EFFECTS OF EXOGENOUS AMINO ACIDS ON THE FLOWER AND FROND PRODUCTION IN DUCKWEED, LEMNA GIBBA G3

1. Twenty usual amino acids examined were shown to be dividedinto two groups with respect to their actions on the flowerformation (A) and frond multiplication (B) in a long-day duckweed,L. gibba G3. Amino acids of the first group (e.g., arginine)inhibited A without preventing B, and those of the second group(e.g., lysine) inhibited both A and B. The inhibition of flowerformation was always the greatest when amino acid was appliedat the induction period. 2. The floral inhibition by arginine applied at the inductionperiod was partially or wholly reversed by the simultaneousaddition of other amino acid (especially lysine) or by one additionallong day. The inhibitions by lysine, however, were not reversedby arginine. 3. It was discussed that the terminal step(s) of photoperiodicinduction process might depend largely on the relative in vivoconcentrations of amino acids. (Received January 28, 1964; )     

INCORPORATION OF AMINO ACIDS INTO SEA URCHIN EGGS STIMULATED INSUFFICIENTLY WITH AN ACTIVATING REAGENT

Investigations were performed on the incorporation of valine-¹⁴C and leucine-³H into sea urchin eggs which were stimulated insufficiently with an activating reagent. Materials used were Pseudocentrotus, Hemicentrotus and Anthocidaris. An insufficient stimulation enhanced the incorporation of amino acids into the eggs, although it provoked no visible cortical changes. The amount of incorporation in this case was 1.6 to 2.7 times as much as that into untreated eggs. In fully activated eggs, the amount of incorporation was more than 4 times that in untreated eggs. The fact that the incorporation of amino acids is increased without accompanying breakdown of the cortical granules indicates that the increase may be linked to an invisible change, probably the fertilizationwave, which is caused by an insufficient stimulation.     

DNA synthesis as related to the reappearance of "light interruption rhythm" in a long-day duckweed, Lemna gibba G3

DNA synthesis in the light perturbation period and its relationto the reappearance, due to light perturbation, of once faded-out"light interruption rhythm" in a long-day duckweed, Lemna gibbaG 3, were studied. After long continuous darkness, the duckweedincorporated ³H-thymidine into both nuclear and satellite DNA_sunder a light condition, but into satellite DNA alone undera dark condition. The number of dividing cells in frond epidermisincreased in proportion to the length of the light perturbationperiod. This increase was inhibited by 5-fluorodeoxyuridine.From these and previous results we conclude that nuclear DNAnewly synthesized in the light is intimately related with thereappearance of the rhythm. (Received June 15, 1970; )     

On the rhythm of sensitivity to light interruption in a long-day duckweed, Lemna gibba G 3

1. The rhythm of sensitivity to light interruption in a long-dayduckweed, Lemna gibba G 3, was examined. The rhythm was circadianand was suggested to be under the control of a physiologicalclock. Light given in the trough between the first and secondpeaks reset the rhythm. Five to 7 cycles of non-circadian photoperiodicregimes given entrained the rhythm to external periodicity,and this entrained rhythm persisted even after the plants weretransferred to continuous darkness. 2. It was suggested that the induction period is not determinedby the physiological clock disclosed here, but by a periodicalternation of dark-sensitivity, or by a periodic change inactivity of SS (system sensitive to IPEF, induction period extendingfactor,) as postulated previously. (Received November 28, 1967; )     

CHLOROPHYLL-SENSITIZED REDUCTION OF PLASTOQUINONE BY ASCORBIC ACID AND QUENCHING OF CHLOROPHYLL-FLUORESCENCE BY PLASTOQUINONE

1. Photochemical reduction of plastoquinone by ascorbic acid inethanol was sensitized with some derivatives of chlorophyll.The order of effectiveness was as follows: allomerized chlorophylla > chlorophyllin a > chlorophyll a > chlorophyll b> pheophytin a.
2. Quenching of the fluorescence of chlorophylla by plastoquinonewas observed. The quenching constant calculatedwas 71 litreper mole.

