Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cockroaches”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed1990

Morphological and physiological characterization of descending ocellar interneurons in the American cockroach.

In the present study two types of descending ocellar neurons have been morphologically and physiologically identified in the cockroach Periplaneta americana: a descending ipsilateral ocellar neuron (DIO-neuron) and a descending contralateral ocellar neuron (DCO-neuron). Both DIO- and DCO-neurons possess a cell body near the ocellar tract in the protocerebrum and extend dendritic processes into the ipsilateral ocellar nerve. An axon of the DIO-neuron descends to the metathoracic ganglion, and its entire course is ipsilateral to the cell body. An axon of the DCO-neuron crosses the median plane of the protocerebrum and descends through the contralateral ventral nerve cord to the second abdominal ganglion. Both axons possess masses of branches in each ganglion as well as in the brain. Both DIO- and DCO-neurons showed no spontaneous spike discharges, and responded with a few off-spikes to ocellar illumination. They responded to various mechanical stimuli, like cercal stimulation with a train of spikes which was suppressed by ocellar illumination. Spikes of DCO-neurons caused postsynaptic potentials and spikes in some interganglionic metathoracic interneurons, and spikes in motor nerves. These data are discussed in relation to the ocellar function of the cockroach as well as in comparison with that of other insects.

Animals↗
PubMed1995

Morphology of higher-order ocellar interneurons in the cockroach brain.

Most species of insects have two or three ocelli, in addition to a pair of compound eyes. In the cockroach ocellus, a large number of photoreceptors converge upon four second-order neurons, which exit the ocellus and project into the ocellar tract neuropil of the brain, where they form synapses with at least 15 third-order neurons. Third-order neurons project into a variety of neuropils in the brain, including the posterior slope, a premotor center from which descending neurons originate. I examined the morphology and ocellar response of neurons in the posterior slope of the cockroach, using intracellular recording and stainings. Most ocellar neurons of the posterior slope exhibited transient depolarizations at the cessation of ocellar illumination, which seem to reflect sign-conserving synaptic input from third-order neurons. Ocellar neurons of the posterior slope project into various areas of the brain, including 1) the central complex, a higher center implicated in higher locomotory control, 2) the pedunculus of the mushroom body, an associative center, 3) the lamina (the first neuropil of the culus of the mushroom body, an associative center, 3) the lamina (the first neuropil of the optic lobe), 4) the antennal lobe (olfactory center), 5) the tritocerebrum (mechanosensory center), and 6) the subesophageal and thoracic motor centers. These results suggest that the posterior slope is a high-order ocellar center from which ocellar signals are transmitted to various target neuropils of the brain, as well as a premotor center to form descending motor commands.

Animals↗
PubMed1992

The problem of the number of tarsomeres in the regenerated cockroach leg.

There are 5 tarsomeres in the normal cockroach leg, but this number is often reduced in regenerated legs. In order to examine this complicated situation, fore-, mid-, and hindlegs of German cockroaches were amputated at 11 different tarsal levels and at 18 different times during the last instar. When tarsi were amputated at or proximal to the 3rd tarsomere, 4-segmented tarsi regenerated. When legs were amputated distal to the 3rd tarsomere, the regenerated tarsi had 5 segments. Three-segmented tarsi rarely regenerated when legs were amputated proximal to 3rd tarsomere and in the latter half of the instar period. The lengths of all tarsomeres of regenerated tarsi were measured together with those of unoperated contralateral tarsomeres, and the ratios of the former to the latter were calculated. The ratios ranged from 28 to 138% for the various tarsomeres and levels of amputation. From a comparison of the ratios and morphological observations, it was suggested that the 3rd tarsomere of the normal 5-segmented tarsus has disappeared in the regenerated 4-segmented tarsus. Pads and disto-lateral spines of tarsomeres were observed on unoperated and regenerated tarsi. It was of interest that double spines were often found on the 4-segmented tarsi, mostly on the 2nd tarsomere, just proximal to the position of the missing 3rd tarsomere. This observation supported the idea that the 3rd tarsomere has not simply disappeared, but has probably fused with the 2nd tarsomere.

Animals↗
PubMed2005

Cockroach homologs of praying mantis peripheral auditory system components.

