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At least 73 records · Page 4Linked to original sources
PubMed2004

B chromosomes and developmental homeostasis in the yellow-necked mouse, Apodemus flavicollis (Rodentia, Mammalia): effects on nonmetric traits.

B chromosomes are found in almost all populations of the yellow-necked mouse, Apodemus flavicollis (Rodentia, Mammalia). Their effects on developmental homeostasis in this species were analyzed using morphological nonmetric traits (number of foramina) in a sample of 218 animals from locality Mt Jastrebac in the former Yugoslavia. Variations of the parameters of developmental homeostasis (the degree of fluctuating asymmetry--FA, the number of asymmetrical characters per individual--NA, and the total phenotypic variability--PV) were examined in three groups: in animals without Bs, with one B chromosome, and with more than one B chromosome. Significant differences in the level of FA between groups of animals were found for two characters. Carriers of one B chromosome displayed the highest level of phenotypic variability. Parameters of developmental stability (DS) were monitored in the population in which significant variations in the frequency of animals with Bs (fB) were established during the season earlier. The FA levels for four foramina out of a total of 12 examined followed the changes of frequencies of animals with Bs. Furthermore, a significant seasonal correlation between NA and fB was found. The presence of B does not cause a disturbance of homeostasis in a way that allows changes in homeostasis to be directly related to B chromosome's presence. However, carriers of B react differently to environmental changes than do noncarriers.

Animals↗
PubMedDate not supplied

[Gallegostronglyus ibicensis n. gen., n. sp. (Nematoda: Metastrongylidae), a lung parasite of Mus musculus Linnaeus, 1758 (Rodentia: Muridale) in Ibiza (Balearic Islands) (author's transl)].

Description of Gallegostrongylus ibicensis n. gen., n. sp., a Metastrongyle parasitizing the lungs of Mus musculus Linnaeus, 1758 (Rodentia: Muridae) in Ibiza (Balearic Islands). Gallegostrongylus n. gen. is proposed to include in the Angiostrongylinae the parasites of the lungs of Rodents, with bursal rays of reduced or middle size, dorsal ray consisting of two branches completely separated and located wide apart from each other, and spicules imbricated, arched and winged.

Animals↗
PubMed1990

[Ecoepidemiology of leishmaniasis in Syria. 1. Leishmania major Yakimoff and Schokhor (Kinetoplastida-Trypanosomatidae) infestation of Psammomys obesus Cretzschmar (Rodentia-Gerbillidae)].

During an epidemiological survey of zoonotic cutaneous leishmaniasis in South-West Syria, Leishmania major zymodème MON-26 was isolated from a reservoir host, Psammomys obesus terraesanctae (Rodentia-Gerbillidae). The abundance of this rodent, its close contact with infected villages and the high prevalence of the infection (63,1%) indicate that this is the main reservoir host of oriental sore in the semi desert area of this country.

Animals↗
PubMed1991

Helminthfauna of Microtus (Microtus) cabrerae (Thomas, 1906) (Rodentia: Arvicolidae) in the Iberian peninsula: faunistic and ecological considerations.

Faunistic and ecological study of parasitic helminths of Microtus (Microtus) cabrerae (Thomas, 1906) (Rodentia: Arvicolidae) in the Iberian Peninsula. 70 specimens have been dissected, coming from 8 enclaves located in three Spanish provinces; 6 species of helminths have been detected (1 Digenetic Trematode, 4 Cestodes and 1 Nematode). Structure of helminthfauna of M. (M.) cabrerae in relation to remaining Iberian Arvicolids and the most conditioning ecological factors of the helminthfauna of the Rodent are analyzed.

Animals↗
PubMed1986

Mammary number and litter size in Rodentia: The "one-half rule".

Litter size and mammary number in the mammalian order Rodentia show a significant positive correlation. Mean litter size is typically one-half the number of available mammaries, while maximum litter size approximates mammary number. Similar relationships are found in the families Muridae, Cricetidae, and Sciuridae. The relationship of litter size to mammary number is significantly different between the arboreal and terrestrial squirrels, and between the hystricomorph and nonhystricomorph rodents. Mammary number may have operated as a selective constraint on litter size over evolutionary time.

Journal Article↗
PubMed2002

Proliferating cell nuclear antigen (PCNA) expression in tooth primordia in the field vole (Microtus agrestis, Rodentia).

Cell proliferation in developing tooth germs has been studied particularly using bromodeoxyuridine (BrdU) incorporation into growing tooth primordia and by counting and three-dimensional (3D) reconstruction of mitoses in serial sections of developing teeth. PCNA has been proposed as an alternative marker of proliferation activity. The aim of our study was to detect immunohistochemically locations of PCNA-positive cells in developing tooth germs of Microtus agrestis (Rodentia). PCNA expression could be distinguished in oral epithelium and mesenchyme before first signs of dental lamina elevation. During bud, cap, and bell stages, positive immunostaining could be observed at defined sites in enamel organ, tooth papilla, and dental follicle. Rudimental tooth germs of the upper diastema, enamel knots, and inner enamel epithelium at day of ontogeny 18 and 19 showed negative reaction. PCNA marks cycling and early G0 cells and can be used successfully as a proliferation marker even in collection material.

