| cathepsin d-mediated yolk protein degradation is blocked by acid phosphatase inhibitors. | vitellin (vt) is a lipoglycophosphoprotein stored inside the eggs of every oviparous organism during oogenesis. in the blood-sucking bug rhodnius prolixus, vt is deposited inside growing oocytes together with two acid hydrolases: acid phosphatase (ap) and cathepsin d (cd). egg fertilization triggers ap activity and vt proteolysis in vivo [insect biochem. mol. biol. 2002 (32) 847]. here, we show that cd is the main protease targeting vt proteolysis during egg development. cd activity in total egg ... | 2005 | 15797237 |
| a model for fluid secretion in rhodnius upper malpighian tubules (umt). | we have measured fluid secretion rate in rhodnius prolixus upper malpighian tubules (umt) stimulated to secrete with 5-oh-tryptamine. we used double perfusions in order to have access separately to the basolateral and to the apical cell membranes. thirteen pharmacological agents were applied: ouabain, bafilomycin a(1), furosemide, bumetanide, dioa, probenecid, sits, acetazolamide, amiloride, dpc, bacl(2), pcmbs and dtt. these agents are known to block different ion transport functions, namely at ... | 2004 | 15702374 |
| edysteroid receptor (ecr) shows marked differences in temporal patterns between tissues during larval-adult development in rhodnius prolixus: correlations with haemolymph ecdysteroid titres. | the presence of ecdysteroid receptor (ecr) in various tissues was studied throughout larval-adult development of the blood-sucking bug, rhodnius prolixus, using an antibody to ecr that recognizes all isoforms. on western blots, the antibody recognizes three peptides of approximate molecular masses of 70, 68 and 64 kda, from epidermis and fat body of developing larvae, which contain high levels of haemolymph ecdysteroids. these peptides are absent from both unfed larvae and adults, which are devo ... | 2005 | 15686643 |
| the role of salivary lipocalins in blood feeding by rhodnius prolixus. | in order to overcome host mechanisms that prevent blood loss, the blood-sucking bug rhodnius prolixus has evolved a complex salivary secretion containing dozens of different proteins. a number of these have been characterized and found to have roles in inhibiting various hemostatic or inflammatory systems. interestingly, many of these biologically active salivary proteins belong to the lipocalin protein family. a proliferation of lipocalin genes has occurred via gene duplication and subsequent d ... | 2005 | 15660358 |
| the distribution and activity of tachykinin-related peptides in the blood-feeding bug, rhodnius prolixus. | the invertebrate tachykinin-related peptides (trps) with the conserved c-terminal sequence fx1gx2ramide shows sequence similarity to the vertebrate tachykinins after which they are named, and are hypothesized to be ancestrally related. in this study a polyclonal antiserum generated against a locust tachykinin (lomtk i), was used to demonstrate the presence and describe the distribution of lomtk-like immnoreactivity in the cns and gut of rhodnius prolixus. reverse phase high performance liquid ch ... | 2005 | 15626503 |
| antihemostatic strategies of blood-feeding arthropods. | arthropods in at least 23 different families or orders, distributed between two classes (insecta and arachnida), feed on vertebrate blood. they are able to do this despite constraints imposed by a sophisticated array of hemostatic defenses, due to the presence of a wide range of antihemostatic molecules in their saliva, including vasodilators, antiplatelet factors, and anticoagulants. vasodilators include amines, prostaglandins, peptides, proteins, and even a mechanism to store large amounts of ... | 2004 | 15578959 |
| protein functional cycle viewed at atomic resolution: conformational change and mobility in nitrophorin 4 as a function of ph and no binding. | the blood-sucking insect rhodnius prolixus uses nitrophorin 4, a heme protein, to deliver nitric oxide (no) to a victim, causing vasodilation and improved feeding. binding of no occurs at a ferric heme and is modulated by ph. no binding at lower ph induces a large conformational change involving loops a-b and g-h that leads to distal pocket desolvation and protection of the nitrosyl heme complex. we have determined the crystal structures of rhodnius nitrophorin 4 to ultrahigh resolution in four ... | 2004 | 15504026 |
| appetence behaviours of the triatomine bug rhodnius prolixus on a servosphere in response to the host metabolites carbon dioxide and ammonia. | a combination of 1,000 ppm co(2) plus 30-40 ppb nh(3) in an air stream induced rhodnius prolixus nymphs walking on a servosphere to perform a series of appetence behaviours. shortly after the onset of stimulation the nymphs turned sharply upwind towards the source of the chemostimuli (within 13 +/- 9 s) from mostly downwind and crosswind walks in the air stream alone. the mean vector angles of these upwind tracks were concentrated in a cone 60 degrees either side of due upwind. the upwind walkin ... | 2004 | 15503053 |
| rhodnius prolixus malpighian tubule's aquaporin expression is modulated by 5-hydroxytryptamine. | the purpose of the present study was to detect the presence of an aquaporin-like water channel, a member of the major intrinsic protein (mip) family, in the malpighian tubule (mt) of the hematophagous insect rhodnius prolixus, which excrete a large bulk of fluid after a massive blood meal, and its possible regulation by 5-hydroxytryptamine (5-ht). reverse transcription polymerase chain reaction (rt-pcr) and southern blots of cdna was obtained from adult r. prolixus mt poly (a)+ rna. employing de ... | 2004 | 15484262 |
| na+ competes with k+ in bumetanide-sensitive transport by malpighian tubules of rhodnius prolixus. | we examined the effects of bathing saline na+/k+ ratio, bumetanide and hydrochlorothiazide on fluid and ion transport by serotonin-stimulated malpighian tubules of rhodnius prolixus. previous pharmacological and electrophysiological studies indicate that a bumetanide-sensitive na+/k+/2cl- cotransporter is the primary route for basolateral ion entry into the cell during fluid secretion. the goal of this study was to resolve the apparent conflict between relatively high secretion rates by tubules ... | 2004 | 15371478 |
| characterization of an ecto-phosphatase activity in malpighian tubules of hematophagous bug rhodnius prolixus. | we have characterized a phosphatase activity present on the external surface of intact malpighian tubules in rhodnius prolixus. this phosphatase hydrolyses the substrate p-nitrophenyl phosphate at a rate of 3.38 +/- 0.07 nmol pi x mg(-1) x min(-1). phosphatase activity decreased with the increase of the ph from 6.4 to 7.6 ph, a range in which tubules cellular integrity was maintained for at least 1 h. classical inhibitors of acid phosphatase, such as ammonium molybdate, fluoride, vanadate, mpv-p ... | 2004 | 15352154 |
| structural dynamics controls nitric oxide affinity in nitrophorin 4. | nitrophorin 4 (np4) is one of seven nitric oxide (no) transporting proteins in the blood-sucking insect rhodnius prolixus. in its physiological function, no binds to a ferric iron centered in a highly ruffled heme plane. carbon monoxide (co) also binds after reduction of the heme iron. here we have used fourier transform infrared spectroscopy at cryogenic temperatures to study co and no binding and migration in np4, complemented by x-ray cryo-crystallography on xenon-containing np4 crystals to i ... | 2004 | 15258143 |
