中国中西部五大山系间社鼠头骨形态的地理分化

种群分化是物种形成过程中的关键一步,通过形态特征进行种内变异的探讨对揭示微进化过程具有积极
意义。本文以社鼠头骨为材料,通过SPSS 统计分析软件对采集自我国中西部5 大山系的250 号标本头骨形态变
量进行了判别函数分析,结果表明秦岭与四川各山系之间社鼠头骨已发生完全分化,而在四川各山系之间,除
邛崃和相岭山系外,其余各山系社鼠头骨形态已分化明显。腭长、上颌齿隙长等变量是各山系社鼠头骨样本发
生分化的主要变量,暗示上述山系之间社鼠头骨形态的分化可能主要来自于局部种群在食物资源及觅食习性等
方面的差异。除此之外,本文研究结果尚揭示了在对具有广泛分布的小型兽类进行种下阶元(如亚种) 的划分
时,需充分考虑形态特征可能存在的地理差异。     

四川藏鼠兔头骨形态的种群分化

种群分化是物种形成过程中具有决定意义的一步,是研究微进化过程的核心内容.为探讨地理隔离对小型兽类种群分化的影响,本文系统比较了四川西部3个隔离藏鼠兔Ochotona thibetana种群在头骨形态上的异同.结果表明在所测量的19个头骨形态指标中,岷山与邛崃山、邛崃山与凉山、岷山与凉山的藏鼠兔种群已分别在9、14及4个头骨变量上存在明显差异,颧宽、眶间宽、鼻骨长等变量是导致该3个山系藏鼠兔种群头骨形态发生分化的主要变量.由于藏鼠兔在各山系内部属一较为常见的物种,分析认为其头骨形态的种群分化可能与隔离状态下局部环境差异导致的选择压力不同有关.本研究揭示了在进行藏鼠兔等小型兽类种及种下阶元划分时,除数理统计手段引入的必要外,尚应充分考虑不同地理区域种群可能已产生的局部分化.     

云南高山姬鼠头骨的几何形态学研究

表型可塑性是指同一基因型在不同环境条件下而产生多种不同表现型的反应能力。哺乳动物头骨形态的变化是在进化过程中出现的重要表型特征之一。云南省地势西高东低、海拔变化剧烈、是古北界寒带物种南迁,中南半岛热带物种北移的交汇地,自然环境的地带性和非地带性变化明显,栖息在该地区的动物为了适应多样的环境,可能出现不同的表型分化。高山姬鼠(Apodemus chevrieri)为我国特有种,主要分布在中国西南的横断山及其附近地区,是研究表型与生态适应之间关系的理想物种。为研究在云南特殊生态环境下物种的微进化,采用几何形态学的方法测量云南不同地区高山姬鼠头骨形态的变异,采用线粒体细胞色素b(Cytochrome b,Cyt b)基因和线粒体控制区(Mitochondrial control region,D-loop)探讨基因型的变化。结果显示:昆明种群与横断山种群(中甸、剑川、丽江)间发生了明显的形态变异和遗传分化,高山姬鼠头骨背面和腹面,横断山种群和滇中昆明种群很少重叠,这两个种群变异较大;但头骨的侧面和下颌侧面变异不明显。因此,分布于云南地区的高山姬鼠可能正处于生态物种形成的早期阶段。     

横断山区高山姬鼠（Apdoemus chevrieri）头骨几何形态分析

研究对分布于横断山区（从北到南：巴塘、中甸、宁蒗、景东）的高山姬鼠头骨背面、腹面、侧面及下颌侧面的形态特征进行主成分分析、判别分析、薄片样条分析和多维尺度分析,以进一步探讨高山姬鼠头骨形态变异与环境之间的关系。研究结果表明,高山姬鼠头骨的背面和腹面在研究多种群头骨形态时更适宜,更有参考价值;经过薄片样条法分析显示形变集中在鼻骨、眼眶和臼齿,这可能与高山姬鼠生存的横断山从北到南的气候和地理环境变化相关;经多维尺度分析显示横断山地区的高山姬鼠的头骨发生了变异,这可能与高山姬鼠生活环境的经度和纬度有关。综上,横断山区的高山姬鼠种群的头骨形态有一定的变异,这可能反映了其对横断山不同生态环境的形态适应性变异．     

横断山区高山姬鼠臼齿特征的研究

高山姬鼠Apodemus chevrieri分布在横断山及其附近地区。臼齿在动物的生存和生态适应中起着重要的作用。为探讨横断山环境对高山姬鼠臼齿表型变异的影响,本研究采用几何形态测量法对横断山由北到南(东北:巴塘;中部:中甸和宁蒗;南部:景东)分布的高山姬鼠的上臼齿(第一上臼齿、第二上臼齿、第三上臼齿)和下臼齿(第一下臼齿、第二下臼齿、第三下臼齿)进行测量,并进行主成分分析、薄片样条分析和多维尺度分析。研究结果表明,横断山高山姬鼠各地理种群间的臼齿有一定形态变异,薄片样条法分析显示各臼齿齿叶间有一定的形变发生,这可能与高山姬鼠在横断山各地区生存环境有关。     

