Biomedical subjects

B Dutrillaux

Publications and source records attributed to B Dutrillaux.

At least 307 records · Page 17Linked to original sources

PubMed1986

Chromosomal evolution in Malagasy lemurs. IX. Chromosomal banding studies of Lepilemur mustelinus, L. dorsalis, and L. edwardsi.

The karyotypes of three Lepilemuridae species, Lepilemur mustelinus, L. edwardsi, and L. dorsalis, are described and compared to those of three Lepilemur species previously reported. The phylogenetic relationships between the six species and their presumed last common ancestor are given. The results obtained, and the comparison with other groups, strongly suggest a monophyletic origin for all Malagasy lemurs.

Animals↗

PubMed1986

Meiotic association between the XY chromosomes and the autosomal quadrivalent of a reciprocal translocation in two infertile men, 46,XY,t(19;22) and 46,XY,t(17;21).

An electron microscopy study of synaptonemal complexes in two men carrying reciprocal translocations, a t(19;22) and a t(17;21), is reported. It is shown that a delay in synapsis affects the segments corresponding to the short arms of the acrocentrics involved in the formation of quadrivalents. This appears to provoke an interaction with the sex bivalent which could lead to a failure of spermatogenesis. A study of the literature comparing reciprocal translocations that do and do not involve acrocentrics in sterile and fertile men shows the existence of a significant association between the presence of an acrocentric in the rearrangement and sterility. These results on reciprocal translocations involving at least one acrocentric chromosome correspond to those obtained in cases of Robertsonian translocations.

Chromosomes, Human, Pair 17↗

PubMed1986

Synaptonemal complexes in Gerbillidae: probable role of intercalated heterochromatin in gonosome-autosome translocations.

A study of sex chromosomes and synaptonemal complexes in male specimens of Gerbillus chiesmani, G. nigeriae, G. hoogstrali, and Taterillus pygargus is reported. In each of these Gerbillidae species there are two or three translocations of autosomes with X and Y chromosomes. Analysis of mitotic chromosomes consistently shows the presence of constitutive heterochromatin on the der t(X;autosome) at the X-autosome junction and on the der t(Y;autosome). Analysis of the synaptonemal complexes shows the existence of an unusual structure, lightly stained, at the X-autosome junction and at the Y-autosome junction, which is probably heterochromatic in nature, thus corresponding to the mitotic patterns. This heterochromatin separates the autosomal and gonosomal segments, which behave independently and normally. By analogy with findings from humans and other mammals, a general hypothesis is proposed on the role of intercalated heterochromatin between translocated gonosomes and autosomes. This hypothesis explains why the pathological consequences of these translocations may be very different in males and females. The role of intercalated heterochromatin would be to avoid the pathological consequences of gonosome-autosome translocations resulting from inactivation of the sex chromosomes in female somatic cells and male germinal cells.

Animals↗

PubMed1986

Induction of increased salvage pathways of nucleotide synthesis by dosage effect due to chromosome imbalances may be fundamental in carcinogenesis: the example of colorectal carcinoma.

The cytogenetic study of colorectal carcinomas is consistent with the following sequence in the tumor evolution: rearrangement of chromosome 17 with loss of 17p and often gain of 17q, loss of chromosome 18, frequent del(5q), frequent del(1p) correlated with the gain of an early replicating X. At least one gene directly involved in nucleotide synthesis, especially in the de novo pathways for thymidine is located on each of these chromosomes or chromosomes segments. A model established on the gene dosage effect, which likely results of these chromosome imbalances, may be proposed: (1) increase of thymidine kinase activity (chromosome 17q) and thus of the salvage pathway of thymidine synthesis (2) decrease of thymidine de novo pathways by decreased of thymidylate synthase (chromosome 18) and of dihydrofolate reductase (chromosome 5q) and thus accumulation of 2'-deoxyuridine-5'-P, which saves 2'-deoxycytidine 5'-P (3) decrease of cytidylate (or uridylate) kinase (chromosome 1p) and thus accumulation of 2-deoxycytidine-5-PP and of uridine-5-P (UMP) decreasing the metabolisation of orotidine-5'-P, precursor of 2-deoxycytidine-5-PP, which (4) saves -D-5-ribosyl-PP (PRPP) or even conversion of orotidine-5'-P in PRPP. The later is the immediate precursor of nucleotides in their major salvage pathways synthesis: PRPP + base----nucleotide + PPi. This reaction which would be much activated needs hypoxanthine phosphorybosyl transferase (HPRT). Its gene is carried by chromosome X which is here duplicated in its active early replicating form.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosome Aberrations↗

