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41.
Hypocotyls of Albizia odoratissima cultured on shoot induction medium (MS medium with 7.5 μM BAP and 0.5 μM NAA) showed adventitious shoot organogenesis under
light with 16 h photoperiod. Similar cultures under total darkness produced non-morphogenic calli. The changes in the specific
peroxidase and catalase activity, total protein content and acidic isoperoxidase pattern were compared between the culture
showing shoot organogenesis and culture producing non-morphogenic calli. It was found that in vitro shoot bud differentiation
is accompanied by an increase of the specific activities of peroxidase and catalase in culture kept under light. In parallel
with the above changes the total protein content reached to the maximum level and also a new isoperoxidase (P10) expressed
on the 21st day in cultures kept under light. Conversely, culture producing non-morphogenic calli underwent a reverse change
in specific peroxidase activity. This change in antioxidant enzyme activities corresponds to the histological observation
of shoot bud differentiation in cultures kept under light. 相似文献
42.
Apoflavodoxin from the sulfate reducing bacteria Desulfovibrio desulfuricans is a small, acidic protein with a net charge of -19 at neutral pH. Here, we show that monovalent cations in biologically relevant amounts have dramatic effects on apoflavodoxin stability. The effect is largest for Gdm(+) and decreases as a function of increased cation charge density (Gdm(+)>NH(4)(+)K(+) approximately Cs(+) approximately Na(+)>Li(+)). A linear correlation of stabilizing effects with cation hydration properties suggests an important role of dehydration in efficient cation interaction with the protein. The effects on stability are due to preferential binding of one cation to native apoflavodoxin and results in an increase in thermal midpoint of 20 degrees C and the free energy of unfolding (at 20 degrees C) increases fivefold. Tuning of biophysical properties (such as folding and ligand/cofactor binding) of acidic proteins by cation binding may be important in vivo. 相似文献
43.
Hu F Sun WW Zhao XT Cui ZJ Yang WX 《Biochemical and biophysical research communications》2008,369(4):989-993
Synoviocyte hyperplasia is critical for rheumatoid arthritis, therefore, potentially an important target for therapeutics. It was found in this work that a TRPV1 agonist capsaicin, and acidic solution (pH 5.5) induced increases in cytosolic calcium concentration ([Ca2+]c) and reactive oxygen species (ROS) production in synoviocytes isolated from a rat model of collagen-induced arthritis. The increases in both [Ca2+]c and ROS production were completely abolished in calcium-free buffer or by a TRPV1 antagonist capsazepine. Further experiments revealed that capsaicin and pH 5.5 solution caused mitochondrial membrane depolarization and reduction in cell viability; such effects were inhibited by capsazepine, or the NAD(P)H oxidase inhibitor diphenylene iodonium. Both capsaicin and pH 5.5 buffer induced apoptosis as shown by nuclear condensation and fragmentation. Furthermore, RT-PCR readily detected TRPV1 mRNA expression in the isolated synoviocytes. Taken together, these data indicated that TRPV1 activation triggered synoviocyte death by [Ca2+]c elevation, ROS production, and mitochondrial membrane depolarization. 相似文献
44.
Seven different strains were selected for their ability to degrade citrus pectin. Alkaline pectinases were produced by five bacterial soil isolates, whereas two fungal strains produced pectinase in an acidic environment. The bacteria were isolated from soil of a plum orchard in Northern Ireland. These isolates produced significant amounts of pectin lyase (PL) and polygalacturonase (PG) with maximum activities of 30.1 and 29.1 U/ml respectively. Fungal strains Aspergillus sp. and PN-1 produced four different pectinolytic activities; endo-PG, exo-PG, pectin esterase (PE) and PL. The Aspergillus sp. produced higher amounts of pectinase than PN-1. The Aspergillus sp. excreted highly stable pectinases, which may be of importance for industrial applications. 相似文献
45.
Response of Picea rubens seedlings to intermittent mist varying in acidity, and in concentrations of sulfur-, and nitrogen-containing pollutants 总被引:7,自引:0,他引:7
Jay S. Jacobson Twylene Bethard Laurence I. Heller James P. Lassoie 《Physiologia plantarum》1990,78(4):595-601
Two-year-old red spruce seedlings ( Picea rubens Sarg .) growing in. field chambers were repeatedly exposed to acidic mist with a factorial combination of 3 fluctuating levels of acidity: median pH values of 3.0 (range of 2.5 to 3.5), 3.5 (range of 3.0 to 4.0), and 4.0 (range of 3.5 to 4.5). and 3 ion compositions: sulfate. nitrate and ammonium, and a combination of all 3 ions. The experiment was performed during the growing season over a period of 3.5 months. Mist exposures were intermittent with 5 wet-dry cycles for each 16-h overnight exposure period, Foliar necrosis occurred on seedlings treated with the most acidic mist and was most severe when the mist contained sulfate. At a median pH of 3.5, a value close to that of cloud water occurring in the eastern United States, injury developed with sulfuric acid mist, but not. when the mist contained nitric acid. The combination of high acidity and sulfate significantly decreased volume of aboveground tissues, while high acidity and nitrate increased volume. Root and needle dry weights were not affected. However, high acidity of mist was associated with increased leader shoot length. These results indicate, that there is a risk of foliar injury and changes in growth of red spruce with cloud water at a median acidity of pH 3.5 or below, especially when there are high concentrations of sulfate and low concentrations of nitrate. 相似文献
46.
Keitaro Sou 《生物化学与生物物理学报:生物膜》2008,1778(4):1035-1041
Anionic vesicles containing acidic phospholipids are known complement activators. To clarify which negative physicochemical electrostatic charges on vesicles and structural specificities of acidic lipids are critical to complement activation, the electrostatic properties and activity to complement of two anionic vesicles modified with a carboxylic acid derivative or a conventional acidic phospholipid were compared. Electrophoretic mobility measurements indicated that the negative zeta potential and the electrostatic interactivity of these two anionic vesicles were equal at pH 7.4. However, the infusion of vesicles containing acidic phospholipid induced significant complement activation, while vesicles containing the carboxylic acid derivative failed to activate complement. These results indicate that the negative charge on the surface of vesicles is not critical for the activation complement, suggesting that complement activation is specific to the structure of acidic groups. This finding is likely to be important to the design of anionic biointerfaces and may support the promising medical applications of this anionic vesicle modified with a carboxylic acid derivative. 相似文献
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