Anaerobically controlled expression system derived from the arcDABC operon of Pseudomonas aeruginosa: application to lipase production.

The anaerobically inducible arcDABC operon encodes the enzymes of the arginine deiminase pathway in Pseudomonas aeruginosa. Upon induction, the arcAB mRNAs and proteins reach high intracellular levels, because of a strong anaerobically controlled promoter and mRNA processing in arcD, leading to stable downstream transcripts. We explored the usefulness of this system for the construction of expression vectors. The lacZ gene of Escherichia coli was expressed to the highest levels when fused close to the arc promoter. Insertion of lacZ further downstream into arcA or arcB did not stabilize the intrinsically unstable lacZ mRNA. On the contrary, lacZ mRNA appeared to be a vulnerable endonuclease target destabilizing arcAB mRNAs in the 5'-to-3' direction in P. aeruginosa. The native arc promoter was modified for optional expression in the -10 sequence and in the -40 region, which is a binding site for the anaerobic regulator ANR. In P. aeruginosa grown either anaerobically or with oxygen limitation in unshaken cultures, this promoter was stronger than the induced tac promoter. The P. aeruginosa lipAH genes, which encode extracellular lipase and lipase foldase, respectively, were fused directly to the modified arc promoter in an IncQ vector plasmid. Semianaerobic static cultures of P. aeruginosa PAO1 carrying this recombinant plasmid overproduced extracellular lipase 30-fold during stationary phase compared with the production by strain PAO1 without the plasmid. Severe oxygen limitation, in contrast, resulted in poor lipase productivity despite effective induction of the ANR-dependent promoter, suggesting that secretion of active lipase is blocked by the absence of oxygen. In conclusion, the modified arc promoter is useful for driving the expression of cloned genes in P. aeruginosa during oxygen-limited growth and stationary phase.

Contribution of livestock to food production in developing countries

Selostus: Kotieläintuotannon osuus kehitysmaiden ruoantuotannosta

Application of metabolic engineering to the production of scopolamine

Scopolamine is an alkaloid widely used in medicine for its anticholinergic activity. The aim of this review is to show that metabolic engineering techniques constitute a suitable tool to improve the production of tropane alkaloids, focusing in particular on scopolamine. We present an overview of results obtained by various research groups, including our own, who have studied the overexpression of genes involved in the biosynthesis of scopolamine in different plant species that produce tropane alkaloids. Experiments carried out to improve production in hairy root cultures will also be described, as well as those attempting to biotransform hyoscyamine into scopolamine in roots and transgenic tobacco cells.

Fourth Report of the Iowa Library Commission Made to the Governor of Iowa, 1906-1908

1906-1908 Iowa Library Commission Report made to the Governor of Iowa.

Fifth Report of the Iowa Library Commission Made to the Governor of Iowa for the Biennial Period July 1, 1908 to June 30, 1910

1908-1910 Iowa Library Commission Report made to the Governor of Iowa.

Sixth Report of the Iowa Library Commission Made to the Governor of Iowa 1910-1912

1910-1912 Iowa Library Commission Report made to the Governor of Iowa.

Seventh Report of the Iowa Library Commission Made to the Governor of Iowa, 1912-1914

1912-1914 Iowa Library Commission Report made to the Governor of Iowa.

1920 Report of the Iowa Library Commission Made to the Governor of Iowa for the Biennial Period July 1, 1918 to June 30, 1920

1918-1920 Iowa Library Commission Report made to the Governor of Iowa.

Thirteenth Report of the Iowa Library Commission Made to the Governor of Iowa for the Biennial Period July 1, 1924 to June 30, 1926

1924-1926 Iowa Library Commission Report made to the Governor of Iowa.

Fourteenth Report of the Iowa Library Commission Made to the Governor of Iowa for the Biennial Period July 1, 2926 to June 30, 1928

1926-1928 Iowa Library Commission Report made to the Governor of Iowa.

Fifteenth Report of the Iowa Library Commission Made to the Governor of Iowa for the Biennial Period July 1, 1928 to June 30, 1930 1928-1930

1928-1930 Iowa Library Commission Report made to the Governor of Iowa.

Sixteenth Report of the Iowa Library Commission Made to the Governor of Iowa for the Biennial Period July 1, 1930 to June 30, 1932

1930-1932 Iowa Library Commission Report made to the Governor of Iowa.

Seventeenth Report of the Iowa Library Commission Made to the Governor of Iowa for the Biennial Period July 1, 1932 to June 30, 1934

1932-1934 Iowa Library Commission Report made to the Governor of Iowa.

Eighteenth Report of the Iowa Library Commission Made to the Governor of Iowa for the Biannual Period July 1,1934 to June 30, 1936

1934-1936 Iowa Library Commission Report made to the Governor of Iowa.

Nineteenth Report of the Iowa Library Commission Made to the Governor of Iowa for the Biennial Period July 1,1936 to June 30, 1938

1936-1938 Iowa Library Commission Report made to the Governor of Iowa.