硫胺素在瘤胃内的合成及其在预防亚急性瘤胃酸中毒中的应用

亚急性瘤胃酸中毒是现代集约化反刍动物生产中的常见营养代谢病,揭示亚急性瘤胃酸中毒的发生机制及其预防措施是畜牧业生产中的重要科学问题。本文通过综述硫胺素在反刍动物生产中的应用效果、影响硫胺素合成的因素、硫胺素与亚急性瘤胃酸中毒的关系及其调控亚急性瘤胃酸中毒的可能作用途径,进一步揭示了亚急性瘤胃酸中毒的发生机理和硫胺素的生理作用,并为反刍动物生产提供理论参考。     

乳腺内氨基酸调控乳蛋白合成的分子作用机制

作为维持哺乳动物生命活动重要的"生物工厂",乳腺利用从流经血液中摄取的氨基酸等营养物质为底物合成乳蛋白。研究证实,氨基酸还可作为一种信号因子,通过乳腺内多种信号级联传导通路,调控乳蛋白基因的转录及翻译过程,从而影响乳腺中乳蛋白的合成。酪氨酸蛋白激酶-信号转导子和转录激活子(JAK-STAT)信号通路和哺乳动物雷帕霉素靶蛋白(m TOR)信号通路是乳蛋白基因转录和翻译过程中的主要调控路径。本文综述了乳腺JAKSTAT和m TOR信号通路的分子机制及氨基酸通过这些通路调控乳蛋白合成的研究进展,旨在进一步阐明氨基酸调控乳蛋白合成的作用机理。     

脂肪细胞因子对动物脂类代谢的调控机理

脂肪细胞是一种能分泌多种细胞因子的内分泌细胞,如脂联素(APN)、瘦素、白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)及抵抗素等,这些细胞因子通过多种信号通路在机体脂类代谢中发挥着重要作用。本文主要综述了脂肪细胞因子对动物脂类代谢的调控机理,为通过饲粮途径调控动物的脂类代谢和改善肉品质提供参考依据。     

多胺对动物肠道稳态的调控作用及可能机制

多胺(腐胺、亚精胺、精胺等)是动物体内一类具有生物活性的低分子质量脂肪族化合物。多胺能调控动物肠道稳态,参与动物肠道的生长发育、肠道黏膜屏障、抗氧化和代谢等生理过程。但目前多胺调节肠道稳态的作用机理尚不清晰。本文就多胺对肠道稳态的调节作用做一综述,分析了多胺作用的可能机理,旨在为多胺的进一步应用提供参考。     

Effects of Complex Nutritional Regulation Additives on Meat Quality of Grazing Sheep in Cold Season

The experiment was conducted to investigate the effects of complex nutritional regulation additives on meat quality of grazing sheep in cold season.A single factor random block design was used,48 grazing ewes with 7 months old and the average body weight (28.01±1.70) kg were randomly divided into 4 groups:Group Ⅰ without supplement;Group Ⅱ with routine concentrate;Group Ⅲ with routine concentrate+complex formulation group 1 (0.30% malic acid,0.06% cysteamine,0.08% saccharicterpenin);Group Ⅳ with routine concentrate+complex formulation group 2 (0.60% malic acid,0.12% cysteamine,0.16% saccharicterpenin).And there were 3 repeats for each group with 4 grazing ewes in each repeat.At the end of experiment,the longissimus dorsi of ewes were collected to determine the content of meat nutrient and amino acids.The results showed that:① The crude fat content of group Ⅲ was higher than groupⅠ,Ⅱ and Ⅳ by 27.92% (P < 0.05),16.67% (P > 0.05) and 7.85% (P > 0.05),respectively.The crude protein content of group Ⅲ was higher than groupⅠ,Ⅱ and Ⅳ by 7.35% (P < 0.05),3.94% (P > 0.05) and 2.49% (P > 0.05),respectively.The shear force in three supplementary feeding groups were extremely significantly lower than that in the control group (P < 0.01) and compared with group Ⅱ,group Ⅲ was decreased by 3.98% (P < 0.05).② Compared with group Ⅰ and Ⅱ,the proline content of group Ⅳ was increased by 38.34% (P < 0.01) and 22.75% (P < 0.05),respectively.While the proline content of group Ⅲ was higher than groupⅠand Ⅱ by 19.63% (P > 0.05) and 6.15% (P > 0.05),respectively.Except for proline,other amino acids were not significant different among the four experimental groups (P > 0.05).In conclusion,in this trial,supplementing complex nutritional regulation additives had good effects on crude fat,crude protein and shear force and amino acids contents,also improved the flavor and nutritional value of grazing sheep in cold season.Taking into consideration various factors,the effect of group Ⅲ (supplementing routine concentrate+complex formulation group 1) was the most obvious,which had the practical guiding importance in improving the meat quality of grazing sheep in cold season.     

