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1.
Abstract. . 3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase and HMG-CoA reductase show coordinated regulation in the fat body of Blattella germanica females. Since the profile of activity is parallel to the cycle of vitellogenin production, we postulated a link between the mevalonate pathway and vitellogenesis. Here we have studied both enzymes in females of B.germanica modified by ovariectomy (which leads to a saturable accumulation of vitellogenin) and allatectomy (which supresses vitellogenesis). Protein levels and enzymatic activity for both enzymes in ovariectomized specimens rose early in the first days of imaginal life and remained high until the end of the period studied, whereas controls showed cyclic profiles. In allatectomized specimens the same parameters were measured on day 4 of adult life and values were much lower with respect to controls. The parallelism between the patterns of HMG-CoA synthase and reductase, and that of vitellogenin, suggests a functional relationship between the mevalonate pathway and the glycosylation of vitellogenin through dolichol intermediates.  相似文献   

2.
Ecdysteroids play a major role during developmental growth in insects. The more active form of these hormones, 20-hydroxyecdysone (20E), acts upon binding to its heterodimeric receptor, formed by the two nuclear receptors, EcR and RXR/USP. Functional characterization of USP has been exclusively conducted on the holometabolous insect Drosophila melanogaster. However, it has been impossible to extend such analysis to primitive-hemimetabolous insects since species of this group are not amenable to genetic analysis. The development of methodologies based on gene silencing using RNA interference (RNAi) after treatment with double-stranded RNA (dsRNA) in vivo has resolved such limitations. In this paper, we show that injection of dsRNA into the haemocoel of nymphs and adults of the cockroach Blattella germanica can be used to silence gene function in vivo. In our initial attempt to test RNAi techniques, we halted the expression of the adult-specific vitellogenin gene. We then used the same technique to silence the expression of the B. germanica RXR/USP (BgRXR) gene in vivo during the last nymphal instar. BgRXR knockdown nymphs progressed through the instar correctly but they arrested development at the end of the stage and were unable to molt into adults. The results described herein suggest that RXR/USP function, in relation to molting, is conserved across the insect Class.  相似文献   

3.
Gregarines are enteric parasites of invertebrates but little is known about the negative effects of this parasitism on host species. The present study evaluates the influence of the parasitism of Gregarina sp. on the survival of Blattella germanica and methods for elimination of gregarine infection in laboratory rearing systems. Insects were dissected and the infection was detected in 80% of a sample of 50 adults. Diseased cockroaches had swollen abdomens, slower movement at high incidences of the protozoan, and short antennas. Dead cockroaches showed darkened body and putrid smell, indicating septicaemia. Infected insects were more susceptible than healthy cockroaches when treated with Metarhizium anisopliae and triflumuron.  相似文献   

4.
Several lines of evidence point to leucomyosuppressin (LMS) and myosuppressin-related peptides as inhibitory modulators of heartbeat frequency in arthropods. Previous studies in Blattella germanica demonstrated that heartbeat frequency decreases after ootheca formation, and remains low during the period of ootheca transport. Subsequent work in this cockroach resulted in the characterization of LMS and the cloning and sequencing of its precursor. The present paper describes the activity of LMS on modulation of heartbeat in B. germanica. Assays using semi-isolated heart preparations revealed that LMS reduces heartbeat frequency in a dose dependent manner, at physiological concentrations. Additional experiments showed that LMS inhibits heartbeat rates in vivo. Finally, injection of dsRNA for LMS elicited a decrease in LMS mRNA to virtually undetectable levels and heartbeat frequency increased significantly in females carrying oothecae. These data suggest that LMS contributes to the modulation of cardiac rhythm in B. germanica during the reproductive cycle.  相似文献   

5.
6.
In this study, the trypsin gene (bgtryp-1) from the German cockroach, Blattella germanica, was cloned via the immunoscreening of patients with allergies to cockroaches. Nucleotide sequence analysis predicted an 863 bp open reading frame which encodes for 257 amino acids. The deduced amino acid sequence exhibited 42-57% homology with the serine protease from dust mites, and consisted of a conserved catalytic domain (GDSGGPLV). bgtryp-1 was determined by both Northern and Southern analysis to be a 0.9 kb, single-copy gene. SDS-PAGE and Western blotting analyses of the recombinant protein (Bgtryp-1) over-expressed in Escherichia coli revealed that the molecular mass of the expressed protein was 35 kDa, and the expressed protein was capable of reacting with the sera of cockroach allergy patients. We also discussed the possibility that trypsin excreted by the digestive system of the German cockroach not only functions as an allergen, but also may perform a vital role in the activation of PAR-2.  相似文献   

