High quality labeling reagents are required to generate highly fluorescent probes. CyDye fluorescent dyes combined with the new CyScribe™ Microarray Labeling Kits provide the solution for high sensitivity dual-color differential gene expression analysis. CyScribe Post-Labeling Kit The CyScribe Post-Labeling Kit has been specifically developed for the generation of Cy 3- and Cy5-labeled first-strand cDNA probes by the 'post-labeling' (amino allyl) method. It gives the most even incorporation of both dyes, the brightest results and the highest yield of probe and is ideal for customers interested in using the post- labeling technique. Complete reagents and protocols will help generate excellent results quickly in what can be a complicated procedure. CyScribe First-Strand cDNA Labeling Kit The CyScribe First-Strand cDNA Labeling Kit has been specifically developed at Amersham Laboratories for the generation of Cy3 and Cy5 labeled first-strand cDNA probes to be used in two-colour microarray hybridization's. The CyScribe First Strand cDNA Labeling Kit will enable you to get the best probe labeling from the CyDye™ deoxynucleotides utilising a modified reverse transcriptase- CyScript™ which gives more even dye incorporation and the brightest signals compared to other modified reverse transcriptase enzymes. The CyScribe First Strand cDNA Labeling kit produces probes which give hybridization signal intensities almost twice as bright as those generated by leading reverse transcriptase enzymes such as SuperScript™ II using equal amount of CyDye and achieves more even incorporation of Cy3 and Cy5 labeled deoxynucleotides.

About CyDye Fluors CyDye™ fluorescent dyes, from GE Healthcare, have gained wide acceptance as the dyes of choice for microarray detection. These patented dyes are now routinely used in microarrays and are cited in many publications. ..

Choosing between the CyScribe First-Strand cDNA Labeling Kit and the CyScribe Post-Labeling Kit

The two CyScribe Microarray Labeling Kits have been designed to be used with dual-color microarray analysis, in which differential expression of genes is being identified and quantified. Together, these kits offer a choice of the two most popular methods for making first-strand cDNA probes for microarray hybridization—direct nucleotide incorporation and post labelling (amino allyl incorporation).

The CyScribe kits have been optimized to give excellent results in microarray hybridization by generating bright and evenly labeled probes. Both CyScribe kits include optimized reagents and protocols including the appropriate form of CyDye for maximum confidence and convenience. Although the post-labeling method is more labour intensive, it yields a higher amount of cDNA from a given amount of starting mRNA than direct incorporation.

The post labeling technique is growing in popularity because:

• The yield of cDNA is higher with the post-labeling method than with direct incorporation.
  
• Indirect incorporation of the reactive dyes of Cy3 and Cy5 into probe is greater and more even than CyDye labeled nucleotide incorporation.
  
• The post-labeling method is less prone to incorporating artefacts caused by the size of CyDye-nucleotides (e.g. chain termination, proximity quenching, sequence specific bias).
  
• Post-labeling produces longer cDNAs, which is beneficial when array targets have been derived from the 5’-ends of cDNAs.