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Genetics Approaches (genetics + approach)
Selected AbstractsBacillus pumilus SG2 isolated from saline conditions produces and secretes two chitinasesJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2007G. Ahmadian Abstract Aims: Isolation and characterization of chitinases from a halotolerant Bacillus pumilus. Methods and Results: Bacillus pumilus strain SG2 was isolated from saline conditions. It is able to produce chitinase activity at high salt concentration. SDS-PAGE analysis of the B. pumilus SG2 culture supernatant showed two major bands that were induced by chitin. The amino acid sequence of the two proteins, designated ChiS and ChiL, showed a high homology with the chitinase of B. subtilis CHU26, and chitinase A of B. licheniformis, respectively. N -terminal signal peptide of both proteins was also determined. The molecular weight and isoelectric point of the chitinases were determined to be 63 and 74 kDa, and 4·5 and 5·1, for ChiS and ChiL respectively. The genes encoding for both chitinases were isolated and their sequence determined. The regulation of the chitinase genes is under the control of the catabolite repression system. Conclusions: Secreted chitinase genes and their flanking region on the genome of B. pumilus SG2 have been identified and sequenced. Significance and Impact of the Study: This is the first report of a multiple chitinases-producing B. pumilus halotolerant strain. We have identified two chitinases by using a reverse genetics approach. The chitinases show resistance to salt. [source] The emerging field of chemical genetics: potential applications for pesticide discoveryPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 12 2007Terence A Walsh Abstract The use of small molecules to probe biological systems, generally described as ,chemical genetics', has grown considerably in the past 7 years, especially in areas related to human biology and therapeutics. This review describes some aspects of chemical genetics technologies that can be usefully applied to pesticide target discovery and lead generation. The chemical genetics approach (consisting of a phenotype screen, a chemical library and a robust target identification methodology) is compared with conventional and target-based screening. The outcomes of a chemical genetics approach are novel protein targets coupled with in vivo -active chemical ligands. The ,chemistry-first' paradigm of the chemical genetics approach can circumvent some of the obstacles that have emerged for the exploitation of novel but chemically unvalidated targets identified from genetic or genomic screens. Some of the advantages and challenges in using chemical genetics approaches are reviewed. Copyright © 2007 Society of Chemical Industry [source] Evolutionary genetics and biogeographic structure of Rhizobium gallicum sensu lato, a widely distributed bacterial symbiont of diverse legumesMOLECULAR ECOLOGY, Issue 13 2005CLAUDIA SILVA Abstract We used phylogenetic and population genetics approaches to evaluate the importance of the evolutionary forces on shaping the genetic structure of Rhizobium gallicum and related species. We analysed 54 strains from several populations distributed in the Northern Hemisphere, using nucleotide sequences of three ,core' chromosomal genes (rrs, glnII and atpD) and two ,auxiliary' symbiotic genes (nifH and nodB) to elucidate the biogeographic history of the species and symbiotic ecotypes (biovarieties) within species. The analyses revealed that strains classified as Rhizobium mongolense and Rhizobium yanglingense belong to the chromosomal evolutionary lineage of R. gallicum and harbour symbiotic genes corresponding to a new biovar; we propose their reclassification as R. gallicum bv. orientale. The comparison of the chromosomal and symbiotic genes revealed evidence of lateral transfer of symbiotic information within and across species. Genetic differentiation analyses based on the chromosomal protein-coding genes revealed a biogeographic pattern with three main populations, whereas the 16S rDNA sequences did not resolve that biogeographic pattern. Both the phylogenetic and population genetic analyses showed evidence of recombination at the rrs locus. We discuss our results in the light of the contrasting views of bacterial species expressed by microbial taxonomist and evolutionary biologists. [source] The stem canker (blackleg) fungus, Leptosphaeria maculans, enters the genomic eraMOLECULAR PLANT PATHOLOGY, Issue 3 2005T. ROUXEL SUMMARY Leptosphaeria maculans is the most ubiquitous pathogen of Brassica crops, and mainly oilseed brassicas (oilseed rape, canola), causing the devastating ,stem canker' or ,blackleg'. This review summarizes our current knowledge on the pathogen, from taxonomic issues to specific life traits. It mainly illustrates the importance of formal genetics approaches on the pathogen side to dissect the interaction with the host plants. In addition, this review presents the main current research topics on L. maculans and focuses on the L. maculans genome initiative recently begun, including its main research issues. Taxonomy:,Leptosphaeria maculans (Desm.) Ces. & de Not. (anamorph Phoma lingam Tode ex Fr.). Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes (Loculoascomycetes), Order Pleosporales, Genus Leptosphaeria, Species maculans. Host range:, cultivated Brassicas such as Brassica napus (oilseed rape, canola), B. rapa, B. juncea, B. oleracea, etc., along with numerous wild crucifers species. Arabidopsis thaliana was recently reported to be a potential host for L. maculans. Primary disease symptoms are greyish-green collapse of cotyledon or leaf tissue, without a visible margin, bearing tiny black spots (pycnidia). The fungus then develops an endophytic symptomless growth for many months. Secondary symptoms, at the end of the growing season, are dry necroses of the crown tissues with occasional blackening (stem canker or blackleg) causing lodging of the plants. Pseudothecia differentiate on leftover residues. Seedling damping-off and premature ripening are also reported under certain environmental conditions. Useful websites:,Leptosphaeria maculans sequencing project at Genoscope: http://www.genoscope.cns.fr/externe/English/Projets/Projet_DM/organisme_DM.html; the SECURE site: http://www.secure.rothamsted.ac.uk/ the ,Blackleg' group at the University of Melbourne: http://www.botany.unimelb.edu.au/blackleg/overview.htm [source] The emerging field of chemical genetics: potential applications for pesticide discoveryPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 12 2007Terence A Walsh Abstract The use of small molecules to probe biological systems, generally described as ,chemical genetics', has grown considerably in the past 7 years, especially in areas related to human biology and therapeutics. This review describes some aspects of chemical genetics technologies that can be usefully applied to pesticide target discovery and lead generation. The chemical genetics approach (consisting of a phenotype screen, a chemical library and a robust target identification methodology) is compared with conventional and target-based screening. The outcomes of a chemical genetics approach are novel protein targets coupled with in vivo -active chemical ligands. The ,chemistry-first' paradigm of the chemical genetics approach can circumvent some of the obstacles that have emerged for the exploitation of novel but chemically unvalidated targets identified from genetic or genomic screens. Some of the advantages and challenges in using chemical genetics approaches are reviewed. Copyright © 2007 Society of Chemical Industry [source] | ||||||||||