scholarly journals Germinal vesicle breakdown in the Xenopus laevis oocyte : description of a transient microtubular structure

1981 ◽  
Vol 21 (1) ◽  
pp. 135-148 ◽  
Author(s):  
Denise HUCHON ◽  
Nicole CROZET ◽  
Nicole CANTENOT ◽  
R. OZON
Keyword(s):  
Xenopus Laevis ◽  
Germinal Vesicle ◽  
Xenopus Laevis Oocyte ◽  
Germinal Vesicle Breakdown

scholarly journals Cell cycle dynamics of an M-phase-specific cytoplasmic factor in Xenopus laevis oocytes and eggs.

1984 ◽  
Vol 98 (4) ◽  
pp. 1247-1255 ◽  
Author(s):  
J Gerhart ◽  
M Wu ◽  
M Kirschner
Keyword(s):  
Cell Cycle ◽  
Xenopus Laevis ◽  
Germinal Vesicle ◽  
Small Scale ◽  
Xenopus Laevis Oocytes ◽  
Germinal Vesicle Breakdown ◽  
Cytoplasmic Factor ◽  
M Phase ◽  
Cytostatic Factor ◽  
Meiotic Cycle

We have examined the regulation of maturation-promoting factor (MPF) activity in the mitotic and meiotic cell cycles of Xenopus laevis eggs and oocytes. To this end, we developed a method for the small scale extraction of eggs and oocytes and measured MPF activity in extracts by a dilution end point assay. We find that in oocytes, MPF activity appears before germinal vesicle breakdown and then disappears rapidly at the end of the first meiotic cycle. In the second meiotic cycle, MPF reappears before second metaphase, when maturation arrests. Thus, MPF cycling coincides with the abbreviated cycles of meiosis. When oocytes are induced to mature by low levels of injected MPF, cycloheximide does not prevent the appearance of MPF at high levels in the first cycle. This amplification indicates that an MPF precursor is present in the oocyte and activated by posttranslational means, triggered by the low level of injected MPF. Furthermore, MPF disappears approximately on time in such oocytes, indicating that the agent for MPF inactivation is also activated by posttranslational means. However, in the absence of protein synthesis, MPF never reappears in the second meiotic cycle. Upon fertilization or artificial activation of normal eggs, MPF disappears from the cytoplasm within 8 min. For a period thereafter, the inactivating agent remains able to destroy large amounts of MPF injected into the egg. It loses activity just as endogenous MPF appears at prophase of the first mitotic cycle. The repeated reciprocal cycling of MPF and the inactivating agent during cleavage stages is unaffected by colchicine and nocodazole and therefore does not require the effective completion of spindle formation, mitosis, or cytokinesis. However, MPF appearance is blocked by cycloheximide applied before mitosis; and MPF disappearance is blocked by cytostatic factor. In all these respects, MPF and the inactivating agent seem to be tightly linked to, and perhaps participate in, the cell cycle oscillator previously described for cleaving eggs of Xenopus laevis (Hara, K., P. Tydeman, and M. Kirschner, 1980, Proc. Natl. Acad. Sci. USA, 77:462-466).

Diacylglycerol production in Xenopus laevis oocytes after microinjection of p21ras proteins is a consequence of activation of phosphatidylcholine metabolism

1990 ◽  
Vol 10 (1) ◽  
pp. 333-340
Author(s):  
J C Lacal
Keyword(s):  
Xenopus Laevis ◽  
Inositol Phosphates ◽  
Biological Response ◽  
Germinal Vesicle ◽  
Xenopus Laevis Oocytes ◽  
Ras Proteins ◽  
Germinal Vesicle Breakdown ◽  
Second Peak ◽  
Synthesis And Degradation ◽  
Phosphatidylcholine Metabolism

Microinjection of p21Ha-ras proteins into Xenopus laevis oocytes induces a rapid increase of 1,2-diacylglycerol (DAG) levels. The observed alterations in DAG levels were consistent with the ability of the protein to induce maturation, measured by germinal vesicle breakdown (GVBD). Both the increase in DAG levels and GVBD activity were dependent on the ability of the proteins to undergo membrane translocation. Alterations of DAG levels or GVBD activity did not correlate with changes in the levels of inositol phosphates. However, at minimal doses sufficient to achieve maximal biological response, a biphasic increase in the amounts of phosphocholine and CDP-choline was observed. The first burst of phosphocholine and CDP-choline preceded the increase in DAG levels. The second peak paralleled the appearance of DAG. Choline kinase activity was also increased in oocyte extracts after p21ras microinjection. These results suggest that both the synthesis and degradation of phosphatidylcholine are activated after microinjection of ras proteins into Xenopus oocytes, resulting in a net production of DAG.

