Production and Release of Proinflammatory Mediators by the Cockroach Allergen Bla g 1 via a Shared Membrane-Destabilization Mechanism.

The cockroach allergen Bla g 1 encloses an exceptionally large hydrophobic cavity, which allows it to bind and deliver unsaturated fatty acid ligands. Bla g 1-mediated delivery of naturally occurring (nMix) ligands has been shown to destabilize lipid membranes, contributing to its digestive/antiviral functions within the source organism. However, the consequences of this activity on Bla g 1 allergenicity following human exposure remain unknown. In this work, we show that Bla g 1-mediated membrane disruption can induce a proinflammatory immune response in mammalian cells via two complementary pathways. At high concentrations, the cytotoxic activity of Bla g 1 induces the release of proinflammatory cytosolic contents including damage-associated molecular patterns (DAMPs) such as heat-shock Protein-70 (HSP70) and the cytokine interleukin-1 (IL-1ß). Sublytic concentrations of Bla g 1 enhanced the ability of phospholipase A2 (PLA2) to extract and hydrolyze phospholipid substrates from cellular membranes, stimulating the production of free polyunsaturated fatty acids (PUFAs) and various downstream inflammatory lipid mediators. Both of these effects are dependent on the presence of Bla g 1's natural fatty-acid (nMix) ligands with CC50 values corresponding to the concentrations required for membrane destabilization reported in previous studies. Taken together, these results suggest that mechanisms through which Bla g 1-mediated lipid delivery and membrane destabilization could directly contribute to cockroach allergic sensitization.

Comparative analysis of adipokinetic hormones and their receptors in Blattodea reveals novel patterns of gene evolution.

Adipokinetic hormone (AKH) is a neuropeptide produced in the insect corpora cardiaca that plays an essential role in mobilising carbohydrates and lipids from the fat body to the haemolymph. AKH acts by binding to a rhodopsin-like G protein-coupled receptor (GPCR), the adipokinetic hormone receptor (AKHR). In this study, we tackle AKH ligand and receptor gene evolution as well as the evolutionary origins of AKH gene paralogues from the order Blattodea (termites and cockroaches). Phylogenetic analyses of AKH precursor sequences point to an ancient AKH gene duplication event in the common ancestor of Blaberoidea, yielding a new group of putative decapeptides. In total, 16 different AKH peptides from 90 species were obtained. Two octapeptides and seven putatively novel decapeptides are predicted for the first time. AKH receptor sequences from 18 species, spanning solitary cockroaches and subsocial wood roaches as well as lower and higher termites, were subsequently acquired using classical molecular methods and in silico approaches employing transcriptomic data. Aligned AKHR open reading frames revealed 7 highly conserved transmembrane regions, a typical arrangement for GPCRs. Phylogenetic analyses based on AKHR sequences support accepted relationships among termite, subsocial (Cryptocercus spp.) and solitary cockroach lineages to a large extent, while putative post-translational modification sites do not greatly differ between solitary and subsocial roaches and social termites. Our study provides important information not only for AKH and AKHR functional research but also for further analyses interested in their development as potential candidates for biorational pest control agents against invasive termites and cockroaches.

Different neuroendocrine cell types in the pars intercerebralis of Periplaneta americana produce their own specific IGF-related peptides.

Of the nine genes of the American cockroach, Periplaneta americana, coding for peptides related to insulin and insulin-like growth factor, seven show significant expression in the central nervous system as demonstrated by the polymerase chain reaction on reverse transcribed RNA. In situ hybridisation shows that five of those are expressed by cells in the pars intercerebralis. Antisera raised to the predicted peptides show that these cells are neuroendocrine in nature and project to the corpora cardiaca. Interestingly, there are at least three cell types that each express different genes. This contrasts with Drosophila where a single cell type expresses a number of genes expressing several such peptides. Whereas in Drosophila the neuroendocrine cells producing insulin-like peptides also express sulfakinins, the arthropod orthologs of gastrin and cholecystokinin, in Periplaneta the sulfakinins are produced by different cells. Other neuropeptides known to be produced by the pars intercerebralis in Periplaneta and other insect species, such as the CRF-like diuretic hormone, neuroparsin, leucokinin or myosuppressin, neither colocalize with an insulin-related peptide. The separate cellular localization of these peptides and the existence of multiple insulin receptors in this species implies a more complex regulation by insulin and IGF-related peptides in cockroaches than in the fruit fly.

