Showing papers on "Chromosome 21 published in 1976"

Antibodies to a cell-surface component coded by human chromosome 21 inhibit action of interferon.

Abstract: ANTICELLULAR sera able to block specific cell responses are important in the study of surface receptors. Particularly useful are antibodies against the human cellular antigens coded for by a specific chromosome, which can be prepared by immunising mice with mouse–human somatic cell hybrids containing defined human chromosomes1. We have applied this method to the study of the mechanism by which the presence of human chromosome 21 renders such hybrids sensitive to human interferon2. Interaction of an interferon with sensitive cells induces intracellular biochemical changes, including the formation of an inhibitor of protein synthesis, making the cell unable to support virus replication3,4. We have obtained antibodies to hybrid cells containing human chromosome 21, and these inhibit the response of live human cells to interferon. Our experiments indicate that chromosome 21 codes for a cell-surface component required as a specific receptor for human interferon.

Localization of the Gene AVG for the Antiviral Expression of Immune and Classical Interferon to the Distal Portion of the Long Arm of Chromosome 21

Abstract: The responses of normal fibroblasts and of fibroblasts trisomic and monosomic for chromosome 21 to exogenously administered virus-induced (classical) and phytohemagglutinin-induced (immune) human interferon were determined. The virus-induced interferon was obtained from leukocytes treated with Sendai virus and from neonatal foreskin fibroblasts treated with Newcastle disease virus. With both classical and immune interferons, the mean response of the trisomic cell lines was three times that of the normal cells, whereas that of the monosomic lines was half or less that of the normal cells, Furthermore, a line trisomic for only the distal half of the long arm of chromosome 21 (q21 leads to qter) also demonstrated increased sensitivity to virus- and phytohemagglutinin-induced interferons, a fact that indicated that the gene responsible for the antiviral effect of interferon, AVG, is located on this part of chromosome 21. Responses to the two categories of interferon (virus-induced and phytohemagglutinin-induced) of individual cell lines of different degrees of sensitivity were strongly correlated (r=0.79). It is concluded, therefore, that despite their physical and antigenic differences, the antiviral expressions of both classical and immune interferons are ultimately mediated by the same genetic locus, AVG.

Human Y-chromosome-specific reiterated DNA.

Abstract: Radiolabeled reiterated DNA specific for the human Y chromosome has been obtained by extensive reassociations between [3H]DNA prepared from men and excess DNA from women. These highly purifed labeled sequences reassociate only with DNA from individuals with a Y chromosome. The percentage of Y-chromosome-specific DNA isolated from individuals with differing numbers of Y chromosomes is a function of the number of chromosomes present. The purifed Y-chromosome-specific sequences may represent between 7 and 11 percent of the human Y chromosome.

Localisation of the human ABO: Np-1: AK-1 linkage group by regional assignment of AK-1 to 9q34.

Abstract: Quantitative red cell adenylate kinase (AK-1) assay has been used in 8 patients with partial duplication or deletion of chromosome 9 in an attempt to find the precise intrachromosomal location of the structural gene locus. All regions of chromosome 9 are represented in abnormal dosage in at least one patient. A 43% increase in AK-1 activity was found to be associated with duplication of the terminal band of the long arm of chromosome 9. Duplication of all other parts of chromosome 9 were associated with normal enzyme activity. These findings not only confirm the assignment of the AK-1 locus to chromosome 9 made previously in somatic cell hybrids, but suggest a more precise assignment to region 9q33→qter. This places the ABO: Np-1: AK-1 linkage group at the distal end of the long arm of chromosome 9.

