Comparison With Other Expression Profiling Technologies

The number of methods employed for gene expression analyses is numerous; however, there are now only a few DD routinely used approaches such as PCR-based, subtractive hybridization (SH), serial analysis of gene expression (SAGE), and microarrays. Additionally, there are variations on the theme that modify or combine features of these basic approaches.

A bottleneck in all variants of DD has been the confirmation of differential expression. Isolation and identification of clones, Northern blots, or RT-PCR analyses are time- and labor-intensive techniques. Therefore several attempts have been made to combine DD with microarrays to facilitate parallel identification of frequently expressed tags simultaneously in many biological systems.[17,18] Furthermore, probes generated by DD from archived experiments can now be reamplified and used as sensitive probes for cDNA microarray studies, revealing more information than was yielded when originally resolved as fingerprints on PAG.[19] The use of fluorescent probes[20] combined with robotics for liquid dispensing and tube handling/rotation, digital analysis, and specialized computer programs for data acquisition, analysis, and storage increases method throughput and facilitates data interpretation.[1,7]

Another strategy combined DD with SH, rationalizing that removing the most commonly expressed mRNA and then displaying the remaining mRNAs might improve displaying.[21]

Table 1 illustrates the advantages and disadvantages of major approaches to gene expression studies. It can be seen that no one method is superior to any other in all parameters surveyed. Ultimately, the correct identification of the gene and its transcript in the hand of the

Table 1 Comparison among major approaches to genome expression profiling

Parameter

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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