1,720,993 research outputs found
Wide-scale analysis of protein expression in head and thorax of Aedes albopictus females
No full textThe recently available genome of Aedes albopictus – the most worldwide-spread human arbovirus vector – has revealed a large genome repertory and a great plasticity which are believed to have contributed to the species
success as an invasive species and opened the way to genomic, transcriptomic and proteomic studies. We carried out the first wide-scale quantitative proteomic analysis of Ae. albopictus female head and thorax by means of a ‘shotgun’ approach based on nano liquid chromatography-high resolution mass spectrometry associated to protein Label Free Quantification (LFQ) which allows to assess differences in protein expression between tissues and different physiological stages. We identified 886 and 721 proteins in heads and thoraxes respectively, 5 of which were exclusively expressed in thoraxes and 170 in heads, consistently with the more complex head physiology. Head-protein expression was found to be highly divergent between virgin and mated females and limited before and after blood-feeding and oviposition. The large repertoire of proteins identified represents an instrumental source of data for genome annotation and gene-expression studies, and may contribute to studies aimed at investigating the molecular bases of physiological processes of this successful invasive species
Structure and biotechnological applications of odorant-binding proteins
No full textOdorant-binding proteins (OBPs) are small soluble polypeptides found in sensory organs of vertebrates and insects as well as in secretory glands and are dedicated to detection and release of chemical stimuli. OBPs of vertebrates belong to the family of lipocalin proteins, while those of insects are folded into α-helical domains. Both types of architectures are extremely stable to temperature, organic solvents and proteolytic digestion. These characteristics make OBPs suitable elements for fabricating biosensors to be used in the environment, as well as for other biotechnological applications. The affinity of OBPs for small volatile organic compounds is in the micromolar range, and they have broad specificity to a range of ligands. For biotechnological applications, OBPs can be expressed in bacterial systems at low cost and are easily purified. The large amount of information available on their structures and affinities to different molecules should allow the design of specific mutants with desired characteristics and represent a solid base for tailoring OBPs for different applications
Candidate biomarkers for mosquito age-grading identified by label-free quantitative analysis of protein expression in Aedes albopictus females
No full textWe applied a “shotgun” approach based on nanoliquid chromatography–high resolution mass spectrometry associated to label free quantification (LFQ) to identify proteins varying with age, independently from the physiological state, in Aedes albopictus, a mosquito species which in the last decades invaded temperate regions in North America and Europe, creating concerns for associated high nuisance and risk of arbovirus transmission. The combined “shotgun” and LFQ approach was shown to be highly suitable to simultaneously compare several biological samples, as needed in a study aimed to analyze different age-groups and physiological states of adult mosquito females. The results obtained represent the first wide-scale analysis of protein expression in Ae. albopictus females: N1000 and 665 proteins were identified from few micrograms of crude protein extracts of mosquito heads and thoraxes, respectively. Six of these proteins were shown to significantly vary from 2- to 16-day-old females, independently from their physiological state (i.e. virgin, mated, host-seeking, blood-fed, and gravid). Biological significance: Mosquito-borne diseases, such as malaria, dengue and other arboviroses, are a persistent cause of global mortality and morbidity, affecting hundreds of thousands of people. Billions of people living in tropical areas are at risk of being bitten every day by an infective mosquito female and the spread of tropical species such as Aedes albopictus to temperate areas is creating alarmin the northern hemisphere. Mosquito longevity is a critical factor affecting mosquito-borne pathogen transmission cycles and the mosquito capacity to transmit pathogens. However, large scale analyses of the age structure of mosquito field populations is hampered by the lack of optimal age-grading approaches. Our findings open new perspectives for the development of reliable, simple and cheap protein-based assays to age-grade Ae. albopictus females and, most likely, other mosquito species of higher medical relevance, such as the main dengue vector, Aedes aegypti, and the major Afrotropical malaria vectors. These assays would greatly contribute to epidemiological studies aimed at defining the actual vectorial capacity of a given mosquito species. Moreover, they would be very valuable in assessing the effectiveness of mosquito control interventions based on the relative ratio between young and old individuals before and after the intervention
Soluble proteins of chemical communication: an overview across arthropods
Full text linkDetection of chemical signals both in insects and in vertebrates is mediated by soluble proteins, highly concentrated in olfactory organs, which bind semiochemicals and activate, with still largely unknown mechanisms, specific chemoreceptors. The same proteins are often found in structures where pheromones are synthesised and released, where they likely perform a second role in solubilising and delivering chemical messengers in the environment.A single class of soluble polypeptides, called Odorant-Binding Proteins (OBPs) is known in vertebrates, while two have been identified in insects, OBPs and CSPs (Chemosensory Proteins). Despite their common name, OBPs of vertebrates bear no structural similarity with those of insects. We observed that in arthropods OBPs are strictly limited to insects, while a few members of the CSP family have been found in crustacean and other arthropods, where however, based on their very limited numbers, a function in chemical communication seems unlikely.The question we address in this review is whether another class of soluble proteins may have been adopted by other arthropods to perform the role of OBPs and CSPs in insects. We propose that lipid-transporter proteins of the Niemann-Pick type C2 family could represent likely candidates and report the results of an analysis of their sequences in representative species of different arthropods
