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Gametogenesis in Madracis decactis Lyman, 1859 (Cnidaria, Scleractinia) from Ilha Grande Bay (Rio de Janeiro), southeastern Brazil

MURAMATSU, Daniela; SILVEIRA, Fábio Lang da
Fonte: Universidade de São Paulo, Instituto Oceanográfico Publicador: Universidade de São Paulo, Instituto Oceanográfico
Tipo: Artigo de Revista Científica
ENG
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Collections were made every two months in Ilha Grande Bay, Rio de Janeiro, for 21 months (August/2004-May/2006) to study the gametogenesis of Madracis decactis Lyman, 1859. A total of 1800 polyps were examined using standard histological techniques. Madracis decactis is a hermaphroditic species whose male and female gametes develop within different mesenteries. Oogenesis begins in October, while spermatogenesis begins at the end of February, both reaching maturity at the end of April. The peak of reproductive activity occurred between February and April, when all the polyps were fertile, containing mainly stage III oocytes. Examination of fertile polyps indicated the simultaneous presence of stages I, II and III for oogenesis and I, II, III and IV for spermatogenesis. No embryos or planulae were observed in the histological sections. The gametes or planulae spawning may occur between April and May.; Coletas foram feitas a cada dois meses na Baía de Ilha Grande, Rio de Janeiro, durante 21 meses (agosto/2004 - maio/2006) para estudar a gametogênese de Madracis decactis Lyman, 1859. Um total de 1800 pólipos foram examinados através de técnicas histológicas padrão. M. decactis é uma espécie hermafrodita, cujos gametas masculinos e femininos se desenvolvem em mesentérios diferentes. A ovogênese iniciou em outubro...

Quantificação da gametogênese através de análises histológicas para estimar a reprodução sexuada de Madracis decactis Lyman, 1859 (Cnidaria, Anthozoa, Scleractinia) do litoral sul do Estado do Rio de Janeiro; Gametogenesis quantification though histological analisys to estimate the sexual reproduction of Madracis decactis Lyman, 1859 (Cnidaria, Anthozoa, Scleractinia) from southern coast of Rio de Janeiro State.

Muramatsu, Daniela
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/08/2007 PT
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Uma das espécies de coral pétreo zooxantelado com mais ampla distribuição no litoral brasileiro é Madracis decactis Lyman, 1859. M. decactis forma colônias incrustantes nodulares que podem atingir até 30 cm de diâmetro. O estudo da gametogênese foi realizado através de coletas bimensais na Baía de Ilha Grande, RJ durante 21 meses (agosto/2004-maio/2006), totalizando 10 coletas (12 colônias/coleta) (Licença IBAMA no. 201/2004). Foram realizados cortes histológicos de 7 µm, e de 10 até 16 pólipos por colônia foram analisados, totalizando mais de 1800 pólipos. A análise dos pólipos indicou que M. decactis é hermafrodita, com gametas localizados no mesmo lóculo gástrico, porém em mesentérios diferentes. A gametogênese durou cerca de sete meses. A ovogênese iniciou-se ao redor de outubro, enquanto que a espermatogênese teve inicio no final de fevereiro, ambas terminando em sincronia no final do mês de maio. O exame dos pólipos férteis indicou a presença dos estágios I, II e III de desenvolvimento para a ovogênese e dos estágios I, II, III e IV para a espermatogênese. Não foram encontrados embriões ou plânulas nos cortes histológicos, indicando talvez que estes estágios permaneçam pouco tempo no interior do pólipo. O pico da atividade reprodutiva ocorre entre os meses de fevereiro e abril com todas as colônias férteis contendo ovócitos principalmente no estágio III de maturação. A provável época de liberação de plânulas ocorre entre os meses de abril e maio...

