Marine drugs--macrolactins

The increasing demands for new lead compounds in pharmaceutical and agrochemical industries have driven scientists to search for new bioactive natural products. Marine microorganisms are rich sources of novel, bioactive secondary metabolites, and have attracted much attention of chemists, pharmacologists, and molecular biologists. This mini-review mainly focuses on macrolactins, a group of 24-membered lactone marine natural products, aiming at giving an overview on their sources, structures, biological activities, as well as their potential medical applications.     

Fine structure of the ventral nerve centre and interspecific identification of individual neurons in the enigmatic Chaetognatha

The enigmatic arrow worms (Chaetognatha) are marine carnivores and among the most abundant planktonic organisms. Their phylogenetic position has been heavily debated for a long time. Most recent molecular studies still provide a diverging picture and suggest arrow worms to be some kind of basal protostomes. In an effort to understand the organization of the nervous system in this clade for a broad comparison with other Metazoa we analysed the ultrastructure of the ventral nerve centre in Spadella cephaloptera by transmission electron microscopy. We were able to identify six different types of neurons in the bilateral somata clusters by means of the cytoplasmic composition (regarding the structure of the neurite and soma including the shape and eu-/heterochromatin ratio within the nucleus) as well as the size and position of these neurons. Furthermore, our study provides new insights into the neuropil composition of the ventral nerve centre and several other fine structural features. Our second goal was to examine if individually identifiable neurons are present in the ventral nerve centres of four chaetognath species, Sagitta setosa, Sagitta enflata, Pterosagitta draco, and Spadella cephaloptera. For that purpose, we processed whole mount specimens of these species for immunolocalization of RFamide-related neuropeptides and analysed them with confocal laser-scanning microscopy. Our experiments provide evidence for the interspecific homology of individual neurons in the ventral nerve centres of these four chaetognath species suggesting that the potential to generate serially arranged neurons with individual identities is part of their ground pattern.     

Developing a scuba trail vulnerability index (STVI): a case study from a Mediterranean MPA

Scuba diving is now one of the major form of commercial use of marine protected areas (MPAs) around the world and the control of its potential impacts on the marine environment represents a fundamental key to manage this recreational activity in highly dived areas. A potential tool to tackle such issues has been thought to be the definition of a value of recreational carrying capacity of an area, but this approach has been rarely considered management-effective. Therefore, the first step for effectively managing scuba-diving should be ‘bottom-up’: characterizing the benthic communities potentially affected by diving and evaluating their vulnerability. Aim of this paper is to propose a tool to define an index of vulnerability for dive trails (STVI: scuba trail vulnerability index). This has taken into consideration both physical and biological features of each trail. All the considered features are represented by non-quantitative variables, because either they are purely qualitative or their quantitative measurement is impractical. The management of such qualitative information and its translation into a formal methodology was performed by means of fuzzy logic, which has been repeatedly proposed as a powerful technique to develop indices of environmental quality. The approach adopted in this study provided a useful tool for the preliminary assessment of the potential vulnerability of benthic assemblages to scuba-diving and may represent an alternative method to the assessment of carrying capacity. The application of this index will enable management strategies for potentially reducing the degradation of benthic organisms/assemblages, and allowing a sustainable use of MPAs.     

Dung Beetle and Terrestrial Mammal Diversity in Forests, Indigenous Agroforestry Systems and Plantain Monocultures in Talamanca, Costa Rica

In order to explore the importance of indigenous agroforestry systems for biodiversity conservation, we compared the abundance, species richness and diversity of dung beetles and terrestrial mammals across a gradient of different land use types from agricultural monocultures (plantains) to agroforestry systems (cocoa and banana) and forests in the BriBri and Cabécar indigenous reserves in Talamanca, Costa Rica. A total of 132,460 dung beetles of 52 species and 913 tracks of 27 terrestrial mammal species were registered. Dung beetle species richness and diversity were greatest in the forests, intermediate in the agroforestry systems and lowest in the plantain monocultures, while dung beetle abundance was greatest in the plantain monocultures. The number of mammal tracks per plot was significantly higher in forests than in plantain monocultures, whereas mammal species richness was higher in forests than in either cocoa agroforestry systems or plantain monocultures. Species composition of both terrestrial mammals and dung beetles also varied across the different land use types. Our study indicates that indigenous cocoa and banana agroforestry systems maintain an intermediate level of biodiversity (which is less than that of the original forest but significantly greater than that of plantain monocultures) and provide suitable habitat for a number of forest-dependent species. Although the agroforestry systems appear to serve as favorable habitats for many terrestrial mammal species, their potential positive contribution to mammal conservation is being offset by heavy hunting pressure in the reserves. As in other agricultural landscapes, the conservation of biodiversity in Talamanca will depend not only on maintaining the existing forest patches and reducing the conversion of traditional agroforestry systems to monocultures, but also on reducing hunting pressure.     

Unusual glycoconjugates in the oesophagus of a tilapine polyhybrid

The aim of this work is to elucidate the glycoconjugate composition of the secretory products of the oesophageal mucous cells in a tilapine polyhybrid. Lectin histochemistry gave evidence of the presence of β-galactose, α-N-acetylgalactosamine and sialic acid residues in the terminal position. The majority of sialic acid belongs to short side chains; a few sialic acid residues are acetylated at the C₇ and/or C₈ and/or C₉ level. The heterogeneity of the carbohydrate chains may mask potential receptor sites for micro-organisms and hamper the formation of multiple bonds.     

妥布霉素产生菌激光育种的研究

本文首次报道铜蒸气激光选育妥布霉素产生菌—黑暗链霉菌（Ｓｔｒｅｐｔｏｍｙｃｅｓｔｅｎｅｂｒａｒｉｕｓ）的研究结果。在相同实验条件下,铜蒸气激光辐照黑暗链霉菌比其随后又以氯化锂复合处理的选育效果好。在铜蒸气激光辐照后,曾获得实验高产株,发酵单位比对照未辐照组提高７２％。     

Isolation,taxonomic and fermentation studies on a new strain of Streptomyces arenae var ukrainiana producing a tetraene antibiotic

A Streptomyces strain UK10 was isolated from Ukrainian soil and identified by taxonomical studies as Streptomyces arenae var ukrainiana. HA-2-91 was isolated from the biomass of S. arenae var ukrainiana and is supposedly a polyene macrolide antibiotic belonging to the tetraene group. HA-2-91 showed promising antifungal activity (in vitro) against yeasts and filamentous fungi, including plant pathogens and dermatophytes and was found to be less toxic in mice than nystatin and rimocidin.