The blood-feeding bug Rhodnius prolixus ingests a large blood meal, and this is followed by a rapid diuresis to eliminate excess water and salt. Previous studies have demonstrated that serotonin and an unidentified peptide act as diuretic factors. In other insects, members of the corticotropin-releasing factor (CRF)-related peptide family have been shown to play a role in post-feeding diuresis. Using fluorescence immunohistochemistry and immunogold labelling with antibodies to the Locusta CRF-like diuretic hormone (Locusta-DH) and serotonin, we have mapped the distribution of neurones displaying these phenotypes in R. prolixus. Strong Locusta-DH-like immunoreactivity was found in numerous neurones of the central nervous system (CNS) and, in particular, in medial neurosecretory cells of the brain and in posterior lateral neurosecretory cells of the mesothoracic ganglionic mass (MTGM). Positively stained neurohaemal areas were found associated with the corpus cardiacum (CC) and on abdominal nerves 1 and 2. In addition, Locusta-DH-like immunoreactive nerve processes were found over the posterior midgut and hindgut. Double-labelling studies for Locusta-DH-like and serotonin-like immunoreactivity demonstrated some co-localisation in the CNS; however, no co-localisation was found in the medial neurosecretory cells of the brain, the posterior lateral neurosecretory cells of the MTGM or neurohaemal areas. To confirm the presence of a diuretic factor in the CC and abdominal nerves, extracts were tested in Malpighian tubule secretion assays and cyclic AMP assays. Extracts of the CC and abdominal nerves caused an increase in the rate of secretion and an increase in the level of cyclic AMP in the Malpighian tubules of fifth-instar R. prolixus. The presence of the peptide in neurohaemal terminals of the CC and abdominal nerves that are distinct from serotonin-containing terminals indicates that the peptide is capable of being released into the haemolymph and that this release can be independent of the release of serotonin.
So long Andy and welcome Monica
We say a fond farewell to Andy Biewener who, after 20 years and steering hundreds of manuscripts through peer review, will be stepping down from his role as JEB Editor. We are delighted to welcome Monica Daley to the team in his place.
Call for papers - Building New Paradigms in Comparative Physiology and Biomechanics
Our upcoming special issue is welcoming submissions until 31 July 2021. The special issue will be published in early 2022 and will be widely promoted online and at key global conferences.
Supporting early-career researchers
As a journal published by The Company of Biologists, we champion early-career researchers. Find out more about the practical solutions available to help this vital community navigate the first stages of their careers.
Neuroethology of number sense across the animal kingdom
Andreas Nieder considers the fundamentally different types of brains of diverse and distantly related animal species that give rise to number skills across the animal kingdom.
Hiking trails ideal for sauntering grizzlies
New measurements reveal that grizzly bears use similar amounts of energy as humans when walking and prefer to take routes with a gradient of less than 10%, which explains why they sometimes turn up on human hiking trails that are shallow for our use and are also ideal for grizzlies.
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