Valerio Zupo

Biological succession on silicone fouling‐release surfaces: Long‐term exposure tests in the harbour of ischia, Italy

A static test site was set up in the Harbour of Ischia (Gulf of Naples, Italy) to investigate the antifouling effectiveness of newly developed non‐polluting coatings. Two‐year exposure experiments were performed on sets of panels coated with silicone‐based coatings, and results were compared both to sets of panels coated with toxic agents, and non‐toxic epoxydic compounds. Abiotic factors, strength of adhesion of the temporal dynamics of succession of foulers were analyzed throughout the period of immersion. Brown algae constantly represented the “border point”; between the early community, dominated by sume, micro‐ and macroalgae, and the late community, mainly represented by bryozoans and molluscs, as well as polychaetes, sponges and tunicates. Brown algae, such as Ectocarpus siliculosus, tunicates (mainly Botryllus schlossen) and polychaetes (Hydroides elegans, Pileolaria pseudomilitaris) were demonstrated to be key species, triggering the community and influencing its development. Light was the main abiotic factor discriminating the community on the two sides of panels exposed to different irradiances. The best performing coatings (silicone easy release coatings without additives) substantially influenced community structure, shifting it to the earliest stages of colonization. Silicone coatings proved to be unsuitable for colonization by organisms typical of mature communities, due to their low energy surfaces. The results of the present paper demonstrate that silicone coatings technology represents an alternative to the use of biocidal antifouling paints.

Biofouling and barnacle adhesion data for fouling-release coatings subjected to static immersion at seven marine sites

Little is known about the performance of fouling‐release coatings at different geographical locations. An investigation was designed to measure the differences in biofouling and biofouling adhesion strength on three known silicone formulations and an epoxy control at seven static immersion sites located in California, Florida, Hawaii, Hong Kong, India, Italy and Singapore. The study found that whilst the relative performance of the coatings was similar at each site, there were statistically significant differences in the type and intensity of fouling that developed on the coatings and in barnacle adhesion strength among sites. The results emphasize the importance of evaluating potential coatings at more than one static immersion site.

Strategies of sexual inversion in Hippolyte inermis Leach (Crustacea, Decapoda) from a Mediterranean seagrass meadow

The population of the shrimp Hippolyte inermis Leach was investigated for one year along a transect through a bed of Posidonia oceanica (L.) Delile. Two reproductive periods per year were observed and two types of females were identified, one type is small, does not pass through a male stage and spawns in September to produce the next years male generation. The other is large, passes through a male stage, and spawns in April to produce sufficient males and females for the reproductive period in September. This unusual strategy of sexual inversion could be an adaptation to overcome problems related to predation pressure and seasonal availability of food in P. oceanica seagrass meadows.

Metabolite profiling of the benthic diatom Cocconeis scutellum by GC-MS

Cocconeis scutellum is a benthic diatom producing one or more compounds responsible for the early programmed cell death (apoptosis) of the male gonad and the androgenic gland of the protandric shrimp Hippolyte inermis Leach. The metabolite composition of both the ether and butanol extracts was studied by gas chromatography-mass spectrometry (GC-MS) in both electron impact (EI) and chemical ionization (CI) mode. The compounds were identified as trimethylsilyl (TMSi) derivatives. The structure of the fatty acids (FA) was confirmed after conversion to their methyl esters. The ether fraction of C. scutellum contained FA (76%), of which 30% were saturated (SFA), 24% monounsaturated (MUFA) and 22% polyunsaturated (PUFA). Mono- (8%) and diglycerides (3%) as well as sterols (5%) and isoprenoid compounds (4%) were also found in this fraction. The butanol extract consisted of FA (45%), carbohydrates (25%), amino acids and N-containing metabolites (10%), fatty alcohols (9%), glycerides (4%) and organic acids (3%). In the literature, many reports deal with the chemistry and the chemical ecology of planktonic diatoms; contrastingly, benthic species are still less studied, especially with respect to their chemical composition, due to their difficult cultivation. Hence, our investigation represents a preliminary approach to clarify on chemical bases the ecological role of Cocconeis on decapods in the marine benthos, as well as a description of the metabolic pattern of this benthic diatom.

