A simple technique for sex chromatin analysis in amniotic cells of mouse and rat embryos

A simple technique has been developed for sex chromatin analysis in the amniotic membrane of rodent embryos. This technique combines the use of 60% acetic acid as a fixative and a carbol fuchsin stain. This technique may be useful for quick sex diagnosis of rodent embryos at midgestation for various purposes in experimental embryology.     

A Simple Technique for Sex Chromatin Analysis in Amniotic Cells of Mouse and Rat Embryos

A simple technique has been developed for sex chromatin analysis in the amniotic membrane of rodent embryos. This technique combines the use of 60% acetic acid as a fixative and a carbol fuchsia stain. This technique may be useful for quick sex diagnosis of rodent embryos at midgestation for various purposes in experimental embryology.     

New building, old parasite: Mesostigmatid mites--an ever-present threat to barrier facilities

Mesostigmatid mites are blood-sucking parasitic mites found in wild rodent populations. Periodically they can also become a problem for laboratory rodent colonies, particularly when building construction or renovations disturb colonies of commensal (building) rodents that had been acting as hosts. Mesostigmatid mites infest both rats and mice and, unlike the more common rodent fur mites (Myobia, Myocoptes, and Radfordia sp.), can survive for long periods in the environment and travel considerable distances in search of new hosts. They easily penetrate barrier caging systems, including individually ventilated cages, thus circumventing the usual precautions to protect rodents from infection. The two mites reported in laboratory rodent colonies, Ornithonyssus bacoti and Laelaps echidnina, also bite humans and have the potential to transmit zoonotic diseases. Once the mites gain access to a colony, eradication requires elimination of commensal rodent reservoirs in addition to insecticide treatment of both the laboratory rodents and the environment. In view of the undesirability of insecticide use in the animal facility, it is advisable to investigate the effectiveness of preventive treatments, such as environmental application of insect growth regulators or silica-based products. This article summarizes available information on mesostigmatid mites and their laboratory incursions, and provides suggestions for diagnosis, treatment, and control based on the authors experience with several outbreaks at a large academic institution..     

钱塘江河口滩涂围垦区人口迁居与农田小兽群落的关系

1987年8月和1989年8月,作者对钱塘江河口滩涂围垦区人口迁居与农田小兽群落的关系进行了调查。在6种类型的人群居住区内,4种家栖小兽中以臭鼩为优势种。随着人口和建筑物增多,食虫类数量超过家鼠,处于优势地位,因而在家鼠与食虫类之间有一定程度的负相关。同时还探讨了家栖小兽群落与农田小兽群落之间的迁移和扩散的关系。     

自然生态条件下鼠类数量与天敌数量的平衡关系

近些年,越来越多的科学家将天敌对鼠害的控制作用纳入综合防治的总体方案之中,大部分学者倾向认为,天敌是鼠类种群数量调节的主要因素之一。研究天敌在鼠类种群动态中所起的作用,不仅对鼠害防治工作具有重要意义,而且有助于生态学理论的发展。本文在有关天敌对鼠类种...     

From rodent reagents to human therapeutics using antibody guided selection

Guided selection is a method of producing a human version of a rodent or any other non-human antibody. The process is a serial transition from rodent to human via rodent-human chimaerics, through to a panel of human antibodies with similar characteristics to those of the starting rodent antibody. The guided selection process can be undertaken using either phage display or ribosome display, and chimaeric antibodies can be made either in series or parallel, with or without the retention of the original rodent CDR3s. Guided selection has successfully been used for the generation of a number of human versions of rodent antibodies, including HUMIRA, an inhibitor of tumour necrosis factor-alpha which is approved for the treatment of moderate to severe rheumatoid arthritis in over 40 countries.     