This study identifies the cuticular metathoracic structures in earless cockroaches that are the homologs to the peripheral auditory components in their sister taxon, praying mantids, and defines the nature of the cuticular transition from earless to eared in the Dictyoptera. The single, midline ear of mantids comprises an auditory chamber with complex walls that contain the tympana and chordotonal transduction elements. The corresponding area in cockroaches, between the furcasternum and coxae, has many socketed hairs arranged in discrete fields and the Nerve 7 chordotonal organ, the homolog of the mantis tympanal organ. The Nerve 7 chordotonal organ attaches at the apex of the lateral ventropleurite (LVp), which has the same shape and general structure as an auditory chamber wall. High-speed video shows that when the coxa moves toward the midline, the LVp rotates medially to stimulate socketed hairs, and also moves like a triangular hinge giving the chordotonal organ maximal in-out stimulation. Formation of the mantis auditory chamber from the LVp and adjacent structures would involve only enlargement, a shift toward the midline, and a mild rotation. Almost all proprioceptive function would be lost, which may constitute the major cost of building and maintaining the mantis ear. Isolation from leg movement dictates the position of the mantis ear in the midline and the rigid frame, formed by the cuticular knobs, which protects the chordotonal organs.

Animals↗
PubMed1991

Localization of ventral giant interneuron connections to the ventral median branch of thoracic interneurons in the cockroach.

A detailed morphological study was performed to localize the probable sites of connections between two identified populations of interneurons (ventral giant interneurons and type-A thoracic interneurons) in the cockroach. Type-A thoracic interneurons (TIAS) appear to play an important role in orienting the cockroach during wind-mediated escape. However, their large number, approximately 100 neurons, precludes analyzing each cell's role electrophysiologically. The TIAS are characterized by a prominent branch located on one or both sides of the ventral median (VM) region of the thoracic ganglion in which their soma resides. The presence of this ventral median branch can be used to predict connectivity with left or right ventral giant interneurons (vGIs) (Ritzmann and Pollack, 1988) and is correlated with the TIA's directional response to wind (Westin, Ritzmann, and Goddard, 1988), suggesting that this is the locus of synaptic connection. Two approaches were employed to address this hypothesis. Morphological overlap of differentially labelled cells (ethidium bromide, Lucifer Yellow) was examined at the light microscopic level to locate areas of possible synaptic contact. Experiments were also performed in which one-half of the vGI input to the TIAs was surgically removed early in postembryonic development. Although no changes in the overall branching pattern were observed, the VM branches on the operated side were significantly shorter than were those on the unoperated side. Thoracic interneurons that do not receive inputs from vGIs were unaffected by this surgery. The data reported here thereby confirm previous observations by localizing the vGI inputs specifically to the VM branch, and provide a morphological cue for predicting connectivity and function.

Animals↗
PubMed1995

Dual pathways for tactile sensory information to thoracic interneurons in the cockroach.

The escape system of the American cockroach is both fast and directional. In response to wind stimulation both of these characteristics are largely due to the properties of the ventral giant interneurons (vGIs), which conduct sensory information from the cerci on the rear of the animal to type A thoracic interneurons (TIAs) in the thoracic ganglia. The cockroach also escapes from tactile stimuli, and although vGIs are not involved in tactile-mediated escapes, the same thoracic interneurons process tactile sensory information. The response of TIAs to tactile information is typically biphasic. A rapid initial depolarization is followed by a longer latency depolarization that encodes most if not all of the directional information in the tactile stimulus. We report here that the biphasic response of TIAs to tactile stimulation is caused by two separate conducting pathways from the point of stimulation to the thoracic ganglia. Phase 1 is generated by mechanical conduction along the animal's body cuticle or other physical structures. It cannot be eliminated by complete lesion of the nerve cord, and it is not evoked in response to electrical stimulation of abdominal nerves that contain the axons of sensory receptors in abdominal segments. However, it can be eliminated by lesioning the abdominal nerve cord and nerve 7 of the metathoracic ganglion together, suggesting that the relevant sensory structures send axons in nerve 7 and abdominal nerves of anterior abdominal ganglia. Phase 2 of the TIA tactile response is generated by a typical neural pathway that includes mechanoreceptors in each abdominal segment, which project to interneurons with axons in either abdominal connective. Those interneurons with inputs from receptors that are ipsilateral to their axon have a greater influence on TIAs than those that receive inputs from the contralateral side. The phase 1 response has an important role in reducing initiation time for the escape response. Animals in which the phase 2 pathway has been eliminated by lesion of the abdominal nerve cord are still capable of generating a partial startle response with a typically short latency even when stimulated posterior to the lesion.

