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Strongyloides myopotami, a parasite of Myocastor coypus (nutria or coypu), was found during an extensive parasitological survey carried out on parasitic helminths of 5 species of subterranean rodents (tuco-tucos) belonging to the genus Ctenomys from Argentina and Uruguay. Strongyloides myopotami became known by causing “marsh itch” (also called “nutria itch” or “swimmer’s itch”), a severe rash caused by larvae that enter the skin in humans, and it is recognised as a zoonosis for people handling nutria fur. In the present study S. myopotami was found in 2 of the 5 examined species of Ctenomys (C. talarum from Argentina and C. pearsoni from Uruguay), both inhabiting the vicinity of water courses. Population descriptors of S. myopotami in C. talarum showed that a population of this parasite is well established in this rodent. The development of infective filariform larvae from eggs in the faeces of C. talarum and the prevalence of gravid parasitic females in this host can be considered as evidence of the establishment of a population of S. myopotami independent of the source population parasitizing M. coypus. Therefore, the presence of S. myopotami in these species of tuco-tucos indicates a change from a semi-aquatic to subterranean life cycle. Evidence that tuco-tucos are reservoirs for these nematodes and therefore may be a risk to human health in the areas studied is provided.
We analysed the physical structure and functional interpretation of juvenile vocaliza­tions of Ctenomys talarum Thomas, 1898. Two sounds, one true vocalization (care- -elicitation call) and one mechanical sound (nursing sound) were recorded during the nestling period. Care-elicitation calls were emitted by isolated pups and caused the mother to respond by immediately approaching the pups to take care of them. This maternal response to the care-elicitation calls of C. talarum pups, together with the production of these vocalizations during the first weeks after birth, when pups depend exclusively on their mother to obtain food and maintain their body temperature, give preliminary support for the recent theory that care-elicitation cries are honest adver­tisements of offspring need.
The tuco-tucoCtenomys talarum Thomas, 1898 is a solitary subterranean rodent that breeds seasonally in coastal sand-dune grasslands from Argentina. We assessed whether short-day photoperiod determines the onset of reproduction by an increase in female’s receptivity and whether male odour interacts with photoperiod as a cue by producing a greater response in receptivity. Receptivity was measured by an increase in the percentage of vaginal epithelial cells, particularly cornified cells. Females were trapped during their non-reproductive season (summer-long days) and randomly assigned to different day-length experimental groups: constant summer (CS), early winter (EW), and natural (NA) photoperiod. We examined the vaginal epithelium using vaginal smears during the first experimental phase (120 days) to test the effect of photoperiod. In the second experimental phase (15 days), we presented the females with male-soiled shavings to test the effect of photoperiod and male odor.Ctenomys talarum females showed some evidence of reproductive responsiveness to photoperiodic cuing. The proportion of epithelial cells peaked earlier in females when winter day-length was advanced than in females under natural photoperiod. Contrary to that expected, male odours did not stimulate female receptivity. These results suggest that, while photoperiod may participate in regulating reproduction, the integration of other environmental and social factors, as well as the identification of bodily conditions that lead to differences in individual response needs further consideration.
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