几种啮齿类动物高血脂实验动物模型的建立方法

高脂血症为终身疾病,在人群中其发病率逐年增高,目前没有根治方法.长期高血脂,可引起机体代谢紊乱,产生进行性动脉硬化,进而导致心、脑、肾等重要脏器受到损害,严重危害健康,危及生命.探讨高脂血症的预防和治疗,开发降血脂保健品和药物,是目前国内外的研究热点之一,因此,选择一个理想的高血脂动物模型是研究血脂代谢及其影响因素的关键.目前,动物实验中用啮齿类动物进行高血脂动物模型造模较为常见,造模的方法也较多,本文拟对几种啮齿类动物高血脂模型的造模方法作一综述.

二甲双胍在豚鼠卵母细胞体外成熟中的作用研究

探究二甲双胍对豚鼠卵母细胞体外成熟和发育的影响。方法 12只二月龄性成熟雌性豚鼠(Hartley)、12只幼龄豚鼠分别随机均分为四组:对照组、二甲双胍组、超排组(HMG 组)、给药和超排联用组(二甲双胍+HMG组),连续16天二甲双胍生理盐水溶液(30mg/ml)300mg/kg单次灌胃给药,连续3天皮下注射HMG(15IU/kg)进行超排,对照组等量生理盐水每日单次灌胃给药,取卵巢和输卵管,计数豚鼠排卵数、体外成熟率、体外受精率、卵裂率和囊胚率。结果 ①幼龄豚鼠经过二甲双胍、HMG超排和二甲双胍与HMG超排联合处理后,GV期卵母细胞数和成熟卵母细胞占比均显著高于对照组(p<0.05),其中二甲双胍与HMG联用效果最好,而性成熟豚鼠二者无显著差异。②经过二甲双胍处理后,体外受精的幼龄豚鼠卵母细胞,2-细胞卵裂率显著高于对照组(p<0.05)。结论 二甲双胍可以提高豚鼠的排卵数、体外成熟率和卵裂率。

Influence of roads on small rodents population in fragmented forest areas, South Korea

The road effect on small rodent population is investigated at 8 fragmented forest areas in the Baekdudaegan mountain range, South Korea in September 2001. We especially focused on the distribution and body condition of small rodents near the roads. Korean field mouse (Apodemus peninsulae) seems to be more sensitive to the existence of a road than striped field mouse (Apodemus agrarius). Korean field mouse prefers interior forest area to around road. Striped field mouse is a habitat generalist and has wide distributional range around road, but Korean field mouse is forest-inhabiting species and their distribution is limited in forest area. These results suggest the effect of road is different on each small rodent species and their habitat preferences.

Morphological,kinetic,membrane biochemical and genetic aspects of intestinal enteroplasticity

The process of intestinal adaptation("enteroplasticity") is complex and multifaceted.Although a number of trophic nutrients and non-nutritive factors have been identified in animal studies,successful,reproducible clinical trials in humans are awaited.Understanding mechanisms underlying this adaptive process may direct research toward strategies that maximize intestinal function and impart a true clinical benefit to patients with short bowel syndrome,or to persons in whom nutrient absorption needs to be maximized.In this review,we consider the morphological,kinetic and membrane biochemical aspects of enteroplasticity,focus on the importance of nutritional factors,provide an overview of the many hormones that may alter the adaptive process,and consider some of the possible molecular profiles.While most of the data is derived from rodent studies,wherever possible,the results of human studies of intestinal enteroplasticity are provided.

Aging gracefully: social engagement joins exercise and enrichment as a key lifestyle factor in resistance to age-related cognitive decline

Cognitive impairment is a consequence of the normal aging process that effects many species, including humans and rodent models. Decline in hippocampal memory function is especially prominent with age and often reduces quality of life. As the aging population expands, the need for interventional strategies to prevent cognitive decline has become more pressing. Fortunately, several major lifestyle factors have proven effective at combating hippocampal aging, the most well-known of which are environmental enrichment and exercise. While the evidence supporting the beneficial nature of these factors is substantial, a less well-understood factor may also contribute to healthy cognitive aging: social engagement. We review the evidence supporting the role of social engagement in preserving hippocampal function in old age. In elderly humans, high levels of social engagement correlate with better hippocampal function, yet there is a dearth of work to indicate a causative role. Existing rodent literature is also limited but has begun to provide causative evidence and establish candidate mechanisms. Summed together, while many unanswered questions remain, it is clear that social engagement is a viable lifestyle factor for preserving cognitive function in old age. Social integration across the lifespan warrants more investigation and more appreciation when designing living circumstances for the elderly.

