A case of colonization of a prosthetic mitral valve by Acremonium strictum

A case of colonization of a prosthetic mitral valve in a 73-year-old Spanish male by the fungus Acremonium strictum W. Gams is described. The valve was replaced due to paravalvular leak and severe insufficiency and the patient died of multiorgan failure. The identity of the fungus was determined by morphological studies and it was confirmed by the analysis of the ITS region sequence analysis. Molecular studies seem to demonstrate that A. strictum is a species complex. The case emphasizes the potential high risk of fungal infection for patients with prosthetic valves.     

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

Grazing rate estimates indicate that approximately half of the bacterivory in oligotrophic oceans is due to mixotrophic flagellates (MFs). However, most estimations have considered algae as a single group. Here we aimed at opening the black-box of the phytoflagellates (PFs) <20 μm. Haptophytes, chlorophytes, cryptophytes and pigmented dinoflagellates were identified using fluorescent in situ hybridization or by standard 4′,6-diamidino-2-phenylindole staining. Their fluctuations in abundance, cell size, biomass and bacterivory rates were measured through an annual cycle in an oligotrophic coastal system. On average, we were able to assign to these groups: 37% of the total pico-PFs and 65% of the nano-PFs composition. Chlorophytes were mostly picoplanktonic and they never ingested fluorescently labeled bacteria. About 50% of the PF <20 μm biomass was represented by mixotrophic algae. Pigmented dinoflagellates were the least abundant group with little impact on bacterioplankton. Cryptophytes were quantitatively important during the coldest periods and explained about 4% of total bacterivory. Haptophytes were the most important mixotrophic group: (i) they were mostly represented by cells 3–5 μm in size present year-round; (ii) cell-specific grazing rates were comparable to those of other bacterivorous non-photosynthetic organisms, regardless of the in situ nutrient availability conditions; (iii) these organisms could acquire a significant portion of their carbon by ingesting bacteria; and (iv) haptophytes explained on average 40% of the bacterivory exerted by MFs and were responsible for 9–27% of total bacterivory at this site. Our results, when considered alongside the widespread distribution of haptophytes in the ocean, indicate that they have a key role as bacterivores in marine ecosystems.     

Induction and preliminary characterization of intracellular β-glucosidases from a cellulolytic Streptomyces strain

Abstract The cellulolytic actinomycete Streptomyces sp. QM-B814 posasses an intracellular β-glucosidase system which is induced by cellobiose and carboxymethylcellulose. Maximal β-glucosidase activity was attained 8–10 h after inducer addition to exponential phase growing cultures. The induction is depressed in the presence of glucose. The system is composed of two electrophoretically different β-glucosidase forms showing relative molecular masses of about 60 and 35 kDa, and p I values in the range 4.2–4.5. Both β-glucosidases are synthesized de novo. The enzymes share substrate preference and are both inhibited by δ-gluconolactone and p -chloromercuribenzoate. The induction pattern and glucose inhibition are similar for both enzymes.     

The crystal structure of thrombin-activable fibrinolysis inhibitor (TAFI) provides the structural basis for its intrinsic activity and the short half-life of TAFIa

Mature thrombin-activable fibrinolysis inhibitor (TAFIa) is a highly unstable metallocarboxypeptidase that stabilizes blood clots by clipping C-terminal lysine residues from partially degraded fibrin. In accordance with its in vitro antifibrinolytic activity, animal studies have reported that inhibition of mature TAFI aids in the prevention of thrombosis. The level of TAFI activity is stringently regulated through (i) controlled proteolytic truncation of the zymogen (TAFI), generating the mature enzyme, TAFIa, and (ii) the short half-life of TAFIa. TAFI itself exhibits an intrinsic enzymatic activity, which is likely required to provide a baseline level of antifibrinolytic activity. The novel crystal structure presented here reveals that the active site of TAFI is accessible, providing the structural explanation for the its intrinsic activity. It also supports the notion that an "instability region" exists, in agreement with site-directed mutagenesis studies. Sulfate ions, bound to this region, point toward a potential heparin-binding site and could explain how heparin stabilizes TAFIa.     

Dispersion du Genre Homo au sud d’Ibérie et au Maghreb. Nouvelles données à propos des fossiles VM-1960 et BL-0

In this article, there is a discussion about out-of-Africa models of Homo dispersal, considering new findings, specially a new site with Oldowan industry in Morocco (Ain-Beni-Mathar), found in 2005 by some of the authors (Gibert J, Gibert L, and El Hamouti). There is also a critical of the models of Homo dispersal only based on carrion consumption. We also discuss some objections about two human remains from Orce sites (VM-1960 and BL-0) based on morphometric data (that, in any case, move these remains away from genus Homo), on authority criteria and ad hoc hypothesis, ignoring the decisive anatomical data.     

