Publications

4482

Summary Many hemipterans are associated with symbiotic bacteria, which are usually found intracellularly in specific bacteriomes. In this study, we provide the first molecular identification of the bacteriome‐associated, obligate endosymbiont in a G ondwanan relict insect taxon, the moss bugs ( H emiptera: C oleorrhyncha: P eloridiidae), which represents one of the oldest lineages within the H emiptera. Endosymbiotic associations of fifteen species of the family were analysed, covering representatives from S outh A merica, A ustralia/ T asmania and N ew Z ealand. Phylogenetic analysis based on four kilobases of 16 S –23 S r RNA gene fragments showed that the obligate endosymbiont of P eloridiidae constitute a so far unknown group of G ammaproteobacteria which is named here ‘ Candidatus Evansia muelleri’. They are related to the sternorrhynchous endosymbionts C andidatus   P ortiera and C andidatus   C arsonella. Comparison of the primary‐endosymbiont and host ( COI  + 28 S rRNA ) trees showed overall congruence indicating co‐speciation the hosts and their symbionts. The distribution of the endosymbiont within the insect body and its transmission was studied using FISH . The endosymbionts were detected endocellularly in a pair of bacteriomes as well as in the ‘symbiont ball’ of the posterior pole of each developing oocyte. Furthermore, ultrastructural analysis of the M alpighian tubules revealed that most host nuclei are infected by an endosymbiotic, intranuclear bacterium that was determined as an A lphaproteobacterium of the genus R ickettsia .

ABSTRACT The draft genome sequence of a single orange Beggiatoa (“ Candidatus Maribeggiatoa”) filament collected from a microbial mat at a hydrothermal site in Guaymas Basin (Gulf of California, Mexico) shows evidence of extensive genetic exchange with cyanobacteria, in particular for sensory and signal transduction genes. A putative homing endonuclease gene and group I intron within the 23S rRNA gene; several group II catalytic introns; GyrB and DnaE inteins, also encoding homing endonucleases; multiple copies of sequences similar to the fdxN excision elements XisH and XisI (required for heterocyst differentiation in some cyanobacteria); and multiple sequences related to an open reading frame (ORF) (00024_0693) of unknown function all have close non- Beggiatoaceae matches with cyanobacterial sequences. Sequences similar to the uncharacterized ORF and Xis elements are found in other Beggiatoaceae genomes, a variety of cyanobacteria, and a few phylogenetically dispersed pleiomorphic or filamentous bacteria. We speculate that elements shared among filamentous bacterial species may have been exchanged in microbial mats and that some of them may be involved in cell differentiation.

ABSTRACT We report here the draft genome sequence of “ Candidatus Liberibacter americanus” strain PW_SP. The 1,176,071-bp genome, with 31.6% G+C content, comprises 948 open reading frames, 38 tRNAs, and three complete rRNAs.