Decreased expression of VE-cadherin and claudin-5 and increased phosphorylation of VE-cadherin in vascular endothelium in nasal polyps

VE-cadherin and claudin-5 are major components of adherens and tight junctions of vascular endothelial cells and a decrease in their expression and an increase in the tyrosine-phosphorylation of VE-cadherin are associated with an increase in endothelial paracellular permeability. To clarify the mechanism underlying the development of edema in nasal polyps, we studied these molecules in polyp microvessels. Normal inferior turbinate mucosal tissues and nasal polyps from patients treated with or without glucocorticoid were stained for VE-cadherin or claudin-5 and CD31 by a double-immunofluorescence method and the immunofluorescence intensities were graded 1–3 with increasing intensity. To correct for differences in fluorescence intensity attributable to a different endothelial area being exposed in a section or to the thickness of a section, the relative immunofluorescence intensity was estimated by dividing the grade of VE-cadherin or claudin-5 by that of CD31 in each microvessel. Tyrosine-phosphorylation of VE-cadherin was examined by Western blot analysis. The relative intensities of VE-cadherin and claudin-5 in the CD31-positive microvessels significantly decreased in the following order; inferior turbinate mucosa, treated polyps and untreated polyps. The ratio of tyrosine-phosphorylated VE-cadherin to VE-cadherin was significantly higher in untreated polyps than in the inferior turbinate mucosa and treated polyps, between which no significant difference in the ratio was seen. Thus, in nasal polyps, the barrier function of endothelial adherens and tight junctions is weakened, although glucocorticoid treatment improves this weakened barrier function.     

Mitochondria‐type GPAT is required for mitochondrial fusion

Glycerol‐3‐phosphate acyltransferase (GPAT) is involved in the first step in glycerolipid synthesis and is localized in both the endoplasmic reticulum (ER) and mitochondria. To clarify the functional differences between ER‐GPAT and mitochondrial (Mt)‐GPAT, we generated both GPAT mutants in C. elegans and demonstrated that Mt‐GPAT is essential for mitochondrial fusion. Mutation of Mt‐GPAT caused excessive mitochondrial fragmentation. The defect was rescued by injection of lysophosphatidic acid (LPA), a direct product of GPAT, and by inhibition of LPA acyltransferase, both of which lead to accumulation of LPA in the cells. Mitochondrial fragmentation in Mt‐GPAT mutants was also rescued by inhibition of mitochondrial fission protein DRP‐1 and by overexpression of mitochondrial fusion protein FZO‐1/mitofusin, suggesting that the fusion/fission balance is affected by Mt‐GPAT depletion. Mitochondrial fragmentation was also observed in Mt‐GPAT‐depleted HeLa cells. A mitochondrial fusion assay using HeLa cells revealed that Mt‐GPAT depletion impaired mitochondrial fusion process. We postulate from these results that LPA produced by Mt‐GPAT functions not only as a precursor for glycerolipid synthesis but also as an essential factor of mitochondrial fusion.     

Alarm call discrimination in a social rodent: adult but not juvenile degu calls induce high vigilance

Many social animals develop vocal communications to send and receive information efficiently in a group. In alarm communication, call recipients in a social group evaluate alarm calls, enhancing their probability of survival in the face of predatory threats. Calls from naïve and younger group members might be less evocative, in terms of rendering group members vigilant, than calls from more experienced adults because adults are generally more reliable. It remains uncertain, however, what acoustic characteristics render an alarm call reliable. Here, we report that adult degus, Octodon degus (Rodentia, Octodontidae), produced an alarm with a frequency-modulated (FM) syllable, accompanied by low bandwidth and entropy, to evoke a high-vigilance response amongst receivers. Unlike adults, subadult degus did not emit the FM syllable in the warning context, and their call without the FM syllable evoked less vigilance than the adult alarm. We suggest that the FM structure of the adult-produced syllable serves as the primary feature characterizing a reliable alarm call. Our results are consistent with those found in other social rodents, e.g., ground squirrels and gerbils, also produce FM alarm calls in high-urgency situations supports the importance of the FM syllable in alarm communication.     

Involvement of gangliosides in the process of Cbp/PAG phosphorylation by Lyn in developing cerebellar growth cones

The association of gangliosides with specific proteins in the central nervous system was examined by coimmunoprecipitation with an anti‐ganglioside antibody. The monoclonal antibody to the ganglioside GD3 (R24) immunoprecipitated the Csk (C‐terminal src kinase)‐binding protein (Cbp). Sucrose density gradient analysis showed that Cbp of rat cerebellum was detected in detergent‐resistant membrane (DRM) raft fractions. R24 treatment of the rat primary cerebellar cultures induced Lyn activation and tyrosine phosphorylation of Cbp. Treatment with anti‐ganglioside GD1b antibody also induced tyrosine phosphorylation. Furthermore, over‐expressions of Lyn and Cbp in Chinese hamster ovary (CHO) cells resulted in tyrosine 314 phosphorylation of Cbp, which indicates that Cbp is a substrate for Lyn. Immunoblotting analysis showed that the active form of Lyn and the Tyr314‐phosphorylated form of Cbp were highly accumulated in the DRM raft fraction prepared from the developing cerebellum compared with the DRM raft fraction of the adult one. In addition, Lyn and the Tyr314‐phosphorylated Cbp were highly concentrated in the growth cone fraction prepared from the developing cerebellum. Immunoelectron microscopy showed that Cbp and GAP‐43, a growth cone marker, are localized in the same vesicles of the growth cone fraction. These results suggest that Cbp functionally associates with gangliosides on growth cone rafts in developing cerebella.     

