Combined loss of asxl1 and tet2 leads to MPN and AML in a subset of adult zebrafish. Morphological and quantitative analysis of blood cell types in the kidney marrow and peripheral blood of 5-month-old fish with the indicated genotypes. MGG staining was performed on kidney marrow smears. (A-H) Red arrows denote mature erythrocytes; light blue arrows denote myelomonocytes; green arrows denote lymphocytes; black arrows denote progenitor cells; and orange arrows denote immature red blood cells. (A) In wild-type fish, the kidney marrow hematopoietic cells showed normal maturation and morphology. (B) Five of 11 asxl1+/−tet2+/+ fish had an increased number of mature myeloid cells, indicating MPN; the remaining 6 fish had normal morphology. (C) Eight of 11 asxl1+/−tet2+/− fish showed an increased number of mature myeloid cells, indicating MPN. (D) Two of 10 asxl1+/−tet2−/− fish showed increased myeloid blast cells, indicating AML. Four of the remaining 8 fish had MPN, while the other 4 had normal morphology. (E-H) Analysis of peripheral blood smears by MGG staining. (E) Wild-type fish had normal maturation and morphology of the blood cells. (F) Five of 11 asxl1+/−tet2+/+ fish showed rounded circulating immature red blood cells and increased mature myeloid cells. (G) Eight of 11 asxl1+/−tet2+/− fish showed immature rounded circulating red blood cells. (H) Two of 10 asxl1+/−tet2−/− fish showed an increased number of myeloid blast cells, myelomonocytes and immature erythrocytes. (I-L) Forward- versus side-scatter analysis of kidney marrow cell populations in 5-month-old fish with the indicated genotypes. (M-P) Forward- versus side-scatter analysis of absolute cell numbers per liter of blood in 5-month-old fish with the indicated genotypes, showing increased myelomonocytes and decreased red blood cells in asxl1+/− fish. A subpopulation of asxl1+/−tet2−/− fish showed increased progenitor cell numbers in kidney marrow and blood. Mean values with s.e.m. are shown. Statistical analysis was done with Prism software. Unpaired Student's t-tests were performed in Prism to determine the P-value for each genotypic group compared with controls.
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