Marine isocyanides and related natural products structure, biosynthesis and ecology

This review highlights structural and biosynthetic work on a group of nitrogen-functionalised terpenes that are almost exclusively found in marine invertebrates and the animals that feed on them. The chemical functionality reviewed includes isocyanides, isothiocyanates, formamides, thiocyanates, isocyanates, and dichloroimines. The literature through mid 2003 is reviewed and there are 143 citations.

Formation of mononuclear and chloro-bridged binuclear copper(II) complexes of patellamide D, a naturally occurring cyclic peptide: influence of anion and solvent

Patellamide D (patH(4)) is a cyclic octapeptide isolated from the ascidian Lissoclinum patella. The peptide possesses a 24-azacrown-8 macrocyclic structure containing two oxazoline and two thiazole rings, each separated by an amino acid. The present spectrophotometric, electron paramagnetic resonance (EPR) and mass spectral studies show that patellamide D reacts with CuCl, and triethylamine in acetonitrile to form mononuclear and binuclear copper(II) complexes containing chloride. Molecular modelling and EPR studies suggest that the chloride anion bridges the copper(II) ions in the binuclear complex [Cu-2(patH(2))(mu-Cl)](+). These results contrast with a previous study employing both base and methanol, the latter substituting for chloride in the copper(II) complexes en route to the stable mu-carbonato binuclear copper(II) complex [Cu-2 (patH(2))(mu-CO3)]. Solvent clearly plays an important role in both stabilising these metal ion complexes and influencing their chemical reactivities. (C) 2004 Elsevier Inc. All rights reserved.

Offspring size effects mediate competitive interactions in a colonial marine invertebrate

Over the past 30 years, numerous attempts to understand the relationship between offspring size and fitness have been made, and it has become clear that this critical relationship is strongly affected by environmental heterogeneity. For marine invertebrates, there has been a long-standing interest in the evolution of offspring size, but there have been very few empirical and theoretical examinations of post-metamorphic offspring size effects, and almost none have considered the effect of environmental heterogeneity on the offspring size/fitness relationship. We investigated the post-metamorphic effects of offspring size in the field for the colonial marine invertebrate Botrylloides violaceus. We also examined how the relationship between offspring size and performance was affected by three different types of intraspecific competition. We found strong and persistent effects of offspring size on survival and growth, but these effects depended on the level and type of intraspecific competition.. Generally, competition strengthened the advantages of increasing maternal investment. Interestingly, we found that offspring size determined the outcome of competitive interaction: juveniles that had more maternal investment were more likely to encroach on another juvenile's territory. This suggests that mothers have the previously unrecognized potential to influence the outcome of competitive interactions in benthic marine invertebrates. We created a simple optimality model, which utilized the data generated from our field experiments, and found that increasing intraspecific competition resulted in an increase,in predicted optimal size. Our results suggest that the relationship between offspring size and fitness is highly variable in the marine environment and strongly dependent on the density of conspecifics.

Reliably estimating the effect of toxicants on fertilization success in marine broadcast spawners

Recently, there has been a dramatic increase in the number of ecotoxicological studies examining the effects of toxicants on fertilization success in marine broadcast spawners and it appears that this life-history stage is one of the most vulnerable to toxicants. Most of the studies examining this issue use single sperm concentrations in their assays. Here, I discuss recent advances in fertilization ecology that suggest this technique has some severe limitations resulting in unreliable estimations of the size and direction of toxicant effects. I present an alternative assay technique and two metrics (F-max and [Sperm](max)) that will reliably estimate the size of a toxicant's effect on fertilization success. This technique has the added advantage of making comparisons among species and studies easier without an impractical increase in effort. (c) 2006 Elsevier Ltd. All rights reserved.

