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At least 19 recordsLinked to original sources
PubMed1976

Negative silver staining in A-T and satellite DNA-rich regions of human chromosomes.

Human metaphase chromosomes were stained with silver following a pretreatment with a heated alkaline solution. The most conspicuous feature of the stained metaphases was the omission of silver staining in the secondary constrictions of chromosomes 1,9 and 16, and on the distal Yq. Our evidence indicates that the negative silver binding is due to the preferential removal or alteration of non-histone proteins associated with these regions. The cytochemical significance of these findings is discussed.

Adenine Nucleotides↗
PubMed1978

Base ratio, DNA content, and quinacrine-brightness of human chromosomes.

Human chromosomes were labeled with base-specific radioactive DNA precursors and examined autoradiographically to measure their DNA content and base ratio (percentage A-T base pairs). The requirement that incorporation of labeled bases be uniform during DNA synthesis was met by the use of inhibitors of de novo synthesis of DNA precursors. The genome was subdivided into 75 segments based on quinacrine banding, and the base ratio of each was calculated by a method that corrects for bias due to the scatter of grains about their source. Estimates of base ratio are shown to be sufficiently precise to detect variability among chromosomes and among segments within a chromosome. Analysis of these data and of measurements of the quinacrine fluorescence intensity of segments leads to the following conclusions. Base ratio is positively correlated with brightness, as predicted from independent in vitro studies. Larger chromosomes tend to have higher base ratios and to be brighter than smaller ones. The best prediction of the brightness of a segment must take into account not only its base ratio but also its DNA content. To explain these results, we suggest an evolutionary model in which chromosomes containing repeated sequences of A-T-rich DNA tend to grow by means of unequal sister chromatid and meiotic exchanges.

Base Sequence↗
PubMed1979

Necessity for two human chromosomes for human chorionic gonadotropin production in human-mouse hybrids.

Through a series of human-mouse hybrids we have identified that two human chromosomes, 10 and 18, must be present for production of the pregnancy protein hormone human chorionic gonadotropin (hCG). Human choriocarcinoma cells producing hCG were hybridized to mouse cells. From 49 independent clones three hybrid clones continued to produce whole hCG. Chromosomal analysis was done on the 3 producer clones and 5 nonproducer clones. The additional 41 nonproducer clones were genetically characterized by isozymes. Only when chromosomes 10 and 18 were present in a clone would the whole hCG molecule be produced. Clones with only 10 or only 18 did not produce hormone. Nine subclones of a producer clone confirmed this observation. Three subclones retaining both 10 and 18 continued to produce hCG. This study demonstrated the need to use cellular chromosome data and population enzyme data to identify two chromosomes necessary for hCG production in heterogeneous human-mouse hybrids.

Animals↗
PubMed1976

Cytochemical study of pseudoisocyanine stained human chromosomes.

Human meiotic and mitotic chromosomes were studied with N-N' diethyl pseudoisocyanine stain. Following methylation and oxydation, the staining allowed microscopic observation of slides with both monochromatic light and fluorescence. In addition, stained preparations can be permanently conserved. Preceeded by diverse methods of chromosome denaturation or 5-BUDR incorporation, PIC lends itself to a large number of banding techniques. Cytochemical study of stained chromosomes demonstrated a certain PIC affinity for DNA although tests performed do not exclude the possibility of PIC reaction with certain proteins.

Chromatin↗
PubMed1978

Transfer of human chromosomes via human minisegregant cells into mouse cells and the quantitation of the expression of hypoxanthine phosphoribosyltransferase in the hybrids.

