Hematopoietic and Vascular System Toxicity - Zebrafish: Methods for Assessing Drug Safety and Toxicity - page 82

7.3.5.5 Lymphoid Cells T cells can be assayed by looking at rag1, rag2, and
ikaros expression beginning at 4dpf in the thymus. Rag2:EGFP (Langenau
et al., 2004) and RAG2:dsRED (Langenau et al., 2005) transgenic lines label
T-cell populations with fluorescent markers. B-cell lymphocytes are not as well
characterized, but can be identified with immunoglobin gene expression levels in the
pancreas and kidney (Danilova and Steiner, 2002).
7.3.5.6 Thrombocytes Thrombocytes and their precursors express CD41 at
high levels. (It is important to note that zebrafish HSCs also express CD41, but at
lower levels.) CD41 positive cells can be detected in circulation by 2-3dpf, and are
present in the adult kidney. CD41 levels can be assayed by ISH or with a CD41-eGFP
transgenic line (Lin et al., 2005).
7.3.5.7 Vasculature Flk1 and fli1 are expressed in endothelial precursors from
five somites. They appear as two stripes until merging and forming the ICM by 18hpf.
Flk1 and fli1 are also expressed in differentiated vascular cells. By 24hpf, ISVs have
formed, and express flk1 and fli1. fli:eGFP (Lawson and Weinstein, 2002) and flk:
eGFP (Jin et al., 2005) transgenic lines have been created. Specification of the DA and
PCV can also be analyzed by ISH at 24-28hpf. Numerous genes are expressed in the
dorsal aorta, including ephrinB2, notch5, and deltaC. In contrast, Flt4 and ephB4 are
expressed in the PCV.
7.4 SUMMARY
Hematopoietic and vascular development is highly conserved among vertebrate
organisms, including the zebrafish. This chapter has summarized many methods
that are available to assay the zebrafish hematopoietic and vascular systems. When
analyzing toxic effects of compounds, these assays provide numerous approaches to
confirm functional blood and vascular development in embryonic and adult zebrafish.
ACKNOWLEDGMENT
We would like to thank Michelle Lin for critical review of this manuscript.
REFERENCES
B ALDESSARI D and M IONE M (2008). How to create the vascular tree? (Latest) help from the zebrafish.
Pharmacol Ther 118(2): 206-230.
B ENNETT CM, K ANKI JP, R HODES J, L IU TX, P AW BH, K IERAN MW, L ANGENAU DM, D ELAHAYE -B ROWN A,
Z ON LI, F LEMING MD, and L OOK AT (2001). Myelopoiesis in the zebrafish, Danio rerio. Blood 98(3):
643-651.