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  • 1
    ISSN: 1432-2048
    Keywords: 1-Aminocyclopropane-1-carboxylic acid ; 1-Amino-2-ethyl-cyclopropane-1-carboxylic acid ; 1-Butene ; Ethylene formation ; Pisum (ethylene synthesis)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The characteristics of the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene by pea (Pisum sativum L.) epicotyls and by pea epicotyl enzyme are compared. Of the four stereoisomers of 1-amino-2-ethylcyclopropane-1-carboxylic acid (AEC), only (1R,2S)-AEC is preferentially converted to 1-butene in pea epicotyls. This conversion is inhibited by ACC, indicating that butene production from (1R,2S)-AEC and ethylene production from ACC are catalyzed by the same enzyme. Furthermore, pea epicotyls efficiently convert ACC to ethylene with a low K m (66 μM) for ACC and do not convert 4-methylthio-2-oxo-butanoic acid (KMB) to ethylene, thus demonstrating high specificity for its substrate. In contrast, the reported pea epicotyl enzyme which catalyzes the conversion of ACC to ethylene had a high K m (389 mM) for ACC and readily converted KMB to ethylene. We show, moreover, that the pea enzyme catalyzes the conversion of AEC isomers to butene without stereodiscrimination. Because of its lack of stereospecificity, its low affinity for ACC and its utilization of KMB as a substrate, we conclude that the reported pea enzyme system is not related to the in-vivo ethylene-forming enzyme.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 199-210 
    ISSN: 0192-253X
    Keywords: aging ; Drosophila ; behavior ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The question as to the role that genes play in determining life-span is essentially unresolved. Although it is well documented that genotype influences longevity, this is no way demonstrates that life-span is genetically determined. In the present study we examine five temperature-sensitive mutations for their effect on the aging process. At the permissive temperature (22°C ), the longevity of each mutant strain is comparable to that of wild type. However, at the restrictive temperature (29°C ) the life-span of these mutants is severely curtailed. Using behavior loss as a landmark of adult physiological age, we examined each of these strains for its pattern of behavior loss relative to longevity, and compared each to a wild-type strain. In four of the mutations the pattern of behavior loss relative to longevity was severely altered at one or both temperatures. However, one strain, adl-16tsl displayed a pattern of behavior loss that was indistinguishable from wild type at both 22°C and 29°C. At 29°C not only was the longevity decreased, the pattern of behavior loss was also compressed into a shorter time period. The compression of the pattern of behavior loss was proportional to the reduction in life-span. Thus it appears that this mutation, adl-16tsl, may accelerate the normal aging process when placed at 29°C. The potential utility of these types of mutants for studying the aging process is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 77-97 
    ISSN: 0192-253X
    Keywords: behavioral mutation ; Drosophila ; flightlessness ; temperature sensitive ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mutations in 13 genes with temperature-sensitive (ts), flightless phenotypes have been examined. All hop and fly well when raised at the permissive temperature, but fly poorly, or not at all, when raised at the restrictive temperature. The mutations were divided into three groups on the basis of their temperature-sensitive periods (TSPs) for flightlessness. The TSPs for mutations at five loci, fli-C1, D1, E1, I1, and shak A1, in the first group are confined to 24 to 48 hr interval during early pupal development. Mutations in the second group, including eag101, fli B1, and futs1 have continuous TSPs 3 to 4 days in length, extending from late larval through the early pupal stages. The flight TSPs for mutations in the third class, including fli J1, fli K2, flrd H3, and flrd N1, are almost continuous, and span most of the larval and pupal periods. Many of the mutations have pleiotropic phenotypes, including semilethality and lethality, and wing posture and cuticle abnormalities, with discernible TSPs. One of the more intriguing pleiotropic phenotypes is the ts optomotor response exhibited by fli J2, the TSP for which extends from late larval through late pupal stages.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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