Altering the Binding Properties of PRDM9 Partially Restores Fertility across the Species Boundary

Sterility or subfertility of male hybrid offspring is commonly observed. This phenomenon contributes to reproductive barriers between the parental populations, an early step in the process of speciation. One frequent cause of such infertility is a failure of proper chromosome pairing during male meiosis. In subspecies of the house mouse, the likelihood of successful chromosome synapsis is improved by the binding of the histone methyltransferase PRDM9 to both chromosome homologs at matching positions. Using genetic manipulation, we altered PRDM9 binding to occur more often at matched sites, and find that chromosome pairing defects can be rescued, not only in an intersubspecific cross, but also between distinct species. Using different engineered variants, we demonstrate a quantitative link between the degree of matched homolog binding, chromosome synapsis, and rescue of fertility in hybrids between Mus musculus and Mus spretus. The resulting partial restoration of fertility reveals additional mechanisms at play that act to lock-in the reproductive isolation between these two species.

Response Corridors for Blunt Impacts to the Back

Corridors for the biofidelity of blunt impact to the back are important for sled and crash testing with Anthropomorphic Test Devices (ATDs). The Hybrid III is used in rear sled tests as part of Federal Motor Vehicle Safety Standards (FMVSS) 202a. The only corridor for biofidelity is the neck extension. Eight Post Mortem Human Subjects (PMHS) were subjected to 20 blunt impacts with a 15.2 cm (6 in.) diameter pendulum weighing 23.4 kg. The impact was below T1 at 4.5 m/s and 6.7 m/s and below T6 at 4.5 m/s centered on the back. Head, neck, and chest responses were reported in 2001 [8]. In this study, the responses were scaled to the 50th male Hybrid III, and corridors were determined defining biofidelity for blunt impacts to the back. The scaled data gives an average peak force of 3.44 kN ± 0.74 kN at T1 and 4.5 m/s, 5.08 kN ± 1.35 kN at T1 and 6.7 ms, and 3.4 kN ± 1.2 kN at T6 and 4.5 m/s. The corresponding scaled deflection was 44.0 ± 19.7 mm, 60.2 ± 21.2 mm, and 53.1 ± 16.5 mm. The average stiffness of the back was 1.21 kN/cm at T1 and 4.5 m/s, 1.17 kN/cm at T1 and 6.7 m/s, and 1.14 kN/cm at T6 and 4.5 m/s. The corridors help to define biofidelity and can be used to assess the performance of the Hybrid III, Biofidelic Rear Impact Dummy (BioRID) II, and other ATDs.

Reproductive Isolation Between Taxonomically Controversial Forms of the Gray Voles (Microtus, Rodentia; Arvicolinae): Cytological Mechanisms and Taxonomical Implications

The formation of hybrid sterility is an important stage of speciation. The voles of the genus Microtus, which is the most speciose genus of rodents, provide a good model for studying the cytological mechanisms of hybrid sterility. The voles of the “mystacinus” group of the subgenus Microtus (2n = 54) comprising several recently diverged forms with unclear taxonomic status are especially interesting. To resolve the taxonomic status of Microtus mystacinus and Microtus kermanensis, we crossed both with Microtus rossiaemeridionalis, and M. kermanensis alone with Microtus arvalis “obscurus” and M. transcaspicus and examined the reproductive performance of their F1 hybrids. All interspecies male hybrids were sterile. Female M. kermanensis × M. arvalis and M. kermanensis × M. transcaspicus hybrids were sterile as well. Therefore, M. mystacinus, M. kermanensis, and M. rossiaemeridionalis could be considered valid species. To gain an insight into the cytological mechanisms of male hybrid sterility, we carried out a histological analysis of spermatogenesis and a cytological analysis of chromosome synapsis, recombination, and epigenetic chromatin modifications in the germ cells of the hybrids using immunolocalization of key meiotic proteins. The hybrids showed wide variation in the onset of spermatogenesis arrest stage, from mature (although abnormal) spermatozoa to spermatogonia only. Chromosome asynapsis was apparently the main cause of meiotic arrest. The degree of asynapsis varied widely across cells, individuals, and the crosses—from partial asynapsis of several small bivalents to complete asynapsis of all chromosomes. The asynapsis was accompanied by a delayed repair of DNA double-strand breaks marked by RAD51 antibodies and silencing of unpaired chromatin marked by γH2A.X antibodies. Overall, the severity of disturbances in spermatogenesis in general and in chromosome synapsis in particular increased in the hybrids with an increase in the phylogenetic distance between their parental species.

