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  • 1
    Electronic Resource
    Electronic Resource
    The Mos/MAPK pathway is involved in metaphase II arrest as a cytostatic factor but is neither necessary nor sufficient for initiating oocyte maturation in goldfish (2000)
    Springer
    Development genes and evolution 210 (2000), S. 416-425 
    Details
    ISSN: 1432-041X
    Keywords: Key words Cytostatic factor ; MAP kinase ; Mos ; Maturation-promoting factor ; Oocyte maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Mos plays a crucial role in meiotic cell division in vertebrates. In Xenopus, Mos is involved in the initiation of oocyte maturation as an initiator and in the arrest at the metaphase II stage (MII) as a component of the cytostatic factor (CSF). The function of Mos is mediated by MAP kinase (MAPK). We investigated the function of the Mos/MAPK pathway during goldfish oocyte maturation induced by 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP), a natural maturation-inducing hormone in fishes. Mos was absent in immature goldfish oocytes. It appeared before the onset of germinal vesicle breakdown (GVBD), increased to a maximum in mature oocytes arrested at MII and disappeared after fertilization. MAPK was activated after Mos synthesis but before maturation-promoting factor (MPF) activation, and its activity reached maximum at MII. Injection of either Xenopus or goldfish c-mos mRNA into one blastomere of 2-cell-stage Xenopus and goldfish embryos induced metaphase arrest, suggesting that goldfish Mos has a CSF activity. Injection of constitutively active Xenopus c-mos mRNA into immature goldfish oocytes induced MAPK activation, but neither MPF activation nor GVBD occurred. Conversely, the injection of goldfish c-mos antisense RNA inhibited both Mos synthesis and MAPK activation in the 17α,20β-DP-treated oocytes, but these oocytes underwent GVBD. These results indicate that the Mos/MAPK pathway is not essential for initiating goldfish oocyte maturation despite its general function as a CSF. We discuss the general role of Mos/MAPK during oocyte maturation, with reference to the difference in contents of inactive MPF (pre-MPF) stored in immature oocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270000083
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  • 2
    Electronic Resource
    Electronic Resource
    DMY is a Y-specific DM-domain gene required for male development in the medaka fish (2002)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 417 (2002), S. 559-563 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Although the sex-determining gene Sry has been identified in mammals, no comparable genes have been found in non-mammalian vertebrates. Here, we used recombinant breakpoint analysis to restrict the sex-determining region in medaka fish (Oryzias latipes) to a 530-kilobase (kb) stretch of the Y ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature751
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  • 3
    Electronic Resource
    Electronic Resource
    Meiosis-Reinitiation-Inducing Factor of Tetrahymena Functions Upstream of M-Phase-Promoting Factor (1992)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 39 (1992), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Reinitiation of meiosis (maturation) of amphibian Bufo and Xenopus oocytes can be induced if Tetrahymena extract is injected into them. The activity differed from M-phase-promoting factor, because action of the former factor on the induction of maturation was inhibited by treatment of the oocytes with cycloheximide. Activity of M-phase-promoting factor was not detected in Tetrahymena extract regardless of the presence of cdc2 homologues in the extract. However, cycloheximide-resistant-maturation-inducing activity appeared in the recipients, when the maturation was induced by injection of Tetrahymena extract. Immunoblots using antibodies against cdc2 showed that injection of Tetrahymena extract induced fast mobility of the recipient cdc2 in the presence of the recipient protein synthesis. The same mobility shift of the cdc2 was also induced when M-phase-promoting