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At least 829 records · Page 46Linked to original sources
PubMed1998

Karyotype and chromosomal polymorphism of an undescribed Akodon from Central Brazil, a species with the lowest known diploid chromosome number in rodents.

The diploid chromosome number of 2n = 10 found in a new species of Akodon (Cricetidae, Rodentia) from two localities of the state of Mato Grosso, Central Brazil, represents the lowest chromosome number known for rodents. One female with nine chromosomes due to sex chromosome monosomy (2n = 9,XO) was also found. The karyotype comprises two large metacentric pairs (1 and 2); one large polymorphic pair (3), which could be acrocentric, submetacentric, or heterozygous as a result of a pericentric inversion; and one minute metacentric pair (4). The sex determination is of the XX/XY type. CBG, GTG, and RBG banding patterns, Ag-NORs, and meiotic data are presented. Fluorescence in situ hybridization with a (TTAGGG)7 repeat as a probe revealed interstitial telomeric bands (ITBs) in two of the large pairs.

Animals↗
PubMed2002

"Ag-NORs" are not always true NORs: new evidence in mammals.

In spite of uncertainty about the biochemical processes involved, silver staining is a widely used technique for assessing the locations of active NORs in eukaryotic genomes in general, and in mammalian genomes in particular. However, following a previous study of hedgehog chromosomes, we present here a second example from two gerbil species (Rodentia, Muridae), which have several clear Ag-positive signals that do not correspond to 28S rDNA clusters. Although this pattern may be characteristic of particular genomes displaying unusual heterochromatic features, our study casts doubt upon the reliability and universality of Ag-staining for detecting active NORs.

Animals↗
PubMed1996

Discovery of mammalian hosts to Gnathostoma nipponicum larvae and prevalence of the larvae in rodents and insectivores.

From September 1993 to November 1995, to clarify the natural infection of Gnathostoma nipponicum (G.n.) larvae in small wild mammals, a total of 313 animals consisted of three species of rodents and two species of insectivores, collected from an endemic area of this nematode in Aomori Prefecture, were investigated. Two species, Rattus norvegicus (R.n.) and Chimarrogale himalayica (C.h.) were infected with G.n. larvae, and the infection rate was extremely high with 27.2% and 72.7% in the former and latter. The infected animals harbored the larvae of 2-10 (mean: 6.0) in R.N. and 2-40 (10.6) in C.h., and a total of 273 larvae was recovered. The all larvae (18) from R.n. and the vast majority of the larvae (216/255: 82.4%) from C.h. were recovered from the musculature, and many encapsulated larvae were found in these portions of C.h. Taxonomically, all the larvae were identified as the advance third-stage larvae (AdL3) of G.n. The body length was 1,056-2,110 microns, and was larger than those of the naturally-infected AdL3 reported from cold-blooded animals. No morphological alterations or death of the larva was observed. From these results, it would seem that R.n. and C.h. are highly susceptible to G.n. larvae, and has very suitable characteristics as the hosts. Furthermore, a hypothesis is advanced that these mammals serves as the plausible paratenic hosts in the life cycle of G.n. This report is the first record of R.n. (Rodentia) and C.h. (Insectivora) naturally-infected with AdL3 of G.n.

Animals↗
PubMed1999

The prevalence of Balantidium coli infection in fifty-six mammalian species.

A total of 375 fecal samples of 56 mammalian species belonging to 17 families of 4 orders were examined for the detection of Balantidium coli from December 1994 to August 1995. As a result, B. coli was found from 6 species belonging to 4 families of 2 orders (Primates and Artiodactyla) of host animals examined. White-handed gibbon (Hylobates lar), squirrel monkey (Saimiri sciurea) and Japanese macaque (Macaca fuscata) were new hosts for B. coli. All the wild boar (Sus scrofa) and chimpanzee (Pan troglodytes) examined were positive. The highest number of B. coli was obtained from a chimpanzee (1,230/g feces). No B. coli was detected from the animals of orders Rodentia and Carnivora including dogs and cats. The rarity of B. coli infection in breeding animals in Japan. suggests that there is no serious problem in controlling infections.

Animals↗
PubMedDate not supplied

Calomys callosus: an alternative model to study fibrosis in schistosomiasis mansoni. The pathology of the acute phase.

