Intestinal stem cells (ISCs) in the Drosophila adult midgut are essential for maintaining tissue homeostasis and replenishing lost cells in response to tissue damage. Here we demonstrate that the Hippo (Hpo) signaling pathway, an evolutionarily conserved pathway implicated in organ size control and tumorigenesis, plays an essential role in regulating ISC proliferation. Loss of Hpo signaling in either midgut precursor cells or epithelial cells stimulates ISC proliferation. We provide evidence that loss of Hpo signaling in epithelial cells increases the production of cytokines of the Upd family and multiple EGFR ligands that activate JAK-STAT and EGFR signaling pathways in ISCs to stimulate their proliferation, thus revealing a unique non–cell-autonomous role of Hpo signaling in blocking ISC proliferation. Finally, we show that the Hpo pathway mediator Yorkie (Yki) is also required in precursor cells for injury-induced ISC proliferation in response to tissue-damaging reagent DSS.

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We determined the complete nucleotide sequences of the mitochondrial genome (mitogenome) of the Korean hairstreak, Coreana raphaelis (Lepidoptera: Lycaenidae). The entire mitochondrial DNA (mtDNA) molecule was 15,314 bp long. The C. raphaelis genes were in the same order and orientation as the completely sequenced mitogenomes of other lepidopteran species, except for the presence of an extra copy of tRNA(Ser)(AGN). High similarity in primary sequence and secondary structure between the two tandemly located copies of the tRNA(Ser)(AGN) suggest a recent duplication of an original single tRNA(Ser)(AGN). The DHU arm of the two copies of tRNA(Ser)(AGN) formed a simple loop as seen in many other metazoan mt tRNA(Ser)(AGN). The putative initiation codon for the C. raphaelis COI gene appears to be a tetranucleotide, TTAG, found commonly in the sequenced lepidopterans. ATPase8, ATPase6, ND4L and ND6 genes, which are next to another protein-coding gene at their 3' end all had the sequences potential to form a hairpin structure, suggesting the importance of such a structure for precise cleavage of the mature protein-coding genes.