Taxonomic and life cycle reappraisals of the marine basidiomycete Nia vibrissa complex, with descriptions of three new Nia species.

The marine basidiomycete Nia vibrissa has been regarded as a species complex, possibly including several species, because morphological variations in fruitbody, spore, and spore appendage have been observed in materials from worldwide collections. Using more than 50 monosporic isolates of N. vibrissa-like fungi mainly obtained from Japanese beach coasts, we investigated their molecular phylogeny, morphological characteristics, mating compatibility, nuclear behavior during spore formation, and life cycles. Molecular phylogenetic analyses separated the examined strains into seven clades. Each clade of fungi exhibited distinctive characteristics in fruitbodies and spores produced by culturing monokaryotic strains and mated dikaryotic strains; these characteristics included the color of fruitbodies, apical structure of peridial hair hyphae, spore shape, and apical structure of spore appendages. Mating tests of monokaryotic strains demonstrated mating compatibility between strains within a clade and incompatibility among clades. Therefore, each clade of fungi was phylogenetically, morphologically, and biologically recognized as a different Nia species. Observation of the type specimen of N. vibrissa revealed a tiny T-shaped apical structure of spore appendages-not mentioned in the original description-that is unique to the species. This finding, together with the original description, suggests that our studied strains include N. aff. vibrissa, whose morphology is mostly identical to N. vibrissa sensu stricto, and three new species. Thus, we describe three new Nia species and propose emendation of the descriptions of the genus Nia. Culture-based studies have demonstrated that Nia species have both sexual and asexual morphs that produce morphologically similar fruitbodies (basidiomata and conidiomata) and spores (basidiospores and conidia). Because it has both morphs forming appendaged waterborne basidiospores and conidia, Nia must be the most well-adapted marine basidiomycete, ensuring the continuation of new generations by two morphs, while distributing in and inhabiting numerous marine environments.

New teleomorph combinations in the entomopathogenic genus Metacordyceps.

The genus Metacordyceps contains arthropod pathogens in Clavicipitaceae (Hypocreales) that formerly were classified in Cordyceps sensu Kobayasi et Mains. Of the current arthropod pathogenic genera of Hypocreales, the genus Metacordyceps remains one of the most poorly understood and contains a number of teleomorphic morphologies convergent with species of Cordyceps s.s. (Cordycipitaceae) and Ophiocordyceps (Ophiocordycipitaceae). Of note, the anamorph genera Metarhizium and Pochonia were found to be associated only with Metacordyceps and demonstrated to be phylogenetically informative for the clade. Several species of Cordyceps considered to have uncertain placements (incertae sedis) in the current taxonomic framework of clavicipitoid fungi were collected during field expeditions mostly in eastern Asia. Species reclassified here in Metacordyceps include Cordyceps atrovirens Kobayasi & Shimizu, Cordyceps indigotica Kobayasi & Shimizu, Cordyceps khaoyaiensis Hywel-Jones, Cordyceps kusanagiensis Kobayasi & Shimizu, Cordyceps martialis Speg., Ophiocordyceps owariensis Kobayasi, Cordyceps pseudoatrovirens Kobayasi & Shimizu and Ophicordyceps owariensis f. viridescens (Uchiy. & Udagawa) G.H. Sung, J.M. Sung, Hywel-Jones & Spatafora. Incorporation of these species in a multigene phylogenetic framework of the major clades of clavicipitoid fungi more than doubled the number of species in Metacordyceps and allowed for refinement of morphological concepts for the genus consistent with the phylogenetic structure. Based on these findings we then discuss evolution of this genus, subgeneric relationships, anamorph connections, and suggest additional species that should be confirmed for possible inclusion in Metacordyceps.

Evidence for the involvement of NADPH oxidase in ischemia/reperfusion-induced gastric damage via angiotensin II.

Reactive oxygen species are known to be derived from NADPH oxidase in several tissues. Angiotensin II was suggested to be involved in the activation of NADPH oxidase; however, its role in the gastric mucosa is unclear. We examined the roles of angiotensin II receptor and NADPH oxidase in ischemia/reperfusion-induced gastric damage in rats. Under urethane anesthesia, male Sprague-Dawley rat stomachs were mounted in an ex-vivo chamber, had 100 mM HCl applied to them, and then a catheter was passed through the femoral vein. Ischemia/reperfusion was accompanied by blood collection and reperfusion through the catheter. Losartan, candesartan, valsartan, which are AT1 receptor blockers (ARB); PD123319, an AT2 receptor blocker; enalapril, an ACE inhibitor; or diphenylene iodonium, a NADPH oxidase inhibitor, was given i.v. 10 mins, and beta-NADPH, a NADPH oxidase substrate, was given i.v. 5 mins before reperfusion. The gastric damage by ischemia/reperfusion was attenuated by treatment with any of ARB or enalapril, but was not affected by PD123319. The increase in gastric H(2)O(2) production and microvascular permeability by ischemia/reperfusion was also suppressed by treatment with any of ARB or enalapril. In rat gastric mucosa, the NADPH oxidase subunit p47(phox) was detected. Additionally, diphenylene iodonium had similar effects to ARB against ischemia/reperfusion-caused gastric damage, increased H(2)O(2) production, and microvascular permeability. Ischemia/reperfusion activated NADPH oxidase in the gastric mucosa, and the activation was significantly attenuated by treatment with losartan or diphenylene iodonium. These results suggest that ischemia/reperfusion generated reactive oxygen species are derived from NADPH oxidase activation via AT1 receptor in rat stomachs.

