云南不同地区中缅树鼩头骨形态特征的比较

中缅树鼩为东洋界热带亚热带特有类群.本研究采用几何形态测量法对分布于滇中高原(禄劝县)和横断山地区(剑川县、丽江市和云龙县)的中缅树鼩头骨侧面、腹面、背面及下颌侧面的形态进行了初步研究.结果表明,主成分分析和判别函数分析显示头骨侧面和下颌侧面更适宜于区分滇中高原和横断山地区的中缅树鼩;经过薄片样条法分析显示形变多集中在鼻骨和臼齿,这可能与中缅树鼩生存的气候和地理环境相适应;经多维尺度分析显示滇中高原和横断山地区的中缅树鼩头骨有明显差异,这可能与中缅树鼩生活环境的经度和纬度有关.因此,滇中高原和横断山地区的中缅树鼩从头骨形态上可以区分开来,并且差异仅仅发生在种群水平,这可能反映了其对特定生态环境的形态适应.     

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。     

基于细胞色素氧化酶亚基Ⅰ基因的中缅树鼩地理种群遗传分化

中缅树鼩广泛分布于东南亚地区,在我国主要分布于西南地区及海南岛。本研究以中国10个地理种群共112只中缅树鼩为研究对象, PCR扩增得到1398 bp的细胞色素氧化酶亚基Ⅰ（COⅠ）基因序列,并对其进行分析。 结果显示：112个中缅树鼩COⅠ基因共定义了64个单倍型,其单倍型多样性（Hd）平均值为0.9730,核苷酸多样性（Pi ）平均值为0.04494;AMOVA方差分析显示种群间的变异占总变异的93.09%,说明中缅树鼩地理种群变异主要发生在种群间;整体遗传分化固定指数（F_ST）为0.93091,说明各地理种群中缅树鼩已出现明显的遗传分化;结合中性检验与碱基错配分布图结果表明中缅树鼩在历史进程中未经历过种群扩张现象; 基于单倍型构建的系统进化树与NETWORK网络图显示10个地理种群的中缅树鼩聚为4支：海南种群一支,大新种群一支,片马种群一支,其他种群一支。结果表明：中国不同地理种群的中缅树鼩具有较高的遗传多样性,各地理种群间已经出现了较为明显的遗传分化,地理阻隔作用可能是其分化的主要原因。     

DNA条形码技术在中缅树鼩隆安种群和昆明种群鉴定中的研究

目的:本研究利用线粒体细胞色素C氧化酶亚基I基因(CO1)的一段保守区域作为DNA条形码技术的研究序列,探讨DNA条形码技术对中缅树鼩隆安种群和昆明种群进行分类鉴定的可行性。方法:对22只广西隆安树鼩和21只昆明树鼩样本的CO1基因进行PCR扩增、测序,应用MEGA V5软件对序列进行比对及分析其遗传距离,采用NJ法构建系统发育树。结果:中缅树鼩种群中,隆安种群、昆明种群和海南亚种的种内遗传距离为0.00%-0.79%,种群间遗传距离为9.71%-13.59%,中缅树鼩与普通树鼩的种间遗传距离为20.43%-24.11%,存在条形码间隔。系统发育树显示:隆安种群、昆明种群及海南亚种分别聚为一小支,分支置信度高达100%。结论:本研究结果表明DNA条形码技术有助于树鼩种群和亚种的分类鉴定,经CO1基因的测序分析证实广西隆安树鼩和昆明树鼩分属不同的种群。     

大理和勐腊中缅树鼩血清及肝差异代谢物的比较

为探究不同海拔地区中缅树鼩(Tupaia belangeri)血清和肝的差异代谢物及代谢通路变化,本研究采集大理(高海拔)和勐腊(低海拔)中缅树鼩分别12只和8只的血清和肝,采用非靶向代谢组气相色谱-质谱联用检测技术测定代谢物.结果 表明,高海拔种群和低海拔种群相比,血清中一共有36种代谢物差异显著,其中,柠檬酸、葡萄...     

广西和云南树鼩群体遗传多样性的比较分析

目的比较分析我国广西、云南两个树鼩群体的遗传差异和分化程度,推动树鼩优良品系的培育和优化实验动物模型。方法提取广西和云南各32只树鼩的全血基因组DNA,分别采用9对荧光标记微卫星引物进行PCR扩增,通过毛细管电泳技术检测扩增片段,并利用POPGENE等软件比较两个树鼩群体的遗传相关指标。结果广西和云南两个树鼩群体平均期望杂合度(He)为0.703,平均多态信息含量(PIC)为0.725,Fis均值0。CCBL1B、CCDC61、EDA1和OPA3四个位点表现为极显著偏离哈迪-温伯格平衡。两群体的遗传距离及无偏遗传距离分别为1.277和1.268,遗传相似系数约为0.28。遗传结构变异的分布情况显示61.57%的微卫星遗传变异来自于群体内部,38.43%存在于群体之间。STRUCTURE分析发现广西和云南树鼩为中缅树鼩群体的两个不同的亚种。结论广西和云南树鼩两个群体的遗传多样性都较丰富,两个群体间具有较大的遗传差异和分化程度,遗传变异主要来源于群体内部。     