Behavioral interactions between a coexisting rodent Micaelamys namaquensis and macroscelid Elephantulus myurus

A number of mechanisms are known to influence coexistence in small mammal communities. However, the role ofbehavioral interactions in promoting species coexistence is under-represented in the literature. We studied the behavioral interactionsof two coexisting small mammals, the Namaqua rock mouse Micaelamys namaquensis (Rodentia) and the Rock sengi Elephantulusmyurus (Macroscelidae), which have high dietary and microhabitat overlap. Using wild-caught individuals, intra- andinterspecific dyadic encounters were staged in tanks on a neutral rocky outcrop. Interspecific dyads displayed significantly moreactive avoidance behavior. There was no support for the prediction that the larger, more specialist species, E. myurus, is behaviorallydominant over M. namaquensis. Intraspecific encounters of E. myurus showed significantly more passive avoidance andamicable behavior, whereas the behavior of M. namaquensis did not differ between intra- and inter-specific encounters, both ofwhich were characterized by low levels of aggression and amicability. Thus, due to the lack of aggression, direct competition appearsweak and instead mutual avoidance may reduce or minimize interspecific interactions, potentially promoting coexistence.

Juvenile ferric iron prevents microbiota dysbiosis and colitis in adult rodents

AIM: To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice. METHODS: Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe2+) iron salt or ferric (Fe3+) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated usingquantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria. RESULTS: Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg proteinvs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po - 6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po - 6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood.CONCLUSION: Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.

Effects of Forest Roads on Habitat Pattern for Sables in Da Hinggan Mountains, Northeasten China

The anthropogenic managements of forest have created a network of roads resulting in the loss and alternation of habitat. To better understand road′s impact on animal habitats, we assessed the habitat pattern of sables(Martes zibellina), one of rodents within national first-class protected species, when roads are considered in Huzhong area in Da Hinggan Mountains, northeastern China. Employing published literatures about behavior ecology, aerial photographs and forest stand maps, we classified the study area into three habitat types including best-suitable, suitable and unsuitable habitats based on sable habitat requirements at the landscape scale including four variables derived from forest source map with attribute database. Results indicated the loss and significant fragmentation of best-suitable habitat and home range habitat when roads, especially 150 m avoidance distance of roads, were considered. The roads reduced and fragmented highly suitable habitats more significantly during earlier development period than the later development period. Additionally, the suitable area percentage increased with increasing distance to roads. This study helped to identify the suitable area for sables and location of sable population. Also, this study suggested the passage construction and road management involving road closure and removal will reduce the fragmentation functionally and benefit the sable population.

Seed caching and cache pilferage by three rodent species in a temperate forest in the Xiaoxinganling Mountains

Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence, differentiation in cache pilfering abilities among sympatric rodents with different hoarding strategies is seldom addressed. We carried out semi-natural enclosure experiments to investigate seed hoarding tactics among three sympatric rodent species (Tamias sibiricus, Apodemus peninsulae and Clethrionomys rufocanus) and the relationship of their pilfering abilities at the inter- and intraspecific levels. Our results showed that T. sibiricus exhibited a relatively stronger pilfering ability than A. peninsulae and C. rufocanus, as indicated by its higher recovery rate of artificial caches. Meanwhile A. peninsulae showed a medium pilfering ability and C. rufocanus displayed the lowest ability. We also noted that both cache size and cache depth significantly affected cache recovery in all three species. T. sibiricus scatter-hoarded more seeds than it larder-hoarded, A. peninsulae larder-hoarded more than scatter-hoarded, and C. rufocanus acted as a pure larder-hoarder. In T. sibiricus, individuals with lower pilfering abilities tended to scatter hoard seeds, indicating an intraspecific variation in hoarding propensity. Collectively, these results indicated that sympatric rodent species seem to deploy different food hoarding tactics that allow their coexistence in the temperate forests, suggesting a strong connection between hoarding strategy and pilfering ability.

