布氏田鼠对主要贮草种类的选储嗜好

布氏田鼠 (Ｍｉｃｒｏｔｕｓｂｒａｎｄｔｉ)为内蒙古典型草原区的主要害鼠 ,其危害主要表现在与牲畜争夺牧草资源[1,3 ,5,6,9] 。该鼠属不冬眠种类 ,冬季主要以洞群贮草仓库中的贮草为食 ,因此 ,研究其秋季集群的贮草习性 ,对于分析和了解该鼠的越冬生态特征具有一定的意义。有关布氏田鼠的贮草习性 ,已有一些报道[4 ,7] 。研究表明 ,在羊草 冷蒿 隐子草草场 ,布氏田鼠的越冬贮草以蒿属 (Ａｒｔｅｍｉｓｉａ)植物为主 ,其中冷蒿 (Ａ .ｆｒｉｇｉｄａ)与黄蒿 (Ａ .ｓｃｏｐａｒｉａ)占贮草比例超过 90 % [2 ] ,但上述研究均未涉及布氏田鼠…     

Chromosomes and DNA of Microtus

Newborn Microtus agrestis were given single acute whole-body -irradiation (350, 500, or 750R). C-banded bone marrow preparations showed cells with radiation-induced rearrangements of constitutive heterochromatin of the sex chromosomes, usually the consequence of single events, encompassing a wide spectrum of deletions and translocations. These cells persisted in bone marrow for more than a year after irradiation; however, many cells showing the same redistribution of heterochromatin constituted clones of both deletions and translocations. These results indicate that deletion or rearrangement of constitutive heterochromatin does not impair the capacity of bone marrow cells for further proliferation.     

Nitrogen Requirements of Microtus rossiaemeridionalis

Total nitrogen requirements in the small herbivorous rodent Microtus rossiaemeridionaliswere studied. When provided with two kinds of standard laboratory food (about 20% and 0% digestible protein, respectively) ad libitum(cafeteria diet), the voles chose a diet of 14% protein. The total daily (with urine and faeces) nitrogen losses were, in this case, determined as 3.65 ± 0. 60 mg N/ g of body mass. When provided with a protein-free diet alone, the animals lost 0.90 ± 0,05 mg N/ g body mass per day, comprising about 3% of their body mass daily. It was proposed that the consumption of a low-fiber diet (about 4% in both kinds of food) could affect the gastrointestinal bacterial flora and, thus, lead to changes in the primarily herbivorous nitrogen metabolism.     

东方田鼠长江亚种和指名亚种基因组DNA序列比较分析

根据东方田鼠基因组DNA序列片段(CenBank登录号：AF277394),通过PCR方法扩增东方田鼠长江亚种(Microtus fortis calamorum)和宁夏指名亚种(Microtus fortis fortis)基因组DNA,得到-670bp左右的特异扩增片段。将PCR扩增产物克隆到pGEM-Teasy裁体,进行DNA序列分析,并用生物信息学方法比较东方田鼠长江亚种与指名亚种之间该序列的差异。结果表明：在东方田鼠两个亚种中共发现19个不同的等位基因,不同的个体在该序列存在广泛的单个核苷酸多态性(SNP),多态性位点多达25个;变换类型包括：转换(G→A、A→G、T→C、C→T)、颠换(G→T、A→T、T→A、C→A)、插入(CA)和缺失(TGTTTT)。东方田鼠长江亚种和指名亚种两个种群之间存在明显差别,尤其是在146、192、223、224、235位,但两种群间同源性仍高达98％。同时采用系统发育树(phylogenetic tree)分析方法,对两个亚种的亲缘关系进行了分析和比较,结果显示,东方田鼠长江亚种和宁夏指名亚种基因组DNA明显的分为两大组别。     

Clusters of Repetitive DNA Sequences in Chromosomes of Voles of the Subgenus Microtus (Microtus,Arvicolidae)

Russian Journal of Genetics - The study is focused on the analysis of the mechanisms underlying the formation and distribution of repeat clusters in mammalian chromosomes, as exemplified by a group...     

