应激蛋白研究进展

应激蛋白（HSP）可在多种应激原刺激下产生，并具有伴随性、自卫性、协同性、模拟性、双重性等特性。近年研究表明：HSP可提高机体耐热性，保护、修复细胞蛋白质，参与机体免疫反应，介导肿瘤增殖并参与肿瘤免疫，参与胚胎分化发育等诸多作用。因此，HSP的研究在生命科学的诸多领域受到重视。     

热应激对家禽HPG轴结构和繁殖功能的影响及HSPs的作用

高温环境容易引起家禽热应激,造成家禽下丘脑-垂体-性腺(hypothalamic-pituitary-gonadal,HPG)轴各组织结构不同程度的损伤,进而影响家禽正常繁殖功能,给集约化饲养管理模式下家禽养殖业造成一定的损失。热休克蛋白(HSPs)是一类保护性蛋白,它能在家禽遭受高温应激时发挥分子伴侣作用,一定程度上保护机体免受高温刺激的损伤。文章对热应激条件下家禽的HPG轴各组织结构、繁殖功能的影响及HSPs的作用进行综述,为家禽生产提供相关资料。     

热应激对牛肉品质影响的研究进展

近年来,高温环境对肉牛生产造成的影响不可忽视.国内外学者的研究多集中在热应激对牛肉品质的影响,而热应激期牛肉品质变化的分子机制研究相对较少.文章从热应激对牛肉的肉色、pH、系水力、嫩度、风味等的影响以及与热应激反应密切相关的小分子热激蛋白等方面进行简要介绍,以期分析影响牛肉品质变化的机制,为进一步提高热应激期牛肉品质的...     

热应激蛋白对畜禽抗应激机理的研究进展

热应激蛋白(heat shock proteins, HSPs)是机体在应激条件下所产生的一组特异性蛋白质,能使机体迅速适应环境变化。作者简要介绍了HSPs的来源及分类,阐述了HSP70 的基因结构和调控机制,综述了HSPs抗应激功能及在畜禽应激反应中的表达,以期为从分子水平探索HSPs 抗应激机理提供参考。     

Dietary thymol supplementation promotes skeletal muscle fibre type switch in longissimus dorsi of finishing pigs

As one of the key points related to meat quality, skeletal muscle fibre type is determined by energy metabolism and genetic factors, but its transformation could be also greatly influenced by many factors. Thymol, the primary effective ingredients of thyme, is well known for its anti-oxidation and anti-inflammatory, while little is known about its effect on skeletal muscle oxidative metabolism and fibre type switch. Therefore, in order to investigate its effects and possibility to be applied in livestock production, 36 150-day-old fattening Pigs were fed with different diet for six-week experiment. As a result, the drip loss ratio of longissimus dorsi (LD) was significantly reduced (p < .05). Oxidative metabolism-related enzyme activity, the mRNA levels and protein expression of COX5B and PGC1α, mRNA level of myosin heavy chain I (MyHC I) and protein level of MyHC IIa were significantly upregulated (p < .05). While compared with control group, the protein expression of MyHC IIb was significantly decreased (p < .05). The result revealed that thymol could promote the oxidative metabolism in the muscle of pigs and improve the meat quality to a certain extent.     

Effects of a short‐term supranutritional selenium supplementation on redox balance,physiology and insulin‐related metabolism in heat‐stressed pigs

Heat stress (HS) disrupts redox balance and insulin‐related metabolism. Supplementation with supranutritional amounts of selenium (Se) may enhance glutathione peroxidase (GPX) activity and reduce oxidative stress, but may trigger insulin resistance. Therefore, the aim of this experiment was to investigate the effects of a short‐term high Se supplementation on physiology, oxidative stress and insulin‐related metabolism in heat‐stressed pigs. Twenty‐four gilts were fed either a control (0.20 ppm Se) or a high Se (1.0 ppm Se yeast, HiSe) diet for 2 weeks. Pigs were then housed in thermoneutral (20°C) or HS (35°C) conditions for 8 days. Blood samples were collected to study blood Se and oxidative stress markers. An oral glucose tolerance test (OGTT) was conducted on day 8 of thermal exposure. The HS conditions increased rectal temperature and respiration rate (both p < .001). The HiSe diet increased blood Se by 12% (p < .05) and ameliorated the increase in rectal temperature (p < .05). Heat stress increased oxidative stress as evidenced by a 48% increase in plasma advanced oxidized protein products (AOPPs; p < .05), which may be associated with the reductions in plasma biological antioxidant potential (BAP) and erythrocyte GPX activity (both p < .05). The HiSe diet did not alleviate the reduction in plasma BAP or increase in AOPPs observed during HS, although it tended to increase erythrocyte GPX activity by 13% (p = .068). Without affecting insulin, HS attenuated lipid mobilization, as evidenced by a lower fasting NEFA concentration (p < .05), which was not mitigated by the HiSe diet. The HiSe diet increased insulin AUC, suggesting it potentiated insulin resistance, although this only occurred under TN conditions (p = .066). In summary, HS induced oxidative stress and attenuated lipid mobilization in pigs. The short‐term supranutritional Se supplementation alleviated hyperthermia, but did not protect against oxidative stress in heat‐stressed pigs.     