Practical Applications with Geosynthetic Mats Reinforced with Steel Wire Meshes to Prevent Embankment Damage by Burrowing Large Rodents and Beavers

Recent studies show an increase in the population of beavers, nutria and other rodents in vast regions of central Europe over the last 15 years. Unfortunately, this caused in many instances considerable damage on large rivers along dykes and earthworks in the floodplain areas, leading to an increased risk of bank failures. However, most of these mammals belong to protected species. This work is aimed at showing positive experience in cooperation with universities, research institutes and environmental agencies regarding measures to permanently safeguard the banks using composite erosion control systems with polymer coated steel wire net （as flexible reinforcement component） and a geosynthetic （to promote vegetation growth）. The steel mesh component works as an effective long-term barrier against the intrusion of mammals, discouraging them from digging inside the core of the dyke. An analysis of the sensitive areas to be protected led also to definition of the characteristics of these interventions （length, shape, escape ways, population areas, etc.）. The study will present several additional benefits when using polymer steel nets along dykes, such as： high and durable erosion protection in overflow areas, promotion of fast and effective vegetation growth （increasing stability）, surface protection against ice impacts （in northern regions）, ease of installation, maintenance, ability to conform to irregular shapes of the slope. This work will also present the positive outcome of research studies along dykes in Germany, Austria and in Italy.

Caffeine Intake during Pregnancy： What Are the Real Evidences？

Caffeine is a substance presented in foods such as coffee, tea, soft drinks, chocolates and medicines and is commonly consumed by pregnant women. Due to its ability to cross the placental membrane and accumulate in the fetus body, caffeine and its metabolites have been contraindicated or recommended in small doses during pregnancy. Studies in rodents relate caffeine intake to lower rates of fertilization, embryonic implantation, changes in placental structure, increased occurrence of low fetal and placental weights, abortion and stillbirth. However, in humans, studies involving caffeine consumption are inconclusive. Methodological complexity, difficulty for measuring caffeine intake and ethical reasons are limiting factors for a more accurate conclusion. So far, caffeine recommendation ranges from 100 to 300 mg/day. Even though researches have recommended low caffeine consumption by pregnant women in order to avoid deleterious consequences during gestation, a safe dose has not been established until now. The aim of the present review is to describe the main findings on the effects of caffeine consumption during pregnancy in both human and rodent experimental models.

Reproductive toxicity assessment of benzo[a]pyrene in the marine polychaete Perinereis nuntia

Benzo[a]pyrene （B[a]P） is an increasingly present marine environmental pollutant, yet our understanding of the long-term consequences of reproductive toxicity in marine benthic polychaetes remains limited. To test the reproductive toxicity of B[a]P on polychaetes, Perinereis nuntia was exposed to B[a]P-contaminated artificial seawater and sexual maturation, the sex ratio, number of eggs spawned, fertilization and hatching rated, as well as vitellogenin （VTG） mRNA expression levels were analyzed. A low concentration of B[a]P （2.5 gg/L） had no effects on the rate of sexual maturation, spawning, or fertilization but significantly increased the sex ratio （female： male） from 1.6±0.15：1 to 2.3±0.18：1, inhibited hatching rate by 27%, and significantly increased VTG mRNA expression level by 3.7-fold following a 60-day exposure, compared with those in the solvent controls. A higher concentration of B[a]P （25 μg/L） caused more serious effects; sexual maturation, fertilization success, and hatching decreased by 31%, 17% and 46%, respectively, and the sex ratio （female： male） and VTG mRNA gene expression level increased by 54% and 7.1-fold, respectively. These results demonstrate that sublethal concentrations of B[a]P negatively affect reproductive performance of the sandworm P. nuntia.

Isolation,Characterization,and Phylogenetic Analysis of Two New Crimean-Congo Hemorrhagic Fever Virus Strains from the Northern Region of Xinjiang Province,China

