Tsugio Shiroya

Metabolism of raffinose in cotton seeds

Abstract Raffinose and stachyose, in addition to sucrose, are present in the resting seeds of cotton, and on germination, raffinose and stachyose decreased and then disappeared completely, while sucrose and reducing sugars increased to a considerable extent. No free galactose or any other oligosaccharide containing galactose was detected throughout germination, α-galactosidase activity was fairly high in resting seeds and rose in soaked and germinated seeds, while invertase activity was very low in resting and soaked seeds but increased markedly in germinated seedlings. By infiltrating d -galactose, it was shown that an effective mechanism for galactose utilization existed in the cotyledons of germinated seedling. Galactokinase activity was, however, very low in the germinated seedling. Aerobic conditions were found to be necessary not only for germination but also for disappearance of raffinose and utilization of galactose. Raffinose appeared in the seed during ripening, but was not detected in any other parts of the plant body. Raffinose was also formed in unripe seeds when they were detached from cotton boll and air-dried, suggesting the existence of a system for the formation of raffinose inside the unripe seed, Stachyose was formed from raffinose by transgalactosidation.

The sugars in the seeds and seedlings of Pinus Thunbergii.

Summary o 1. By paper partition chromatography, it has been shown that raffinose and stachyose, in addition to sucrose, are present in the resting seeds of Pinus Thunbergii. 2. The raffinose and stachyose disappeared completely and sucrose increased to a considerable extent in the germinating seeds. Reducing sugars were not observed in resting seeds, but were found as soon as germination began. 3. Free galactose and di- or trisaccharide containing galactose as a component were not detectable throughout all stages of germination. 4. α-Galactosidase activity only was conspicuous, and invertase seemed not to be present in the resting seeds. In sharp contrast with this, the enzyme activity of the former was low, and that of the latter, high, in germinated and grown seedlings.

ACTION SPECTRUM FOR PHOTOREACTIVATION OF ULTRAVIOLET‐INDUCED MORPHOLOGICAL ABNORMALITY IN SEA URCHIN EGGS

Abstract An action spectrum was obtained for photoreactivation (PR) of morphological abnormality arising from ultraviolet (UV)‐irradiation of sea urchin sperm. The wavelength dependence of PR was measured by the restoration of the formation of normal pluteus larvae after the exposure of fertilized eggs to various fluences of monochromatic PR light (313 to 500 nm). The PR action spectrum showed a maximum around 365 nm and a secondary peak somewhere above 400 nm. High PR activity beyond 400 nm wavelengths may reflect an advantageous or adaptational ability to cope with harmful effects of solar UV radiation.

Purification and characterization of arylsulfatase from sea urchin (Hemicentrotus pulcherrimus) embryos

Abstract 1. 1. Arylsulfatase was extracted from sea urchin (Hemicentrotus pulcherrimus) plutei and purified to electrophoretical homogeneity by means of DEAE-cellulose, acetone fractionation and Sepharose CL-6B, successively. 2. 2. The molecular weight of this enzyme was approx, 670,000. The molecular weight of a single subunit was approx. 63,000. The Km value for p-nitrophenyl sulfate was 0.59 mM. 3. 3. This enzyme was competitively inhibited by the sulfate ion and was classified as the type II arylsulfatase. The pH optimum was between 5.0 and 6.0.

PHOTOREVERSIBILITY OF UV-INDUCED THYMINE DIMERS AND ABNORMAL MORPHOGENESIS IN SEA-URCHIN EMBRYOS

Abstract— Irradiation of synchronously dividing 16‐cell embryos of a sea‐urchin (Hemicentrotus pul‐cherrimus) with 200 J m−2 of UV light (254 nm) resulted in the complete inhibition of normal pluteus‐larva formation when the embryos were cultured in the dark after UV‐irradiation. Illumination of the UV‐irradiated embryos with visible light (11 W m−2) for 1 h immediately after the UV‐irradiation reversed the abnormal morphogenesis. Measurement of thymine dimers indicates that the degree of UV‐induced abnormal morphogenesis is greatly correlated with the amount of thymine dimers in the DNA of the embryos. The degree of the photoreversal decreased with an increase in the interval between UV‐irradiation and exposure to visible light. Visible light was ineffective as to the reversibility of both thymine dimers and the abnormal morphogenesis at 60 min after the UV‐irradiation, when the UV‐irradiated 16‐cell embryos entered the next cell cycle.

