| a longitudinal study of junin virus activity in the rodent reservoir of argentine hemorrhagic fever. | we monitored junin virus (jv) activity in rodent populations for 30 months at seven mark-recapture grids located in agricultural fields and adjacent roadsides and fence lines in endemic and nonendemic areas of argentine hemorrhagic fever. blood and oral swabs taken from rodents captured at five-week intervals were analyzed by enzyme-linked immunosorbent assay for jv antigen (ag). calomys laucha and c. musculinus were the most frequently captured rodents, making up 47% and 22% of captures, respec ... | 1992 | 1335214 |
| microgeographic distribution of allele frequencies in populations of calomys laucha (rodentia, cricetidae). | the microgeographic differentiation of allelic frequencies was analysed in two population samples of calomys laucha, collected in a grid set in cultivated fields at laguna larga (córdoba province, argentina). one of the samples (n = 79) was obtained in may (autumn), when the population density is at a maximum, and the other (n = 85) in november (spring), at the onset of reproductive activity. fst values for the november sample show significant differences between the six groups over which the sa ... | 1991 | 1880049 |
| heterozygosity and gene flow in populations of calomys laucha (rodentia, cricetidae). | enzyme polymorphism was studied by means of starch gel electrophoresis on five population samples of calomys laucha collected in different sites and seasons. c. laucha, a cricetid rodent inhabiting preferentially cultivated fields in the central-eastern plains of argentina, is a reservoir-host of junin virus, agent of argentine hemorrhagic fever. results show high levels of genic variability in all the samples (p from 62.50 to 77.27; h from 0.118 to 0.163) and low genetic distance among populati ... | 1990 | 2194995 |
| bot fly parasitism (rogenhofera bonaerensis) (diptera, cuterebridae) in the pampean grassland mouse (akodon azarae), in argentina. | seasonality and impact of parasitism by the larvae of rogenhofera bonaerensis (diptera: cuterebridae) in pampean grassland mouse (akodon azarae, rodentia, cricetidae) populations were studied in grasslands and cropfield borders near diego gaynor (buenos aires province, argentina), from november 1985 to december 1986. trapped mice infections ranged from one larva (77%) to four (4%) per host; larvae occurred on tails (75.7%), backs (17.1%), thighs (5.7%), and abdomen (1.4%). prevalence of larvae o ... | 1990 | 2406466 |
| epidemiology of argentine hemorrhagic fever. | present knowledge points to horizontal transmission as the most significant mechanism for junín virus maintenance in the main natural reservoirs, namely calomys musculinus and calomys laucha. the existence of naturally infected akodon azarae, both within and outside the endemic area, as well as the finding that other species, ecologically and phylogenetically related to the main reservoirs, such as akodon molinae and calomys callidus, can experimentally develop persistent infections with virus s ... | 1988 | 2841151 |
| [natural infection of calomys laucha by trypanosoma cruzi]. | | 1980 | 7005601 |
| an outbreak of hantavirus pulmonary syndrome in western paraguay. | during an investigation of hantavirus pulmonary syndrome (hps) in paraguay in 1995, sera from persons with hps-like illness, houshold contacts of confirmed hps case-patients, and a sample of the area residents were analyzed by elisa for antibodies to sin nombre virus (snv). rodent serosurveys and analysis of precipitation records were also conducted. twenty-three of 24 available probable cases were snv antibody-positive, 17 of whom were ill between july 1995 and january 1996. four (14.8%) of 27 ... | 1997 | 9311636 |
| laguna negra virus associated with hps in western paraguay and bolivia. | a large outbreak of hantavirus pulmonary syndrome (hps) recently occurred in the chaco region of paraguay. using pcr approaches, partial virus genome sequences were obtained from 5 human sera, and spleens from 5 calomys laucha rodents from the outbreak area. genetic analysis revealed a newly discovered hantavirus, laguna negra (ln) virus, to be associated with the hps outbreak and established a direct genetic link between the virus detected in the hps cases and in the c. laucha rodents, implicat ... | 1997 | 9375015 |
