Biosynthesis of galactomannans found in filamentous fungi belonging to Pezizomycotina

The galactomannans (GMs) that are produced by filamentous fungi belonging to Pezizomycotina, many of which are pathogenic for animals and plants, are polysaccharides consisting of α-(1→2)-/α-(1→6)-mannosyl and β-(1→5)-/β-(1→6)-galactofuranosyl residues. GMs are located at the outermost layer of the cell wall. When a pathogenic fungus infects a host, its cell surface must be in contact with the host. The GMs on the cell surface may be involved in the infection mechanism of a pathogenic fungus or the defense mechanism of a host. There are two types of GMs in filamentous fungi, fungal-type galactomannans and O-mannose type galactomannans. Recent biochemical and genetic advances have facilitated a better understanding of the biosynthesis of both types. This review summarizes our current information on their biosynthesis.     

PAR‐3 controls endothelial planar polarity and vascular inflammation under laminar flow

Impaired cell polarity is a hallmark of diseased tissue. In the cardiovascular system, laminar blood flow induces endothelial planar cell polarity, represented by elongated cell shape and asymmetric distribution of intracellular organelles along the axis of blood flow. Disrupted endothelial planar polarity is considered to be pro‐inflammatory, suggesting that the establishment of endothelial polarity elicits an anti‐inflammatory response. However, a causative relationship between polarity and inflammatory responses has not been firmly established. Here, we find that a cell polarity protein, PAR‐3, is an essential gatekeeper of GSK3β activity in response to laminar blood flow. We show that flow‐induced spatial distribution of PAR‐3/aPKCλ and aPKCλ/GSK3β complexes controls local GSK3β activity and thereby regulates endothelial planar polarity. The spatial information for GSK3β activation is essential for flow‐dependent polarity to the flow axis, but is not necessary for flow‐induced anti‐inflammatory response. Our results shed light on a novel relationship between endothelial polarity and vascular homeostasis highlighting avenues for novel therapeutic strategies.     

Predation by a photosynthetic dinoflagellate Gyrodinium instriatum on loricated ciliates

Feeding of a naked photosynthetic dinoflagellate, Gyrodiniuminstriatum, on loricated ciliates was investigated. Gyrodiniuminstriatum preyed on Favella azorica and Eutintinnus tubulosusby engulfment through the posterior end of the sulcus. In thecase of E.tubulosus, G.instriatum preyed on this small ciliatekeeping the original gymnodinioid cell shape. On the other hand,G.instriatum preyed on Favella taraikaensis by absorbing thecell contents of this large ciliate, which resulted in a balloonlike inflation of its body size. It seemed that G.instriatumcan change its feeding style according to the size of prey.Thus, the present study shows, by using direct observationson the feeding of G.instriatum on loricated ciliates, a reversalof energy flow processes in the food chain in which photosyntheticorganisms eat primary consumers. The growth of G.instriatumafter feeding on F.taraikaensis and E.tubulosus is also describedbriefly.     

Large-scale EST sequencing in rice

Large-scale cDNA analysis provides several great advantages for genome investigations in rice. Isolated and partially characterized cDNA clones have contributed not only to the construction of an RFLP linkage map and physical maps of the chromosomes but also to investigations of the mechanisms of expression of various isozymes and family genes. The ultimate aim of our large-scale cDNA analysis is to catalogue all the expressed genes of this important cereal, including tissue-specific, developmental stage-specific, and stress-specific genes. As of August 1996, the Rice Genome Research Program (RGP) has isolated and partially sequenced more than 29000 cDNA clones from various tissues and calluses in rice (Nipponbare, a japonica variety). The sequence data were translated into amino acid sequences for the 3 possible reading frames, and the similarity of these amino acid sequences to known proteins registered in PIR were examined. About 25% of the clones had significant similarities to known proteins. Some of the hit clones showed library-specific distributions, indicating that the composition of the clones in each library reflects, to some extent, the regulation of gene expression specific to differentiation, growth condition, or environmental stress. To further characterize the cDNA clones, including unknown clones, nucleotide sequence similarities of 24728 clones were analyzed and the clones were classified into around 10000 independent groups, suggesting that around a half or one third of expressed genes in rice have already been captured. These results obtained from our large-scale cDNA analysis provide useful information related to gene expression and regulation in rice.     

