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J Gautier

Publications and source records attributed to J Gautier.

At least 55 records · Page 3Linked to original sources
PubMed1988

Purified maturation-promoting factor contains the product of a Xenopus homolog of the fission yeast cell cycle control gene cdc2+.

In the fission yeast S. pombe, the Mr = 34 kd product of the cdc2+ gene (p34cdc2) is a protein kinase that controls entry into mitosis. In Xenopus oocytes and other cells, maturation-promoting factor (MPF) appears in late G2 phase and is able to cause entry into mitosis. Purified MPF consists of two major proteins of Mr approximately equal to 32 kd and 45 kd and expresses protein kinase activity. We report here that antibodies to S. pombe p34cdc2 are able to immunoblot and immunoprecipitate the approximately equal to 32 kd component of MPF from Xenopus eggs. The Mr approximately equal to 32 kd and 45 kd proteins exist as a complex that expresses protein kinase activity. These findings indicate that a Xenopus p34cdc2 homolog is present in purified MPF and suggest that p34cdc2 is a component of the control mechanism initiating mitosis generally in eukaryotic cells.

Animals↗
PubMed1988

Differential cytolocalization of prosomes in axolotl during oogenesis and meiotic maturation.

The prosomes, a novel type of small RNA-protein complex previously characterized in avian and mammalian cells, were isolated from axolotl (Ambystoma mexicanum) oocytes and identified by sedimentation analysis and protein composition. The prosomal nature of these particles was further ascertained by immunoblot analysis with anti-duck prosome monoclonal antibodies. By in vitro [35S]methionine labelling, de novo synthesis of prosomal proteins could be detected neither during oogenesis nor meiotic maturation. The results obtained by both indirect immunofluorescence and immunoblot analyses demonstrated a dramatic change in the localization of prosomal antigens during oocyte development. They were initially detected in the oocyte cytoplasm, during oocyte growth. At the end of vitellogenesis (stages V-VI), they entered the nucleus (germinal vesicle) and were accumulated there to the highest concentration. During oocyte maturation, after nuclear envelope breakdown, prosomal antigens were found to be localized again in the cytoplasm, until fertilization. No specific localization of prosomal antigens in mature oocytes, unfertilized and fertilized eggs was observed within the oocyte cytoplasm in relation to the cytoplasmic rearrangements leading to grey crescent formation.

Ambystoma mexicanum↗
PubMed1986

Changes in patterns of protein synthesis in axolotl oocytes during progesterone-induced maturation.

Patterns of protein phosphorylation and synthesis during axolotl (Ambystoma mexicanum) oocyte maturation were studied by incorporation of [32P]orthophosphate and [35S]methionine into polypeptides, followed by two-dimensional gel electrophoresis. Various alterations were observed after progesterone treatment: de novo appearance of [35S]methionine-labelled polypeptides, a quantitative increase in previously synthesized proteins and a quantitative decrease in or disappearance of other previously synthesized proteins. Changes in 32P- and 35S-labelling were observed very early during maturation. Neither prior oocyte enucleation nor alpha-amanitin treatment had a significant effect on these changes. Stimulation with MPF provided the same final protein pattern as PG treatment. However, cholera toxin inhibited all the changes seen during maturation. Comparisons between the patterns of [35S]methionine- and [32P]phosphate-labelling provide further information on the biochemical events that take place during oocyte maturation.

Ambystoma mexicanum↗
PubMed1985

A three-step scheme for gray crescent formation in the rotated axolotl oocyte.

It has been shown that various inhibitors of protein synthesis can elicit the precocious appearance of a gray crescent (GC) in in vitro maturing, nonactivated Ambystoma mexicanum oocytes. However, evidence has now been obtained that these treatments fail to induce GC formation when the oocytes are enucleated before initiation of maturation. The ability to form a GC is reestablished in enucleated oocytes by the injection of nucleoplasm from a normal oocyte, either before or after the injection of the inhibitor. In the latter case, the GC appears very rapidly, even though protein synthesis is at about 1/10th that of the control enucleated oocyte, after treatment with diphtheria toxin (final concentration 10(-8) M) as an inhibitor. One or several nuclear factors, in conjunction with inhibition of protein synthesis, are therefore essential for early symmetrization. The corrective nuclear factor is already present in the germinal vesicle of young oocytes, at the very beginning of vitellogenesis. It is not species specific, since enucleated axolotl oocytes can be symmetrized with Pleurodeles or even Xenopus oocyte nucleoplasm. Moreover, it has been shown that the nuclear-cytoplasmic interaction is possible only when cytoplasmic maturation has been proceeding for at least 10 hr after exposure to progesterone (at 18 degrees C). A three-step process as a prerequisite of GC formation in the oocyte is proposed: Cytoplasmic maturation must proceed till a reactive state is attained, allowing interactions with nuclear factors; Nuclear factor(s) interact(s) with matured cytoplasm; Inhibition of protein synthesis triggers GC formation. Sequence of steps 2 and 3 can be experimentally inverted but must always be preceded by step 1. Since a sharp reduction in amino acid incorporation has also been found in normally fertilized eggs just prior to GC formation, it is suggested that the scheme described above could be also applicable to normal symmetrization in this model system.

Ambystoma↗
PubMed1983

Plasma protein patterns in captive American kestrels.