| superovulation in vesper mice, calomys laucha--an important biomedical model for hantavirus and arenavirus (rodentia-sigmodontinae). | sigmodontine rodents are poorly studied and have not received much attention as a reproductive model. renewed interest in the south american rodents has been stimulated by their link to endemic diseases that are transmitted to man. calomys laucha acts as a reservoir of two dangerous viruses: an arenavirus named 'junin virus', the aetiological agent of argentinian haemorrhagic fever, and the hantavirus, both of which constitute serious sanitary problems. the aim of this study was to establish sui ... | 1999 | 10778786 |
| patterns of infection with laguna negra virus in wild populations of calomys laucha in the central paraguayan chaco. | in 1995, an outbreak of hantavirus pulmonary syndrome occurred in the central paraguayan chaco. the primary reservoir of the virus, laguna negra virus, was identified as the vesper mouse, calomys laucha. over a 15-month period, we collected 1,090 small mammals at 12 locations representing 4 habitats common in the central paraguayan chaco. calomys laucha was common in agricultural habitats and uncommon in the native forest habitat. populations of c. laucha were greater during the dry season month ... | 2001 | 11791973 |
| evaluation of an enzyme-linked immunosorbent assay for detection of antibodies to junin virus in rodents. | junin virus is the etiological agent of argentine hemorrhagic fever, a serious rodent-borne disease. an enzyme-linked immunosorbent assay (elisa) to detect junin virus igg antibodies in rodents was evaluated using sera from 27 calomys musculinus and five calomys laucha, inoculated experimentally with a live attenuated strain of this arenavirus. the test performance was compared against an indirect immunofluorescence assay (ifa). the elisa had a sensitivity and specificity of 100% and a reproduci ... | 2002 | 11906733 |
| interrelationship between ectoparasites and wild rodents from northeastern buenos aires province, argentina. | infestation parameters and indices of mites, ticks and fleas associated with wild rodents from northeastern buenos aires province, argentina, were studied. host species similarity was also analyzed in relation to their ectoparasites. fifty-five rodents were captured from january 2000 to march 2001. in total, 1,022 ectoparasites were collected and three ectoparasite-host associations were new records. however, this is the first study on craneopsylla minerva wolffhuegeli infesting parameters. ecto ... | 2003 | 12700861 |
| prevalence of infection with hantavirus in rodent populations of central argentina. | we studied hantavirus seroprevalence and virus variability in rodent populations in diego gaynor, northwest of buenos aires province, argentina. rodent samplings were conducted in railroads and cropfield borders in march and july 1999, september and december 2000, and march 2001. antibody detection was performed by an enzyme link immunosorbent assay (elisa), using the recombinant nucleoprotein of andes (and) virus as antigen. tissue samples were taken from positive antibody individuals in order ... | 2003 | 14595446 |
| the complex ecology of hantavirus in paraguay. | following an outbreak of hantavirus pulmonary syndrome (hps) in the paraguayan chaco in 1995, calomys laucha was identified as the rodent host for the hantavirus associated with these cases. to explore the possibility of additional hantaviruses in paraguay, we collected 636 mammals from 10 of the 17 departments. plasma from 27 animals in alto paraguay and boquer6n in the chaco and neembucú and itapúa in the eastern region had antibody to andes virus antigens. of these 27, five individuals (among ... | 2003 | 14628942 |
| in vitro assays for vesper mice (calomys laucha) sperm using heterologous substrates from nonrodent species. | small vesper mice (calomys laucha) may be considered as an animal model for in vitro fertilization studies, but limited data about in vitro evaluations of their sperm quality and fertility are available. the in vitro penetration (ivp) assay is used to estimate potential sperm fertility for many mammal species, but it still requires reduction in cost and labor. this study tested improvements in the ivp assay for c. laucha sperm using swine oocytes and perivitelline layers (pvl) of chicken eggs as ... | 2011 | 22106011 |
