Apodemus Chevrieri Research Articles

Effects of random food deprivation and refeeding on energy metabolism, behavior and hypothalamic neuropeptide expression in Apodemus chevrieri

Maintaining adaptive control of behavior and physiology is the main strategy used by animals in responding to changes of food resources. To investigate the effects of random food deprivation (FD) and refeeding on energy metabolism and behavior in Apodemus chevrieri, we acclimated adult males to FD for 4weeks, then refed them ad libitum for 4weeks (FD-Re group). During the period of FD, animals were fed ad libitum for 4 randomly assigned days each week, and deprived of food the other 3days. A control group was fed ad libitum for 8weeks. At 4 and 8weeks we measured body mass, thermogenesis, serum leptin levels, body composition, gastrointestinal tract morphology, behavior and hypothalamic neuropeptide expression. At 4weeks, food intake, gastrointestinal mass, neuropeptide Y (NPY) and agouti-related protein (AgRP) mRNA expressions increased and thermogenesis, leptin levels, pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) expressions decreased in FD compared with controls. FD also showed more resting behavior and less activity than the controls on ad libitum day. There were no differences between FD-Re and controls at 8weeks, indicating significant plasticity. These results suggested that animals can compensate for unpredictable reduction in food availability by increasing food intake and reducing energy expended through thermogenesis and activity. Leptin levels, NPY, AgRP, POMC, and CART mRNA levels may also regulate energy metabolism. Significant plasticity in energy metabolism and behavior was shown by A. chevrieri over a short timescale, allowing them to adapt to food shortages in nutritionally unpredictable environments.

The role of dietary fiber content on energy metabolism, thermogenesis, and leptin in Chevrier’s field mouse (Apodemuschevrieri)

Food quality and availability are important factors influencing the survival and reproduction of animals. The aim of the present study was to examine the effect of dietary fiber content high-fiber (HF) diet treatment or low-fiber (LF) diet treatment) on energy metabolism, thermogenesis, and leptin concentrations in Chevrier’s field mouse (Apodemus chevrieri (Milne-Edwards, 1868)) (Mammalia: Rodentia: Muridae). Mice on the HF treatment showed a lower body mass compared with LF treatment from day 27 to day 37, and a lower but insignificant body mass to day 71. Dry matter intake (DMI) and gross energy intake (GEI) were greater in HF compared with LF, whereas the digestible energy intake (DEI) was similar for both treatments. Nonshivering thermogenesis (NST) decreased in HF mice, whereas LF mice remained stable; no significant differences were detected in the basal metabolic rate (BMR), uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT), or the levels of serum tri-iodothyronine (T3) and thyroxine (T4) between HF and LF mice. Although there were no differences in body fat content and serum leptin concentrations between HF and LF mice, serum leptin levels were positively correlated with body fat mass. These results support the hypothesis that A. chevrieri can compensate the poor-quality diet physiologically by way of increasing food intake and decreasing thermogenesis.

