Biofilm development in the extremely acidophilic archaeon ‘Ferroplasma acidarmanus’ Fer1

‘Ferroplasma acidarmanus’ Fer1 is an iron-oxidizing extreme acidophile isolated from the Iron Mountain mine, California, USA. This archaeon is predominantly found in biofilm-associated structures in the environment, and produces two distinct biofilm morphologies. Bioinformatic analysis of the ‘F. acidarmanus’ Fer1 genome identified genes annotated as involved in attachment and biofilm formation. No putative quorum sensing signaling genes were identified and no N-acyl homoserine lactone-like compounds were found in ‘F. acidarmanus’ Fer1 biofilm supernatant. Scanning confocal microscopy analysis of biofilm development on the surface of pyrite demonstrated the temporal and spatial development of biofilm growth. Furthermore, two-dimensional polyacrylamide gel electrophoresis was used to examine differential protein expression patterns between biofilm and planktonic populations. Ten up-regulated proteins were identified that included six enzymes associated with anaerobic growth, suggesting that the dominating phenotype in the mature biofilm was associated with anaerobic modes of growth. This report increases our knowledge of the genetic and proteomic basis of biofilm formation in an extreme acidophilic archaeon.     

Is xenodontine snake reproduction shaped by ancestry,more than by ecology?

One of the current challenges of evolutionary ecology is to understand the effects of phylogenetic history (PH) and/or ecological factors (EF) on the life‐history traits of the species. Here, the effects of environment and phylogeny are tested for the first time on the reproductive biology of South American xenodontine snakes. We studied 60% of the tribes of this endemic and most representative clade in a temperate region of South America. A comparative method (canonical phylogenetic ordination—CPO) was used to find the relative contributions of EF and PH upon life‐history aspects of snakes, comparing the reproductive mode, mean fecundity, reproductive potential, and frequency of nearly 1,000 specimens. CPO analysis showed that PH or ancestry explained most of the variation in reproduction, whereas EF explained little of this variation. The reproductive traits under study are suggested to have a strong phylogenetic signal in this clade, the ancestry playing a big role in reproduction. The EF also influenced the reproduction of South American xenodontines, although to a lesser extent. Our finding provides new evidence of how the evolutionary history is embodied in the traits of living species.     

Stereochemistry of the hydrolysis of α,α-trehalose by trehalase,determined by using a labelled substrate

(1,1′-¹³C)α,α-Trehalose was obtained in 37% yield from the Pavia condensation of 2,3,4,6-tetra-O-benzyl-d-(1-¹³C)glucopyranose, in dichloromethane in the presence of trifluoromethanesulfonic anhydride, followed by the usual deprotection techniques. The hydrolysis of this substrate by cockchafer trehalase was monitored at 37° by using ¹³C-n.m.r. spectroscopy with short recording times. Equimolecular amounts of α- and β-d-glucopyranose are released simultaneously by the action of the enzyme. This result is consistent with a bimolecular substitution mechanism, taking into account previous results involving C-2 asymmetric participation in the catalytic step of hydrolysis of α,α-trehalose. For comparative evaluation of its accuracy, the usual polarimetric technique was also used for the determination of the anomeric configuration of the d-glucose released by the action of the enzyme on α,α-trehalose.     

Characterization of the extracellular,water-insoluble α-D-glucans of oral streptococci by methylation analysis,and by enzymic synthesis and degradation

Methylation analysis of water-insoluble α-D-glucans synthesized from sucrose by culture filtrates from several strains of Streptococcus spp. has proved that all of the glucans were highly branched and that the chains contained (1→6)- and (1→3)-linked D-glucose residues not involved in branch points. Hydrolysis of the glucans with a specific endo-(1→3)-α-D-glucanase demonstrated that the majority of the (1→3)-linked glucose residues were arranged in sequences. D-Glucose was the major product of the hydrolysis, and a small proportion of nigerose was also released. The use of a specific endo-(1→6)-α-D-glucanase similarly indicated that the glucans also contained sequences of (1→6)-linked α-D-glucose residues, and that those chains were branched. Two D-glucosyltransferases (GTF-S and GTF-I), which reacted with sucrose to synthesize a soluble glucan and a water-insoluble glucan, respectively, were separated from culture filtrates of S. mutans OMZ176. The soluble glucan was characterized as a branched (1→6)-α-D-glucan, whereas the insoluble one was a relatively linear (1→3)-α-D-glucan. The hypothesis is advanced that the glucosyltransferases can transfer glucan sequences by means of acceptor reactions similar to those proposed by Robyt for dextransucrase, leading to the synthesis of a highly branched glucan containing both types of chain. The resulting structure is consistent with the evidence obtained from methylation analysis and enzymic degradations, and explains the synergy displayed when the two D-glucosyltransferases interact with sucrose. Variations in one basic structure can account for the characteristics of water-insoluble glucans from S. sanguis and S. salivarius, and for the strain-dependent diversity of S. mutans glucans.     

