Distribution of Atr protein in primary spermatocytes of a mouse chromosomal mutant: a comparison of preparation techniques

In this study, we examined the suitability of a three dimensional preparation technique for studying chromosome behaviour in the first meiotic prophase in the mouse chromosomal mutant T(1;13)H/T(1;13)Wa. To preserve cellular shape, primary spermatocytes were encapsulated in a fibrin clot. Conventionally sedimented prophase nuclei served as controls. Axial elements and lateral synaptonemal complex components were subsequently stained by immunofluorescence and the presence of axial elements at the pachytene stage was highlighted with indirect immunofluorescence against the Atr protein. We compared the distribution of Atr signal in the fibrin-embedded spermatocytes with surface-spread preparations and immunohistochemically stained histological sections of seminiferous tubules. Furthermore, fluorescence in situ hybridisation of the mouse minor satellite DNA was done on fibrin-embedded spermatocytes. The Atr signal is most conspicuous in fibrin-embedded nuclei on unpaired axial elements during pachytene, both for sex chromosomal and for autosomal segments, and expanding from these elements into the surrounding chromatin. Both spread and encapsulated zygotene nuclei with extended axial element formation proved to be positive for Atr. Mid- to late zygotene nuclei were devoid of 3,3'-diaminodibenzene deposition in the histological sections. Highlighting the unpaired axial elements in the small heteromorphic 1(13)H;1(13)Wa bivalent with an Atr signal enabled meiotic analysis of this bivalent to be carried out in a three-dimensional context. Thus, proximity of this bivalent with the sex chromosomes is found more often in three-dimensional preparations than in spread preparations. Furthermore, the development of the Atr signal over the sex chromosomes as pachytene proceeds helps in substaging of this long and heterogeneous meiotic phase, in sedimented but especially in fibrin-encapsulated nuclei.

Localisation of RAD50 and MRE11 in spermatocyte nuclei of mouse and rat

Synaptonemal complexes (SCs) are zipperlike structures that are assembled between homologous chromosomes during meiotic prophase. They consist of two axial elements (AEs) (one along each of the two homologous chromosomes), which, in mature SCs, are connected by numerous transverse filaments along their length. Several proteins involved in the later steps of meiotic recombination most probably function in close association with the AEs of SCs, because the proteins involved in these steps have all been localised along AEs or SCs by immunocytochemical methods. It is not known at which step in meiotic recombination this association with the AEs is established. In order to shed some light on this issue, we analysed the localisation of two proteins that are involved in early steps of meiotic recombination, RAD50 and MRE11, relative to AEs and SCs by immunofluorescence labelling of paraffin sections of the mouse testis, using affinity-purified polyclonal antibodies against RAD50 and MRE11, and monoclonal and polyclonal antibodies against SC components. The localisation patterns of MRE11 and RAD50 within spermatocytes were very similar. MRE11 and RAD50 appeared in high abundance in preleptotene spermatocytes, just before SC components could be detected. From preleptotene until early zygotene they were present throughout the nucleus. In mid and late zygotene, MRE11 and RAD50 concentrated in distinct areas; in early pachytene the two proteins had almost disappeared from the nucleus, except from the sex vesicle (the chromatin of the XY bivalent), where they persisted in high abundance until diplotene. We propose that MRE11 and RAD50, together with other proteins, prepare chromatin throughout the early meiotic prophase nucleus for the initiation of meiotic recombination. Possibly, only a small fraction of the RAD50- and MRE11-containing (pre)recombination complexes associates transiently with AEs, where further steps in meiotic recombination can take place.

Preferential fluorescent staining of heterochromatic regions in human chromosomes 9, 15, and the Y by D 287/170

The utility of a newly synthesized chemical variation of DAPI (4'-6-diamidino-2-phenyl-indole), D 287/170, for differential staining of constitutive heterochromatin in man is demonstrated. Direct staining of human chromosomes with D 287/170 results in brilliant fluorescence of the paracentromeric C-band of chromosome 9, of a proximal short-arm segment of chromosome 15, and of certain heterochromatic regions in the Y. Bright, but less conspicuous fluorescence is occasionally seen at the centromeres of other chromosomes. The staining differentiation obtained by D 287/170 is very distinct, and the intensity of the fluorescent light is unusually high. The new fluorochrome should prove particularly useful for detecting and analyzing human chromosome 9 heterochromatin at various stages of the cell cycle in normal and structurally altered chromosomes.

Characterization of a new aberration of the human Y chromosome by banding methods and DNA restriction endonuclease analysis

Comparative cytogenetic analyses were performed with ten different banding methods on a previously undescribed, inherited structural aberration of a Y chromosome, and the results compared with those of normal Y chromosomes occurring in the same family. The value of the individual staining techniques in investigations of Y chromosomal aberrations is emphasized. The aberrant Y chromosome analyzed can be formally derived from an isodicentric Y chromosome for the short arm with a very terminal long-arm breakpoint, in which the centromere, an entire short arm, and the proximal region on one long arm was lost. This interpretation was confirmed by determining the amount of the two Y-specific DNA sequences (2.1 and 3.4 kb in length) by means of Hae III restriction endonuclease analysis. The karyotype-phenotype correlations in the men with this aberrant Y chromosome, especially the fertility dysfunctions (oligoasthenoteratozoospermia, cryptozoospermia), are discussed. The possibility of the existence of fertility factors involved in the control of spermatogenesis within the quinacrine-bright heterochromatic region of the Y long arm is presented.

Mitotic and meiotic analysis in Arctocephalus australis (Otariidae)

The karyotype with C-, G- and NOR-banding of Arctocephalus australis is reported for the first time. The chromosomal number is 2n = 36. The X chromosome, identified in G-banded metaphases from males, is metacentric and the Y chromosome is a minute chromosome, also metacentric. Pachytene spermatocytes were used for synaptonemal complexes analysis with a surface spreading technique. A total of 17 autosomal synaptonemal complexes are observed plus the XY pair. During early pachytene, the X and Y axes are thickened and remain unpaired. As pachytene advances, a short SC is formed between the gonosomes, as it is common among eutherian mammals. The particular asymmetrical appearance of the synaptonemal complex in the sex pair is described and compared to other cases among mammals.

Sequential meiotic prophase development in the pubertal Indian pygmy field mouse: synaptic progression of the XY chromosomes, autosomal heterochromatin, and pericentric inversions

Sequential meiotic prophase development has been followed in the pubertal male pygmy mouse Mus terricolor, with the objective to identify early meiotic prophase stages. The pygmy mouse differs from the common mouse by having large heterochromatic blocks in the X and Y chromosomes. These mice also show various chromosomal mutations; for example, fixed variations of autosomal short arms heterochromatin among different chromosomal species and pericentric inversion polymorphism. Identification of prophase stages was crucial to analyzing effects of heterozygosity for these chromosomal changes on the process of homologous synapsis. Here we describe identification of the prophase stages in M. terricolor, especially the pachytene substages, on the basis of morphology of the XY bivalent. Based on this substaging, we show delayed pairing of the heterochromatic short arms, which may be the reason for their lack of chiasmata. The identification of precise pachytene substages also reveals an early occurrence of "synaptic adjustment" in the pericentric inversion heterobivalents, a mechanism that would prevent chiasma formation in the inverted segment and thereby would abate adverse effects of such heterozygosity. The identification of pachytene substages would serve as the basis to analyze the nature of synaptic anomalies met in M. terricolor hybrids (which will be the basis of a subsequent paper).