Gametogenesis in Madracis decactis Lyman, 1859 (Cnidaria, Scleractinia) from Ilha Grande Bay (Rio de Janeiro), southeastern Brazil

Muramatsu,Daniela; Silveira,Fábio Lang da
Fonte: Universidade de São Paulo, Instituto Oceanográfico Publicador: Universidade de São Paulo, Instituto Oceanográfico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
Relevância na Pesquisa
37.1%
Collections were made every two months in Ilha Grande Bay, Rio de Janeiro, for 21 months (August/2004-May/2006) to study the gametogenesis of Madracis decactis Lyman, 1859. A total of 1800 polyps were examined using standard histological techniques. Madracis decactis is a hermaphroditic species whose male and female gametes develop within different mesenteries. Oogenesis begins in October, while spermatogenesis begins at the end of February, both reaching maturity at the end of April. The peak of reproductive activity occurred between February and April, when all the polyps were fertile, containing mainly stage III oocytes. Examination of fertile polyps indicated the simultaneous presence of stages I, II and III for oogenesis and I, II, III and IV for spermatogenesis. No embryos or planulae were observed in the histological sections. The gametes or planulae spawning may occur between April and May.

Gametogenesis in Chlamydomonas eugametos: I. Light Requirements 12

Lorch, Steven K.; Karlander, Edward P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1973 EN
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27.65%
Male and female mating types of Chlamydomonas eugametos Moewus show an absolute light requirement for gametogenesis. Increasing light intensity from 0.3 to 1.2 mw cm−2 during nitrogen starvation (a precondition for gametogenesis) caused an increase in gametogenesis throughout a 28-hour period. Gametogenesis was measured by determining the percentage of paired cells after a 1-hour mixing period. Light requirements for the male and female differed. There was a 9-hour lag period in gametogenesis in the male, but no lag in the female. Gametogenesis was reduced 50% in the female and 90% in the male when 6.0 μm 3-(3,4-dichlorophenyl)-1, 1-dimethyl-urea was in the N-starvation medium. Sodium acetate, 1.8 mm, in the N-starvation medium increased gametogenesis in both mating types and eliminated the 9-hour lag in the male for cells irradiated for 3, 6, 9, 12, 15, 18, or 23 hours during the last part of a 23-hour N-starvation period. Sodium acetate concentrations higher than 1.8 mm inhibited the mating process. 3-(3,4-Dichlorophenyl)-1, 1-dimethylurea inhibition of gametogenesis was decreased in the male but increased in the female, when sodium acetate was added to the N-starvation medium. These results indicate a nonphotosynthetic as well as a photosynthetic role for light in the gametogenesis of both mating types. Also...

A Classical Arabinogalactan Protein Is Essential for the Initiation of Female Gametogenesis in Arabidopsis

Acosta-García, Gerardo; Vielle-Calzada, Jean-Philippe
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /10/2004 EN
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Classical arabinogalactan proteins (AGPs) are an abundant class of cell surface proteoglycans widely distributed in flowering plants. We have used a combination of enhancer detection tagging and RNA interference (RNAi)–induced posttrancriptional silencing to demonstrate that AGP18, a gene encoding a classical arabinogalactan protein, is essential for female gametogenesis in Arabidopsis thaliana. AGP18 is expressed in cells that spatially and temporally define the sporophytic to gametophytic transition and during early stages of seed development. More than 75% of the T1 transformants resulted in T2 lines showing reduced seed set during at least three consecutive generations but no additional developmental defects. AGP18-silenced T2 lines showed reduced AGP18 transcript levels in female reproductive organs, the presence of 21-bp RNA fragments specific to the AGP18 gene, and the absence of in situ AGP18 mRNA localization in developing ovules. Reciprocal crosses to wild-type plants indicate that the defect is female specific. The genetic and molecular analysis of AGP18-silenced plants containing a single T-DNA RNAi insertion suggests that posttranscriptional silencing of AGP18 is acting both at the sporophytic and gametophytic levels. A cytological analysis of all defective AGP18-RNAi lines...

