| geographic patterns of chromosomal variation in south american marsh rats, holochilus brasiliensis and h. vulpinus. | karyotypes were prepared from 146 individuals, representing nine populations evenly spaced along a 2,000-km north-south transect in paraguay and argentina, to determine the nature, extent, and pattern of chromosomal variation in holochilus brasiliensis chacarius and h. vulpinus. two distinct patterns of chromosomal variation characterized these two species. in h. brasiliensis, the diploid number (2n) ranged from 48 to 56 and the nombre fondamental (nf) from 57 to 63. four classes of chromosomal ... | 1992 | 1505226 |
| meiotic studies of robertsonian polymorphisms in the south american marsh rat, holichilus brasiliensis. | meiosis was studied in male south american marsh rats (1) to help clarify the mechanisms that allow unusually high levels of robertsonian (rb) polymorphisms to be maintained in wild populations of these animals and (2) to test competing assumptions in two distinct models of chromosomal speciation. in both simple rb heterozygotes and rb heterozygotes with monobrachial homology, no univalency was observed in prophase i or metaphase i. rates of nondisjunction were uniformly low (less than 10%) and ... | 1992 | 1505227 |
| occurrence and treatment of the mange mite notoedres muris in marsh rats from south america. | the mange mite notoedres muris is reported from a new host, the marsh rat (holochilus brasiliensis) from argentina. the infection involved alopecia and encrustations on the ears and face, and was treated successfully by a subcutaneous injection of ivermectin. the new record suggests that notoedres muris has become self-maintaining within this marsh rat population. | 1990 | 2406468 |
| exceptional chromosomal mutations in a rodent population are not strongly underdominant. | the observation of karyotypic uniformity in most species has led to the widespread belief that selection limits chromosomal change. we report an unprecedented amount of chromosomal variation in a natural population of the south american marsh rat holochilus brasiliensis. this variation consists of four distinct classes of chromosomal rearrangements: whole-arm translocations, pericentric inversions, variation in the amount of euchromatin, and variation in number and kind of supernumerary (b) chro ... | 1989 | 2771951 |
| histopathological observations in new and classic models of experimental schistosoma haematobium infections. | the authors present marsh rat holochilus brasiliensis, jirds meriones shawi and m. unguiculatus as new models of schistosoma haematobium infection. histological findings were compared with those of classic models mouse mus and hamster mesocricetus. in new models, embryonated eggs were seen in the stool from 90 days post infestation (dpi) and active disease developed from 117 to 175 dpi. seven out of 10 rodents presented granulomatous and/or chronic cystitis, fibrosis, polyps and urothelial chang ... | 1996 | 8673838 |
| deleterious mutations at the mitochondrial nd3 gene in south american marsh rats (holochilus). | statistical analyses of dna sequences have revealed patterns of nonneutral evolution in mitochondrial dna of mice, humans, and drosophila. here we report patterns of mitochondrial sequence evolution in south american marsh rats (genus holochilus). we sequenced the complete mitochondrial nd3 gene in 82 holochilus brasiliensis and 21 h. vulpinus to test the neutral prediction that the ratio of nonsynonymous to synonymous nucleotide changes is the same within and between species. within h. brasilie ... | 1998 | 9725852 |
| newly recognized hantaviruses associated with hantavirus pulmonary syndrome in northern brazil: partial genetic characterization of viruses and serologic implication of likely reservoirs. | following the occurrence of the first laboratory-confirmed cases of hantavirus pulmonary syndrome (hps) in maranhao state, brazil, rodents were trapped and rodent materials screened by elisa for antibodies to sin nombre and andes hantaviruses. antibody-positive samples were tested by rt-pcr, amplified products were sequenced, and phylogenetic trees were constructed for comparison with known hantaviruses. from 104 rodent blood samples collected (40 bolomys lasiurus, 52 holochilus sciureus, 12 oli ... | 2005 | 15815145 |
| new species boundaries and the diversification history of marsh rat taxa clarifies historical connections among ecologically and geographically distinct wetlands of south america. | taxa with broad geographic ranges that occur in different biomes and exhibit plastic morphological traits and/or adaptations to particular habitats make inferences about species boundaries especially challenging. however, technological and conceptual advances in the generation and analysis of genomic data have advanced the description of biodiversity. here we address the outstanding questions about the delimitation of species in the genus holochilus, a rodent with morphological specializations t ... | 2020 | 33096231 |
| parasitological and histological aspects of holochilus sciureus naturally infected by schistosoma mansoni. | schistosomiasis is a neglected disease that affects millions of people around the world, being common in the state of maranhão. a total of 225 rodents of the holochilus sciureus species from the western lowland maranhão were studied, of which 144 animals (64%) exhibited schistosoma eggs in their feces samples. macroscopic lesions characterized as well-defined whitish areas on the liver and spleen surfaces were observed. histopathological examination revealed multifocal granulomas in the esophagu ... | 2020 | 31618302 |
| spatial and seasonal distribution of holochilus sciureus with schistosoma mansoni infection in an endemic area for schistosomiasis in brazil. | the occurrence of wild rodents in the schistosoma mansoni life cycle may increase the transmission of schistosomiasis and understanding the spatial and seasonal distribution of the natural infection of these reservoirs is essential for the development of more effective control strategies. | 2019 | 31286359 |
| mazzanema n. gen. and mazzanema fortuita n. comb. for longistriata fortuita freitas, lent, and almeida, 1937 (nematoda: heligmonellidae), a parasite of the marsh rat holochilus chacarius (rodentia: cricetidae) from northern argentina. | the species described as longistriata fortuita freitas, lent, and almeida, 1937 is here redescribed from new material collected from the type host, holochilus chacarius balnearum thomas, and the type locality, san martín del tabacal, salta, argentina. neotypes are designed for the species since the type material deposited by the authors is lost. the original description did not include the synlophe or the female and both are here described. several characters of the synlophe as the number of rid ... | 2013 | 23574047 |
| rediscovery and new morphological data on two hassalstrongylus (nematoda: heligmonellidae) coparasitic in the marsh rat holochilus chacarius (rodentia: cricetidae) from argentina. | two species of hassalstrongylus durette-desset, 1971, coparasitic in holochilus chacarius thomas (rodentia, cricetidae) and not recorded since their original description in 1937, were newly found in their type host and locality. hassalstrongylus mazzai (freitas, lent and almeida, 1937) and hassalstrongylus argentinus (freitas, lent and almeida, 1937) were obtained from ho. chacarius from 2 different populations: one from salta province (northwest argentina) and another from chaco province (north ... | 2015 | 26193068 |
| small mammals as hosts of leishmania spp. in a highly endemic area for zoonotic leishmaniasis in north-eastern brazil. | leishmania parasites cause leishmaniasis in humans and animals worldwide. these parasites are transmitted by phlebotomine sand flies, which become infected upon feeding on an infected mammalian host. we assessed the occurrence of leishmania infection in small mammals in an area of cutaneous and visceral leishmaniasis endemicity. | 2013 | 23868744 |