[The electron microscopic analysis of synaptonemal complexes in male hybrids]

Cytogenetic studies of sterile male F1 hybrids may be helpful for the understanding of genetic bases of Haldane's Rule. The main purpose of this review is to provide several explanations for various meiotic abnormalities associated with impaired fertility. Results of cytogenetic studies of gametogenesis in vertebrates (mainly mammals) performed using electron microscopy lead to the conclusion that abnormal morphology of synaptonemal complexes is one of the main factors underlying sterility of hybrid males in mammals. Various abnormalities of synaptonemal complexes have been described in male hybrids of primates (lemur), small rodents (hybrids of laboratory mice with wild mice, as well as voles, mole-voles, hamsters, rats, and gerbils), and carnivores (silver fox, mustelids), as well as in the shrew, cattle hybrids, buffalo, and fish.

Sex chromosomes and sex-determining genes: insights from marsupials and monotremes

Comparative studies of the genes involved in sex determination in the three extant classes of mammals, and other vertebrates, has allowed us to identify genes that are highly conserved in vertebrate sex determination and those that have recently evolved roles in one lineage. Analysis of the conservation and function of candidate genes in different vertebrate groups has been crucial to our understanding of their function and positioning in a conserved vertebrate sex-determining pathway. Here we review comparisons between genes in the sex-determining pathway in different vertebrates, and ask how these comparisons affect our views on the role of each gene in vertebrate sex determination.

Transmission of a fully functional human neocentromere through three generations

An unusual Y chromosome with a primary constriction inside the long-arm heterochromatin was found in the amniocytes of a 38-year-old woman. The same Y chromosome was found in her husband and brother-in-law, thus proving that it was already present in the father. FISH with alphoid DNA showed hybridization signals at the usual position of the Y centromere but not at the primary constriction. Centromere proteins (CENP)-A, CENP-C, and CENP-E could not be detected at the site of the canonic centromere but were present at the new constriction, whereas CENP-B was not detected on this Y chromosome. Experiments with 82 Y-specific loci distributed throughout the chromosome confirmed that no gross deletion or rearrangement had taken place, and that the Y chromosome belonged to a haplogroup whose members have a mean alphoid array of 770 kb (range 430-1,600 kb), whereas that of this case was approximately 250 kb. Thus, this Y chromosome appeared to be deleted for part of the alphoid DNA. It seems likely that this deletion was responsible for the silencing of the normal centromere and that the activation of the neocentromere prevented the loss of this chromosome. Alternatively, neocentromere activation could have occurred first and stimulated inactivation of the normal centromere by partial deletion. Whatever the mechanism, the presence of this chromosome in three generations demonstrates that it functions sufficiently well in mitosis for male sex determination and fertility and that neocentromeres can be transmitted normally at meiosis.

Clinical, cytogenetic and molecular analysis of three 46,XX males

Cytogenetic analysis, fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR) were applied to characterize the Y-chromosomal breakpoints of three XX male patients. Two of these patients show a breakpoint within a protein kinase gene, PRKY, previously described as a hotspot of ectopic recombination between homologous regions on X and Y chromosomes during male meiosis. The slightly different clinical phenotypes of the three patients cannot be correlated with the localization of the breakpoints.

[Characteristics of the first meiotic division in hamster hybrids obtained by backcrossing Phodopus sungorus and Phodopus campbelli]

Spermatocytes of fertile, subfertile, and sterile hamster hybrids obtained by backcrossing Phodopus sungorus and Ph. campbelli were analyzed under light and electron microscopes. Light microscopy showed that early meiosis was blocked in pachitene in the spermatocytes of sterile hybrids. The X and Y chromosomes were dissociated in metaphase I in several fertile and subfertile animals. Electron microscopic analysis of the synaptonemal complex (SC) revealed a disturbed synapsis of sex chromosomes and autosomes in all hybrids. Dissociation of the sex chromosomes, terminal and interstitial asynapsis, and interlocking of autosomes were observed. Disturbed synapsis in hybrids was assumed to result from the difference between Ph. sungorus and Ph. campbelli in not only their chromosomes, but their genes as well.

Case report: high fertilization rate in conventional in-vitro fertilization utilizing spermatozoa from an oligozoospermic subject presenting microdeletions of the Y chromosome long arm

A case is reported in which a high fertilization rate was achieved by conventional in-vitro fertilization (IVF), using spermatozoa from an oligozoospermic man carrying a microdeletion of the long arm of the Y chromosome. The patient presented with idiopathic infertility of 10 years duration; the fertility status of his wife was completely normal. After IVF, five out of eight oocytes retrieved showed normal fertilization and four showed normal embryo cleavage. Four embryos were transferred; however, pregnancy did not result. These results demonstrate that spermatozoa from oligozoospermic patients carrying a Yq microdeletion are fully competent in achieving capacitation, acrosome reaction and fertilizing ability during IVF. Therefore, although definitive conclusions cannot be made from a single case report, we suggest that Yq microdeletion analysis should be considered in oligozoospermic patients undergoing conventional IVF.

[Analysis of a microdeletion in the AZF gene region in azoospermic patients: from research to molecular biology laboratory routine]

Microdeletions in AZF (Azoospermia Factor) region of the Y Chromosome have been recently described in azoospermic or oligozoospermic men. A Y chromosome molecular analysis was performed in peripheral blood DNA obtained from 16 azoospermic patients. Microdeletions within the interval 6 of the long arm of chromosome Y were analysed using the PCR (Polimerase Chain Reaction) technique. The presence of the DAZ (SY255) sequence was tested in 6 patients, while the remaining 10 patients were analysed for 6 different loci mapped to AZFb and AZFc regions. Microdeletion was detected in one azoospermic patient in the YRRM2 sequence. This result supports the finding of microdeletions not involving the DAZ sequence and suggests that routine investigation of azoospermic patients for microdeletions spanning the interval 6 region of y chromosome is also required.

