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At least 235 records · Page 13Linked to original sources
PubMed2000

Notes on mites of the family Myobiidae (Acari: Prostigmata) parasitising rodents (Mammalia: Rodentia) in Iran.

Six mite species of the family Myobiidae, Radfordia (Austromyobia)persica sp. n., Radfordia (Austromyobia) merioni Bochkov, Dubinina et Chirov, 1990, Radfordia (Radfordia) acomys Fain et Lukoschus, 1977, Radfordia (Radfordia) affinis (Poppe, 1896), Radfordia (Graphiurobia) dyromys Fain et Lukoschus, 1973, and Myobia (Myobia) murismusculi (Schrank, 1781) were found in Iran on the rodents Gerbillus cheesmani Thomas, Meriones libycus Lichtenstein, Acomys cahirinus (Desmarest), Alus musculus L., Dryomys nitedula (Pallas), and Mus muscullus, respectively. R. (A.) persica is described as a new species from the female, male and tritonymph. The other five myobiid species are new to Iran.

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PubMed2006

Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha).

It has been widely accepted that mammalian females are born with a non-renewing, finite pool of oocytes that will be continuously cleared by atresia, with only a small proportion of them reaching ovulation. Apoptosis regulates this mass germ cell death, especially through the balance between pro- and anti-apoptotic proteins encoded by the BCL-2 gene family. The caviomorph rodent Lagostomus maximus, the South American plains viscacha, displays the highest ovulation rate known for a mammal releasing 400-800 eggs per cycle. We tested the hypothesis that in L. maximus massive polyovulation is a consequence of reduced apoptosis resulting in suppressed follicular atresia. We found that anti-apoptotic BCL-2 gene is markedly expressed in all kind of follicles from primordial to fully mature antral stages in the adult ovary of L. maximus. On the other hand, pro-apoptotic BAX gene showed weak signals or was undetectable by immunohistochemical examination. Western blot against both proteins confirmed immunohistochemical results. Screening for DNA fragmentation by TUNEL assay was conspicuously negative in ovaries from both pregnant and non-pregnant females. In addition, alpha-oestrogen receptor also showed an enhanced expression from primordial stage to fully mature antral follicles. Our results show that natural preferential expression of BCL-2 and restricted BAX expression greatly suppresses apoptosis in the ovary of L. maximus. This prevents the decline of the oocyte reserve by abolishing follicular atresia and enables the highest ovulation rate known for a mammal, 400-800 or more eggs per cycle.

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PubMed2003

Karyotypic analysis in species of the genus Dasyprocta (Rodentia: Dasyproctidae) found in Brazilian Amazon.

A total of 30 animals of the genus Dasyprocta were cytogenetically studied. They belong to the following species: D. prymnolopha (N=20), D. leporina (N=6), D. fuliginosa (N=1) and Dasyprocta sp. (N=3) (Dasyproctidae, Hystricognathi). Cell suspensions were obtained by peripheral blood culture, besides bone marrow and spleen cells, from D. prymnolopha and D. leporina. The diploid number was 64/65 for all samples. The karyotypes showed similarity, and chromosomal polymorphism was not detected by Giemsa conventional staining and G banding. The constitutive heterochromatin distribution at the pericentromeric region of all the chromosomes was similar in all species. D. prymnolopha, D. leporina and Dasyprocta sp. presented variation in the heterochromatical block size at one of the homologues of the A18 pair. D. fuliginosa presented the heterochromatin uniformly distributed in all chromosomes. There was not variation in the NORs pattern in the species studied.

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PubMedDate not supplied

[Infection induced in wild rodents Dasyprocta leporina (Rodentia: Dasyproctidae), with larval eggs of Lagochilascaris minor (Nematoda: Ascarididae)].

Specimens of Dasyprocta leporina (Linnaeus, 1758) were raised out their natural environment. At three to four months of age they were orally inoculated with Lagochilascaris minor (Leiper, 1909) eggs obtained from a native patient. The eggs were incubated for more than 80 days so that it was possible to obtain, by mechanical compression, larvae that could be maintained alive in liquid medium for 48 hours or more. The animals were sacrificed 14-46 days after infection and tangled larva in inflammatory nodules were found in skeletal muscle without foreign body reaction, abscess formation or calcification. The development of the nodules did not seem to affect the hosts. The larvae obtained were similar to those described by SPRENT as the third stage of these helminths. When white mice were inoculated with similar material it was not possible to recuperate larva from their tissues nor were nodules found. Based on these results it is postulated that the helminth does not present a pulmonary cycle and that its development requires an intermediary host.

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PubMedDate not supplied

The susceptibility of wild caught sand flies to infection by a subspecies of Leishmania mexicana isolated from Proechimys iheringi denigratus (Rodentia, Echimyidae).

Several species of wild caught sand flies were collected in the same site where a subspecies of Leishmania mexicana was isolated from the rodent Proechimys iheringi denigratus. The absence of natural infection in these sand flies permitted us to test, with relative assurance, the susceptibility of wild caught females to infection by this parasite. The success obtained in these experimental infections suggest that one or more of the sand fly species encountered in high numbers in the same site where the infected rodents were captured may be the vector(s) of this subspecies of L. mexicana.

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PubMedDate not supplied

A new host of Trypanosoma cruzi from Jujuy, Argentina: Octodontomys gliroides (Gervais & D'Orbigny, 1844) (Rodentia, Octodontidae).

