The transcriptome of the arbuscular mycorrhizal fungus Glomus intraradices (DAOM 197198) reveals functional tradeoffs in an obligate symbiont

• The arbuscular mycorrhizal symbiosis is arguably the most ecologically important eukaryotic symbiosis, yet it is poorly understood at the molecular level. To provide novel insights into the molecular basis of symbiosis-associated traits, we report the first genome-wide analysis of the transcriptome from Glomus intraradices DAOM 197198. • We generated a set of 25,906 nonredundant virtual transcripts (NRVTs) transcribed in germinated spores, extraradical mycelium and symbiotic roots using Sanger and 454 sequencing. NRVTs were used to construct an oligoarray for investigating gene expression. • We identified transcripts coding for the meiotic recombination machinery, as well as meiosis-specific proteins, suggesting that the lack of a known sexual cycle in G. intraradices is not a result of major deletions of genes essential for sexual reproduction and meiosis. Induced expression of genes encoding membrane transporters and small secreted proteins in intraradical mycelium, together with the lack of expression of hydrolytic enzymes acting on plant cell wall polysaccharides, are all features of G. intraradices that are shared with ectomycorrhizal symbionts and obligate biotrophic pathogens. • Our results illuminate the genetic basis of symbiosis-related traits of the most ancient lineage of plant biotrophs, advancing future research on these agriculturally and ecologically important symbionts.

Efficient construction of a large nonimmune phage antibody library: the production of high-affinity human single-chain antibodies to protein antigens

A large library of phage-displayed human single-chain Fv antibodies (scFv), containing 6.7 x 10(9) members, was generated by improving the steps of library construction. Fourteen different protein antigens were used to affinity select antibodies from this library. A panel of specific antibodies was isolated with each antigen, and each panel contained an average of 8.7 different scFv. Measurements of antibody-antigen interactions revealed several affinities below 1 nM, comparable to affinities observed during the secondary murine immune response. In particular, four different scFv recognizing the ErbB2 protein had affinities ranging from 220 pM to 4 nM. Antibodies derived from the library proved to be useful reagents for immunoassays. For example, antibodies generated to the Chlamydia trachomatis elementary bodies stained Chlamydia-infected cells, but not uninfected cells. These results demonstrate that phage antibody libraries are ideally suited for the rapid production of panels of high-affinity mAbs to a wide variety of protein antigens. Such libraries should prove especially useful for generating reagents to study the function of gene products identified by genome projects.

Success rate and failures for fixed partial dentures after 20 years of service: Part I

PURPOSE

The objective of this study was to identify failures and to assess rate for fixed partial dentures constructed 20 years earlier by general practitioners in Sweden.

MATERIALS AND METHODS

The original group consisted of 164 patients who had received prosthodontic treatment in 1974 comprising fixed partial dentures with at least five units. They had all been selected at random from the files of the Swedish Federal Dental Insurance Register. Twenty years later, 98 of them could be located and 72 of them agreed to participate in a clinical examination. The majority of drop-outs of the original group had died, could not be traced, or could not participate because of medical reasons. The examination focused on removed prostheses and/or units and a number of other clinically valid variables that will be reported in a forthcoming article. The 26 patients not participating in the clinical examination were interviewed by telephone.

RESULTS

The examined participants had a total of 140 fixed partial dentures, 557 retainers, and 383 pontics still in service. When the number of failed and removed prostheses was calculated, a cumulative success rate of 65% was found, i.e., one third had been lost since 1974. There was no difference in failures between fixed partial dentures with or without cantilevers during the previous 8 years compared to the first 12 years in service. Loss of retention together with periodontal and esthetic problems, wear, and discoloration of acrylic veneers were the most frequently reported reasons for removal.

CONCLUSIONS

The cumulative success rate for fixed partial dentures placed in 1974 was 65%. Failed prostheses had in most cases been replaced by a new fixed partial denture.

Axial wall convergence of full veneer crown preparations. Documented for dental students and general practitioners

The convergence angle in 478 full crown preparations was assessed. Of these preparations, 351 had been performed by general practitioners and 127 by dental students. Groups of preparations performed on incisors, premolars, and molars were compared, as were preparations performed by dentists and students. Two different convergence angles were measured for each tooth, buccolingually and mesiodistally. The results showed a mean angle of 21 degrees. The mean values for premolars and molars differed significantly. When a comparison was made of preparations performed by students, a significant difference was found between premolars and molars. The same comparison for general practitioners showed a significant difference both for incisors compared with molars and for premolars compared with molars. A wide range was found for the convergence of the axial walls, especially for the preparations performed by general practitioners.