丝裂原活化蛋白激酶信号通路及其与热应激反应的关系

丝裂原活化蛋白激酶(mitogen-activated protein kinases,MAPKs)信号通路存在于所有生物体内的大多数细胞内,是哺乳动物细胞重要的信号转导通路,可将细胞表面信号刺激转导至细胞及其核内,与细胞增殖、存活、分化、凋亡等生理病理过程密切相关。在机体发生热应激时,MAPKs信号途径被激活,调控机体产生一系列生物学功能变化。作者综述MAPKs信号转导通路的激活机制和生物效应,重点阐述了MAPKs通路与热应激反应之间的关系。     

集中供热系统实行热计量收费可能出现的若干问题

笔者针对目前集中供热系统实现分户计量收费这一情况,分析了可能出现的一些问题。以引起社会关注,共同探讨解决问题的最好办法。     

热应激牛初乳对新生犊牛血清免疫指标的影响研究

新生犊牛通过初乳获得被动免疫,但是关于热应激对新生犊牛被动免疫的影响程度尚不清楚。本试验旨在研究热应激牛初乳对新生犊牛被动免疫是否有显著影响,并与非热应激生产条件下进行比较。试验动物为对应于采食热应激和非热应激母牛初乳的新生犊牛各4头,在其采食母牛初乳后的不同时间内采血用于免疫指标分析。结果表明:热应激奶牛哺乳犊牛血清中各成分含量在144h内均低于非热应激奶牛哺乳犊牛血清中相对应成分,其中IgG、T3、T(472h内)变化差异显著(P<0.05),INS和IGF-Ⅰ变化差异不显著(P>0.05),热应激在一定程度上影响新生犊牛被动免疫,有关机理有待于进一步研究。     

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。     

"抗暑一号"对热应激小鼠部分血液生理生化指标的影响

为探讨中药复方制剂"抗暑一号"对热应激小鼠部分血液生理生化指标的影响,将50只昆明小鼠随机分成5组,每组10只,其中1组至3组为热应激中药低、中、高剂量治疗组,4组为阳性对照组,5组为阴性对照组。各组按常规饲养,其中1组至4组模拟夏季高温天气,在生化培养箱内复制热应激病理模型。1组至3组分别灌服1∶1的"抗暑一号"煎剂0.2、0.40、.6 mL,4组和5组分别灌服生理盐水0.4 mL,各组连续灌胃1周。各组于末次灌药后的24 h,摘除眼球采血分离血清检测相关生化指标。结果表明,阳性对照组中的K+、Cl-、GOT、GPT浓度较阴性对照组显著升高(P<0.01),而Na+、TP、ALB、AKP浓度较阴性对照组显著降低(P<0.01)。3个剂量均能不同程度改善热应激小鼠的血液生理生化指标异常,与阳性对照组相比,差异均极显著(P<0.01),其中Na+、K+、TP、GPT浓度已回升至正常水平(与阴性对照组相比,P>0.05)。     

模拟鸟巢式运动场的热集聚效应及其对草坪生长的影响

通过模拟北京奥运国家体育场的鸟巢式框架结构,并对体育场的热集聚效应及其对场内运动草坪生长所造成的影响进行了研究分析。结果表明:鸟巢式体育场有明显的热集聚效应,在外部气温28℃以下时,场内的热集聚效应相对较小,温度增加幅度为4~5℃;但当外部气温高于35℃时,场内的热集聚效应十分明显,场内温度要比外部高出12~15℃,可达到了45~50℃的极端高温。这种热集聚效应所产生的极端高温严重影响了场内草坪的生长,草坪质量在夏季高温第一次来临时(7月4日)即出现明显的下降,比露地对照草坪的质量下降提早了18d,草坪密度的下降则表现得更为强烈,比露地对照要提早24d,草坪的生长量对热胁迫有一个增长式的响应过程,露地对照草坪的热响应时间有30d,而鸟巢式结构所产生的热集聚效应将草坪生长的热响应时间缩短到了6d,之后其生长出现迅速下降,热集聚效应也加速了草坪叶片中叶绿素含量的下降幅度,其叶绿素含量在整个夏天的处理过程中都要显著低于露地对照,直至8月9日草坪完全死亡。而露地对照草坪虽然在夏天有一个极明显的质量下降过程,但随着秋天凉爽气候的到来,草坪能够逐渐恢复。     

基于GIS的内蒙古兴安盟地区热量资源空间分布特征研究

采用半经验半理论回归模拟方法,建立了内蒙古兴安盟地区40个表征热量资源的空间分布模型,模型全部通过0.01显著性检验,其中90%的模型同代检验和87.5%的模型模拟检验相对误差在-5%～5%之内.不同时间尺度空间分布模型之间具有较好的一致性,所建模型能够较好的模拟该地区的热量资源空间分布.在此基础上,应用GIS技术和1...     

