Moniliformis moniliformis infection has no effect on some behaviors of the cockroach Diploptera punctata.

The behavior of the cockroach Diploptera punctata parasitized with the acanthocephalan Moniliformis moniliformis was examined for parasite-induced alterations. No significant difference in behavior was found between parasitized and unparasitized animals in the following behavioral tests: (1) choice of white/black, horizontal/vertical substrate under light and dark conditions; (2) temporal and directional response to a bright light source; (3) choice between light and dark (photophilia); and (4) activity (time spent moving, distance, and velocity). A comparison of uninfected animals under 2 light conditions showed that light affected the activity of uninfected animals and their response to substrate. Diploptera punctata is the first nondomestic cockroach to be examined for behavioral responses to Moniliformis infection. This is the first report of an arthropod in which acanthocephalan infection has failed to alter behavior under at least some common test conditions.     

Investigation of a sex pheromone for the oriental cockroach,Blatta orientalis

A sex pheromone for adult male oriental cockroaches Blatta orientalis was isolated from the faeces of adult virgin female oriental cockroaches. It elicited a sexual response at 10 pg and 1 ng with B. orientalis and Periplaneta americana adult males, respectively. The site of production appers to be the crop, oesophagus, and proventriculus. Electroantennogram responses of male antennae toward the isolated pheromone were greater than those of the female antennae. The adult male oriental cockroach also responded to the American cockroach sex pheromone. The isolated pheromone with a mol. wt of 232 may be similar to one of the components of the American cockroach sex pheromone.     

Significance of methanogenic symbionts for development of the American cockroach,Periplaneta americana

The effects of suppression of methanogenesis with a drug, 2-bromoethanesulfonic acid (BES), on the hindgut ecosystem and development of the cockroach Periplaneta americana fed either low or high fiber diet were evaluated by measuring methane production, volatile fatty acids (VFA) concentrations in the hindgut, cockroach weight gain and development time (the length of nymphal period). Methane production and VFA concentrations in the hindgut of cockroaches fed high fiber diet were significantly higher than those fed low fiber diet. Although BES treatment greatly reduced methane production, VFA concentrations in the hindgut, cockroach weight gain and development time were not significantly altered. These results indicate that methanogenic microbes are not essential for keeping low hydrogen pressure in the hindgut lumen, and normal cockroach development.     

Experimental infection of the cockroach Periplaneta americana with Toxocara canis and the establishment of patent infections in pups

The possible role of the cockroach Periplaneta americana in the transmission of Toxocara canis eggs and larvae via faeces and tissue migration was studied. Cockroaches fed with 3 x 105 and 5 x 105 embryonated eggs were found to harbour viable eggs and larvae from days 1 to 5 post-infection (DPI). At necropsy on 5 DPI, eggs and larvae were also recovered from the rectal contents but not from the tissues of cockroaches. In addition patent infections were established in pups fed on infected faeces of cockroaches, with eggs first appearing in the faeces of pups at 38 DPI. Adult worms of T. canis were also recovered at necropsy. Therefore the importance of cockroaches as good mechanical disseminators of ascarid eggs, especially T. canis, is discussed.     

Tricarboxylic Acid Cycle Enzymes in Tetrahymena pyriformis after Infection of the Cockroach Periplaneta americana1

SYNOPSIS. Activities of enzymes of the tricarboxylic acid cycle in extracts of Tetrahymena pyriformis S, axenically recovered after living in the hemocoel of female cockroaches Periplaneta americana for 48 hr, were compared with activities in ciliates not exposed to the cockroach. Malic dehydrogenase activity was depressed after recovery from the cockroach; isocitric and succinic dehydrogenases and α-ketoglutaric oxidase activities were unchanged. Citrate synthetase activity was increased, and pyruvi oxidase activity decreased, after ciliates had been in the cockroach. These alterations persisted for several hundred generations after recovery from the insect.     

Contribution of anaerobic protozoa and methanogens to hindgut metabolic activities of the American cockroach, Periplaneta americana.

