In vitro effects of metal pollution on Mediterranean sponges: Species-specific inhibition of 2 ‘,5 ‘-oligoadenylate synthetase.

7 páginas, 5 figuras, 1 tabla.Heavy metals are among the main pollutants of the Mediterranean coastal waters where they can harm sublittoral biota. Filter-feeder, long-living invertebrates that remain fixed to the rocky bottom, such as sponges, are good targets tometal contamination studies since theymay be exposed to potential lowlevels of contamination for years. Several molecular and biochemical mechanisms are developed by sponges to counteract the effects of noxious metals. As a result, some of the normal cell functions can be altered. Herewe showthat the main heavy metals that can be found in marine sublittoralwaters (i.e. copper, iron, zinc and manganese) may alter the immune system of sponges by inhibiting the activity of the sponge 2 ,5 -oligoadenylate synthetase (2-5A synthetase), which is an enzyme involved in the immune system of vertebrates. We selected the widespread Mediterranean sponges Geodia cydonium, Crella elegans and Chondrosia reniformis for the study. They exerted a high 2-5A synthetase activity and gave a unique profile of 2 ,5 -oligoadenylate product production. Several metals alter the 2-5A synthetase activity differently, in a species-specific manner. 2-5A synthetases from G. cydonium and C. elegans were inhibited by all the metal ions assayed. However, in C. reniformis, 2-5A synthetase was either activated or inhibited by the same ions depending on their final concentrations. Like in humans, metal contamination may have an effect on the OAS activity and thus it might alter the sponge immune system. However, since the effects are species-specific, 2-5A synthetase cannot be used as general biomarker of metal pollutions.This work was supported by the European Union with the Marie Curie Research Training Network, BIOCAPITAL FP6 and by the Spanish Government with the projects INTERGEN, CICYT: CTM2004-05265-C02/MAR and MARMOL, CICYT: CTM2007-66635-CO2.Peer reviewe

2′-phosphodiesterase and 2′,5′-oligoadenylate synthetase activities in the lowest metazoans, sponge [porifera]

4 páginas, 1 tabla, 1 figura.Sponges [porifera], the most ancient metazoans, contain modules related to the vertebrate immune system, including the 2 0 ,5 0 -oligoadenylate synthetase (OAS). The components of the antiviral 2 0 ,5 0 -oligoadenylate (2–5A) system (OAS, 2 0 -Phosphodiesterase (2 0 -PDE) and RNAse L) of vertebrates have not all been identified in sponges. Here, we demonstrate for the first time that in addition to the OAS activity, sponges possess a 2 0 -PDE activity, which highlights the probable existence of a premature 2–5A system. Indeed, Suberites domuncula and Crella elegans exhibited this 2–5A degrading activity. Upon this finding, two out of three elements forming the 2–5A system have been found in sponges, only a endoribonuclease, RNAse L or similar, has to be found. We suspect the existence of a complex immune system in sponges, besides the self/non-self recognition system and the use of phagocytosis and secondary metabolites against pathogens.This work was supported by the European Union with the Marie Curie Research Training Network, BIOCAPITAL FP6 and by the Spanish Government with the project MARMOL, CI-CYT: CTM2007- 66635-CO2.Peer reviewe

Evolution of the 2′-5′-Oligoadenylate Synthetase Family in Eukaryotes and Bacteria

13 páginas, 5 figuras, 3 tablas.The 2 0 -5 0 -oligoadenylate synthetase (OAS) belongs to a nucleotidyl transferase family that includes poly(A) polymerases and CCA-adding enzymes. In mammals and birds, the OAS functions in the interferon system but it is also present in an active form in sponges, which are devoid of the interferon system. In view of these observations, we have pursued the idea that OAS genes could be present in other metazoans and in unicellular organisms as well. We have identified a number of OAS1 genes in annelids, mollusks, a cnidarian, chordates, and unicellular eukaryotes and also found a family of proteins in bacteria that contains the five OAS-specific motifs. This indicates a specific relationship to OAS. The wide distribution of the OAS genes has made it possible to suggest how the OAS1 gene could have evolved from a common ancestor to choanoflagellates and metazoans. Furthermore, we suggest that the OASL may have evolved from an ancestor of cartilaginous fishes, and that the OAS2 and the OAS3 genes evolved from a mammalian ancestor. OAS proteins function in the interferon system in mammals. This system is only found in jawed vertebrates. We therefore suggest that the original function of OAS may differ from its function in the interferon system, and that this original function of OAS is preserved even in OAS genes that code for proteins, which do not have 2 0 -5 0 -oligoadenylate synthetase activity.The work was initially supported by a grant from the Danish Natural Science Council and the Carlsberg Foundation. The work was supported by the Estonian Science Foundation (Grant no. 7421).Peer reviewe