Alternative food sources of native and non-native bivalves in a subtropical eutrophic lake

The aim of this study was to evaluate the consumption of alternative food sources (water column and sediment) and the potential competition under different conditions between Diplodon parallelopipedon (native) and Corbicula fluminea (non-native). We evaluated filtration and ingestion rates of water column at 6 and 24 h, held with and without organic matter and different phytoplankton types: needle-shaped green algae (Ankistrodesmus sp.) and filamentous cyanobacteria (Planktothrix agardhii) dominated communities. Our results confirmed higher filtration and ingestion rates per biomass unit for C. fluminea in the presence of sediment without organic matter. However, when we compared the filtration of bivalves held in sediment with organic matter, D. parallelopipedon rates were not significantly different from C. fluminea values. Moreover, in the presence of filamentous cyanobacteria, only C. fluminea filtration and ingestion rates decreased significantly. Our experimental results and previous field evidence concur that C. fluminea were not able to outcompete the native bivalves in organic matter rich sediment and cyanobacteria blooms conditions. The differential responses to the eutrophication process between exotic and native bivalves, apparently favoring the later, might buffer the potential competition interactions allowing their coexistence.     

Estimation of sex from the hyoid body in skeletal individuals from archeological sites

Recent forensic studies have shown that the hyoid bone is a sexually dimorphic element of the human skeleton. Given the advanced techniques of collecting human remains in archeological and forensic contexts, the recovery of hyoid bones is now more frequent in skeletal samples. For that reason the authors propose a new method for estimating sex based on hyoid bodies from archeological sites.     

Cell-to-cell spread of Borna disease virus proceeds in the absence of the virus primary receptor and furin-mediated processing of the virus surface glycoprotein

Borna disease virus (BDV) is an enveloped virus with a nonsegmented negative-strand RNA genome whose organization is characteristic of Mononegavirales. BDV cell entry follows a receptor-mediated endocytosis pathway, which is initiated by the recognition of an as-yet-unidentified receptor at the cell surface by the virus glycoprotein G. BDV G is synthesized as a precursor (GPC) that is cleaved by the cellular protease furin to produce the mature glycoproteins GP1 and GP2, which have been implicated in receptor recognition and pH-dependent fusion events, respectively. BDV is highly neurotropic and its spread in cultured cells proceeds in the absence of detectable extracellular virus or syncytium formation. BDV spread has been proposed to be strictly dependent on the expression and correct processing of BDV G. Here we present evidence that cell-to-cell spread of BDV required neither the expression of cellular receptors involved in virus primary infection, nor the furin-mediated processing of BDV G. We also show that in furin-deficient cells, the release of BDV particles induced by the treatment of BDV-infected cells with hypertonic buffer was not significantly affected, while virion infectivity was dramatically impaired, correlating with the decreased incorporation of BDV G species into viral particles. These findings support the view that the propagation of BDV within the central nervous systems of infected hosts involves both a primary infection that follows a receptor-mediated endocytosis pathway and a subsequent cell-to-cell spread that is independent of the expression of the primary receptor and does not require the processing of BDV G into GP1 and GP2.     

Generation and characterization of a recombinant vesicular stomatitis virus expressing the glycoprotein of Borna disease virus

Borna disease virus (BDV) is an enveloped virus with a nonsegmented negative-strand RNA genome whose organization is characteristic of mononegavirales. However, based on its unique genetics and biological features, BDV is considered to be the prototypic member of a new virus family, Bornaviridae, within the order Mononegavirales. BDV cell entry occurs via receptor-mediated endocytosis, a process initiated by the recognition of an as yet unidentified receptor at the cell surface by the BDV surface glycoprotein (G). The paucity of cell-free virus associated with BDV infection has hindered studies aimed at the elucidation of cellular receptors and detailed mechanisms involved in BDV cell entry. To overcome this problem, we generated and characterized a replication-competent recombinant vesicular stomatitis virus expressing BDV G (rVSVDeltaG*/BDVG). Cells infected with rVSVDeltaG*/BDVG produced high titers (10(7) PFU/ml) of cell-free virus progeny, but this virus exhibited a highly attenuated phenotype both in cell culture and in vivo. Attenuation of rVSVDeltaG*/BDVG was associated with a delayed kinetics of viral RNA replication and altered genome/N mRNA ratios compared to results for rVSVDeltaG*/VSVG. Likewise, incorporation of BDV G into virions appeared to be restricted despite its high levels of expression and efficient processing in rVSVDeltaG*/BDVG-infected cells. Notably, rVSVDeltaG*/BDVG recreated the cell tropism and entry pathway of bona fide BDV. Our results indicate that rVSVDeltaG*/BDVG represents a unique tool for the investigation of BDV G-mediated cell entry, as well as the roles of BDV G in host immune responses and pathogenesis associated with BDV infection.     