The ciliate Nyctotherus ovalis occurs in high numbers in the hindgut of the American cockroach (Periplaneta americana) and harbors methanogenic bacteria as endosymbionts. The contribution of these hindgut microorganisms to metabolic and developmental processes of P. americana was studied by comparing cultures of cockroaches in which the composition of the hindgut microbial population was altered in various ways. Rearing the insects protozoan free resulted in increased insect generation time, decreased adult body weight, and absence of methane production. After feeding of protozoan-free adult cockroaches with a hindgut suspension containing N. ovalis and methanogens, methane increased to normal values and insect body weight was restored during the development of the second generation of insects. Feeding the protozoan-free cockroaches a hindgut suspension which was made free of N. ovalis resulted in an increase in methane production to only about 20% of the normal methane production level. This suggests that the methanogenic endosymbionts of N. ovalis are the major source of methane production in the hindgut. Inhibition of methanogens by addition of bromoethanesulfonic acid to the drinking water of a normal cockroach culture resulted in a reduction of methane production to about 2% of the normal level. No effects on insect body weight or the number of N. ovalis organisms were observed, but the fermentation pattern in the hindgut was shifted towards a relative increase in propionate levels. Similar results were obtained for in vitro cultures of hindgut microorganisms treated with bromoethanesulfonic acid. The results suggest a major role for hindgut protozoa in cockroach metabolic activities, especially during the insect growth period. The relatively large amounts of methane produced by cockroaches and by other methane-producing xylophagous insects suggest a major contribution by insects to global methane production.     

Classical olfactory conditioning in the cockroach Periplaneta americana

We established a classical conditioning procedure for the cockroach, Periplaneta americana, by which odors were associated with reward or punishment. Cockroaches underwent differential conditioning trials in which peppermint odor was associated with sucrose solution and vanilla odor was associated with saline solution. Odor preference of cockroaches was tested by allowing them to choose between peppermint and vanilla sources. Cockroaches that had undergone one set of differential conditioning trials exhibited a significantly greater preference for peppermint odor than did untrained cockroaches. Memory formed by three sets of differential conditioning trials, with an inter-trial interval of 5 min, was retained at least 4 days after conditioning. This conditioning procedure was effective even for cockroaches that had been harnessed in plastic tubes. This study shows, for the first time in hemimetaborous insects, that both freely moving and harnessed insects are capable of forming olfactory memory by classical conditioning procedure. This procedure may be useful for future electrophysiological and pharmacological studies aimed at elucidation of neural mechanisms underlying olfactory learning and memory.     

Brain-midgut short neuropeptide F mechanism that inhibits digestive activity of the American cockroach, Periplaneta americana upon starvation

Immunohistochemical reactivity against short neuropeptide F (sNPF) was observed in the brain-corpus cardiacum and midgut paraneurons of the American cockroach, Periplaneta americana. Four weeks of starvation increased the number of sNPF-ir cells in the midgut epithelium but the refeeding decreased the number in 3h. Dramatic rises in sNPF contents in the midgut epithelium and hemolymph of roaches starved for 4 weeks were confirmed by ELISA. Starvation for 4 weeks reduced α-amylase, protease and lipase activities in the midgut of P. americana but refeeding restored these to high levels. Co-incubation of dissected midgut with sNPF at physiological concentrations inhibited α-amylase, protease and lipase activities. sNPF injection into the hemocoel led to a decrease in α-amylase, protease and lipase activities, whereas PBS injection had no effects. The injection of d-(+)-trehalose and l-proline into the hemocoel of decapitated adult male cockroaches that had been starved for 4 weeks had no effect on these digestive enzymes. However, injection into the hemocoel of head-intact starved cockroaches stimulated digestive activity. Injection of d-(+)-trehalose and l-proline into the lumen of decapitated cockroaches that had been starved for 4 weeks increased enzymes activities and suppressed sNPF in the midgut. Our data indicate that sNPF from the midgut paraneurons suppresses α-amylase, protease and lipase activities during starvation. Injection of d-(+)-trehalose/l-proline into the hemocoel of head-intact starved cockroach decreased the hemolymph sNPF content, which suggests that sNPF could be one of the brain factors, demonstrating brain-midgut interplay in the regulation of digestive activities and possibly nutrition-associated behavioral modifications.     

