Browsing by Author "Fernandez, M"

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    Mate choice in the amphipod Eogammarus oclairi Bousfield: The role of current velocity, random assortment, habitat heterogeneity and male's behavior
    (1996) Iribarne, O; Fernandez, M; Armstrong, D
    Field studies on the mating system of the amphipod Eogammarus oclairi Bousfield in the intertidal shell habitat of Grays Harbor estuary (WA, USA) showed weight assortative mating. There was no spatial difference in the size distribution of individuals, and assortativeness was not affected by habitat complexity. Laboratory experiments showed that males tended to select larger females, and that larger males may either outcompete or take over the females of smaller males. Interaction between a lone, searching male and an amplexing couple was influenced by proximity of the female's moll, the size of the female and size of the intruder male compared to the amplexing male. Males increased the tenacity of their hold on a female during interactions with intruder males as pending female molt grew closer. Among environmental variables, flow velocity up to 30 cm.s(-1) in an artificial flume did not affect males' ability to pair and carry a female. Males were able to remain in amplexus for 24 h with females larger than themselves at this velocity. All evidence suggests that assortative mating is mostly driven by male-male competition and that sexual selection favors large males.
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    Selective depletion of Vβ2+CD8+ T cells in peripheral blood from rheumatic heart disease patients
    (2003) Carrión, F; Fernandez, M; Iruretagoyena, M; Andrade, LEC; Odete-Hilário, M; Figueroa, F
    Acute rheumatic fever (ARF) and its chronic valvular sequelae are the delayed consequence of a pharyngeal infection with group A Streptococcus (GAS). Several GAS proteins have been shown to be superantigens, raising the possibility that the expansion or deletion of T cells expressing specific Vbeta regions might play a role in the pathogenesis of ARF or chronic rheumatic heart disease (RHD). We therefore analyzed by four-color flow cytometry, the V repertoire on CD3, CD4 and CD8 T cells from four ARF patients, 10 RHD patients and also nine healthy controls. A selective depletion of Vbeta2+ T cells was found only in the CD8 subset of chronic RHD patients. This is of interest since a number of GAS superantigens exert their effects on Vbeta2+ cells and because only CD8+ T cells from ARF and RHD patients undergo anergy in response to GAS superantigens. Our results suggests that an ongoing immune process is present in RHD patients and that CD8+ T cells may have an important immunoregulatory role in the pathogenesis of the disease. (C) 2003 Elsevier Science Ltd. All rights reserved.