Effect of Nutrient Loading on Bacterioplankton Community Composition in Lake Mesocosms

Changes in bacterioplankton community composition were followed in mesocosms set up in the littoral of Lake Vesijärvi, southern Finland, over two summers. Increasing nitrogen and phosphorus concentrations in the mesocosms represented different trophic states, from mesotrophic to hypertrophic. In 1998, the mesocosms were in a turbid state with a high biomass of phytoplankton, whereas in 1999, macrophytes proliferated and a clear-water state prevailed. The bacterial communities in the mesocosms also developed differently, as shown by denaturing gradient gel electrophoresis profiling of partial 16S rRNA gene fragments and by nonmetric multidimensional scaling analysis. In 1998, nutrient treatments affected the diversity and clustering of bacterial communities strongly, but in 1999, the bacterial communities were less diversified and not clearly affected by treatments. Canonical correspondence analysis indicated that bacterioplankton communities in the mesocosms were influenced by environmental physicochemical variables linked to the increasing level of eutrophication. Nitrogen concentration correlated directly with the bacterioplankton composition. In addition, the high nutrient levels had indirect effects through changes in the biomass and composition of phyto- and zooplankton. Sequencing analysis showed that the dominant bacterial divisions remained the same, but the dominant phylotypes changed during the 2-year period. The occurrence of Verrucomicrobia correlated with more eutrophic conditions, whereas the occurrence of Actinobacteria correlated with less eutrophic conditions.     

Decreased frost hardiness of Vaccinium vitis-idaea in reponse to UV-A radiation

The aim of this study was to investigate plant frost hardiness responses to ultraviolet (UV) radiation, since the few results reported are largely contradictory. It was hypothesized that functional adaptation of life forms could explain these contradictions. Dwarf shrubs and tree seedlings, representing both evergreen and deciduous forms, were tested (Vaccinium vitis-idaea, Vaccinium myrtillus, Pinus sylvestris, Betula pubescens and its red form f. rubra). The research was performed in Sodankyl?, Northern Finland (67°N), with enhanced UV-B- and UV-A-radiation treatments between 2002 and 2009. Plant frost hardiness was determined using the freeze-induced electrolyte leakage method in early autumn, during the onset of the frost hardening process. Additional physiological variables (malondialdehyde, glutathione, total phenols, C and N contents) were analyzed in V. vitis-idaea to explain the possible responses. These variables did not respond significantly to UV-radiation treatments, but explained the frost hardiness well (r2 = 0.678). The main finding was that frost hardiness decreased in the evergreen shrub V. vitis-idaea, particularly with enhanced UV-A radiation. No significant responses were observed with the other plants. Therefore, this study does not support the idea that enhanced UV radiation could increase plant frost hardiness.     

Whole grain products, fish and bilberries alter glucose and lipid metabolism in a randomized, controlled trial: the Sysdimet study

Background

Due to the growing prevalence of type 2 diabetes, new dietary solutions are needed to help improve glucose and lipid metabolism in persons at high risk of developing the disease. Herein we investigated the effects of low-insulin-response grain products, fatty fish, and berries on glucose metabolism and plasma lipidomic profiles in persons with impaired glucose metabolism.

Methodology/Principal Findings

Altogether 106 men and women with impaired glucose metabolism and with at least two other features of the metabolic syndrome were included in a 12-week parallel dietary intervention. The participants were randomized into three diet intervention groups: (1) whole grain and low postprandial insulin response grain products, fatty fish three times a week, and bilberries three portions per day (HealthyDiet group), (2) Whole grain enriched diet (WGED) group, which includes principally the same grain products as group (1), but with no change in fish or berry consumption, and (3) refined wheat breads (Control). Oral glucose tolerance, plasma fatty acids and lipidomic profiles were measured before and after the intervention. Self-reported compliance with the diets was good and the body weight remained constant. Within the HealthyDiet group two hour glucose concentration and area-under-the-curve for glucose decreased and plasma proportion of (n-3) long-chain PUFAs increased (False Discovery Rate p-values <0.05). Increases in eicosapentaenoic acid and docosahexaenoic acid associated curvilinearly with the improved insulin secretion and glucose disposal. Among the 364 characterized lipids, 25 changed significantly in the HealthyDiet group, including multiple triglycerides incorporating the long chain (n-3) PUFA.

Conclusions/Significance

The results suggest that the diet rich in whole grain and low insulin response grain products, bilberries, and fatty fish improve glucose metabolism and alter the lipidomic profile. Therefore, such a diet may have a beneficial effect in the efforts to prevent type 2 diabetes in high risk persons.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00573781","term_id":"NCT00573781"}}NCT00573781     

Fallen retention aspen trees on clear-cuts can be important habitats for red-listed polypores: a case study in Finland

Green-tree retention is a relatively new forestry application, which aims at decreasing the negative effects of clear-cut logging on forest biodiversity. In this study, the value of retained aspens in maintaining diverse assemblages of wood-decaying fungi (polypores; Basidiomycota) on clear-cuts was investigated, after the retention trees had died, fallen and started to decay. A total of 110 fallen aspen trunks were investigated on clear-cuts and within old-growth forests in eastern Finland, southern boreal zone; and 499 records of polypores belonging to 46 species were made. The intermediately decayed trunks on a clear-cut area hosted more species and more red-listed species than did trunks within forests. Most of the polypore species with more than two records were found in both habitats. These results suggest that many aspen-associated polypores are able to live and reproduce in sun-exposed habitats, if the quality and quantity of dead wood fulfill the species-specific requirements. This unexpected result, however, may be partly due to the exceptionally great abundance of aspen in the study area. Furthermore, in the long term, the local benefits of fallen retention trees can be limited, unless the local continuity of large aspens, both living and dead, is ensured.     

