Differential screening

Kuang TO et al. Differential screening and suppression subtractive hybridisation identified genes differentially expressed in an estrogen receptor-positive breast carcinoma cell line. Nucleic Acids Res 1998 26 1116-1123. 

The final SAR gene family, SAR8.2, comprises several highly related cDNAs which were isolated by differential screening of a tobacco cDNA library constructed from RNA of induced resistant leaves (D. Alexander et al., unpublished data). The cDNA encodes a basically-charged protein of about 50 residues, which has not been isolated and whose function is unknown. 

Kajiwara K., Nagawawa H., Shimizu-Nishikawa S., Ookuri T., Kimura M., and Sugaya E. (1996). Molecular characterization of seizure-related genes isolated by differential screening. Biochem. Biophys. Res. Commun. 219 795-799. 

Chong, B. E. Hamler, R. L. Lubman, D. M. Ethier, S. P. Rosenspire, A. J. Miller, F. R. 2001. Differential screening and mass mapping of profiles from premalignant and cancer cell lines using nonporous reversed phase HPLC with on-line detection by ESI-TOFMS. Anal. Chem., 73, 1219-1227. 

Peter Schultz s team used a combinatorial library of purines to identify agents that could disassemble multinucleated myotubes into mononucleated fragments (a morphological differentiation screen). A new microtubule-binding molecule, mysoseverin, was identified in this way [19]. 

Two enz)mies of pyrrolidine alkaloid formation responsible for the conversion of putrescine to the N-methylpyrrolinium ion have been investigated in some detail. PMT, partially purified from cultures of Hyoscyamus niger and fully characterized from Datura stramonium, has been cloned by differential screening of complementary deoxyribonucleic acid (cDNA) libraries from high- and low-nicotine-yielding N. tabacum plants (Hibi et ah, 1994). The enzyme shows considerable sequence homology to spermidine synthase but is distinct from this enz)mie as it only shows PMT activity when expressed in Escherichia coli. MPO has been isolated in pure form from N. tabacum transformed root cultures (McLauchlan et ah, 1993). It is quite widely spread in... 

Even though the concept probably could trace back to the early differential screening in which desired cDNA clones could be enriched by subtracting against a separate source of undesired clones, the principle remains the same... 

Differential screen analyses (a) direct plot from Table 28.2 (ft) plot adjusted for size range of increment. 

Using differential screening, Tanaka et al. [34] found cDNAs representing cytokinin-induced mRNAs in the tobacco thin layer system. One cDNA encodes S-adenosyl-L-homocysteine hydrolase (SAH hydrolase), which is involved in regulating intracellular transmethylation reactions. The promoter sequence of the gene was fused to the 3-glucuronidase (GUS) reporter gene and introduced in suspension-cultured cells, which rendered expression of GUS inducible by kinetin. 

Lehmann, H.E. and J. Csank 1957. Differential screening of phrenotropic agents in man Journal of Clinical Psychopath- 18 222-135. 

The amount of RNA loaded per dot is obviously dependent on the abundance of the transcript in the RNA population. For a cDNA clone identified by differential screening (and hence of high abundance in the mRNA pool) a loading of 5 ig total RNA per dot should be sufficient. For medium and low abundance transcripts it may be necessary to load more total RNA or isolate polyA RNA for efficient detection of transcript. 

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