Geographic variation in rodent-flea relationships in the presence of black-tailed prairie dog colonies

We characterized the relationship between fleas and their rodent hosts in the presence of prairie dog colonies and compared them to adjacent assemblages away from colonies. We evaluated the rodent-flea relationship by quantifying prevalence, probability of infestation, flea load, and intensity of fleas on rodents. As prairie dog burrows provide refugia for fleas, we hypothesized that prevalence, flea load, and intensity would be higher for rodents that are associated with black-tailed prairie dog colonies. Rodents were trapped at off- and on-colony grids, resulting in the collection of 4,509 fleas from 1,430 rodents in six study areas. The rodent community composition varied between these study areas. Flea species richness was not different between prairie dog colonies and the surrounding grasslands (p = 0.883) but was positively correlated with rodent species richness (p = 0.055). Prairie dog colonies did not increase the prevalence of fleas (p > 0.10). Flea loads on rodents did not vary between off- and on-colony grids at three of the study areas (p > 0.10). Based on the prevalence, infestation rates, and flea loads, we identified Peromyscus maniculatus, Onychomys leucogaster, and two Neotoma species as important rodent hosts for fleas and Aetheca wagneri, Orchopeus leucopus, Peromyscopsylla hesperomys, Pleochaetis exilis, and Thrassisfotus as the most important fleas associated with these rodents. Prairie dog colonies did not seem to facilitate transmission of fleas between rodent hosts, and the few rodent-flea associations exhibited significant differences between off- and on-colony grids.     

Oncogene and tumor suppressor gene alterations in nasal tumors

The development of nasal tumors in humans and rodents is likely mediated through the accumulation of genetic alterations in genes that regulate cell proliferation, cell death and differentiation (oncogenes and tumor suppressor genes). By examination of the relationship between genetic alterations that are known to occur in human cancers with those induced in rodent tumors with defined carcinogenic exposures, biologically relevant mechanistic linkages of molecular events leading to tumors in rodents and humans can be established. Molecular genetic studies on nasal squamous cell carcinomas (SCC) in rats thus far have indicated the presence of oncogenes unrelated to the ras oncogene family and that p53 mutation occurs at a high frequency among the nasal SCC examined. The finding of p53 mutations in rat nasal SCC and the high prevalence of p53 mutations among human SCC, indicates that a common molecular alteration is shared between rodent and human SCC.     

RXR-LXR heterodimer modulators for the potential treatment of dyslipidemia

A number of RXR agonists were synthesized and screened in functional assays. The synthesis and the structure-activity relationship (SAR) within the series of compounds will be presented. Some in vivo data in rodent models for dyslipidemia and diabetes will also be presented.     

贺兰山西坡啮齿动物生境选择及种间关系

为明确对贺兰山西坡啮齿动物生境选择起关键作用的主要环境因子,探讨各鼠种之间的相互作用如何影响鼠种的生境选择,选取地理因子（海拔、坡度、坡向）、植被因子（植被盖度、植被高度、灌木/乔木高度）和其他因子（距水源距离、距道路距离、距灌木/乔木距离）等9种生境因子,利用资源选择函数模型和logistic回归模型对啮齿动物生境选择和种间关系进行分析。结果表明,在贺兰山西坡,捕获数量最多的6种啮齿动物对的生境选择存在差异,大林姬鼠（Apodemus peninsulae）偏好高海拔、多灌木（乔木）的生境;子午沙鼠（Meriones meridianus）偏好海拔较低的半荒漠稀疏生境,对道路和人为干扰不回避;灰仓鼠（Cricetulus migratorius）偏好距水源较远、多灌木（乔木）、距道路较近的生境;阿拉善黄鼠（Spermophilus alaschanicus）偏好低海拔、植被丰富的生境;短尾仓鼠（Cricetulus eversmanni）偏好高海拔、距道路较近的生境;社鼠（Niviventer niviventer）偏好海拔较高、坡度较大、距水源较远的生境。鼠种间的相互关系主要呈现回避或随机关系。研究结果有助于了解啮齿动物分布的变化及种群动态规律,可为贺兰山生物资源保护,区域性鼠害的预测、预报和综合治理提供基础资料和科学依据。     

Genome size and heterochromatin variation in rodents

Nuclear DNA amounts are determined in 16 species and the C-banding patterns for 19 species of rodents. A list of rodent DNA amounts is compiled. The fraction of heterochromatin in the genome is determined as the length of C-banded chromosome material relative to the total karyotype length. Among all rodents, heterochromatin amounts tend to be larger in the larger genomes. However, this relationship is not exact and does not hold true for individual genera. In general the notion of a basic rodent genome of defined size to which various amounts of heterochromatin have been added is untenable.     

