Four distinct trimeric forms of light-harvesting complex II isolated from the green alga Chlamydomonas reinhardtii

Photosynthesis Research - Crassulacean acid metabolism (CAM) is a specialized photosynthetic pathway present in a variety of genera including many epiphytic orchids. CAM is under circadian control...     

Comparative characterization of the oah2 gene homologous to the oah1 of Thermus thermophilus HB8

The oah2 gene homologous to the oah1 of Thermus thermophilus HB8 was cloned and sequenced. It comprised 1,236 bp encoding a protein of 412 amino acid residues and was overexpressed. The gene product, also having O-acetyl-L-homoserine sulfhydrylase (EC 4.2.99.10) activity, was purified to homogeneity and characterized comparatively with the oah1 product. The two proteins shared many characteristics.     

Mutations affecting somite formation in the Medaka (Oryzias latipes)

The metameric structure of the vertebrate trunk is generated by repeated formation of somites from the unsegmented presomitic mesoderm (PSM). We report the initial characterization of nine different mutants affecting segmentation that were isolated in a large-scale mutagenesis screen in Medaka (Oryzias latipes). Four mutants were identified that show a complete or partial absence of somites or somite boundaries. In addition, five mutations were found that cause fused somites or somites with irregular sizes and shapes. In situ hybridization analysis using specific markers involved in the segmentation clock and antero-posterior (A-P) polarity of somites revealed that the nine mutants can be compiled into two groups. In group 1, mutants exhibit defects in tailbud formation and PSM prepatterning, whereas A-P identity in the somites is defective in group 2 mutants. Three mutants (planlos, pll; schnelles ende, sne; samidare, sam) have characteristic phenotypes that are similar to those in zebrafish mutants affected in the Delta/Notch signaling pathway. The majority of mutants, however, exhibit somitic phenotypes distinct from those found in zebrafish, such as individually fused somites and irregular somite sizes. Thus, these Medaka mutants can be expected to provide clues to uncovering novel components essential for somitogenesis.     

Carbohydrate structure and differential binding of prostate specific antigen to Maackia amurensis lectin between prostate cancer and benign prostate hypertrophy

Serum prostate-specific antigen (PSA) assay is widely used for detection of prostate cancer. Because PSA is also synthesized from normal prostate, false positive diagnosis cannot be avoided by the conventional serum PSA test. To apply the cancer-associated carbohydrate alteration to the improvement of PSA assay, we first elucidated the structures of PSA purified from human seminal fluid. The predominant core structure of N-glycans of seminal fluid PSA was a complex type biantennary oligosaccharide and was consistent with the structure reported previously. However, we found the sialic acid alpha2-3 galactose linkage as an additional terminal carbohydrate structure on seminal fluid PSA. We then analyzed the carbohydrate moiety of serum PSA from the patients with prostate cancer and benign prostate hypertrophy using lectin affinity chromatography. Lectin binding was assessed by lectin affinity column chromatography followed by determining the amount of total and free PSA. Concanavalin A, Lens culinaris, Aleuria aurantia, Sambucus nigra, and Maackia amurensis lectins were tested for their binding to the carbohydrates on PSA. Among the lectins examined, the M. amurensis agglutinin-bound fraction of free serum PSA is increased in prostate cancer patients compared to benign prostate hypertrophy patients. The binding of PSA to M. amurensis agglutinin, which recognizes alpha2,3-linked sialic acid, was also confirmed by surface plasmon resonance analysis. These results suggest that the differential binding of free serum PSA to M. amurensis agglutinin lectin between prostate cancer and benign prostate hypertrophy could be a potential measure for diagnosis of prostate cancer.     

Unprecedented olefin-dependent histidine-kinase inhibitory of zerumbone ring-opening material

Zerumbone ring-opening derivative, 4 (10E/10Z=3/2), inhibited autophosphorylation of the essential histidine-kinase YycG existing in Bacillus subtilis constituting a two-component system (TCS). Generation of 4E-form could be regulated chemically using the difference from the ring-opening reactivity of the precursor forming of 4 and pure 4E was isolated. The stereoisomer, 4E, showed main inhibition activity of autophosphorylation of YycG (IC(50)=63.5 microM).     

The significant effect of the carbohydrate structures on the DNA photocleavage of the quinoxaline-carbohydrate hybrids

The novel DNA interactive quinoxaline-carbohydrate hybrids possessing disaccharides as the carbohydrate moieties were designed and synthesized, and their DNA photocleaving abilities were evaluated in order to examine the effect of the disaccharide structures. The configurations of the glycosidic bonds in the disaccharide strongly affected the DNA photocleaving ability, and two beta-glycosidic bond linkages were very effective for the DNA photocleavage. Furthermore, the quinoxaline-disaccharide hybrids exhibited selective cytotoxicity against cancer cells with photoirradiation.