[Seminal fluid today]

Semen analysis is still today a fundamental stage in male fertility diagnosis. In fact it's essential to evaluate didimal functional state and particularly the sperm genesis. But a semen analysis with normal parameters does not assure male fertility. Except the cases of azoospermia it does not distinguishes fertile from infertile patients, but when the sperm quality decrease, the pregnancy rate also decrease but rarely touch zero. Reliability of the analysis depends on the experience and on the analyst's ability who has to give an opinion about fundamental parameters like motility and sperm morphology. It is most correct to talk about semen analysis instead of semen examination because is possible to obtain not only number and quality of spermatozoa but also hormonal, immunological, bacteriological, cytogenetic, biomolecular data. Furthermore in the last ten years a lot of functional tests have been perfected, able to value accurately the integrity of some spermatozoa's "functional compartments" like membrane, acrosoma, DNA, nuclear proteins but these examinations have been considered at level assessment only for select cases. Semen analysis remains therefore a fundamental examinations in the study of male infertility even if rarely it is able to express definitive trials about infertility. In fact this always represents a couple problem, particularly of the couple in study.

Defining the anatomy of the Rangifer tarandus sex chromosomes

A comprehensive cytogenetic characterization of the unusally large reindeer (Rangifer tarandus) sex chromosomes is presented for the purpose of studying the evolution of these atypical gonosomes. Sex chromosome idiograms were constructed from G-banded and C-banded chromosomes to illustrate the relative amounts and locations of euchromatin and heterochromatin. Hybridization with a Mazama gouazoubira X whole-chromosome paint revealed that essentially all reindeer X-linked euchromatin and most reindeer Y-linked euchromatin is conserved interspecifically. Subsequently, painting probes were generated from flow-sorted reindeer X chromosomes, flow-sorted reindeer Y chromosomes, and from microdissections of specific gonosomal regions to establish specific segment-to-segment homologies between these gonosomes. In particular, one microdissection-generated paint demonstrated that certain constituent repetitive DNAs, found in C-band region Xq31, were also present in essentially all heterochromatin blocks of the Y chromosome. Microdissection-generated paints from other X-linked heterochromatin blocks revealed the presence of DNA sequences that lacked homologous sequences on the Y chromosomes and were more specific for their region of origin. These characteristics of the reindeer sex chromosomes are consistent with the notion that mammalian sex chromosomes were derived from homologous progenitor chromosome pairs and provide insights into the evolution of these atypical mammalian gonosomes.

Optimization of non-isotopic in situ hybridization: detection of the Y chromosome in paraformaldehyde-fixed, wax-embedded cat retina

A technique was developed to detect the Y chromosome in paraformaldehyde-fixed diethylglycoldiesterate-embedded cat retina. The Y chromosome specific DNA probe was labeled with digoxigenin through polymerase chain reaction incorporation. After treatment of paraformaldehyde-fixed, diethylglycoldiesterate-embedded tissue sections with deoxyribonucleic acid decondensation and proteolytic digestion, non-fluorescent, non-isotopic in situ hybridization was performed on the retina sections. Most extensive treatment was required for the outer nuclear layer while the inner nuclear layer required more extensive treatment than the retinal pigment epithelial cells. Under optimal pretreatment conditions, the male cat retina displayed black spots which specifically localized at the periphery of the nuclei, while the female cat retina showed negative staining for the Y chromosome specific probe. The technique allows observation of the Y chromosome signal with preservation of retinal morphology and thus may be a valuable tool to discriminate donor cells in retinal pigment epithelial cell and photoreceptor cell transplants.

The X1X2Y sex chromosome system in the fish Hoplias malabaricus. II. Meiotic analyses

The neotropical fish Hoplias malabaricus shows diversified cytotypes and may represent a group of distinct species. One of these cytotypes is characterized by 2n = 40 and 2n = 39 chromosomes in females and males, respectively, with a multiple sex chromosome system of the X1X1X2X2/X1X2Y type. The Y, representing a large chromosome in male karyotype, is derived from a translocation event between two biarmed chromosomes: one of them similar to X1 chromosome (no. 6) and another one similar to X2 chromosome (probably no. 20). Meiotic data (standard and synaptonemal complexes analyses) show 18 bivalents and one characteristic trivalent in pachytene and metaphase I spermatocytes, as well as two kinds of metaphase II cells with 19 and 20 chromosomes. The trivalent is formed by the Y, X1 and X2 chromosomes and usually presents a complete pairing in pachytene. However, trivalents with partially or fully asynapsed segments are also observed. These segments are assumed to be non-homologous regions of the X1 and X2 chromosomes without correspondence with the Y chromosome, which can heterosynapse. This behaviour of the sex trivalent leading to a fully paired structure, taken together with the close frequencies of the two spermatocyte types at metaphase II, suggests a normal pattern for male H. malabaricus meiosis, representing a stabilized multiple sex chromosome system in this species.

Chromosome pairing in inter-racial hybrids of the house musk shrew (Suncus murinus, Insectivora, Soricidae)

Two chromosome races of the house shrew Suncus murinus that differ from each other for five Robertsonian translocations (8.17, 9.13, 10.12, 11.16, and 14.15), heterochromatic insertions in chromosomes 7 and X, and multiple rearrangements in the Y chromosome were crossed and then intercrossed in captivity to produce a hybrid stock. Electron-microscopic analysis of synaptonemal complexes in fertile and sterile hybrid males was carried out. Meiosis in sterile males did not progress beyond pachytene and was severely disrupted. Meiotic arrest was not determined by structural heterozygosity: heterozygotes for all variant chromosomes distinguishing two parental races were found in both sterile and fertile male hybrids. Fertile hybrids demonstrated an orderly pairing of all chromosomes. In heterozygotes for Robertsonian fusions, completely paired trivalents were formed between the Robertsonian metacentrics and homologous acrocentrics. In heterozygotes for chromosome 7, bivalents with a small buckle were observed in a small fraction of pachytene cells. No differences were found in the morphology and pairing pattern of sex bivalents, composed of the X and Y chromosomes derived from the same or different parental races. Univalents, multivalents, and associations between X and Y chromosomes and autosomal trivalents, as well as associations of autosomal trivalents with each other, were observed in a small fraction of the pachytene cells of fertile males. Our results indicate that the system controlling male sterility in interracial hybrids of S. murinus is of genic rather than of chromosomal type.

Synaptonemal complex analysis of the X1X2Y trivalent in Mantis religiosa L. males: inferences on the origin and maintenance of the sex-determining mechanism

Characterization of sex chromosomes in males of Mantis religiosa L. (2n = 24 + X1X2Y) was carried out by C-banding, silver staining and fluorescence in situ hybridization. They are meta- or submetacentric, their arms being designated as X1L, X1R, X2R, X2L, YL and YR. Meiotic behaviour of the sex trivalent was examined through the analysis of synaptonemal complexes (SCs), prometaphase I (metaphase I) and metaphase II nuclei. On the basis of the SC analysis, chromosomal length measurements at mitosis and prometaphase I and data from several orthopteran species, it is proposed that the breakpoints of the reciprocal translocation that originated this complex sex-determining mechanism were close to the centromeres of the X and the largest autosome, and that the asynapsed X1L and X2R regions observed in the sex trivalent at pachytene represent the original X chromosome. The X centromere being probably that of the X2 element because it lacks a partner in the SC pachytene trivalent. The relationship among synaptic pattern, chiasma localization and balanced segregation of the sex trivalent is also discussed.

