Metagenomic investigation of the geologically unique Hellenic Volcanic Arc reveals a distinctive ecosystem with unexpected physiology

Hydrothermal vents represent a deep, hot, aphotic biosphere where chemosynthetic primary producers, fuelled by chemicals from Earth's subsurface, form the basis of life. In this study, we examined microbial mats from two distinct volcanic sites within the Hellenic Volcanic Arc (HVA). The HVA is geologically and ecologically unique, with reported emissions of CO₂‐saturated fluids at temperatures up to 220°C and a notable absence of macrofauna. Metagenomic data reveals highly complex prokaryotic communities composed of chemolithoautotrophs, some methanotrophs, and to our surprise, heterotrophs capable of anaerobic degradation of aromatic hydrocarbons. Our data suggest that aromatic hydrocarbons may indeed be a significant source of carbon in these sites, and instigate additional research into the nature and origin of these compounds in the HVA. Novel physiology was assigned to several uncultured prokaryotic lineages; most notably, a SAR406 representative is attributed with a role in anaerobic hydrocarbon degradation. This dataset, the largest to date from submarine volcanic ecosystems, constitutes a significant resource of novel genes and pathways with potential biotechnological applications.     

Toxoplasmosis snapshots: Global status of Toxoplasma gondii seroprevalence and implications for pregnancy and congenital toxoplasmosis

Toxoplasma gondii’s importance for humans refers mainly to primary infection during pregnancy, resulting in abortion/stillbirth or congenital toxoplasmosis. The authors sought to evaluate the current global status of T. gondii seroprevalence and its correlations with risk factors, environmental and socioeconomic parameters. Literature published during the last decade on toxoplasmosis seroprevalence, in women who were pregnant or of childbearing age, was retrieved. A total of 99 studies were eligible; a further 36 studies offered seroprevalence data from regions/countries for which no data on pregnancy/childbearing age were available. Foci of high prevalence exist in Latin America, parts of Eastern/Central Europe, the Middle East, parts of south-east Asia and Africa. Regional seroprevalence variations relate to individual subpopulations’ religious and socioeconomic practices. A trend towards lower seroprevalence is observed in many European countries and the United States of America (USA). There is no obvious climate-related gradient, excluding North and Latin America. Immigration has affected local prevalence in certain countries. We further sought to recognise specific risk factors related to seropositivity; however, such risk factors are not reported systematically. Population awareness may affect recognition of said risks. Global toxoplasmosis seroprevalence is continuingly evolving, subject to regional socioeconomic parameters and population habits. Awareness of these seroprevalence trends, particularly in the case of women of childbearing age, may allow proper public health policies to be enforced, targeting in particular seronegative women of childbearing age in high seroprevalence areas.     

Tissue structure-specific distribution of glycosaminoglycans in the human penis

The aim of this work was to isolate and characterise the glycosaminoglycans present in the different tissue structures of the human penis in view of their potentially significant role in the physiology of erection. Penile tissue samples were obtained from patients who underwent penectomy and were subsequently dissected into individual tissue structures. Total glycosaminoglycans were isolated and purified from tunica albuginea, corpora cavernosa and corpus spongiosum, following tissue mincing, ultrasonication, lipid extraction, extensive digestion with pronase and DNase, treatment with alkali-borohydride and ethanol precipitation. Isolated glycosaminoglycans were separated by cellulose acetate electrophoresis and fractionated by anion exchange chromatography on DEAE Sephacel columns. Different glycosaminoglycan fractions were identified using glycosaminoglycan-degrading enzymes of known specificity. Gradient polyacrylamide gel electrophoresis was used to determine the average molecular mass of the glycosaminoglycans. The corpus cavernosum and the corpus spongiosum extracts contained almost twice the amount of glycosaminoglycan-associated uronic acids as compared to the tunical extracts (1.47+/-0.09, and 1.49+/-0.15 as opposed to 0.75+/-0.15 microg/mg dry defatted tissue, respectively; S.E.M., n=5). With the exception of hyaluronic acid, the relative amount of individual glycosaminoglycan types varied significantly among extracts of different origin. Heparan sulphate was more abundant in cavernosal, dermatan sulphate in tunical, and chondroitin-6-sulphate in corpus spongiosum extracts. No structure-specific differences were detected with respect to the molecular mass distribution of each glycosaminoglycan type. Our study shows that the different structures of the human penis produce distinct profiles of glycosaminoglycans, which are well suited to the individual functional characteristics of these structures.     

