Site‐specific profiles of biochemical properties in the larval digestive tract of Japanese rhinoceros beetle,Trypoxylus dichotomus (Coleoptera: Scarabaeidae)

The larvae of Japanese rhinoceros beetle, Trypoxylus dichotomus, feed on dead plant material in forest soils that are derived from fallen leaves broken down by basidiomycete fungi. Our previous work provided an understanding of the degradation of polysaccharides in dead plant material by T. dichotomus larvae and reported the complexity of the physicochemical and biochemical environment of the larval gut. Here, we examined ten divisions of the digestive tract of T. dichotomus larvae for physicochemical and biochemical conditions to elucidate site‐specifically functional properties along the tract. The distribution of potassium ions, pH, and acetic acid differed markedly along the length of the digestive tract with the potassium ion concentration profile closely reflecting that of pH along the length of the digestive tract. Distinct physicochemical environments were maintained in the digestive tract along with site‐specific polysaccharide degradation. Based on these findings, we suggest that there are metabolic relationships between the activities of the enzymes involved in polysaccharide degradation, the presence of intermediate metabolites and location along the digestive tract. Furthermore, we revealed that the anterior region of the gut plays an important role in the degradation of polysaccharides in the digestive tract of T. dichotomus larvae.     

Contribution of Zinc Deficiency to Insulin Resistance in Patients with Primary Biliary Cirrhosis

The relationship between metabolic abnormalities of trace elements and insulin resistance has been established. Recent studies have revealed that insulin resistance is associated with autoimmune responses. The purpose of this study was to examine the correlation between zinc or copper metabolism and insulin resistance in patients with primary biliary cirrhosis (PBC). Sixteen patients with PBC were divided into two groups: early and advanced stage disease. The overall value of the homeostasis model assessment of insulin resistance (HOMA-IR) in patients with advanced stage PBC was significantly higher than that in patients with early stage PBC, although the mean value in advanced stage PBC was significantly lower than that in hepatitis C virus (HCV)-related liver cirrhosis. There was an inverse correlation between serum zinc concentrations and HOMA-IR values in patients with PBC, while we found no correlation between serum copper levels and HOMA-IR values. HOMA-IR values were inversely associated with peripheral platelet counts, indicating the relationship between insulin resistance and hepatic fibrosis. These results suggest that zinc deficiency plays important roles of insulin resistance and subsequent hepatic fibrosis in patients with PBC, although insulin resistance in advanced stage PBC was significantly milder than that in HCV-related liver cirrhosis.     

Enzymatic properties of the recombinant serine-type carboxypeptidase OcpC, which is unique to Aspergillus oryzae

Gene AO090103000153 is unique to Aspergillus oryzae RIB40 and A. flavus NRRL3357, and is speculated to encode a serine-type carboxypeptidase. In this study, we purified and characterized a heterologously expressed gene product of AO090103000153. 5'-Rapid amplification of cDNA ends indicated that the translation start site of the gene is located 1,586 bp downstream of the translation start site predicted by the genome sequencing project. The gene, starting from the revised translation start codon, termed ocpC, was transcribed constantly in A. oryzae RIB40. Purified recombinant OcpC exhibited the enzymatic properties of a serine-type carboxypeptidase. This protease was stable at temperatures below 45°C and a low pH, and had broad substrate specificity for N-acylpeptides, but it exhibited significantly lower specific activity and a lower k(cat) value for substrates than previously reported serine-type carboxypeptidases from A. oryzae.     

Primary and secondary CoQ(10) deficiencies in humans

CoQ(10) deficiencies are clinically and genetically heterogeneous. This syndrome has been associated with five major clinical phenotypes: (1) encephalomyopathy, (2) severe infantile multisystemic disease, (3) cerebellar ataxia, (4) isolated myopathy, and (5) nephrotic syndrome. In a few patients, pathogenic mutations have been identified in genes involved in the biosynthesis of CoQ(10) (primary CoQ(10) deficiencies) or in genes not directly related to CoQ(10) biosynthesis (secondary CoQ(10) deficiencies). Respiratory chain defects, ROS production, and apoptosis variably contribute to the pathogenesis of primary CoQ(10) deficiencies.     

Effect of oral intake of winged bean extract on a skin lichenification model: evaluation by microarray analysis

Winged bean (WB), Psophocarpus tetragonolobus, is a tropical legume, the potential of which is not fully understood. We found that 5-week oral administration of a WB seed extract inhibited wrinkle formation induced by repeated tape stripping (TS) as a model of lichenification in human chronic eczematous dermatitis. To elucidate the mechanism of the effect of WB on this model, we applied microarray analysis. Hierarchical clustering revealed that each experimental group formed a distinct cluster, suggesting the presence of a distinct gene expression profile among the three groups of non-TS, TS, and TS with oral administration of WB extract (TS/WB). Gene ontology analysis showed that several gene groups with keratinization and mitosis were significantly upregulated by TS, while other groups with ATP synthesis and glycolysis were significantly downregulated by TS/WB. Moreover, WB extract influenced a number of genes related to epidermal differentiation and inflammation. This suggests that these changes inhibited wrinkle formation by TS.     