Y-autosome translocation and infertility: usefulness of molecular, cytogenetic and meiotic studies

An apparently balanced reciprocal translocation 46,X,t(Y;6) (q11.23 approximately q12;p11.1) was observed in an infertile man with severe oligozooteratozoospermia. Different mitotic chromosome banding patterns were performed and fluorescence in situ hybridization indicated a breakpoint in the fluorescent Yq heterochromatin. Molecular genetic deletion experiments for the azoospermia factor region in distal Yq11 showed the retention of the DAZ gene and meiotic pairing configurations suggested that the man's infertility could be due to the pairing behaviour of the Y;6 translocation chromosome with the X chromosome visualised by synaptonemal complex analysis at the electron microscopy level. The morphological appearance of the normal chromosome 6 and the Y;6 translocated chromosome included in the compartment of the sex vesicle may allow an explanation of the degeneration of most spermatocytes after the pachytene stage.

Sequences from higher primates orthologous to the human Xp/Yp telomere junction region reveal gross rearrangements and high levels of divergence

A high level of sequence polymorphism combined with linkage disequilibrium has created a limited number of highly diverged haplotypes across the human Xp/Yp telomere junction region. To gain insight into the unusual genetic characteristics of this region, we have examined the orthologous sequences in the common chimpanzee (Pan troglodytes ), the gorilla (Gorilla gorilla) and the orang-utan (Pongo pygmaeus). Divergence from the human Xp/Yp sequence is higher (average 2.6-fold) than that observed at other loci. The position of the human Xp/Yp telomere is unique, as additional sequences are present at this location in the other three species. These included an array of subterminal satellite in the chimpanzee and, in the gorilla a small interstitial array of telomere-like repeats followed by sequences with strong homology to the human 18p subterminal region. In the orang-utan, two alleles with different structures were identified. These differ by the presence or absence of a short interspersed nuclear element (SINE) sequence just proximal to long arrays of telomere-like repeat sequences that probably represent the proximal end of the orang-utan Xp/Yp telomere. In addition, a high level of sequence divergence between the two orang-utan structures was identified. This divergence is similar to that observed between the human Xp/Yp telomere-adjacent haplotypes. The high sequence divergence and evidence of gross rearrangements indicate that the Xp/Yp telomeric region has evolved faster than the rest of the genome.

The prevalence of a YY synaptonemal complex over XY synapsis in an XYY man with exclusive XYY spermatocytes

An infertile XYY man was studied by synaptonemal complex analysis of microspread spermatocytes and by quantitation of germ cells in semithin sections. All the 74 spermatocytes micrographed have an XYY constitution, and the biopsy shows a homogeneous arrest of spermatogenesis at the spermatocyte/young spermatid stages. The overwhelming majority (86%) of spermatocytes showed a Y-Y bivalent plus a univalent X. The Y-Y bivalent is totally synapsed in 48% of the cells. In the remaining cells, the YY bivalent has an average synaptic segment covering 43% of its length that always includes Yp. Another 9% of the spermatocytes showed an XYY trivalent and 4% of the spermatocytes showed univalence of the three gonosomes. Progression through all the pachytene substages was observed in cells with the two main synaptic configurations, but a high level of germ cell death was observed at or immediately after the meiotic divisions. The prevalence of Y-Y synapsis arises from the longer homologous region and the higher speed of pairing between the two Y chromosomes. Germ cell death is probably related to the univalence of the X chromosome. Synaptic competition between three gonosomes seems to be similar to that found in triploid birds but is somewhat different from that of XYY mice.

Centromeric inactivation in a dicentric human Y;21 translocation chromosome

A de novo dicentric Y;21 (q11.23;p11) translocation chromosome with one of its two centromeres inactive has provided the opportunity to study the relationship between centromeric inactivation, the organization of alphoid satellite DNA and the distribution of CENP-C. The proband, a male with minor features of Down's syndrome, had a major cell line with 45 chromosomes including a single copy of the translocation chromosome, and a minor one with 46 chromosomes including two copies of the translocation chromosome and hence effectively trisomic for the long arm of chromosome 21. Centromeric activity as defined by the primary constriction was variable: in most cells with a single copy of the Y;21 chromosome, the Y centromere was inactive. In the cells with two copies, one copy had an active Y centromere (chromosome 21 centromere inactive) and the other had an inactive Y centromere (chromosome 21 centromere active). Three different partial deletions of the Y alphoid array were found in skin fibroblasts and one of these was also present in blood. Clones of single cell origin from fibroblast cultures were analysed both for their primary constriction and to characterise their alphoid array. The results indicate that (1) each clone showed a fixed pattern of centromeric activity; (2) the alphoid array size was stable within a clone; and (3) inactivation of the Y centromere was associated with both full-sized and deleted alphoid arrays. Selected clones were analysed with antibodies to CENP-C, and staining was undetectable at both intact and deleted arrays of the inactive Y centromeres. Thus centromeric inactivation appears to be largely an epigenetic event.

A novel Mr 77,000 protein of the XY body of mammalian spermatocytes: its localization in normal animals and in Searle's translocation carriers

We describe a novel XY body protein of rat and mice pachytene spermatocytes called XY77. Biochemical characterization showed that protein XY77 (Mr 77,000; pH value 8.3) is present in meiotic but absent in postmeiotic stages of spermatogenesis. With the aid of an antibody against protein XY77 together with another specific for XY body-associated protein XY40 we also investigated the localization of these proteins in mice carrying Searle's translocation, a reciprocal X-autosomal translocation. We show here that in these mice the distribution of both XY77 and XY40 is abnormal. Our results indicate that in Searle's translocation alterations are not restricted to the translocated autosome, but also involve chromatin segments corresponding originally to the sex chromosomes X and Y.

Fluorescent in situ hybridization (FISH) analysis of the relationship between chromosome location and nuclear morphology in human neutrophils

Human neutrophil nuclei typically consist of three of four large heterochromatic lobes joined by thin, DNA-containing filaments. In addition, some lobes exhibit appendages of various sizes and shapes. Classical genetic and cytological studies suggest that some appendages contain specific chromosomes. The studies reported here provide the first detailed analysis of the spatial relationship between individual chromosomes and recognizable structures in neutrophil nuclei using fluorescent in situ hybridization. Analysis of DNA sequences in chromosomes 2, 18, X, and Y demonstrate that specific lobes in a population of neutrophil nuclei do not have a fixed chromosome content. This result implies that chromosomes partition randomly among lobes during neutrophil differentiation. However, neutrophil nuclear topography is not entirely fortuitous. For instance, none of the sequences probed in this study mapped to a filament and most centromeres lie in clusters near the nuclear periphery. In addition, one of the X chromosome centromeres in females and the Y chromosome centromere in males consistently associate with specific nuclear appendages found in a subset of neutrophil nuclei. Chromosomes 2 and 18 occupy discrete nd separate territories within individual lobes and neither territory ever extends into a filament. Surprisingly, the sizes of these territories are not proportional to chromosome length, suggesting that individual neutrophil chromosomes vary in their degree of compaction. These results are discussed in the light of models that attempt to explain nuclear morphology in terms of chromosome spatial organization.

