نتایج جستجو برای: Gamete Biology
تعداد نتایج: 165412 فیلتر نتایج به سال:
Flowering plant reproduction is characterized by double fertilization, in which two diminutive brother sperm cells initiate embryo and endosperm. The role of the male gamete, although studied structurally for over a century at various levels, is still being explored on a molecular and cellular level. The potential of the male to influence development has been historically underestimated and the...
The relative energetic investment in reproduction between the sexes forms the basis of sexual selection and life history theories in evolutionary biology. It is often assumed that males invest considerably less in gametes than females, but quantifying the energetic cost of gamete production in both sexes has remained a difficult challenge. For a broad diversity of species (invertebrates, reptil...
The advantage of sex has been among the most debated issues in biology. Surprisingly, the question of why sexual reproduction generally requires the combination of distinct gamete classes, such as small and large gametes, or gametes with different mating types, has been much less investigated. Why do systems with alternative gamete classes (i.e. systems with either anisogamy or mating types or ...
Sperm-zona adhesion is an essential event in mammalian fertilization, failure of which causes sterility. However, the molecular mechanisms involved in this process are still poorly understood. It has been suggested by few laboratories studying gamete interaction that acrosomal molecules are implicated in sperm-zona pellucida adhesion prior to the acrosome reaction (AR). Zonadhesin, a sperm-spec...
Reproductive isolation is pivotal to maintain species separation and it can be achieved through a plethora of mechanisms. In addition, the development of barriers to gamete interaction may drive speciation. Such barriers to interspecific gamete interaction can be prezygotic or postzygotic. Considering the great diversity in animal species, it is easy to assume that regulation of the early steps...
Sexuality in the marine araphid diatom Tabularia involves an unusual type of gamete, not only among diatoms but possibly in all of nature. The non-flagellated male gamete is free and vigorously motile, propelled by pseudopodia. However, the cues (if any) in their search for compatible female gametes and the general search patterns to locate them are unknown. We tracked and compared male gamete ...
Running head: Regulation of gene expression in plant male gamete 1 2 3 Xiaoping Gou 4 222 South Tianshui Road, School of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000, China 5 Tel: 86-13519610667 6 Email: [email protected] 7 8 Scott D. Russell 9 770 Van Vleet Oval, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, 10 OK 73019 11 Tel: 405-325-4391 12 Email: ...
Embryos and gamete cryopreservation contract is a contract between the embryos cryopreservation applicant and cryopreservation centers to freeze and preserve their embryos and gamete. This article aims to review constitutional conditions of validity, parties` obligation, sanction and dissolution methods of embryos and gamete cryopreservation contract. Research method has been revision in some p...
What is it for an animal to be female, or male? An emerging consensus among philosophers of biology that sex grounded in some manner another on anisogamy, is, the ability produce either large gametes (egg) small (sperm), though exact nature this grounding remains contentious. Here we argue a new conception relation. In our view, one’s doesn’t depend kind gamete one capable making, but designed ...
The nematode Caenorhabditis elegans is an important model for studies of germ cell biology, including the meiotic cell cycle, gamete specification as sperm or oocyte, and gamete development. Fundamental to those studies is a genome-level knowledge of the germline transcriptome. Here, we use RNA-Seq to identify genes expressed in isolated XX gonads, which are approximately 95% germline and 5% so...
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