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  • 1
    Electronic Resource
    Electronic Resource
    Two New Basic Chromosome Numbers in the Genus Pennisetum (1956)
    [s.l.] : Nature Publishing Group
    Nature 178 (1956), S. 1241-1242 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In the somatic complement of P. ramosum one pair of satellited chromosomes was seen and the centromeres in all the chromosomes were either median or sub-median (Fig. 1). At diakinesis and metaphase I of meiosis in microsporocytes, there were five bivalents (Fig. 2). One plant was heterozygous for ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/1781241a0
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Sex chromosomes, micronuclei and aging in women (1994)
    Springer
    Chromosoma 103 (1994), S. 186-192 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Several studies on aneuploidy and aging have shown a significant increase in the loss of chromosomes in both males and females with age. Others have observed a significant increase in micronucleus formation in lymphocytes with age. The objectives of this investigation were to determine the relationship between sex chromosome loss and increased micronucleus frequencies with age, to establish sex chromosome loss frequencies unbiased by cellular survival factors or slide preparation, and to determine the effect of smoking on sex chromosome loss. Blood samples were obtained from 8 newborn females and 38 adult females ranging in age from 19 to 77. Isolated lymphocytes were cultured according to standard techniques and blocked with cytochalasin B. Two thousand binucleated cells per donor were scored using a modified micronucleus assay to determine the kinetochore status of each micronucleus. Slides were then hybridized with a 2.0 kb centromeric X chromosome-specific probe labeled with biotinylated dUTP, and detected with fluorescein-conjugated avidin. All micronucleated cells were relocated and their X chromosome status was determined. We found the X chromosome to be present in 72.2% of the micronuclei scored; additionally our results show a significant increase with age in the number of micronuclei containing an X chromosome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368011
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Activation status of the X chromosome in human micronucleated lymphocytes (1996)
    Springer
    Human genetics 〈Berlin〉 97 (1996), S. 471-475 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The frequency of X chromosome aneuploidy in human female peripheral blood lymphocytes has been reported by several investigators to be significantly higher than expected based upon chance alone. Studies in our laboratory showed that 72% of the micronuclei in the peripheral blood of human females contained the X chromosome. Such a high frequency of X chromosome loss suggests that some unique mechanism may be responsible for this phenomenon. The present study was carried out to test the hypothesis that the lost or micronucleated chromsome is the inactive and not the active X. Blood samples were obtained from two unrelated females, 36 and 33 years of age, each with a different X; 9 reciprocal translocation. In each, the normal X chromosome is inactive and the translocated X is active. Isolated lymphocytes were cultured according to standard techniques and blocked with cytochalasin B. Using a modified micronucleus assay, we scored 10,000 binucleated cells from the 36 year old, while 9,500 binucleated cells were scored from the 33 year old. The slides were first labeled and the kinetochore status of each micronucleus was determined. This was followed by simultaneous hybridization with a 2.0 kilobase centromeric X chromosome-specific probe and a chromosome 9 specific whole chromosome painting probe. All micronucleated cells were relocated and scored for their probe status. A total of 217 micronuclei were scored from the two subjects, of which 96 (44.2%) contained the X chromosome. Of these 96 micronuclei, 80 (83.3%) contained the inactive X, based on the absence of chromosome 9 material in the micronucleus. These results support our hypothesis that the inactive X chromosome is preferentially included in the micronuclei, and suggest that the X chromosome hypoploidy observed at metaphase in aging women is a related phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267069
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Y Chromosome aneuploidy, micronuclei, kinetochores and aging in men (1995)
    Springer
    Chromosoma 103 (1995), S. 725-731 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. This investigation was conducted to determine the relationship between Y chromosome loss and increased micronucleus formation with age. We also investigated the status of kinetochore proteins in the micronuclei. Umbilical cord blood samples were obtained from 18 newborn males, and peripheral blood was obtained from 35 adult males ranging in age from 22 to 79 years. Isolated lymphocytes from all 53 donors were cultured and blocked with cytochalasin B. Two thousand binucleate cells per donor were scored using a modified micronucleus assay to determine the kinetochore status of each micronucleus. This assay showed 23.8% of the micronuclei to be kinetochore-positive, while 76.2% of the micronuclei were kinetochore-negative. Cells were then hybridized with a 3.56-kb biotinylated Y chromosome-specific probe. All micronucleate cells were relocated and their Y probe status was determined. A significant increase in Y-bearing micronuclei with age was observed. Metaphase cells from the same samples were analyzed for the presence or absence of Y chromosome. The relationship between Y chromosome-positive micronuclei and Y chromosome-negative metaphase cells was highly significant, suggesting that Y chromosome-deficient metaphase cells result from cells which had previously lost a Y chromosome due to micronucleation. The cause of micronucleus formation from a lagging Y chromosome appears probably to be either a faulty or a diminished amount of kinetochore protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344234
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Sex chromosomes, micronuclei and aging in women (1994)
    Springer
