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PubMed1993

The wind-elicited escape response of cockroaches (Periplaneta americana) is influenced by lesions rostral to the escape circuit.

When the escape response of the cockroach (Periplaneta americana) is triggered by wind, it is mediated by the cercal-to-giant interneuron pathway and leg motor circuitry, within the abdominal and thoracic portions of the ventral nerve cord. We have found that a lesion rostral to the thorax (transection of a cervical connective) produces specific changes in wind-evoked escape. Lesioned animals reliably displayed short-latency responses to wind. However, the orientation of the initial turning component of escape was altered and the duration of subsequent running was reduced. Preliminary physiological study suggests that changes in the orientation of escape reflect changes in the integration of wind-sensory signals by thoracic circuitry. These findings imply that rostral centers influence sensorimotor integration underlying wind-evoked escape.

Abdomen↗
PubMed1989

Developmental stage-specific antigens in the nervous system of the cockroach.

A specific effort was made to obtain monoclonal antibodies that bind to macromolecules that play a role in the development of the nervous system. It was considered that good candidates for such molecules were those that were only transiently present in the embryonic nervous system. Hybridomas were prepared from spleen cells taken from mice that had been immunized with nerve cords from cockroach embryos at the 43-50% stage of development. The hybridoma supernatants were screened for antibody binding to frozen sections of both embryonic and adult thoracic ganglia. Cell lines that produced monoclonal antibodies that transiently bound to the embryonic nervous system were saved and cloned. These developmental stage-specific monoclonal antibodies either did not bind to the adult nervous system or bound to it with a pattern very different from that in the embryonic nervous system. The developmental stage-specific antigens detected by these monoclonal antibodies were organized into four categories based on the part of the embryonic nervous system in which they were transiently localized. These include binding to the cell bodies of all neurons, cell bodies of subsets of neurons or neuroblasts, subsets of axons, and the neuropile. Preliminary biochemical characterization of the antigens showed that many of these antibodies were recognizing carbohydrate epitopes. Functions for these antigens, most of which are components of the cell surface, are tentatively proposed.

Age Factors↗
PubMed1990

Patterns of ionic currents around the developing oocyte of the German cockroach, Blattella germanica.

The development of patterns of current around vitellogenic oocytes of the cockroach, Blattella germanica, was examined by means of a two-dimensional vibrating probe. Previtellogenic oocytes exhibited small unstable currents. Shortly after vitellogenic uptake began (oocytes 0.6-0.8 mm anterior to posterior) currents were either all inward or all outward at the plane of measurement. A dorsoventral pattern of currents was first observed around oocytes a little larger than 0.8 mm. Current exited dorsally (source) and entered ventrally (sink). In these oocytes source and sink were small, less than half the anterior-posterior length. As oocytes grew, relative sizes of source and sink increased until they extended across the major part of dorsal and ventral surfaces. Many late vitellogenic oocytes had a pattern of dorsal outward current with a bimodal distribution. At the onset of chorionation measured currents were again small, unstable, and exhibited no well-defined pattern. Current density was greatest during midvitellogenesis.

Animals↗
PubMed1978

Postsynaptic effects of 4-aminopyridine in the sixth abdominal ganglion of the cockroach.

The synaptic action of 4-aminopyridine (4-AP) was studied in the sixth abdominal ganglion of the cockroach Periplaneta americana L. The drug 4-AP did not modify the affinity of cholinergic receptors. At concentrations above 10(-4)M, 4-AP depolarized the postsynaptic membranes even after blockage of muscarinic and nicotinic receptors by antagonistic substances.

Animals↗
PubMed1990

The effect of domperidone on the electrical response of cockroach salivary gland acinar cells.

The effects of domperidone on the electrical response of the cockroach salivary gland to applied dopamine and to nerve stimulation have been investigated. Dopamine and nerve stimulation induced a hyperpolarization of the salivary gland acinar cells, which was occasionally followed by a depolarization. At 1 and 10 microM domperidone had no effect on the responses; however, at higher concentrations domperidone (50 and 100 microM) potentiated the hyperpolarization induced by both dopamine and nerve stimulation. Domperidone (50 microM) also potentiated the hyperpolarization induced by 5-HT. Thus the potentiation probably results from a post synaptic action independent of either the dopamine or 5-hydroxytryptamine receptor. In addition, domperidone (50 and 100 microM) had two delayed effects; one, presynaptic, led to a reduction in the response to nerve stimulation; the other, postsynaptic, led to the abolition of the depolarizing phase of the response.

