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At least 667 records · Page 37Linked to original sources
PubMed1991

[Karyotype evolution in the genus Ellobius (Microtinae, Rodentia)].

Comparative analysis was undertaken of the pattern of G-dyed chromosome sets of three Ellobius species: E. tancrei, E. fuscocapillus, E. lutescens with respective diploid chromosome numbers 54, 36, 17. From the data obtained one can envisage probable evolutionary pathway of the Ellobius karyotype. Variability in chromosome numbers of this genus species was shown to be a result of both centromeric and centromeric-telomeric as well as telomeric translocations of originally acrocentric chromosomes. No combinations of acrocentric chromosomes of the E. tancrei Robertsonian fan were found in the karyotypes of E. fuscocapillus and E. lutescens, which points to independence of the evolutionary processes in the Ellobius genus taking different routes. The data are obtained to the effect that evolution of the genus Ellobius was accompanied by increase in the amount of C-heterochromatin.

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PubMed1990

[The B-chromosome system--a marker of Apodemus peninsulae (Rodentia, Muridae) populations in the Baĭkal region].

Karyological studies of 56 Apodemus peninsulae mice from 6 points in the neighbourhood of the Baikal lake revealed both considerable likeness and difference in the variants of the B-chromosomes system of this species. The mice from the regions situated at a distance of 150 kilometers from each other have similar karyotype variants, which allowed to consider these animals as one geographical population. The mice from the south-west, South Pribaikal and south-east regions considerably differ in the variants of the B-chromosomes system and may belong to 3 separate geographical populations.

Animals↗
PubMed1990

[Variability of the cytogenetic structure of Apodemus peninsula (Rodentia, Muridae) population from the West Sayans region].

Karyological investigations of East-Asiatic mice (28 animals) from 5 catching points in the region of West Sayans revealed the presence of 1-12 B-chromosomes in these animals. Nearly all the mice had their individual variant of B-chromosomes system, including combinations of two-shoulder-like chromosomes of different size (from 1 to 5), and also small acrocentric (from 0 to 1) and dot-like B-chromosomes (from 0 to 9). Most frequent were the mice with 5 and 6 (21%) B-chromosomes. The catching points were 120 kilometers from each other, and clinical changes were observed between these points in the direction from the South to the North.

Animals↗
PubMed1989

[Karyotyping of Holochilus venezuelae (Rodentia, Cricetidae)].

We studied the cariotype of Holochilus venezuelae from 28 individuals (14 males and 14 females). Chromosome preparations were obtained by applying colchicine to live animals, followed by hypotonic shock, acetic methanol fixation and Giemsa staining of bone marrow cells. Metaphase configurations were photographed with a M-20 Wild automatic photomicroscope, and 10 karyotype from each animal were prepared from enlarged prints. Idiograms were calculated from the mean length of each chromosome pair and expressed as percentage of the length of the haploid autosome set plus one X chromosome. Results indicate the presence of six karyomorphs and the most frequent karyotype, considered basic for the species, was 2n = 44 (NF = 56), which consists of seven pairs of metacentric chromosomes (five large, one small and one microchromosome), comprising 59.5% of the haplid set; fourteen acrocentric pairs (nine small and five microchromosomes) representing 32.0% of the set; and the sexual pair, which is acrocentric, represent 6% (X) and 2.5% (Y) of the haploid set. The chromosome polymorphisms can be interpreted as the result of Robertsonian changes (fusion) and from the presence of accessory chromosomes (supernumerary). The karyotypical characteristics of the population sample studied suggest the existence of reproductive isolation through chromosomal hybrid sterility with H. brasiliensis (2n = 56 and 2n = 50), which means that H. venezuelae can be considered an allospecie.

Animals↗
PubMed1989

Eimeria lancasterensis (Apicomplexa: Eimeriidae) from the eastern fox squirrel, Sciurus niger (Rodentia: Sciuridae), in north-central Texas.

Eimeria lancasterensis Joseph, 1969, is reported for the first time from the feces of 10 of 11 (91%) eastern fox squirrels, Sciurus niger ludovicianus, in Dallas and Johnson counties, Texas. Oocyst measurements were similar to those reported previously from the eastern gray squirrel, Sciurus carolinensis carolinensis, in Massachusetts. Except for our observation of a substieda body, oocyst morphology was identical to the original description of E. lancasterensis.

Animals↗
PubMed1989

Brachylaima apoplania n. sp. (Digenea: Brachylaimidae) from the Polynesian rat, Rattus exulans (Rodentia: Muridae), in New Zealand: origins and zoogeography.

Brachylaima apoplania n. sp. is described from the small intestine of the Polynesian rat (Rattus exulans) on Tiritiri Matangi Island, New Zealand. The new species is most similar to Brachylaima ratti Baugh, 1962, from Rattus rattus. The two species differ only in morphometric characters, B. apoplania possessing significantly smaller suckers, pharynx, testes, ovary, and cirrus sac. The close resemblance between B. apoplania and B. ratti, the close relationship between their hosts, and archaeological evidence on the origin and early dispersal of R. exulans are used to hypothesize a common Southeast Asian origin for the 2 Brachylaima species. Brachylaima apoplania is believed to have dispersed subsequently throughout the South Pacific islands, along with its rodent host, in the canoes of the ancestors of the modern Polynesians and Maoris.

Animals↗
PubMed1986

[Variability of satellite DNA in 2 groups of field mice (Rodentia, Microtinae)].

