Plant regeneration from isolated cells ofLavandula latifolia medicus

Summary Single cells were obtained from hypocotyl-derived callus ofLavandula latifolia Medicus. Cells were plated in Murashige and Skoog medium supplemented with indoleacetic acid (IAA), benzyladenine (BA), and several IAA-BA combinations. Cell division required the simultaneous presence of IAA and BA in the culture medium, but callus formation was only achieved with 0.1 or 1 mg/liter IAA and 2 mg/liter BA. To induce organogenesis, calli were transferred to various regeneration media. Shoot-bud differentiation efficiency depended on the composition of both the callus induction and the shoot regeneration media, best results being obtained when calli grown in 1 mg/liter IAA and 2 mg/liter BA were subcultured to media containing 2 mg/liter BA and 15% coconut milk. Under these conditions, up to 75% of calli formed shoots that subsequently were rooted and established in soil.     

Factors affecting shoot proliferation and vitrification inDigitalis obscura cultures

Summary Variations of composition and consistency of the culture medium and time of exposure to growth regulators were assayed to optimize normal caulogenic response ofDigitalis obscura hypocotyls cultured in vitro. The effects of the culture conditions on physiologic changes related to vitrification of the regenerated plants were also investigated. Liquid medium increased the bud-forming capacity of the explants but induced buds failed to develop into shoots and showed symptoms of vitrification. On agar-solidified media, maximum multiplication rates were achieved with 0.7% agar. Increasing agar concentration reduced vitrification but lowered the propagation rate. Changes in the strength of the macronutrients of Murashige and Skoog did not significantly affect the bud-forming capacity of the explants. In contrast, a drastic inhibitory effect on both bud formation and shoot elongation was produced when NH₄NO₃ was omitted. Reduction of NH₄NO₃ to one-half or one-fourth of the level of the original formulation not only increased the bud-forming capacity ofD. obscura hypocotyls but also resulted in less vitrification. Modifications of time and method of exposure to growth regulators neither improved the multiplication rates nor overcame vitrification. Cardenolide content was lower in vitrified than in normal cultures and coincided with an overall reduction of photosynthetic pigments, lignin, and dry matter.     

Stimulatory effect of vasoactive intestinal peptide (VIP) on cyclic AMP production in rat peritoneal macrophages.

Vasoactive intestinal peptide (VIP) stimulated cyclic AMP production in rat peritoneal macrophages. The stimulatory effect of VIP was dependent on time, temperature and cell concentration, and was potentiated by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). At 15 degrees C, the response occurred in the 0.1-1000 nM range of VIP concentrations. Half maximal stimulation of cellular cyclic AMP (ED50) was obtained at 1.2 +/- 0.5 nM VIP, and maximal stimulation (about 3-fold basal level) was obtained between 100-1000 nM. The cyclic AMP system of rat peritoneal macrophages showed a high specificity for VIP. The order of potency observed in inducing cyclic AMP production was VIP greater than rGRF greater than hGRF greater than PHI greater than secretin. Glucagon, insulin, pancreastatin and octapeptide of cholecystokinin did not modify cyclic AMP levels at concentrations as high as 1 microM. The beta-adrenergic agonist isoproterenol increased the cyclic AMP production and show additive effect with VIP. Somatostatin inhibits the accumulation of cyclic AMP in the presence of both vasoactive intestinal peptide and isoproterenol. The finding of a VIP-stimulated cyclic AMP system in rat peritoneal macrophages, together with the previous characterization of high-affinity receptors for VIP in the same cell preparation, strongly suggest that VIP may be involved in the regulation of macrophage function.     

A morphogenetic role for ethylene in hypocotyl cultures of Digitalis obscura L.

The effect of exogenously applied ethylene on organogenesis in Digitalis obscura L. hypocotyls cultured in vitro was studied. Interactions of this gas with other growth regulators was also tested. Ethylene by itself only promoted root formation. Shoot regeneration was obtained in presence of indoleacetic acid and kinetin. The addition of ethylene (10 ppm) increased the caulogenetic action of this medium; higher concentrations than 10 ppm reduced this response. Kinetin alone did not promote organogenesis and nullified the promotive effect of ethylene on rhizogenesis.Abbreviations BM basal medium - IAA indoleacetic acid - Kn kinetin     

Utilización de marcadores ITS e ISSR para la caracterización molecular de cepas híbridas de Pleurotus djamor

Background

Molecular characterisation of wild type Pleurotus species is important for germplasm conservation and its further use for genetic improvement. No molecular studies have been performed with monokaryons used for producing hybrid strains, either with the reconstituted strains obtained by pairing those monokaryons. The molecular characterisation of parental dikaryons, hybrid, and reconstituted strains as well as monokaryotic strains, is therefore of utmost importance.

A review of heavy metal cation binding to deoxyribonucleic acids for the creation of chemical sensors

Various human activities lead to the pollution of ground, drinking, and wastewater with toxic metals. It is well known that metal ions preferentially bind to DNA phosphate backbones or DNA nucleobases, or both. Foreman et al. (Environ Toxicol Chem 30(8):1810–1818, 2011) reported the use of a DNA-dye based assay suitable for use as a toxicity test for potable environmental water. They compared the results of this test with the responses of live-organism bioassays. The DNA-based demonstrated that the loss of SYBR Green I fluorescence dye bound to calf thymus DNA was proportional to the toxicity of the water sample. However, this report raised questions about the mechanism that formed the basis of this quasi-quantitatively test. In this review, we identify the unique and preferred DNA-binding sites of individual metals. We show how highly sensitive and selective DNA-based sensors can be designed that contain multiple binding sites for 21 heavy metal cations that bind to DNA and change its structure, consistent with the release of the DNA-bound dye.     

Hexose metabolism in pancreatic islets: Effect of D-glucose on the mitochondrial redox state

The mitochondrial NADH/NAD⁺ ratio for free nucleotides in rat pancreatic islets was judged from the cell content in L-glutamate and L-alanine, 2-ketoglutarate and pyruvate, and NH ₄ ⁺ . At a physiological concentration of D-glucose, such a ratio averaged 9.6±1.1%. A rise in hexose concentrations, above a threshold value in excess of 5.6 mM, caused a rapid, sustained and rapidly reversible decrease in the mitochondrial NADH/NAD⁺ ratio. It is speculated that in the process of glucose-stimulated insulin release, the latter change participates in the coupling between metabolic and secretory events by favouring both the activity of key mitochondrial dehydrogenases and the translocation of Ca²⁺ from the mitochondria into the cytosol.