Since newly created beings are often perceived as either wholly good or bad, the genetic alteration of living cells impacts directly on a symbolic meaning deeply imbedded in every culture. During the earlier years of gene expression research, te- nological applications were confined mainly to academic and industrial laboratories, and were perceived as highly beneficial since molecules that were previously unable to be separated or synthesized became accessible as therapeutic agents. Such were the success stories of hormones, antibodies, and vaccines produced in the bacterium Escherichia coli. Originally this bacterium gained fame among humans for being an unwanted host in the intestine, or worse yet, for being occasionally dangerous and pathogenic. H- ever, it was easily identified in contaminated waters during the 19th century, thus becoming a clear indicator of water pollution by human feces. Tamed, cultivated, and easily maintained in laboratories, its fast growth rate and metabolic capacity to adjust to changing environments fascinated the minds of scientists who studied and modeled such complex phenomena as growth, evolution, genetic exchange, infection, survival, adaptation, and further on—gene expression. Although at the lower end of the complexity scale, this microbe became a very successful model system and a key player in the fantastic revolution kindled by the birth of recombinant DNA technology.

Maximizing Gene Expression focuses on prokaryotic and eukaryotic gene expression. The book first discusses E. coli promoters. Topics include structure analysis, steps in transcription initiation, structure-function correlation, and regulation of transcription initiation. The text also highlights yeast promoters, including elements that select initiation sites, transcription regulation, regulatory proteins, and upstream promoter elements. The text also describes protein coding genes of higher eukaryotes; instability of messenger RNA in bacteria; and replication control of the ColE1-type plasmids. The text then describes translation initiation, including the translation of prokaryotes and eukaryotes. The book puts emphasis on the selective degradation of abnormal proteins in bacteria. Topics include proteins rapidly hydrolyzed in E. coli; intracellular aggregates of abnormal polypeptides; energy requirement and pathway for proteins; proteolytic enzymes in E. coli; and regulation of ion expression. The text also highlights the detection of proteins produced by recombinant DNA techniques and mechanism and practice. The book is a good source of information for readers wanting to study gene expression.

This detailed volume explores advances in vector design, DNA delivery, cell cultivation, host cell engineering, and bioprocess optimization within the study of recombinant protein expression in mammalian cells. The majority of the protocols employ either Chinese hamster ovary cells (CHO) or human embryonic kidney 293 cells (HEK293), the workhorses of the field, as the production host; however, the methods can be adapted to other mammalian hosts under the appropriate cell-specific conditions. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and convenient, Recombinant Protein Expression in Mammalian Cells: Methods and Protocols aims to aid researchers in building on our knowledge of protein structure and function and to speed the discovery of new therapeutic proteins.

With the advent of recombinant DNA technology, expressing heterologous proteins in microorganisms rapidly became the method of choice for their production at laboratory and industrial scale. Bacteria, yeasts and other hosts can be grown to high biomass levels efficiently and inexpensively. Obtaining high yields of recombinant proteins from this material was only feasible thanks to constant research on microbial genetics and physiology that led to novel strains, plasmids and cultivation strategies. Despite the spectacular expansion of the field, there is still much room for progress. Improving the levels of expression and the solubility of a recombinant protein can be quite challenging. Accumulation of the product in the cell can lead to stress responses which affect cell growth. Buildup of insoluble and biologically inactive aggregates (inclusion bodies) lowers the yield of production. This is particularly true for obtaining membrane proteins or high-molecular weight and multi-domain proteins. Also, obtaining eukaryotic proteins in a prokaryotic background (for example, plant or animal proteins in bacteria) results in a product that lack post-translational modifications, often required for functionality. Changing to a eukaryotic host (yeasts or filamentous fungi) may not be a proper solution since the pattern of sugar modifications is different than in higher eukaryotes. Still, many advances in the last couple of decades have provided to researchers a wide variety of strategies to maximize the production of their recombinant protein of choice. Everything starts with the careful selection of the host. Be it bacteria or yeast, a broad list of strains is available for overcoming codon use bias, incorrect disulfide bond formation, protein toxicity and lack of post-translational modifications. Also, a huge catalog of plasmids allows choosing for different fusion partners for improving solubility, protein secretion, chaperone co-expression, antibiotic resistance and promoter strength. Next, controlling culture conditions like temperature, inducer and media composition can bolster recombinant protein production. With this Research Topic, we aim to provide an encyclopedic account of the existing approaches to the expression of recombinant proteins in microorganisms, highlight recent discoveries and analyze the future prospects of this exciting and ever-growing field.

Recombinant gene expression is the fastest growing area in the study of molecular biology. By the time the Human Genome Project is completed (~2002), several thousand sequences will be known, but the purpose of the resultant expression products will remain a mystery. Gene discovery requires efficient expression systems for determining the structure and function of gene products. Gene Expression Systems covers a variety of promoters and host organisms that researchers can tailor to their specific needs.

This is an introduction to the methods and applications of polymerase chain reaction (PCR) technology, a technology developed by Erlich's group at Cetus and Cetus, and is expected to be used in all biology laboratories worldwide within the next few years.