7.
In hemimetabolous insects, the molecular basis of the 20-hydroxyecdysone (20E)-triggered genetic hierarchy is practically unknown. In the cockroach Blattella germanica, we had previously characterized one isoform of the ecdysone receptor, BgEcR-A, and two isoforms of its heterodimeric partner, BgRXR-S and BgRXR-L. One of the early-late genes of the 20E-triggered genetic hierarchy, is HR3. In the present paper, we report the discovery of three isoforms of HR3 in B. germanica, that were named BgHR3-A, BgHR3-B(1) and BgHR3-B(2). Expression studies in prothoracic gland, epidermis and fat body indicate that the expression of the three isoforms coincides with the peak of circulating ecdysteroids at each nymphal instar. Experiments in vitro with fat body tissue have shown that 20E induces the expression of BgHR3 isoforms, and that incubation with 20E and the protein inhibitor cycloheximide does not inhibit the induction, which indicates that the effect of 20E on BgHR3 activation is direct. This has been further confirmed by RNAi in vivo of BgEcR-A, which has shown that this nuclear receptor is required to fully activate the expression of BgHR3. RNAi has been also used to demonstrate the functions of BgHR3 in ecdysis. Nymphs with silenced BgHR3 completed the apolysis but were unable to ecdyse (they had duplicated and superimposed the mouth parts, the hypopharinge, the tracheal system and the cuticle layers). This indicates that BgHR3 is directly involved in ecdysis. Finally, RNAi of specific isoforms has showed that they are functionally redundant, at least regarding the ecdysis process.  相似文献   

8.
The discontinuous gas exchange cycle (DGC) was described in the German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae) for the first time. Also, the effect of the DGC on water loss was investigated. The CO(2) emission pattern in both insecticide resistant and susceptible B. germanica varied with temperature. At 10, 15, and 20 degrees C the pattern was discontinuous. Cycle frequency increased at 25 and 30 degrees C, and at 35 degrees C the pattern became cyclic. In most DGCs, there was no clear distinction between the closed and flutter phases in both strains thus data for these phases were combined and analyzed as the interburst phase. The probability that B. germanica would breath discontinuously varied with temperature. Most cockroaches (62.8%) displayed DGCs at 10 degrees C, therefore measurement of metabolic rate and water loss was carried out at this temperature. Using repeated measures of analysis of variance, the interburst and burst V(.)(CO(2))(ml h(-1)) were not significantly different between the two strains. The variability in CO(2) emission during the interburst and burst phases over time was not significantly different from cycle to cycle or between strains. Overall metabolic rate during the entire recording was not significantly different between both strains. There was a significant difference in the duration of the interburst and burst phases between the strains. The susceptible strain had significantly longer interburst and burst phase durations during a complete DGC than the resistant strain. The interburst and burst phase durations were 5.01+/-0.19 and 6.21+/-0.13 min, respectively, for the resistant strain, whereas the durations were 7.16+/-0.37 and 6.73+/-0.17 min, respectively, for the susceptible strain. This resulted in a DGC of significantly longer duration (13.89+/-0.44 min) in the susceptible strain compared with the resistant strain (11.23+/-0.26 min). The duration of the interburst phase was significantly different from the open phase duration in the resistant strain such that during a single DGC lasting approximately 11.23 min, 43.5% consisted of the interburst phase while the burst phase made up 56.5% of the cycle. The cuticular permeability at 10 degrees C and 0% RH was 2.26 microg cm(-2) h(-1) mmHg(-1) for the resistant strain and 3.42 microg cm(-2) h(-1) mmHg(-1) for the susceptible strain. In both strains, cuticular transpiration accounted for approximately 95% of total water loss. The significantly longer duration of the interburst phase of the susceptible strain was not important in reducing water loss.  相似文献   

9.
The molecular basis of ecdysteroid function during development has been analyzed in detail in holometabolous insects, especially in Drosophila melanogaster, but rarely in hemimetabolous. Using the hemimetabolous species Blattella germanica (German cockroach) as model, we show that the ecdysone receptor isoform-A (BgEcR-A) mRNA is present throughout the penultimate and last nymphal instars in all tissues analyzed (prothoracic gland, epidermis and fat body). To study the functions of BgEcR-A, we reduced its expression using systemic RNAi in vivo, and we obtained knockdown specimens. Examination of these specimens indicated that BgEcR-A during the last nymphal instar is required for nymphal survival, and that reduced expression is associated with molting defects, lower circulating ecdysteroid levels and defects in cell proliferation in the follicular epithelium. Some BgEcR-A knockdown nymphs survive to the adult stage. The features of these specimens indicate that BgEcR-A is required for adult-specific developmental processes, such as wing development, prothoracic gland degeneration and normal choriogenesis.  相似文献   