Do benthic and planktonic diatoms produce equivalent effects in crustaceans

Hippolyte inermis Leach 1814 is a benthic shrimp characterized by a peculiar mechanism of sex reversal influenced by diatom foods. In fact, the appearance of primary females in spring is due to an apoptotic early disruption of the androgenic gland and of the male gonad, triggered by still unknown compounds present in diatoms of the genus Cocconeis. The influence of diatoms on the reproductive ecology and life cycle of planktonic crustaceans has been demonstrated previously: some planktonic diatoms produce aldehydes inducing apoptosis in the embryos and in the larvae of marine copepods, reducing their viability. Both benthic and planktonic diatoms therefore produce compounds having an apoptotic effect on some tissues of target crustaceans, although the ecological significance of the two processes is different: deleterious for copepod populations, regulative for shrimps associated with Posidonia oceanica. In the present article we experimentally administered specific planktonic diatoms, their fractions and compounds known to induce apoptosis in planktonic copepods, to H. inermis postlarvae, to check whether the apoptotic effect is due to an identical family of diatom compounds, and to establish whether the processes observed in the plankton and in the benthos, respectively, are analogous or homologous, from an ecological point of view. Our results indicated that diatom compounds acting in the two systems are different, since both planktonic diatoms and their aldehydes had negligible effects on the sex ratios of cultured shrimps.

Apoptotic activity of the marine diatom Cocconeis scutellum and eicosapentaenoic acid in BT20 cells

Context: The marine diatoms Cocconeis scutellum Ehrenberg (Bacillariophyceae) are known to trigger apoptosis in the androgenic gland of the Mediterranean crustacean Hippolyte inermis Leach (Decapoda), affecting the shrimp’s sex reversal. Objective: The aim of this study was to evaluate a possible apoptotic effect of extracts and fractions from these microalgae also on human tissues. Materials and methods: The chemical profile of C. scutellum was determined by gas chromatography-mass spectrometry (GC-MS) and, afterwards, organic extracts and fractions from the diatoms were used to treat to breast cancer BT20 cells. Double labeling with annexin V-FITC and isotonic propidium iodide (PI) along with flow cytometry analysis enabled the evaluate of cell apoptosis and viability, whereas hypotonic PI staining was used to analyze the cell cycle in BT20 lines. The involvement of specific caspases was studied by Western blotting. Results: Results demonstrated that the diethyl ether extract and, in particular, fraction 3, the richest fraction in eicosapentaenoic acid (EPA) from the diethyl ether extract, selectively induced apoptosis (up to 89.2% at 1 μg/well of fraction 3) and decreased viability in BT20 cells. The apoptotic effect was displayed in a concentration and time-dependent manner, by activating caspases-8 and 3, and arresting the progression of the cell cycle from S to G2-M phase. EPA alone showed similar apoptotic effects in BT20 cells. Discussion and conclusion: The study demonstrates the apoptotic activity of C. scutellum diatoms on breast cancer cells and suggests their potential use as a source of apoptotic compounds.