Twenty Calomys callosus, Rengger, 1830 (Rodentia-Cricetidae) were studied in the early stage of the acute schistosomal mansoni infection (42nd day). The same number of Swiss Webster mice were used as a comparative standard. Liver and intestinal sections, fixed in formalin-Millonig and embedded in paraffin, were stained with hematoxilin and eosin, PAS-Alcian Blue, pH = 1.0 and 2.5, Lennert's Giemsa, Picrosirius plus polarization microscopy, Periodic acid methanamine silver, Gomori's silver reticulin and resorcin-fuchsin. Immunohistological study (indirect immunofluorescence and peroxidase labeled extravidin-biotin methods) was done with antibodies specific to pro-collagen III, fibronectin, elastin, condroitin-sulfate, tenascin, alpha smooth muscle actin, vimentin and desmin. The hepatic granulomas were small, reaching only 27% of the volume of the hepatic Swiss Webster granuloma. They were composed mainly by large immature macrophages, often filled by schistosomal pigment, characterizing an exsudative-macrophage granuloma type. The granulomas were situated in the parenchyma and in the portal space. They were often intravascular, poor of extracellular matrix components, except fibronectin and presented, sometimes alpha smooth muscle actin and vimentin positive cells. The C. callosus intestinal granulomas were similar to Swiss Webster, showing predominance of macrophages. Therefore, the C. callosus acquire very well the Schistosoma mansoni infection, without developing strong hepatic acute granulomatous reaction, suggesting lack of histopathological signs of hypersensitivity.

Acute Disease↗
PubMed1998

Effects of schistosomal mansoni infection on Calomys callosus coelom-associated lymphomyeloid tissue (milky spots).

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 brightfield 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.

Animals↗
PubMed2006

Circadian chronotypes among wild-captured west Andean octodontids.

Rest activity pattern was studied in wild-captured males of Octodon degus (n=9), Octodon bridgesi (n=3), and Spalacopus cyanus (n=6) (Rodentia: Octodontidae). Ten-minute resolution actograms were constructed from data obtained by an automated acquisition system. After two months of habituation to a stable light-dark schedule, recordings were performed in isolation chambers under a 12: 12 Light Dark schedule. A free-running period (constant darkness) was recorded for O. bridgesi and S. cyanus. O. degus displayed a crepuscular pattern of rest activity rhythm. Entrained O. bridgesi and S. cyanus displayed nocturnal preference, with rest anticipating light phase and without crepuscular activity bouts. Under constant darkness, active phase occurred at subjective night in O. bridgesi and S. cyanus. Wild-captured O. bridgesi and S. cyanus possess a circadian driven nocturnal preference, while wild O. degus displays a crepuscular profile. Diurnal active phase preference of wild S. cyanus colonies observed in the field could not be explained solely by photic entrainment, since social and/or masking processes appear to be operative. The genus Octodon includes species with diverse chronotypes. We propose that crepuscular diurnal pattern observed in O. degus is a recent acquisition among the octodontid lineage.

Adaptation, Physiological↗
PubMed1976

Trypanosomes of small mammals in Iran.

Trypanosomes in the subgenera Herpetosoma, Schizotrypanom and Megatrypanum were found in 31 small mammals representing nine species of the orders Rodentia, Insectivora and Chiroptera in Iran.

Animals↗
PubMed1996

Serological survey of small mammals in a vesicular stomatitis virus enzootic area.

Small mammals were captured in a Costa Rican dairy farm located in a vesicular stomatitis virus (VSV) enzootic focus, in order to determine which species were naturally infected by this virus. Monthly captures were performed from March 1989 to February 1990. Eighty-four individuals belonging to the orders Rodentia (n = 52), Insectivora (n = 31) and Marsupialia (n = 1) were captured. Only Sigmodon hispidus had neutralizing antibodies to VSV; among 21 animals, six had antibodies to Indiana, one to New Jersey, and two to both serotypes. In addition, groups of 40 sentinel mice (Mus musculus, strain C3H) were placed in cages distributed throughout the farm. Each group was exposed for 1 mo over a period of 1 yr. None of 312 sentinel mice developed antibodies against either VSV serotype. Based on these results, we believe that S. hispidus might be part of the natural cycle of VSV in this enzootic focus. Caged Mus musculus do not seem appropriate for monitoring VSV activity in this area.

Animals↗
PubMed1998

Small mammal survival and trapability in mark-recapture monitoring programs for hantavirus.

