Fig. 4

Mechanical force differentially regulates expression of matn1 in ima enthesis tenocytes. Ventral views of Meckel’s cartilage and associated tenocytes showing in situ Hybridization Chain Reaction (isHCR) of matn1 (green) and anti-mCherry immunofluorescence (magenta) marking the tenocytes in Tg(scxa:mCherry) embryos at 72 hpf in WT uninjected (WT) (A–E), aBTX-inj (Paralyzed) (F–J), partially recovered aBTX-inj (Twitching) (K–O), and completely recovered aBTX-inj (Full Recovery) (P–T) conditions at ima enthesis. (D, I, N, S) Grayscale images showing nuclei stained with DAPI with ROIs showing isolated 3D volumes of chondrocytes (green) and enthesis tenocytes (magenta) based on DAPI signal. (E, J, O, T) Insets showing magnified views of the 3D volumes of tenocytes associated with ima enthesis depicting expression of matn1 and stained for mCherry. (U) Violin plot showing changes in mean fluorescence intensity of matn1 in ima enthesis tenocyte nuclei between WT (n = 8), Paralyzed (n = 8), Twitching (n = 6), and Full Recovery (n = 7) with ~8 nuclei measured per embryo. p-value calculated with linear mixed effects model with Tukey post hoc test. *p < 0.05, **p < 0.01, ***p < 0.001. Scale bars = 20 µm.