Crimean-Congo hemorrhagic fever(CCHF)caused by the CCHF virus(CCHFV)is a tick-borne natural focal disease with a mortality rate of approximately 50%.CCHFV is widely prevalent in Africa,southern Asia,the Middle East,and southeast Europe.CCHF outbreaks have been reported previously in Xinjiang province,China,especially in its southern region.Epidemiological surveys conducted on ticks and animals have revealed the presence of CCHFV strains in ticks,rodents,and infected individuals from cities and counties in southern Xinjiang.Phylogenetic analyses revealed that the Chinese CCHFV strains belong to one genotype,based on complete sequences of the S segments of its negative-stranded RNA genome.The present study reports two new CCHFV strains isolated from Hyalomma asiaticum asiaticum ticks collected from Fukang City and Wujiaqu City in the northern region of Xinjiang.Viral characteristics and their evolutionary relationships were analyzed through metagenomic and reverse-transcription PCR analyses;these analyses indicated that the genotype of both strains was different from that of other Chinese strains.Furthermore,previous reports of CCHFV in Xinjiang were reviewed and phylogenetic analyses were performed.CCHFV was found to prevail in Fukang City in Junggar Basin for more than 20 years,and that Fukang City and Wujiaqu City are considered natural reservoirs of different genotypes of CCHFV strains.Our findings facilitate the understanding of CCHFV distribution in Xinjiang province and provide insights into the evolutionary relationships among Chinese CCHFV strains.

Chevrier＇s Field Mouse(Apodemus chevrieri) and Père David＇s Vole(Eothenomys melanogaster) in China Carry Orthohepeviruses that form Two Putative Novel Genotypes Within the Species Orthohepevirus C

Hepatitis E virus(HEV)is the prototype of the family Hepeviridae and the causative agent of common acute viral hepatitis.Genetically diverse HEV-related viruses have been detected in a variety of mammals and some of them may have zoonotic potential.In this study,we tested 278 specimens collected from seven wild small mammal species in Yunnan province,China,for the presence and prevalence of orthohepevirus by broad-spectrum reverse transcription(RT)-PCR.HEV-related sequences were detected in two rodent species,including Chevrier’s field mouse(Apodemus chevrieri,family Muridae)and Père David’s vole(Eothenomys melanogaster,family Cricetidae),with the infection rates of 29.20%(59/202)and 7.27%(4/55),respectively.Further four representative full-length genomes were generated:two each from Chevrier’s field mouse(named Rd HEVAc14 and Rd HEVAc86)and Père David’s vole(Rd HEVEm40 and Rd HEVEm67).Phylogenetic analyses and pairwise distance comparisons of whole genome sequences and amino acid sequences of the gene coding regions showed that orthohepeviruses identified in Chinese Chevrier’s field mouse and Père David’s vole belonged to the species Orthohepevirus C but were highly divergent from the two assigned genotypes:HEV-C1 derived from rat and shrew,and HEV-C2 derived from ferret and possibly mink.Quantitative real-time RT-PCR demonstrated that these newly discovered orthohepeviruses had hepatic tropism.In summary,our work discovered two putative novel genotypes orthohepeviruses preliminarily named HEVC3 and HEV-C4 within the species Orthohepevirus C,which expands our understanding of orthohepevirus infection in the order Rodentia and gives new insights into the origin,evolution,and host range of orthohepevirus.

Nanpoping fauna of the Lanzhou Basin and its environmental significance

The Asian monsoon-arid environment system began to develop during the Oligocene, but the exact position of the arid zone boundary is uncertain in the Oligocene. Fossil mammal assemblages can be used to assess the environment of an area. There were two sizes of mammals in the Nanpoping fauna from the Oligocene strata of the Lanzhou Basin： the small ones were grassland rodents such as Ctenodactylidae; the large ones were forest dwellers such as Paraceratherium and Paraentelodon. Of the 23 species of mammals identified in the Nanpoping fauna, -40% were forest dwellers and the rest （-60%） were grassland taxa. The Nanpoping fauna was compared with the contemporaneous Dingdanggou fauna in the Danghe area to the north and Jiaozigou fauna in the Linxia area to the south. The Nanpoping fauna contains elements of both other faunas and thus represents a transitional assemblage between forest and grassland. So, it can be inferred that the southern boundary of the arid zone in China during the Oligocene was probably near the Lanzhou Basin.

Differences in hoarding behavior between captive and wild sympatric rodent species

