Distribution of the freshwater fishes of Japan: an historical overview

Japanese freshwater fishes, including lampreys, comprise 15 orders, 35 families, and 96 genera, with 211 species and subspecies. Most belong to the families Cyprinidae (29% of species and subspecies), Gobiidae (21%), Salmonidae (10%), and Cobitidae (8%). Cyprinids and cobitids presumably originated from east Asia, gobiids from southeast Asia, and cottids and salmonids from the north Pacific. Japanese freshwater fishes include 88 endemic species and subspecies, of which three have been extirpated. Fishes introduced into natural rivers and lakes for inland commercial fisheries and sport fishing, and by accident, include many exotic species, of which 23 now inhabit natural freshwaters. These often have destroyed the local fish fauna by predation, and caused genetic pollution by hybridization with local strains. Destruction of freshwater environments by land development also poses a threat to Japanese freshwater fish communities. In addition Japanese freshwater systems have been markedly altered by development of rice paddy fields which have caused some species to decline but others to flourish, and changed the distribution patterns of fishes between upstream and downstream areas. To conserve endangered species and declining communities of Japanese freshwater fishes, we need to clarify the characteristics of their original habitats and the effects of developing paddy fields, from both the ecological and historical points of view.     

Domain architecture of vasohibins required for their chaperone‐dependent unconventional extracellular release

Vasohibins (VASH1 and VASH2) are recently identified regulators of angiogenesis and cancer cell functions. They are secreted proteins without any classical secretion signal sequences, and are thought to be secreted instead via an unconventional protein secretion (UPS) pathway in a small vasohibin‐binding protein (SVBP)‐dependent manner. However, the precise mechanism of SVBP‐dependent UPS is poorly understood. In this study, we identified a novel UPS regulatory system in which essential domain architecture (VASH‐PS) of VASHs, comprising regions VASH1_91–180 and VASH2_80–169, regulate the cytosolic punctate structure formation in the absence of SVBP. We also demonstrate that SVBP form a complex with VASH1 through the VASH1_274–282 (SIa), VASH1_139‐144 (SIb), and VASH1_133–137 (SIc), leading to the dispersion in the cytosol and extracellular release of VASH1. The amino acid sequences of VASH‐SIa and VASH‐PS, containing SIb and SIc, are highly conserved among VASH family members in vertebrates, suggesting that SVBP‐dependent UPS may be common within the VASH family. This novel UPS regulatory system may open up new avenues for understanding fundamental protein secretion in vertebrates.     

A familial case of visceral toxocariasis due to consumption of raw bovine liver

We present 3 adult cases of visceral toxocariasis from the same family, who each consumed thin slices of raw bovine liver weekly, and developed eosinophilia and multiple small lesions in their livers and lungs. Serological examinations using the larval excretory–secretory product of Toxocara canis strongly indicated infection with Toxocara species larvae. The patients responded well to treatment with albendazole. Ingestion of raw liver from paratenic animals is considered to be a common transmission route of human toxocariasis, especially in adults.     

Regulation of VEGF-mediated angiogenesis by the Akt/PKB substrate Girdin

The serine/threonine protein kinase Akt is involved in a variety of cellular processes including cell proliferation, survival, metabolism and gene expression. It is essential in vascular endothelial growth factor (VEGF)-mediated angiogenesis; however, it is not known how Akt regulates the migration of endothelial cells, a crucial process for vessel sprouting, branching and the formation of networks during angiogenesis. Here we report that Akt-mediated phosphorylation of Girdin, an actin-binding protein, promotes VEGF-dependent migration of endothelial cells and tube formation by these cells. We found that exogenously delivered adenovirus harbouring Girdin short interfering RNA in Matrigel embedded in mice, markedly inhibited VEGF-mediated angiogenesis. Targeted disruption of the Girdin gene in mice impaired vessel remodelling in the retina and angiogenesis from aortic rings, whereas Girdin was dispensable for embryonic vasculogenesis. These findings demonstrate that the Akt/Girdin signalling pathway is essential in VEGF-mediated postneonatal angiogenesis.     