The behaviour of human cells arrested in mitosis can be severely perturbed so as to generate numerous small minisegregants containing very few chromosomes. These cells can be separated according to size and DNA content and fused with intact cells. In this paper we describe the production and some properties of proliferating cell hybrids generated by fusion of human minisegregant cells derived from a HeLa strain with mouse A9 cells deficient in hypoxanthine phosphoribosyltransferase (HPRT, EC 2.4.2.8). The hybrids were shown to contain up to 10 human chromosomes including a single X. Independently derived hybrid clones were quantitatively characterized and compared with the parental phenotypes with respect to HPRT. Human isozymes of each of the 3 enzymes HPRT, glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and phosphoglycerate kinase (EC 2,7.2.3) were found. Tests to evaluate both structure and function of HPRT were utilized. The specific activity of HPRT of more than 10 hybrids tested was approximately 10% that of the HeLa parent. Structural characterization of HPRT from hybrid cells as evidenced by heat inactivation and electrophoretic mobility results in a 'human-like' phenotype. Functional characterization of parental HPRT results in kinetic constants for cofactor and substrate which do not permit distinction of human and of human and mouse enzymes; HPRT from the minisegregant hybrids had normal kinetic constants. The reduced specific activity of HPRT in the hybrids is discussed in terms of the inability of the mouse environment to regulate the full expression of the human structural gene.

Animals↗
PubMed1978

Altered pattern of replication of human chromosomes in a human fibroblast-mouse cell hybrid.

The pattern of terminal replication of the human chromosomes in a clone of hybrids between diploid human fibroblasts and mouse cells was analyzed by autoradiography. An average of 10 human chromosomes was present in the hybrid cells. Several of these chromosomes were found to terminate replication in a different order from the same chromosomes in the parental human fibroblasts. Chromosomes 4 and 5 completed replication later in the hybrid than in the fibroblasts (relative to the other human chromosomes). In contrast, chromosomes 7, 12, and 15 completed replication earlier in the hybrid than in the fibroblasts. These results suggest that the sequence of terminal chromosome replication in human fibroblasts is not irreversibly programmed into each chromosome.

Animals↗
PubMed1978

Chromosomal localization of human beta globin gene on human chromosome 11 in somatic cell hybrids.

We have successfully used a DNA.cDNA molecular hybridization assay to directly determine the presence or absence of human beta globin gene sequences in 20 human-mouse somatic cell hybrids, each of which contained a different subset of human chromosomes. The assay is specific for the individual human globin genes and will detect the presence of a globin gene if the relevant chromosome is present in only 10% of the cells of a hybrid population. The content of human chromosomes in each hybrid clone was characterized by Giemsa 11 staining, Giemsa trypsin-Hoechst 33258 staining, and by the use of 22 independent isozyme markers for 17 different human chromosomes. All human chromosomes were present in one or more cell lines devoid of the human beta globin gene except for 6, 8, 9, 11, and 13. Among these latter chromosomes, only chromosome 11 was present in the six hybrid clones that contained the human beta globin gene. In fact, chromosome 11 was the only human chromosome that was present in all of the six hybrid clones found to be positive for the human beta globin gene. Two sister clones, 157-BNPT-1 and 157-BNPT-4, had similar subsets of human chromosomes except that 11 was present only in 157-BNPT-4. 157-BNPT-4 contained the human beta globin gene while 157-BNPT-1 did not. DNA from three hybrid lines was also annealed to purified human gamma globin cDNA; two lines positive for human beta globin gene sequences also contained human gamma globin gene sequences while one line was negative for both beta and gamma gene sequences. On the basis of these results, the human beta and gamma globin genes have been assigned to human chromosome 11.

Chromosomes, Human, 6-12 and X↗
PubMed1978

Homologous genes for enolase, phosphogluconate dehydrogenase, phosphoglucomutase, and adenylate kinase are syntenic on mouse chromosome 4 and human chromosome 1p.

