Environment Control in Biology
Online ISSN : 2185-1018
Print ISSN : 0582-4087
ISSN-L : 0582-4087
Volume 19, Issue 2
Displaying 1-4 of 4 articles from this issue
  • Adaptive Significance of Phototaxis in Newly Hatched Larvae
    Isamu SHIMIZU
    1981 Volume 19 Issue 2 Pages 41-49
    Published: June 30, 1981
    Released on J-STAGE: June 22, 2010
    JOURNAL FREE ACCESS
    To determine the adaptive significance of phototactic behavior in newly hatched silkworm larvae, some experiments were designed and performed.
    1) Before being fed mulberry leaves, the larvae showed active klinophototaxis (Fig. 2) .
    2) The phototactic response-intensity curves showed a threshold for the response between 10-3 and 10-2lux after dark-adaptation, and between 10-2and 10-1lux after light-adaptation (Fig. 3) .
    3) The shape of the light source toward the newly hatched larvae oriented themselves affected the phototactic response (Fig.4) .
    4) In the visual region, the newly hatched larvae showed a maximum phototactic response to green irradiation (557 nm), but scarcely responded to blue and red irradiations (Fig. 5) . Larvae also responded to an ultraviolet irradiation of 357 nm. The light transmitted through the mulberry leaf had a remark-able attraction for the newly hatched larvae (Fig.6) .
    5) The tactic activity by which the newly hatched larvae oriented and moved toward the mulberry leaves was lower in complete darkness than under light. Blind larvae, which had lost their vision and phototaxis due to a defect in vitamin A showed a reduced tactic response to mulberry leaf, irrespective of darkness or of light conditions (Figs.7 and 8) .
    6) These results show that the larval phototaxis mediated by vision is important for finding and ar-riving at the green leaves of the host plant (mulberry) as is chemotaxis (Fig.9) .
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  • Tsuyoshi MATSUI, Hiromi EGUCHI, Keiichiro MORI
    1981 Volume 19 Issue 2 Pages 51-57
    Published: June 30, 1981
    Released on J-STAGE: June 22, 2010
    JOURNAL FREE ACCESS
    A radiative cooling system was developed to control dew and frost formations and to examine the effect of the radiative cooling on the leaf temperature. The growth chamber was provided with a box which was constructed by using heat insulating materials to minimize the disturbances and to regulate the air current. A cooling coil (cooling surface of 300 cm2) was equipped at the bottom of the box and manipulated by a refrigerator of 1, 430 kcal hour-1, and a concave mirror was attached to the ceiling of the box to facilitate the reflection of the radiation from the leaf to the cooling coil. The moisture in air was supplied by flowing the controlled air (0.2 m3min-1) into the box. The distribution of dew point temperatures was almost uniform horizontally even under vertically slight conversion (downward velocity of 1.3 cm sec-1) of the air. The leaf temperature became about 1.0°C lower than the ambient air temperature under the radiative cooling. The dew and the frost were clearly observed on the leaf after the time when the leaf temperature had become lower than the dew point temperature. The dew increased in size in course of time, and the frost varied in shape and in size with the temperatures. Thus, artificial formations of the dew and the frost were made possible by the radiative cooling system developed in this experiment.
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  • Kenji OMASA, Yasushi HASHIMOTO, Ichiro AIGA
    1981 Volume 19 Issue 2 Pages 59-67
    Published: June 30, 1981
    Released on J-STAGE: June 22, 2010
    JOURNAL FREE ACCESS
    We have reported on a method for evaluating the distributions of stomatal resistance to water vapor diffusion and SO2or NO2sorption on a leaf, using a thermal infrared image instrumentation system. In the present paper, we examined quantitatively the relation-ships between the acute effects, such as stomatal response and visible injury, of SO2or NO2on a leaf and gas sorption, using the image instrumentation method. The results obtained were as follows.
    1) There was a tendency for stomata to close during SO2or NO2exposure. However, the behavior varied randomly at different sites on a leaf. The differences in stomatal response at local sites were not dependent on those in integrated SO2or NO2sorption for 60 minutes exposure. These results suggest that there are differences in the stomatal sensitivity to SO2or NO2at local sites on a leaf.
    2) There was a tendency for visible injury to occur at sites where the integrated SO2or NO2sorption was over a threshold value. Injured leaves were generally separated into two areas, a healthy area and an injured one. It was seen that the characteristic visible injuries were caused by differences in boundary layer and stomatal resistances at local sites governing the gas sorption.
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  • III. Difference in Leaf Temperature between Adaxial and Abaxial Surfaces in Cotyledon of Cucurbita maxima Duch
    Tsuyoshi MATSUI, Hiromi EGUCHI, Masahiro KOUTAKI
    1981 Volume 19 Issue 2 Pages 69-72
    Published: June 30, 1981
    Released on J-STAGE: June 22, 2010
    JOURNAL FREE ACCESS
    The dynamics of the temperatures of adaxial and abaxial surfaces of a cotyledon were analyzed under controlled environments with reference to a physiological difference between those surfaces. The difference in temperature between those surfaces was clearly observed at the time of their lowest temperatures under the radiation; the temperature of the abaxial surface was 0.5°C lower than that of the adaxial one, when the cotyledon was radiated both on adaxial surface, and even on abaxial surface. In the case that the stomata closed by the treatment with ABA, there was scarcely any appreciable difference between the temperatures of both surfaces. In microscopical examination, the ratio of stomatal frequency on the adaxial surface to that on the abaxial one was found to be about 80% in the cotyledon used. From these results, it could be conceivable that the stomatal transpiration on the abaxial surface is higher than that on the adaxial one, and this function results in decrease in temperature on the abaxial surface under the radiation.
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