Determination of taxonomic resolution capacity of conventional one-dimensional SDS-polyacrylamide gel electrophoresis of whole-cell proteins using Enterobacteriaceae

The capacity of one-dimensional SDS-PAGE of whole bacterial cells to both separate and cluster taxonomic units is studied using members of Enterobacteriaceae as test material. The results show that intraspecies variation can be detected and on the other hand the degree of taxonomic divergence which still can be grouped together is determined. In addition the system has high tolerance to changes in cell culture conditions making the usage of SDS-PAGE suitable for applications where rapid and reliable bacterial identification is needed.     

Improved distribution of antigenic site specificity of poliovirus-neutralizing antibodies induced by a protease-cleaved immunogen in mice.

Previous studies showed that the distribution of antigenic site specificity of neutralizing antibodies to type 3 poliovirus obtained with the inactivated poliovirus vaccine can be deficient as compared with that obtained following poliovirus infection. This observation was shown by the relatively low capacity of sera from inactivated-poliovirus-vaccine-immunized persons to neutralize poliovirus cleaved at antigenic site 1. We investigated possibilities for improving the situation in a mouse model. Balb/c mice were immunized with intact or trypsin-cleaved type 3 poliovirus (Saukett strain). Sera from mice immunized with the intact virus readily neutralized the intact virus but neutralized the cleaved virus only rarely. In contrast, cleaved-virus-immunized mice produced antibodies that were able to neutralize the cleaved virus as well as the intact one. Mice immunized with a 100-fold-higher dose of the intact virus produced significant levels of antibodies to the cleaved virus, too. Somewhat surprisingly, mice immunized with high doses of the cleaved virus produced antibodies specific for the intact loop between beta sheets B and C of VP1 (virion protein 1), which should be cleaved in the immunogen. This was shown by a higher titer of antibodies to intact Saukett virus than to the corresponding cleaved virus, as well as to a type 1/type 3 hybrid poliovirus in which only the BC loop amino acids were derived from type 3 poliovirus. The cleavage-induced enhanced availability of antigenic determinants residing outside the BC loop was also shown by increased neutralization titers of monoclonal antibodies specific for some of these other determinants. These results indicate that by using a trypsin-cleaved type 3 poliovirus as a parenteral immunogen, it is possible to change the distribution of antigenic site specificities of neutralizing antibodies to resemble that following poliovirus infection.     

Chloroplast DNA variation inAnemone s. lato (Ranunculaceae)

Chloroplast DNA of seven species belonging toAnemone (sectt.Omalocarpus, Anemonidium, andAnemonanthea),Hepatica, andPulsatilla have been analyzed by restriction enzymes. According to the dendrogram constructed, the sections ofAnemone and the generaHepatica andPulsatilla seem to be evolutionary approximately equidistant to each others. This supports the concept that these groups should be treated on a similar taxonomic level, either as genera or subgenera.     

Antibodies to the vitronectin receptor (integrin alpha V beta 3) inhibit binding and infection of foot-and-mouth disease virus to cultured cells.

The amino acid sequence Arg-Gly-Asp (RGD) is highly conserved on the VP1 proteins of different serotypes and subtypes of foot-and-mouth disease virus (FMDV) and is essential for cell attachment. This sequence is also found in certain extracellular matrix proteins that bind to a family of cell surface receptors called integrins. Within the Picornaviridae family, enterovirus coxsackievirus A9 also has an RGD motif on its VP1 capsid protein and has recently been shown to utilize the vitronectin receptor integrin alpha V beta 3 as a receptor on monkey kidney cells. Competition binding experiments between type A12 FMDV and coxsackievirus A9 using BHK-21 and LLC-MK2 cells revealed shared receptor specificity between these two viruses. Polyclonal anti-serum to the vitronectin receptor and a monoclonal antibody to the alpha V subunit inhibited both FMDV binding and plaque formation, while a monoclonal antibody to the beta 3 subunit inhibited virus binding. In contrast, antibodies to the fibronectin receptor (alpha 5 beta 1) or to the integrin (alpha V beta 5) had no effect on either binding or plaque formation. These data demonstrate that the alpha V beta 3 vitronectin receptor can function as a receptor for FMDV.     

The localization of the β-subtype of protein kinase C (PKC-β) in rat sympathetic neurons

Summary The localization of PKC- was studied in rat sympathetic neurons using a polyclonal antibody specific for the ₁- and ₂-subspecies. The tissues studied included the superior cervical (SCG) and hypogastric (HGG) ganglia and the target tissues of the SCG and HGG neurons: the submandibular gland, iris, prostate and vas deferens. PKC--LI was found in nerve fibers in both ganglia. A proportion of the fibers in the SCG disappeared after decentralization, suggesting that the fibers were of both pre- and postganglionic origin. The somata of the HGG and SCG neurons expressed varying amounts of PKC--LI, the majority of SCG neurons being labelled only after colchicine treatment. In all target tissues there were PKC--immunoreactive nerve fibers in bundles, but the most peripheral branches of the fibers were negatively labelled. The results show that PKC--LI is widely present in sympathetic postganglionic neurons with mainly quantitative differences. The lack of PKC- in the most peripheral branches of nerve fibers might be a general feature of sympathetic postganglionic neurons, suggesting that the participation of PKC- in neurotransmitter release and in other functions in nerve terminals in sympathetic adrenergic neurons is unlikely.     

Selection for outbreeding in Varroa parasitising resistant honey bee (Apis mellifera) colonies

Parasitism is expected to select for counter‐adaptations in the host: driving a coevolutionary arms race. However, human interference between honey bees (Apis mellifera) and Varroa mites removes the effect of natural selection and restricts the evolution of host counter‐adaptations. With full‐sibling mating common among Varroa, this can rapidly select for virulent, highly inbred, Varroa populations. We investigated how the evolution of host resistance could affect the infesting population of Varroa mites. We screened a Varroa‐resistant honey bee population near Toulouse, France, for a Varroa resistance trait: the inhibition of Varroa's reproduction in drone pupae. We then genotyped Varroa which had co‐infested a cell using microsatellites. Across all resistant honey bee colonies, Varroa's reproductive success was significantly higher in co‐infested cells but the distribution of Varroa between singly and multiply infested cells was not different from random. While there was a trend for increased reproductive success when Varroa of differing haplotypes co‐infested a cell, this was not significant. This suggests local mate competition, through the presence of another Varroa foundress in a pupal cell, may be enough to help Varroa overcome host resistance traits; with a critical mass of infesting Varroa overwhelming host resistance. However, the fitness trade‐offs associated with preferentially co‐infesting cells may be too high for Varroa to evolve a mechanism to identify already‐infested cells. The increased reproductive success of Varroa when co‐infesting resistant pupal cells may act as a release valve on the selective pressure for the evolution of counter resistance traits: helping to maintain a stable host–parasite relationship.