Photoreactivation associated with chromosomal abnormality in sea urchin eggs fertilized with ultraviolet-irradiated sperm.

Abstract Chromosomal abnormality due to the ultraviolet (UV) irradiation of sperm and its modification by photoreactivation (PR) were studied in the sea urchin, Hemicentrotus pulcherrimus. When sperm was UV‐irradiated and allowed to fertilize unirradiated eggs, the effect of UV was manifested as an abnormal separation of chromosomes at the anaphase of the first mitosis. The frequency of abnormal anaphase increased with UV fluence. In the UV fluence of larger than 20J/m2, more than 90% of eggs showed chromosomal abnormality. The UV‐induced chromosomal abnormality was prevented by photoreactivation when the fertilized eggs were illuminated with visible light. The PR sector for the PR of chromosomal abnormality, which was comparable to the PR sector for morphological abnormality, was higher than that of cleavage delay. The UV sensitivity expressed in terms of chromosomal abnormality was significantly higher than the sensitivity expressed in terms of morphological abnormality. Photo‐reactivation illumination sufficed to effect a nearly complete PR when applied up to 20 min after fertilization, while the PR effectiveness declined thereafter. Illumination after 40 min had little effect for PR.

PHOTOREACTIVATION ASSOCIATED WITH MORPHOLOGICAL ABNORMALITY IN SEA URCHIN EMBRYOS INDUCED BY ULTRAVIOLET-IRRADIATED SPERM

Abstract— Morphological abnormality due to the UV irradiation of sperm and its modification by photoreactivation (PR) were studied in the sea urchin, Hemicentrotus pukherrimus. When sperm was UV‐irradiated and allowed to fertilize unirradiated eggs, the effect of the UV was manifested as an abnormal morphology of embryos in the gastrula or later stages. The UV‐induced morphological abnormality was prevented by photoreactivation when the fertilized eggs were illuminated with visible light. In the experiments on a stage‐dependent change of PR effectiveness, it was found that an illumination sufficed to effect a nearly complete PR when applied up to the onset of the first DNA synthetic phase, while the PR effectiveness declined thereafter. Illumination after the completion of DNA synthesis had little effect for PR.

Developmental Timing of Synthesis and Translation of Arylsulfatase mRNA in Sea Urchin Embryo

In the sea urchin (Hemicentrotus pulcherrimus) embryo, the arylsulfatase activity is known to increase dramatically after the mesenchyme blastula stage. In the present experiment, we have studied the mechanism underlying this increase in the arylsulfatase activity by using the inhibitors of transcription and translation. Inhibition of transcription by actionmycin D before hatching prevented the increase in the arylsulfatase activity, while inhibition of transcription after hatching failed to prevent the increase in the enzyme activity. Inhibition of translation by emetine always reduced the arylsulfatase activity. These results have been interpreted as that the arylsulfatase activity in the blastula embryo is supported by the pre‐synthesized mRNA, and that the marked increase in the enzyme activity which is observed from the mesenchyme‐blastula stage to the prism stage is due to the transcription of the arylsulfatase gene which occurs during the development from hatching to the mesenchyme‐blastula stage.

Biphasic stage sensitivity to UV suppression of gastrulation in sea urchin embryos.

The effects of ultraviolet light (UV) on the gastrulation of sea urchin embryos were examined. The results suggest that gastrulation is inhibited by UV irradiation and that stage sensitivity to UV suppression of gastrulation changes biphasically: higher sensitivity at early and late blastula, and lower sensitivity at the mid-blastula stages. The UV-induced inhibition of gastrulation was completely reversible by subsequent exposure to visible light.

Purification of Acetylcholinesterase from Sea Urchin (Hemicentrotus pulcherrimus) Embryos by Affinity Chromatography

Only one form of acetylcholinesterase (AchE) was detected in Hemicentrotus pulcherrimus embryos. In H. pulcherrimus embryos as well as in the other sea urchin embryos, AchE activity begins to increase rapidly after gastrula stage.