Effects of ethanol on the growth and elongation of Escherichia coli under high pressures up to 40 MPa

The effects of ethanol on growth, viability and cell length were studied in Escherichia coli cultured under pressures up to 40 MPa (400 bar). A pressure of 10 MPa reversed the effect of ethanol in retarding cell growth. Cells cultured in the absence of ethanol became about seven times longer at 40 MPa than at atmospheric pressure, and some cells showed incomplete cell division. Ethanol also increased cell length but these effects were not seen at pressures of 20 MPa or more.     

A proteomic approach to identification of transmembrane proteins and membrane-anchored proteins of Arabidopsis thaliana by peptide sequencing.

A proteomic approach was developed for the identification of membrane-bound proteins of Arabidopsis thaliana. A subcellular fraction enriched in vacuolar membranes was prepared from 4-week-old plants and was washed with various agents to remove peripheral membrane proteins and contaminating soluble proteins. The remaining membrane-bound proteins were then subjected to proteomic analysis. Given that these proteins were resolved poorly by standard two-dimensional gel electrophoresis, we subjected them instead to SDS-polyacrylamide gel electrophoresis and to protein digestion within gel slices with lysylendopeptidase. The resulting peptides were separated by reverse-phase high-performance liquid chromatography and subjected to Edman sequencing. From the 163 peptide peaks analyzed, 69 peptide sequences were obtained, 64 of which were informative. The proteins corresponding to these peptide sequences were identified as belonging to 42 families, including two subfamilies, by comparison with the protein sequences predicted from annotation of the A. thaliana genome. A total of 34 proteins was identified definitively with protein-specific peptide sequences. Transmembrane proteins detected in the membrane fraction included transporters, channels, receptors, and unknown molecules, whereas the remaining proteins, categorized as membrane-anchored proteins, included small GTPases, GTPase binding proteins, heat shock protein 70-like proteins, ribosomal proteins, and unknown proteins. These membrane-anchored proteins are likely attached to membranes by hydrophobic anchor molecules or through tight association with other membrane-bound proteins. This proteomic approach has thus proved effective for the identification of membrane-bound proteins.     

Antennal and locomotor responses to attractive and aversive odors in the searching cockroach

The behavioral responses to attractive and aversive odors were examined in blinded adult male cockroaches under tethered-walking conditions. A sex pheromone-like stimulant derived from adult virgin females and artificially synthesized limonene were used as attractive and aversive odor sources, respectively. When a searching animal was stimulated with the attractive female-derived odor, the horizontal deflections of both the antennae were increased, and in most cases the vertical antennal positions were shifted downward. The stimulation also significantly decreased the walking speed of the animal. These behavioral changes imply a careful search in the immediate surroundings. The aftereffect of the sex pheromone was more pronounced on locomotion than on antennal movement. On the other hand, stimulation with the aversive odor (limonene) tended to suppress active antennal movement, and also increased the walking speed. Immediately after the withdrawal of the aversive odor, the active movement of the antennae was resumed, and the walking speed rapidly decreased to a level approximately the same as that of the control period. These results indicate that the responses to the qualitatively opposite types of odor are reciprocal to each other with regard to both antennal movement and locomotion.     

Effects of microenvironmental heterogeneity on the seed-to-seedling process and tree coexistence in a riparian forest

In a temperate riparian forest, the effects of substrate types, canopy gaps and conspecific seedfall density were investigated on the seed-to-seedling process for the five dominant species (Aesculus turbinata, Fagus crenata, Acer mono, Pterocarya rhoifolia and Cercidiphyllum japonicum). Densities of seedfall and subsequent seedling recruits were measured in the stand over a period of 6 years. A model assuming that local density of seedling recruits is proportional to seedfall density in the preceding year significantly explained a spatial variation in seedling recruits for all species. Several environmental factors were then added. Substrate composition had a positive effect on P. rhoifolia and C. japonicum. P. rhoifolia was favored by gravel substrate, which also explained the adult distribution of this species in this forest. C. japonicum appeared to be facilitated by a mineral-soil substrate. However, the distributions of this substrate and adults of C. japonicum did not follow each other closely. A. mono was negatively affected by gaps, and F. crenata was negatively affected by conspecific seedfall density. In contrast, A. turbinata was not significantly affected by any of the environmental factors tested. The microenvironmental heterogeneity in this forest explained species coexistence to a limited extent in the context of seed-to-seedling processes. Performances at later stages of the life-cycle and/or catastrophic disturbances (e.g. landslides) might have a stronger influence on species coexistence in this forest.     

Molecular analysis of the deletion mutants in the E homeotic complex of the silkworm Bombyx mori.

The E loci in Bombyx mori are expected to contain a homeotic gene complex specifying the identities of the larval abdominal segments. However, the molecular structure of this complex remains to be determined. We have started to analyze the structural changes in the E complex mutations. We used three newly isolated Bombyx homeobox genes as probes. These genes are probably homologues of the Ultrabithorax (Ubx), abdominal-A (abd-A) and Abdominal-B (Abd-B) in the Drosophila bithorax complex, because the amino-acid sequences of the homeobox regions in these Bombyx genes are almost identical to those of Drosophila genes. We found that the Bombyx Ubx and abd-A genes are deleted in the EN chromosome, and the Bombyx abd-A gene is deleted in the ECa chromosome. From these results, we conclude that the Bombyx E complex consists of the Ubx, abd-A and possibly Abd-B genes, which may play similar roles to their homologues in the Drosophila bithorax complex.