| a new species of syphacia (nematoda: oxyuridae) from calomys laucha (rodentia: cricetidae) in an agroecosystem of central argentina. | a new oxyurid nematode syphacia hodarae n. sp. is described from the cecum and rectum of the cricetid rodent calomys laucha fischer, 1814 (sigmodontinae, phyllotini), captured in an agroecosystem of central argentina. the new species is distinguished from other members of the genus mainly by the shape of the cephalic plate, presence of cervical alae in females, absence of lateral alae, and absence of deirids. some characters are shared with syphacia carlitosi, a parasite of akodon azarae from th ... | 2011 | 21506826 |
| sperm impairments in adult vesper mice (calomys laucha) caused by in utero exposure to bisphenol a. | this study aimed to evaluate the effects of in utero administration of bisphenol a (bpa) on semen parameters of vesper mice. sixty female calomys laucha were divided into six groups and received by gavage during gestation the following substances: water (negative control), olive oil (vehicle control), diethylstilbestrol (des - positive control - 6.5 μg kg(-1) bw) and bpa (40, 80 and 200 μg kg(-1) bw). male offspring were euthanised at 70 days of age, and sperm parameters were analysed. bpa reduc ... | 2014 | 24147964 |
| influence of mineral, olive or sunflower oils on male reproductive parameters in vitro--the wild rodent calomys laucha. | the aim of this study was to evaluate the influence of oils on male reproductive parameters in calomys laucha. twenty-four animals were distributed into four groups and given the following substances by gavage: water, mineral oil, olive oil and sunflower oil. after 10 days of gavage, the animals were euthanised and the semen was collected from them for assessing acrosome integrity and carrying out in vitro penetration (ivp) test. acrosome was significantly reduced (p < 0.05) for the vehicles in ... | 2014 | 23889566 |
| seasonal pelage color change: news based on a south american rodent. | mammalian seasonal molting and color change are known to be influenced by photoperiod changes. calomys laucha, a south american rodent, exhibits seasonal pelage color change; however, unlike northern hemisphere rodents, which present a gray or brown color during summer and a whitish color during winter, c. laucha pelage changes from an orange color during summer to a dark gray color during winter. animals maintained for over a year in stationary photoperiod (ld 12:12h, 22 degrees c) presented or ... | 2006 | 16532209 |
| successful capacitation and homologous fertilization in vitro in calomys musculinus and calomys laucha (rodentia - sigmodontinae). | small south american rodents of the genus calomys have been used extensively for virology and ecological research. previous studies have demonstrated that calomys musculinus and calomys laucha have a relatively short oestrous cycle and that superovulation and parthenogenetic activation can be induced. the purpose of this study was to determine the requirements for in vitro manipulation of the male gamete and in vitro fertilization. two culture media and different concentrations of spermatozoa we ... | 2000 | 11006144 |
| the kinetics of oocyte activation and dynamics of polar body formation in calomys musculinus and calomys laucha (rodentia-sigmodontinae). | the objective of this study was to determine whether calomys laucha and calomys musculinus superovulated oocytes undergo parthenogenetic activation following activation stimuli. cumulus-intact or denuded oocytes were treated with medium containing ethanol (7%), medium containing strontium chloride, or medium alone. they were then incubated for 6-8 h to allow for activation. a group of oocytes was fixed immediately after maturation to serve as a control. the nuclear status of the oocytes was exam ... | 1999 | 10717953 |
| protein polymorphism and genetic distance in south american cricetid rodents of the genus calomys. | allozymic variation in population samples of calomys laucha, c. musculinus and c. venustus collected simultaneously from the province of córdoba, argentina, was analyzed by gel electrophoresis. these three species showed high levels of polymorphism: for c. laucha, the p value was 72.7% and the h value was 0.147 (19 loci); for c. musculinus, p = 61.9% and h = 0.149 (20 loci); for c. venustus, p = 66.7% and h = 0.146 (18 loci). these species are non-fossorial generalists, have a high reproductive ... | 1990 | 2199323 |
