Rodentia

Attention deficit hyperactivity disorder (ADHD) presents special challenges for drug development. Current treatment with psychostimulants and nonstimulants is effective, but their mechanism of action beyond the cellular level is incompletely understood. We review evidence suggesting that altered reinforcement mechanisms are a fundamental characteristic of ADHD. We show that a deficit in the transfer of dopamine signals from established positive reinforcers to cues that predict such reinforcers may underlie these altered reinforcement mechanisms, and in turn explain key symptoms of ADHD. We argue that the neural substrates controlling the excitation and inhibition of dopamine neurons during the transfer process are a promising target for future drug development. There is a need to develop animal models and behavioral paradigms that can be used to experimentally investigate these mechanisms and their effects on sensitivity to reinforcement. More specific and selective targeting of dru...

Effective small interfering RNA (siRNA)-mediated therapeutics require the siRNA to be delivered into the cellular RNA-induced silencing complex (RISC). Quantitative information of this essential delivery step is currently inferred from the efficacy of gene silencing and siRNA uptake in the tissue. Here we report an approach to directly quantify siRNA in the RISC in rodents and monkey. This is achieved by specific immunoprecipitation of the RISC from tissue lysates and quantification of small RNAs in the immunoprecipitates by stem-loop PCR. The method, expected to be independent of delivery vehicle and target, is label-free, and the throughput is acceptable for preclinical animal studies. We characterized a lipid-formulated siRNA by integrating these approaches and obtained a quantitative perspective on siRNA tissue accumulation, RISC loading, and gene silencing. The described methodologies have utility for the study of silencing mechanism, the development of siRNA therapeutics, and ...

The use of plant protection products on agricultural crops can result in exposure of birds and mammals to toxic chemicals. In the European Union, the risks from such exposures are assessed under the current (2009) guidance document from the European Food Safety Authority (EFSA), designed to increase the realism of the theoretical risk assessments in comparison to its predecessor (SANCO/4145/2000). Since its adoption over 7 yr ago, many plant protection products have been evaluated successfully using the 2009 EFSA guidance document. However, there are still significant areas of improvement recommended for future revisions of this guidance. The present Focus article discusses experiences to date with the current scheme, including levels of conservatism in input parameters and interpretation by regulatory authorities together with proposals for how the guidance document could be improved when it is revised in the not too distant future. Several areas for which further guidance is recom...

Yersinia pestis invaded the continental United States in 1900 and subsequently became established in wild rodent populations in several western states, traversing 2,250 km in approximately 40 years. However, the specific path of the eastward expansion of plague into the United States is poorly understood. We directly calculated velocities of disease spread and performed trend-surface analyses on spatio-temporally unique plague cases to clarify the route and speed of the initial spread of plague eastward. Velocities of disease spread were then analyzed using multiple linear regression models to identify environmental features that significantly impacted the rate of spread. Between one and three introductions of plague along the Pacific coast were observed, after which plague traveled from 45 to 87 km/year. In all regression models, the coast ranges of California were associated with slower spread, and the Southern Rockies were associated with a significant increase in the rate of dis...

Hantaviruses are causative agents of some severe human illnesses, including hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). The viruses are maintained by rodent hosts, and humans acquire infection by inhaling virus-contaminated excreta from infected animals. To examine the epidemiology of hantavirus infections in Japan and Far East Russia, we conducted epidemiological surveys in these regions. In Japan, anti-hantavirus antibodies were found in four rodent species, Clethrionomys rufocanus, Rattus norvegicus, R. rattus, and Apodemus speciosus. Although no new HFRS cases have been officially reported over the past 20 years in Japan, one member of the Japan Ground Self-Defense Force did test positive for hantavirus antibody. Repeated surveys in Far East Russia have revealed that two distinct hantavirus types cause severe HFRS in this region. Hantavirus sequences identified from A. peninsulae, fetal HFRS cases in Vladivostok, and Amur virus are highl...

