The Isolation and Evaluation of Two Naturally Occurring Mild Strains of Vanilla Necrosis Potyvirus for Control by Cross-Protection

In an attempt to find mild virus strains that would cross-protect sgainst vanilla necrosis potyvirus (VNPV), Vanilla fragrans plants in Tonga were surveyed for the presence of mild or symptomless potyvirus infections. Potyviruses were detected by indirect ELISA using a commercially available portyvirus group monoclonal anibody. From 28 plants with mild or symptomless infections two portyvirus isolates, designated V1 and V3, included systemic infections in Nicotiana benthamiana following mechanical inoculation. V1, which causes a mild mottle in N. benthamiana, is serologically related to VNPV, while V3 which causes mild vein banding is serologically unrelated to VNPV. Prior inoculation with V1 protected N. benthamiana against the severe mosaic symptoms of VNPV when challenge inoculated after 14 and 21 days, but not after 7 days. When V3 was used as the protecting strain, cross-protection was observed in some, but not all plants, when chalenged with VNPV after 14 and 21 days.     

Streptomycetes possess peptidyl-prolyl cis-trans isomerases that strongly resemble cyclophilins from eukaryotic organisms

A functionally active 17.5 kDa peptidyl-prolyl cis-trans isomerase was purified to homogeneity from Streptomyces chrysomallus, a Gram-positive filamentous bacterium. Characterization of the enzyme revealed inhibition and binding characteristics, against the immunsuppressive drug cyclosporin A, which were similar to cyclophilins from eukaryotes such as mammals, plants, fungi and yeasts, but different from those of cyclophilins from enterobacteria such as Escherichia coli. The amino acid sequence of the S. chrysomallus cyclophilin, as deduced from the gene sequence, revealed a striking degree of amino acid sequence identity with the corresponding 17 kDa proteins of humans (66%), Neurospora (70%) and yeast (69%). Comparison with cyclophilin sequences from the Gram-negative enterobacteria revealed much less homology (25% identity with E. coli b, 23% identity with E. coli a). Cyclophilin was detected in each of the four other Streptomyces species tested. The cyclophilins from the various streptomycetes differed in size, varying between 17 and 20.5 kDa. The cyclophilins were abundant in the Streptomyces cells, and present throughout growth.     

Cancer: improving early detection and prevention. A community practice randomised trial.

OBJECTIVE--To test the impact of physician education and facilitator assisted office system interventions on cancer early detection and preventive services. DESIGN--A randomised trial of two interventions alone and in combination. SETTING AND SUBJECTS--Physicians in 98 ambulatory care practices in the United States. INTERVENTIONS--The education intervention consisted of a day long physician meeting directed at improving knowledge, attitudes, and skills relevant to cancer prevention and early detection. The office system intervention consisted of assistance from a project facilitator in establishing routines for providing needed services. These routines included division of responsibilities for providing services among physicians and their staff and the use of medical record flow sheets. MAIN OUTCOME MEASURES--The proportions of patients provided the cancer prevention and early detection services indicated annually according to the US National Cancer Institute. RESULTS--Based on cross sectional patient surveys, the office system intervention was associated with an increase in mammography, the recommendation to do breast self examination, clinical breast examination, faecal occult blood testing, advice to quit smoking, and the recommendation to decrease dietary fat. Education was associated only with an increase in mammography. Record review for a patient cohort confirmed cross sectional survey findings regarding the office system for mammography and faecal occult blood testing. CONCLUSION--Community practices assisted by a facilitator in the development and implementation of an office system can substantially improve provision of cancer early detection and preventive services.     

The extraction and use of facial features in low bit-rate visual communication.

A review is given of experimental investigations by the author and his collaborators into methods of extracting binary features from images of the face and hands. The aim of the research has been to enable deaf people to communicate by sign language over the telephone network. Other applications include model-based image coding and facial-recognition systems. The paper deals with the theoretical postulates underlying the successful experimental extraction of facial features. The basic philosophy has been to treat the face as an illuminated three-dimensional object and to identify features from characteristics of their Gaussian maps. It can be shown that in general a composite image operator linked to a directional-illumination estimator is required to accomplish this, although the latter can often be omitted in practice.     

