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PubMed1985

Biogenic amine uptake by nerve cords from the American cockroach and the influence of amidines on amine uptake and release.

Uptake of 5-hydroxytryptamine (5-HT) by isolated whole nerve cords of the American cockroach, Periplaneta americana (L.), involved a dual component system, with one component consisting of rapid active uptake and the other of passive diffusion. Using high performance liquid chromatography with electrochemical detection, it was shown that nerve cords contained 5-HT levels of about 350 ng/g and an equivalent amount of 5-hydroxyindoleacetic acid (5-HIAA), a 5-HT metabolite not previously reported in cockroach nerve cords. Amidines had no discernable effect on uptake of 5-HT or octopamine by nerve cords or on endogenous levels of 5-HT and 5-HIAA in cords.

Amidines↗
PubMed1986

Primary structure and synthesis of a blocked myotropic neuropeptide isolated from the cockroach, Leucophaea maderae.

A peptide which stimulates the contractile activity of the cockroach hindgut was isolated from head extracts of the cockroach, Leucophaea maderae. The inability of aminopeptidase M to degrade the peptide and the presence of glutamic acid in the hydrolysate suggested N-terminal blocking by pyroglutamic acid. The N-terminal pGlu was removed enzymatically and the unblocked fragment was sequenced with an automated gas-phase peptide sequencer. The structure determined (pGlu-Thr-Ser-Phe-Thr-Pro-Arg-Leu-NH2) was synthesized and shown to be both chemically and biologically identical with the natural product.

Amino Acid Sequence↗
PubMed1987

The action of two classes of pyrethroids on the inhibition of brain Na-Ca and Ca + Mg ATP hydrolyzing activities of the American cockroach.

Ca2+-stimulated ATP hydrolyzing activities (i.e. Na-Ca ATP hydrolysis and Ca + Mg ATP hydrolysis) measured in cockroach brain tissue were highly sensitive to the action of pyrethroid insecticides under in vitro conditions. Non-cyano-containing pyrethroids inhibited Na-Ca ATP hydrolysis to a greater extent than their cyano-containing counterparts. The reverse is true for pyrethroid action on Ca + Mg ATP hydrolysis. Nonmitochondrial Ca + Mg ATP hydrolysis of disrupted synaptosomes was the most sensitive activity examined. Ca2+-stimulated ATP hydrolyzing activities were inhibited in cockroaches poisoned by permethrin in vivo. In vivo poisoning occurred in the presence of a similar amount of bound [14C]permethrin which had been determined to cause a substantial amount of inhibition to Ca2+-stimulated ATP hydrolyzing activities in vitro.

Adenosine Triphosphatases↗
PubMed1989

Effects of AF64A on cholinergic neurotransmission in the sixth abdominal ganglion of the cockroach.

1. The effects of ethylcholine mustard aziridinium ion (AF64A) on the cholinergic neurotransmission in the sixth abdominal ganglion of the cockroach were studied electrophysiologically and morphologically. 2. The pre- and post-synaptic compound action potentials (CAPs) elicited via electrical stimulation of the presynaptic fibers were recorded extracellularly. 3. The amplitude of both CAPs was depressed by AF64A (50-400 microM) in a concentration- and time-dependent manner. 4. At a high concentration, they were abolished but 100 microM of carbachol still evoked the postsynaptic event. 5. Electron microscopic observation of AF64A-treated ganglia showed that nerve terminals containing small lucent vesicles could not be observed but those containing dense core or large granular vesicles changed only slightly in shape. 6. These results suggest that AF64A is selectively neurotoxic for the presynaptic cholinergic neurons in the sixth abdominal ganglion of the cockroach.

Abdomen↗
PubMed1990

The action of dopamine receptor antagonists on the secretory response of the cockroach salivary gland in vitro.