Metoprolol elicits neurobehavioral insufficiency and oxidative damage in nontarget Nauphoeta cinerea nymphs.

Metoprolol, a drug for hypertension and cardiovascular diseases, has become a contaminant of emerging concern because of its frequent detection in various environmental matrices globally. The dwindling in the biodiversity of useful insects owing to increasing presence of environmental chemicals is currently a great interest to the scientific community. In the current research, the toxicological impact of ecologically relevant concentrations of metoprolol at 0, 0.05, 0.1, 0.25, and 0.5 µg/L on Nauphoeta cinerea nymphs following exposure for 42 consecutive days was evaluated. The insects' behavior was analyzed with automated video-tracking software (ANY-maze, Stoelting Co, USA) while biochemical assays were done using the midgut, head and fat body. Metoprolol-exposed nymphs exhibited significant diminutions in the path efficiency, mobility time, distance traveled, body rotation, maximum speed and turn angle cum more episodes, and time of freezing. In addition, the heat maps and track plots confirmed the metoprolol-mediated wane in the exploratory and locomotor fitness of the insects. Compared with control, metoprolol exposure decreased acetylcholinesterase activity in insects head. Antioxidant enzymes activities and glutathione level were markedly decreased whereas indices of inflammation and oxidative injury to proteins and lipids were significantly increased in head, midgut and fat body of metoprolol-exposed insects. Taken together, metoprolol exposure induces neurobehavioral insufficiency and oxido-inflammatory injury in N. cinerea nymphs. These findings suggest the potential health effects of environmental contamination with metoprolol on ecologically and economically important nontarget insects.

Burkholderia pseudomallei JW270 Is Lethal in the Madagascar Hissing Cockroach Infection Model and Can Be Utilized at Biosafety Level 2 to Identify Putative Virulence Factors.

Burkholderia pseudomallei, the causative agent of melioidosis, is classified by the CDC as a tier 1 select agent, and work involving it must be performed in a biosafety level 3 (BSL-3) laboratory. Three BSL-2 surrogate strains derived from B. pseudomallei 1026b, a virulent clinical isolate, have been removed from the CDC select agent list. These strains, Bp82, B0011, and JW270, are highly attenuated in rodent models of melioidosis and cannot be utilized to identify virulence determinants because of their high 50% lethal dose (LD50). We previously demonstrated that the Madagascar hissing cockroach (MHC) is a tractable surrogate host to study the innate immune response against Burkholderia. In this study, we found that JW270 maintains its virulence in MHCs. This surprising result indicates that it may be possible to identify potential virulence genes in JW270 by using MHCs at BSL-2. We tested this hypothesis by constructing JW270 mutations in genes that are required (hcp1) or dispensable (hcp2) for B. pseudomallei virulence in rodents. JW270 Δhcp1 was avirulent in MHCs and JW270 Δhcp2 was virulent, suggesting that MHCs can be used at BSL-2 for the discovery of important virulence factors. JW270 ΔBPSS2185, a strain harboring a mutation in a type IV pilin locus (TFP8) required for full virulence in BALB/c mice, was also found to be attenuated in MHCs. Finally, we demonstrate that the hmqA-G locus, which encodes the production of a family of secondary metabolites called 4-hydroxy-3-methyl-2-alkylquinolines, is important for JW270 virulence in MHCs and may represent a novel virulence determinant.

Prophenoloxidase of Odontotermes formosanus (Shiraki) (Blattodea: Termitidae) Is a Key Gene in Melanization and Has a Defensive Role during Bacterial Infection.

Melanization mediated by the prophenoloxidase (PPO)-activating system is an important innate immunity to fight pathogens in insects. In this study, the in vitro time-dependent increase in the intensity of melanization and phenoloxidase (PO) activity from the hemolymph of Odontotermes formosanus (Shiraki) challenged by pathogenic bacteria was detected. PPO is one of the key genes in melanization pathway, whereas the molecular characteristics and functions of O. formosanus PPO are unclear. The OfPPO gene was cloned and characterized. The open reading frame of OfPPO is 2085 bp in length and encodes a 79.497 kDa protein with 694 amino acids. A BLASTx search and phylogenetic analyses revealed that OfPPO shares a high degree of homology to the Blattodea PPOs. Moreover, real-time fluorescent quantitative PCR analysis showed that OfPPO is ubiquitously expressed in all castes and tissues examined, with the highest expression in workers and variable expression patterns in tissues of different termite castes. Furthermore, the expression of OfPPO was significantly induced in O. formosanus infected by pathogenic bacteria. Intriguingly, in combination with silencing of OfPPO expression, pathogenic bacteria challenge caused greatly increased mortality of O. formosanus. These results suggest that OfPPO plays a role in defense against bacteria and highlight the novel termite control strategy combining pathogenic bacteria application with termite PPO silencing.