云南高山姬鼠头骨的几何形态学研究

PDF HTML阅读 XML下载 导出引用 引用提醒 云南高山姬鼠头骨的几何形态学研究 DOI: 10.5846/stxb201409011737 作者: 作者单位: 云南师范大学生命科学学院,云南师范大学生命科学学院,云南师范大学生命科学学院,云南师范大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31360096);云南省应用基础研究计划重点项目(2013FA014);获云南省博士研究生学术新人奖资助 Geometric morphometric research of the skull of Apodemus chevrieri from Yunnan Province Author: Affiliation: School of Life Sciences,Yunnan Normal University,School of Life Sciences,Yunnan Normal University,School of Life Sciences,Yunnan Normal University,Yunnan Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要: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。 Abstract:Phenotypic plasticity is the capacity of individuals to modify their phenotype in response to environmental changes. Fundamental to the way in which organisms cope with environmental variations, phenotypic plasticity is associated with all types of environmentally-induced variations, including changes to morphological, physiological, and behavioral processes. The skull morphology of mammals is the most important phenotypic trait, which changes during the evolutionary process. The Chevrier's field mouse, Apodemus chevrieri is a nocturnal and species endemic to China, and originated in the Palaearctic region. A. chevrieri is mainly distributed in the Hengduan Mountains and nearby regions of China, including Zhaotong, Kunming, Lijiang, Dali, and the land around the Lancang and Nu Rivers in Yunnan Province. A. chevrieri mainly inhabits farmland and its nearby shrubland, and is one of the main natural foci of plague in the Hengduan Mountains, which is a crossroads of species dispersal. The boreal species of the Palaearctic migrating southward, and tropical species from the Indochina Peninsula migrating northward, and thus is an area of interest for biologists studying mammal diversity. Meanwhile, the Hengduan Mountains are located in the west of the Yunnan Province, where there are many mountains and canyons. From west to east, there are dramatic changes in environmental conditions with changes in altitude, and noticeable changes were observed in the zone and non-zone landscape. In order to adapt to the different environments, animals inhabiting the area may exhibit different phenotypic variations, so A. chevrieri was employed as an ideal model for examining the relationships between phenotypic and ecological adaptations. The analysis of morphology is a fundamental part of many biological studies. With the development of more sophisticated statistical techniques, the sophistication of analyses of these types of data also increased. Since the 1980s, there was a fundamental change in the nature of the data gathered and analyzed, as scientists began to focus on the coordinates of landmarks and the geometric information relating to their relative positions. Geometric morphometrics, was hailed as a "revolution" in morphometrics. Morphological divergence among taxa was estimated quantitatively by analyzing the outline of the mandible. This method treats the mandible shape globally, and provides continuous data which can be used to compute phenotypic distances. In order to study the microevolution of species in the Yunnan province, with its special ecological environment, we applied geometric morphometric methods to the study of skull shape changes in different areas of A. chevrieri distribution, and used mitochondrial cytochrome b (Cyt b) gene and control region (D-loop) to investigate the gene type. The results showed that the Kunming and Hengduan Mountain populations (Zhongdian, Jianchuan, and Lijiang) exhibited obvious morphological and genetic variations. In particular, the dorsal and ventral of skull in A. chevrieri rarely overlap between the Hengduan Mountain populations and the Kunming population, with large variations between two populations having been noted. However, the side and lower side of the skull showed no significant variation between populations. Therefore, this study indicates that A. chevrieri in the Yunnan Province might be in the process of undergoing ecological speciation. 参考文献 相似文献 引证文献

Plasticity in the physiological energetics of Apodemus chevrieri: the role of dietary fiber content

Small mammals are usually adapted to cope with changes in food quality and availability. In order to investigate the adaptive strategy of small rodents responding to varying dietary fiber content, in the present study,Apodemus chevrieriindividuals were acclimated to a high-fiber diet for four weeks and then a relatively low-fiber diet for another four weeks. The results show that body mass was relatively stable over the course of acclimation, but dry matter intake, gross energy intake and the mass of the digestive tract increased significantly and digestibility decreased significantly in high-fiber diet mice, while the digestible energy intake was similar for both high-fiber and low-fiber diet mice except for the first week. High-fiber/low-fiber diet mice showed only a significant lower basal metabolic rate and nonshivering thermogenesis compared to low-fiber diet mice on day R1. The high-fiber diet induced a decrease in serum leptin levels and brown adipose tissue mass associated with a reduction in the cytochromecoxidase activity and uncoupling protein 1 content of brown adipose tissue. Body mass, thermogenic capacity, energy intake, serum leptin levels and digestive tract morphology returned to the control levels after 4 weeks of refeeding low-fiber diet. Further, serum leptin levels were positively related to body fat mass and negatively related to food intake. These data indicated that body mass, energy intake, serum leptin levels and organ morphological plasticity were the main strategies by whichA. chevriericopes with variations in dietary fiber content.