| extracellular h+ dynamics during oogenesis in rhodnius prolixus ovarioles. | the spatiotemporal dynamics of transmembrane hydrogen ion (h+) fluxes during oogenesis were investigated in the telotrophic ovarioles of the insect, rhodnius prolixus. although rhodnius ovarioles possess exaggerated morphological and electrical polarity between nurse cells and oocytes, little is known about h+ changes during oogenesis, despite the regulatory role played by h+ and ph in many relevant cellular processes. a number of dynamic extracellular h+ fluxes were measured along rhodnius ovar ... | 2004 | 15235012 |
| role of binding site loops in controlling nitric oxide release: structure and kinetics of mutant forms of nitrophorin 4. | nitrophorins are ferric heme proteins that transport nitric oxide (no) from blood-sucking insects to victims. no binding is tighter at lower ph values, as found in the insect salivary gland, and weaker at the ph of the victim's tissue, facilitating no release and subsequent vasodilation. previous structural analyses of nitrophorin 4 (np4) from rhodnius prolixus revealed a substantial no-induced conformational change involving the a-b and g-h loops, which rearrange to desolvate the distal pocket ... | 2004 | 15157102 |
| exploring the sialome of the blood-sucking bug rhodnius prolixus. | rhodnius prolixus is a hemiptera that feeds exclusively on vertebrate blood in all life stages. its salivary glands produce potent pharmacological substances that counteract host hemostasis, including anti-clotting, anti-platelet, and vasodilatory substances. to obtain a further insight into the salivary biochemical and pharmacological complexity of this insect, a cdna library was randomly sequenced, and salivary gland homogenates were fractionated by hplc to obtain aminoterminal sequences of ab ... | 2004 | 14976983 |
| identification and tissue-specific distribution of sulfated glycosaminoglycans in the blood-sucking bug rhodnius prolixus (linnaeus). | we have previously characterized heparan sulfate (hs) as the major ovarian sulfated glycosaminoglycan (gag) in females of rhodnius prolixus, while chondroitin sulfate (cs) was the minor component. using histochemical procedures we found that gags were concentrated in the ovarian tissue but not found inside the oocytes. here, we extend our initial observations of gag expression in r. prolixus by characterizing these molecules in other organs: the fat body, intestinal tract, and the reproductive t ... | 2004 | 14871621 |
| the distribution and effects of dippu-allatostatin-like peptides in the blood-feeding bug, rhodnius prolixus. | using a polyclonal antiserum to dippu-allatostatin 7 (dippu-ast 7; formerly ast 1) of the cockroach diploptera punctata, we have demonstrated the presence of ast-like immunoreactivity (ali) in cells and processes throughout the nervous system, gut, and peripheral tissues of unfed fifth instar and adult rhodnius prolixus. ali in apparent neurosecretory cells of the brain, suboesophageal ganglion, and mesothoracic ganglionic mass, as well as in midgut endocrine cells, suggests that rhodnius allato ... | 2003 | 14706534 |
| axial ligand complexes of the rhodnius nitrophorins: reduction potentials, binding constants, epr spectra, and structures of the 4-iodopyrazole and imidazole complexes of np4. | previously, we utilized 4-iodopyrazole (4ipzh) as a heavy atom derivative for the initial solution of the crystal structure of the nitrophorin from rhodnius prolixus, np1, where it was found to bind to the heme with the iodo group disordered in two positions. we have now determined the structure of the 4ipzh complex of np4 at ph 7.5 and find that the geometry and bond lengths at the iron center are extremely similar to those of the imidazole (imh) complex of the same protein (structure determine ... | 2004 | 14673714 |
| a miniature radioimmunoassay for melatonin for use with small samples from invertebrates. | melatonin has been identified in a number of invertebrates, but little is known of its functions or its circadian control. studies in this area are hindered by the lack of an assay for melatonin that is appropriate for use with the small sample volumes obtainable from most invertebrates and with the large numbers of sequential samples generated by circadian studies. we describe and validate a novel, miniature radioimmunoassay (ria) protocol for these purposes. sample volumes of c.50 microl were ... | 2003 | 14511991 |
| inhibition of the sapk/jnk pathway blocks the stimulatory effects of glutamine on fluid secretion by the malpighian tubules of rhodnius prolixus. | physiological levels of amino acids such as glutamine, glutamate, aspartate and proline increase the rates of fluid secretion and ion transport by serotonin-stimulated malpighian tubules (mts) of rhodnius prolixus. here, we examine the proposal that the effects of glutamine are mediated through activation of specific kinases to produce the observed increases in fluid secretion. the glutamine-dependent increase in mt fluid secretion rate was blocked by two chemically unrelated inhibitors of the s ... | 2003 | 14511822 |
| changes in the rate of co2 release following feeding in the insect rhodnius prolixus. | we describe for the first time changes in the rate of co2 release (as a surrogate of metabolic rate) in the terminal larval stage of the insect rhodnius prolixus following a blood meal and during the molt leading to the adult stage. these data are presented on a whole-animal basis as well as per gram wet and dry weight. we have also used techniques that allow us to describe the rate of release per gram of actual body tissue (i.e., removing the weight of the remaining bloodmeal in the gut and the ... | 2013 | 12905116 |
| feeding is not necessary for triggering plasticization of the abdominal cuticle in haematophagous bugs. | a simple device was used to quantify changes in the mechanical properties of the cuticle of rhodnius prolixus and triatoma infestans that take place when these insects feed, i.e., plasticization. different stimuli were presented for 1min to test for their ability to trigger plasticization. these were: a blood meal, a ringer solution meal, contact with a warm surface and thermal stimulation without such contact. our results supplant any previous hypotheses that have supposed that the presence of ... | 1998 | 12770155 |
| ion physiology of vitellogenic follicles. | the ion physiology of vitellogenic follicles from a lepidopteran (hyalophora cecropia) and a hemipteran (rhodnius prolixus) are compared. similarities that can be expected to occur in vitellogenic follicles of many other insects include: (1) gap junctions, which unite the cells of a follicle into an integrated electrical system, (2) transmembrane k(+) and h(+) gradients that account for over 60% of follicular membrane potentials, (3) absence of a cl(-) potential, (but the opening of channels to ... | 2002 | 12770038 |
| anti-diuresis in the blood-feeding insect rhodnius prolixus stål: antagonistic actions of camp and cgmp and the role of organic acid transport. | secretion of primary urine by upper malpighian tubules of the blood-sucking insect rhodnius prolixus has recently been shown to be inhibited by cyclic gmp (cgmp). in the present work, we have demonstrated that cgmp has effects antagonistic to those of camp in rhodnius tubules and have further characterized the effects of cgmp on tubular secretion. cyclic gmp inhibited secretion at all concentrations from 5x10(-6) to 10(-3)m, though this inhibition was partially or wholly reversed by large (2mm) ... | 1998 | 12769938 |