Gametogenesis in Malaria Parasites Is Mediated by the cGMP-Dependent Protein Kinase

McRobert, Louisa; Taylor, Cathy J; Deng, Wensheng; Fivelman, Quinton L; Cummings, Ross M; Polley, Spencer D; Billker, Oliver; Baker, David A
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN
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27.37%
Malaria parasite transmission requires differentiation of male and female gametocytes into gametes within a mosquito following a blood meal. A mosquito-derived molecule, xanthurenic acid (XA), can trigger gametogenesis, but the signalling events controlling this process in the human malaria parasite Plasmodium falciparum remain unknown. A role for cGMP was revealed by our observation that zaprinast (an inhibitor of phosphodiesterases that hydrolyse cGMP) stimulates gametogenesis in the absence of XA. Using cGMP-dependent protein kinase (PKG) inhibitors in conjunction with transgenic parasites expressing an inhibitor-insensitive mutant PKG enzyme, we demonstrate that PKG is essential for XA- and zaprinast-induced gametogenesis. Furthermore, we show that intracellular calcium (Ca2+) is required for differentiation and acts downstream of or in parallel with PKG activation. This work defines a key role for PKG in gametogenesis, elucidates the hierarchy of signalling events governing this process in P. falciparum, and demonstrates the feasibility of selective inhibition of a crucial regulator of the malaria parasite life cycle.

Regulation of entry into gametogenesis

van Werven, Folkert J.; Amon, Angelika
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 27/12/2011 EN
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Gametogenesis is a fundamental aspect of sexual reproduction in eukaryotes. In the unicellular fungi Saccharomyces cerevisiae (budding yeast) and Schizosaccharomyces pombe (fission yeast), where this developmental programme has been extensively studied, entry into gametogenesis requires the convergence of multiple signals on the promoter of a master regulator. Starvation signals and cellular mating-type information promote the transcription of cell fate inducers, which in turn initiate a transcriptional cascade that propels a unique type of cell division, meiosis, and gamete morphogenesis. Here, we will provide an overview of how entry into gametogenesis is initiated in budding and fission yeast and discuss potential conserved features in the germ cell development of higher eukaryotes.

Transcription of two long non-coding RNAs mediates mating type control of gametogenesis in budding yeast

van Werven, Folkert J.; Neuert, Gregor; Hendrick, Natalie; Lardenois, Aurélie; Buratowski, Stephen; van Oudenaarden, Alexander; Primig, Michael; Amon, Angelika
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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27.37%
The cell fate decision leading to gametogenesis is essential for sexual reproduction. In S. cerevisiae, only diploid MATa/α but not haploid MATa or MATα cells undergo gametogenesis, known as sporulation. We find that transcription of two long non-coding RNAs (lncRNAs) mediates mating type control of sporulation. In MATa or MATα haploids expression of IME1, the central inducer of gametogenesis, is inhibited in cis by transcription of the lncRNA IRT1, located in the IME1 promoter. IRT1 transcription recruits the Set2 histone methyltransferase and the Set3 histone deacetylase complex to establish repressive chromatin at the IME1 promoter. Inhibiting expression of IRT1 and an antisense transcript that antagonizes the expression of the meiotic regulator IME4, allows cells expressing the haploid mating-type to sporulate with kinetics that are indistinguishable from that of MATa/α diploids. Conversely, expression of the two lncRNAs abolishes sporulation in MATa/α diploids. Thus, transcription of two lncRNAs governs mating type control of gametogenesis in yeast.

The Rim15-Endosulfine-PP2ACdc55 Signalling Module Regulates Entry into Gametogenesis and Quiescence via Distinct Mechanisms in Budding Yeast

