共查询到20条相似文献，搜索用时 15 毫秒
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Yeoung‐Gyu Ko Jisoo Yun Hyoung Joon Park Satoshi Tanaka Kunio Shiota Jae‐Hyeon Cho 《Molecular reproduction and development》2013,80(3):212-222
DNA methyltransferase1o (Dnmt1o), which is specific to oocyte and preimplantation embryo, plays a role in maintaining DNA methylation in mammalian cells. Here, we investigated the methylation status of CpGs sites in the Dnmt1o 5′‐flanking region in germ cells at different stages of oogenesis or spermatogenesis. The methylation levels of the CpG sites at the 5′‐flanking regions were hypermethylated in growing oocytes of all follicular stages, while the oocytes in meiotic metaphase II (MII) were demethylated. The methylation pattern within the CpGs sites in the 5′‐flanking region, however, was dramatically changed during spermatogenesis. We observed that there was significant non‐CpG methylation both in MII oocytes and spermatocytes. Although a low methylation level in non‐CpG sites was observed in primary and secondary oocytes, the CpA site of position 25 and CpT site of position 29 within the no‐CpG region in the 5′‐flanking region of Dnmt1o was highly methylated in MII oocytes. During spermatogenesis, the low degree of methylation at CpG sites in spermatocytes increased to a higher degree in sperm, while the high ratio of methylation in non‐CpG sites in spermatocytes decreased. Together, germ cells showed inverted methylation patterns between CpG and non‐CpG sites in the Dnmt1o 5′‐upstream region, and the methylation pattern during oogenesis did not drastically change, remaining generally hypomethylated at the MII stage. Mol. Reprod. Dev. 80: 212–222, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
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Laura J. Lyons Ruth M. O’Riordan Thomas F. Cross Sarah C. Culloty 《Invertebrate reproduction & development.》2013,57(2):144-156
A histological study of the reproductive cycle of male and female shore crabs, Carcinus maenas (Linnaeus), was performed monthly on the South West coast of Ireland (from December 2006 to July 2008). The calculated sex ratio deviated from equality, 1:0.53, revealing a strong male bias. A system was devised, based on screening of tissue sections, to describe and stage gametogenic development. Histological examinations revealed that ovarian development occurred biannually, with a primary winter cycle in which the larger crabs reproduced and a secondary summer cycle, when smaller crabs reproduced. An association was observed where more of the larger specimens were caught in the summer months and the smaller specimens in the winter months, which inversely correlated with the segregated breeding cycles. There was strong evidence that mature male crabs could potentially copulate year round since all mature specimens, collected throughout the year, contained viable spermatozoa. Developmental stages of oogenesis and spermatogenesis were described to develop a practical gonadal index for this portunid crab, providing information on the biology of this species, which will be of benefit for fisheries management. 相似文献
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The giant Caribbean sea anemone, Condylactis gigantea, is an ecologically important member of the benthic community. It provides habitat for many species, including symbiotic cleaner shrimps, and is recognized by reef fishes as a cleaning station cue. Numbers of C. gigantea in Florida have recently declined, possibly due to deteriorating environmental conditions and increasing harvest pressure. A previous research finding indicating that C. gigantea spawns in the late spring has been questioned by fishers for the aquarium trade industry. We therefore examined specimens of C. gigantea collected monthly from October 2011 to September 2012 in the Florida Keys to characterize the reproductive cycle, also measuring several physical and chemical parameters of concurrently collected water samples. We ascertained that the anemone is gonochoric and has a 1:1 sex ratio. Within and between individuals, at the same time and place, spermatogenesis was synchronous, whereas oocyte development was asynchronous. Low‐level spawning occurred between October and April with a peak in May, in good agreement with earlier research. Water quality at both sites showed no discernible change over the study period. Conservation efforts directed at population management could benefit this anemone. 相似文献
