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The adjustment of Calomys callosus (Rodentia, Cricetidae) to food deprivation
Ades, César;Kolde, Renate Edla;
Revista Brasileira de Zoologia , 1989, DOI: 10.1590/S0101-81751989000200005
Abstract: the adjustment of calomys callosus (rodentia, cricetidae) to intermittent food deprivation was investigated. animals subjected either to 24-hr or to 48-hr repeated periods of deprivation successfully compensated, showing (1) increases in post-fast intake relatively to the intake by control animals; (2) rapid recovery of the baseline levels of body wieght. the regulatory ability of c. callosus is comparable, in such respects, to the ability of the common rat and some other rodents but it is remarkably different from the hamster's.
A new species of Calomys Waterhouse (Rodentia, Sigmodontinae)from the Cerrado of Central Brazil
Bonvicino, Cibele R.;Lima, José F. S.;Almeida, Francisca C.;
Revista Brasileira de Zoologia , 2003, DOI: 10.1590/S0101-81752003000200021
Abstract: a new brazilian calomys waterhouse, 1837 species is described based on morphologic and karyologic data. this species is endemic to the cerrado of central brazil and allopatric with all other species of the genus calomys. its chromosome complement (2n = 46, an = 66) is different from those described in other calomys species. morphometric analysis significantly distinguished this new species from other calomys of the brazilian fauna like c. callosus (renger, 1830), c. expulsus (lund, 1841) and c. tener (winge, 1887) and placed it among the large-sized calomys.
A new species of Calomys Waterhouse (Rodentia, Sigmodontinae)from the Cerrado of Central Brazil  [cached]
Bonvicino Cibele R.,Lima José F. S.,Almeida Francisca C.
Revista Brasileira de Zoologia , 2003,
Abstract: A new Brazilian Calomys Waterhouse, 1837 species is described based on morphologic and karyologic data. This species is endemic to the Cerrado of Central Brazil and allopatric with all other species of the genus Calomys. Its chromosome complement (2n = 46, AN = 66) is different from those described in other Calomys species. Morphometric analysis significantly distinguished this new species from other Calomys of the Brazilian fauna like C. callosus (Renger, 1830), C. expulsus (Lund, 1841) and C. tener (Winge, 1887) and placed it among the large-sized Calomys.
Experimental Infection of Calomys callosus (Rodentia, Cricetidae) by Toxoplasma gondii
Favoreto-Junior, Sílvio;AV Ferro, Eloísa;Clemente, Diogo;Silva, Deise AO;Mineo, José R;
Memórias do Instituto Oswaldo Cruz , 1998, DOI: 10.1590/S0074-02761998000100018
Abstract: calomys callosus, rengger 1830 (rodentia, cricetidae), a wild rodent found in central brazil, was studied to investigate its susceptibility to toxoplasma gondii experimental infection and its humoral immune response against this protozoa. the electrophoretic profile of the serum proteins of c. callosus showed that igg, which shows no affinity to protein a, has higher cross reactivity with rat igg than with igg from other rodents. the susceptibility assay was performed by inoculation groups of animals with various suspensions of t. gondii tachyzoites from 102 to 106 parasites. all animals died between 3 and 9 days after infection and the kinetics of antibody synthesis was determined. basically, they recognized predominantly the immunodominant antigen sag-1 (p30). the immunohistochemistry assays revealed that the liver was the most heavily infected organ, followed by the spleen, lungs, intestine, brain and kidneys. it can be concluded that c. callosus is an excellent experimental model for acute phase of toxoplasma infection
Experimental Infection of Calomys callosus (Rodentia, Cricetidae) by Toxoplasma gondii  [cached]
Favoreto-Junior Sílvio,AV Ferro Eloísa,Clemente Diogo,Silva Deise AO
Memórias do Instituto Oswaldo Cruz , 1998,
Abstract: Calomys callosus, Rengger 1830 (Rodentia, Cricetidae), a wild rodent found in Central Brazil, was studied to investigate its susceptibility to Toxoplasma gondii experimental infection and its humoral immune response against this protozoa. The electrophoretic profile of the serum proteins of C. callosus showed that IgG, which shows no affinity to Protein A, has higher cross reactivity with rat IgG than with IgG from other rodents. The susceptibility assay was performed by inoculation groups of animals with various suspensions of T. gondii tachyzoites from 102 to 106 parasites. All animals died between 3 and 9 days after infection and the kinetics of antibody synthesis was determined. Basically, they recognized predominantly the immunodominant antigen SAG-1 (P30). The immunohistochemistry assays revealed that the liver was the most heavily infected organ, followed by the spleen, lungs, intestine, brain and kidneys. It can be concluded that C. callosus is an excellent experimental model for acute phase of Toxoplasma infection
Application of geometric morphometrics to the study of postnatal size and shape changes in the skull of Calomys expulsus
Erika Hingst-Zaher,Leslie Marcus,R. Cerqueira
Hystrix : the Italian Journal of Mammalogy , 2000, DOI: 10.4404/hystrix-11.1-4139
Abstract: We analyzed ontogenetic patterns of landmarks for 169 laboratory-raised specimens of Calomys expulsus, at 0, 5, 10, 20, 30, 50, 100, 200, and 300 days of age, using two-dimensional geometric morphometrics. There is sexual dimorphism in size, with males smaller than females at earlier ages, but larger after 50 days. Differences in shape between sexes are strong only until 10 days of age, suggesting that shape is more constrained than size. Combining sexes, there is strong variation in size with age, reduced after 200 days, while most of the variation in shape occurs before 20 days. This dissociation is common for sigmodontine rodents, and might be the basis of heterochronic processes responsible for the morphological variation of this South American group. Centroid size does not show any reduction in the coefficient of variation over ages, while Procrustes distances within sucessive ages are reduced after 20 days. Uniform component and the more global partial warps explain most of the shape changes with age. Cranial and Facial parts of the skull increase in size at different rates with a relative lengthening of the snout and decrease in height of the braincase. We were unable to detect a clear pattern of integration for the rostrum and braincase, besides that shown by landmark displacements.
