Biology subjects

Russ, I.

Publications and source records attributed to Russ, I..

3 recordsLinked to original sources

bioRxiv2024

Back to the horns: a reconstruction of the ancestral horn state through distinct types of recombination events.

BackgroundBreeding of the genetically polled animals is the desirable approach in modern cattle husbandry. At least four different genetic variants associated with polledness in cattle have been identified, suggesting genetic heterogeneity. These dominant variants have been identified on chromosome 1 between the regions of approx. 2.42 to 2.73 Mb (reference: ARS-UCD1.2), also called the POLLED locus. Among these variants, Friesian (PF, 80 kbp duplication) and Celtic (PC, 212 bp complex InDel) are the most observed in the majority of breeds in the production systems globally, such as in Holstein-Friesian (HF) and Fleckvieh (FV). While a putative causal association of PC with polledness is proven, the presence of large duplication in PF makes it difficult to prove the causality. ResultsIn this study, we conduct whole-genome sequencing (WGS) analysis of two trios exhibiting unexpected inheritance patterns related to PC and PF variants. In both instances, horned offspring were produced from mating pairs where one parent was homozygous for the polled variant, and the other was homozygous for the ancestral horned variant. By analyzing the WGS data generated using long-read sequence technology, we show that de-novo generation of the ancestral horned variant in both the offspring was the result of distinct recombination events. Specifically, in case of the HF trio, it was the result of non-allelic homologous recombination in the gametes of the sire (PF/PF), while in case of the FV trio, it was the result of allelic homologous recombination in the gametes of the dam (PC/PF). The findings from the HF trio support the hypothesis that the 80-kbp duplication is the genetic variant responsible for the polled phenotype of Friesian origin. ConclusionHere we show that different genomic arrangements in POLLED locus can lead to the emergence of de-novo ancestral horn phenotypes. These kinds of arrangements can make a reliable gene test less reliable and the derivation of the phenotype difficult to predict. Therefore, it is important for the large POLLED-locus that any deviation from the expected result is critically analyzed. Possibly some of these cases can further narrow down the sequence motif that is essential for polledness in cattle.

genomics↗

bioRxiv2022

Fine-mapping and identification of candidate causal genes for tail length in the Merinolandschaf breed

BackgroundDocking the tails of young lambs in long-tailed sheep breeds is a common practice worldwide. This practice is associated with pain, suffering and damage to the affected animals. Breeding for a shorter tail in long-tailed sheep breeds could offer one of the alternatives. This study aimed to analyze the natural tail length variation in the most common German Merino variety, and to identify possible causal alleles for the short tail phenotype segregating within a typical long-tailed breed. ResultsHaplotype-based mapping in 362 genotyped (Illumina OvineSNP50) and phenotyped Merinolandschaf lambs resulted in a genome-wide significant mapping at position 37,111,462 bp on sheep chromosome 11 and on chromosome 2 at position 94,538,115 bp (Oar_v4.0). Targeted capture sequencing of these regions in 48 selected sheep and comparative analyses of WGS data of various long and short-tailed sheep breeds as well as wild sheep subspecies identified a SNP and a SINE element as the promising candidates. The PCR genotyping of these candidates revealed complete linkage of both the candidate variants. The SINE element is located in the promotor region of HOXB13, while the SNP was located in the first exon of HOXB13 and predicted to result in a nonsynonymous mutation. ConclusionsOur approach successfully identified HOXB13 as candidate genes and the likely causal variants for tail length segregating within a typical long-tailed Merino breed. This would enable more precise breeding towards shorter tails, improve animal welfare by amplification of ancestral alleles and contribute to a better understanding of differential embryonic development.

genomics↗

bioRxiv2020

A nonsense mutation of bone morphogenetic protein-15 (BMP15) causes both infertility and increased litter size in pigs.

BackgroundAtypical external genitalia are often a sign of reproductive organ pathologies and infertility with both environmental or genetic causes, including karyotypic abnormalities. Genome-wide association studies (GWAS) provide a means for identifying chromosomal regions harboring deleterious DNA-variants causing such phenotypes. We performed a GWAS to unravel the causes of incidental cases of atypically small vulvae in German Landrace gilts. ResultsA case-control GWAS involving Illumina porcine SNP60 BeadChip-called genotypes of 17 gilts with atypically small vulvae and 1,818 control animals (fertile German Landrace sows) identified a significantly associated region on the X-chromosome (P = 8.81 x 10-43). Inspection of whole-genome sequencing data in the critical area allowed us to pinpoint a likely causal variant in the form of a nonsense mutation of bone morphogenetic protein-15 (Sscrofa11.1_X:g.44618787C>T, BMP15:p.R212X). The mutant allele occurs at a frequency of 6.2% in the German Landrace breeding population. Homozygous gilts exhibit underdeveloped, most likely not functional ovaries and are not fertile. Male carriers do not seem to manifest defects. Heterozygous sows produce 0.41{+/-}0.02 (P=4.5 x 10-83) piglets more than wildtype animals. However, the mutant alleles positive effect on litter size accompanies a negative impact on lean meat growth. ConclusionOur results provide an example for the power of GWAS in identifying the genetic causes of a fuzzy phenotype and add to the list of natural deleterious BMP15 mutations that affect fertility in a dosage-dependent manner, the first time in a poly-ovulatory species. We advise eradicating the mutant allele from the German Landrace breeding population since the adverse effects on the lean meat growth outweigh the larger litter size in heterozygous sows.

genomics↗