Roles of fat body trophocytes,mycetocytes and urocytes in the American cockroach,Periplaneta americana under starvation conditions: An ultrastructural study

In insects, trophocytes (adipocytes) are major cells of a storage organ, the fat body, from which stored glycogen and lipids are mobilized under starvation. However, cockroaches have 2 additional types of cell in the fat body: mycetocytes harboring an endosymbiont, Blattabacterium cuenoti, and urocytes depositing uric acid in urate vacuoles. These cells have not been investigated in terms of their roles under starvation conditions. To gain insight into the roles of trophocytes, mycetocytes and urocytes in cockroaches, structural changes were first investigated in the cells associated with starvation in the American cockroach, Periplaneta americana, by light and electron microscopy. The area of lipid droplets in trophocytes, the endosymbiont population and mitotic activity in mycetocytes, and the area of urate vacuoles in urocytes were analyzed in association with survival rates of the starved cockroaches. After 2 weeks of starvation, trophocytes lost glycogen rosettes and their area of lipid droplets decreased, but almost all cockroaches survived this period. However, further starvation did not reduce the area, but the survival rates dropped rapidly and all cockroaches died in 7 weeks. Endosymbionts were not affected in terms of population size and mitotic activity, even if the cockroaches were dying. The area of urate vacuoles rapidly decreased in a week of starvation and did not recover upon further starvation. These results indicate that starved cockroaches mobilize glycogen and lipids stored in trophocytes to survive for 2 weeks and then die after the exhaustion of nutrients in these cells. Endosymbionts are not digested for the recycling of nutrients, but uric acid is reused under starvation.     

Effect of static load on motor behavior of the cockroach Periplaneta americana

Effect of static load on activity of motor centers controlling motor activity (walking flight) was studied in the American cockroach Periplaneta americana L. It has been established that under effect of load on the animal body the relative excitability of these centers increases. A suggestion is put forward about the presence of common neuronal elements in the generator networks providing motor acts in the American cockroach; a role of afferent systems in control of excitability of locomotor centers functioning in the regime of static load is shown.     

Effect of static load on motor behavior of the cockroach Periplaneta americana

Effect of static load on activity of motor centers controlling motor activity (walking, flight) was studied in the American cockroach Periplaneta americana L. It has been established that under effect of load on the animal body the relative excitability of these centers increases. A suggestion is put forward about the presence of common neuronal elements in the generator networks providing motor acts in the American cockroach; a role of afferent systems in control of excitability of loco-motor centers functioning in the regime of static load is shown.     

Characterization and purification of polymorphic arylalkylamine N-acetyltransferase from the American cockroach, Periplaneta americana.

We separated two forms of arylalkylamine N-acetyltransferase (AANAT) from various organs of the American cockroach, Periplaneta americana. Both forms of the enzyme had an equivalent molecular mass of 28 kDa. One form isolated from the testicular accessory glands had high enzyme activity at acidic pHs. The isoelectric point was 5-6 and the substrate specificity was wider than the other type. The other isolated form from female midguts had a higher level of enzyme activity at basic pHs. These findings suggested that P. americana contains polymorphic AANAT, as is the case in Drosophila melanogaster. These forms differed not only in pH specificity, and substrate specificity but in chromatographic behavior and kinetic properties. Most of the organs we examined contained a mixture of the two forms since two types of AANAT activity were separated in different chromatographic fractions when two pH conditions were used for activity measurement.     

Starvation suppresses cell proliferation that rebounds after refeeding in the midgut of the American cockroach, Periplaneta americana

Starvation affects behavior, development, metabolism, reproduction, and longevity in almost all animals including insects. In the American cockroach, Periplaneta americana, we investigated the effect of starvation on organ size and cell proliferation activity of the midgut, over a period of one month, using anti-bromodeoxyuridine (BrdU), and anti-phospho-histone H3 antibodies. Under starvation conditions, the midgut became clear and fragile while its length and diameter were reduced. Both the rate of BrdU-uptake in the nucleus and the mitotic activity shown by anti-phospho-histone H3 antibody decreased under long starvation up to half that of the continuously fed control. Refeeding restored BrdU-uptake and mitosis that overshot the fed control. When casein, starch, or cooking oil was fed as representative nutrient sources to the starved cockroaches, all restored BrdU-uptake, but non-nutrient, talc, did not. This study supports the hypothesis that P. americana has a homeostatic mechanism to regulate the cell population of the midgut epithelium according to changes in the nutritional environment.     

Molecular characterization of American cockroach tropomyosin (Periplaneta americana allergen 7), a cross-reactive allergen

Inhalation of allergens produced by the American cockroach (Periplaneta americana) induces IgE Ab production and the development of asthma in genetically predisposed individuals. The cloning and expression in Escherichia coli of P. americana tropomyosin allergen have been achieved. The protein shares high homology with other arthropod tropomyosins (80% identity) but less homology with vertebrate ones (50% identity). The recombinant allergen was produced in E. coli as a nonfusion protein with a yield of 9 mg/l of bacterial culture. Both natural and recombinant tropomyosins were purified by isoelectric precipitation. P. americana allergen 1 (Per a 1) and Per a 7 (tropomyosin) are to date the only cross-reacting allergens found in cockroaches. ELISA and Western blot inhibition experiments, using natural and recombinant purified tropomyosins from shrimp and cockroach, showed that tropomyosin induced cross-reactivity of IgE from patients allergic to these allergens, suggesting that this molecule could be a common allergen among invertebrates.     

