Heterologous synthesis of geranyllinalool,a diterpenol plant product,in the cyanobacterium Synechocystis

Cyanobacteria are industrially robust photosynthetic microorganisms that can be genetically programmed to synthesize commodity products for domestic and industrial consumption. In the present work, Synechocystis was endowed with the synthesis of the plant secondary metabolite geranyllinalool, a diterpene alcohol of commercial interest. Total average yields of 360 μg of geranyllinalool per gram of dry cell weight were obtained in the course of a 48-h cultivation period. Geranyllinalool was primarily sequestered inside the transformant cells, corresponding to 60–70% of the total heterologous product, instead of being entirely exuded, as the case is with shorter heterologous terpene hydrocarbons. Extraction of geranyllinalool necessitated disruption of the cells in order to release and isolate this chemical product. Moreover, geranyllinalool accumulation in the cells caused a mild inhibitory effect on cell fitness and biomass growth rate, such that the duplication time of Synechocystis transformants was 1.4-fold longer than that of the control. The remaining 30–40% of the geranyllinalool product was found to float on the surface of sealed transformant cultures, where it was siphoned off by applying a hydrophobic overlayer, with no need to disrupt the cells in this case. Concluding, the work extended efforts to heterologously produce terpene and terpenol products in cyanobacteria, and addressed possibilities and constrains inherent to this production system.

     

P2Y<Subscript>1</Subscript>receptor switches to neurons from glia in juvenile versus neonatal rat cerebellar cortex

Background  

In the CNS, several P2 receptors for extracellular nucleotides are identified on neurons and glial cells to participate to neuron-neuron, glia-glia and glia-neuron communication.     

What strikes most when we think of Geoff

Purinergic Signalling -     

Micromorphological,geochemical, and diagenetic characterization of sirenian ribs preserved in the Late Miocene paleontological site of Cessaniti (southern Calabria,Italy)

The site of Cessaniti (Vibo Valentia, Italy) has been well known since the 19th century for the richness and good preservation of its Miocene fauna and flora. The sedimentary succession of the site represents a paralic system that evolved toward an open-marine environment recording the Tortonian transgression. The fossil assemblage contains rich invertebrate (corals, bivalves, gastropods, brachiopods, echinoids, benthic and planktonic foraminifers) and vertebrate faunas (proboscideans, rhinoceroses, giraffids, bovids, sirenids, marine turtles, and fish remains). The fossils recovered at the Cessaniti site have a relevant role in phylogenetic studies and paleogeographic reconstructions of Late Miocene environments of the southern Italy. This research is focused on the microstructure and preservation state of the fossil bones. Samples of Metaxytherium sp. bones have been analyzed to understand the diagenetic profile of the bone assemblages that characterizes the taphonomic history of the Cessaniti site. The analyses provided a comprehensive account of how bone mineral (bioapatite) has been altered and demonstrated that the post-burial processes did not significantly affect the micromorphological and biogeochemical features of the bones. The excellent preservation state of the bones strengthens the importance of the Cessaniti site for studies of the Mediterranean Miocene vertebrate fauna.     

Deletion of DNA lying close to the glkA locus induces ectopic sporulation in Streptomyces coelicolor A3(2)

Streptomyces coelicolor A3(2) J1668 sporulated ectopically in the substrate hyphae (the Esp phenotype) with the same time course as sporulation in the aerial hyphae. Examination of related strains implied that the Esp phenotype was caused by the deletion of DNA that lies close to, but is distinct from, the glucose kinase gene ( glkA ). Co-transduction of the Esp phenotype with the deletion present in J1668 confirmed this hypothesis. The size of the deletion was found to be 7.4 kb. Construction of a strain carrying both the J1668 deletion and a whiG mutation demonstrated that the Esp phenotype depends on at least one of the genes required for the differentiation of aerial hyphae into spores.