Transgene expression

Screen-printed gold electrodes were, firstly, modified with a mixed monolayer of a 25-mer thiol-tethered DNA probe and a spacer thiol, 6-mercapto-1 -hexanol (MCH). The DNA probe sequence was internal to the sequence of the 35S promoter, which sequence is inserted in the genome of GMOs regulating tire transgene expression. 

DOWN R E, FORD L, BEDFORD S J, GATEHOUSE L N, NEWELL C, GATHOUSE J A, GATEHOUSE A M (2001) Influence of plant development and environment on transgene expression in potato and consequences for insect resistance. Transgenic Res. 10(3) 223-260. 

Success with transgenic expression of Pds or Zds or both has not been reported. Also not known is twhether CRTISO and Z-ISO, the companion isomerases to the desaturations, will influence accumulation of intermediates or products. 

Broxmeyer HE, Cooper S, Kohli L, et al. Transgenic expression of stromal cell-derived factor-l/CXC chemokine ligand 12 enhances myeloid progenitor cell sur-vival/antiapoptosis in vitro in response to growth factor withdrawal and enhances myelopoiesis in vivo. J Immunol 2003 170(1) 421 429. 

Yang TY, Chen SC, Leach MW, et al. Transgenic expression of the chemokine receptor encoded by human herpesvirus 8 induces an angioproliferative disease resembling Kaposi s sarcoma. J Exp Med 2000 191 (3) 445 154. 

Fig. 1. Modification of plant metabolic pathways for the synthesis of poly(3HB) and poly(3HB-co-3HV). The pathways created or enhanced by the expression of transgenes are highlighted in bold, while endogenous plant pathways are in plain letters. The various transgenes expressed in plants are indicated in italics. The ilvA gene encodes a threonine deaminase from E. coli. The phaARe, phaBRe, and phaCRe genes encode a 3-ketothiolase, an aceto-acetyl-CoA reductase, and a PHA synthase from R. eutropha, respectively. The btkBRe gene encodes a second 3-ketothiolase isolated from R. eutropha which shows high affinity for both propionyl-CoA and acetyl-CoA [40]. PDC refers to the endogenous plant pyruvate dehydrogenase complex...

Meyer P (1998) Stabilities and instabilities in transgene expression. In Lindsey K (ed) Transgenic plant research. Harwood Academic Publishers, Amsterdam, p 263... 

Fisher KD, Ulbrich K, Subr V, Ward CM, Mautner V, Blakey D, Seymour LW (2000) A versatile system for receptor-mediated gene delivery permits increased entry of DNA into target cells, enhanced delivery to the nucleus and elevated rates of transgene expression. Gene Ther 7 1337-1343... 

Carlisle RC, Bettinger T, Ogris M, Hale S, Mautner V, Seymour LW (2001) Adenovirus hexon protein enhances nuclear delivery and increases transgene expression of polyethy-lenimine/plasmid DNA vectors. Mol Ther 4 473 183... 

Transcriptional inhibitors could be used simultaneously. Rifampicin blocks chloroplast and mitocondrian RNA synthesis [23, 24], while tagetitoxin is a very specific inhibitor of chloroplast RNA polymerase [25]. Treatment with these antibiotics does not inhibit Rubisco SSU synthesis since the promoter is part of the nuclear genome, while the cytosolic ribosomes are not affected by streptomycin. Therefore SSU promoters can be used to drive transgene expression and facilitate the accumulation of recombinant proteins. Expressed proteins are targeted to a suitable cellular compartment, such as the cytoplasm, apoplastic space or chloroplast, depending on the nature of the protein. 

Fig. 3.6 Human serum albumin (HSA) was produced during the sprouting of transgenic rape-seeds. A light-inducible Rubisco promoter was used to control transgene expression. The highest yield was obtained with light induction after three days of continuous darkness. Sprouting was carried out in an airlift fermentor at room temperature. The sprouting medium was water.

Further improvements to vims expression systems include trans-complementation of some of the virus functions from transgenic host plants (P12 plants for AlMV). By integrating parts of the viral vector into the plant chromosome, this system has the potential for multiple technical solutions that could overcome limitations of classical viral vectors [33]. Viral vectors can be used as molecular switches for tightly controlled, high-level transgene expression (Hull et al. unpublished data). 

In order to make molecular farming commercially profitable, recombinant proteins must be produced at a sufficiently high yield and in an active form. It has become clear that, for high-level protein accumulation, the stability of transgene expression can be as important as the expression level itself. The quantity of protein is determined by the rate of protein synthesis, assembly as well as proteolytic degradation [83]. 

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