Optimization of regeneration and transformation parameters in tomato and improvement of its salinity and drought tolerance

As part of our efforts to improve tomato tolerance to abiotic stress, we have undertaken this study to introduce two candidate genes encoding: a sodium antiporter and a vacuolar pyrophosphatase, previously shown to enhance drought and salt tolerance in transgenic Arabidopsis plants. First, we evaluated the potential of primary leaves from three to four week-old in vitro-grown tomato seedlings as alternative explants to cotyledons for tomato transformation. Our results demonstrated that primaryleaves are three times more efficient then cotyledons in terms of regeneration percentage, productivity, and transformation frequencies independently of the medium and genetic construct used. Second,primary leaves were used to introduce the genes of interest using Agrobacterium-mediated transformation. Many transgenic tomato plants were easily recovered. The presence of the transgenes and their expression were confirmed by PCR and RT-PCR analysis. The transformation frequencies for primary leaf explants ranged from 4 to 10% depending on the genetic construct used. The time requiredfrom inoculation of primary leaves with Agrobacterium cells to transfer of transgenic tomato plants to soil was only 2 months compared to 3 to 4 months using standard tomato transformation protocols. The transgenic tomato plants obtained in the current study were more tolerant to salinity and drought stress than their wild-type counterparts

Elaboration and characterization by XRD and SEM of the glass-ceramics in BaTiO3 – NaPO3 system

There is a strong need for low cost glass-ceramic materials whose high chemical stability and dielectric properties can be engineered flexibly in bulk and fiber forms. Therefore we have manufactured transparent ferroelectric glass-ceramics consisting of barium titanate (BT) crystallites in a chain metaphosphate glass matrix. Several glass compositions, in the series (1-x) NaPO3 – x BaTiO3 have been prepared by a conventional melt quenching method. The compositions have been selected on the basis of chemical stability. X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate the formation of small particle size of BaTiO3 in the glass network when its amount is above 4 mol%.There is a strong need for low cost glass-ceramic materials whose high chemical stability and dielectric properties can be engineered flexibly in bulk and fiber forms. Therefore we have manufactured transparent ferroelectric glass-ceramics consisting of barium titanate (BT) crystallites in a chain metaphosphate glass matrix. Several glass compositions, in the series (1-x) NaPO3 – x BaTiO3 have been prepared by a conventional melt quenching method. The compositions have been selected on the basis of chemical stability. X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate the formation of small particle size of BaTiO3 in the glass network when its amount is above 4 mol%

Is there a common water-activity limit for the three domains of life?

Archaea and Bacteria constitute a majority of life systems on Earth but have long been considered inferior to Eukarya in terms of solute tolerance. Whereas the most halophilic prokaryotes are known for an ability to multiply at saturated NaCl (water activity (a w) 0.755) some xerophilic fungi can germinate, usually at high-sugar concentrations, at values as low as 0.650-0.605 a w. Here, we present evidence that halophilic prokayotes can grow down to water activities of <0.755 for Halanaerobium lacusrosei (0.748), Halobacterium strain 004.1 (0.728), Halobacterium sp. NRC-1 and Halococcus morrhuae (0.717), Haloquadratum walsbyi (0.709), Halococcus salifodinae (0.693), Halobacterium noricense (0.687), Natrinema pallidum (0.681) and haloarchaeal strains GN-2 and GN-5 (0.635 a w). Furthermore, extrapolation of growth curves (prone to giving conservative estimates) indicated theoretical minima down to 0.611 a w for extreme, obligately halophilic Archaea and Bacteria. These were compared with minima for the most solute-tolerant Bacteria in high-sugar (or other non-saline) media (Mycobacterium spp., Tetragenococcus halophilus, Saccharibacter floricola, Staphylococcus aureus and so on) and eukaryotic microbes in saline (Wallemia spp., Basipetospora halophila, Dunaliella spp. and so on) and high-sugar substrates (for example, Xeromyces bisporus, Zygosaccharomyces rouxii, Aspergillus and Eurotium spp.). We also manipulated the balance of chaotropic and kosmotropic stressors for the extreme, xerophilic fungi Aspergillus penicilloides and X. bisporus and, via this approach, their established water-activity limits for mycelial growth (∼0.65) were reduced to 0.640. Furthermore, extrapolations indicated theoretical limits of 0.632 and 0.636 a w for A. penicilloides and X. bisporus, respectively. Collectively, these findings suggest that there is a common water-activity limit that is determined by physicochemical constraints for the three domains of life

Dielectric and Raman Studies of 0.935(Bi0.5Na0.5TiO3)−0.065BaTiO30.935(Bi_{0.5}Na_{0.5}TiO_3)-0.065BaTiO_3 Lead Free Ceramics

The $0.935(Na_{0.5}Bi_{0.5})TiO_3-0.065BaTiO_3$ lead free ceramic was synthesized by conventional solid state reaction technique. Sintering was done at 1200°C for 4 h in air atmosphere. Dielectric and Raman spectroscopic studies have been performed as a function of temperature from 25 to 450°C. The phase transitions from ferroelectric to antiferroelectric and from antiferroelectric to paraelectric order were observed through the dielectric measurements. Further support for the obtained results was drawn from the Raman spectroscopy measurements

X-ray diffraction, dielectric, pyroelectric, piezoelectric and Ramanspectroscopystudies on (Ba0.95Ca0.05)0.8875Bi0.075TiO3 ceramic

The (Ba0.95Ca0.05)0.8875Bi0.075TiO3ceramic composition was prepared using the conventional mixed-oxide technique. X-raydiffraction at room temperature and dielectric permittivity in the temperature range from 85 to 450 K and frequency range from 102 to 2 × 105 Hz, respectively, were studied. The X-ray spectra were investigated by profile refinement technique with the use of specialized software at room temperature, the (Ba0.95Ca0.05)0.8875Bi0.075TiO3 composition crystallizes in quadratic perovskite structure. The dielectric measurements show classical ferroelectric behavior. The pyroelectric and piezoelectric results confirm the dielectric measurements. The pyroelectric coefficient is about 69.2 nC/cm2 K at the transition temperature (TC = 367 K). The piezoelectric constant is d31 = 31.1 pC/N and the electromechanical coupling factor is kP = 0.14679. Raman spectra of (Ba0.95Ca0.05)0.8875Bi0.075TiO3ceramic were taken at various temperatures and measured over the wave number range from 50 to 1000 cm−1. All the Raman bands were assigned as the transitional modes of Ba2+, Ca2+, Bi3+ and Ti4+ cations. The temperature evolution of Raman spectra across the transition shows an important evolution characterizing the disorder of the high temperature phase