Submicroscopic deletions in the Y chromosome of infertile men

Recent investigations have suggested a high prevalence of Y chromosome submicroscopic deletions in men with severely impaired spermatogenesis. We evaluated the frequency of Y chromosome deletions in 160 infertile men using a series of 36 sequence-tagged-sites, emphasizing intervals 5 and 6 of the long arm of the Y chromosome. Peripheral leukocyte DNA was extracted and amplified with two parallel techniques to minimize potential overestimation of the frequency of deletions. The presence of deletions was evaluated relative to patient's sperm concentration, testis volume, and hormonal parameters. Men with sperm concentration <5 x 10(6)/ml had a 7% prevalence of submicroscopic Y chromosome deletions. Deletions were detected in 7% of azoospermic men, 10% of men with <1 x 10(6) spermatozoa/ml, and 8% of men with >1 x 10(6) but <5 x 10(6) spermatozoa/ml. Other clinical parameters did not identify men with Y chromosome deletions prior to polymerase chain reaction (PCR)-based testing for the presence of sequence-tagged-sites. Two distinct regions of Y chromosome deletions were detected, approximately 3.6 Mb and 1.4 Mb in length respectively. These deleted regions are present in AZFb and AZFc respectively. No deletions were detected in AZFa. The loss of these two distinct areas is supported by the finding of highly repetitive sequences along the Y chromosome, predisposing to deletion of specific intervals on the Y chromosome during meiosis. Men with severe male infertility are at high risk for Y chromosome deletions. Testing of men for these genetic abnormalities is indicated prior to treatment with assisted reproduction.

Shared DNA sequences between the X and Y chromosomes in the tammar wallaby - evidence for independent additions to eutherian and marsupial sex chromosomes

Marsupial sex chromosomes are smaller than their eutherian counterparts and are thought to reflect an ancestral mammalian X and Y. The gene content of this original X is represented largely by the long arm of the human X chromosome. Genes on the short arm of the human X are autosomal in marsupials and monotremes, and represent a recent addition to the eutherian X and Y. The marsupial X and Y apparently lack a pseudoautosomal region and show only end-to-end pairing at meiosis. However, the sex chromosomes of macropodid marsupials (kangaroos and wallabies) are larger than the sex chromosomes of other groups, and a nucleolus organizer is present on the X and occasionally the Y. Chromosome painting using DNA from sorted and microdissected wallaby X and Y chromosomes reveals homologous sequences on the tammar X and Y chromosomes, concentrated on the long arm of the Y chromosome and short arm of the X. Ribosomal DNA sequences were detected by fluorescence in situ hybridization on the wallaby Xp but not the Y. Since no chiasmata have been observed in marsupial sex chromosomes, it is unlikely that these shared sequences act as a pseudoautosomal region within which crossing over may occur, but they may be required for end-to-end associations. The shared region of wallaby X and Y chromosomes bears no homology with the recently added region of the eutherian sex chromosomes, so we conclude that independent additions occurred to both sex chromosomes in a eutherian and macropodid ancestor, as predicted by the addition-attrition hypothesis of sex chromosome evolution.

Evaluating sex chromosome content of sorted human sperm samples with use of dual-color fluorescence in situ hybridization

OBJECTIVE

Although most methods for selecting the sex of offspring by sorting spermatozoa are ineffective at shifting the ratio of Y- to X-containing cells, some commercial sources continue to offer such services. Our objective was to evaluate commercially "sorted" samples with use of dual-color fluorescence in situ hybridization and to identify variations in assessment by comparing motile and total sperm populations, donors, observers, and fluorescence in situ hybridization probes.

STUDY DESIGN

Cryopreserved sperm from seven anonymous donors were processed as for insemination. Sperm cells from each total sample or motile subfraction were prepared for fluorescence in situ hybridization by incubation with disulfide-reducing agents to expand sperm nuclei. Two sets of X and Y chromosome-specific, fluorophore-labeled deoxyribonucleic acid probes were used. At least 400 nuclei from each preparation were classified independently by three blinded observers. Hybridization efficiency, aneuploidy, and sex chromosome content were evaluated in subsets of five unsorted, five female-oriented, and five male-oriented samples. Total and motile subfractions were compared with eight samples. Fluorescence in situ hybridization probes were compared in five paired unsorted samples.

RESULTS

No differences were detected between washed samples and paired motile subfractions. No differences in hybridization and aneuploidy were detected between groups of sorted samples. The Y/X ratio was significantly different between the sorted groups. However, male-oriented samples had a lower Y/X ratio than female-oriented samples did. Observer and probe choice accounted for small but significant variations that did not alter conclusions about the X/Y ratio for sorted samples.

CONCLUSION

In a series of 10 sorted samples from one commercial source, dual-color fluorescence in situ hybridization demonstrated a small but significant shift in the sex chromosome ratios among samples. However, this shift was opposite to that expected by the orientation of the sorted samples.

Classification of the southern African sanga and east African shorthorned zebu

Humped African cattle, which are differentiated into zebu and sanga types, have traditionally been classified as Bos indicus. This paper discusses existing evidence and presents new evidence supporting the classification of southern African sangas as Bos taurus and East African zebus as 'taurindicus'. Classification is based on karyotype, frequencies of DNA markers and protein polymorphisms. The Boran, an East African zebu, has an acrocentric Y chromosome typical of Bos indicus. The southern African sanga breeds have a submetacentric Y chromosome typical of Bos taurus. Frequencies of four DNA markers support the hypothesis that the Tuli, a southern African sanga, had taurine ancestors and the Boran had both taurine and indicine ancestors. Frequencies for several protein polymorphisms strongly suggest that southern African sangas have more in common with taurine than with indicine breeds, while East African zebus are an admixture of African taurine and Asian indicine breeds.

[Chromocenter organization in salivary glands of the malaria mosquito Anopheles messeae Fall]

The chromocenter organization and the relationship with the nuclear envelope were studied in Anopheles messeae Fall. malaria mosquito. The interchromosomal contacts within the chromocenter were shown to be formed by both alpha- and beta-heterochromatin. In the pericentric regions of all chromosomes and in highly repeated sequences localized mostly in alpha-heterochromatin, the incorporation of the moderate He-T repeat of D. melanogaster was also found. Each chromosome was shown to have an independent contact to the nuclear envelope via certain beta-heterochromatin loci. The morphology of the Y chromosome, which is also capable of forming ectopic contacts within the chromocenter boundaries, was studied.