| role of the head in the ultrastructural midgut organization in rhodnius prolixus larvae: evidence from head transplantation experiments and ecdysone therapy. | studies on the effects of decapitation, head transplantation and ecdysone therapy on the ultrastructural organization of the midgut in 5th-instar larvae of rhodnius prolixus, were carried out. control insects had a typical and significant organization of the epithelial cells (mainly microvilli, extracellular membrane layers and basal portion of the epithelial cells) of the midgut (stomach and intestine) during the entire period of the experiment. however, the host larvae, when decapitated 1 day ... | 1998 | 12769937 |
| lipophorin interaction with the midgut of rhodnius prolixus: characterization and changes in binding capacity. | several classes of lipids are transported in insect hemolymph by lipophorin, a major hemolymphatic lipoprotein. the binding of lipophorin to the midgut of the hematophagous insect rhodnius prolixus was characterized in a midgut membrane preparation, using purified lipophorin radiolabelled in protein moiety ((125)i-hdlp). lipophorin specific binding to membranes achieved equilibrium after 30-40 min, was sensitive to ph, and was maximal at ph 7.0. in the presence of increasing concentrations of me ... | 2003 | 12650691 |
| on the biosynthesis of rhodnius prolixus heme-binding protein. | the biosynthesis of rhodnius prolixus heme-binding protein (rhbp), which is present in the hemolymph and oocytes of rhodnius prolixus, was investigated. fat bodies of female insects incubated in vitro with 14c-leucine were able to synthesize and secrete 14c-rhbp to the culture medium. titrtion of synthesized rhbp with hemin showed that the protein secreted by the fat bodies is bound to heme, despite the presence of apo-rhbp in the hemolymph. the sequence of the rhbp cdna encodes a pre-protein of ... | 2002 | 12530221 |
| changes in salivary nitrophorin profile during the life cycle of the blood-sucking bug rhodnius prolixus. | the insect rhodnius prolixus is a hematophagous hemipteran that has five nymphal instars. fifth instar nymphs contain, in their salivary glands, four nitrophorins which have already been described in the literature (np1, np2, np3 and np4). two new hemeproteins were isolated and partially characterized from first instar nymphs. np2, that shows an anticoagulant activity, was also identified, but np1, np3 and np4 were not found. as these new hemeproteins have amino-terminal sequences clearly homolo ... | 2003 | 12459197 |
| evidence for crf-like and kinin-like peptides as neurohormones in the blood-feeding bug, rhodnius prolixus. | in rhodnius prolixus, the rapid post-feeding diuresis is under neurohormonal control. while serotonin has been demonstrated to be a diuretic neurohormone [j exp biol 156 (1991) 557], a peptide is also known to be involved. previously, we have demonstrated the presence of corticotropin releasing factor (crf)-like and kinin-like peptides in the central nervous system (cns) of 5th instar rhodnius [j exp biol 202 (1999) 2017; peptides 22 (2001) 161]. these peptides are present in neurohemal sites of ... | 2002 | 12431735 |
| aggregation behaviour and interspecific responses in rhodnius prolixus stål. | the response to intra- and interspecific faecal assembling signals was tested in rhodnius prolixus. papers impregnated with excrement of r. prolixus induced the aggregation of larvae of this species, but also of those of triatoma infestans. however, faeces belonging to t. infestans were not able to assemble larvae of r. prolixus. on the other hand, there was no response of r. prolixus to putative chemical factors from their cuticle (footprints), in contrast to t. infestans. results are discussed ... | 2002 | 12118293 |
| oocyte fertilization triggers acid phosphatase activity during rhodnius prolixus embryogenesis. | acid phosphatase activity, previously identified in rhodnius prolixus oocytes, was studied during egg development. fertilized eggs exhibited a five fold increase of total acid phosphatase activity during the first days of development. in contrast non-fertilized oviposited eggs showed no activation of this enzyme. an optimum ph of 4.0 for pnpp hydrolysis in a saturable linear reaction and a strong inhibition by lysosomal acid phosphatase inhibitors such as naf (10 mm) and na(+)/k(+) tartrate (0.5 ... | 2002 | 12110294 |
| cyclic nucleotide-independent phosphorylation of vitellin by casein kinase ii purified from rhodnius prolixus oocytes. | in this study we show that vitellin (vt) phosphorylation in chorionated oocytes of rhodnius prolixus is completely inhibited by heparin (10 microg/ml), a classical casein kinase ii (ck ii) inhibitor. vt phosphorylation is not affected by modulators of cyclic nucleotide-dependent protein kinases such as c-amp (10 microm), h-8 (1 microm) and h-89 (0.1 microm). we have obtained a 3000-fold vt-free enriched preparation of ck ii. autophosphorylation of this enzyme preparation in the presence of (32)p ... | 2002 | 12110292 |
| rhodnius prolixus vitellin is composed of three different populations: comparison with vitellogenin. | rhodnius prolixus oocyte extracts were chromatographed on an ion exchange column in order to purify vitellin (vt). three vt heterogeneous populations were identified and named vt(1), vt(2), and vt(3) according to their order of elution from the column. the phosphate content of each population was determined, after lipid extraction, and a heterogeneous distribution was found: vt(1) being the less phosphorylated (50 mol p/mol protein) and vt(3) the heavily phosphorylated population (281 mol p/mol ... | 2002 | 12044487 |
| intracellular ion activities in malpighian tubule cells of rhodnius prolixus: evaluation of na+-k+-2cl- cotransport across the basolateral membrane. | intracellular ion activities (a(ion)) and basolateral membrane potential (vbl) were measured in malpighian tubule cells of rhodnius prolixus using double-barrelled ion-selective microelectrodes. in saline containing 103 mmol l(-1) na+, 6 mmol l(-1) k+ and 93 mmol l(-1) cl-, intracellular ion activities in unstimulated upper malpighian tubules were 21, 86 and 32 mmol l(-1), respectively. in serotonin-stimulated tubules, acl was unchanged, whereas ana increased to 33 mmol l(-1) and ak declined to ... | 2002 | 12000809 |
| contractions associated with the salivary glands of the blood-feeding bug, rhodnius prolixus: evidence for both a neural and neurohormonal coordination. | the salivary glands of the blood-feeding bug, rhodnius prolixus, are composed of a single epithelial layer of binucleate cells and a double layer of visceral muscle cells surrounding a large secretory cavity. the saliva contains substances which counteract the hemostasis of the host, and injection of saliva into the host is an essential component of successful and efficient gorging. the muscles surrounding the salivary glands of rhodnius are under polyneuronal control from the salivary nerve pro ... | 2002 | 11897388 |
| the biological activity of diuretic factors in rhodnius prolixus. | the rapid post-feeding diuresis of rhodnius prolixus is under neurohormonal control and involves the integrated activity of the crop, malpighian tubules and hindgut. one of the factors which is involved in this rapid diuresis is serotonin, however a peptide(s) is also considered to be involved. in other insects, corticotropin releasing factor (crf)-like and kinin-like, calcitonin-like peptides and cap(2b) have been demonstrated to be diuretic factors/hormones. in the present study, serotonin and ... | 2002 | 11897386 |
| fluid secretion in rhodnius upper malpighian tubules (umt): water osmotic permeabilities and morphometric studies. | we have measured the osmotic permeability of the basolateral cell membrane (poscb) and compared it with the transepithelial permeability (poste) to calculate the paracellular (posp) permeability of the upper malpighian tubules (umt) of the 5th instar of rhodnius prolixus under several experimental conditions, namely, at rest and after stimulation to secrete with 5-ht, each under control conditions (no treatment), after treatment with pcmbs, and after addition of pcmbs and dtt. secretion rate is ... | 2001 | 11891553 |
