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.

BACKGROUND:Chinese Holstein is a dairy cattle breed developed through crossbreeding and long-term selection. The Beijing Holstein represents a distinct population within the Chinese Holstein breed, specifically bred in the Beijing region. OBJECTIVES:This study aimed to estimate the genetic parameters for six economic traits in Beijing Holstein cows. METHODS:Data from 5409 Beijing Holstein cows across 13 dairy farms were analysed by MTDFREML and SAS software. The linear univariate and bivariate animal model analyses were employed to estimate heritabilities and genetic correlations, respectively. RESULTS:Heritabilities of milk yield in 305 days (d), fat percentage, protein percentage, somatic cell score (SCS), lactose percentage and dry matter percentage were 0.08, 0.17, 0.20, 0.10, 0.16 and 0.26, respectively. Most genetic correlations aligned in direction and magnitude with their phenotypic correlations. Notably, dry matter percentage exhibited strong positive genetic correlations with fat percentage (0.96), protein percentage (0.74) and lactose percentage (0.70). The genetic correlations were moderately significant negative between dry matter percentage and milk yield in 305 d (-0.39), between SCS and dry matter percentage (-0.26), between SCS and lactose percentage (-0.30), and between SCS and fat percentage (-0.38). CONCLUSIONS:On the basis of the genetic parameters and their economic significance, the milk yield in 305 d, fat percentage, protein percentage and SCS would be selected as breeding goal traits with different direction and extent of weight. A balanced breeding approach targeting these traits is essential to enhance overall production performance. This study provides foundational data for evaluating the production potential of Beijing Holstein cows and supports informed breeding decisions.

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%), and the colour, emulsion stability, texture characteristics and dynamic rheological behaviour of emulsified sausages were analysed. The results indicate substituting fat with nanocellulose led the L* (lightness) and a* (redness) values increased and the b* (yellowness) values decreased of the emulsified sausages. Increasing nanocellulose concentration improved the emulsion stability of the sausages. In terms of emulsion stability, the use of CNFs outperformed CNCs, especially for samples substituted with 50% fat. In terms of texture, emulsified sausages where CNCs replaced fat showed lower hardness, viscosity, and chewiness compared to those with CNFs. The dynamic rheological results indicated that when the fat replacement levels were 10% and 30%, samples using CNFs as fat substitute had slightly higher storage modulus (G') values than those using CNCs. However, for 50% fat replacement, samples using CNFs as fat substitute had significantly higher G' values than those using CNCs, which demonstrates that higher CNFs concentrations are more conducive to the formation of a three-dimensional network structure.

介绍了生物化学课程思政的改革措施和实施效果.改革内容包括课堂思政教学应主抓三点(需求点、困惑点、兴趣点),显隐结合(显性思政内容和隐性思政教育方法结合),采用多元化教育方式和考核方式.问卷调查结果表明,这些措施获得了大多数学生的认可,具有较好的效果.

The stress resistance of sodium alginate and poly-l-lysine compound probiotics microcapsules was studied. Sodium alginate and poly-l-lysine were used as wall materials, and the probiotics were pre-fermented encapsulated by the internal emulsification method. The morphological structures of microcapsule probiotics and the diameter distribution of microcapsule granule were observed and measured. The characteristics of temperature resistance, acid resistance and intestinal solubility of probiotics microcapsules were studied. Compared with unencapsulated probiotics bacterial powder, the microencapsulated bacteria were treated at 110 or 130 ℃ for 30, 45 s and 60 s, respectively; and were treated at 75 or 85 ℃ for 1 min under the 100 % high humidity treatment; and were treated in simulated gastric or intestinal fluids for 30, 90 min and 180 min treatment. The results showed probiotic microcapsules were uniform in size, and the average diameter of the microcapsules was 717 μm. Compared with unencapsulated probiotics bacterial powder, the ability to resist high temperature and high humidity was improved significantly（P＜0.01）, and the ability to tolerate gastric juice and intestinal juice of probiotics microcapsules was significantly improved（P＜0.05）. The stress resistance of sodium alginate and poly-l-lysine compound probiotics microcapsule was much higher than that of uncapsulated ones.