基于细胞色素b基因探讨昆明禄劝地区树鼩的分类意义

通过对云南省昆明市禄劝地区30只中缅树鼩(Tupaia belangeri)细胞色素b(Cytochrome b,Cyt b)基因全序列(1 140 bp)的遗传分析,对禄劝地区中缅树鼩;Cyt b基因特征进行初步探讨.结果表明,禄劝地区中缅树鼩Cyt b基因包含32个核苷酸变异位点,占全序列的2.81%,其转换/颠换为10.4.基于Cyt b基因的遗传距离构建的分子系统树显示,本实验研究的中缅树鼩是一个独立的分类单位而非普通树鼩(T.glis)的亚种;同时显示攀鼩目(Scandentia)与皮翼目(Dermoptera)亲缘关系较近.     

利用面包虫制作小型哺乳动物头骨标本的方法

采用面包虫制作小型哺乳动物中缅树鼩的头骨标本,探索利用面包虫剥制头骨标本的适宜条件,从而能更快、更好地制作头骨标本。该方法简单、易控制,速度快,除用于高校科研外,也可供偏远山区、少数民族地区的基层学校生物学教学。     

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。     

华南人颅骨上、下颌臼齿磨耗与年龄变化的关系

本文以华南人103例17—73岁男性颅骨的709个臼齿为材料,研究了上下颌臼齿磨耗度与年龄的关系。将磨耗度分为九级,统计分析结果表明,华南人臼齿的磨耗度与年龄关系是密切相关的,这种相关关系,能够作为估计华南人颅骨年龄的标准。第一臼齿与第二臼齿的磨耗平均年龄比率是M1∶M2=6∶6.9;磨耗度与年龄的相关系数M1为0.91,M2为0.90,均为高度相关。并得出磨耗度的平均年龄及95％置信区间(见表3)。华南人下颌臼齿的磨耗比上颌臼齿的磨耗稍大(61.5％)。     

Tupaia Belangeri as an Experimental Animal Model for Viral Infection

Tupaias, or tree shrews, are small mammals that are similar in appearance to squirrels. The morphological and behavioral characteristics of the group have been extensively characterized, and despite previously being classified as primates, recent studies have placed the group in its own family, the Tupaiidae. Genomic analysis has revealed that the genus Tupaia is closer to humans than it is to rodents. In addition, tupaias are susceptible to hepatitis B virus and hepatitis C virus. The only other experimental animal that has been demonstrated to be sensitive to both of these viruses is the chimpanzee, but restrictions on animal testing have meant that experiments using chimpanzees have become almost impossible. Consequently, the development of the tupaia for use as an animal infection model could become a powerful tool for hepatitis virus research and in preclinical studies on drug development.     

Cystathionine in the brains of tree shrews and other mammals

The amino acid cystathionine is reported to show higher concentrations in the brains of man as compared to those of other species. Two-dimensional separation by electrophoresis-chromatography and densitometric analysis of amino acids showed that the brains of tree shrews had levels of cystathionine intermediate between those of man and other mammals such as tamarins, hedgehogs, and rats. Cystathionine may be involved in the circadian rhythms ofTupaiidae. In man a 10 fold variation in cerebral cystathionine is related to pathological conditions. Greater concentrations in white matter as compared to grey matter and other regional differences in brain tissue support the findings from inherited disorders that cystathionine plays an important role in the normal as well as the abnormal functioning of the brain.     

Phylogenetic and environmental components of morphological variation: skull, mandible, and molar shape in marmots (Marmota, Rodentia)