factor containing Xenopus oocyte extract was injected into immature oocytes or when the immature oocyte extract was treated with alkaline phosphatase. These results indicate that meiosis-reinitiation-inducing factor of Tetrahymena functions upstream of M-phase-promoting factor to induce dephosphorylation of the recipient cdc2. Tetrahymena cdc2 homologues also showed fast mobility when the Tetrahymena extract was treated with alkaline phosphatase. Preliminary experiments showed that the meiosis-reinitiation-inducing factor of Tetrahymena was a soluble protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1992.tb04449.x
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  • 4
    Electronic Resource
    Electronic Resource
    A comparative study on stainability of preprophase bands by the PSTAIR antibody (1996)
    Springer
    Journal of plant research 109 (1996), S. 185-192 
    Details
    ISSN: 1618-0860
    Keywords: cdc2 kinase ; Higher plants ; Microtubule ; Preprophase band ; PSTAIR antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The detectability of preprophase bands (PPBs) by antibody to PSTAIR sequence, which is found in cyclin-dependent kinases and is perfectly conserved in the p34 cdc2 kinase from all known sources, was compared among root tip cells of 12 plant species and cultivars. Although more than 80% of prophase cells in all species examined had PPBs of microtubules (MTs), the detectability of PPBs by anti-PSTAIR varied from 0% to 88% depend on species examined. The detectability of PPBs by the antibody to PSTAIR was as high as that by antibody to tubulin inAllium cepa, A. fistulosum andA. tuberosum. InTriticum andPisum, the detectability varied greatly among cultivars. Only few faint PPBs could be detectable inChrysanthemum, and no PPBs were seen inHibiscus using anti-PSTAIR. The PSTAIR antibody recognized single (Hordeum, Triticum Zea) or multiple (Allium, Hibiscus, Pisum) bands around 34 kDa on protein blots of root tip exracts. PPBs of anti-PSTAIR cross reactive molecules were detectable in one fourth of the prophase cells ofPisum (cv. Snack) by the conventional method. However, the detectability of PPBs inPisum increased to 80% when the method for the PSTAIR-fluorescence was modified, suggesting that the low detectability of PPBs by anti-PSTAIR may not be due to genuine differences between species or cultivars, but may be the result of variable staining.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02344544
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  • 5
    Electronic Resource
    Electronic Resource
    Cyclin-dependent kinase 2 (cdk2) in the murine cdc2 kinaseTS mutant (1992)
    Springer
    Somatic cell and molecular genetics 18 (1992), S. 403-408 
    Details
    ISSN: 1572-9931
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Kinases of the mammalian cdc2 family including cdk2 (cyclin-dependent kinase 2) are thought to be involved in both the G2/M transition and DNA replication. To investigate the role of cdc2 kinase and cdk2 in cell cycle progression, murine tsFT210 cells bearing a temperaturesensitive cdc2 mutation were used. These kinases were purified by column chromatography, using a peptide with the consensus phosphorylation site of cdc2 kinase as the substrate. In this mutant, cdc2 kinase activity was temperature sensitive and cdk2 activity was not. At the restrictive temperature, the mutant was only arrested in the G2 phase and not in the G2-S phase, suggesting that cdk2 did not compensate for cdc2 kinase at the G2/M transition but did function at the G1-S phase. This suggestion was supported by the finding that transfection of cdk2 cDNA did not improve the growth of the mutant cell line at the restrictive temperature, although transfection of cdc2 cDNA did.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01233079
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  • 6
    Electronic Resource
    Electronic Resource
    Differentiation and development of Leydig cells, and changes of testosterone levels during testicular differentiation in tilapiaOreochromis niloticus (1989)
    Springer
