Legumes symbioses: absence of Nod genes in photosynthetic bradyrhizobia

Leguminous plants (such as peas and soybeans) and rhizobial soil bacteria are symbiotic partners that communicate through molecular signaling pathways, resulting in the formation of nodules on legume roots and occasionally stems that house nitrogen-fixing bacteria. Nodule formation has been assumed to be exclusively initiated by the binding of bacterial, host-specific lipochito-oligosaccharidic Nod factors, encoded by the nodABC genes, to kinase-like receptors of the plant. Here we show by complete genome sequencing of two symbiotic, photosynthetic, Bradyrhizobium strains, BTAi1 and ORS278, that canonical nodABC genes and typical lipochito-oligosaccharidic Nod factors are not required for symbiosis in some legumes. Mutational analyses indicated that these unique rhizobia use an alternative pathway to initiate symbioses, where a purine derivative may play a key role in triggering nodule formation.

Development and assessment of scoring functions for protein identification using PMF data

PMF is one of the major methods for protein identification using the MS technology. It is faster and cheaper than MS/MS. Although PMF does not differentiate trypsin-digested peptides of identical mass, which makes it less informative than MS/MS, current computational methods for PMF have the potential to improve its detection accuracy by better use of the information content in PMF spectra. We developed a number of new probability-based scoring functions for PMF protein identification based on the MOWSE algorithm. We considered a detailed distribution of matching masses in a protein database and peak intensity, as well as the likelihood of peptide matches to be close to each other in a protein sequence. Our computational methods are assessed and compared with other methods using PMF data of 52 gel spots of known protein standards. The comparison shows that our new scoring schemes have higher or comparable accuracies for protein identification in comparison to the existing methods. Our software is freely available upon request. The scoring functions can be easily incorporated into other proteomics software packages.

Recent progress in immunoisolated cell therapy

Biohybrid implants represent a new class of medical device in which living cells, supported in a hydrogel matrix, and surrounded by a semipermiable membrane, produce and deliver therapeutic reagents to specific sites within a host. First proposed in the mid-1970s for diabetes, this treatment modality has progressed rapidly in the past four years and is now being investigated not just for endocrine disorders but also for alleviation of chronic pain, treatment of neurodegenerative disorders, and delivery of neurotrophic factors to sites within the blood brain barrier, and as a practical alternative to conventional ex vivo.

Inhibition of ornithine decarboxylase alters neurological responsiveness to a tremorigen

Difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase (ODC; 200-800 mg/kg, s.c.), to rats has no detectable behavioral effects using a battery of tests to assess sensorimotor function. In contrast, the induction of tremor by chlordecone, a neurotoxic agent that affects neuronal ionic processes, is significantly attenuated by pretreatment with DFMO. The effects of DFMO on chlordecone-induced tremor were reversed by pretreatment with putrescine. DFMO had no effects on p,p'-DDT, a tremorigen having a mechanism of action different from chlordecone. These findings imply that polyamines may play a role in select neuronal processes.