This article reviews the main events of embryo-implantation and decidualization in rodents. In common laboratory rodents the embryo attaches to the uterine epithelial lining, usually on days 4 to 6 of pregnancy. A progressive degree of proximity between trophoblast and epithelium occurs until the epithelial cells undergo apoptosis and detach from the basement membrane. During the attachment stage, the spindle-shaped connective tissue cells that underlie the epithelium next to the embryos transform into polyhedral and closely packed decidual cells. Following the epithelial detachment and the breaching of the basement membrane the embryo is thus in direct contact with decidual cells. These cells accumulate organelles associated with synthesis of macromolecules, intermediate filaments, and eventually lipid droplets and glycogen. Another remarkable feature of decidual cells is the establishment of gap and adherens intercellular junctions. Differentiation of fibroblasts into decidual cells advances antimesometrially and mesometrially, creating in the endometrium several regions of cells with different morphology. The whole phenomenon of decidualization which is normally triggered by the embryo can be artificially induced in pseudopregnant or hormonally-prepared animals with the use of diverse stimuli. The uterine epithelium is probably responsible for the transduction of the initial stimulus. Prostaglandins have been shown to be important in the induction of decidualization. More recently other substances such as leukotrienes, platelet-activating factor (PAF), and transforming growth factor (TGF) have been thought to play a role in induction. Much evidence points to prostaglandin production by the decidual cells. New proteins such as a luteotropic factor, desmin, and other molecules were shown to be produced after rat stromal cells undergo decidual transformation. The extracellular matrix of the mouse decidua contains very thick collagen fibrils. Mouse decidual cells are also very active in phagocytosing the thick fibrils, contributing to the remodeling and involution of the decidua that accompanies embryonic growth. Radioautographic data indicates that mouse decidual cells produce and secrete collagen and sulfated proteoglycans. © 1993 Wiley-Liss, Inc.

В учебное пособие входят практические рекомендации по проведению отловов, учетов, коллектированию и содержанию в не-воле мелких млекопитающих. Пособие включает подробные методики по изучению поведения, питания, гельминтов грызунов и землероек, оригинальный определитель позволяет установить не только видовую, но и половозрастную принадлежность изучаемых объектов. Учебное пособие предназначено для студентов и аспирантов биологических специальностей и может быть использовано для про-ведения самостоятельных исследований учителями биологии, молодыми учеными.

Patagonian cavies (Dolichotis patagonum) are large South American rodents well adapted for cursorial life (well adapted for running). They are monogamous but can live in groups of up to 70 individuals who maintain communal burrows. They are primarily herbivorous and may be maintained on commercially produced rodent or primate diets. Their long, thin legs and skittish nature make them difficult to restrain. Common medical problems include malocclusion of cheek teeth, gastrointestinal parasites, hypertrophic cardiomyopathy, and traumatic leg fractures.

Behavioural and trapping studies of the social organization of coypus have suggested the occurrence of kin groups and a polygynous mating system. We used 16 microsatellite markers to analyse parentage and relatedness relationships in two populations (Jáuregui and Villa Ruiz) in the Argentinean Pampas. At Jáuregui, a dominant male monopolized most paternities, leading to a high variance in reproductive success between males and a high level of polygyny. At Villa Ruiz, variance in reproductive success was low among resident males and males were the fathers of zero to four offspring each. For females, no significant differences were found. Two different social groups in each study site were used to assess genetic relatedness within and between groups. These groups were neighbouring at Jáuregui but not at Villa Ruiz. At Villa Ruiz, coypus were significantly more related within than between groups, suggesting that behavioural groups were also genetic ones, and adult females were more rel...

We study the micromammals from the sites of Valdocarros and HAT, located in the lithostratigraphic unit of Arganda II and IV respectively, within the Arganda Complex Terrace, in the Jarama Valley (Madrid, Spain). The micromammal associations of these sites consist of the following taxa: in Valdocarros: Erinaceomorpha: Erinaceus europaeus; Soricomorpha: Crocidura aff. russula; Rodentia: Eliomys quercinus, Castor fiber, Apodemus sp., Cricetulus (Allocricetus) bursae, Arvicola aff. sapidus and Microtus brecciensis; and Lagomorpha: Oryctolagus cuniculus; and in HAT: Soricomorpha: Soricidae indet.; Rodentia: Eliomys quercinus, Apodemus sp., Arvicola aff. sapidus and Microtus cf. cabrerae; and Lagomorpha: cf. Oryctolagus sp. The micromammal assemblage of the Valdocarros site can be placed in the advanced Middle Pleistocene, but not in its end, because of the faunal association and the evolved state of Microtus brecciensis. However, in HAT, the presence of Microtus cf. cabrerae suggests that this site belongs to the Late Pleistocene. Both micromammal assemblages indicate a temperate climate and a well developed vegetation cover, consisting of some forest and also open areas, with shrub-like vegetation and also meadow and riverside vegetation.

Fullest available information about mammals in Bulgaria is synthesized in the representation of individual species, and generalizations concerning the entire fauna, including some traditional aspects of this type of monographs - historical development patterns and the formation of the fauna, modern species composition, zoogeographic characteristics, territorial differentiation in the light of spatial heterogeneity of environmental conditions topography, geography, climate, vegetation). An extensive summary in English contains original keys, separately for three groups of characters ( external, skull, lower jaws), and short faunal information for each species.