| the role of eicosanoids on rhodnius heme-binding protein (rhbp) endocytosis by rhodnius prolixus ovaries. | the participation of eicosanoids and second messengers on the regulation of rhbp endocytosis by the ovaries was investigated, using [(125)i]rhbp in experiments in vivo and in vitro. addition of pge(2) (one of the products of the cyclooxygenase pathway) decreased in vitro the uptake of rhbp by 35%. the rate of rhbp endocytosis increased in the presence of indomethacin, a potent cyclooxigenase inhibitor, up to 50% in vitro and up to 55% in vivo, thus giving support to the role of cyclooxygenase de ... | 2002 | 11891130 |
| biochemical and functional characterization of recombinant rhodnius prolixus platelet aggregation inhibitor 1 as a novel lipocalin with high affinity for adenosine diphosphate and other adenine nucleotides. | the rhodnius prolixus aggregation inhibitor 1 (rpai-1) is a novel blood-sucking salivary molecule that binds to adp and attenuates platelet aggregation. in this report, we determine the binding constants and specificity of rpai-1 for adenine nucleotides and its functional significance. by the hummel-dreyer method of equilibrium gel filtration, we show that rpai-1 binds adp with a k(0.5) of 48.6 plus minus 12.2 nm. rpai-1 also displays high-affinity binding to atp, amp, ado, ap4a, and alpha,beta ... | 2002 | 11888300 |
| resonance raman spectroscopic study of nitrophorin 1, a nitric oxide-binding heme protein from rhodnius prolixus, and its nitrosyl and cyano adducts. | the resonance raman (rr) spectra of nitrophorin 1 (np1) from the saliva of the blood-sucking insect rhodnius prolixus, in the absence and presence of nitric oxide (no) and in the presence of cyanide (cn(-)), have been studied. the np1 displayed rr spectra characteristic of six-coordinate high-spin (6chs) ferric heme at room temperature and six-coordinate low-spin heme (6cls) at low temperature (77 k). no and cn(-) each bind to fe(iii), both ligands forming 6cls complexes with np1. the fe(iii)-no ... | 2001 | 11716723 |
| effects of some lignans and neolignans on the development and excretion of rhodnius prolixus. | the effects of six lignans and neolignans as inhibitors of ecdysis and on the water balance in fourth-instar larvae of rhodnius prolixus were studied by oral, topical and continuous contact treatments. the main results may be summarised as follows: (i) burchellin, pinoresinol, sesamin, licarin a and nordihydroguaiaretic acid (ndga) did not cause feeding inhibition at doses of 100 micrograms/ml blood; podophyllotoxin had no antifeedant effect but caused a high moulting inhibition and significant ... | 2000 | 11449462 |
| a quantum chemical survey of metalloporphyrin-nitrosyl linkage isomers: insights into the observation of multiple feno conformations in a recent crystallographic determination of nitrophorin 4. | using density functional theory-based geometry optimizations, we have searched for eta(1)-no, eta(1)-on (isonitrosyl), and eta(2)-no (side-on bound no) linkage isomers of a number of metalloporphyrin-no complexes, m(por)(no)(l), where por = porphinato dianion, m = mn(ii), fe(ii), fe(iii), ru(ii), ru(iii), co(ii), and rh(ii), and l = no ligand, sme, ph, and imidazole. the eta(1)-no isomer had the lowest energy in all cases, and the isonitrosyl isomer was also located as a higher energy potential ... | 2001 | 11403599 |
| [bioactive molecule supporting blood feeding: unique activities from the salivary glands in the kissing bug, rhodnius prolixus]. | | 2001 | 11268644 |
| the distribution of a kinin-like peptide and its co-localization with a crf-like peptide in the blood-feeding bug, rhodnius prolixus. | rhodnius prolixus, a blood-feeding hemipteran insect, ingests large meals which are followed by rapid diuresis to eliminate excess water and salt. in rhodnius, serotonin and an unidentified peptide(s) [33,34] have been shown to act as neurohormonal diuretic factors. in other insects, two families of diuretic peptides, the corticotropin releasing factor (crf)-like, and kinin peptides [9], have been identified and sequenced. recently, we demonstrated the presence of a crf-like diuretic peptide in ... | 2001 | 11179809 |
| transepithelial potential in malpighian tubules of rhodnius prolixus: lumen-negative voltages and the triphasic response to serotonin. | previous studies of the malpighian tubules of rhodnius reported lumen-negative values of transepithelial potential (tep), and a characteristic triphasic change in tep in response to stimulation of tubule fluid secretion by serotonin. tep was measured using the ramsay technique, in which electrodes are positioned in bathing and secreted fluid droplets for tubules isolated under paraffin oil. the validity of this method of tep measurement has been questioned on the grounds that, in tubules of some ... | 2001 | 11166306 |
| effects of lignoids on a hematophagous bug, rhodnius prolixus: feeding, ecdysis and diuresis. | the effects of lignoids on feeding, ecdysis and diuresis in fourth-instar larvae of rhodnius prolixus (hemiptera) were investigated. up to 100 microg/ml burchellin, podophyllotoxin, pinoresinol, sesamin, licarin a, or nordihydroguaiaretic acid (ndga) in the diet did not induce antifeedant effects. pinoresinol and ndga significantly inhibited ecdysis. in experiments in vivo, burchellin and podophyllotoxin reduced the production of urine after feeding. 5-hydroxytryptamine (5-ht), a diuretic hormon ... | 2000 | 11130672 |
| sulfated glycosaminoglycans from ovary of rhodnius prolixus. | we have characterized sulfated glycosaminoglycans from ovaries of the blood-sucking insect rhodnius prolixus, and determined parameters of their synthesis and distribution within this organ by biochemical and histochemical procedures. the major sulfated glycosaminoglycan is heparan sulfate while chondroitin 4-sulfate is a minor component. these glycosaminoglycans are concentrated in the ovarian tissue and are not found inside the oocytes. besides this, we detected the presence of a sulfated comp ... | 2001 | 11102832 |
| rhodnius prolixus: effects of the neolignan burchellin on in vivo and in vitro diuresis. | supplementation of blood with the neolignan burchellin (100 microg/ml), a compound from the arboreous lauraceae aniba burchelli, affected the course of excretion of fourth-instar larvae of rhodnius prolixus, especially directly after feeding, and reduced the volume of feces/urine excreted within 6 h of feeding to about 18% and, on the simultaneous addition of the diuretic hormone analogue 5-hydroxytryptamine (5-ht), about 71% of that observed in untreated bugs. in the latter, 5-ht induced a sign ... | 2000 | 11002977 |
| kinetics and equilibria in ligand binding by nitrophorins 1-4: evidence for stabilization of a nitric oxide-ferriheme complex through a ligand-induced conformational trap. | nitrophorins 1-4 (np1-4) are ferriheme proteins from the blood-sucking insect rhodnius prolixus that transport nitric oxide (no) to the victim, sequester histamine, and inhibit blood coagulation. here, we report kinetic and thermodynamic analyses for ligand binding by all four proteins and their reduction potentials. all four undergo biphasic association and dissociation reactions with no. the initial association is fast (1.5-33 microm(-)(1) s(-)(1)) and similar to that of elephant metmyoglobin. ... | 2000 | 10956000 |
