Gene expression system

Gene Expression Systems. One of the potentials of genetic engineering of microbes is production of large amounts of recombinant proteias (12,13). This is not a trivial task. Each proteia is unique and the stabiUty of the proteia varies depending on the host. Thus it is not feasible to have a single omnipotent microbial host for the production of all recombinant proteias. Rather, several microbial hosts have to be studied. Expression vectors have to be tailored to the microbe of choice. 

Mierau, I. and Kleerebezem, M. (2005) 10 years of the nisin-controlled gene expression system (NICE) in Lactococcus lactis. Applied Microbiology and Biotechnology, 68 (6), 705—717. 

In reverse chemical genetics, it is crucial to synthesize proteins of interest using appropriate foreign gene expression systems and cDNA resources. Since cell-free protein synthesis systems have the potential to synthesize any desired proteins, including both native proteins and those that are toxic to cells (1), with high throughput, they can be powerful tools for this objective. We developed a cell-free protein synthesis system from Spodop-tera fm iperda 21 (S 21) insect cells, which are widely used as the host for baculovirus expression systems, and commercialized it as the Transdirect insect cell. 

Gene-expression system within cell-sized lipid vesicles. 

Encapsulation of a gene-expression system expression of GEP with very high efficiency. 

ITABLE 4.3. Comparison of the features and requirements of gene expression systems... 

TABLE 4.4. Some methods used for screening and verifying molecular clones form the gene expression system ... 

Gene Expression Systems, Academic Press, San Diego, California... 

Heat inducible gene expression systems can be activated by a variety of technologies, all via the production of hyperthermia. Technologies used in clinical applications of hyperthermia include simple approaches, such as water baths, or more sophisticated methods, such as microwave or radiofrequency radiations and ultrasound (Gemer and Cetas, 1993). The magnitude of heat shock promoter activity induction is dependent on both the time of exposure to hyperthermia and the hyperthermic temperature (Gemer et al., 2000). HSP promoter activity is activated by temperature in a species-specific manner. In flies, HSP promoter activity is activated by temperatures over 30 °C (Lindquist, 1986). In human cells, temperatures of 40 °C and above are required to activate HSP promoters (Gemer et al., 2000). 

Recent efforts have focused on using these highly regulated gene expression systems in gene therapies for disease. Applications include modification of stem cells (Moutsatsos et al., 2001), treatment of retinal diseases (Dejneka et al., 2001) and immunotherapy for cancer (Nakagawa et al., 2001). 

Gossen, M., and Bujard, H. (1993) Anhydrotetracycline, a novel effector for tetracycline controlled gene expression systems in eukaryotic cells. Nucleic Acids Res., 21, 4411—4412. 

An additional screening test for TCDD-like (aryl hydrocarbon receptor, AhR, active) chemicals has been developed (Garrison et al. 1996) and is available commercially (Anonymous 1997). Dubbed the CALUX (for chemically activated luciferase gene expression) system, the assay is based on recombinant cell lines into which researchers have inserted a firefly luciferase gene. When exposed to dioxin-like compounds, the recombinant cells luminesce. The method is sensitive to ppt levels of 2,3,7,8-TCDD equivalents in blood, serum, and milk (Anonymous 1997). Samples testing positive can be subjected to more definitive and specific analytical testing. 

Claridge-Chang A., Wijnen H., Naef F., Boothroyd C., Rajewsky N. and Young M. W. (2001) Circadian regulation of gene expression systems in the Drosophila head. Neuron 32, 657-671. 

Teshigawara K, Katsura Y (1992), A simple and efficient mammalian gene expression system using an EBV-based vector transfected by electroporation in G2/M phase, Nucleic Acids Res. 20 2607-2611. 

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