Spectroscopic characterization of copper(II) binding to the immunosuppressive drug mycophenolic acid

Mycophenolic acid (MPA) is a drug that has found widespread use as an immunosuppressive agent which limits rejection of transplanted organs. Optimal use of this drug is hampered by gastrointestinal side effects which can range in severity. One mechanism by which MPA causes gastropathy may involve a direct interaction between the drug and gastric phospholipids. To combat this interaction we have investigated the potential of MPA to coordinate Cu(II), a metal which has been used to inhibit gastropathy associated with use of the NSAID indomethacin. Using a range of spectroscopic techniques we show that Cu(II) is coordinated to two MPA molecules via carboxylates and, at low pH, water ligands. The copper complex formed is stable in solution as assessed by mass spectrometry and H-1 NMR diffusion experiments. Competition studies with glycine and albumin indicate that the copper-MPA complex will release Cu(II) to amino acids and proteins thereby allowing free MPA to be transported to its site of action. Transfer to serum albumin proceeds via a Cu(MPA)(albumin) ternary complex. These results raise the possibility that copper complexes of MPA may be useful in a therapeutic situation.

Prudent female allocation by modular hermaphrodites: female investment is promoted by the opportunity to outcross in cyclostome bryozoans

Many sessile, suspension-feeding marine invertebrates mate by spermcasting: aquatic sperm are spawned and gathered by conspecific individuals to fertilize eggs that are generally retained during development. In two phylogenetically distant examples, a cheilostome bryozoan and an aplousobranch ascidian, the receipt of allosperm has previously been shown to alter sex allocation by triggering female investment in eggs and brooding. Here we report experiments demonstrating that two species of cyclostome bryozoan also show restrained female investment in the absence of mating opportunity. In Tubulipora plumosa, the production of female zooids and progeny is much reduced in reproductive isolation. In Filicrisia geniculata, development of distinctive female zooids (gonozooids) begins but halts in the absence of mating opportunity, and no completed gonozooids or progeny result. Reduced female investment in the absence of a mate thus occurs in at least two orders of Bryozoa, but significant differences in detail exist and the evolutionary history within the phylum of the mechanism(s) by which female investment is initiated might be complex. The broadening taxonomic spectrum of examples where female investment appears restrained until allosperm becomes available may signify a general adaptive strategy among outcrossing modular animals, analogous to similarly adaptive sex allocation typical of many flowering plants.

Prudent female allocation by modular hermaphrodites: female investment is promoted by the opportunity to outcross in cyclostome bryozoans

Many sessile, suspension-feeding marine invertebrates mate by spermcasting: aquatic sperm are spawned and gathered by conspecific individuals to fertilize eggs that are generally retained during development. In two phylogenetically distant examples, a cheilostome bryozoan and an aplousobranch ascidian, the receipt of allosperm has previously been shown to alter sex allocation by triggering female investment in eggs and brooding. Here we report experiments demonstrating that two species of cyclostome bryozoan also show restrained female investment in the absence of mating opportunity. In Tubulipora plumosa, the production of female zooids and progeny is much reduced in reproductive isolation. In Filicrisia geniculata, development of distinctive female zooids (gonozooids) begins but halts in the absence of mating opportunity, and no completed gonozooids or progeny result. Reduced female investment in the absence of a mate thus occurs in at least two orders of Bryozoa, but significant differences in detail exist and the evolutionary history within the phylum of the mechanism(s) by which female investment is initiated might be complex. The broadening taxonomic spectrum of examples where female investment appears restrained until allosperm becomes available may signify a general adaptive strategy among outcrossing modular animals, analogous to similarly adaptive sex allocation typical of many flowering plants.

Ascidonia Flavomaculata (Heller, 1864), a new record for the Portuguese marine invertebrate fauna (Decapoda, Pontoniidae)

Several specimens of Ascidonia flavomaculata were collected during experimental fishing trials along the southern coast of Portugal. All specimens were associated with the solitary ascidian, Phallusia mammillata. The pontoniinae shrimp, A. flavomaculata is here recorded from the Portuguese coast for the first time, extending the species’ known distribution range further north along the coast of the eastern Atlantic Ocean.