Survival and function of rip13→Irs2 mice during streptozotocin-induced diabetes. (a) Representative H&E-stained pancreas sections from untreated WT or rip13Irs2 islets compared with pancreas sections obtained 15 days after one injection per day for 5 days of low-dose (40 mg/kg) streptozotocin (strep; original magnification, ×200). (b) Blood glucose levels in WT or rip13→Irs2 mice were measured before and after five (daily) injections of low-dose (40 mg/kg) streptozotocin. Results are expressed as mean ± SEM of eight WT and eight rip13→Irs2 mice (**P < 0.01); (c) Glucose levels (mg/dl) divided by serum insulin levels (ng/dl) are shown for experimental days 0, 6, and 15 (***P < 0.001). (d) Apoptotic cells were detected in deparaffinized sections using a rhodamine DNA fragmentation detection assay. The number of apoptotic nuclei per β cell is shown for day 15. Values are expressed as mean ± SEM of eight WT and eight transgenic mice (***P < 0.001). (e) Transplantation of WT islets into streptozotocin-diabetic mice. C57BL/6 mice were treated with 100 mg/kg streptozotocin for 3 consecutive days. Blood glucose levels were measured in samples obtained through tail bleeds of fed mice before transplantation (shaded area) and at the indicated ages after transplantation of 300 (filled circles) or 150 (open circles) WT islets. (f) Transplantation of rip13→Irs2 islets into streptozotocin-diabetic mice was conducted in identical fashion with 250 (filled circles), 120 (open circles), or 50 (inverted triangles) islets. Values are mean ± SEM of at least three mice per experiment.