Nuclear DNAs of three forms of Microtus juldashi--M. carruthersi (group 1) and of three subspecies of polytypic species Alticola macrotis (group 2) were compared. Intensive interpopulational karyotype differentiation was observed in both groups, particularly, for centromeric heterochromatin quantity and localization. As satellite DNAs (satDNAs) were present in C-heterochromatin of the Rodents groups studied, the latter were used as a model for comparison of the satDNAs in the species in statu nascendi. With this view, the nuclear DNAs were studied by means of the neutral CsCl equilibrium centrifugation. In both groups examined, no correlation was found between the presence, the characteristics of the satDNAs and morphological as well as cytogenetic features of the animals. These results are an indirect confirmation of the idea, according to which satDNA does not possibly play significant role in the development of the reproductive isolation and species formation.

Animals↗
PubMed1987

To the knowledge of the common hamster (Cricetus cricetus Linné, 1758; Rodentia) as host of leptospirosis in Czechoslovakia.

A total of 1288 hamsters (Cricetus cricetus), coming from two regions of Czechoslovakia, were serologically investigated on the presence of leptospirosis. In 1114 hamsters from eastern Slovakia, where an outbreak occurred and local populations lived quite atypically, there was 31.8% positivity, in 174 animals from central Moravia, where the populations were at higher levels but lived normally, the positivity amounted to 17.2%. The serological positivity increases proportionately to the weight, i.e. to the age of the animals. The serovar grippotyphosa was dominant in them (29.6% of examined hamsters), while 6.0% were positive for L. pomona, 1.0% for serovars from the serogroup Sejroe, 0.2% for L. sorex-jalna and L. bataviae respectively, and 0.1% for L. bratislava. The hamsters from central Moravia were positive only for the serovar grippotyphosa. Antibodies in lower titres against L. pomona, having the character of coagglutinations, were simultaneously detected in some hamsters positive for L. grippotyphosa. In Czechoslovakia the common hamster is one of the potential hosts of L. grippotyphosa, its importance increasing during severe outbreaks, when the incidence of infection with L. grippotyphosa in hamster populations increases and the animals inhabit most varied types of biotopes and transfer to synanthropic way of life.

Animals↗
PubMed1985

Coccidian parasites (Apicomplexa: Eimeriidae) of Microtus spp. (Rodentia: Arvicolidae) from the United States, Mexico, and Japan, with descriptions of five new species.

Beginning in July 1980, 149 voles (Microtus spp.) representing 9 species and 14 subspecies collected in Japan, Mexico and the United States were examined for coccidia; 67 (45%) had oocysts in their feces. These included 1 of 3 (33%) M. californicus sactidiegi; 0 of 1 M. longicaudus longicaudus; 0 of 1 M. l. macrurus; 48 of 111 (43%) M. mexicanus including 11 of 26 (42%) M. m. fulviventer, 1 of 2 (50%) M. m. fundatus, 13 of 31 (42%) M. m. mexicanus, 1 of 4 (25%) M. m. mogollonensis and 22 of 48 (46%) M. m. subsimus; 5 of 8 (63%) M. montanus arizonensis; 6 of 6 M. montebelli montebelli; 2 of 4 (50%) M. oregoni oregoni; 5 of 13 (38%) M. pennsylvanicus pennsylvanicus; 0 of 1 M. quasiater and 0 of 1 M. townsendii townsendii. The following coccidians were identified from infected voles: Eimeria saxei n. sp. (syn. E. wenrichi "B") from M. c. sactidiegi; E. ochrogasteri, E. saxei, E. wenrichi (syn. E. wenrichi "A"), and Eimeria sp. from M. m. fulviventer, Eimeria sp. from M. m. fundatus; E. ochrogasteri, E. saxei, Eimeria tolucadensis n. sp., E. wenrichi, and Eimeria sp. from M. m. mexicanus; E. wenrichi from M. m. mogollonensis; Eimeria coahuiliensis n. sp., E. saxei, Eimeria subsimi n. sp., E. wenrichi, Eimeria sp., and Isospora mexicanasubsimi n. sp. from M. m. subsimus; E. tamiasciuri and E. wenrichi from M. m. arizonensis; Eimeria spp. from M. m. montebelli; E. saxei and E. wenrichi from M. o. oregoni; and E. ochrogasteri and E. wenrichi from M. p. pennsylvanicus. Sporulated oocytsts of Eimeria coahuiliensis n. sp. were ellipsoid, 29.6 X 19.6 (27-34 X 18-22) micron with ovoid sporocysts 14.4 X 8.9 (13-18 X 8-10) microns. Sporulated oocysts of Eimeria saxei n. sp. were subspheroid, 13.0 X 11.0 (11-14 X 10-12) micron with ovoid sporocysts 7.5 X 4.0 (6-9 X 4-5) micron. Sporulated oocysts of Eimeria subsimi n. sp. were ovoid/subspheroid, 25.1 X 18.7 (22-28 X 17-21) micron with ellipsoid sporocysts 13.9 X 7.4 (13-15 X 6-8) micron. Sporulated oocysts of Eimeria tolucadensis n. sp. were subspheroid, 25.4 X 20.3 (23-26 X 19-23) micron with ellipsoid sporocysts 11.3 X 7.8 (10-13 X 7-9) micron. Sporulated oocysts of Isospora mexicanasubsimi n. sp. were subspheroid, 23.7 X 23.1 (21-26 X 21-26) micron with ovoid sporocysts 14.9 X 10.8 (12-16 X 10-12) micron.(ABSTRACT TRUNCATED AT 400 WORDS)

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