Improvements in Tritrichomonas foetus molecular testing
Bovine trichomoniasis is a sexually transmitted disease that results in infertility, abortion, and calf age variability. To date, management strategies include testing for Tritrichomonas foetus and culling of infected males. Challenges associated with testing include cost of culture medium, time and labor burden of sample incubation and processing, and adverse effects of bacterial growth on detection sensitivity. To overcome these challenges, we developed a direct reverse-transcription quantitative real-time PCR (direct RT-qPCR) utilizing smegma, eliminating the use of culture medium. In an analysis of 166 field samples (56 positives and 110 negatives as determined using microscopic reading of cultures as the reference test), the direct RT-qPCR exhibited 100% diagnostic sensitivity and 100% specificity, whereas the currently employed qPCR (culture qPCR), which utilizes cultured samples, exhibited 95% diagnostic sensitivity and 100% specificity. Agreement between direct RT-qPCR and culture qPCR was 98%. Moreover, direct RT-qPCR identified 3 more positive samples and exhibited lower quantification cycle (Cq) values among positives by culture reading than did culture qPCR (direct RT-qPCR Cq range = 14.6–32.3 vs. culture qPCR Cq range = 18.7–37.4). The direct RT-qPCR enables simplified sample collection, elimination of culture medium, faster results, applicability in cows, and lower cost than culture qPCR.
Early pathogenesis and pathology of Tritrichomonas foetus infection in virgin heifers.
Abstract The mating of a bull infected with Tritrichomonas foetus var. brisbane to 20 susceptible nulliparous cows resulted in 19 of the animals becoming infected after a single service. After T. foetus infection was confirmed, 2 cows were killed at approximately 2 week intervals in the order of mating to the bull. All cows were killed within 100 days of the commencement of mating. Eleven of the 18 cows that were killed 28 days or more after mating were pregnant. T. foetus was cultured from several areas of the genital tract in the 8 cows killed from 15 to 50 days after mating. The organism was found in the vagina and cervix of all cows, in the uterus in 6 and in the oviducts of 4. No macroscopic or microscopic lesions attributable to T. foetus infection were seen in any of these animals. Of the 12 cows killed from 60 to 100 days after mating 7 had acute or chronic microscopic lesions in many areas of the genital tract. Abortion was pending in 2 that were mated at 60 and 95 days previously, and a third cow had a pyometra. The remaining 5 cows had no macroscopic or microscopic lesions and T. foetus was cultured from the cervix and vagina of 1 animal only. T. foetus appeared to be confined to the surface secretions in the genital tract.
Testosterone levels, handedness and sex ratio at birth.
Geschwind has hypothesized that levels of androgens in utero affect postnatal laterality preferences, high levels being associated with left-handedness of offspring. I have hypothesized that high parental androgen levels at the time of conception are associated with subsequent male births. However, left-handed parents seem to produce an excess of female, not male, offspring. This finding could be reconciled with the two hypotheses if individuals who were exposed to high levels of androgens in utero had low circulating levels in adulthood. Some evidence for this loophole is reviewed here. Lyster & Lloyd (1987, J. theor. Biol. 126, 125) have reported that (consistent with the hypotheses) index left-handed men have an excess of brothers; but, contrary to the hypotheses, index left-handed women have an excess of sisters. Accordingly these authors proposed that left-handedness in females is associated not with high levels of androgen in utero, but with a "sensitivity" to it. If such sensitivity were associated with low androgen levels, it might explain an excess of sisters among the sibs of left-handed women. It is shown here that evidence in agreement with this hypothesis (though not discriminating between it and Geschwind's) suggests that the sex ratios of offspring of LH male x RH female and of RH male x LH female matings, are both low.