Qiuling Li

Fat deposition determines beef marbling grade and meat quality, but the underlying molecular mechanisms remain unclear. This study aimed to investigate the role of bovine PPARD in lipid deposition, especially its effect on the expression of fatty acid transport genes (CD36, FATP1, and FABP1) and the lipid droplet-associated gene (PLIN2) in liver tissues from cattle with different marbling grades. The mRNA abundance and protein levels in liver tissues from thirty-one Wagyu × Angus crossbred beef cattle (25–26 months old) with different marbling grades (according to GB/T 29392-2022, based on the marbling richness of the longissimus dorsi muscle at the 12th–13th rib interface) were analyzed by RT-qPCR and Western blot, respectively. Additionally, PPARD was knocked down and overexpressed in bovine mammary epithelial cells to validate its effects on lipid-metabolism-related genes. The results showed that the mRNA levels of CD36, FATP1, PPARD, RXRA, RXRB, and PLIN2 were significantly higher (p < 0.01) in livers tissues from the A3 and A4 groups (high marbling) than in those from the A1 and A2 groups (low to moderate marbling). Western blot analysis revealed significantly higher PPARD protein expression in the A3 and A4 groups (high marbling) than that in the A1 and A2 groups (low to moderate marbling) (p < 0.05). It should be noted that the sample size of Group A4 is only 2, and the results of this group should be considered as a preliminary trend that needs to be validated with larger sample sizes. Cellular experiments confirmed that PPARD knockdown significantly decreased mRNA expressions of FABP1, CD36, and PLIN2 (p < 0.01), while PPARD overexpression significantly increased their mRNA levels (p < 0.05). These results indicate a positive correlation between PPARD expression and the transcriptional levels of genes involved in fatty acid transport and lipid droplet storage, suggesting that PPARD may be associated with hepatic lipid metabolism and potentially contribute to marbling development. These findings suggest that the PPARD signaling pathway contributes to hepatic lipid deposition and may play a role in marbling formation in beef cattle.

Mastitis is an important disease limiting milk production in dairy cows. Somatic cell score is commonly used as one of the main ways to gauge the level of mastitis in dairy cows, with higher somatic cell scores usually indicating possible mastitis. However, the main molecular markers affecting somatic cell scores remain unknown. The aim of this study was to investigate the association between single nucleotide polymorphisms in the SLC11A1 gene and somatic cell score in Chinese Holstein cows. In this study, 210 Chinese Holstein cows were genotyped and potential SNPs were detected by DNA sequencing, PCR-SSCP and PCR-RFLP analysis. Our results revealed two SNPs were identified in the CDS region of SLC11A1: c.723C>T and c.1144C>G. For the c.723C>T polymorphic site, two genotypes (AA, AB) were found and the genotype frequencies were 0.790 and 0.210, respectively. The results of the association analysis showed that the mean somatic cell score of the AA genotypes were significantly lower than those of the AB genotypes, suggesting that the A allele is a potential marker for improving mastitis resistance in Chinese Holstein cows. For the c.1144C>G polymorphic site, three genotypes (CC, CD, and DD) were found and the genotype frequencies were 0.629, 0.352 and 0.019, respectively. The association analysis revealed that the mean somatic cell score of CC genotypes was lower than that of CD and DD genotypes, however, no significant differences were observed among the various genotype groups when subjected to pair-wise comparisons. The bioinformatic analysis showed that these mutations affected the secondary and tertiary structure of SLC11A1 mRNA, suggesting that they may affect gene expression or protein translation and function. Finally, we predicted the SLC11A1 protein interaction network and found that SPI1, NOD2, TLR2 and S100A12 interacted with SLC11A1 and were reported as candidate genes associated with mastitis resistance. The results indicated that the SNP (c.723C>T) could be potential molecular marker for improving mastitis resistance traits in Chinese Holstein cows. We recommend further validation of this SNP in larger populations and its potential integration into breeding programs to enhance mastitis resistance in dairy cows.

Two different morphologies of?nanocellulose –?cellulose nanofibres (CNFs) and cellulose nanocrystals (CNCs) with different contents were added to?emulsified sausages to?replace pork back fat in?different proportions (10%, 30%, and?50%), ...