Following the 1993 hantavirus pulmonary syndrome (HPS) epidemic in the south-western United States, mammalogists and epidemiologists instituted long-term studies to monitor population density and prevalence of infection in rodents which constitute the reservoir for Sin Nombre virus (SNV). In this study, field techniques used in sampling small mammals for SNV infection were evaluated to determine if trapping and handling protocols were having significant effects on future trapability or mortality of animals. We compared rodent mark-recapture control plots, on which all rodents were simply measured, marked, and released on site, with experimental plots on which all animals were anesthetized with methoxyflurane, sampled for blood and saliva, measured, marked, and released. Blood samples were obtained from anesthetized animals on the experimental plots via a retro-orbital sinus puncture using a heparinized capillary tube. Dacron tipped oral swabs were used to collect buccal cells and saliva from the rodent's oral cavity. Field data were collected monthly from August 1994 to August 1996 at two sites in New Mexico (USA). Analyses were based on 3,661 captures of 1,513 individuals representing 21 species from three rodent families (Rodentia: Muridae, Heteromyidae, Sciuridae) and two species of rabbits (Lagomorpha: Leporidae). Overall, for most murid rodents (including five Peromyscus spp., Neotoma albigula, and Onychomys leucogaster) and one rabbit species (Sylvilagus floridanus), the handling/bleeding procedures had no significant effects on recapture rates or mortality. In contrast, several species of heteromyids (Dipodomys ordii and Perognathus flavus), one murid (Reithrodontomys megalotis) and one leporid (S. auduboni) suffered higher mortality rates, and heteromyid kangaroo rats (D. ordii and D. merriami) exhibited lower trapability as a result of the anesthesia and sampling procedures. In view of the overall non-significant influence of the sampling procedures on murid rodents, the anesthesia and blood/saliva sampling protocols described herein appear to be appropriate for hantavirus research, and may serve as a model for environmental monitoring of other zoonotic agents and their reservoirs.

Animal Welfare↗
PubMed1998

Acute filariasis in a springhaas.

A 2-yr old Springhaas (Pedetes capensis; Pedetidae, Rodentia) imported into the USA from the Republic of South Africa was severely debilitated as the result of abberant migrations of adult Filaria versterae (Filarioidea: Filariidae) normally confined to the subcutaneous tissues of this host in Africa. Some nematodes invaded the peritoneal and thoracic cavities, the pericardial sac and the lungs. Invasion of the lungs resulted in life-threatening respiratory distress necessitating euthanasia. Filaria versterae is redescribed.

Animals↗
PubMed1975

[Study of the correlations between the volumes of the hypophysis, the epiphysis and the subfornical organ to the somatic weight and the volume of the hypothalamus in rodents].

The correlations between volume of the hypophysis, of the epiphysis and of the subfornical organ to body weight and volume of the hypothalamus were studied on 193 rodents belonging to 41 species. Concerning the volume of the hypophyseal lobes the regression slopes of Rodentia occupy an intermediate position between those of Isectivora and Prosimians studied by BAUCHOT. The volume of the epiphysis increases more rapidly with the weight of the body than that of the hypophyseal lobes, the volume of the subfornical organ increases on the contrary more slowly.

Africa↗
PubMed1991

Lung and hearth nematodes in some Spanish mammals.

Thirteen host species belonging to the orders Rodentia, Insectivora and Carnivora from various localities in Galicia (NW Spain) were examined for heart and lung parasites. The following species were found: Parastrongylus dujardini (5.5%) in Apodemus sylvaticus, Crenosoma striatum in Erinaceus europaeus (83%), Angiostrongylus vasorum, Crenosoma vulpis and Eucoleus aerophilus in Vulpes vulpes (3, 3.46 and 0.50%, respectively), Crenosoma taiga in Putorius putorius (100%) and Crenosoma sp. in Meles meles (25%). In Crocidura russula nematode larvae were found (3.3%). Mus musculus, Rattus norvegicus, Rattus rattus, Talpa caeca, Sorex araneus, Genetta genetta and Canis lupus were not parasitized by lung or heart parasites.

Animals↗
PubMed1991

[The genetic classification of the Pasteurella pneumotropica complex].

Pasteurella pneumotropica with its biotypes Jawetz and Heyl are the most common bacterial pathogens associated with diseases in rodents. 23 P. pneumotropica biotype Jawetz, biotype Heyl and P. pneumotropica-like rodentia isolates have been investigated phenotypically by characterization of their micromorphology and biochemical fermentation reactions. The taxonomic position within the family Pasteurellaceae has been examined by DNA:DNA hybridisation (optical method). It could be shown that P. pneumotropica biotype Jawetz represents a genus-like cluster containing several species including the V-factor dependent Haemophilus Taxon B and the avian P. pneumotropica-like organism and therefore resembles a new species of the new genus. It is concluded that the biotype Heyl of P. pneumotropica taxonomically remains as a species within the family Pasteurellaceae, however without further relationship to other known genera or genus-like groups.

Animals↗
PubMedDate not supplied

[Seasonal changes in the brain and skull sizes of small mammals].

A comparative study of seasonal-age dynamics of brain size in six small mammal species, Clethrionomys glareolus, C. rutilus, Microtus oeconomus, M. gregalis (Rodentia); Sorex araneus, S. minutis (Insectivora) has been carried out. The analysis of seasonal changes in brain weight confirms the existence of autumn-winter regression of brain weight, which takes place at the organism level. The regression is less pronounced in voles than in shrews. The decrease in brain weight both in voles and in shrews is accompanied by the decrease in height (capacity) of brain capsule of cranium. In spring the brain weight increase and reaches its maximal specific values in wintered voles in summer. In wintered shrews the brain weight never reaches the value, inherent in young animals before winter regression. The analysis of the data obtained and published data on variability of craniometric features allowed to conclude that seasonal changes in brain size, accompanied by the changes in capacity of cranium capsule might be considered as a general pattern for a large group of palearctic and nonarctic species of small mammals.

