Sequence of zebrafish Magp1 protein and expression pattern of zebrafish magp1 mRNA during embryonic development. (A) Predicted amino acid sequence of zebrafish Magp1 protein. The predicted amino-terminal signal sequence is underlined. The predicted site of transglutamination at a glutamine residue is indicated by a double underline. The predicted tyrosine sulfation site is indicated by a circle. Predicted O-glycosylation site at a threonine residue. Sites of modifications are predicted based on the amino acid sequence analysis of the bovine MAGP1 protein.27 (B) Phylogenetic tree of vertebrate MAGP proteins. Zebrafish Magp1 clusters with vertebrate MAGP1 proteins. Mouse MAGP1 GenBank accession no. P55002; human MAGP1, P55001; bovine MAGP1, P27424; human MAGP2 (also known as MFAP5), NP_003471; mouse MAGP2, NP_056591. The value at each branch denotes the mean number of differences per residue along each branch. (C) Summary of 2 independent experiments showing the alleviation of zebrafish magp1 MO–generated vascular phenotypes by the coinjection of mouse magp1 expression construct (compare columns 2 and 1). N denotes the number of embryos scored. Error bars indicate SEM. (D) At 16-somite stage (dorsal view shown on the right), magp1 is expressed in the notochord (white arrow in the dorsal view) and the somites (white arrowheads in the dorsal view). (E) At 22 hours after fertilization or 26-somite stage, expression of magp1 in the somites begins to be down-regulated. Expression of magp1 is also detected in the mesoderm. (F) At 24 hours after fertilization (end of somitogenesis), expression of magp1 is detected in the caudal somites and the trunk mesenchyme. (G) A cross-section of a 24-hour embryo showing the expression of magp1 in the connective tissue between the neural tube, around somites (red arrowheads), ventral medial somites, and cells surrounding the dorsal aorta (DA) and the posterior cardinal vein (PCV) (arrows). (H) Expression of magp1 in the blood vessels posterior to the eyes (white arrowheads) and around the eyes (black arrowheads) is also detected at 33 hours after fertilization. For panels E, F, and H, anterior is to the left. Original magnifications: (D-F, H) 10 ×; (G) 20 ×.
