Antonio Giraldez: At the tip of the microRNA iceberg

MicroRNAs (miRNAs) are single-stranded RNA molecules of approximately 22 nucleotides. They regulate protein expression by binding to and suppressing translation of messenger RNAs. Less than 20 years ago, they were unheard of, but the number of identified miRNAs is growing. Antonio Giraldez This burgeoning field captured Antonio Giraldez's attention while he was a PhD student studying Drosophila wing morphogenesis (1–3), yet he didn't start his own experiments on the subject until after he had started his postdoc. Better late than never, as Giraldez's studies produced important data showing that zebrafish zygotes unable to make their own miRNAs cannot undergo brain morphogenesis, and that one particular miRNA can rescue the defect (4, 5). Now running his own laboratory at Yale, Giraldez has stuck with zebrafish and investigates how miRNAs shape gene expression to orchestrate embryonic development (6).