Synthesis and SAR development of novel P2X7 receptor antagonists for the treatment of pain: part 2

Novel P2X₇ antagonists were developed using a purine scaffold. These compounds were potent and selective at the P2X₇ receptor in human and rodent as well as efficacious in rodent pain models. Compound 15a was identified to have oral potency in several pain models in rodent similar to naproxen, gabapentin and pregabalin. Structure–activity relationship (SAR) development and results of pain models are presented.     

基于进化足迹法结合位置打分函数的转录因子结合位点预测

目的:预测转录因子结合位点。方法:本文从ABS数据库上下载了人类和啮齿类动物的直系同源的启动子序列,首先使用位置打分函数对这些启动子序列进行打分,找到候选的转录因子结合位点,并进一步利用进化足迹法对这些候选的转录因子结合位点进行筛选,只有结合位点同时出现在人类和啮齿类动物的启动子序列才认为是真正的结合位点。结果:在对人类和啮齿类动物进行转录因子结合位点预测时,与单独使用打分函数的结果相比,进化足迹法与打分函数结合的方法有效的提高了预测结果的性能,大幅度提供所得预测结果的特异性。结论:进化足迹法结合位置打分矩阵的方法能较为准确有效的预测转录因子结合位点。     

长爪沙鼠的肝毛细线虫感染率与鼠类及猛禽密度的关系

为研究鼠类密度和猛禽密度对鼠类肝毛细线虫(Capillaria hepatica)感染率的影响,作者于2004年7月在内蒙古锡林郭勒盟阿巴嘎旗北部和东乌珠穆沁旗西南部典型草原草场选取了14个实验样地,采用洞口计数法(四分之一圆面积法)调查估计各实验样地内长爪沙鼠(Meriones unguiculatus)密度,同时采用夹线调查法捕获鼠类样本,进行常规解剖获取肝毛细线虫的感染数据。采用目测计数法统计猛禽的出现频次,并以其出现频次作为猛禽的相对密度指标。实验样地共捕获长爪沙鼠1 058只,观察到鹰隼类活动69只次。数据分析结果表明,长爪沙鼠肝毛细线虫感染率与鼠类密度之间存在极显著的正相关关系(P0.01,R~2=0.926),长爪沙鼠肝毛细线虫感染率与猛禽密度之间亦存在极显著的正相关关系(P0.01,R~2=0.853)。该结果说明,长爪沙鼠是肝毛细线虫的主要宿主,鼠类密度和猛禽密度的升高均会增加长爪沙鼠肝毛细线虫感染率,猛禽密度和鼠类密度之间还存在叠加效应,猛禽的捕食作用会加快肝毛细线虫病的传播周期,加重肝毛细线虫病疫情。     

荒漠啮齿动物群落与植物群落的对应分析

动物与其生存环境变量之间的关系一直是生态学家们广泛关注的问题.啮齿动物作为荒漠生态系统中重要的功能群,其数量大小和生态功能对生态系统的平衡和稳定具有重要意义.生境中的植被为啮齿动物提供赖以生存的食物资源和栖息地,了解啮齿动物群落与植被特征之间的关系对于理解动物群落变动规律具有重要意义.不同植被条件下啮齿动物群落的结构不同,Hernández等(2005)研究发现北美Chihuahuan荒漠的灌木生境中啮齿动物密度高于草地生境.     

