シクロヘキシミド処理タバコ葉細胞の微細構造

The effect of cycloheximide on cell organelles was investigated at the level of ultrastructure, with an emphasis on the ribosomal behaviors. The antibiotic, at low concentrations, primarily caused an orderly alignment of ribosomes on endoplasmic reticuli (ER), giving rise to rough-surfaced ER. Development of membrane systems was also a characteristic feature of the cells treated at low concentration or incubated for short period of time. Prolonged incubation or treatment at higher concentrations led eventuaily to the degeneration of cytoplasmic and nuclar organizations, the aggregation of ribosomal debris being one of the conspicuous features. On the contrary, no major structural change was observed of the chloroplasts and mitochondria which are both resistant to the inhibitory action of cycloheximide. These results were discussed in relation to the inhibition of protein synthesis by the cycloheximide

有機ふっ素化合物の脱ふっ素に関与する土壌微生物について

Microbial population in soils was studied in relation to defluorinaton of organic fluorine compounds, monofluoroacetate (FA) and monofluoroacetamide (FAA). No significant difference in microbial pooulation was observed between the soils collected from FAA-sprayed and non-sprayed citrus orchards. Soils of the FA-producing factory contained more bacteria which are capable of growing in a medium containing FA or FAA as a sole source of carbon. The soils sprayed with relatively large amount of the pesticide ingredients contained more ingredient resistant bacteria, by 30 days after spraying, suggesting that a temporary seleection to the ingredient degradation occurs in soils. The defluorination in soils, however, was not as high as had been expected

シクロヘキシミドのタバコ葉核酸代謝におよぼす影響

The effect of cycloheximide on RNA metabolism in tobacco leaf discs was analyzed to signify its inhibitive or stimulative effect on TMV multiplication. RNA content increased in the leaf discs incubated in 1.0 or 3.0 ppm solution. 32P-incorporation into RNA, however, was accelerated at 1.0 ppm and disturbed at 3.0 ppm, suggestirg th~t the increment of RNA in the leaf disc<- treated at 1. O ppm is qualitatively different from that in the discs incubated at 3.0 ppm, i. e., the former is the result of stimulated synthesis while the latter is mainly due to the inhibition of degradation. Column chromatograms with methylated albumin Kiselguhr clearly elucidated that incubation of discs in 3.0 ppm led to the abolition of the integrity of the light ribosomal RNA. The change in chromatographic pattern was discernible 24 hr after the initiation of treatment of leaf discs. Incubation in 1.0 ppm cycloheximide, however, did not give rise to a drastic change in chromatograms, although an undulate incorporation of 32P-orthophosphate into ribosomal RNAs was noticed. 14C-glycine incorporation into RNA suggested that cycloheximide not only enhances RNA synthesis but also stimulates the synthesis of purine bases. Ribonuclease activity of leaf homogenate remarkably decreased by cycloheximide treatment, suggesting that the accumulation of RNA in the discs treated at 3.0 ppm could be acounted for by the retardation in RNA degradation. The inhibitory and stimulative effects of cycloheximide on TMV multiplication were discussed on the basis of these results

土壌菌による有機塩素殺菌剤、ダコニールの吸収と脱クロールについて

Fungi tolerant to an organochlorine fungicide, tetrachloroisophthalonitrile (TCPN), was selected and isolated from various soil samples, and examined for the activity to metabolize TCPN. The population of tolerant fungi was extremely large in the plastic house - soil on which TCPN has been used for six years to control diseases. This is probably due to the change of soil microflora owing to the decline of TCPN-sensitive competitors. Many tolerant fungi took up TCPN very rapidly from culture filtrate. Of ten tolerant isolates tested, two isolates, C-F- I and V-P-5, were found to metabolize TCPN. The metabolite was isolated in pure form by preparative TLC, and identified as trichloroisophthalonitrile by mass spectrometry. C-F-1 was identified as Aspergillus luchuensis and V-P-5 as Penicillium godlewskii. Namely, these soil fungi dechlorinate from tetrachloroisophthalontrile to trichloroisophthalonitrile

エンドウ褐紋病菌の胞子発芽液に含まれるピサチン蓄積誘導物質の分離と性質

An elicitor of pisatin accumulation was isolated and partially characterized from spore germination fluid, mycelial extract, and cell wall preparation of a pea pathogen, Mycosphaerella pinodes. The elicitor was found to be a polysaccharide or glycoprotein and the active component was composed of glucose. The approximate molecular weight was 70,000 daltons. This elicitor elicited pisatin accumulation in pea leaves at a concentration of 10 ug/ml and the maximum activity was ca. 350-400 ug/ml, but did not elicit phytoalexins in soybean, bean, and red clover. High molecular weight preparations from the mycelial extract and mycelial wall of Mycosphaerella melonis and Stemphylium sarcinaeforme, nonpathogens of pea, elicited pisatin accumulation in pea leaves

農業用殺菌剤、植物病原菌の有害代謝産物によるファイトアレキシンの生産

The endocarp of the fresh pea pod incubated with solution or suspension of agricultural fungicides, phytotoxic metabolites of plant pathogenic fungi formed the pea phytoalexin, pisatin. Among the compounds tested, cycloheximide, triazine, dichlone, phenyimercury acetate, UV degradation product of phenylmercury acetate, triphenyltin fungicides, and 3-hydroxy-5-methylisoxazole induced pisatin. Ophiobolin, a toxin from Cochliobolus mtyabeanus, and ascochitine, a toxic metabolite from Ascochyta fabae, also induced pisatin. The possibilities of the development of harmless plant disease control agents was discussed in relation- to the induced synthesis of phytoalexins

Carbohydrate structures of the cell adhesion molecule, contact site A, from Dictyostelium discoideum

AbstractWe determined the carbohydrate structures of contact site A from Dictyostelium discoideum. The carbohydrate moieties of contact site A were released by hydrazinolysis. Fractionation of the deacidified oligosaccharide mixture by Bio-Gel P-4 column chromatography revealed that it was composed of four major oligosaccharides. Their respective structures were determined by sequential exoglycosidase digestion. It is known that contact site A consists of two kinds of carbohydrates, I and II. Taking together the previous and the present results, it was deduced that carbohydrate I comprises N-linked oligosaccharides and carbohydrate II O-linked ones. Furthermore, the relative molar contents of GalNAc and GlcNAc in reducing terminal suggested that contact site A contains 67% of N-linked and 33% of O-linked oligosaccharides