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  • 1965-1969  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Annulment of Aziridine (Apholate)-Induced Growth Inhibition in the Estuarine Flagellate Tetraselmis subcordiformis by Some Purines and Pyrimidines (1969)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 16 (1969), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. At 850 ppm apholate [2,2,4,4,6,6-hexakis (1-aziridinyl)-2,2,4,4,6,6-hexahydro-1,3,5,2,4,6-triazatriphosphorine], an insect chemosterilant, reduced growth of the marine flagellate Tetraselmis subcordiformis by 50% in 21 days. Mean cell volume more sensitively indicated cellular response at low apholate concentrations than cell number or biomass. Two other aziridinyl chemosterilants tested were 12 and 120 X more toxic than apholate—values agreeing with those reported for some estuarine animals. Apholate acted directly upon the organisms rather than indirectly on the experimental medium since comparatively small molar additions of orotic acid, adenine, guanine, and thymine to apholate-poisoned cultures annulled the growth inhibition. Determining the mode of action of aziridinyl chemosterilants by activity annulment is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1969.tb02254.x
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  • 2
    Electronic Resource
    Electronic Resource
    Photoperiod acclimation and 24-hour variations in the critical thermal maxima of a tropical and a temperate frog (1969)
    Springer
    Oecologia 2 (1969), S. 143-161 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of photoperiod on the upper thermal tolerance of two species of frogs was studied by using the critical thermal maximum (CTM) as the end point. Both species are heliotropic and from temperate climates, but Hyla labialis lives under a near constant tropical photoperiod while Rana pipiens lives under a varying temperatezone photoperiod. The CTM of both species was studied over a 24-hour period to determine if a rhythm of temperature tolerance exists. In all but one of the acclimatization conditions used, the CTM of R. pipiens was higher than that of H. labialis. This agrees with what is known of their thermal ecology. Photoperiod significantly affects the CTM of both species. For Rana pipiens long (LD 16:8) photoperiods result in significantly higher thermal tolerance than short (LD 8:16) or moderate (LD 12:12) photoperiods at both 15 and 25° C. H. labialis shows a different pattern, having highest CTM at 25°C, LD 12:12 and lowest at 15°C, LD 12:12. When acclimated to a short (LD 8:16) photoperiod certain aspects of the frogs' tolerance of high temperatures are altered. At the same acclimatization the CTM of R. pipiens is higher than that of H. labialis, except under a combination short light regime and low temperature, and H. labialis at LD 8:16 shows no thermal acclimation between 15 and 25°C. Significant variation in the CTM over a 24-hour period occurred in H. labialis acclimatized at 25°C, LD 12:12 and R. pipiens at 25°C, LD 8:16 and 15°C, LD 12:12. For both species the 24-hour rhythm of temperature tolerance, when it occurs at LD 12:12, might be of adaptive value. Times of highest thermal tolerance are in the late morning or early afternoon and lowest tolerance is during the dark period. For R. pipiens under the unnatural combination of 25°C, LD 8:16, the pattern is reversed. When all three significant cycles are phase shifted so that the times of highest tolerance coincide, the pattern of the curves is very similar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379157
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    Paper (German National Licenses)
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