Animals↗
PubMed2003

Evolution of rRNA gene clusters and telomeric repeats during explosive genome repatterning in TATERILLUS X (Rodentia, Gerbillinae).

A survey of 28S and 5S rRNA gene clusters, and telomeric repeats was performed using single and double FISH in the Taterillus genus (Rodentia, Muridae, Gerbillinae). Taterillus was previously demonstrated to have undergone a very recent and extensive chromosomal evolution. Our FISH results demonstrate that rRNA genes can vary in location and number irrespective of the phylogenetic relationships. Telomeric repeats were detected in pericentromeric and interstitial regions of several chromosomes, thus providing nonambiguous evolutionary footprints of Robertsonian and tandem translocation events. These footprints are discussed in reference to the molecular process of these karyotypical changes. Also, examples of colocation of rDNA clusters and telomeric repeats lend support to their possible involvement in nucleolus formation. Finally, the presence of rRNA genes, and the extensive amplification of telomeric repeats at specific loci within a double X-autosome translocated element which were not observed on the homologous Y1 and Y2, served as basis for an epigenomic hypothesis on X-autosome translocation viability in mammals.

Animals↗
PubMed1996

A finding of the XX/XY1Y2 sex-chromosome system in Taterillus arenarius (Gerbillinae, Rodentia) and its phylogenetic implications.

A chromosome banding study (R- and C-bands) of a male Taterillus arenarius (Rodentia, Gerbillinae) specimen from Mauritania revealed the presence of an XX/XY1Y2 sex-chromosome system in the karyotype, as found previously in three other congeneric species. This finding allowed us to resolve the phylogenetic affinities of this species within the genus and to propose an evolutionary scenario leading to the formation of the species with an XX/XY1Y2 sex-chromosome system. A review of chromosome data in Taterillus suggests that there may be more species in the genus than hitherto recognized.

Animals↗
PubMed1989

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 weaning was 84.9%. Mean life span in laboratory conditions was 13.5 months and a cumulative mortality of 90% was reached at 27-28 months of age.

Animal Husbandry↗
PubMedDate not supplied

Experimental infection of Calomys callosus (Rodentia, Cricetidae) by Toxoplasma gondii.

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 10(2) to 10(6) 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.

Animals↗
PubMed2004

Blood and intestinal parasites of squirrels (Rodentia: Sciuridae) in Amazonian Brazil.

We report the result of an examination for blood and intestinal protozoa in 12 specimens of the red squirrel Sciurus spadiceus (Rodentia: Sciuridae) from Birroque, municipality of Placido de Castro, state of Acre, Brazil. No parasites were detected in thin, Giemsa-stained blood films of the animals, but culture of the blood of three in Difco B45 medium blood-agar slants gave rise to isolates of epimastigotes. Inoculation of one isolate into laboratory mice resulted in the appearance of Trypanosoma cruzi-like trypomastigotes in their peripheral blood, and the other two isolates gave rise to transient infections with a T. lewisi-like parasite in inoculated mice and hamsters. The failure of the latter parasite to develop in the triatomine bug Rhodnius robustus suggests that it is probably not T. rangeli. This appears to be the first record of a T. lewisi-like trypanosome in neotropical squirrels. Oocysts of an Eimeria sp., were detected in the faeces of 10 animals (83.3%). The parasite develops in the epithelial cells of the intestine, where it may cause severe damage and sometimes results in death of the animal. No oocysts were detected in bile.

Animals↗
PubMed2005

Habitat use by Oryzomys subflavus (Rodentia) in an open shrubland formation in Restinga de Jurubatiba National Park, RJ, Brazil.

The Restinga de Jurubatiba has at least 10 plant formations, including open Clusia shrubland. This formation is composed of dense shrubs of many shapes and sizes, where Clusia hilariana is one of the most important plant species. Shrublands with Clusia (CC) are poorer in plant species and less dense than shrublands without Clusia (SC). Oryzomys subflavus (Rodentia) is the most abundant small mammal species in the open Clusia shrubland. We tested the hypothesis that the abundance of rodents would increase with the size of the patch and would be higher in SC shrublands. Rodents were captured, marked and released in three 780-m-long transects. At each capture site, we evaluated the shape of the shrubland patch, calculated the area and noted the category of the shrubland. Using ANCOVA, we ascertained whether the abundance of Oryzomys subflavus increased with the sampled area and used CC and SC shrublands differently. We also verified if the size of patches used by rodents varies in the same frequency as the size of available shrublands. Rodent abundance was found to increase significantly with the area. There were no differences in the size of the patches used by rodents and the frequency of the size of available patches. This finding indicates that O. subflavus, in the study area, is a generalist species that uses its habitat according to availability.

Animals↗
PubMed2002

A new species, Litomosoides odilae n. sp (Nematoda: Onchocercidae) from Oligoryzomys nigripes (Rodentia: Muridae) in the rainforest of Misiones, Argentina.

