Adaptive reactions of dehydrogenation processes in root voles during additional impacts of the physical nature

Variations of the dehydrogenation enzyme activity (succinate dehydrogenase, pyruvate dehydrogenase, lactate dehydrogenase) in the heart muscle, liver and brain of root voles (Microtus oeconomus Pall.) and their progeny associated with additional stress effects (chronic low-level gamma-irradiation, short-term exposure to cold) have been studied. Root voles (parents) were caught in the areas with a normal and high-level natural radioactivity in the Republic of Komi. It has been revealed that the direction of shifts of the dehydrogenation enzyme activity in response to the factors of the physical nature is determined by the initial level of the oxidation process in tissues of root voles and their progeny that haven't been subjected to these actions. The reaction of root voles and their progeny (1-3 generations) from the radium zone has lower reserve functional possibilities in relation to the additional exposure as compared with the animals from the control zone. In some cases, chronic low-level irradiation and short-term cooling lead to leveling of differences between groups of animals which initially varied from each other in biochemical indexes.     

Effect of increased natural radioactivity on bone marrow morphology of Microtus oeconomus pall

It was established that Microtus oeconomus Pall. living in territories with the increased radiation background exhibit focal myeloid hyperplasia in the bone marrow, changes in the maturation indices of erythroid and myeloid elements, increase in number of karyocytes due to the increase in their mitotic activity. It is suggested that activation of vole haemopoiesis is an adaptive reaction of the organism to the effect of the radioecological factor.     

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.     

Effect of low doses of ionizing radiation on bone marrow cell chromosomes in Microtus oeconomus Pall

It is shown that Microtus oeconomus Pall. living in conditions of enhanced natural radioactive background do not suffer from the increased radioactivity with regard to the induction of cytogenetic disturbances in bone marrow cells. It is supposed that these animals are more radioresistant than Microtus oeconomus Pall. living in vivaria.     

Karyological and dental identification of Microtus limnophilus in a large focus of alveolar echinococcosis (Gansu, China).

A study of voles (Arvicolidae, Rodentia) from Gansu (China) designed to identify a potential host of Echinococcus multilocularis, responsible for human alveolar echinococcosis, leads to a general analysis of Microtus limnophilus population karyotypes, M1 of M. oeconomus populations from all of Eurasia and of M. limnophilus of Mongolia. The Microtus of Gansu belonging to the nominal subspecies M. limnophilus limnophilus (2n = 38; NF = 58) differs markedly in size and shape of M1 from the M. limnophilus of Mongolia, which must therefore be considered as a new subspecies M. limnophilus of malygini nov. ssp. (2n = 38; NF = 60) and the M. oeconomus of Mongolia should be ranked as M. oeconomus kharanurensis nov. ssp. (2n = 30; NF = 60).     

Energy-Metabolising Enzymes in Brain Regions of Adult and Aging Rats

Abstract: The regional enzyme activities of glucose metabolism in the rat brain were investigated. Hexokinase (EC 2.7.1.1) and pyruvate dehydrogenase (EC 1.2.4.1), key enzymes for glucose metabolism, showed no changes in activity in all the regions studied of the aging brain as compared with the adult brain. However, the activity of d -3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) is low throughout the adult brain and, in contrast with hexokinase and pyruvate dehydrogenase, its activity decreases significantly during aging. Other enzymes that showed significant decreases during aging are aldolase (EC 4.1.2.13), lactate dehydrogenase (EC 1.1.1.27), citrate synthase (EC 4.1.3.7), and NAD⁺-linked isocitrate dehydrogenase (EC 1.1.1.41). The catabolic enzyme in cholinergic metabolism, acetylcholinesterase (EC 3.1.1.7), selected as an example of a non-energy-metabolising enzyme, also showed significant decreases in all regions of the brain in aging, although its highest activity remained in the striatum. These results are discussed with respect to the energy metabolism in various brain regions and their status with aging.     

