Exploiting a wheat EST database to assess genetic diversity

Expressed sequence tag (EST) markers have been used to assess variety and genetic diversity in wheat (Triticum aestivum). In this study, 1549 ESTs from wheat infested with yellow rust were used to examine the genetic diversity of six susceptible and resistant wheat cultivars. The aim of using these cultivars was to improve the competitiveness of public wheat breeding programs through the intensive use of modern, particularly marker-assisted, selection technologies. The F2 individuals derived from cultivar crosses were screened for resistance to yellow rust at the seedling stage in greenhouses and adult stage in the field to identify DNA markers genetically linked to resistance. Five hundred and sixty ESTs were assembled into 136 contigs and 989 singletons. BlastX search results showed that 39 (29%) contigs and 96 (10%) singletons were homologous to wheat genes. The database-matched contigs and singletons were assigned to eight functional groups related to protein synthesis, photosynthesis, metabolism and energy, stress proteins, transporter proteins, protein breakdown and recycling, cell growth and division and reactive oxygen scavengers. PCR analyses with primers based on the contigs and singletons showed that the most polymorphic functional categories were photosynthesis (contigs) and metabolism and energy (singletons). EST analysis revealed considerable genetic variability among the Turkish wheat cultivars resistant and susceptible to yellow rust disease and allowed calculation of the mean genetic distance between cultivars, with the greatest similarity (0.725) being between Harmankaya99 and Sönmez2001, and the lowest (0.622) between Aytin98 and Izgi01

Single-copy nuclear genes resolve the phylogeny of the holometabolous insects

Background: Evolutionary relationships among the 11 extant orders of insects that undergo complete metamorphosis, called Holometabola, remain either unresolved or contentious, but are extremely important as a context for accurate comparative biology of insect model organisms. The most phylogenetically enigmatic holometabolan insects are Strepsiptera or twisted wing parasites, whose evolutionary relationship to any other insect order is unconfirmed. They have been controversially proposed as the closest relatives of the flies, based on rDNA, and a possible homeotic transformation in the common ancestor of both groups that would make the reduced forewings of Strepsiptera homologous to the reduced hindwings of Diptera. Here we present evidence from nucleotide sequences of six single-copy nuclear protein coding genes used to reconstruct phylogenetic relationships and estimate evolutionary divergence times for all holometabolan orders. Results: Our results strongly support Hymenoptera as the earliest branching holometabolan lineage, the monophyly of the extant orders, including the fleas, and traditionally recognized groupings of Neuropteroidea and Mecopterida. Most significantly, we find strong support for a close relationship between Coleoptera (beetles) and Strepsiptera, a previously proposed, but analytically controversial relationship. Exploratory analyses reveal that this relationship cannot be explained by long-branch attraction or other systematic biases. Bayesian divergence times analysis, with reference to specific fossil constraints, places the origin of Holometabola in the Carboniferous (355 Ma), a date significantly older than previous paleontological and morphological phylogenetic reconstructions. The origin and diversification of most extant insect orders began in the Triassic, but flourished in the Jurassic, with multiple adaptive radiations producing the astounding diversity of insect species for which these groups are so well known. Conclusion: These findings provide the most complete evolutionary framework for future comparative studies on holometabolous model organisms and contribute strong evidence for the resolution of the 'Strepsiptera problem', a long-standing and hotly debated issue in insect phylogenetics

Ultrastructure of smear layer-covered intraradicular dentin after irrigation with BioPure MTAD

The structure of mechanically instrumented intraradicular dentin after irrigation with NaOCl as the initial rinse and BioPure MTAD as the final rinse were examined from the coronal, middle, and apical parts of root canal walls using transmission electron microscopy. Sterile distilled water and EDTA as final rinses were employed as the respective positive and negative controls under the same experimental conditions. There were 2 to 5 μm thick smear layers produced on mechanically instrumented root canal walls that were completely removed by EDTA and BioPure MTAD under agitation. Both irrigants created a zone of demineralized collagen matrices in eroded dentin and around the dentinal tubules, with the mildly acidic BioPure MTAD being more aggressive than EDTA. These demineralized dentin zones create the opportunity for dentin hybridization by infiltration of hydrophilic adhesives/sealers. However, the potential consequences of compaction of hydrophobic sealers against air-dried, collapsed collagen matrices, and hydrolytic degradation of incompletely infiltrated matrices remain unresolved. Copyright © 2006 by the American Association of Endodontists.link_to_subscribed_fulltex