Action Potentials↗
PubMed1989

Isolation and structure of corazonin, a cardioactive peptide from the American cockroach.

Corazonin, a new cardioaccelerating peptide, has been isolated from the corpora cardiaca of the American cockroach, Periplaneta americana, and its structure determined to be Glp-Thr-Phe-Gln-Tyr-Ser-Arg-Gly-Trp-Thr-Asn-amide. The peptide stimulated heart beat at concentrations as low as 0.2 nM, which makes it the most potent insect cardioactive neuropeptide.

Animals↗
PubMed1983

Isolation of neurosecretory granules containing cytochromogenic hormone activity from the corpora cardiaca of Blaberus discoidalis cockroaches.

Neurosecretory granules (NSG) were isolated by differential centrifugation from a homogenate of the corpora cardiaca-corpora allata complex of newly emerged, adult, female Blaberus discoidalis cockroaches. By centrifuging at 11,000 g, the procedure yielded a final pellet that was enriched in small, membrane-bound vesicles (103 nm mean diameter). This pellet contained 61% of the cytochromogenic activity present in the original homogenate at an 11-fold increase in concentration. A pellet formed at 4000 g contained a mixture of mitochondria and larger NSG (146 nm mean diameter) and most of the hindgut-stimulating hormone activity. This procedure provided a quick, simple method for purifying neurosecretory granules and separating them into two categories of size and endocrine content.

Animals↗
PubMed1983

Nervous and humoral inhibition of C16 juvenile hormone synthesis in last instar females of the viviparous cockroach, Diploptera punctata.

The control of the decline in C16 juvenile hormone (C16JH) synthesis in the final larval stadium of the viviparous cockroach Diploptera punctata Eschscholtz was investigated to establish how nervous and humoral signals affect the activity of the corpora allata (CA) before metamorphosis. Denervation of the CA in young last instars caused an increase in the rate of JH biosynthesis as monitored by an in vitro radiochemical assay and resulted in a supernumerary larval form at the following ecdysis. However, when larval CA were transplanted into corpus allatectomized adults, they exhibited a further 5- to 10-fold stimulation in synthetic rate and supported host oocyte development at near normal rates. Conversely, adult CA implanted into young and old last instars were inhibited in comparison to those implanted into penultimate instars and adults. These experiments suggest that in D. punctata, an unfavorable humoral environment as well as nervously transmitted inhibitory signals maintain low rates of JH synthesis prior to the imaginal molt.

Animals↗
PubMed1985

Properties of an in vitro bioassay for hypertrehalosemic hormone of Blaberus discoidalis cockroaches.

The ability of the fat body to respond to the hypertrehalosemic action of corpora cardiaca-allata (CC + CA) extracts was measured in vitro with tissue from adult, male Blaberus discoidalis cockroaches. Only trehalose increased in the hemolymph when gland extracts were injected in vivo; likewise, only trehalose levels responded when fat bodies were exposed to gland extracts in vitro. Although fat bodies from 0-day-old animals gave the least response to gland extracts, all animals 5 or more days old showed elevated responses. A linear dose-response occurred between 0.02 and 0.08 CC + CA pair. Fat bodies did not show an in vitro, hypertrehalosemic response to insulin, glucagon, proctolin, dopamine, epinephrine, norepinephrine, serotonin, octopamine, or tyramine. A strong hypertrehalosemic response was found to both synthetic adipokinetic hormone and red-pigment concentrating hormone; however, reversed-phase, thin-layer chromatography of CC + CA extracts and adipokinetic hormone indicated that the hypertrehalosemic effect and the adipokinetic hormone were separate. This in vitro system comprises a relatively rapid, simple, and accurate bioassay for the hypertrehalosemic neurohormone of insects.

