Publications

4475

ABSTRACT “ Candidatus Midichloria mitochondrii,” an intracellular symbiont of the tick Ixodes ricinus , is the only described organism able to invade the mitochondria of any multicellular organism. We used quantitative PCR to examine cycles of bacterial growth and death throughout the host's development and found that they correspond with the phases of engorgement and molt, respectively.

ABSTRACT A new huanglongbing (HLB) “ Candidatus Liberibacter” species is genetically characterized, and the bacterium is designated “ Candidatus Liberibacter psyllaurous.” This bacterium infects the psyllid Bactericera cockerelli and its solanaceous host plants potato and tomato, potentially resulting in “psyllid yellowing.” Host plant-dependent HLB transmission and variation in psyllid infection frequencies are found.

Feline haemoplasma infection can cause haemolytic anaemia. The natural method of transmission of haemoplasmas between cats is currently unknown but the nature of some of the risk factors for infection suggests that saliva may act as a mode of transmission. The aim of this study was to determine if Mycoplasma haemofelis (Mhf) and ‘ Candidatus Mycoplasma haemominutum’ (CMhm) DNAs could be amplified from saliva and salivary gland samples collected from haemoplasma-infected cats.

ABSTRACT Triple-agent therapy with lansoprazole (15 mg/kg)-clarithromycin (50 mg/kg)-amoxicillin (50 mg/kg) twice daily for 7 days fully cleared “ Candidatus Helicobacter heilmannii” from infected mouse stomachs. Moreover, gastric mucosa-associated lymphoid tissue lymphoma-like lesions in the stomach nearly disappeared in the treated mice 4 months after the therapy.

Abstract A sequence analysis is described of a fosmid clone from a coastal marine metagenomic library that contains a 16S rRNA gene with high sequence similarity to that of the SAR11 bacterium ‘Candidatus Pelagibacter ubique’ HTCC1062. The sequence of the fosmid clone was 32 086 bp in length and contained 23 187 bp of the 48-kb hyper-variable region 2 (HVR2) present in the genome of ‘Cand. P. ubique’. However, half of the sequences within the HVR2 region of the fosmid clone show little sequence similarity to or have no representative homologues in the genome sequence of ‘Cand. P. ubique’ HTCC1062. Given their putative functions, the acquisition of these genes suggests that SAR11 could harbour more diverse phenotypes than represented by the 16S rRNA taxonomy. Variation in SAR11 genomes from different locations might explain why SAR11 is abundant in so many diverse marine provinces.

ABSTRACT Buchnera aphidicola BCc, the primary endosymbiont of the aphid Cinara cedri (subfamily Lachninae), is losing its symbiotic capacity and might be replaced by the coresident “ Candidatus Serratia symbiotica.” Phylogenetic and morphological analyses within the subfamily Lachninae indicate two different “ Ca . Serratia symbiotica” lineages and support the longtime coevolution of both symbionts in C. cedri .

ABSTRACT “ Candidatus Pelagibacter ubique,” an abundant marine alphaproteobacterium, subsists in nature at low ambient nutrient concentrations and may often be exposed to nutrient limitation, but its genome reveals no evidence of global regulatory mechanisms for adaptation to stationary phase. High-resolution capillary liquid chromatography coupled online to an LTQ mass spectrometer was used to build an accurate mass and time (AMT) tag library that enabled quantitative examination of proteomic differences between exponential- and stationary-phase “ Ca . Pelagibacter ubique” cells cultivated in a seawater medium. The AMT tag library represented 65% of the predicted protein-encoding genes. “ Ca . Pelagibacter ubique” appears to respond adaptively to stationary phase by increasing the abundance of a suite of proteins that contribute to homeostasis rather than undergoing a major remodeling of its proteome. Stationary-phase abundances increased significantly for OsmC and thioredoxin reductase, which may mitigate oxidative damage in “ Ca . Pelagibacter,” as well as for molecular chaperones, enzymes involved in methionine and cysteine biosynthesis, proteins involved in ρ-dependent transcription termination, and the signal transduction enzyme CheY-FisH. We speculate that this limited response may enable “ Ca . Pelagibacter ubique” to cope with ambient conditions that deprive it of nutrients for short periods and, furthermore, that the ability to resume growth overrides the need for a more comprehensive global stationary-phase response to create a capacity for long-term survival.