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Over hundreds of years, cats have been domesticated and selectively bred, resulting in numerous pedigreed breeds expedited by recent cat shows and breeding associations. Concerns have been raised about the limited breeding options and the genetic implications of inbreeding, indicating challenges in maintaining genetic diversity and accurate identification in purebred cats. In this study, genetic variability and structure were examined in 5 Thai domestic cat breeds using 15 microsatellite markers and mitochondrial DNA (mtDNA) D-loop sequencing. In total, 184 samples representing the Wichien Maat (WCM), Suphalak (SL), Khao-Manee (KM), Korat (KR), and Konja (KJ) breeds were analyzed. High genetic diversity (H o and H e  > 0.5) was observed in all breeds, and mtDNA analysis revealed two primary haplogroups (A and B) that were shared among all domestic cat breeds in Thailand and globally. However, minor differences were observed between Thai domestic cat breeds based on clustering analyses, in which a distinct genetic structure was observed in the WCM breed. This suggests that allele fixation for distinctive morphological traits has occurred in Thai domestic cat breeds that emerged in isolated regions with shared racial origins. Analysis of relationships among individuals within the breed revealed high identification efficiency in Thai domestic cat breeds (P (ID)sibs  < 10 -4 ). Additionally, diverse and effective individual identification can be ensured by optimizing marker efficiency by using only nine loci. This comprehensive genetic characterization provides valuable insights into conservation strategies and breeding practices for Thai domestic cat breeds., (© 2024. The Author(s).)

Background: The Bangkaew dog is an indigenous dog breed in the Phitsanulok province of Thailand. This breed is recognized by the Fédération Cynologique Internationale (FCI), a global canine organization. The unique traits of the Bangkaew breed lead to purebred selection for breeding, while only their traits and pedigree from parental history are recorded. Determination of the risk of inbreeding depression and the origin of unknown DNA profiles is essential due to the challenges in predicting puppy characteristics, which are crucial for breed management and conservation., Objective: This study aimed to emphasize that current allelic frequency data for the Bangkaew dog breed must be considered for precise individual identification., Methods: Approximately 82 Bangkaew dogs from various Thai localities were studied using 15 microsatellite markers for genotypic monitoring and individual identification. Maternal genetic inheritance was assessed via mtDNA D-loop analysis., Results: The results revealed high genetic diversity in the Bangkaew breed, indicating low potential for inbreeding. We also found that using a 15 loci microsatellite panel was effective for the identification of Bangkaew dogs. The optimized 10 loci microsatellite genotyping panel developed in this study presents improved identification testing efficiency, promoting both time- and cost-effectiveness., Conclusion: Analysis of microsatellite DNA markers in Bangkaew dogs using an optimized panel of 10 loci selected from 15 loci effectively facilitated individual identification. This approach not only enhances time and cost efficiency, but also provides accurate allelic frequency estimates, which are crucial for the realistic evaluation of DNA evidence., (© 2024. The Author(s) under exclusive licence to The Genetics Society of Korea.)

The majority of lizards classified in the superfamily Iguanoidea have an XX/XY sex-determination system in which sex-chromosomal linkage shows homology with chicken ( Gallus gallus ) chromosome 15 (GGA15). However, the genomics of sex chromosomes remain largely unexplored owing to the presence of homomorphic sex chromosomes in majority of the species. Recent advances in high-throughput genome complexity reduction sequencing provide an effective approach to the identification of sex-specific loci with both single-nucleotide polymorphisms (SNPs) and restriction fragment presence/absence (PA), and a better understanding of sex chromosome dynamics in Iguanoidea. In this study, we applied Diversity Arrays Technology (DArTseq TM ) in 29 phenotypic sex assignments (14 males and 15 females) of green iguana ( Iguana iguana ). We confirmed a male heterogametic (XX/XY) sex determination mode in this species, identifying 29 perfectly sex-linked SNP/PA loci and 164 moderately sex-linked SNP/PA loci, providing evidence probably indicative of XY recombination. Three loci from among the perfectly sex-linked SNP/PA loci showed partial homology with several amniote sex chromosomal linkages. The results support the hypothesis of an ancestral super-sex chromosome with overlaps of partial sex-chromosomal linkages. However, only one locus among the moderately sex-linked loci showed homology with GGA15, which suggests that the specific region homologous to GGA15 was located outside the non-recombination region but in close proximity to this region of the sex chromosome in green iguana. Therefore, the location of GGA15 might be further from the putative sex-determination locus in green iguana. This is a paradigm shift in understanding linkages on homomorphic X and Y sex chromosomes. The DArTseq platform provides an easy-to-use strategy for future research on the evolution of sex chromosomes in Iguanoidea, particularly for non-model species with homomorphic or highly cryptic sex chromosomes., (Copyright © 2020 Koomgun, Laopichienpong, Singchat, Panthum, Phatcharakullawarawat, Kraichak, Sillapaprayoon, Ahmad, Muangmai, Peyachoknagul, Duengkae, Ezaz and Srikulnath.)