Phylogenetic analysis of the complete mitochondrial genome of the Korean field mouse Apodemus peninsulae (Rodentia, Murinae) from China

We sequenced and characterized a complete mitogenome (KP671850) of the Chinese Apodemus peninsulae and compared it with a previously published mitogenome of the Korean A. peninsulae (NC016060). The total length of the Chinese A. peninsulae mitogenome is 16,457 bp. The mitogenome consists of 13 protein-coding genes (PCGs), two rRNA (12S rRNA and 16S rRNA) genes, 22 tRNA genes, and one D-loop region. The most common start codon was ATG, used in the nine PCGs for initiation. The mitogenomes of Chinese and Korean A. peninsulae showed 98.9% sequence similarity. The intra-/interspecific phylogeny of the Chinese A. peninsulae revealed that the Chinese A. peninsulae was well grouped with the Korean A. peninsulae. The clade of A. peninsulae was sister to that of Apodemus agrarius, Apodemus chejuensis, and Apodemus chevrieri.

Energy requirements during lactation in female Apodemus chevrieri (Mammalia: Rodentia: Muridae) in the Hengduan Mountain region

Lactation is the most energetically demanding period in small mammals. To investigate the energy balance strategies in lactating Apodemus chevrieri, we compared body mass, energy intake, thermogenic capacity, organ mass and other morphological parameters of the digestive tract of reproductive and non-reproductive females. The results showed that at parturition, mean body mass was 23.89% higher than that of the non-reproductive group. Over the course of the lactation period (from day 0 to day 21), females decreased by 24.30% in body mass and increased by 21.46% in resting metabolic rate (RMR), then all reached the original levels at day 30. Non-shivering thermogenesis (NST) decreased significantly and reached a minimum at peak lactation (on day 21). During lactation, mean NST was 18.55% lower than that of the non-reproductive group. At the same time, lactating A. chevrieri increased their energy intake significantly. Energy intake increased after parturition and reached a maximum at day 21 of lactation (216.46 kJ/day), 2.57 times that in the non-reproductive group, and then energy intake significantly decreased and reached the original level at day 30. Liver mass, digestive tract length and weight increased significantly in the lactating group compared to the non-reproductive group. All of the results indicated that A. chevrieri increased RMR and energy intake, decreased NST and body mass and mobilised the digestive tract to match the high energy demands for lactation.

The role of photoperiod on the expression of hypothalamic genes regulating appetite in Chevrier’s field mouse (Apodemus chevrieri)

The hypothalamus and leptin play a key role in the regulation of food intake. The present study investigated the effects of 4 weeks of short- or long-photoperiod on serum leptin levels and food intake in relation to mRNA expression levels of neuropeptide Y, agouti-related protein, pro-opiomelanocortin, and cocaine- and amphetamine-regulated transcript in the hypothalamus of Chevrier’s field mouse (Apodemus chevrieri). There was a significant difference in body fat mass, food intake and neuropeptide Y mRNA expression between the two groups, but serum leptin level, agouti-related protein, pro-opiomelanocortin, and cocaine- and amphetamine-regulated transcript mRNA expression in the hypothalamus were not difference between the two groups. The elevation of neuropeptide Y mRNA regulated neuropeptides in the hypothalamus suggests a physiological role of neuroendocrine factors in food intake during the different photoperiod. We conclude that leptin may be involved in energy balance and body mass regulation.

Diet induced obesity in Apodemus chevrieri (Mammalia: Rodentia: Muridae)

To test the hypothesis that mammals that show decrease in body mass under short-day condition should be resistant to high-fat induced obesity, we traced the changes of energy balance in a wild rodent, Apodemus chevrieri, which were acclimated to either long day [16 light (L):8 dark (D), LD] or short day (8 L:16D, SD) and fed either a low-fat diet (LFD) or high-fat diet (HFD) in each photoperiodic manipulation. We found that A. chevrieri was not resistant to high-fat diet-induced obesity, and SD, not HFD, induced the elevation in basal metabolic rate (BMR), nonshivering thermogenesis (NST) and uncoupling protein-1 (UCP1) content in brown adipose tissue (BAT). HFD caused the increase in apparent digestibility and body fat mass, and the decrease in energy intake in both LD and SD A. chevrieri. The enhancement of energy absorption associated with small intestine tissue recruitment can compensate the lower energy intake, which may contribute to the high-fat diet-induced body fat deposition. Thus, a decrease in body-weight gain without resistance to high-fat induced obesity implies an evolutionary and adaptive mechanism, which is a benefit for their winter survival.