Two new tryptophane metabolites of the American cockroach

In the course of attempts to isolate and characterize the ‘nesting’ or aggregation pheromone of the American cockroach, Periplaneta americana, two metabolites of tryptophane have been identified. These are oxindole and hydrocarbostyril. That these were indeed tryptophane metabolites was demonstrated by administering radiolabelled tryptophane to cockroaches following tetracycline treatment and isolating the radioactive metabolites.     

Selective regulation of sensitivity to odours of different behavioural significance in the American cockroach, Periplaneta americana

Abstract.  Orally supplied octopamine significantly enhances the wing-raising behaviour in male American cockroaches Periplaneta americana , in response to periplanone B the main component of the sex pheromone, but not attraction. In addition, octopamine decreases the response to the general odorant, hexan-1-ol. The presence of a calling female, as well as octopamine treatment, eliminates the avoidance of hexanol by males. Electroantennogram responses to hexan-1-ol decreases after topical octopamine application.     

Opioid involvement in the control of feeding in an insect, the American cockroach

Administration of the kappa opiate agonist, U-50,488H (0.10-10 mg/kg), produced over three hours a significant dose-dependent increase in the ingestive responses of free feeding American cockroaches, Periplaneta americana. These effects could be decreased by the opiate antagonist, naloxone (1.0 mg/kg), with naloxone by itself blocking the augmented feeding responses of food-deprived cockroaches. The mu opiate agonist, morphine (1.0-20 mg/kg) caused a significant dose-dependent and naloxone-reversible increase in the locomotory activity of cockroaches. These results suggest that opioid systems may be involved in the control of the feeding in cockroaches in a manner analogous to that proposed for vertebrates.     

美洲大蠊Per a7基因的克隆、表达及免疫学鉴定

根据原肌球蛋白基因序列设计引物,以我国南方地区美洲大蠊Periplaneta Americana RNA为模板,用RT-PCR方法扩增出852 bp的全长编码片段,经序列分析发现该基因与NCBI公布的Per a7有3个核苷酸发生改变。将目的片段克隆到pET24a(+)表达载体中,在大肠杆菌BL21 Star获得表达,融合蛋白的分子量约为33 kD。利用蟑螂过敏性患者血清对表达产物进行Western blotting检测,出现明显的识别条带,说明表达产物具有IgE结合活性。     

Cloning of PaAtg8 and roles of autophagy in adaptation to starvation with respect to the fat body and midgut of the Americana cockroach,Periplaneta americana

Starvation, in particular amino acid deprivation, induces autophagy in trophocytes (adipocytes), the major component of the fat body cell types, in the larvae of Drosophila melanogaster. However, the fat body of cockroach has two additional cell types: urocytes depositing uric acid in urate vacuoles as a nitrogen resource and mycetocytes harboring an endosymbiont, Blattabacterium cuenoti, which can synthesize amino acids from the metabolites of the stored uric acid. These cells might complement the roles of autophagy in recycling amino acids in the fat body or other organs of cockroaches under starvation. We investigate the presence of autophagy in tissues such as the fat body and midgut of the American cockroach, Periplaneta americana, under starvation by immunoblotting with antibody against Atg8, a ubiquitin-like protein required for the formation of autophagosomes and by electron microscopy. Corresponding changes in acid phosphatase activity were also investigated as representing lysosome activity. Starvation increased the level of an autophagic marker, Atg8-II, in both the tissues, extensively stimulating the formation of autophagic compartments in trophocytes of the fat body and columnar cells of the midgut for over 2 weeks. Acid phosphatase showed no significant increase in the fat body of the starved cockroaches but was higher in the midgut of the continuously fed animals. Thus, a distinct autophagic mechanism operates in these tissues under starvation of 2 weeks and longer. The late induction of autophagy implies exhaustion of the stored uric acid in the fat body. High activity of acid phosphatase in the midgut of the fed cockroaches might represent enhanced assimilation and not an autophagy-related function.     

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.