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ispartof: Physiological Entomology vol:46 issue:1 pages:70-81 status: published

In this work, we solve the Euler’s equations for periodic waves travelling under a sheet of ice using a reformulation introduced in [1]. These waves are referred to as flexural-gravity waves. We compare and contrast two models for the effect of the ice: a linear model and a nonlinear model. The benefit of this reformulation is that it facilitates the asymptotic analysis. We use it to derive the nonlinear Schrödinger equation that describes the modulational instability of periodic travelling waves. We compare this asymptotic result with the numerical computation of stability using the Fourier-Floquet-Hill method to show they agree qualitatively. We show that different models have different stability regimes for large values of the flexural rigidity parameter. Numerical computations are also used to analyse high frequency instabilities in addition to the modulational instability. In the regions examined, these are shown to be the same regardless of the model representing ice.

We conducted a randomized, controlled trial to evaluate different strategies of offering an HPV-self sampling program, and compared this with two control groups. All total of 35,354 women who did not participate in the Flemish cancer screening program were included in the study: 9,118 received a HPV self-collection brush (RIATOL qPCR HPV genotyping test (qPCR [E6/E7]); 9,098 were offered the opportunity to order an HPV-selfsampling brush, 8,830 received the recall letter; 8,849 received no intervention. Within 12 months after the mailing, 18.7% of the women who had received the brush, participated by returning a self-sample sample, while 10.6% women allocated to the opt- in group did so. 10.5% women who received the standard recall letter, had a PAP smear taken within a period of 12 months; while 8% women did so without receiving an intervention at all. Participation in postmenopausal women was higher than in women younger than 50 in both self-sampling arms. Screening by means of the self-sample kit increased by age, contradictory when screening is performed by a PAP smear. Of those testing hrHPV positive (9.5%), 88.9% attended for follow up cytology. The mean DNA concentration, found in the self-sampler, decreased by age, causing a higher number of inconclusive results. Our results support the efficacy of a self-sampling strategy to increase participation in the Flemish screening program. Self-sampling seems particularly acceptable to postmenopausal non-responders. Future research should focus on the performance of different self-sampling devices in post-menopausal women as low DNA concentrations exponentially increased over age.

A stable periodic mesoporous organosilica (PMO) with accessible sulfonic acid functionalities is prepared via a one-pot-synthesis and is used as solid support for highly active catalysts, consisting of gold(I)-N-heterocyclic carbene (NHC) complexes. The gold complexes are successfully immobilized on the nanoporous hybrid material via a straightforward acid-base reaction with the corresponding [Au(OH)(NHC)] synthon. This catalyst design strategy results in a boomerang-type catalyst, allowing the active species to detach from the surface to perform the catalysis and then to recombine with the solid after all the starting material is consumed. This boomerang behavior is assessed in the hydration of alkynes. The tested catalysts were found to be active in the latter reaction, and after an acidic work-up, the IPr*-based gold catalyst can be recovered and then reused several times without any loss in efficiency.

In Tanzania, edible Ruspolia differens are still harvested from the natural environments. In this perspective, little is known about the microbiological quality of wild harvested R. differens. This study was conducted to assess the microbiological quality of wild harvested R. differens and evaluate the efficacy of conventional processing methods in reducing microbial load. Two districts (Bukoba rural and Muleba) within the Kagera region were purposively selected for the study. Sampling was done from the same batches along the R. differens food chain as follows: (a) at harvest points in the villages, (b) after transportation to the market and plucking of wings and legs, (c) after rinsing with potable tap water, and (d) after processing using conventional methods. Generally, high microbial counts, that is, total viable aerobic count (TVC), Enterobacteriaceae, lactic acid bacteria, bacterial endospores, and yeasts and molds were observed in raw R. differens samples. A significant increase in microbial counts after transportation and plucking was only observed for TVC, bacterial endospores, and yeasts and molds. A statistically significant reduction in all types of counts, with the exception of bacterial endospores, was observed after processing. All processed samples analyzed were devoid of salmonellae, Listeria monocytogenes, and Escherichia coli. PRACTICAL APPLICATIONS: Although commonly used processing methods of Ruspolia differens were effective in reducing microbial load, bacterial endospores were hardly eliminated and could pose a health hazard to consumers; thus, improved handling of R. differens along the food chain could reduce such risks. ispartof: Journal Of Food Safety vol:39 issue:1 status: published