The repeated DNA sequences of Microtinae : I. Microtus agrestis, Microtus pennsylvanicus and Ellobius lutescens

A comparison has been made of the repeated nucleotide sequences from 3 Microtinae which possess varying amounts of constitutive heterochromatin per cell nucleus. Eight repetitive fractions of DNA, ranging in C_ot values from 10⁻³ to 10⁻³, were obtained by reassociation of sheared, denatured DNA and fractionation on hydroxyapatite. At C_ot values of less than 1, 3 fractions were isolated that amounted to 18.7, 10.0 and 7.4 % of the total DNA of Microtus agrestis, Microtus pennsylvanicus and Ellobius lutescens, respectively, in agreement with the amounts of heterochromatin in these species. At C_ot values higher than 1, the amounts of repeated sequences were more comparable and constituted about 12 to 14 % of the DNA. Thermal denaturation profiles of all the repetitive fractions showed a good deal of order in the reassociated duplexes, with an average hyperchromicity of 20 %. Upon density gradient centrifugation in neutral CsCl, the fractions from M. pennsylvanicus and E. lutescens yielded almost identical patterns and differed significantly from those of M. agrestis. In M. agrestis a fraction of fast-intermediate repetitiveness (reassociating at C_ot values between 10⁻² and 1) was isolated, amounting to about 12 % of the total DNA. This fraction has a base composition comparable to that of total DNA and represents the major component of the constitutive heterochromatin of giant sex chromosomes that have been isolated by the disruption of brain and liver nuclei and differential centrifugation.     

东方田鼠的游泳行为和能力

东方田鼠(Microtus fortis)是一种栖息于湿地生境的小型哺乳动物,为了解其水生运动适应,作者在实验室内观察和测试了该鼠的游泳行为、皮毛防水性能和长时间游泳能力。结果发现,东方田鼠主要在水面游泳,亦能潜水,游泳姿势是狗刨式,并主要以后肢交替划水提供推进力,速度约为0.37 m/s。在20℃水温条件下,东方田鼠皮毛表现出良好的防水性能,且防水性能与其年龄及体重均存在极显著的负相关关系(P 0.01,R~2=0.805);东方田鼠具有平均约持续5 h以上的长时间游泳能力,且长时间游泳能力与其皮毛防水性能存在极显著的正相关关系(P 0.01,R~2=0.682);上述两项指标性别差异显著。这表明,东方田鼠有较强的水中运动能力和长时间游泳能力,具有水生运动方面的适应性进化,有利于其在沼泽等栖息地的生存。     

Dynamics of intestinal coccidia in peak density Microtus agrestis, Microtus oeconomus and Clethrionomus glareolus populations in Finland

Study of seasonal changes in the occurrence of Eimeria spp. in Microtus agrestis, Clethrionomys glareolus and Microtus oeconomus populations in Finland showed distinct seasonal variation in all three host species: the peaks occurred in both prevalence and density of infection in early autumn. The low prevalence and density of eimerian infections before and during the main crash of vole populations in late winter indicate that these organisms, although potentially pathogenic, do not significantly contribute to the drastic decline in cyclic vole populations.     

Patterns of variation in Microtus arvalis and Microtus agrestis populations from Middle to Late Pleistocene in southwestern Europe

Fifteen paired fossil populations of Microtus arvalis and Microtus agrestis from southwestern Europe have been analysed from a morphological and morphometric point of view. The sites under consideration are located in the northern Iberian Peninsula and southern France, from the Middle Pleistocene to the end of the Late Pleistocene. The aim of this study is to stress once again the importance of keeping these two species separated in the fossil record in order to recognize specific trends of evolution and divergence and to obtain more precise information on palaeoclimatic and palaeoenvironmental conditions. It was possible to observe remarkable intraspecific differences between Middle and Late Pleistocene populations of both species. Furthermore, in synchronic co-specific populations from the Late Pleistocene, climatic and geographic conditions seem to exert a major influence in shaping intraspecific changes in dental pattern.     

甘肃鼢鼠和根田鼠听域研究

用电生理学方法对甘肃鼢鼠和根田鼠的听性脑干反应(ABR)的反应阈值做了测定,以确定甘肃鼢鼠和根田鼠听域.结果 表明甘肃鼢鼠听力敏感频率为12 kHz,根田鼠的听力敏感频率为16～32 kHz.甘肃鼢鼠和根田鼠听性脑干电位测定结果表明地下鼠和地面鼠低频高频听力阈值存在差异,地下鼠对中低频声波敏感.     

东方田鼠乳酸脱氢酶同工酶的研究

目的研究乳酸脱氢同工酶在3种东方田鼠不同器官的分布.方法以大鼠和小鼠作对照,用聚丙烯酰胺凝胶电泳对3个不同地区的东方田鼠(Microtusfortis)血清、红细胞、肝脏、肾脏、肺中乳酸脱氢酶(LDH)同工酶进行分析.结果东方田鼠血浆中只有LDH5,血清中湖南洞庭湖地区、宁夏青铜峡地区的东方田鼠也只有LDH5,而东北地区的东方田鼠则含有LDH1和LDH5,3个地区的东方田鼠肾脏和肺中都有5种LDH同工酶,肝脏中除东北地区的东方田鼠含5种LDH同工酶外,其余两种东方田鼠均以LDH5为主(LDH5占95%以上).结论东北地区东方田鼠乳酸脱氢酶同工酶谱与其他两地的东方田鼠不相同.