Differential condensation of human chromosomes 9 and Y

Some differences were observed in the mitotic condensation of regions composing human chromosomes 9 and Y: regions 9p, 9h and Y nf are characterized by an intense condensation by the end of the spiralization interval studied (the length of the repair chromosome 3 varying from 5.4 to 2.9 mkm). At the same time, the condensation of regions 9q-h (region 9q without heterochromatic block) is slowing in the initial spiralization interval (the length of chromosome 3 varying from 16.6 to 5.5 mkm). The Yf-block of Y-chromosome is condensing faster than nf-region. The condensation parameters of Q-heterochromatic blocks are most variable while the euchromatic regions are most stable. The dynamics of 9h and of f-block condensation are independent within one karyotype. Based on the data obtained we doubt the correctness of studies on linear dimensions of the constitutive heterochromatin blocks for the evaluation of its quantity in the karyotype. A possible association of differential mitotic condensation with the chromosome segregation disturbances is discussed.     

Differential spiralization along mammalian mitotic chromosomes

Morphology of chromosomes replicating in the presence of 5-bromodeoxyuridine was studied using long-term cultures of Chinese hamster cells (line Blld-ii-FAF28). The cytological effect of the analog administered in various concentrations, at different stages of the S period, and during one and two successive mitotic cycles was studied. — The main cytological manifestation of the BUdR action consisted in spiralization delay of certain chromosome regions. The degree of the delay was dependent on the time interval between the introduction of the agent and mitosis, as well as on the agent's concentration. With prolongation of the interval, the spiralization delay diminished and disappeared being therefore always observable only in late replicating chromosome regions. Increased concentration of BUdR (in the range of 25 to 400 g/ml) produced enhancement of the delay of chromosome spiralization. — After two successive reproduction cycles in the presence of BUdR, a great number of metaphases contained chromosomes the sister chromatids of which showed unequal spiralization delay. Autoradiography of ³H-BUdR distribution showed that the sister chromatid with a more pronounced underspiralization corresponds to the chromatid incorporating BUdR into both strands of the DNA molecule. — Mechanisms of the effect observed, as well as chemical influence on chromosome spiralization as a usefull tool of displaying linear chromosome differentiation, are discussed.     

Effects of distamycin A on human leukocytes in vitro.

Distamycin A, an oligopeptide antibiotic, supplied at various concentrations for 24 h to human leukocytes in culture, has induced the appearance on some chromosomes of specific areas lacking spiralization. In particular, the centromeric regions of chromosomes 1, 3 and one C-group chromosome and the distal part of the long arm of the Y chromosome were despiralized. The possible nature of these regions is discussed.     

A t(Y;15) translocation with a deletion of the proximal Yq in a boy with mixed gonadal dysgenesis

Summary A Japanese boy with genital malformation and mixed gonadal dysgenesis is described. The karyotype appeared to be 46,X t(15;Y)(p13;q11). A comparison of the Q-positive segment on der(15) with that of the paternal Y chromosome revealed, however, the loss of over half of the Q-positive segment from the paternal Y during t(15;Y) translocation. The father had an unusually long Y chromosome that corresponded to a chromosome 18. DNA analysis further revealed a deletion of the non-fluorescent part of the long arm of the Y chromosome spanning interval 5–6.     

Evidence on the time of chromosome pairing from the preleptotene spiral stage in Lilium longiflorum “Croft”

A period of chromosome spiralization and contraction was observed between premeiotic interphase and leptotene in Lilium longiflorum Croft. There was variation in the extent of preleptotene spiralization and contraction of chromosomes among microsporocytes, anthers and buds. The chromosomes sometimes contracted sufficiently to be visible as separate entities. It could then be determined that the chromosomes were single and entirely separate; synapsis and crossing-over had not yet occurred. Furthermore there was no evidence of alignment or association of homologues during the preleptotene contraction period; the chromosomes appeared to be distributed at random. The chromosomes subsequently elongated into the leptotene stage. Wherever they were visible separately the chromosomes were single in early leptotene. These observations support the classical view that synapsis of homologous chromosomes takes place during zygotene, followed by crossing-over at pachytene.It is a pleasure to dedicate this paper to Dr. Sally Hughes-Schrader on the occasion of her seventy-fifth birthday.     