PubMed1986

[Role of chromosomes in evolution: a new interpretation].

The number of possible meiotic segregations of paternal and maternal chromosomes is 2N (N = haploid chromosome number). In eutherian Mammals, where large variations of N exist, 2N may be very different in related species, genes, or families. For instance, in Cercopithecidae, species with the highest value (N = 36) make 2(15) = 32,768 more gametic chromosome combinations than those with the lowest value (N = 21). It is also shown that the number of chiasmata varies from species to species and is proportional to the haploid number of arms NF/2 of the karyotype. Thus, increase or decrease of both N and NF/2, often concomitant, both increase or decrease genetic mixing. The chromosomal phylogeny of Primates, Carnivora and Rodentia shows that pure dichotomic evolution is rare, at contrast with populational (non dichotomic) evolution which seems most frequent. In these Mammals, the few examples of dichotomic evolution are observed in groups with low values of N and NF/2. It is concluded that dichotomic evolution, which should be favoured by the transmission of groups of linked mutant alleles, is prevented, in most instances, by the high recombination rate in karyotypes with high values of N and NF/2. Thus the mode of speciation would depend on karyotype modifications by long term effects on population genetics, in addition to the immediate effects of gametic barriers due to chromosomal rearrangements in the heterozygous state.

Alleles↗

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

Theoretical study of inversions affecting human chromosomes.

A theoretical study of inversions affecting human chromosomes is proposed. Taking into consideration the number of bands and the fact that breaks occur at interfaces between bands, it is concluded that: 7.659 different pericentric inversions might be detected in a prometaphasic 802-band karyotype; this number decreases to 917 in a metaphasic 273-band karyotype; 8.607 and 862 different paracentric inversions might be detected in the same karyotypes respectively, but these results are likely to be overestimated. These theoretical data are used for showing that the pericentric inversions detected in human cytogenetic laboratories, are too frequently recurrent and are not distributed at random.

Chromosome Inversion↗

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

Acquired inversions in human leucocytes.

Peri- and paracentric inversions are observed in human leukocytes at various rates. Four categories are proposed, in relation to the frequency of occurrence, although it may vary with time for a same inversion. Category 1 corresponds to isolated, thus non recurrent inversions. Category 2 (f congruent to .001) corresponds to inv(14)(q12qter) and inv(7)(p14q35) in individuals with presumably normal genetic constitution. Category 3 (f congruent to .01) corresponds to inv(7)(p14q35) in patients affected by ataxia telangiectasia (AT). This inversion, when it is frequent, indicates an abnormal genetic constitution, radiation sensitive and predisposing to cancers. Finally, category 4 (f greater than or equal to .1) corresponds to inversions existing in precancer or in cancer clonal cells: inv(14)(q11.2q32.2) in AT patients affected by a T-cell hemopathy, inv(14)(q12qter) in chronic T-cell lymphocytic leukaemia, and inv(16)(p13q22) in acute myelomonocytic leukaemia with abnormal eosinophils. The prognostic and diagnostic interests of these inversions is discussed.

Ataxia Telangiectasia↗

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

Radiation sensitivity of Bloom's syndrome lymphocytes during S and G2 phases.

