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Few sex-autosome chromosome abnormalities have been documented in domestic animal species. In humans, Y-autosome chromosome abnormalities may occur at a rate of 1/2,000 live births, whereas in the domestic pig only 2 Y-autosome reciprocal translocations have been previously described. During a routine cytogenetic screening of young boars, we identified a new Y-autosome translocation carrier, which after puberty showed semen devoid of sperm and testicular hypoplasia with spermatogenesis arrest. Whole chromosome painting by FISH analysis corroborated the reciprocal nature of the chromosomal exchanges between the Y chromosome and SSC13. The possible causes for the observed meiotic arrest of the carrier are reviewed., (© 2016 S. Karger AG, Basel.)

The heteromorphic X and Y chromosomes behave in a special way in mammalian spermatocytes; they form the XY body and synapse only partially. The aim of this article was to study the origin and the role of the special differentiations in the XY pair of the domestic cat during pachytene by analyzing its fine structural characteristics and the immunolocalization of the main meiotic proteins SYCP3, SYCP1, SYCE3, SMC3, γ-H2AX, BRCA1, H3K27me3, and MLH1. The cat XY body shows particularly striking structures: an extreme degree of axial fibrillation in late pachynema and a special location of SYCP3-containing fibrils, bridging different regions of the main X axis, as well as one bridge at the inner end of the pairing region that colocalizes with the single mandatory MLH1 focus. There are sequential changes, first bullous expansions, then subdivision into fibrils, all involving axial thickening. The chromatin of the XY body presents the usual features of meiotic sex chromosome inactivation. An analysis of the XY body of many eutherians and metatherians suggests that axial thickenings are primitive features. The sequential changes in the mass and location of SYCP3-containing fibers vary among the clades because of specific processes of axial assembly/disassembly occurring in different species., (© 2017 S. Karger AG, Basel.)

Three different diploid chromosome numbers (2n = 54, 56 and 58) have been reported in the lesser horseshoe bat, Rhinolophus hipposideros. Asia Minor and the Middle East are inhabited by R. hipposideros specimens with 58 chromosomes. In Europe, specimens with 56 chromosomes have been recorded from several localities in the Czech Republic, Slovakia, Italy and Greece. Up to now, specimens with 54 chromosomes have been reported only from Spain and possibly from Switzerland. With the record of 54 chromosomes in specimens from Germany presented here, the distributional area of this variant is expanded into Central Europe. According to the cytogenetic data presently available, we presume that the European R. hipposideros population is divided into a western form (from Spain to Germany) with a 2n = 54 karyotype and an eastern form (from the Czech Republic to Greece) with a 2n = 56 karyotype. This study presents banded karyotypes for the 2n = 54 and 2n = 56 variants for the first time. In addition, chromosomal arm homology to the vespertilionid bat species Myotis myotis revealed by chromosome painting is reported. Whether the variants could represent separate species is also discussed., (Copyright © 2013 S. Karger AG, Basel.)

The presence of a parachute sex chromosome bivalent (Xyp) at metaphase I of male meiosis is a well-known characteristic of Coleoptera, present in almost all families of this order and assumed to represent their ancestral sex chromosome formula. Sex chromosomes appear to be manifold more frequently involved in inter-chromosomal rearrangements than the average of the nine autosomal pairs usually forming their karyotype. This leads to various formulae such as neo-sex, multiple sex and perhaps unique sex chromosomes. These rearrangements alter the intimate association between sex chromosomes and nucleolar proteins, which are usual components of the Xyp. Different situations, selected in a series of 125 mitotic and meiotic cytogenetic studies of Polyphaga beetle species, are reported and discussed, with the aim to improve our knowledge on the mechanisms of sex chromosome rearrangements, the relationships with nucleoli and the consequences on dosage compensation and chromosome segregation.

The karyotype of the giant beetle Dynastes hercules hercules is composed of only 16 autosomes and large sex chromosomes. Meiotic studies in the males showed that a large part of the sex chromosomes undergo synapsis at pachynema similarly to autosomes, demonstrating that both derived from an autosome-gonosome translocation. Therefore, karyotype formula is 18,neoXY. The heterochromatisation of the neoX short arm at pachynema indicates that it corresponds to the ancestral X. It carries the nucleolar organizer region (NOR) in its proximal part, which is undercondensed, especially in male mitotic and meiotic cells. In female mitotic cells, both NOR staining and undercondensation were more difficult to observe in the neoX short arms. In somatic interphase nuclei, NOR expression strongly varies with the sex. Two separated compact groups of silver dots were observed in female nuclei, while a single dispersed and large group of silver deposit exists in the males. Both the lower condensation and the higher NOR expression of the single neoX of the males, compared to each of the two neoXs of the females, is interpreted to be a consequence of dosage compensation, a mechanism not yet described in Coleoptera. In mammals as well as in Coleoptera, the carriers of gonosome-autosome translocations not exhibiting deleterious phenotypes show constitutive heterochromatin at the autosome-gonosome junction. Thus, heterochromatin may play an important universal role by clearly separating chromosome segments with different regulations of gene expression, such as inactivation or dosage compensation of the X chromosome on the one side and a conventional autosomal structure on the other side., (Copyright 2007 S. Karger AG, Basel.)

The availability of fetal cells from the maternal peripheral blood opens up the possibility for a noninvasive prenatal diagnosis. Until now this prospect has been hampered by the fact that there are no highly specific antibodies to fetal cells. In the present study, four as yet untested monoclonal antibodies - 2G5, 3F9, EPO-R and Flk1 - were analyzed in view of their effectiveness to stain fetal nucleated cells. Therefore, 20 ml of peripheral blood from 40 women carrying a male fetus were collected in the 16th to 28th weeks of pregnancy. Mononucleated cells, enriched by density gradient, were stained with one of the four antibodies and isolated with magnetic cell sorting. Subsequently, fluorescence in situ hybridization with chromosome X and Y centromere probes was performed which allowed us to analyze the maternal or fetal origin of the enriched cells. For evaluation, 500 nuclei per case were examined. The antibody 3F9 detected 0.2 cells on average (n = 5), 2G5 1.2 (n = 11), EPO-R 1.6 (n = 10) and Flk1 1.8 cells (n = 8) with fetal specific Y-positive hybridization signals. The antibody against CD71 (n = 6) used as control gave no Y-specific signals. Considering these results, the tested antibodies, especially Flk1, appear to be more successful in detecting fetal cells than the commonly used CD71 antibody., (Copyright 2001 S. Karger AG, Basel)