Lysophosphatidic acid induces a pertussis toxin-sensitive Ca(2+)-activated Cl- current in Xenopus laevis oocytes

1992 ◽  
Vol 263 (4) ◽  
pp. C896-C900 ◽  
Author(s):  
M. E. Durieux ◽  
M. N. Salafranca ◽  
K. R. Lynch ◽  
J. R. Moorman
Keyword(s):  
Xenopus Laevis ◽  
Pertussis Toxin ◽  
Lysophosphatidic Acid ◽  
Reversal Potential ◽  
Germinal Vesicle ◽  
Membrane Receptor ◽  
Xenopus Laevis Oocytes ◽  
Germinal Vesicle Breakdown ◽  
Specific Membrane ◽  
Specific Membrane Receptor

Lysophosphatidic acid (LPA) induces a Ca(2+)-activated Cl- current in defolliculated Xenopus laevis oocytes. The response appears mediated by a specific membrane receptor, because no current is induced when related compounds [phosphatidic acid (PA), lysophosphatidylcholine (LPC), and lysophosphatidylserine (LPS)] are applied extracellularly or when LPA is injected intracellularly. Incubation in pertussis toxin prevents the response. The response is mediated by a Ca(2+)-activated Cl- current because 1) it is abolished by intracellular ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA; 5 mM) but not affected by changes in extracellular Ca2+ concentration and 2) the reversal potential becomes more positive at lower Cl- concentrations. Suramin (2 mM) blocks the LPA-induced current, but PA, LPS, LPC, and the platelet-activating factor antagonist WEB-2086 do not. The response is dose dependent for LPA concentrations from 10(-8) to 10(-3) M. Incubation of oocytes in LPA does not induce germinal vesicle breakdown. These findings suggest that this novel oocyte response to LPA is mediated by a specific membrane receptor linked to a pertussis toxin-sensitive G protein.

Induction of germinal vesicle breakdown in Xenopus laevis oocytes: synergistic action of progesterone and insulin

1984 ◽  
Vol 101 (1) ◽  
pp. 7-12 ◽  
Author(s):  
C. Le Goascogne ◽  
S. Hirai ◽  
E.-E. Baulieu
Keyword(s):  
Xenopus Laevis ◽  
Physiological Role ◽  
Germinal Vesicle ◽  
Xenopus Laevis Oocytes ◽  
Germinal Vesicle Breakdown ◽  
Low Sensitivity ◽  
Dose Dependent ◽  
Subthreshold Level ◽  
Insulin Like Growth Factors

ABSTRACT Progesterone is the hormone that reinitiates the meiotic division of amphibian oocytes and insulin and insulin-like growth factors are also active on defolliculated oocytes in vitro. We have studied Xenopus laevis oocytes (stage 5–6) of different hormonal sensitivities, obtained from unstimulated and from human chorionic gonadotrophin-stimulated females. Some oocytes from unstimulated females were also precultured with a subthreshold level of progesterone. A dose-dependent potentiating effect of the action of progesterone was observed with insulin, and this was particularly remarkable in low-sensitivity oocytes. Since in the presence of insulin, the optimally effective concentration of progesterone was much reduced (as an example from 1 μmol/l to 50 nmol/l), it is suggested that an insulin-like growth factor may play a physiological role in the reinitiation of meiosis in ovaries. J. Endocr. (1984) 101, 7–12

scholarly journals Diacylglycerol production in Xenopus laevis oocytes after microinjection of p21ras proteins is a consequence of activation of phosphatidylcholine metabolism.

1990 ◽  
Vol 10 (1) ◽  
pp. 333-340 ◽  
Author(s):  
J C Lacal
Keyword(s):  
Xenopus Laevis ◽  
Inositol Phosphates ◽  
Biological Response ◽  
Germinal Vesicle ◽  
Xenopus Laevis Oocytes ◽  
Ras Proteins ◽  
Germinal Vesicle Breakdown ◽  
Second Peak ◽  
Synthesis And Degradation ◽  
Phosphatidylcholine Metabolism

Microinjection of p21Ha-ras proteins into Xenopus laevis oocytes induces a rapid increase of 1,2-diacylglycerol (DAG) levels. The observed alterations in DAG levels were consistent with the ability of the protein to induce maturation, measured by germinal vesicle breakdown (GVBD). Both the increase in DAG levels and GVBD activity were dependent on the ability of the proteins to undergo membrane translocation. Alterations of DAG levels or GVBD activity did not correlate with changes in the levels of inositol phosphates. However, at minimal doses sufficient to achieve maximal biological response, a biphasic increase in the amounts of phosphocholine and CDP-choline was observed. The first burst of phosphocholine and CDP-choline preceded the increase in DAG levels. The second peak paralleled the appearance of DAG. Choline kinase activity was also increased in oocyte extracts after p21ras microinjection. These results suggest that both the synthesis and degradation of phosphatidylcholine are activated after microinjection of ras proteins into Xenopus oocytes, resulting in a net production of DAG.

