Frequency of injury and the ecology of regeneration in marine benthic invertebrates

Many marine invertebrates are able to regenerate lost tissue following injury, but regeneration can come at a cost to individuals in terms of reproduction, behavior and physiological condition, and can have effects that reach beyond the individual to impact populations, communities, and ecosystems. For example, removal and subsequent regeneration of clams' siphons, polychaetes' segments, and brittlestars' arms can represent significant energetic input to higher trophic levels. In marine soft-sediment habitats, injury changes infaunal bioturbation rates and thus secondarily influences sediment-mediated competition, adult-larval interactions, and recruitment success. The importance of injury and regeneration as factors affecting the ecology of marine invertebrate communities depends on the frequency of injury, as well as on individual capacity for, and speed of, regeneration. A key question to answer is: "How frequently are marine benthic invertebrates injured?" Here, I review the sources and the frequencies of injury in a variety of marine invertebrates from different benthic habitats, discuss challenges, and approaches for accurately determining injury rates in the field, consider evidence for species-specific, temporal and geographic variation in injury rates, and present examples of indirect effects of injury on marine invertebrates to illustrate how injury and regeneration can modify larger-scale ecological patterns and processes.     

Clinical isolates of Enterococcus faecalis aggregate human platelets

Many endocarditis pathogens activate human platelets and this has been proposed to contribute to virulence. Here we report for the first time that many clinical isolates of Enterococcus faecalis, a common pathogen in infective endocarditis, aggregate human platelets. 84 isolates from human blood and urine were screened for their ability to aggregate platelets from four different donors. Platelet aggregation occurred for between 11 and 65% of isolates depending on the donor. In one donor, a significantly larger proportion of isolates from blood than from urine caused platelet aggregation. Median time to aggregation was 11 min and had a tendency to be shorter for blood isolates as compared to urine isolates. Immunoglobulin G (IgG) was shown to be essential in mediating activation and aggregation. Platelet aggregation could be abolished by an IgG-specific proteinase (IdeS), by an antibody blocking FcRγIIa on platelets, or by preabsorption of plasma with an E. faecalis isolate. Fibrinogen binding to bacteria or platelets does not contribute to platelet activation or aggregation under our experimental conditions. These results indicate that platelet activation and aggregation by E. faecalis is dependent on both host and bacterial factors and that it may be involved in the pathogenesis of invasive disease with this organism.     

Inositol pyrophosphates get the vip1 treatment

Inositol pyrophosphates are unique signaling molecules implicated in the regulation of diverse cellular processes. Two new studies by Mulugu et al. (2007) and Lee et al. (2007) extend the biological and metabolic diversity of this class of molecules. They identify yeast Vip1 as a new inositol pyrophosphate synthase and show that the products of Vip1 activity regulate a cyclin/cyclin-dependent kinase complex.     

Synthetic consolidants attacked by melanin-producing fungi: case study of the biodeterioration of Milan (Italy) cathedral marble treated with acrylics

Monuments and artistic stone surfaces are often consolidated and protected with synthetic polymers, in particular, acrylics. Although it is generally thought that acrylic polymers are resistant to biodeterioration, we report for the first time the systematic occurrence of dematiaceous meristematic fungi on many marble samples of the cathedral in Milan (Italy) previously treated with this material. Fourier transform infrared spectroscopy applied to the Milan cathedral stone samples revealed characteristic features of biodeteriorated synthetic resins that differentiated them from the aged but nonbiodeteriorated samples. Samples showing biological colonization were analyzed for the presence of fungi. Cultivation and morphological characterization and methods independent from cultivation, such as denaturing gradient gel electrophoresis coupled with partial 18S rRNA gene sequencing and immunofluorescence staining with melanin-binding antibodies, showed that melanin-producing species are heavily present on stone surfaces protected with acrylic resins. This observation raises the question of the effectiveness of acrylics in protecting stone artworks.