Animals↗
PubMed2000

Partial characterization of a putative allatostatin receptor in the midgut of the cockroach Diploptera punctata.

Dippu-allatostatins (Dippu-ASTs) are a family of peptides originally isolated from the cockroach Diploptera punctata which appear to be pleiotropic in function. All members of the family are able to inhibit the biosynthesis of juvenile hormone by corpora allata in vitro. In addition, ASTs are able to modulate the contraction of visceral muscles and may play a role in the regulation of digestive enzyme secretion by the midgut. We have identified a putative AST receptor in the cockroach midgut using a radioligand-binding assay. (125)I-Dippu-AST 7 binding to midgut membranes was specific, saturable, and reversible. The midgut appears to contain a single class of binding sites for Dippu-AST 7, with K(d) of 20.9 +/- 3.6 nM and B(max) of 1.8 +/- 0.15 pmol. mg(-1) membrane protein. The relative affinity of the 13 members of the Dippu-AST family was determined using a single-point competitive binding assay. Dippu-AST 7 and 2 appear to have higher affinity for the midgut AST receptor than Dippu-AST 5, 9, 10, or 11. Other Dippu-ASTs were unable to compete with (125)I-Dippu-AST 7 for binding, even at high concentration.

Animals↗
PubMed1982

The toxicity of p-benzoquinone on the central nervous system of the cockroach.

The behavioural symptoms of acute-p-benzoquinone intoxication in the cockroach were shown to be an initial excitation followed by rigid paralysis. p-Benzoquinone produced a depolarization of the postsynaptic membrane of the giant neurones in the 6th abdominal ganglion of the cockroach which was accompanied by an increase in the electrically evoked excitatory postsynaptic potential. The frequency and amplitude of unitary postsynaptic potentials also increased. These effects may be due to inhibition of active cation transport, as illustrated here on the frog isolated skin.

Animals↗
PubMed1990

A circadian rhythm in neural activity can be recorded from the central nervous system of the cockroach.

Evidence presented in this paper indicates that a robust circadian rhythm in the frequency of neural activity can be recorded from the central nervous system of intact cockroaches, Leucophaea maderae. This rhythmicity was abolished by optic lobe removal. Spontaneous neural activity was then used as an assay to demonstrate that the optic lobe is able to generate circadian oscillations in vitro. These results provide direct evidence that the cockroach optic lobe is a self-sustained circadian oscillator capable of generating daily rhythms in the absence of neural or hormonal communications with the rest of the organism.

Action Potentials↗
PubMed1990

Catecholamines and related o-diphenols in cockroach hemolymph and cuticle during sclerotization and melanization: comparative studies on the order Dictyoptera.

Catecholamines and related o-diphenols extracted from the cuticle and hemolymph of adult cockroaches during sclerotization and pigmentation of the cuticle were analyzed by reverse phase HPLC with electrochemical detection. At ecdysis, dopamine (DA) o-conjugates predominated in the hemolymph of Periplaneta americana, P. australasiae, P. fuliginosa, P. brunnea, and Blatta orientalis (Blattidae); Blattella germanica (Blattellidae); and Gromphadorhina portentosa and Blaberus craniifer (Blaberidae). N-Acetyldopamine (NADA) conjugates were second in abundance in these species, but were major in the hemolymph of the other blaberoid species, Leucophaea maderae and Nauphoeta cinerea. After ecdysis NADA became the major hemolymph catecholamine in all species as DA decreased rapidly. N-beta-Alanyldopamine (NBAD) concentrations in the hemolymph remained low in all species, although NBAD and its metabolite, N-beta-alanylnorepinephrine (NBANE), were generally the major catecholamines in tanning cuticle. Catechol (1,2-dihydroxybenzene) occurred mainly as a conjugate(s) at high levels in the hemolymph of nymphs and adults of all blattid species. Only trace amounts were detected in B. germanica and Cryptocercus punctulatus (Cryptocercidae), and none was found in any of the blaberoid species. High concentrations of NBANE and NBAD accumulated in tanning cuticle of B. germanica, G. portentosa, and all blattid species, whereas NADA and DA predominated in cuticle from the other blaberoid species, particularly L. maderae and N. cinerea. However, cockroaches as a group appear to utilize both the N-acetyl and N-beta-alanyl catecholamines for stabilization of the exoskeleton. The Blattidae differed most from the other families in having considerably higher concentrations of catecholamines in hemolymph and cuticle, as well as the large amounts of catechol conjugates in the hemolymph.