¹Contribution No. 159 from the Department of Biology, Facultyof Science, Kyushu University. Supported in part by a grant-in-aidfor Fundamental Scientific Research from the Ministry of Education. ²Present address: Biological Laboratory, General Education Department,Kyushu University, Ropponmatsu, Fukuoka. ³Present address: Biological Institute, Daiichi College of PharmaceuticalSciences, Tamagawa-machi, Takamiya, Fukuoka.     

RESTORATION OF PHOTOCHEMICAL ACTIVITY OF ISOLATED CHLOROPLASTS LOST BY ALUMINA TREATMENT

Isolated spinach chloroplasts were ground with alumina in amortar with the addition of 0.2 M KC1 solution. This treatmentresulted in a loss of fifty to ninety per cent of the originalphotochemical activity. A petroleum benzin extract was prepared from the alumina residue.After evaporating the solvent from the extract, the residuewas dissolved in methanol. The methanol was evaporated and theresidue was suspended in distilled water and centrifuged. Thecolorless supernatant solution exhibited a reactivation effectwhen added to the alumina-treated chloroplasts. It was inferred from the difference spectrum obtained betweenits oxidized and reduced forms that the active substance inquestion is functioning as intermediary hydrogen carrier inthe HILL reaction. ¹ Contribution No. 100 from the Department of Biology, Facultyof Science, Kyushu University. (Received July 19, 1960; )     

Content of Adenosine Phosphate Compounds in a Long-Day Duckweed, Lemna gibba G3, under Different Light and Nutritional Conditions

The levels of ATP ADP and AMP as well as the energy charge were examined in the long-day duckweed. Lemna gibba G3, under different light and nutritional conditions. ATP and ADP content, but not AMP, decreased slightly when the plant was cultured with a medium depleted of sucrose or was exposed to continuous darkness. The energy charge was not affected either by changes in the light conditions or by the depletion of sucrose from the medium, although increase of fresh weight changed drastically under these conditions. The levels of ADP and AMP and the value of the energy charge remained nearly constant throughout a 1-day period when the plant was exposed to short-day, continuous light and continuous dark. ATP content decreased gradually during the light period of the short day and thereafter remained constant during the dark period. When the plant was exposed to continuous light. ATP content decreased until the 8th hour after beginning of the continuous light, only to recover rapidly to its original level during the phase coinciding with the preceding dark period of the short day. Under continuous dark conditions the ATP content remained constant throughout the day. It was concluded that the diurnal rhythm of physiological activities previously reported cannot be related to the energy charge.     

Increase in Shedding of Intercellular Adhesion Molecule-1 in Human Malignant Melanoma Cell Lines Treated With Hyperthermia In Vitro

Human malignant melanoma cell lines were found to increase shedding of soluble intercellular adhesion molecule-1 (sICAM-1) into the culture medium when the cells were treated with hyperthermia at 41–43°C for 3–6 hr in vitro. The content of ICAM-1 in the cell lysate was also found to be increased after hyperthermia. The increased rate of ICAM-1 concentration in the cells was at maximum when they were incubated at 41°C for 3 hr. Also, the melanoma cell lines heat-treated at 41°C showed more intense immuno-fluorescence in the ICAM-1 expression on the cell surface. It remains to be investigated further whether the effects of hyperthermia on the ICAM-1 expression in melanoma cells is to augment membrane ICAM-1 expression, which in turn leads to shedding of soluble ICAM-1 or only to acceleration of shedding of sICAM-1 by unknown mechanisms.     

Choanoflagellates (Sarcomastigophora, Protozoa) from the Coastal Waters of Taiwan and Japan. I. Three New Species

Three new acanthoecidaean species collected from the coastal waters of Taiwan and Japan are described: Acanthocorbis camarensis n. sp. resembles Acanthocorbis unguiculata in lorica morphology, but differs in having regularly arranged longitudinal and transverse costae at the anterior lorica chamber, and in lacking a nail at the apical end of anterior spine; Diaphanoeca spiralifurca n. sp. is characterized by the spiral arrangement of the costal strips in the posterior half of the lorica chamber and is closely related to Diaphanoeca grandis; Stephanoeca supracostata n. sp. is closely related to Stephanoeca elegans, but differs in having an additional transverse costa at the anterior lorica chamber.