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Diatoms function as major primary producers, accumulating large amounts of biomass in most aquatic environments. Given their rapid responses to changes in environmental conditions, diatoms are used for the biological monitoring of water quality and for performing ecotoxicological tests in aquatic ecosystems. However, the molecular basis for their toxicity to chemical compounds remains largely unknown. Here, we sequenced the genome of a freshwater diatom, Mayamaea pseudoterrestris NIES-4280, which has been proposed as an alternative strain of Navicula pelliculosa UTEX 664 for performing the Organisation for Economic Co-operation and Development ecotoxicological test. This study shows that M. pseudoterrestris has a small genome and carries the lowest number of genes among freshwater diatoms. The gene content of M. pseudoterrestris is similar to that of the model marine diatom, Phaeodactylum tricornutum. Genes related to cell motility, polysaccharide metabolism, oxidative stress alleviation, intracellular calcium signalling, and reactive compound detoxification showed rapid changes in their expression patterns in response to copper exposure. Active gliding motility was observed in response to copper addition, and copper exposure decreased intracellular calcium concentration. These findings enhance our understanding of the environmental adaptation of diatoms, and elucidate the molecular basis of toxicity of chemical compounds in algae. [ABSTRACT FROM AUTHOR]

Ischemia-reperfusion not only damages the affected organ but also leads to remote organ injuries. Hepatic inflow interruption usually occurs during hepatic surgery. To investigate the influence of liver ischemia-reperfusion on lung injury and to determine the contribution of tidal volume settings on liver ischemia-reperfusion-induced lung injury, we studied anesthetized and mechanically ventilated rats in which the hepatic inflow was transiently interrupted twice for 15 min. Two tidal volumes, 6 ml/kg as a low tidal volume (IR-LT) and 24 ml/kg as a high tidal volume (IR-HT), were assessed after liver ischemia-reperfusion, as well as after a sham operation, 6 ml/kg (NC-LT) and 24 ml/kg (NC-HT). Both the IR-HT and IR-LT groups had a gradual decline in the systemic blood pressure and a significant increase in plasma TNF-[alpha] concentrations. Of the four groups, only the IR-HT group developed lung injury, as assessed by an increase in the lung wet-to-dry weight ratio, the presence of significant histopathological changes, such as perivascular edema and intravascular leukocyte aggregation, and an increase in the bronchoalveolar lavage fluid TNF-[alpha] concentration. Furthermore, only in the IR-HT group was airway pressure increased significantly during the 6-h reperfusion period. These findings suggest that liver ischemia-reperfusion caused systemic inflammation and that lung injury is triggered when high tidal volume ventilation follows liver ischemia-reperfusion. acute lung injury; ventilator-induced lung injury; lung protective strategy; cytokines

Pneumonia caused by Pseudomonas aeruginosa carries a high rate of morbidity and mortality. A lung-protective strategy using low tidal volume ([V.sub.T]) ventilation for acute lung injury improves patient outcomes. The goal of this study was to determine whether low [V.sub.T] ventilation has similar utility in severe P. aeruginosa infection. A cytotoxic P. aeruginosa strain, PA103, was instilled into the left lung of rats anesthetized with pentobarbital. The lung-protective effect of low [V.sub.T] (6 ml/kg) with or without high positive end-expiratory pressure (PEEP, 10 or 3 cm[H.sub.2]O) was then compared with high [V.sub.T] with low PEEP ventilation ([V.sub.T] 12 ml/kg, PEEP 3 cm[H.sub.2]O). Severe lung injury and septic shock was induced. Although ventilatory mode had little effect on the involved lung or septic physiology, injury to noninvolved regions was attenuated by low [V.sub.T] ventilation as indicated by the wet-to-dry weight ratio (W/D; 6.13 [+ or -] 0.78 vs. 3.78 [+ or -] 0.26, respectively) and confirmed by histopathological examinations. High PEEP did not yield a significant protective effect (W/D. 4.03 [+ or -] 0.32) but, rather, caused overdistension of noninvolved lungs. Bronchoalveolar lavage revealed higher concentrations of TNF-[alpha] in the fluid of noninvolved lung undergoing high [V.sub.T] ventilation compared with those animals receiving low [V.sub.T]. We conclude that low [V.sub.T] ventilation is protective in noninvolved regions and that the application of high PEEP attenuated the beneficial effects of low [V.sub.T] ventilation, at least short term. Furthermore, low [V.sub.T] ventilation cannot protect the involved lung, and high PEEP did not significantly alter lung injury over a short time course. acute lung injury; ventilator-induced lung injury; lung protective strategy; cytokines; bacterial toxins