PHYSIOLOGICAL RESPONSES OF LIGHT-GROWN CUCUMBER HYPOCOTYLS TO HELMINTHOSPOROL AND ITS DERIVATIVES

Helminthosporol, helminthosporic acid and dihydrohelminthosporicacid stimulated hypocotyl elongation of light-grown cucumberseedlings. The relative activities of the three compounds werein the order H₂-H-acid> H-acid> H-ol. The higher the dosage,the longer the promotion of the hypocotyl elongation lasted.The response of the hypocotyl to H-acid depended on the presenceof cotyledons. As the amount of the cotyledon attached to thehypocotyl was reduced, the response decreased. When IAA-oxidase was estimated as IAA metabolized per dry weightof the hypocotyl, there was an inverse relationship betweenIAAoxidase activity and H-ol-induced elongation of the hypocotyl.However, there was no difference between control and H-ol treatedmaterials when IAA metabolized per plant was compared. It isunlikely that the mechanism of H-ol action is closely relatedto IAA-oxidase activity of the plant. (Received April 5, 1967; )     

Ubiquitous distribution of fluorescent protein in muscles of four species and two subspecies of eel (genus <Emphasis Type="Italic">Anguilla</Emphasis>)

In this study, the localization of fluorescent protein (FP) was characterized in the muscles of four species and two subspecies of eels Anguilla anguilla, A. australis, A. bicolor bicolor (b.), A. bicolor pacifica (p.) and A. mossambica in addition to the previously reported A. japonica. The open reading frame of each eel FP was 417 bp encoding 139 amino acid residues. The deduced amino acid sequences among the four species and two subspecies exhibited 91.4–100% identity, and belonged to the fatty-acid-binding protein (FABP) family. The gene structure of eel FPs in A. japonica, A. anguilla, A. australis, A. bicolor b., A. bicolor p. and A. mossambica have four exons and three introns, and were common to that of FABP family. The apo eel FPs expressed by Escherichia coli with recombinant eel FP genes were analysed for the fluorescent properties in the presence of bilirubin. The excitation and emission spectra of holo eel FPs had the maximum wavelengths of 490–496 and 527–530 nm, respectively. The holo eel FPs indicated that the fluorescent intensities were stronger in A. japonica and A. bicolor than in A. mossambica, A. australis and A. anguilla. The comparison of amino acid sequences revealed two common substitutions in A. mossambica, A. australis and A. anguilla with weak fluorescent intensity.     

WRINKLED BLASTULA OF THE SEA-STAR,ASTERINA MINOR HAYASHI*

In naturally raised embryos of Asterina minor, the changes of internal structure during the wrinkled blastula stage were followed. Eight hours after spawning, blastomeres on the surface of the coeloblastula drop into the blastocoel and eventually form multiple invaginations of the blastodermal layer. Four and a half hours after the commencement of wrinkling, the blastocoel appears to be filled by the developed invaginations. The invaginations then decrease in number and complexity, and 11.5 hr thereafter the wrinkled blastula stage ends, although gastrulation takes place before the complete disappearance of the wrinkle-invaginations.     

Effects of Organic Matter on Solubilities and Crystal Form of Carbonates

The results of a study of the role of organic compounds in theformation of carlxmate crystals in marine biological systemsare reported. In an increasing concentration of certain organiccompounds which complex calcium ions, the proportion of aragonitedecreases and that of calcite increases. In increasing concentrationsof magnesium ions the proportion of aragonite increases andthat of calcite and vaterite decreases. When the influence oforganic compounds is greater or smaller than that of magnesiumions, only calcite or only aragonite is formed, respectively.Organic compounds forming a strong complex with calcium ionscause the formation of magnesium-rich calcite, and with an increasein temperature and the concentration of magnesium ions, themagnesium carbonate content of precipitated magnesian calciteincreases. When the influence of organic compounds is almostequivalent to that of magnesium ions, in increasing or decreasingtemperatures, the proportion of calcite decreases or increases,respectively, and the proportion of aragonite increases or decreases,respectively. The concentration of magnesium ions in the bodyfluids of marine calcareous organisms seems to differ littlefrom that of other organisms, and seems to be similar to thatof sea water. Only the presence of certain organic compoundsbrings about the formation of the carbonate crystals observedin marine biological systems. The very important role of organicmatter in the formation of crystals found in skeletal carbonatesis emphasized.     

