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J Couturier

Publications and source records attributed to J Couturier.

At least 73 records · Page 4Linked to original sources
PubMed1987

Isoacentric and isocentric chromosomes originating after deletions of human chromosomes.

The analysis of a sample of 100 isoacentric (IA) and isocentric (IC) chromosomes, which had originated from spontaneous or radiation-induced deletions in human lymphocytes, is reported. IC and also IA have a strong tendency to be formed after breakage in juxtacentromeric heterochromatin. When euchromatic regions are involved, the breaks are not distributed at random since they frequently occur at places where juxtacentromeric heterochromatin exists in other primate species. It is assumed that intercalary structures conserving some of the properties of heterochromatin exists in human chromosomes in intercalary positions.

Chromosome Aberrations↗
PubMed1987

Inactive X chromosome gene reactivation induced by 5-azacytidine, is not correlated with the modification of the pattern of replication.

The replication pattern of a human inactive X chromosome reactivated for one to four genes by 5-azacytidine has been studied by the BrdU-33258-Hoechst-Giemsa technique in four subclones of a somatic hamster-human hybrid. In one of them the pattern was clearly modified. In the three others the changes were not significant. No correlation was found between expression and replication.

Animals↗
PubMed1986

Trisomy and tetrasomy for long arm of chromosome 1 in near-diploid human endometrial adenocarcinomas.

Karyotypic analysis by R-banding after short-term culture, carried out on 7 cases of human endometrial adenocarcinoma, showed in 4 of these a trisomy or a tetrasomy for the long arm of chromosome I. In the 4 cases, these imbalances were due to rearrangements involving centromeric or para-centromeric break-points: 46,XX,-16, +der(1q16p) t(1;16)(1p16q;1q16p); 46,XX,-21, +der (1q21q)t(1;21) (1p21p;1q21q); 46,XX, -21, +der(21) t(1;21)(q11;p13); 48, XX, +2, +i(1q). Two other cases showed only a numerical aberration: 47, XX, +10 and 47, XX, +12. In the last case, only cells with apparently normal karyotype were seen. In the 4 cases with an anomaly of chromosome I, two normal I chromosomes coexisted with abnormal elements. This shows that the rearrangement very likely occurred in G2 phase of the cell cycle.

Adenocarcinoma↗
PubMed1986

The rate of chromosome breakage is age dependent in lymphocytes of adult controls.

Chromosome breaks and chromatid-type lesions from a prospective study of more than 1000 lymphocyte karyotypes from each of six controls were analysed. These lesions were more frequent in older (75 years old on average) than in younger (29 years old on average) controls, especially after 72 h cultures. All controls were found to be carriers of fragile sites. The most frequent were 3p14.3 and 16q23, especially in older controls. At least one fra (X) (q27) mitosis was found in each control. Most deletions occurred after breakage in heterochromatin or in late-replicating euchromatin. As almost all radials were either "mitotic chiasmata" or triradials (branched chromosomes), it is concluded that chromatid exchanges between non-homologous segments are very rare, and indicate chromosomal instability syndrome or recent exposure to a mutagen.

Adult↗
PubMed1986

Chromosome imbalances in endometrial adenocarcinomas: a possible adaptation to abnormal metabolic pathways.

Chromosome studies of endometrial carcinomas show several recurrent trisomies or tetrasomies: 1 (long arm), 10, 2, 7, 12, 3 and possibly X (long arm). These chromosomes or chromosome segments carry the majority of the genes coding for enzymes of glucidic metabolism, citrate cycle, and initial steps of nucleotide synthesis. Their excess, which does not appear as a primary event in tumorigenesis, is interpreted as an adaptation of the cancer cells to abnormalities of metabolic pathways. The increase of gene copies, by chromosome duplication, would facilitate the synthesis of enzymes the activity of which is increased. If this view is correct and has a general value, it would mean that, in addition to primary chromosome changes, which may induce oncogene activation, most anomalies, which are obviously secondary, may reflect a disturbance of metabolic pathways coded by housekeeping genes.

Adenocarcinoma↗
PubMed1986

Radiation induced inversions in human somatic cells.

Peri- and paracentric inversions induced by various types of ionizing radiation (gamma and alpha-rays, neutron and neon beams) are analysed. Their frequencies significantly increase for radiation doses greater than or equal to .5 Gy. Their distribution does not seem to be at random. Pericentric are detected 3 to 4 times more frequently than paracentric inversions. Some identical inversions are recurrently induced. A proportion reproduces inversions detected in human cytogenetics laboratories and a larger proportion, chromosomes of other primate species. It seems that breakages, which numbers are roughly proportional to chromosome lengths, lead to reassociations with a limited number of combinations.

Alpha Particles↗
PubMed1986

Inversions in evolution of man and closely related species.

By the comparative study of the karyotypes of many Primates, 35 inversions (25 peri- and 10 paracentric) having accumulated during evolution of species related to man were reconstructed. Some of them originated human chromosomes from more ancestral chromosomes still present in other primate species. Their detection in man would indicate the occurrence of reverse mutations. Other inversions occurred in ancestral chromosomes identical to those of man, and originated chromosomes of other Primates species. Their detection in man would indicate the occurrence of a convergent mutation. It is shown that such reverse and convergent mutations do occur. They are too frequently observed than by mere chance among patients ascertained in human cytogenetic laboratories. Their excess is still larger among radiation induced inversions in human cells. This demonstrates the nonrandom occurrence of inversions. In addition, it is concluded that inversions which have accumulated during evolution are more representative of mutagenesis than those detected in human cytogenetic laboratories.