Adipose Tissue↗
PubMed1988

Neuroendocrine and juvenile hormone effects on fat body protein synthesis during the reproductive cycle in female Blaberus discoidalis cockroaches.

Ovarian protein content and fat body protein synthesis were measured during the first gonotrophic cycle in virgin female Blaberus discoidalis cockroaches. Protein synthesis was measured for in vitro fat bodies from animals treated with combinations of a juvenile hormone analog (JHA = methoprene) and corpora cardiaca (CC) extracts. Ovarian protein content began to increase on Day 5 of adult life and reached its maximum at Days 20-22. Synthesis of proteins secreted by the in vitro fat body increased by 12-fold between emergence and its maximum on Day 18, then declined to nearly its original level by Day 33. Synthesis of nonsecreted, fat body proteins increased by 4-fold between emergence and a maximum on Day 21, then declined. CC extracts and JHA were administered to decapitated females to determine their regulative effects on fat body protein synthesis. The synthesis by the fat body of nonsecreted proteins was increased by both JHA and CC extracts. In contrast, synthesis of secreted proteins increased only in the presence of JHA. CC extracts, alone, had no effects on the synthesis of secreted proteins, but administration of CC extracts in combination with JHA increased the synthesis of the secreted proteins by 55% above that observed with JHA alone. SDS-PAGE of proteins secreted into the medium by the in vitro fat body demonstrated that JHA stimulated the synthesis of specific polypeptides, whereas CC extracts did not affect the synthesis of specific-secreted polypeptides. These results suggest that JH regulates specific protein synthesis by the fat body of B. discoidalis; neurohormones elevate the general capacity of the fat body for protein synthesis and amplify the specific effects of JH.

Age Factors↗
PubMed1989

Studies on the cellular defense reactions of the Madeira cockroach, Leucophaea maderae: nodule formation in response to injected bacteria.

Nodules were formed in the Madeira cockroach, Leucophaea maderae, in response to injections of low doses (3 x 10(4) bacteria/insect) of three strains of Bacillus cereus and Escherichia coli K12 D31. The most pathogenic strain of bacteria used, B. cereus B1, produced the greatest cellular response, while the least pathogenic, E. coli K12 D31, injected at the same dose, caused little nodule formation. Similarly, nodules were generally found to be larger following injection of pathogenic bacteria such as B. cereus B1 than to the weak pathogen, E. coli K12 D31. There was, however, no difference in the extent of nodule formation with the four bacterial strains/species if they were heat killed prior to injection. Histologically, the nodules formed in response to all bacterial species employed were similar, with a central necrotic core enclosing cell debris and occasional bacteria, and an outer, thin sheath of plasmatocyte-like hemocytes. Possible reasons for the enhanced cellular reactivity observed in L. maderae to pathogenic bacteria are discussed.

Animals↗
PubMed1982

Effects of central nervous system lesions on leg lift learning in the cockroach, P. americana.

When headless and intact cockroaches were trained to keep their prothoracic legs flexed to avoid electric shock, headless animals reached an asymptote more quickly than intact animals. Three behavioral measures were examined for experimental and yoked control animals to analyze differences between headless and intact animals. When cycloheximide (CXM) was injected before leg lift training, cycloheximide-injected headless animals reached an asymptote more slowly than control headless animals. However, cycloheximide did not impair leg lift learning in intact animals.

Animals↗
PubMed1994

Leg position learning in the cockroach nerve cord using an analog technique.

The ultimate goal of this research is to correlate neural activity with leg behavior during learning. Contrary to previous studies of shock avoidance learning in the headless cockroach, in which an all-or-none method of recording was used, we have adopted a direct analog recording of leg position to measure learning in the prothoracic ganglion. This method provides a sensitive and continuous record of leg movement that can be correlated with the interactions of individual neurons that may be involved in such learning. Of the 10 prothoracic legs trained to flex to avoid shock, eight escaped shock by flexion within a maximum of 13 min and seven showed savings when retested. Only four of eight prothoracic legs trained to extend showed avoidance learning and all four showed savings. Electrical stimulation of nerves 3,4,5, and 6 innervating the prothoracic leg revealed which nerves were instrumental in the flexion and extension responses.

