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; )     

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.     

Effect of inhibitors of nucleic acid and protein synthesis on the reappearance of "light interruption rhythm" in a long-day duckweed, Lemna gibba G 3

Effects of several inhibitors of DNA, RNA and protein synthesison the reappearance of a once faded-out light interruption rhythmin a long-day duckweed, Lemna gibba G 3, were studied. The reappearancewas not affected by inhibitors of RNA and protein synthesis;i.e., 2-thiouracil, 8-azaguanine, ethionine and chloramphenicol,but was suppressed by inhibitors of DNA synthesis; i. e., 5-fluorodeoxyuridine,5-fluorouracil and mitomycin C only when these were appliedduring the light period for perturbation. We concluded that synthesis of a new DNA species during thelight period was required for the recurrence of this rhythm. (Received September 25, 1968; )     

SPERMIOGENESIS IN BARNACLES WITH SPECIAL REFERENCE TO ORGANIZATION OF THE ACCESSORY BODY*

Ultrastructural changes during spermiogenesis in the barnacles, Balanus amphitrite albicostatus, Balanus tintinnabulum rosa, Balanus trigonus and Tetraclita squamosa japonica, and organization of the sperm with special reference to the accessory body were studied. The Golgi complex organizes both the acrosome and the accessory body at different stages during spermiogenesis; the former is formed at the mid-spermatid stage and the latter is formed at the late spermatid stage. The arrangement of the components in the mature filiform sperm is quite unique, with the acrosome, the basal body just behind the acrosome, the axial filament parallel to a long nucleus, and a slender long mitochondrion behind the nucleus. The sperm in the anterior and posterior half of the ejaculatory duct differ from each other in form in that the sperm in the anterior duct are not equipped with the accessory body and the sperm in the posterior duct are. The accessory body can be artificially broken down by some treatments (1 M urea, alkaline sea water: pH 9.0-9.7, low ionic concentration of sea water). The loss of the accessory body from the sperm is assumed to be related to the ferti-lizability of the sperm.     

THE RHYTHMICAL CHANGE IN SENSITIVITY OF A LONG-DAY DUCKWEED, LEMNA GIBBA G3, TO DARK-BREAK

1. Effect of varied lengths of darkness given before continuousillumination, and that of dark-break of continuous light asa function of the time of its application, on the flower formationin a long-day duckweed, Lemna gibba G3, were studied. The results obtained suggested a rhythmic change in sensitivityto darkness, i.e., a cycle of 36 hr-period consisting of 12hr of sensitivity and the following 24 hr of insensitivity.The inhibition by darkness (12–36 hr) given before thestart of, or by dark-break (12, 24 hr) inserted in, the inductionperiod involved an extension of the induction period, but nota slow-down of the rate of flower formation. The dark-breakgiven after the induction period, however, suppressed the rateof flower production in proportion to the length of the darkness. 2. The inhibition of flowering by darkness given in the darksensitivephase was cancelled by a relatively brief light period insertedin the darkness. 3. Relation between the rhythm and the length of induction periodwas discussed. (Received August 13, 1965; )