Genome-wide sequence divergence of satellite DNA could underlie meiotic failure in male hybrids of bighead catfish and North African catfish (Clarias, Clariidae).

Hybrid sterility, a hallmark of postzygotic isolation, arises from parental genome divergence disrupting meiosis. While chromosomal incompatibility is often implicated, the underlying mechanisms remain unclear. This study investigated meiotic behavior and genome-wide divergence in bighead catfish (C. macrocephalus), North African catfish (C. gariepinus), and their sterile male hybrids (important in aquaculture). Repetitive DNA analysis using bioinformatics and cytogenetics revealed significant divergence in satellite DNA (satDNA) families between parental species. Notably, one hybrid exhibited successful meiosis and spermatozoa production, suggesting potential variation in sterility expression. Our findings suggest that genome-wide satDNA divergence, rather than chromosome number differences, likely contributes to meiotic failure and male sterility in these catfish hybrids.

Small but Mighty: Genetic Diversity of the Thai Ridgeback Dog Population.

Originating in Thailand, the Thai Ridgeback dog is known for its unique fur ridge that grows in the opposite direction along its back. Selective breeding and a limited populations in Thailand have led to significant close inbreeding among related individuals. The current Thai Ridgeback population is assumed to have experienced a loss of genetic diversity and bottleneck events. Furthermore, studies on the genetic diversity and structure of Thai Ridgeback dogs are limited. Therefore, the aim of this study was to assess the genetic diversity in Thai Ridgeback dogs. Microsatellite genotyping and mitochondrial DNA D-loop sequences were used to assess genetic diversity in 105 Thai Ridgeback dogs from various farms throughout Thailand. Significant genetic diversity and minimal inbreeding were observed in the current Thai Ridgeback population. Signs of bottlenecks were not observed because the exchange of genetic material among Thai Ridgeback owners effectively preserved the genetic diversity. Moreover, the genetic parameters in this study supported owner-to-owner exchanges animals for mating programs. To sustain the genetic diversity of Thai Ridgeback dogs, the use of genetic parameters to manage genetic closeness while preserving breed characteristics is essential. These data are crucial for ensuring demographic stability, which is pivotal for long-term conservation and effective population management.

New record of Gracilariaphuquocensis (Gracilariaceae, Rhodophyta) in the Philippines.

While reliance on morphology has been at the expense of clearly distinguishing gracilarioid species, molecular data have proven to be more reliable in discriminating between taxa. Gracilariaphuquocensis was originally described, based on materials collected from Vietnam. Since it was described in 2020, there have been no further reports of this species. Meanwhile, a question has been raised as to whether the identity of a rhodophyte gracilarioid alga collected from the Philippines that has been referred to as an unidentified species of Gracilaria, could be G.phuquocensis. Based on comparative morpho-anatomical features and a molecular phylogeny based on rbcL gene sequences, establishing the identity of the Philippine material has led to the finding of the new record of G.phuquocensis outside its type locality. In addition to the discovery of G.phuquocensis in the Philippines, the species here is also identified as a newly-reported host for the adelphoparasite resembling Gracilariababae.

Optimizing Bangkaew dog breed identification using DNA technology.

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.

Shared alleles and genetic structures in different Thai domestic cat breeds: the possible influence of common racial origins.

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 (Ho and He > 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.

Research Note: Possible influence of thermal selection on patterns of HSP70 and HSP90 gene polymorphisms in Thai indigenous and local chicken breeds and red junglefowls.

The thermal stress caused by global climate change adversely affects the welfare, productivity, and reproductive performance of farm animals, including chickens, and causes substantial economic losses. However, the understanding of the genetic basis of the indigenous chicken adaptation to high ambient temperatures is limited. Hence, to reveal the genetic basis of thermal stress adaptation in chickens, this study investigated polymorphisms in the heat shock protein 70 (HSP70) and HSP90 genes, known mechanisms of cellular defense against thermal stress in indigenous and local chicken breeds and red junglefowls in Thailand. The result revealed seven alleles of the HSP70 gene. One allele exhibited a missense mutation, where an amino acid changed from Asn to His in the substrate-binding and peptide-binding domains, which is exclusive to the Lao Pa Koi chicken breed. Twenty new alleles with silent mutations in the HSP90 gene highlighted its greater complexity. Despite this diversity, distinct population structures were not found for either HSP70 or HSP90, which suggests incomplete impact on the domestication process and selection. The low genetic diversity, shown by the sharing of alleles between red junglefowls and Thai indigenous and local chicken breeds, aligns with the hypothesis that these alleles have undergone selection in tropical regions, such as Thailand. Selection signature analysis suggests the purifying selection of HSP70 for thermotolerance. This study provides valuable insights for enhancing the conservation of genetic resources with thermotolerant traits, which are essential for developing breeding programs to increase poultry production in the context of global climate change.

Samae Dam Chicken: A variety of the Pradu Hang Dam breed revealed from microsatellite genotyping data.