A human candidate spermatogenesis gene, RBM1, is conserved and amplified on the marsupial Y chromosome

Three genes, RBM1, DAZ and TSPY, map to a small region of the long arm of the human Y chromosome which is deleted in azoospermic men. RBM1, but not DAZ or TSPY, has a Y-linked homologue in marsupials which is transcribed in the testis. This suggests that RBM1 has been retained on the Y chromosome because of a critical male-specific function. Marsupial RBM1 is closely related to human RBM1, but, like the related autosomal gene hnRNPG, lacks the amplification of an exon. This suggests that RBM1 evolved from hnRNPG at least 130 million years ago and has undergone internal amplification in primates, as well as independent amplification in several therian [corrected] lineages.

Isolation and characterization of X chromosome-derived DNA sequences from a dioecious plant Melandrium album

A number of X chromosome DNA sequences have been isolated from a dioecious plant, Melandrium album (syn. Silene latifolia), using chromosome microdissection followed by degenerate oligonucleotideprimed polymerase chain reaction (DOP-PCR) amplification. Six DNA clones were selected and further characterized by DNA/DNA hybridization techniques to check their copy numbers, sex-specific methylation patterns, species specificity and positions on chromosomes. These clones were moderately to highly repetitive (approximately 10(3)-10(5) copies per haploid genome) and none of them gave a positive signal on Northern blots. One of the clones yielded a sex-specific methylation pattern: its abundant non-methylated CCGG island was found only in males. All the clones also hybridized to two closely related dioecious Melandrium species (M. rubrum and M. dicline). Nucleotide sequences of two X-derived clones showed a number of internal short direct repeats; one of them strikingly resembled a plant conservative telomere sequence (TTTAGGG). None of the clones hybridized to the X chromosome only, but all were localized at the telomeric heterochromatic regions (DAPI C-bands) of both arms of a vast majority of M. album chromosomes using the fluorescence in situ hybridization (FISH) technique. However, the non-homologous arm of the Y chromosome (contrary to the arm homologous to the X chromosome, possessing the pseudoautosomal region) showed neither a DAPI C-banding-stained heterochromatin nor a FISH signal with any of the DNA probes tested, thus indicating its evolutionary diversification.

The origin and distribution of the Lund Y chromosome in Microtus agrestis (Rodentia, Mammalia)

The Lund Y (Lu-Y) chromosome of the field vole (Microtus agrestis) is distinguished from the standard Y (St-Y) by its much longer short arm. G-banding revealed that the Lu-Y originated by a pericentric inversion in the St-Y. Chromosome analysis of 297 male field voles from 92 localities in Fennoscandia. Germany, and England, in addition to data from the literature, made it possible to map the distribution area of the Lu-Y. It is restricted to the south-western parts of Sweden. The question of when and where the Lund Y population originated is discussed. Adding data from a hybrid zone (Jaarola et al. 1997) and from females, totally 491 specimens from 120 localities were analyzed without detecting any variation in chromosome number and autosome morphology. Other cases of intraspecific Y chromosome polymorphism in mammals, and the use of Y chromosome variants as population genetic markers, are discussed.

Mitochondrial DNA and Y chromosome-specific polymorphisms in the Seminole Tribe of Florida

Mitochondrial DNA (mtDNA) sequence variation was examined in 37 Seminoles from Florida by polymerase chain reaction amplification and high resolution restriction endonuclease analysis. The Y chromosome TaqI restriction fragment length polymorphisms detected by the probes 49a, 49f, and 12f2 were examined in the 26 males of this group. Analysis of the mtDNA revealed that all four Native American haplogroups (A, B, C and D) were present in the Seminoles encompassing about 95% of the Seminole mtDNAs. No European mtDNAs were found among the Seminoles, but two mtDNAs (about 5%) were members of the African-specific haplogroup L1, thus indicating that a limited number of African women were incorporated in the Seminole tribe. Analysis of Y chromosome haplotypes supports the hypothesis that haplotypes 18 and 63 are the most likely founding Native American Y chromosome haplotypes from Asia. However, 11% of the Seminole Y chromosomes represented haplotypes generally attributed to Europeans, though none harbored standard African haplotypes. These findings support historical evidence that the Seminole tribe has integrated individuals of European and African ancestry, but suggests that the sex ratio of nonnatives from different continents may have varied.

Comparative analysis of Y chromosome structure in Bos taurus and B. indicus by FISH using region-specific, microdissected, and locus-specific DNA probes

Results of fluorescence in situ hybridization (FISH) of Bos taurus and B. indicus Y chromosomes using the bovine locus-specific Y probes BC1.2 and lambda ES6.0 and region-specific probes of B. indicus and B. taurus Y chromosomes, which were generated by microdissection and DOP-PCR, indicate that the Y chromosomes of B. indicus (BIN Y) and B. taurus (BTA Y) differ by a pericentric inversion. Parts of the short and long arms of the Y chromosome in B. taurus and the distal half of the Y chromosome in B. indicus were microdissected, amplified by DOP-PCR, biotinylated, and rehybridized in situ to the corresponding metaphase chromosomes to test the chromosome fragment specificity of the DNA probes. The region-specific painting probes were used for hybridization to metaphase chromosomes of the other species. The DNA painting probes BTA Yp12 and BTA Yq12.1-ter derived from BTA Y hybridized to the distal and proximal halves of BIN Y, respectively. Complex hybridization signals on BTA Yq12.1-->qter were generated with the DNA probe BIN Yqcen-centr (centromere-central) after FISH. The results demonstrate that BTA Yp is homologous to the distal half of BIN Y and that BTA Yq corresponds to the proximal part of BIN Yq. Hybridization of the Y chromosome-specific DNA probes lambda ES6.0 to BTA Yp12-->p11 and near to the telomere of BIN Y and BC1.2 to BTA Yq12-->q13 and to the telomere of BIN Y indicate an opposite orientation of the homologous chromosome fragments BTA Yp and of the distal half of BIN Yq.

Comparison of automated and manual analysis of interphase in situ hybridization signals in tissue sections and nuclear suspensions

In this study we compared visual and automated analyses of interphase in situ hybridization (ISH) signals in five prostatic tumor specimens and one normal prostate sample, both in tissue sections and nuclear suspensions. The advantage of tissue sections is preservation of tissue morphology allowing precise analysis of tumor cells only. The advantage of nuclear suspensions is easier access to automated analysis, due to their disaggregated and dispersed cellular appearance. The samples were hybridized with probes for the (peri)centromeric regions of chromosome 1 and Y. The number of ISH signals per nucleus was counted both manually and automatically by means of a commercially available image analysis system. After image analysis the results were interactively corrected using a gallery display. The automatic and manual counts, before and after interactive correction, were then statistically evaluated. We found no significant differences in overall distributions between the automated and the manual counts, before as well as after correction. This was observed for both tissue sections and cellular suspensions. It is therefore concluded that automated analysis of ISH signals is feasible in both nuclear suspensions and in tissue sections, despite a low percentage of nuclei that could be measured on the latter.

