Greening of the coasts: a review of the Perna viridis success story

The green mussel Perna viridis has been receiving a lot of attention from workers working in the research areas of intertidal ecology, aquaculture, pollution monitoring, biofouling, zoogeography and invasion biology. P. viridis is a remarkable species in terms of its ability to reach very high biomass levels, to withstand environmental fluctuations, to concentrate a variety of organic and inorganic environmental pollutants, to colonise artificial marine habitats and to invade new geographic territories. This review collates data available on salient aspects of the distribution, biology and ecology of P. viridis. It is argued that the remarkable success of P. viridis as an invasive species basically stems from its long larval duration, fast growth rate, high fecundity, early maturity, high productivity and ability to withstand fluctuating environmental conditions (temperature, salinity, water turbidity and pollutants). Relevant aspects of the data are compared with the data available for a similar species Perna perna, which too is an invasive species, but to a more limited extent.     

Delta-9-tetrahydrocannabinol and human spermatozoa

Thein vitro effect of δ⁹-tetrahydrocannabinol on adenosine triphosphatase and phosphodiesterase activities as well as on the cyclic-AMP content of human spermatozoa has been studied. At a concentration of 1.0 ▪g, sperm metabolism may be increased as shown by increased cyclic AMP and adenosine-triphosphatase activity while at a higher concentration (10 ▪g tetrahydrocannabinol), it may be reversed.     

The Pleiades are a cluster of fungal effectors that inhibit host defenses

Biotrophic plant pathogens secrete effector proteins to manipulate the host physiology. Effectors suppress defenses and induce an environment favorable to disease development. Sequence-based prediction of effector function is impeded by their rapid evolution rate. In the maize pathogen Ustilago maydis, effector-coding genes frequently organize in clusters. Here we describe the functional characterization of the pleiades, a cluster of ten effector genes, by analyzing the micro- and macroscopic phenotype of the cluster deletion and expressing these proteins in planta. Deletion of the pleiades leads to strongly impaired virulence and accumulation of reactive oxygen species (ROS) in infected tissue. Eight of the Pleiades suppress the production of ROS upon perception of pathogen associated molecular patterns (PAMPs). Although functionally redundant, the Pleiades target different host components. The paralogs Taygeta1 and Merope1 suppress ROS production in either the cytoplasm or nucleus, respectively. Merope1 targets and promotes the auto-ubiquitination activity of RFI2, a conserved family of E3 ligases that regulates the production of PAMP-triggered ROS burst in plants.     

Effects of alkyltin compounds on hydrogen-oxidizing anaerobic bacteria

Methyl and butyltin compounds were inhibitory to all anaerobes examined, but there were great variations, depending on the specific alkyltin and bacterium. The methanogens were inhibited more strongly by methyl than by butyl derivatives; more than 50% inhibition occurred with 0.025–0.5 mM of the methyltins, whereas 0.16–1.8 mM butyltins were needed for the same level of inhibition; tri-butyltin was the least toxic.Methanosarcina barkeri was, in general, more resistant than theMethanococcus sp. andMethanobacterium bryantii. TheDesulfovibrio were more strongly inhibited by mono-methyltin than by di- and tri-methyl derivatives; butyltins were, in general, not so toxic. Mono-methyltin at 0.15 mM almost completely inhibited three of the sulfate reducers, butDesulfovibrio thermophilus required 0.7 mM for this level of inhibition. Tri-butyltin at 1.8 mM did not cause major inhibition, whereas mono- and di-butyltins were more inhibitory.Acetobacterium woodii was most affected by mono- and dimethyltins, and least by tri-methyltin and mono-butyltin. In contrast,Wollinella succinogenes was most affected by tri-methyltin. This study suggests several major groups of anaerobes thought to be involved in metal biocorrosion vary greatly in their response to alkyltins; most interesting is the relative insensitivity by methanogens and sulfate reducers to tri-butyltin, which is a major component in commercial antifouling paints. Our results differ considerably from those reported for aerobic microorganisms, which were found to be most affected by tributyltin.     

Nitrate as a sole nitrogen source forMethanococcus thermolithotrophicus and its effect on growth of several methanogenic bacteria

Methanococcus (Mc.) thermolithotrophicus can use nitrate as the sole source of nitrogen, but four other species of methanogens cannot. The growth rate was similar on both nitrate and ammonium, but yields were 20–25% lower on nitrate.Mc. thermolithotrophicus, Methanobacterium thermoautotrophicum, andMethanobrevibacterium smithii were not inhibited by 20 mM nitrate, butMethanospirillum hungatei was inhibited 35%, andMethanosarcina barkeri was completely inhibited by 20 mM nitrate. WhenMc. thermolithotrophicus was growing with nitrate as the sole source of nitrogen, growth was dependent on either molybdenum or tungsten, and the presence of both gave the best growth response; vanadium or chromium did not replace the requirement for these metals. Growth on ammonium could not be strictly demonstrated to require either of these metals, but both molybdenum and tungsten stimulated growth.     

Ectopic Expression of eIF-4E in Human Colon Cancer Cells Promotes the Stimulation of Adhesion Molecules by Transforming Growth Factorβ

Transforming growth factor β1 (TGFβ) inhibits cellular proliferation, promotes differentiation, and stimulates the expression and secretion of the extracellular matrix adhesion molecules fibronectin and laminin and the colon-associated intercellular adhesion molecule carcinoembryonic antigen. This is collectively called the TGFβ-mediated adhesion response and occurs in the human colon cancer cell line Moser while the cell line KM12SM is relatively unresponsive to TGFβ. We have previously shown that TGFβ rapidly stimulates protein kinase C (PKC) phosphotransferase activity in the Moser cells and that the induction of the adhesion response (but not antiproliferation) by TGFβ is dependent on PKC. Because resistance to growth factors may be due to translational suppression and the translation initiation factor eIF-4E may alleviate translational suppression, we determined the effect of eIF-4E expression on the responses of Moser and KM12SM cells to TGFβ. Ectopic expression of eIF-4E in the TGFβ-responsive Moser cells enhanced the activation of PKC by TGFβ and the induction of the adhesion response, especially the secretion of adhesion molecules, but not the antiproliferative response. Ectopic expression of eIF-4E in the TGFβ-resistant KM12SM cells increased TGFβ stimulation of PKC and the TGFβ-mediated adhesion response (but not antiproliferation). The secretion of adhesion molecules was significantly increased by TGFβ. These results showed in these cells that eIF-4E promotes TGFβ-regulated adhesion but not antiproliferation in a PKC-dependent manner.