Species- and size-related differences in dopamine-like immunoreactive clusters in the brain of Nasonia vitripennis and N. giraulti

AbstractAn extreme reduction in body size has been shown to negatively impact the memory retention level of the parasitic waspNasonia vitripennis. In addition,N. vitripennis andNasonia giraulti, closely related parasitic wasps, differ markedly in the number of conditioning trials required to form long-term memory. These differences in memory dynamics may be associated with differences in the dopaminergic neurons in theNasonia brains. Here, we used dopamine immunoreactivity to identify and count the number of cell bodies in dopaminergic clusters of normal- and small-sizedN. vitripennis and normal-sizedN. giraulti. We counted in total a maximum of approximately 160 dopaminergic neurons per brain. These neurons were present in 9 identifiable clusters (D1a, D1b, D2, D3, D4a, D4b, D5, D6 and D7). Our analysis revealed thatN. giraulti had fewer cells in the D2 and D4a clusters but more in D4b, compared with normal-sizedN. vitripennis. In addition, we found fewer cells in the D5 and D7 cluster of small-sizedN. vitripennis compared to normal-sizedN. vitripennis. A comparison of our findings with the literature on dopaminergic clusters in the fruit flyDrosophila melanogaster and the honey beeApis mellifera indicates that clusters D2, D3 and D5 may play a role in memory formation inNasonia wasps. The results from both the species comparison and the size comparison are therefore of high interest and importance for our understanding of the complex intricacies that underlie the memory dyn...
Source: Cell and Tissue Research - Category: Cytology Source Type: research