Using FTA® cards to store avian blood samples for genetic studies. Their application in sex determination

FTA® cards were used for long‐term storage of avian blood samples. Blood DNA was extracted by a simple method and used in PCR for sex identification of adult and nestling Great Grey Shrikes Lanius excubitor.     

Characterization of a light-dependent glutamate synthase activity in Chlamydomonas reinhardtii

Photosynthetically active vesicles prepared from Chlamydomonas reinhardtii retained a light-dependent glutamate synthase activity which was highly specific for 2-oxoglutarate (K_m=2.1 mM) and L-glutamine (K_m=0.9 mM) as amido group acceptor and donor respectively. This activity was inhibited by azaserine, p-hydroxymercuribenzoate and 3-(p-chlorophenyl)-1,1-dimethyl urea.Light-dependent synthesis of glutamate was also obtained by coupling Chlamydomonas photosynthetic particles to purified ferredoxin-glutamate synthase, using ascorbate and 2,6-dichlorophenol-indophenol as electron donor. This system was also specific for 2-oxoglutarate (K_m=1 mM) and L-glutamine (K_m=0.8 mM) as substrates, and was stimulated by dithioerythritol. Azaserine and p-hydroxymercuribenzoate, but not 3-(p-chlorophenyl)-1,1-dimethyl urea, inhibited the reconstituted activity; high concentrations of 2-oxoglutarate were inhibitory.Abbreviations A Absorbance - CCP p-Trichlorometoxi-carbonylcyanide-phenylhydrazone - Chl Chlorophyll - CMU 3-(p-Chlorophenyl)-1,1-dimethyl urea - DPIP 2,6-Dichlorophenol-indophenol - DTE Dithioerythritol - MSX L-Methionine, D-L, sulfoximine - MV Methyl viologen     

Friedländer reaction on 2-amino-3-cyano-4H-pyrans: Synthesis of derivatives of 4H-pyran [2,3-b] quinoline, new tacrine analogues

The unprecedented Friedländer reaction of densely functionalized 2-amino-3-cyano-4H-pyrans (1) with cyclohexanone has afforded in one step and good yield 5-amino-4-aryl-3-ethoxycarbonyl-2-methyl-6,7,8,9-tetrahydro-4H-pyran[2,3-b]quinolines (2), novel amino-substituted fused pyran derivatives. These compounds are new tacrine analogues.     

Neurotrophic Effects of l-DOPA in Postnatal Midbrain Dopamine Neuron/Cortical Astrocyte Cocultures

Abstract: l -DOPA is toxic to catecholamine neurons in culture, but the toxicity is reduced by exposure to astrocytes. We tested the effect of l -DOPA on dopamine neurons using postnatal ventral midbrain neuron/cortical astrocyte cocultures in serum-free, glia-conditioned medium. l -DOPA (50 µ M ) protected against dopamine neuronal cell death and increased the number and branching of dopamine processes. In contrast to embryonically derived glia-free cultures, where l -DOPA is toxic, postnatal midbrain cultures did not show toxicity at 200 µ M l -DOPA. The stereoisomer d -DOPA (50–400 µ M ) was not neurotrophic. The aromatic amino acid decarboxylase inhibitor carbidopa (25 µ M ) did not block the neurotrophic effect. These data suggest that the neurotrophic effect of l -DOPA is stereospecific but independent of the production of dopamine. However, l -DOPA increased the level of glutathione. Inhibition of glutathione peroxidase by l -buthionine sulfoximine (3 µ M for 24 h) blocked the neurotrophic action of L-DOPA. N -Acetyl- l -cysteine (250 µ M for 48 h), which promotes glutathione synthesis, had a neurotrophic effect similar to that of l -DOPA. These data suggest that the neurotrophic effect of l -DOPA may be mediated, at least in part, by elevation of glutathione content.     