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Hoai Thu Le Yoshikazu Hasegawa Yoko Daitoku Kanako Kato Saori Miznuo‐Iijima Tra Thi Huong Dinh Yumeno Kuba Yuki Osawa Natsuki Mikami Kento Morimoto Shinya Ayabe Yoko Tanimoto Kazuya Murata Ken‐ichi Yagami Satoru Takahashi Seiya Mizuno Fumihiro Sugiyama 《Genesis (New York, N.Y. : 2000)》2020,58(7)
Germ cell development is essential for maintaining reproduction in animals. In postpubertal females, oogenesis is a highly complicated event for producing fertilizable oocytes. It starts when dormant primordial oocytes undergo activation to become growing oocytes. In postpubertal males, spermatogenesis is a differentiation process for producing sperm from spermatogonial stem cells. To obtain full understanding of the molecular mechanisms underlying germ cell development, the Cre/loxP system has been widely applied for conditional knock‐out mouse studies. In this study, we established a novel knock‐in mouse line, B6‐Ddx4 em1(CreERT2)Utr, which expresses CreERT2 recombinase under the control of the endogenous DEAD‐box helicase 4 (Ddx4) gene promoter. Ddx4 was specifically expressed in both female and male germ cell lineages. We mated the CreERT2 mice with R26GRR mice, expressing enhanced green fluorescent protein (EGFP) and tDsRed before and after Cre recombination. We found tDsRed signals in the testes and ovaries of tamoxifen‐treated B6‐Ddx4 em1(CreERT2)Utr::R26GRR mice, but not in untreated mice. Immunostaining of their ovaries clearly showed that Cre recombination occurred in all oocytes at every follicle stage. We also found 100% Cre recombination efficiency in male germ cells via the progeny test. In summary, our results indicate that B6‐Ddx4 em1(CreERT2)Utr is beneficial for studying female and male germ cell development. 相似文献
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In Caenorhabditis briggsae hermaphrodites, spermatogenesis begins in the L4 larval stage and persists into early adulthood. Oogenesis begins after spermatogenesis; the sperm‐to‐oocyte transition is irreversible. The timing of this transition is believed to have evolved in response to selection to maximize the intrinsic growth rate. Sperm‐to‐oocyte transitions occurred early in Cbr‐met‐2 and Cbr‐fem‐3 mutants. These early transitions resulted in reduced brood sizes, but had little or no impact on the intrinsic growth rate. In Cbr‐met‐2; Cbr‐fem‐3 doubly mutant hermaphrodites, the transition to oogenesis occurred even earlier and brood size was further reduced, indicating that Cbr‐met‐2 and Cbr‐fem‐3 regulate the sperm‐to‐oocyte transition through separate pathways. Mutations in Cbr‐met‐2 also resulted in an increase in the frequency of males in mutant populations. These increased male frequencies were not caused by increased rates of X nondisjunction during oogenesis in mutant hermaphrodites. Rather, increases in the rates of outcrossing in mutant populations likely were an indirect effect of reduced brood sizes derived from self‐fertilization. Based on these observations, it is possible that the timing of the sperm‐to‐oocyte transition in C. briggsae evolved in response to sexual selection on hermaphrodites to limit rates of outcrossing. Mutations in the orthologous Caenorhabditis elegans gene, Cel‐met‐2, did not impact the timing of the sperm‐to‐oocyte transition, consistent with the independent evolution of hermaphroditic reproduction in these species. Although brood sizes were reduced in Cel‐met‐2 mutant strains, increased male frequencies were not observed. Cbr‐ and Cel‐met‐2 mutations also differed in terms of germline mortality, observed in C. elegans, but not in C. briggsae. 相似文献
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The germ cell nuclear factor (GCNF) 总被引：1，自引：0，他引：1
Zechel C 《Molecular reproduction and development》2005,72(4):550-556
