Biological pathway databases – Reactome, SAGE, Microarray

SAGE (Serial Analysis of Gene Expression) and Microarray are important techniques in biological research for analyzing gene expression patterns. SAGE involves extracting short sequence tags from mRNA, which are then concatenated and sequenced to quantify gene expression. It provides a digital and quantitative approach to identifying expressed genes without prior knowledge of the sequences. Microarray technology uses a solid surface with immobilized DNA probes that hybridize with fluorescently labeled cDNA samples, allowing simultaneous measurement of thousands of gene transcripts. Both methods are used to compare gene expression across different tissues, developmental stages, or experimental conditions. They help identify differentially expressed genes involved in various biological processes and diseases. In cancer research, these methods are used to classify tumor types and predict treatment responses. In developmental biology, they are applied to study temporal changes in gene expression. They also assist in understanding the effects of environmental stressors or drugs on cellular functions. Gene expression data from these techniques support the construction of gene regulatory networks and pathway analysis. These methods have become essential for large-scale transcriptomic studies and contribute significantly to biomarker discovery and therapeutic target identification.