Telomeres comprise tandem repeated DNA sequences that protect the ends of chromosomes from deterioration or fusion with neighboring chromosomes, and their lengths might vary with sex and age. Here, age- and sex-related telomere lengths in male and female captive Siamese cobras ( Naja kaouthia ) were investigated using quantitative real-time polymerase chain reaction based on cross-sectional data. A negative correlation was shown between telomere length and body size in males but not in females. Age-related sex differences were also recorded. Juvenile female snakes have shorter telomeres relative to males at up to 5 years of age, while body size also rapidly increases during this period. This suggests that an accelerated increase in telomere length of female cobra results from sex hormone stimulation to telomerase activity, reflecting sexually dimorphic phenotypic traits. This might also result from amplification of telomeric repeats on sex chromosomes. By contrast, female Siamese cobras older than 5 years had longer telomeres than males. Diverse sex hormone levels and oxidative stress parameters between sexes may affect telomere length., Competing Interests: None declared.

Background: Satellite DNAs (stDNAs) are highly repeated sequences that constitute large portions of any genome. The evolutionary dynamics of stDNA (e.g. copy number, nucleotide sequence, location) can, therefore, provide an insight into genome organization and evolution. We investigated the evolutionary origin of VSAREP stDNA in 17 monitor lizards (seven Asian, five Australian, and five African) at molecular and cytogenetic level., Results: Results revealed that VSAREP is conserved in the genome of Asian and Australian varanids, but not in African varanids, suggesting that these sequences are either differentiated or lost in the African varanids. Phylogenetic and arrangement network analyses revealed the existence of at least four VSAREP subfamilies. The similarity of each sequence unit within the same VSAREP subfamily from different species was higher than those of other VSAREP subfamilies belonging to the same species. Additionally, all VSAREP subfamilies isolated from the three Australian species (Varanus rosenbergi, V. gouldii, and V. acanthurus) were co-localized near the centromeric or pericentromeric regions of the macrochromosomes, except for chromosomes 3 and 4 in each Australian varanid. However, their chromosomal arrangements were different among species., Conclusions: The VSAREP stDNA family lack homogenized species-specific nucleotide positions in varanid lineage. Most VSAREP sequences were shared among varanids within the four VSAREP subfamilies. This suggests that nucleotide substitutions in each varanid species accumulated more slowly than homogenization rates in each VSAREP subfamily, resulting in non-species-specific evolution of stDNA profiles. Moreover, changes in location of VSAREP stDNA in each Australian varanid suggests a correlation with chromosomal rearrangements, leading to karyotypic differences among these species.

Sex identification provides important information for ecological and evolutionary studies, as well as benefiting snake conservation management. Traditional methods such as cloacal probing or cloacal popping are counterproductive for sex identification concerning very small species, resulting in difficulties in the management of their breeding programs. In this study, the nucleotide sequences of gametologous genes ( CTNNB1 and WAC genes) were used for the development of molecular sexing markers in caenophidian snakes. Two candidate markers were developed with the two primer sets, and successfully amplified by a single band on the agarose gel in male (ZZ) and two bands, differing in fragment sizes, in female (ZW) of 16 caenophidian snakes for CTNNB1 and 12 caenophidian snakes for WAC . Another candidate marker was developed with the primer set to amplify the specific sequence for CTNNB1 W homolog, and the PCR products were successfully obtained in a female-specific 250-bp DNA bands. The three candidate PCR sexing markers provide a simple sex identification method based on the amplification of gametologous genes, and they can be used to facilitate effective caenophidian snake conservation and management programs.