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  • 1
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    Online Resource
    Isolation, characterization, and in vitro and in vivo differentiation of putative thecal stem cells
    Proceedings of the National Academy of Sciences ; 2007
    In:  Proceedings of the National Academy of Sciences Vol. 104, No. 30 ( 2007-07-24), p. 12389-12394
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 104, No. 30 ( 2007-07-24), p. 12389-12394
    Abstract: Although ovarian theca cells play an indispensable role in folliculogenesis by providing follicular structural integrity and steroid substrates for estrogen production, little information is available about their recruitment, growth, and differentiation because their immature forms have not been identified. We have isolated putative thecal stem cells with the ability to self-renew and differentiate in vivo and in vitro . They are similar to fibroblasts in morphology and proliferate in vitro as round colonies with a homogenous cell population. They were induced to differentiate into early precursors and steroidogenic cells in a stepwise manner after treatment with serum, luteinizing hormone, and paracrine factors from granulosa cells. At each differentiation step, these cells displayed appropriate gene expression and morphological markers and later secreted androstenedione. The fully mature morphology was achieved by coculture with isolated granulosa cells. When transplanted into the ovaries, the putative thecal stem cells colonized exclusively in the ovarian interstitium and the thecal layer of follicles as differentiated cells. Thus, thecal stem cells appear to be present in neonatal ovaries and can be isolated, purified, and induced to differentiate in vitro . Thecal stem cells could provide an invaluable in vitro experimental system to study interactions among the oocytes, granulosa cells, and theca cells during normal folliculogenesis and to study ovarian pathology caused by theca cell dysfunction.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0703787104
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2007
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    detail.hit.zdb_id: 1461794-8
    SSG: 11
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  • 2
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    Online Resource
    Production of knockout mice by random or targeted mutagenesis in spermatogonial stem cells
    Proceedings of the National Academy of Sciences ; 2006
    In:  Proceedings of the National Academy of Sciences Vol. 103, No. 21 ( 2006-05-23), p. 8018-8023
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 103, No. 21 ( 2006-05-23), p. 8018-8023
    Abstract: Stem cells represent a unique population of cells with self-renewal capacity. Although they are important therapeutic targets, the genetic manipulation of tissue-specific stem cells has been limited, which complicates the study and practical application of these cells. Here, we demonstrate successful gene trapping and homologous recombination in spermatogonial stem cells. Cultured spermatogonial stem cells were transfected with gene trap or gene targeting vectors. Mutagenized stem cells were expanded clonally by drug selection. These cells underwent spermatogenesis and produced heterozygous offspring after transplantation into the seminiferous tubules of infertile mouse testes. Heterozygous mutant mice were intercrossed to produce homozygous gene knockouts. Using this strategy, the efficiency of homologous recombination for the occludin gene locus was 1.7% using a nonisogenic DNA construct. These results demonstrate the feasibility of altering genes in tissue-specific stem cells in a manner similar to embryonic stem cells and have important implications for gene therapy and animal transgenesis.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0601139103
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2006
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
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  • 3
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    Online Resource
    Rad6-Bre1-mediated histone H2B ubiquitylation modulates the formation of double-strand breaks during meiosis
    Proceedings of the National Academy of Sciences ; 2004
    In:  Proceedings of the National Academy of Sciences Vol. 101, No. 31 ( 2004-08-03), p. 11380-11385
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 101, No. 31 ( 2004-08-03), p. 11380-11385
    Abstract: An E2 ubiquitin-conjugating enzyme, Rad6, working with an E3 ubiquitin ligase Bre1, catalyzes monoubiquitylation of histone H2B on a C-terminal lysine residue. The rad6 mutant of Saccharomyces cerevisiae shows a meiotic prophase arrest. Here, we analyzed meiotic defects of a rad6 null mutant of budding yeast. The rad6 mutant exhibits pleiotropic phenotypes during meiosis. RAD6 is required for efficient formation of double-strand breaks (DSBs) at meiotic recombination hotspots, which is catalyzed by Spo11. The mutation decreases overall frequencies of DSBs in a cell. The effect of the rad6 mutation is local along chromosomes; levels of DSBs at stronger hotspots are particularly reduced in the mutant. The absence of RAD6 has little effect on the formation of ectopic DSBs targeted by Spo11 fusion protein with a Gal4 DNA-binding domain. Furthermore, the disruption of the BRE1 as well as substitution of the ubiquitylation site of histone H2B also reduces some DSB formation similar to the rad6 . These results suggest that Rad6-Bre1, through ubiquitylation of histone H2B, is necessary for efficient recruitment and/or stabilization of a DSB-forming machinery containing Spo11. Histone tail modifications might play a role in DSB formation during meiosis.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0400078101
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2004
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 4
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    Online Resource
    Adenovirus-mediated gene delivery into mouse spermatogonial stem cells
    Proceedings of the National Academy of Sciences ; 2007
    In:  Proceedings of the National Academy of Sciences Vol. 104, No. 8 ( 2007-02-20), p. 2596-2601
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 104, No. 8 ( 2007-02-20), p. 2596-2601
