Untitled - CNR

Marine research at CNRful culture/maintainance of echinoderms inthe laboratory have been established sincemany years, a necessary prerequisite forany organisms to be adopted as modelfor bioassays. Thus, also by virtue oftheir commercial importance and consideringtheir abundance and wide distribution,echinoderms are emerging as new potentialsentinel organisms able to perceiveenvironmental hazards. Figure 1 showsthe most commonly used among echinoderms,namely sea urchin and sea staradults, embryos, larvae and adult immunecells (coelomocytes). A good number ofstudies have focused on effects of chemicalson sea urchin embryos or larvae and ondevelopment of molecular biomarkers forthe detection of the risk to metal exposure[3, 4, 5, 6, 7, 8]. In the following we willreview our research activities related to theuse of the model organism of choice in ecotoxicologicaland biomolecular tests, bothin field and laboratory studies.3 Field studies3.1 Oceanographic campaignsIt is well known that some heavy metalsoccur naturally in the ecosystem withlarge variations in concentration and yet,in some cases, they have vital or beneficialeffects on living organisms. In moderntimes, large amounts of heavy metals havebeen introduced in the ecosystem by anthropogenicsources and, since they arenon-biodegradable and persist in the environmentfor long periods, can have seriousecotoxicological impacts. This poses amain challenge in the assessment of potentialremediation procedures which areunder study.In 1995, we began to be interested in assessingmarine pollution, when we tookpart to an EU Summer Course on “Monitoringof environmental stress using moderntechniques”. In that context, Paracentrotuslividus sea urchin coelomocyteswere used for the first time for monitoringenvironmental stress. In those pioneeringstudies, we analysed and validated a fewcellular and molecular markers of stress,opening the way to other field studiesand introducing sea urchin coelomocytesas biosensors of environmental stress [9].Coelomocytes are a population of differentcells types that freely circulate in the bodyfluid of the adult coelom. They representthe echinoderm defence system, which reactsto injuries, host invasion and adverseconditions [10, 11, 12, 13, 14, 15]. Variationsin the usual number of cells withineach subpopulation were considered as afirst indication of cellular stress [9]. Duringthe oceanographic campaigns held in1995, coelomocytes were collected fromanimals of three different Croatian coastalsites, some identified as urban or industrialcontaminated areas, others referredto as unpolluted controls. Significant differenceswere observed in coelomocytesfrom polluted sea waters as it was founda consistent greater number of red amoebocytes(Figure 1B), a subpopulation ofthe immune cells which is usually poorlyrepresented [9]. At the molecular level,the marker analysed was the heat shockprotein 70 kDa (hsp70). The protein belongsto an evolutionary conserved familyof proteins, virtually found in all livingorganisms, from bacteria to humans[16]. Hsps are constitutively expressed incells under normal conditions where theyact as chaperones, controlling protein synthesisand folding [17]. In response to avariety of different stressors, their expressionis rapidly up-regulated at the post-1969