Transcriptome-Wide m6A Analysis Provides Novel Insights Into Testicular Development and Spermatogenesis in Xia-Nan Cattle.

Testis is the primary organ of the male reproductive tract in mammals that plays a substantial role in spermatogenesis. Improvement of our knowledge regarding the molecular mechanisms in testicular development and spermatogenesis will be reflected in producing spermatozoa of superior fertility. Evidence showed that N6-Methyladenosine (m6A) plays a dynamic role in post-transcription gene expression regulation and is strongly associated with production traits. However, the role of m6A in bovine testis has not been investigated yet. In this study, we conducted MeRIP-Seq analysis to explore the expression profiles of the m6A and its potential mechanism underlying spermatogenesis in nine bovine testes at three developmental stages (prepuberty, puberty and postpuberty). The experimental animals with triplicate in each stage were chosen based on their semen volume and sperm motility except for the prepuberty bulls and used for testes collection. By applying MeRIP-Seq analysis, a total of 8,774 m6A peaks and 6,206 m6A genes among the studied groups were identified. All the detected peaks were found to be mainly enriched in the coding region and 3'- untranslated regions. The cross-analysis of m6A and mRNA expression exhibited 502 genes with concomitant changes in the mRNA expression and m6A modification. Notably, 30 candidate genes were located in the largest network of protein-protein interactions. Interestingly, four key node genes (PLK4, PTEN, EGR1, and PSME4) were associated with the regulation of mammal testis development and spermatogenesis. This study is the first to present a map of RNA m6A modification in bovine testes at distinct ages, and provides new insights into m6A topology and related molecular mechanisms underlying bovine spermatogenesis, and establishes a basis for further studies on spermatogenesis in mammals.

Cloning and expression analysis of zygote arrest 1 (Zar1) in New Zealand white rabbits.

Zygote arrest 1 (Zar1) is an oocyte-specific maternal-effect gene. Previous studies indicate that Zar1 plays important role in early embryo development, but little is known about its function in rabbit. The objectives of this study were to clone the New Zealand white rabbit Zar1 gene and to investigate its expression in various organs in groups of animals with different reproductive traits.We obtained a 709-bp Zar1 cDNA fragment consisting of an 8-bp exon 1, 161-bp exon 2, 75-bp exon 3, 271-bp exon 4 and 194-bp 3'sequences. The rabbit Zar1 nucleotide sequence showed per cent identities of 91, 88, 88, 87, 86, 87, 76 and 82% with Zar1 orthologues in human, cattle, sheep, pig, mouse, rat, zebrafish and Xenopus laevis, respectively, indicating a high homology with other species and evolutionary conservation. Quantitative real-time polymerase chain reaction analyses revealed nonoocyte-specific Zar1 expression, with expression in spleen, lung, ovary, uterus, heart, liver and kidney. The expression level was highest in the lung. This study may lay the theoretical foundation for the study of ZAR1's biological function.

Molecular characterization of the porcine JHDM1A gene associated with average daily gain: evaluation its role in skeletal muscle development and growth.

JHDM1A, a member of the JHDM (JmjC-domain-containing histone demethylase) family, plays an central role in gene silencing, cell cycle, cell growth and cancer development through histone H3K36 demethylation modification. Here reported the cloning, expression, chromosomal location and association analysis with growth traits of porcine JHDM1A gene. Sequence analysis showed that the porcine JHDM1A gene encodes 1,162 amino acids and contains JmjC, F-box, and CXXC zinc-finger domains, which coding sequence and deduced protein shares 91 and 99% similarity with human JHDM1A, respectively. Spatio-Temporal expression analysis indicated that the mRNA expression of porcine JHDM1A had significantly higher levels in the middle (65 days) and later (90 days) period's embryo skeletal muscle than that of 33 days, and showed a ubiquitously expression but with the highest abundance in kidney, lung and liver of an adult pig. Radiation hybrid mapping and the following linkage mapping data indicate that JHDM1A maps to 2p17 region of pig chromosome 2 (SSC2). Allele frequency differences were detected in different pig breeds and an association study was performed with a SNP within 3'UTR. The results showed that there is a tendency for allele frequencies to differ between the fast growth breeds (Yorkshire) and slow growth pig breeds (Qingping pigs, Yushan Black pigs, Erhualian pigs and Dahuabai pigs). The association analysis using a Berkshire × Yorkshire F(2) population indicated that the C224G polymorphism had a highly significant association with average daily gain on test (P < 0.01), a trend association with average back fat thickness (P < 0.07), and significant associations (P < 0.01) on percent of average drip loss, Fiber Type II Ratio, muscle shear force and average lactate content in µmol/g. This study provides the first evidence that JHDM1A is differentially expressed in porcine embryonic skeletal muscle and associated with meat growth and quality traits.