The influence of physical training on the pH of skeletal muscle in pigs

Treadmill training of pigs was shown to retard the pH-drop of longissimus dorsi biopsy samples. Training similarly had an inhibiting effect on the post-mortem pH, ATP and glycogen, and on fluid loss (expressible juice) of the gracilis muscle.     

Rapamycin administration during an acute heat stress challenge in growing pigs

Study objectives were to determine the effects of rapamycin (Rapa) on biomarkers of metabolism and inflammation during acute heat stress (HS) in growing pigs. Crossbred barrows (n = 32; 63.5 ± 7.2 kg body weight [BW]) were blocked by initial BW and randomly assigned to 1 of 4 environmental-therapeutic treatments: 1) thermoneutral (TN) control (n = 8; TNCon), 2) TN and Rapa (n = 8; TNRapa), 3) HS control (n = 8; HSCon), or 4) HS and Rapa (n = 8; HSRapa). Following 6 d of acclimation to individual pens, pigs were enrolled in two experimental periods (P). During P1 (10 d), pigs were fed ad libitum and housed in TN conditions (21.3 ± 0.2°C). During P2 (24 h), HSCon and HSRapa pigs were exposed to constant HS (35.5 ± 0.4°C), while TNCon and TNRapa pigs remained in TN conditions. Rapamycin (0.15 mg/kg BW) was orally administered twice daily (0700 and 1800 hours) during both P1 and P2. HS increased rectal temperature and respiration rate compared to TN treatments (1.3°C and 87 breaths/min, respectively; P < 0.01). Feed intake (FI) markedly decreased in HS relative to TN treatments (64%; P < 0.01). Additionally, pigs exposed to HS lost BW (4 kg; P < 0.01), while TN pigs gained BW (0.7 kg; P < 0.01). Despite marked changes in phenotypic parameters caused by HS, circulating glucose and blood urea nitrogen did not differ among treatments (P > 0.10). However, the insulin:FI increased in HS relative to TN treatments (P = 0.04). Plasma nonesterified fatty acids (NEFA) increased in HS relative to TN treatments; although this difference was driven by increased NEFA in HSCon compared to TN and HSRapa pigs (P < 0.01). Overall, circulating white blood cells, lymphocytes, and monocytes decreased in HS compared to TN pigs (19%, 23%, and 33%, respectively; P ≤ 0.05). However, circulating neutrophils were similar across treatments (P > 0.31). The neutrophil-to-lymphocyte ratio (NLR) was increased in HS relative to TN pigs (P = 0.02); however, a tendency for reduced NLR was observed in HSRapa compared to HSCon pigs (21%; P = 0.06). Plasma C-reactive protein tended to differ across treatments (P = 0.06) and was increased in HSRapa relative to HSCon pigs (46%; P = 0.03). Circulating haptoglobin was similar between groups. In summary, pigs exposed to HS had altered phenotypic, metabolic, and leukocyte responses; however, Rapa administration had limited impact on outcomes measured herein.     

The effect of physical training on skeletal muscle enzyme composition in pigs.

Running exercise in pigs results in an elevation of lactic acid in blood. This elevation in blood lactate does not occur in physically conditioned pigs. Activities of succinic dehydrogenase, fructose-l,6-diphosphate aldolase, lactate dehydrogenase and creatine Phosphokinase as well as the myoglobin content were determined in m. gastrocnemius from 6 ergometer-trained and 4 untrained pigs. The succinic dehydrogenase and myoglobin contents were significantly higher (P<0.01) in trained animals, whereas no changes were noted in the aldolase and creatine Phosphokinase contents. The lactate dehydrogenase showed somewhat reduced levels in the trained pigs. This was accompanied by an increased H/M subunit ratio. The results provide evidence for an increase in the maximal aerobic metabolism in trained pigs and that trained pigs to a higher extent can rely on an aerobic energy metabolism during running exercise.     

