Expression analysis and characterization of an autosome-localized tesk1 gene in half-smooth tongue sole (Cynoglossus semilaevis)

Genome-wide association study identifies genomic regions associated with key reproductive traits in Korean Hanwoo cows

BACKGROUND

Conducting genome-wide association studies (GWAS) for reproductive traits in Hanwoo cattle, including age at first calving (AFC), calving interval (CI), gestation length (GL), and number of artificial inseminations per conception (NAIPC), is of paramount significance. These analyses provided a thorough exploration of the genetic basis of these traits, facilitating the identification of key markers for targeted trait improvement. Breeders can optimize their selection strategies, leading to more efficient and sustainable breeding programs, by incorporating genetic insights. This impact extends beyond individual traits and contributes to the overall productivity and profitability of the Hanwoo beef cattle industry. Ultimately, GWAS is essential in ensuring the long-term genetic resilience and adaptability of Hanwoo cattle populations. The primary goal of this study was to identify significant single nucleotide polymorphisms (SNPs) or quantitative trait loci (QTLs) associated with the studied reproductive traits and subsequently map the underlying genes that hold promise for trait improvement.

RESULTS

A genome-wide association study of reproductive traits identified 68 significant single nucleotide polymorphisms (SNPs) distributed across 29 Bos taurus autosomes (BTA). Among them, BTA14 exhibited the highest number of identified SNPs (25), whereas BTA6, BTA7, BTA8, BTA10, BTA13, BTA17, and BTA20 exhibited 8, 5, 5, 3, 8, 2, and 12 significant SNPs, respectively. Annotation of candidate genes within a 500 kb region surrounding the significant SNPs led to the identification of ten candidate genes relevant to age at first calving. These genes were: FANCG, UNC13B, TESK1, TLN1, and CREB3 on BTA8; FAM110B, UBXN2B, SDCBP, and TOX on BTA14; and MAP3K1 on BTA20. Additionally, APBA3, TCF12, and ZFR2, located on BTA7 and BTA10, were associated with the calving interval; PAX1, SGCD, and HAND1, located on BTA7 and BTA13, were linked to gestation length; and RBM47, UBE2K, and GPX8, located on BTA6 and BTA20, were linked to the number of artificial inseminations per conception in Hanwoo cows.

CONCLUSIONS

The findings of this study enhance our knowledge of the genetic factors that influence reproductive traits in Hanwoo cattle populations and provide a foundation for future breeding strategies focused on improving desirable traits in beef cattle. This research offers new evidence and insights into the genetic variants and genome regions associated with reproductive traits and contributes valuable information to guide future efforts in cattle breeding.

Molecular characterization and expression pattern of inhibin α and βb in Chinese tongue sole (Cynoglossus semilaevis)

Inhibin plays important roles in vertebrate reproduction and development. In this study, we have cloned two genes encoding inhibin subunits, inhα and ihnβb, in Chinese tongue sole. inhα consists of 1032 bp, encoding a 343 amino-acid protein. inhβb is composed of 1275 bp, encoding a 424 amino-acid protein. Phylogenetic tree analysis indicated that INHα and INHβB were independently evolved. qPCR showed that inhα expression of in male testis was higher than that in ovary and pseudomale testis, while the expression of inhβb in ovary was higher than that in male and pseudomale testis. During gonadal developmental stages, inhα expression reached highest at 120 days post hatching (dph) both in ovary and testis, then showed decline in ovary but it was first decreased and then increased in the testis. Similarly, inhβb expression in ovary was low at 50-80 dph. At 120 dph, its expression was significantly increased to the peak level, and then gradually decreased. inhβb expression in testis maintained at a low level. During the embryonic developmental stages, inhα displayed the highest expression at 32-cell stage, whereas inhβb reached the highest expression at blastula stages. In situ hybridization data showed that both of inhα and inhβb were detected in oocytes of all stages. In male testis, inhα and inhβb was localized in spermatogonia, spermatocytes, spermatozoa, sertoli and leydig cells. In pseudomale testis, inhα showed the similar pattern in male testis, while the inhβb was detected in spermatocytes and spermatozoa. These data suggested that inhα may participate the spermatogenesis and oogenesis of Chinese tongue sole, while inhβb might predominantly function in oogenesis.