The effects of early‐age thermal manipulation and daily short‐term fasting on performance and body temperatures in broiler exposed to heat stress

This study was conducted to investigate the effects of thermal manipulation at 5 days of age and short‐term fasting during the warmest part of the day on responses to prolonged heat stress of broilers. A total of 240‐day‐old Ross 308 female broiler chicks were divided into three groups: control, thermal manipulation (chicks were exposed to 36 °C for 24 h at 5 days of age) and short‐term fasting during the warmest part of the day (10.00–17.00 h). Prolonged heat stress was induced daily from 28 to 42 days by heating until the ambient temperature reached 32–35 °C between 10.00 and 17.00 h. Both thermal manipulation and short‐term fasting resulted in a decrease in rectal temperatures and haematocrit values at 35 and 41 days of age. Thermal manipulation improved body weight, feed consumption and feed conversion. However, short‐term fasting caused a reduction in body weight and a deterioration in feed conversion. Short‐term fasting lowered the percentages of carcass, whereas thermal manipulation highered breast yield. Both thermal manipulation and short‐term fasting decreased heart mass and abdominal fat.     

Effects of canopy interception on energy conversion processes in a Chinese fir plantation ecosystem

The functions of canopy interception on energy conversion processes in a Chinese fir plantation ecosystem were studied with the aid of long-term observation data in Huitong. The results showed that the absorbed, penetrated and reflected amounts of solar radiation were, respectively, 2.5543 × 10⁹ J/(m²·year) (absorption rate of 0.827), 2.5306 × 10⁸ J/(m²·year) (penetration rate of 0.082), and 2.7432 × 10⁸ J/(m²·year) (reflection rate of 0.091) by the canopy. The conversion of net solar radiation to latent heat in the process of evaporation from canopy interception amounted to 6.3695 × 10⁸ J/(m²·year) (accounting for 22.9% of total ecosystem net radiation and 30.4% of ecosystem evaporation), which was an important part of the budget of the energy system. Canopy interception consumed kinetic energy of raindrops in overcoming resistance of branches and leaves, which collected raindrops, followed with the conversion of potential energy in raindrops to kinetic energy with falling raindrops. In general, the diameter of raindrops from the canopy is larger than that of the raindrops above the canopy as a result of the collection effort by the canopy. The kinetic energy of raindrops from the canopy, therefore, was higher than that of raindrops in the atmosphere. The drop-size distribution from the canopy was affected by the structure of the canopy layer rather than the amount of precipitation and precipitation intensity. The canopy had no important nor efficient effects on decreasing the kinetic energy of raindrops in our case study with a first branch height of 7 m and precipitation amounts over 3 mm. However, the canopy would play a key role in decreasing kinetic energy of raindrops in two cases, that of a small amount of precipitation and one of heavy precipitation intensity, in which the canopy could intercept the largest amount of precipitation in the former condition and the canopy could scatter bigger raindrops to smaller raindrops with striking leaves in the case of heavy precipitation. __________ Translated from Scientia Silvae Sinicae, 2007, 43(2): 15–20 [译自: 林业科学]     

Presence of chlorogenic acid during in vitro maturation protects porcine oocytes from the negative effects of heat stress

Chlorogenic acid (CGA) is known to protect oocytes from oxidative stress. Here we investigated the effects of CGA on porcine oocyte maturation under heat stress and subsequent embryonic development after parthenogenetic activation. For in vitro maturation (IVM) at 41.0°C (hyperthermic condition), supplementation of the maturation medium with 50 μM CGA significantly improved the percentage of matured oocytes and reduced the rate of apoptosis relative to oocytes matured without CGA (p < .05). CGA treatment of oocytes during IVM under hyperthermia tended to increase (p < .1) percentage of blastocyst formation after parthenogenesis and significantly increased (p < .05) the total cell number per blastocyst relative to oocytes matured without CGA. For IVM at 38.5°C (isothermic condition), CGA significantly improved the rate of blastocyst development compared with oocytes matured without CGA (p < .05), but did not affect oocyte maturation, apoptosis rate or the number of cells per embryo. Omission of all antioxidants from the IVM medium significantly reduced the rate of oocyte maturation, but the rate was restored upon addition of CGA. These results demonstrate that CGA is a potent antioxidant that protects porcine oocytes from the negative effects of heat stress, thus reducing the frequency of apoptosis and improving the quality of embryos.