Chapter 110 - Genomics

Abstract

This chapter discusses insect's genomics. Any study of an insect's genome fundamentally requires that the sequence of nucleotide bases that make up the chromosomes and mitochondria be determined. Genome-sequencing projects typically concentrate on the euchromatic portion of the genome, which contain most of the genes, and ignore the highly repetitive heterochromatic portions. The modern technique of genome sequencing relies on fragmenting the genome into small random sections, 300–1000 nucleotide long, obtaining the sequence of these sections, and finally assembling these sections into larger fragments. The two main advantages of this method are speed and relatively low cost compared to earlier methods that concentrated on sequencing specific regions on the chromosome. The aim of functional genomics is to describe and understand the pattern of gene expression. It has been established that gene expression is influenced by the expression of many genes. Before the entire set of Drosophila genes became known, study of gene expression relied heavily on the generation of fruit fly mutants for specific genes and on deducting the function of these genes based on observation of physical or behavioral differences compared to wild-type flies. While generating mutant Drosophila flies is far easier than for any other insect, it remains a time consuming and labor intensive task. The sequencing of the Drosophila genome revolutionizes the study of insect gene expression by making microarray assays possible for the entire set of Drosophila genes.