Хромосомы и видообразование у туко-туко (Ctenomys, Hystricognathi, Rodentia)

Tuco-tucos, South American rodents of the genus Ctenomys represent an interesting model of speciation. Their strict territorial and solitary life under the earth, vast but highly fragmented habitats, low migration activity were the causes of their very fast radiation. About 60 species of this genus have been described. They are found in a variety of habitats, from the mountains of the Andes to the coastal dunes of the Atlantic, from humid steppes of Pampas to dry deserts of Chaco. Tuco-tucos have a very high level of chromosomal polymorphism and polytypism based on Robertsonian and whole-arm reciprocal translocations and inversions, and can therefore be used to test different versions of chromosomal speciation hypothesis. The classic version of this hypothesis emphasizes the sterility of the hybrids, due to incorrect or incomplete chromosome synapsis in heterozygotes for rearrangements, germ cells death, chromosome nondisjunction and the generation of unbalanced gametes. The modern version of chromosomal speciation hypothesis suggests that the reduction of gene flow across chromosomal hybrid zones is due to the suppression of recombination in hybrids around the break points of rearrangements distinguishing the parental species. Field studies have not revealed strong negative effects of chromosomal heterozygosity on the fitness of the carriers. These results cast doubt on the validity of the classic version of the hypothesis. Analysis of chromosome behavior in the meiotic prophase in the chromosomal heterozygotes revealed significant changes in the frequency and distribution of recombination: crossingover suppression around the breakpoint and chiasma distalization. These changes can modulate the flow of genes between chromosomal races and amplify the divergence which has arisen due to spatial isolation. These data confirm the recombinational model of chromosomal speciation.Fil: Torgasheva, Anna A.. Novosibirsk State University; Rusia. Institute of Cytology and Genetics; RusiaFil: Savchenko, Ekaterina. Institute of Cytology and Genetics; RusiaFil: Gomez Fernandez, Maria Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Mirol, Patricia Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Borodin, Pavel M.. Novosibirsk State University; Rusia. Institute of Cytology and Genetics; Rusi

Recent advances in understanding genetic variants associated with growth, carcass and meat productivity traits in sheep (Ovis aries): an update.

peer reviewedIdentification of quantitative trait loci (QTLs) and candidate genes that affect growth intensity is a prerequisite for the marker-assisted selection of economically important traits. The number of QTL studies on sheep is relatively small in comparison to those on cattle and pigs. The current QTL sheep database - Sheep QTLdb - contains information on 1658 QTLs for 225 different traits. A few genes and markers associated with growth, carcass and meat productivity traits have been reported. The information about QTLs from the Sheep QTLdb cannot be directly used in marker-assisted selection due to the lack of essential information such as effective and reference alleles, the effect direction etc., and it requires manual curation and validation. In this study we performed a comprehensive search for QTLs focusing on single nucleotide polymorphisms (SNPs) associated with growth and meat traits in sheep. The database contains information about 156 SNP-trait associations (123 unique SNPs) and a list of 165 associated genes. The updated information is freely available at https://github.com/Defrag1236/Ovines_2018 (last access: 18 September 2019). This information can be useful for further association studies and preliminary estimation of genetic variability for economically important traits in different breeds

Multivariate Analysis Identifies Eight Novel Loci Associated with Meat Productivity Traits in Sheep.

peer reviewedDespite their economic value, sheep remain relatively poorly studied animals in terms of the number of known loci and genes associated with commercially important traits. This gap in our knowledge can be filled in by performing new genome-wide association studies (GWAS) or by re-analyzing previously documented data using novel powerful statistical methods. This study is focused on the search for new loci associated with meat productivity and carcass traits in sheep. With a multivariate approach applied to publicly available GWAS results, we identified eight novel loci associated with the meat productivity and carcass traits in sheep. Using an in silico follow-up approach, we prioritized 13 genes in these loci. One of eight novel loci near the FAM3C and WNT16 genes has been replicated in an independent sample of Russian sheep populations (N = 108). The novel loci were added to our regularly updated database increasing the number of known loci to more than 140

Identification of sex chromosomes in Eremias velox (Lacertidae, Reptilia) using lampbrush chromosome analysis

Reptiles are good objects for studying the evolution of sex determination, since they have different sex determination systems in different lineages. Lacertid lizards have been long-known for possessing ZZ/ZW type sex chromosomes. However, due to morphological uniformity of lacertid chromosomes, the Z chromosome has been only putatively cytologically identified. We used lampbrush chromosome (LBC) analysis and FISH with a W-specific probe in Eremias velox (Pallas, 1771) to unequivocally identify the ZW bivalent and investigate its meiotic behavior. The heterochromatic W chromosome is decondensed at the lampbrush stage, indicating active transcription, contrast with the highly condensed condition of the lampbrush W chromosomes in birds. We identified the Z chromosome by its chiasmatic association with the W chromosome as chromosome XIII of the 19 chromosomes in the LBC karyotype. Our findings agree with previous genetic and genomic studies, which suggested that the lacertid Z chromosome should be one of the smaller macrochromosomes

Challenges and science-based implications for modern management and conservation of European ungulate populations

Wildlife management systems face growing challenges to cope with increasingly complex interactions between wildlife populations, the environment and human activities. In this position statement, we address the most important issues characterising current ungulate conservation and management in Europe. We present some key points arising from ecological research that may be critical for a reassessment of ungulate management in the future. Ecosystem . Population sustainability . Science-basedmanagement .Wildlifemanagement .Adaptive managemen

Deep inelastic inclusive and diffractive scattering at Q2Q^2 values from 25 to 320 GeV2^2 with the ZEUS forward plug calorimeter

Deep inelastic scattering and its diffractive component, $ep \to e^{\prime}\gamma^* p \to e^{\prime}XN$, have been studied at HERA with the ZEUS detector using an integrated luminosity of 52.4 pb$^{-1}$. The $M_X$ method has been used to extract the diffractive contribution. A wide range in the centre-of-mass energy $W$ (37 -- 245 GeV), photon virtuality $Q^2$ (20 -- 450 GeV$^2$) and mass $M_X$ (0.28 -- 35 GeV) is covered. The diffractive cross section for $2 < M_X < 15$ GeV rises strongly with $W$, the rise becoming steeper as $Q^2$ increases. The data are also presented in terms of the diffractive structure function, $F^{\rm D(3)}_2$, of the proton. For fixed $Q^2$ and fixed $M_X$, \xpom F^{\rm D(3)}_2 shows a strong rise as \xpom \to 0, where \xpom is the fraction of the proton momentum carried by the Pomeron. For Bjorken-$x < 1 \cdot 10^{-3}$, \xpom F^{\rm D(3)}_2 shows positive $\log Q^2$ scaling violations, while for $x \ge 5 \cdot 10^{-3}$ negative scaling violations are observed. The diffractive structure function is compatible with being leading twist. The data show that Regge factorisation is broken.Comment: 89 pages, 27 figure