Fucoxanthin, a main marine carotenoid, in five species of fucoxanthin-containing microalgae, was quantified by highperformance liquid chromatography. Among the studied species, Isochrysis aff. galbana contained the highest amount of fucoxanthin (18.23 mg/g dried sample). This microalga showed good fucoxanthin extraction efficiency under the tested solvents (methanol, ethanol, acetone, and ethyl acetate), with the exception of n-hexane. In addition, most fucoxanthin (~95%) could be extracted by a single extraction in ethanol within 5 min, and only 15% degradation of fucoxanthin was detected during ethanol extraction for 24 h. The two-phase solvent system of n-hexaneethanol-water with a volume ratio of 10:9:1 was determined to be the best system for the separation of fucoxanthin and lipids from extracts of I. aff. galbana. Under these conditions, fucoxanthin was fractionated in the hydroalcohol phase apart from the hexane phase containing lipids. These results imply that I. aff. galbana can be a commercial source for the spontaneous production of valuable fucoxanthins and lipids.

The acaricidal activity of materials derived from the roots of Ostericum koreanum (Apiaceae) toward adults of Dermatophagoides farinae and Dermatophagoides pteronyssinus was examined by direct contact and vapor phase toxicity bioassays. Results were compared with those of three acaricides: benzyl benzoate, dibutyl phthalate, and N,N-diethyl-m-toluamide (DEET). The active principle was identified as the sesquiterpenoid bisabolangelone by spectroscopic analysis. In fabric-piece contact toxicity bioassays using adult D. farinae, bisabolangelone (1.88 microg/cm2) was more toxic than benzyl benzoate (11.91 microg/cm2), DEET (62.20 microg/cm2), or dibutyl phthalate (79.54 microg/cm2), based on 24-h LD50 values. Against adult D. pteronyssinus, bisabolangelone (1.79 microg/cm2) was similarly more active than benzyl benzoate (9.65 microg/cm2), DEET (64.45 microg/cm2), and dibutyl phthalate (77.79 microg/cm2). In vapor phase toxicity tests with both mite species, bisabolangelone was equitoxic in closed versus open containers. These results indicate that bisabolangelone was largely toxic through contact action. Bisabolangelone merits further study as a potential contact acaricide or lead for the control of house dust mites.

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Legume-Rhizobium spp. symbiosis requires signaling between the symbiotic partners and differential expression of plant genes during nodule development. Previously, we cloned a gene encoding a putative b-carotene hydroxylase (GmBCH1) from soybean (Glycine max) whose expression increased during nodulation with Bradyrhizobium japonicum. In this work, we extended our study to three GmBCHs to examine their possible role(s) in nodule development, as they were additionally identified as nodule specific, along with the completion of the soybean genome. In situ hybridization revealed the expression of three GmBCHs (GmBCH1, GmBCH2, and GmBCH3) in the infected cells of root nodules, and their enzymatic activities were confirmed by functional assays in Escherichia coli. Localization of GmBCHs by transfecting Arabidopsis (Arabidopsis thaliana) protoplasts with green fluorescent protein fusions and by electron microscopic immunogold detection in soybean nodules indicated that GmBCH2 and GmBCH3 were present in plastids, while GmBCH1 appeared to be cytosolic. RNA interference of the GmBCHs severely impaired nitrogen fixation as well as nodule development. Surprisingly, we failed to detect zeaxanthin, a product of GmBCH, or any other carotenoids in nodules. Therefore, we examined the possibility that most of the carotenoids in nodules are converted or cleaved to other compounds. We detected the expression of some carotenoid cleavage dioxygenases (GmCCDs) in wild-type nodules and also a reduced amount of zeaxanthin in GmCCD8-expressing E. coli, suggesting cleavage of the carotenoid. In view of these findings, we propose that carotenoids such as zeaxanthin synthesized in root nodules are cleaved by GmCCDs, and we discuss the possible roles of the carotenoid cleavage products in nodulation.

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