Eukaryotic hosts

Kealey, J.T., Liu, L., Santi, D.V. et al. (1998) Production of a polyketide natural product in nonpolyketide-producing prokaryotic and eukaryotic hosts. Proceedings ofthe National Academy of Sciences ofthe United States of America, 95, 505—509. 

The biosphere includes ecological niches where microbes peacefully co-exist with their eukaryotic host in the human this includes the concept of the micro-biome [14], which is defined as the totality of microbial organisms that co-habit with human beings. On the other hand, microbial colonization of human mucosal surfaces or prosthetic devices, often results in the development of biofilms, with significant deleterious effects on human health [15]. These are some of the challenges in infectious diseases that reflect the need to maximally utilize genomic sequence information and related sciences to better control microbial disease in human populations, and to develop anti-microbial agents with a better therapeutic index. 

Perrakis, A. and Romier, C. (2008) Assembly of protein complexes by coexpression in prokaryotic and eukaryotic hosts an overview. Methods in Molecular Biology (Clifton, NJ), 426, 247-256. 

ImHNL is a nonglycosylated homodimer (84 kDa) which catalyzes the reversible cleavage of aliphatic (R)-cyanohydrins [34]. This HNL does not require complex protein modification after protein biosynthesis. Thus, expression in prokaryotic Escherichia coli) and eukaryotic hosts Pichia pastoris) is possible [35-37]. However, initial trials to express IwHNL in E. coli were hampered by formation of inclusion bodies [36]. 

Genes can similarly be cloned and expressed in eukaryotic cells, with various species of yeast as the usual hosts. A eukaryotic host can sometimes promote post-translational modifications (changes in protein structure made after synthesis on the ribosomes) that might be required for the function of a cloned eukaryotic protein. 

Effective cloning systems are available for a variety of bacterial hosts, including Bacillus subtilis, Streptomyces spp., and Agrobacter tumefaciens. Cloning systems have also been developed for eukaryotic hosts such as the yeast Saccharomyces cerevisiae, mammalian cells in tissue culture, and plant cells. 

Most cloning has been done in E. coli. Yeast is the most used eukaryotic host. Cloning is also possible in a number of plant and animal cells. 

There exist a variety of vectors for cloning into eukaryotic systems, ranging from yeast (Saccharomyces as well as Pichia) through insect cells (Baculovims) and plants (Ti plasmid from Agrobacterium tumefaciens) to mammalian cells (transfected by viral or mammalian vectors). As expression in eukaryotic hosts is less efficient than bacterial expression in terms of yield and time and more complicated in terms of vector structure and culture conditions, such eukaryotic expression systems are only used for genes whose proteins require posttranslational modification which is not possible in bacteria. Yeast is the preferred option as a relatively easily culturable single-cell system but posttranslational modification capabilities is limited. The additional complexity can be circumvented in part by exploiting the ability of eukaryotic vectors to act as shuttle vectors, which can be shuttled between two evolutionarily different hosts. Thus, eukaryotic vectors can be replicated and analyzed in bacteria and transfected into eukaryotic cells for expression of the recombinant product. 

J Kealey, L Liu, DV Santi, M Betlach, PJ Barr. Production of a polyketide natural product in non-polyketide producing prokaryotic and eukaryotic hosts. Proc Natl Acad Sci (USA) 95 505-509, 1998. 

In contrast, the immediate ancestor of the organelle lost the ability to escape from pro-eukaryotic host, with its proliferation having been forced to keep pace with host cell division. The establishment of highly precise and... 

Even though the yields obtained in yeast are not yet comparable with those obtained with LAB, S. cerevisiae has great potential for the development of a cost-competitive process, leading to the conclusion that this eukaryotic host can represent an alternative production platform to LAB. The production of lactic acid from biomass with LAB has already been the object of investigation [153] nevertheless, the advances obtained with S. cerevisiae in using raw biomass as substrate represent important drivers for exploiting this yeast for chemicals production. 

The temi symbioses was first defined loosely by De Bary (1879) as two or more difFerendy named organisms bving together. Although symbiotic interactions are ubiquitous in nature, few of the marine planktonic systems have been well characterized, and comparatively less is known of the functional role of the symbiont for the host and vice versa. Many of the planktonic symbioses are between eukaryotic hosts and cyanobacterial symbionts, or cyanobionts. Cyanobacteria are photosynthetic, and many are capable of nitrogen (N2) fixation, thus often it is presumed... 

The final product must be free of adventitious agents that primarily include bacterial or viral pathogens and other biologic contaminates contributed during cell culture, such as DNA from prokaryotic or eukaryotic host cells and endotoxin. Purity testing for these factors must be performed throughout the production procedure and meet defined criteria before administration into humans. 

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