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. 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. 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.

热应激会导致牛乳中酪蛋白含量减少,降低牛乳品质.本研究拟鉴定参与热应激应答的酪蛋白基因来源的环状RNA,为今后阐明热应激导致酪蛋白表达减少的分子机制提供理论依据.本课题组前期工作通过RNA-seq获取了环状RNA在非热应激及热应激奶牛(Bos taurus)乳腺组织中的表达数据.本研究随机挑选4个环状RNA,通过Sanger测序法验证了其反向剪接位点的存在;通过实时荧光定量PCR技术验证了其在非热应激及热应激组中的相对表达水平,所得结果与高通量测序分析结果一致.酪蛋白的编码基因包括αs1酪蛋白(casein alpha s1,CSN1S1)、αs2酪蛋白(CSN1S2)、β酪蛋白(casein beta,CSN2)以及κ酪蛋白(casein kappa,CSN3).通过统计分析环状RNA的宿主基因数据,分别统计了来源于各个编码基因的环状RNA,通过聚类热图及韦恩图展示了这些环状RNA在不同样本及不同组别中的表达模式.最后,通过RNA-seq的TPM(transcripts per million)数据分析了酪蛋白基因来源的环状RNA的相对表达水平.本研究鉴定出源于酪蛋白基因的环状RNA共52个,其中来源于CSN1S1、CSN1S2和CSN2的环状RNA种类分别为29、16和7个,未检测到来源于CSN3的环状RNA.这些环状RNA中,与非热应激组相比,显著上调的环状RNA有5种,其中3种在热应激条件下特异性表达.所鉴定的酪蛋白来源的环状RNA,在热应激应答过程中显著差异表达(P<0.05),可能参与了热应激应答过程的乳蛋白合成调控.本研究鉴定了热应激应答过程中酪蛋白来源的环状RNA差异表达谱,有助于阐明热应激导致牛乳中酪蛋白含量减少的分子机制,为提高牛乳品质提供了理论依据.

溶菌酶是动物体液和血液中重要的非特异性免疫因子,其以化学性质稳定、无残留、无抗药性等优良抗菌特性受到科研人员广泛关注.天然溶菌酶抗菌谱窄,对革兰氏阳性菌抑菌效果明显,而对革兰氏阴性菌几乎无抑菌作用,因此对天然溶菌酶实施分子结构调整以拓宽其抑菌谱具有非常重要的意义.本文主要综述了化学、物理、生物改性方法对溶菌酶进行修饰以及溶菌酶在畜牧业中的研究进展,并对修饰溶菌酶在畜牧业中的应用潜力进行展望,以期为溶菌酶在畜牧业中的广泛应用提供参考.

热休克转录因子1(heat shock transcription factor 1,HSF1)是启动热休克蛋白基因表达的重要转录因子,对其进行深入研究有助于阐明HSF1对热应激反应的调控机制.本研究采用反转录PCR(reverse transcription-PCR,RT-PCR)技术对中国荷斯坦奶牛(Bos taurus)HSF1基因全长CDS进行克隆,并采用生物信息学技术分析其编码蛋白的生物学特性.结果显示,奶牛HSF1基因的3种剪接体被成功克隆,即HSF1-AS1(GenBank No.MW401766)、HSF1-AS2(GenBank No.XM_005215151.4)和HSF1-AS3(GenBank No.MW401767),剪接方式分别为外显子跳跃、内含子保留和可变的3'端位点.开放阅读框分析发现,HSF1的3种剪接体分别编码311、553和517个氨基酸.对本实验室前期的乳腺组织RNA-seq数据进行分析,结果显示,HSF1-AS2剪接体表达量最高(P<0.01),HSF1-AS1表达量最低(P<0.01).qRT-PCR检测结果显示,热应激使乳腺上皮细胞HSF1-AS1和HSF1-AS2表达水平显著上调.对剪接因子结合位点进行分析,发现HSF1基因第11外显子的SNP(18959 C>T)恰巧处于一个潜在的外显子剪接增强子(exonic splicing enhancer,ESE)区域,可能与HSF1-AS3的形成有关.基因进化分析发现,牛HSF1氨基酸序列与山羊(Capra hircus)同源性较高.本研究为深入阐明HSF1基因表达调控机制提供参考依据.

