Induced resistance in intertidal macroalgae modifies feeding behaviour of herbivorous snails

Herbivory in terrestrial and marine systems can induce changes in plant chemistry affecting the foraging behaviour of herbivores. A model based on terrestrial plant-herbivore interactions predicts herbivory-induced changes in leaf chemistry to be manifested in (1) increased herbivore mobility, (2) increased feeding dispersal and (3) reduced tissue consumption by herbivores. This study is the first to demonstrate that herbivory-induced changes in the tissue chemistry of the brown seaweed Ascophyllum nodosum elicit the same response in the feeding behaviour of the gastropod Littorina obtusata as predicted for herbivorous insects, providing good evidence for the models validity across different ecosystems. The potential benefit of increased feeding dispersal to terrestrial plants as suggested by the model is the prevention of concentrated damage to apical tissues thereby preserving the plants ability to compete for light; A. nodosum does not conform to these predictions. Increased dispersal of feeding damage on A. nodosum away from primary frond tissues would reduce the likelihood of frond breakage implying a fitness benefit of induced resistance.     

The mitochondrial prohibitin complex is essential for embryonic viability and germline function in Caenorhabditis elegans

Prohibitins in eukaryotes consist of two subunits (PHB1 and PHB2) that together form a high molecular weight complex in the mitochondrial inner membrane. The evolutionary conservation and the ubiquitous expression in mammalian tissues of the prohibitin complex suggest an important function among eukaryotes. The PHB complex has been shown to play a role in the stabilization of newly synthesized subunits of mitochondrial respiratory enzymes in the yeast Saccharomyces cerevisiae. We have used Caenorhabditis elegans as model system to study the role of the PHB complex during development of a multicellular organism. We demonstrate that prohibitins in C. elegans form a high molecular weight complex in the mitochondrial inner membrane similar to that of yeast and humans. By using RNA-mediated gene inactivation, we show that PHB proteins are essential during embryonic development and are required for somatic and germline differentiation in the larval gonad. We further demonstrate that a deficiency in PHB proteins results in altered mitochondrial biogenesis in body wall muscle cells. This paper reports a strong loss of function phenotype for prohibitin gene inactivation in a multicellular organism and shows for the first time that prohibitins serve an essential role in mitochondrial function during organismal development.     

What to do in marine biotechnology?

During the symposium "Marine Biotechnology: Basics and Applications", held 25 February-1 March, 2003 in Matalasca?as, Spain, a special brainstorm session was organized. Two questions were addressed: 1, "What is the most desirable development in marine biotechnology"?; 2, "What is the most spectacular development in this field in your 'wildest' dreams"? The outcome of this session is reported in this paper. From the more than 250 ideas generated, concern for the environment and human health emerged as the most significant issues.     

The origin of new genes: glimpses from the young and old

Genome data have revealed great variation in the numbers of genes in different organisms, which indicates that there is a fundamental process of genome evolution: the origin of new genes. However, there has been little opportunity to explore how genes with new functions originate and evolve. The study of ancient genes has highlighted the antiquity and general importance of some mechanisms of gene origination, and recent observations of young genes at early stages in their evolution have unveiled unexpected molecular and evolutionary processes.     

Characterization of Polylactide-b-polyisoprene-b-polylactide Thermoplastic Elastomers

Model polylactide-b-polyisoprene-b-polylactide (PLA-PI-PLA) triblock copolymers were prepared by an efficient protocol starting with alpha,omega-dihydroxy polyisoprene (HO-PI-OH). Using a moderately electrophilic Al(O-i-Pr)(3) catalyst and carefully controlling the ratio of Al to HO-PI-OH avoided gel formation and resulted in acceptable lactide polymerization rates. The triblock copolymers were free of homopolymer or diblock contaminants as determined by chromatographic and spectroscopic analyses. Three representative PLA-PI-PLA materials were prepared with spherical, cylindrical, and lamellar morphologies as confirmed by small-angle X-ray scattering and transmission electron microscopy. We employed dynamic mechanical analysis and tensile testing to assess the viscoelastic and mechanical behavior. The morphology largely determined the tensile properties of these materials, with the Young's modulus and ultimate tensile strength following predicted trends. Excellent elongations were achieved especially for the PLA-PI-PLA sample with the cylindrical morphology, and the PLA-PI-PLA sample with the spherical morphology showed the best elastomeric recovery. Microphase alignment and pull rate significantly influenced the resultant tensile properties.     

Synthesis and cytotoxic activity of different open indolocarbazole alkaloid analogues

An array of 4-(aryl or indolyl)pyrrolo[3,4-c]carbazole-1,3-diones (open analogues of indolocarbazole alkaloids), 10-(aryl or indolyl)pyrrolo[3,4-b]carbazole-1,3-diones, and different derivatives have been prepared using a Diels-Alder plus Fischer indolization approach and tested as cytotoxic agents. Some representative compounds display interesting cytotoxic profiles.