Chromosome 21 and the Cell Growth Inhibitory Effect of Human Interferon Preparations

Abstract: INTERFERONS constitute a class of biologically active glycoproteins1–3 which induce a spectrum of physiological changes in living cells, leading to the inhibition of virus replication4, of cell growth in vitro—both normal and tumour cells5,8—and of tumour growth in vivo9–15. The mechanism(s) underlying these effects is unknown. Gressor et al. have suggested that the same molecule in an interferon preparation is responsible for both the antiviral (AV) and cell growth inhibitory (CGI) effect5. This suggestion was based on the observation of a consistent and direct correlation between the two effects in an interferon preparation purified more than a millionfold. Gressor also reported that tumour cells treated with interferon had a lower capacity to form colonies in Agarose and were less tumorigenic when innoculated15, suggesting that the antitumour effect of interferon depended, in part, on the inhibition of tumour cell multiplication which can be demonstrated in vivo. I describe here a genetic approach to ascertain whether the CGI effect of human interferon preparations is mediated by chromosome 21-directed gene(s), known to govern the AV action of interferon16–19. Such an approach, should provide further insight into whether the different effects of interferon are governed by a cluster of genes on chromosome 21 or whether a single genetic locus on chromosome 21 codes for the pleiotropic effects of interferon.

Distribution of spontaneous chromosome breaks in human chromosomes.

Abstract: Localization of chromosome breaks in human chromosomes was analyzed in 264 peripheral lymphocyte cultures. Three hundred and sixty-nine chromosome breaks could be exactly localized to a chromosome band or region of the Paris Conference nomenclature. The distribution of breaks in the chromosome regions was found to be nonrandom. Chromosome 3 alone had 23% of the breaks and region 3p2 had 13% of the total breaks. Some other chromosome regions, such as 5p1, 9q1, 14q2, and 16q2 also displayed clustering of breaks. Sex chromosomes had less breaks than expected. Spontaneous chromosome breaks were almost exclusively located in the lightly stained G bands.

Origin of the extra chromosome no. 21 in Down's syndrome.

Abstract: Eighteen of 38 examined families with children with Down's syndrome showed polymorphisms of chromosome 21 elucidating the origin of the extra chromosome 21. Maternal origin was found in 10 cases and paternal origin in 8 cases. In both sexes errors occurred both in the first and in the second meiotic division.

Partial monosomy and partial trisomy 18 in two offspring of carrier of pericentric inversion of chromosome 18.

Abstract: A pericentric inversion of chromosome 18 is described in the mother of a patient with clinical diagnosis of 18q--syndrome. The propositus' chromosome complement includes the recombinant 18 with deficiency of the distal one-third of the long arm and duplication of the terminal segment of the short arm. The propositus' sister carrier the recombinant 18 with a duplication of the distal one-third of the long arm and a deficiency of the terminal segment of the short arm. The relative length of the inverted segment represents about 60% of the total chromosome 18 length. The probability of recombinant formation following the occurrence of a chiasma within the inverted segment is predicted to be high.

[Partial trisomy 21 (21q21 - 21q22.2)].

Abstract: An abnormal chromosome 21 is reported in a child with a phenotype strongly reminiscent of trisomy 21 syndrome. It is shown to result from duplication of the segment 21q21 leads to 21q22.2. Comparison of the phenotype with that of other partial and total trisomics shows that the characteristic features of the trisomy 21 syndrome (mongolism), the mental retardation in particular - is due to trisomy 21q22.2 and perhaps 21q22.2.

A child with presumptive monosomy 21 (45,XY,–21) in a family in which some members are Gq–

Abstract: Presumptive monosomy for chromosome 21 was found in a male child with multiple malformations and severe psychomotor retardation. Chromosome analyses of cells from blood and skin samples were performed

High Rates of Occurrence of Spontaneous Chromosome Aberrations in DROSOPHILA MELANOGASTER.

Abstract: Spontaneous mutations were accumulated for 40 generations in 140 unrelated second chromosomes with the standard gene arrangement. These were extracted from the same population by using the marked inversion technique, and the following findings were obtained: (1) In 42 out of the 140 chromosome lines, chromosome aberrations were detected by examining the salivary gland chromosomes: 40 paracentric and 15 pericentric inversions, 2 reciprocal translocations between the second and the third chromosomes, and 6 transpositions. (2) In 63 out of the 90 originally lethal-free lines, recessive lethal mutations occurred. (3) There were only 3 lines that acquired chromosome aberrations (inversions) with no lethal effects in the homozygous condition. (4) In a comparison of these results with those of the (CH), (PQ), and (RT) chromosomes in which no chromosome aberrations occurred after accumulating mutations for 22058 chromosome·generations (Yamaguchi and Mukai 1974), it was concluded that some of these 140 chromosomes carried a kind of mutator. (5) The frequency of mutator-carrying chromosome lines was estimated to be 0.66 on the basis of the distribution of the break-points on the chromosome lines and the frequency of lines that acquired neither recessive lethal mutations nor chromosome aberrations. Thus, the average number of breaks per mutator-carrying chromosome was estimated to be about 0.19/generation. On the basis of these estimates, the nature of the mutator factor was discussed.

