIROP (%) at the blocking step; hence, it is an absolute value of ΔIROP (%).For 800 µm BICELLs, the sensing recognition curve  shows ΔIFor 100 μm BICELLs, the sensing recognition curve shown in Results for control experiments are shown in ® is considered the gold standard diagnostic technique for food allergies [® curves working in a similar assay format. The comparative results are shown in the curves of ®. In the case of the biochip, the response of the PoC reader with 800 µm BICELLs (concentration range: 2–5000 kU/L) and with 100 µm BICELLs (concentration range: 0.7–1000 kU/L) are shown in graph C and D, respectively.ImmunoCAPllergies , however2 > 0.95). The LOD reported  and to other biosensors LODs reported in References [® .The response of the biochips was sensitive and with good curve correlations (R68 ng/mL ) is the ferences ,32 . The following step will be to demonstrate the applicability of the proposed system for detection of specific IgEs in human serum samples by using BICELLs biofunctionalized with molecular allergens.In this work, we performed a biofunctionalization strategy of BICELLs in order to obtain a calibration curve comparable to the ImmunoCAP