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41.
Aguilar-Rojas A Almaraz-Barrera Mde J Krzeminski M Robles-Flores M Hernández-Rivas R Guillén N Maroun RC Vargas M 《Experimental parasitology》2005,109(3):150-162
The molecular, biochemical, and cellular characterization of EhGEF1 protein is described. Complete cDNA sequence of 1890 bp revealed an open reading frame that encodes a protein of 69 kDa. EhGEF1 is constituted of Dbl homology domain, pleckstrin homology domain, and several putative regulation sites. Studies of guanine nucleotide exchange activity of EhGEF1 on several GTPases from Entamoeba histolytica and Homo sapiens showed preferential activation on EhRacG, suggesting that EhGEF1 protein could be involved in mechanisms related to actin cytoskeleton activation, cytokinesis, capping, and uroid formation in trophozoite. Confocal microscopy studies of pExEhNeo/HSV-tagged-EhGEF1-transfected cells showed that trophozoites stimulated with ConA, EhGEF1, and EhRacG were localized at plasma membrane. Cellular studies showed that F-actin content of pExEhNeo/HSV-tagged-EhGEF1-transfected trophozoites as well as cellular migration and cell damage capacity were significantly altered. The observations suggest that EhRacG was the principal target of EhGEF1 and that EhGEF1 may provide a link between F-actin dynamics and EhRacG signaling. 相似文献
42.
Maria Elena Hernandez Abraham Soto-Cid Gonzalo E Aranda-Abreu Rosaura Díaz Fausto Rojas Luis I Garcia Rebeca Toledo Jorge Manzo 《Reproductive biology and endocrinology : RB&E》2007,5(1):11-9
Background
The prostate is a sexual gland that produces important substances for the potency of sperm to fertilize eggs within the female reproductive tract, and is under complex endocrine control. Taking advantage of the peculiar behavioral pattern of copulating male rats, we developed experimental paradigms to determine the influence of sexual behavior on the level of serum testosterone, prostate androgen receptors, and mRNA for androgen receptors in male rats displaying up to four consecutive ejaculations. 相似文献43.
G. F. Grether J. Hudon D. F. Millie 《Proceedings. Biological sciences / The Royal Society》1999,266(1426):1317
Carotenoids produce most of the brilliant orange and yellow colours seen in animals, but animals cannot synthesize these pigments and must rely on dietary sources. The idea that carotenoids make good signals because they are a scarce limiting resource was proposed two decades ago and has become the leading hypothesis for the role of carotenoids in animal communication. To our knowledge, until now, however, there has been no direct evidence that carotenoids are a limiting resource in nature. We showed that carotenoid availability in the wild limits the expression of sexual coloration in guppies (Poecilia reticulata), a species in which females prefer males with brighter orange carotenoid-containing spots. Further, the degree of carotenoid limitation varies geographically along a replicated environmental gradient (rainforest canopy cover), which opens new avenues for testing signal evolution theory. 相似文献
44.
Adriana Casao Igor Cebrián Mayra Eoda Asumpção Rosaura Pérez-Pé José A Abecia Fernando Forcada José A Cebrián-Pérez Teresa Muiño-Blanco 《Reproductive biology and endocrinology : RB&E》2010,8(1):59
Background
Some breeds of sheep are highly seasonal in terms of reproductive capability, and these changes are regulated by photoperiod and melatonin secretion. These changes affect the reproductive performance of rams, impairing semen quality and modifying hormonal profiles. Also, the antioxidant defence systems seem to be modulated by melatonin secretion, and shows seasonal variations. The aim of this study was to investigate the presence of melatonin and testosterone in ram seminal plasma and their variations between the breeding and non-breeding seasons. In addition, we analyzed the possible correlations between these hormones and the antioxidant enzyme defence system activity. 相似文献45.
Dilia Martínez Méndez Rosaura Hernández Valles Primavera Alvarado Mireya Mendoza 《Revista iberoamericana de micología》2013,30(1):39-46
BackgroundIn 1984 the Venezuelan Work Groups in Mycology (VWGM) were created introducing an innovative approach to the study of the mycoses in Venezuela.AimTo study the occurrence of the mycoses in Venezuela.MethodsReview the reported cases of mycoses by the newsletter Boletín Informativo Las Micosis en Venezuela (VWGM) from 1984 to 2010.ResultsThe data collected showed 36,968 reported cases of superficial mycoses, 1,989 of deep systemic cases, and 822 of localized mycoses. Pityriasis dermatophytosis was the most common superficial infection, and paracoccidioidomycosis and histoplasmosis the most frequent deep systemic infection. Chromoblastomycosis was the most frequently diagnosed subcutaneous infection. The data provided showed the distribution by geographical area for each of the fungal infections studied, which may help to establish the endemic areas.DiscussionSuperficial mycosis is a public health problem due to its high morbidity and is probably responsible for some of the outbreaks in high-risk groups. Paracoccidioidomycosis and histoplasmosis were reported more often, which agrees with earlier reports prior to the formation of the VWGM. Cases of sporotrichosis and chromoblastomycosis in Venezuela can be considered unique due to the high number of cases. This study highlights the contribution of the VWGM to the behavior of the mycoses in Venezuela, its incidence, prevalence, and the recognition of these infections as a problem of public health importance. The VWGM should keep working in this endeavor, not only reporting new cases, but also unifying the clinical and epidemiological criteria, in order to properly monitor the evolving epidemiological changes reported in these types of infections. 相似文献
46.