| the crystal structure of nitrophorin 2. a trifunctional antihemostatic protein from the saliva of rhodnius prolixus. | nitrophorin 2 (np2) (also known as prolixin-s) is a salivary protein that transports nitric oxide, binds histamine, and acts as an anticoagulant during blood feeding by the insect rhodnius prolixus. the 2.0-a crystal structure of np2 reveals an eight-stranded antiparallel beta-barrel containing a ferric heme coordinated through his(57), similar to the structures of np1 and np4. all four rhodnius nitrophorins transport no and sequester histamine through heme binding, but only np2 acts as an antic ... | 2000 | 10884386 |
| synthesis of vitellogenin by the follicle cells of rhodnius prolixus. | the synthesis and secretion of vitellogenin by the ovary of rhodnius prolixus was investigated. using whole ovary or epithelial cells isolated from follicles of different sizes, it is shown that the follicle cells are a site of synthesis for this protein in the ovary. the ovaries or follicle cells were incubated in vitro with [(35)s]-methionine or (32)pi and the secretion of newly synthesized ovarian vitellogenin (o-vg) was estimated by the radioactivity associated with the immunoprecipitate or ... | 2000 | 10844247 |
| the insect salivary protein, prolixin-s, inhibits factor ixa generation and xase complex formation in the blood coagulation pathway. | prolixin-s is a salivary anticoagulant of the blood-sucking insect, rhodnius prolixus, and known as an inhibitor of the intrinsic xase. we report here its inhibitory mechanisms with additional important anticoagulation activities. we found prolixin-s specifically bound to factor ix/ixa in the presence of ca(2+) ions. light scattering and surface plasmon resonance studies showed that prolixin-s interfered with factor ix/ixa binding to the phospholipid membrane, indicating that prolixin-s inhibit ... | 2000 | 10692472 |
| fatty acid incorporation by rhodnius prolixus midgut. | [(14)c]oleic acid injected into the hemocoel of rhodnius prolixus females was shown to rapidly associate with lipophorin particles. half of the lipophorin-associated [(14)c]oleic acid was transferred in about 5 min to different organs, but the midgut was the main organ to take it up on day 10 after a blood meal. the rate of [(14)c]oleic acid incorporation by the midgut was high up to 15 min after injection and then declined. the [(14)c]oleic acid incorporated by the midgut was found in phospholi ... | 2000 | 10685097 |
| adenosine modulates the (na(+)+k(+))atpase activity in malpighian tubules isolated from rhodnius prolixus. | the role of adenosine on regulation of the (na(+)+k(+))atpase activity present in the malpighian tubules isolated from rhodnius prolixus was investigated. adenosine decreases the (na(+)+k(+)) atpase specific activity by 88%, in a dose-dependent manner, with maximal effect at a concentration of 10(-9) m. this effect was mimicked by n(6)-cyclohexyladenosine (cha) at 10(-8) m, an agonist for a(1) adenosine receptor, and was reversed by 10(-9) m 8-cyclopentyl-1,3-dipropylxanthine (dpcpx), an antagon ... | 2000 | 10644971 |
| a new factor xa inhibitor (lefaxin) from the haementeria depressa leech. | the salivary complex of the leech haementeria depressa produces potent anticoagulant components. among them, a protein named lefaxin inhibits factor xa (fxa). lefaxin was purified to homogeneity from dissected salivary complexes by gel filtration in sephadex g-150 followed by two ion exchange chromatography steps in mono-q. inhibition of fxa by lefaxin was demonstrated by the inhibition of its amidolytic activity, measured with chromogenic substrate s-2765 (apparent k(i) of 4 nm), and of its abi ... | 1999 | 10595640 |
| functional binding of a vertebrate hormone, l-3,5,3'-triiodothyronine (t3), on insect follicle cell membranes. | a vertebrate hormone, l-3,5,3'-triiodothyronine (t3), induces volume reduction in the follicle cells of locusta migratoria and rhodnius prolixus. the effect of t3 on locust follicle cells is inhibited by ouabain and by antibodies raised against a membrane binding protein for juvenile hormone (jh). [125i]-t3 binds to membrane preparations of vitellogenic follicles in a specific and saturable fashion, with a kd in the low nanomolar range. t3 and jh iii exhibited equivalent abilities to compete for ... | 1999 | 10528413 |
| extracellular glutathione peroxidase from the blood-sucking bug, rhodnius prolixus | glutathione peroxidase (gpx) activity was measured in several tissues of the blood-sucking bug, rhodnius prolixus. in contrast to the pattern found in vertebrates, where gpx is predominantly intracellular, the highest levels of this enzyme in rhodnius were found in the hemolymph. the hemolymph glutathione-dependent peroxidase accepted both h(2)o(2) and t-butyl hydroperoxide as substrates. this fact, together with the absolute glutathione dependence, inhibition by mercaptosuccinate, insensitivity ... | 1999 | 10421891 |
| daily rhythm of responsiveness to prothoracicotropic hormone in prothoracic glands of rhodnius prolixus | the synthesis of ecdysteroids by the prothoracic glands (pgs) of rhodnius prolixus occurs with a circadian rhythm throughout most of larval-adult development. this rhythm is generated by a circadian oscillator within the pgs. the principle regulator of the pgs is the cerebral neuropeptide prothoracicotropic hormone (ptth), which is also known to be released with a circadian rhythm, but it has not been shown that these daily releases of ptth are detected by the pgs. the present report examines th ... | 1999 | 10398334 |
| the distribution of a crf-like diuretic peptide in the blood-feeding bug rhodnius prolixus. | 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-li ... | 1999 | 10393817 |
| kinetic analysis on nitric oxide binding of recombinant prolixin-s, a nitric oxide transport protein from the bloodsucking bug, rhodnius prolixus. | kinetics of the no binding and removal reaction of recombinant prolixin-s (rprolixin-s) were analyzed using stopped-flow spectrophotometry. the reaction was observed as a biphasic process. the rate constant of the fast phase increased linearly as no concentration increased. the rate constant at the slow phase increased as no concentrations increased at low no concentration, then reached a plateau at high no concentration. these no dependencies of the reaction are characteristic of a bimolecular ... | 1999 | 10350624 |
| protein phosphorylation during rhodnius prolixus embryogenesis: protein kinase casein kinase ii activity. | protein kinase casein kinase ii (ck ii) activity was assayed during rhodnius prolixus embryogenesis. vitellin (vt) is the main endogenous substrate during the whole development. it is maximally phosphorylated at the third day of embryogenesis by ck ii and then its phosphorylation decreases to a basal level by the time of first instar eclosion. when dephosphorylated casein was used as an exogenous substrate a different profile of enzyme activity was obtained. ck ii activity increases on day 1 aft ... | 1999 | 10319435 |
| urate synthesis in the blood-sucking insect rhodnius prolixus. stimulation by hemin is mediated by protein kinase c. | hemin is a catalyst of the formation of reactive oxygen species. we proposed that hematophagous insects are exposed to intense oxidative stress because of hemoglobin hydrolysis in their midgut (petretsky, m. d., ribeiro, j. m. c., atella, g. c., masuda, h., and oliveira, p. l. (1995) j. biol. chem. 270, 10893-10896). we have shown that hemin stimulates urate synthesis in the blood-sucking insect rhodnius prolixus (graça-souza, a. v., petretsky, j. h., demasi, m., bechara, e. j. h., and oliveira, ... | 1999 | 10092654 |