Docosahexaenoic acid withstands the Aβ25-35-induced neurotoxicity in SH-SY5Y cells

Background

Docosahexaenoic acid (DHA, C22:6, n-3) ameliorates the memory-related learning deficits of Alzheimer's disease (AD), which is characterized by fibrillar amyloid deposits in the affected brains. Here, we have investigated whether DHA-induced inhibition of Amyloid β-peptide_25-35 (Aβ_25-35) fibrillation limits or deteriorates the toxicity of the human neuroblastoma cells (SH-SY5Y).

Experimental methods

In vitro fibrillation of Aβ_25-35 was performed in the absence or presence of DHA. Afterwards, SH-SY5Y cells were incubated with Aβ_25-35 in absence or presence 20 μM DHA to evaluate its effect on the Aβ_25-35-induced neurotoxicity by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)]-redox and TUNEL (TdT-mediated dUTP-biotin nick end-labeling) assay and immunohistochemistry. The level of Aβ_25-35-induced lipid peroxide (LPO) was determined in the absence or presence of oligomer-specific antibody. Fatty acid profile was estimated by gas chromatography.

Results

DHA significantly reduced the Aβ_25-35 in vitro fibrillation, as indicated by fluorospectroscopy and transmission electron microscopy. Aβ_25-35 decreased the MTT-redox activity and increased the apoptotic damage and levels of LPO when compared with those of the controls. However, when the SH-SY5Y cells were treated with Aβ_25-35 in the presence of DHA, MTT redox potential significantly increased and the levels LPO decreased, suggesting an inhibition of the Aβ_25-35-induced neurotoxity. DHA improved the Aβ_25-35 induced DNA damage and axodendritic loss, with a concomitant increase in the cellular level of DHA, suggesting DHA protects the cell from neurotoxic degeneration.

Conclusion

DHA not only inhibits the in vitro fibrillation but also resists the Aβ_25-35-induced toxicity in the neuronal cells. This might be the basis of the DHA-induced amelioration of Aβ-induced neurodegeneration and related cognitive deficits.     

Tissue-autonomous promotion of palisade cell development by phototropin 2 in Arabidopsis

Light is an important environmental information source that plants use to modify their growth and development. Palisade parenchyma cells in leaves develop cylindrical shapes in response to blue light; however, the photosensory mechanism for this response has not been elucidated. In this study, we analyzed the palisade cell response in phototropin-deficient mutants. First, we found that two different light-sensing mechanisms contributed to the response in different proportions depending on the light intensity. One response observed under lower intensities of blue light was mediated exclusively by a blue light photoreceptor, phototropin 2 (PHOT2). Another response was elicited under higher intensities of light in a phototropin-independent manner. To determine the tissue in which PHOT2 perceives the light stimulus to regulate the response, green fluorescent protein (GFP)-tagged PHOT2 (P2G) was expressed under the control of tissue-specific promoters in the phot1 phot2 mutant background. The results revealed that the expression of P2G in the mesophyll, but not in the epidermis, promoted palisade cell development. Furthermore, a constitutively active C-terminal kinase fragment of PHOT2 fused to GFP (P2CG) promoted the development of cylindrical palisade cells in the proper direction without the directional cue provided by light. Hence, in response to blue light, PHOT2 promotes the development of cylindrical palisade cells along a predetermined axis in a tissue-autonomous manner.     

Acrolein,an Environmental Toxin,Induces Cardiomyocyte Apoptosis via Elevated Intracellular Calcium and Free Radicals

Acrolein, an unsaturated aldehyde, is an environmental toxin known to inhibit mitochondrial electron transport chain in brain and induce lipid peroxidation and apoptosis. However, the nature of the effects of acrolein on cardiac function and myocardium is not known. The objective of this study is to examine whether acrolein induces apoptosis in cardiomyocytes and alters cytosolic calcium concentration and the intracellular oxygen free-radical levels. Adult mouse cardiomyocytes exposed to 1 μmol/l of acrolein showed a marked increase in the intracellular oxygen free-radicals and calcium concentration, by 12- and 2-fold, respectively, compared to the resting value. Moreover, the cardiomyocyte viability decreased significantly in a dose-dependent manner by treatment with 25, 50, and 100 μmol/l of acrolein compared to controls. Morphological changes and DNA laddering typical of apoptosis were found in acrolein-exposed cardiomyocytes. Our finding suggested that acrolein caused apoptotic death of adult mice cardiomyocytes by increasing intracellular oxygen free-radicals and calcium concentration.