The license to pair: identification of meiotic pairing sites in Drosophila

Sites for pairing and segregation of achiasmatic bivalents have been characterized in both male and female meiosis in Drosophila melanogaster. The major sex chromosome pairing site in male meiosis corresponds to the intergenic spacer repeats of the rDNA arrays, which are located in the heterochromatin of the X and Y. The sex chromosome pairing sites in females are also heterochromatic, but involve different repeated sequences. In males, weak pairing sites are widely distributed along euchromatin but not heterochromatin of chromosome 2, an autosome. One strong site for male meiotic pairing has been identified on chromosome 2; it overlaps with the his locus, which contains the repetitive structural genes for the histones. In females the sites for pairing of chromosome 4, another autosome, are restricted to the heterochromatin. Thus for both sex chromosomes and autosomes, sites for achiasmatic pairing are heterochromatic in females but euchromatic (except for the rDNA) in males. The possible roles of sequence repetition and of transcription in chromosome pairing are discussed.

Meiotic behavior of the X1X2Y1Y2 quadrivalent of the primate Alouatta caraya

A multiple sex chromosome system was found in three unrelated individuals of the primate Alouatta caraya. This mechanism is originated by a translocation between the Y chromosome and one of the autosomes (A7). Mitotic karyotypes show two small, acrocentric chromosomes (AY and YA), which are the translocation products. In metaphase I of male meiosis, there is a very long chain quadrivalent in which the order of the element is: X-YA-A7-AY. Segregation in the quadrivalent is alternate and gives balanced products. Synaptonemal complex karyotypes at pachytene show the structure of the quadrivalent made by the four axes. There is a slight difference in the relative length of AY and YA and the kinetochore of A7 aligns with that of AY. The synaptic pattern and changes in the quadrivalent during pachytene are described. Thin sections of the quadrivalent body show that the chromatin packing in the sex chromosome region is different from that of the autosomal region. This X1X2Y1Y2/X1X1XX2 sex chromosome system may be extended among other members of the genus Alouatta.

High-resolution fluorescence in situ hybridization of RBM- and TSPY-related cosmids on released Y chromatin in humans and pygmy chimpanzees

Applying two-colour fluorescence in situ hybridization (FISH) we simultaneously hybridized RBM- and TSPY-related cosmids to Y chromosomes in prophase and to released Y chromatin in interphase nuclei of man and pygmy chimpanzee. Whereas, even on prophasic Y chromosomes, no resolution of the overlapping RBM and TSPY signal clusters could be achieved, the RBM and TSPY signals are completely separated from each other in our maximum released Y chromatin stretches in interphase nuclei. These results unequivocally lend support to the view that the RBM and TSPY families have an interspersed organization on the Y chromosomes of man and higher apes. Thus, the distribution of RBM and TSPY signals might well go back to a common organization of these genes next to each other on an ancient Y chromosome.

Strukturdifferenzierungen in Y-chromosom von Drosophila hydei: the unique morphology of the Y chromosomal lampbrush loops Threads results from 'coaxial shells' formed by different satellite-specific subregions within megabase-sized transcripts

The results of pulsed-field gel electrophoresis (PFGE) analysis and two-colour transcript fluorescence in situ hybridization (FISH) for the three Threads-specific DNA satellites YLII, YLI and rally are in support of long-range clustering of these sequence families within the subterminal region on the long arm of the Y chromosome of Drosophila hydei. On the basis of the linear arrangement of at least four extended clusters of satellite-specific sequences, the loop morphology of wild-type and several mutant Threads can be explained by assumption of a single Threads-specific transcription unit comprising about 5.1 Mb of repetitive DNA located between the Pseudonucleolus and the Nucleolus organizer. Transcription is unidirectional from the Pseudonucleolus towards the terminally located Nucleolus organizer. Transcripts most likely start in front of or within the 3.2 Mb region of YLII-related sequences, pass through subsequent blocks of 1.2 and 0.3 Mb of YLI- and rally-related sequences, respectively, and cease within the region of a smaller block of YLI-related repeats. The megabase-sized transcripts remain physically linked to the DNA axis and their extended satellite-specific regions form coaxial clouds or shells around the central DNA axis. In this way each cluster of earlier-transcribed sequences generates a cloud or shell on top of the later-transcribed ones. According to this model of 'satellite-specific coaxial shells' the tube-like morphology and other peculiarities of the Y chromosomal lampbrush loops Threads can be explained as a result of satellite-specific RNA superstructures and/or formation of extended ribonucleoprotein (RNP) complexes between clusters of satellite-specific transcripts and specific proteins. On the basis of this model the specific morphology of several Threads mutants can be interpreted as the result of large interstitial or terminal deletions that alter the total length of the Threads-specific transcription unit without exerting other major effects on principal features of the transcription process along the Threads.

Spermatogenesis in Drosophila

A short summary on the present knowledge on spermatogenesis in Drosophila is given which also points out particular questions of interest in the context of this morphogenetic process. Such points of interest are the formation of lampbrush loops in primary spermatocytes, the chromosomal events during meiosis, the occurrence of chromatin rearrangements and the regulation of gene activities at the posttranscriptional level. The activities and some major conclusions from my laboratory are subsequently described. They include studies of the expression of histone variants, the structure and function of lampbrush loops and the expression of genes participating in sperm morphogenesis.

Spatial distribution of sex chromosomes and ribosomal genes: a study on human lymphocytes and testicular cells

The location of the sex chromosomes in relation to the rRNA genes in the nuclei of human lymphocytes and testicular cells was examined. Sex chromosomes were found to be located closer to ribosomal genes than would be expected assuming a random arrangement of these chromosomes with respect to rRNA genes. This proximity could be observed irrespective of the transcriptional activity of ribosomal genes indicating that the chromosomal material and not transcriptional activity is responsible for the intranuclear order of these chromosomes.

A reassessment of Y chromosomal behaviour in germ cells and Sertoli cells of the mouse as revealed by in situ hybridisation

In situ hybridisation experiments were carried out to reappraise the state of condensation of the Y chromosome in germ cells and Sertoli cells of the mouse. Previous work had suggested that all testicular cells showed a condensed Y chromosome prior to the adult stage. We now demonstrate that, although the Y chromosome is condensed in pre-pubertal Sertoli cells, it is greatly expanded in primordial germ cells (gonocytes). An expanded Y-signal is first seen in Sertoli cell nuclei at or around day 21 of postnatal development, coinciding with the first appearance of spermatids in the germinal epithelium.

Molecular mapping of the putative gonadoblastoma locus on the Y chromosome

Based on the high incidence of gonadoblastoma in females with XY gonadal dysgenesis or 45,X/46,XY mosaicism, the existence of a susceptibility locus on the Y chromosome (GBY) has been postulated. We attempted to map GBY by making use of a recently developed dense map of Y-chromosomal sequence-tagged sites (STSs). In two female patients with gonadoblastoma, small marker chromosomes contained portions of the Y chromosome, and a single region of overlap could be defined extending from probe pDP97 in interval 4B, which contains the centromere, to marker sY182 in interval 5E of the proximal long arm. This interval is contained in a YAC contig that comprises approximately 4 Mb of DNA. Our findings confirm the previous localization of GBY and greatly refine it. The localization of GBY overlaps with the region to which a putative growth determinant, GCY, was recently assigned.