Genotyping and its epidemiological significance on Yunnan Yersinia pestis under Fse I enzyme digestion method

To create the fingerprint library of Yunnan Yersinia pestis by pulse field gel electrophoresis(PFGE)with Fse I enzyme digestion method and to study its epidemiological significance. We used rare cutting restriction enzyme Fse? to digest Yunnan Yersinia pestis strains that were isolated from foci including Rattus flavipectus Plague Focus,Apodemus chevrieri-Eothenomys miletus Plague Focus and Yulong Plague Focus. Fingerprints to Bionumerics software were used for cluster analysis. 30 tested strains were divided into 16 genotypes with the similarity value as 79.8%-100.0% . 16 genotypes wee formed into 4 clusters, with one consisted of only EV76 while the other three belonged to Rattus flavipectus,Apodemus chevrieri- Eothenomys miletus and Yulong clusters, respectively. PFGE genotypes of Yunnan Yersinia pestis accorded with its ecotypes and biovars, with clustered regional features. The strains isolated from Yulong showed an unique PFGE type, indicating a new clone group was identified.

神农架地区4种啮齿类食性及脏器形态差异比较

PDF HTML阅读 XML下载 导出引用 引用提醒 神农架地区4种啮齿类食性及脏器形态差异比较 DOI: 10.5846/stxb201211091570 作者: 作者单位: 中国科学院植物研究所植被与环境变化国家重点实验室,中国科学院植物研究所植被与环境变化国家重点实验室,湖北神农架林区林业科学研究所,中国科学院植物研究所植被与环境变化国家重点实验室,三峡大学化学与生命科学学院,中国科学院植物研究所植被与环境变化国家重点实验室,湖北省宜昌市五峰县林业局,中国科学院植物研究所植被与环境变化国家重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金面上项目（No.30970474）；中国科学院战略性先导科技专项（XDA05050302） Variations in food habit and viscera organ morphology of four rodents in Shennongjia, central China Author: Affiliation: State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chinese Academy of Sciences,State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chinese Academy of Sciences,Shennongjia Institute of Forestry, Shennongjia Forestry Region,,College of Chemistry and Life Science, China Three Gorges University,State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences,Wufeng Forestry Bureau,State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要: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。 Abstract:The separation of ecological niches in terms of food resource, activity pattern or space contributes to the coexistence of sympatric species. Spatiotemporal variations in resource availability affect foraging behavior, habitat selection and even the existence of species. To explore the coexistence mechanisms of sympatric rodents, variations in food habit, viscera organ and digestive tract morphology among different rodent species were investigated in Shennongjia, central China.Studied rodents were trapped by snap-trap in October 2010. Upon capture, all rodents were carried to laboratory. The species, gender, age, reproductive status, body mass and length were recorded. Then the heart, lung, liver, spleen, kidney and the entire digestive tract were removed from the body and the carcass mass was weighted. The connective tissue and lipid was stripped and the digestive tract was extended to its full length. Fresh weights of all organs and lengths of digestive tract were weighted. After removing digestive tract contents, fresh weights without contents and food items in the stomach were recorded. Dry weights of all organs were measured after drying in the oven.A total of 220 adult rodents, including 8 Niviventer andersonii, 167 N. confucianus, 5 Apodemus chevrieri, and 35 A. draco, 2 Leopoldamys edwardsi and 3 Typhlomys cinereus, were collected for analysis. L. edwardsi and T. cinereus were excluded for statistical tests due to insufficient samples. The analysis of food habit showed that N. andersoni, N. confucianus, A. chevrieri and A. draco were omnivorous but the Chi-square test detected significant variation in dietary biases. N. andersoni was primarily phyllophagous and seminivorous and the others were primarily seminivorous and carnivorous. The analysis of covariance of viscera organs showed that while fresh weights of heart, lung and spleen and dry weight of spleen did not differ between rodents, other indices did exhibit significant variation with the highest value found in N. andersoni. In the analysis of digestive tract morphology, while length, fresh and dry weight of caecum did not differ between rodents, fresh and dry weights of stomach and large intestine, fresh weights including stomach, caecum and large intestine contents, and length of large intestine did differ significantly with the highest value found in N. andersoni. Otherwise, the length, fresh and dry weight of small intestine, and fresh weight including small intestine contents also showed significant variations between species, with the highest value found in N. confucianus.Variations in viscera organ morphology of N. andersoni compared to other species indicate that the segregation of food resources contributes to this species coexistence with other rodents. In order to adapt to different availability of food resources, the viscera organ and digestive tract morphology of N. andersoni show adaptable phenotypic plasticity. However, A. chevrieri and A. draco, both belonging to the genus Apodemus, do not exhibit differences in food habit, viscera organ and digestive tract morphology, which implied that their coexistence may result from other strategies than resource allocation, such as habitat selection. 参考文献 相似文献 引证文献

