Figure 4.

Ceramide effects on zebrafish morphology and blood flow. (A) Composite images of head, mid-trunk, and tail regions of a DMSO-exposed (control) 48 hpf embryo and a composite image of head, mid-trunk and tail regions of 48 hpf embryo exposed to ceramide. The heart in each is denoted by the black arrowhead. (B) Blood vessel development in zebrafish embryos. At the top is a schematic diagram of the zebrafish circulatory system in the trunk region illustrating key structures. (ISA: Intersegmental artery; ISV: Intersegmental vein; DLAV: dorsal longitudinal anastomotic vessel). Blood flows caudally (to the right) via the dorsal aorta (DA), and returns rostrally (to the left) via post cardinal vein (PCV). At the bottom is a brightfield image of blood vessels in a 48 hpf embryo. Dashed lines denote the vessels. (C) Intersegmental blood vessel (ISBV) diameter in the mid-trunk region is altered in zebrafish embryos exposed to ceramide. Top; DMSO- exposed embryo at 48 hpf. Bottom; ceramide-exposed embryo at 48 hpf. White arrows in both images denote ISBVs. Black arrows point to individual blood cells. D. Quantification revealed that ceramide exposure altered blood flow in 69% of the embryos examined. Heart rates were also measured and found to be similar in both cases. Lastly, in ceramide exposed embryos, intersegmental blood vessels (ISBVs) that lacked blood flow were significantly thinner in diameter than blood vessels in DMSO control embryos (* p < 0.01). Scale bars = 500 µm in A, 20 µm in B and C.