Twin pregnancies with complete hydatidiform mole and coexisting fetus: use of fluorescent in situ hybridization to evaluate placental X- and Y-chromosomal content

Twin pregnancies with a complete hydatidiform mole (CHM) and a coexisting fetus have an aggressive postevacuation behavior; it is, therefore, important to differentiate these cases from partial hydatidiform moles that rarely require treatment for late sequelae. It has been presumed that twin pregnancies with a CHM and a coexistent fetus are dizygotic gestations, but this has not been confirmed in most cases. The authors investigated the sex chromosomal constitution of paraffin-embedded, formalin-fixed placental tissues in nine pregnancies histopathologically diagnosed as twin gestations with CHM and coexisting fetus, using fluorescent in situ hybridization (FISH) with X- and Y-chromosomal probes. Normal placental tissues showed an even sex distribution--four cases: X signal only, presumably female; four cases: X and Y signals, presumably male. In contrast, all molar tissues of these same pregnancies hybridized with the X-chromosomal probe only. Thus, in four of nine cases, gender differences (ie, different sex chromosome content) in molar villi (X chromosome only, cytogenetic female) versus normal villi (both sex chromosomes, cytogenetic male) confirmed the histopathological diagnosis of dizygotic twinning; a strict relationship between villous morphology (molar vs normal) and chromosomal gender was observed in each instance. This study illustrates that use of FISH on paraffin-embedded tissues can retrospectively establish dizygotic twinning in this unusual type of molar gestation.

Electron microscope investigation of polytene chromosomes in the Mediterranean fruit fly Ceratitis capitata

Ultrastructural analyses of polytene chromosomes from male pupal orbital bristle cells and from larval salivary glands of Ceratitis capitata were carried out. It was shown that chromatin complexes corresponding to the X chromosome heterochromatic network are surrounded by material containing ribonucleoprotein (RNP) granules 250-300 A (1 A = 0.1 nm) in diameter. RNP granules of similar size surround the spherical Y chromosome. These data point out the presence of transcriptional activity in both of these chromosomes. The absence of clear structure in chromosomal regions situated between large bands in both types of tissues was observed. These results support the hypothesis of weak synapsis between chromatids or small chromomeres of polytene chromosomes in this species. In addition, we describe a specific puff revealed in both orbital trichogen cells and salivary glands that is morphologically similar to the 93D puff of Drosophila melanogaster.

Identification of male epithelial cells in routine postcoital cervicovaginal smears using fluorescence in situ hybridization. Application in sexual assault and molestation

In a prospective blinded controlled study, the efficacy of fluorescence in situ hybridization (FISH) to detect non-sperm male cells verifying sexual contact was examined. Cervicovaginal smears (CVS) from 40 women with reported post-coital intervals were examined for sperm by cytology and for sperm and non-sperm male cells by FISH using X and Y chromosome specific DNA probes. Fluorescence in situ hybridization identified sperm and/or non-sperm male cells in all specimens from women with positive coital histories, including when the partner had a vasectomy. Male cells were also detectable by FISH in CVS up to 3 weeks after coitus. In comparison, cytology identified sperm in 41% of the positive coital history cases, and none beyond 2 weeks. Fluorescence in situ hybridization is highly sensitive and specific in detecting male cells, and can be performed rapidly on routine CVS. Application of this technique can provide new and additional evidence of sexual contact when current tests are inconclusive.

Y chromosomal effects on hippocampal mossy fiber distributions in mice selected for aggression

The influence of the non-pseudoautosomal region of the Y chromosome (YNPAR) on the sizes of the hippocampal intra- and infrapyramidal mossy fiber (IIPMF) terminal fields were examined in wild house mice. For this purpose selection lines for short attack latency (SAL), long attack latency (LAL), and their respective congenics for the YNPAR were used. We found an incremental effect of the (non-aggressive) LAL YNPAR, combined with an additive effect of the line background on the sizes of the IIPMF terminal fields. In contrast, only the line background affected attack latency. The implications of this finding for the previously observed correlation between the size of the IIPMF and aggression in male house mice are discussed.

[Identification of sex chromosome markers using fluorescence in situ hybridization (FISH)]

From 6 to 15% of the patients with Turner syndrome have a mosaic karyotype, i.e. a 45,X cell line and another with a small sex chromosome marker of undetermined origin which may be a ring or a centric fragment. It is important to establish whether this marker chromosome derives from a Y chromosome as this implies that the patient has a high risk of developing gonadoblastoma. The objective of the present paper was to identify the origin of small sex chromosome markers using fluorescence in situ hybridization (FISH). Eight patients were studied; seven had a Turner phenotype and one had a short stature with ambiguous genitalia. In all cases karyotype in peripheral lymphocytes showed mosaicism, with one cell line that had a sex chromosome marker, and in three cases, the mosaicism was corroborated in fibroblast cultures. Biotin labeled DNA probes with complementary centromeric alpha-satellite sequences of chromosomes X and Y were used in the FISH technique. In seven patients the chromosome marker came from the X chromosome as established with the X chromosome alpha-satellite probe. In the patient with ambiguous genitalia, the marker did derive from the Y chromosome. We conclude that the FISH technique proved to be useful to establish the origin of sex chromosome markers in our laboratory.

Complex Y chromosome aberrations are a recurrent secondary event in radiation-induced murine acute myeloid leukaemia

Arbitrarily primed-PCR analysis of DNA from male CBA/H radiation-induced leukaemic spleens revealed the loss of an approximately 350-bp sequence in several leukaemias. We have isolated a lambda EMBL3 C57BL/6 genomic subclone (pJB1) which hybridizes to the AP-PCR probe and is located on the Y chromosome. Southern blot analyses using the pJB1 probe indicate that the genomic sequence was deleted in five of 14 leukaemias. Cytogenetic analyses of 31 X-ray induced leukaemias in male CBA/H mice revealed, in addition to the characteristic partial deletion of chromosome 2 (28/31 leukaemias), a high incidence (16/31) of the loss of an intact Y chromosome. Comparison of the Southern blot and cytogenetic analyses of the leukaemias demonstrate a significant lack of correspondence between the loss of an intact Y chromosome and Y chromosome-specific DNA sequences, suggesting that Y chromosome aberrations are complex. Whereas partial deletion of chromosome 2 can be detected in 6% of bone marrow cells within 6-11 days of irradiation, no Y chromosome involvement was detected, indicating that Y chromosome aberrations are a late event in radiation-induced leukaemogenesis. These findings are comparable to the loss of sex chromosomes in human t(8;21) AML.