白头鹎的代谢率与器官重量在季节驯化中的可塑性变化

动物能量代谢的生理生态特征与物种的分布和丰富度密切相关,基础代谢率(BMR)是恒温动物维持正常生理机能的最小产热速率,是动物在清醒时维持身体各项基本功能所需的最小能量值,是内温动物能量预算的重要组成部分.本研究测定了白头鹎(Pycnonotus sinensis)的BMR、内部器官(肝、心、肌胃、小肠、肾和整体消化道)和肌肉的重量,分析了白头鹎内部器官和肌肉重量的季节性变化及与BMR的关系.方差分析表明,白头鹎的BMR存在明显的季节性变化,冬季较高,夏季最低.其内部器官及肌肉重量的变化同样有明显的季节性.相关分析表明,白头鹎的BMR与肝、心、消化道等内部器官和肌肉重量存在明显的相关性.     

光周期对白头鹎（Pycnonotus sinensis）体重、器官重量和能量代谢的影响

光周期是四季环境变化的最直接表现因素之一,并影响动物的生理变化特征。为探讨光周期驯化对白头鹎(Pycnonotus sinensis)体重、器官重量及能量代谢的影响,以室温28℃、不同光周期 (16L ∶ 8D,LD组和8L ∶ 16D,SD组)对两组白头鹎进行为期4周的光周期驯化,测定其体重、各器官鲜重和干重、基础代谢率(BMR)和食物摄入能、排泄能及同化能并计算同化率。结果发现,SD组个体体重、内部器官(肝、小肠)重量、BMR及同化率相应显著高于LD组个体;短光照刺激白头鹎显著降低摄入能、排泄能及同化能。这些结果表明:光周期对白头鹎的体重、器官重量、BMR及能量收支有着一定影响,并且短光照较长光照更能引起白头鹎体重、器官重量及能量代谢的明显变化,同时验证了"中心限制假说",即白头鹎BMR与中心器官代谢(肝、小肠等)具有相关性,中心器官是改变白头鹎BMR的主要原因之一。     

光周期对白头鹎体重、器官重量和能量代谢的影响

光周期是四季环境变化的最直接表现因素之一,并影响动物的生理变化特征。为探讨光周期驯化对白头鹎(Pycnonotussinensis)体重、器官重量及能量代谢的影响,以室温28℃、不同光周期(16L∶8D,LD组和8L∶16D,SD组)对两组白头鹎进行为期4周的光周期驯化,测定其体重、各器官鲜重和干重、基础代谢率(BMR)和食物摄入能、排泄能及同化能并计算同化率。结果发现,SD组个体体重、内部器官(肝、小肠)重量、BMR及同化率相应显著高于LD组个体;短光照刺激白头鹎显著降低摄入能、排泄能及同化能。这些结果表明:光周期对白头鹎的体重、器官重量、BMR及能量收支有着一定影响,并且短光照较长光照更能引起白头鹎体重、器官重量及能量代谢的明显变化,同时验证了中心限制假说,即白头鹎BMR与中心器官代谢(肝、小肠等)具有相关性,中心器官是改变白头鹎BMR的主要原因之一。     

温度与光周期对白头鹎体质量、能量收支和消化道形态的影响

温度与光周期是环境季节性变化的最直接表现因子及时间变化指示标志,对动物的形态、生理及行为产生重要的影响.本文以白头鹎为研究对象,探讨了不同温度与光周期对其体质量、能量收支和消化道形态的影响,分析了能量收支与消化道形态特征的关系.将28只白头鹎(12雄16雌)分为4组:暖温长光组(30℃,16 L8 D;3雄4雌)、暖温短光组(30 ℃,8 L16 D;3雄4雌)、低温长光组(10 ℃,16 L8 D;3雄4雌)和低温短光组(10 ℃,8 L16 D;3雄4雌).结果表明: 低温与短光照可促进白头鹎的体质量、摄入能及同化能明显增加,同时温度与光周期的交互作用对白头鹎的摄入能及同化能影响显著.低温条件下,胃、小肠、直肠及总消化道的湿质量及干质量明显增加.残差分析表明,小肠与总消化道的长度及干质量与摄入能和同化能显著相关.表明低温与短光照下白头鹎通过增加体质量、能量摄入和改变消化道形态来应对严酷的环境条件.     