| calomys laucha (rodentia, cricetidae): growth and breeding in laboratory conditions. | the husbandry and breeding of calomys laucha (rodentia, cricetidae) in captivity are described. growth curves based on body weight and length showed statistical differences between sexes after 45 days, males being heavier than females. the overall reproductive efficiency was 53.4% but birth rate was depressed during winter. gestation length was 21 +/- 1 days and females exhibited postpartum oestrus with a 3-7 day implantation delay (51%). litter size was 5.3 +/- 1.1 (n = 34). pup survival at wea ... | 1989 | 2681995 |
| low atrazine dosages reduce sperm quality of calomys laucha mice. | reproductive effects caused by the exposure to environmentally relevant dosages of atrazine on wild animals are poorly understood. this study evaluated the effects of three dosages of atrazine on sperm parameters of adult calomys laucha males. adult mice were orally exposed to dosages of 0 (water and vehicle control), 0.1, 1, and 10 mg/kg of animal weight for a 21-day period. following exposure, analyses were performed to determine sperm motility parameters, plasma membrane integrity and fluidit ... | 2018 | 29147981 |
| use of an argentinean wildlife tissue collection for epidemiological studies of histoplasmosis. | histoplasmosis is a worldwide systemic endemic mycosis caused by several cryptic species included within the histoplasma capsulatum complex. domestic and wild mammals are susceptible to infection by this fungus and could be used as indicators of its presence in the environment. the aim of the study was to identify the natural reservoirs of h. capsulatum in the argentinean humid pampas eco-region analyzing a wildlife frozen-tissue collection and trace its distribution patterns over time and space ... | 2020 | 31993951 |
| multimarker approach to assess the exposure of the wild rodent calomys laucha to a simulated crude oil spill. | a mysterious oil spill occurred in the ocean near brazil in 2019, which affected coastal areas in northeastern brazil. when oil pollution occurs in coastal zones, organisms such as small mammals can suffer deleterious effects to their health. this study aimed to evaluate the effects of exposure to contaminated sandy soil with different crude oil concentrations in males of the species calomys laucha. the exposure to crude oil resulted in multiple health issues for the subjects in the very first d ... | 2020 | 32880044 |
| atrazine exposure in gestation and breastfeeding affects calomys laucha sperm cells. | the present study evaluated the effects of low doses of atrazine administered during gestation and breastfeeding on sperm characteristics of the wild rodent calomys laucha. adult females were divided into groups of 10 and administered different doses of atrazine through gavage, during gestational or breastfeeding period. at 3 months of age, the f1 adult male progeny of these females was evaluated. we observed a drastic reduction in the total and progressive motility of male sperm cells at all do ... | 2019 | 31664666 |
| effects of exposure to triphenyltin (tpt) contaminant on sperm activity in adulthood of calomys laucha exposed through breastfeeding. | triphenyltin (tpt) is an organotin compound (ot), primarily used in agriculture and in the composition of antifouling paints for ships worldwide. studies have showed its effects as an endocrine disrupter in several organisms by preventing enzymatic expression and causing reproductive toxicity. this study aimed to evaluate the effects of exposure to tpt, via breastfeeding, on reproductive physiology in the calomys laucha species. the experimental design was compound of five groups, two controls a ... | 2019 | 30706268 |
| triphenyltin exposition induces spermatic parameter alters of calomys laucha species. | the present study aims to evaluate the influence of triphenyltin (tpt) exposure on reproductive physiology on calomys laucha species, since this species inhabits regions susceptible to exposure to this contaminant. animals exposed to the highest dose (10.0 mg/kg) presented signs of severe intoxication in only 7 days of exposure, demonstrating a higher sensitivity of this species to triphenyltin. the 10.0 mg tpt/kg dose was analyzed separately for short-term exposure and results suggest that expo ... | 2018 | 30223333 |