To identify wild hosts of Trypanosoma cruzi, surveys were conducted in the subandean valleys of Jujuy Province, Argentina, between June 1986 and March 1987. Seventy two mammals from 13 different species were examined by xenodiagnosis. Fifty two of them were mostly rodents trapped at the localities of Maimará, León and Tilcara, and the remainder had been kept in captivity at the Estación Biológica Experimental, in Jujuy. Trypanosoma cruzi infection was detected only in 2 Octodontomys gliroides (2 pos./8 exam. 25%) from all 72 examined mammals. Isolates were called Octodontomys Argentina 1 and 2 (OA1 and OA2). Both infected animals were caught at the archaelogical ruin of Pucará, at Tilcara. Repeated searches for triatomines in the ruin itself and in neighbour houses rendered negative results. Groups of mice inoculated with either OA1 or OA2 isolates became infected between 7 (OA1) to 12 days (OA2) postinoculation PI. Parasitemia peaks were observed between day 12th-14th PI. Scarce amastigote nests were found in myocardium and skeletal muscle. Mortality was observed only for mice inoculated with OA1. Isoenzyme patterns of OA1 and OA2 were identical to one found in dogs and slightly different from that of human parasites in Argentina. Bones from Octodontomys sp., were recently found in a cave, dated 10200-8600 BC, in Pumamarca, near Tilcara, Jujuy. There are evidences that O. gliroides cohabited with man in ancient times and was associated to the domestic cycle of T. cruzi transmission, playing a role like that of domestic caves in Bolivia.

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PubMed2004

Infection of Calomys callosus (Rodentia Cricetidae) with strains of different Trypanosoma cruzi biodemes: pathogenicity, histotropism, and fibrosis induction.

The influence of different Trypanosoma cruzi biodemes on the evolution of the infection and on the histopathological lesions of the heart and skeletal muscles, during the experimental infection of Calomys callosus, was investigated. Three groups of C. callosus were infected, respectively, with parasite strains representative of three different Biodemes: Type I (Y strain), Type II (21 SF strain), and Type III (Colombian strain). For each group, normal C. callosus were also used as controls. Marked differences have been detected in the responses of C. callosus to the infection with the three strains in this model. The strains Types I and II (Y and 21 SF) determined moderate lesions, mostly in the myocardium, with low parasitism, a rapid course, and total regression of the lesions by the 60th day of infection. Differently, Type III strain (Colombian), was more pathogenic for C. callosus and induced necrotic-inflammatory lesions in skeletal muscles and myocardium, in correspondence to intracellular parasitism. Proliferation of fibroblasts and amorphous matrix deposits, followed by interstitial fibrosis were present. Progressive regression of the inflammatory changes and collagen deposits occurred spontaneously. The progression and regression of both inflammation and fibrosis induced by the Colombian strain were further submitted to quantitative evaluation by morphometry. Results of the morphometric studies presented good correlation with the histopathological findings. The results confirm the importance of the different biodemes in the determination of tissue lesions and the peculiarities of response of C. callosus to infection with T. cruzi.

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PubMed2005

Maintenance and breeding of Thrichomys (Trouessart, 1880) (Rodentia: Echimyidae) in captivity.

South American histricognath rodents Thrichomys apereoides laurentius and Thrichomys pachyurus are natural hosts of Trypanosoma cruzi, agent of Chagas disease. We established breeding colonies of these species to serve as experimental models in various parasitological studies. Both species of Thrichomys have all the requirements necessary to become excellent laboratory models: they can be easily maintained in the standard laboratory conditions and breed throughout the year and they do not have any special dietary demands and can be fed by standard food pellets designed for laboratory mice. Both species produce precocious offspring that have their eyes and ears open, teeth erupted, fur well developed, and can eat solid food in the first week of life. T. a. laurentius has larger litter sizes and lower body masses at birth and weaning than T. pachyurus. Moreover, females of T. a. laurentius reach puberty earlier and with lower body mass than T. pachyurus.

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PubMed2006

Caamembecaia gratiosus n. gen., n. sp. (Acari: Trombiculidae), from Trinomys gratiosus (Gunter) (Rodentia: Echimydae), of Atlantic forest in southeastern Brazil.

From June 1999 to May 2001, small mammals were captured in three areas of the Atlantic Forest in Southeastern Brazil and examined for ectoparasites. Analysis of ectoparasites revealed the presence of a new chigger genus and species, Caamembecaia gratiosus, from Trinomys gratiosus. This is the first record of a chigger from T. gratiosus.

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PubMed2002

Spatial use of rodents (Rodentia: Mammalia) host body surface by ectoparasites.

We studied the ectoparasite and the Amblyopinini beetle fauna associated with four small mammal species of the Atlantic Rainforest of Ilha Grande, an island located off the southern Rio de Janeiro State Coast, Southeastern Brazil, analyzing to what extent the parasites were specific to each region of the host body. During the study, a total of 90 individual rodents were captured: 61 Proechimys iheringi Thomas, 1911 (Echymyidae), 22 Sciurus aestuans (Thomas, 1901) (Sciuridae), 4 Oxymycterus sp. (Waterhouse, 1837), and 2 Nectomys squamipes (Brants, 1827) (Sigmodontinae). The data showed that the ectoparasites and Amblyopinini on some rodent hosts in Ilha Grande tend to prefer particular host body sites, and that some ectoparasite species sites may overlap owing to their inaccessibility to the host.

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