Screening Platforms

Lipophilic metabolites tend to accumulate within the production host. If in addition the metabolite is colored or fluorescing, a carotenoid for instance, flow cytometry-based cell sorting protocols are suited to isolate individuals with improved production traits out of a mutagenized population, even if they are present at very low frequency. Value compounds typically produced with B. subtilis production hosts, such as water-soluble vitamins, purine nucleosides, ribose, or proteins, are secreted and accumulate in the culture medium. Screening of improved production strains for such metabolites requires clonal cultivation of the members of the mutagenized population in compartmentalized reactors and individual analyses of the culture supernatants in each of the reactors. 

Analysis of the droplet interior for quantitative or qualitative product analysis typically requires a fluorescence signal which can be recorded at the kilohertz range with commercially available flow cytometers [227] or customized microchips [228]. Naturally, most industrially relevant products are not fluorescent, which requires that an appropriate chemical or biological assays is integrated into the microdroplets too. Yet, once all components are in place, libraries containing 10 entries can be readily screened. 

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Von, L.A., Kumpf, R., Menzel, S., Reulle, D., Griebel, R., Valler, M.J., and Buttner, F.H., Miniaturization and validation of a high-throughput serine kinase assay using the alpha screen platform, /. Biomol. Screen., 9, 719, 2004. 

Qian J, Voorbach MJ, Huth JR, Coen ML, Zhang H, Ng S-C, Comess KM, Petros AM, Rosenberg SH, Warrior U, Bums DJ Discovery of novel inhibitors of Bcl-xL using multiple high-throughput screening platforms. Anal Biochem 2004, 328, 131-138. 

The siRNA screening is performed in duplicate in 96-well plates as shown in Fig. 1. The first replica is used for viability readout and the second for phenotypic readout where we look at spindle structure by using a high content screening platform. The small molecule library screening is also performed in duplicate with the first replica used for viability readout. In contrast to the siRNA... 

Black wall, clear bottom 96-well tissue culture plates to be read by a suitable high content screening platform. 

The implementation and adaptation of the different technologies developed for the study of NSC proliferation and differentiation might be instrumental for the establishment of screening platforms to identify small molecules with neurogenic and/or antitumor activity. 

Compound Screen Platforms Workstations and Fully Automated Robotic Systems.189... 

COMPOUND SCREEN PLATFORMS WORKSTATIONS AND FULLY AUTOMATED ROBOTIC SYSTEMS... 

Based on the numbers of daily compound screens, a screening laboratory may choose a workstation or fully automated screen system (Figure 11.3) (Hamilton, 2002). A workstation-based screening platform can be set up quickly and requires less capital funding. The screening throughput with a workstation platform is relatively small—usually 20 to 100 plates per day in 8 hr. A fully automated robotic screen system requires 6 to 12 months for implementation and a minimum investment of... 

Subsequently, a 1 pL per well substrate solution is dispensed to the assay plates in another Multidrop-Combi equipped with plate stackers. After 30-min incubation at room temperature, the operator manually moves the assay plates to a plate detector with stackers and executes the measurement of assay plates in a specific detection mode (fluorescence intensity in this case). The data file from the plate reader and the tracer file will be copied to a computer for data analysis after the experiment. This screening platform is very useful for laboratories that screen small compound collections, assay validation with the LOPAC collection, and follow-up screens for hit confirmation and lead optimization. 

More recently, a plethora of small companies and biotechnology ventures were established to handle biologies as well as natural products, many of them with proprietary screening platforms designed to make natural product screening more straightforward and quicker. Some developed proprietary collections of particular natural product sources for extract production such as organisms isolated from extreme environments, leaf litter, caves, unique water environments, and endophytes from marine and terrestrial plants. 

Design factors Monolithic screening Platform screening Chemical biology... 

Profile Cellomics Inc., formerly BioDx Inc., is a privately held corporation founded in October 1996. Cellomics mission is to improve the efficiency of the drug discovery process by delivering a cell-based screening platform that automates target validation and lead optimization using fluorescence-based assays. 

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