Spontaneous chromosome mutation and screening of mutator factors in Drosophila melanogaster

Abstract: 1 (1) The marked inversion technique was used, and 38 major autosome sets of Drosophila melanogaster were extracted from populations of Jugoslavia, Taiwan and Japan Spontaneous mutations were allowed to accumulate on the major chromosomes for 25 generations Then the second chromosomes were tested to determine whether or not they were associated with such known mutator factors as the male crossing-over factor, SD, and the extrachromosomal element delta Chromosome mutations were examined by salivary gland chromosome analysis, and viability mutations were done by the marked autosomal translocation method 2 (2) In 8 out of 38 major autosome lines, 5 inversions occurred in the second chromosomes, 4 inversions in the third chromosomes, and 1 reciprocal translocation between the second and the third chromosomes Chromosome mutation rates were, therefore, 00063 per second chromosome per generation and 00053 per third chromosome per generation Since there was no significant difference in the rates, chromosome mutations seem to be occurring approximately equally in both major autosomes 3 (3) Lethal mutation rates were estimated to be 00097 per major autosome per generation 4 (4) Twenty-four second chromosome lines out of 37 demonstrated male crossing-over among the cinnabar and brown interval; the average frequencies were 00031 for all lines and 00034 when non-recombination lines were excluded 5 (5) One second chromosome exhibited delta retaining ability (ID), but no second chromosome carried SD

Inclusion of satellites in an 18/21 translocation chromosome shown by ammonical-silver staining (sat-banding) in case of partial trisomy 18.

Abstract: A male infant with a partial trisomy 18 and a 46,XY, --21, t(18;21)(18qter replaced by 18q12::21 p13 replaced by 21 qter) chromosome complement is described. The translocation chromosome is of special interest because it includes the satellites of chromosome 21. This was shown by differential satellite staining with the ammoniacal-silver technique.

Fusion of two apparently intact human X chromosomes.

Abstract: Cytological studies have been presented from a 15-year-old girl with short stature and failure of puberty. Buccal mucosa preparations revealed X-chromatin mass approximately double in size of that of a normal female. Leukocyte metaphases suggested a two cell line composition of the patient. One population of cells conformed with 45,X chromosome distribution. The chromosome complement of her other cell line had a modal number of 46. In this cell line a "C" chromosome was replaced by an exceptionally large submetacentric chromosome. This abnormal element exhibited late DNA replicating pattern. G-banding study revealed that the abnormal chromosome was produced as a result of fusion involving telomeric ends of long arms of 2 intact X chromosomes. This translocation X was bearing 2 C-banded areas; one around the centromere and the other at the distal end of the long arm. The distal C-band area did not show any evidence for centromeric function. It appears that a centromere becomes latent in the presence of another centromere in a translocation bearing 2 total chromosomes. Such a change of state in the additional centromere is vital for the stability of the translocation chromosome.

Chromosome 21 does not code for an interferon receptor.

Abstract: IT is well established that human cells which are trisomic for chromosome 21 are more sensitive to the antiviral activity of interferon than normal diploid cells1–6. If chromosome 21 codes for an interferon receptor site localised at the cell surface, as suggested4,5, one might expect cellular binding of interferon to increase in the order mono-somic 21 cells, disomic 21 cells and trisomic 21 cells. This did not prove to be the case. All cell types bound interferon equally well. In view of these and previously5 reported data, it is postulated that chromosome 21, if it codes for a protein involved in the interferon response of the cells, does not specify the receptor molecule per se but another molecule that is involved in the processing of the antiviral message from the cell surface to the interior of the cell.

A polymorphic structural rearrangement in the chromosomes of two populations of orangutan.