The phenotype is a product of its phylogenetic history and its recent adaptation to local environments, but the relative importance of the two factors is controversial. We assessed the effects of diet, habitat, elevation, temperature, precipitation, body size, and mtDNA genetic divergence on shape variation in skulls, mandibles, and molars, structures that differ in their genetic and functional control. We asked whether these structures have adapted to environment to the same extent and whether they retain the same amount of phylogenetic signal. We studied these traits in intra- and interspecific populations of Eurasian marmots whose last common ancestor lived 2-5 million years ago. Path Analysis revealed that body size explained 10% of variation in skulls, 7% in mandibles, and 15% in molars. Local vegetation explained 7% of variation in skulls, 11% in mandibles, and 12% in molars. Dietary category explained 25% of variation in skulls, 11% in mandibles, and 9% in molars. Cyt b mtDNA divergence (phylogeny) explained 15% of variation in skulls, 7% in mandibles, and 5% in molars. Despite the percentages of phylogenetic variance, maximum-likelihood trees based on molar and skull shape recovered most phylogenetic groupings correctly, but mandible shape did not. The good performance of molars and skulls was probably due to different factors. Skulls are genetically and functionally more complicated than teeth, and they had more mathematically independent components of variation (5-6-in skulls compared to 3-in molars). The high proportion of diet-related variance was not enough to mask the phylogenetic signal. Molars had fewer independent components, but they also have less ecophenotypic variation and evolve more slowly, giving each component a proportionally stronger phylogenetic signal. Molars require larger samples for each operational taxonomic unit than the other structures because the proportion of within-taxon to between-taxon variation was higher. Good phylogenetic signal in quantitative skeletal morphology is likely to be found only when the taxa have a common ancestry no older than hundreds of thousands or millions of years (1% to 10% mtDNA divergence)--under these conditions skulls and molars provide stronger signal than mandibles.     

Morphometric distances and population structuring in the common shrew <Emphasis Type="Italic">Sorex araneus</Emphasis> L. (Lipotyphla: Soricidae)

The skulls of shrews of genus Sorex from eight samplings from the European part of Russia and two from the vicinity of Novosibirsk were compared. The characteristics were identified using 22 marks on the axial skull. It was found that the centroid size differs significantly in the common and Laxmann’s shrews S. caecutiens and the pygmy shrew S. minutus, while for selected marks, the common and Laxmann’s, as well as pygmy, shrews were significantly different in form, but the differences were very small between Laxmann’s and pygmy shrews. The characteristic features of the biology of the shrews Sorex are discussed, which may contribute to understanding the general laws of the morphological evolution of the genus.     

Sequence diversity of the MHC Ⅱ DRB gene in Chinese tree shrews (Tupaia belangeri chinensis)

The major histocompatibility complex (MHC) is a cluster of genes involved in vertebrate immune response regulation. MHC class I and II cell surface proteins are crucial for discrimination of self versus non-self by the adaptive immune system. Due to their special phylogenetic position within the Euarchontoglires and as a relative of primates, tree shrews have been proposed as an alternative experimental animal model for biomedical studies. However, information about the genetic structure of the tree shrew populations is largely unknown. In this study, we characterized diversity in exon 2 of the MHC II DRB gene isolated from Chinese tree shrews (Tupaia belangeri chinensis). We identified 12 different DRB exon 2 alleles from 15 Chinese tree shrews, 1 to 4 alleles were observed per individual with high levels of sequence divergence between alleles. There were more non-synonymous than synonymous substitutions in the functionally important antigen-binding site (dN/dS = 2.7952, P < 0.01), indicating that the DRB exon 2 in Chinese tree shrews has been influenced by positive selection.     

Ontogenetic and lung development in Tupaia belangeri during the early postnatal period

The Belanger's tree shrew (Tupaia belangeri) has an unusual reproductive strategy. The animals are born in altricial condition and remain in the nest for the first four weeks of life, nursed only once in 48 h. This is highly demanding for the constitution of the neonates. Despite their immaturity in the external appearance at birth, newborn tree shrews have to deal with the absence of the mother. We asked if the lung structure of the neonates match the high physiological requirements of this “absentee system”. To examine the lung development of nest young tree shrews, histological and ultrastructural investigations were performed. Newborn tree shrews are at the transition stage between the saccular and the alveolar stage of lung development. In addition to small saccules, the lung has alveoli and associated structures already at birth and thus appears more mature compared with typical altricial species. The results of the present study reveal that despite their immaturity in the external appearance newborn tree shrews are relatively mature in terms of lung development. This can be interpreted as a prerequisite for thermoregulatory abilities, necessary in neonate tree shrews to cope with the restricted nature of maternal care.     

Nasal shape,prognathism and adaptation in man

The association between nasal shape, prognathism and the shape of the maxillary dental arch has been examined within samples of Negro and European skulls. Prognathism tends to be accompanied by an increasingly broad and short nose. Particularly high correlations exist between nasal height and the length of the cranial base and between nasal breadth and the distance which separates the upper canine teeth. Regression analysis has yielded quantitative estimates of the effect on a given dimension of variation in one or more of the others. It seems probable that both nasal shape and the maxillary dental arch-prognathism complex may be subject to direct selection by environmental stress. The morphological association between these complexes suggests that a part of the interpopulation variation in prognathism may be a secondary effect of selection acting on the nose. Similarly, selection acting on the dental arch or maxilla could produce secondary changes in the nasal index (i.e. a non-adaptive component of nasal variation).