Functional analysis of the two chitin synthase genes, TcCHS1 and TcCHS2 , in the red flour beetle, Tribolium castaneum , revealed unique and complementary roles for each gene. TcCHS1‐ specific RNA interference (RNAi) disrupted all three types of moult (larval–larval, larval–pupal and pupal–adult) and greatly reduced whole‐body chitin content. Exon‐specific RNAi showed that splice variant 8a of TcCHS1 was required for both the larval‐pupal and pupal‐adult moults, whereas splice variant 8b was required only for the latter. TcCHS2 ‐specific RNAi had no effect on metamorphosis or on total body chitin content. However, RNAi‐mediated down‐regulation of TcCHS2 , but not TcCHS1 , led to cessation of feeding, a dramatic shrinkage in larval size and reduced chitin content in the midgut.

Background: The ATP-binding cassette (ABC) transporters belong to a large superfamily of proteins that have important physiological functions in all living organisms. Most are integral membrane proteins that transport a broad spectrum of substrates across lipid membranes. In insects, ABC transporters are of special interest because of their role in insecticide resistance.Results: We have identified 73 ABC transporter genes in the genome ofT. castaneum, which group into eight subfamilies (ABCA-H). This coleopteran ABC family is significantly larger than those reported for insects in other taxonomic groups. Phylogenetic analysis revealed that this increase is due to gene expansion within a single clade of subfamily ABCC. We performed an RNA interference (RNAi) screen to study the function of ABC transporters during development. In ten cases, injection of double-stranded RNA (dsRNA) into larvae caused developmental phenotypes, which included growth arrest and localized melanization, eye pigmentation defects, abnormal cuticle formation, egg-laying and egg-hatching defects, and mortality due to abortive molting and desiccation. Some of the ABC transporters we studied in closer detail to examine their role in lipid, ecdysteroid and eye pigment transport.Conclusions: The results from our study provide new insights into the physiological function of ABC transporters inT. castaneum,and may help to establish new target sites for insect control.

INTRODUCTION: Tribolium castaneum is a small, low-maintenance beetle that has emerged as a sophisticated model system for studying the evolution of development and that complements (in some cases, even rivals) Drosophila for functional genetic analysis of basic biological questions. Although Tribolium and Drosophila are both holometabolous insects, they differ fundamentally in larval and adult morphology. Even generally conserved developmental features, such as body segmentation, are achieved by quite different means. Thus, comparison of developmental mechanisms between these two insects can address many interesting questions concerning the evolution of morphology and other characters. Genetic tools available for Tribolium include genetic maps for visible and molecular markers, chromosomal rearrangements that enable lethal mutations to be balanced in true-breeding stocks, transposon-based transformation systems, a completed and annotated genome sequence, and systemic RNA interference (RNAi), which makes it possible to knock down any given gene and even particular splice variants in the offspring or in any tissue of the injected animal. Inactivating gene functions at various developmental stages provides new opportunities to investigate post-embryonic development, as well as larval and adult physiology, including hormonal control, host-parasite interactions, and pesticide resistance.

BeetleBase (http://www.beetlebase.org) has been updated to provide more comprehensive genomic information for the red flour beetle Tribolium castaneum. The database contains genomic sequence scaffolds mapped to 10 linkage groups (genome assembly release Tcas_3.0), genetic linkage maps, the official gene set, Reference Sequences from NCBI (RefSeq), predicted gene models, ESTs and whole-genome tiling array data representing several developmental stages. The database was reconstructed using the upgraded Generic Model Organism Database (GMOD) modules. The genomic data is stored in a PostgreSQL relatational database using the Chado schema and visualized as tracks in GBrowse. The updated genetic map is visualized using the comparative genetic map viewer CMAP. To enhance the database search capabilities, the BLAST and BLAT search tools have been integrated with the GMOD tools. BeetleBase serves as a long-term repository for Tribolium genomic data, and is compatible with other model organism databases.