Vasoactive intestinal peptide enhances growth and angiogenesis of human experimental prostate cancer in a xenograft model

We show that vasoactive intestinal peptide (VIP) exerts trophic and proangiogenic activities in experimental prostate cancer in vivo. Nude mice were subcutaneously injected with Matrigel impregnated with LNCaP prostate cancer cells. Cell treatment with 100 nM VIP for 1h before xenograft resulted in increased tumor growth after 8 and, more remarkably, 15 days of injection. The same occurred with the mRNA expression of the main angiogenic factor, vascular endothelial growth factor (VEGF), as shown by real-time RT-PCR quantification. The proangiogenic activity of VIP was further established by showing increases of hemoglobin levels, Masson trichromic staining, and immunohistochemical CD34 staining in tumors excised 15 days after subcutaneous injection of VIP-treated cells as compared to control conditions. All these parameters indicate that VIP increases vessel formation. This xenograft model is a useful tool to study in vivo the effects of VIP-related peptides in tumor growth and development of blood supply as well as their therapeutical potential in prostate cancer.     

Expression and one-step purification of recombinant Arabidopsis thaliana frataxin homolog (AtFH)

Frataxin, a nuclear-encoded mitochondrial protein, has been proposed to participate in Fe-S cluster assembly, mitochondrial energy metabolism, respiration, and iron homeostasis. However, its precise function remains elusive. Frataxin is highly conserved in living organisms with no major structural changes, in particular at the C-terminal protein domain, suggesting that it plays a key function in all organisms. Recently, a plant gene, AtFH, with significant homology to other members of the frataxin family has been described. To gain insight on the frataxin role in plants, the frataxin domain was expressed in Escherichia coli BL21-codonPlus (DE3)-RIL cells and purified using a Ni-chelating column. The purified protein, added to a mixture containing Fe(II) and H2O2, attenuates the Fenton reaction indicating that the recombinant plant frataxin is functional. The procedure described here produced high yield of 99% pure protein through only one chromatographic step, suitable for further structure-function studies.     

Phylogenetic reconstruction from non-genomic data

MOTIVATION: Recent results related to horizontal gene transfer suggest that phylogenetic reconstruction cannot be determined conclusively from sequence data, resulting in a shift from approaches based on polymorphism information in DNA or protein sequence to studies aimed at understanding the evolution of complete biological processes. The increasing amount of available information on metabolic pathways for several species makes it of greater relevance to understand the similarities and differences among such pathways. These similarities can then be used to infer phylogenetic trees not based exclusively in sequence data, therefore avoiding the previously mentioned problems. RESULTS: In this article, we present a method to assess the structural similarity of metabolic pathways for several organisms. Our algorithms work by using one of the three possible enzyme similarity measures (hierarchical, information content, gene ontology), and one of the two clustering methods (neighbor-joining, unweighted pair group method with arithmetic mean), to produce a phylogenetic tree both in Newick and graphic format. The web server implementing our algorithms is optimized to answer queries in linear time. AVAILABILITY: The software is available for free public use on a web server, at the address http://www.jaist.ac.jp/~clemente/cgi-bin/phylo.pl. It is available on demand in source code form for research use to educational institutions, non-profit research institutes, government research laboratories and individuals, for non-exclusive use, without the right of the licensee to further redistribute the source code.     

Seed bank dynamics of two obligate seeders, <Emphasis Type="Italic">Cistus monspeliensis</Emphasis> and <Emphasis Type="Italic">Rosmarinus officinalis</Emphasis>, in relation to time since fire

Many species in Mediterranean-type ecosystems regenerate after fire by seed germination from soil seed banks. Seed bank dynamics of two of those obligate seeders, Cistus monspeliensis and Rosmarinus officinalis, were investigated in relation to stand age since fire in southwestern Portugal. Soil seed density, annual seed input, annual seed losses through germination and seed persistence were compared between species at stands differing in age since fire (5, 10 and 35 years). Soil seed density and seed input increased over the first decade after fire and were lowest at 35-year-old stands for C. monspeliensis. In R. officinalis, few seeds were produced and found in the soil at early stages, and maximum seed input and soil seed density were attained at 35-year-old stands. Soil seed density was mostly driven by seed production in both species, which is largely dependent on plant traits and population dynamics related to fire. Overall, stand age since fire had a negligible effect on seed germination, seed persistence and viability. Ten to 39% of buried seeds were not recovered after 1 year, and viability of seeds recovered was 97–100% for C. monspeliensis and only 0–3% for R. officinalis. Variation in plant traits within the seeder syndrome was evidenced by this study. R. officinalis evidenced lower seed persistence, lower proportion of viable seed produced and lower density of viable soil seed than C. monspeliensis at any stage after fire. R. officinalis is expected to depend largely on previous year seed production for population replacement after fire.     

Crystal structure of a soluble form of human monoglyceride lipase in complex with an inhibitor at 1.35 Å resolution

A high-resolution structure of a ligand-bound, soluble form of human monoglyceride lipase (MGL) is presented. The structure highlights a novel conformation of the regulatory lid-domain present in the lipase family as well as the binding mode of a pharmaceutically relevant reversible inhibitor. Analysis of the structure lacking the inhibitor indicates that the closed conformation can accommodate the native substrate 2-arachidonoyl glycerol. A model is proposed in which MGL undergoes conformational and electrostatic changes during the catalytic cycle ultimately resulting in its dissociation from the membrane upon completion of the cycle. In addition, the study outlines a successful approach to transform membrane associated proteins, which tend to aggregate upon purification, into a monomeric and soluble form.