减缓肉牛热应激最新研究进展

为了减少肉牛热应激对肉牛生产性能、生理生化指标、抗氧化能力、妊娠牛激素及免疫功能等方面产生的影响,笔者检索了国内外相关文献,从品种、中草药方剂和饲料添加剂、环境控制三方面归纳在肉牛抗应激能力的最新研究进展,为肉牛健康高效养殖提供参考。     

Viability of maternally heat-stressed mouse zygotes in vivo and in vitro

Mammalian preimplantation embryos are susceptible to heat stress. This present study examined how maternal heat stress affects the development of mouse zygotes in vivo and in vitro. In Experiment 1, zygotes collected from female mice that were heat‐stressed for 12 h on day 1 of pregnancy were cultured in vitro. Maternally heat‐stressed zygotes developed normally to the two‐cell stage, but the majority of embryos failed to develop into morulae or blastocysts. In Experiment 2, pregnant mice were heat‐stressed on day 1 or from day 1 to day 3 of pregnancy. The number of living fetuses on day 14 of pregnancy was lower in heat‐stressed mice than in non‐stressed mice, but the difference was significant only in successively heat‐stressed mice. These results demonstrate that maternally heat‐stressed zygotes have reduced in vitro viability, but this phenomenon does not necessarily lead to embryo loss in the maternal environment.     

Effects of transport stress on pathological injury and main heat shock protein expression in the respiratory system of goats

The aim of the present study was to investigate the pathological injury and the expression of heat shock proteins in the caprine lung, trachea and bronchus under transport stress. 12 healthy male goats were selected and randomly divided into three groups. The control group (non-transported group), 2 hr transport-treated group and 6 hr transport-treated group. Morphological changes as well as the expression of heat shock proteins (HSPs, mainly HSP27, HSP70 and HSP90) in three parts of the respiratory tract were examined. Our results showed swollen mucosa and congestive blood vessels in mucous layer and submucosa, inflammatory cell infiltration as well as degeneration and necrosis of mucosal epithelial cells in trachea and bronchus of the transport-treated groups. The epithelial cells were degenerated, and the exfoliated cells and debris could be seen in the alveolar cavity. The results of immunohistochemistry showed that HSP27 and HSP70 were strongly expressed in tracheal and bronchial epithelium, glandular epithelium, vascular endothelium and bronchiole epithelium. And the amount of positive inflammatory cells was increased in transport-treated groups. Western blot results indicated that the expression of all three proteins had no obvious difference among the three groups in bronchi (p > .05). In trachea, there was no significant difference in the expression of heat shock proteins among the three groups except that the expression of HSP70 which was obviously higher in the two transported groups than the control group (p < .05). The expression level of HSP70 in the 2 hr transport-treated group was significantly higher than the 6 hr group (p < .05) and control groups (p < .05). However, there was no significant difference in the expression level of HSP27 and HSP90 in three groups (p > .05). In conclusion, our data showed that transport stress could damage the caprine respiratory system.     

动物机体热休克应答相关信号途径的研究进展

动物处于不良饲养、运输、屠宰等环境下产生热应激,机体对热应激的反应称为热休克应答,多条信号途径调控热休克应答,引发热休克蛋白的产生。本文综述了MAPK、PI3K/Akt、PKC等信号途径对热休克蛋白的调控作用,从分子机制上阐明了热应激的调控机理。     

The solubilization of myofibrillar proteins of vertebrate skeletal muscle in water

Myofibrillar proteins of vertebrate skeletal muscles are insoluble in solutions of ionic strength that approximate physiological conditions. We established a method to solubilize more than 80% of chicken breast muscle myofibrillar proteins in water for the use of meat as a source of food protein. SDS‐polyacrylamide gel electrophoretic patterns of water‐soluble myofibrillar proteins demonstrated that all identified myofibrillar proteins except connectin/titin were soluble in water. A part of α‐actinin was released from myofibrils by repeated washing with 2.5 mmol/L NaCl and 5 mmol/L L‐histidine solution, and subsequent destruction of connectin/titin in washed myofibrils by ultrasonication resulted in solubilization of a large fraction of chicken breast muscle myofibrillar proteins in water. Myofibrillar proteins of chicken leg, pork loin, beef shoulder loin, and lamb were also solubilized in water using this procedure.     

热休克蛋白与寄生虫感染的关系

近年来热休克蛋白（heat shock proteins, HSPs）在寄生虫感染、治疗和预防中的意义已引起广泛关注,成为最活跃的研究领域之一。作者就热休克蛋白家族及其在寄生虫感染中的作用作一综述。     

清热解暑中药验方对热应激奶牛采食行为及产奶性能的影响

本试验探讨3种清热解暑中药验方对热应激奶牛采食行为及产奶性能的影响.40头泌乳末期的中国荷斯坦奶牛随机分为4组,分别接受4种处理,即对照组、清热健胃组、清暑组和加减白虎汤组.所有试验牛饲喂相同的全混合日粮,3个处理组分别补饲清热健胃散、清暑散和加减白虎汤散剂,用量为每日每头150 g.结果发现,全天采食量和牛舍各时点的温度和温湿指数极显著负相关.在奶牛处于轻度热应激时添加清热解暑中药对采食行为影响不显著,仅在第1天早饲时略影响采食速度.清暑组干物质采食量较高,产奶量下降较少,表明清暑散具有缓解热应激、促进食欲的作用.