Costs of reproduction and their effect on age-related gene expression in Bombus terrestris queens

Our two main aims were 1) to isolate age-related changes in gene expression in queens of the eusocial bumble bee, Bombus terrestris; and 2) to determine whether experimentally increasing the costs of reproduction (by removing eggs) caused changes in age-related gene expression in these queens. To address these aims we extracted RNA from three key tissues (brain, fat body and ovary) from queens at two time points (10% and 60% mortality phases). Each of these queens had experienced one of two treatments: an egg removal (R) treatment (to increase the costs of reproduction) and an egg removal and replacement (C) treatment (to control for the effects of disturbance caused by egg removal). Overall design: We used mRNA-seq to identify the RNA profiles in three tissue types (brain, fat body and ovary) in two time points (after 10% cohort death (TP1) and 60% cohort death (TP2)) for two treatments (egg removal (R) and egg removal and replacement (C)), with up to six biological replicates per tissue/time point/treatment combination. Each sample was sequenced on two lanes (L1 and L2) of the sequencing machine in order to generate sufficient numbers of reads while controlling for between lane variability.