Pyrosequencing the Manduca sexta larval midgut transcriptome: messages for digestion, detoxification and defence

Area of Science:

• * Insect molecular biology and genomics.
• * Comparative transcriptomics.
• * Biochemistry and physiology of insect midgut.

Background:

• * The tobacco hornworm (Manduca sexta) is a key model organism in insect physiology.
• * Limited genomic and transcriptomic data currently exist for M. sexta.
• * Expressed sequence tags (ESTs) are valuable for gene discovery and annotation.

Purpose of the Study:

• * To define the larval midgut transcriptome of Manduca sexta using advanced sequencing technologies.
• * To identify and classify genes involved in digestion, detoxification, and immunity.
• * To discover novel genes and gene families within the M. sexta midgut.

Main Methods:

• * Generation of over 387,000 midgut ESTs from M. sexta larvae.
• * Utilized a combination of Sanger and 454 pyrosequencing technologies.
• * Bioinformatic analysis for protein classification and gene identification.

Main Results:

• * Comprehensive catalog of M. sexta larval midgut transcripts, including full-length cDNA sequences for many genes.
• * Identification of 36 new cytochrome P450 genes, potentially involved in nicotine metabolism.
• * Discovery of new lepidopteran gene families and a high proportion of immunity-related genes (e.g., 39 serpin contigs).

Conclusions:

• * The study significantly expands the available transcriptomic data for Manduca sexta.
• * Highlights the critical role of the insect midgut in immune responses.
• * Provides foundational data for future M. sexta genome sequencing and annotation efforts.