Subchronic treatment with vanadate does not potentiate the toxicity of cardiac glycosides

Since it has been claimed that vanadate is an endogenous regulator of Na/K-ATPase activity and that it potentiates the toxicity of cardiac glycosides, we were alarmed to discover that certain Finnish physicians were prescribing vanadate in combination with other trace minerals to elderly patients for many different chronic diseases (e.g., cancer, rheumatism). To study the interaction of vanadate and cardiac glycosides, we fed vanadate in the drinking water (25 μg/mL) to guinea pigs for 20 d, and studied either their sensitivity to the acute toxicity of the cardiac glycoside ouabain or whether the vanadate would influence the subacute toxicity of ouabain. Vanadate had no influence on the toxicity of ouabain either acute or subchronically administered, nor was there any sign of inhibition of Na/K-ATPase activity as measured by⁸⁶Rb-uptake into intact erythrocytes (RBCs), RBC content of sodium or potassium or Na/K-ATPase activity in RBC membranes prepared from the vanadate-treated guinea pigs. Vanadate had been absorbed in substantial quantities from the gastrointestinal tract, since serum, heart, liver, and especially kidney contained measurable amounts of vanadium in contrast to controls, but it is concluded that this vanadate is not in a biologically active form.     

Restriction map of virulence plasmid in Yersinia enterocolitica O:3

Restriction map of the 72-kb virulence plasmid isolated from Yersinia enterocolitica O:3 was generated using EcoRI, BamHI, HindIII, and XbaI restriction enzymes. The mapping was done after cloning all of the 13 BamHI fragments of the plasmid in Escherichia coli. In addition, the restriction enzyme analysis revealed two types of virulence plasmids (types I and II) in Y. enterocolitica O:3. No functional differences between the strains bearing type I or type II plasmid were observed.     

Description of Non-Type Seinura winchesi from Mushroom Compost (Nematoda: Seinuridae)

Non-type material identified as Seinura winchesi, and deposited in the collection of the Nematology Department, Rothamsted Experimental Station, England, is described. The material was collected from mushroom compost in Leeds, England, in 1957. Females of this population are characterized by a set-off head, knobless stylet (20-21 µm), two rows of oogonia-oocytes, and absence of a postuterine sac. The median bulb is oblong and, at times, is constricted in the middle. The body is 565 to 675 µm long and tapers posteriorly to a pointed terminus. The cuticle is finely annulated, and there are three incisures in the lateral field. The ovary is outstretched and overlaps the esophageal gland lobes. A spermatheca is present, and spermatozoa are visible. The vulva is posteriorly located (V = 77-80), and a flap is absent. Males are 550 to 680 µm long with a spicate tail that bears three pairs of subventral papillae. The spike is short (14-18 µm), about one-half the tail length. The testis is 360 to 412 µm long, not reflexed, and at times overlaps the esophageal gland lobes. Spermatogonia-spermatocytes are in two rows. Spicules are 14 to 15 µm long with a prominent apex, and small rostrum. A bursa and gubernaculum are absent.     

Fungal communities decline with urbanization—more in air than in soil

Increasing evidence suggests that degradation of biodiversity in human populated areas is a threat for the ecosystem processes that are relevant for human well-being. Fungi are a megadiverse kingdom that plays a key role in ecosystem processes and affects human well-being. How urbanization influences fungi has remained poorly understood, partially due to the methodological difficulties in comprehensively surveying fungi. Here we show that both aerial and soil fungal communities are greatly poorer in urban than in natural areas. Strikingly, a fivefold reduction in fungal DNA abundance took place in both air and soil samples already at 1 km scale when crossing the edge from natural to urban habitats. Furthermore, in the air, fungal diversity decreased with urbanization even more than in the soil. This result is counterintuitive as fungal spores are known to disperse over large distances. A large proportion of the fungi detectable in the air are specialized to natural habitats, whereas soil fungal communities comprise a large proportion of habitat generalists. The sensitivity of the aerial fungal community to anthropogenic disturbance makes this method a reliable and efficient bioindicator of ecosystem health in urban areas.Subject terms: Community ecology, Fungal ecology     

Aphelenchoides microstylus n. sp. and Seinura onondagensis n. sp. (Nemata: Aphelenchina) from New York

Aphelenchoides microstylus n. sp. and Seinura onondagensis n. sp., a nematode predator, are described from dead Scots pine (Pinus sylvestris L.) in Onondaga County, New York. Females of A. microstylus are 370 to 485 µm long. The body is slender and tapers posteriorly to an amucronate, pointed terminus. The head is continuous with the body, and lips bear a stylet guide. Diagnostic characters of females are three incisures in the lateral field, a short stylet (6-7.5 µm) with small basal knobs, a single row of oocytes, and a long postuterine sac (25-50 µm). Males are characterized by small spicules (10-11µm); two pairs of post-anal, subventral papillae; and a single row of spermatocytes. A bursa and gubernaculum are absent. Seinura onondagensis females are characterized by a body of moderate length (475-595 µm), finely annulated cuticle, and a slightly set-off head. Diagnostic characters are four incisures in the lateral field, long stylet without basal knobs (17-22 µm), single row of oocytes, and presence of a postuterine sac (14-38 µm). Males are unknown. The monospecific genus Indaphelenchus is proposed as a synonym of Seinura, and S. siddiqii n. comb. is proposed for the only species, I. siddiqii.