BackgroundCAP/Capulet (Capt), Slingshot (Ssh) and Cofilin/Twinstar (Tsr) are actin-binding proteins that restrict actin polymerization. Previously, it was shown that low resolution analyses of loss-of-function mutations in capt, ssh and tsr all show ectopic F-actin accumulation in various Drosophila tissues. In contrast, RNAi depletion of capt, tsr and ssh in Drosophila S2 cells all affect actin-based lamella formation differently. Whether loss of these three related genes might cause the same effect in the same tissue remains unclear.MethodsLoss-of-function mutant clones were generated using the MARCM or EGUF system whereas overexpression clones were generated using the Flip-out system. Immunostaining were then performed in eye imaginal discs with clones. FRAP was performed in cultured eye discs.ResultsHere, we compared their loss-of-function phenotype at single-cell resolution, using a sheet of epithelial cells in the Drosophila eye imaginal disc as a model system. Surprisingly, we found that capt and ssh, but not tsr, mutant cells within and posterior to the morphogenetic furrow (MF) shared similar phenotypes. The capt/ssh mutant cells possessed: (1) hexagonal cell packing with discontinuous adherens junctions; and (2) largely complementary accumulation of excessive phosphorylated myosin light chain (p-MLC) and F-actin rings at the apical cortex. We further showed that the capt/ssh mutant phenotypes depended on the inactivation of protein kinase A (PKA) and activation of Rho.ConclusionsAlthough Capt, Ssh and Tsr were reported to negatively regulate actin polymerization, we found that Capt and Ssh, but not Tsr, share overlapping functions during eye morphogenesis.

dorsal closure is a morphogenetic movement that involves flanking epidermal cells, assembling actomyosin cables, and migrating dorsally over the underlying amnioserosa to seal at the dorsal midline. Echinoid (Ed)-a cell adhesion molecule of adherens junctions (AJs)-participates in several developmental processes. The disappearance of Ed from the amnioserosa is required to define the epidermal leading edge for actomyosin cable assembly and coordinated cell migration. However, the mechanism by which Ed is cleared from amnioserosa is unknown. Here, we show that Ed is cleared in amnioserosa by both transcriptional and post-translational mechanisms. First, mRNA transcription was repressed in amnioserosa prior to the onset of dorsal closure. Second, the ubiquitin ligase Smurf downregulated pretranslated Ed by binding to the PPXY motif of Ed. During dorsal closure, Smurf colocalized with Ed at AJs, and Smurf overexpression prematurely degraded Ed in the amnioserosa. Conversely, Ed persisted in the amnioserosa of mutant embryos, which, in turn, affected actomyosin cable formation. Together, our results demonstrate that transcriptional repression of followed by Smurf-mediated downregulation of pretranslated Ed in amnioserosa regulates the establishment of a taut leading edge during dorsal closure.

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In this current work, pyromellitic acid (PMA) was employed to synthesize a NiCo metal-organic framework (MOF) for supercapacitors. The resultant NiCo-MOF (PMA) showed dandelion-like structure and therefore its surface area was reached as high as 500.7 m2 g− 1. The NiCo-MOF (PMA) delivered an impressive specific capacitance value of 918.8 F g− 1 at the current density of 1 A g− 1. Upon increasing the current density to 10 A g− 1, it retained 61.1% of the capacitance obtained at 1 A g− 1. Moreover, the capacitance retention of 64.3% was achieved even after being charged/discharged at 10 A g− 1 for 10,000 cycles. More importantly, the asymmetric supercapacitor (ASC) based on the NiCo-MOF (PMA) cathode showed specific capacitance of 83.47 F g− 1 at 0.5 A g− 1 and 80.34% of its initial capacitance was still maintained after 5,000 cycles at 5 A g− 1. Furthermore, the ASC delivered an energy density of 23.88 Wh kg− 1 at a power density of 750 Wkg− 1. Additionally, two ASCs in series successfully drove 120 green LEDs lighting for 21 minutes, demonstrating its potential practical applications.