Sex chromosome aberrations involving loss and translocation of tumor-inducing loci inXiphophorus

Summary Karyotypic changes involving a deletion and a translocation of certain sex-linked tumor-inducing loci of the platyfish,Platypoecilus (Xiphophorus) maculatus, have been investigated. The effects of these chromosome aberrations on tumor formation and viability of the fish are discussed.Supported by DFG through SFB 103 (Zellenergetik und Zelldifferenzierung, Marburg). We thank Käte Klinke for providing fish stocks.     

Detection and isolation of induced chromosome aberrations in Lepidoptera

Summary An embryo chromosome technique combined with larval testes sampling permits isolation within 1 generation of lepidopteran strains carrying chromosome aberrations     

Adriamycin-induced chromosome damage: elevated frequencies of isochromatid aberrations in G2 and S phases.

Analysis of chromosomes from cells treated with adriamycin during G2 and S phases showed a high frequency of isochromatid-type of breaks, in addition to the expected chromatid breaks. These are interpreted as independent breaks on sister chromatids because of preferential effects of the drug in specific chromosome regions. The break points are likely to be different, but morphologically such breaks would be indistinguishable from isochromatid or chromosome breaks.     

Trisomy of the T6 translocation chromosome in the mouse

Résumé En utilisant le chromosome T6 pour des expériences de transplantations dans la souris, nous avons trouvé des cellules contenant 41 chromosomes et le trisomique pour le chromosome T6.

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This work was supported by The Spastics Society, A.A.M. was in receipt of a grant from the Instituto de Alta Cultura, Portugal. Mr.L. Kelberman processed the photograph.     

Adriamycin-induced chromosome damage: Elevated frequencies of isochromatid aberrations in G2 and S phases

Summary Analysis of chromosomes from cells treated with adriamycin during G₂ and S phases showed a high frequency of isochromatid-type of breaks, in addition to the expected chromatid breaks. These are interpreted as independent breaks on sister chromatids because of preferential effects of the drug in specific chromosome regions. The break points are likely to be different, but morphologically such breaks would be indistinguishable from isochromatid or chromosome breaks.Supported in part by NO1-CM-53773 Division of Cancer Treatment NCI, Bethesda, Maryland, and by Research Grant No. VC-21 from American Cancer Society.     

X-ray induction of chromosome and chromatid aberrations in the same cells after treatment with hydroxyurea

Summary Vicia faba root meristem cells treated for 24 h with 1.25 mM hydroxyurea and then X-irradiated contained a large number of cells with both chromosome and chromatid aberrations. X-irradiation 4 h after release from the hydroxyurea block yielded cells with almost exclusively chromatid aberrations.Acknowledgments. This paper is based on work performed under contract with the U. S. Energy Research and Development Administration at the University of Rochester Biomedical and Environmental Research Project and has been assigned Report No. UR-3490-443. This work was also partially supported by USPHS, grants FD-00694 and GM-22680.     

Induction of chromosome aberrations and chlorophyll mutations in plants by methylisocyanate (MIC) gas

Summary Seeds ofSolanum surattense Burm. f. collected from areas of Bhopal (India) affected by methylisocyanate gas showed chromosome aberrations in root cells, and growth retardation and chlorophyll mutation of seedlings, the frequencies of which varied from one locality to another.     

Cytological evidence for a spontaneous chromosome translocation in the domestic fowl

Résumé La première translocation chromosomique spontanée observée chez le coq domestique implique un échange réciproque entre les chromosomes 2 et 3.

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This investigation was supported in part by a grant from the General Research Fund, Graduate School, Oregon State University. Technical Paper No. 2318, Oregon Agricultural Experiment Station.     

Modifications with chelating agents of the effects of γ-ray fractionated exposures on chromosome aberrations

Résumé Des graines sèches deNigella damascena ont été traitées par les agents de chélation suivants: l'EDTA, le 2, 2-dipyridyl, le Cupferron, la 8-hydroxyquinoléne et le diéthyldithiocarbamate avant d'Être irradiées par les rayons du⁶⁰Co à des doses fractionnées (2×2 krads) séparées par des intervalles de 0 à 5 min. On a constaté une suppression de l'effet de fractionnement et une augmentation absolue des fréquences de tous les types d'aberrations des chromosomes. Par contre, pour des inter-valles courts ou nuls, un effet radioprotecteur est observé par rapport au témoin.