Prodigiosin from Serratia Marcescens in Cockroach Inhibits the Proliferation of Hepatocellular Carcinoma Cells through Endoplasmic Reticulum Stress-Induced Apoptosis.

Hepatocellular carcinoma (HCC) is the most common primary liver malignant tumor, and the targeted therapy for HCC is very limited. Our previous study demonstrated that prodigiosin(PG), a secondary metabolite from Serratia marcescens found in the intestinal flora of cockroaches, inhibits the proliferation of HCC and increases the expression of CHOP, a marker protein for endoplasmic reticulum stress (ERS)-mediated apoptosis, in a dose-dependent manner. However, the mechanisms underlying the activity of PG in vivo and in vitro are unclear. This study explored the molecular mechanisms of PG-induced ERS against liver cancer in vitro and in vivo. The apoptosis of hepatocellular carcinoma cells induced by PG through endoplasmic reticulum stress was observed by flow cytometry, colony formation assay, cell viability assay, immunoblot analysis, and TUNEL assay. The localization of PG in cells was observed using laser confocal fluorescence microscopy. Flow cytometry was used to detect the intracellular Ca2+ concentration after PG treatment. We found that PG could promote apoptosis and inhibit the proliferation of HCC. It was localized in the endoplasmic reticulum of HepG2 cells, where it induces the release of Ca2+. PG also upregulated the expression of key unfolded response proteins, including PERK, IRE1α, Bip, and CHOP, and related apoptotic proteins, including caspase3, caspase9, and Bax, but down-regulated the expression of anti-apoptotic protein Bcl-2 in liver cancer. Alleviating ERS reversed the above phenomenon. PG had no obvious negative effects on the functioning of the liver, kidney, and other main organs in nude mice, but the growth of liver cancer cells was inhibited by inducing ERS in vivo. The findings of this study showed that PG promotes apoptosis of HCC by inducing ERS.

Streptozotocin induces brain glucose metabolic changes and alters glucose transporter expression in the Lobster cockroach; Nauphoeta cinerea (Blattodea: Blaberidae).

The development of new models to study diabetes in invertebrates is important to ensure adherence to the 3R's principle and to expedite knowledge of the complex molecular events underlying glucose toxicity. Streptozotocin (STZ)-an alkylating and highly toxic agent that has tropism to mammalian beta cells-is used as a model of type 1 diabetes in rodents, but little is known about STZ effects in insects. Here, the cockroach; Nauphoeta cinerea was used to determine the acute toxicity of 74 and 740 nmol of STZ injection per cockroach. STZ increased the glucose content, mRNA expression of glucose transporter 1 (GLUT1) and markers of oxidative stress in the head. Fat body glycogen, insect survival, acetylcholinesterase activity, triglyceride content and viable cells in head homogenate were reduced, which may indicate a disruption in glucose utilization by the head and fat body of insects after injection of 74 and 740 nmol STZ per nymph. The glutathione S-transferase (GST) activity and reduced glutathione levels (GSH) were increased, possibly via activation of nuclear factor erythroid 2 related factor as a compensatory response against the increase in reactive oxygen species. Our data present the potential for metabolic disruption in N. cinerea by glucose analogues and opens paths for the study of brain energy metabolism in insects. We further phylogenetically demonstrated conservation between N. cinerea glucose transporter 1 and the GLUT of other insects in the Neoptera infra-class.

Parasitoid Jewel Wasp Mounts Multipronged Neurochemical Attack to Hijack a Host Brain.