The germ cell nuclear factor (GCNF), which is also known as RTR (retinoid receptor-related testis-associated receptor) is a member of the nuclear receptor superfamily. As a natural ligand remains to be discovered, GCNF is referred to as an orphan receptor. Owing to GCNF's unique features and its distant relation to any other known nuclear receptor it has been classified as the only member of the subgroup six and designated NR6A1 by the Receptor Nomenclature Committee (Duarte et al., 2002: Nucleic Acids Res 30: 364-368). To date, GCNF has been cloned from distinct vertebrate species, including zebrafish, Xenopus laevis, mouse, rat, and human. Cloning and characterization of the gene, domain organization and DNA binding properties of the protein, as well as the differential expression of mRNA splice variants or the protein during development and in the adult animal have been comprehensively reviewed by others (Greschik and Schüle, 1998: J Mol Med 76:800-810; Cooney et al., 1999: Am Zool 39:796-806). In this minireview I focus on the pleiotropic function of GCNF in embryogenesis and germ cell differentiation, and discuss novel concepts about its putative role in neurogenesis. 相似文献
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Abstract. The reproductive cycles of four Mediterranean demosponges ( Axinella damicornis, Corticium candelabrum, Raspaciona aculeata , and Chondrosia reniformis ) were investigated during 2 consecutive years. Three of the species had annual gametogenic cycles characterized by a single peak of gamete production, but members of C. candelabrum showed continuous oocyte production during the 2 years. The relationship between gametogenic dynamics and seawater temperature varied substantially among species, contrary to the widespread belief that gamete production is associated with seasonal water warming. The annual temperature increase (in June) concurred with oocyte production only in C. reniformis , although maximum temperatures were simultaneous with the production of both oocytes in R. aculeata and sperm in C. reniformis . In contrast, the annual temperature decline in October was associated with both oogenesis in A. damicornis and spermatogenesis in R. aculeata . Spermatogenesis in A. damicornis started after a 5-month period of low-temperature values (December–April in 2004 and November–March in 2005). Likewise, in C. candelabrum , spermatogenesis started after a 3-month period of low-temperature values (November–February), a period concomitant with a slow increase in oocyte production. These findings reveal that sponge species that cooccur and share similar thermal regimes may differ substantially in their timing of gamete production. If we are to predict the future effects of climate change on marine benthic communities, there is an urgent need to improve our knowledge of the species-specific relationship between timing of gametogenesis and temperature, at least for those sponges that are key species in benthic communities. 相似文献
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Ana Riesgo Adriana Villamor Mikel Becerro 《Invertebrate reproduction & development.》2013,57(3):138-151
Echinaster (Echinaster) sepositus is one of the most abundant sea stars in western Mediterranean rocky bottoms, yet its reproductive biology remains virtually unknown. Here we report the ultrastructure of its gametogenesis over 2 consecutive years. It is a gonochoric species with an annual reproductive cycle spawning gametes in late summer and early autumn. Each arm of every individual contained two gonads (dark red in females and yellow in males). In both sexes, the gonad was a single, large sac composed of several smaller sacs. The gonad wall consisted of two multilayered sacs, outer and inner, separated by the genital haemal sinus. The histology of the gonad wall was consistent with that found in other asteroids. Oogenesis was continuous during the year, but eggs were spawned only in late summer. Oocytes were in close relationship with follicular cells that are suggested to transfer nutrients to the oocytes. Spermatogenesis was restricted to 5–6 months in spring-summer. It occurred in columns with an axial interstitial cell supporting each column, and producing processes towards the lumen that remained connected to spermatogenic cells by intercellular junctions. Developing sperm cells were found along the length of the column, while spermatozoa were found free in the testis lumen. Spermatogenesis followed the pattern described for echinoderms, to give rise to an acrosome-bearing, round-shaped spermatozoon. The histology and cytology of the reproductive process in E. sepositus followed the general pattern found for asteroids. 相似文献
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A. C. Triantaphyllou 《Journal of nematology》1985,17(1):1-5
