Genetic insights: mapping sex-specific loci in Siamese cobra (Naja kaouthia) sheds light on the putative sex determining region.

The location of female-specific/linked loci identified in Siamese cobra (Naja kaouthia) previously has been determined through in silico chromosome mapping of the Indian cobra genome (N. naja) as a reference genome. In the present study, we used in silico chromosome mapping to identify sex-specific and linked loci in Siamese cobra. Many sex-specific and sex-linked loci were successfully mapped on the Z sex chromosome, with 227 of the 475 specific loci frequently mapped in a region covering 57 Mb and positioned at 38,992,675-95,561,177 bp of the Indian cobra genome (N. naja). This suggested the existence of a putative sex-determining region (SDR), with one specific locus (PA100000600) homologous to the TOPBP1 gene. The involvement of TOPBP1 gene may lead to abnormal synaptonemal complexes and meiotic chromosomal defects, resulting in male infertility. These findings offer valuable insights into the genetic basis and functional aspects of sex-specific traits in the Siamese cobra, which will contribute to our understanding of snake genetics and evolutionary biology.

Disclosing the hidden nucleotide sequences: a journey into DNA barcoding of raptor species in public repositories.

BACKGROUND: In nucleotide public repositories, studies discovered data errors which resulted in incorrect species identification of several accipitrid raptors considered for conservation. Mislabeling, particularly in cases of cryptic species complexes and closely related species, which were identified based on morphological characteristics, was discovered. Prioritizing accurate species labeling, morphological taxonomy, and voucher documentation is crucial to rectify spurious data. OBJECTIVE: Our study aimed to identify an effective DNA barcoding tool that accurately reflects the efficiency status of barcodes in raptor species (Accipitridae). METHODS: Barcode sequences, including 889 sequences from the mitochondrial cytochrome c oxidase I (COI) gene and 1052 sequences from cytochrome b (Cytb), from 150 raptor species within the Accipitridae family were analyzed. RESULTS: The highest percentage of intraspecific nearest neighbors from the nearest neighbor test was 88.05% for COI and 95.00% for Cytb, suggesting that the Cytb gene is a more suitable marker for accurately identifying raptor species and can serve as a standard region for DNA barcoding. In both datasets, a positive barcoding gap representing the difference between inter-and intra-specific sequence divergences was observed. For COI and Cytb, the cut-off score sequence divergences for species identification were 4.00% and 3.00%, respectively. CONCLUSION: Greater accuracy was demonstrated for the Cytb gene, making it the preferred primary DNA barcoding marker for raptors.