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Y Rumpler

Publications and source records attributed to Y Rumpler.

At least 73 records · Page 4Linked to original sources
PubMed1989

Synaptonemal complex study in some species of Gerbillidae without heterochromatin interposition.

Synaptonemal complexes were studied in Gerbillus campestris, Meriones libycus, M. shawi, M. crassus, and in two hybrids M. shawi x M. libycus (Gerbillidae, Rodentia). In both the pure species and hybrids, there was no pairing of X and Y chromosomes, as was previously observed in Psammomys obesus and other Gerbillidae species with gonosome-autosome translocations. A pair of autosomes was also located in proximity to the sex chromosomes in pachytene and showed unusual meiotic behavior with no, incomplete, or much delayed pairing. This chromosome pair, composed of late replicating heterochromatin, exists in most Gerbillidae species and is constant in number, but variable in size across the species. Both meiotic and mitotic characteristics indicate that this pair may correspond to a new type of chromosome which is different from B chromosomes. We do not know if there is a relationship between the presence of this chromosome and the unusual behavior of the sex chromosomes. In Gerbillidae species, the lack of pairing of both sex and heterochromatic chromosomes obviously does not prevent their correct meiotic segregation.

Animals↗
PubMed1988

Heterosynapsis in a heterozygous fertile boar carrier of a 3;7 translocation.

Silver-stained synaptonemal complexes (SCs) in surface-spread pachytene nuclei from a boar, heterozygous for a reciprocal translocation, were analysed by electron microscopy. In such heterozygotes, cross-shaped quadrivalent configurations are expected to form in order to maximize homologous pairing. Contrary to the classical, expected cross-shaped configuration, heterosynapsis was often observed, with asymmetrical association in the lateral elements of the non-homologous partners of the quadrivalents. This heterosynapsis is assumed to be a mechanism preventing spermatocyte loss, but inducing a secondary segregational type of impairment of fertility due to foetal wastage leading to reduced prolificacy.

Animals↗
PubMed1988

Synaptonemal complexes in a subfertile man with a pericentric inversion in chromosome 21. Heterosynapsis without previous homosynapsis.

Analysis of surface-spread synaptonemal complexes of zygotene and pachytene spermatocytes was carried out on a human male carrier of a pericentric inversion of chromosome 21 ascertained after four miscarriages. The synaptic behavior of the bivalent, which could be unambiguously identified by its nonaligned kinetochores, was analyzed. All zygotene and pachytene spermatocytes had 22 linearly paired autosomal bivalents, with apparently normal synaptonemal complexes, and no evidence of a loop configuration in the 50 cells analyzed. According to the XY type (classification of Solari), the cells were distributed across zygotene and pachytene stages, not exclusively in the late pachytene to which adjustment is conventionally thought to be confined. It is suggested that inverted segments heterosynapse at early pachytene, without previous homosynapsis. It is expected that this meiotic process leads to failure of crossing-over, reduces the production of unbalanced gametes, and the risk of recombinant offspring, but can increase the incidence of aneuploidy as a result of nondisjunction during meiosis I (a frequent cause of pregnancy wastage).

Adult↗
PubMed1988

Statistical study of a semiquantitative evaluation of testicular biopsies.

A statistical method was used to evaluate 629 testicular biopsies on which a semiquantitative morphometric analysis was applied. The results confirm with a high level of significance (p less than 0.001) the qualitative knowledge of testicular pathology. Some tight correlations between histological and/or cytological parameters are enlightened.

Biopsy↗
PubMed1987

Pachytene analysis in a 17;21 reciprocal translocation carrier: role of the acrocentric chromosomes in male sterility.

Pachytene analysis was undertaken in an infertile male, heterozygous for a 17;21 reciprocal translocation. The quadrivalent was identified by its configuration and chromomere pattern. A non-random association was found between the quadrivalent and the sex vesicle in 77% of the pachytene nuclei analysed. In 13.1% of the cells the contact with the sex vesicle was established by the terminal chromomere of the two chromosomes 21; in 63.9% of the cells, the entire region of the breakpoints was completely hidden by the sex vesicle. In some nuclei asynapsis was found in the region of the breakpoints. The nature of the contact between the quadrivalent and the sex vesicle is discussed in this paper. It is proposed that the acrocentric chromosome favours the contact between the quadrivalent and the sex vesicle, and increases the risk of sterility in male carriers of Robertsonian translocations and of reciprocal translocations involving one acrocentric chromosome.

Adult↗
PubMed1987

Successful artificial insemination in Lemur fulvus mayottensis.

A method is reported for collection of sperm by electrostimulation or prostatic massage in order to carry out artificial in utero insemination in Lemur fulvus mayottensis. Using fresh sperm, one success out of 7 attempts was obtained, although it was achieved with a vesiculectomized male.

Animals↗
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

Meiotic behaviour of familial pericentric inversions of chromosomes 1 and 9.

Pachytene analysis was carried out in two infertile brothers, one heterozygous for two pericentric inversions of chromosomes 1 and 9, the second heterozygous for the pericentric inversion of chromosome 1. The synaptic behaviour of the bivalent 1 inversion was the most informative. Analysis of the chromomere pattern combined with centromeric heterochromatin staining and synaptonemal complexes visualization allowed precise description of synaptic initiation and extension leading to the homosynapsed loop. Heterosynapsis following alignment of the inverted segments was demonstrated. Non-homologous synapsed bivalents had the morphological aspects of straight bivalents with two distant blocks of centromeric heterochromatin. The possible sterilizing effect caused by the autosomal inversion is discussed.

Adult↗