Pneumocystis: newer knowledge about the biology of this group of organisms in laboratory rats and mice

This review is an update on some of the remarkable advances that have led to greater understanding of Pneumocystis, an important group of rodent pathogens. The author outlines the life cycle of these pulmonic fungi, their taxonomic position, and their nomenclature. He discusses how infections begin and spread in laboratory rodent colonies, and how those infections are inadvertently maintained in barriered breeding colonies. He also addresses the diagnosis of Pneumocystis infection and provides suggestions for the establishment of Pneumocystis-free animal colonies.     

我国害鼠不育控制研究进展

害鼠给人类带来巨大的经济损失,导致严重的生态问题。人们采用各种方法防治鼠害,其中不育控制是一种新的方法。不育控制即通过某种手段使雄性或和雌性绝育,或阻碍胚胎着床,甚至阻断幼体生长,以降低生育率。不育控制的概念最早在20世纪60年代提出,近年来,我国在利用不育技术控制害鼠方面做了大量研究,总结了国内该领域研究的部分结果。在实验室测试了多种不育剂。被测试的不育剂对相应的鼠类几乎都有不育作用;一些不育剂会影响鼠类的行为,这会减弱竞争性繁殖干扰的作用;一些不育剂在达到一定剂量后有致死作用,不育和灭杀的双重作用会产生更好的控制效果;还观察到不育个体的复孕现象,这会减弱控制效果;关于不育剂安全性的研究发现更昔洛韦和M001雄性不育灭鼠剂对家鸽没有任何毒性作用。大量野外实验证实不育剂对害鼠大都有较好的控制效果,实际控制中,控制面积不宜太小。利用数学模型所作的理论分析表明不育控制有不比灭杀控制差的效果;在决定种群是否灭绝上,不育率、灭杀率、选择性收获率等的作用是相同的。根据研究的实际情况,本文提出了一些今后研究中应注意的问题。无论在实验室还是野外,除了种群动态外,还要记录更详细的数据,以期对不育控制有更详细的了解。要加大不育剂对非靶向动物和环境影响的研究。在不育控制这种干扰下,害鼠种群的变化必然导致与其相关的种群也作出相应的变化,这一方面的研究需要进行。每种控制方式都有自己的特点,多种控制方法联合使用会达到更理想的效果。竞争性繁殖干扰现象是存在的,它使种群规模更小,在数学模型中,应体现出这一因素。     

Indirect food web interactions affect predation of Tengmalm's Owls Aegolius funereus nests by Pine Martens Martes martes according to the alternative prey hypothesis

Although population cycles of rodents are geographically widespread and occur in a number of rodent species, higher‐order food web interactions mediated by predator–rodent dynamics have primarily been described from boreal and arctic biomes. During periods of low rodent abundance, predators may switch to alternative prey, which may affect other predators directly or indirectly. Using a long‐term dataset, we assessed the frequency of Pine Marten Martes martes predation on the nests of Tengmalm's Owl Aegolius funereus during periods of fluctuating rodent abundance in Central Europe. The number of nests predated by Pine Martens was positively correlated with the annual number of nests available. The probability of predation by Pine Martens on Tengmalm's Owl nests decreased with increasing spring abundance index of Apodemus mice, but was not related to the abundance index of Myodes and Microtus voles, pooled rodent abundance or age of the nestbox. Additionally, we found no relationship between the breeding frequency (i.e. the number of nesting attempts per nestboxes available) and an abundance index of Microtus and Myodes voles, Apodemus mice or overall rodent abundance. Our results demonstrate, for the first time in a temperate area, that during periods of low Apodemus mouse abundance, the switching response of an opportunistic mammalian predator can lead to indirect food web interactions through an increase in nest predation on a sympatric avian predator.     

The morphogenetic causes of parallelisms in the dental system of rodents]

Morphogenetic causes of the origin of true hypsodonty and transformation of bunodont teeth pattern to lophodont one in the rodent evolution are discussed. Wide distribution of these processes in different rodent groups and many other mammals can be explained by the universality of morphogenetic mechanisms of teeth development and by scantiness of their possible transformation pathways.