The freshness and bacterial communities of fresh and salted rabbit meat during 8 days of refrigerated storage at 4 °C were evaluated. The results showed that the addition of 2% salt significantly changed the color of meat, of which the lightness (L*), redness (a*), and yellowness (b*) were lower than that of fresh meat over time. The pH of all samples increased during storage, and meat with salt addition had lower values in comparison to fresh samples over time. The total volatile base nitrogen (TVB-N) concentration increased rapidly in salt-treated meat but was significantly (p < 0.05) lower than that in meat without salt added before 6 days. Over time, the content of thiobarbituric acid reactive substances (TBARS) showed a progressive trend, but a rapid increase occurred in salted meat. High-throughput sequencing showed that the microflora of each sample had a positive trend in alpha diversity and a negative trend in beta diversity. Bacterial taxonomic analysis indicated that the initial microbial flora for chilled rabbit meat was dominated by Shigaella, Bacteroides, and Lactococcus, and the population of Brochothrix and Psychrobacter increased over time and became the dominant spoilage bacterium. In particular, the addition of salt significantly reduced the abundance of Psychrobacter and Brochothrix. These findings might provide valuable information regarding the quality monitoring of rabbit meat during chilled storage.

Background: Imprinted genes are closely related to mammalian development, growth and behavior. To date more than 150 imprinted genes have been identified in human and mice but only a very limited number of imprinted genes have been reported in bovine. A novel gene PMM2 was identified as paternally imprinted in cattle (Bos taurus), but little is known about its expression pattern in yak (Bos grunniens). The aim of the present study was to investigate the imprinting status as well as expression levels of PMM2 gene in yak tissues and to determine whether DNA methylation would play a role in its expression. Methods: The exonic SNPs of yak PMM2 gene were discovered by direct sequencing of PCR amplicons from genomic DNA, by which the allelic expression was confirmed with reverse transcription PCR. Moreover, RT-qPCR was used to derive the expression levels of this gene in various tissues, and the DNA methylation status in the promoter was finally analyzed by bisulfite sequencing. Result: A total of four SNPs were screened out through direct sequencing of PCR amplicons in exon 9, based on these SNPs, we found that only one allele of the PMM2 gene was expressed in tissues of heart, lung, kidney, testis and muscle. Moreover, RT-qPCR revealed that the PMM2 gene was highly expressed in testis but at extremely low levels in lung. Finally, the DNA methylation status of a CpG enriched region in promoter was analyzed by using bisulfite sequencing, and a hypermethylated status was found in all the tissues in 18 CpG sites, indicating that the DNA methylation modification of promoter region may not be involved in the regulation of PMM2 expression in yak. This study provides a reference for further exploring the molecular mechanisms of PMM2 gene function and imprinting in yak.