Four human Chromosome 3q and four human Chromosome 21 loci map onto sheep Chromosome 1q

Eight new loci have been assigned to sheep Chromosome (Chr) 1q by use of a chromosomally characterized minipanel of sheep x hamster cell hybrids. Four loci, which have been mapped to the distal region of human Chr 3q, are ceruloplasmin (CP), sucrase isomaltase (SI), glucose transporter 2 (GLUT2), and ectopic viral integration site 1 (EVI1). The other four loci, on human Chr 21, include interferon alpha receptor (IFNAR); interferon inducible protein p78, murine (MX1); collagen type VI, alpha 1 (COL6A1); and S100 protein, beta polypeptide (S100B). All of these loci, except GLUT2 and MX1, have been mapped onto bovine Chr 1 or are syntenic with loci on this chromosome. The in situ localization of transferrin (TF) to sheep Chr 1q42-q45 confirms our previous assignment of this locus and independently anchors the eight new syntenic loci to sheep Chr 1q.     

Chromosome analysis of human sperm

Summary A modified technique has been developed for the visualization of the chromosomes in human sperm. The cytogenetic analysis of 129 G-banded human sperm metaphases of 6 normal donors showed an incidence of structural and numerical chromosome abnormalities of 7.8%. Two out of 129 spermatozoa were aneuploid (1.6%). The frequency of sperms with chromatid-type aberrations was 2.3% (3/129). Chromosome-type aberrations were found in 5 out of 129 (3.9%) spermatozoa. X to Y ratio did not differ significantly from the expected one-to-one ratio. Twenty-six sperm complements from a patient 18–20 months after testes exposure to 30 Gy were examined. A significant increase of numerical and structural chromosome abnormalities was not observed. Chromatidtype aberrations were found in two sperm complements (7.7%) and chromosome-type aberrations in one sperm complement (3.9%). The cytogenetic analysis of 15 human sperms from a cancer patient 26 months after chemotherapy showed an increased frequency of aberrant sperm complements (33.4%). One chromatid-type (6.7%), three chromosometype aberrations (20.0%) and one (6.7%) hyperploid sperm complement could be observed. The sample size is still too small to answer the question whether chemical mutagens may increase the frequency of chromosomal abnormalities in human sperm.     

Chromosome anomalies in human azoospermia

The anomalies of genome were found as a result of cytogenetic study of three azoospermic men. In two cases, the circular Y chromosome was revealed. Different methods of chromosome staining demonstrated complete loss of heterochromatic portion of the long arm of the Y chromosome in one case, and the absence of the euchromatic region in another. A balanced translocation among the chromosomes 1 and 15 was observed in the third case. A question concerning disturbances of spermatogenesis having chromosomal etiology is discussed.     

Chromosome 1 in human colorectal tumors

Summary The significance of short and long arm anomalies of chromosome 1 was investigated in 55 colorectal tumors comprising 41 carcinomas and 14 adenomas. The tumors were at various stages of transformation from adenoma to carcinoma. Our investigation was prompted by the observation of a p32-pter deletion on the short arm of chromosome 1 in a case of benign tubulovillous adenoma with mild dysplasia, as well as by frequent reports that chromosome 1 is involved in many neoplastic processes. Long arm anomalies were found in seven of the 41 carcinomas, six of which were in stage B2, and short arm anomalies in ten carcinomas at various stages. Three of the adenomas exhibited chromosome 1 anomalies, which in one case comprised a 1p32-pter deletion only. Overall, short arm anomalies especially concerned the p32–36 region. These results suggest that the cytogenetic anomalies respectively located on the short and long arms of chromosome 1 should be considered separately. Damage to the long arm might constitute a late non-specific event, whereas damage to the p32-pter region of the short arm might be involved in triggering colorectal tumor development.     

Chromosome abnormalities in the human oocyte

Aneuploidy is the most commonly occurring type of chromosome abnormality and the most significant clinically. It arises mostly due to segregation errors taking place during female meiosis and is also closely associated with advancing maternal age. Two main aneuploidy-causing mechanisms have been described: the first involves the non-disjunction of entire chromosomes and can take place during both meiotic divisions, whereas the second involves the premature division of a chromosome into its 2 sister chromatids, followed by their random segregation, upon completion of meiosis I. To elucidate the causal mechanisms of maternally derived aneuploidy and the manner with which they affect the 2 meiotic divisions, a large number of oocytes and their corresponding polar bodies have been examined. Various classical and molecular cytogenetic methods have been employed for this purpose, and valuable data have been obtained. Moreover, research into the gene expression patterns of oocytes according to maturity, maternal age, and chromosome status has provided a unique insight into the complex nature of the biological processes and genetic pathways regulating female meiosis. Findings obtained from the cytogenetic and molecular analysis of oocytes will be reviewed in this article.     

Chromosome changes and human malignant tumors

The data from home and foreign literature on chromosome changes in human tumours of different genesis and localization are analyzed. The role and significance of changes in the chromosome structure in malignant cells are discussed.     

Chromosome abnormalities in human cancer and leukemia

The meaning and application of chromosomal (cytogenetic, karyotypic) changes in human leukemia and cancer have been succinctly reviewed in this article. Thus, the usefulness of these changes in the diagnosis, classification and prognosis of various leukemic conditions and, more recently, of solid tumors is stressed and their application to molecular studies indicated. The meaning of primary (specific) and additional (secondary) karyotypic changes in malignant and benign tumors is discussed. Tables containing the common cytogenetic changes in leukemias and tumors, including benign ones, are included.     

Chromosome replication in aging human diploid fibroblasts

The patterns of termination of DNA replication in human embryonic MRC-5 fibroblasts at four passage levels have been examined by autoradiography. Only chromosome 9 showed statistically significant differences in the time of replication among cultures of different ages. This chromosome terminated replication earlier at later passages than at earlier passages, primarily because of differences in the time of replication of the centromere region. Because very few differences were observed at different passage levels, we conclude that changes in the order of chromosome replication are unlikely to contribute to the phenomenon of in vitro senescence.     

Chromosome arrangements in human fibroblasts at mitosis

Summary The positions of the centromeres of all 46 human chromosomes were analysed in three dimensional reconstructions of electron micrographs of 10 serially sectioned unpretreated human male fibroblast cells. The reconstructions show that the spatial positioning of the chromosomes during division is not random. The centromeres were arranged on a metaphase plate that was ellipsoidal and that tended to be flat. The distance of centromeres from the centre of the mitotic figure was correlated with chromosome size; small chromosomes tended to be central in all the metaphases. Large chromosomes were more peripheral, especially in cells that were more advanced in mitosis. Thus, there is a tendency for larger chromosomes to move outwards as metaphase advances. In many cells, the A group centromeres were overdispersed, whereas G group centromeres tended to be clustered. The acrocentric chromosomes (D and G groups) also tended to be clustered when analysed together, probably reflecting associations in nucleoli at the previous interphase. The results show that chromosome disposition is non-random and that it changes during division.     

Chromosome studies in human in vitro fertilization

Summary The chromosome constitution of 22 human preimplantation embryos from donor oocytes fertilized in vitro by donor sperm was studied to assess the contribution of lethal chromosome anomalies to the high failure rate of implantation of in vitro fertilized embryos after embryo transfer in infertile women. Evidence was found of nondisjunction, resulting in trisomy, monosomy, and nullosomy; structural abnormalities; haploidy; and triploidy. Despite the lethality of their chromosome complements, these embryos could not be distinguished morphologically from those with normal chromosomes.