The parasitoid emerald jewel wasp Ampulex compressa induces a compliant state of hypokinesia in its host, the American cockroach Periplaneta americana through direct envenomation of the central nervous system (CNS). To elucidate the biochemical strategy underlying venom-induced hypokinesia, we subjected the venom apparatus and milked venom to RNAseq and proteomics analyses to construct a comprehensive "venome," consisting of 264 proteins. Abundant in the venome are enzymes endogenous to the host brain, including M13 family metalloproteases, phospholipases, adenosine deaminase, hyaluronidase, and neuropeptide precursors. The amphipathic, alpha-helical ampulexins are among the most abundant venom components. Also prominent are members of the Toll/NF-κB signaling pathway, including proteases Persephone, Snake, Easter, and the Toll receptor ligand Spätzle. We find evidence that venom components are processed following envenomation. The acidic (pH∼4) venom contains unprocessed neuropeptide tachykinin and corazonin precursors and is conspicuously devoid of the corresponding processed, biologically active peptides. Neutralization of venom leads to appearance of mature tachykinin and corazonin, suggesting that the wasp employs precursors as a prolonged time-release strategy within the host brain post-envenomation. Injection of fully processed tachykinin into host cephalic ganglia elicits short-term hypokinesia. Ion channel modifiers and cytolytic toxins are absent in A. compressa venom, which appears to hijack control of the host brain by introducing a "storm" of its own neurochemicals. Our findings deepen understanding of the chemical warfare underlying host-parasitoid interactions and in particular neuromodulatory mechanisms that enable manipulation of host behavior to suit the nutritional needs of opportunistic parasitoid progeny.

The power of neuropeptide precursor sequences to reveal phylogenetic relationships in insects: A case study on Blattodea.

Recent state-of-the-art analyses in insect phylogeny have exclusively used very large datasets to elucidate higher-level phylogenies. We have tested an alternative and novel approach by evaluating the potential phylogenetic signals of identified and relatively short neuropeptide precursor sequences with highly conserved functional units. For that purpose, we examined available transcriptomes of 40 blattodean species for the translated amino acid sequences of 17 neuropeptide precursors. Recently proposed intra-ordinal relationships of Blattodea, based on the analysis of 2370 protein-coding nuclear single-copy genes (Evangelista et al., 2019), were corroborated with maximum support. The functionally different precursor units were analyzed separately for their phylogenetic information. Although the degree of information was different in the different sequence motifs, all precursor units contained phylogenetic informative data at the ordinal level, and their separate analysis did not reveal contradictory topologies. This study is the first comprehensive exploitation of complete neuropeptide precursor sequences of arthropods in such a context and demonstrates the applicability of these rather short but conserved sequences for an alternative, fast and simple analysis of phylogenetic relationships.

Winner and loser effects in lobster cockroach contests for social dominance.

In the context of animal aggression, the winner/loser effect is a cross-taxa phenomenon. In the present study, the effect of social contest experience on winning and losing subsequent encounters was investigated in the furious male lobster cockroach, Nauphoeta cinerea. Dominant and subordinate individuals were generated as the result of an encounter between two socially naïve males (SNMs); the winner and loser were designated as 1st encounter dominants and 1st encounter subordinates, respectively. With these dominants and subordinates, three experiments were conducted: (I) the original pair met in a re-encounter, (II) the 1st encounter dominants and subordinates were paired with an inexperienced SNM, (III) the 1st encounter dominants and subordinates were paired with an experienced individual of the same rank. Each experiment was conducted at 1 week, 2 weeks, 3 weeks, 4 weeks and 5 weeks after the 1st encounter fight. Juvenile hormone (JH) III titer was monitored in all individuals before and after each subsequent encounter. Our results showed that, in the original pairing and in the pairing with SNMs, the probability that a 1st encounter dominant (or subordinate) would win (or lose) the subsequent encounter fit well with the 95% confidence interval of the theoretical criteria proposed by Begin et al. (1969), indicating the existence of the winning/losing effect. However, this effect was inconsistent along the five-week observation period. For all 1st encounter dominants, at each week after the 1st encounter, the before subsequent encounter JH III titers distribution was significantly different from that on the 1st encounter day; the distributions of before subsequent encounter JH III titers could be further clustered into two groups, the higher JH III group and the lower JH III group, which were significantly correlated with subsequent winning and losing, respectively. For the 1st encounter subordinates, the distributions of before subsequent encounter JH III titers were not significantly different from that of SNMs, but the titer distributions were significantly shifted to a higher level compared to the 1st encounter day. Compared with before subsequent encounter, the after subsequent encounter hemolymph JH III level was significantly increased in winners and significantly decreased in losers. From these data, we propose that instability of the winner and loser effects may occur due to physiological costs and recovery; this instability may partly explain why the social hierarchy is unstable in this cockroach species.