云南呈贡和剑川地区高山姬鼠消化道形态的比较

为探讨不同地区的高山姬鼠(Apodemus chevrieri)消化道形态是否存在差异，本研究于2012年6月分别对捕自云南剑川和呈贡地区高山姬鼠的体重、消化道(胃、小肠、大肠和盲肠)的长度以及含内容物重、去内容物重进行了测量。结果显示：剑川地区高山姬鼠的小肠和盲肠去内容物重以及长度均显著大于呈贡地区；体重、胃和盲肠含内容物重以及盲肠长均显著小于呈贡地区。结果表明：剑川地区的高山姬鼠具有较小的体重以减少对能量的绝对需求来应对该地较低的气温和食物资源短缺，暗示消化道形态的大小和消化能力的调整在自然环境高山姬鼠消化对策中起着重要的作用。In order to investigate whether there are differences on digestive tract morphology in A. chevrieri from different areas, we measured weight and lengths of total digestive tract morphology including stomach, small intestine, large intestine and cecum of A. chevrieri from Jianchuan and Chenggong. The results showed that the length and weight without contents of the small intestine and cecum in A. chevrieri at Jianchuan were significantly greater than that of Chenggong; body mass, the stomach, the weight with content of stomach and cecal and lengths of cecum at Jianchuan were significantly less than that of Chenggong. The results indicated that A. chevrieri at Jianchuan might adjust the body mass and weight of digestive tract to maintain the normal physiological function in stressed condition, such as at cold environment and lack of food. This suggests that the adjustments in capacity and size of the gastrointestinal tract play an important role in their digestive strategies of A. chevrieri in natural environment.

Effects of long-term forced exercise training on body mass, energy metabolism and serum leptin levels in Apodemus chevrieri (Mammalia: Rodentia: Muridae)

Mammals, including rodents, are able to maintain a stable body mass, which is a result of balance between energy intake and energy expenditure. Exercise training can increase energy expenditure and is considered one of the most important factors affecting energy balance in mammals. In order to understand the effect of exercise on body mass regulation and energy metabolism, changes of body mass, metabolic rate, energy intake, serum leptin levels and body composition were measured in Apodemus chevrieri during an 8-week forced exercise training with a treadmill. The results showed that exercise training had no significant effects on body mass, but the metabolic rate and energy intake were increased during the 8-week exercise training. Body fat mass and serum leptin levels decreased in the exercise group compared to the control group. There was a positive relationship between serum leptin levels and body fat mass in the control group, but no relationship in the exercise group. Mass of liver and digestive tracts increased significantly, while wet carcass mass and water of carcass decreased significantly in the exercise group compared to the control group. The results indicated that A. chevrieri mobilized body fat mass, and increased the metabolic rate and energy intake to regulate the body mass and energy balance during long-term forced exercise training. Serum leptin levels would be potentially involved in the body mass regulation and thermogenesis during the long-term forced exercise training.