The migratory locust, Locusta migratoria, is a serious agricultural pest and important insect model in the study of insect digestion and feeding behaviour. The gut is one of the primary interfaces between the insect and its environment. Nevertheless, knowledge on the gut transcriptome of L. migratoria is still very limited. Here, 48 802 expressed sequence tags were extracted from publicly available databases and their expression in larval gut and/or brain tissue was determined using microarray hybridization. Our data show 2765 transcripts predominantly or exclusively expressed in the gut. Many transcripts had putative functions closely related to the physiological functions of the gut as a muscular digestive organ and as the first barrier against microorganisms and a wide range of toxins. By means of a ranking procedure based on the relative signal intensity, we estimated 15% of the transcripts to show high expression levels, the highest belonging to diverse digestive enzymes and muscle-related proteins. We also found evidence for very high expression of an allergen protein, which could have important implications, as locusts form a traditional food source in various parts of the world, and were also recently added to the list of insects fit for human consumption in Europe. Interestingly, many highly expressed sequences have as yet unknown functions. Taken together, the present data provide significant insight into locust larval gut physiology, and will be valuable for future studies on the insect gut.

A dynamical model equation for interfacial gravity-capillary (GC) waves between two semi-infinite fluid layers, with a lighter fluid lying above a heavier one, is derived. The model proposed is based on the fourth-order truncation of the kinetic energy in the Hamiltonian of the full problem, and on weak transverse variations, in the spirit of the Kadomtsev-Petviashvilli equation. It is well known that for the interfacial GC waves in deep water, there is a critical density ratio where the associated cubic nonlinear Schrodinger equations changes type. Our numerical results reveal that, when the density ratio is below the critical value, the bifurcation diagram of plane solitary waves behaves in a way similar to that of the free-surface GC waves on deep water. However, the bifurcation mechanism in the vicinity of the minimum of the phase speed is essentially similar to that of free-surface gravity-flexural waves on deep water, when the density ratio is in the supercritical regime. Different types of lump solitary waves, which are fully localized in both transverse and longitudinal directions, are also computed using our model equation. Some dynamical experiments are carried out via a marching-in-time algorithm.

In closely related plant species that display strong similarities in phenology and pollinator communities, differences in breeding system and associated shifts in floral traits may have important effects on the magnitude and direction of heterospecific pollen flow and hybridization. Here, we quantified the strength of several pre- and postzygotic barriers acting between the facultatively outcrossing Centaurium erythraea and the predominantly selfing C. littorale via a suite of experiments, and estimated the frequency of hybridization in the field using molecular markers. The reproductive barriers primarily responsible for preventing hybridization were essentially prezygotic and these acted asymmetrically. Due to differences in floral display, pollen production, and pollen transfer rates, heterospecific pollen flow occurred predominantly from C. erythraea to C. littorale. In C. littorale, on the other hand, close anther-stigma positioning and resulting higher capacity for autonomous selfing functioned as an efficient barrier to counterbalance the higher risk for hybrid mating. In both species the action of all reproductive barriers resulted in a small opportunity for hybrid establishment, which was confirmed by the occurrence of only ∼1% putative hybrids in the field. Our findings confirm that differences in breeding system affect heterospecific pollen transfer patterns and that autonomous selfing may efficiently prevent hybridization.

The migratory locust, Locusta migratoria, is a serious agricultural pest and important insect model in the study of insect digestion and feeding behaviour. The gut is one of the primary interfaces between the insect and its environment. Nevertheless, knowledge on the gut transcriptome of L. migratoria is still very limited. Here, 48 802 expressed sequence tags were extracted from publicly available databases and their expression in larval gut and/or brain tissue was determined using microarray hybridization. Our data show 2765 transcripts predominantly or exclusively expressed in the gut. Many transcripts had putative functions closely related to the physiological functions of the gut as a muscular digestive organ and as the first barrier against microorganisms and a wide range of toxins. By means of a ranking procedure based on the relative signal intensity, we estimated 15% of the transcripts to show high expression levels, the highest belonging to diverse digestive enzymes and muscle-related proteins. We also found evidence for very high expression of an allergen protein, which could have important implications, as locusts form a traditional food source in various parts of the world, and were also recently added to the list of insects fit for human consumption in Europe. Interestingly, many highly expressed sequences have as yet unknown functions. Taken together, the present data provide significant insight into locust larval gut physiology, and will be valuable for future studies on the insect gut. ispartof: Insect Molecular Biology vol:25 issue:6 pages:745-756 ispartof: location:England status: published

