Extended Data Fig. 7: Additional characterization of mmp14b deficient fish.
From: Extracellular matrix proteolysis maintains synapse plasticity during brain development
a) Representative images and quantification of the number of microglia having 4C4 microglial marker in mpeg-GFP fish (mmp14b+/+, n = 8 fish; mmp14b−/−, n = 7 fish; p = 0.468, Welch’s t-test). Dashed lines indicate hindbrain regions. Scale: 100 µm. b) Representative images and quantification of the total length of microglial processes (mmp14b+/+, n = 23 microglia from n = 7 fish; mmp14b−/−, n = 23 microglia from n = 7 fish; p = 0.026*, Kolmogorov-Smirnov test, performed for microglia). Scale: 5 µm. c) Representative images and quantification of synapse density per µm of dendrite length (Chat-PSD95FingR puncta) in mmp14b−/− and mmp14b+/+ control at 14 dpf. Dots represent means per fish from n = 1-3 dendritic segments analyzed per fish (mmp14b+/+, n = 21 dendrites from n = 11 fish; mmp14b−/−, n = 17 dendrites from n = 11 fish; p = 0.0044**, Welch’s t-test for fish). Scale: 5 µm d) Representative images and quantification of SV2 presynapse marker in mmp14b−/− fish at 14 dpf (mmp14b+/+, n = 7 fish; mmp14b−/−, n = 9 fish, p = 0.035*, Welch’s t-test). SV2 intensity normalized to mean of mmp14b+/+ control. Dashed lines indicate hindbrain regions. Scale: 100 µm. e) Schematics of the astrocytic mmp14b-HA expression construct. f) Representative images and quantification of synapse density per µm of dendrite length (Chat-PSD95FingR puncta) with or without astrocytic Mmp14b rescue. Chat-PSD95FingR;mmp14b+/+ and;mmp14−/− fish were injected with slc1a3b:mmp14b-HA construct at one-cell stage embryos and analyzed at 14 dpf. Dots show means per fish from n = 1 ~ 4 dendritic segments analyzed per fish (mmp14b+/+ no rescue, n = 47 dendrites from n = 22 fish; mmp14b+/+ rescue, n = 47 dendrites from n = 23 fish; mmp14−/− no rescue, n = 48 dendrites from n = 24 fish; mmp14−/− rescue, n = 52 dendrites from n = 24 fish; Two-way ANOVA for fish, F(1,89) interaction effect p = 0.0083**, asterisks show Tukey’s multiple comparisons). Scale: 5 µm. g) Non-merged images of time lapse imaging experiment from Fig. 3m. Circles indicate stable synapses. Boxes indicate the region shown in Fig. 3m. Scale: 5 µm. Values were plotted as mean ± SEM.***: p < 0.001; **: p < 0.01; *: p < 0.05; ns: not significant.