    Fish physiology and biochemistry 7 (1989), S. 211-219 
    Details
    ISSN: 1573-5168
    Keywords: histology ; ultrastructure ; testicular differentiation ; Leydig cell ; gonad ; spermatogonia ; reproduction ; testosterone ; tilapia ; steroid producing cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Initial appearance and development of Leydig cells (LCs) during testicular differentiation in tilapia,Oreochromis niloticus, were investigated histologically. In addition, changes of testosterone levels in gonadal tissue and serum were examined by radioimmunoassay. In the gonads of fry at 23–26 days after hatching, initial testicular differentiation was confirmed by the observation of the differentiation of connective tissues into tissues which are characteristic of the adult testis. LCs, which were identified by the ultrastructural features (a moderate number of mitochondria with tubular cristae, well developed smooth endoplasmic reticulum and many free ribosomes) appeared initially at the time of testicular differentiation. LCs increased in number rapidly in the testes of fish at 70 days after hatching. Concomitant with this increase, spermatogonia increased in number. Testosterone was detectable in the fish at 40–50 days after hatching, but levels in tissue and serum were low. Testosterone levels increased gradually in the fish beginning at 70 days after hatching and increased still more at 100–150 days accompanying active spermatogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004709
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  • 7
    Electronic Resource
    Electronic Resource
    Diurnal rhythm of serum steroid hormone levels in the Japanese whiting, Sillago japonica, a daily-spawning teleost (1990)
    Springer
    Fish physiology and biochemistry 8 (1990), S. 329-338 
    Details
    ISSN: 1573-5168
    Keywords: final oocyte maturation ; maturation-inducing steroid ; 17α,20β-dihydroxy-4-pregnen-3-one ; vitellogenesis ; estradiol-17β ; daily spawning ; Japanese whiting ; marine teleost
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ovarian developmental stages and serum steroid hormone levels were examined at six different times of day (0100, 0600, 1000, 1300, 1600, 2000 h) in a marine teleost, the Japanese whiting Sillago japonica, which has an asynchronous-type ovary containing oocytes at various stages of development and spawns every day during a period ranging up to three months. The largest oocytes in the ovaries at the active vitellogenic or post-vitellogenic stages were found between 0100 and 1300 h. Oocyte maturation indicated by germinal vesicle breakdown (GVBD) occurred at 1600 h, and ovulated oocytes were observed in the ovaries collected at 2000 h. These processes were accompanied by a significant daily change in serum steroid hormone levels. The serum level of estradiol-17β showed a peak in fish with mature oocytes sampled at 1600 h. In these fish, the second-largest oocytes in the ovaries were at the initial stage of vigorous vitellogenesis, the secondary yolk stage. Therefore the highest level of serum estradiol-17β was considered to be due to the second-largest oocytes. Testosterone levels remained low and constant throughout the experimental period. The serum levels of 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-diOHprog) peaked at 1600 h at which time all fish had mature oocytes. These results indicate that the Japanese whiting possesses a diurnal rhythm of oocyte development including vitellogenesis, oocyte maturation and ovulation, and further suggest that daily cycles in oocyte growth and maturation which simultaneously take place in an ovary are regulated by diurnal secretions of estradiol-17β and the maturation-inducing steroid, 17α,20β-diOHprog.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00003428
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  • 8
    Electronic Resource
    Electronic Resource
    Histological and ultrastructural evidence for the role of gonadal steroid hormones in sex change in the protogynous wrasse Thalassoma duperrey (1989)
    Springer
    Environmental biology of fishes 24 (1989), S. 117-136 
    Details
    ISSN: 1573-5133