Photoperiod-dependent release of suppression pheromone in the male lobster cockroach Nauphoeta cinerea.

The complex agonistic repertoire between male lobster cockroaches (Nauphoeta cinerea) makes this species an excellent model for aggression studies. During the establishment of dominance hierarchies, 3-hydroxy-2-butanone (3H-2B) functions as a suppression pheromone, keeping the rivals in a submissive state. In the present study, we evaluated the release of 3H-2B by dominant individuals across four different time phases within the 24-h photoperiod, i.e., early scotophase (ES), late scotophase (LS), early photophase (EP), and late photophase (LP). For each time phase, we collected volatile pheromones during a 60-min first-encounter fight to measure the level of released 3H-2B. Subsequently, the amount of 3H-2B remaining in the sternal glands of dominant and subordinate individuals was measured and compared to socially naïve male controls. Release of 3H-2B was relatively high during ES or LP first-encounter fights, compared to LS or EP encounters. The attack duration and aggressive posture intensity in dominant males were positively correlated with the amount of 3H-2B release in all four phases. A similar statistical distribution was found between the amount of 3H-2B released by dominant males and the amount of 3H-2B in the sternal glands of naïve male sternal during LS, EP, and LP. However, during ES, the statistical distribution of 3H-2B released by the dominant was significantly greater than the distribution of 3H-2B content in socially naïve male sternal glands. The observed phase-dependence of 3H-2B release might be due to variations in 3H-2B biosynthesis or the scotophase-specific behavior of naïve males, wherein an aggressive posture is spontaneously adopted with concomitant 3H-2B release.

Cryptochrome 2 mediates directional magnetoreception in cockroaches.

The ability to perceive geomagnetic fields (GMFs) represents a fascinating biological phenomenon. Studies on transgenic flies have provided evidence that photosensitive Cryptochromes (Cry) are involved in the response to magnetic fields (MFs). However, none of the studies tackled the problem of whether the Cry-dependent magnetosensitivity is coupled to the sole MF presence or to the direction of MF vector. In this study, we used gene silencing and a directional MF to show that mammalian-like Cry2 is necessary for a genuine directional response to periodic rotations of the GMF vector in two insect species. Longer wavelengths of light required higher photon fluxes for a detectable behavioral response, and a sharp detection border was present in the cyan/green spectral region. Both observations are consistent with involvement of the FADox, FAD(•-) and FADH(-) redox forms of flavin. The response was lost upon covering the eyes, demonstrating that the signal is perceived in the eye region. Immunohistochemical staining detected Cry2 in the hemispherical layer of laminal glia cells underneath the retina. Together, these findings identified the eye-localized Cry2 as an indispensable component and a likely photoreceptor of the directional GMF response. Our study is thus a clear step forward in deciphering the in vivo effects of GMF and supports the interaction of underlying mechanism with the visual system.

Cloning, Expression and Effects of P. americana Thymosin on Wound Healing.

The American cockroach (Periplaneta americana) is a medicinal insect. Its extract is used clinically to promote wound healing and tissue regeneration, but the effective medicinal components and mechanisms are not yet clear. It has been reported that human thymosin beta 4 (Tß4) may accelerate skin wound healing, however, the role of P. americana thymosin (Pa-THYs) is still poorly understood. In the present study, we identify and analyze the DNA sequences of Pa-THYs by bioinformatics analysis. Then we clone, express, and purify the Pa-THYs proteins and evaluate the activity of recombinant Pa-THYs proteins by cell migration and proliferation assays in NIH/3T3 cells. To elucidate the role of Pa-THYs in wound healing, a mouse model is established, and we evaluate wound contraction, histopathological parameters, and the expressions of several key growth factors after Pa-THYs treatment. Our results showed that three THY variants were formed by skipping splicing of exons. Pa-THYs could promote fibroblast migration, but have no effect on fibroblast proliferation. In wound repair, Pa-THYs proteins could effectively promote wound healing through stimulating dermal tissue regeneration, angiogenesis, and collagen deposition. On the molecular mechanism, Pa-THYs also stimulated the expression of several key growth factors to promote wound healing. The data suggest that Pa-THYs could be a potential drug for promoting wound repair.

