Laminin can rescue pathology in lama2−/− larvae. a Heat shocked transgenic lama2−/− larvae carrying the Tg(hsp70l:Lama2-mCherry) cassette are were measured for active force at 6 dpf using a force transducer. The optimal length for active contraction was first determined, then muscles were stimulated at this length at supra-maximal voltage for maximal force production. Providing heatshock at 3 but not at 5 dpf resulted in an increased active force within mutants. b, c Two distinct methods of exogenous delivery of fluorescently labelled Lam111, systemic (b) and direct intramuscular injection (c) lead to the accumulation of laminin protein preferentially at areas of fibre loss (arrows), as detected in Tg(actc1b:EBFP2) as reduced blue fluorescence. d, e Injection into the transgenic line Tg(smyhc1:GFP) which provides single-fibre resolution of the superficial slow muscle palisade, reveals both focal (arrowheads) and large fibre-associated regions (arrows). b, c Single confocal plane images; d, e maximum projection images of myotome. Larvae at 5 dpf. f Injection of Lam111 at 3 dpf ameliorates the rate of muscle loss in lama2−/− larvae. Results are expressed as a mean ± SD, each group n = 12 per data point. Significance is tested in a two-way ANOVA between groups at each time point; *p < 0.05, ****p < 0.0001. Scale bars, 20 μm
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