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Evidence for a Symbiosis Island Involved in Horizontal Acquisition of Pederin Biosynthetic Capabilities by the Bacterial Symbiont of Paederus fuscipes Beetles. Jörn Piel, 2004.Pederin belongs to a group of antitumor compounds found in terrestrial beetles and marine sponges . It is used by apparently all members of the rove beetle genera Paederus and Paederidus as a chemicaldefense against predators . However, a recent analysis of the putative pederin biosynthesis [ped] gene cluster strongly suggests that pederin is produced by bacterial symbionts . We have sequenced an extended region of the symbiont genome to gain further insight into the biology of this as-yet-unculturable bacterium and the evolution of pederin symbiosis . Our data indicate that the symbiont is a very close relative of Pseudomonas aeruginosa that has acquired several foreign genetic elements by horizontal gene transfer . Besides one functional tellurite resistance operon,the region contains a genomic island spanning 71.6 kb that harborsthe putative pederin biosynthetic genes . Several decayed insertion sequence elements and the mosaic-like appearance of the island suggest that the acquisition of the ped symbiosis genes was followed by further insertions and rearrangements . A horizontal transfer of genes for the biosynthesis of protective substancescould explain the widespread occurrence of pederin-type compoundsin unrelated animals from diverse habitats. Dihydroethanoanthracene Derivatives as In Vitro Malarial Chloroquine Resistance Reversal Agents. Julie Millet, 2004.The ability of four 9,10-dihydroethanoanthracene derivatives (BG920, BG932, BG958, and BG996), as well as verapamil and promethazine, to reverse chloroquine resistance was assessed against 24 chloroquine-resistant and 10 chloroquine-susceptible strains of Plasmodium falciparum from different countries . The 9,10-dihydroethanoanthracene derivatives clearly increase chloroquine susceptibility only in chloroquine-resistant isolates . Characterization of Plasmid pRT1 from Pyrococcus sp . Strain JT1. Donald E. Ward, 2002.We discovered a 3,373-bp plasmid (pRT1) in the hyperthermophilic archaeon Pyrococcus sp . strain JT1 . Two major open reading frames were identified, and analysis of the sequence revealed some resemblance to motifs typically found in plasmids that replicate via a rolling-circle mechanism . The presence of single-stranded DNA replication intermediates of pRT1 was detected, confirming this mode of replication . Direct Profiling of Environmental Microbial Populations by Thermal Dissociation Analysis of Native rRNAs Hybridized to Oligonucleotide Microarrays. Said El Fantroussi, 2003.Oligonucleotide microarrays were used to profile directly extracted rRNA from environmental microbial populations without PCR amplification . In our initial inspection of two distinct estuarine study sites, the hybridization patterns were reproducible and varied between estuarine sediments of differing salinities . The determination of a thermal dissociation curve (i.e., melting profile) for each probe-target duplex provided information on hybridization specificity, which is essential for confirming adequate discrimination between target and nontarget sequences .
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