Entomotoxic activity of Rhinella icterica (Spix, 1824) toad skin secretion in Nauphoeta cinerea cockroaches: An octopamine-like modulation.

Rhinella icterica is a poisonous toad whose toxic secretion has never been studied against entomotoxic potential. Sublethal doses of Rhinella icterica toxic secretion (RITS) were assayed in Nauphoeta cinerea cockroaches, in order to understand the physiological and behavioral parameters, over the insect central and peripheral nervous system. RITS (10 µg/g) injections, induced behavioral impairment as evidenced by a significant decrease (38 ±â€¯14%) in the distance traveled (p < .05), followed by an increase (90 ±â€¯6%) of immobile episodes (p < .001, n = 28, respectively). In cockroaches semi-isolated heart preparations, RITS (16 µg/200 µl) induced a significant irreversible dose-dependent negative chronotropism, reaching ~40% decrease in heart rate in 20 min incubation. In in vivo cockroach neuromuscular preparations, RITS (20, 50 and 100 µg/g of animal weight) induced a time-dependent inhibition of twitch tension that was complete for 20 µg/g, in 120 min recordings. RITS (10 µg/g) also induced a significant increase in the insect leg grooming activity (128 ±â€¯10%, n = 29, p < .01), but not in the antennae counterparts. The RITS increase in leg grooming activity was prevented in 90% by the pretreatment of cockroaches with phentolamine (0.1 µg/g). The electrophysiological recordings of spontaneous neural compound action potentials showed that RITS (20 µg/g) induced a significant increase in the number of events, as well as in the rise time and duration of the potentials. In conclusion, RITS showed to be entomotoxic, being the neuromuscular failure and cardiotoxic activity considered the main deleterious effects. The disturbance of the cockroaches' behavior together with the electrophysiological alterations, may unveil the presence of some toxic components present in the poison with inherent biotechnological potentials.

Ecdysone signalling and ovarian development in insects: from stem cells to ovarian follicle formation.

Although a great deal of information is available concerning the role of ecdysone in insect oogenesis, research has tended to focus on vitellogenesis and choriogenesis. As such, the study of oogenesis in a strict sense has received much less attention. This situation changed recently when a number of observations carried out in the meroistic polytrophic ovarioles of Drosophila melanogaster started to unravel the key roles played by ecdysone in different steps of oogenesis. Thus, in larval stages, a non-autonomous role of ecdysone, first in repression and later in activation, of stem cell niche and primordial germ cell differentiation has been reported. In the adult, ecdysone stimulates the proliferation of germline stem cells, plays a role in stem cell niche maintenance and is needed non-cell-autonomously for correct differentiation of germline stem cells. Moreover, in somatic cells ecdysone is required for 16-cell cyst formation and for ovarian follicle development. In the transition from stages 8 to 9 of oogenesis, ecdysone signalling is fundamental when deciding whether or not to go ahead with vitellogenesis depending on the nutritional status, as well as to start border cell migration. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

Synthesis and biological activity of FGLamide allatostatin analogs with Phe(3) residue modifications.

A FGLamide allatostatin neuropeptide mimic (H17) is a potential insect growth regulator which inhibits the production of juvenile hormone by the corpora allata. To find more evidence to reveal the structure-activity relationships of the Phe(3) residue in the C-terminal conserved pentapeptide and search for novel analogs with high activity, a series of Phe(3) residue-modified analogs were designed and synthesized using H17 as the lead compound. Bioassay using juvenile hormone (JH) production by corpora allata of the cockroach Diploptera punctata indicated that analogs 4, 11, and 13 showed strong ability to inhibit JH production in vitro, with IC50 of 38.5, 22.5, and 26 nM, respectively. As well, the activity of analog 2 (IC50 : 89.5 nM) proved roughly equivalent to that of H17. Based on the primary structure-activity relationships of Phe(3) residue, we suggest that for analogs containing six-membered aromatic rings, removing the methylene group of Phe(3) or an o-halogen or p-halogen-substituted benzene ring could increase the ability to inhibit biosynthesis of JH. This study will be useful for the design of new allatostatin analogs for insect management. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

Neurobehavioral and biochemical changes in Nauphoeta cinerea following dietary exposure to chlorpyrifos.

