Separation of the Effects of Photoperiod and Hormones on Sex Expression in Cucumber

The effects of photoperiod on the sex expression of cucumberflowers were examined in relation to the endogenous GA and ethyleneproduction with short day (SD)- and long day (LD)-sensitivecultivars under controlled environmental conditions. Growth of plants was greatly reduced under LD in both typesof cultivars. Reflecting this, GA activity was greater and ethyleneevolution less in plants grown under SD than in those underLD. However, the number of pistillate flowers increased underSD and LD in SD- and LD-sensitive cultivar, respectively, indicatingthat a change in sex expression did not coincide with hormonalchanges in the SD-sensitive cultivar. Thus, the effect of photoperiodon the sex expression was found to be separate, at least inpart, from the effect of GA or ethylene in cucumber. (Received September 16, 1982; Accepted December 7, 1982)     

Changes in Microtubules in Onion Leaf Sheath Cells during Bulb Development

Cortical microtubules are oriented transversely to the cellaxis in leaf sheath cells of onion plants (Allium cepa L. cv.Osaka-Okute) that have not started bulb formation. As the bulbdevelops and the leaf sheath cells swell, the microtubules becomedisoriented and scattered and finally disappear. The microtubuleinhibitors colchicine and cremart [O-ethyl O-(3-methyl-6-nitrophenyl)N-sec-butylphosphorothioamidate]cause swelling of leaf sheath cells and make the basal partof the plant bulbous. The cortical microtubules may have animportant role in regulating bulb development in onion plants. (Received August 21, 1982; Accepted December 6, 1982)     

Effect of TPA on the mutagenicity of caffeine in the soybean mutation test

12-O-Tetradecanoylphorbol-13-acetate (TPA) is a well-known tumor promoter in mouse-skin carcinogenesis. Its effects on mutagenesis in a soybean test system were examined, and the effects were judged from the appearance of spots of various colors on the leaves. When soybean seeds were treated with TPA plus 0.03% caffeine, the frequency of spots per leaf decreased significantly and in proportion to the concentration of TPA. TPA alone at concentrations of 1–20 μg/ml did not induce any mutations. Mutations induced by γ-rays were not affected by administration of TPA either before or after exposure to γ-rays. The mechanism of suppression by TPA of mutations induced by caffeine is discussed.     

Changes in leukocyte count, blood glucose and coagulation system in calves injected with Escherichia coli endotoxin

Responses of leukocyte, blood glucose and coagulation system in calves were investigated to injection with Escherichia coli endotoxin. Severe leukopenia and hyperglycemia following transient hypoglycemia were noted within 24 hours after injection. In the coagulation system, a definite decrease in platelet count, prolongation of prothrombin time and activated partial thromboplastin time were observed. Fibrinogen, soluble fibrin monomer complex and clotting time, however, varied.     

The ultrastructural basis of the permeability of arterial endothelium to horseradish peroxidase

The thoracic aorta and basilar artery, in which the incidence of atherosclerosis is known to be different, were examined to elucidate the correlation between the structure of the intercellular cleft junction between adjacent endothelial cells and its permeability to HRP. Tannic acid or HRP in the vessel lumen passed through the intercellular clefts of the thoracic aorta into the subendothelial space, whereas in the basilar artery they were unable to penetrate beyond the tight junction of the intercellular clefts. Freeze-fracture replicas revealed that the tight junctions of the thoracic aorta consisted of one to two junctional strands in most areas of the cleaved planes, with discontinuities in some places, whereas those of the basilar artery consisted of a continuous belt-like meshwork of six anastomosing junctional strands on average. These observations confirm that the structure of endothelial junctions in arteries has a close correlation with the permeability of the intercellular clefts to HRP.