Localization of 'Candidatus Liberibacter solanacearum' and Evidence for Surface Appendages in the Potato Psyllid Vector.

The potato psyllid Bactericera cockerelli is implicated as the vector of the causal agent of zebra chip of potato and vein-greening of tomato diseases. Until now, visual identification of bacteria in the genus 'Candidatus Liberibacter' has relied on direct imaging by light and electron microscopy without labeling, or with whole-organ fluorescence labeling only. In this study, aldehyde fixative followed by a coagulant fixative, was used to process adult psyllids for transmission electron microscopy (TEM) colloidal gold in situ hybridization experiments. Results indicated that 'Ca. Liberibacter solanacearum' (CLso)-specific DNA probes annealed to a bacterium that formed extensive, monocultural biofilms on gut, salivary gland, and oral region tissues, confirming that it is one morphotype of potentially others, that is rod-shaped, approximately 2.5 µm in diameter and of variable length, and has a rough, granular cytosol. In addition, CLso, prepared from shredded midguts, and negatively stained for TEM, possessed pili- and flagella-like surface appendages. Genes implicating coding capacity for both types of surface structures are encoded in the CLso genome sequence. Neither type was seen for CLso associated with biofilms within or on digestive organs, suggesting that their production is stimulated only in certain environments, putatively, in the gut during adhesion leading to multiplication, and in hemolymph to afford systemic invasion.

Reasons given by California physical therapists for not belonging to the american physical therapy association.

BACKGROUND AND PURPOSE: In 1997, only 22% of licensed physical therapists living in California were members of the American Physical Therapy Association (APTA). This 1998 study was designed to identify the reason(s) why most licensed physical therapists in California choose not to belong to their profession's national association and to examine the demographics of nonmembers. SUBJECTS: The subjects were a random sample of 400 California licensed physical therapists who were not members of APTA. METHODS: The survey instrument included a demographic questionnaire and statements for response using a 5-point Likert-type scale. Frequency distributions were calculated for responses and demographic data. Nonparametric analyses were used to determine statistical significance. Chi-square analysis was used to compare responses to statements by gender and by full-time versus part-time work status. Spearman rank correlation coefficients were used to determine any relationships between demographic data (eg, gender and work status). The Mann-Whitney U test was used to determine any differences in responses to specific representation questions by those respondents who worked in those environments. All statistical tests were 2-tailed tests conducted at the P(.05 level, unless otherwise indicated. Means, standard deviations, and ranges were used where appropriate. RESULTS: There was a 67% response rate. Eighty-nine percent of the respondents had been members of APTA. Eighty-eight percent of the respondents believed that APTA national dues were too high, and 90% thought California Chapter dues were too high. DISCUSSION AND CONCLUSION: Cost was the primary reason given for APTA nonmembership in California.

Characterization of a cytosolic fucosylation pathway in Dictyostelium.

FP21 is a 21-kDa fucoprotein which fractionates with the cytosol after high-speed centrifugation of gently lysed Dictyostelium cells. Less than 0.7% of FP21 is associated with vesicles. In proliferating cells, 4 x 10(5) fucosyl moieties/cell are associated with FP21 as anionic, possibly O-linked oligosaccharides equal in size to 4.8 glucose units. FP21 is underfucosylated in a mutant strain (HL250) that depends on extracellular fucose for synthesis of GDP-fucose. To determine the cellular site of FP21 fucosylation, cytosolic and vesicular preparations from strain HL250 were compared for their ability to transfer fucose from GDP-fucose to FP21. Cytosolic preparations fucosylate endogenous FP21 in a time-, concentration-, and divalent cation-dependent fashion, with a Km for GDP-fucose of 1.4 microM. Activity in normal cell cytosol is dependent on exogenous mutant FP21, demonstrating that FP21 is normally fully fucosylated. Both mutant and normal cytosols are also able to alpha-fucosylate a type 1 glycolipid substrate (8-methoxycarbonyloctyl-Gal beta 1-3 beta GlcNAc), but not related substrates, with Km values for the type 1 glycolipid of 0.99 mM and for GDP-fucose of 1.6 microM. Competitive inhibition between FP21 and the type 1 glycolipid shows that the same enzyme fucosylates both substrates. Intact and permeabilized vesicle preparations from wild-type cells are unable to fucosylate FP21 or the type 1 glycolipid by a divalent cation-dependent mechanism, and thus are devoid of FP21-fucosyltransferase. Since control experiments showed that vesicle leakage is minimal during cytosol preparation, these results indicate that FP21 is synthesized and fucosylated in the cytosolic compartment, by an unusual soluble fucosyltransferase.