Using γ-emitting artificial radionuclides,released by nuclear plants,as markers of restricted movements by chub,Leuciscus cephalus,in a large river,the Lower Rhône

Synopsis On the basis that -emitting artificial radionuclides, present in nuclear plant radioactive wastes, can be considered as natural collective markers of fish living downstream from a radioactive discharge, we studied the restricted movements of chub in a reservoir on the Lower Rhône river where the Marcoule nuclear plant is located. A qualitative determination, based on the detection of specific radioelements in our samples originating from radioactive waste, and a quantitative determination of the cesium-137 concentration in the samples, were used to identify fish radioactively marked by the effluent. Individual measurements of -radioactivity in 49 adult chub captured at two stations, each 2 km long and 6 km apart, divided the fish into two distinct sub-units: one living downstream of the discharge pipe, in which 73% were marked, and the other upstream, in which 79% were not marked. Similar results were found in two neighbouring stations when we analysed previous radioecological measurements of -radioactivity in groups of chub. After combining all the data concerning chub, detailed information was obtained on the spatial stability of the chub population in the reservoir. Two spatially different stocks were found and each stock can be divided in two components: a sedentary component that remains in a restricted zone (its home range), and a mobile component that undertakes movements between the two zones.     

Skink predation by hedgehogs at Macraes Flat, Otago, New?Zealand

The stomach contents of 158 hedgehogs captured at Macraes Flat, Otago, New Zealand, over two summers in 2000 and 2001 were examined for the occurrence of lizards. The remains of at least 43 skinks (both Oligosoma nigriplantare polychroma and O.?maccanni) and one gecko (Hoplodactylus sp.) were found. Twenty-one percent (n?=?33; 8 males and 25 females) of the examined hedgehogs had fed on skinks. Female hedgehogs ate significantly more skinks than did males. Our results suggest that the presence of large numbers of hedgehogs can have a high impact on native reptile populations in New Zealand and therefore they should be targeted in future trapping programmes.     

Food, Nutrigenomics, and Neurodegeneration—Neuroprotection by What You Eat!

Diet in human health is no longer simple nutrition, but in light of recent research, especially nutrigenomics, it is linked via evolution and genetics to cell health status capable of modulating apoptosis, detoxification, and appropriate gene response. Nutritional deficiency and disease especially lack of vitamins and minerals is well known, but more recently, epidemiological studies suggest a role of fruits and vegetables, as well as essential fatty acids and even red wine (French paradox), in protection against disease. In the early 1990s, various research groups started considering the use of antioxidants (e.g., melatonin, resveratrol, green tea, lipoic acid) and metabolic compounds (e.g., nicotinamide, acetyl-l-carnitine, creatine, coenzyme Q₁₀) as possible candidates in neuroprotection. They were of course considered on par with snake oil salesman (women) at the time. The positive actions of nutritional supplements, minerals, and plant extracts in disease prevention are now mainstream and commercial health claims being made are subject to regulation in most countries. Apart from efficacy and finding, the right dosages, the safety, and especially the level of purification and lack of contamination are all issues that are important as their use becomes widespread. From the mechanistic point of view, most of the time these substances replenish the body’s deficiency and restore normal function. However, they also exert actions that are not sensu stricto nutritive and could be considered pharmacological especially that, at times, higher intake than recommended (RDA) is needed to see these effects. Free radicals and neuroinflammation processes underlie many neurodegenerative conditions, even Parkinson’s disease and Alzheimer’s disease. Curcumin, carotenoids, acetyl-l-carnitine, coenzyme Q₁₀, vitamin D, and polyphenols and other nutraceuticals have the potential to target multiple pathways in these conditions. In summary, augmenting neuroprotective pathways using diet and finding new natural substances that can be more efficacious, i.e., induction of health-promoting genes and reduction of the expression of disease-promoting genes, could be incorporated into neuroprotective strategies of the future.     