The phospholipid composition of the liver in root voles living under different radioecological conditions

The effect of the increased natural radiation background (within some areas in Komi Republic) and man-caused radioactive contamination in the Chernobyl NPP accident zone on the composition of liver phospholipids in Microtus oeconomus inhabiting these areas was studied. The significant changes in the liver lipid composition in rodents inhabiting both the Chernobyl accident zone and the areas with the increased natural radiation background were found. The maximal changes in the liver phospholipid composition were revealed during the first year after the accident. The reverse dependence between the phosphatidyl choline/phosphatidyl ethanolamine ratio and the ratio between the sum of more readily oxidizable phospholipids and the sum of more poorly oxidizable ones was found. However, the slope of corresponding curves significantly depends on the radioactive state in the area of the population inhabitance. The conclusion about high sensitivity of the lipid composition of hepatocytes in Microtus oeconomus both to the impact of the man-caused radioactive contamination and the increased level of the natural radioactivity was drawn.     

Pattern of X-Y chromosome pairing in the Taiwan vole, Microtus kikuchii.

Pairing of X and Y chromosomes at meiotic prophase and the G- and C-banding patterns and nucleolar organizer region (NOR) distribution were analyzed in Microtus kikuchii. M. kikuchii is closely related to M. oeconomus and M. montebelli, karyologically and systematically. The formation of a synaptonemal complex between the X and Y chromosomes at pachytene and end-to-end association at diakinesis--metaphase I are only observed in three species in the genus Microtus; M. kikuchii, M. oeconomus, and M. montebelli. All the other species that have been studied so far have had asynaptic X-Y chromosomes. These data confirm that M. kikuchii, M. oeconomus, and M. montebelli are very closely related, and support the separation of asynaptic and synaptic groups on the phylogenetic tree.     

单宁酸对高原鼠兔和根田鼠生殖激素的影响

高原鼠兔和根田鼠是生存于青藏高原的小哺乳动物,它们所取食的高原植物含有多种次生化合物。为了证明食物中的次生化合物对高原鼠兔和根田鼠繁殖相关激素的影响,探讨它们与取食植物间的协同进化,分别对两种动物灌服0、5、10 和20 mg/ kg BW 剂量单宁酸1 d、3 d 及5 d 后,测定其下丘脑促性腺激素释放激素、血浆中睾酮和血浆雌二醇的含量。结果表明,单宁酸对高原鼠兔的LD₅₀ 为112 ±27.72 mg/ kg BW,对根田鼠的LD₅₀ 为117 ± 17.37 mg/ kg BW;单宁酸可以使高原鼠兔和根田鼠血浆睾酮和雌二醇水平升高,但对下丘脑促性腺激素释放激素水平没有明显的影响。说明单宁酸可能会促进这两种动物的性成熟,有利于它们的繁殖。     

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.     

Species specificity of karyotype instability under conditions of radionuclide contamination (the Chernobyl Nuclear Power Plant) in the voles, Micrototus oeconomus, Micrototus arvalis, and Clethrionomys glareolus

The comparative analysis of frequencies of different type cytogenetic anomalies in voles Microtus oeconomus, Microtus arvalis, Clethrionomys glareolus trapped in territories with different levels of radionuclide contamination inside the 30-km zone of estrangement around the Chernobyl NPP was carried out. Animals with constitutive chromosome abnormalities were not revealed. The frequency of lympocytes with micronuclei was the most universal and sensitive character to chronic low-dose radiation in investigated species. The species-specific relation was observed between level of radionuclide contamination in trapping zone and increase in frequencies of cytogenetic abnormalities: aneuploidy in Microtus arvalis and metaphase plates with asynchronous centromere fission in Microtus oeconomus. Common vole appears to be the most sensitive species of investigated ones to chronic low-dose ionizing irradiation.     

Enzymatic and Ultrastructural Changes in Thoracic Muscles of Triatomine Insects during the Last Stages of Metamorphosis

