Differential gene transcription across the life cycle in <italic>Daphnia magna</italic> using a new all genome custom-made microarray.

Background: Unravelling the link between genes and environment across the life cycle is a challenging goal that requires model organisms with well-characterized life-cycles, ecological interactions in nature, tractability in the laboratory, and available genomic tools. Very few well-studied invertebrate model species meet these requirements, being the waterflea <italic>Daphnia magna</italic> one of them. Here we report a full genome transcription profiling of <italic>D. magna</italic> during its life-cycle. The study was performed using a new microarray platform designed from the complete set of gene models representing the whole transcribed genome of <italic>D. magna.</italic> Results: Up to 93% of the existing 41,317 <italic>D. magna</italic> gene models showed differential transcription patterns across the developmental stages of <italic>D. magna</italic>, 59% of which were functionally annotated. Embryos showed the highest number of unique transcribed genes, mainly related to DNA, RNA, and ribosome biogenesis, likely related to cellular proliferation and morphogenesis of the several body organs. Adult females showed an enrichment of transcripts for genes involved in reproductive processes. These female-specific transcripts were essentially absent in males, whose transcriptome was enriched in specific genes of male sexual differentiation genes, like <italic>doublesex</italic>. Conclusion: Our results define major characteristics of transcriptional programs involved in the life-cycle, differentiate males and females, and show that large scale gene-transcription data collected in whole animals can be used to identify genes involved in specific biological and biochemical processes. [ABSTRACT FROM AUTHOR]