10.
11.
Food consumption was measured in an insecticide-susceptible (Orlando) and-resistant (Village Green) strain of German cockroach, Blattella germanica (Dictyoptera: Blattellidae), throughout each stadium. All instars exhibited a similar pattern of consumption over the course of the instar; consumption was low to moderate at the beginning of each instar, climbed steadily to a maximum near the middle, declined progressively from the mid-instar maximum, and ceased or was minimal several days before the next molt. Consumption ceased or was minimal during the final two to four days of each instar. Cumulative consumption for the six instars was significantly greater in the Village Green strain as compared with the Orlando strain. Village Green nymphs consumed 79.6±0.7 mg of rat chow while Orlando nymphs consumed 63.7±3.4 mg. Total consumption by instar increased significantly with each successive instar in the Village Green strain. In addition, Village Green sixth instar females consumed significantly more food than sixth instar males. A similar trend was observed for the Orlando strain; consumption tended to increase in each successive instar. Relative consumption rate (food consumed/cockroach/instar divided by the mean weight of the instar) was highest in the first two instars and decreased in subsequent instars.  相似文献   

12.
Mukha  D. V.  Schal  K. 《Molecular Biology》2003,37(4):513-523
A new Blattella germanica densovirus (BgDNV, Parvoviridae: Densovirinae, Densovirus) was found. Virus DNA and cockroach tissues infected with BgDNV were examined by electron microscopy. Virus particles about 20 nm in diameter were observed both in the nucleus and in the cytoplasm of infected cells. Virus DNA proved to be a linear molecule sized about 1.2 m. The complete BgDNV genome was sequenced and analyzed. Five ORF were detected: two coded for structural capsid proteins and were on one DNA strand, and three coded for regulatory proteins and were on the other strand. Potential promoters and polyadenylation signals were identified. Structural analysis was performed for terminal inverted repeats containing extended palindromes. The genome structure of BgDNV was compared with that of other Parvoviridae.  相似文献   

13.
A population of Blattella germanica L. (Dictyoptera) cockroaches was studied in a swimming-bath. Trapped adults were marked and released in their capture area.The overall recapture rate was 15%, but it varied according to the capture area. This rate was higher in the toilets than around the pool borders. Distances between capture and recapture points also varied. Recaptures were more frequent in the capture area than in other areas; only 15% of the animals left their initial area. Movements occurred mainly between neighbouring areas. Recaptures in the capture area were lower around the large pool than around the shallow pool and in the toilets.In conclusion, there were three types of areas which were differently occupied. This could be explained by variations of resources like shelter and food. The complexity of the environmental structure favoured development of cockroach populations although they were able to modify their behavior in relation to the environmental features.
Résumé Une population de Blattes (Blattella germanica) a été étudiée dans l'enceinte d'une piscine par des piégeages hebdomadaires. Les animaux adultes sont marqués et relachés dans leur zone de capture initiale.Le taux de recapture total est de 15%; mais on observe des differences en fonction de la zone de capture. Le taux de recapture est plus élevé dans les toilettes qu'en bordure des bassins. Par contre les distances entre capture et recapture y sont plus faibles.D'autre part, le taux de recapture est plus élevé dans la zone de capture initiale: seulement 15% des animaux changent de zone. Les déplacements ont lieu principalement entre deux zones voisines. Les recaptures dans la zone d'origine sont meilleures autour du petit bassin et dans les toilettes qu'autour du grand bassin.D'après ces résultats, il est possible de distinguer trois types de zone qui présentent un taux d'occupation plus ou moins élevé. Le taux d'occupation dans ces trois zones pourrait être lié à l'abondance des ressources telles que la nourriture et les abris. L'augmentation de la complexité de la structure du milieu qui augmente le nombre d'abris potentiels semble favoriser le développement des populations de Blattes. Celles-ci sont cependant capables d'adapter leur comportement avec les caractéristiques du milieu et de l'exploiter au mieux.
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14.
Tropomyosins derived from invertebrates are well-known pan allergens. However, the allergenicities of recombinant tropomyosins are variable. Here, we undertook to compare the IgE-binding reactivities of native and recombinant German cockroach tropomyosins. Native tropomyosin was purified by ammonium sulfate fractionation, hydroxyapatite column chromatography, and electroelution, and recombinant tropomyosin was expressed in Pichia pastoris. The allergenicities of the native and recombinant tropomyosins were compared by ELISA inhibition analysis. Native German cockroach tropomyosin showed 18% IgE-binding reactivity to German cockroach sensitized sera. Recombinant tropomyosin was produced without fusion protein and its N-terminus was blocked like that of the native counterpart. The IgE-binding reactivity of the recombinant was found to be comparable to that of native tropomyosin over the concentration range 1-1000 ng/ml by ELISA inhibition testing. Recombinant German cockroach tropomyosin expressed in Pichia pastoris showed better allergenicity than that expressed in Escherichia coli. Other factors in addition to the structural differences of native and recombinant proteins may also influence the IgE reactivities of tropomyosins.  相似文献   

