Ecology of Hantaan virus at Twin Bridges Training Area,Gyeonggi Province,Republic of Korea, 2005–2007

The Twin Bridges Training Area (TBTA) in the Republic of Korea consists of dirt roads, barren training areas, and forested hillsides adjacent to linear and broad expanses of tall grasses, herbaceous, and scrub vegetation. Of the six species of small mammals, the striped field mouse, Apodemus agrarius, was the most frequently captured (96.1%). Apodemus agrarius capture rates varied from 17.7 to 33.2% during three trapping periods. Gravid females were observed during November‐December 2006 (8.4%) and March 2007 (5.1%). In 2005, the overall seroprevalence of Hantaan virus (HTNV) was high (34.4%) and lower during surveys in 2006 (14.2%) and 2007 (13.8%). Seroprevalence was directly correlated with weight increase of A. agrarius.     

Field evaluation of alpha-chlorohydrin against the Indian mole rat: studies on toxic and antifertility effects

Field acceptance and efficacy of a toxicant-sterilant, alpha-chlorohydrin (α-CH), at its 0.5% concentration in bait were evaluated against rodents in sugarcane fields which harboured high populations of the Indian mole rat Bandicota bengalensis (Trap Index (TI) = 53.6 rats/100 traps/24 h) followed by that of the Indian bush rat Golunda ellioti (TI = 28.6) and soft-furred field rat Rattus meltada (TI = 1.8). Acceptance of the α-CH bait by rodents in the fields was evident from complete consumption of the offered bait at most of the baiting points. The treatment (72 h exposure to the poison bait) resulted in 63.7% to 82.9% rodent mortality. Survey of the mature sugarcane crop revealed that the percentage of rodent cut canes in the treated fields (7.6% to 16.2%) was significantly less than that of the reference fields (26.3%). Most of the surviving male B. bengalensis, captured after 15 days of the treatment, had developed sterility as revealed by the functional abnormalities in their testes and epid-idymides. They showed decreased thickness of the seminiferous tubules, lower population of spermatogenic cells, cauda epididymal sperm concentration, live sperm and sperm mortality. A nonsignificant positive correlation between the testicular weight and sperm motility in males from treated fields indicated the effect of α-CH at maturation level in the cauda epididymides. Overall, it was evident that a significant proportion of the surviving B. bengalensis had become permanently sterile as a consequence to the development of spermatocoeles in the caput epididymides and the remaining had significantly low numbers (< 30%) of motile sperm in their cauda epididymides which was, obviously, a handicap for successful fertilisation.     

Post‐traumatic stress disorder and beyond: an overview of rodent stress models

Post‐traumatic stress disorder (PTSD) is a psychiatric disorder of high prevalence and major socioeconomic impact. Patients suffering from PTSD typically present intrusion and avoidance symptoms and alterations in arousal, mood and cognition that last for more than 1 month. Animal models are an indispensable tool to investigate underlying pathophysiological pathways and, in particular, the complex interplay of neuroendocrine, genetic and environmental factors that may be responsible for PTSD induction. Since the 1960s, numerous stress paradigms in rodents have been developed, based largely on Seligman's seminal formulation of ‘learned helplessness’ in canines. Rodent stress models make use of physiological or psychological stressors such as foot shock, underwater trauma, social defeat, early life stress or predator‐based stress. Apart from the brief exposure to an acute stressor, chronic stress models combining a succession of different stressors for a period of several weeks have also been developed. Chronic stress models in rats and mice may elicit characteristic PTSD‐like symptoms alongside, more broadly, depressive‐like behaviours. In this review, the major existing rodent models of PTSD are reviewed in terms of validity, advantages and limitations; moreover, significant results and implications for future research—such as the role of FKBP5, a mediator of the glucocorticoid stress response and promising target for therapeutic interventions—are discussed.     

Harm to Others Acts as a Negative Reinforcer in Rats

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Small mammal diversity and dynamics within Nigeria,with emphasis on reservoirs of the lassa virus

Nigeria has a rich small mammal community, with several species implicated as carriers of zoonotic microbes such as the Lassa virus (LASV). We sought to elucidate the diversity and distribution of these animals (including known LASV reservoirs) geographically, habitat-wise and seasonally. Our DNA-assisted survey detected at least 19 small mammal species amongst 790 specimens. Diversity indices were similar between ecological zones and also between endemic and non-endemic areas for Lassa fever. Mastomys natalensis, the most renowned LASV host, was present in eight out of nine localities sampled. We also described the spatial occurrence of other known LASV hosts such as M. erythroleucus and Hylomyscus pamfi, including carriers of LASV-like arenaviruses such as Mus (Nannomys) spp. The most numerous rodents (Mastomys natalensis, M. erythroleucus, and Praomys daltoni) were captured mainly inside human dwellings. Reproductive activity occurred throughout the year, but led to population peaks for M. natalensis in the dry season and for M. erythroleucus and P. daltoni in the rainy season. Extensive geographic distribution of LASV rodent reservoirs, with population peaks in different seasons, shows that the risk of rodent-to-human transmission of LASV is greater than currently realized.     

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ABSTRACT

In most mammals, adults produce relatively low frequency vocalizations compared to those of juveniles. This rule is not maintained however at least in four species of ground squirrels, whose juveniles call at the adult's fundamental frequency. These findings have been obtained however with separate sets of juveniles and adults and no data is available concerning the ontogeny linked to these differences. Here we analyze the acoustic structure of alarm calls of the same Yellow Spermophilus fulvus and Speckled S. suslicus ground squirrel individuals, recorded as pups and as adults after hibernation. We found the fundamental frequencies of adults within the same frequency ranges as those of pups, in spite of the significant difference in body mass. In ground squirrels, severing the relationship between body size and call frequency removes some vocal cues to age. We discuss some functional hypotheses advanced to explain manipulations with fundamental frequencies in ground squirrels and other animals, and suggest the lack of data for discussing the mechanisms of such vocal tuning.