Use of Heterorhabditis bacteriophora for the biological control of Popillia japonica larvae and evaluation of its impact on non-target soil biota
No full textPopillia japonica (Coleoptera: Scarabaeidae) is a scarab beetle native to Japan and accidentally introduced to Italy from North America in 2014. The high reproductive rate, the pathway of introduction, and the dispersal capability, as well as the polyphagous diet, led the EU to include this pest in the priority list. Popillia japonica spends most of its life cycle as a grub in the soil. At this stage, the grubs damage turf grasses, hay meadows, soccer pitches, and golf courses and are susceptible to biological control agents present in the soil, such as entomopathogenic nematodes (EPNs). As part of the Horizon 2020 Project ‘IPM-POPILLIA’, a large number of natural EPN strains have been collected from the soil in the outbreak area in Northern Italy along the Ticino River. The most virulent indigenous strain of Heterorhabditis bacteriophora (POP 16) was used in field trials to assess its effectiveness in containing the P. japonica larval population and its persistence in soil. Since September 2021, these trials have been carried out in the Piedmont region in three meadows with different irrigation management (non-irrigated, semi-irrigated, and irrigated fields). Two months after the treatments, a significant reduction of P. japonica larvae was observed in plots treated with EPNs (>90%) compared to untreated ones. Regarding persistence, H. bacteriophora was isolated again after the winter season and at lower concentrations one and two years after treatments, depending on irrigation management. Furthermore, in the irrigated meadow, the effects of EPNs on non-target soil biota were also evaluated, comparing soil arthropod assemblages with a Before-After Control-Impact experimental design. Compared to the control, no evident negative effect on non-target edaphic arthropods was disclosed on soil treated with EPNs. However, some taxa showed an increase in abundance, suggesting that some changes may occur in the long term. These results evidenced that the use of the selected EPN indigenous strain may be an excellent candidate for the integrated management of P. japonica, with no impact on non-target species, and at the same time highlighting the importance of evaluating the effects on soil biota to preserve the key- functioning of the ecosystem
Advances in mosquito repellents: effectiveness of citronellal derivatives in laboratory and field trials
Full text linkBACKGROUND
Several essential oils, including citronella (lemongrass, Cymbopogon sp., Poaceae), are well-known mosquito repellents. A drawback of such products is their limited protection time resulting from the high volatility of their active components. In particular, citronella oil protects for <2 h, although formulations with fixatives can increase this time.
RESULTS
We synthesized hydroxylated cyclic acetals of citronellal, the main component of citronella, to obtain derivatives with lower volatility and weaker odour. The crude mixture of isomers obtained in the reaction was tested under laboratory conditions for its repellency against two mosquito species, the major malaria vector Anopheles gambiae and the arbovirus vector Aedes albopictus, and found to be endowed with longer protection time with respect to DEET (N,N-diethyl-meta-toluamide) at the same concentration. Formulated products were tested in a latin square human field trial, in an area at a high density of A. albopictus for 8 h from the application. We found that the performance of the citronellal derivatives mixture is comparable (95% protection for ≤3.5 h) with those of the most widespread synthetic repellents DEET and Icaridin, tested at a four-fold higher doses.
CONCLUSIONS
Modifying the hydrophilicity and volatility of natural repellents is a valuable strategy to design insect repellents with a long-lasting effect. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry
Semiochemicals and olfactory protein in mosquito control
No full textThis thesis reports a biochemical study on the olfactory system in mosquitoes, which pose one of the major threats to human health, in order to devise strategies alternative to insecticides for population control. In particular, the final aim of the research work was the discovery of new mosquito repellents.
Our approach has been developed along two parallel lines:
a) a biochemical research on the proteins mediating odour perception in mosquitoes, in particular a functional study of Odorant-binding proteins (OBPs) and Chemosensory proteins (CSPs), two classes of polypeptides involved in the detection and recognition of olfactory stimuli in insects.
b) a structural comparison of the main components of essential oils behaviourally active on mosquitoes, in order to extract common feature that might provide guidelines for the design of better repellents;
The experimental work has been focused on the expression of OBPs and CSPs in mosquitoes. Using a proteomic approach, applied to antennae and pre-adult stages (in particular eggs, larvae and pupae) we have identified OBPs and CSPs that are more likely involved in odour recognition. These proteins were expressed in bacterial system and used in ligand-binding assays with compounds bioactive on mosquitoes.
