Biomedical subjects

Rocky De Nys

Publications and source records attributed to Rocky De Nys.

3 recordsLinked to original sources

PubMed2003

Microtopography and antifouling properties of the shell surface of the bivalve molluscs Mytilus galloprovincialis and Pinctada imbricata.

Biofouling rapidly covers most submerged surfaces in the marine environment. However, some marine organisms remain clean despite strong fouling pressure. Potential physical inhibitors of fouling were investigated by comparing the thickness, cover, and microtopographic structure of the periostracum of two bivalve molluscs, the blue mussel, Mytilus galloprovincialis, and the pearl oyster, Pinctada imbricata. The cover and thickness of the periostracum were measured on four size classes of each species using histological and microscopic techniques. The periostracum of M. galloprovincialis was significantly thicker than that of P. imbricata and did not differ significantly between size classes. In contrast, the periostracum of P. imbricata decreased significantly with increasing size in both thickness and cover. The microtopography of the shell surface of both species was measured using atomic force microscopy (AFM) and scanning electron microscopy (SEM), which revealed a homogeneous ridged surface for M. galloprovincialis with a uniform distance of 1-2 microns between ridges with a mean depth of 1.5 microns. P. imbricata had a heterogeneous surface structure without a repeating structural pattern. To compare the potential antifouling properties of the shell surface the four size classes of both species were tested in fourteen-week field exposure trials. M. galloprovincialis was rarely fouled over the trial period with less than 10% of M. galloprovincialis shell across all size classes being fouled. In contrast, P. imbricata had significantly higher levels of fouling. Both the proportion of P. imbricata shells fouled and the density of fouling organisms were positively correlated with the age of the shell and the amount of intact periostracum. The relationship between the shell surface microtopography and the intensity of fouling is discussed.

Animal Structures↗

PubMed2003

The effects of foul-release coatings on the settlement and behaviour of cyprid larvae of the barnacle Balanus amphitrite amphitrite Darwin.

Foul-release coatings are generally assumed to affect fouling of surfaces via interfering with adhesion of fouling organisms. However, the potential effects of these coatings on other aspects of the biology of fouling organisms such as behaviour have not in general been explored. The effects of wax-based foul-release coatings containing silicone oil on the settlement and behaviour of cyprid larvae of the barnacle Balanus amphitrite were studied. Settlement (as measured by metamorphosis) of cyprids was strongly inhibited on all coatings but particularly on those containing silicone oil at concentrations of 5% or more. The behaviour of cyprids was also altered on coatings containing > or = 5% silicone oil, with cyprids assuming an inverted position, preventing adhesion. This effect was reversible in part; when cyprids exposed to experimental coatings for 1 d were transferred to uncoated surfaces their behaviour returned to normal, except that metamorphosis did not occur. The results indicate that model foul-release coatings containing wax and silicone oil can affect settlement and behaviour, as well as adhesion.

Animals↗

PubMed2002

Chemical cues for surface colonization.

Colonization of surfaces in marine benthic environments is often one of the most significant moments in the life history of benthic organisms, representing, for example, a change from a planktonic to a benthic existence, a shift from a mobile to a sessile life form, or the initiation of pathogenesis. Many of the surfaces that are colonized are, in fact, other marine organisms, and in a general sense there is widespread evidence that specific chemical cues derived from marine organisms affect colonization by both marine prokaryotes and eukaryotes. However, detailed information for any one system on the nature of such cues, their distribution in situ, and their effects on the demography of colonizers is rare. Here, we selectively review the literature on chemical cues for colonization in the sea, focussing on contrasts between positive (inducers) and negative (inhibitors, deterrents) cues and on prokaryote/eukaryote interactions. We also consider whether generalized life history or natural history characteristics of colonizers (i.e., the mobility of a propagule, the extent to which a species is a habitat generalist or specialist, etc.) affect their response to chemical cues, and we touch briefly on some recent highlights relevant to the critical interplay between hydrodynamics and chemistry. A number of important methodological concerns are now being addressed through the introduction of field assays and analyses for chemical cues, and through molecular techniques for the characterization of microbial biofilms. These developments are encouraging, as is the increasingly multidisciplinary and cross-taxonomic approach to research in this area.

Animals↗