Animals↗
PubMed1982

Demonstration of kinetochores and centrioles in spermatocytes of two species of cockroaches by silver staining.

Light microscopy following silver staining of spermatocytes of German and Madagascar hissing cockroaches demonstrated: (1) the localization of a kinetochore in each autosomal synaptonemal complex during pachytene, and (2) visualization of centrioles in different stages of meiotic prophase. The presence of a "hairpin-like" twist and the nucleolus organizer region in the X-chromosome was observed only in the German cockroach.

Animals↗
PubMed1987

Immunocytochemical demonstration of proopiomelanocortin- and other opioid-related substances and a CRF-like peptide in the gut of the american cockroach, Periplaneta americana L.

Using the peroxidase-antiperoxidase technique, we showed the presence of peptides which are immunologically resembling mammalian corticotropin releasing hormone (CRF)-, adrenocorticotropic hormone (ACTH)-, beta-endorphin (beta-END)-, alpha-melanocyte stimulating hormone (alpha-MSH)-, methionine-enkephalin (met-ENK)- and leucine enkephalin (leu-ENK)- like immunoreactivity in hundreds to thousands of endocrine cells and nerve fibers in the midgut of the American cockroach Periplaneta americana. In the cockroach hindgut no immunoreactive cell bodies could be observed, although nerve fibers were clearly noticed to be recognized by antisera to CRF, ACTH1-24, ACTH11-24 and beta-END. Nothing is exactly known as to the function(s) of the demonstrated materials, but one can speculate that these numerous immunoreactive cells, might have important paracrine and/or endocrine functions in the insect physiology.

Adrenocorticotropic Hormone↗
PubMed1988

Organization of a complex movement: fixed and variable components of the cockroach escape behavior.

The escape behavior of the cockroach Periplaneta americana was studied by means of high speed filming (250 frames/s) and a computer-graphical analysis of the body and leg movements. The results are as follows: 1. The behavior begins with pure rotation of the body about the posteriorly located cerci, followed by rotation plus forward translation, and finally pure translation (Figs. 1, 2). 2. A consistent inter-leg coordination is used for the entire duration of the turn (Fig. 3A). At the start of the movement, five or all six legs execute their first stance phase (i.e. leg on the ground during locomotion) simultaneously. By the end of the turn the pattern has changed to the alternate 'tripod' coordination characteristic of insect walking. The change-over from all legs working together, to working alternately, occurs by means of a consistent pattern of delays in the stepping of certain legs. 3. The movements made by each leg during its initial stance phase are carried out using consistent movement components in the anterior-posterior (A-P) and the medial-lateral (M-L) axes (Fig. 4A). The movement at a particular joint in each middle leg is found to be diagnostic for the direction of turn. 4. The size and direction of a given leg's M-L movement in its initial stance phase depends on the same leg's prior A-P position (Fig. 5). No such feedback effects were seen among different legs. 5. Animals that are fixed to a slick surface on which they make slipping leg movements show the same inter-leg coordination (Fig. 3B), direction of initial stance movement (Fig. 4B) and dependence of the leg's initial M-L movement on its prior A-P position (Fig. 6), as did free-ranging animals. 6. Cockroaches that are walking at the moment they begin their escape reverse those ongoing leg movements that are contrary to escape movements. 7. These results are discussed in terms of the overall coordination of the complex movements, and in terms of the known properties of the neural circuitry for escape. Possibilities for neurobiological follow-up of certain of the findings presented here are also addressed.

Animals↗
PubMed1995

Toxic effects of boric acid on the German cockroach.