Effective gene dispersal and female reproductive success in Mediterranean maritime pine (Pinus pinaster Aiton)

Understanding population-scale processes that affect allele frequency changes across generations is a long-standing interest in genetic, ecological and evolutionary research. In particular, individual differences in female reproductive success and the spatial scale of gene flow considerably affect evolutionary change and patterns of local selection. In this study, a recently developed maximum-likelihood (ML) method based on established offspring, the Seedling Neighbourhood Model , was applied and exponentially shaped dispersal kernels were fitted to both genetic and ecological data in a widespread Mediterranean pine, Pinus pinaster Aiton. The distribution of female reproductive success in P. pinaster was very skewed (about 10% of trees mothered 50% of offspring) and significant positive female selection gradients for diameter (γ = 0.7293) and cone crop (γ = 0.4524) were found. The selective advantage of offspring mothered by bigger trees could be due to better-quality seeds. These seeds may show more resilience to severe summer droughts and microsite variation related to water and nutrient availability. Both approaches, ecological and of parentage, consistently showed a long-distance dispersal component in saplings that was not found in dispersal kernels based on seed shadows, highlighting the importance of Janzen-Connell effects and microenvironmental variation for survival at early stages of establishment in this Mediterranean key forest tree.     

The binding of 3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine to ribonuclease A in the crystal

The binding of a moderate inhibitor, 3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine, to ribonuclease A has been studied by X-ray crystallography at 1.7A resolution. Two inhibitor molecules are bound in the central RNA binding cavity of RNase A exploiting interactions with residues from peripheral binding sites rather than from the active site of the enzyme. The uracyl moiety of the first inhibitor molecule occupies the purine-preferring site of RNase A, while the rest of the molecule projects to the solvent. The second inhibitor molecule binds with the carboxyl group at the pyrimidine recognition site and the uridine moiety exploits interactions with RNase A residues Lys66, His119 and Asp121. Comparative structural analysis of the 3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine complex with other RNase A-ligand complexes provides a structural explanation of its potency. The crystal structure of the RNase A-3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine complex provides evidence of a novel ligand-binding pattern in RNase A for 3'-N-aminonucleosides that was not anticipated by modelling studies, while it also suggests ways to improve the efficiency and selectivity of such compounds to develop pharmaceuticals against pathologies associated with RNase A homologues.     

Crystallographic studies on two bioisosteric analogues, N-acetyl-beta-D-glucopyranosylamine and N-trifluoroacetyl-beta-D-glucopyranosylamine, potent inhibitors of muscle glycogen phosphorylase

Structure-based inhibitor design has led to the discovery of a number of potent inhibitors of glycogen phosphorylase b (GPb), N-acyl derivatives of beta-D-glucopyranosylamine, that bind at the catalytic site of the enzyme. The first good inhibitor in this class of compounds, N-acetyl-beta-D-glucopyranosylamine (NAG) (K(i) = 32 microM), has been previously characterized by biochemical, biological and crystallographic experiments at 2.3 angstroms resolution. Bioisosteric replacement of the acetyl group by trifluoroacetyl group resulted in an inhibitor, N-trifluoroacetyl-beta-D-glucopyranosylamine (NFAG), with a K(i) = 75 microM. To elucidate the structural basis of its reduced potency, we determined the ligand structure in complex with GPb at 1.8 angstroms resolution. To compare the binding mode of N-trifluoroacetyl derivative with that of the lead molecule, we also determined the structure of GPb-NAG complex at a higher resolution (1.9 angstroms). NFAG can be accommodated in the catalytic site of T-state GPb at approximately the same position as that of NAG and stabilize the T-state conformation of the 280 s loop by making several favourable contacts to Asn284 of this loop. The difference observed in the K(i) values of the two analogues can be interpreted in terms of subtle conformational changes of protein residues and shifts of water molecules in the vicinity of the catalytic site, variations in van der Waals interaction, and desolvation effects.     

Impact of obesity in intima media thickness of carotid arteries

Objective: To explore differences in intima media thickness (IMT) of the carotid arteries induced by differences in BMI. Research Methods and Procedures: Data from 3173 consecutive subjects, who were referred to our Hypertension Center from 1998 to 2004, were reviewed. Criteria for patients to be considered for further analysis included no past or concurrent antihypertensive medication, no concurrent medication with the potential to raise blood pressure (BP) (e.g., prednisone), and no clinical signs or laboratory evidence of secondary causes of hypertension. Our population was divided into four groups according to NIH criteria for obesity: underweight, normal weight, overweight, and obese. BMI, mean IMT of internal carotid arteries, and 24‐hour BP values were available for all subjects. Five hundred thirty six subjects of the four groups, matched for age, gender, and mean 24‐hour BP values, were included in the analysis. Results: Mean IMT of internal carotid arteries was increased with increasing BMI. Mean IMT was significantly higher in obese subjects compared with normal‐weight (p < 0.01) and underweight (p < 0.001) subjects. Mean IMT was significantly higher in overweight subjects compared with normal‐weight ones (p < 0.05). Furthermore, multivariate regression analysis in obese subjects revealed that fasting serum glucose was independently associated with IMT. Discussion: Obesity may be an important factor for carotid atherosclerosis, and at least some of the effects of obesity are independent of the BP levels. Fasting serum glucose levels in obese subjects may play an important role in carotid atherosclerosis.