In the last decade, genome sequence data and gene structure information on invertebrate receptors has been greatly expanded by large sequencing projects and cloning studies. This information is of great value for the identification of receptors; however, functional and pharmacological data are necessary for an accurate receptor classification and for practical applications. In insects, an important group of neurotransmitter and neurohormone receptors, for which ample sequence information is available but pharmacological information is missing, are the biogenic amine G protein-coupled receptors (GPCRs). In the present study, we investigated the sequence information, pharmacology and signalling properties of a 5-HT7 -type serotonin receptor from the red flour beetle, Tribolium castaneum (Trica5-HT7 ). The receptor encoding cDNA shows considerable sequence similarity with cognate 5-HT7 receptors and phylogenetic analysis also clusters the receptor within this 5-HT receptor group. Real-time reverse transcription PCR demonstrated high expression levels in the brain, indicating the possible importance of this receptor in neural processes. Trica5-HT7 was dose-dependently activated by 5-HT, which induced elevated intracellular cyclic AMP levels but had no effect on calcium signalling. The synthetic agonists, α-methyl 5-HT, 5-methoxytryptamine, 5-carboxamidotryptamine and 8-hydroxy-2-(dipropylamino)tetralin hydrobromide, showed a response, although with a much lower potency and efficacy than 5-HT. Ketanserin and methiothepin were the most potent antagonists. Both showed characteristics of competitive inhibition on Trica5-HT7 . The signalling pathway and pharmacological profile offer important information that will facilitate functional and comparative studies of 5-HT receptors in insects and other invertebrates. The pharmacology of invertebrate 5-HT receptors differs considerably from that of vertebrates. The present study may therefore contribute to establishing a more reliable classification of invertebrate 5-HT receptors.

The desert locust (Schistocerca gregaria) has been feared agricultural pest since early civilization, with plagues documented in ancient texts. Population genetic studies of the desert locust are needed to determine genetic variation and movement pattern for efficient control of the pest. In this study, we complemented the limited available microsatellite collection for the desert locust with 34 new polymorphic and multiplexed microsatellite loci. To this aim, we screened an expressed sequence tags library and constructed a partial genomic library enriched for dinucleotide repeats to develop high-throughput and high-quality genotyping assays. We then paid particular attention to quality control and carefully validated 26 of these novel microsatellites and six previously described loci for the absence of null alleles in Western African field populations. This large panel of high-quality microsatellite markers provides new opportunity to infer dispersal rates between populations of the desert locust and help prioritize early monitoring and control. Furthermore, high potential for cross-taxa utility of markers was observed within Schistocerca genus, which includes other locust pest species, with reliable amplification achieved for at least ten of loci per species. Microsatellite markers developed from transcriptome resources were largely devoid of null alleles and were conserved across species compared with those derived from traditional genomic libraries. Accordingly, the number of highly reliable microsatellite markers was greatly improved compared with that of previous studies on Orthopteran species, and this strategy might be broadly applied in other insect species prone to null alleles.

Drastic changes in the environment during a lifetime require developmental and physiological flexibility to ensure animal survival. Desert locusts, Schistocerca gregaria, live in an extremely changeable environment, which alternates between periods of rainfall and abundant food and periods of drought and starvation. In order to survive, locusts display an extreme form of phenotypic plasticity that allows them to rapidly cope with these changing conditions by converting from a cryptic solitarious phase to a swarming, voracious gregarious phase. To accomplish this, locusts possess different conserved mediators of phenotypic plasticity. Recently, attention has been drawn to the possible roles of protein kinases in this process. In addition to cyclic AMP-dependent protein kinase (PKA), also cyclic GMP-dependent protein kinase (PKG), which was shown to be involved in changes of food-related behavior in a variety of insects, has been associated with locust phenotypic plasticity. In this article, we study the transcript levels of the S. gregaria orthologue of the foraging gene that encodes a PKG in different food-related, developmental and crowding conditions. Transcript levels of the S. gregaria foraging orthologue are highest in different parts of the gut and differ between isolated and crowd-reared locusts. They change when the availability of food is altered, display a distinct pattern with higher levels after a moult and decrease with age during postembryonic development.