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Aspirant au Fonds National Belge de la Recherche Scientifique     

Sex chromosome inactivation in germ cells: emerging roles of DNA damage response pathways

Sex chromosome inactivation in male germ cells is a paradigm of epigenetic programming during sexual reproduction. Recent progress has revealed the underlying mechanisms of sex chromosome inactivation in male meiosis. The trigger of chromosome-wide silencing is activation of the DNA damage response (DDR) pathway, which is centered on the mediator of DNA damage checkpoint 1 (MDC1), a binding partner of phosphorylated histone H2AX (γH2AX). This DDR pathway shares features with the somatic DDR pathway recognizing DNA replication stress in the S phase. Additionally, it is likely to be distinct from the DDR pathway that recognizes meiosis-specific double-strand breaks. This review article extensively discusses the underlying mechanism of sex chromosome inactivation.     

Sterility and lethality in crosses involving two translocation heterozygotes of the German cockroach,Blattella germanica (L.)

Summary Productivity in crosses involving two independent reciprocal translocations inBlattella germanica are reported. Lethal effects alone could not account for the reductions in hatch since completely unproductive crosses occurred frequently. The latter are attributed to the inability of reduced numbers of viable embryos to force open the egg case. The implications for genetic control of the joint dominant effects from embryonic trapping and translocation semisterility are discussed.Acknowledgment. This research was supported in part by Naval Facilities Engineering Command Contract No. N00025-74-C-0014 and a grant from Johnson's Wax Fund, Inc. The data on the translocation heterozygote and the wild-type matings were obtained byNancy L. Ross, and their use is gratefully acknowledged.     

Sterility and lethality in crosses involving two translocation heterozygotes of the Germay cockroach, Blatella germanica (L.).

Productivity in crosses involving two independent reciprocal translocations in Blattella germanica are reported. Lethal effects alone could not account for the reductions in hatch since completely unproductive crosses occurred frequently. The latter are attributed to the inability of reduced numbers of viable embryos to force open the egg case. The implications for genetic control of the joint dominant effects from embryonic trapping and translocation semisterility are discussed.     

Trial selection of 2 sub-strains of NZB mice based on the level of chromosome aberrations]

Increased chromosomal breakage is observed in NZB mice. Breeding experiments with mice selected according to breakage frequencies provide evidence that the proportion of animals with high and low breakage figures in the first and second generation progeny depends on the phenotype of the parents.     

Chromosome aberrations in in vitro irradiated lymphocytes from human cord blood.

An in vitro dose effect curve of dicentric chromosome aberrations in human cord blood lymphocytes has been obtained for 250-kV X-rays. This is compared with a curve prepared in an identical manner using blood from adults. The comparison shows a marginally higher dicentric yield in blood of newborns at doses above about 250 rads.     

Pentobarbital sodium and chromosome abnormalities in rabbit blastocysts.

Female rabbits were injected with pentobarbital sodium at 1/4 h or 6 h post coitum. A slight delay in oocyte maturation was evident in animals killed at 17 h pc, however, zygote development appeared normal by 24 h pc. At 6 days pc, a greater frequency of chromosomally abnormal blastocysts was found in animals injected with pentobarbital than in control rabbits.     

Inhibition by verapamil of ionophore-mediated calcium translocation.

Verapamil and other organic calcium-antagonists inhibit the A23187-mediated translocation of calcium from an aqueous into an organic phase.     

2/8 translocation in a Japanese Burkitt's lymphoma.

A new translocation between chromosomes 2 and 8, t(2p-; 8q+), was found in fresh lymphoma cells from a Japanese patient with Epstein-Barr virus-carrying Burkitt's lymphoma, and in a lymphoma cell line derived from this patient. There was no 14q+ translocation, as has been previously described in African and North American Burkitt's lymphomas.     

Loss of antibody production accompanied by chromosome loss in a cloned hybrid line secreting antibodies to sheep red blood cells

Summary Somatic cell hybrids between Sp2/O-Ag14 mouse myeloma cells and lymphocytes derived from BALB/c mice hyperimmunized with sheep red blood cells (SRBC) were produced. One hybrid producing IgG₁ antibody to SRBC was selected, cloned twice and subsequently transferred to BALB/c mice. After a number of transfers it was found that the antibody titer in ascitec fluid gradually decreased. Cytogenetic analysis revealed gradual chromosome loss in the hybrid clone, which produced progressively less antibody.     

Loss of antibody production accompanied by chromosome loss in a cloned hybrid line secreting antibodies to sheep red blood cells

Somatic cell hybrids between Sp2/O-Ag14 mouse myeloma cells and lymphocytes derived from BALB/c mice hyperimmunized with sheep red blood cells (SRBC) were produced. One hybrid producing IgG1 antibody to SRBC was selected, cloned twice and subsequently transferred to BALB/c mice. After a number of transfers it was found that the antibody titer in ascites fluid gradually decreased. Cytogenetic analysis revealed gradual chromosome loss in the hybrid clone, which produced progressively less antibody.