Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

Methods of dental shade determination

Dental shade determination and seamless integration of restorative work in the oral cavity are challenging and important tasks in the everyday clinical dental practice. The aim of this in-vitro study was to evaluate comparatively the capability of software-based color analysis of mobile phone photography, with the spectrophotometric and visual methods for dental shade determination. Visual shade determination of the incisal, middle, and cervical thirds parts of ten extracted human teeth was performed using the Vita Classical and Vita 3D Master stock shade guides. Shade determination of the thirds of each tooth was performed using the Vita Easyshade spectrophotometer. Subsequently, photographs of each tooth were captured using a mobile phone camera. Color charts were produced using an in-house image processing technique, and the tooth color captured by the mobile phone photography was matched to the shade guides. The results show that the camera-based method had better agreement with the spectrophotometric and visual methods when the Vita Classical shade guide was employed. Software-based color analysis of mobile phone photography should be further explored for its use as an affordable potential tool for increasing objectivity and accuracy in dental shade determination

Inefficient purifying selection: the mammalian Y chromosome in the rodent genus Mus

Two related genes with potentially similar functions, one on the Y chromosome and one on the X chromosome, were examined to determine if they evolved differently because of their chromosomal positions. Six hundred fifty-seven base pairs of coding sequence of Jarid1d ( Smcy ) on the Y chromosome and Jarid1c ( Smcx ) on the X chromosome were sequenced in 13 rodent taxa. An analysis of replacement and silent substitutions, using a counting method designed for samples with small evolutionary distances, showed a significant difference between the two genes. The different patterns of replacement and silent substitutions within Jarid1d and Jarid1c may be a result of evolutionary mechanisms that are particularly strong on the Y chromosome because of its unique properties. These findings are similar to results of previous studies of Y chromosomal genes in these and other mammalian taxa, suggesting that genes on the mammalian Y evolve in a chromosome-specific manner.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46987/1/335_2005_Article_50.pd

Magnetodielectric Effects in Magnetorheological Elastomers Based on Polymer Fabric, Silicone Rubber, and Magnetorheological Suspension

We fabricate a hybrid magnetorheological elastomer (hMRE) based on a microfiber cloth soaked with a mixture containing magnetorheological suspension (MRS) and silicone rubber (SR). Two parallel copper electrodes are attached to the hMRE and the capacitance C is measured as a function of time t, for fixed values of magnetic flux density B. We show that C is stable in time and is sensibly influenced by B, while the relative dielectric permittivity increases up to two orders of magnitude when B reaches 340 mT. We explain the physical mechanism which leads to the observed magnetodielectric effects. The obtained results can be used for various biomedical applications such as in fabrication of active biomagnetic membranes used in dental implantology

Complete denture analyzed by optical coherence tomography

The complete dentures are currently made using different technologies. In order to avoid deficiencies of the prostheses made using the classical technique, several alternative systems and procedures were imagined, directly related to the material used and also to the manufacturing technology. Thus, at the present time, there are several injecting systems and technologies on the market, that use chemoplastic materials, which are heat cured (90-100°C), in dry or wet environment, or cold cured (below 60°C). There are also technologies that plasticize a hard cured material by thermoplastic processing (without any chemical changes) and then inject it into a mold. The purpose of this study was to analyze the existence of possible defects in several dental prostheses using a non invasive method, before their insertion in the mouth. Different dental prostheses, fabricated from various materials were investigated using en-face optical coherence tomography. In order to discover the defects, the scanning was made in three planes, obtaining images at different depths, from 0,01 μm to 2 mm. In several of the investigated prostheses we found defects which may cause their fracture. These defects are totally included in the prostheses material and can not be vizualised with other imagistic methods. In conclusion, en-face OCT is an important investigative tool for the dental practice