Dipetalogaster maximus and Triatoma infestans are hematophagous insects, vectors of Chagas' disease. After the last molt of their metamorphosis, from fifth instar nymph to adult, they acquire wings and the ability to fly, which is important for their dispersal. Some biochemical changes accompanying this last stage have been studied by determining activity of hexokinase (EC 2.7.1.1), fructose-6-phosphate kinase (EC 2.7.1.11), glucose-6-phosphate dehydrogenase (EC 1.1.1.49), glutamate dehydrogenase (EC 1.4.1.4), aspartate aminotransferase (EC 2.6.1.1), malate dehydrogenase (EC 1.1.1.37) and glycerol-3-phosphate dehydrogenase (EC 1.1.1.8) in thoracic muscle extracts of fifth instar nymphs and adults. Activity of all the enzymes, expressed in U per mg protein, was significantly higher in muscles of adults than of nymphs, except that of aspartate aminotransferase, had lower activity in adults of T. infestans. The increase of glycerol-3-phosphate dehydrogenase activity was particularly striking (30-fold), while the increase in glucose-6-phosphate dehydrogenase activity was of a lesser magnitude than those observed for other enzymes. Comparative ultrastructural studies of thoracic muscles showed that in adult preparations mitochondria were more numerous and larger in size, and presented more cristae than in muscles of fifth instar nymphs. The biochemical changes detected appear to be the expression of the adaptation of adult muscles for flight activity. Thus, adult muscles would have higher glycolytic and respiratory capacity than those of fifth instar nymphs. The operation of systems transferring hydrogen into mitochondria, especially that of the glycerophosphate shuttle, may be greatly increased in adult muscles.     

Cytogenetic effect of the action of apretana on the bone marrow cells of Microtus oeconomus

A frequency of aneuploid cells and mitotic activity induced in bone marrow cells of Microtus oeconomus by apretan was examined. Treatment with doses 10 g per kg of the weight increased the frequency of aneuploidy from 5.4 to 29.6% and that of the mitotic activity two times. The possible reasons for these data are discussed.     

Schistosoma haematobium: oxidoreductase histochemistry and ultrastructure of niridazole-treated females

Administration of niridazole to Saccostomus campestris produced changes in enzyme activity in Schislosoma haematobium females as indicated histochemically by a decrease in the activity of cytochrome oxidase (EC 1.9.3.1), malate (NAD) dehydrogenase (EC 1.1.1.37), malate (NADP) dehydrogenase (EC 1.1.1.40), succinate dehydrogenase (EC 1.3.99.11), isocitrate (NAD) dehydrogenase (EC 1.1.1.41), isocitrate (NADP) dehydrogenase (EC 1.1.1.42), lactate dehydrogenase (EC 1.1.1.27), glucose-6-phosphate dehydrogenase (EC 1.1.1.49), NADH: tetrazolium oxidoreductase, NADPH: tetrazolium oxidoreductase, and a disappearance of both the activity of phenolase (EC 1.10.3.1) and the reactivity of vitelline phenols. These changes were associated with the following alterations in the ultrastructure of the parasites: a decrease in number of immature vitelline cells of gonial type, a disruption of the tegument surface, a swelling of mitochondria in vitelline cells, a disappearance of the regular structure of the endoplasmic reticulum and a vaeuolization of the cytoplasm in vitelline cells, an appearance of areas of focal cytoplasmic degradation in vitelline cells, and a disruption of shell globules. The degree of changes in enzyme activity and ultrastructure increased both with increase in the dose of niridazole administered to the hosts, and with length of time after treatment.Preincubation of control sectioned material in a buffered niridazole-sucrose solution produced total inhibition of succinate dehydrogenase activity, whereas the activity of other enzymes examined remained unchanged.     

根田鼠视网膜的胚后发育

视觉对动物的生活习性尤其是取食具有重要意义。本文对根田鼠视网膜的胚后发育进行了研究,结果表明:出生3d内根田鼠视网膜分化程度较低,神经节母细胞层尚未分化,占据了视网膜层的一半以上;5日龄时,外网层开始出现;6日龄时,外网层开始清晰,外核层与内核层更加清晰;18日龄时,视网膜结构与成年根田鼠结构相似,各层结构清晰可见。测量了神经节细胞层和外核层的细胞密度以及核层厚度,结果表明:随着个体发育,外核层细胞层厚度及细胞密度不断增加;而神经节细胞层厚度及细胞密度不断减少。与褐家鼠、黑线姬鼠、大仓鼠、棕色田鼠、甘肃鼢鼠、达乌尔黄鼠、岩松鼠视网膜相比,根田鼠视网膜结构介于夜行性与昼行性鼠类之间[动物学报52(2):376-382,2006]。     