During the last decade, we have witnessed an increasing number of publications dealing with mosquito repellents, most identified in plant essential oils. This large amount of research was stimulated by recent concerns on the safety of DEET, the commercial repellent. We have concluded that the best strategy for designing more efficient repellents is to aim at compounds with lower volatility, that provides a longer permanence on the skin as well as a reduced odour intensity. Based on this idea and taking the structures of some known repellents as templates, we have designed new molecules by introducing additional polar groups in the molecule and/or increasing their molecular weight. The new chemicals have been tested in “warm body” and “human-bait” experiments and several of them proved to be as good to repel mosquitoes as those currently used
Espressione e caratterizzazione delle CSP (Chemosensory Protein) nell'ape
No full textRIASSUNTO
Questo lavoro di tesi presenta una ricerca effettuata con tecniche di biochimica e di biologia molecolare su proteine solubili coinvolte nella chemiorecezione negli insetti, le Chemosensory protein (CSP). Queste sono proteine solubili di circa 100-120 amminoacidi, presenti nella linfa sensillare degli insetti, dove svolgono una funzione legante verso semiochimici. Alcune di esse sono state trovate anche in altre parti del corpo, come ghiandole produttrici di feromoni, svolgendo in questi casi ancora funzioni legate alla comunicazione chimica. E’ stata anche riportata la presenza di CSP in organi in fase di sviluppo, come nel caso della p10 della blatta, prodotta durante la rigenerazione degli arti, e della CSP5 dell’ape, presente solo nelle uova e negli ovari di regina.
In ogni caso, tali proteine costituiscono obiettivi interessanti nel controllo di popolazioni di insetti dannosi alle colture o nocivi per la salute umana, ma anche di insetti utili, come le api, che sono responsabili della impollinazione di molte piante. Una migliore conoscenza di queste proteine e di altre coinvolte nella comunicazione chimica puo’ suggerire azioni mirate per la conservazione di specie utili o la riduzione di quelle dannose.
Il lavoro sperimentale, riguarda lo studio delle 6 CSP presenti nel genoma di Apis mellifera. Quattro di queste sono state espresse in sistemi batterici, ottenendo ottime rese e proteine allo stato nativo. Tre di queste proteine, la CSP1, la CSP3 e la CSP4, sono state purificate mediante una serie di passaggi cromatografici su resine a scambio anionico e gel-filtrazione ed utilizzate in saggi di binding con molecole leganti diverse. La CSP1 lega in maniera forte e specifica composti a catena lineare come alcooli ed esteri a 13-14 atomi di carbonio. La CSP3 ha mostrato una selettivita’ simile, legando con alta affinita’ l’1-tridecanolo, accanto ad altri composti, quali benzoati alchilici. E’ noto che alcuni esteri a catena medio-lunga sono stati identificati come componenti di miscele feromonali utilizzate dalle api nei loro rapporti sociali. Non e’ escluso, quindi che sia la CSP1 che la CSP3 siano coinvolte nella percezione di tali messaggi chimici. La CSP4, invece, ha mostrato un comportamento molto diverso, legando composti terpenici di dimensioni realtivamente grandi, quali il retinolo ed il beta-ionone.
Utilizzando la spettrometria di massa MALDI alcune CSP sono state identificate nelle antenne di api appartenenti alle diverse caste ed in altri tessuti. Questa rappresenta la prima indagine sulla presenza di proteine olfattive negli insetti effettuata per spettrometria di massa direttamente su tessuti biologici
Profiles of soluble proteins in chemosensory organs of three members of the afro-tropical Anopheles gambiae complex
No full textIn female mosquitoes, host-seeking and preference as well as several other important behaviors are largely driven by olfaction. Species of the Afrotropical Anopheles gambiae complex display divergent host-preference that
are associated with significant differences in their vectorial capacity for human malaria. Olfactory sensitivity begins with signal transduction and activation of peripheral sensory neurons that populate the antennae,
maxillary palps and other appendages. We have used shotgun proteomics to characterize the profile of soluble proteins of antennae and maxillary palps of three different species: An. coluzzii, An. arabiensis and An. quadriannulatus that display remarkable differences in anthropophilic behavior. This analysis revealed interspecific differences in the abundance of several proteins that comprise cuticular components, glutathione S-transferase and odorant binding proteins, the latter of which known to be directly involved in odor recognition
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