ON TESTING THE SHOCK-ABSORBING SEATS FOR HELICOPTER CREW MEMBERS

Recommendations on improving the dynamic performance of shock-absorbing seats for helicopter pilots resulted from analysis of the Russian pilots' anthropometric data and helicopter 3-d attitude and position during emergency landing. The idea is to complement the existing list of impact tests with two more tests in which the impact vector will be perpendicular to the test-platform horizontal. One of these tests should be performed with a light anthropomorphic test device (Hybrid-III) representing a 5-percentile female and the other, heavy Hybrid-III representing a 95-percentile male. For horizontal impact testing, the 50-percentile male Hybrid-III should be replaced by the 95-percentile Hybrid-III.

PENGARUH PEMBERIAN RANSUM KOMERSIL DENGAN PENAMBAHAN BAHAN PAKAN LOKAL TERFERMENTASI AMONIUM SULFAT DAN UREA TERHADAP BOBOT HIDUP, BOBOT KARKAS, DAN BOBOT GIBLET ITIK HIBRIDA JANTAN

This research aimed to know the influence of giving a commercial ration with addition of local feed fermented with ammonium sulphate and urea and to find out the best ration on live weight, carcass weight, and giblet weight of male hybrid ducks. This research was carried out in July 2018--August 2018 in the cage of ducks, Department of Animal Husbandry, Faculty of Agriculture, Lampung University. Research material used consisted of 40 male hybrid ducks. This study used a Completely Randomized Design (CRD). Data was analysed using analysis of variance at 5% level of significance. The results showed that there was no different effect of treatments on live weight (1,552--1,717 g / duck), carcass weight (805,6--1.016 g / duck), and giblet weight (106.8--118.45 g /duck) of male hybrid ducks. Keywords: Carcass weight, Giblet weight, Live weight, Male hybrid duck.

Male hybrid sterility in the cattle–yak and other bovines: a review

Hybridization is important for both animal breeders attempting to fix new phenotypic traits and researchers trying to unravel the mechanism of reproductive barriers in hybrid species and the process of speciation. In interspecies animal hybrids, gains made in terms of adaptation to environmental conditions and hybrid vigour may be offset by reduced fertility or sterility. Bovine hybrids exhibit remarkable hybrid vigour compared to their parents. However, the F1 male hybrid exhibits sterility whereas the female is fertile. This male-biased sterility is consistent with Haldane’s rule where heterogametic sex is preferentially rare, absent, or sterile in the progeny of two different species The obstacle of fixing favourable traits and passing them to subsequent generations due to the male sterility is a major setback in improving the reproductive potential of bovines through hybridization. Multi-perspective approaches such as molecular genetics, proteomics, transcriptomics, physiology and endocrinology have been used by several researchers over the past decade in an attempt to unravel the potential mechanisms underlying male hybrid sterility. However, the mechanism of sterility in the hybrid male is still not completely unravelled. This review seeks to provide an update of the mechanisms of the sterility in the cattle-yak and other bovines.