Sarkar, Sourav; Dalgaard, Jacob Z.; Millar, Jonathan B. A.; Arumugam, Prakash
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 26/06/2014 EN
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27.55%
Quiescence and gametogenesis represent two distinct survival strategies in response to nutrient starvation in budding yeast. Precisely how environmental signals are sensed by yeast cells to trigger quiescence and gametogenesis is not fully understood. A conserved signalling module consisting of Greatwall kinase, Endosulfine and Protein Phosphatase PP2ACdc55 proteins regulates entry into mitosis in Xenopus egg extracts and meiotic maturation in flies. We report here that an analogous signalling module consisting of the serine-threonine kinase Rim15, the Endosulfines Igo1 and Igo2 and the Protein Phosphatase PP2ACdc55, regulates entry into both quiescence and gametogenesis in budding yeast. PP2ACdc55 inhibits entry into gametogenesis and quiescence. Rim15 promotes entry into gametogenesis and quiescence by converting Igo1 into an inhibitor of PP2ACdc55 by phosphorylating at a conserved serine residue. Moreover, we show that the Rim15-Endosulfine-PP2ACdc55 pathway regulates entry into quiescence and gametogenesis by distinct mechanisms. In addition, we show that Igo1 and Igo2 are required for pre-meiotic autophagy but the lack of pre-meiotic autophagy is insufficient to explain the sporulation defect of igo1Δ igo2Δ cells. We propose that the Rim15-Endosulfine-PP2ACdc55 signalling module triggers entry into quiescence and gametogenesis by regulating dephosphorylation of distinct substrates.

Evidence for equal size cell divisions during gametogenesis in a marine green alga Monostroma angicava

Togashi, Tatsuya; Horinouchi, Yusuke; Sasaki, Hironobu; Yoshimura, Jin
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 03/09/2015 EN
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In cell divisions, relative size of daughter cells should play fundamental roles in gametogenesis and embryogenesis. Differences in gamete size between the two mating types underlie sexual selection. Size of daughter cells is a key factor to regulate cell divisions during cleavage. In cleavage, the form of cell divisions (equal/unequal in size) determines the developmental fate of each blastomere. However, strict validation of the form of cell divisions is rarely demonstrated. We cannot distinguish between equal and unequal cell divisions by analysing only the mean size of daughter cells, because their means can be the same. In contrast, the dispersion of daughter cell size depends on the forms of cell divisions. Based on this, we show that gametogenesis in the marine green alga, Monostroma angicava, exhibits equal size cell divisions. The variance and the mean of gamete size (volume) of each mating type measured agree closely with the prediction from synchronized equal size cell divisions. Gamete size actually takes only discrete values here. This is a key theoretical assumption made to explain the diversified evolution of isogamy and anisogamy in marine green algae. Our results suggest that germ cells adopt equal size cell divisions during gametogenesis.

The making of gametes in higher plants

Boavida, L.; Becker, J.D.; Feijó, J.A.
Fonte: UBC Press Publicador: UBC Press
Tipo: Artigo de Revista Científica
Publicado em //2005 ENG
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27.26%
Higher plants have evolved to be one of the predominant life forms on this planet. A great deal of this evolutionary success relies in a very short gametophytic phase which underlies the sexual reproduction cycle. Sexual plant reproduction takes place in special organs of the flower. In most species the processes of gametogenesis, pollination, syngamy and embryogenesis are sequentially coordinated to give rise to a functional seed in a matter of few weeks. Any of these processes is so intricately complex and precisely regulated that it becomes no wonder that each involves more specific genes and cellular processes than any other function in the plant life cycle. While variability generation - the evolutionary output of the sexual cycle - is the same as in any other Kingdom, plants do it using a completely original set of mechanisms, many of which are not yet comprehended. In this paper, we cover the fundamental features of male and female gametogenesis. While the physiological and cellular bases of these processes have been continuously described since the early nineteen century, recent usage of Arabidopsis and other species as central models has brought about a great deal of specific information regarding their genetic regulation. Transcriptomics has recently enlarged the repertoire and pollen became the first gametophyte to have a fully described transcriptome in plants. We thus place special emphasis on the way this newly accumulated genetic and transcriptional information impacts our current understanding of the mechanisms of gametogenesis.

