Communication and signal exchange in the Rhizobium bradyrhizobium legume system

A new comprehensive communication concept in the Rhizobium/Bradyrhizobium legume symbiosis was developed. It includes a root zone specific flavonoid exudation, the differential activity of phenylpropane/acetate pathway derivatives on chemotaxis, nod-gene inducing activity and phytoalexin resistance induction on the microsymbiont side (Bradyrhizobium). Nod factor production from the microsymbiont affects the host plant in root hair curling and meristem induction. Phytoalexin production in the host plant is also an early response, however repressed to a low level after a few hours. Another strategy of the microsymbiont to overcome phytoalexin effects is degradation of phytoalexins in Rhizobium leguminosarum bv. vicieae. Competitiveness within the same infection group of the microsymbiont was studied with gus-gene fusion, using the blue coloured nodules to easily discriminate marked strains from unmarked competitors. New exopolysaccharide (EPS) mutants of Bradyrhizobium japonicum were reconstructed homologous with a DNA region to exoB gene of Rhizobium meliloti. Their clearly reduced competitiveness of nodulation, demonstrates that exopolysaccharides of Bradyrhizohium japonicum also have an important function during the early stages of this symbiotic interaction

Introduction of an MPEG-7 query language

Today the availability of digital media content is well established and widespread. Not only commercial content distribution is a big market, but also user driven digital multimedia content is produced and shared in big communities. One of the metadata standards that has been established to describe multimedia content via metadata is MPEG-7. This international standard facilitates many application domains and is probably the richest multimedia metadata set available today. However it does not yet exist a common query format that enables the user to query multimedia metadata databases. Therefore the MPEG committee decided to instantiate a call for proposal (N8220)for an MPEG-7 query format (MP7QF) framework and specified a set of requirements (N8219). This paper introduces a MP7QF query language and describes the background and requirements as well as the main architectural concepts and associated MP7QF XML schema types