Plasma proteins of the American kestrel (Falco sparverius) were analyzed by polyacrylamide disc electrophoresis for 3 different groups of birds: laying and non-laying females, and males. The electrophoretic patterns were homogeneous for each group and showed differences in the mobility of some proteins among the 3 groups. There was no significant difference among the 3 groups in the amount of proteins and in the standard parameter of albumin to globulin ratio.

Animals↗
PubMed1983

[Formation of the gray crescent, induced in axolotl oocytes during maturation, depends on factors of nuclear origin].

Inhibitors of protein synthesis caN elicit the precocious appearance of a grey crescent (GC) in in vitro maturing Ambystoma mexicanum oocytes. This treatment however fails to induce GC formation when the oocytes are enucleated before initiation of maturation. The ability to form a GC is reestablished in enucleated oocytes by the injection of nucleoplasm from a normal oocyte, either before or after injection of the inhibitor. In the latter case, the GC appears even though the protein synthesis level is already about one-tenth that of the control enucleated oocytes. One or several nuclear factors, in conjunction with protein synthesis inhibition, are therefore essential for the early symmetry reaction. The corrective nuclear factor is already present in the germinal vesicle of young oocytes at the very beginning of vitellogenesis. It is not species-specific and enucleated axolotl oocytes can be symmetrized with Pleurodeles or even Xenopus oocyte nucleoplasm. The interaction between nuclear factor(s) and cytoplasm is possible only when cytoplasmic maturation has occurred.

Ambystoma↗
PubMed1978

Deanol, lithium and placebo in the treatment of tardive dyskinesia. A double-blind crossover study.

A double-blind crossover study on the effects of deanol and lithium carbonate was conducted on a sample of 29 chronic schizophrenic patients with tardive dyskinesia. In addition to his usual treatment with different neuroleptics, each patient received during an 8-week period either deanol, lithium carbonate or placebo. A 4-week wash-out period was inserted between each of the 8-week periods of experimental treatment of the tardive dyskinesia. The administration of either deanol, lithium carbonate or placebo added to the neuroleptic treatment did not produce a statistically significant improvement of tardive dyskinesia in our patient population as a whole. Favorable and unfavorable responses are discussed.

Adult↗
PubMed1978

Pharmacokinetic interaction between amitriptyline and neuroleptics.

The influence of amitriptyline on the plasma level of various neuroleptics was studied in 25 chronic schizophrenic patients. The study lasted 20 weeks. Patients were kept first 4 weeks on their former neuroleptic medication, with amitriptyline added for 12 subsequent weeks, and withdrawn during the last 4 weeks when only the neuroleptic medication was continued unchanged. The plasma level of neuroleptics was assayed by gas-liquid chromatography, once weekly throughout the study. The amitriptyline plasma level was also evaluated once weekly during the 12 weeks of its administration. The mean neuroleptic plasma values for each 4-week period were pooled together in three groups: aliphatic, piperdine and piperazine phenothiazine derivatives. Amitriptyline provoked some increase of the plasma level of all phenothiazine derivatives. This augmentation was significant only transitorily, however. The putative mechanisms of this neuroleptic tricyclic antidepressant interaction are discussed.

Adult↗
PubMed1977

Influence of the antiparkinsonian drugs on the plasma level of neuroleptics.

The interaction between various neuroleptics and antiparkinsonian drugs was analyzed by measuring the neuroleptic plasma level before and after withdrawal of antiparkinsonian drugs. The population completing the study consisted of 32 chronic schizophrenics treated with chlorpromazine (8), levomepromazine (14), thioridazine (6), or haloperidol (4). Twenty-five were also receiving benztropine; 4, trihexyphenidyl; and 3, procyclidine. During the first 4 weeks patients remained on neuroleptics and antiparkinsonians, the latter being withdrawn during the 5th week, and the neuroleptics alone being administered during 16 following weeks. The plasma level of neuroleptics was assayed by gas liquid chromatography, once weekly in the morning at two different times. The analysis of variance showed a significant difference in neuroleptic plasma level when patients took neuroleptics only versus the period they had received neuroleptics and antiparkinsonians. The multiple comparison based on Studentized range Q0-05 revealed a significant progressive increase of neuroleptic plasma level during 12 weeks after withdrawal of antiparkinsonian drugs after which a plateau was reached. The hypothetical mechanisms of action of antiparkinsonians on neuroleptic plasma level are discussed.

Adult↗
PubMed1975

Influence of reserpine on all-night sleep pattern in nonlobotomized and lobotomized chronic schizophrenic patients.

This study was performed on two groups of schizophrenic patients. One group consisted on nine nonlobotomized patients and the other of nine lobotomized ones. The groups were matched for age, sex, duration of illness, clinical symptoms, type and dose of psychopharmacological treatment. The patients of both groups were administered 1 mg of reserpine half an hour before bedtime, for three successive days. Before reserpine administration the mean percentage time of the NREM stage 4 was significantly higher in the lobotomized group. There was no significant difference in the REM parameters. After three days of reserpine administration in the nonlobotomized group, there was no significant difference in the mean percentage of the NREM stage 4, whereas the mean REM percentage significantly increased and REM latency decreased. In the lobotomized group the same procedure, i.e., three days of reserpine administration, provoked a significant decrease in the mean percentage of the NREM stage 4 and no significant changes in the REM parameters. This difference in reserpine action on sleep in the lobotomized group is discussed.

Chronic Disease↗