Development of an ON/OFF switchable fluorescent probe targeting His tag fused proteins in living cells

The fluorescent labeling of target proteins is useful for analyzing their functions and localization in cells, and several fluorescent probes have been developed. However, the fusion of tags such as green fluorescent protein (GFP) to target proteins occasionally affects their functions and/or localization in living cells. Therefore, an imaging method that uses short peptide tags such as hexa-histidine (the His tag) has been attracting increasing attention. Few studies have investigated ON/OFF switchable fluorescent probes for intracellular His-tagged proteins. We herein developed a novel ON/OFF switchable probe for imaging targeted intracellular proteins fused with a CH6 tag, which is composed of one cysteine residue and six histidine residues.     

Changes in biosynthesis of exopolysaccharide in Lactococcus lactis subspecies cremoris treated by moderate pulsed electric field treatment

Metabolome analysis and physicochemical analyses were executed with cell extracts of a Lactococcus lactis subspecies cremoris strain treated by moderate pulsed electric field (PEF) to elucidate the mechanism of enhanced production of exopolysaccharide (EPS) by the treatment. Metabolome analysis by capillary electrophoresis time of flight mass spectrometry annotated 224 metabolites from the cytoplasmic extract of the strain, which, however, showed no significant changes in metabolites related to the EPS production. Electron microscopic observation and chemical analysis of undecaprenoids as carrier of EPS biosynthetic intermediates suggested that PEF treatment dissociated immature EPSs from the intermediates due to the focal electro-condensation of hydrogen ions at the cell surface. Thus, liberated undecaprenyl phosphates were recycled efficiently, which resulted in mass increase of EPS with smaller molecular weight. The study suggested the feasibility of moderate PEF treatment as a food processing technique and revealed the mechanism of enhanced production of EPS by the treatment.     

Soybean Seed Extracts Preferentially Express Genomic Loci of Bradyrhizobium japonicum in the Initial Interaction with Soybean, Glycine max (L.) Merr

Initial interaction between rhizobia and legumes actually starts via encounters of both partners in the rhizosphere. In this study, the global expression profiles of Bradyrhizobium japonicum USDA 110 in response to soybean (Glycine max) seed extracts (SSE) and genistein, a major soybean-released isoflavone for nod genes induction of B. japonicum, were compared. SSE induced many genomic loci as compared with genistein (5.0 µM), nevertheless SSE-supplemented medium contained 4.7 µM genistein. SSE markedly induced four predominant genomic regions within a large symbiosis island (681 kb), which include tts genes (type III secretion system) and various nod genes. In addition, SSE-treated cells expressed many genomic loci containing genes for polygalacturonase (cell-wall degradation), exopolysaccharide synthesis, 1-aminocyclopropane-1-carboxylate deaminase, ribosome proteins family and energy metabolism even outside symbiosis island. On the other hand, genistein-treated cells exclusively showed one expression cluster including common nod gene operon within symbiosis island and six expression loci including multidrug resistance, which were shared with SSE-treated cells. Twelve putatively regulated genes were indeed validated by quantitative RT-PCR. Several SSE-induced genomic loci likely participate in the initial interaction with legumes. Thus, these results can provide a basic knowledge for screening novel genes relevant to the B. japonicum- soybean symbiosis.Key words: soybean seed extracts, Bradyrhizobium japonicum, expression clusters, genistein, symbiosis     

Phylogenetic relationships of subgenera of the genus Exorista Meigen,with a revision of the Japanese species (Diptera: Tachinidae)

Phylogenetic relationships of the subgenera of Exorista Meigen (Diptera: Tachinidae) are inferred from morphological data. Our results show that the genus Exorista is not monophyletic and that members of the subgenus Spixomyia Crosskey are divided into two clades. Each subgenus is redefined based on male and female morphological features. The Japanese species of Exorista are revised and classified into five subgenera: Adenia Robineau‐Desvoidy, Exorista Meigen, Podotachina Brauer and Bergenstamm, Ptilotachina Brauer and Bergenstamm, and Spixomyia Crosskey. Thirteen species are recognized, including two newly recorded species, Exorista (Adenia) cuneata Herting and Exorista (Spixomyia) lepis Chao. Exorista cantans Mesnil is transferred to the subgenus Podotachina from Spixomyia.     

Improvement of the transactivation activity of phenylpropanoic acid-type peroxisome proliferator-activated receptor pan agonists: effect of introduction of fluorine at the linker part

We developed a potent peroxisome proliferator-activated receptor pan agonist (a candidate drug for treatment of altered metabolic homeostasis) by introducing fluorine atoms at appropriate position(s) of the known phenylpropionic acid-type pan agonist TIPP-703.