Takahisa Yamada

As one of the five major indigenous yellow cattle breeds in China, Qinchuan cattle are characterized by stable genetic performance and desirable meat quality. However, compared with imported commercial breeds, Qinchuan cattle have a relatively slow growth rate. Therefore, improving the growth rate of Qinchuan cattle has become a top priority in Qinchuan cattle breeding. The CDC10 (Septin 7) gene, an important member of the Septin family, participates in various cellular physiological processes including intracellular substance transport, cell division, cell cycle regulation, and apoptosis. Studies have repeatedly mapped the CDC10 gene to quantitative trait loci influencing growth-related traits, such as body weight and carcass weight in many beef cattle breeds. Previous study has also demonstrated the high expression of CDC10 in JB cattle with high performance for carcass weight, however, the association between CDC10 and growth-related traits in Qinchuan cattle remain unclear. Therefore, in this study, we selected five individuals each from Chinese Simmental, Mongolian cattle, Luxi cattle, and Qinchuan cattle for direct sequencing, aiming to identify mutations within the CDC10 gene of native Chinese yellow cattle. Subsequently, we performed genotyping of 367 Qinchuan cattle using the MassARRAY technology, followed by genetic diversity analysis of the identified mutations and association analysis between these sites and growth-related traits of Qinchuan cattle. This study demonstrated high expression of the CDC10 gene in Qinchuan cattle with high performance for carcass weight. Furthermore, we identified the g.61303052G>C and c.225A>G SNPs in the promoter and exon regions, respectively, as being significantly associated with multiple growth-related traits in Qinchuan cattle. The c.225A>G SNP was also found to alter the secondary structure of the CDC10 protein. These findings provide reliable molecular markers for enhancing the growth rate of Qinchuan cattle and establish a solid theoretical foundation for the development of the beef cattle industry.

In Japan, Crested Ibis Nipponia nippon is a special natural treasure and a specified national endangered species of Wild Fauna and Flora. This species became extinct in the wild in Japan in 1981. The current captive population, which was established in Japan in 1999, stems from a total of seven founders provided by China to facilitate captive breeding for release back into the wild. Since the reintroduction program was initiated in 2008, the captive population has played a critical role as the source of the released birds and hence the gene pool of the reintroduced population. In this study, several population genetic parameters and the genetic diversity of the captive population were estimated using pedigree data of individuals including all of the founders. The effective population size was estimated to be 11.2 in 2004 and 25.8 in 2021 with a gradual increase in recent years. The average degree of inbreeding was 2.2% in 2004 and 8.9% in 2018, after which it began to decline. The effective number of founders was 2.67 in 2004, rising to 4.96 in 2021, while that of non-founders was 22.8 in 2021. The value of founder genome equivalents was 4.08 in 2021, showing a consistent increase from 2.38 in 2004. The total loss of genetic diversity in 2021 was 0.123, and had decreased steadily from 0.210 in 2004. This was found to be attributed to the losses of 0.071 (58%), 0.029 (24%) and 0.020 (18%) due to the limited number of founders, the unequal genetic contributions of founders, and the population bottleneck and Mendelian sampling, respectively. In conclusion, while this study has revealed generally desirable trends of genetic diversity and population genetic parameters over about 20 years, it is suggested that further efforts should be made to increase genetic diversity beyond the current level.

Fatty acids (FAs) are a group of organic compounds that are regulated by polygenic and environmental factors and affect the taste, nutritional value, and quality of meat. Lamb meat is rich in FAs required by the human body, which has directed more attention to sheep research and meat production. The fatty acid-binding protein 4 (FABP4) gene is considered a candidate gene that can affect FA composition in livestock. Therefore, the aim of this study was to screen for genetic polymorphisms of FABP4 and confirm the association between these polymorphisms and FAs, chemical composition, and carcass traits in Sonid lambs. The results of the association study showed that g.57764667T>C, g.57764436T>G, g.57764242G>A, and g.57757988A>G were associated with the composition of certain long-chain FAs, and g.57764242G>A, g.57764436T>G, and g.57758026G>A were associated with free amino acid levels. In addition, g.57764667T>C and g.57757988A>G were associated with carcass weight and live weight in Sonid lambs. Therefore, the polymorphisms of the FABP4 gene are expected to be a genetic selection marker for superior traits in Sonid sheep breeding, which also provides new insights into how the ovine FABP4 gene affects traits of lamb quality.