树麻雀代谢率和器官重量在季节驯化中表型的可塑性变化

动物能量代谢的生理生态特征与物种的分布和丰富度密切相关,基础代谢率(BMR)是内温动物能量预算的重要组成部分。北温带的小型鸟类,通过增加产热来适应低温环境。增加BMR的基础之一是中心器官(代谢机器)发生明显的变化。本研究中我们测定了树麻雀(Passermontanus)的BMR、体重和各器官的重量,分析了麻雀各器官的季节性变化及与BMR的关系。方差分析表明:麻雀的BMR存在明显的季节性变化,在冬季和秋季较高。麻雀内部器官的变化同样有明显的季节性,冬季和秋季麻雀的肝脏、心脏、肌胃、小肠、直肠和整体消化道的重量,都有明显的增加。相关分析表明:麻雀的BMR与肝脏、心脏和消化道等内部器官存在明显的相关性。我们的结果验证了“中心限制假说”,即麻雀体内存在着与BMR相关的“代谢机器”,中心器官是提高麻雀BMR的基础之一。     

白头鹎的的体温调节与蒸发失水

采用开放式呼吸测定仪和数字式温度测量仪,在环境温度为5.0~35.0℃范围内,测定白头鹎的体温、代谢产热和蒸发失水(EWL),并计算其热传导等生理生态特征。结果表明：白头鹎的热热中性区为25.0~32.0℃;基础代谢率(BMR)为(3.67±0.03)ml O₂ g_-1 h_-1,是体重预期值的64%。平均最小热传导为(0.15±0.00)ml O₂ g_-1 h_-1 ℃_-1,是体重预期值的124%。蒸发失水与产热的比率(EWL/RMR)在5.0~35.0℃时随着环境温度的升高而升高,在35℃时达到峰值,为(1.71±0.07)mg H₂O/ml O₂。代谢水和蒸发失水的比率(MWP/EWL)随环境温度上升而下降,在16.4℃时,MWP/EWL为1。这些结果表明了白头鹎具有较低的基础代谢率和高的热传导,蒸发失水在体温调节中占有重要的地位。     

白头鹎对季节性驯化和温度适应的生理反应

在自然环境中,有机体某一特性的可塑性变化在适应和功能方面是非常重要的。以成年白头鹎(Pycnonotus sinensis)为研究对象,分别在野外驯化条件和实验室温度适应条件下测定静止代谢率(RMR)、蒸发失水率(EWL)和代谢活性器官的重量,同时测定肝脏及肌肉的线粒体呼吸和细胞色素C氧化酶活力(COX)。野外季节性驯化在冬季和夏季时测定;实验室温度适应分为2组,分别在10℃和30℃下适应4周后进行测定。结果显示,与夏季驯化和暖适应组相比,冬季驯化和冷适应组RMR和EWL较高、代谢活性器官较重,线粒体呼吸速率和COX活性显著增加;器官重量和细胞产热能力的适应性变化可能是导致了RMR适应性调节。结果表明,白头鹎可以表现出对季节性驯化和温度适应的生理反应,利用这种能力应付野外环境温度的波动。生理能量特性的可塑性是鸟类能量代谢的共同特征。     

食物限制对高山姬鼠能量代谢和内脏器官形态的影响

为探讨栖息于横断山区高山姬鼠对食物匮乏的适应策略,在实验室条件下,以每日能量需求为标准,测定了饲喂食量为130%每日能量需求(DER)和70%DER两组高山姬鼠的体重、体温、基础代谢率(BMR)、非颤抖性产热(NST)等的变化,并在限食28d后,测定了肝脏鲜重和消化道形态的变化。结果显示:限食组高山姬鼠的体温、体重、BMR、NST显著降低,比0d分别下降了4.4%、23.6%、38.6%、20.3%。肝脏鲜重显著下降,小肠长度和小肠含内容物重显著增加。在限食条件下,高山姬鼠主要通过降低体重、体温、减少肝脏重量和能量代谢水平及消化器官适应性变化来减少能量支出,以适应食物资源短缺的外部环境。     

树麻雀代谢率和器官重量在光周期驯化中的变化

为探讨光周期对树麻雀代谢产热和代谢器官变化的影响,对成年树麻雀 Passer montanus 进行温度为25℃、两种光周期16 L:8 D(LD组)和8 L:16 D(SD组)4周的气候箱驯化后,测定其体重、基础代谢率(BMR)、体脂和水分含量,以及各器官、组织的鲜重和干重.结果 显示,SD组麻雀BMR显著大于LD组,作为代谢活性器官的消化道显著增生是其BMR显著增加的主要原因之一;麻雀通过增加体重和能量储备物脂肪来实现对较长黑暗环境的适应是其成功的生存策略.SD组麻雀体重的显著增加和水分含量显著降低,说明短光照的刺激引起麻雀能量储备的增加和代谢活性器官消化道增生.光周期驯化的结果验证了"中心限制假说",即麻雀体内存在着与BMR相关的"代谢机器",中心器官(消化道)是改变麻雀BMR的基础之一.     

