BackgroundEndothelial or epithelial cellular branching is vital in development and cancer progression; however, the molecular mechanisms of these processes are not clear. In Drosophila, terminal cell at the end of some tracheal tube ramifies numerous fine branches on the internal organs to supply oxygen. To discover more genes involved in terminal branching, we searched for mutants with very few terminal branches using the Kiss enhancer-trap line collection.ResultsIn this analysis, we identified cropped (crp), encoding the Drosophila homolog of the transcription activator protein AP-4. Overexpressing the wild-type crp gene or a mutant that lacks the DNA-binding region in either the tracheal tissues or terminal cells led to a loss-of-function phenotype, implying that crp can affect terminal branching. Unexpectedly, the ectopic expression of cropped also led to enlarged organs, and cell-counting experiments on the salivary glands suggest that elevated levels of AP-4 increase cell size and organ size. Like its mammalian counterpart, cropped is controlled by dMyc, as ectopic expression of dMyc in terminal cells increased cellular branching and the Cropped protein levels in vivo.ConclusionsWe find that the branching morphogenesis of terminal cells of the tracheal tubes in Drosophila requires the dMyc-dependent activation of Cropped/AP-4 protein to increase the cell growth of terminal cells.Electronic supplementary materialThe online version of this article (doi:10.1186/s12861-015-0069-6) contains supplementary material, which is available to authorized users.

Meiogyne Miq. (Annonaceae) is a genus of Southeast Asian shrubs and trees with distinctive warty or corrugated patches at the base of the adaxial surface of the inner petals. The plants have small to medium-sized, nearly sessile, axillary flowers and oblong, multi-seeded indehiscent monocarps. Nine species were recognized in the first revision of the genus (van Heusden, 1994), which emphasized as diagnostic features of Meiogyne the differentiated petal bases and the elongate, obliquely oriented connective apex of the anthers of the innermost stamens. These two features united Annonaceae species that previously had been classified in six separate genera:

Artabotrys comprises a species-poor early divergent grade (EDG) and a main species-rich clade ("main Artabotrys clade," MAC). All members of the MAC exhibit a remarkably well-conserved floral Bauplan characterized by a tightly enclosed floral chamber with an elaborate rim between the inner petal blade and claw. Conversely, EDG resembles the sister genus Xylopia in lacking the inner petal rim, with one species (Artabotrys brachypetalus) bearing petals that lack the distinction between blade and claw altogether. The floral phenology and pollination ecology of two exemplar species-Artabotrys brachypetalus from the EDG and Artabotrys blumei from the MAC-are compared, including assessment of effective pollinators and their activity patterns, scent chemistry and thermogenesis. Our study revealed that Artabotrys blumei exhibits abbreviated anthesis (c. 27 hr), with a floral phenology and morphology that are clearly consistent with pollinator trapping, and may be pollinated by small beetles. Artabotrys brachypetalus has a typical anthetic duration (c. 45 hr), lacks a pollinator trapping mechanism, and is pollinated by honey bees and curculionid beetles. The "xylopioid" traits of the EDG are likely to be plesiomorphic, whereas the tightly enclosed floral chamber is likely to be apomorphic for the MAC and functionally significant in trapping pollinators.

Oncodostigma Diels (1912: 143) was erected by Diels (1912) based on the type species O. leptoneura Diels (1912: 143). Five additional species were subsequently added to the genus, viz.: O. wilsonii Guillaumin (1931: 224), O. monosperma (Hooker & Thomson 1872: 57) Sinclair (1951: 605), O. mindorense (Merrill 1907: 273) Bân (1974: 1779), O. hainanense (Merrill 1925: 131) Tsiang & Li (1979: 81) and O. microflorum Okada (1996: 8). Van Heusden (1992) conducted a detailed comparative study of the floral morphology of Annonaceae and noted that Oncodostigma is not clearly distinct from Meiogyne Miquel (1865: 12). She subsequently transferred O. mindorense and O. monosperma to Meiogyne and reduced O. wilsonii to synonymy with M. cylindrocarpa (Burck 1911: 433) Heusden (1994: 499). The name Oncodostigma hainanense (Merrill 1925: 131) Tsiang & Li (1979: 81) had previously been transferred to Meiogyne by Bân (1973).

Meiogyne oligocarpa sp. nov. (Annonaceae) is described from Yunnan Province in Southwest China. It is easily distinguished from all previously described Meiogyne species by the possession of up to four carpels per flower, its bilobed, sparsely hairy stigma, biseriate ovules and cylindrical monocarps with a beaked apex. A phylogenetic analysis was conducted to confirm the placement of this new species within Meiogyne. Meiogyne oligocarpa represents the second species of Meiogyne in China: a key to the species of Meiogyne in China is provided to distinguish it from Meiogyne hainanensis. Paraffin sectioning was undertaken to study the anatomy of the corrugations on the inner petals of Meiogyne oligocarpa to verify whether they are glandular.