Study of the social hierarchy and territoriality of Calomys callosus Rengger, 1830 (Rodentia: Cricetidae)
Póvoa, CP.;Brandeburgo, MAM.;
Brazilian Journal of Biology , 2007, DOI: 10.1590/S1519-69842007000300007
Abstract: the genus calomys comprises a lot of species distributed throughout south america. the species c. callosus rengger, 1830 occur in brazil, been often used in laboratory experiments. this work involved a study of aggressive behavior and dominance, which are aspects related to hierarchy and territoriality, among c. callosus males kept in a laboratory. the establishment of a hierarchy was observed, with the dominant animals controlling the space, food and water, while the remaining animals were confined to a restricted space. the intensity of aggression and variations in the number of attacks declined over time as a result of the formation of the hierarchy. no wounds were observed, probably due to the ritualistic nature of the attacks.
Acquired and Congenital Ocular Toxoplasmosis Experimentally Induced in Calomys callosus (Rodentia, Cricetidae)
Pereira, Maria de Fátima;Silva, Deise Aparecida Oliveira;Ferro, Eloisa Amália Vieira;Mineo, José Roberto;
Memórias do Instituto Oswaldo Cruz , 1999, DOI: 10.1590/S0074-02761999000100021
Abstract: an experimental model for acquired and congenital ocular toxoplasmosis as well as a model to induce experimental autoimmune uveitis (eau) was investigated in calomys callosus. toxoplasma gondii, me-49 strain, was used to infect males and pregnant- and not pregnant-females while s-antigen, a major glycoprotein of the retinal photoreceptor cell, was used to induce eau. the ocular lesions elicited by t. gondii were characterized by the presence of cysts, free tachyzoites and inflammatory cells in the retina or related tissues. in the congenital form, 40% of the fetus presented ocular lesions, i.e., presence of cysts in the retina, vitreous, and extra-retinal tissues. in the acquired form, 75% of the females and 50% of the males presented unilateral ocular cysts both at 21 and 47 days post-infection. it was also demonstrated that s-antigen was not uveitogenic in the c. callosus model. no lesion was observed in the animals exclusively immunized with this retinal component, even when jacalin was used as additional adjuvant for polyclonal response to the retinal antigen. it can be concluded that c. callosus may constitute in a promising model for study both acquired and congenital ocular toxoplasmosis, particularly when it is important to make sure that a non autoimmune process is involved in the genesis of the ocular infection.
Acquired and Congenital Ocular Toxoplasmosis Experimentally Induced in Calomys callosus (Rodentia, Cricetidae)  [cached]
Pereira Maria de Fátima,Silva Deise Aparecida Oliveira,Ferro Eloisa Amália Vieira,Mineo José Roberto
Memórias do Instituto Oswaldo Cruz , 1999,
Abstract: An experimental model for acquired and congenital ocular toxoplasmosis as well as a model to induce experimental autoimmune uveitis (EAU) was investigated in Calomys callosus. Toxoplasma gondii, ME-49 strain, was used to infect males and pregnant- and not pregnant-females while S-antigen, a major glycoprotein of the retinal photoreceptor cell, was used to induce EAU. The ocular lesions elicited by T. gondii were characterized by the presence of cysts, free tachyzoites and inflammatory cells in the retina or related tissues. In the congenital form, 40% of the fetus presented ocular lesions, i.e., presence of cysts in the retina, vitreous, and extra-retinal tissues. In the acquired form, 75% of the females and 50% of the males presented unilateral ocular cysts both at 21 and 47 days post-infection. It was also demonstrated that S-antigen was not uveitogenic in the C. callosus model. No lesion was observed in the animals exclusively immunized with this retinal component, even when jacalin was used as additional adjuvant for polyclonal response to the retinal antigen. It can be concluded that C. callosus may constitute in a promising model for study both acquired and congenital ocular toxoplasmosis, particularly when it is important to make sure that a non autoimmune process is involved in the genesis of the ocular infection.
Effects of Schistosomal mansoni infection on Calomys callosus coelom-associated lymphomyeloid tissue (milky spots)
Lenzi, Jane A;Pelajo-Machado, Marcelo;Mota, Ester M;Oliveira, Denise N;Panasco, M?nica S;Andrade, Zilton A;Lenzi, Henrique L;
Memórias do Instituto Oswaldo Cruz , 1998, DOI: 10.1590/S0074-02761998000700003
Abstract: calomys callosus rengger, 1830 (rodentia: cricetidae) is a mouse-like south american wild rodent, which is permissive to schistosoma mansoni infection. in this paper we studied the effect of schistosomal infection in c. callosus mesenteric and omental milky spots (ms), subsidiary foci of coelom-associated lymphomyeloid tissue (calt), during the acute, transitional (acute to chronic), and chronic phases of the infection. ms were morphologically analyzed by histological methods, using brigthfield and confocal laser scanning microscopies. the ms of infected animals were mainly of lymphomyelocytic (42 to 90 days) and lymphoplasmacytic (160 days of infection) types and showed frequent presence of lymphoid follicles with germinal centers, plasmacytogenesis and plasmacytosis, mastocytosis, megakaryopoiesis, erythropoiesis and less pronounced eosinopoiesis. these results indicate that ms are a preferential site of germinal-center-dependent and independent plasmacytogenesis, and a bone marrow-like organ, committed with various cellular lineages. the consequence of c. callosus ms reactivity for schistosomal infection is still unknown and is under investigation.
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