C57/129SJ wild type (WT) and PARP1-/- mice were infected with Trypanosoma cruzi (10,000 Tc/mouse), and sacrificed at 150 days’ post-infection (pi) corresponding to chronic disease phase. (A) RT-qPCR evaluation of myocardial levels of PARP1 mRNA, normalized to GAPDH mRNA (n ? 5 mice/group, triplicate observations per mouse). (B-K) Myocardial tissue homogenates and fractionated organelles were prepared as detailed in Materials and Methods. Representative Western blot images (n = 3 mice/group) are shown for total heart homogenate levels of PARP1 and GAPDH (B), cytosolic levels of PARP1 and PAR with GAPDH as loading control (D&F), nuclear levels of PARP1 and PAR with Lamin B as loading control (D&G), and mitochondrial levels of PARP1 and PAR with COIV as loading control (D&H). Densitometry analysis was performed for all Western blot gels from n ? 6 mice/group, and data for PARP1 and PAR levels in total heart homogenates and cytosolic fractions (C,E,&I), nuclear fractions (E&J) and mitochondrial fractions (E&K) are presented. In bar graphs, data are plotted as mean value ± SEM. Statistical significance is marked as *WT.Tc vs. WT, &PARP1-/-.Tc vs. PARP1-/-, and #WT.Tc vs. PARP1-/-.Tc (**,&&,##p<0.01, ***,&&&,###p<0.001).