The Relationship between Antigenic Compounds Produced by Sweet Potato in Response to Black Rot Infection and the Magnitude of Disease Resistance

Tissue extracts of healthy, sliced and black-rotted sweet potato roots of several Japanese varieties showed immunochemical precipitation lines with antisera toward sliced and diseased tissue extracts prepared from an American resistant variety, Sunnyside. The immunochemical precipitation patterns of healthy and sliced tissue extracts and those of diseased tissue extract of the Japanese varieties respectively were almost the same as those of sliced and diseased tissue extracts of the American Sunnyside. Antigenic components designated as A and Cs were distributed in all tissue extracts of both Japanese and American varieties. Components B and D were produced in response to the infection in root tissues of Japanese varieties as well as of American ones. The amount of component B produced in several Japanese varieties was correlated with the magnitude of resistance action of root tissues to the fungus infection and the order was as follows: Norm No. 10 (highly resistant) >Norin No. 1 and Okimasari (resistant) >Norin No. 4 and Norin No. 5 (susceptible). Components B and D seemed to be present in healthy root tissue in very small amounts, and showed an increase in response to the simple injury or slicing, though the magnitude of this increase was much less than the response to the pathogenic infection.     

Morphological Changes in Chilling Injured Sweet Potato Root

Hydrophobicity and amounts of polar groups on the cell surface were determined by the use of fluorescent probe, colloid titration, and acid titration. Surface hydrophobicity of hydrocarbon-grown cells was about 7 times greater than that of glucose-grown cells of the same strain, while amounts of polar groups did not differ so much. Adsorption of cells to air bubbles was maximum at pH 3. Langmuir’s adsorption isotherm held for the adsorption. Affinity to air bubbles of hydrocarbon-grown cells was 1.8 times greater than that of glucose-grown cells, while the theoretical maximum amounts of cells to adsorb per unit area of bubbles were equal for the both cells.     

Improved Synthesis of 3-14C-3-Hydroxy-3-methylglutaryl Coenzyme A

A new polysaccharide with a molecular weight of 5.0×10⁴ was isolated as a possible wheat allergen from a water-soluble fraction of flour by affinity chromatography and gel filtration. The isolated polysaccharide was found to be a possible wheat allergen, as it bound specifically to IgE antibodies in the sera of patients allergic to the water-soluble fraction of flour. Chemically, the sugar moiety of the polysaccharide consisted of D-glucose and D-mannose with β-1,4-linkages in a molar ratio of 4.4:1. Since this mannoglucan is thought to be stable in our body, it would act as a remaining allergen to cause a long-lasting allergic reaction to wheat flour.     

Mechanism of Chilling Injury in Sweet Potatoes

1. 1. Both amounts of lipid phosphorus and acid-insoluble nitrogen in the mitochondrial fraction from chilling-injured sweet potatoes (var. Okinawa 100) were larger than in the fraction from healthy sweet potatoes. The N-amount appeared to be increased more by chilling-injury than the P-amount.

2. 2. Sweet potato, a tropical plant, showed lower value of the degree of unsaturation of fatty acids in mitochondrial fraction than white potato, a temperate-zone plant.

3. 3. The amount of unsaturated fatty acids of C₁₆, C₁₈ and C₂₀ as percentage of the total fatty acids was higher in mitochondrial fractions from chilling-injured sweet potatoes (var. Okinawa 100 and var. Norin 1) than in mitochondrial fractions from healthy sweet potatoes. However, in the case of white potato mitochondrial fraction no detectable difference was observed between storage at 0~1°C and at 10~14°C.

     

Phytopathological Chemistry of Black Rot Sweet Potato

The proteolytic enzyme system in the tissues of sweet potato root was partially purified and its several characteristics were investigated. Based on the results from these preliminary experiments, we found that proteolytic activity in the tissues suffering from black rot declines as penetration of the pathogen proceeds. Procedures to extract the enzyme system from the affected plant tissues were also established. The diminution in activity of the affected tissues was discussed in connection with those results reported hitherto.     

The Effect of NADP+ on Electrophoretic Behavior of Glucose 6-Phosphate Dehydrogenase from Sweet Potato

The gene from Bacillus brevis TT02–8 encoding arginase was cloned into Escherichia coli, and its nucleotide sequence was identified. The nucleotide sequence contained an open reading frame that encoded a polypeptide of 298 amino acid residues with a predicted molecular weight of 31,891, which was consistent with that previously calculated for arginase purified from this bacterium. Comparison of the deduced amino acid sequence of the B. brevis TT02–8 arginase with that of the prokaryotic and eukaryotic arginases of Bacillus caldovelox, Bacillus subtilis, Agrobacterium Ti plasmid C58, Saccharomyces cerevisiae, Coccidioides immitis, Xenopus laevis, Rana catesbeiana, rat liver, and human liver, showed 33–66% of the sequences to be similar; there were several highly conserved regions. Arginase activity was detected in Escherichia coli cells transformed with an expression plasmid of the cloned arginase gene.     

Occurrence of 3-Hydroxy-3-methyl-glutaryl Coenzyme A Reductase in Sweet Potato

Illumination of the dark-grown Euglena gracilis, both the wild-green type and a permanently bleached mutant, for 4 hr at 2,000 lux caused about 6-fold increase of the cellular content of total l-ascorbic acid. The increase was mainly due to an increase of reduced-form l-ascorbic acid. From the action spectrum only blue light was found to be effective for the increase. Darkening stopped the increase and reillumination started a renewed increase. The activity of l-gulono-γ-lactone dehydrogenase, catalyzing the last step of l-ascorbic acid biosynthesis, was also increased two fold by illumination for 2 hr, and was changed in parallel to that of the cellular content of l-ascorbic acid depending on the presence or absence of illumination. The augmentation of l-ascorbic acid formation was markedly inhibited by various inhibitors and uncouplers, but not by dichlorophenyldimethylurea. The results in sum suggest that the light-dependent increase of l-ascorbic acid formation in E. gracilis is not primarily associated with photosynthesis, but is apparently related to the adaptation of the dark-grown cells to the illuminated state.     

Biochemical Effects of Gamma Radiation on Potato and Sweet Potato Tissues

Relationship between the chemical constituents of tobacco leaves and the gaseous constituents of cigarette smoke from which K value¹⁾ was computed was discussed and the following presuppositions were demonstrated to be correct.

1. Fibrous substances in tobacco leaves are the main precursors of acetaldehyde, propionaldehyde, acrolein, acetone, methylethylketone, diacetyl, methanol, furan, an unknown compound, No. 6 and an unknown compound, No. 16 in cigarette smoke.

2. Sugars in tobacco leaves are the main precursors of 2-methylfuran and 2,5-dimethyl- furan in cigarette smoke.

3. Resinous substances in tobacco leaves are the main precursors of isoprene and an unknown compound, No. 2 in cigarette smoke.