A general approach toward the design of inhibitors of serine proteinases: inhibition of human leukocyte elastase by substituted dihydrouracils

A general approach toward the rational design of potential inhibitors of serine proteinases is described. The approach is exemplified and validated through the use of appropriate heterocyclic systems in inhibiting human leukocytes elastase (HLE).     

Introduction of exogenous DNA into Chlamydomonas reinhardtii by electroporation.

The fate of exogenous DNA introduced into Chlamydomonas reinhardtii by electroporation was analyzed. With single and double electrical pulses, plasmids as large as 14 kb were introduced into cells with and without intact cell walls. Within hours after introduction, exogenous plasmid DNA was associated with nuclei isolated from cells; several weeks after introduction, exogenous DNA was stably integrated into the Chlamydomonas genome. These studies establish electroporation as a method for introducing DNA, and potentially other molecules, into C. reinhardtii.     

Potential role of poly(A) polymerase in the assembly of polyadenylation-specific RNP complexes.

To elucidate the mechanism by which poly(A) polymerase functions in the 3'-end processing of pre-mRNAs, polyadenylation-specific RNP complexes were isolated by sedimentation in sucrose density gradients and the fractions were analyzed for the presence of the enzyme. At early stages of the reaction, the RNP complexes were resolved into distinct peaks which sedimented at approximately 18S and 25S. When reactions were carried out under conditions which support cleavage or polyadenylation, the pre-mRNA was specifically assembled into the larger 25S RNP complexes. Polyclonal antibodies raised against the enzyme purified from a rat hepatoma, which have been shown to inhibit cleavage and polyadenylation (Terns, M., and Jacob, S. T., Mol. Cell. Biol. 9:1435-1444, 1989) also prevented assembly of the 25S polyadenylation-specific RNP complexes. Furthermore, formation of these complexes required the presence of a chromatographic fraction containing poly(A) polymerase. UV cross-linking analysis indicated that the purified enzyme could be readily cross-linked to pre-mRNA but in an apparent sequence-independent manner. Reconstitution studies with the fractionated components showed that formation of the 25S RNP complex required the poly(A) polymerase fraction. Although the enzyme has not been directly localized to the specific complexes, the data presented in this report supports the role of poly(A) polymerase as an essential component of polyadenylation-specific complexes which functions both as a structural and enzymatic constituent.     

Genetic mapping of the Xq27-q28 region: new RFLP markers useful for diagnostic applications in fragile-X and hemophilia-B families.

We have characterized and genetically mapped new polymorphic DNA markers in the q27-q28 region of the X chromosome. New informative RFLPs have been found for DXS105, DXS115, and DXS152. In particular, heterozygosity at the DXS105 locus has been increased from 25% to 52%. We have shown that DXS105 and DXS152 are contained within a 40-kb region. A multipoint linkage analysis was performed in fragile-X families and in large normal families from the Centre d'Etudes du Polymorphisme Humain (CEPH). This has allowed us to establish the order centromere-DXS144-DXS51-DXS102-F9-DXS105-FRAX A-(F8, DXS15, DXS52, DXS115). DXS102 is close to the hemophilia-B locus (z[theta] = 13.6 at theta = .02) and might thus be used as an alternative probe for diagnosis in Hemophila-B families not informative for intragenic RFLPs. DXS105 is 8% recombination closer to the fragile-X locus than F9 (z[theta] = 14.6 at theta = .08 for the F9-DXS105 linkage) and should thus be a better marker for analysis of fragile-X families. However, the DXS105 locus appears to be still loosely linked to the fragile-X locus in some families. The multipoint estimation for recombination between DXS105 and FRAXA is .16 in our set of data. Our data indicate that the region responsible for the heterogeneity in recombination between F9 and the fragile-X locus is within the DXS105-FRAXA interval.