    Keywords: Behavior ; Coral reef fish ; Hermaphroditism ; Initial-phase ; Labridae ; Leydig cells ; Oocytes ; Protogyny ; Reproduction ; Spermatogonia ; Terminal-phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The process of sex change in the protogynous wrasse, Thalassoma duperrey, was investigated through histological and ultrastructural observations on the gonads of females changing sex to male. Changes in plasma steroid levels concomitant with structural changes were measured by radioimmunoassay. The process of sex change from ovary to testis was divided into six stages on the basis of changes in the structure of the germinal and somatic elements. Ovaries of females were filled with vitellogenic oocytes during the breeding season, but contained no spermatogenic tissue (Stage 1). At the commencement of sex change (Stage 2), vitellogenic oocytes began to degenerate, and were ingested by macrophagous cells. This stage was accompanied by a rapid drop in plasma levels of estradiol-17β. Thereafter, previtellogenic oocytes (Stage 3) also began to degenerate, and aggregations of stromal tissue, and loose connective tissue were observed in the central region of the lamellae. Steroid producing cells (Leydig cells), developed at the border of this loose connective tissue. Presumed spermatogonia proliferated on the periphery of the lamellae, and Leydig cells increased in size and number (Stage 4). Spermatogonia formed cysts, and underwent spermatogenesis (Stage 5). Finally, sex change to male was considered complete, with the beginning of active spermatogenesis and spermiation (Stage 6). Plasma levels of testosterone remained low throughout the sex change, but a second androgen, 11-ketotestosterone increased gradually in parallel to the increased numbers of Leydig cells and spermatogonia. Preliminary in vitro incubation of gonads with salmon gonadotropin, revealed that sex-changed males had higher levels of 11-ketotestosterone production than did females, while females had higher levels of estradiol-17β production than did males. Production of both these steroids increased in a dose-related fashion with increasing doses of gonadotropin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001282
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  • 9
    Electronic Resource
    Electronic Resource
    Isolation and expression of rainbow trout (Oncorhynchus mykiss) ovarian cDNA encoding 3β-hydroxysteroid dehydrogenase/Δ5−4-isomerase (1993)
    Springer
    Fish physiology and biochemistry 11 (1993), S. 273-279 
    Details
    ISSN: 1573-5168
    Keywords: rainbow trout ; ovarian steroidogenesis ; 3β-hydroxysteroid dehydrogenase/Δ5−4-isomerase ; cDNA cloning ; expression in COS-1 cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Abstract A distinct shift in steroidogenesis from testosterone to 17α-hydroxyprogesterone occurs in the salmonid ovarian thecal cell layers immediately prior to oocyte maturation, and is a prerequisite for the production of 17α,20β-dihydroxy-4-pregnen-3-one (maturation-inducing hormone of salmonid fishes) by granulosa cells during oocyte maturation. 17α-Hydroxylase/17,20-lyase cytochrome P-450 (P-45017α) and 3β-hydroxysteroid dehydrogenase/Δ5−4-isomerase (3β-HSD) are the two major steroidogenic enzymes involved in the production of 17α-hydroxyprogesterone and testosterone. Using mammalian cDNA probes, we isolated and characterized full-length cDNAs encoding these two enzymes from a rainbow trout (Oncorhynchus mykiss) ovarian thecal cell cDNA library. The cloning of 2.4-kilobase cDNA encoding P-45017α and transient expression of this clone in nonsteroidogenic monkey kidney tumor COS-1 cells have recently been reported (Sakai et al. 1992). We have isolated a 1.4-kilobase cDNA which is hybridized to the mammalian 3β-HSD cDNAs. Expression of this cDNA in COS-1 cells led to the production of an enzyme which is capable of converting dehydroepiandrosterone to androstenedione. In this study, enzymatic activities and expression of rainbow trout ovarian P-45017α and 3β-HSD are discussed in relation of the steroidogenic shift occurring in the ovarian follicle layers.