In hand reared birds and mammals, it is generally considered that the development of hoarding behavior is the result of an interaction between the development and maturation of the nervous system and learning from individual experience. How- ever, few studies have been done on wild animals. We tested differences in hoarding behavior between captive reared and wild individuals of two sympatric small rodents, Korean field mice Apodemus peninsulae and Chinese white-bellied rats Niviventer confucianus. Our aim was to identify if lack of experience from the wild would result in poorly developed hoarding behavior. The Korean field mice perform scatter- and larder-hoarding behaviors whereas Chinese white-bellied rats hoard food in larders only. Within outdoor enclosures we compared seed-hoarding behavior in reared juveniles （RJ, 40-50 d old, pregnant mothers were captured in the wild）, wild juveniles （WJ, as young as the RJ） and wild adults （WA, over-winter animals）. We found that a lack of experience from the wild had significant effects on seed-hoarding behavior for both species. The RJ-group removed and hoarded fewer seeds than the WJ- and WA-groups. The two latter groups hoarded seeds in a similar way. In the Korean filed mouse the ILl-group placed more seeds on the ground surface than other groups. These findings suggest that wild experience is important for the acquisition of an appropriate food-hoarding behavior （especially for scatter-hoarding） in these species

Does urbanization influence the diet of a large snake？

Urbanization facilitates synanthropic species such as rodents, which benefit the diets of many predators in cities. We investigated how urbanization affects the feeding ecology of dugites Pseudonaja affi- nis, a common elapid snake in south-west Western Australia. We predicted that urban snakes： 1） more frequently contain prey and eat larger meals, 2） eat proportionally more non-native prey, 3） eat a lower diversity of prey species, and 4） are relatively heavier, than non-urban dugites. We analyzed the diet of 453 specimens obtained from the Western Australian Museum and opportunistic road-kill collections. Correcting for size, sex, season, and temporal biases, we tested whether location influenced diet for our 4 predictions. Body size was a strong predictor of diet （larger snakes had larger prey present, a greater number of prey items, and a greater diversity of prey）. We identified potential collection biases： urban dugites were relatively smaller （snout-vent length） than non-urban specimens, and females were relatively lighter than males. Accounting for these effects, urban snakes were less likely to have prey present in their stomachs and were relatively lighter than non-urban snakes. Other urban-adapted carnivores appear to benefit from urbanization through increased food supplementation, but we found the opposite of this： urban dugites were less likely to contain a meal, and their meals were smaller, indicating they did not make greater use of synanthropic species than was evident for non-urban snakes. In contrast to other carnivores, snakes do not appear to fit a consistent directional pattern for size differences between urban and non-urban populations.

Hemorrhagic fever with renal syndrome in China： Mechanisms on two distinct annual peaks and control measures

Hemorrhagic fever with renal syndrome （HFRS） is a rodent-borne disease caused by several serotypes of hantavirus and 90% of all reported HFRS cases occur in China. However, the dynamics of such outbreak, particularly the characteristics of two distinct annual peaks in China, are not well understood. Here, we investigate several of the biologically plausible causes for the peaks in monthly HFRS cases, and find that the key factor is the interplay between periodic transmission rates and rodent periodic birth rate. Analysis of dynamicM model reveals that vaccination plays a significant role in the control of HFRS in China. Sensitive analysis of different interventions demonstrates that integrating rodent culling and environmental management with the current vaccination program is effective for HFRS control. Our results suggest that for diseases from animals to human beings, the features of both animals and humans beings should be taken into account in the control and prevention strategies.

Breeding bird density does not drive vocal individuality

Many species produce individually specific vocalizations and sociality is a hypothesized driver of such individuality. Previous studies of how social variation influenced individuality focused on colonial or non-colonial avian species, and how so- cial group size influenced individuality in sciurid rodents. Since sociality is an important driver of individuality, we expected that bird species that defend nesting territories in higher density neighborhoods should have more individually-distinctive calls than those that defend nesting territories in lower-density neighborhoods. We used Beecher＇s information statistic to quantify individu- ality, and we examined the relationship between bird density （calculated with point-counts） and vocal individuality on seven spe- cies of passerines. We found non-significant relationships between breeding bird density and vocal individuality whether regres- sions were fitted on species values, or on phylogenetically-independent contrast values. From these results, we infer that while in- dividuality may be explained by social factors, breeding bird density is unlikely to be generally important in driving the evolution of individually-specific vocalizations [Current Zoology 58 （5）： 765-772, 2012].

Determinants of uterine aging:lessons from rodent models

The uterus is an indispensable organ for the development of a new life in eutherian mammals.The female mammalian reproductive capacity diminishes with age.In this respect,the senescence of uterine endometrium is convinced to contribute to this failure.This review focuses on the physiological function of the uterus and the related influence of aging mainly in rodent models.A better understanding of the underlying mechanisms governing the process of uterine aging is hoped to generate new strategies to prolong the reproductive lifespan in humans.