Journal: bioRxiv

Article Title: Developmental system drift in dorsoventral patterning is linked to transitions to autonomous development in Annelida

doi: 10.1101/2025.05.29.656861

Figure Lengend Snippet: ( a ) Whole mount in situ hybridisation of the secondary messenger smad1/5/8 and receptors bmpr1 and bmpr2 of the BMP pathway at the blastula (6 hpf), gastrula (9 hpf) and larval (24 hpf) stages in O. fusiformis . ( b ) Schematic diagram of a multiple protein alignment of the MH domains and linker region of SMAD1/5/8 across bilaterian and cnidarians highlighting the high conservation of the MH domains. ( c ) Multiple protein alignment in the linker region of SMAD1/5/8 showing the presumptive MAPK phosphorylation sites (highlighted in violet). Only Deuterostomes have all sites conserved. ( d ) Multiple protein alignment of the C-terminus of SMAD1/5/8 proteins showing the conserved residues recognised by the pSMAD1/5/8 antibody used in this study. In ( a ), the arrowheads point to the 4d organiser, and the asterisks mark the animal/apical pole. Scale bars are 50 µm. an anus, ao apical organ, bp blastopore, ch chaetae, cs chaetal sac, fg foregut, lat lateral, mo mouth, pt prototroch, veg vegetal.

Article Snippet: To detect the activation of SMAD1/5/8, the primary antibody rabbit anti-Phospho- Smad1/5 (Cell Signaling Technology; Cat No.: 9516) was used following a modified protocol used in other spiralians .

Techniques: In Situ, Hybridization, Phospho-proteomics