Richter HG Benson GM Blum D Chaput E Feng S Gardes C Grether U Hartman P Kuhn B Martin RE Plancher JM Rudolph MG Schuler F Taylor S Bleicher KH 《Bioorganic & medicinal chemistry letters》2011,21(1):191-194
Herein we describe the synthesis and structure activity relationship of a new class of FXR agonists identified from a high-throughput screening campaign. Further optimization of the original hits led to molecules that were highly active in an LDL-receptor KO model for dyslipidemia. The most promising candidate is discussed in more detail. 相似文献
47.
Gregory F. Grether 《Evolution; international journal of organic evolution》1996,50(5):1949-1957
I studied the sex-limited red spots on the wings of male rubyspot damselflies (Hetaerina americana) in relation to territoriality and fitness in the wild. Both observational and experimental (wing spot manipulation) studies indicated that wing spots were selected through competition among males for mating territories, not through female choice or direct competition for females. Males with naturally or artificially large wing spots were more successful at holding territories and consequently mated at higher rates than males with relatively small wing spots. In contrast, sexual selection on male body size appeared to operate among nonterritorial males at the clasping stage of the mating sequence, perhaps because larger males were better at clasping females forcibly. Of four models proposed to explain the evolution of ornaments through territory competition, only the agonistic handicap model makes predictions consistent with the results of this study. 相似文献
48.
Traits that mediate intraspecific social interactions may overlap in closely related sympatric species, resulting in costly between-species interactions. Such interactions have principally interested investigators studying the evolution of reproductive isolation via reproductive character displacement (RCD) or reinforcement, yet in addition to reproductive interference, interspecific trait overlap can lead to costly between-species aggression. Previous research on rubyspot damselflies (Hetaerina spp.) demonstrated that sympatric shifts in male wing colour patterns and competitor recognition reduce interspecific aggression, supporting the hypothesis that agonistic character displacement (ACD) drove trait shifts. However, a recent theoretical model shows that RCD overshadows ACD if the same male trait is used for both female mate recognition and male competitor recognition. To determine whether female mate recognition is based on male wing coloration in Hetaerina, we conducted a phenotype manipulation experiment. Compared to control males, male H. americana with wings manipulated to resemble a sympatric congener (H. titia) suffered no reduction in mating success. Thus, female mate recognition is not based on species differences in male wing coloration. Experimental males did, however, experience higher interspecific fighting rates and reduced survival compared to controls. These results greatly strengthen the case for ACD and highlight the mechanistic distinction between ACD and RCD. 相似文献
49.
Jonathan P. Drury Kenichi W. Okamoto Christopher N. Anderson Gregory F. Grether 《Proceedings. Biological sciences / The Royal Society》2015,282(1804)
Interspecific territoriality occurs when individuals of different species fight over space, and may arise spontaneously when populations of closely related territorial species first come into contact. But defence of space is costly, and unless the benefits of excluding heterospecifics exceed the costs, natural selection should favour divergence in competitor recognition until the species no longer interact aggressively. Ordinarily males of different species do not compete for mates, but when males cannot distinguish females of sympatric species, females may effectively become a shared resource. We model how reproductive interference caused by undiscriminating males can prevent interspecific divergence, or even cause convergence, in traits used to recognize competitors. We then test the model in a genus of visually orienting insects and show that, as predicted by the model, differences between species pairs in the level of reproductive interference, which is causally related to species differences in female coloration, are strongly predictive of the current level of interspecific aggression. Interspecific reproductive interference is very common and we discuss how it may account for the persistence of interspecific aggression in many taxonomic groups. 相似文献
50.
Conspicuousness to predators frequently has been invoked asa cost of sexually selected traits, but conspicuousness to preyhas not We tested for the latter using rubyspot damselflies(Hetaerina americana) as the predator. Previous work on thisspecies showed that the red spots on male wings are intrasexuallyselected and reduce survival. Since female wings lack red spots,we first compared male and female weight gain rates per unithunting time. Females gained weight significandy faster thanmales in both mg per hour and relative to body weight. We thencompared the weight gain rates of females painted with red wingspots to those of control females painted with clear ink ornot manipulated. Controls gained weight significandy fasterthan red-painted females. Behavioral observations revealed thatred females attempted to capture prey at normal rates and experiencednormal rates of agonistic interference from conspecifics ofboth sexes. Nevertheless, red females captured fewer prey perminute and per capture attempt than did sham-manipulated andunmanipulated controls. We infer that the red spots reducedfemale weight gain rates by increasing their visibility to prey.Close similarity between male and red female weight gain ratesrelative to unmanipulated females suggests that red spots mayalso be a hunting handicap for males. [Behav Ecol 7: 465473(1996)] 相似文献