Arctic marine fungi: biomass, functional genes, and putative ecological roles.

Recent molecular evidence suggests a global distribution of marine fungi; however, the ecological relevance and corresponding biological contributions of fungi to marine ecosystems remains largely unknown. We assessed fungal biomass from the open Arctic Ocean by applying novel biomass conversion factors from cultured isolates to environmental sterol and CARD-FISH data. We found an average of 16.54 nmol m-3 of ergosterol in sea ice and seawater, which corresponds to 1.74 mg C m-3 (444.56 mg C m-2 in seawater). Using Chytridiomycota-specific probes, we observed free-living and particulate-attached cells that averaged 34.07 µg C m-3 in sea ice and seawater (11.66 mg C m-2 in seawater). Summed CARD-FISH and ergosterol values approximate 1.77 mg C m-3 in sea ice and seawater (456.23 mg C m-2 in seawater), which is similar to biomass estimates of other marine taxa generally considered integral to marine food webs and ecosystem processes. Using the GeoChip microarray, we detected evidence for fungal viruses within the Partitiviridae in sediment, as well as fungal genes involved in the degradation of biomass and the assimilation of nitrate. To bridge our observations of fungi on particulate and the detection of degradative genes, we germinated fungal conidia in zooplankton fecal pellets and germinated fungal conidia after 8 months incubation in sterile seawater. Ultimately, these data suggest that fungi could be as important in oceanic ecosystems as they are in freshwater environments.

[Effect of concomitant chronic kidney disease on the xanthine metabolism in patients with chronic heart failure].

It is believed that patients with decreased glomerular filtration rate have stronger association between serum uric acid levels and increased risk of cardіоvascular disease. However, it is unclear whether the presence of concomitant chronic kidney disease modifies the xanthine metabolism. The aim of this study was to examine xanthine metabolism violations in chronic heart failure (CHF) patients with concomitant chronic kidney disease (CKD), and evaluate its impact on uric acid levels and xanthine oxidase activity. The study population consisted of 112 patients, aged 72,5±0,98 years. The main group of patients consisted of 72 within CKD patients and the comparison group - of 40 non-CKD participants. We noted high and almost equal detection of xanthine metabolism violations in CHF patients with CKD as well as in non-CKD patients. This data indicate greater severity of the xanthine metabolism violations in patients with concomitant CKD.

Lipoxygenase is involved in the control of potato tuber development.

Plant lipoxygenases (LOXs) are a functionally diverse class of dioxygenases implicated in physiological processes such as growth, senescence, and stress-related responses. LOXs incorporate oxygen into their fatty acid substrates and produce hydroperoxide fatty acids that are precursors of jasmonic acid and related compounds. Here, we report the involvement of the tuber-associated LOXs, designated the Lox1 class, in the control of tuber growth. RNA hybridization analysis showed that the accumulation of Lox1 class transcripts was restricted to developing tubers, stolons, and roots and that mRNA accumulation correlated positively with tuber initiation and growth. In situ hybridization showed that Lox1 class transcripts accumulated in the apical and subapical regions of the newly formed tuber, specifically in the vascular tissue of the perimedullary region, the site of the most active cell growth during tuber enlargement. Suppression mutants produced by expressing antisense coding sequence of a specific tuber LOX, designated POTLX-1, exhibited a significant reduction in LOX activity in stolons and tubers. The suppression of LOX activity correlated with reduced tuber yield, decreased average tuber size, and a disruption of tuber formation. Our results indicate that the pathway initiated by the expression of the Lox1 class genes of potato is involved in the regulation of tuber enlargement.

A leaf lipoxygenase of potato induced specifically by pathogen infection.

Lipoxygenase (LOX) activity has been identified consistently during pathogen-induced defense responses. Here we report the involvement of a specific leaf LOX gene of potato (Solanum tuberosum), designated POTLX-3 (GenBank/EMBL accession no. U60202), in defense responses against pathogens. The sequence of POTLX-3 does not match any other LOX genes of potato and has the greatest match to a tobacco LOX gene that contributes to a resistance mechanism against Phytophthora parasitica var nicotianae. POTLX-3 transcript accumulation was not detected in untreated, healthy potato organs or in wounded mature leaves. POTLX-3 mRNA accumulation was induced in potato leaves treated with ethylene or methyl jasmonate or infected with either virulent or avirulent strains of Phytophthora infestans, the causal agent of late blight. During the resistance response, POTLX-3 was induced within 6 hours, increased steadily through 24 hours, and its mRNA continued to accumulate for a week after inoculation. In contrast, when a plant was susceptible to P. infestans, induction of mRNA accumulation in response to inoculation was inconsistent and delayed. LOX activity assayed during an incompatible interaction in leaves peaked 3 days earlier than during a compatible interaction. POTLX-3 mRNA accumulation also was induced during hypersensitive response development caused by the incompatible pathogen Pseudomonas syringae pv phaseolicola. Our results show that POTLX-3 may be involved specifically in defense responses against pathogen infection.