Gonadal organization and gametogenesis in musculium argentinum (Veneroida: Sphaeriidae) from a population in Southern Chile

Fonte: Universidade Católica de Temuco Publicador: Universidade Católica de Temuco
Tipo: Artículo de Revista
EN
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37.1%
The gonadal organization and cytological characteristics of gametogenesis in a population of the freshwater clam Musculium argentinum (d'Orbigny, 1835) are described. Sections of the rather small gonad demonstrate the existence of hermaphroditic specimens, and is composed of hermaphrodite follicles among the intestine coils in the posterior dorsal region of the body. Follicles contain male and female germ cells at different stages of maturation, which can be recognized by their shape, size, and nuclear features. Male germ cells are organized in cysts, and spermatocytes do carry out meiosis. Within follicles, male and female germ cells occupy different regions. Gonad activity throughout the year is coincident with the life cycle pattern of the M. argentinum population studied previously.

Drosophila Importin α1 Performs Paralog-Specific Functions Essential For Gametogenesis

Ratan, R.; Mason, D. A.; Sinnot, B.; Goldfarb, D. S.; Fleming, R. J.
Fonte: Genetics Society of America Publicador: Genetics Society of America
Tipo: Artigo de Revista Científica
Publicado em /02/2008 EN
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27.26%
Importin α's mediate nuclear transport by linking nuclear localization signal (NLS)-containing proteins to importin β1. Animal genomes encode three conserved groups of importin α's, α1's, α2's, and α3's, each of which are competent to bind classical NLS sequences. Using Drosophila melanogaster we describe the isolation and phenotypic characterization of the first animal importin α1 mutant. Animal α1's are more similar to ancestral plant and fungal α1-like genes than to animal α2 and α3 genes. Male and female importin α1 (Dα1) null flies developed normally to adulthood (with a minor wing defect) but were sterile with defects in gametogenesis. The Dα1 mutant phenotypes were rescued by Dα1 transgenes, but not by Dα2 or Dα3 transgenes. Genetic interactions between the ectopic expression of Dα1 and the karyopherins CAS and importin β1 suggest that high nuclear levels of Dα1 are deleterious. We conclude that Dα1 performs paralog-specific activities that are essential for gametogenesis and that regulation of subcellular Dα1 localization may affect cell fate decisions. The initial expansion and specialization of the animal importin α-gene family may have been driven by the specialized needs of gametogenesis. These results provide a framework for studies of the more complex mammalian importin α-gene family.

Boule and the Evolutionary Origin of Metazoan Gametogenesis: A Grandpa's Tale

Eirín-López, José M.; Ausió, Juan
Fonte: SAGE-Hindawi Access to Research Publicador: SAGE-Hindawi Access to Research
Tipo: Artigo de Revista Científica
Publicado em 06/07/2011 EN
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27.26%
The evolution of sex remains a hotly debated topic in evolutionary biology. In particular, studying the origins of the molecular mechanisms underlying sexual reproduction and gametogenesis (its fundamental component) in multicellular eukaryotes has been difficult due to the rapid divergence of many reproductive proteins, pleiotropy, and by the fact that only a very small number of reproductive proteins specifically involved in reproduction are conserved across lineages. Consequently, during the last decade, many efforts have been put into answering the following question: did gametogenesis evolve independently in different animal lineages or does it share a common evolutionary origin in a single ancestral prototype? Among the various approaches carried out in order to solve this question, the characterization of the evolution of the DAZ gene family holds much promise because these genes encode reproductive proteins that are conserved across a wide range of animal phyla. Within this family, BOULE is of special interest because it represents the most ancestral member of this gene family (the “grandfather” of DAZ). Furthermore, BOULE has attracted most of the attention since it represents an ancient male gametogenic factor with an essential reproductive-exclusive requirement in urbilaterians...

Gametogenesis and Sex Steroid Profiles in Cultured Coho Salmon (Oncorhynchus kisutch, Walbaum)