Effects of food restriction on body mass, thermogenesis and serum leptin level in Apodemus chevrieri (Mammalia: Rodentia: Muridae)

To investigate the effect of food restriction on the body mass, thermogenesis and serum leptin level in Apodemus chevrieri, the changes of body mass, body fat mass, resting metabolic rate (RMR), mitochondrial cytochrome coxidase (COX) activity both in liver and brown adipose tissue (BAT), uncoupling protein1 (UCP1) content of BAT, and serum leptin level were measured. The results showed that food restriction induced significant reductions in body mass and body fat mass. RMR decreased significantly in response to food restriction, and food restriction induced significant reduction in total mitochondrial protein content, COX activity both in liver and BAT, and UCP1 content in BAT. Food restriction also induced a reduction in serum leptin level. In contrast, length and mass with content in the small intestine in the food-restricted group was significantly higher relative to the control group. It suggests that the physiological regulations in energy metabolism to adaptively cope with a period of food shortage include decreasing body mass, reductions in the energy spent for RMR and thermogenesis, as well as the mobilization of fat storage. Leptin may play a potential role in physiological regulations in thermogenesis in response to food restriction.

The thermogenic and metabolic responses to photoperiod manipulations in Apodemus chevrieri

Environmental cues play important roles in the regulation of an animal’s physiology and behavior. In the present study, we examined the effects of short photoperiod on body weight as well as on several physiological, hormonal, and biochemical measures indicative of thermogenic capacity to test our hypothesis that short photoperiod stimulates increases in thermogenesis without cold stress in Apodemus chevrieri. A. chevrieri were randomly assigned to either a long or short photoperiod for 4 weeks at constant temperature. The short photoperiod group of A. chevrieri showed increases in resting metabolic rate and nonshivering thermogenesis during the 4-week photoperiod acclimation. At the end, A. chevrieri at short photoperiod had lower body weights, higher levels of mitochondrial protein content and cytochrome C oxidase activity in liver and brown adipose tissues, and had higher levels of mitochondrial uncoupling protein-1 contents in brown adipose tissues. No difference in serum leptin levels were found between short and long photoperiod groups, but serum leptin levels were positively correlated with body mass and body fat mass, and negatively correlated with energy intake and uncoupling protein-1 content in brown adipose tissues, respectively. All results suggest that the short photoperiod may induce an increased thermogenesis capacity in A. chevrieri and that leptin is potentially involved in the photoperiod induced body mass regulation and thermogenesis in A. chevrieri.