15.
Virgin German cockroach females, Blattella germanica(L.), were observed, for the first time, to exhibit a characteristic calling behavior during which females emit a volatile sex pheromone. Under a photoperiod of 12L12D, the percentage of 7-day-old virgin females that exhibited this behavior peaked before the end of the scotophase in a similar pattern to the diel periodicity of mating. A clear relationship was evident between calling and stages of sexual receptivity during successive gonotrophic cycles. Females initiated calling 5–6 days after the imaginal molt, when their basal oocytes were 1.6 mm long. If not mated, females continued to exhibit bouts of calling during the next 3–4 days until 24 h before ovulation. Calling was completely suppressed by mating as well as the presence of an egg case in the genital atrium in both virgin and mated gravid females. We suggest that calling and the emission of a volatile sex pheromone serve to attract males from a distance as well as to potentiate responses to contact sex pheromone in aggregations.  相似文献   

16.
3-Hydroxy-3-methylglutaryl-CoA reductase (EC 1.1.1.34), the major rate-limiting enzyme of cholesterogenesis, was studied in epithelial cells isolated in a villus to crypt gradient from chick duodenum, jejunum and ileum, in order to resolve the apparent controversy that exists on the anatomical localization of sterol synthesis in the intestine. Consistent separation was demonstrated by using the marker enzymes alkaline phosphatase, specific to the villus cells, and thymidine kinase, specific to the crypt cells. No relative difference in stability was observed, as shown by the equal distribution of acid phosphatase. Cells were 90-95 per cent viable. The highest specific activity of reductase was located in the microsomal fraction (41 per cent of the total). The mitochondria had lower specific activity (8 per cent of the total). The distribution of reductase activity in epithelial cells of the villus-crypt axis was also studied. The specific activity in each cell fraction from chick duodenum was clearly lower than that in jejunum and ileum. The jejunal and ileal crypt regions showed lower specific activity than the villus cells. About 70 per cent of total reductase activity was found in cells from the upper and the mid villus fraction in each intestinal segment.  相似文献   

17.
Kulshrestha  Vandana  Pathak  S.C. 《Mycopathologia》1997,139(2):75-78
Natural infection of Aspergillus flavus was observed in adults of Blattella germanica. Though the adult insects exhibited no external symptoms, they became hypoactive and later died. The dead and experimentally infected insects repeatedly yielded Aspergillus flavus in culture on Czapek's medium. Direct microscopic observation of the tissues of infected insects revealed fungal material. The blood films stained with Giemsa stain showed granulocytes (GRs) engulfing fungal hyphae. A remarkable increase in GR and plasmatocyte (PL) counts occurred in differential haemocyte counts (DHCs) of the infected insects. Two main types of immunological responses of the insect noticed were phagocytosis and encapsulation. DHC showed maximum involvement of GRs and PLs in immune mechanism. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