Animals↗
PubMed1975

Inverted gap and other cell junctions in cockroach hemocyte capsules: a thin section and freeze-fracture study.

Freeze-fracture and thin-section studies were done on cockroach hemocytes that had encapsulated implanted pieces of Araldite. Desmosome-like junctions and 'B' type gap junction were described. Freeze-fractured gap junctions displayed fused and clustered, but not hexagonally arrayed intramembranous practicles (approximately 130 A) on the B face and pitted areas on the A face of the plasmalemma. Gap junctions were quite numerous and counts of gap and non-gap particles indicated at least a five-fold particle density increase (4000/mu2) compared with B face particle densities (approximately 800/mu2) from free circulating blood cells where gap junctions had not been formed.

Animals↗
PubMed1976

Fine structure of the rectum in cockroaches (Dictyoptera): general organization and intercellular junctions.

The organization of the rectal pads is described in cockroaches belonging to the Groups Blattoidea (Periplaneta americana, Blatta orientalis) and Blaberoidea (Supella supellectillu, Blaberus craniifer). In the Blattoidea, each pad is composed of two layers (principal and basal cells) and is surrounded by very narrow junctional cells supporting the sclerotized cuticle of the pad frame; basally, the junctional cells abut on to the basal cells. In the Blaberoidea, the basal cell layer is discontinuous, the basal cells being interspersed between extensions of the junctional cells beneath the pad. The ultrastructural features of each cell type is described, with special reference to the intercellular junctions, which exhibit unusual complexity. Four types of junction are recognized: desmosomes (belt and spot desmosomes), gap junctions, septate junctions and scalariform (ladder-like) junctions. The last are usually closely associated with mitochondria, forming mitochondrial-scalariform junction complexes (MS). The distribution of these junctions is examined in relation to the partitioning of extracellular spaces, and to the problem of fluid transport.

Animals↗
PubMed1978

Fine structure of axons associated with the salivary apparatus of the cockroach, Nauphoeta cinerea.

Previous studies have shown that the neurotransmitter at the salivary gland of the cockroach is probably dopamine. An ultrastructural study of the innervation of these glands was made. It was concluded that there are two types of axon present designated type A and type B. Type A axons possess small agranular eliptical vesicles and large granular vesicles, whereas type B possess only large granular vesicles of larger diameter than those found in type A. The relationship of these types of axon to the cells of the acini is discussed. It is concluded that type A axons are catecholaminergic.

Animals↗
PubMed1980

Histochemical properties of axons associated with the salivary apparatus of the cockroach, Nauphoeta cinerea.

A variety of techniques have indicated that dopamine is probably the neurotransmitter at the salivary gland of the cockroach, Nauphoeta cinerea (Olivier). It is known from a previous ultrastructural study that two types of axon are associated with the gland but it is not known which of these axons contain catecholamines. The present study, using permanganate fixation or incubation in 5-hydroxydopamine or 6-hydroxydopamine, shows that only one category of axon contains catecholamines.

Animals↗
PubMed1981

Frontal bodies: novel structures involved in water vapour absorption by the desert burrowing cockroach, Arenivaga investigata.

Above 83% relative humidity, nymphs and adult females of the desert cockroach can condense water vapour on to a fluid layer covering protruded hypopharyngeal bladders. This fluid is produced by a pair of spheroidal bodies situated beneath the frons. Each such frontal body is connected by to the corresponding bladder by a groove in the epipharynx. During absorption, contraction of muscles connecting the frontal bodies to the frons causes them to move dorsally from the mandibles. Oscillation frequency increases with relative humidity or the application of nanoliter quantities of water to the bladders. Frontal bodies appear to be derived from invaginations of the integument, and consist of a mass of tough fibres containing protein and chitin. Fibres embed in a permeable plate which gives rise to the epipharyngeal groove. Tonofibrillae connect the fibres to elongate epidermal cells which are composed primarily of microtubules. The myoepidermal junction is characterized by fascia adherens. Frontal bodies resist tensile forces, but undergo changes in shape as they oscillate. Accompanying changes in hydrostatic pressure may move extracellular fluid across the plate and into the epipharyngeal groove. Possible roles of the fluid in the absorption process are discussed.

Absorption↗