1. A study has been made of the potency of a number of dopamine antagonists to inhibit dopamine-induced secretion from the cockroach salivary gland in vitro. 2. Chlorpromazine (0.5-5 microM), SCH23390 (10-100 microM), haloperidol (10-100 microM) and metoclopramide (2 mM) competitively inhibited the secretory response to dopamine. In contrast (+/-)sulpiride (1-100 microM) and domperidone (1-100 microM) had no effect on either basal or dopamine-induced secretion. 3. Apparent dissociation constants (KDapp) were obtained using a 'three point assay'. The rank order of potency (KDapp in parentheses) was as follows: chlorpromazine (0.2 microM) greater than SCH23390 (2.2 microM) greater than haloperidol (17.5 microM) much greater than metoclopramide (1.2 mM). 4. It is concluded that the receptor mediating dopamine-induced secretion in the cockroach salivary gland is similar to the D1/DA1 dopamine receptor and distinct from the D2/DA2 receptor found in mammalian systems.

Animals↗
PubMed1991

Biogenic amine levels in the cockroach Blaberus craniifer Burm. nervous system.

1. Apart from octopamine, the same indolamines and catecholamines were detected in the whole nervous system of the cockroach Blaberus craniifer Burm., at the same time. 2. However, levels were found to depend on sex, age, and the anatomic region within the nervous system. 3. Although not established, it is thought that these substances act synchronously from the ganglia. 4. The differences in levels between males and females and between anatomical regions during imaginal life suggest, in this species of cockroach, the physiological importance of the metameric organization in metabolic pathways or functional aspects of biogenic amines.

Acetylation↗
PubMed1996

Effect of the insect growth regulators, N-tert-butyl-N, N'-dibenzoylhydrazines, on neural activity of the American cockroach.

N-tert-Butyl-N,N'-dibenzoylhydrazines, agonists of 20-hydroxyecdysone, decelerated the rising and falling phases of an action potential, which had been electrically induced in the cockroach giant axon, at moderately high concentrations. 4-Aminopyridine, a blocker of potassium channels of nerve, selectively decelerated the falling phase of the action potential. This class of compounds caused convulsions in American cockroaches when injected. The convulsive activity seemed to be positively related to the activity to decelerate the falling phase of the action potential.

4-Aminopyridine↗
PubMed1995

Purification and characterization of an esterase isozyme from insecticide resistant and susceptible strains of German cockroach, Blattella germanica (L.).

The most active forms of esterases (E5, E6 and E7) from the German cockroach, Blattella germanica (L.) were purified from resistant and susceptible strains. About 45-155 fold purification with a 11-16% of total esterase recovery was achieved after different column chromatography and preparative gel electrophoresis. Elution profiles of resistant and susceptible strains were similar, but esterase E6 activity was higher in the resistant strains. Kinetic analyses indicate no differences in Km values between the resistant and susceptible strains. However Vmax was significantly higher in resistant strains. Inhibition of esterase activity by paraoxon, chlorpyrifos and propoxur did not suggest any structural differences in esterase E6 between strains. From these results we suggest that insecticide resistance in German cockroach is due to the increased production of E6 esterase. The role of E6 may be sequestration of toxic molecules rather than hydrolysis.

Animals↗
PubMed2005

Unraveling biochemical properties of cockroach (Periplaneta americana) proteinases with a gel X-ray film contact print method.

Eleven proteinase activity bands were detected in American cockroach (Periplaneta americana) gut. These were partially purified and characterized using a gel X-ray film contact print method. Cockroach gut proteinases (CGPs) show activity over a broad range of pH with maximum activity between pH 6 and 10, and optimal activity at 50-70 degrees C. CGPs were partially purified by preparative gel electrophoresis and analyzed using synthetic substrates and inhibitors. Four of the proteases exhibited chymotrypsin-like (C1 to C4) activity and seven trypsin-like (T1 to T7) activity. Accuracy of the gel X-ray film contact print method is confirmed by including bovine chymotrypsin in CGP analysis. Inhibition of CGPs with different plant proteinaceous proteinase inhibitors allowed identification of potential CGP inhibitors. Our results imply that presence of several CGP activity bands, and their stability and activity over a broad pH and temperature range might contribute to adaptation of P. americana to extreme environmental conditions and the polyphagous nature of the species.

Animals↗
PubMed2004

German cockroach extract activates protease-activated receptor 2 in human airway epithelial cells.