Dimorphisms of the proteasome subunit beta type 8 gene (PSMB8) of ectothermic tetrapods originated in multiple independent evolutionary events

The proteasome subunit beta type 8 gene (PSMB8) encodes one of the beta subunits of the immunoproteasome responsible for the generation of peptides presented by major histocompatibility complex class I molecules. Dimorphic alleles of the PSMB8 gene, termed A and F types, based on the deduced 31st amino acid residue of the mature protein have been reported from various vertebrates. Phylogenetic analysis revealed the presence of dichotomous ancient lineages, one comprising the F-type PSMB8 of basal ray-finned fishes, and the other comprising the A-type PSMB8 of these animals and both the F- and A-type PSMB8 of Xenopus and acanthopterygians, indicating that evolutionary history of the PSMB8 dimorphism was not straightforward. We analyzed the PSMB8 gene of five reptile and one amphibian species and found both the A and F types from all six. Phylogenetic analysis indicated that the PSMB8 F type was apparently regenerated from the PSMB8 A type at least five times independently during tetrapod evolution. Genomic typing of wild individuals of geckos and newts indicated that the frequencies of the A- and F-type alleles are not highly biased in these species. Phylogenetic analysis of each exon of the reptile PSMB8 gene suggested interallelic sequence homogenization as a possible evolutionary mechanism for the apparent recurrent regeneration of PSMB8 dimorphism in tetrapods. An extremely strong balancing selection acting on PSMB8 dimorphism was implicated in an unprecedented pattern of allele evolution.     

Vegetation and fire history with their implication for climatic change and fire events since the last deglacial in the Aso Valley, central Kyushu, southwestern Japan: new pollen and charcoal data

To better understand the response of forest vegetation to climate and fire regimes with reference to human activities over the last deglacial period in the Aso Caldera, central Kyushu, southwestern Japan, a 33.9 m long sediment core was examined in order to reconstruct the vegetational and fire history using pollen and charcoal analyses. The results show that a cool temperate broad-leaved deciduous forest, dominated by Quercus (deciduous oaks) with Carpinus and Fagus, prevailed in the Aso Valley from ca. 14.6 ka cal. b.p., indicating warming since the last glacial period. The landscape was presumably covered by a mosaic of deciduous Quercus forests and terrestrial Artemisia communities. Around 12.8–11.7 ka cal. b.p., Quercus dominated the forest and fires occurred frequently. Co-expansion of distinctive Ulmus–Zelkova and Celtis–Aphananthe forests coupled with a progressive retreat of Quercus in the early Holocene could reflect a strengthening of the East Asian summer monsoon under mild and humid climate conditions. Around 8 ka cal. b.p., significant increases in Cyclobalanopsis (evergreen oaks), Castanopsis/Castanea and Podocarpus indicate a further warming, in particular an increased winter temperature. Warm temperate lucidophyllous forests, dominated by Cyclobalanopsis, flourished after 7.3 ka cal. b.p., probably corresponding to the “Holocene Climatic Optimum” interval. Progressive expansion of Quercus at the expense of Cyclobalanopsis began around 6.4 ka cal. b.p. and paralleled an increase in charcoal until ca. 4.8 ka cal. b.p.; this could be evidence of fire disturbance induced by the early-middle Jomon people. The disturbed evergreen forest experienced a temporary recovery but then opened again from 3.6 ka cal. b.p. due to extensive fire deforestation, as suggested by the high charcoal levels during this time. Human exploitation and buckwheat (Fagopyrum) agriculture may have contributed to the opening of the forest, which allowed secondary forests (primarily Pinus and Quercus) and herbaceous communities (mainly Poaceae) to spread. These results are discussed in comparison with other high-resolution pollen data from western Japan to better elucidate the vegetation and fire history over the last deglacial in the Aso Caldera.     

Intermolecular Forces Involved in the Gelation and Gel Stability of Sesame 13S Globulin

The effect of various reagents on the formation and stability of heat-induced gels of sesame 13S globulins were investigated. Electrostatic interaction, the hydrophobic bond and the disulfide bond were important for forming the network structure of gels, and the hydrogen bond also had an influence on the formation of the gel. Hydrophobic bonds mainly contributed to the stability of the gel. Subunit analyses of the proteins solubilized from the gels showed the presence of a free acidic subunit (AS) and basic subunit (BS), a polymer of AS, a dimer of BS and the dimer of a fragment from AS or BS. From the results, sulfhydryl-disulfide exchange reactions during gelation are suggested.     

Glycolipids Isolated from Spirulina maxima: Structure and Fatty Acid Composition

Several glycolipids were isolated from Spirulina maxima, an edible blue-green algae, by systematic fractionation with different solvents. Structural investigation by using methylation, GC-MS, and enzymic techniques indicated that the major glycolipids are O-β-d-galactosyl-(1→l′)-2′, 3′-di-O-acyl-d-glycerol, O-α-d-galactosyl-(l-→6)-O-β-d-galactosyl-(1→l′)-2′,3′-di-O-acyl-d-glycerol and 6-sulfo-O-α-quinovosyl-(l→l′)-2′, 3′-di-O-acyl-d-glycerol. Main fatty acid components of these glycolipids were identified as palmitic acid and linoleic or linolenic acid. Based on-these fatty acid compositions, Spirulina glycolipids were compared with those in higher plants.