scholarly journals The distribution of a CRF-like diuretic peptide in the blood-feeding bug Rhodnius prolixus

1999 ◽  
Vol 202 (15) ◽  
pp. 2017-2027 ◽  
Author(s):  
V.A. Te Brugge ◽  
S.M. Miksys ◽  
G.M. Coast ◽  
D.A. Schooley ◽  
I. Orchard
Keyword(s):  
Cyclic Amp ◽  
Malpighian Tubule ◽  
Immunogold Labelling ◽  
Blood Feeding ◽  
Neurosecretory Cells ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Double Labelling ◽  
Neurohaemal Areas ◽  
The Brain

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.

Anti-diuresis in the blood-feeding insect Rhodnius prolixus Stål: the peptide CAP2b and cyclic GMP inhibit Malpighian tubule fluid secretion.

1997 ◽  
Vol 200 (17) ◽  
pp. 2363-2367 ◽  
Author(s):  
M C Quinlan ◽  
N J Tublitz ◽  
M J O'Donnell
Keyword(s):  
Cyclic Gmp ◽  
Physiological Role ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Blood Feeding ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Tubule Fluid ◽  
Secretion Rates

Rhodnius prolixus eliminates NaCl-rich urine at high rates following its infrequent but massive blood meals. This diuresis involves stimulation of Malpighian tubule fluid secretion by diuretic hormones released in response to distention of the abdomen during feeding. The precipitous decline in urine flow that occurs several hours after feeding has been thought until now to result from a decline in diuretic hormone release. We suggest here that insect cardioacceleratory peptide 2b (CAP2b) and cyclic GMP are part of a novel mechanism of anti-diuresis. Secretion rates of 5-hydroxytryptamine-stimulated Malpighian tubules are reduced by low doses of CAP2b or cyclic GMP. Maximal secretion rates are restored by exposing tubules to 1 mmol l-1 cyclic AMP. Levels of cyclic GMP in isolated tubules increase in response to CAP2b, consistent with a role for cyclic GMP as an intracellular second messenger. Levels of cyclic GMP in tubules also increase as urine output rates decline in vivo, suggesting a physiological role for this nucleotide in the termination of diuresis.

Cyclic AMP in the malpighian tubule fluid and in the urine of Rhodnius prolixus

1990 ◽  
Vol 77 (1) ◽  
pp. 136-142 ◽  
Author(s):  
Ricardo Montoreano ◽  
Francisco Triana ◽  
Teresa Abate ◽  
Rafael Rangel-Aldao
Keyword(s):  
Cyclic Amp ◽  
Malpighian Tubule ◽  
Rhodnius Prolixus ◽  
Tubule Fluid

Intracellular ion activities in Malpighian tubule cells ofRhodnius prolixus: evaluation of Na+-K+-2Cl-cotransport across the basolateral membrane

2002 ◽  
Vol 205 (11) ◽  
pp. 1645-1655 ◽  
Author(s):  
Juan P. Ianowski ◽  
Robert J. Christensen ◽  
Michael J. O'Donnell
Keyword(s):  
Basolateral Membrane ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Rhodnius Prolixus ◽  
Passive Movement ◽  
Malpighian Tubules ◽  
Intracellular Ion Activities ◽  
Ion Activities ◽  
Tubule Cells ◽  
Electrochemical Potentials

SUMMARYIntracellular ion activities (aion) and basolateral membrane potential (Vbl) were measured in Malpighian tubule cells of Rhodnius prolixus using double-barrelled ion-selective microelectrodes. In saline containing 103mmoll-1Na+, 6mmoll-1 K+ and 93mmoll-1Cl-, intracellular ion activities in unstimulated upper Malpighian tubules were 21, 86 and 32mmoll-1, respectively. In serotonin-stimulated tubules, aCl was unchanged, whereas aNa increased to 33mmoll-1 and aK declined to 71mmoll-1. Vbl was -59mV and -63mV for unstimulated and stimulated tubules, respectively. Calculated electrochemical potentials(Δμ/F) favour passive movement of Na+ into the cell and passive movement of Cl- out of the cell in both unstimulated and serotonin-stimulated tubules. Passive movement of K+ out of the cell is favoured in unstimulated tubules. In stimulated tubules, Δμ/F for K+ is close to 0 mV.The thermodynamic feasibilities of Na+-K+-2Cl-, Na+-Cl-and K+-Cl- cotransporters were evaluated by calculating the net electrochemical potential (Δμnet/F) for each transporter. Our results show that a Na+-K+-2Cl- or a Na+-Cl- cotransporter but not a K+-Cl- cotransporter would permit the movement of ions into the cell in stimulated tubules. The effects of Ba2+ and ouabain on Vbl and rates of fluid and ion secretion show that net entry of K+ through ion channels or the Na+/K+-ATPase can be ruled out in stimulated tubules. Maintenance of intracellular Cl- activity was dependent upon the presence of both Na+ and K+ in the bathing saline. Bumetanide reduced the fluxes of both Na+ and K+. Taken together, the results support the involvement of a basolateral Na+-K+-2Cl- cotransporter in serotonin-stimulated fluid secretion by Rhodnius prolixus Malpighian tubules.