光周期和高脂食物对雌性高山姬鼠能量代谢和产热的影响

Environmental factors play an important role in the seasonal adaptation of body mass,energy intake and thermogenesis in small mammals. The Hengduan Mountains region is at the boundary between the Palaearctic region and the Oriental region. It is alpine with high mountains and gorges; the diversity and abundance of mammals is high and it is considered to be "the harbor in fourth ice age". Therefore small mammals may differ from those from other regions.Apodemus is the most common rodent to inhabit the broadleaf forests in the Temperate Zone of the Palaearctic region; in China Apodemus chevrieri is distributed in the Hengduan mountains region,and on vales,it is the host of rat epidemic disease in the Hengduan mountains region. Evaporative water loss and energy metabolism in A. chevrieri were reported in2008. The effect of cold acclimation on energy metabolism and body mass regulation in A. chevrieri was also studied in2011,A. chevrieri decreased body mass and increased thermogenesis and energy intake. Nowadays,to investigate the roles of photoperiod and high fat diet in the regulation of energy budget and thermogenesis in small mammals in the Hengduan mountains region,32 adult female A. chevrieri were acclimatized to one of 4 regimens,1) long day and low fat diet,LL; 2)long day and high fat diet,LH; 3) short day and low fat diet,SL; 4) short day and high fat diet,SH. The animals in any groups were housed individually throughout the experiment. After a 7-week acclimation period,we determined body mass( Body mass was measured before the experiment and every 3 days throughout the acclimation of 7 weeks),energy budget( Dry matter intake,DMI; Gross energy intake,GEI; Digestive energy intake,DEI; Digestibility),basal metabolic rate( BMR),nonshivering thermogenesis( NST),body composition( Heart,Liver,Spleen,Lung,Kidneys,Wet carcass mass,Dry carcass mass,Body fat,Brown adipose tissue and so on),serum leptin level and body fat content. The results showed that short days induced decreases in body mass,wet and dry carcass mass,wet lung mass and serum leptin level,and increases in wet spleem mass and nonshivering thermogenesis. There were no significant effects of diets varying in body mass,basal metabolic rate,nonshivering thermogenesis and serum leptin level. However,high-fat diet significantly reduced dry matter intake,gross energy intake,digestive energy intake and elevated apparent digestibility and body fat content.Serum leptin level were positively correlated with body fat mass,however,not with energy intake. Our results suggest that A. chevrieri resist high-fat diet induced obesity,which might be mediated by the increased sensitivity of leptin and enhanced thermogenesis during short photoperiods. A. chevrieri in the field,can prevent excessive obesity by adaptive regulation of energy metabolism and thermogenesis.

Effects of Fat and Protein Levels on Foraging Preferences of Tannin in Scatter-Hoarding Rodents

Both as consumers and dispersers of seeds, scatter-hoarding rodents often play an important role in the reproductive ecology of many plant species. However, the seeds of many plant species contain tannins, which are a diverse group of water-soluble phenolic compounds that have a high affinity for proteins. The amount of tannins in seeds is expected to affect rodent foraging preferences because of their major impact on rodent physiology and survival. However, variable results have been obtained in studies that evaluated the effects of tannin on rodent foraging behavior. Hence, in this study, we aimed to explain these inconsistent results and proposed that a combination of seed traits might be important in rodent foraging behavior, because it is difficult to distinguish between the effects of individual traits on rodent foraging behavior and the interactions among them. By using a novel artificial seed system, we manipulated seed tannin and fat/protein levels to examine directly the univariate effects of each component on the seed preferences of free-ranging forest rats (Apodemus latronum and Apodemus chevrieri) during the behavioral process of scatter hoarding. Our results showed that both tannin and fat/protein had significant effects on rodent foraging behavior. Although only a few interactive effects of tannin and fat/protein were recorded, higher concentrations of both fat and protein could attenuate the exclusion of seeds with higher tannin concentrations by rodents, thus influencing seed fate. Furthermore, aside from the concentrations of tannin, fat, and protein, numerous other traits of plant seeds may also influence rodent foraging behavior. We suggest that by clarifying rodent foraging preferences, a better understanding of the evolution of plant seed traits may be obtained because of their strong potential for selective pressure.

Seasonal variations of body mass, thermogenesis and digestive tract morphology in Apodemus chevrieri in Hengduan mountain region

Seasonal changes in an animal’s morphology, physiology, and behavior are considered to be an adaptive strategy for survival and reproductive success. We hypothesize thatApodemus chevrieriwill change their thermogenesis seasonally and serum leptin will change with body mass or body fat mass. Seasonal variations in body mass (BM), basal metabolic rate (BMR), nonshivering thermogenesis (NST), digestive tract morphology, serum leptin and uncoupling protein 1 (UCP1) were measured in wild-trappedA. chevrieriin Hengduan mountain region. The results showed that the body weight ofA. chevrieriwas lowest in winter and highest in summer. Decreased BM in the winter was accompanied by increased energy intake and enhanced NST and UCP1 as well as by decreased body fat mass, adjusted digestive tract morphology and reduced levels of circulating leptin. Further, serum leptin were positively correlated with body weight and body fat mass, and negatively correlated with energy intake and UCP1 contents. These data suggest that wildA. chevrierido not depend on a decrease in BM, but instead increase their thermogenic capacity to cope with cold stress. Leptin may be involved in the seasonal regulation in energy balance and thermogenesis in fieldA. chevrieri.