Adaptive genetic variation is a key factor in evolutionary biology, but the detection of signatures of natural selection remains challenging in nonmodel organisms. We used a genome scan approach to detect signals of natural selection in the Black alder (Alnus glutinosa), a widespread wind-pollinated tree. Gene flow through pollen dispersal is believed to be high in this species, and we therefore expected to find a clear response to natural selection. In combination with two different landscape genetic approaches, we determined which environmental variables were most associated with the inferred selection. This analysis was performed on a regional scale (northern Belgium) and on a continental scale (Europe). Because climate-related differences are much more pronounced at the continental scale, we expected to find more selection-sensitive genetic markers across Europe than across northern Belgium. At both spatial scales, a substantial number of genetic loci were considered outliers, with respect to neutral expectations, and were therefore identified as selective. Based on results from our combined approach, four putative selective loci (or 2.5%) were recovered with high statistical support. Although these loci seemed to be associated with different environmental variables, they were mainly temperature-related. Our study demonstrates that the use of complementary methods in landscape genetics allows the discovery of selective loci which otherwise might stay hidden. In combination with a genome scan, the selective loci can be verified and the nature of the selection pressure can be identified.

Novel endomorphin-2 (EM-2) analogs have been synthesized, incorporating unnatural amino acids with six-membered heterocyclic rings, such as piperidine-2-, 3- and 4-carboxylic acids (Pip, Nip and Inp, respectively) instead of Pro in position 2. [(R)-Nip(2)]EM-2 displayed an extremely high affinity for the mu-opioid receptor with IC(50) = 0.04 +/- 0.01 nM in comparison with IC(50) = 0.69 +/- 0.03 nM for EM-2. This analog was also very potent in the aequorin luminescence-based functional calcium assay and showed significantly enhanced stability in rat brain homogenate.

In locusts, little is known about the physiological and biochemical mechanisms regulating complex processes, such as reproduction and phase transition. The pacifastin family constitutes a family of peptidic inhibitors of serine proteases that are considered to be important regulators of several physiological processes in arthropods. We have performed a detailed transcript profiling analysis of two pacifastin-related peptide precursors, SGPP-2 and SGPP-4, during the reproductive cycle of adult desert locusts (Schistocerca gregaria). This quantitative real-time (RT)-PCR analysis revealed a temporal regulation of both transcripts, which is paralleled by several events that occur during the reproductive cycle of adult locusts. The observed temporal transcript profiles display a strong tissue-, gender- and phase-dependence. In addition, a partial regregarization experiment suggests that both transcript levels are regulated during phase transition and can be employed as molecular markers of the gregarization process.

Dynamin I (Dyn I) and Synaptotagmin I (Syt I) are essential for endocytosis-exocytosis processes, thus for neurotransmission. Despite their related function at presynaptic terminals, Dyn I and Syt I displayed opposite expression patterns during visual cortex maturation in the cat. Dyn I was more abundantly expressed in adults, while Syt I exhibited higher levels in kittens of postnatal day 30 (P30). In area 17 this developmental difference was most obvious in layers II/III. Layer VI displayed a strong hybridization signal for both molecules, independent of age. In addition, Syt I levels were higher in posterior compared to anterior area 17 in adult subjects. Moreover, in higher-order visual areas Syt I was unevenly distributed over the cortical layers, thereby setting clear areal boundaries in mature cortex. In contrast, Dyn I was rather homogeneously distributed over extrastriate areas at both ages. Both molecules thus demonstrated a widespread but different distribution and an opposite temporal expression pattern during visual system development. Notably, monocular deprivation during the critical period of ocular dominance plasticity significantly decreased Syt I expression levels in area 17 ipsilateral to the deprived eye, while no effect was observed on Dyn I expression. We therefore conclude that visual experience induces changes in Syt I expression that may reflect changes in constitutive exocytosis involved in postnatal structural refinements of the visual cortex. On the other hand, the spatial and temporal expression patterns of Dyn I correlate with the establishment and maintenance of the mature neuronal structure rather than neurite remodeling.