被毛在黑线仓鼠能量代谢、产热和体温调节中的作用

为阐明小型哺乳动物被毛的季节性变化及其在能量代谢和体温调节中的作用,测定了季节性驯化,以及不同光周期和温度驯化的黑线仓鼠的被毛重量、体温和能量收支。结果显示: (1)冬季黑线仓鼠的被毛重量和产热显著高于夏季;(2)短光照(8L∶16D)和低温(5℃ ) 对被毛生长的影响不显著; (3)与室温组(21℃ )相比,低温组(5℃ )摄入能、基础代谢率(BMR)、非颤抖性产热(NST) 、褐色脂肪组织细胞色素c 氧化酶活性和热传导率显著增加,而暖温组(30℃ )显著降低; (4)室温和低温下,剃毛导致摄入能、BMR、NST 和热传导率显著增加;结果表明:被毛的作用与环境温度有关,低温下被毛降低了能量需求,增强了动物应对低温环境的适应能力;被毛的适应性变化是独居的野生小型哺乳动物应对环境温度季节性波动的主要适应策略之一,在其能量代谢和体温调节中具有重要作用和意义。     

黑龙江省东完达山地区东北虎猎物种群现状及动态趋势

猎物种群丰度是限制虎分布和数量的关键因子,因此猎物种群密度监测和估算是虎保护的重要内容之一。应用采用大样方法,地理信息系统技术和多元统计分析,研究了黑龙江东完达山东部地区东北虎猎物种群(马鹿、狍子和野猪)现状及动态变化趋势。结果表明:研究地区马鹿的种群平均密度为(0.2010±0.0270)只/km²、狍子的平均种群密度为(0.4980±0.0436)只/km²、野猪的平均种群密度为(0.3423±0.0275)只/km²。单因素方差分析表明,在相同生境下,3种有蹄类密度在在阔叶混交林中和杂木林中差异极为显著;不同的生境,3种猎物的猎物的密度也存在着显著差异。相关分析表明马鹿密度和野猪密度程正相关,而马鹿密度和狍子密度、狍子密度和野猪密度则不相关。 同1989年该地区东北虎猎物种群相比:1989-2002年的13 a时间内马鹿的年平均递减率为13.48%、狍子的年平均递减率为12.69%、野猪的年平均递减率为1.89%。     

Probing electron transfer reactions between two azurins from Alcaligenes xylosoxidans GIFU 1051 with optically active Ru complexes as molecular recognition probes: Importance of the 43rd residue

Electron transfer reactions between optically-active Ru^II/III complexes incorporating (S)-/(R)-amino acids, and the two azurins, azurin-1 (az-1Cu) and azurin-2 (az-2Cu) isolated from Alcaligenes xylosoxidans GIFU 1051, have been studied to probe molecular recognition sites on the two azurins. The Ru^II/III complexes are K[Ru^II(L)(bpy)] and [Ru^III(L)(bpy)], and have a tripodal ligand (L) derived from the (S)-/(R)-amino acids, which are in turn exchanged for other functional substituent groups, such as (S)-/(R)-phenylalanine, -leucine, -valine, -alanine, and -glutamic acid (L = (S)-/(R)-BCMPA, -BCMLE, -BCMVA, -BCMAL, and -BCMGA). In the oxidation reaction of az-1Cu^I promoted by the Ru^III complexes, the kinetic parameters exhibited enantio- and stereo-selectivities, while the same reaction of az-2Cu^I was less enantio- and stereo-selective. These differences suggest that the processes of formation of the activated states are different for the two azurins. On the other hand, such a difference has not been observed for az-1 and az-2 with respect to the reduction reactions promoted by both azurins Cu^II by the Ru^II complexes within the experimental error. This suggests that the neutrality of the Ru complexes is important for precise molecular recognition of azurins. His117 has been proposed as the electron transfer site. The local structures in the vicinity of the His117 side chain in the two azurins, are essentially identical with the exception of the 43rd residue, Val43 and Ala43 for az-1 and az-2, respectively. Electron transfer reactions between Ru^III complexes and a mutant azurin, V43A-az-1, were also carried out. Interestingly, the activation parameters estimated were very similar to those of az-2, indicating that the 43rd residue acts as the electron transfer site in azurins and provides rationalization for the different mechanisms of az-1 and az-2 in redox reactions.     