The present study aimed to increase our understanding about the mode of toxic action of organophosphate pesticides in insects by evaluating the biochemical and neurobehavioral characteristics in Nauphoeta cinerea exposed to chlorpyrifos (CPF)-contaminated diet. The insects were exposed for 35 consecutive days to CPF at 0.078, 0.15625, 0.3125 and 0.625µg/g feed. Locomotor behavior was assessed for a 10-min trial in a novel arena and subsequently, biochemical analyses were carried out using the cockroaches' heads. In comparison to control, CPF-exposed cockroaches showed significant decreases in the total distance traveled, body rotation, turn angle and meandering, along with significant increase in the number of falls, time and episodes of immobility. The marked decrease in the exploratory profiles of CPF-exposed cockroaches was confirmed by track plots, whereas occupancy plot analyses showed a progressive dispersion at 0.15625µg/g feed group. Moreover, the heads of CPF-exposed cockroaches showed marked decrease in acetylcholinesterase activity and antioxidant status with concomitant significant elevation in dichlorofluorescein oxidation and lipid peroxidation levels in CPF-treated cockroaches. Gas Chromatography-Mass Spectrometry analyses revealed bioaccumulation of CPF in cockroaches exposed to concentrations above 0.078µg/g feed. The findings from this investigation showed N. cinerea as a value model organism for the risk assessment of environmental organophosphate contamination in insects.

FoxO is required for the activation of hypertrehalosemic hormone expression in cockroaches.

BACKGROUND: FoxO proteins are a subgroup of the Forkhead-box family of transcription factors, which function as the main transcriptional effectors of the insulin receptor pathway. This pathway, activated by the binding of insulin or IGFs (or insect insulin-like peptides), promotes the phosphorylation and inactivation of FoxO because of its export from the nucleus to the cytoplasm. The homolog of FoxO in the cockroach Blattella germanica works in a situation of nutrient shortage by inhibiting the endocrine induction of reproduction. METHODS: Using Blattella germanica as a model, we studied the functions of FoxO using RNA interference methodologies. We analyzed the mRNA levels of hypertrehalosemic hormone (HTH) and genes related to lipolysis, glycogenolysis and gluconeogenesis and quantified triacylglycerides, glycogen and trehalose. RESULTS: FoxO knockdown eliminates the starvation-induced expression of HTH in the corpora cardiaca. In addition, FoxO knockdown prevents the activation of the expression of Brummer lipase, glycogen phosphorylase and phosphoenolpyruvate carboxylase in the fat body of starved females. CONCLUSIONS: Starvation-induced activation of FoxO stimulates the transcription of different genes related to catabolic processes, including HTH and genes involved in lipolysis, glycogenolysis and gluconeogenesis. GENERAL SIGNIFICANCE: Our results show conservation in the action of the transcription factor FoxO in the activation of catabolic processes from basal insects to vertebrates. The results also describe a new and essentially different mode of action of transcription factor FoxO, which works through the activation of neuropeptide HTH expression, which will subsequently produce its own catabolic stimulatory function.

Brain-midgut cross-talk and autocrine metabolastat via the sNPF/CCAP negative feed-back loop in the American cockroach, Periplaneta americana.

Immunohistochemical reactivities against short neuropeptide F (sNPF-ir) and crustacean cardioactive peptide (CCAP-ir) were detected in both the brain-subesophageal ganglion (Br-SOG) and midgut epithelial cells of the male American cockroach, Periplaneta americana. Four weeks of starvation increased the number of sNPF-ir cells and decreased the CCAP-ir cells in the Br-SOG, whereas refeeding reversed these effects. The contents of sNPF in the Br-SOG, midgut and hemolymph titer decreased in response to an injection of CCAP into the hemocoel of normally fed male cockroaches, while CCAP titers/contents decreased in response to an injection of sNPF. The results of a double-labeling experiment demonstrated that sNPF-ir co-existed in CCAP-ir cells in the pars intercerebralis (PI), dorsolateral region of protocerebrum (DL), deutocerebrum (De) and SOG. sNPF-ir and CCAP-ir were also colocalized in the midgut. sNPF and CCAP are neuropeptides and midgut factors that interact with each other. Since the two peptides are known to be secreted by identical cells that affect each other, this constitutes autocrine negative feedback regulation for a quick response to food accessibility/inaccessibility. These peptides not only constitute the switch in the digestive mechanism but also couple digestive adaptation with behavior. A CCAP injection suppressed locomotor activity when cockroaches were starved, whereas sNPF activated it when they were fed.