Abstract
Apterous A (apA), a member of the LIM-homeobox gene family, plays a critical role in the development of wing. The achaete-scute Complex (AS-C) encodes basic helix-loop-helix (bHLH) transcription factors and functions in bristle development. In the present study, we cloned apA (NlapA) and an achaete-scute homologue (NlASH) from N. lugens. Levels of NlapA and NlASH were higher in nymphs than adults, with particularly high expression in the thorax of nymphs. NlapA expressed more highly in nymphs of the macropterous strain (MS) than those of the brachypterous strain (BS) at 2nd and 4th instar. Knockdown of NlapA and NlASH in vivo generated similar phenotypic defects in the wing (loss-of-bristles, twisted or erect wing). Silencing of NlapA in nymphs of MS led to decreased wing size in adults. Moreover, depletion of NlapA suppressed expression of NlDl, Nlsal, Nlser, Nlvg and Nlwg, both in MS and BS, but induced differential responses of Nlubx and Nlnotch expression between MS and BS. Notably, expression of NlASH was regulated by NlapA. These results collectively indicate that NlapA is an upstream modulator of wing size, bristle formation and patterning. Further studies on DNA-protein and protein-protein interactions are required to elucidate NlapA-mediated regulation of wing development.
Highlights
Apterous A, a member of the LIM-homeobox gene family, plays a critical role in the development of wing
Several reports have focused on the effects of environmental and genetic factors on wing development and dimorphism of BPH26, the underlying molecular mechanisms remain unclear
In D. melanogaster and T. castaneum, the dorsal selector gene, ap, determines the activation of Notch signaling along the dorso-ventral boundary, in turn, inducing expression of wg, and acts as a long-range morphogen, providing positional information along the dorso-ventral axis by triggering expression of vg at different thresholds[31]
Summary
Apterous A (apA), a member of the LIM-homeobox gene family, plays a critical role in the development of wing. The achaete-scute Complex (AS-C) encodes basic helix-loop-helix (bHLH) transcription factors and functions in bristle development. Expression of NlASH was regulated by NlapA These results collectively indicate that NlapA is an upstream modulator of wing size, bristle formation and patterning. A 26 bp deletion within the Bm-ASH2 (ac/sc homologue of Bombyx mori) promoter is closely linked to the scaleless mutation, and leads to loss of Bm-ASH2 expression and the scaleless-wing phenotype, indicating that Bm-ASH2 plays a critical role in scale formation in B. mori[17]. Selection of the sensory organ precursor is associated with high levels of ac/sc expression maintained by regulators, such as Sens, Pannier, Chip, dLMO, Ap, Wingless and Shaggy. Downregulation of BPH Distal-less in 3rd-instar larvae leads to disrupted development of the leg, and that of NlDll in 5th- instar larvae to abnormal wing formation[29]
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