Microheterogeneity of PSI-E Subunit of Photosystem I in Nicotiana sylvestris

Microheterogeneity of a photosystem I (PSI) subunit encodedby a nuclear gene psaE was examined in Nicotiana sylvestris,with the aid of cDNA cloning, peptide mapping analysis and proteinsequencing. The psaE product of this plant has four isoformswhose mobilities in PAGE are slightly different from each other.We isolated two types of psaE cDNAs from a N. sylvestris cDNAlibrary, and designated the corresponding genes as psaEa andpsaEb, respectively. The psaEa and psaEb genes are 77% homologousat DNA level, and their translation products share 80.4% homologyfor the precursor proteins and 89.1% for the mature forms. Comparativeanalysis of the four isoproteins and the putative products ofthe two psaE genes revealed that two isoproteins out of fourare derived from psaEa gene, and the difference between thesetwo isoproteins lies in the respective presence or absence ofN-terminal alanine. Likewise, the other two proteins are derivedfrom psaEb with similar N-terminal heterogeneity. These resultsindicate that multi-gene organization and heterogeneous N-terminalformation at post-translational level are two possible causesfor PSI subunit polymorphism in isogenic plant lines. (Received October 8, 1993; Accepted November 30, 1993)     

Direct atomization atomic absorption spectrometry for intact biological samples: application to trace metal analysis in silkworm eggs and their hatched worms.

Highly sensitive carbon rod atomic absorption for trace elements was observed by direct atomization of samples with no pretreatment for intact silkworm eggs, their hatched worms, or National Bureau of Standards biological samples (orchard leaves and bovine liver). Crucial temperatures for drying, ashing, and atomization processes were found to obtain accurate results. Results were consistent with those of activation analyses and of ordinary atomic absorption with wet ashing. The precision and dynamic range of this method were evaluated. The advantages and disadvantages of the present approach were critically discussed.     

Scanning electron-microscopy of starch granules, with or without amylase attack

Scanning electron-microscopy (SEM) revealed that, for starch granules relatively susceptible to amylase, numerous pin holes could be observed on the surfaces of granules attacked by amylase. We also observed that the pores penetrated into the inner layers of granules during the enzyme action and some of the granules exhibited a terraced or step-shaped apperance in their inner portions. These internal characteristics are most probably indicative of layered internal structures of the granules. The other characteristic observations by SEM were striated structures on the surfaces of starch granules of banana, lily, and lotus attacked by pancreatin.     

Chemical identification and functional analysis of apocarotenoids involved in the development of arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizae formed between more than 80% of land plants and arbuscular mycorrhizal (AM) fungi represent the most widespread symbiosis on the earth. AM fungi facilitate the uptake of soil nutrients, especially phosphate, by plants, and in return obtain carbohydrates from hosts. Apocarotenoids, oxidative cleavage products of carotenoids, have been found to play a critical role in the establishment of AM symbiosis. Strigolactones previously isolated as seed-germination stimulants for root parasitic weeds act as a chemical signal for AM fungi during presymbiotic stages. Stimulation of carotenoid metabolism, leading to massive accumulation of mycorradicin and cyclohexenone derivatives, occurs during root colonization by AM fungi. This review highlights research into the chemical identification of arbuscular mycorrhiza-related apocarotenoids and their role in the regulation and establishment of AM symbiosis conducted in the past 10 years.     

Purification and Some Properties of Debranching Enzyme of Germinating Rice Endosperm

A debranching enzyme was extracted from the endosperm of germinating rice seeds and purified through three steps, namely cyclohexaamylose-coupled Sepharose 6B, Ultrogel AcA-44 and Bio-Gel P-150 column chromatography. This disc-electrophoretically homogeneous enzyme showed a specific activity of 43 units/mg of protein (30°C) with a pH optimum of 5.5. The isoelectric point was 4.9, unlike that (pI 3.5) of debranching enzyme of ungerminated rice seeds. Our enzyme hydrolyzed pullulan rapidly, and glutinous rice starch and waxy corn starch moderately. The enzyme was also able to act on phytoglycogen and glycogen unlike debranching enzymes originating in some plants.     

Detection of SO2 at the ppm Level with Localized Surface Plasmon Resonance (LSPR) Sensing

Plasmonics - Detection and monitoring of SO2 is important because it is a representative toxic gas in the atmospheric environment that is emitted from industrial and natural processes. Localized...     

Isolation and Characterization of Globulin from Seeds of Amaranthus hypochondriacus L.

Seeds of grain amaranths contain a high amount (about 60% of total nitrogen) of albumin and globulin and a trace amount of prolamin. From salt-soluble extracts of A. hypochondriacus seeds, a globulin (440,000 in apparent molecular weight and ) was purified by Sepharose 6B gel and DEAE-cellulose column chromatographies. The protein comprised at least four kinds of subunits whose molecular weights were 36,000, 32,000, 20,000 and 18,000, respectively. The amino acid composition of the globulin was almost similar to those of soybean and oat globulins.     

Biosynthesis of Cercosporin

¹³C NMR spectra were measured for 19 pyrethroids and their related compounds including allethrin, tetramethrin, resmethrin, furamethrin, phenothrin and permethrin. Complete assignment of chemical shifts was accomplished by relative spectral pattern, single-frequency off-resonance decoupling, benzene substituent effects, proton selective decoupling and use of shift reagents. The use of shift reagent was found to be especially efficient for assignment of ¹³C resonances. In the case of allethrin, the splittings of some resonance peaks were observed originating from diastereomerism.