    Notes: Résumé Un net changement de la stéroïdogenèse, passant de la production de testostérone à celle de 17α-hydroxy-progestérone, apparait dans les cellules ovariennes de la thèque des salmonidés, juste avant la maturation ovocytaire. Ce changement est un prérequis pour la production de 17α,20β-dihydroxy-4-pregnene-3-one (stéroïde inducteur de la maturation chez les salmonidés), par les cellules de la granulosa, durant la maturation ovocytaire. Le cytochrome P-450 portant l'activité 17α-hydroxylase/17,20-lyase (P-45017α) et la 3β-hydroxystéroïde déshydrogénase/Δ5−4-isomérase (3β-HSD) sont les deux enzymes stéroïdogènes majeures impliquées dans la synthèse de la 17α-hydroxyprogestérone et de la testostérone. En utilisant des sondes ADNc de mammifère, nous avons isolé et caractérisé un ADNc complet codant pour ces deux enzymes, à partir d'une librairie d'ADNc de cellules ovariennes thèquales de truite arc-en-ciel (Oncorhynchus mykiss). Le clonage d'un ADNc, de 2,4 kilobase, codant pour le P-45017α, et l'expression transitoire de ce clone dans des cellules non stéroïdogènes de tumeur de rein, COS-1, de singe, ont été récemment rapportés (Sakai et al. 1992). Nous avons isolé un ADNc de 1,4 kilobase qui s'hybride avec l'ADNc mammalien de la 3β-HSD. L'expression de cet ADNc, dans les cellules COS-1, conduit à la production d'une enzyme capable de convertir la déhydroépiandrostérone en androsténédione. Une discussion est faite sur l'évolution des activités enzymatiques et de l'expression de la P-45017α et de la 3β-HSD, dans l'ovaire de truite arc-en-ciel, en rapport avec la modification de la stéroïdogenèse apparaissant dans les enveloppes du follicule ovarien.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004575
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  • 10
    Electronic Resource
    Electronic Resource
    Specific binding of [3H]17α,20β-dihydroxy-4-pregnen-3-one to oocyte cortices of rainbow trout (Oncorhynchus mykiss) (1993)
    Springer
    Fish physiology and biochemistry 11 (1993), S. 15-24 
    Details
    ISSN: 1573-5168
    Keywords: meiotic maturation ; 17α,20β-dihydroxy-4-pregnen-3-one ; salmonids ; steroid receptor ; membrane receptor ; solubilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Abstract Specific binding of [3H]17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP) to plasma membranes prepared from defolliculated oocytes of rainbow trout (Onchorhynchus mykiss) was identified and characterized. Binding was rapid and reached equilibrium in 30 min. 17α,20β-DP strongly inhibited [3H] 17α,20β-DP binding in a competitive manner. Scatchard analysis revealed two different binding sites: a high affinity binding site with a Kd of 18 nM and a Bmax of 0.2 pmoles/mg protein; and a low affinity binding site with a Kd of 0.5 μM and a Bmax of 1 pmoles/mg protein. This binding activity was successfully solubilized with n-heptyl-β-D-thioglucoside. [3H]17α,20β-DP binding to solubilized preparations reached equilibrium in 1h, and was competitively inhibited with 17α,20β-DP and 17α,20β,21-trihydroxy-4-pregnen-3-one. However, Scatchard analysis showed a single binding site with a Kd of 0.3 μM. The reason for the disappearance of the high affinity binding site in solubilized preparations remains unclear. These results demonstrate that a specific binding site for 17α,20β-DP exists in the plasma membrane of rainbow trout oocytes.
    Notes: Résumé Une liaison spécifique de le [3H]17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP), avec des membranes plasmiques d'ovocytes défollicularisés de truite arc-en-ciel (Onchorhynchus mykiss), a été identifiée et caractérisée. Sa cinétique est rapide et atteint son équilibre en 30 minutes. Le 17α,20β-DP inhibe fortement, et de manière compétitive, la liaison de la [3H] 17α,20β-DP. Une étude de Scatchard a mis en évidence deux sites diffŕents de liaison: un site de forte affinité, de Kd 18 nM et de Bmax 0,2 pmoles/mg de protéine; et un site de faible affinité, de Kd 0,5 μM et de Bmax 1 pmoles/mg de protéine. L'activité de liaison a été solubilisée, avec succés, par le n-heptyl-β-D-thioglucoside. Dans la fraction soluble, la liaison de le [3H]17α,20β-DP atteint un équilibre en 1h.; et elle est complétement inhibiée par la 17α,20β-DP et le 17α,20β,21-trihydroxy-4-pregnen-3-one. Cependant, une étude de Scatchard ne permet de déceler qu'un seul site de liaison, de Kd 0,3 μM. La disparition du site de liaison de forte affinité dans la fraction soluble reste inexpliquée. Ces résultats démontrent l'existence d'un site spécifique de liaison du 17α,20β-DP dans les membranes plasmiques des ovocytes de truite arc-en-ciel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004546
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