Odorant binding proteins : a biotechnological tool for odour control

The application of an odorant binding protein for odour control and fragrance delayed release from a textile surface was first explored in this work. Pig OBP-1 gene was cloned and expressed in Escherichia coli , and the purified protein was biochemically characterized. The IC50 values(concentrations of competitor that caused a decay of fluorescence to half-maximal intensity) were determined for four distinct fragrances, namely, citronellol, benzyl benzoate,citronellyl valerate and ethyl valerate. The results showed a strong binding of citronellyl valerate,citronellol and benzyl benzoate to the recombinant protein, while ethyl valerate displayed weaker binding. Cationized cotton substrates were coated with porcine odorant binding protein and tested for their capacity to retain citronellol and to mask the smell of cigarette smoke. The immobilized protein delayed the release of citronellol when compared to the untreated cotton. According to a blind evaluation of 30 assessors, the smell of cigarette smoke, trapped onto the fabrics’ surface, was successfully attenuated by porcine odorant binding protein (more than 60 % identified the weakest smell intensity after protein exposure compared to β-cyclodextrin-treated and untreated cotton fabrics). This work demonstrated that porcine odorant binding protein can be an efficient solution to prevent and/orremove unpleasant odours trapped on the large surface of textiles. Its intrinsic properties make odorant binding proteins excellent candidates for controlled release systems which constitute a new application for this class of proteins.This work was co-funded by the European Social Fund through the management authority POPH and FCT. The authors Carla Silva and Teresa Matama would like to acknowledge their post-doctoral fellowships: SFRH/BPD/46515/2008 and SFRH/BPD/47555/2008, respectively

Current Status of a Model System: The Gene Gp-9 and Its Association with Social Organization in Fire Ants

The Gp-9 gene in fire ants represents an important model system for studying the evolution of social organization in insects as well as a rich source of information relevant to other major evolutionary topics. An important feature of this system is that polymorphism in social organization is completely associated with allelic variation at Gp-9, such that single-queen colonies (monogyne form) include only inhabitants bearing B-like alleles while multiple-queen colonies (polygyne form) additionally include inhabitants bearing b-like alleles. A recent study of this system by Leal and Ishida (2008) made two major claims, the validity and significance of which we examine here. After reviewing existing literature, analyzing the methods and results of Leal and Ishida (2008), and generating new data from one of their study sites, we conclude that their claim that polygyny can occur in Solenopsis invicta in the U.S.A. in the absence of expression of the b-like allele Gp-9b is unfounded. Moreover, we argue that available information on insect OBPs (the family of proteins to which GP-9 belongs), on the evolutionary/population genetics of Gp-9, and on pheromonal/behavioral control of fire ant colony queen number fails to support their view that GP-9 plays no role in the chemosensory-mediated communication that underpins regulation of social organization. Our analyses lead us to conclude that there are no new reasons to question the existing consensus view of the Gp-9 system outlined in Gotzek and Ross (2007)

A Functional Genomics Approach Identifies Candidate Effectors from the Aphid Species Myzus persicae (Green Peach Aphid)