    Abstract: Spermatogonial stem cells represent a self-renewing population of spermatogonia, and continuous division of these cells supports spermatogenesis throughout the life of adult male animals. Previous attempts to introduce adenovirus vectors into spermatogenic cells, including spermatogonial stem cells, have failed to yield evidence of infection, suggesting that male germ cells may be resistant to adenovirus infection. In this study we show the feasibility of transducing spermatogonial stem cells by adenovirus vectors. When testis cells from ROSA26 Cre reporter mice were incubated in vitro with a Cre-expressing adenovirus vector, Cre-mediated recombination occurred at an efficiency of 49–76%, and the infected spermatogonial stem cells could reinitiate spermatogenesis after transplantation into seminiferous tubules of infertile recipient testes. No evidence of germ-line integration of adenovirus vector could be found in offspring from infected stem cells that underwent Cre-mediated recombination, which suggests that the adenovirus vector infected the cells but did not stably integrate into the germ line. Nevertheless, these results suggest that adenovirus may inadvertently integrate into the patient's germ line and indicate that there is no barrier to adenovirus infection in spermatogonial stem cells.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0609282104
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2007
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 5
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    Online Resource
    Tid1/Rdh54 promotes colocalization of Rad51 and Dmc1 during meiotic recombination
    Proceedings of the National Academy of Sciences ; 2000
    In:  Proceedings of the National Academy of Sciences Vol. 97, No. 20 ( 2000-09-26), p. 10814-10819
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 97, No. 20 ( 2000-09-26), p. 10814-10819
    Abstract: Two RecA homologs, Rad51 and Dmc1, assemble as cytologically visible complexes (foci) at the same sites on meiotic chromosomes. Time course analysis confirms that co-foci appear and disappear as the single predominant form. A large fraction of co-foci are eliminated in a red1 mutant, which is expected as a characteristic of the interhomolog-specific recombination pathway. Previous studies suggested that normal Dmc1 loading depends on Rad51. We show here that a mutation in TID1 / RDH54 , encoding a RAD54 homolog, reduces Rad51-Dmc1 colocalization relative to WT. A rad54 mutation, in contrast, has relatively little effect on RecA homolog foci except when strains also contain a tid1 / rdh54 mutation. The role of Tid1/Rdh54 in coordinating RecA homolog assembly may be very direct, because Tid1/Rdh54 is known to physically bind both Dmc1 and Rad51. Also, Dmc1 foci appear early in a tid1 / rdh54 mutant. Thus, Tid1 may normally act with Rad51 to promote ordered RecA homolog assembly by blocking Dmc1 until Rad51 is present. Finally, whereas double-staining foci predominate in WT nuclei, a subset of nuclei with expanded chromatin exhibit individual Rad51 and Dmc1 foci side-by-side, suggesting that a Rad51 homo-oligomer and a Dmc1 homo-oligomer assemble next to one another at the site of a single double-strand break (DSB) recombination intermediate.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.97.20.10814
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2000
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 6
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    Meiotic recombination-related DNA synthesis and its implications for cross-over and non-cross-over recombinant formation
    Proceedings of the National Academy of Sciences ; 2007
    In:  Proceedings of the National Academy of Sciences Vol. 104, No. 14 ( 2007-04-03), p. 5965-5970
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 104, No. 14 ( 2007-04-03), p. 5965-5970
    Abstract: Meiotic recombination-related DNA synthesis (MRDS) was analyzed in Saccharomyces cerevisiae by specifically timed incorporation of thymidine analogs into chromosomes. Lengths and positions of incorporation tracts were determined relative to a known recombination hot spot along DNA, as was the timing and localization of incorporation relative to forming and formed synaptonemal complex in spread chromosomes. Distinct patterns could be specifically associated with the majority cross-over and non-cross-over recombination processes. The results obtained provide direct evidence for key aspects of current consensus recombination models, provide information regarding temporal and spatial relationships between non-cross-over formation and the synaptonemal complex, and raise the possibility that removal of RecA homolog Rad51 plays a key role in regulating onset of MRDS. Finally, classical observations on MRDS in Drosophila , mouse, and lily are readily mapped onto the findings presented here, providing further evidence for a broadly conserved meiotic recombination process.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0611490104
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2007
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 7
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    Online Resource
    Photoperiod and temperature separately regulate nymphal development through JH and insulin/TOR signaling pathways in an insect
    Proceedings of the National Academy of Sciences ; 2020
    In:  Proceedings of the National Academy of Sciences Vol. 117, No. 10 ( 2020-03-10), p. 5525-5531
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 10 ( 2020-03-10), p. 5525-5531
    Abstract: Insects living in the temperate zone enter a physiological state of arrested or slowed development to overcome an adverse season, such as winter. Developmental arrest, called diapause, occurs at a species-specific developmental stage, and embryonic and pupal diapauses have been extensively studied in mostly holometabolous insects. Some other insects overwinter in the nymphal stage with slow growth for which the mechanism is poorly understood. Here, we show that this nymphal period of slow growth is regulated by temperature and photoperiod through separate pathways in the cricket Modicogryllus siamensis . The former regulates the growth rate, at least in part, through the insulin / target of rapamycin (TOR) signaling pathway. Lower temperature down-regulates the expression of insulin -like peptide ( Ms’Ilp ) and Target of rapamycin ( Ms’Tor ) genes to slow down the growth rate without affecting the number of molts. The latter regulates the number of molts independent of temperature. Short days increase the number of molts through activation of the juvenile hormone (JH) pathway and down-regulation of myoglianin ( Ms’myo ), a member of the TGFβ family, which induces adult metamorphosis. In contrast, long days regulate Ms’myo expression to increase during the fifth to sixth instar to initiate adult metamorphosis. When Ms’myo expression is suppressed, juvenile hormone O-methyl transferase ( Ms’jhamt ) was up-regulated and increased molts to prolong the nymphal period even under long-day conditions. The present findings suggested that the photoperiod regulated Ms’myo , and the JH signaling pathway and the temperature-controlled insulin/TOR pathway cooperated to regulate nymphal development for overwintering to achieve seasonal adaptation of the life cycle in M. siamensis .
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1922747117
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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