Chromophore: apoprotein interactions in phytochrome A*

Phytochromes are molecular light switches by virtue of their photochromic red/far-red reversibility. The His-324 residue next to the chromophore-linked Cys-323 plays a critical role in conferring photochromism to the tetrapyrrole chromophore in native phytochrome A. The chromophore appears to be enclosed between the amphiphilic α-helical chains in a hydrophobic pocket. The absorbance maxima of both the Pr and the Pfr forms of pea phytochrome A are blue-shifted by 10 and 20 nm, respectively, upon C-terminal truncation. We speculate that the quaternary structure of the phytochrome A molecule involves some interactions of the C-terminal half with the chromophore domain. The Pfr conformation of phytochrome includes an amphiphilic α-helix of the amino terminal chain, which occurs in 113 ms after picosecond photoisomerization of the Pr form. Compared to α-helical folding, unfolding of the α-helix occurs faster in about 310 μs upon phototransformation of the Pfr form of phytochrome A. The photochromic transformation of phytochrome A modulates protein kinase-catalysed phosphorylation sites in vivo and in vitro, but only a subtle local change in conformation is detectable in the phosphorylated phytochromes. This suggests that the post-translational modification serves as a surface label, rather than a transducer-activating trigger, for the recognition of a putative phytochrome receptor.     

INFLUENCE OF OXIDATION-REDUCTION REDUCTANTS ON SALMONELLA TYPHIMURIUM GROWTH RATES AFTER INITIAL pH ADJUSTMENT AND ZINC COMPOUND ADDITION

The objective of this study was to examine the separate influence of acidic pH, reductants (cysteine and sulfide) and zinc compounds (Zn acetate and Zn sulfate) during anaerobic growth of a S. typhimurium poultry isolate in rich or minimal media. The anaerobic growth of a S. typhimurium poultry isolate in TSB medium was significantly inhibited by either acidic initial pH or higher concentrations of Zn acetate. S. typhimurium anaerobic growth in M9 minimal medium was significantly inhibited by either acidic pH or higher concentrations of Zn acetate or Zn sulfate. Most anaerobic growth rates of the S. typhimurium poultry isolate in acidic media and with higher concentrations of Zn acetate or Zn sulfate were less than 0.10 h^-1. The overall anaerobic growth rates of S. typhimurium were inhibited more in the presence (0.089 h^-1) of reductants than in the absence (0.102 h^-1) of reductants in M9 medium. Results in this study suggest that either increasing Zn concentration or decreasing initial pH can reduce growth rate of foodborne Salmonella under anaerobic growth conditions.     

Molecular Phylogeny among Local Populations of Formica japonica (Hym., Formicidae) in Korea

ABSTRACT Not only were used Random amplified polymorphismic DNA(RAPD) markers as input for an analysis of molecular variance (AMOVA) and cluster analysis to describe the population genetic structure, but also morphometric analysis of Formica japonica in Korea in order to investigate the relationships between local populations according to altitude. The ten populations of F. japonica in Korea did not showed any relationships according to altitude in morphological analysis, while they showed distinct relationship in RAPD analysis. It was noticed that they were clearly separated as four groups according to altitude. The first was Jirisan-Gachilbong- Gyebangsan population, the second Iksansi-Odongdo, the third Deukyusan-Hallasan, the fourth Siheungsi- Seonamsa-Jinjusi. The first group was high mountainous, the second flat and low altitude, the third high mountainous, and the fourth flat and low altitude. They occur from low altitude to comparative high altitude 1,400 m in Korea. Actually, it was found that the relationships of 10 local populations of Korean Formica japonica were not related to morphological evolution, but related to molecular evolutionary data evolved from RAPD analysis.     

