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Fig. 8. Triple knockdown of Arp2, tau and XNIF substantially phenocopied hnRNP K knockdown. (Aa-Cb) Parasagittal optical sections of stage 37/38 heads immunostained for peripherin in whole mount. Whereas Arp2 MO (Aa,Ab) and tau MO (Ba,Bb) injected individually yielded only moderate defects in peripheral axon outgrowth on the injected side, triple knockdown of Arp2, tau and XNIF yielded severe defects (Ca,Cb). II, optic; Vop and Vmd, opthalmic and mandibular branches of the trigeminal; VII, facial; IX, glossopharyngeal; and X, vagus nerves. (Da-Fe) In dissociated culture, Arp2 and tau MO injected individually yielded marked defects in actin filaments and microtubules, respectively, compared with control MO (Da-Dd, phalloidin stained; Ea-Ed, N-β tubulin immunostained). Triple knockdown of Arp2, tau and XNIF synergistically compromised axon outgrowth severely (Fb,Fd) compared with control MO (Fa,Fc). Fa,Fb, phalloidin stained; Fc,Fd, N-β tubulin immunostained. Scale bars: 100 μm for Aa-Cb; 10 μm for Db,Dd,Eb,Ed; 20 μm for Da,Dc,Ea,Ec,Fa-Fd. Bar graphs show mean total length of neuritic arbor and number of higher order branches (secondary and higher) per cell (±s.d., three cultures). White bars, uninjected; black bars, control MO-injected; gray bars, bilaterally injected with Arp2 (De), tau (Ee) or all three (Fe) MOs. **P<0.01, t-test. Numbers of uninjected, control MO and experimental MO neurons were: De: 128, 107, 106; Ee: 117, 104, 109; Fe: 108, 115, 126, respectively. |
