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  • 1
    Electronic Resource
    Electronic Resource
    Gene action in fish of tetraploid origin. I. Cellular and biochemical parameters in cyprinid fish (1975)
    Springer
    Biochemical genetics 13 (1975), S. 45-51 
    Details
    ISSN: 1573-4927
    Keywords: gene action ; polyploidy ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In phylogenetically diploid and tetraploid Cyprinid fish species, erythrocyte volumes, protein contents, and mean activities of the enzymes LDH, 6PGD, and PGI per cell per active gene locus decline with increasing DNA contents. These findings are assumed to reflect an evolutionary tendency of polyploids to regulate their genic activity down to the level of the diploids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486005
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  • 2
    Electronic Resource
    Electronic Resource
    Hidden breaks in ribosomal RNA of phylogenetically tetraploid fish and their possible role in the diploidization process (1983)
    Springer
    Biochemical genetics 21 (1983), S. 819-841 
    Details
    ISSN: 1573-4927
    Keywords: evolution ; polyploidy ; ribosomal RNA ; protein synthesis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Hidden breaks occur in the ribosomal RNA of tetraploid Cyprinid fish such that the large ribosomal RNA (28 S) yields upon denaturation two RNA fragments of 8.7×105 and 5.0×105 daltons, whereas the small rRNA (18 S) yields fragments of 3.2×105 to 5.0×104 daltons. In tetraploid Cyprinids hidden breaks occur only in the rRNA of somatic tissue and not in oocytes and sperm cells. Hidden breaks can be detected only slightly in diploid Cyprinid species. Ribosomes purified from somatic tissue of tetraploid Cyprinids show a reduced efficiency in protein synthesis in vitro. The ribosomal proteins from diploid and tetraploid Cyprinid fish show considerable electrophoretic differences. This is discussed in light of a possible functional role of hidden breaks in rRNA in the process of diploidization of gene expression in tetraploid Cyprinid species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00498929
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  • 3
    Electronic Resource
    Electronic Resource
    Subzonal microinjection of mouse spermatozoa: Insufficient sperm motility might induce phagocytosis (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 28 (1991), S. 47-54 
    Details
    ISSN: 1040-452X
    Keywords: Spermatozoa ; Slight motility ; Microinjection ; In vitro fertilization ; Zona pellucida ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Acrosome-reacted CB6F1 mouse spermatozoa with slight flagellar motility were microinjected under the zona pellucida of CB6F1 mouse oocytes. Electron microscopy revealed the presence of swollen and decondensed sperm heads in the oocyte cytoplasm. Sixty-one percent of the microinjected oocytes reached a morphologically apparent two-cell stage, but chromosomal analysis demonstrated only haploid chromosomal complements in all cases. The exposure of microinjected oocytes to suspensions of spermatozoa of mice homozygous for a 2,4 reciprocal translocation resulted in normal fertilization and embryonic development with a maternally as well as a paternally derived haploid genome. Identical results were obtained with oocytes microinjected with medium and subjected to in vitro fertilization thereafter. Thus it can be suggested that the microinjected spermatozoa with insufficient flagellar motility are incorporated into the oocyte cytoplasm by phagocytosis. These spermatozoa do not induce a polyspermy block but induce the oocyte to parthenogenetic development.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080280108
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