International audience; Bursicon is a neurohumoral agent responsible for tanning and hardening of the cuticle and expansion of the wings during the final phase of insect metamorphosis. Although the hormonal activity was described more than 40 years ago, the molecular nature of bursicon has remained elusive. We identify here Drosophila bioactive bursicon as a heterodimer made of two cystine knot polypeptides. This conclusion was reached in part from the unexpected observation that in the genome of the honey bee, the orthologs of the two Drosophila proteins are predicted to be fused in a single open reading frame. The heterodimeric Drosophila protein displays bursicon bioactivity in freshly eclosed neck-ligated flies and is the natural agonist of the orphan G protein-coupled receptor DLGR2.

Insects have a highly developed innate immune system, including humoral and cellular components. The cellular immune responses refer to hemocyte-mediated processes such as phagocytosis, nodulation, and encapsulation. Nodulation is considered the predominant defense reaction to infection in insects. Treating third instar larvae of the grey flesh fly, Neobellieria bullata, with laminarin (beta-1,3-glucan, a typical component of fungal cell walls) induced nodulation in a dose-dependent manner. This reaction was initiated very soon after injection and reached its maximal response level after 4 h. The nodules were not randomly distributed in the hemocoel, but were concentrated around the crop. The possible role of eicosanoids in this nodulation process was determined by treating larvae with the phospholipase A(2) inhibitor, dexamethasone, the cyclooxygenase inhibitor, naproxen, and the lipoxygenase inhibitor, esculetin. Both dexamethasone and naproxen significantly impaired the ability of N. bullata larvae to form nodules in response to laminarin. Supplying dexamethasone-treated larvae with the eicosanoid precursor, arachidonic acid, restored the full response. On the other hand, treating larvae with esculetin did not influence the formation of nodules in response to laminarin. This is the first study that demonstrates the occurrence of a laminarin-induced nodulation response in Diptera. Phospholipase A(2) and cyclooxygenase activities, both involved in prostaglandin biosynthesis, appear to play an important role in the regulation of this process.

This study describes the identification and distribution of two novel neuroparsin precursor transcripts ( ScgNPP3 / Scg-NPP4 ) in the desert locust, Schistocerca gregaria . Unlike Scg-NPP1 and Scg-NPP2 , both transcripts were not only detected in the brain, but also in various other tissues, such as fat body, ventral nerve cord, testis and male accessory glands. Northern analysis showed that the levels of these transcripts are regulated during larval development, as well as during moulting and reproductive cycles. A significant increase in both mRNAs was observed during the period that just precedes the initial sexual activity of adult females and males. In silico analysis of sequence databases revealed the existence of several other neuroparsin-like peptides in a variety of arthropod species, including crustaceans and chelicerates. Neuroparsins also display similarities with vertebrate IGFBP.

Recently, a novel serine protease-inhibiting peptide family, designated as the 'pacifastin family', has been described in locusts and crayfish. All members of this family possess a characteristic cysteine-rich domain. The present study describes the cDNA cloning, sequencing and transcript distribution of two novel pacifastin-related peptide precursors in the migratory locust, Locusta migratoria. Only one of the encoded peptides (HI) was identified previously, whereas six others represent new members of the pacifastin family. Northern blot analysis showed that both precursor transcripts are present in adult locust fat body. These could not be detected in the midgut. Interestingly, an in silico data mining approach of the expressed sequence tags (EST) database revealed the existence of Manduca sexta and Bombyx mori cDNAs that display pronounced sequence similarities with these locust pacifastin-related transcripts.