Animals↗
PubMed1986

Comparative aspects of mammalian spermiogenesis.

The testes of some different orders of eutherian mammals were examined by conventional electron microscopy with respect to their pattern of spermiogenesis. In addition, some of the testes were studied by cytochemical methods for demonstration of certain nuclear proteins and of glycoproteins in the acrosome and the plasma membrane of spermatids. It was found that although the basic pattern of spermiogenesis was similar in all species studied, there were pronounced dissimilarities in the final shape of the spermatids. Differences were also observed in the timing of the differentiation of several organelles. The head of late spermatids and spermatozoa of Primates, Carnivora and Perissodactyla was cone-shaped, whereas in Artiodactyla and Lagomorpha it was flattened or paddle-shaped, and in Rodentia hook-shaped. The size and shape of the acrosome varied considerably between the orders, as did the length of the middle piece.

Animals↗
PubMed1973

Comparative studies of retinol transport in plasma.

The comparative immunology and biochemistry of plasma retinol transport were studied using radioimmunoassays previously developed for human and for rat retinol-binding protein (RBP). Serum or plasma from 25 species of verebrates, from the mammalian orders Primates, Artiodactyla, Perissodactyla, Carnivora, and Rodentia and from the classes Aves, Amphibia, and Pisces, were assayed. There was a high degree of immunological specificity within a given mammalian order. Sera from seven subhuman primate species tested reacted in the human RBP immunoassay, and sera from four of five rodents reacted in the rat RBP immunoassay. Primate sera failed to react in the rat RBP immunoassay, and rodent sera failed to react in the human RBP immunoassay. Except for a slight reactivity of canine serum in the human RBP immunoassay, other sera showed no immunoreactivity. Using gel filtration, apparent molecular weights were estimated at 60,000-80,000 for the retinol transport systems in whole serum from cow, swine, chicken, and dog. Canine RBP was isolated and partially characterized. Purified canine RBP was generally similar to human and rat RBP with regard to molecular weight (approximately 20,000) and other properties. In plasma, canine RBP circulates as a protein-protein complex of higher apparent molecular weight. The complex remains to be characterized. These data suggest that mammals in general have a retinol transport system similar to the human and rat transport systems but that immunologically important differences in RBP occur among mammalian orders.

Amphibians↗
PubMed1984

[Comparative anatomical studies of the vomeronasal complex and the rostral palate of various mammals. I].

The anatomy of the vomeronasal complex and, in connection with this, the structures of the rostral palate were studied in different species of mammals, namely members of the order Marsupialia, Scandentia, Insectivora, Primates, Rodentia, and Lagomorpha. The following results were obtained: The organs of Jacobson of all forms studied are well-developed. The organ of Jacobson is situated at the base of the nasal septum and opens rostrally, always closely connected to the nasopalatine duct. Even in rodents, lagomorphs and Solenodon, where the openings of the organs are positioned rostral to the ductus, both systems are nevertheless connected by means of special furrows. Accordingly the organs of Jacobson are functionally much more closely related to the oral cavity than to the nasal cavity, which they actually belong to. This can be emphasized by the peculiar structures of the rostral palate inclosing the papilla palatina and with it the oral openings of the nasopalatine ducts. In all species studied, the anterior part of the upper jaw presents a very interesting situation because the median furrow of the rhinarium communicates directly or indirectly with the sulcus papillae palatinae, thus forming a very distinct system of grooves which preserves a connection between the nasopalatine ducts and the preoral surroundings. In rodents, lagomorphs, and Solenodon, we find in this part of the palate a special situation because of their unusually arranged incisors, which are not separated by a diastema. However, also in these cases, there are distinct connecting passages between the papilla palatina and the extraoral surroundings. The conditions found in Ratufa bicolor and in early stages of the rat demonstrate that the extraordinary topography of the rostral palate in rodents is a secondary formation by means of ontogeny and phylogeny. Cebus apella, a platyrrhine simian, shows already a clear reduction of palatal structures compared to those found in prosimians. In Setifer setosus and Echinops telfairi, we find the papilla palatina and with it the oral openings of the nasopalatine ducts overgrown by a bipartite caudal branch of the rhinarium. The neonate Setifer allows us to reconstruct the mechanism of this overgrowing procedure. We find a similar situation in Erinaceus, where the papilla palatina remains uncovered, however. Because of contradictory bibliographical data, some elements of the vomeronasal complex in mammals needed to be carefully analysed in regard to structure and nomenclature: in many species the paraseptal cartilage bifurcates rostrally into a dorsal and a ventral branch.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