Color Doppler twinkling artifact related to chronic pancreatitis with parenchymal calcification.

Color Doppler twinkling artifact is known as a rapidly changing mixture of red and blue behind certain strongly reflecting structures. This artifact has been described behind calcifications in various tissues. We describe a case of twinkling artifact related to chronic pancreatitis with parenchymal calcification.

Regulation of CO on heterocyst differentiation and nitrate uptake in the cyanobacterium Anabaena sp. PCC 7120.

AIMS: The aim of the present investigation was to study the effects of different inorganic carbon and nitrogen sources on nitrate uptake and heterocyst differentiation in the culture of cyanobacterium Anabaena sp. PCC 7120. METHODS AND RESULTS: Anabaena was cultivated in media BG11 containing combined nitrogen and supplementary NaHCO3 or CO2. Cell growth, heterocyst differentiation, nitrate reductase (NR, EC 1.7.7.2), glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) and NO uptake were analysed. The cells cultivated in BG11(0) medium with aeration were taken as reference. Experimental results showed that the differentiation frequency of heterocysts when the cells were cultivated with elevated CO2 was higher than that of the cells grown with air or bicarbonate. Heterocysts appeared unexpectedly when CO2 was introduced into the medium containing nitrate. However, no heterocysts emerged when CO2 was added to medium containing NH or urea, or when NaHCO3 was supplied to the medium with nitrate. Both nitrate uptake rate and nitrate reduction enzyme activity were depressed by the supplement of CO2 to the culture. The activity of G6PDH was enhanced with the increase in heterocyst differentiation frequency. CONCLUSION: CO2 might compete with NO for energy and electrons in the uptake process and CO2 appears favoured. This led to a high intracellular C/N ratio and a relative N limitation. So the process of heterocyst differentiation was activated to supplement nitrogen uptake. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provided an attractive possibility to form more heterocysts by rapid growth of Anabaena cells cultivated in the medium containing nitrate in order to increase nitrogen fixation and hydrogen production.

[Photoautotrophic cultivation of Synechococcus sp. PCC7002 in photobioreactor].

The Photoautotrophic cultivation of Synechococcus sp. PCC 7002 in a 15 L-airlift photobioreactor was carried out. The changes of light intensity with cell density and optical length in the cultivation system were investigated. Based on experimental results, the light attenuation could be described by I = I0exp [-(-0.0239 + 0.0777 OD750).L]. The effects of the variations of light intensity, CO2 concentration in gas inlet and culture temperature on the growth of cells during the cultivation process have also been studied. The optimized condition was determined and a high dry cell density of 3.4 g/L was obtained. The volumetric productivity reached 0.57 g/(L.d) under the optimized condition.