RNA interference (RNAi) has become a widely used loss-of-function tool in eukaryotes; however, the delivery of double-stranded (ds)RNA) to the target cells remains a major challenge when exploiting the RNAi-technology. In insects, the efficiency of RNAi is highly species-dependent. Yet, the mechanism of cell entry in insects has only been characterized in a cell line of the fruit fly, Drosophila melanogaster, a species that is well known to be poorly amenable to environmental RNAi. In the present paper, we demonstrate that silencing vacuolar H-ATPase 16 (vha16) and clathrin heavy chain (clath), two components of the Clathrin-dependent endocytosis pathway, together with pharmacological inhibition of scavenger receptors with polyinosine and dextran sulphate, can significantly attenuate the highly robust RNAi response in the desert locust, Schistocerca gregaria. ispartof: Insect Molecular Biology vol:23 issue:3 pages:320-329 ispartof: location:England status: published

RNA interference (RNAi) has become a widely used loss-of-function tool in eukaryotes; however, the delivery of double-stranded (ds)RNA) to the target cells remains a major challenge when exploiting the RNAi-technology. In insects, the efficiency of RNAi is highly species-dependent. Yet, the mechanism of cell entry in insects has only been characterized in a cell line of the fruit fly, Drosophila melanogaster, a species that is well known to be poorly amenable to environmental RNAi. In the present paper, we demonstrate that silencing vacuolar H-ATPase 16 (vha16) and clathrin heavy chain (clath), two components of the Clathrin-dependent endocytosis pathway, together with pharmacological inhibition of scavenger receptors with polyinosine and dextran sulphate, can significantly attenuate the highly robust RNAi response in the desert locust, Schistocerca gregaria.

The LCR/MEL system (Locus Control Region/Murine Erythroleukaemia cells) was employed to express and characterize the Locusta migratoria tyramine receptor (TyrLoc), an insect G protein-coupled receptor. Functional agonist-dependent responses were recorded in stable, tyramine receptor expressing cell clones (MEL-TyrLoc). Tyramine elicited a dose-dependent increase of cytosolic Ca2+-ions and an attenuation of forskolin-induced cyclic adenosine monophosphate (AMP) production. Octopamine was shown to be a weak agonist for both responses. In addition, yohimbine proved to be a potent tyramine receptor antagonist. This study reports the first application of the LCR/MEL expression system in functional assays for G protein-coupled receptors and therefore expands the capabilities of this system by exploiting the functionality of the signal transduction pathways.

Pharmacological characterization of STKR, an insect G protein-coupledreceptor for tachykinin-like peptides.

Neuroparsins were originally identified in locust corpus cardiacum extracts as folliculostatic or ‘antigonadotropic’ neuropeptides. This paper presents the cloning of two different neuroparsin precursor cDNAs from the brain of the desert locust, Schistocerca gregaria. The first transcript encodes the precursor (Scg-NPP1) of S. gregaria neuroparsin A and B, whereas the second codes for a novel neuroparsin-related peptide precursor (Scg-NPP2). Both precursors display significant sequence similarities with each other and with the Locusta migratoria neuroparsin (Lom-NPP) and Aedes aegypti ovary ecdysteroidogenic hormone (Aea-OEH1) precursors. Northern blot analysis revealed that these neuroparsin transcripts are present in larval and adult locust brains. Interestingly, the Scg-NPP2 mRNA content proved to be strongly regulated during the reproductive cycle in both adult males and females.

G protein-coupled receptors (GPCRs) are seven-transmembrane proteins (7-TM) that transduce extracellular signals into cellular physiological responses through the activation of heterotrimeric guanine nucleotide binding proteins (alpha beta gamma subunits). Their general properties are remarkably well conserved during evolution. Despite this general resemblance, a large variety of different signals are mediated via this category of receptors. Several GPCR-(sub)families have an ancient origin that is situated before the divergence of Protostomian and Deuterostomian animals. Nevertheless, an enormous diversification has occurred since then. The availability of novel sequence information is growing very rapidly as a result of molecular cloning experiments and of metazoan genome (Caenorhabditis elegans, Drosophila melanogaster, Homo sapiens) and EST (expressed sequence tags) sequencing projects. The Drosophila Genome Sequencing Project will certainly have an important impact on insect signal transduction and receptor research. In parallel, convenient expression systems and functional assay procedures will be needed to investigate insect receptor properties and to monitor the effects of natural and artificial ligands. The study of the evolutionary aspects of G protein-coupled receptors and of their signaling pathways will probably reveal insect-specific features. More insight into these features may result in novel methods and practical applications. Arch.