| ouabain-insensitive na(+)-atpase activity of malpighian tubules from rhodnius prolixus. | in the present paper, we show the existence of a furosemide-sensitive na(+)-stimulated, mg(2+)-dependent atpase activity in cell lysates of malpighian tubular cells from rhodnius prolixus, which could be the biochemical expression of the na(+)-pump. the main characteristics of this activity are: (1) k0.5 for na+ = 1.49 +/- 0.18 mm, (2) vmax = 2.8 +/- 0.1 nmol inorganic orthophosphate (pi).mg prot-1.min-1, (3) it is fully abolished by 2 mm furosemide, (4)it is insensitive to ouabain concentration ... | 1998 | 9787771 |
| characterization and cdna cloning of a hemoprotein in the salivary glands of the blood-sucking insect, rhodnius prolixus. | three major red hemoproteins, named rpsg i, ii (identical with prolixin-s) and iii, in the salivary glands of the blood-sucking insect, rhonius prolixus, show homology in n-terminal amino acid (aa) sequences, and are immunologically related. we focussed on one of these proteins, rpsg-i, in this paper. rpsg-i in fresh salivary gland extract was separated into two components (ia and ib) by isoelectric focussing gel electrophoresis. absorption spectra of rpsg-ia and ib showed soret peaks at 400 nm ... | 1998 | 9654741 |
| the origin of rhodnius prolixus in central america. | | 1998 | 9580149 |
| crystal structures of a nitric oxide transport protein from a blood-sucking insect. | the nitrophorins are heme-based proteins from the salivary glands of the blood-sucking insect rhodnius prolixus that deliver nitric oxide gas (no) to the victim while feeding, resulting in vasodilation and inhibition of platelet aggregation. the nitrophorins also bind tightly to histamine, which is released by the host to induce wound healing. here we present three crystal structures of nitrophorin 1 (np1): bound to cyanide, which binds in a manner similar to no (2.3 a resolution); bound to hist ... | 1998 | 9546222 |
| rhythmic steroidogenesis by the prothoracic glands of the insect rhodnius prolixus in the absence of rhythmic neuropeptide input: implications for the role of prothoracicotropic hormone. | circadian rhythms have been reported both in the synthesis of the insect steroid moulting hormones (ecdysteroids) by the prothoracic glands (pgs) and in the release of the cerebral neuropeptide, prothoracicotropic hormone (ptth). ptth is known to activate steroidogenesis early in development, but the function of continued rhythmic release is unknown. the functional relationship between these two hormonal rhythms was examined. we report the properties of the rhythm of steroidogenesis by pgs of an ... | 1997 | 9405112 |
| anti-diuresis in the blood-feeding insect rhodnius prolixus stål: the peptide cap2b and cyclic gmp inhibit malpighian tubule fluid secretion. | 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 cyc ... | 1997 | 9316268 |
| role of phospholipids in the protein stability of an insect lipoprotein, lipophorin from rhodnius prolixus. | lipophorin (lp) is the major lipoprotein in insect hemolymph. the structural organization proposed for lp is basically the same as that suggested for vertebrate lipoproteins, consisting of a hydrophobic core containing neutral lipids, stabilized in the aqueous environment by surrounding polar moieties of protein and phospholipids at the particle surface. after complete removal of phospholipids from lp by phospholipase a2, the particle remains soluble [gondim, k. c., atella, g. c., kawooya, j. k. ... | 1997 | 9287164 |
| kcl reabsorption by the lower malpighian tubule of rhodnius prolixus: inhibition by cl(-) channel blockers and acetazolamide. | iono- and osmoregulation by the blood-feeding hemipteran rhodnius prolixus involves co-ordinated actions of the upper and lower malpighian tubules. the upper tubule secretes ions (na(+), k(+), cl(-)) and water, whereas the lower tubule reabsorbs k(+) and cl(-) but not water. the extent of kcl reabsorption by the lower tubule in vitro was monitored by ion-selective microelectrode measurement of cl(-) and/or k(+) concentration in droplets of fluid secreted by malpighian tubules isolated under oil. ... | 1997 | 12769977 |
| analysis of epithelial transport by measurement of k+, cl- and ph gradients in extracellular unstirred layers: ion secretion and reabsorption by malpighian tubules of rhodnius prolixus | summary the ph and concentrations of k+ and cl- in the unstirred layer (usl) associated with the basolateral surfaces of the upper and lower malpighian tubules of rhodnius prolixus were measured using extracellular ion-selective microelectrodes. when stimulated with 5-hydroxytryptamine (5-ht) in vitro, the upper malpighian tubule secretes na+, k+, cl- and water at high rates; the lower malpighian tubule reabsorbs k+ and cl- but not water. concentrations of k+ and cl- in the unstirred layer of th ... | 1997 | 9319533 |
| k+ reabsorption by the lower malpighian tubule of rhodnius prolixus: inhibition by ba2+ and blockers of h+/k+-atpases | active k+ reabsorption by the lower malpighian tubule of the blood-feeding hemipteran rhodnius prolixus does not involve the amiloride-sensitive k+/h+ exchangers or v-type h+-atpases implicated in secretion of ions from haemolymph to lumen in the upper tubule. amiloride, n-ethylmaleimide, 4-chloro-7-nitrobenzo-2-oxa-1,3-diazol and bafilomycin a1 inhibit haemolymph-to-lumen secretion of na+ and k+ by the upper malpighian tubule, but have little or no effect on lumen-to-haemolymph reabsorption of ... | 1997 | 9317503 |
| unipolar microtubule array is directly involved in nurse cell-oocyte transport. | the telotrophic ovariole of rhodnius prolixus is richly endowed with microtubules (mts). an extensive, stable array of mts packs the trophic core and trophic cords which link the nurse cell compartments to the growing oocytes. this system is excellent to study mt-based transport as the mts are believed to play a role in transport of nurse cell-produced mitochondria, ribosomes, and mrnas to the oocytes. we investigated mt polarity and molecular mt motors in this unidirectional transport system. h ... | 1997 | 9096957 |
| urate protects a blood-sucking insect against hemin-induced oxidative stress. | urate at high concentrations (up to 5 mm) is found in the hemolymph of the blood-sucking bug, rhodnius prolixus. increased urate levels are observed in the days following a blood meal. injecting hemin into the hemocoel increases both urate titer and tbars formation in the hemolymph. the urate response to hemin injection seems to arise from increased synthesis by the fat body as urate secretion by this organ is stimulated in vitro by incubation with hemin, and markedly counteracted by allopurinol ... | 1997 | 8958146 |
| cdna cloning, expression and characterization of nitric-oxide synthase from the salivary glands of the blood-sucking insect rhodnius prolixus. | rhodnius prolixus, a blood-sucking bug, is a unique insect that is known to produce nitric oxide (no) in the salivary glands to use as a vasodilator for blood sucking. we report here the cloning of the no synthase (nos) cdna from these salivary glands and its expression in a baculovirus system. this cdna encodes a protein of 1174 amino acids with a calculated molecular mass of 132,331 da. the primary structures of mammalian nos, including the putative cofactor-recognition sites for heme, tetrahy ... | 1996 | 9022713 |
| isolation of a calcium-binding phosphoprotein from the oocytes and hemolymph of the blood-sucking insect rhodnius prolixus. | a novel calcium-binding phosphoprotein was isolated from the oocytes of the blood-sucking bug rhodnius prolixus. this protein exhibits an apparent molecular mass of 18 kda on gel filtration, but migrates as an 8-kda band on n-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine/sds-polyacrylamide gels. it has a high content of serine (24% of the total number of residues), and phosphoserine is the sole amino acid phosphorylated in vivo. a similar protein was partially purified from the hemolymph. it re ... | 1996 | 8939975 |