Hybridization fluctuates with rainfall in Darwin’s tree finches

Hybridization in natural populations may be an adaptive response to shifting climatic regimes, but understanding this can be limited by the timing of sampling effort and confident identification of hybrids. On the Galapagos Islands, Darwin’s finches regularly hybridize; the islands also show extreme annual variation in rainfall, but the effect of annual rainfall on the frequency of finch hybridization is little known. Across a 20-year period on Floreana Island, we compare patterns of hybridization in sympatric Darwin’s tree finches (N = 425; Camaryhnchus spp.) and test for an effect of annual rainfall on (1) the frequency of hybrids (C. pauper × C. parvulus) and (2) the percentage of male hybrid birds produced per year (hybrid recruitment). Annual rainfall correlated with recruitment positively for hybrids, negatively for C. parvulus and not at all for C. pauper. Furthermore, the percentage of hybrids (range: 12–56%) and C. parvulus did not change with sampling year, but the critically endangered C. pauper declined. Our findings indicate that hybrid recruitment is recurring and variable according to annual rainfall in Camarhynchus Darwin’s finches.

Pengaruh Perbedaan Rasio Indukan Puyuh Jantan Hybrid dan Puyuh Betina Jepang (Coturnix coturnix japonica) terhadap Kualitas DOQ

Abstrak. Permasalahan yang terjadi saat ini di berbagai peternakan puyuh ialah penyediaan bibit sendiri sebagai indukan dengan cara perkawinan yang ada hubungan kekerabatan dekat (sedarah) tanpa persilangan dengan bibit baru dari luar. Akibatnya bibit-bibit yang dihasilkan dari hasil perkawinan tersebut mengalami kecacatan karena pengaruh inbreeding yang telah melampaui batas. Salah satu upaya untuk meningkatkan kualitas puyuh yaitu dengan dilakukannya perkawinan silang (Cross Breeding) pada indukan puyuh. Perkawinan silang ini sangat baik jika dilakukan antara dua jenis puyuh yang memiliki kelebihan yang berbeda seperti puyuh Jepang (Coturnix coturnix japonica) dan puyuh Hybrid. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh perbedaan rasio indukan puyuh jantan Hybrid dan puyuh betina Jepang (Coturnix coturnix japonica) terhadap kualitas DOQ. Parameter yang diamati yaitu fertilitas, kematian embrio, daya tetas, berat tetas, mortalitas dan rasio DOQ jantan betina. Berdasarkan data hasil penelitian dapat disimpulkan bahwa perbedaan rasio indukan puyuh Hybrid jantan dan puyuh betina Jepang tidak memberikan pengaruh yang nyata terhadap fertilitas, kematian embrio, daya tetas, berat tetas, mortalitas dan rasio DOQ jantan betina. Meskipun tidak berbeda nyata, fertilitas dan daya tetas tertinggi hasil persilangan puyuh jantan Hybrid dan puyuh betina Jepang (Coturnix coturnix japonica) yaitu pada P4 dengan perbandingan indukan dan pejantan 4:4.(The Effect of Differences in the Ratio of Sires of Male Hybrid Quails and Japanese Female Quails (Coturnix coturnix japonica) to DOQ Quality)Abstract. The problem that is currently occurring at various quail farms is the supply of own seeds as sires by means of marriage that have close kinship (blood) without crossing with new seeds from outside. As a result the seeds produced from the results of the marriage experience disability because of the influence of inbreeding that has exceeded the limit. One effort to improve the quality of quail is by doing cross breeding on quail breeders. Cross - breeding is very good if done between two types of quail that have different advantages such as Japanese quail (Coturnix coturnix japonica) and Hybrid quail. The purpose of this study was to determine the effect of differences in the ratio of sires of male hybrid quails and Japanese female quails (Coturnix coturnix japonica) to DOQ quality. The parameters observed were fertility, embryo death, hatchability, hatch weight, mortality and female DOQ ratio. Based on the research data it can be concluded that the differences in the ratio of male hybrid quail and Jap anese quail broodstock did not have a significant effect on fertility, embryo death, hatchability, hatch weight, female DOQ mortality and ratio. Although not significantly different, fertility and highest hatchability were the result of hybrid crosses of male quail and Japanese female quail (Coturnix coturnix japonica), namely in P4 with a 4: 4 sires and male ratio.