实验旨在分析17℃保存对获能精子蛋白酪氨酸磷酸化的影响,通过精子蛋白亚组分分离及酪氨酸磷酸化鉴定,研究精浆以及中药水提液对保存精子获能相关蛋白酪氨酸磷酸化的影响.选择获能指标-酪氨酸磷酸化分析新鲜猪精子和17℃保存猪精子,提取精子全蛋白、膜蛋白、核蛋白以及骨架蛋白,利用WB分离及鉴定酪氨酸磷酸化差异.结果显示:17℃保存条件下,获能精子在40～45、46～50 ku分子量膜蛋白酪氨酸磷酸化程度减弱;未获能精子在30～35 ku分子量胞浆蛋白磷酸化程度增强,出现似"获能"现象;精浆在保存中起到提供营养的作用但易导致细菌滋生;中药水提液对精子保存过程中的保护效果体现在精子获能培养后,鞭毛中段、主段酪氨酸磷酸化和新鲜精子无明显差异.

Fresh grass carp was used to produce surimi and 50 g/kg, 100 g/kg, or 150 g/kg pork back fat was added. The water distribution, thiobarbituric acid reactive substances (TBARS), myoglobin oxidation, color parameter (L*, a*, and b*), heme and non-heme iron content of samples were determined to analyze the effects of different fat content on the oxidation of myoglobin and lipids during multiple freeze-thaw cycles of grass carp surimi. Both multiple freeze-thaw cycles and increased fat content lead to an increase in TBARS, a blue shift in the absorption peak of myoglobin porphyrin, a decrease in heme iron content, and an increase of non-heme iron content. Repeated freeze-thaw caused a decrease in immobilised water content and L*, and caused an increase in a* and b*. Increased fat content caused an increase in immobilised water content, L* and a*, and caused a decrease in b*.

以生物化学课程蛋白质结构与功能一节网络直播教学为例,分享直播平台选择、课堂教学设计经验.网络直播教学平台应该满足:以内容为导向,可互动、可录屏回放,教学环节有数据记录、可追溯;课堂教学设计除了设计教的内容,还要设计学生学的内容,学的内容不仅局限在教材,还需要学生广泛涉猎多方求知;教学案例选择上应与生活和时事相联系,引入人文情怀和课程思政内容.

夏季奶牛热应激问题给奶业生产造成了巨大的经济损失.为揭示奶牛发生热应激后乳腺组织应答反应的分子机制,通过研究热应激奶牛乳腺组织差异表达基因,探究差异基因对乳腺组织转录调控的影响.以8头中国荷斯坦牛为研究对象,分别采集热应激期(8月,温湿指数THI=83.8)和非热应激期(3月,THI=65.8)各4头奶牛乳腺组织,利用HiSeq2000进行转录组测序,并进行生物信息学分析,共发现96个差异表达基因(差异倍数>2),其中上调表达46个,下调表达50个.GO分类结果表明,注释到细胞组分、分子功能和生物学过程的差异基因数量分别为41、38和36个(P<0.05).KEGG通路分析结果表明,差异基因共富集到18条信号通路(P<0.05),其中6条与疾病有关,9条与代谢有关,此外,与免疫应答相关的细胞因子-细胞因子受体相互作用和NOD样受体信号通路明显富集.通过比较热应激和非热应激奶牛乳腺组织转录组,分析差异基因相关信号通路,为进一步了解奶牛发生热应激反应的分子机制奠定基础.