Valladares, Luis; Torres, Alfredo; Díaz, Nelon F.; Neira Roa, Roberto Fernando; Estay, Francisco
Fonte: Universidade do Chile Publicador: Universidade do Chile
Tipo: Artículo de revista
EN_US
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The gametogenesis of a 2-year-old coho salmon broodstock population cultured in a fish farm in southern Chile was studied. Gonadosomatic index (GSI), microscopic gonadal traits, and serum levels of estradiol-17b(E2), testosterone, and 17a,20b-dihydroxy-4-pregnene-3-one (17,20P) in both sexes were recorded beginning 9 months before spawning in bimonthly samplings. Maximum GSI means were reached during May, the month of spawning, with 16.8 ± 4.1% for females and 8.4 ± 0.8% for males, both values within the range described in the literature. GSI in males, however, was triple that of females during January, showing a faster rate of gonadal growth in males in early summer. Gonadal microscopy for both sexes showed stages corresponding to those described by different authors for other salmonids such as rainbow trout. The secondary vitellogenesis period was 4 to 5 months and corresponded with the short vitellogenesis model described in rainbow trout for broodstocks maturing at 2 years of age. The serum profiles of sex steroids in both sexes are consistent with those described in coho salmon and other salmonid species. In females, E2 and 17,20P show opposite profiles, reaching their maximum levels (E2: 45.13 ± 11.3 ng/ml; 17...

The role of ATR kinase during mammalian gametogenesis

Pacheco Piñol, Sarai
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2015 ENG
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ATR és una proteïna cinasa essencial per a la viabilitat cel·lular que participa en els mecanismes de resposta al dany en el DNA per tal de mantenir la integritat del genoma. Aquesta proteïna es activada en resposta a regions de cadena simple del DNA (ssDNA) generades per la resecció dels trencaments de doble cadena (DSBs) i controla la progressió de les forques de replicació durant la fase S del cicle cel·lular. Durant la meiosi, un tipus de divisió cel·lular especialitzada per la qual les cèl·lules es divideixen per formar gàmetes haploides, es generen deliberadament una sèrie de DSBs en el genoma. La reparació d'aquests DSBs condueix a l'aparellament, sinapsi i recombinació dels cromosomes homòlegs creant connexions entre ells per tal de promoure la correcta segregació dels cromosomes durant la primera divisió meiòtica i evitar la formació de gàmetes aneuploides. Aquests processos son crucials per a la viabilitat de les cèl·lules meiòtiques, i per tant es troben altament regulats mitjançant diferents mecanismes que inclouen les vies de senyalització de les proteïnes d'ATM i ATR. Estudis citològics suggereixen que ATR està implicada en la reparació meiòtica, ja que s'ha demostrat que es troba als DSBs juntament amb altres proteïnes de resposta al dany el DNA...

Sexual reproductive cycle of the epibiotic soft coral Alcyonium coralloides (Octocorallia, Alcyonacea)

Quintanilla, Elena; Gili, Josep-Maria; López-González, Pablo J.; Tsounis, Georgios; Madurell, Teresa; Fiorillo, Ida; Rossi, Sergio
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2013 ENG
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27.26%
Alcyonium coralloides is an epibiotic soft coral overgrowing living colonies of Mediterranean gorgonians. The main features of the sexual reproductive cycle of this soft coral species are described and quantified for the first time, in a population found at 18 to 22 m depth off the Medes Islands (NW Mediterranean). A. coralloides is a gonochoric internal brooder. The sexual cycle showed a single reproductive event per year. Gametogenesis took 5 to 6 mo, which is the shortest known gametogenesis in littoral octocorals (especially for oogenesis). The maximum mean ± SD diameter was 365 ± 86 μm for spermatic cysts and 632 ± 125 μm for mature oocytes. Sperm was released in spring (late May). Average male and female fecundity in this last phase of the cycle was 15 ± 9 spermatic cysts and 7 ± 4 oocytes per polyp, respectively. Larvae of about 1000 μm in length were observed in the gastrovascular cavities of female colonies in May, before they were released in June. We suggest that the remarkable short gametogenesis and timing shown by A. coralloides is an adaptation to optimize the colonization of its host (in this case the gorgonian octocoral Paramuricea clavata). We conclude that A. coralloides larvae could be ready to settle in early summer when the host P. clavata is probably more vulnerable as a result of its own reproductive cycle coming to an end.