Nitrogen-fixing cyanobacteria as source of phycobiliprotein pigments. Composition and growth performance of ten filamentous heterocystous strains

Ten strains of filamentous, heterocystous nitrogen-fixing blue-green algae (cyanobacteria) were screened for growth performance and tolerance to temperature, pH, irradiance and salinity, together with their potential as producers of phycobiliprotein pigments. Phycobiliproteins typically accounted for about 50% total cell protein, the prevalent type being C-phycocyanin, followed by alloppycocyanin, with levels of 17 and 11% d.wt, respectively, in some strains of Anabaena and Nostoc. C-phycoerythrin was the major pigment in several Nostoc strains, reaching 10% d.wt. Some strains represent, therefore, excellent sources of one or more phycobiliproteins. All strains tolerated an irradiance of ca 2000 μmol photon m^-2 s^-1. Anabaena sp. ATCC 33047 and Nostoc sp. (Albufera) exhibited the widest optimum range of both temperature (30–45 and 25–40 °C) and pH (6.5–9.5 and 6.0–9.0) for growth, the former also showing significant salt tolerance. In an outdoor open system, productivity of cultures of two phycoerythrin-rich strains of Nostoc was over 20 g (d.wt) m^-2 d^-1 during summer. The growth performance of the allophycocyanin-rich Anabaena sp. ATCC 33047 in outdoor semi-continuous culture has been assessed throughout the year. Productivity values under optimized conditions ranged from 9 (winter) to 24 (summer) g (d.wt) m^-2 d^-1.     

Partial deletion of 4p16 band in a ring chromosome and wolf syndrome

Summary A new case of ring chromosome 4 in a 2-day-old female child with multiple malformations is described. By means of the GTG-banding technique, a karyotype 46,XX,r(4), (p16q35) was determined. The characteristics of the child's karyotype and the relationship with the structure of the chromosome, especially the location of the deletion that produces the syndrome, are compared with previous reports.     

The kinetic mechanisms of the bifunctional enzyme aspartokinase-homoserine dehydrogenase I from Escherichia coli

The kinetic mechanisms of the reactions catalyzed by the two catalytic domains of aspartokinase-homoserine dehydrogenase I from Escherichia coli have been determined. Initial velocity, product inhibition, and dead-end inhibition studies of homoserine dehydrogenase are consistent with an ordered addition of NADPH and aspartate beta-semialdehyde followed by an ordered release of homoserine and NADP+. Aspartokinase I catalyzes the phosphorylation of a number of L-aspartic acid analogues and, moreover, can utilize MgdATP as a phosphoryl donor. Because of this broad substrate specificity, alternative substrate diagnostics was used to probe the kinetic mechanism of this enzyme. The kinetic patterns showed two sets of intersecting lines that are indicative of a random mechanism. Incorporation of these results with the data obtained from initial velocity, product inhibition, and dead-end inhibition studies at pH 8.0 are consistent with a random addition of L-aspartic acid and MgATP and an ordered release of MgADP and beta-aspartyl phosphate.     

High temperature effects on photosynthetic activity of two tomato cultivars with different heat susceptibility

The functional activities of the photosynthetic apparatus of two tomato cultivars of different thermotolerance were investigated after a short period of high temperature treatment. Seedlings of two tomato genotypes, Lycopersicon esculentum var. Campbell-28 and the wild thermotolerant Nagcarlang, were grown under a photoperiod of 16h at 25 degrees C and dark period of 8h at 20 degrees C. At the fourth true leaf stage, a group of plants was exposed to heat stress of 45 degrees C for 2 h. The heat shock treatment caused important reductions of the net photosynthetic rate (Pn) of Campbell-28 plants due to non-stomatal components. These non-stomatal effects were not evident in Nagcarlang-treated plants. This reduction in the CO2 assimilation rate observed in Campbell-28 was generated by affections in the Calvin cycle and also in the PSII functioning. No changes in these parameters were observed in the thermotolerant genotype after the stress. Injury to the plasma membrane because of the heat stress was evident only in the Campbell-28 genotype. Heat led to a sun-type adaptation response of the photosynthesis pigment apparatus for the Nagcarlang genotype, but not for Campbell-28, and thus an increase in chlorophyll a/b ratio and a decrease in chlorophyll/carotenoid ratio were shown in Nagcarlang stressed plants.