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Fig. 7 Figure 7. Evolutionary conservation and upstream regulation of Isl1 sinoatrial node (SAN) enhancer function.A, View of Isl1 locus SAN enhancer (ISE) with alignment to human, mouse, and opossum genomes (above, areas in red indicate >70% conservation, scale from 50% to 100%) and previously published embryonic heart chromatin immunoprecipitation and sequencing (ChIP-seq) data for Gata4 (GATA-binding protein 4), Tbx5 (T-box transcription factor 5), and Tead1 (TEA domain transcription factor 1). B, Maximum intensity projections of confocal z-stacks of 48 hours postfertilization (hpf) Tg(myl7:mCherry-NTR) zebrafish hearts after injection of ISE:green fluorescent protein (GFP) reporter construct (top), or a 1.0-kb fragment (Fr1, lower). C, Enhancer-reporter analysis of founders from injections of ISE and a 1 kb fragment (Fr1 [fragment 1]) in 48 hpf zebrafish hearts with the indicated patterns of reporter activity. Numbers in parentheses indicate the embryos observed to have the indicated expression pattern/total embryos injected that survived to 48 hpf. a indicates atrium; ATAC-seq, assay for transposase-accessible chromatin; avc, av canal; F0, filial generation 0; PC, pacemaker cell; RACM, right atrial cardiomyocyte; san, sinoatrial node; sv, sinus venosus; and v, ventricle.