18.
A population of Blattella germanica L. was studied in a swimming-bath facility using a sampling method. A set of traps deposited weekly, over a period of 50 weeks, allowed us to follow the variations of the temporal and spatial distributions of the population inside the building. A Factorial Correspondance Analysis, performed on the data, led us to the conclusion that the population was stable in time. The spatial distribution of the insects was contiguous. Inside an aggregate, we were able to define a circular movement from the center towards the periphery and vice versa; this movement can be superimposed up on the biological development on the individuals. After birth in the middle of the aggregate, during development, larvae explore further a field as far as the border of the aggregate; this exploratory phase, related to foraging behavior or search for new shelters when these become limiting factors, could be considered as the spreading phase of the population. Then, with the imminence of the imaginal moult, old larvae tend to gather in high density areas in the middle of the aggregate. Newly molted adults look for a sexual partner. And finally females remain in the shelters during oothecae maturation.
Résumé L'étude d'une population de Blattella germanica L. dans une piscine par des piégeages hebdomadaires pendant une période de 50 semaines, nous a permis de suivre l'évolution spatiale et temporelle de cette population. Les résultats des piégeages étudiés par Analyse Factorielle des Correspondances nous permettent de conclure à une certaine stabilité temporelle de la population. Elle se répartit en larges agrégats dans lesquels s'inscrit un mouvement circulaire, allant du centre vers la périphérie et retour, qui se superpose au cycle de développement des individus.
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19.
Adult female Blattella germanica (L.) (Dictyoptera: Blattellidae) carrying oothecae were confined in cages with bait formulations of boric acid or hydramethylnon at 90% r.h. and either 20° or 28° C until all had been killed. Females poisoned by hydramethylnon retained their oothecae at death, while a considerable proportion of those killed by boric acid deposited their oothecae prematurely. Oothecae from both groups of insects were monitored until they either hatched or lost viability. Oothecae from both 7–14 day old adults and 14–21 day old adults poisoned with hydramethylnon showed reduced hatching relative to controls at 20° but not at 28 °C, an effect attributed to premature loss of water-exchange between oothecae and female adult during the maturation process. Fewer oothecae hatched from females poisoned with boric acid at both temperatures, and the proportion of those which did hatch was higher in the group retained by the female at death than in the group prematurely deposited. These results for the boric acid-treated females and results which showed no significant difference between the hatch of oothecae from hydramethylnon-treated females and decapitated females suggested that transfer of insecticide from treated female to oothecae was not important in reducing hatch for either compound. Reinfestation as a consequence of the failure of conventional blatticides to prevent hatching of oothecae carried by female B. germanica is discussed.
Résumé Des femelles adultes de B. germanica, maintenues à 20° ou 28° C et 90% HR, ont été exposées, 7 à 14 jours ou 14 à 21 jours après l'émergence à des appâts contenant de l'hydraméthylnone ou de l'acide borique. Empoisonnées par l'hydraméthylnone les femelles retiennent leur oothèque jusqu'à la mort, tandis que empoisonnées par l'acide borique, elles déposent leur oothèque prématurément. Toutes les oothèque des femelles empoisonnées ont été maintenues dans les mêmes conditions écologiques jusqu'à ce qu'elles éclosent ou se révèlent non viables. Avec l'acide borique, une réduction des naissances a été observée pour les oothèques des mères des 2 classes d'âges et aux 2 températures, ce qui n'a eu lieu qu'à la température basse avec l'hydraméthylnone. L'effet ne semble pas dû au transfert de l'insecticide de la femelle à l'oothèque et est plus probablement provoqué par la fin des échanges d'eau entre la mère et l'oothèque, à la mort ou lors de l'émission prématurée. Pour les femelles traitées à l'acide borique, la proportion d'éclosion d'oothèques est plus importante chez les femelles ayant retenu leur oothèque jusqu'à la mort que chez celles qui les ont émises prématurément. Les femelles empoisonnées lors d'opérations d'éradication peuvent mourir ou déposer leurs oothèques loin des zones traitées; les larves éclosant de ces oothèques peuvent maintenir la contamination.
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20.
Glucose-averse (Glu/Glu) male German cockroaches, Blattella germanica, rejected brief exposures to glucose solutions despite food deprivation so extreme as to cause high mortality. In the 24-h period following 5 days of food deprivation, both Glu/Glu and wild-type (+/+) were given a continuous source of 1 M glucose solution. Although Glu/Glu visited the solution as frequently as +/+, feeding bouts were significantly shorter. These truncated feeding bouts were sufficient to extend Glu/Glu longevity to ca. 80 days, regardless of glucose concentration. When provided continuously, the glucose was completely rejected by Glu/Glu for the first 3 days. However, by day 9, glucose intake levels were similar to those of wild-type cockroaches. The initial feeding lag probably accounted for the lower long-term survival of the Glu/Glu vs the +/+ strain. Under the stress of food deprivation, glucose-averse B. germanica modify their feeding behavior toward glucose like many phytophagous insects provided non-host plants in no-choice situations.  相似文献   

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