Spatial analysis of mortality caused by malignant tumors, especially by digestive system tumors, using empirical Bayes estimates in Fejér County, Hungary

General practitioners in the vicinity of Lake Velencei in Fejér County, Hungary, have reported an unusual pattern of recent cancer mortality. Our aim was to clarify whether the presumed mortality cluster is epidemiologically justified; whether it is restricted to the locations in question or also appears elsewhere in the county; and if it is associated with some particular disease group. County mortality from malignancies of the digestive system, other malignancies, and all other causes for the period 1994 to 1999 was analyzed in 15- to 64-year-old men and women, using conventional standardized mortality ratios and empirical Bayes estimates. A continuous surface was interpolated from settlement level data for mortality maps. A mortality cluster from men's digestive cancers is apparent north and east of Lake Velencei and also elsewhere in the county. Differences from the country average in the frequency of males' deaths from other malignancies are fairly limited. A number of problematic areas in men's mortality from other causes are identifiable, including some of the settlements under the primary focus. Women's digestive tract cancer mortality in the area of the men's cluster near Lake Velencei is below the national average. There are almost no differences from the country level in women's deaths from other malignancies. Female mortality from all other causes shows remarkable elevations in the south of the county. Our results suggest the possible role of geographically localized exposures. Men's high mortality from digestive tract cancers is a problem affecting a considerable area of the county, necessitating further investigation. Continued search for causes is also warranted by some estimates of exceptionally high death rates in women from causes other than malignancies.     

Is the expression of autogeny by Culex molestus Forskal (Diptera: Culicidae) influenced by larval nutrition or by adult mating,sugar feeding,or blood feeding?

Culex molestus Forskal is suspected to have been introduced into southern Australia during the 1940s. Investigations to determine factors influencing the expression of autogeny, the response of this mosquito to potential blood meals, and the subsequent influence on oviposition were undertaken. Immature mosquitoes raised at five feeding regimes had mortality rates, development rates, wing length, and autogenous egg raft size measured. All surviving female mosquitoes laid autogenous eggs but there was a significant difference between the mean number of eggs per raft. For mosquitoes raised at each of the feeding regimes, there was a significant linear relationship between the number of eggs per autogenous egg raft and wing length. Newly emerged mosquitoes were offered a blood meal (i.e., rodent) daily but no blood feeding occurred until the autogenous egg raft was laid. There was no statistical difference in the rate of autogenous oviposition or post-oviposition blood feeding between control or treatment groups. The results of this study indicate that Cx. molestus is perfectly adapted to subterranean habitats in close association with human habitation, but their preference to delay blood feeding until up to day 8 following emergence may reduce their relative importance as a vector of arboviruses.     

Lake Prespa,a European natural monument,endangered by irrigation and eutrophication?

The most interesting (Hutchinson, 1957), and at the same time oldest graben lakes of Europe, are Lakes Ohrid and Prespa. According to geologists and geographers, both originated during the Pliocene. They show karstic features and differ by volume, much less by area. At the occasion of an excursion to Lake Prespa in September 1994, an absence of oxygen in the hypolimnion between 17 m and the maximum lake depth, 48 m, was observed, for the first time since Stankovic' (1926) record. Moreover, a continuous decrease in lake level since the 1960s, the lowest transparency ever recorded from Megali Prespa, and high nutrient values, though only observed during a short part of the late stagnation period, are alarming signals, all suggesting eutrophication.     

Petiole mechanics,light interception by Lamina,and “Economy in Design”