Egg-laying hens undergo a specific and dramatic calcium metabolism to lay eggs with eggshells composed of calcium carbonate. Calcium metabolism is mainly regulated by vitamin D₃. Although vitamin D₃ metabolism is closely related to the deterioration of eggshell quality associated with aging and heat stress, the details of the mechanisms regulating vitamin D₃ metabolism are not clear. In mammals, the vitamin D₃ metabolite (25(OH)D₃) produced in the liver binds to the vitamin binding protein (DBP), is subsequently taken up by renal proximal tubular cells via the endocytic receptors megalin (Meg) and cubilin (CUB), and is metabolized to 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃). Therefore, the present study aimed to examine the expression and localization of Meg and CUB in the kidneys of immature chicks and mature and aged laying hens to prevent eggshell quality deterioration. As a result, we showed that as circulating 1,25(OH)₂D₃ concentrations increased from 156.0 ± 13.5 pg/mL to 815.5 ± 61.4 pg/mL with maturation in immature chicks, relative expression levels (arbitrary units; AU) of Meg and CUB mRNA in the kidneys of mature hens significantly increased 1.92- and 2.75-fold, respectively, compared to those in immature chicks. On the other hand, the Meg mRNA expression levels of mature hens did not change with age, while CUB mRNA expression levels (1.03 ± 0.11 AU) were significantly decreased compared to mature hens (2.75 ± 0.24 AU). Immunohistochemical observations showed that Meg and CUB proteins were localized to the apical membrane of renal proximal tubular epithelial cells in immature chicks, mature hens, and aged hens, and that DBP protein was observed as granular endosomes in the cytoplasm of proximal tubular cells from the apical membrane to the cell nucleus. Especially in mature hens, the endosomes were larger and more numerous than those in immature chicks. In contrast, in aged hens, DBP-containing endosomes were smaller and limited to the apical cytoplasm. These results indicate that with maturation, the expression of Meg and CUB is promoted in the renal proximal tubules of laying hens, facilitating the uptake of the 25(OH)D₃-DBP complex and its conversion to 1,25(OH)₂D₃, and regulating calcium metabolism in eggshell formation. On the other hand, it is suggested that the age-related decrease in CUB expression suppresses the uptake of the 25(OH)D₃-DBP complex in the kidney, resulting in a deterioration of eggshell quality.

Heat stress is one of the adverse effects on productivity in the livestock. In pig, it is shown that the growth rate decreases under heat stress conditions. Moreover, it is reported that genetic variation is associated with heat stress tolerance. However, much less study has been done on identification of candidate genes and pathways associated with heat stress tolerance in pig. Here, this study aimed to identify the candidate genes and pathways associated with heat stress tolerance for growth rate in pig using microarray and RNA-seq. These methods were used to investigate differences in small intestine gene expression profiles among two finishing pig groups (high-tolerant and low-tolerant) with divergent heat stress tolerance for growth rate under heat stress conditions and control finishing pig group under non-heat stress conditions. The results of microarray and RNA-seq, respectively, showed that a total of 1277 genes for microarray and 2970 genes for RNA-seq were regarded as the genes showing heat stress responsive differential expression profiles associated with heat stress tolerance, and also 825 genes for microarray and 1233 genes for RNA-seq were upregulated and 452 genes for microarray and 1737 genes for RNA-seq were downregulated in hightolerant group as compared to low-tolerant group. Among these genes, we found overrepresentation of a set of genes involved in TGFβ signaling pathway. The gene set exhibited differential expression profiles between hightolerant and low-tolerant groups which are reported to lead to activation of TGFβ signaling pathway, resulting in cell differentiation and regeneration of intestinal cell in hightolerant group. These results suggested that the TGFβ signaling pathway was identified as the intriguing pathway showing heat stress-responsive activation associated with heat stress tolerance for growth rate in small intestine of finishing pig.

