The Archaea Community Associated with Lava-Formed Gotjawal Forest Soil in Jeju, Korea

The abundance and diversity of archaeal assemblages were analyzed in soils collected from Gyorae Gotjawal forest, Jeju, Korea. Gotjawal soil refers to soil derived from a lava-formed forest, characterized by high organic matter content, fertility, and poor rocky soil. Using domain-specific primers, archaeal 16S rRNA gene sequences were PCR amplified for clone library construction, and a total of 185 archaeal clones were examined. The archaeal clones were affiliated with the phyla Thaumarchaeota (96.2%) and Euryarchaeota (3.8%). The most abundant thaumarchaeal group (90.3% of the clones) was the group I.1b clade, which includes soil ammonia-oxidizing archaea. The unique characteristics of Gotjawal soil, including basalt morphology, vegetation, and groundwater aquifer penetration, may be reflected in the archaeal community composition. Further study is necessary to understand the unique factors of Gotjawal soils that influence archaeal abundance, composition, and diversity.

Biphenyl- and carvone-induced protein expression patterns in Rhodococcus sp. ACS

Protein expression patterns in the polychlorinated biphenyl (PCB)-degrading Rhodococcussp. strain ACS were examined following growth on two substrates capable of inducing the enantioselective biotransformation of PCBs via different degradation pathways. Eleven inducible proteins were identified by SDS-PAGE and characterized by LC-MS/MS. Four of the peptides, a spore coat protein, an extracellular serine protease, a spoVP, and a molecular chaperonin from Bacillus subtilis, were identified as being unique to biphenyl-induced cells, whereas anextracellular serine protease from B. subtilis was identified as being unique to carvone-induced cells. None of the peptides identified had sequences that corresponded to known dioxygenases or other PCB-degrading enzymes of this Gram- positive bacterium, suggesting that the identified induced proteins may be involved in either PCB degradation or adaptive responses that protect cells from toxicity.

Size fractionation and microbial community structure of soil aggregates

The microbial community structure in various microaggregates in a loamy sand soil was investigated. The microaggregates were separated into outer and inner aggregates using a series of soil washes. Further physical fractionation of inner aggregates was achieved by separation into coarse and fine sand as macroaggregate fractions, coarse and fine silt as microaggregate fractions, and clay. Research on microbial communities and soil microaggregates can aid in our understanding of soil microhabitats and microorganisms in soil structures, with applications that may contribute to increasing crop production and maintaining sustainable agriculture. In order to study the microbial community structure of aggregates, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was performed using 16S rRNA genes. The PCR-DGGE of the Bacteria Actinomycetes and Archaea showed divergent results between the different aggregate fractions. The results showed that the bacterial community structure was highly similar between bulk soil and clay;the inner aggregate community structure of Actinomycetes was closely related between coarse and fine sand and coarse silt, and the Archaea community structure of outer and inner aggregates was more similar than that of total bacteria or Actinomycetes.

Characterization and recombinant protein expression of ferritin light chain homologue in the silkworm, Bombyx mori

The silkworm genome encodes three iron storage proteins or ferritins, FerlHCH, Fer2LCH, and Fer3HCH. Probing our EST library constructed from 1-day- old silkworm eggs revealed only Fer2LCH mRNA, which encoded for a protein with a predicted putative N-glycosylation site. Developmental and tissue expression analyses dur- ing embryogenesis revealed that Fer2LCH mRNA was abundant from 6 h to 6 days after oviposition. Transcriptional expression of Fer2LCH during the postembryonic stage is also high in the larval fat body and mid-gut, and then is upregulated in all pupal tissues tested. We found that Fer2LCHmRNA contains an iron-responsive element, suggesting this fer- ritin subunit is subject to translational control. Although ferritin expression has been shown to increase following immune challenge in other insects, the levels of Fer2LCH mRNA were not significantly induced following viral or bacterial infection ofBombyx mori. Using a baculovirus expression system we expressed recombinant BmFer2LCH protein, which was detectable in the cytoplasmic fraction, likely in a compartment of the secretory path- way, and was shown to undergo posttranslational modifications including N-glycosylation. In particular, rBmFer2LCH carbohydrate chains were composed ofmannose and GlcNAc. We suggest that Fer2LCH is important for iron homeostasis and maintaining normal organ function in silkworms.