In the last decade, genome sequence data and gene structure information on invertebrate receptors has been greatly expanded by large sequencing projects and cloning studies. This information is of great value for the identification of receptors; however, functional and pharmacological data are necessary for an accurate receptor classification and for practical applications. In insects, an important group of neurotransmitter and neurohormone receptors, for which ample sequence information is available but pharmacological information is missing, are the biogenic amine G protein-coupled receptors (GPCRs). In the present study, we investigated the sequence information, pharmacology and signalling properties of a 5-HT7 -type serotonin receptor from the red flour beetle, Tribolium castaneum (Trica5-HT7 ). The receptor encoding cDNA shows considerable sequence similarity with cognate 5-HT7 receptors and phylogenetic analysis also clusters the receptor within this 5-HT receptor group. Real-time reverse transcription PCR demonstrated high expression levels in the brain, indicating the possible importance of this receptor in neural processes. Trica5-HT7 was dose-dependently activated by 5-HT, which induced elevated intracellular cyclic AMP levels but had no effect on calcium signalling. The synthetic agonists, α-methyl 5-HT, 5-methoxytryptamine, 5-carboxamidotryptamine and 8-hydroxy-2-(dipropylamino)tetralin hydrobromide, showed a response, although with a much lower potency and efficacy than 5-HT. Ketanserin and methiothepin were the most potent antagonists. Both showed characteristics of competitive inhibition on Trica5-HT7 . The signalling pathway and pharmacological profile offer important information that will facilitate functional and comparative studies of 5-HT receptors in insects and other invertebrates. The pharmacology of invertebrate 5-HT receptors differs considerably from that of vertebrates. The present study may therefore contribute to establishing a more reliable classification of invertebrate 5-HT receptors. ispartof: Insect Molecular Biology vol:23 issue:2 pages:230-243 ispartof: location:England status: published

A comparison of solution conformations of active, restricted-conformation analogues of two sequence-similar insect/vertebrate neuropeptide family pairs shed light on the potential existence of molecular evolutionary relationships. Analogues of the locustatachykinins and the mammalian tachykinin substance P, containing a sterically hindered Aib-NMePhe/Tyr residue block, share similar low-energy turn conformations incorporating a cis peptide bond. Conversely, restricted conformation analogues of the insect kinins and the mammalian opiate peptide Tyr-W-MIF-1, with near identical C-terminal tetrapeptide sequences, adopt different conformations. The insect kinins adopt a cisPro 1-4 beta-turn, in which the Phe1 is critical for bioactivity. Tyr-W-MIF-1 prefers a transPro 2-5 turn, and an additional N-terminal Phe severely inhibits mu-opiate receptor binding. Comparisons of the chemical/conformational requirements for receptor interaction are consistent with a distant evolutionary relationship between the insectatachykinins and tachykinins, but not between the insect kinins and Tyr-W-MIF-1. Therefore, analogues of the insect kinins with pest control potential can be readily designed to avoid mammalian interactions.

Antisera raised against two distinct peptide regions of the Drosophila neurokinin-like receptor NKD were used to immunolocalize tachykinin-receptor-like proteins in the central nervous system of two insect species: the African migratory locust, Locusta migratoria, and the gray fleshfly, Neobellieria bullata. The resulting immunopositive staining patterns were identical for both antisera. Moreover, a very similar distribution of the immunoreactive material was observed in fleshflies and locusts. Immunoreactivity was found in nerve terminals of the retrocerebral complex, suggesting a presynaptic localization of the receptor in this part of the brain. Cell bodies were stained in the subesophageal ganglion: an anterior group of four larger cells and a posterior group of about 20 cells. These cells have axons projecting into the contralateral nervus corporis allati (NCA) II, bypassing the corpus allatum and projecting through the NCA I into the storage part of the corpus cardiacum. In the glandular part of the corpus cardiacum, the glandular adipokinetic hormone-producing cells did not show any immunopositive staining. In the locust, additional immunopositive staining was observed in internolaterally located neurons of the tritocerebrum and in important integrative parts of the neuropil such as the central body and the mushroom bodies.