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. Author manuscript; available in PMC: 2021 Oct 1.
Published in final edited form as: Toxicology. 2020 Aug 13;443:152561. doi: 10.1016/j.tox.2020.152561

Fig. 1. Model overview: Indirect flight muscle (IFM) development and methylmercury perturbations.

Fig. 1

(A - B) Dorsal view of Drosophila pupae under white light at (A) 24 hours after pupa formation (h APF) and (B) 64 h APF to show the dark pupa stage preceding eclosion. Dashed circles indicate the thorax. (C – D) Cartoon timeline of major myo-morphogenic events of the dorsal longitudinal flight muscles (DLM). Approximate levels of gene expression at each window are indicated by +’s and GWAS candidates in bold font. Heterotypic, directional myoblastfusion requires kirre and occurs from 8 - 24 h APF. The myofibers reach full length at 24 h APF to initiate myotube-tendon attachment and form the myotendinous junction (MTJ) before myotube compaction occurs from 32 - 36 h APF. Myotube elongation and attachment initiation require kon. Attachment maturation continues through 48 h APF as additional adhesion proteins (e.g. integrins inflated(if) and myospheroid (mys)) assemble at the MTJ, at which point myofibrillogenesis proceeds. (E – F) Time-lapse still images from mδ.RFP pupae over the course of IFM development at 24, 36, 41, 48, and 64 hours h APF in (E) control (F) or 10 μM MeHg-treated conditions. Arrows of each panel indicate anterior and posterior attachments of the dorsal myotube. White asterisks (*) demarcate myospheres, while the white chevrons show a change in position in free-moving myospheres. Annotations are limited the left hemithorax. This figure can be viewed in color online. (Additional time lapse movies of (E) and (F) can be viewed in supplementary material online)