Sheep grazing causes shift in sex ratio and cohort structure of Brandt's vole: Implication of their adaptation to food shortage

Livestock grazing has been demonstrated to affect the population abundance of small rodents in grasslands, but the causative mechanism of grazing on demographic parameters, particularly the age structure and sex ratio, is rarely investigated. In this study, we examined the effects of sheep grazing on the cohort structure and sex ratio of Brandt's vole (Lasiopodomys brandtii) in Inner Mongolia of China by using large manipulative experimental enclosures during 2010–2013. Our results indicated that sheep grazing significantly decreased the proportion of the spring‐born cohort, but increased the proportion of the summer‐born cohort. Grazing increased the proportion of males in both spring and summer cohorts. In addition, we found a negative relation between population density and the proportion of the overwinter cohort. Our results suggest that a shift in the cohort structure and the sex ratio may be an important strategy for small rodents to adapt to changes in food resources resulting from livestock grazing.     

CpxR对鼠伤寒沙门菌的黏菌素耐药相关基因pmrB和phoQ调控作用的研究

为了探索 cpxR 对鼠伤寒沙门菌的黏菌素耐药相关基因 pmrB 和 phoQ 的调控作用,用overlapping PCR扩增得到 cpxR 、 pmrB 和 cpxR 、 phoQ 共表达基因 cpxR - pmrB 、 cpxR - phoQ ,用2倍微量肉汤稀释法对构建的 pmrB 、 phoQ 单基因过表达菌株JSΔ acrB Δ cpxR :: kan /p pmrB (JSΔΔ/p B )、JSΔ acrB Δ cpxR :: kan /p phoQ (JSΔΔ/p Q )和 cpxR - pmrB 、 cpxR - phoQ 共表达菌株JSΔ acrB Δ cpxR :: kan /p cpxR - pmrB (JSΔΔ/p RB )、JSΔ acrB Δ cpxR :: kan /p cpxR - phoQ (JSΔΔ/p RQ )进行黏菌素最小抑菌浓度(MICs)的测定,同时以各菌株在LB中的OD 600 nm 值绘制生长曲线,以各菌株在不同浓度的黏菌素中的存活率绘制杀菌曲线。结果:成功构建的鼠伤寒沙门菌 pmrB 、 phoQ 的单基因过表达菌株JSΔΔ/p B 、JSΔΔ/p Q 和 cpxR - pmrB 、 cpxR - phoQ 共表达菌株JSΔΔ/p RB 、JSΔΔ/p RQ 的MIC结果显示,JSΔ acrB Δ cpxR :: kan /p cpxR (JSΔΔ/p R )的MIC值较JS下降93.75%,与本实验室前期研究结果一致。JSΔΔ/p B 、JSΔΔ/p Q 的MIC值较JS均上升3倍,而JSΔΔ/p RB 、JSΔΔ/p RQ 的MIC值较JS分别降低50%和75%。生长曲线结果显示JSΔΔ/p R 的生长活性最低,JSΔΔ/p B 、JSΔΔ/p Q 、JSΔΔ/p RB 和JSΔΔ/p RQ 的生长活性均低于JSΔ acrB Δ cpxR :: kan /pHisA(JSΔΔ/pHisA)。黏菌素的杀菌曲线结果显示JSΔΔ/p B 和JSΔΔ/p Q 在不同浓度的黏菌素中的存活率显著高于黏菌素较敏感的JSΔΔ/p RB 和JSΔΔ/p RQ 。上述结果表明:CpxR能够通过PmrB和PhoQ调控鼠伤寒沙门菌对黏菌素的敏感性。     

microRNA对动物生殖轴以及胚胎着床影响的研究进展

表观调控作为调节基因功能的一种重要手段,其对生殖内分泌方面的调控起着重要作用。microRNA(miRNA)作为一类小的非编码RNA,也是一种表观遗传因子,它广泛参与生物体内各种生理及病理过程,对哺乳动物繁殖起着重要的调控作用。本文围绕miRNA在哺乳动物繁殖相关组织的表达及调控作用和miRNA对胚胎着床的影响进行综述,为理解miRNA对繁殖方面的表观调控、改善哺乳动物繁殖能力提供理论基础。     

CDK2和P53在细胞中心体复制与调控中的作用

中心体是真核生物重要的细胞器,其复制与调控异常可能是体外胚胎发育异常的重要原因,而CDK2和P53是调控中心体复制的关键且必要因子,在细胞中心体复制调控中起核心作用。作者简要介绍了中心体的功能和复制过程,重点综述了CDK2、P53及其相关因子在中心体复制调控中的作用,对研究体外受精胚胎和克隆胚胎的发育异常具有一定的理论意义。     

哺乳动物雌性生殖系统β-防御素的研究进展

β-防御素(beta-defensian,BD)在哺乳动物雌性生殖系统中广泛表达,在免疫、预防生殖道感染及胎儿正常发育等方面起到重要作用。主要对哺乳动物β-防御素在哺乳动物雌性生殖系统组织中的分布、作用及其调控进行了综述,并对其应用前景进行了展望,以期更好地揭示β-防御素在雌性生殖系统中的影响,从而为β-防御素的进一步研究提供理论依据。