Boric acid is a slow-acting, inorganic insecticide whose mode of action has not been satisfactorily elucidated. Reported here is evidence which shows that ingested boric acid destroys the cellular lining of the foregut of German cockroaches, Blattella germanica (L.). This effect appears to be sufficient to bring about the death of the insects, perhaps ultimately by starvation. This finding is important because resistance to conventional insecticides may re-establish boric acid as a prominent cockroach control chemical.

Animals↗
PubMed2001

Isolation and characterization of a Chryseobacterium strain from the gut of the American cockroach, Periplaneta americana.

A 16S rDNA sequence cloned directly from whole-gut microbiota of the American cockroach, Periplaneta americana, indicated the presence of a member of the Bacteroides/Flavobacterium group most closely related to the genus Flavobacterium. In an attempt to confirm this finding, we isolated a yellow-pigmented bacterium (strain FR2) from the hindgut of this insect. Strain FR2 was phylogentically and phenotypically most similar to species of Flavobacterium and related bacteria, namely Chryseobacterium indologenes. Fifty-four other yellow-pigmented bacteria isolated during a 1-year study shared the salient phenotypic characteristics of Chryseobacterium spp., and thus were considered the same phenotype. This phenotype's abundance was related to the fiber content of the insect diet, being consistently detected only in cockroaches fed a high-fiber diet (30% crude fiber by weight). The highest population density was in the hindgut, ranging from 2 x 10(6) to 1.2 x 10(7) colony forming units ml(-1) during a 1-year period. The nature of the symbiosis between the FR2 phenotype and P. americana is discussed.

Animals↗
PubMed2002

Control of climbing behavior in the cockroach, Blaberus discoidalis. II. Motor activities associated with joint movement.

Deathhead cockroaches employ characteristic postural strategies for surmounting barriers. These include rotation of middle legs to re-direct leg extension and drive the animal upward. However, during climbing the excursions of the joints that play major roles in leg extension are not significantly altered from those seen during running movements. To determine if the motor activity associated with these actions is also unchanged, we examined the electromyogram activity produced by the slow trochanteral extensor and slow tibial extensor motor neurons as deathhead cockroaches climbed over obstacles of two different heights. As they climbed, activity in the slow trochanteral extensor produced a lower extension velocity of the coxal-trochanteral joint than the same frequency of slow trochanteral extensor activity produces during horizontal running. Moreover, the pattern of activity within specific leg cycles was altered. During running, the slow trochanteral extensor generates a high-frequency burst prior to foot set-down. This activity declines through the remainder of the stance phase. During climbing, motor neuron frequency no longer decreased after foot set-down, suggesting that reflex adjustments were made. This conclusion was further supported by the observation that front leg amputees generated even stronger slow trochanteral extensor activity in the middle leg during climbing movements.

Amputation, Surgical↗
PubMed2003

Wind spectra and the response of the cercal system in the cockroach.

Experiments on the cercal wind-sensing system of the American cockroach, Periplaneta americana, showed that the firing rate of the interneurons coding wind information depends on the bandwidth of random noise wind stimuli. The firing rate was shown to increase with decreases in the stimulus bandwidth, and be independent of changes in the total power of the stimulus with constant spectral composition. A detailed analysis of ethologically relevant stimulus parameters is presented. A phenomenological model of these relationships and their relevance to wind-mediated cockroach behavior is proposed.

Action Potentials↗
PubMed2000

Two engrailed-related genes in the cockroach: cloning, phylogenetic analysis, expression and isolation of splice variants.

engrailed-related genes have been isolated in numerous taxa. Within the insects, some species have a single engrailed-related gene whilst others have two copies, raising the question of when and how often gene duplications have occurred. Here we report the cloning, in the cockroach Periplaneta americana, of two engrailed-related genes Pa-en1 and Pa-en2. By comparing conserved domains and by carrying out a phylogenetic analysis, we conclude that these two genes are likely to be the product of a recent duplication in the cockroach lineage. Pa-en1 and Pa-en2 are co-expressed during early embryogenesis and their segmental pattern of expression appears in an anterior-posterior progression. We have also isolated potential splice variants of Pa-en2 which lack some regulatory domains. The roles these splice variants may play in regulating developmental processes are discussed.

Alternative Splicing↗