Expression analysis and characterization of zglp1 in the Chinese tongue sole (Cynoglossus semilaevis)

Zinc finger GATA like protein-1 (ZGLP1) is a nuclear zinc finger protein that regulates the interaction between somatic cells and germ cells during gonad developmental process in mammals. In this study, the zglp1 of Chinese tongue sole, Cynoglossus semilaevis (cysezglp1), was cloned and characterized for the first time in fish. Cysezglp1 had an open reading frame with five exons and was located to chromosome 9. The open reading frame of cysezglp1 consisted of 1692 nucleotides and encoded a 583 amino acid polypeptide. The predicted protein contained two zinc finger structures (Znf1 and Znf2), one of which was highly homologous to the GATA-type zinc finger domain. Multiple sequence alignment showed that Znf1 was conserved across different species while Znf2 was more divergent. Through quantitative Real-time PCR (qRT-PCR), we found that cysezglp1 was predominantly expressed in gonads, and the expression level of the ovary was significantly higher than that of the testis. We compared expression level in different embryonic stages and found that cysezglp1 mRNAs were mainly expressed in the fertilized egg to the cleavage stage, subsequently declining in the blastula stage. Cysezglp1 expression was not detected from the gastrulation stage onward. In the ovary, cysezglp1 expression was detected at 120 days after hatching and expression gradually increased with the maturation of the ovary. In situ hybridization showed that the cysezglp1 was mainly expressed in oocytes. Taken together, our results suggest that cysezglp1 may play an important role in the process of oogenesis in Chinese tongue sole.

Molecular characterization of Pod1 during sex development in Chinese tongue sole (Cynoglossus semilaevis)

Pod1 encodes a Class II bHLH transcription factor involved in the development of a number of tissues such as gonad, spleen, lungs and heart. However, to date, little is known about its function in teleosts. In this study, we cloned and characterized Pod1 gene from Cynoglossus semilaevis. This gene contains three exons and two introns, with the full-length cDNA of 918 nucleotides that encodes a 183 amino acid protein with a conserved bHLH domain. Realtime quantitative PCR revealed that Pod1 was predominantly expressed in the testes of C. semilaevis. In different stages of testes development, Pod1 expression was undetectable up to 120 days after hatching (dah), and then increased at 210 dah and 1 year after hatching (yah). Furthermore, in situ hybridization (ISH) analysis revealed that Pod1 was mainly localized in the germ cells of testes, but was not detected in ovarian cells; which suggested its possible functions in spermatogenesis of C. semilaevis. The methylation profile analysis of Pod1 genomic sequence in the gonads showed that the differences in their putative promoter regions of Pod1 among ovary, male and pseudo-male testes were not obvious. Thus, further research might be needed to evaluate whether Pod1 expression is regulated by epigenetic level.

Identification and analysis of the β-catenin1 gene in half-smooth tongue sole (Cynoglossus semilaevis)

β-catenin is a key signalling molecule in the canonical Wnt pathway, which plays a role in cell adhesion, embryogenesis and sex determination. However, little is known about its function in teleosts. We cloned and characterized the full-length β-catenin1 gene from half-smooth tongue sole (Cynoglossus semilaevis), which was designated CS-β-catenin1. The CS-β-catenin1 cDNA consists of 2,346 nucleotides and encodes a protein with 782 amino acids. Although CS-β-catenin1 was transcribed in the gonads of both sexes, the level was significantly higher in ovaries compared to testes. Furthermore, the mRNA level of CS-β-catenin1 was significantly upregulated at 160 days and constantly increased until 2 years of age. In situ hybridization revealed that CS-β-catenin1 mRNA was mainly localized in oocyte cells, especially in stage I, II and III oocytes. When CS-β-catenin1 expression was inhibited by injection of quercetin in the ovaries, levels of CS-Figla and CS-foxl2 mRNA were significantly down-regulated, and CS-dmrt1 was up-regulated, which suggested that CS-β-catenin1 is a potential upstream gene of CS-Figla and is involved in the development of the ovaries, i.e., folliculogenesis.