The inter-relationship between the age of carrot roots at harvest and infection by Mycocentrospora acerina in storage

Infection of carrot roots by Mycocenlrospora acerina in chill storage (3.5 °C) following inoculation with chlamydospores was studied in 1973–74 and 1974–75. AREAS of intact periderm were only rarely infected, and the high level of periderm resistance predominated over other variables. However, wound infection tended to increase with depth of wound and with increasing age of the plants at harvest. Irrespective of age of root or depth of wound, roots were comparatively resistant to infection at harvest and early in storage, resistance being expressed as a restriction of mycelial growth on the wound surface or localisation of the lesion. Increasing susceptibility with time in storage, depth of wounds, or age at harvest, resulted in larger numbers of inoculated sites becoming infected and a more rapid development from localised to progressive lesions.     

Monoclonal antibodies directed against surface-associated polypeptides of Treponema pallidum define a biologically active antigen

Murine monoclonal antibodies (Mabs) were raised against two outer-membrane-associated polypeptides of Treponema pallidum (47 and 44 kDa). Three Mabs against each polypeptide were investigated further and only those directed against the 44 kDa polypeptide were demonstrated to have immobilizing activity. The specificity of the Mabs for T. pallidum was determined by Western blotting procedures and the surface association of the antigens was inferred by immunogold electron microscopy. The clear distinction between these two polypeptides in their biological activity could help to explain the pathobiology of syphilis infections as the 47 kDa antigen has been shown to be associated with the outer membrane of this organism. Inactivity of such a surface-located protein in antibody-mediated anti-treponemal mechanisms could account for the observed ability of this organism to survive in the face of strong antibody responses in infection.