APPLICATION OF A TRANSPOSON FOOTPRINTING TECHNIQUE FOR RAPID IDENTIFICATION OF SALMONELLA TYPHIMURIUM TN5 MUTANTS REQUIRED FOR SURVIVAL UNDER DESICCATION STRESS CONDITIONS

Salmonella spp. are one of the foodborne pathogens that can be isolated in the environments of poultry houses and desiccation is a potential stress condition that can influence the survival of Salmonella spp. in this environment. In order to investigate the desiccation survival mechanism of Salmonella spp. the genome of S. typhimurium ATCC 14028 was screened for the genes potentially required for survival during desiccation using a novel method based on Tn5 mutagenesis previously developed in our laboratory. This method, termed transposon footprinting, simultaneously amplifies the Tn5-flanking sequences in a complex pool of the Tn5 mutants. As the length of the amplified DNA fragment should be unique for each distinct Tn5 mutant, the polymerase chain reaction (PCR) products separated on an agarose gel generate transposon footprints with each band in the footprint representing the corresponding Tn5 mutant. By comparing the transposon footprints from the pools of S. typhimurium Tn5 mutants before and after exposure to desiccation, Tn5 mutants that were not recovered after the selection were rapidly identified that would be easily isolated for further genetic analysis.     

General biology of Ostrinia palustralis memnialis (Walker), a potential biological control agent of Rumex spp. in Korea

Ostrinia palustralis memnialis is an oligophagous insect that feeds on the species of the genus Rumex. Continuous rearing of O. palustralis memnialis was carried out from 2004 to 2005, and its general biology was studied. The preliminary host specificity test showed a promising result for O. palustralis memnialis as a potential biological control agent for Rumex spp.     

Upregulation of hemolymph and tissue ferritin by dietary HgCl2 in the wax moth Galleria mellonella

The effect of Hg treatment on hemolymph and tissue ferritin in the wax moth Galleria mellonella was examined by western blotting. At 48 h after feeding HgCl₂, the level of hemolymph ferritin increased approximately 1.8‐fold over that of control insects that were not fed HgCl₂, while there was a small increase in tissue ferritin. Time series experiments showed that tissue ferritin had a typically saturated pattern, with a maximum level from 24 to 72 h, although it decreased 12 h following HgCl₂ feeding, while hemolymph ferritin first decreased but subsequently increased. Tissue ferritin in the fat body, gut and Malpighian tubules, the main tissues of ferritin expression, was upregulated over time following treatment with Hg, and in particular, tissue ferritin in the gut increased by a large amount at 12–48 h. The results suggest that in G. mellonella, the ferritin‐inducible mechanisms following treatment with HgCl₂ are different for hemolymph and tissue ferritin, as are their biochemical properties.     

Production of Recombinant Hinnavin II/MSH Hybrid in Insect Cells

The increasing problem of antibiotic resistance among pathogenic bacteria requires development of new antimicrobial agents. For the purpose of this study, a cDNA encoding hinnavin II‐α‐melanocyte stimulating hormone (hin/MSH) hybrid was chemically synthesized, annealed, and then cloned into transfer vector pBacPAK 9 for expression in Sf21 insect cells. Recombinant hin/MSH (rhin/MSH) hybrid was efficiently produced in baculovirus expression vector system (BEVS) as a hybrid peptide. The antibacterial activity of the rhin/MSH hybrid was compared to that of the recombinant hinnavin II (rhin), using inhibition zone and overlay assay. This new recombinant hybrid peptide may serve as an attractive candidate for powerful novel class of antimicrobial pharmaceuticals.     

First Record of the Family Passandridae in Korea (Coleoptera: Cucujoidea)

A taxonomic study of the Korean Passandridae is presented. The family, genus and species (Ancistria apicalis Reitter) are reported for the first time in Korea. Comparison with a lectotype was made. An illustration of the habitus and line drawings of diagnostic characters are provided.     

Four New Species of Symphypleona (Collembola) from Korea

ABSTRACT Four new species of Symphypleona, Ptenothrix plumiseta, Deuterosminthurus serratus, Sminthurus annulatus, Smithurinus distinctus , are described from Korea. Especially two genera, Deuterosminthurus and Sminthurinus are new record to Korea. Korean Collembola Symphypleona add up to 18 species, 11 genera in 6 family.