Studies of oogenesis and spermatogenesis revealed that Meloidogyne nataliei is a diploid, amphimictic species with four (n), relatively large chromosomes, and possibly with an XX ♀-XY ♂ mechanism of sex determination. It differs considerably from all other amphimictic, or meiotically parthenogenetic, species of Meloidogyne which have 13-18 smaller chromosomes and from Meloidogyne (Hypsoperine) spartinae which has seven. Consequently, the taxonomic position of M. nataliei needs to be re-evaluated. The chromosomes of M. nataliei and their behavior during gametogenesis resemble more closely chromosomes of the genus Heterodera than those of the genus Meloidogyne. This resemblance, however, may not imply a closer phyletic relationship of M. nataliei to heteroderid nematodes. 相似文献
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Makoto Mizuno 《Phycological Research》2006,54(1):57-64
The evolution of meiotic patterns of the oogenesis and spermatogenesis in centric diatoms was inferred according to the parsimony principle. The pattern provisionally named type 1, in which one of two daughter nuclei becomes pycnotic, no cytokinesis occurs at meiosis II and two eggs are produced, was inferred to be the most primitive among extant meiotic patterns of oogenesis. It was also inferred that the pattern provisionally named 4‐2EC, in which equal cytokinesis occurs after each nuclear division and four functional haploid cells are produced, is the most primitive among extant meiotic patterns of spermatogenesis. The evolution of meiotic pattern suggests that bipolar or multipolar forms are primitive among centric diatoms. 相似文献
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Vasiliki Koutsouveli Paco Crdenas Nadiezhda Santodomingo Anabel Marina Esperanza Morato Hans Tore Rapp Ana Riesgo 《Molecular biology and evolution》2020,37(12):3485
All animals are capable of undergoing gametogenesis. The ability of forming haploid cells from diploid cells through meiosis and recombination appeared early in eukaryotes, whereas further gamete differentiation is mostly a metazoan signature. Morphologically, the gametogenic process presents many similarities across animal taxa, but little is known about its conservation at the molecular level. Porifera are the earliest divergent animals and therefore are an ideal phylum to understand evolution of the gametogenic toolkits. Although sponge gametogenesis is well known at the histological level, the molecular toolkits for gamete production are largely unknown. Our goal was to identify the genes and their expression levels which regulate oogenesis and spermatogenesis in five gonochoristic and oviparous species of the genus Geodia, using both RNAseq and proteomic analyses. In the early stages of both female and male gametogenesis, genes involved in germ cell fate and cell-renewal were upregulated. Then, molecular signals involved in retinoic acid pathway could trigger the meiotic processes. During later stages of oogenesis, female sponges expressed genes involved in cell growth, vitellogenesis, and extracellular matrix reassembly, which are conserved elements of oocyte maturation in Metazoa. Likewise, in spermatogenesis, genes regulating the whole meiotic cycle, chromatin compaction, and flagellum axoneme formation, that are common across Metazoa were overexpressed in the sponges. Finally, molecular signals possibly related to sperm capacitation were identified during late stages of spermatogenesis for the first time in Porifera. In conclusion, the activated molecular toolkit during gametogenesis in sponges was remarkably similar to that deployed during gametogenesis in vertebrates. 相似文献
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Patricia Postingel Quirino Diógenes Henrique de Siqueira-Silva Maira da Silva Rodrigues Amanda Pereira dos Santos-Silva Maria Luiza Ribeiro Delgado José Augusto Senhorini Alexandre Ninhaus-Silveira Rosicleire Veríssimo-Silveira 《Journal of fish biology》2021,99(5):1719-1728
Individuals of the same species may present different reproductive tactics depending on the environment in which they develop and mature. The present study aimed to define the gonadal development phases of males and females of Astyanax rivularis and to carry out a comparative analysis of the reproductive development of specimens captured in two isolated environments of the São Francisco River basin in Serra da Canastra, Brazil (Point 1: low vegetation and river showing calm and crystalline waters with small well formations; Point 2: current waters, and well-established areas of arboreal vegetation). Thus, the gonads of A. rivularis specimens were collected, fixed and processed with techniques for light microscopy. Five maturation phases of the females' reproductive cycle were established: immature, developing, spawning capable, regressing and regenerating. Three maturation phases of the males' reproductive cycle were observed: spawning capable, regressing, and regenerating. There are differences in the phases of gonadal development of A. rivularis between the two sampling points so that, possibly, animals upstream of the waterfall demonstrate a delay in the reproductive cycle in relation to animals downstream. 相似文献
