<p><b>Copyright information:</b></p><p>Taken from "The chemokine Sdf-1 and its receptor Cxcr4 are required for formation of muscle in zebrafish"</p><p>http://www.biomedcentral.com/1471-213X/7/54</p><p>BMC Developmental Biology 2007;7():54-54.</p><p>Published online 22 May 2007</p><p>PMCID:PMC1904199.</p><p></p>D-I) RNA in situ hybridization with riboprobe (blue). (A,B) High level of transcript in newly formed and posterior somites, 13.5 h and 16 h respectively. In somites, expression is restricted to anterior part. Expression becomes increasingly restricted to anterior part within each somite over time, black arrows. (C) Overlapping expression domain of with (red) is observed, 14 h. (J) Schematic representation of expression (blue) in posterior somites. (D) staining covers almost the entire three anterior-most somites indicated by white bracket, while in posterior somites expression is restricted to posterior part, 13 h. (E) Expression in early somites, 11 h. (F,G) Overlap of expression of and (red), 14 h. (H) Expression is restricted to the posterior part of each somite, 16.5 h, white arrowheads. (I) Faint expression is detected in forming and newly formed somite, 21 h. (K) Schematic representation of expression (blue) in posterior somites. (L) Reverse transcription (RT)-PCR detects continuous presence of transcript of during early development. transcript is present at low levels before mid-blastula transition (MBT). To confirm results, the PCR products were sequenced. was used as a positive control. -RT control using primers without addition of reverse transcriptase, no band was detected (data not shown). Black dashed lines indicate boundary between somite and newly formed somite (B,I). White lines demarcate the somite boundaries (C,H). Abbreviations: a – anterior; p – posterior; psm – presomitic mesoderm; r – rhombomere; s – somite; S0 – forming somite; S1 – newly formed somite; tb – tailbud; ys – yolk sac. Scale bars = 50 μm