Influence of transmucosal designs of three one-piece implant systems on early tissue responses: a histometric study in beagle dogs.

PURPOSE: The purpose of this study was to investigate the early tissue response around three one-piece implant systems with different transmucosal designs. MATERIALS AND METHODS: Three one-piece dental implant systems with different profiles and surface roughnesses on the transmucosal portion were examined in the current study. The transmucosal portions were flared and machined (FM), concave and machined with microgrooves (CMG), or straight and anodic oxidized (SA). A total of 30 implants (10 of each type) were placed in computer-generated randomized order in the mandibular residual ridges of five beagle dogs. Six months later, all animals were sacrificed and histologic sections were prepared to measure epithelial tissue height, connective tissue contact, and the amount of bone resorption. One-way analysis of variance and the Bonferroni post hoc test were used for statistical evaluation (alpha = 95%). RESULTS: After a 6-month nonfunctional loading period, all 30 implants were clinically immobile. Slight swelling and redness of the peri-implant soft tissue were noticed around most of the implant abutments. Histometric analysis showed that the FM implants had a longer epithelial tissue height than the CMG implants. The CMG implants showed the greatest amount of connective tissue attachment among the three groups and the least amount of marginal bone resorption. The CMG and SA implants showed bone growth above the initial reference point at 10 and 7 measurement sites, respectively, whereas no bone overgrowth was noted around the FM implants. CONCLUSION: Based on this study conducted in five beagle dogs, a concave transmucosal profile with a microgrooved surface was associated with longer connective tissue attachments and less bone resorption versus implants that were flared with a machined surface or straight with an anodic oxidized surface in the early healing phase. Int J Oral Maxillofac Implants 2010;25:309-314.

The diageotropica gene of tomato encodes a cyclophilin: a novel player in auxin signaling.

The single gene, auxin-resistant diageotropica (dgt) mutant of tomato displays a pleiotropic auxin-related phenotype that includes a slow gravitropic response, lack of lateral roots, reduced apical dominance, altered vascular development, and reduced fruit growth. Some auxin responses are unaltered in dgt plants, however, and the levels, metabolism, and transport of auxin appear normal, indicating that the Dgt gene encodes a component of a specific auxin signaling pathway. By combining map-based cloning with comparative microsynteny, we determined that the Dgt gene encodes a cyclophilin (CYP) (LeCYP1; gi:170439) that has not previously been identified as a component of auxin signaling and plant development. Each of the three known dgt alleles contains a unique mutation in the coding sequence of LeCyp1. Alleles dgt(1-1)and dgt(1-2) contain single nucleotide point mutations that generate an amino acid change (G137R) and a stop codon (W128stop), respectively, while dgt(dp) has an amino acid change (W128CDelta129-133) preceding a 15 bp deletion. Complementation of dgt plants with the wild-type LeCyp1 gene restored the wild-type phenotype. Each dgt mutation reduced or nullified the peptidyl-prolyl isomerase activity of the GST-LeCYP1 fusion proteins in vitro. RT-PCR and immunoblot analyses indicated that the dgt mutations do not affect the expression of LeCyp1 mRNA, but the accumulation of LeCYP1 protein is greatly reduced for all three mutant alleles. The CYP inhibitor, cyclosporin A, partially mimics the effects of the dgt mutation in inhibiting auxin-induced adventitious root initiation in tomato hypocotyl sections and reducing the auxin-induced expression of the early auxin response genes, LeIAA10 and 11. These observations confirm that the PPIase activity of the tomato CYP, LeCYP1, encoded by the Dgt gene is important for specific aspects of auxin regulation of plant growth, development, and environmental responses.

Fine mapping in tomato using microsynteny with the Arabidopsis genome: the Diageotropica (Dgt) locus.

BACKGROUND: The Arabidopsis thaliana genome sequence provides a catalog of reference genes applicable to comparative microsynteny analysis of other species, facilitating map-based cloning in economically important crops. We have applied such an analysis to the tomato expressed sequence tag (EST) database to expedite high-resolution mapping of the Diageotropica (Dgt) gene within the distal end of chromosome 1 in tomato (Lycopersicon esculentum). RESULTS: A BLAST search of the Arabidopsis database with nucleotide sequences of markers that flank the tomato dgt locus revealed regions of microsynteny between the distal end of chromosome 1 in tomato, two regions of Arabidopsis chromosome 4, and one on chromosome 2. Tomato ESTs homeologous to Arabidopsis gene sequences within those regions were converted into co-dominant molecular markers via cleaved amplified polymorphic sequence (CAPS) analysis and scored against an informative backcross mapping population. Six new microsyntenic EST (MEST) markers were rapidly identified in the dgt region, two of which further defined the placement of the Dgt gene and permitted the selection of a candidate tomato bacterial artificial chromosome clone for sequence analysis. CONCLUSIONS: Microsynteny-based comparative mapping combined with CAPS analysis of recombinant plants rapidly and economically narrowed the dgt mapping region from 0.8 to 0.15 cM. This approach should contribute to developing high-density maps of molecular markers to target-specific regions for positional cloning and marker-assisted selection in a variety of plants.