基于细胞色素b基因的中国岩羊不同地理种群遗传差异分析

为了揭示中国岩羊不同地理种群的遗传差异,探讨岩羊亚种分化的分子机制,采用中国岩羊不同地理种群的细胞色素b(Cyt b)基因的全序列,分析了碱基变异情况、遗传距离以及核苷酸序列差异。用最大似然法和贝叶斯法构建分子系统树并对获得的拓扑结构进行分析。结果发现,西藏亚种与四川亚种Cyt b基因平均序列差异为4.2%(±0.007),处于偶蹄目亚种的序列差异范围内,支持了目前对岩羊西藏亚种的分类地位。四川亚种内部各地理种群之间的遗传距离(0.033±0.0 111)与它们分别到西藏种群的遗传距离(0.042±0.007)差异不显著(t=1.824,P=0.084),说明四川亚种内部各地理种群间已经发生较显著的遗传分化。其中,四川、甘肃和青海种群亲缘关系较近,并与四川亚种内部的其它种群已产生了显著的遗传分化。因此认为四川亚种内部各地理种群的种下分化需要深入研究。     

神农架地区4种啮齿类食性及脏器形态差异比较

生活在同一地域的物种,会因强烈的资源竞争而产生生态位重叠与分离,从而实现相互共存。以神农架地区啮齿动物为研究对象,比较分析不同啮齿类食性、脏器重量及消化道形态差异,探索其共存机制及其生理生态学上的适应策略。食性上,安氏白腹鼠(Niviventer andersoni)、社鼠(N.confucianus)、高山姬鼠(Apodemus chevrieri)、中华姬鼠(A.draco)均为杂食者,但各自喜食偏好不同,安氏白腹鼠的食物组成以植物枝叶和种子为主,社鼠、高山姬鼠和中华姬鼠的食物组成均以种子和动物性食物为主。与各自生态习性及其食性相适应,不同啮齿动物的脏器重量及消化道形态发生相应的变化。脏器重量上,不同啮齿动物心鲜重、肺鲜重、脾鲜重和干重无显著差异,其它指标差异显著。安氏白腹鼠的心干重、肺干重、肝鲜重和干重、肾鲜重和干重显著大于社鼠、高山姬鼠和中华姬鼠。消化道形态上,不同啮齿动物盲肠长、净鲜重和干重无显著差异,其它指标差异显著。其中,胃含内容物鲜重、净鲜重和干重,盲肠含内容物鲜重,大肠长、含内容物鲜重、净鲜重和干重均以安氏白腹鼠具较大值,但各自变化趋势不同;小肠长、含内容物鲜重、净鲜重和干重则以社鼠具较大值。且同属姬鼠属的高山姬鼠和中华姬鼠脏器重量及消化道形态各指标间均无显著差异。由于小泡巨鼠和猪尾鼠数量较少,未进行统计分析。以上结果显示:食物资源利用上的分化有利于安氏白腹鼠与其近缘物种社鼠及其他鼠类的同域共存,且为适应不同的食物资源利用模式,其脏器及消化道形态也发生了适应性的变化;同域分布的近缘物种高山姬鼠、中华姬鼠则有可能采取其它策略而非食物资源分化模式实现共存。     

高原鼢鼠(Eospalax baileyi)头骨形态的地理分化

运用单因素方差分析、主成分分析、判别分析和聚类分析,对高原鼢鼠(Eospalax baileyi)4个地区(临潭、天祝、玛曲和碌曲)8个地理群体的头骨形态特征进行综合分析,比较13个特征变量的地理分异,挖掘形态特征的主要变量,并探讨其形态变异与环境的关系。结果发现,群体间13个特征变量均存在显著差异,主成分分析表明13个头骨特征变量可用3个主成分来表述,其累计贡献率达96.981%。颅全长、上齿列长及齿隙长是高原鼢鼠头骨发生分化的主要变量。天祝种群与碌曲种群,及玛曲种群与临潭种群都有重叠,其中碌曲的两个种群相似性最高,玛曲种群和临潭种群与其他种群几乎无重叠,显示完全分化,聚类分析结果与判别分析结果一致。头骨形态与地理因子的相关性分析发现头骨形态大小与海拔成显著的正相关关系。综合分析认为地理隔离、栖息地海拔因子影响下的生态条件等是高原鼢鼠头骨分化的主要因素。     

中华姬鼠与大林姬鼠头骨的几何形态学研究

中华姬鼠Apodemus draco和大林姬鼠A.peninsulae形态与习性相似,北京地区的这两种鼠都存在还是只有大林姬鼠存在一直存在争议.通过新兴的几何形态测量技术对北京地区捕获的137只姬鼠头骨与黑龙汀的9只大林姬鼠头骨进行背面和侧面的形态对比分析.系统聚类分析结果、主成分分析结果和判别函数分析结果显示,北京地...     

大蹄蝠头骨形态地理变化

本文采用几何形态测量法对中国大蹄蝠9个不同地理种群头骨形态变化进行研究。结果表明,不同地理种群的头骨大小及形状存在显著差异,其中云南思茅种群与海南陵水种群差异最大。回归分析表明头骨形态的地理变化与气候因素相关。随着年均温度、年均湿度的升高以及年均降水量的增多,大蹄蝠头骨变小,上颌、齿、咬肌附着部分以及耳蜗部分的形状发生变化。此外,头骨大小与海拔高度呈正相关,头骨形状变化与纬度显著相关。本研究表明对栖息地生态条件的适应是中国大蹄蝠头骨形态地理变化的重要原因。     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。