Genomic Variants Revealed by Invariably Missing Genotypes in Nelore Cattle

The development of genome-wide single nucleotide polymorphisms in blue wildebeest using the DArTseq platform

Blue wildebeest (Connochaetes taurinus taurinus) are economically important antelope that are widely utilised in the South African wildlife industry. However, very few genomic resources are available for blue wildebeest that can assist in breeding management and facilitate research. This study aimed to develop a set of genome-wide single nucleotide polymorphism (SNP) markers for blue wildebeest. The DArTseq genotyping platform, commonly used in polyploid plant species, was selected for SNP discovery. A limited number of published articles have described the use of the DArTseq platform in animals and, therefore, this study also provided a unique opportunity to assess the performance of the DArTseq platform in an animal species. A total of 20,563 SNPs, each located within a 69 bp sequence, were generated. The developed SNP markers had a high average scoring reproducibility (>99%) and a low percentage missing data (~9.21%) compared to other reduced representation sequencing approaches that have been used in animal studies. Furthermore, the number of candidate SNPs per nucleotide position decreased towards the 3' end of sequence reads, and the ratio of transitions (Ts) to transversions (Tv) remained similar for each read position. These observations indicate that there was no read position bias, such as the identification of false SNPs due to low sequencing quality, towards the tail-end of sequencing reads. The DArTseq platform was also successful in identifying a large number of informative SNPs with desirable polymorphism parameters such as a high minor allele frequency (MAF). The Bos taurus genome was used for the in silico mapping of the marker sequences and a total of 6020 (29.28%) sequences were successfully mapped against the bovine genome. The marker sequences mapped to all of the bovine chromosomes establishing the genome-wide distribution of the SNPs. Moreover, the high observed Ts:Tv ratio (2.84:1) indicate that the DArTseq platform targeted gene-rich regions of the blue wildebeest genome. Finally, functional annotation of the marker sequences revealed a wide range of different putative functions indicating that these SNP markers can be useful in functional gene studies. The DArTseq platform, therefore, represents a high-throughput, robust and cost-effective genotyping platform, which may find adoption in several other African antelope and animal species.

Genetic and phenotypic characterization of the novel mouse substrain C57BL/6N Korl with increased body weight

In inbred mouse lines, there is generally little genetic difference between individuals. This small genetic variability facilitates carrying out research on minute changes of various traits and the gene pool. Also, characterizing the diversity and detecting selective genetic and phenotypic signatures are crucial to understanding the genomic basis of a population and to identify specific patterns of evolutionary change. In this study, we investigated the underlying genetic profiles of a newly developed mouse strain, C57BL/6NKorl (Korl), established through sibling mating over 30 generations. To analyse the distinctive genomic features of Korl mice, we used whole-genome sequencing from six samples, which were compared to those of other C57BL/6N-based mouse strains. Korl strain-specific polymorphisms were identified and signatures of a selective sweep were detected. In particular, the candidate genes related to the increased body weight of the Korl strain were identified. Establishment of the genetic profile of Korl mice can provide insight into the inbreeding-induced changes to the gene pool, and help to establish this strain as a useful model for practical and targeted research purposes.