Effect of inorganic polyphosphate in periodontitis in the elderly

Aim: Inorganic polyphosphate exists as chains of phosphate molecules and is distributed in osteoblasts, and regulates osteoblastic cell differentiation and bone matrix calcification. The purpose of this study was to clarify the effects of inorganic polyphosphate on periodontitis. Material and methods: Subgingival local irrigation with inorganic polyphosphate was studied in a randomised double‐blind study of 33 patients with periodontitis. Scaling and root planing were performed 1 week after the initial examination. Results: No significant differences between the inorganic polyphosphate group and control were detected in each item except IL‐1β. Patients in whom both the bleeding on probing and gingival index at 1 week had improved were significantly older in the inorganic polyphosphate group than in the control group (p < 0.05). Bone regeneration was seen in one case of the inorganic polyphosphate group. Conclusions: Inorganic polyphosphate was useful in the treatment of periodontitis in the elderly, indicating a probable effect of anti‐ageing, with similar bone regenerations occurring in both groups.     

Atg26-Mediated Pexophagy Is Required for Host Invasion by the Plant Pathogenic Fungus Colletotrichum orbiculare

The number of peroxisomes in a cell can change rapidly in response to changing environmental and physiological conditions. Pexophagy, a type of selective autophagy, is involved in peroxisome degradation, but its physiological role remains to be clarified. Here, we report that cells of the cucumber anthracnose fungus Colletotrichum orbiculare undergo peroxisome degradation as they infect host plants. We performed a random insertional mutagenesis screen to identify genes involved in cucumber pathogenesis by C. orbiculare. In this screen, we isolated a homolog of Pichia pastoris ATG26, which encodes a sterol glucosyltransferase that enhances pexophagy in this methylotrophic yeast. The C. orbiculare atg26 mutant developed appressoria but exhibited a specific defect in the subsequent host invasion step, implying a relationship between pexophagy and fungal phytopathogenicity. Consistent with this, its peroxisomes are degraded inside vacuoles, accompanied by the formation of autophagosomes during infection-related morphogenesis. The autophagic degradation of peroxisomes was significantly delayed in the appressoria of the atg26 mutant. Functional domain analysis of Atg26 suggested that both the phosphoinositide binding domain and the catalytic domain are required for pexophagy and pathogenicity. In contrast with the atg26 mutant, which is able to form appressoria, the atg8 mutant, which is defective in the entire autophagic pathway, cannot form normal appressoria in the earlier steps of morphogenesis. These results indicate a specific function for Atg26-enhanced pexophagy during host invasion by C. orbiculare.     

Amphiregulin regulates the production of human chorionic gonadotropin in trophoblasts

AimsThe aim of this study was to investigate the significance of epidermal growth factor receptor (EGFR) ligands produced in syncytiotrophoblasts during normal pregnancy.Main methodsWe examined the expression of EGFR ligands in human pregnancy by real-time PCR, and analyzed the relationship between EGFR ligands and human chorionic gonadotropin (hCG) or human placental lactogen in amniotic fluid by ELISA. In addition, we also examined the EGFR ligands in syncytiotrophoblasts and the amount of hCG secretion in JAR, JEG3 and BeWo cells in the presence of each EGFR ligand.Key findingsIn order to identify possible candidates among the EGFR ligands, we examined the predominant expression of an EGFR ligand in the chorionic villi and amniotic fluid during normal pregnancy, and analyzed the relationship between EGFR ligands and hCG in trophoblastic model cells. Amphiregulin was primarily expressed throughout human pregnancy and stimulated the secretion of hCG, indicating that amphiregulin is a key molecule among EGFR ligands.SignificanceAmphiregulin may play a pivotal role in the development or maturation of placenta.