Effects of DAPI on human leukocytes in vitro.

DAPI (4'-6-diamidino-2-phenylindole), a fluorochrome specific for AT-rich DNA, was supplied for 24 h at various concentrations to human leukocytes in culture. This treatment caused the appearance on the chromosomes of specific areas lacking spiralization. In particular, the centromeric regions of chromosomes 1,9, and 16, a short region on the long arm of chromosomes 1 and 2, and the distal heterochromatic part of the long arm of the Y chromosome were despiralized. The despiralization pattern of DAPI is compared with those previously obtained with Hoechst 33258 and Distamycin A.     

The relation of temperature to preleptotene chromosome contraction in Lilium

Preleptotene chromosome contraction was observed in individuals of Lilium longiflorum Ace grown at high temperatures in a glasshouse and at moderate or cool temperatures in a lathhouse. The lathhouse plants exhibited an extremely high degree of preleptotene contraction and the glasshouse plants an extremely low degree of preleptotene contraction. It is known that high temperature increases and low temperature decreases the rate of meiosis. Therefore it is proposed that the amounts of preleptotene contraction observed in lathhouse and glasshouse plants reflect the relative durations of the preleptotene contraction stages in these individuals. Differences in degree of chromosome contraction among microsporocytes in different regions of the anther may be attributed to the effects of axial and transverse gradients of metabolism on duration of the preleptotene contraction state. Any genotype that increases or decreases microsporocyte sensitivity to temperature, or otherwise alters the duration of the preleptotene spiralization period, should influence the degree of preleptotene contraction.     

Change in the microchromosome number in the process of macrochromosome spiralization in Gallus domesticus

A correlation of mitotic spiralization of macrochromosomes with a change in the number of microchromosomes is detected. A wave character of microchromosomes variability during spiralization of macrochromosomes is suggested to be due to reversible despiralization of microchromosomes, which is probably a result of the colchicin treatment. Metaphase plates where the range of chromosome 1 length is from 10.5 to 12mu are recommended to calculate the number of microchromosomes.     

Molecular mapping of a Yq deletion in a patient with normal stature

The proximal long arm of the Y chromosome probably contains a gene (GCY) involved in stature determination. Recent reports have proposed the critical region extends from interval 4B to interval 5G (or 5E). In the present study, the deletion breakpoint in a male adult patient of normal height with a 46,X,del(Yq) karyotype was defined by the use of sequence-tagged site markers. The breakpoint was found between sY78 (interval 4B) and sY79 (interval 5A). The existence of a normal stature in this patient suggests that the growth determinant is proximal to sY79, therefore probably located in interval 4B or in proximal interval 5A of the Y chromosome. Received: 22 March 1996     

Molecular analysis of 46,XY females and regional assignment of a new Y-chromosome-specific probe

Summary The relationship between Y-chromosome abnormalities and gonadal differentiation was investigated in six phenotypic females with a 46,XY karyotype and one patient with ambiguous genitalia secondary to apparently nonmosaic 46,XY mixed gonadal dysgenesis. No alterations were found in the Y chromosomes of six of these individuals by the use of either cytogenetic or molecular techniques. Cytogenetic analysis with high-resolution G-banding and Q-banding revealed a small deletion in the short arm of the Y chromosome in one female patient with some features of Turner syndrome. Southern hybridization with Y-specific probes showed a loss of DNA within deletion intervals 1, 2, and 3 of the Y chromosome. A new Y-chromosome-specific DNA probe that hybridizes to deletion interval 3 is described.     

The role of the Y-chromosome in sex determination.