It is possible to generate interspecific somatic cell hybrids that preferentially segregate mouse chromosomes, thus making possible mapping of mouse genes. Therefore, comparison of the linkage relationships of homologous genes in man and mouse is now possible. Chinese hamster x mouse somatic cell hybrids segregating mouse chromosomes were tested for the expression of mouse enolase (ENO-1; EC 4.2.1.11, McKusick no. 17245), 6-phosphogluconate dehydrogenase [PGD; EC 1.1.1.44, McKusick no. 17220], phosphoglucomutase-2 (PGM-2; EC 2.7.5.1, McKusick no. 17190), and adenylate kinase-2 (AK-2; EC 2.7.4.3, McKusick no. 10302). In man, genes coding for the homologous forms of these enzymes have been assigned to the short arm of human chromosome 1. Analysis of 41 primary, independent, hybrid clones indicated that, in the mouse, ENO-1 and AK-2 are syntenic with PGD and PGM-2 and therefore can be assigned to mouse chromosome 4. In contrast, they were asyntenic with 21 other enzymes including mouse dipeptidase-1 (DIP-1, human PEP-C; EC 3.4.11.(*), McKusick no. 17000) assigned to human chromosome arm 1q and mouse chromosome 1. Karyologic analysis confirmed this assignment. These data demonstrate that a large autosomal region (21 map units in the mouse and 51 map units in the human male) has been conserved in the evolution of mouse chromosome 4 and the short arm of human chromosome 1. Identification of such conserved regions will contribute to our understanding of the evolution of the mammalian genome and could suggest gene location by homology mapping.

Adenylate Kinase↗
PubMed1977

Complement-mediated antiserum cytotoxic reactions to human chromosome 7 coded antigen(s): immunoselection of rearranged human chromosome 7 in human-mouse somatic cell hybrids.

Immunoselection via complement-dependent lysis of human-mouse somatic cell hybrids containing chromosome 7, with antisera reactive to cell surface antigen(s) coded for by chromosome 7, has resulted in growth of somatic cell hybrids containing rearranged human chromosome 7s. Investigation of these hybrids has localized the gene(s) coding for the relevant cell surface antigen(s) to the short arm of human chromosome 7. The simian virus 40 integration site and the gene coding for human beta-glucuronidase appear to be localized to the long arm of chromosome 7 in this hybrid clone.

Animals↗
PubMed1976

Method for the determination of mean densitometric profiles of chromosomes: application to human chromosomes stained by quinacrine mustard, ethidium bromide or by the Feulgen reaction.

When comparing the densitometric profiles of corresponding chromosomes registered from different metaphases or homologous pairs, one is always faced with the variability of their length and overall height. This makes difficult the quantitative comparison of a given chromosome treated by various staining procedures.--A simple and rapid method has been developed for normalizing the densitometric profiles and averaging them in order to obtain a "mean density pattern" of each chromosome. The analysis involves: photographic images, digitalization of the densitometric profiles and processing of the data by a mini-computer.--The method, based on a linear relationship between the area of the densitometric profiles and their length, has been applied to five human chromosomes (1, 2, 6, 12 and 16) stained by ethidium bromide, quinacrine mustard (with or without acidic hydrolysis), pararosaniline and bisaminophenyl-oxadiazole (Feulgen reaction).

Bromides↗
PubMed1978

Epstein-Barr virus and human chromosomes: close association of the resident viral genome and the expression of the virus-determined nuclear antigen (EBNA) with the presence of chromosome 14 in human-mouse hybrid cells.

Fourteen hybrid clones derived from the fused cultures of human lymphoblastoid FV5 cells and 5-bromodeoxyuridine-resistant mouse fibroblastic MCB2 cells grown in hypoxanthine/aminopterin/thymidine selective medium were examined for the presence of Epstein-Barr virus (EBV) DNA, the expression of the virus-determined nuclear antigen (EBNA), and the presence of human chromosomes, in the course of serial passage in vitro. Among the hybrid clones tested, 3 were positive for EBV DNA and EBNA, whereas the remaining 11 were totally negative. The chromosome investigations showed that human chromosome 14 was consistently involved in all three EBV genome-positive and EBNA-positive hybrid clones, but not in any negative clones. In 10 subclones isolated from 1 of the 3 positive clones, all of which contained only chromosome 14 of the human chromosomes, a concordant segregation of EBNA, EBA DNA, and chromosome 14 was evident. These findings suggest that the resident EBV genome is closely associated with chromosome 14 and the presence of this particular chromosome alone is sufficient for the maintenance and the expression of EBV genetic information in human lymphoblastoid cells.

Antigens, Viral↗
PubMed1978

Liquid nitrogen storage and human chromosome composition of human-mouse hybrid cells.

