Yeast culture repairs rumen epithelial injury by regulating microbial communities and metabolites in sheep.

This study delves into the impact of yeast culture (YC) on rumen epithelial development, microbiota, and metabolome, with the aim of investigating YC's mechanism in regulating rumen fermentation. Thirty male lambs of Hu sheep with similar age and body weight were selected and randomly divided into three groups with 10 lambs in each group. Lambs were fed a total mixed ration [TMR; rough: concentrate (R:C) ratio ≈ 30:70] to meet their nutritional needs. The experiment adopted completely randomized design (CRD). The control group (CON) was fed the basal diet with high concentrate, to which 20 g/d of YC was added in the low dose YC group (LYC) and 40 g/d of YC in the high dose YC group (HYC). The pretrial period was 14 days, and the experimental trial period was 60 days. At the end of a 60-day trial, ruminal epithelial tissues were collected for histomorphological analysis, and rumen microorganisms were analyzed by 16S rDNA sequencing and rumen metabolites by untargeted liquid chromatography-mass spectrometry (LC-MS) metabolomics techniques. The results showed that YC improved rumen papilla development and increased rumen papilla length (p < 0.05), while decreased cuticle thickness (p < 0.05). The 16S rDNA sequencing results showed that YC reduced the relative abundance of Prevotella_1 (p < 0.05), while significantly increased the relative abundance of Ruminococcaceae_UCG-005, uncultured_bacterium_f_Lachnospiraceae, and Ruminococcus_1 genus (p < 0.05). Metabolomics analysis showed that YC changed the abundance of metabolites related to amino acid metabolism, lipid metabolism and vitamin metabolism pathways in the rumen. In summary, YC might maintain rumen health under high-concentrate diet conditions by changing rumen microbiota structure and fermentation patterns, thereby affecting rumen metabolic profiles and repairing rumen epithelial injury.

Identification and functional characterization of developmental-stage-dependent piRNAs in Tibetan sheep testes.

The core function of the testes is to produce sperms, which is the prerequisite for maintaining male fertility. PIWI-interacting RNAs (piRNAs) are a class of non-coding small RNAs that are mainly enriched in the reproductive organ and play a key role in germ cell development and spermatogenesis. However, the expression and function of piRNAs in the testes of Tibetan sheep, a domestic animal endemic to the Tibetan Plateau, remain unknown. In this study, we evaluated the sequence structure, expression profile, and potential function of piRNAs in testicular tissues from Tibetan sheep at different developmental stages (3 months, 1 year, and 3 years of age, respectively) by small RNA sequencing. Of the identified piRNAs, the sequence lengths of 24-26 nt and 29 nt dominate. Most piRNA sequences begin with uracil and have a distinct ping-pong structure which mainly distributes in exons, repeat regions, introns, and other unannotated regions of the genome. The piRNAs in the repeat region are primarily derived from the retrotransposons: long terminal repeats, long interspersed nuclear elements, and short interspersed elements. These piRNAs constitute 2,568 piRNA clusters, which mainly distribute on chromosomes 1, 2, 3, 5, 11, 13, 14, and 24, and of these clusters, a total of 529 piRNA clusters were differentially expressed in at least two age groups. Most of the piRNAs were expressed in a low abundance in the testes of developing Tibetan sheep. A total of 41,552 and 2,529 differential piRNAs were identified in testes from 3 months vs. 1 year, and 1 year vs. 3 years, respectively, presenting significantly increased abundance for most piRNAs in 1 year and 3 years compared with 3 months. The functional evaluation of the target genes showed that the differential piRNAs are mainly involved in regulating gene expression, transcription, protein modification, and cell development during spermatogenesis and testicular development. In conclusion, this study focused on the sequence structure and expression characteristics of piRNAs in the testis of Tibetan sheep and provided new insights into the functional mechanism of piRNAs in testicular development and spermatogenesis of sheep.

The testis in mammals plays an indispensable role in male fertility, in which the development and function are strictly regulated by a variety of non-coding small RNAs. PIWI-interacting RNAs (piRNAs) are the most abundant non-coding small RNAs in mammalian testes, playing an irreplaceable role in testicular development and spermatogenesis. To characterize the piRNA expression and investigate their potential biological function in developmental Tibetan sheep testes, we carried out RNA sequencing. Our results revealed that the length distribution of the identified piRNAs is mostly 24­26 nt and 29 nt, exhibiting a preference for uracil at their 5' end and significant ping-pong structure. Most piRNAs were differentially expressed in Tibetan sheep testes in a development-age-dependent manner, and the vast majority of them were upregulated in postpubertal and adult testes. Based on the functional annotation of piRNA target genes, they were mainly implicated in the regulation of gene expression, transcription, protein modification and development during testicular development and spermatogenesis.

Immunogenicity and protective efficacy of a novel foot-and-mouth disease virus empty-capsid-like particle with improved acid stability.

Foot-and-mouth disease virus (FMDV) is the etiological agent of a highly contagious disease that affects cloven-hoofed animal species. The FMDV capsid is highly acid labile and viral particles lose their immunogenicity when they disassemble at mildly acidic pHs. The viral capsid of FMDV serotype O is more sensitive than those of other serotypes, making it more difficult to acquire enough empty-capsid-like particles in the acidic insect cell environment for research. In this study, novel FMDV mutants with increased acid resistance were isolated using BHK-21 cell cultured under low-pH conditions. Amino acid substitutions Q25R, K41E, and N85A in the VP1 capsid protein and K154Q in the VP3 capsid protein were detected in all six mutants. Based on these amino acid replacements, empty-capsid-like particles of FMDV serotype O, which were resistant to the acid-induced dissociation of the capsid into pentameric subunits, were produced in insect cells. We characterized the protective immunity induced by these acid-resistant empty capsid particles. Significant humoral and cellular immune responses were elicited in mice after immunization with the acid-resistant empty capsid particles. The acid-resistant empty-capsid-like particles also induced strong neutralizing antibodies in guinea pigs and protected all the guinea pigs from FMDV challenge. Our results suggest that these acid-resistant empty-capsid-like particles have potential utility as a vaccine against serotype O FMDV infection.

Novel chimeric foot-and-mouth disease virus-like particles harboring serotype O VP1 protect guinea pigs against challenge.

Foot-and-mouth disease is a highly contagious, acute viral disease of cloven-hoofed animal species causing severe economic losses worldwide. Among the seven serotypes of foot-and-mouth disease virus (FMDV), serotype O is predominant, but its viral capsid is more acid sensitive than other serotypes, making it more difficult to produce empty serotype O VLPs in the low pH insect hemolymph. Therefore, a novel chimeric virus-like particle (VLP)-based candidate vaccine for serotype O FMDV was developed and characterized in the present study. The chimeric VLPs were composed of antigenic VP1 from serotype O and segments of viral capsid proteins from serotype Asia1. These VLPs elicited significantly higher FMDV-specific antibody levels in immunized mice than did the inactivated vaccine. Furthermore, the chimeric VLPs protected guinea pigs from FMDV challenge with an efficacy similar to that of the inactivated vaccine. These results suggest that chimeric VLPs have the potential for use in vaccines against serotype O FMDV infection.