The basic plan of gonadal development in both sexes is female unless testes are induced by factor(s) of the Y chromosome, known as testis determining factor(s) (TDF). It is not clearly established whether the Y chromosome control is autonomous or under the control of a gene on the X chromosome or autosomes. A gene for the H-Y antigen (Histocompatibility-Y antigen) has been postulated to be the factor determining testicular differentiation. Recent studies have demonstrated that the gene for testis determination and the H-Y determinant are two separate entities. Although earlier cytogenetic observations localized TDF on the pericentric region of the short arm of the Y chromosome, subsequent findings by high-resolution chromosome banding and molecular analysis localise TDF to the distal part of the short arm of the Y chromosome, adjacent to the pseudoautosomal region. A candidate for TDF, the ZFY, was localised within the 140 kb interval where the position of TDF was defined, and considered as the TDF gene. However, a smaller gene sequence of 35 kb, the SRY, situated outside the 140 kb ZFY region, has recently been isolated and proved to be the only and the smallest part of the Y chromosome necessary for male sex determination.     

Reciprocal translocation between Y chromosome long arm euchromatin and the short arm of chromosome 1

A case with an apparently balanced reciprocal translocation between the long arm of the Y chromosome and the short arm of chromosome 1 t(Y;1)(q11.2;p34.3) is described. The translocation was found in a phenotypically normal male ascertained by infertility and presenting for intra-cytoplasmatic sperm injection treatment. Histological examination of testicular biopsies revealed spermatogenic failure. Chromosome painting with probes for chromosome 1 and for the euchromatic part of the Y chromsome confirmed the translocation of euchromatic Y chromosomal material onto the short arm of chromosome 1 and of a substantial part of the short arm of chromosome 1 onto the Y chromosome. Among the Y/autosome translocations, the rearrangements involving long arm euchromatin of the Y chromosome are relatively rare and mostly associated with infertility. Microdeletion screening at the azoospermia locus revealed no deletions, suggesting another mechanism causing infertility in this translocation carrier.     

Deletion mapping of H-Y antigen to the long arm of the human Y chromosome

A gene encoding or controlling the expression of the H-Y transplantation antigen was previously mapped to the human Y chromosome. We now report the sublocalization of this gene on the long arm of the human Y chromosome. Eight patients with Y-chromosomal abnormalities were examined with a series of existing and new DNA markers for the Y chromosome. The resulting deletion map was correlated with H-Y antigen expression. We conclude that the H-Y antigen gene maps to a portion of deletion interval 6 that is identified by specific DNA markers.     

草鱼染色体的包装（间期—中期）

以草鱼ＺＣ７９０１细胞株为材料,观察鱼类细胞从间期染色质到中期染色体的包装过程。主要通过（１）分裂期与间期细胞融合,诱导染色体早熟凝集;（２）染色体“伸长”处理;（３）培养细胞的低渗处理;（４）染色质辅展等方法,制作染色体标本,进行扫描和透射电镜观察。观察表明,鱼类染色质的基本结构与哺乳类细胞相同,也是直径约１０ｎｍ的核丝。染色体的色装有两种形式：一种是多级螺旋化形成直径约３００ｎｍ的染色单体,     

Cytogenetic investigations on leucocytes of workers from a cadmium plant.

Chromosome analysis has been performed on workers from a cadmium plant who were exposed to fumes and dust of cadmium and lead. The 35 workers were classified, according to the type and duration of exposure, into a group (cadmium service) exposed to high levels of lead and cadmium in the absence of zinc (23 people) and a group of rolling-mill workers subjected mostly to zinc but also to lower levels of lead and cadmium (12 people). A higher yield of severe chromosome anomalies (chromatid exchange, disturbance of spiralization, chromosome translocation, ring and dicentric chromosomes) together with a total lower number of structural aberrations was observed in the cadmium workers when compared with the rolling-mill group.     

RAPD isolation of a Y chromosome specific ORF in a dioecious plant, Silene latifolia.