In order to study chromosome sensitivity of Bloom's syndrome (BS) cells in relation to the replication stage, gamma-ray irradiation was performed immediately before adding bromodeoxyuridine (BrdU) to lymphocyte cultures of one BS patient and of one control. It was found that BS cells are much more sensitive to the irradiation than control cells at the end of S and at G2 phases. The rate of induction of chromosome breaks is significantly increased and that of chromatid breaks and exchanges is also increased, though to a lesser degree. Our results also favor the existence of a cell subpopulation in BS characterized by a slow cycle, a high spontaneous chromosome aberration rate, and a high radiation sensitivity.

Bloom Syndrome↗

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

Diagrammatic representation for chromosomal mutagenesis studies. III. Radiation-induced rearrangements in Pan troglodytes (chimpanzee).

A qualitative study is presented of chromosomal rearrangements induced by gamma-irradiation at 2 Gy and 3 Gy in peripheral blood lymphocytes of the chimpanzee Pan troglodytes. From a sample of 460 cells, karyotyped after R-banding, 1047 rearrangements were detected. Each type of rearrangement is analyzed according to the diagrammatic method previously developed. The non-random nature of the induction of the rearrangements is clear. The chimpanzee seems highly sensitive to the induction of dicentrics. This may be related to the existence, in its karyotype, of sensitive juxta-telomeric heterochromatin, much more frequently affected in the case of formation of dicentrics than of other types of rearrangements. Thus, the evaluation of radiation sensitivity of a given species based only on the yield of dicentrics may not have a general value for chromosomal mutagenesis.

Animals↗

PubMed1985

Chromosomal phylogeny of Lagothrix, Brachyteles, and Cacajao.

Based on a comparison of the karyotypes of two Plathyrrhini species, Cacajao melanocephalus (Pitheciinae) and Brachyteles arachnoides (Atelinae), with those of two previously studied species, Lagothrix lagothrica (Atelinae) and C calvus rubicundus (Pitheciinae), it appears that the two Cacajao species have undergone the same number of chromosome rearrangements since they diverged from their common ancestor and that the karyotype of Brachyteles is ancestral to that of Lagothrix. The chromosomal phylogeny of these four species is proposed. A Y-autosome translocation is present in the karyotypes of the two Cacajao species.

Animals↗

PubMed1985

Chromosomal evolution in Malagasy lemurs. VIII. Chromosome banding studies of Lepilemur ruficaudatus, L leucopus, and L septentrionalis.

The karyotypes of three Lepilemuridae species, Lepilemur ruficaudatus, L leucopus, and L septentrionalis, are described and compared. An almost complete analogy of chromosome banding is exhibited. Several complex chromosomal rearrangements, especially end-to-end translocations, have occurred in the evolution of these species. The chromosomal data indicate that the species studied are well separated. In addition, their common chromosomal characters show that they constitute a clearly distinct family among the lemurs.

Animals↗

PubMed1985

Major chromosome homeologies between Muridae and Cricetidae.

The presumed ancestral karyotype of Muridae, previously reconstructed, is compared with that of a selected Cricetidae species, Akodon a arviculoides. Most of the chromosomes of the presumed ancestral chromosomes of Muridae are homeologous to chromosome arms or segments in the Akodon karyotype. This result strengthens the validity of the reconstruction of the ancestral karyotype for both Muridae and Cricetidae.

Animals↗

PubMed1985

[Chromosomal phylogeny of 7 species of Sciurinae].

The sequence of chromosomal rearrangements that leads to the karyotypes of living species of Sciurinae is hardly compatible with a dichotomic evolution. The most probable hypothesis is that of a populational chromosomal evolution: the different lineages would have been isolated successively from an ancestral population in which several chromosomal rearrangements would have spread to more or less important fractions of the population. The proposed order in the succession of these isolations (Marmota monax, Sciurus vulgaris, Callosciurus flavimanus, Heliosciurus gambianus, Atlantoxerus getulus, Eutamias sibiricus then Menetes berdmorei) fits the paleontological data.

Animals↗