Currently, between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely. More species than ever before are being described annually by an increasing number of authors. If the current trend continues, most species will be discovered this century.

The majority of invertebrate skeletal tissues are composed of the most stable crystalline polymorphs of CaCO(3), calcite, and/or aragonite. Here we describe a composite skeletal tissue from an ascidian in which amorphous and crystalline calcium carbonate coexist in well-defined domains separated by an organic sheath. Each biogenic mineral phase has a characteristic Mg content (5.9 and 1.7 mol %, respectively) and concentration of intramineral proteins (0.05 and 0.01 wt %, respectively). Macromolecular extracts from various biogenic amorphous calcium carbonate (ACC) skeletons are typically glycoproteins, rich in glutamic acid and hydroxyamino acids. The proteins from the crystalline calcitic phases are aspartate-rich. Macromolecules extracted from biogenic ACC induced the formation of stabilized ACC and/or inhibited crystallization of calcite in vitro. The yield of the synthetic ACC was 15-20%. The presence of Mg facilitated the stabilization of ACC: the protein content in synthetic ACC was 0.12 wt % in the absence of Mg and 0.07 wt % in the presence of Mg (the Mg content in the precipitate was 8.5 mol %). In contrast, the macromolecules extracted from the calcitic layer induced the formation of calcite crystals with modified morphology similar to that expressed by the original biogenic calcite. We suggest that specialized macromolecules and magnesium ions may cooperate in the stabilization of intrinsically unstable amorphous calcium carbonate and in the formation of complex ACC/calcite tissues in vivo.

Communications CED MATERIALS mono-thiophene (N-[(6-(thien-3-yl)hexanoyloxy]-pyrroli-dine-2,5-dione; see Scheme 1) instead of the bithiophene derivative, we have been able to prepare analogous glucose oxidase-modified polymer films. The functionalized polythiophene film has been obtained using a similar multisweep regime, however, with potential scans up to a vertex potential of 1.7 V vs. SCE, reflecting the higher potential of the radical cations formation. The second step, the covalent immobilization of the enzyme is of course equivalent and independent from the specific needs for the formation of the polymer film. The obtained enzyme electrodes show a slightly lower response as those obtained with the functionalized poly(bithiophene) films, despite there are double active ester groups available to react with the enzyme. Probably, due to the size of an individual enzyme molecule the increased number of binding sites at the electrode surface does not concomitantly increase the immobilized enzyme activity.To conclude, we have shown that, despite the high oxidation potential of thiophene and its derivatives, polythiophene films can be advantageously used for the entrapment or covalent immobilization of enzymes. This was realized by entrapment of glucose oxidase using dimeric or trimeric thiophenes as parent compounds for the polymerization process in CH3CN/water mixtures or, according to a two-step procedure, based on functionalized polythiophene or poly(bithi0phene) films and covalently bound enzyme. In principle, polythiophene as immobilization matrix in amperometric enzyme electrodes has at least two advantages over other conducting polymer films: First, derivatization of thiophene in the 3-position and the synthesis of oligomers is much easier than for pyrrole. Second, due to the higher redox potential of the polymer film itself, deterioration e.g. by enzymatically generated H202 is less probable. This is even more important for a next sensor generation, in which the conducting polymer is expected to act as molecular wire between the active site of the enzyme and the electrode surface. Possibly, the improved stability of polythiophene against oxidation in ambient environments will allow the construction of biosensors with improved sensor characteristics and life-time.Some organisms form stable minerals that would never precipitate under ambient conditions in an inorganic environment, or, if formed, are unstable precursors of more stable compounds.['321 One of the most fascinating examples is biogenic amorphous calcium carbonate, because its transformation into crystalline polymorphs is not only thermodynamically favored, but also kinetically fast.I3] We report here an example of a single skeletal element, spicules from the calcareous sponge Clathrina, composed of crystalline calcite in one layer and stable amorphous CaC03 in another. Differential dissolution of the amorphous phase of these spicules released macromolecules with proteins rich in glutamic acid (and/or glutamine), serine, glycine and polysaccharide...

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The last comprehensive reviews of ecology and natural history of ascidians were included in the excellent 1971 publication by Millar on the biology of ascidians and the 1991 treatise on New Caledonia ascidians by Monniot, Monniot, and Laboute. Several hundred papers have been published since that time, greatly expanding our knowledge of environmental tolerances and responses to increasing levels of anthropogenically derived toxins in marine waters, energetics and feeding strategies, predator–prey relationships, competition both intra- and inter-specific that include many studies of self–nonself recognition in colonial species, modes and environmental regulation of reproduction and development, symbionts, natural-product chemistry as antifouling and antipredator defenses, and dispersal mechanisms. The relatively new field of molecular genetics is revealing the presence of cryptic species and is helping to determine the origin of anthropogenically transported individuals, an important and growing problem that affects natural ecological relationships in marine communities worldwide. We are learning more about the difficult-to-study abyssal and Antarctic species. There have been great advances in our understanding of the importance in open-ocean food webs of the planktonic Appendicularia and Thaliacea. Also included in this review is a brief discussion of recent work on the Cephalochordata and Hemichordata.

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2 Bullard et al. AbstractDidemnum sp. A is a colonial ascidian with rapidly expanding populations on the east and west coasts of North America. The origin of Didemum sp. A is unknown.Populations were first observed on the northeast coast of the U.S. in the late 1980s and on the west coast during the 1990s. It is currently undergoing a massive population explosion and is now a dominant member of many subtidal communities on both coasts. 3 Bullard et al.