| salivary thiol oxidase activity of rhodnius prolixus. | cysteine and other thiol compounds can accelerate the unloading of nitric oxide (no) from salivary nitrosyl-nitrophorins of the blood sucking bug rhodnius prolixus. the dependence of no unloading on cysteine concentration is biphasic, showing a maximum between 0.5 and 1 mm cysteine. the proposed mechanism of action for the unloading is a series of reactions where cysteine (at low concentrations) reacts with the heme group of nitrophorins to form cystine and superoxide. the superoxide then reacts ... | 2013 | 9014335 |
| the insect neuropeptide prothoracicotropic hormone is released with a daily rhythm: re-evaluation of its role in development. | prothoracicotropic hormone (ptth) is the central cerebral neurohormone in insect development. its release has been believed for decades to be confined to one (or two) critical moments early in each developmental stage at which time it triggers prolonged activation of the prothoracic glands to synthesize and release the steroid molting hormones (ecdysteroids), which elicit developmental responses in target tissues. we used an in vitro assay for ptth released from excised brains of the bug rhodniu ... | 1996 | 11607650 |
| circadian regulation of a daily rhythm of release of prothoracicotropic hormone from the brain retrocerebral complex of rhodnius prolixus (hemiptera) during larval-adult development. | a daily rhythm of release of prothoracicotropic hormone (ptth) has been reported throughout most of larval-adult development in rhodnius prolixus. ptth released by explanted brain-retrocerebral complexes was quantified using an in vitro bioassay in which the ptth released into the incubation medium was assayed by its ability to stimulate ecdysteroid synthesis in arrhythmic prothoracic glands (pgs). the present article employs this assay to reveal that the daily rhythm of ptth release is under ci ... | 1996 | 8860316 |
| purification, characterization and cdna cloning of a novel anticoagulant of the intrinsic pathway, (prolixin-s) from salivary glands of the blood sucking bug, rhodnius prolixus. | the salivary glands of the blood sucking insect, rhodnius prolixus, have an anticoagulant, prolixin-s, which was reported as a specific inhibitor of intrinsic coagulant pathway. prolixin-s was purified from the salivary glands extract of rhodnius prolixus by gel filtration and anion exchange hplc by assaying prolongation of activated partial thromboplastin time (aptt). the isolated protein specifically inhibited factor ixa-catalyzed activation of factor x in the presence of ca2+ and phospholipid ... | 1996 | 8743181 |
| the paracellular channel for water secretion in the upper segment of the malpighian tubule of rhodnius prolixus. | lumen to bath j12/c1 and bath to lumen j21/c2 fluxes per unit concentration of 19 probes with diameters (dm) ranging from 3.0-30.0 a (water, urea, erythritol, mannitol, sucrose, raffinose and 13 dextrans with dm 9.1-30.0 a) were measured during volume secretion (jv) in the upper segment of the malpighian tubule of rhodnius by perfusing lumen and bath with 14c or 3h-labeled probes. jnet = (j12/c1-j21/c2) was studied as a function of jv.jv was varied by using different concentrations of 5-hydroxy ... | 1995 | 8747555 |
| purification and characterization of prolixin s (nitrophorin 2), the salivary anticoagulant of the blood-sucking bug rhodnius prolixus. | the salivary anticoagulant of the blood-sucking bug rhodnius prolixus was purified to homogeneity using a protocol consisting of weak cation-exchange, deae, hydrophobic-interaction and octadecyl reverse-phase chromatography, yielding a protein with the same n-terminal sequence as nitrophorin 2, one of the four no haem protein carriers present in the salivary glands of rhodnius with a molecular mass of 19689 da [d. champagne, r.h. nussenzveig and j.m.c. ribeiro, (1995) j. biol. chem. 270, in the ... | 1995 | 7755571 |
| antioxidant role of rhodnius prolixus heme-binding protein. protection against heme-induced lipid peroxidation. | heme in aqueous solutions actively promotes free radical reactions leading to degradation of biological molecules. the blood-sucking insect rhodnius prolixus has a heme-binding protein (rhbp) in its hemolymph (oliveira, p.l., kawooya, j.k., ribeiro, j.m.c., meyer, t., poorman, r., alves, e.w., walker, f., padovan, g.j., and masuda, h. (1994) j. biol. chem. 270, 10897-10901. here we show that this protein inhibits heme-dependent peroxidation of both linolenic acid liposomes and lipophorin, the ma ... | 1995 | 7738029 |
| nitric oxide loading of the salivary nitric-oxide-carrying hemoproteins (nitrophorins) in the blood-sucking bug rhodnius prolixus. | the salivary glands of the blood-sucking bug rhodnius prolixus are formed by a single layer of binucleated epithelial cells surrounded by a double layer of transversely oriented smooth muscle cells. the epithelial cells are rich in rough endoplasmic reticulum and mitochondria and have abundant microvillar projections towards the gland lumen. this cell layer surrounds a relatively large cavity where abundant secretory material is stored. epithelial cells produce an intense and generalized nadph d ... | 1995 | 8627144 |
| purification, partial characterization, and cloning of nitric oxide-carrying heme proteins (nitrophorins) from salivary glands of the blood-sucking insect rhodnius prolixus. | four nitric oxide (no)-carrying proteins have been isolated from salivary glands of the blood-sucking insect rhodnius prolixus. these have been given the collective name "nitrophorins," and individual proteins are designated np1-np4 in order of their relative abundance in the glands. all four reversibly bind no; spectral shifts associated with no binding indicate the interaction of no with an fe(iii) heme. physical properties, amino acid composition, and amino-terminal sequences of the nitrophor ... | 1995 | 7721773 |
| the feeding stimulus in rhodnius prolixus is transmitted to the brain by a humoral factor | neurosecretory cells in the brain of rhodnius prolixus are known to be the source of an ovulation hormone released at feeding. they were selected to test the hypothesis that feeding brings about the release of another hormone in the abdomen which is transported forward to activate the neuroendocrine axis in the brain, and that severing the aorta interferes with this transport. these cells have previously been shown to exhibit an increase in action potential frequency at the time of release of th ... | 1995 | 9318904 |
| immunogold labelling of serotonin-like and fmrfamide-like immunoreactive material in neurohaemal areas on abdominal nerves of rhodnius prolixus. | the ultrastructure of neurohaemal areas on abdominal nerves of the blood-sucking bug rhodnius prolixus was investigated. four types of axon terminals were found, distinguished by the morphology of their neurosecretory granules. by use of post-embedding immunogold labelling, granules in type i axon terminals were shown to contain serotonin-like immunoreactive material, and granules in type ii axon terminals were shown to contain fmrfamide-like immunoreactive material. there was no colocalization ... | 1994 | 7954695 |