Evaluating the Flow-Cytometric Nucleic Acid Double-Staining Protocol in Realistic Situations of Planktonic Bacterial Death

Since heterotrophic prokaryotes play an important biogeochemical role in aquatic ecosystems and have a high capacity to survive in extreme environments, easy-to-perform protocols that probe their physiological states and the effects of environmental variables on those states are highly desired. Some methodologies combine a general nucleic acid stain with a membrane integrity probe. We calibrated one of these, the nucleic acid double-staining (NADS) protocol (G. Grégori, S. Citterio, A. Ghiani, M. Labra, S. Sgorbati, S. Brown, and M. Denis, Appl. Environ. Microbiol. 67:4662-4670, 2001), determining the optimal stain concentrations in seawater and the response to conditions that generate prokaryote death (such as heat) and to conditions that are known to produce death in plankton, such as nutrient limitation or flagellate grazing. The protocol was validated by comparison to two methods used to detect viability: active respiration by 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) and incorporation of tritiated leucine. We show that concentrations in the range of 5 to 20 μg ml⁻¹ of propidium iodide, simultaneous to a 10× concentration of Sybr green I, are best for detecting two separated populations of “live” (green cells) and “dead” (red cells) organisms. During exposure to heat and UVC, we observed that the number of live cells declined concurrently with that of actively respiring cells (CTC positive) and with total leucine incorporation. In seawater mesocosms, the NADS protocol allowed detection of bacterioplankton starvation-related death and flagellate predation. The protocol was also tested in deep profiles in the northwest Atlantic, demonstrating its potential for routine characterization of this fraction of the physiological diversity of marine heterotrophic prokaryotic plankton.     

Amyloidogenic properties of the prion protein fragment PrP(185-208): comparison with Alzheimer's peptide Abeta(1-28), influence of heparin and cell toxicity

Amyloid fibrils are a hallmark of Alzheimer’s and prion diseases. In both pathologies fibrils are found associated to glycosaminoglycans, modulators of the aggregation process. Amyloid peptides and proteins with very poor sequence homologies originate very similar aggregates. This implies the possible existence of a common formation mechanism. A homologous structural motif has recently been described for the Alzheimer’s peptide Aβ(1-28) and the prion protein fragment PrP(185-208). We have studied the influence histidine residues and heparin on the aggregation process of both peptides and determined the possible amyloid characteristics of PrP(185-208), still unknown. The results show that PrP(185-208) forms amyloid aggregates in the presence of heparin. Histidines influence the aggregation kinetics, as in Aβ(1-28), although to a lesser extent. Other spectroscopic properties of the PrP(185-208) fragment are shown to be equivalent to those of other amyloid peptides and PrP(185-208) is shown to be cytotoxic using a neuroblastoma cell line.     

Plasma fatty acid binding protein 4 is associated with atherogenic dyslipidemia in diabetes

The aim of this study was to evaluate the impact of adipocyte fatty acid binding protein 4 (FABP4) on the lipid profile in type 2 diabetic subjects. Plasma levels of FABP4 and adiponectin and an extensive lipid profile were analyzed in 169 type 2 diabetic subjects and 105 controls. Type 2 diabetic subjects were categorized according the presence of atherogenic dyslipidemia. Univariate statistical analyses, partial correlation tests, and binary logistic regression models were applied. In type 2 diabetic subjects, FABP4 was positively correlated with plasma triglycerides (P = 0.007), apolipoprotein C-III (apoC-III) (P = 0.009), and all the components of triglyceride-rich lipoproteins, including VLDL triglycerides (P = 0.002), VLDL-cholesterol (P = 0.001), and VLDL apoB (P = 0.001). FABP4 was inversely correlated with apoA-I (P = 0.038), HDL-cholesterol (P = 0.002), and HDL apoA-I (P = 0.010) in type 2 diabetic subjects. These correlations are not significantly affected by age, gender, body mass index, adiponectin, insulin, or any pharmacological treatment. The associations are even stronger when the FABP4/adiponectin ratio is considered. None of these associations were observed in controls. High FABP4 and low adiponectin levels are independent predictors of atherogenic dyslipidemia. In conclusion, FABP4 plasma concentrations hold strong potential for development as a clinical biomarker for atherogenic dyslipidemia, independent of obesity and insulin resistance, in type 2 diabetic subjects.     

Structure of ground-foraging ant assemblages in relation to land-use change in the northwestern Mediterranean region

The abandonment by humans of marginal and less productive zones signifies an important change in land use in North Mediterranean agroecosystems. Human perturbations have led to a highly diversified landscape, with a mosaic made up of patches of land at different stages of succession, from cultivated fields to closed forest. Our aim here is to characterize ant assemblages and their functional groups in response to these land-use changes. This progressive abandonment results in an initial increase in ant richness and abundance, which can reach high levels if the succession proceeds as far as woodland. In terms of the ant functional groups, this land-use change implies: (1) the appearance of Subordinate Camponotini; (2) an increase in Generalized Myrmicinae, Cryptics and Cold-climate specialists in terms of ant species richness, overall abundance and, for Generalized Myrmicinae and Cryptics, an increase in abundance percentage; (3) a decrease in percentage abundance of Opportunists; (4) a progressive decrease in species richness as well as overall and percentage abundance of Hot-climate Specialists throughout the transformation from crops to woodlands; and (5) an initial increase of Dominant Dolichoderinae followed by a decrease in ant species richness, overall abundance and percentage abundance. Using the ant functional group approach for the clearly separate stages of the regeneration process is a promising method for comparing responses of ant communities to human land use.