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  • Articles: DFG German National Licenses  (4)
  • Gynogenesis  (2)
  • Physical Chemistry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Sex determination in the genus Oreochromis (1991)
    Springer
    Theoretical and applied genetics 82 (1991), S. 144-152 
    Details
    ISSN: 1432-2242
    Keywords: Sex determination ; Oreochromis niloticus ; Gynogenesis ; Sex reversal ; Triploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Established techniques of genetic manipulation were used to elucidate sex-determining mechanisms in the commercially important tilapia, Oreochromis niloticus. Analysis of sex ratios from single-pair matings of normal broodstock showed these to be heterogeneous, with an asymmetrical frequency distribution. Data were homogeneous, with the exclusion of a number of broods with sex ratios not significantly different from 3∶1 (male: female), and further progeny testing revealed atypical female heterogamety in the parents of these broods. Analysis of sex ratios from complete diallele-type crosses using five males and five females demonstrated no association between male parent, female parent and progeny sex ratio. Sex ratios of gynogens (0∶1) and triploids (1∶1), and from progeny testing of sex-reversed males (0∶1) and sex-reversed females (3∶1), provide evidence for female homogamety in this species. Progeny testing of male gynogens derived from sex-reversed females demonstrated recombination between the centromere and the sex-determining locus (68.9%). Novel YY “supermales” were shown to be viable and produced all-male offspring. It was concluded that this species exhibits monofactorial, genotypic sex determination with male heterogamety. However, rare autosomal or environmental sex-modifying factors may account for occasional deviations from expected sex ratios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226205
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Sex determination in the genus Oreochromis (1991)
    Springer
    Theoretical and applied genetics 82 (1991), S. 153-160 
    Details
    ISSN: 1432-2242
    Keywords: Sex determination ; Oreochromis aureus ; Gynogenesis ; Sex reversal ; Hybridisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sex ratios from 62 single-pair matings of normal broodstock O. aureus were highly heterogeneous with an overall deficit of males (41.4%). Peaks in the sex ratio frequency distribution occurred at 1∶1, 3∶5 and 1∶3 (male∶female). Hybridisation of O. aureus with O. mossambicus, O. spilums and O. niloticus produced highly variable sex ratios, suggesting a complexity of hybrid sex determination. Few valid inferences could be made regarding intraspecific sex determination from these hybrid data. Sex ratios from progeny testing of sex-reversed males (1∶3) and most sex-reversed females (1∶0) provide evidence for female heterogamety in O. aureus. Several aberrant ratios observed suggest Mendelian inheritance of an autosomal recessive gene (F,f), epistatic to the major sex-determining gene (W,Z). Sex ratios of triploids and gynogens support the hypothesis of recombination between the centromere and the major sex-determining locus. Progeny testing of a female mitogyne demonstrated the viability of a novel WW “superfemale”, which gave only female offspring. Not all data could be explained by a two-factor model of sex determination. Further exceptional sex ratios may be accounted for by rare autosomal or environmental sex-modifying factors. It is concluded that O. aureus has a multifactorial mechanism of sex determination with the underlying primary mechanism of female heterogamety.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226206
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the Cl + CO reaction in air (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 28 (1996), S. 763-771 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Long-path FTIR spectroscopy was used to study the kinetics and mechanism of the reaction of Cl atoms with CO in air. The relative rate constants at 298 K and 760 torr for the forward direction of the reaction of Cl with 13CO and the reaction of Cl13CO with O2 were k1 = (3.4 ± 0.8) × 10-14 cm3 molecule-1 s-1 and k2 = (4.3 ± 3.2) × 10-13 cm3 molecule-1 s-1, respectively (all uncertainty limits are 2σ). The rate constant for the net loss of 13CO due to reaction with Cl in 1 atm of air at 298 K was kCl+COobs = (3.0 ± 0.6) × 10-14 cm3 molecule-1 s-1. The only observed carbon-containing product of the Cl + 12CO reaction was 12CO2, with a yield of 109 ± 18%. Our results are in good agreement with extrapolations from previous studies. The reaction mechanism and the implications for laboratory studies and tropospheric chemistry are discussed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.7
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Rate constant for the reaction of Cl with CHCl3 (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 28 (1996), S. 399-404 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constant for the reaction of Cl with CHCl3 was measured relative to the Cl reaction with CH4 and CH3Cl using long path FTIR. The measured rate constant at 298 K and 1 atm total pressure was (1.21 ± 0.13) × 10-13 cm3 molecule -1s-1 (2σ) about 60% larger than the currently recommended value (although within the large error bars). The implications of the Cl + CHCl3 reaction for relative rate studies chloromethane reactivity, and tropospheric chemistry are discussed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.1
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    Paper (German National Licenses)
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