Morphological Characterization of First Instar Larvae of Asian Horseshoe Crabs and their Hybrids*

The morphological characters of first instar larvae of three Asian horseshoe crabs and their hybrids were examined. For this purpose, the length of six parts on the larvae, the pattern of pigmentation, the structure of the margin of the opisthosoma, and the distribution and shape of spines on the extracardiac region of the prosoma were recorded. In general, the phenotypes of the hybrids were intermediate between those of the parents, suggesting that both male and female genomes contribute to development of the hybrids. However, there were some exceptional characters and phenotypic variations. Some characters were inherited from only one parent. This was suggested to imply that if the maternal species did not have the gene regulating expression of a given paternal character, the paternal gene did not express this character.     

Auxin-induced growth of tuber tissue of Jerusalem artichoke VI. Biochemical changes in chromatin during aging and cell expansion

Possible mechanisms by which auxin and gibberellic acid stimulateRNA synthesis were examined, using slices excised from cold-storedtubers of Jerusalem artichoke. The ratio of DNA in nucleo non-histone to the total DNA in chromatinincreased during the aging process. On the other hand, cellexpansion did not involve this kind of change in chromosomalcomponents. Gibberellic acid and 2,4-D showed no significanteffects on the ratio of DNA in nucleo non-histone to the totalDNA in chromatin. Melting points of DNA and nucleohistone did not differ significantlyaccording to their sources, i.e. unaged, aged and growing tissues. (Received November 13, 1970; )     

Metabolism of glucose in relation to the lipid synthesis in the fruit of Persea americana MILL.

Studies on the lipogenesis in the fruit of avocado were undertakento elucidate the metabolism of glucose relative to the lipidsynthesis as an important process. The relative participationof the pentose phosphate pathway was determined. Approximately30% of the glucose metabolized by catabolic pathways was directlyoxidized to release carbon dioxide and to provide about 50%of the total reducing power responsible for the fatty acid synthesis.Whereas carbon number 1 of glucose was incorporated into theglyceryl moiety, carbon number 6 was incorporated into the fattyacyl moiety of glycerolipids in the tissue slices of the developingfruit. From the experiments in vitro, it may be concluded that,besides glucose-6-phosphate dehydrogenase, malic enzyme andisocitrate dehydrogenase participate in the provision of NADPH₂for the fatty acid synthesis in the mesocarp of avocado fruit. ¹Present address: Department of Botany, Faculty of Agriculture,Hokkaido University, Sapporo 060, Japan (Received January 13, 1969; )     

Stimulation of gibberellin-induced germination in lettuce seeds by cyclic 3',5'-adenosine monophosphate

Cyclic 3',5'-adenosine monophosphate and sodium dibutyryl cyclic3',5'-adenosine monophosphate had no effect on dark-germinationof light-sensitive lettuce {Lacluca sativa L., var. Grand Rapids)seeds when given alone. Cyclic 3',5'-adenosine monophosphate,however, synergistically enhanced the 3 µ 10^–5 Mgibberellic acid-induced germination, but showed no such effecton kinetin-stimulated germination. 5'-AMP, in contrast to cyclic3',5'-adenosine monophosphate, had no effect on gibberellicacidinduced germination. (Received August 8, 1971; )     

Role of photoperiod and temperature in seasonal morph determination of the butterfly Eurema hecabe

ABSTRACT. Environmental cues affecting seasonal morph determination of the pierid butterfly Eurema hecabe L. were examined in laboratory experiments and in the field. A sexual difference exists in the photoperiodic response for seasonal morph determination: in short days at 25C the proportion of the autumn morph is higher in females than in males, and as the rearing temperature is decreased the proportion of autumn morphs increases in both sexes. A 5C drop in temperature during the final larval stadium induces 100% autumn morph production in short-day animals. This increase in autumn morph production induced by temperature decrease explains the seasonal morph change of this butterfly occurring in early autumn in the field. The role of this sex-linked photoperiodic response is discussed as a seasonal strategy of reproduction.     

Glutaraldehyde as an effective stabilizer for the isolation of intact chloroplasts

A good yield of structurally intact chloroplasts isolated fromwheat for electron microscope examination was obtained withthe application of glutaraldehyde fixative as a primary maceratingand isolating medium. It was not always necessary to take specialprecautions in tonicity or to hesitate to store the chloroplastsuspension for delayed electron microscopic preparation. Somenoticeable features found in senescent chloroplasts are described. ¹This work is a part of a project aided by a fellowship grantedto the author from the National Research Council of Canada,1963–1965. ²Permanent address: Department of Biology, Faculty of Science,Niigata University, Niigata, Japan. (Received January 23, 1969; )     

PHENOL METABOLISM IN RELATION TO DISEASE RESISTANCE OF POTATO TUBER: I. ACTIVITIES OF PHENOL OXIDASE AND SOME ENZYMES RELATED TO GLYCOLYSIS AS AFFECTED BY CHLOROGENIC ACID TREATMENT

Disks of potato tubers, 0.5 mm in thickness, were treated witha mixture of chlorogenic and ascorbic acids. When they werenot washed with water after the treatment, they became brown.Activities of phenol oxidase and glutathione reductase and o-diphenolcontent increased more rapidly in these disks than in untreatedcontrol. Activity of the pentose phosphate pathway was increasedby the treatment, while that of EMDEN-MEYERHOF-PARNAS pathwaywas greatly inhibited. In washed unbrowned disks, the changesin those activities were negligible or smaller than those inthe browned disks, although chlorogenic acid which had permeatedremained in the tissue after washing. Oxidized products of chlorogenicacid and possibly of ascorbic acid may be a trigger in thisalteration in metabolism. Malonate and streptomycin also induced similar effects on thephenol metabolism in the tuber disks. Increases in o-diphenolcontents and in phenol oxidase activity were caused probablyby preferential inhibition of EMDEN-MEYERHOF-PARNAS pathwayand tricarboxylic acid cycle. These results are discussed inrelation to the mechanism of disease resistance of potato tuber. (Received May 6, 1966; )     

EFFECT OF AUXIN ON β-1, 3-GLUCANASE ACTIVITY IN AVENA COLEOPTILE

When the homogenate of Avena coleoptile segments was fractionated, the specific activity of β-1, 3-glucanase was remarkably associated with the cell wall, partly to be released from it by a detergent. The cell wall-bound glucanase activity was increased by the treatment of coleoptile segments with auxin. Only in 10 min of the treatment the glucanase activity and the incorporation of labeled leucine into the proteins were found to be increased in the fraction to be liberated by detergent from the cell wall fraction. These effects of auxin were inhibited by 10 μg/ml cycloheximide.     

Auxin-induced cell expansion in relation to cell wall extensibility

Decapitation of 30 mm oat coleoptiles, which are commonly usedfor growth tests, resulted in a decrease in their elastic extensibility(DE) but not in their plastic extensibility (DP). By auxin treatmentunder osmotic stress, old coleoptile (45 mm) cells showed noincrease in subsequent expansion in water, whereas RNA synthesisin these cells was stimulated just as in young ones. Auxin increasedthe DE of young coleoptile cell walls but not that of old ones.Significant increase of DE occurred in only 10 min, and themaximum level of DE was reached in 15 min of the auxin treatment.An antiauxin (2,4,6-trichlorophenoxyacetic acid), mitomycinC and cycloheximide inhibited auxin-induced increases in expansionand DE (or Rex, reversible extensibility) of young coleoptilecells. (Received July 23, 1968; )