A new species of Litomosoides was collected from the abdominal cavity of Oligoryzomys nigripes (Rodentia: Muridae) in a semideciduous secondary rainforest of Misiones, Argentina. Litomosoides odilae n. sp. belongs to the carinii group and is characterized by the amphids displaced dorsally; buccal capsule with an anterior segment transparent and an annular asymmetrical thickening; esophagus divided, with the posterior glandular portion slightly wider than the muscular; male cloacal aperture strongly protruded; and microfilaria sheathed with an attenuated tail. The morphology of the new species, which is similar to that of L petteri, a parasite of marsupials in Brazil, suggests that host-switching events may have occurred in the diversification of this genus.

Abdominal Cavity↗
PubMed1992

The complement system of Calomys callosus, Rengger, 1830 (Rodentia, Cricetidae).

The complement system (C) of Calomys callosus, Rengger, 1830 (Rodentia, Cricetidae), a wild reservoir for several infectious agents in Latin America, was characterized. Sera from normal adult animals lysed sheep erythrocytes (Es) previously sensitized with rabbit serum anti-Es (Ar) in the presence of veronal-buffered saline containing 0.15 mM CaCl2 and 0.5 mM MgCl2, pH 7.4, or unsensitized rabbit erythrocytes (Er) in the presence of one-half isotonic strength veronal-buffered-saline containing 2.5% glucose, 2 mM MgCl2 and 10 mM EGTA, pH 7.4. Both hemolytic curves were sigmoidal in shape, with CH50 values of 30-40 for females and 20-30 for males. C5, determined hemolytically using the intermediate cells EsArClm4m2m3m, was approximately 4.5 x 10(8)/ml and 4.0 x 10(8)/ml for females and males, respectively. Immunochemical serum analyses by double immunodiffusion or by immunoblotting using polyclonal antisera against human C1s, C1q, C2, C3, C4, C5, C8 and factors B, I and H indicated that C. callosus C components factor B, C4 and C3 cross-reacted with the corresponding human C components. Thus, C. callosus was found to contain effective classical and alternative pathways (CP, AP) and common pathways, reasonable amounts of C5 and common epitopes in the key C components, factor B, C4 and C3, which were preserved during evolution.

Animals↗
PubMed1982

Identification of left-handed Z-DNA by indirect immunomethods in metaphasic chromosomes of a mammal, Gerbillus nigeriae (Gerbillidae, Rodentia).

Antisera and antibodies against Z-DNA were used on metaphasic fixed chromosomes of a mammal, Gerbillus nigeriae (Gerbillidae, Rodentia). By indirect immunofluorescence and indirect immunoperoxidase labelling a heavy staining was detected in a fraction of the R-band positive heterochromatic segments, which are presumed to be rich in G-C base pairs. A weak and non homogeneous staining was also observed on euchromatic segments. The presence of a left-handed Z-DNA in mammalian chromosomes is discussed.

Animals↗
PubMed1998

A new Eimeria species (Apicomplexa: Eimeriidae) infecting Onychomys species (Rodentia: Muridae) in New Mexico and Arizona.

Fecal samples from 3 species of Onychomys (Rodentia: Muridae) captured in New Mexico and Arizona were examined for coccidia. Six of the 59 (10%) were infected with a new species of Eimeria. Sporulated oocysts (n = 105) of this new species are subspheroidal, 17.4 x 16.1 (14-21 x 13-19) microm, with ellipsoidal sporocysts 10.4 x 5.7 (9-12 x 5-8) microm. This species occurred in 3 of 24 (13%) Onychomys arenicola, 2 of 31 (6%) Onychomys leucogaster from New Mexico, and 1 of 4 (25%) Onychomys torridus from Arizona. Isolates recovered from O. leucogaster and O. torridus were inoculated into O. leucogaster (n = 5) and produced infections with a prepatent period of 7 days and a patent period of 7-23 days.

Animals↗
PubMed1996

A tendon-locking mechanism in two climbing rodents, Muscardinus avellanarius and Micromys minutus (Mammalia, Rodentia).

Having compared the microanatomy of the toes of a terrestrial to two climbing species, adaptations were found in the flexor tendons and in the integument. In contrast to Crocidura russula, both Muscardinus avellanarius and Micromys minutus have a tendon-locking mechanism (TLM) that is engaged when the middle phalanx is bent. A ventral thickening of the flexor tendon is situated deep to a thickened portion of the ventral tendon sheath. When twigs or stalks are grasped, the TLM allows less muscular energy to be expended. In C. russula glands are restricted to the terminal pads, but in the climbing species they occur in the sole of the toes as well. In the reed-living M. minutus knob-shaped integumental thickenings, together with the digital pads, stabilize the grip. In contrast the arboreal M. avellanarius often climbs thick branches and shows adaptations for pressing the sole of the feet against the surface. Thereby the tendon attached to the plantar integument of the toes transfers the muscle force directly to the bark. Unlike the other digits on the forefeet of both climbing species, no TLM is present in the anterior digit. In M. minutus this short digit is twisted towards the palm and, with the carpal pads, provides an abutment against the grasping fingers. In M. avellanarius the anterior digit has very thin tendons and is that much reduced in length that it is completely integrated into the digital pad where it acts, at best, as a lateral support of the pad.

Adaptation, Physiological↗