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Rice straw is a promising resource for bioethanol production. Because the glucose content of pretreatment liquid hydrolysates is highly correlated with ethanol yield, the selection of appropriate rice cultivars is essential. The glucose content in liquid hydrolysates of pretreated rice straws of 208 diverse cultivars was evaluated in natural field in 2013 and 2014 using a novel high-throughput system. The glucose content of the rice straw samples varied across cultivars and was affected by environmental factors such as temperature and solar radiation. Several high-quality cultivars exhibiting high glucose content in both years were identified. The results of this study can aid in development of novel rice cultivars suitable as both feedstocks for bioethanol production and cooking.

The complete nucleotide sequences of the cDNA and its gene that encode a bifunctional α-amylase/subtilisin inhibitor of rice (Oryza sativaL.) (RASI) were analyzed. RASI cDNA (939 bp) encoded a 200-residue polypeptide with a molecular mass of 21,417 Da, including a signal peptide of 22 amino acids. Sequence comparison and phylogenetic analysis showed that RASI is closely related to α-amylase/subtilisin inhibitors from barley and wheat. RASI was found to be expressed only in seeds, suggesting that it has a seed-specific function. A coding region of RASI cDNA without the signal peptide was introduced into Escherichia coliand was expressed as a His-tagged protein. Recombinant RASI was purified to homogeneity in a single step by Ni-chelating affinity column chromatography and characterized to elucidate the target enzyme. The recombinant inhibitor had strong inhibitory activity toward subtilisin, with an equimolar relationship, comparable with that of native RASI, and weak inhibitory activity toward some microbial α-amylases, but not toward animal or insect α-amylases. These results suggest that RASI might function in the defense of the seed against microorganisms.

The plastid genome of higher plants contains more than one hundred genes for photosynthesis, gene expression, and other processes. Plastid transcription is done by two types of RNA polymerase, PEP and NEP. PEP is a eubacteria-type RNA polymerase that is essential for chloroplast development. In Arabidopsis thaliana, six sigma factors (SIG1-6) are encoded by the nuclear genome, and postulated to determine the transcription specificity of PEP. In this study, we constructed a DNA microarray for all of the plastid protein-coding genes, and analyzed the effects of the sig2lesion on the global plastid gene expression. Of the 79 plastid protein genes, it was found that only the psaJtranscript was decreased in the mutant, whereas transcripts of 47 genes were rather increased. Since many of the up-regulated genes are under the control of NEP, it was suggested that the NEP activity was increased in the sig2-1mutant.

Chloroplast transcription in higher plants is performed by two types of RNA polymerases, plastid-encoded RNA polymerase (PEP) and nuclear-encoded RNA polymerase (NEP). PEP is a eubacteria-type multisubunit enzyme whose catalytic core subunits are encoded by the chloroplast genome, whereas NEP is the nuclear encoded T7 phage-type single subunit enzyme. PEP is critical for the biogenesis and maintenance of chloroplasts, and is finely tuned by the nuclear encoded sigma subunits. Of the six Arabidopsissigma subunits, SIG2 is involved in the transcription of several chloroplast tRNA genes, including trnEencoding tRNA-Glu. SIG2 possibly couples translation and pigment synthesis in chloroplasts. On the other hand, SIG5 is induced by various stresses and contributes to repair of damaged photosystem II (PSII) through transcription of the psbDand psbCgenes. Thus target genes and the physiological role of each sigma subunit are becoming clearer.

Development of plastids into chloroplasts, the organelles of photosynthesis, is triggered by light. However, little is known of the factors involved in the complex coordination of light‐induced plastid gene expression, which must be directed by both nuclear and plastid genomes. We have isolated an Arabidopsismutant, abc1, with impaired chloroplast development, which results in a pale green leaf phenotype. The mutated nuclear gene encodes a sigma factor, SigB, presumably for the eubacterial‐like plastid RNA polymerase. Our results provide direct evidence that a nuclear‐derived prokaryotic‐like SigB protein, plays a critical role in the coordination of the two genomes for chloroplast development.

Three new nuclear genes (sigD, sigEand sigF) of Arabidopsis thaliana, encoding putative plastid RNA polymerase σ factors, were identified and analyzed. Phylogenetic analysis revealed that higher plant σ factors fell into at least four distinct subgroups within a diverse protein family. In addition, Arabidopsis siggenes contained conserved chromosomal intron sites, indicating that these genes arose by DNA duplication events during plant evolution. Transcript analyses revealed two alternatively spliced transcripts generated from the sigDregion, one of which is predicted to encode a σ protein lacking the carboxy‐terminal regions 3 and 4. Finally, the amino‐terminal sequence of the sigFgene product was shown to function as a plastid‐targeting signal using green fluorescent protein fusions.

Enterohemorrhagic Escherichia coli(EHEC) O157:H7 causes serious diarrhea and hemolytic uremic syndrome in humans. The expressions of EspD and intimin by O157:H7 have now been shown to be down-regulated by medium conditioned by O157:H7 grown at stationary phase. Preparation of conditioned medium showing the effect on the amount of EspD was not dependent on temperature or growth medium, but was dependent on growth phase. Inhibition of EspD and intimin expression was also induced by medium conditioned by E. coliK-12 strains and homoserine lactone, a signal molecule of the quorum-sensing system in Gram-negative bacteria. These results suggest the possibility that the quorum-sensing system mediated by self-produced extracellular factors plays an important role in control of colonization of EHEC O157:H7.

P‐type (or E1 E2‐type) ATPases comprise a large family of prokaryotic and eukaryotic proteins capable of transporting a variety of cations, and function in a wide variety of cellular processes. The present study was carried out to search for genes encoding P‐type ATPases in the phototrophie cyanobacterium, Synechococcussp. PCC7942. We succeeded in cloning two genes each encoding P‐type ATPases from this bacterium. It was found that Synechococcusat least, two distinct P‐type ATPases; one belongs to the family of typical prokaryotic P‐type ATPases and the other markedly resembles eukaryotic P‐type ATPases. An insertion mutant lacking either of these two ATPase‐genes was constructed. The results showed that the growth of these mutants is hypersensitive to osmotic stress upon addition of NaCl or sorbitol to the medium.

The OmpR protein of Escherichia coli is a positive regulator specific for the ompF and ompC genes. The function of OmpR is modulated through phosphotransfer signaling mediated by the kinase, EnvZ. We previously demonstrated that OmpR contains two functional domains, which are physically separable; one is responsible for the interaction with EnvZ, whereas the other participates in interactions with cognate promoter DNAs. In this study, these domains of OmpR were overproduced in wild-type cells harboring the endogenous intact ompR gene on their chromosome. It was found that when the N-terminal domain of OmpR, which contains the phosphorylation site, was overproduced, expression of the ompF and ompC genes was markedly inhibited, irrespective of the osmolarity of the growth medium. Based on our current model for the molecular mechanism underlying signal transduction through Envz-OmpR phosphotransger (T. Mizuno and S. Mizushima, Mol. Microbiol. 4, (1990), 1077–1082), we provide evidence that this phenomenon is best interpreted by the concept of ‘signal titration’ in the phosphotransfer signaling pathway.