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Jhennifer Gomes Cordeiro Jeane Rodrigues Raquel dos Santos Maira da Silva Rodrigues Rafael Henrique Nóbrega Felipe Fernando da Silva Siqueira Caio Maximino Diógenes Henrique de Siqueira-Silva 《Acta zoologica》2023,104(3):444-457
This study describes important components of the reproductive biology of the Amazonian amphibian fish Copella arnoldi. The species sex ratio biased to female 1.8 to 1 male and the length-weight relationship also shown differences between sexes (b value = 1.854 for females and 2.235 for males), although both presented allometric growth (b < 3), “being lighter for its length”. The results also show the importance of the histological analysis to describe the gametogenesis and, consequently, define the reproductive cycle of a fish species. It showed both, males and females, spawning capable during a whole year, whereas the gonadosomatic index pointed spawning capable females during the winter and summer, and spawning capable males only in the autumn. The species presents the rare type of semicystic spermatogenesis and the spermatids complete their differentiation into the tubular lumen, forming a Type I spermatozoa. Both the characteristics are described for the first time for the Lebiasinidae family. Such data can contribute to the discussions about the position of the Lebiasinidae family within the Characiform order, which still does not have a conclusion. Moreover, understand the reproductive biology of a fish species helps its preservation in its habitat and may be applied in restoration programs. 相似文献
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Lucía Fantini Nicholas W. Jeffery Paola Pierossi T. Ryan Gregory Mariela Nieves 《Biological journal of the Linnean Society. Linnean Society of London》2016,118(4):752-762
Heterochromatin distribution and chromosomal rearrangements have been proposed as the main sources of karyotype differences among species of Neotropical primates. This variability suggests that there could be differences at other smaller‐scale levels of DNA organization as well. In particular, quantitative differences between genomes result from gains and losses of individual DNA segments, and may result in varying genome sizes (C‐values) among species. In this work, we studied the genomes of 23 individuals from four species in the genus Ateles (Primates: Platyrrhini): A. chamek, A. paniscus, A. belzebuth, and A. geoffroyi. We analyzed genome size and its relationship with the presence of chromosomal rearrangements and patterns of heterochromatin distribution. The C‐value presented in this work for Ateles chamek is the first estimate for this species (3.09 ± 0.23 pg), whereas our estimates for A. belzebuth (2.88 ± 0.06 pg) and A. geoffroyi (3.19 ± 0.24 pg) differed from those previously published. Fluorescent in situ hybridization (FISH) and interspecies comparativegenomic hybridization (iCGH) analyses revealed that differences in genome size among species relate to localized blocks in both heterochromatic and euchromatic regions, the latter of which appear to be genetically unstable. There were also quantitative differences in Y chromosome content. It remains to be seen whether the chromosomal characteristics of Ateles here discussed are common to platyrrhine monkeys, but it is clear that these monkeys exhibit some intriguing genomic features worthy of additional exploration. 相似文献
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Parisha P. Shah Wenjian Lv Joshua H. Rhoades Andrey Poleshko Deepti Abbey Matthew A. Caporizzo Ricardo Linares-Saldana Julie G. Heffler Nazish Sayed Dilip Thomas Qiaohong Wang Liam J. Stanton Kenneth Bedi Michael P. Morley Thomas P. Cappola Anjali T. Owens Kenneth B. Margulies David B. Frank Rajan Jain 《Cell Stem Cell》2021,28(5):938-954.e9
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