Bondability of Resilon to a Methacrylate-Based Root Canal Sealer

Resilon broadens the dimensions of endodontic adhesion by introducing the possibility of creating monoblocs between root canal filling materials and intraradicular dentin by using methacrylate-based sealers. The adhesive strength of Resilon to RealSeal, a methacrylate-based root canal sealer, was evaluated using a modified microshear bond testing design. Flat Resilon surfaces with different roughness were created for bonding to the sealer and compared to a composite control. The composite control exhibited mean shear strength 7.3 to 26.9 times higher than those of the Resilon groups. Shear strength differences among the Resilon groups of different surface roughness highlighted the contribution of micromechanical versus chemical coupling in sealer retention. Ultrastructural evidence of phase separation of polymeric components in Resilon suggested that the amount of dimethacrylate incorporated into this filled, thermoplastic composite may not yet be optimized for effective chemical coupling to methacrylate-based sealers

Improving the performance of EndoREZ root canal sealer with a dual-cured two-step self-etch adhesive. II. Apical and coronal seal

This study tested the hypothesis that the seal of EndoREZ may be improved with an adhesive-modified technique. Instrumented single-rooted teeth were filled with: (a) Warm vertical compaction with AH Plus (control); (b). EndoREZ with master cones and passive application of accessory cones; (c) Application of Clearfil Liner Bond 2V before EndoREZ and gutta-percha condensation. Leakage was assessed by fluid filtration at 10 psi before root resection and after 3 to 12 mm apical resections. Statistical analyses revealed significant differences in filling technique and resection lengths. EndoREZ exhibited significantly higher overall leakage, while no difference was found between AH Plus and the adhesive-modified EndoRez technique. Apical resection of EndoREZ to 12 mm exhibited more leakage than all other interactions, but was not significantly different from the same material resected to 9 mm. Although EndoREZ exhibited an acceptable apical seal, its coronal seal may be improved with the use of a dual-cured self-etch adhesive

Sentinel lymph nodes in the rat: noninvasive photoacoustic and US imaging with a clinical US system

Purpose: To evaluate in vivo sentinel lymph node (SLN) mapping by using photoacoustic and ultrasonographic (US) imaging with a modified clinical US imaging system. Materials and Methods: Animal protocols were approved by the Animal Studies Committee. Methylene blue dye accumulation in axillary lymph nodes of seven healthy Sprague-Dawley rats was imaged by using a photoacoustic imaging system adapted from a clinical US imaging system. To investigate clinical translation, the imaging depth was extended up to 2.5 cm by adding chicken or turkey breast on top of the rat skin surface. Three-dimensional photoacoustic images were acquired by mechanically scanning the US transducer and light delivery fiber bundle along the elevational direction. Results: Photoacoustic images of rat SLNs clearly help visualization of methylene blue accumulation, whereas coregistered photoacoustic/US images depict lymph node positions relative to surrounding anatomy. Twenty minutes following methylene blue injection, photoacoustic signals from SLN regions increased nearly 33-fold from baseline signals in preinjection images, and mean contrast between SLNs and background tissue was 76.0 +/- 23.7 (standard deviation). Methylene blue accumulation in SLNs was confirmed photoacoustically by using the optical absorption spectrum of the dye. Three-dimensional photoacoustic images demonstrate dynamic accumulation of methylene blue in SLNs after traveling through lymph vessels. Conclusion: In vivo photoacoustic and US mapping of SLNs was successfully demonstrated with a modified clinical US scanner. These results raise confidence that photoacoustic and US imaging can be used clinically for accurate, noninvasive imaging of SLNs for axillary lymph node staging in breast cancer patients. (C) RSNA, 2010X11154sciescopu