The human chromosome complement of eight human-mouse hybrid cell strains was studied with fluorescent banding before and after rejuvenation of these cells from liquid nitrogen storage. The karyotype remained essentially stable in several cell strains, while in others both human and mouse chromosomes were lost. A third group demonstrated loss of only human chromosomes. The loss of particular human chromosomes after the rejuvenation process was shown to be statistically significant in four of the eight hybrid cell strains. These preliminary results suggest that karyotypic constancy cannot be assumed in human-mouse hybrid cells subjected to rejuvenation from liquid nitrogen storage.

Animals↗
PubMed1977

Regional localization of a beta-galactosidase locus on human chromosome 22.

Human white blood cells with an X/22 translocation [46, XX, t(X;22)(q23;q13)] were fused with Chinese hamster cells. The isolated hybrids were analyzed for human chromosomes and 21 enzyme markers. An electrophoretic technique for studying the beta-galactosidase isoenzymes in man-Chinese hamster hybrid cells was developed. Immunological studies showed that the beta-galactosidase marker studied in these hybrids did contain immunological determinants of human origin. Furthermore the results provided evidence that a locus for beta-galactosidase is situated on chromosome 22 distal to the breakpoint in q13.

Antigen-Antibody Reactions↗
PubMed1977

[Immunocytochemical labeling of human chromosomes by antibodies from human autoimmune serum].

Mitotic human chromosomes are successively irradiated by ultraviolet, incubated with serum from a patient showing systemic lupus erythematosus (S.L.E.), and antihuman Sheep serum conjugated with peroxidase. After revelation by diaminobenzidine (DAB) banding patterns are pointed out. The chromosome labelling is discussed in comparison with results obtained in other immunocytochemical experiments.

Antibodies↗
PubMed1979

Localisation of the G gamma-, A gamma-, delta- and beta-globin genes on the short arm of human chromosome 11.

Human-mouse somatic cell hybrids have proved invaluable in assigning human genes to their respective human chromosomes. To date, the success of this approach has depended on identifying human proteins which are synthesised in hybrid cells containing a small number of human chromosomes. Consequently, chromosome assignment has been limited mainly to human proteins which are expressed in man-mouse somatic cell hybrids and for which a suitable assay, usually electrophoretic or immunological, exists to distinguish between the human and murine homologous proteins. This technique is therefore unsuitable for the assignment of those human genes which are expressed only in differential cells and not in hybrid cells. Here, we describe how nucleic acid hybridisation and restriction endonuclease mapping of DNA can be combined to test for the presence of human structural gene sequences within hybrid cell DNA. This method can be used to assign any purified human DNA sequence to a human chromosome, and does not require the DNA sequence to be expressed in man-mouse hybrid cells.

Animals↗
PubMed1979

G-banding patterns of high-resolution human chromosomes 6--22, X, and Y.

A precise schematic representation of the number, height, position, and staining intensity of the Giemsa bands of late prophase, prometaphase, early metaphase, and mid-metaphase chromosomes 6--22, X, and Y is presented. Late prophase chromosomes were found to have 2--2 1/2 times the length and 3--3 1/2 times the number of bands previously observed in mid-metaphase, whereas prometaphases and early metaphases were intermediate in length and number of bands. In this work, the maximum number of bands observed per haploid set in late prophase was 1353, while more than 350 were generally found in mid-metaphase.

Azure Stains↗
PubMed1977

[Quantitative assessment of human chromosomal polymorphism with regard to paracentromeric heterochromatin].

The measurement of C-segment length in chromosomes 1, 9 and 16 of 7 individuals was carried out. The regression analysis was employed to study a change of the C-segment sizes in the process of mitotic chromosome condensation. Typical values of C-segment length for chromosomes 1, 9 and 16 are about 1.4, 1.1 and 0.8mu respectively. Among 7 individuals there was no two which had identical size of C-segments for all three chromosomes studied. In six individuals heteromorphysm of C-segments was revealed. It was found that visually detected heteromorphysm may be expressed quantitatively as ratio length of C-segments in homologous chromosomes.

Cells, Cultured↗