Background: Heat stress has a substantial negative economic impact on the dairy industry. N6-methyladenosine (m6A) is the most common internal RNA modification in eukaryotes and plays a key role in regulating heat stress response in animals. In dairy cows, however, this modification remains largely unexplored. Therefore, we examined the effects of heat stress on the m6A modification and gene expression in bovine mammary epithelial cells to elucidate the mechanism of heat stress response. In this study, Mammary alveolar cells-large T antigen (MAC-T) cells were incubated at 37 °C (non-heat stress group, NH) and 40 °C (heat stress group, H) for 2 hours, respectively. HSP70, HSF1, BAX and CASP3 were up regulated in H group compared with those in the NH group. Results: Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were conducted to identify m6A peaks and to produce gene expression data of MAC-T cells in the H and NH groups. In total, we identified 17,927 m6A peaks within 9355 genes in the H group, and 18,974 peaks within 9660 genes in the NH groups using MeRIP-seq. Compared with the NH group, 3005 significantly differentially enriched m6A peaks were identified, among which 1131 were up-regulated and 1874 were down-regulated. In addition, 1502 significantly differentially expressed genes were identified using RNA-seq, among which 796 were up-regulated and 706 were down-regulated in the H group compared to the NH group. Furthermore, 199 differentially expressed and synchronously differentially methylated genes were identified by conjoint analysis of the MeRIP-seq and RNA-seq data, which were subsequently divided into four groups: 47 hyper-up, 53 hyper-down, 59 hypo-up and 40 hypo-down genes. In addition, GO enrichment and KEGG analyses were used to analyzed the potential functions of the genes in each section. Conclusion: The comparisons of m6A modification patterns and conjoint analyses of m6A modification and gene expression profiles suggest that m6A modification plays a critical role in the heat stress response by regulating gene expression.

Heat stress (HS) leads to substantial economic loss of dairy industry each year. The negative effect of HS in dairy cows is becoming one of the more urgent issue due to accelerating side-effects of global warming. Various genes are involved in HS response but the information about the role of noncoding RNAs, especially circular RNAs (circRNAs) is largely unknown. In our study, we aimed to investigate the different expression profile of circRNAs between HS and Non-heat-stressed condition (NC) of Chinese Holstein cow’s mammary gland. CircRNAs were identified using RNA sequencing and bioinformatics analysis. In total, 37405 circRNAs were detected and 95 were differentially expressed (DE), including 15 downregulated and 80 upregulated circRNAs in HS group compared to NC. Eight circRNAs were randomly selected to verify the RNA sequencing result. Further, Sanger sequencing validated the backsplicing site of the eight circRNAs. Moreover, results obtained from the Quantitative real time PCR (qRT-PCR) showed consistent expression trend with that of RNA sequencing. GO annotation and KEGG analysis suggested that these DE circRNAs probably involved in the energy metabolic regulation. Furthermore, we constructed ceRNA network and the result indicated that these DE circRNAs could regulate lactation through IGF1 and PRL signaling pathway.

Food Science of Animal Resources (Food Sci. Anim. Resour.) is an international, peer-reviewed bimonthly journal publishing original research and reviews on basic and applied aspects of the use of animal resources including the meat, egg, dairy, and edible insect/worm products. Food Sci. Anim. Resour. is published and distributed by the Korean Society for Food Science of Animal Resources.

Background: Heat stress (HS) leads to substantial economic loss of dairy industry each year. The negative effect of HS in dairy cows is becoming one of the more urgent and important issue due to accelerating side-effects of global warming. At present, the best way to alleviate the effect of HS is breeding of thermotolerant cows which depends on the profound understanding of mechanism of HS. Various genes are involved in HS response but the information about the role of noncoding RNAs, especially circular RNAs (circRNAs) is largely unknown.Results: In our study, we aimed to investigate the different expression profile of circRNAs between HS and normal condition (NC) of Chinese Holstein cow’s mammary gland. CircRNAs were identified using RNA sequencing and bioinformatics analysis. In total, 37405 circRNAs were detected and 95 were differentially expressed (DE), including 15 downregulated and 80 upregulated circRNAs in HS group compared to NC. Eight circRNAs were randomly selected to verify the RNA sequencing result. Further, Sanger sequencing validated the backsplicing site of the eight circRNAs. Moreover, results obtained from the Quantitative real time PCR (qRT-PCR) showed consistent expression trend with that of RNA sequencing. GO annotation and KEGG analysis suggested that these DE circRNAs probably involved in the energy metabolic regulation. Furthermore, we constructed ceRNA network and the result indicated that these DE circRNAs could regulate lactation through IGF1 and PRL signaling pathway.Conclusion: During our study, it was evident that circRNAs were involved in regulation of HS response in Chinese Holstein cow’s mammary gland. This will help researchers to achieve a better understanding of mechanism related to HS response and can provide new insights in breeding of thermotolerant dairy cows.