Environmental (anti-)androgenic chemicals affect germinal vesicle breakdown (GVBD) of Xenopus laevis oocytes in vitro

2014 ◽  
Vol 28 (3) ◽  
pp. 426-431 ◽  
Author(s):  
Shan Cao ◽  
Wei Xu ◽  
Qin-Qin Lou ◽  
Yin-Feng Zhang ◽  
Ya-Xian Zhao ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Germinal Vesicle ◽  
Xenopus Laevis Oocytes ◽  
Germinal Vesicle Breakdown

scholarly journals On the synthesis and destruction of A- and B-type cyclins during oogenesis and meiotic maturation in Xenopus laevis.

1991 ◽  
Vol 114 (4) ◽  
pp. 755-765 ◽  
Author(s):  
H Kobayashi ◽  
J Minshull ◽  
C Ford ◽  
R Golsteyn ◽  
R Poon ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Oocyte Maturation ◽  
Posttranslational Modifications ◽  
Germinal Vesicle ◽  
Stage Iv ◽  
Cyclin B1 ◽  
Meiotic Maturation ◽  
Germinal Vesicle Breakdown ◽  
Previous Level ◽  
Made In

We have measured the levels of cyclin mRNAs and polypeptides during oogenesis, progesterone-induced oocyte maturation, and immediately after egg activation in the frog, Xenopus laevis. The mRNA for each cyclin is present at a constant level of approximately 5 x 10(7) molecules per oocyte from the earliest stages of oogenesis until after fertilization. The levels of polypeptides show more complex patterns of accumulation. The B-type cyclins are first detectable in stage IV and V oocytes. Cyclin B2 polypeptide is present at approximately 2 x 10(9) molecules (150 pg) per oocyte by stage VI. The amount increases after progesterone treatment, but returns to its previous level after GVBD and undergoes no further change until it is destroyed at fertilization. Cyclin B1 is present at 4 x 10(8) molecules per oocyte in stage VI oocytes, and rises steadily during maturation, ultimately reaching similar levels to cyclin B2 in unfertilized eggs. Unlike the B-type cyclins, cyclin A is barely detectable in stage VI oocytes, and only starts to be made in significant amounts after oocytes are exposed to progesterone. A portion of all the cyclins are destroyed after germinal vesicle breakdown (GVBD), and cyclins B1 and B2 also experience posttranslational modifications during oocyte maturation. Progesterone strongly stimulates both cyclin and p34cdc2 synthesis in these oocytes, but whereas cyclin synthesis continues in eggs and after fertilization, synthesis of p34cdc2 declines strongly after GVBD. The significance of these results is discussed in terms of the activation and inactivation of maturation-promoting factor.

scholarly journals Meiotic induction by Xenopus cyclin B is accelerated by coexpression with mosXe.

1991 ◽  
Vol 11 (3) ◽  
pp. 1713-1717 ◽  
Author(s):  
R S Freeman ◽  
S M Ballantyne ◽  
D J Donoghue
Keyword(s):  
Xenopus Laevis ◽  
Antisense Oligonucleotide ◽  
Xenopus Oocytes ◽  
Germinal Vesicle ◽  
Cyclin B1 ◽  
Cyclin B ◽  
Germinal Vesicle Breakdown ◽  
The Relationship ◽  
Maturation Promoting Factor

We have investigated the relationship between Xenopus laevis c-mos (mosXe) and the cyclin B component of maturation-promoting factor. Microinjection of Xenopus oocytes with in vitro-synthesized RNAs encoding Xenopus cyclin B1 or cyclin B2 induces the progression of meiosis, characterized by germinal vesicle breakdown (GVBD). By preinjecting oocytes with a mosXe-specific antisense oligonucleotide, we show that GVBD induced by cyclin B does not require expression of the mosXe protein. GVBD induced by cyclin B proceeds significantly faster than GVBD induced by progesterone or MosXe. However, coinjection of RNAs encoding cyclin B1 or cyclin B2 with mosXe RNA results in a 2.5- to 3-fold acceleration in GVBD relative to that induced by cyclin B alone. This acceleration of GVBD does not correlate with changes in the level of cyclin B1 and cyclin B2 phosphorylation.

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