Silene latifolia is a dioecious plant and has heteromorphic sex chromosomes: the X and Y chromosomes. The Y chromosome is the largest, and its genetic control seems to be most strict among dioecious plants. To identify the putative sex-determination elements on the Y chromosome, random amplified polymorphic DNA (RAPD) analysis was used to screen for Y chromosome specific DNA fragments, and 31 clones were successfully produced. Genomic Southern hybridization and FISH (fluorescence in situ hybridization) analyses revealed that one of the clones, #2-2, is a Y chromosome specific fragment that has a single copy on the Y chromosome. Sequence tagged site (STS)-PCR analysis also succeeded in amplifying one fragment in males and no fragments in females. Cloning and sequencing of the #2-2 flanking region using inverse PCR revealed an open reading frame (ORF) corresponding to 285 amino acids in length (ORF285), but no expression of the ORF285 gene was identified. ORF285 may be a clue to the origin of dioecy.     

Y chromosome haplogroups and prostate cancer in populations of European and Ashkenazi Jewish ancestry

Genetic variation on the Y chromosome has not been convincingly implicated in prostate cancer risk. To comprehensively analyze the role of inherited Y chromosome variation in prostate cancer risk in individuals of European ancestry, we genotyped 34 binary Y chromosome markers in 3,995 prostate cancer cases and 3,815 control subjects drawn from four studies. In this set, we identified nominally significant association between a rare haplogroup, E1b1b1c, and prostate cancer in stage I (P = 0.012, OR = 0.51; 95% confidence interval 0.30-0.87). Population substructure of E1b1b1c carriers suggested Ashkenazi Jewish ancestry, prompting a replication phase in individuals of both European and Ashkenazi Jewish ancestry. The association was not significant for prostate cancer overall in studies of either Ashkenazi Jewish (1,686 cases and 1,597 control subjects) or European (686 cases and 734 control subjects) ancestry (P(meta) = 0.078), but a meta-analysis of stage I and II studies revealed a nominally significant association with prostate cancer risk (P(meta) = 0.010, OR = 0.77; 95% confidence interval 0.62-0.94). Comparing haplogroup frequencies between studies, we noted strong similarities between those conducted in the US and France, in which the majority of men carried R1 haplogroups, resembling Northwestern European populations. On the other hand, Finns had a remarkably different haplogroup distribution with a preponderance of N1c and I1 haplogroups. In summary, our results suggest that inherited Y chromosome variation plays a limited role in prostate cancer etiology in European populations but warrant follow-up in additional large and well characterized studies of multiple ethnic backgrounds.     

Banding and spiralization of human metaphase chromosomes

Summary A new technique is described which produces spiralization of human metaphase chromosomes. The important feature is heat followed by trypsin treatment. By varying conditions, it is possible to produce bands, spirals and intermediate stages. This provides a new approach to the understanding of banding and chromosome structure.     

Reproductive isolation and environmental adaptation shape the phylogeography of mountain pine beetle (Dendroctonus ponderosae)

Chromosomal rearrangement can be an important mechanism driving population differentiation and incipient speciation. In the mountain pine beetle (MPB, Dendroctonus ponderosae), deletions on the Y chromosome that are polymorphic among populations are associated with reproductive incompatibility. Here, we used RAD sequencing across the entire MPB range in western North America to reveal the extent of the phylogeographic differences between Y haplotypes compared to autosomal and X‐linked loci. Clustering and geneflow analyses revealed three distinct Y haplogroups geographically positioned within and on either side of the Great Basin Desert. Despite close geographic proximity between populations on the boundaries of each Y haplogroup, there was extremely low Y haplogroup mixing among populations, and gene flow on the autosomes was reduced across Y haplogroup boundaries. These results are consistent with a previous study suggesting that independent degradation of a recently evolved neo‐Y chromosome in previously isolated populations causes male sterility or inviability among Y haplotype lineages. Phylogeographic results supported historic contraction of MPB into three separate Pleistocene glacial refugia followed by postglacial range expansion and secondary contact. Distinct sets of SNPs were statistically associated with environmental data among the most genetically distinct sets of geographic populations. This finding suggests that the process of adaptation to local climatic conditions is influenced by population genetic structure, with evidence for largely independent evolution in the most genetically isolated Y haplogroup.