BACKGROUND: The German cockroach has been reported to act as an allergen that might be associated with a protease reaction in asthma. However, the molecular identities of the antigens in German cockroach extract (GCE) with protease activity and the protease-activated receptors (PARs) that are activated by GCE in human airway epithelial cells have not been characterized. OBJECTIVE: We investigated the direct effect of GCE on Ca(2+) signaling in human airway epithelial cells and the type of PARs activated by GCE. METHODS: The Ca(2+)-sensitive dye Fura2 was used to determine intracellular Ca(2+) concentration ([Ca(2+)](i)) by means of spectrofluorometry. RESULTS: GCE induced a baseline type of [Ca(2+)](i) oscillations in a dose-dependent manner. The oscillations persisted for long periods of time in the absence of Ca(2+) entry across the plasma membrane, suggesting that the observed [Ca(2+)](i) increases were due to Ca(2+) release from intracellular stores. Accordingly, after depleting endoplasmic reticulum Ca(2+) with thapsigargin, an endoplasmic reticulum Ca(2+) ATPase inhibitor, the GCE-mediated [Ca(2+)](i) signals were abolished. Whereas desensitization of PAR-1, PAR-3, and PAR-4 had no effect on GCE-mediated Ca(2+) mobilization, no GCE-mediated [Ca(2+)](i) increase was observed after desensitization of PAR-2. CONCLUSIONS: These results indicate that GCE has a direct effect on human airway epithelial cells, in particular generating [Ca(2+)](i) oscillations through Ca(2+) release from thapsigargin-sensitive Ca(2+) stores through activation of PAR-2.

Allergens↗
PubMed2005

Cuticular hydrocarbon synthesis and its maternal provisioning to embryos in the viviparous cockroach Diploptera punctata.

Embryos of the viviparous cockroach Diploptera punctata accumulate large amounts of hydrocarbon (HC) of either maternal or embryonic origin. HC synthesis and its accumulation in maternal and embryonic tissues were measured over the course of gestation. Female abdominal integument was the only tissue that synthesized appreciable amounts of HC in vitro, and did so at an increasing rate from the time of mating to mid-pregnancy, when rates of synthesis declined. The embryos synthesized HC at rates <1% those of the female, showing that the majority of HC detected in and on embryos was of maternal origin. The brood sac that houses the developing embryos did not synthesize HC in vitro, indicating that HC must be transported from the female abdominal integument to the embryos. The mass of female epicuticular HC was constant at approximately 183 microg, while her internal HC increased fourfold from mating to mid-pregnancy, then declined until parturition. The decline in internal HC reflected both declining HC synthesis in the female and greater export to the embryos, as embryonic internal HC increased 250-fold prior to parturition. An external HC coating over the oothecal covering and chorion of the embryos increased to mid-pregnancy, then declined. Unlike oviparous cockroaches, D. punctata females fed throughout the reproductive cycle, reflecting the nutritional demands of continuously provisioning the developing embryos.

Age Factors↗
PubMed2005

Block of two subtypes of sodium channels in cockroach neurons by indoxacarb insecticides.

Indoxacarb, a novel insecticide, and its decarbomethoxyllated metabolite, DCJW, are known to block voltage-gated Na(+) channels in insects and mammals, but the mechanism of block is not yet well understood. The present study was undertaken to characterize the action of indoxacarb and DCJW on cockroach Na(+) channels. Na(+) currents were recorded using the whole-cell patch clamp technique from neurons acutely dissociated from thoracic ganglia of the American cockroach Periplaneta americana L. Two types of tetrodotoxin-sensitive Na(+) currents were observed, with different voltage dependencies of channel inactivation. Type-I Na(+) currents were inactivated at more negative potentials than type-II Na(+) currents. As a result, these two types of Na(+) channels responded to indoxacarb compounds differentially. At a holding potential of -100 mV, type-I Na(+) currents were inhibited reversibly by 1 microM indoxacarb and irreversibly by 1 microM DCJW in a voltage-dependent manner, whereas type-II Na(+) currents were not affected by either of the compound. However, type-II Na(+) currents were inhibited by indoxacarb or DCJW at more depolarizing membrane potentials, ranging from -60 to -40 mV. The slow inactivation curves of type-I and type-II Na(+) channels were significantly shifted in the hyperpolarizing direction by indoxacarb and DCJW, suggesting that these compounds have high affinities for the inactivated state of the Na(+) channels. It was concluded that the differential blocking actions of indoxacarb insecticides on type-I and type-II Na(+) currents resulted from their different voltage dependence of Na(+) channel inactivation. The irreversible nature of DCJW block may be partially responsible for its potent action in insects.

