Ethanol synthesis by genetic engineering in cyanobacteria.

Cyanobacteria are autotrophic prokaryotes which carry out oxygenic photosynthesis and accumulate glycogen as the major form of stored carbon. In this research, we introduced new genes into a cyanobacterium in order to create a novel pathway for fixed carbon utilization which results in the synthesis of ethanol. The coding sequences of pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adh) from the bacterium Zymomonas mobilis were cloned into the shuttle vector pCB4 and then used to transform the cyanobacterium Synechococcus sp. strain PCC 7942. Under control of the promoter from the rbcLS operon encoding the cyanobacterial ribulose-1, 5-bisphosphate carboxylase/oxygenase, the pdc and adh genes were expressed at high levels, as demonstrated by Western blotting and enzyme activity analyses. The transformed cyanobacterium synthesized ethanol, which diffused from the cells into the culture medium. As cyanobacteria have simple growth requirements and use light, CO2, and inorganic elements efficiently, production of ethanol by cyanobacteria is a potential system for bioconversion of solar energy and CO2 into a valuable resource.

Monitoring human chorionic gonadotrophin level: evaluation of urine as an alternative specimen type.

Although urine has been used widely for the qualitative detection of human chorionic gonadotrophin (hCG), serum is chosen conventionally for the serial quantification of the hormone to monitor trophoblastic activity. In response to requests from both clinicians and patients regarding the use of urine as an alternative specimen type, we designed this comparative study to evaluate the possibility, taking into account both laboratory technique and the distribution of hCG within different body fluids. Using the Access Chemiluminescent Immunoassay System, total beta-hCG was measured in serum and urine (n = 30) collected from patients hospitalised for first-trimester abnormal pregnancy. Results obtained with normalised urine (corrected with urinary creatinine) and serum total beta-hCG correlated well (r = 0.98, P < 0.001), and we concluded that urine could be used as an alternative specimen type for the serial quantitation of hCG to monitor trophoblastic activity. However, the assay used must detect the common beta 2 epitope.

Nitrate-reductase expression is under the control of a circadian rhythm and is light inducible in Nicotiana tabacum leaves.

Over a 24-h light-dark cycle, the level of mRNA coding for nitrate reductase (NR; EC 1.6.6.1) in the leaves of nitrate-fed Nicotiana tabacum L. plants increased throughout the night and then decreased until it was undetectable during the day. The amount of NR protein and NR activity were two-fold higher during the day than at night. When plants were transferred to continuous light conditions for 32 h, similar variations in NR gene expression, as judged by the above three parameters, still took place in leaf tissues. On the other hand, when plants were transferred to continuous dark conditions for 32 h, the NR-mRNA level continued to display the rhythmic fluctuations, while the amount of NR protein and NR activity decreased constantly, becoming very low, and showed no rhythmic variations. After 56 h of continuous darkness, the levels of NR mRNA, protein and activity in leaves all became negligible, and light reinduced them rapidly. These results indicate the circadian rhythmicity and light dependence of NR expression.