MicroRNAs (miRNAs) are a class of small noncoding RNAs that play important roles in the regulation of gene expression. However, the role of miRNAs in bovine mammary gland responses to heat stress is not well understood. In the present study, we performed a deep RNA sequencing analysis to identify miRNAs associated with the heat stress potential of the bovine mammary gland. We identified 27 miRNAs that were differentially expressed significantly between the mammary tissue of Holstein cattle heat stress and normal conditions. Twenty miRNAs had higher expression in the mammary tissue of heat-stressed Holstein cattle. The seven highest differentially expressed candidate miRNAs (bta-miR-21-5p, bta-miR-99a-5p, bta-miR-146b, bta-miR-145, bta-miR-2285 t, bta-miR-133a, and bta-miR-29c) identified by deep RNA sequencing were additionally evaluated by stem-loop qPCR. Enrichment analyses for targeted genes revealed that the major differences between miRNAs expression in the mammary gland of heat-stressed versus control were associated with the regulation of Wnt, TGF-β, MAPK, Notch, and JAK-STAT. These data indicated that the differentially expressed miRNAs identified in this study may act as dominant regulators during heat stress. We might reduce heat stress damage of Holstein cows by up-regulating or down-regulating these differentially expressed miRNAs.

The mechanisms that dairy cattle respond to environmental stresses are very complicated. Previous research into the molecular mechanisms of mammalian heat stress has largely focused on the role of protein-coding genes and small non–coding RNAs. Recently, it has become apparent that large numbers of long non-coding RNAs transcribed from mammalian genomes play extensive roles in transcriptional regulation. However, the expression of lncRNAs and their biological functions in heat stress in dairy cattle remain unknown. In this study, we employed a deep RNA sequencing to examine lncRNA expression profiles of heat stressed and non-heat stressed Chinese Holstein cattle. We found that 24,795 novel and 3763 known lncRNAs were expressed in the bovine mammary gland, of which 174 were differentially expressed in heat stress condition, among them, 156 lncRNAs were up-regulated and 18 were down-regulated. Through Cis role analysis, 16,474 lncRNAs were transcribed close to protein-coding neighbors. In addition, 11 and 2024 lncRNAs harbored precursors of known and predicted microRNAs, respectively, were annotated in the precursor analysis of miRNAs. Taken together, our findings represent the first systematic investigation of lncRNA expression in heat stressed Chinese Holstein and provide a resource for further research into the molecular mechanisms of lncRNAs function in dairy cattle.

Alpha 1-antitrypsin (α1-AT) may affect the susceptibility of mastitis in dairy cattle for its possible role in the protection of lactoferrin from proteolytic degradation in the mammary. Milk somatic cell score (SCS) is a logarithmic transformation of the milk somatic cell count widely used as an index to evaluate mastitis. To study the relationships of α1-AT gene and SCS in Chinese Holstein cows, methods of PCR-SSCP, DNA sequencing, PCR-RFLP, and CRS-PCR technologies were used to detect single nucleotide polymorphisms sites in α1-AT gene. Two polymorphic sites at G5503A and G5746C of α1-AT gene were found. AA (0.3633), AB (0.4644) and BB (0.1723) genotypes were detected at G5503A site, CC (0.3483), CD (0.4906) and DD (0.1611) genotypes were found at G5746C in Chinese Holstein cows. Least squares mean of SCS for individuals with BB genotype was significantly lower than that with AA and AB genotype (p < 0.01), and that with AB genotype was significantly lower than that with AA (p < 0.05). There was no significant difference among individuals with CC, CD and DD genotypes (p > 0.05). Least squares mean of SCS for individuals with BBDD genotype combination were significantly lower than those with AACC and AACD (p < 0.05). Statistical analysis indicated that B allele and BBDD genotype combination of α1-AT can improve mastitis resistance in dairy cattle.