A Mitogenome of the Chevrier's Field Mouse (Apodemus Chevrieri) and Genetic Variations Inferred from the CytochromebGene

The Chevrier's field mouse (Apodemus chevrieri) is an endemic species to China and is an important pest in agriculture and human diseases. In this study, the complete mitochondrial genome of this species was sequenced and its size was 16,298 bases (accession no.: HQ896683). The mitogenome structure was similar compared with other reported rodent mitochondrial genomes and includes 13 protein-coding genes, 2 rRNA genes (12S rRNA and 16S rRNA), 22 tRNA genes, and 1 control region. This was the first complete mitogenome sequenced in genus Apodemus. The phylogenetic analyses based on the sequences of 12 heavy-strand protein-coding genes demonstrated that A. chevrieri clustered together with genus Mus. Additionally, extremely high haplotype and nucleotide diversities (h=0.978, π=2.6%) were observed based on 44 mitochondrial cytochrome b (cyt b) gene sequences. This suggests adaptive divergence of this species to a variety of living habitats and potential refuges in the eastern margin of the Hengduan Mountains during the Quaternary ice ages. No population expansions or genetic bottlenecks were observed in demographic analyses. The phylogenetic analysis of cyt b sequences and haplotypes revealed a genetic differentiation between north and south populations. The divergence between north clade and south clade occurred probably in the middle Pleistocene 1.1815 million years ago (Mya) (95% highest posterior density 2.3189-0.2737 Mya), which was congruent with the periods of the most tense uplift events in the Tibetan Plateau.

Thermogenesis, energy intake and serum leptin in Apodemus chevrieri in Hengduan Mountains region during cold acclimation

Environmental factors play an important role in the seasonal adaptation of body mass and thermogenesis in small, wild mammals. The purpose of the present study was to test the hypothesis that ambient temperature was a cue to trigger the adjustments in body mass, energy intake, and serum leptin level in Apodemus chevrieri during 42 days of cold exposure. Our data demonstrated that cold acclimation induced a decrease in body mass and a significant increase in energy intake in A. chevrieri. Serum leptin levels were positively correlated with body mass and fat mass. These data suggest that A. chevrieri reduced the body mass and increased energy intake and thermogenic capacity under cold acclimation. Further, serum leptin appears to be involved in the energy intake regulation and thermoregulation.

Evaporative water loss and energy metabolic in two small mammals, voles ( Eothenomys miletus) and mice ( Apodemus chevrieri), in Hengduan mountains region

Evaporative water loss (EWL) and energy metabolism were measured at different temperatures in Eothenomys miletus and Apodemus chevrieri in dry air. The thermal neutral zone (TNZ) of E. miletus was 22.5–30 °C and that of A. chevrieri was 20–27.5 °C. Mean body temperatures of the two species were 35.75±0.5 and 36.54±0.61 °C. Basal metabolic rates (BMR) were 1.92±0.17 and 2.7±0.5 ml O 2/g h, respectively. Average minimum thermal conductance ( C m) were 0.23±0.08 and 0.25±0.06 ml O 2/g h °C. EWL in E. miletus and A. chevrieri increased with the increase in temperature; the maximal EWL at 35 °C was 4.78±0.6 mg H 2O/g h in E. miletus, and 5.92±0.43 mg H 2O/g h in A. chevrieri. Percentage of evaporative heat loss to total heat production (EHL/HP) increased with the increase in temperature; the maximal EHL/HP was 22.45% at 30 °C in E. miletus, and in A. chevrieri it was 19.96% at 27.5 °C. The results may reflect features of small rodents in the Hengduan mountains region: both E. miletus and A. chevrieri have high levels of BMR and high levels of total thermal conductance, compared with the predicted values based on their body masses, while their body temperatures are relatively low. EWL plays an important role in temperature regulation.