Animals↗
PubMed2006

Nutrient-induced alpha-amylase and protease activity is regulated by crustacean cardioactive peptide (CCAP) in the cockroach midgut.

The midgut plays a major role in digestion and absorption of nutrients in insects, and contains endocrine cells throughout the epithelial layer that express neuropeptides, including crustacean cardioactive peptide (CCAP). In the present study, we demonstrate regulation of digestive enzyme activities by CCAP in response to nutrient ingestion in the cockroach, Periplaneta americana. The midgut of the cockroach exhibits maximal alpha-amylase and protease activities 3 h after intake of either starch or casein, but not of non-nutrients. Similar time-dependent responses of CCAP expression in midgut endocrine cells were observed after feeding starch and casein, but not after non-nutrients. We also show that incubation of the dissected midgut with CCAP leads to an increase in alpha-amylase and protease activity in a time-dependent manner, with the maximal activity at 2 h. Taken together, our data indicate the existence of an inducible mechanism where endocrine cells in the midgut are stimulated to synthesize and secrete CCAP by nutrients, and CCAP then up-regulates the activity of digestive enzymes.

Animals↗
PubMed2004

Channel-forming activity in the venom of the cockroach-hunting wasp, Ampulex compressa.

The parasitoid solitary wasp Ampulex compressa uses the cockroach Periplaneta americana as a food supply for its larvae. To subdue its prey, the wasp injects a venom cocktail into the brain of the cockroach. We investigated channel activity of A. compressa venom by collecting venom and incorporating it into a planar lipid bilayer. The venom, reconstituted into the bilayer, showed ion channel activity, forming a fast-fluctuating channel with a small conductance of 20+/-0.1pS, with no voltage sensitivity. These channels were not observed when the venom was digested with proteases before application to the bilayer, but were not affected by exposure to protease after their incorporation into the bilayer, indicating that the active venom component is a peptide. The channels were found to be cation selective with similar selectivity for the monovalent cations K(+), Li(+) and Na(+), but showed high selectivity against anions (Cl(-)) and divalent cations (Ca(2+) and Mg(2+)). This study is the first demonstration and biophysical characterization of channel activity in the venom of A. compressa. The possible functional significance of this channel activity is discussed in light of the unusual nature of the effects of this wasp venom on the behavior of its prey.

Animals↗
PubMed2001

A putative tachykinin receptor in the cockroach brain: molecular cloning and analysis of expression by means of antisera to portions of the receptor protein.

Tachykinins constitute a neuropeptide family that mediate their actions via a subfamily of structurally related G-protein-coupled receptors. Two receptors, Drosophila neurokinin receptor (NKD) and Drosophila tachykinin receptor (DTKR), with sequence similarities to mammalian tachykinin receptors have previously been cloned in Drosophila. In this study we have isolated a cockroach (Leucophaea maderae) cDNA clone by screening a brain cDNA library with a degenerate oligonucleotide probe based on a conserved sequence within the seventh transmembrane region of the Drosophila tachykinin receptors. This clone, Leucophaea tachykinin receptor (LTKR), encodes a portion of a putative receptor which could be aligned with the C-terminal half of members of the tachykinin receptor subfamily. In the fifth, sixth and seventh transmembrane regions the deduced amino acid sequence of LTKR exhibits 79% sequence identity to the DTKR receptor and 54% to that of NKD. This suggests that LTKR is orthologous to the DTKR receptor. To study the distribution of the predicted LTKR protein by immunocytochemistry, antisera were raised against synthetic peptides corresponding to a region of the third intracellular loop of LTKR. In the cockroach brain immunoreactive neuronal processes were seen in several synaptic neuropils of the protocerebrum and tritocerebrum as well as in the frontal ganglion. Some immunoreactive neuronal cell bodies were detected in the protocerebrum. Double labeling immunocytochemistry revealed that there is a substantial superposition between distribution of LTKR and processes containing tachykinin-related peptide (TRP). Some brain areas, however, only display TRP immunoreactive processes and no LTKR, suggesting the presence of at least one more TRP receptor type.