Objective: The remarkable adaptability to the environment, high growth rate, meat with good taste and aroma, and ornamental appearance of the Pradu Hang Dam (PDH) and Samae Dam (SD) chickens make them valuable for improvement of poultry production to enhance food security. However, despite their close phenotypic similarity, distinct classification of PDH and SD chickens remains controversial. Thus, this study aimed to clarify genetic origins and variation between PDH and SD chickens, genetic diversity and structures of PDH and SD chickens. Methods: This study analyzed 5 populations of PDH and 2 populations of SD chickens using 28 microsatellite markers and compared with those of other indigenous and local chicken breeds using Thailand's "The Siam Chicken Bioresource Project" database. Results: Considerably high genetic variability was observed within PDH (370 total alleles; 4.086 ± 0.312 alleles/locus) and SD chickens (179 total alleles; 3.607 ± 0.349 alleles/locus). A partial overlap of gene pools was observed between SD chickens from the Department of Livestock, Uthai Thani (SD1) and PDH chickens, suggesting a potentially close relationship between the two chicken breeds. A gene pool that is partially overlapped with that of the red junglefowl was observed in the SD chicken population from the Sanhawat Farm Uthai Thani population (SD2). Distinct subclusters were observed within SD chickens, indicating the possibility that genetic differentiation occurred early in the process of establishment of SD chickens. Conclusion: These findings could offer valuable insights into genetic verification of Thai local chicken breeds and their sustainable conservation and utilization.

Weak purifying selection in allelic diversity of the ADSL gene in indigenous and local chicken breeds and red junglefowl in Thailand.

High levels of purine and uric acid, which are associated with health issues such as gout and cardiovascular disease, are found in the meat of fast-growing broiler chickens, which raises concerns about the quality of chicken meat and the health of the consumers who consume it. High genetic homogeneity and uniformity, particularly in genes involved in the synthesis of inosine monophosphate (IMP) and subsequent process of purine synthesis, which are associated with the meat quality, are exhibited in commercial broiler chickens owing to intensive inbreeding programs. Adenosine succinate lyase (ADSL) is a key enzyme involved in de novo purine biosynthetic pathway and its genetic polymorphisms affect IMP metabolism and purine content. In this study, we investigated the polymorphism of the ADSL gene in indigenous and local chicken breeds and red junglefowl in Thailand, using metabarcoding and genetic diversity analyses. Five alleles with 73 single nucleotide polymorphisms in exon 2, including missense and silent mutations, which may act on the synthesis efficiency of IMP and purine. Their protein structures revealed changes in amino acid composition that may affect ADSL enzyme activity. Weak purifying selection in these ADSL alleles was observed in the chicken population studied, implying that the variants have minor fitness impacts and a greater probability of fixation of beneficial mutations than strong purifying selection. A potential selective sweep was observed in Mae Hong Son chickens, whose purine content was lower than that in other breeds. This suggests a potential correlation between variations of the ADSL gene and reduced purine content and an impact of ADSL expression on the quality of chicken meat. However, further studies are required to validate its potential availability as a genetic marker for selecting useful traits that are beneficial to human health and well-being.

Questioning inbreeding: Could outbreeding affect productivity in the North African catfish in Thailand?

The North African catfish (Clarias gariepinus) is a significant species in aquaculture, which is crucial for ensuring food and nutrition security. Their high adaptability to diverse environments has led to an increase in the number of farms that are available for their production. However, long-term closed breeding adversely affects their reproductive performance, leading to a decrease in production efficiency. This is possibly caused by inbreeding depression. To investigate the root cause of this issue, the genetic diversity of captive North African catfish populations was assessed in this study. Microsatellite genotyping and mitochondrial DNA D-loop sequencing were applied to 136 catfish specimens, collected from three populations captured for breeding in Thailand. Interestingly, extremely low inbreeding coefficients were obtained within each population, and distinct genetic diversity was observed among the three populations, indicating that their genetic origins are markedly different. This suggests that outbreeding depression by genetic admixture among currently captured populations of different origins may account for the low productivity of the North African catfish in Thailand. Genetic improvement of the North African catfish populations is required by introducing new populations whose origins are clearly known. This strategy should be systematically integrated into breeding programs to establish an ideal founder stock for selective breeding.

Genome-wide SNP analysis provides insights into the XX/XY sex-determination system in silver barb (Barbonymus gonionotus).

Silver barb (Barbonymus gonionotus) is among the most economically important freshwater fish species in Thailand. It ranks fourth in economic value and third in production weight for fisheries and culture in Thailand. An XX/XY sex-determination system based on gynogenesis was previously reported for this fish. In this study, the molecular basis underlying the sex-determination system was further investigated. Genome-wide single-nucleotide polymorphism data were generated for 32 captive-bred silver barb individuals, previously scored by phenotypic sex, to identify sex-linked regions associated with sex determination. Sixty-three male-linked loci, indicating putative XY chromosomes, were identified. Male-specific loci were not observed, which indicates that the putative Y chromosome is young and the sex determination region is cryptic. A homology search revealed that most male-linked loci were homologous to the Mariner/Tc1 and Gypsy transposable elements and are probably the remnants of an initial accumulation of repeats on the Y chromosome from the early stages of sex chromosome differentiation. This research provides convincing insights into the mechanism of sex determination and reveals the potential sex determination regions in silver barb. The study provides the basic data necessary for increasing the commercial value of silver barbs through genetic improvements.