PhD Candidate York University Toronto, Ontario, Canada
The insect ion transport peptide (ITP) and its alternatively spliced variant, ITP-like (ITP-L) belong to the crustacean hyperglycemic hormone family of peptides and are widely conserved among insect species. While limited, various studies have characterized the ITP/ITP-L signaling systems within many insects, and putative functions including regulation of ion and fluid transport, ovarian maturation, and thirst/excretion have been proposed. However, to date, the expression pattern, tissue distribution, and physiological function of either ITP or ITP-L has not been elucidated in the mosquito, Aedes aegypti. Herein, we aim to molecularly investigate ITP and ITP-L expression profiles in A. aegypti, and examine peptide immunolocalization and distribution within adult tissues. Thus far, transcript expression profiles of both ITP and ITP-L reveal enrichment in males, with ITP exclusively expressed in the brain, and ITP-L expressed predominantly in the abdominal ganglia. Using immunohistochemistry, the central nervous system from adult mosquitoes revealed ITP-like immunostaining in one pair of lateral neurosecretory cells in the posterior region of each brain hemisphere. ITP-L-like immunostaining was observed in one neurosecretory cell located medioposteriorly and ventrally on each abdominal ganglia, with nerve processes migrating anteriorly from the neurosecretory cell and emanating laterally through projections to potential putative neurohaemal sites. Lastly, both starvation and blood-feeding caused upregulation of ITP and ITP-L mRNA in adult mosquitoes, suggesting possible functional roles in ionoregulation. Due to the suggested anti-diuretic role of ITP, further examining the distribution and physiological roles of both ITP and ITP-L may uncover possible osmoregulatory mechanisms within the adult A. aegypti mosquito.