Abstract: A rearranged chromosome 9 was found in 12 of 23 specimens of orangutan, 4 of Bornean and 8 of Sumatran origin. Nine animals were heterozygous, and 3 were homozygous carriers for the variant chromosome

[Partial trisomy of chromosome 21 by maternal translocation t(15;21) (q26.2; q21)].

Abstract: A balanced reciprocal translocation, t(15;21) (q262;q21) was observed in the mother and maternal grandfather of two patients. The propositus, who received the abnormal chromosome 15 from his mother, is trisomic for the distal part of chromosome 21, and his phenotype is that of classical trisomy 21. His sister, who is trisomic for the proximal part of 21q, is slightly retarded but developmentally normal otherwise.

rDNA and acrocentric chromosomes in man. I. rDNA levels in a subject carrier of a 8p/13p balanced translocation and in his unbalanced son.

Abstract: A malformed female infant was found to have a 46,XX complement with a chromosome 8 shorter than normal with a secondary constriction and satellites on the short arm. Chromosome studies on the clinically normal father showed a balanced translocation between chromosome 8 and 13, i.e., 46,XY,t(8;13) (p21 p12). The proposita, carrier of the unbalanced form of the translocation, resulted partially monosomic for short arm of chromosome 8 (8p-) and partially trisomic for short arm of chromosome 13. The levels of DNA complementary to rRNA (normal in the father who had 10 NOR and increased in the proposita who had 11 NOR) confirmed our interpretation of the rearrangement.

21 ring chromosome in a girl with stigmata of Down's and G deletion I syndromes.

Abstract: An 11-year-old girl with severe psychomotor retardation and other congenital anomalies characteristic of Down's and G deletion I syndromes, was confirmed to be a chromosome 21 ring carrier by R- and G-banding techniques. The dynamics of the ring evolution resulting in a population of complex unstable rings, as in our index case, and the effects of the consequent ring mosaicism are briefly discussed.

Philadelphia Chromosome with T(6;22) (P25;q12)

Abstract: The introduction of chromosome analysis in various blood disorders has proved the high specificity of the Philadelphia chromosome — a G22 member with deleted long arms — in the diagnosis of chronic

Asynchronous DNA replication and asymmetrical chromosome loss in Chinese hamster-mouse somatic cell hybrids.

Abstract: A number of parameters were measured in a series of 12 hybrid cell clones from Chinese hamster and mouse cells to test the hypothesis that asymmetrical chromosome loss may result from asynchrony in the replication of the two parental sets of chromosomes. All clones tended to lose telocentric (mouse) chromosomes with culture time, irrespective of the starting ratio of parental chromosomes, and in all clones, biarmed (hamster) chromosomes appeared to complete DNA replication slightly earlier than telocentrics. However, no quantitative correlation could be established between the degree of asynchrony in chromosome DNA replication and the extent of chromosome loss. It appeared that telocentric chromosomes were lost more readily from those clones which started with a high hamster-to-mouse chromosome ratio.

A case of ring chromosome.

Abstract: A girl with a G22 ring chromosome is described. There are few physical abnormalities, performance quotient is in the low normal range but verbal skills are much retarded.

The trisomy 18 syndrome with an E/G translocation

Abstract: An infant with a typical Edwards syndrome and a modal chromosome number of 46 is reported. In all cells analyzed one chromosome G was missing and an additional chromosome similar to a pair No. 16 was present. The phenotype of the child indicates that the extra element is a translocation between G and 18 chromosomes as in one case described previously.

Partial deletion of the short arm of the chromosome 9

Abstract: Monosomy 9p is reported in a boy with trigonocephaly and advanced bone age.

Genetic analysis of a transposable suppressor gene in Saccharomyces cerevisiae.

Abstract: We have demonstrated in Saccharomyces cerevisiae the transposition of a gene coding for an efficient ochre (UAA) suppressor from a centromere-linked site on chromosome III to two new sites in the yeast genome. One site is on chromosome VI, very close to, if not allelic with, SUP11, one of eight genes coding for a tyrosine-inserting suppressor. The second site is on chromosome III, unlinked to the centromere and distal to the mating type locus. This site is very close to those mapped for the recessive lethal amber suppressors, SUP-RL1 and SUP61.