Excretion in the Blood-Sucking Bug, Rhodnius Prolixus Stål

1963 ◽  
Vol 40 (2) ◽  
pp. 247-256 ◽  
Author(s):  
S. H. P. MADDRELL
Keyword(s):  
Instar Larva ◽  
Neurosecretory Cells ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Low Level ◽  
Blood Sucking

1. The mechanism underlying diuresis in Rhodnius has been investigated. 2. An isolated preparation of the Malpighian tubules of a 5th-instar larva is described. 3. The rate of secretion by such a preparation, isolated in a drop of haemolymph, is at first high but soon falls to a low level. It can be restored by the addition of haemolymph taken from an insect during diuresis. 4. It has been shown that diuresis is promoted by some substance, presumably a neurohormone, which can be extracted from the posterior neurosecretory cells of the fused ganglionic mass situated in the mesothorax.

Ovulation in Rhodnius prolixus Stal is induced by an extract of neurosecretory cells

1983 ◽  
Vol 61 (3) ◽  
pp. 684-686 ◽  
Author(s):  
F. L. Kriger ◽  
K. G. Davey
Keyword(s):  
Neurosecretory Cells ◽  
Rhodnius Prolixus ◽  
Pars Intercerebralis ◽  
Median Neurosecretory Cells ◽  
The Brain

The injection of an extract of 10 identified median neurosecretory cells from the pars intercerebralis into gravid mated females previously deprived of these cells by surgery induces ovulation and oviposition during the ensuring 24 h. Injection of an extract of ocellar nerves has no effect. These observations support the hypothesis that ovulation and oviposition are controlled by a myotropin released from neurosecretory cells in the brain.

scholarly journals A comparison of the effects of two putative diuretic hormones from Locusta migratoria on isolated locust malpighian tubules

1993 ◽  
Vol 175 (1) ◽  
pp. 1-14 ◽  
Author(s):  
G. M. Coast ◽  
R. C. Rayne ◽  
T. K. Hayes ◽  
A. I. Mallet ◽  
K. S. Thompson ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Arginine Vasopressin ◽  
Locusta Migratoria ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Enzymatic Digestion ◽  
Malpighian Tubules ◽  
Suboesophageal Ganglion ◽  
Anatomy And Physiology ◽  
Strong Stimulation

Previous work has shown that a peptide related to arginine vasopressin is present in the suboesophageal ganglion of the locust, Locusta migratoria. This peptide was determined to be an anti-parallel dimer of the nonapeptide Cys-Leu-Ile-Thr-Asn-Cys-Pro-Arg-Gly-NH2 and was reported to stimulate cyclic AMP production and fluid secretion in a combined Malpighian tubules and midgut preparation from locusts. For these reasons the peptide has been called the arginine-vasopressin-like insect diuretic hormone (AVP-like IDH). Recently, a second diuretic peptide (Locusta-DP), which is related to corticotropin releasing factor, has been identified: this is a potent stimulant of fluid secretion and cyclic AMP production by isolated locust tubules. Because water balance in insects is likely to be controlled by a cocktail of hormones acting on both Malpighian tubules and hindgut, this study directly compares the activity of these two peptides in fluid secretion and cyclic AMP production bioassays on one target organ, the isolated Malpighian tubule of Locusta migratoria. Locusta-DP was synthesised directly, whereas the dimeric AVP-like IDH was obtained by oxidation of a synthetic nonapeptide monomer. Products were separated by RP-HPLC and their structures unequivocally confirmed by enzymatic digestion, sequence analysis and electrospray mass spectrometry. We show that Locusta-DP causes strong stimulation of fluid secretion and cyclic AMP production, whereas the AVP-like IDH has no effect in either assay. These findings are discussed in the light of recent work on the anatomy and physiology of the vasopressin-like immunoreactive (VPLI) neurones in the suboesophageal ganglion of Locusta migratoria, the proposed source of the AVP-like peptide.

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