Publications

4364

SUMMARY Phytoplasmas are plant‐pathogenic bacteria that are associated with numerous plant diseases. We have previously reported the complete genomic sequence of Candidatus Phytoplasma asteris, OY strain, OY‐M line, which causes mild symptoms. The phytoplasma genome lacks several important metabolic genes, implying that the consumption of metabolites by phytoplasmas in plants may cause disease symptoms. Here we show that the approximately 30‐kb region including the glycolytic genes was tandemly duplicated in the genome of OY‐W phytoplasma, which causes severe symptoms. Almost duplicated genes became pseudogenes by frameshift and stop‐codon mutations, probably because of their functional redundancy. However, five kinds of genes, including two glycolytic genes, remained full‐length ORFs, suggesting that it is advantageous for the phytoplasma to retain these genes in its lifestyle. In particular, 6‐phosphofructokinase is known as a rate‐limiting enzyme of glycolysis, implying that the different number of glycolytic genes between OY‐W and OY‐M may influence their respective glycolysis activities. We previously reported that the phytoplasma population of OY‐W was higher than that of OY‐M in their infected plants. Taking this result into account, the higher consumption of the carbon source may affect the growth rate of phytoplasmas and also may directly or indirectly cause more severe symptoms.

Although Mycoplasma haemofelis and "Candidatus Mycoplasma haemominutum" infections have been reported in wild cats from United States, their presence among native and captive wild cats in Brazil is still unknown. A 12 year old healthy male lion (Panthera leo) from the Zoological Garden of Curitiba, Brazil was anesthetized for transportation and dental evaluation. A blood sample was obtained for a complete blood cell count (CBC) and PCR analysis. DNA was extracted and fragments of Mycoplasma haemofelis and "Candidatus Mycoplasma haemominutum" 16S ribosomal RNA gene were amplified in PCR assays. CBC results were within reference intervals. A weak band of 192 pb for "Candidatus Mycoplasma haemominutum" was observed, and no band was amplified from Mycoplasma haemofelis reaction. A weak PCR band associated with normal CBC results and without visible parasitemia or clinical signs may suggest a chronic subclinical infection with "Candidatus Mycoplasma haemominutum". The lack of clinical signs may also represent the low pathogenicity of this organism; however, it is noteworthy that immune suppression caused by management and/or corticoids treatment may induce parasitemia and anemia in this animal. This detection suggests further studies in captive wild cats in Brazilian Zoological Gardens.

Phylogenetic analysis and phenotypic characterization were used to assign a multicellular magnetotactic prokaryote the name ‘Candidatus Magnetoglobus multicellularis’. ‘Candidatus Magnetoglobus multicellularis' lives in a large hypersaline coastal lagoon from Brazil and has properties that are unique among prokaryotes. It consists of a compact assembly or aggregate of flagellated bacterial cells, highly organized in a sphere, that swim in either helical or straight trajectories. The life cycle of ‘Candidatus Magnetoglobus multicellularis' is completely multicellular, in which one aggregate grows by enlarging the size of its cells and approximately doubling the volume of the whole organism. Cells then divide synchronously, maintaining the spherical arrangement; finally the cells separate into two identical aggregates. Phylogenetic 16S rRNA gene sequence analysis showed that ‘Candidatus Magnetoglobus multicellularis' is related to the dissimilatory sulfate-reducing bacteria within the Deltaproteobacteria and to other previously described, but not yet well characterized, multicellular magnetotactic prokaryotes.

ABSTRACT The pigment composition of “ Candidatus Chlorothrix halophila,” a filamentous anoxygenic phototrophic bacterium found in Baja California Sur, Mexico, was determined. Previous work showed that bacteriochlorophyll c (BChl c ) was the major pigment in “ Ca . Chlorothrix halophila,” but it was not clear if this bacterium also contains BChl a (J. A. Klappenbach and B. K. Pierson, Arch. Microbiol. 181: 17-25, 2004). Here we show that in addition to BChl c , a small amount of a pigment that is spectrally indistinguishable from BChl a is present in cell extracts of “ Ca . Chlorothrix halophila.” Nevertheless, the BChl a -like pigment from “ Ca . Chlorothrix halophila” has a different molecular weight and a different high-performance liquid chromatography elution time than BChl a from other photosynthetic bacteria. Based on mass spectrometry and other spectroscopic analysis, we determined that the BChl a -like pigment in “ Ca . Chlorothrix halophila” contains a tetrahydrogeranylgeraniol tail rather than the phytol tail that is present in BChl a . The carotenoids and major BChl c homologs in “ Ca . Chlorothrix halophila” were also identified. BChls c were found to be farnesol esterified and geranylgeraniol esterified.