Prophylactic effect of lafutidine against the adverse reaction induced in rat stomach by repeated administration of 5-fluorouracil.

We examined the prophylactic effect of lafutidine, a histamine H2 receptor antagonist, on the morphological and functional derangement of the rat stomach after the administration of 5-fluorouracil (5-FU) in the absence or presence of taurocholate Na (TC). Rats were given 5-FU p. o. once daily for 5 days. After 18 hr fasting, the animals were given omeprazole to inhibit acid secretion. Under urethane anesthesia, the stomach was mounted on an ex-vivo chamber, perfused with 100 mM HCl, and both the transmucosal potential difference (PD) and gastric mucosal blood flow (GMBF) were simultaneously measured before and after exposure of the mucosa to 20 mM TC for 30 min. The 5-FU treatment lowered the basal PD with a decrease in the mucosal height and caused few haemorrhagic lesions in the stomach when perfused with 100 mM HCl for 2 hr. The 5-FU treatment had no influence on the reduced PD response caused by TC, but significantly impaired the increase in GMBF after exposure to TC, resulting a marked aggravation of gastric lesions. Lafutidine, given together with 5-FU for 5 days, significantly antagonized the deleterious effect of 5-FU on the basal PD and the GMBF response to TC, and prevented the aggravation of gastric lesions. These effects of lafutidine were not mimicked by cimetidine and disappeared due to the chemical ablation of capsaicin-sensitive afferent neurons. We conclude that 1) 5-FU treatment caused the morphological and functional derangement of the stomach and increased the mucosal vulnerability against acid, and 2) lafutidine prevents such changes caused by 5-FU treatment, probably mediated through capsaicin-sensitive afferent neurons.

Angiotensin AT1 receptor blockers suppress ischemia/reperfusion-induced gastric injury in rats.

Ischemia/reperfusion (I/R) damages gastric mucosa via reactive oxygen species (ROS) activity. ROS was reportedly produced through angiotensin II stimulation in tissues such as kidney, heart and brain. To determine whether AT1 receptor plays a role in gastric mucosal damage, we examined the effect of AT1 receptor blocker (ARB; losartan, candesartan, valsartan) on I/R-induced gastric injury in rats. I/R produced microscopic gastric hemorrhagic injury, and increased gastric microvascular permeability and H(2)O(2) production in rats. The mucosal lesions induced by I/R were attenuated by pretreatment of each ARB. The increase in microvascular permeability was suppressed by losartan pretreatment. Additionally, I/R-caused H(2)O(2) activation was not observed by pretreatment of losartan, candesartan and valsartan. These results suggest that angiotensin II stimulation via AT1 receptor and following ROS production in the stomach contribute to the pathogenesis of the gastric I/R injury.

NADPH oxidase is involved in ischaemia/reperfusion-induced damage in rat gastric mucosa via ROS production--role of NADPH oxidase in rat stomachs.

In the process of the oxygen reduction, NADPH oxidase is the enzyme that produces superoxide anion, which subsequently produces reactive oxygen species (ROS) and causes damage in various tissues and microorganisms. NADPH oxidase is demonstrated to exist in several types of cells such as endothelial cells and vascular smooth muscle cells. In the present study, we examined the role of NADPH oxidase in ischaemia/reperfusion (I/R)-induced damage in the rat gastric mucosa. Male SD rats were used after 18 h fasting. Under urethane anaesthesia, the stomach was mounted in an ex-vivo chamber, applied with 100 mM HCl, and a catheter was passed through the left femoral vein. To produce I/R, 4 mL of blood was removed at for 30 min, and then reperfused. DPI was given i.v. 10 min before reperfusion. The combination of ischaemia and reperfusion produced haemorrhagic damage in the rat gastric mucosa. The damage was attenuated by pretreatment of DPI. I/R increased microvascular permeability, the amount of H2O2 and NADPH oxidase activity in the stomach. These increases were suppressed by pretreatment of DPI. As to the presence of a subunit of NADPH oxidase, we detected protein level of p47phox in the gastric mucosa. In conclusion, these results showed that ROS production via NADPH oxidase activity is involved in the pathogenic mechanism of I/R damage in the rat stomach and suggested that activation of NADPH oxidase and the associated ROS product could be a potential target in the gastrointestinal mucosal damage.

Molecular phylogeny of labyrinthulids and thraustochytrids based on the sequencing of 18S ribosomal RNA gene.

Labyrinthulids and thraustochytrids are unicellular heterotrophs, formerly considered as fungi, but presently are recognized as members in the stramenopiles of the kingdom Protista sensu lato. We determined the 18S ribosomal RNA gene sequences of 14 strains from different species of the six genera and analyzed the molecular phylogenetic relationships. The results conflict with the current classification based on morphology, at the genus and species levels. These organisms are separated, based on signature sequences and unique inserted sequences, into two major groups, which were named the labyrinthulid phylogenetic group and the thraustochytrid phylogenetic group. Although these groupings are in disagreement with many conventional taxonomic characters, they correlated better with the sugar composition of the cell wall. Thus, the currently used taxonomic criteria need serious reconsideration.