Melanoma Antigen and Transforming Gene

We summarize our recent studies on the analysis of melanoma antigen and the melanoma gene recently cloned. The melanoma antigen analyzed by syngeneic monoclonal antibodies is composed of a complex of GM3 ganglioside and protein molecules. The epitope recognized by antimelanoma cytotoxic T lymphocytes seemed to be the combinatorial determinants of GM3 and proteins, whereas the epitope for the suppressor T cells was found to be solely GM3 (NeuAc). The genomic DNA controlling the melanoma antigen was recently isolated and was found to possess transforming activity. The structure of this transforming gene is discussed based on the sequence data of the corresponding cDNA clone.     

Pattern and Time Course of Cleavages in Early Development of the Ovoviviparous Pond Snail, Sinotaia quadratus historica

The pattern and time course of cleavage during early development of the ovoviviparous pond snail, Sinotaia quadratus historica , in in vitro culture were investigated. The fertilized egg, 25–30 μm in diameter, underwent cleavage by repeated constriction and compaction as in blastocyst formation in mammalian embryos. The cleavage was slightly unequal and dextrally spiral, although a slight time lag in cleavages of blastomeres was observed after the 2nd cleavage. A small polar lobe was formed at the 1st cleavage, but not at the 2nd cleavage. Each cleavage proceeded very slowly under the experimental conditions, the 1st, 2nd, 3rd and 4th cleavages taking 22 hr or more, 9 hr and 10 hr, respectively. The cleavage pattern in in vitro cultures observed by light microscopy was confirmed by scanning electron microscopy.     

Studies on nitrogen metabolism in tobacco plants IX. Effect of various compounds on proline biosynthesis in the green leaves

In order to obtain information on the correlation between thebiosynthesis of proline from glutamate and photosynthesis ingreen leaves, the effects of various substances on proline formationfrom ¹⁴C-glutamate have been investigated using tobacco leafdisks in the light. Inhibitors of oxygen evolution in photosynthesis,such as CMU, strongly inhibited the proline formation. The inhibitioncould not be reversed by the addition of reduced NADP, ascorbateplus 2,6-dichlorophenol-indophenol or ATP. Uncouplers or inhibitorsof photophosphorylation such as DNP, arsenate, chlorpromazineand octyl guanidine suppressed the formation of proline fromglutamate. In old leaves, the addition of ADP or ATP markedlyaccelerated proline formation, while neither of these compoundswas effective in young leaves. It was inferred that the reductionof glutamate to ¹-pyrroline-5-carboxylate in green leaves isclosely associated with noncyclic photophosphorylation. (Received August 17, 1967; )     

ACQUISITION OF COMPETENCE FOR CULMINATION DURING FINGER FORMATION IN DICTYOSTELIUM DISCOIDEUM

Finger-like structures of the cellular slime mold, Dictyostelium discoideum , were disrupted with a fine needle and the resulting cell masses were allowed to develop. When complete fingers formed under overhead lighting were disrupted, the cell masses rapidly became transformed into fruiting bodies. Development of similar cell masses from fingers reared in the dark was affected by the lighting conditions after disruption: under overhead lighting the cell masses rapidly culminated; under unilateral lighting, they formed fingers again and then migrating slugs.
In contrast, the cell masses from mounds with tips formed fingers regardless of the lighting conditions.
It is concluded from these findings that the cells become competent for culmination during finger formation under overhead lighting.