Animals↗
PubMed1985

Inversion (14)(q12qter) or (q11.2q32.3): the most frequently acquired rearrangement in lymphocytes.

In a large study of chromosome rearrangements occurring in human lymphocytes from normal subjects, inv (14)(q12qter) or (q11.2q32.3) is found to be the most frequent, affecting 0.15% of mitoses. The same inversion is observed in the lymphocytes of the chimpanzee, indicating the ancestry of this inversion. It is not induced by ionizing radiations, and its frequency may be increased in Fanconi anemia, but not in ataxia telangiectasia. It may represent one of the steps of the process of leukemogenesis.

Animals↗
PubMed1985

Deletion of band 13q21 is compatible with normal phenotype.

A deletion of band 13q21, of maternal origin, was found in a male whose wife had had two miscarriages. The proband and his mother were both phenotypically normal. Repeated studies by high resolution banding techniques failed to demonstrate a translocation of the deleted band in the two subjects. The absence of pathological consequences of the deletion is explained by the fact that this band is one of the latest replicating in the human karyotype, which may indicate, by analogy with heterochromatin, that it carries no transcriptionally active genetic material.

Adult↗
PubMed1985

'Pure' partial trisomy 2q in a male owing to malsegregation of a maternal translocation t(X;2)(p22.3;q32.1).

This report describes a male infant with partial trisomy 2q: 46,Y,der(X),t(X;2) (p22.3;q32.1)mat. The phenotype was compatible with partial trisomy 2q syndrome. Replication studies showed a random X inactivation in the mother. Soluble isocitrate dehydrogenase (IDH-1) dosage was within the expected range for a trisomic patient and favours the assignment of this locus to the region 2q32----qter.

Abnormalities, Multiple↗
PubMed1985

[A new case of partial monosomy of chromosome 12,del(12)(p11.01 to p12.109) confirming the location of the gene for lactate dehydrogenase B].

A new case of partial monosomy of the short arm of chromosome 12 is described in a 17-year-old girl and compared with other observations reported in the literature. The breakpoints were localized to region 12p11----12p.12.1. Qualitative and quantitative activity of LDHB allowed a precise assignment of the structural gene to sub-band 12p12.2.

Adolescent↗
PubMed1985

Aberrations of the synaptonemal complexes in a male 46,XY,-14,+der(14)t(Y;14).

An unbalanced translocation 46,XY,-14,+der(14)t(Y;14)(q11;p11) was observed in an azoospermic male, with reduced spermatogenesis and absent spermiogenesis. At the pachytene stage of spermatocyte 1, the segments of the 2 Y chromosomes, fluorescent with quinacrine mustard, were always found close together. This proximity was also demonstrated by the study of synaptonemal complexes, which showed, in addition, an unusual hypercondensation of the proximal segment of bivalent 14, adjacent to the translocated Y chromosome. This allows us to propose that this hypercondensation might correspond to an inactivation of the translocated autosome, which could be responsible of the degeneration of the germ cells.

Adult↗
PubMed1984

Detailed cell cycle analysis in human lymphocytes; application to gamma-irradiated cells.

A method based on BrdU incorporation for analyzing in detail the kinetics of the cell cycle is described. The S phase has been subdivided into five subphases, each recognizable by their BrdU incorporation pattern at metaphase. The method can be useful for the study of abnormal cell cycles, and may have particular application in mutagenesis studies concerning the various subphases of the S phase, without using synchronization techniques. An application of the method is described, showing that gamma-irradiation, during the course of the S phase, leads to a lack of cells which were in early S phase at the time of irradiation. This finding can be related either to a higher lethality at this stage of the cell cycle or to a delay in completion of DNA replication after irradiation.

Cell Cycle↗
PubMed1984

Chromosome study of Presbytis cristatus: presence of a complex Y-autosome rearrangement in the male.

The karyotypes of a female and of a male Presbytis cristatus are analysed. In the latter, there is a complex Y-autosome rearrangement. The phyletic position of this species, in relation to genus Colobus, previously studied, is proposed, considering the sequence of chromosomal rearrangements which occurred during their evolution. These rearrangements, in addition to the t(Y-autosome), are characterized by a high frequency of inversions, and above all, by several non-Robertsonian translocations which occurred very rarely during evolution of other Primates.

Animals↗
PubMed1984

[Great degree of homology between the ancestral karyotype of squirrels (rodents) and that of primates and carnivores].

The karyotype of 7 species of Sciurinae representative of 6 tribes were compared: Atlantoxerus getulus, Menetes berdmorei, Callosciurus flavimanus, Heliosciurus gambianus, Sciurus vulgaris, Eutamias sibiricus, and Marmota monax. Homoeologies between almost all chromosome segments were found. Numerous similarities with the karyotypes of certain Primates and Carnivora were observed. A presumed ancestral karyotype of the Sciurinae is proposed.

Animals↗
PubMed1983

The ancestral karyotype of Carnivora: comparison with that of platyrrhine monkeys.

The karyotypes of six species of Carnivora (Mungos mungo, Paradoxurus hermaphroditus, Potos flavus, Mustela furo, Felis serval, and Halichoerus grypus), representative of five different families, were studied and compared. Correspondence between almost all chromosome segments was found, and a presumed ancestral karyotype of Carnivora is proposed. Analogies to human chromosomes are also given, and the results obtained are in excellent agreement with previously published gene mapping data on man and the domestic cat.

Animals↗