Putative Phage Hyperparasite in the Rickettsial Pathogen of Abalone, “Candidatus Xenohaliotis californiensis”

Studies on the ecology of microbial parasites and their hosts are predicated on understanding the assemblage of and relationship among the species present. Changes in organismal morphology and physiology can have profound effects on host–parasite interactions and associated microbial community structure. The marine rickettsial organism, “Candidatus Xenohaliotis californiensis” (WS-RLO), that causes withering syndrome of abalones has had a consistent morphology based on light and electron microscopy. However, a morphological variant of the WS-RLO has recently been observed infecting red abalone from California. We used light and electron microscopy, in situ hybridization and16S rDNA sequence analysis to compare the WS-RLO and the morphologically distinct RLO variant (RLOv). The WS-RLO forms oblong inclusions within the abalone posterior esophagus (PE) and digestive gland (DG) tissues that contain small rod-shaped bacteria; individual bacteria within the light purple inclusions upon hematoxylin and eosin staining cannot be discerned by light microscopy. Like the WS-RLO, the RLOv forms oblong inclusions in the PE and DG but contain large, pleomorphic bacteria that stain dark navy blue with hematoxylin and eosin. Transmission electron microscopy (TEM) examination revealed that the large pleomorphic bacteria within RLOv inclusions were infected with a spherical to icosahedral-shaped putative phage hyperparasite. TEM also revealed the presence of rod-shaped bacteria along the periphery of the RLOv inclusions that were morphologically indistinguishable from the WS-RLO. Binding of the WS-RLO-specific in situ hybridization probe to the RLOv inclusions demonstrated sequence similarity between these RLOs. In addition, sequence analysis revealed 98.9–99.4 % similarity between 16S rDNA sequences of the WS-RLO and RLOv. Collectively, these data suggest that both of these RLOs infecting California abalone are “Candidatus Xenohaliotis californiensis,” and that the novel variant is infected by a putative phage hyperparasite that induced morphological variation of its RLO host.     

Tool-use by a rook (Corvus frugilegus), and its causation

A young captive rook, Corvus frugilegus, inserted a plug into a plug-hole in its aviary floor so that a pool of water formed, which was used by all four rooks in the aviary for drinking and bathing. The bird was selective about which, of six holes, it chose for insertion of the tool, choosing the appropriate one with respect to the water source. Days on which attempted or successful tool-use occurred were drier than other days, and days of successful tool-uses were also warmer. Availability of fresh water to the birds did not influence the occurrence of tool-use.     

Internode length in Pisum. I. The effect of the Le/le gene difference on endogenous gibberellin-like substances

The allelopathic potential of the dry fruits of Washingtonia filifera (L. Linden) H. Wendl. was investigated. Leachates from fruits inhibited the germination of lettuce, wheat, red cabbage and cucumber seeds. The inhibitory effect was partly neutralized by kinetin (20 mg 1⁻¹) and gibberellic acid (50 mg 1⁻¹). The effect of kinetin was more pronounced at 25°C than at 20°C. Substances inhibiting germination were localized in the pericarp of the fruit and were resistant to high temperature.     

The measurement of regional rates of cerebral protein synthesis in vivo

Special issue dedicated to Dr. Louis Sokoloff.     

Targeting of porin to the outer membrane of Escherichia coli. Rate of trimer assembly and identification of a dimer intermediate

Porin, a transmembrane protein in the outer membrane of Escherichia coli, exists in a trimeric structure which is not dissociated during sodium dodecyl sulfate-polyacrylamide gel electrophoresis at 25 degrees C. This unusual stability was utilized in the study of the conformational changes which accompany the targeting of porin to the outer membrane. A delay of 16-44 s between completion of synthesis of a monomer and its assembly into a trimer was found from the ratio of monomers to trimers found in exponentially growing cells. Pulse-chase experiments showed that rapid processing of precursor OmpF molecules was followed by assembly into sodium dodecyl sulfate-resistant oligomers with a half-time of 20 s at 30 degrees C. An intermediate in assembly was isolated by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis below 10 degrees C and was identified as a metastable dimer.