نتایج جستجو برای: asexual parasites
تعداد نتایج: 43061 فیلتر نتایج به سال:
With the aim of developing an appropriate in vitro model of the sequestration of developing Plasmodium falciparum sexual-stage parasites, we have investigated the cytoadherence of gametocytes to human bone marrow cells of stromal and endothelial origin. Developing stage III and IV gametocytes, but not mature stage V gametocytes, adhere to bone marrow cells in significantly higher densities than...
The persistence of sexual reproduction is a classic problem in evolutionary biology. The problem stems from the fact that, all else equal, asexual lineages should rapidly replace coexisting sexual individuals due to the cost of producing males in sexual populations. One possible countervailing advantage to sexual reproduction is that, on average, outcrossed offspring are more resistant than com...
Modifying the Redfield model of sexual reproduction and the Penna model of biological aging, we compare reproduction with and without recombination in age-structured populations. In contrast to Redfield and in agreement with Bernardes we find sexual reproduction to be preferred to asexual one. In particular, the presence of old but still reproducing males helps the survival of younger females b...
Question: Can parasites stabilize host-population dynamics and thereby reduce the risk of host extinction? Model: We analysed a discrete-time model of logistic growth in an annual, asexual host population. Infection was assumed to reduce host fecundity, but not host survival. Using simulations, we determined whether parasites stabilized or destabilized host-population dynamics. We calculated th...
Individuals who reproduce asexually have a two-fold advantage over their sexually-reproducing counterparts as they are able to reproduce twice as fast. Explaining why sexual reproduction is favoured over asexual reproduction therefore remains an important challenge in evolutionary biology. Various mechanisms involving resistance to parasites, adaptation to novel environments and helping to purg...
U nderstanding the emergence of sexual reproduction has been one of nature’s long-standing mysteries that even now is only partially understood. There is a clear distinction between the reason sex evolved in the first place in early eukaryotes—and even before that in prokaryotes—and why it has been so stubbornly maintained in virtually all higher species. After all, asexual reproduction is supe...
The life cycles of many parasites involve transitions between disparate host species, requiring these parasites to go through multiple developmental stages adapted to each of these specialized niches. Transmissionofmalaria parasites (Plasmodiumspp.) fromhumans to the mosquito vector requires differentiation from asexual stages replicatingwithin redblood cells into non-dividingmale and female ga...
Circadian rhythms enable organisms to synchronise the processes underpinning survival and reproduction to anticipate daily changes in the external environment. Recent work shows that daily (circadian) rhythms also enable parasites to maximise fitness in the context of ecological interactions with their hosts. Because parasite rhythms matter for their fitness, understanding how they are regulate...
Therapies to prevent transmission of malaria parasites to the mosquito vector are a vital part of the global malaria elimination agenda. Primaquine is currently the only drug with such activity; however, its use is limited by side effects. The development of transmission-blocking strategies requires an understanding of sexual stage malaria parasite (gametocyte) biology and the identification of...
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