Intramuscular fat content and marbling affecting meat quality are important economic traits in beef cattle. CDC10 (cell division cycle 10 or Septin 7), a member of the septin family involved in cellular proliferation, was considered as a functional and positional candidate gene for beef marbling. In a previous study, we revealed that the expression levels of CDC10 were also positively correlated with marbling scores in Japanese Black cattle. However, the regulatory mechanism of the CDC10 gene on IMF deposition in cattle remains unclear. In the present study, flow cytometry, EdU proliferation assays, and Oil Red O staining results showed that overexpression of CDC10 could promote the differentiation of bovine intramuscular preadipocyte (BIMP) and 3T3-L1 cells, whereas knockdown of CDC10 resulted in the opposite consequences. Furthermore, quantitative PCR and Western blotting results showed that overexpression of CDC10 could promote the expression levels of adipogenic marker genes PPARγ and C/EBPα at both mRNA and protein levels in BIMP and 3T3-L1 cells, whereas knockdown of CDC10 resulted in the opposite consequences. Our results provide new insights into the regulatory roles of CDC10 in adipocytes in animals.

Fatty acid (FA) composition has an important impact on the nutrition and flavor of meat, and on consumer health, and is receiving more attention in the sheep industry. This study aimed to evaluate the relationship between the expression levels of the CAST gene and the FA composition in the longissimus thoracis (LL) muscle, to identify novel variants of CAST, and to perform association analysis with the FA composition in grazing Sonid lambs. The correlation results showed that high expression levels of CAST are correlated with better FA compositions and classes in LL. For association studies, the results showed that c.1210C>T and c.1437G>A in LD-M, and c.2097C>T mutations are associated with some compositions and classes of FA in the LL of grazing Sonid sheep. Two missense c.646G>C (G216R) and c.1210C>T (R404C) mutations were predicted to influence the Calpain_inhib domains of CAST. Thus, the correlation results and associated mutations are expected to be genetic selection markers for the FA composition and meat quality of grazing Sonid lamb muscle and provide new insights into sheep meat quality traits influenced by the ovine CAST gene.

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Marbling is characterized by the amount and distribution of intramuscular fat (IMF). The AKIRIN2, TTN, EDG1, and MYBPC1 genes are well-known marbling-related genes, which were first identified in Japanese Black beef cattle. The objectives of this study were to analyze the correlation of the expression levels of these genes in the longissimus muscle (LM) with IMF content, and the associations between the single nucleotide polymorphisms (SNPs) in these genes and IMF content in Chinese Qinchuan cattle (n = 350). The association analyses showed that the g.42041062G>T SNP in the EDG1 gene was significantly associated with IMF content in Qinchuan (p < 0.05). Further, the expressions of the EDG1 and MYBPC1 were up-regulated (p < 0.05) in LM of Qinchuan cattle group with low IMF content. Down-regulations of the AKIRIN2 and TTN genes (p < 0.05 and p < 0.01, respectively) were observed in the Qinchuan cattle group with high IMF content. These results suggest possible effects of the expression levels of selected genes on IMF content in the LM, and the g.42041062G>T SNP in the EDG1 gene might be useful as a molecular marker for IMF content in Qinchuan.

The Japanese captive population of Crested Ibis (Nipponia nippon) has rapidly increased, and reintroduction programs were initiated on Sado Island in 2008. The Japanese captive population, however, was founded by only 5 individuals originating from the Chinese captive population. Because efforts were directed toward preserving genetic diversity in the captive population, it was appropriate to consider genetic diversity in the reintroduced population to evaluate its potential to survive in the wild, where environmental changes are more significant than in captivity. The purpose of this study was to determine the number of individuals to release in the future to preserve genetic diversity of the reintroduced population. We simulated the probability that the reintroduced population after 50 years would retain a rare allele existing in the captive population, based on demographic parameters obtained from either the Japanese captive or reintroduced populations, or Chinese wild populations. As a result, the 10–15 individuals currently released in the annual reintroduction would be the number needed to be released each year over 50 years to retain the rare allele with a frequency in the captive population of 0.05 with a >90% probability. Therefore, the current reintroduction program seems reasonable and should be continued.