| protein phosphorylation in rhodnius prolixus oocytes: identification of a type ii casein kinase. | a protein kinase activity in chorionated oocytes of rhodnius prolixus phosphorylates in vitro vitellin (vt), the major yolk protein. phosphatase inhibitors including naf, sodium vanadate, beta-glycerophosphate and okadaic acid did not alter the protein phosphorylation profile to a visible extent. among the exogenous protein substrates tested, casein was readily phosphorylated, but histones were not. several different protein kinase activators, including camp, ca2+ plus calmodulin, ca2+ plus diol ... | 1993 | 11446384 |
| ionic basis of bioelectric currents during oogenesis in an insect. | transmembrane bioelectric currents around insect ovaries are well documented but as yet poorly understood. in the present study we describe the ionic basis of such currents around the telotrophic ovariole of rhodnius prolixus using a two-dimensional vibrating probe and ion-substituted media and inhibitors. current efflux from the base and apex of the terminal follicle is carried by electrogenic na+ transport, and the return circuit over the middle of the terminal follicle is the result of na+ in ... | 1993 | 7688328 |
| dynamics of the oocyte cortical cytoskeleton during oogenesis in rhodnius prolixus. | the oocyte cortex undergoes dramatic changes during oogenesis in rhodnius prolixus. despite numerous studies examining oogenesis in the telotrophic ovariole, none has investigated the ultrastructural details of the oocyte cortex, in particular, the lateral cortical cytoskeleton. indirect immunofluorescent staining of sections, rhodamine phalloidin staining of whole mounts and scanning and transmission em of permeabilized and unpermeabilized preparations revealed the dynamic changes of the oocyte ... | 1993 | 18621240 |
| cdna cloning and expression of rhodnius prolixus vitellogenin. | it was shown that rhodnius prolixus vitellogenin (vg) is synthesized as precursors of 205 and 190 kda. each vg subunit is antigenically related to a domain in the precursor molecules. since vg has been previously detected in r. prolixus male adults, protein synthesis by fat bodies from 5th instar male nymphs was investigated and no vg synthesis could be detected. also, a 6.1 kb rna is present in female adults but not in 5th instar male nymphs. therefore, cdnas from female adult and 5th instar ma ... | 1993 | 8508188 |
| reversible binding of nitric oxide by a salivary heme protein from a bloodsucking insect. | the bloodsucking bug rhodnius prolixus has a salivary vasodilator, previously characterized as a nitrovasodilator, with salivary smooth muscle-relaxing and antiplatelet activity. rhodnius salivary glands are bright red owing to the abundance of heme proteins. electron paramagnetic resonance and optical spectroscopic experiments indicated that the salivary vasodilator is a nitrosylheme protein with an fe(iii) heme that binds nitric oxide (no) reversibly. dilution of the protein in neutral ph prom ... | 1993 | 8386393 |
| the regulation of haemolymph potassium activity during initiation and maintenance of diuresis in fed rhodnius prolixus. | the blood-sucking insect rhodnius prolixus rapidly eliminates a na(+)-rich k(+)-poor urine after its large meals. k(+)-rich fluid is first secreted by the upper malpighian tubules and passes to the lower tubules where most of the potassium is reabsorbed. during the initial stimulation of the tubules, the lower tubules must be activated first to avoid loss of potassium. the major element in this is that they respond more rapidly than do the upper tubules to particular hormonal concentrations rath ... | 1993 | 8486999 |
| spatial and temporal transcellular current patterns during oogenesis. | we have used the two-dimensional vibrating probe to examine spatial and temporal patterns in the transcellular current flow around telotrophic ovarioles of the insect rhodnius prolixus. we demonstrate a dynamic pattern of currents which correlates with various stages of vitellogenesis. asymmetries exist in the radial current pattern around intact ovarioles, particularly around the terminal follicle, and may correlate with early developmental axes. the extra-cellular current pattern is largely re ... | 1992 | 1397687 |
| insulin-like immunoreactivity and molting in rhodnius prolixus. | two prominent cells were observed when fifth stage rhodnius female larval brains were stained with anti-insulin serum. the staining intensity of these cells varied during the instar, being lowest on day 1 and days 5 and 6 after feeding. injection of anti-insulin serum into 5th stage larvae immediately after feeding and on days 4 and 5 in females and on days 5 and 6 in males prevented molting. control antiserum had no effect on the molting process. injections at other times during the instar had ... | 1992 | 1601272 |
| cell proliferation and rearrangement in the development of the malpighian tubules of the hemipteran, rhodnius prolixus. | the pattern of cell activities resulting in the generation of a simple tubular epithelium, the malpighian tubules of rhodnius prolixus, is examined during embryogenesis. the anlage of the tubules is shown to be of ectodermal origin. an evolving pattern of cycling cells in the primordia is revealed using the immunocytochemical localization of a substituted nucleotide, budr. a cell unique to each tubule is shown not to enter the cell cycle but to be required for the proliferation of the remaining ... | 1992 | 1551481 |
| in vitro photosensitivity of ecdysteroid synthesis by prothoracic glands of rhodnius prolixus (hemiptera). | the effects of light:dark transitions on in vitro ecdysteroid synthesis by prothoracic glands (pgs) of male fifth instar rhodnius have been studied. pgs were rendered arrhythmic by prolonged maintenance of the animals in continuous light (ll). pgs were then explanted and ecdysteroid synthesis was measured hourly by radioimmunoassay. pgs were transferred from ll to darkness at various times after explanation and hourly synthesis was measured for several more hours. transfer of pgs to darkness in ... | 1992 | 1505717 |
| role of phospholipids in the lipophorin particles of rhodnius prolixus. | the lipophorin of rhodnius prolixus metabolically labelled with 32p exclusively in the phospholipid moiety was purified on a potassium bromide gradient and treated with phospholipase a2 in the presence of an excess of fatty acid-free albumin. the treatment completely removed the phospholipids from the particles and generated [32p]-lysophosphatidylcholine, [32p]-lysophosphatidylethanolamine, and free fatty acids that remained bound to albumin. the phospholipid-depleted lipophorin particles remain ... | 1992 | 1504321 |
| identification of yolk platelet-associated hydrolases in the oocytes of rhodnius prolixus. | the yolk platelets from rhodnius prolixus, a blood-sucking bug, are composed mostly of vitellin and here are shown to contain at least two hydrolytic enzymes, a phosphatase and a cathepsin d-like proteinase. both the proteinase and the phosphatase have an acid ph optimum. no hydrolytic activity was observed under alkaline or neutral conditions. among several proteinase inhibitors tested, only pepstatin could abolish vitellin breakdown in vitro. the proteinase appears to be bound to the yolk plat ... | 1992 | 1286200 |
| circadian regulation of synthesis of ecdysteroids by prothoracic glands of the insect rhodnius prolixus: evidence of a dual oscillator system. | rhythmic synthesis of moulting hormones (ecdysteroids) by prothoracic glands (pgs) of the insect rhodnius prolixus during the last larval instar was studied in vitro following explantations every 4-5 hr for up to 96 hr. ecdysteroid synthesis was measured by radioimmunoassay as the quantity of ecdysteroid produced during 4 hr in vitro. a massive daily rhythm is seen, with synthesis at night being three- to fivefold higher than during the day. this rhythm of ecdysteroid synthesis by pgs free-runs ... | 1991 | 1879670 |