Experimental evidence of a sex reversal process in the shrimp Hippolyte inermis

Summary Hippolyte inermis Leach 1815 is a shrimp which forms stable populations in seagrass meadows of the Mediterranean Sea and along the Atlantic coast of Spain. Investigations from the last century have demonstrated specimens experiencing a male stage prior to switching to females (i.e., protandric sex reversal). Further studies have demonstrated that not all females are derived from sex reversal: young females apparently deriving from direct differentiation are present in natural populations. In recent years some authors have claimed that the species is simply gonochoristic, mainly based on the absence of ovotestis development. In order to establish if the species is a peculiar hermaphrodite or a simple gonochoristic, H. inermis postlarvae were individually cultured in Petri dishes in a semi-closed system. Their exuviae were regularly collected, fixed and stained, to monitor the sex and the size of each individual over time. In addition, histological sections were examined and we observed an individual who lost its appendix masculine and developed an active ovary. In contrast, specimens that retained their appendices masculinae exhibited a male reproductive system. Fourteen such individuals who lost their appendices masculinae were observed throughout the experiment, suggesting a mechanism of sex reversal in decapod crustaceans in which an ovotestis may be absent during the transition to the opposite sex.

Feeding ecology of platynereis dumerilii (audouin & milne-edwards) in the seagrass posidonia oceanica system: The role of the epiphytic flora (Polychaeta, nereididae)

Abstract The feeding ecology and the ecological role of the herbivorous polychaete Platynereis dumerilii (Audouin & Milne-Edwards) (Nereididae) in the epiphytic community of the Mediterranean seagrass Posidonia oceanica (L.) Delile was investigated under natural and laboratory conditions. Experiments were devised to define the preferred items, their consumption rate and degree of assimilation of chlorophylls. Results of faecal pellets analyses, food-choice experiments and photosynthetic pigment analyses demonstrated that P. dumerilii feeds preferentially on erect filamentous algae. Worms of length above 10 mm may graze also on living tissue of Posidonia leaves, when starved. This behaviour has rarely been reported for invertebrates, and especially for poly-chaetes in Posidonia ecosystems. Small individuals had a lower feeding rate on large macroalgae (e.g., Cystoseira), but higher digestive efficiency. Platynereis dumerilii thus feeds preferentially on erect micro- and macroalgae which are more easily cut by the jaws of its eversible pharynx. This selective herbivore thus has a special microniche, with respect to other mesograzers inhabiting the Posidonia meadows.

Experimental intensive culture of Penaeus monodon in the cold-temperate climate of the North-East coast of Italy (a fishery valle of the River Po Delta)

Abstract An intensive culture trial was conducted with the black tiger shrimp, Penaeus monodon Fabricius, on the North-East coast of Italy, characterized by a cold temperate climate. The culture was carried out in two steps: a pre-growing phase in fibreglass tanks lasting 31 days, and a 71-day grow-out phase (stocking density of 9.1 individuals m −2 ) in an earthen pond (0.79 ha). Survival rate was 55.4% during the first phase and 73.8% during the second phase, with an overall 40.9% recovery rate at the end of the trial. Average final weight was 17.9 g with a monthly wet weight increase of 7.49 g during the grow-out phase; production in the pond reached 1208 kg·ha −1 in 71 days. Temperature appeared to be the main environmental factor influencing the intensive culture process.

Apoptogenic Metabolites in Fractions of the Benthic Diatom Cocconeis scutellum parva

Benthic diatoms of the genus Cocconeis contain a specific apoptogenic activity. It triggers a fast destruction of the androgenic gland in the early post-larval life of the marine shrimp Hippolyte inermis, leading to the generation of small females. Previous in vitro investigations demonstrated that crude extracts of these diatoms specifically activate a dose-dependent apoptotic process in human cancer cells (BT20 breast carcinoma) but not in human normal lymphocytes. Here, a bioassay-guided fractionation has been performed to detect the apoptogenic compound(s). Various HPLC separation systems were needed to isolate the active fractions, since the apoptogenic metabolite is highly active, present in low amounts and is masked by abundant but non-active cellular compounds. The activity is due to at least two compounds characterized by different polarities, a hydrophilic and a lipophilic fraction. We purified the lipophilic fraction, which led to the characterization of an active sub-fraction containing a highly lipophilic compound, whose molecular structure has not yet been identified, but is under investigation. The results point to the possible medical uses of the active compound. Once the molecular structure has been identified, the study and modulation of apoptotic processes in various types of cells will be possible.