Molecular dynamics study of the proposed proton transport pathways in [FeFe]-hydrogenase

Possible proton transport pathways in Clostridium pasteurianum (CpI) [FeFe]-hydrogenase were investigated with molecular dynamics simulations. This study was undertaken to evaluate the functional pathway and provide insight into the hydrogen bonding features defining an active proton transport pathway. Three pathways were evaluated, two of which consist of water wires and one of predominantly amino acid residues. Our simulations suggest that protons are not transported through water wires. Instead, the five-residue motif (Glu282, Ser319, Glu279, H₂O, Cys299) was found to be the likely pathway, consistent with previously made experimental observations. The pathway was found to have a persistent hydrogen bonded core (residues Cys299 to Ser319), with less persistent hydrogen bonds at the ends of the pathway for both H₂ release and H₂ uptake. Single site mutations of the four residues have been shown experimentally to deactivate the enzyme. The theoretical evaluation of these mutations demonstrates redistribution of the hydrogen bonds in the pathway, resulting in enzyme deactivation. Finally, coupling between the protein dynamics near the proton transport pathway and the redox partner binding regions was also found as a function of H₂ uptake and H₂ release states, which may be indicative of a correlation between proton and electron movement within the enzyme.     

Reactions and structures in the gallium(III)/indium(III)-N,N-dimethylthioformamide systems

The structure of the N,N-dimethylthioformamide (DMTF) solvated gallium(III) ion has been determined in solution by means of extended X-ray absorption fine structure (EXAFS) spectroscopy. The gallium(III) ion is four-coordinate in tetrahedral fashion with a mean Ga-S bond distance of 2.233(2) Å in DMTF solution. At the dissolution of indium(III) perchlorate or trifluoromethanesulfonate in DMTF coordinated solvent molecules are partly reduced to sulfide ions, and a tetrameric complex with the composition [In₄S₄(SHN(CH₃)₂)₁₂]⁴⁺ is formed. The structure of the solid tetrameric complex in the perchlorate salt was solved with single crystal X-ray diffraction. Four indium(III) ions and four sulfide ions form a highly symmetric heterocubane structure where each indium binds three bridging sulfide ions and each sulfide ion binds three indium(III) ions with a mean In-S bond distance of 2.584(1) Å, and S-In-S angles of 90.3(1)°. Each indium(III) additionally binds three DMTF molecules at significantly longer mean In-S bond distance, 2.703(1) Å; the S-In-S angles are in the range 80.3-90.4°. Large angle X-ray scattering data on a DMTF solution of indium(III) trifluoromethanesulfonate show that the same tetrameric species characterized in the solid state is also present in solution, whereas the EXAFS measurements only give information about the In-S bond distances due to the short core hole lifetime.     

Population Dynamics of Plant Nematodes in Cultivated Soil: Effect of Summer Cover Crops in Old Agricultural Land

In a 6-year cover crop sequence study, nematode population densities varied with different cover crops. Millet favored rapid increase of Belonolaimus longicaudatus and supported relatively large numbers of Pratylenchus brachyurus. Beggarweed and ''Coastal'' bermudagrass favored rapid increase of B. Iongicaudatus and to a lesser extent P. brachyurus and Trichodorus christiei. Hairy indigo and Crotalaria supported relatively large numbers of P. brachyurus but suppressed B. longicaudatus. Hairy indigo also supported increases of T. christiei and Xiphinema americanum. Marigold did not favor development of any parasitic nematode species present. Tomato transplant yield was inversely related to nematode population, particularly to B. Iongicaudatus. Largest yields were obtained from plots with smallest numbers of B. longicaudatus and smallest yields were from plots with largest numbers of B. longicaudatus.     

Application of carbohydrate microarray technology for the detection of Burkholderia pseudomallei, Bacillus anthracis and Francisella tularensis antibodies

We developed a microarray platform by immobilizing bacterial 'signature' carbohydrates onto epoxide modified glass slides. The carbohydrate microarray platform was probed with sera from non-melioidosis and melioidosis (Burkholderia pseudomallei) individuals. The platform was also probed with sera from rabbits vaccinated with Bacillus anthracis spores and Francisella tularensis bacteria. By employing this microarray platform, we were able to detect and differentiate B. pseudomallei, B. anthracis and F. tularensis antibodies in infected patients, and infected or vaccinated animals. These antibodies were absent in the sera of na?ve test subjects. The advantages of the carbohydrate microarray technology over the traditional indirect hemagglutination and microagglutination tests for the serodiagnosis of melioidosis and tularemia are discussed. Furthermore, this array is a multiplex carbohydrate microarray for the detection of all three biothreat bacterial infections including melioidosis, anthrax and tularemia with one, multivalent device. The implication is that this technology could be expanded to include a wide array of infectious and biothreat agents.