Induction and Maintenance of Callus and Paclitaxel Production in Torreya grandis

To develop callus-derived tissue culture models for the production of secondary plant metabolites, conditions for callus induction from stems, needles and young buds of Torreya grandis were examined. The young buds were the best tissues for callus induction followed by stems and needles. While most needle and bud calluses turned brown and ceased growth by second subcultures, stem calluses exhibited rapid growth much longer. B5 medium supplemented with 2.0 mg/L naphthalene acetic acid, 0.5 mg/L kinetin, 20 g/L sucrose, and 8 g/L agar was the best medium for callus induction from stems when incubated at 25°C at 12 h light–dark cycle. These produced masses of friable calluses with a growth index of 4.7. However, callus subcultures maintained in darkness were generally of yellow-green color. There were some seasonal differences in callus induction with March being the best. The contents of paclitaxel in the calluses from needles, stems, and aril were 0.0212%, 0.0160%, and 0.0073%, respectively. However, the contents of baccatin III were 0.0034%, 0.0051%, and 0% in the calluses from needles, stems, and aril, respectively. In the suspension culture, B5 medium supplemented with 20 g/L sucrose on day 1 and 20 mg/L methyl jasmonate on day 7 showed improved cellular productivity resulting in the highest amount of paclitaxel (0.0257%) (2.842-fold higher than that of the untreated control) on day 14.

PRODUCCIÓN DE BIOMASA DE LA MICROALGA MARINA CHROOMONAS SP. , EN FUNCIÓN DEL PH, INTENSIDAD LUMINOSA Y SALINIDAD

We report the characterization of a marine microalga of the genus Chroomonas, isolated from a salt lagoon located to the north of Maracaibo, Zulia State, Venezuela. We evaluated the growth and the pigment production in discontinuous culture at different salinites (5, 10, 35, 50, 70 Y 100 ppm),Iight intensites (39,78,117 and 156 µmol quanta.m-2.s-1) and pH (5.0,5.5,6.0,7.0, 8.0 and 9.0). The highest cellular density, 117.99±2.62x106 cel.ml-1, was reached at 35ppm, 156 µmol quanta.m-2.s-1 of light intensity and a pH between 6.0 and 8.0. The cellular content of total chlorophyll and carotenoids increased with the salinity up to 100 ppm, with amounts of 246.55±61.8 and 69.79±18.19 fg.cel-1 respectively. The cellular productivity 4.31x109 cel.l-1d-1 was obteined when the microalga, was grown in semi-continuous culture, at a 2.0 I volume and at a daily renewal rate of 30 % (v/v). The total amount of chlorophyll and carotenoids 1.4 mg.l-1.d-1 and 0.48 mg.l-1.d-1 respectively. This results indicate that this planktonic microalga could be used as daily live food for larvae in aquaculture and for the production of microalgaI biomass and/or pigments.

Impairment of endothelial nitric oxide production by acute glucose overload

We examined the effects of acute glucose overload (pretreatment for 3 h with 23 mM d-glucose) on the cellular productivity of nitric oxide (NO) in bovine aortic endothelial cells (BAEC). We had previously reported (Kimura C, Oike M, and Ito Y. Circ Res, 82: 677–685, 1998) that glucose overload impairs Ca2+ mobilization due to an accumulation of superoxide anions (O2 −) in BAEC. In control cells, ATP induced an increase in NO production, assessed by diaminofluorescein 2 (DAF-2), an NO-sensitive fluorescent dye, mainly due to Ca2+ entry. In contrast, ATP-induced increase in DAF-2 fluorescence was impaired by glucose overload, which was restored by superoxide dismutase, but not by catalase or deferoxamine. Furthermore, pyrogallol, an O2 − donor, also attenuated ATP-induced increase in DAF-2 fluorescence. In contrast, a nonspecific intracellular Ca2+ concentration increase induced by the Ca2+ ionophore A-23187, which depletes the intracellular store sites, elevated DAF-2 fluorescence in both control and highd-glucose-treated cells in Ca2+-free solution. These results indicate that glucose overload impairs NO production by the O2 −-mediated attenuation of Ca2+entry.

Production of concentratedStreptococcus salivariussubsp.thermophilusby coupling continuous fermentation and ultrafiltration

SummaryContinuous production of concentrated cells ofStreptococcus salivariussubsp.thermophiluswas achieved in a continuous stirred tank reactor coupled with an ultrafiltration module. A cellular productivity nine times higher than that obtained by conventional methods was observed. The viability of the cells produced was as satisfactory as that obtained by classical culture, but an increase in latency time and a slight decrease in acidification rate during downstream tests in milk were observed. Specific lactic acid productivity decreased as biomass increased. This process produced concentrated starters and lactic acid which could be purified by a downstream processing such as electrodialysis.