Publications

cospeciation of psyllids and their primary prokaryotic endosymbionts.	psyllids are plant sap-feeding insects that harbor prokaryotic endosymbionts in specialized cells within the body cavity. four-kilobase dna fragments containing 16s and 23s ribosomal dna (rdna) were amplified from the primary (p) endosymbiont of 32 species of psyllids representing three psyllid families and eight subfamilies. in addition, 0.54-kb fragments of the psyllid nuclear gene wingless were also amplified from 26 species. phylogenetic trees derived from 16s-23s rdna and from the host wing ...	2000	10877784
secondary endosymbionts of psyllids have been acquired multiple times.	previous studies have established that psyllids (hemiptera, psylloidea) contain primary endosymbionts, designated as carsonella ruddii, which cospeciate with the psyllid host. this association appears to be the consequence of a single infection of a psyllid ancestor with a bacterium. some psyllids may have additional secondary (s-) endosymbionts. we have cloned and sequenced the 16s-23s ribosomal rna genes of seven representative psyllid s-endosymbionts. comparison of the s-endosymbiont phylogen ...	2000	10977900
degenerative minimalism in the genome of a psyllid endosymbiont.	psyllids, like aphids, feed on plant phloem sap and are obligately associated with prokaryotic endosymbionts acquired through vertical transmission from an ancestral infection. we have sequenced 37 kb of dna of the genome of carsonella ruddii, the endosymbiont of psyllids, and found that it has a number of unusual properties revealing a more extreme case of degeneration than was previously reported from studies of eubacterial genomes, including that of the aphid endosymbiont buchnera aphidicola. ...	2001	11222582
phylogenetic analysis of vertically transmitted psyllid endosymbionts (candidatus carsonella ruddii) based on atpagd and rpoc: comparisons with 16s-23s rdna-derived phylogeny.	psyllids are insects that harbor endosymbionts (candidatuus carsonella ruddii) within specialized cells found in the insect's body cavity. previous phylogenetic analyses based on endosymbiont 16s-23s ribosomal dna and a host gene were concordant (m.l. thao, et al., appl. env. microbiol. 66:2898, 2000). additional analyses with atpagd and rpobc gave similar trees showing the agreement expected from organisms that evolve through vertical transmission with no gene exchange.	2001	11381334
the genetic properties of the primary endosymbionts of mealybugs differ from those of other endosymbionts of plant sap-sucking insects.	mealybugs (hemiptera, coccoidea, pseudococcidae), like aphids and psyllids, are plant sap-sucking insects that have an obligate association with prokaryotic endosymbionts that are acquired through vertical, maternal transmission. we sequenced two fragments of the genome of tremblaya princeps, the endosymbiont of mealybugs, which is a member of the beta subdivision of the proteobacteria. each of the fragments (35 and 30 kb) contains a copy of 16s-23s-5s rrna genes. a total of 37 open reading fram ...	2002	12088995
extracting single genomes from heterogenous dna samples: a test case with carsonella ruddii, the bacterial symbiont of psyllids (insecta).	analysis of many bacterial genomes is impeded by the inability to separate individual species from complex mixtures of cells or to propagate cells in pure culture. this problem is an obstacle to the study of many bacterial symbionts that live intracellularly in insects and other animals. to recover bacterial dna from complex samples, we devised a method that facilitates the cloning of dna fragments of distinctive g+c contents in order to generate shotgun dna libraries enriched in inserts having ...	2005	16299593
the 160-kilobase genome of the bacterial endosymbiont carsonella.	previous studies have suggested that the minimal cellular genome could be as small as 400 kilobases. here, we report the complete genome sequence of the psyllid symbiont carsonella ruddii, which consists of a circular chromosome of 159,662 base pairs, averaging 16.5% gc content. it is by far the smallest and most at-rich bacterial genome yet characterized. the genome has a high coding density (97%) with many overlapping genes and reduced gene length. genes for translation and amino acid biosynth ...	2006	17038615
the frontier between cell and organelle: genome analysis of candidatus carsonella ruddii.	bacterial symbioses are widespread among insects. the early establishment of such symbiotic associations has probably been one of the key factors for the evolutionary success of insects, since it may have allowed access to novel ecological niches and to new imbalanced food resources, such as plant sap or blood. several genomes of bacterial endosymbionts of different insect species have been recently sequenced, and their biology has been extensively studied. recently, the complete genome sequence ...	2007	17908294
genome size of pachypsylla venusta (hemiptera: psyllidae) and the ploidy of its bacteriocyte, the symbiotic host cell that harbors intracellular mutualistic bacteria with the smallest cellular genome.	psyllids harbor the primary symbiont, carsonella ruddii (gamma-proteobacteria), within the cytoplasm of specialized cells called bacteriocytes. carsonella has the smallest known cellular genome (160 kb), lacking numerous genes that appear to be essential for bacterial life. this raises the question regarding the genetic mechanisms of the host which supports the survival of carsonella. our preceding analyses have indicated that some of the genes that are encoded in the psyllid genome and which ar ...	2010	19302725
phylogeny of gammaproteobacteria.	the phylogeny of the large bacterial class gammaproteobacteria has been difficult to resolve. here we apply a telescoping multiprotein approach to the problem for 104 diverse gammaproteobacterial genomes, based on a set of 356 protein families for the whole class and even larger sets for each of four cohesive subregions of the tree. although the deepest divergences were resistant to full resolution, some surprising patterns were strongly supported. a representative of the acidithiobacillales rou ...	2010	20207755
diversity of endosymbionts in the potato psyllid, bactericera cockerelli (triozidae), vector of zebra chip disease of potato.	zebra chip disease is an emerging, serious disease of solanaceous crops and the causal agent is a bacterium "candidatus liberibacter solanacearum" (cls), also known as "candidatus liberibacter psyllaurous", which is transmitted by the potato psyllid, bactericera cockerelli (šulc). we performed bacterial tag-encoded flx amplicon pyrosequencing (btefap) of the 16s rdna genes to determine the bacterial microbiota in adult insects from cls-uninfected and cls-infected strains of b. cockerelli and pot ...	2011	21327558