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PubMed1977

Sex chromosome polymorphism in Oryzomys longicaudatus philippii (Rodentia, Cricetidae).

Oryzomys longicaudatus philippii has a diploid number 2N = 56 (N.F. = 70). A polymorphism of X-chromosomes is described and a duplication as causal mechanism is postulated. The degree of chromosomal differences among the 4 karyological forms of O. longicaudatus and between those forms with O. l. philippii, enable us to postulate the level of full species for all of them.

Animals↗
PubMed1996

Cytogenetic and molecular analysis of the satellite DNA of the genus Ctenomys (Rodentia Octodontidae) from Uruguay.

The genus of subterranean rodents Ctenomys presents the widest range of variability in diploid number among mammals (from 2n = 10 to 2n = 70). In Uruguay, this variability is observed in karyotypes with 2n = 44, 50 or 58 and two geographically isolated populations with 70 chromosomes but different karyotypic structure. The last three populations were analyzed in the present study. They present a satellite DNA, which was isolated from genomic DNA after AluI digestion. In situ hybridization showed that this satellite DNA is located in the centromeric region of a few chromosomes, coincident with Hoechst 33258 staining and C-banding patterns. A similar satellite DNA was detected in Argentinian species of this genus. We established that, in spite of differences in number of positive heterochromatic blocks per karyotype, the C value is the same in the three populations studied. The nature and possible evolutionary path of this repeated DNA is discussed.

Animals↗
PubMed2006

Effect of tunnel inclination on digging energetics in the tuco-tuco, Ctenomys talarum (Rodentia: Ctenomyidae).

Burrows play an important role for many species, providing them with shelter and access to food resources. For subterranean rodents, living underground imposes constraints on morphology and physiology. The convergence in burrow architecture among subterranean rodents has been related to the energy demands imposed by the cost of constructing an entire system. The low frequency of tunnels with downward angles steeper than 40 degrees appears to be a common feature in burrow design. In the subterranean habitat, movements through the soil are expensive and gravity can exert important restrictions on digging energetics when individuals push out the soil removed in steeper digging angles. The aim of this study was to determine the effect of digging angle on digging energetics in Ctenomys talarum. The mass of the removed soil and burrowing speed were similar while digging metabolic rate and net cost of transport were higher in individuals digging in tunnels with angles >40 degrees than in those digging tunnels with angles <40 degrees . The cost of constructing a burrow in the horizontal plane differed by 20% from others in which the natural representation of tunnels >40 degrees was considered. Even given that tunnels >40 degrees represented only 6% of the total burrow length, burrow architecture appears to be constrained by the high energetic cost of constructing in steeper angles.

Animals↗