高原鼢鼠四肢骨的进化适应性分析

通过对比分析了高寒草甸生态系统的高原鼢鼠(Myospalax baileyi)、高原鼠兔(Ochotona curzoniae)及根田鼠(Microtus oeconomus)的四肢骨,结果表明,地下啮齿动物高原鼢鼠的四肢骨比地面种类高原鼠兔和根田鼠的对应骨骼粗壮,显示其较强的挖掘能力。与挖掘效率相关的尺骨挖掘动力臂系数,高原鼢鼠为0.3617,而高原鼠兔和根田鼠不到0.17。高原鼢鼠与其他两物种的四肢骨重量分布也明显不同:高原鼢鼠的前肢骨重量超过后肢骨,而高原鼠兔及根田鼠则正好相反;高原鼠兔及根田鼠的桡尺骨重量在四肢骨中最低,而高原鼢鼠的桡尺骨重量在四肢骨中则最高。这些特征反映了地下啮齿动物为了适应地下生活方式,其四肢骨骼系统已经发生了显著变化,这对于研究地下啮齿动物的进化适应性问题具有重要意义。     

高寒草甸地区小哺乳动物群落多样性的初步研究

高寒苹甸地区的人工草场、半人工草场、次生杂类草草场和撩荒地中共有4个小哺乳类群落;根田鼠+高原鼢鼠群落;根田鼠+甘肃鼠兔群落;高原鼠兔+高原鼢鼠群落;长尾仓鼠+高原鼠兔群落。小哺乳类群落种的多样性与植物群落种的多样性无显著相关关系,而与植被的高度、盖度呈显著负相关关系。高原鼢鼠是各生境中的广布种。根田鼠与甘肃鼠兔在植被郁闭度高的环境中为群落的主要组成者;植被郁闭度低的环境中,高原鼠兔和长尾仓鼠是群落的主要成员。它们的空间格局主要反映空间环境条件的差异。     

Activities of enzymes concerned with pyruvate and oxaloacetate metabolism in the heart and liver of developing sheep.

1. In order to assess whether the potential ability of heart ventricular muscle and liver to metabolise substrates such as alanine, aspartate and lactate varies as the sheep matures and its nutrition changes, the activities of the following enzymes were determined in tissues of lambs obtained at varying intervals between 50 days after conception to 16 weeks after birth and in livers from adult pregnant ewes: lactate dehydrogenase (EC 1.1.1.27), alanine aminotransferase (EC 2.6.1.2), pyruvate kinase (EC 2.7.1.40), pyruvate carboxylase (EC 6.4.1.1), phosphoenolpyruvate carboxykinase (GTP)(EC 4.1.1.32), malate dehydrogenase (EC 1.1.1.37), aspartate aminotransferase (EC 2.6.1.1) and citrate (si)-synthase (EC 4.1.3.7). 2. In the heart a most marked increase in alanine aminotransferase activity was found throughout development. During this period the activities of citrate (si)-synthase, lactate dehydrogenase and pyruvate carboxylase also increased. There were no substantial changes in the activities of aspartate aminotransferase, malate dehydrogenase or pyruvate kinase. Pyruvate kinase activities were five times greater in the heart compared with those found in the liver. No significant activity of phosphoenolpyruvate carboxykinase (GTP) was detected in heart muscle. 3. In the liver the activities of both alanine aminotransferase and aspartate aminotransferase increased immediately following birth although the activity of alanine aminotransferase was lower in livers of pregnant ewes than in any of the lambs. As with alanine aminotransferase the highest activities of lactate dehydrogenase were found during the period of postnatal growth. No marked changes were observed in malate dehydrogenase or citrate (si)-synthase activities during development. A small decline in pyruvate kinase activity occurred whilst the activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase (GTP) tended to rise during development.     

Polymorphism of several dehydrogenases in the skin of sheep and their fetuses

The total activity and isoenzyme spectra of lactate dehydrogenase (EC 1.1.1.27), malate dehydrogenase (EC 1.1.1.37), glutamate dehydrogenase (EC 1.4.1.2) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) were studied in the skin of sheep and their fetuses. There are 5 multiple molecular forms of LDG, 4--of GDG, 2--of MDG and 1--of G-6-PDG in the skin. It is established that the skin of adult sheep and fetus is similar as to the studied parameters.