GAMETOGÊNESE: ESTÁGIO FUNDAMENTAL DO DESENVOLVIMENTO PARA REPRODUÇÃO HUMANA; GAMETOGENESIS: FUNDAMENTAL STAGE THE DEVELOPMENT FOR HUMAN REPRODUCTION

Araújo, Carlos Henrique Medeiros; Araújo, Maria Cristina Picinato Medeiros; Martins, Wellington Paula; Ferriani, Rui Alberto; Reis, Rosana Maria
Fonte: Universidade de São Paulo. Faculdade de Medicina de Ribeirão Preto Publicador: Universidade de São Paulo. Faculdade de Medicina de Ribeirão Preto
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 30/12/2007 POR
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A reprodução é o mecanismo essencial para perpetuação e diversidade das espécies assim como para a continuidade da vida. Os gametas são os veículos de transferência dos genes para as próximas gerações. A gametogênese pode ser caracterizada por três etapas distintas denominadas multiplicação (mitose), crescimento e maturação (meiose), que se diferenciam em vários aspectos na espermatogênese e na oogênese. A oogênese diferencia-se da espermatogênese na ocorrência do processo ao longo da vida do indivíduo, no número de gametas formados, nas etapas de multiplicação, crescimento e maturação, assim como nas diferenciações e maturações citoplasmáticas e nucleares dos gametas masculinos e femininos.O processo da oogênese em relação à maturação oocitária ainda merece mais estudos, pois os aspectos bioquímicos e genéticos deste processo precisam ser mais bem esclarecidos. Por meio da gametogênese masculina e feminina a natureza proporcionou a fertilidade e a capacidade de gerar filhos a casais de diferentes espécies que se reproduzem sexuadamente incluindo a espécie humana. Quando existem falhas neste mecanismo por diferentes motivos como oligospermia, teratozoospermia, astenoospermia, azoospermia...

Gametogenesis in Madracis decactis Lyman, 1859 (Cnidaria, Scleractinia) from Ilha Grande Bay (Rio de Janeiro), southeastern Brazil

Muramatsu, Daniela; Silveira, Fábio Lang da
Fonte: Universidade de São Paulo. Instituto Oceanográfico Publicador: Universidade de São Paulo. Instituto Oceanográfico
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 01/12/2008 ENG
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37.1%
Collections were made every two months in Ilha Grande Bay, Rio de Janeiro, for 21 months (August/2004-May/2006) to study the gametogenesis of Madracis decactis Lyman, 1859. A total of 1800 polyps were examined using standard histological techniques. Madracis decactis is a hermaphroditic species whose male and female gametes develop within different mesenteries. Oogenesis begins in October, while spermatogenesis begins at the end of February, both reaching maturity at the end of April. The peak of reproductive activity occurred between February and April, when all the polyps were fertile, containing mainly stage III oocytes. Examination of fertile polyps indicated the simultaneous presence of stages I, II and III for oogenesis and I, II, III and IV for spermatogenesis. No embryos or planulae were observed in the histological sections. The gametes or planulae spawning may occur between April and May.; Coletas foram feitas a cada dois meses na Baía de Ilha Grande, Rio de Janeiro, durante 21 meses (agosto/2004 - maio/2006) para estudar a gametogênese de Madracis decactis Lyman, 1859. Um total de 1800 pólipos foram examinados através de técnicas histológicas padrão. M. decactis é uma espécie hermafrodita, cujos gametas masculinos e femininos se desenvolvem em mesentérios diferentes. A ovogênese iniciou em outubro...

Early Gametogenesis of Kumamoto oyster (Crassostrea sikamea)

Cáceres-Martínez,Jorge; Vásquez-Yeomans,Rebeca; Guerrero-Rentería,Yanet
Fonte: UAM, Unidad Iztapalapa, Publicador: UAM, Unidad Iztapalapa,
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 EN
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The Kumamoto oyster, Crassostrea sikamea, starts gametogenesis as young as 71 days old from spawning (35 days from post-settlement) with a mean shell height of 3.0 mm. This information constitutes a new record in age-size for gametogenesis in oysters for commercial importance and adds another biological difference comparing this species with the Pacific oyster Crassostrea gigas.