In the field of
genomics, GeneCalling is an open-platform
mRNA transcriptional profiling technique.[1] The GeneCalling protocol measures levels of
cDNA, which are correlated with
gene expression levels of specific
transcripts. Differences between gene expression in healthy tissues and disease or drug responsive tissues are examined and compared in this technology.[2] The technique has been applied to the study of human tissues[3] and plant tissues.[4]
Method
In the GeneCalling protocol, mRNAs are first isolated from a given sample and processed into fragments for analysis. This usually involves the synthesis and subdivision of double-stranded
cDNAs from
polyA RNA. Distinct sets of
restriction enzymes can then be used to digest sets of the divided cDNAs and resulting fragments ligated to labelled adapters to be amplified by
PCR. PCR products are then purified and subjected to gel
electrophoresis on a mounted platform employing stationary laser excitation and a multi-colour
charge-coupled device imaging system.[5] A fluorescent label at the 5' end of one of the PCR primers allows for visualization of the PCR fragments, and the cDNAs are subjected to several isolated and identical restriction digests to generate a merged profile based on peak height and variance.[6] The merged digestion profiles from the cDNA preparations are then compared to locate differentially expressed fragments (such as between normal tissue and diseased or drug responsive tissue); these profiles are compared by means of various internet-ready databases such as GeneScape.[7]
^Green, Cynthia D.; Simons, Jan Fredrik; Taillon, Bruce E.; Lewin, David A. (April 2001). "Open systems: panoramic views of gene expression". Journal of Immunological Methods. 250 (1–2): 67–79.
doi:
10.1016/S0022-1759(01)00306-4.
PMID11251222.
^Gene Expression Analysis by Transcript Profiling Coupled to a Gene Database Query. Nature Biotechnology17, 798-803: 1999
^Expression Profiling of the Maize Flavonoid Pathway Genes Controlled by Estradiol-Inducible Transcription Factors CRC and P. The Plant Cell12, 65-79: 2000