Summary Computer simulations were used to assess the influence of palmate leaf morphology, decussate phyllotaxy, and the elastic moduli of petioles on the capacity of turgid and wilted twigs ofAesculus hippocastanum to intercept direct solar radiation. Leaf size, morphology, orientation, and the Young's and shear moduli (E and G) of petioles were measured and related to leaf position on 8 twigs whose cut ends were placed in water (turgid twigs) and 8 twigs dried for 8 h at room temperature (wilted twigs). Petioles mechanically behaved as elastic cantilevered beams; the loads required to shear petioles at their base from twigs were correlated with the cross-sectional areas of phyllopodia but not with petiole length or tissue volume. Empirically determined morphometric and biomechanical data were used to construct average turgid and wilted twigs. The diurnal capacity to intercept direct sunlight for each was simulated for vertically oriented twigs for 15 h of daylight, 40° N latitude. The daily integrated irradiance (DII) of the wilted twig was roughly 3% less than that of the otherwise comparable twig bearing turgid leaves. Simulations indicated that the orientation of turgid leaves did not maximize DII. More decumbent (wilted) petioles increased DII by as much as 4%. Reduction in the girth, E, or G of petioles, or an increase in petiole length or the surface area of laminae (with attending increase in laminae weight), increased petiolar deflections and DII. Thus, the mechanical design of petioles ofA. hippocastanum was found not to be economical in terms of investing biomass for maximum light interception.     

Characterization of Antimicrobial-bearing Liposomes by ζ-Potential, Vesicle Size, and Encapsulation Efficiency

Liposome entrapment may improve activity of protein or polypeptide antimicrobials against a variety of microorganisms. In this study, ability of liposomes to withstand exposure to environmental and chemical stresses typically encountered in foods and food processing operations were tested. Liposomes consisting of distearoylphosphatidylcholine (PC) and distearoylphosphatidylglycerol (PG), with 0, 5, or 10 μg/ml of the antimicrobial peptide nisin entrapped, were exposed to elevated temperatures (25–75 °C) and a range of pH (5.5–11.0). Ability of liposomes to maintain integrity was assessed by measuring the encapsulation efficiency (EE), ζ-potential, and particle size distribution of liposomes. Distearoylphosphatidylcholine, PC/PG 8:2, and PC/PG 6:4 (mole fraction) liposomes retained between ~70–90% EE despite exposure to elevated temperature and alkaline or acidic pH. Particle size of liposomes averaged between 100 and 240 nm depending on liposome preparation. Liposomal surface charge depended primarily on phospholipid composition and changed little with inclusion of nisin. Surface charge was not affected by temperature for PC and PC/PG 8:2 but decreased for PC/PG 6:4 liposomes. Our results suggest that liposomes containing nisin may be suitable for use as antimicrobial-active ingredients in low- or high-pH foods subjected to moderate heat treatments.     

Competitive, reversible, physiological? Inhibition of mitochondrial cytochrome oxidase by nitric oxide

In the mid 1990s a number of research groups recognized that mitochondrial oxygen consumption could be reversibly inhibited by nitric oxide at the level of the enzyme cytochrome c oxidase. The inhibition was apparently competitive with respect to the oxygen concentration. This review critically assesses the present state of knowledge as regards the hypothesis that nitric oxide is a competitive, reversible, physiological inhibitor of cytochrome oxidase.     

The fusion of erythrocytes by fatty acids, esters, retinol and α-tocopherol

1. The ability of a number of carboxylic acids, their esters, retinol and alpha-tocopherol to induce fusion of hen erythrocytes in vitro was investigated. 2. Some 30 different fat-soluble substances (100mug/ml) were found to cause the formation of multinucleated erythrocytes with a suspension of 3x10(8) erythrocytes/ml. The most effective agents induced fusion within 5-10min at 37 degrees C; some substances required about 1h. 3. Inclusion of Dextran 60C in the test medium minimized colloid osmotic lysis caused by exogenous lipids that induce cell fusion. 4. Cell swelling, followed by cell adhesion, was then seen to precede cell fusion. 5. Fusion occurred with C(10)-C(14) saturated carboxylic acids, with unsaturated, longer-chain carboxylic acids and their mono-esters; retinol, and to a lesser extent alpha-tocopherol, also caused cell fusion. 6. C(6)-C(9), C(15), C(16) and C(18) saturated carboxylic acids did not induce fusion within 4h; glyceryl dioleate was only weakly active, and glyceryl trioleate was inactive in the test system. 7. Fusion was facilitated by a high ratio of chemical agents to cell number and by incubation between pH5 and 6. It was inhibited by EDTA and by serum albumin. 8. Glyceryl mono-oleate caused both a similar fusion of several species of mammalian erythrocyte and the interspecific fusion of human and chicken erythrocytes. 9. The term ;fusogenic' is proposed to describe chemical, viral and physical agents that cause membranes to fuse. 10. The biochemical mechanisms involved and the possible biological significance of membrane fusion by fusogenic lipids are discussed.