Background Long non-coding RNAs (lncRNAs) can play important roles in uterine and ovarian functions. However, little researches have been done on the role of lncRNAs in the adrenal gland of sheep. Herein, RNA sequencing was used to compare and analyze gene expressions in adrenal tissues between follicular phases and luteal phases in FecB(BB) (MM) and FecB(++) (WW) sheep, respectively, and differentially expressed lncRNAs and genes associated with reproduction were identified. Results In MM sheep, 38 lncRNAs and 545 mRNAs were differentially expressed in the adrenal gland between the luteal and follicular phases; In WW sheep, 513 differentially expressed lncRNAs and 2481 mRNAs were identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses indicated that differentially expressed lncRNAs and their target genes are mainly involved in the circadian rhythm, the mitogen activated protein kinase, thyroid, ovarian steroidogenesis and transforming growth factor beta signaling pathways. Differentially expressed lncRNAs can regulate reproduction by modulating genes involved in these signaling pathways and biological processes. Specifically, XLOC_254761, XLOC_357966, 105,614,839 and XLOC_212877 targeting CREB1, PER3, SMAD1 and TGFBR2, respectively, appear to play key regulatory roles. Conclusion These results broaden our understanding of lncRNAs in adrenal gland of sheep and provide new insights into the molecular mechanisms underlying sheep reproduction.

为实现以学生为中心、成果导向和持续改进的教学理念,课程组对传统授课模式加以改变,以雨课堂平台为依托,利用雨课堂实时在线特点进行混合式教学改革.通过课前、课中和课后教学过程的实施及部分教学内容的课题化教学,激发了学生学习兴趣,增强了学生自学能力和创新意识,提高了学生分析问题和解决问题的能力,学生参加科学研究比例得以提高.雨课堂强大的实时互动功能在疫情期间作为网络教学直播平台也得到大多数学生的认可.

研究香辣公干鱼罐头的加工工艺,探讨不同的加工条件(卤制时间、酱油与水的体积比、油炸温度、油炸时间)及调味料(白砂糖、味精、花椒粉、辣椒粉)质量分数对罐头感官品质的影响,并对产品进行理化指标测定.结果 表明:公干鱼罐头的最佳加工条件为卤制时间为6 min,酱油∶水体积比为1∶5,油炸温度为180℃,油炸时间为40 s,白砂糖4％、味精0.5％、花椒粉0.2％、辣椒粉9％.通过此方法生产的公干鱼罐头色泽金黄,富有嚼劲,口感麻辣鲜香.

地方院校向应用型转型需要培养学生的自学能力、探究能力和创新能力,在理论学时被压缩的情况下开展“课题化、研究式”的教学方式增加了教师和学生的压力,网络辅助教学成为解决问题的手段.研究发现,“雨课堂”非常适合当前学校情况,可以很好地完成课前、课上和课后的教学环节.实践表明,小班授课且全程使用“雨课堂”教学在优秀等级和及格等级上有显著差异;大班授课、部分教学过程使用“雨课堂”在优秀等级上有显著差别.

旨在筛选奶山羊 cAMP应答元件结合蛋白 CREB(cAMP response element binding protein)基因的 siRNA,揭示干扰该基因后对乳腺上皮细胞中乳脂合成相关基因表达及甘油三酯合成的影响.本研究通过 qRT-PCR方法从西农萨能奶山羊乳腺组织中扩增 CREB基因完整的 CDS区,进行序列分析和不同泌乳时期表达水平分析,合成靶向 CREB基因的 siRNA,利用荧光定量 PCR筛选有效 siRNA,并检测脂质合成相关基因的表达,采用试剂盒检测细胞内甘油三酯含量.结果表明:1)克隆得到全长为 984 bp的奶山羊 CREB基因的 CDS区(GenBank登录号:MK158073),并对其进行生物信息学分析.2)该基因在奶山羊泌乳盛期乳腺组织的表达量为干奶期的1.93倍(P＜0.05).3)成功筛选到靶向 CREB基因的有效 siRNA,干扰效率为 72％(P＜0.01);并将其在奶山羊乳腺上皮细胞进行转染,通过 qRT-PCR检测脂质合成相关基因的表达,与对照组相比,干扰 CREB基因后显著抑制了 FASN 、ACACA 、SCD1,FABP3,LPL 、CPT1B、GPAM和 DGAT2基因表达量(P＜0.05,并显著增加了 HSL基因表达量(P＜0.05);且细胞内甘油三酯含量被显著下调(P＜0.05).综上所述,CREB基因在奶山羊原代乳腺上皮细胞中很可能通过调控脂质代谢相关基因的表达及甘油三酯含量对山羊的乳脂合成过程发挥重要作用.