    Chromosoma 103 (1994), S. 186-192 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Several studies on aneuploidy and aging have shown a significant increase in the loss of chromosomes in both males and females with age. Others have observed a significant increase in micronucleus formation in lymphocytes with age. The objectives of this investigation were to determine the relationship between sex chromosome loss and increased micronucleus frequencies with age, to establish sex chromosome loss frequencies unbiased by cellular survival factors or slide preparation, and to determine the effect of smoking on sex chromosome loss. Blood samples were obtained from 8 newborn females and 38 adult females ranging in age from 19 to 77. Isolated lymphocytes were cultured according to standard techniques and blocked with cytochalasin B. Two thousand binucleated cells per donor were scored using a modified micronucleus assay to determine the kinetochore status of each micronucleus. Slides were then hybridized with a 2.0 kb centromeric X chromosome-specific probe labeled with biotinylated dUTP, and detected with fluorescein-conjugated avidin. All micronucleated cells were relocated and their X chromosome status was determined. We found the X chromosome to be present in 72.2% of the micronuclei scored; additionally our results show a significant increase with age in the number of micronuclei containing an X chromosome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368011
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Y Chromosome aneuploidy, micronuclei, kinetochores and aging in men (1995)
    Springer
    Chromosoma 103 (1995), S. 725-731 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This investigation was conducted to determine the relationship between Y chromosome loss and increased micronucleus formation with age. We also investigated the status of kinetochore proteins in the micronuclei. Umbilical cord blood samples were obtained from 18 newborn males, and peripheral blood was obtained from 35 adult males ranging in age from 22 to 79 years. Isolated lymphocytes from all 53 donors were cultured and blocked with cytochalasin B. Two thousand binucleate cells per donor were scored using a modified micronucleus assay to determine the kinetochore status of each micronucleus. This assay showed 23.8% of the micronuclei to be kinetochore-positive, while 76.2% of the micronuclei were kinetochore-negative. Cells were then hybridized with a 3.56-kb biotinylated Y chromosome-specific probe. All micronucleate cells were relocated and their Y probe status was determined. A significant mcrease in Y-bearing micronuclei with age was observed. Metaphase cells from the same samples were analyzed for the presence or absence of Y chromosome. The relationship between Y chromosome-positive micronuclei and Y chromosome-negative metaphase cells was highly significant, suggesting that Y chromosome-deficient metaphase cells result from cells which had previously lost a Y chromosome due to micronucleation. The cause of micronucleus formation from a lagging Y chromosome appears probably to be either a faulty or a diminished amount of kinetochore protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344234
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Activation status of the X chromosome in human micronucleated lymphocytes (1996)
    Springer
    Human genetics 〈Berlin〉 97 (1996), S. 471-475 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The frequency of X chromosome aneuploidy in human female peripheral blood lymphocytes has been reported by several investigators to be significantly higher than expected based upon chance alone. Studies in our laboratory showed that 72% of the micronuclei in the peripheral blood of human females contained the X chromosome. Such a high frequency of X chromosome loss suggests that some unique mechanism may be responsible for this phenomenon. The present study was carried out to test the hypothesis that the lost or micronucleated chromsome is the inactive and not the active X. Blood samples were obtained from two unrelated females, 36 and 33 years of age, each with a different X; 9 reciprocal translocation. In each, the normal X chromosome is inactive and the translocated X is active. Isolated lymphocytes were cultured according to standard techniques and blocked with cytochalasin B. Using a modified micronucleus assay, we scored 10,000 binucleated cells from the 36 year old, while 9,500 binucleated cells were scored from the 33 year old. The slides were first labeled and the kinetochore status of each micronucleus was determined. This was followed by simultaneous hybridization with a 2.0 kilobase centromeric X chromosome-specific probe and a chromosome 9 specific whole chromosome painting probe. All micronucleated cells were relocated and scored for their probe status. A total of 217 micronuclei were scored from the two subjects, of which 96 (44.2%) contained the X chromosome. Of these 96 micronuclei, 80 (83.3%) contained the inactive X, based on the absence of chromosome 9 material in the micronucleus. These results support our hypothesis that the inactive X chromosome is preferentially included in the micronuclei, and suggest that the X chromosome hypoploidy observed at metaphase in aging women is a related phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004390050075
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Cytological evidence for DNA chain elongation after UV irradiation in the S phase (1981)
    Springer
    Biochemical genetics 19 (1981), S. 199-210 
    Details
    ISSN: 1573-4927
    Keywords: UV light ; DNA repair ; DNA chain elongation ; Xeroderma pigmentosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Human cells irradiated with UV light synthesize lower molecular weight DNA than unirradiated cells. This reduction in molecular weight is greater in xeroderma pigmentosum (XP) cells than in normal cells. The molecular weight of DNA is further reduced by the addition of caffeine to XP cells. By several hours after irradiation, DNA fragments are barely detectable. Cells from excision-proficient and excision-deficient XP patients were studied autoradiographically to produce cytological evidence of DNA chain elongation. Replicate cultures with and without caffeine were synchronized and irradiated with UV light during the S phase. Caffeine was removed in G2, and the cells were labeled with 3H-thymidine. Results showed significantly increased labeling during G2 of excision-deficient XP cells. Labeling was dependent on both time of irradiation and presence of caffeine. The XP variant cells had no increase in labeling for any irradiation time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00504267
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    Paper (German National Licenses)
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