Amino Acid Sequence↗
PubMed2003

A novel function of cockroach (Periplaneta americana) hypertrehalosemic hormone: translocation of lipid from hemolymph to fat body.

The hypertrehalosemic hormones Pea HTH-I and Pea HTH-II have a lipogenic effect in the cockroach, Periplaneta americana. This has been determined by measuring the change in tri-, di-, monoacylglycerol, phospholipid and free fatty acids in the hemolymph and fat body in response to the hormones. The effect of both hormones 6h after injection is comparable and is expressed as an increase in fat body triacylglycerol and a decrease in hemolymph triacylglycerol. Coincident with this effect the concentration of diacylglycerol in the hemolymph decreases while that in the fat body increases. Hemolymph and fat body phospholipid are both lowered by HTH. The concentration of free fatty acids in the hemolymph, as well as fat body, are increased by both hormones. Confirmation of the lipogenic effect of HTH has been obtained by feeding cockroaches [3H]oleic acid and measuring the incorporation of label into hemolymph and fat body lipid. The data show that the specific activity of the hemolymph phospholipid fraction increases more than 50%. In fat body, the specific activity of the label in the triacylglycerol fraction increased more than 2-fold while that in the free fatty acid fraction increased more than 20-fold. The data support the view that the fatty acids incorporated into fat body triacylglycerol under the influence of HTH are not formed de novo but are derived from the sn-1 and sn-2 positions of phospholipid which is initially formed in the midgut wall.

Animals↗
PubMed1975

The fine structure of the cockroach subgenual organ.

This paper describes the fine structure of the cockroach subgenual organ, a complex ciliated mechanoreceptor that detects vibrations in the substrate upon which the animal stands. Located beneath the knee in each walking leg, the cockroach subgenual organ is a thin, fan-shaped flap of tissue slung across the dorsal blood space of the tibia at right angles to the leg's long axis. It is innervated by approximately 50 chordotonal sensilla. The fine structure of the chordotonal sensilla is is described in detail; possible transducer sites are discussed.

Animals↗
PubMed1997

Cockroach allergen (Bla g 1) in school dust.

BACKGROUND: Cockroach allergen, Bla g 1, is an important indoor allergen. Although household exposure has been documented, little is known about the potential for exposure outside the home. OBJECTIVE: We investigated the settled dust concentration of Bla g 1 in 147 samples collected from classrooms, kitchens, cafeterias, and other sites in four primary schools in the city of Baltimore. METHODS: School authorities were questioned about characteristics of schools, teachers, and students, as well as cockroach control and cleaning procedures. Settled dust samples were collected with a hand-held vacuum cleaner from the floors of all classrooms, food-related areas, and other sites of the schools over a 3-week period. A sample collection in each school took 1 to 2 days. Dust samples from each room were pooled and analyzed as a single sample for Bla g 1 by using a two-site monoclonal ELISA. RESULTS: One hundred two (69%) of the 147 samples had detectable Bla g 1 and were within the range reported by other investigators in inner city homes. There was no difference between the median levels of Bla g 1 in three schools: school 1 (5.2 U/gm), school 2 (3.0 U/gm), and school 4 (2.7 U/gm); but school 3 had a significantly lower level (< 0.8 U/gm, p < 0.001). The median level from the food-related areas was significantly higher than the median classroom level (p = 0.048). School 3 had fewer students on subsidized lunch, fewer African-American students, and fewer students per teacher. Bla g 1 levels were compared in the different schools while controlling for potential confounding variables by a stepwise multiple regression analysis with a logit model for ordinal responses. On the basis of this analysis, Bla g 1 levels in schools 1, 2, and 4 differed significantly from levels in school 3 (p < 0.001 in each case). Food-related areas had significantly higher levels than classrooms (p = 0.048). Floor level, the presence of a sink, and the presence of carpeting did not have significant effects. CONCLUSIONS: We conclude that Bla g 1 is detectable at potentially significant concentrations in some inner city schools. Furthermore, the level of exposure is different between different schools and between sites within individual schools.

Allergens↗