Aphids are amongst the most devastating sap-feeding insects of plants. Like most plant parasites, aphids require intimate associations with their host plants to gain access to nutrients. Aphid feeding induces responses such as clogging of phloem sieve elements and callose formation, which are suppressed by unknown molecules, probably proteins, in aphid saliva. Therefore, it is likely that aphids, like plant pathogens, deliver proteins (effectors) inside their hosts to modulate host cell processes, suppress plant defenses, and promote infestation. We exploited publicly available aphid salivary gland expressed sequence tags (ESTs) to apply a functional genomics approach for identification of candidate effectors from Myzus persicae (green peach aphid), based on common features of plant pathogen effectors. A total of 48 effector candidates were identified, cloned, and subjected to transient overexpression in Nicotiana benthamiana to assay for elicitation of a phenotype, suppression of the Pathogen-Associated Molecular Pattern (PAMP)–mediated oxidative burst, and effects on aphid reproductive performance. We identified one candidate effector, Mp10, which specifically induced chlorosis and local cell death in N. benthamiana and conferred avirulence to recombinant Potato virus X (PVX) expressing Mp10, PVX-Mp10, in N. tabacum, indicating that this protein may trigger plant defenses. The ubiquitin-ligase associated protein SGT1 was required for the Mp10-mediated chlorosis response in N. benthamiana. Mp10 also suppressed the oxidative burst induced by flg22, but not by chitin. Aphid fecundity assays revealed that in planta overexpression of Mp10 and Mp42 reduced aphid fecundity, whereas another effector candidate, MpC002, enhanced aphid fecundity. Thus, these results suggest that, although Mp10 suppresses flg22-triggered immunity, it triggers a defense response, resulting in an overall decrease in aphid performance in the fecundity assays. Overall, we identified aphid salivary proteins that share features with plant pathogen effectors and therefore may function as aphid effectors by perturbing host cellular processes

Molecular Variation at a Candidate Gene Implicated in the Regulation of Fire Ant Social Behavior

The fire ant Solenopsis invicta and its close relatives display an important social polymorphism involving differences in colony queen number. Colonies are headed by either a single reproductive queen (monogyne form) or multiple queens (polygyne form). This variation in social organization is associated with variation at the gene Gp-9, with monogyne colonies harboring only B-like allelic variants and polygyne colonies always containing b-like variants as well. We describe naturally occurring variation at Gp-9 in fire ants based on 185 full-length sequences, 136 of which were obtained from S. invicta collected over much of its native range. While there is little overall differentiation between most of the numerous alleles observed, a surprising amount is found in the coding regions of the gene, with such substitutions usually causing amino acid replacements. This elevated coding-region variation may result from a lack of negative selection acting to constrain amino acid replacements over much of the protein, different mutation rates or biases in coding and non-coding sequences, negative selection acting with greater strength on non-coding than coding regions, and/or positive selection acting on the protein. Formal selection analyses provide evidence that the latter force played an important role in the basal b-like lineages coincident with the emergence of polygyny. While our data set reveals considerable paraphyly and polyphyly of S. invicta sequences with respect to those of other fire ant species, the b-like alleles of the socially polymorphic species are monophyletic. An expanded analysis of colonies containing alleles of this clade confirmed the invariant link between their presence and expression of polygyny. Finally, our discovery of several unique alleles bearing various combinations of b-like and B-like codons allows us to conclude that no single b-like residue is completely predictive of polygyne behavior and, thus, potentially causally involved in its expression. Rather, all three typical b-like residues appear to be necessary

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Not AvailablePheromones are defined as chemical signals that are released from one individual and induce specific endocrine or behavioural reactions in another individual of the same species. Odours play a significant role in signalling the stage of reproduction of the cow, and the bull can use a combination of factors displayed by the female to determine its receptivity. During oestrus, females release olfactory molecules, thus signalling the stage of their cycle and stimulating sexual behaviour and functions of males. Attempts were made to review the chemical nature of olfactory signals of oestrus in milk, urine, blood, saliva, skin gland secretion during the proestrous and oestrous cycle. Several behavioural studies indicated that bovine milk from different stages of the oestrous cycle had different odours. Bulls have also been· found to detect pheromone odours and difkrentiate between oestrus and non-oestrus urine. Bioassay involving rats revealed the presence of maximal pheromone activity during proestrus. Vaginal fluid is also reported to act as a chemical signal. Saliva, serum, skin gland secretions and faeces have also been studied for their pheromonal properties. ·Systemic evaluation of either urine or vaginal secretions over the whole cycle has yet to be investigated. The use of artificial olfaction could enable more accurate detection of oestrus and potentially increase fertility in cows. The current status of chemical signals (pheromones) of oestrus and their identification in farm animals is reviewed in this article with emphasis on cows.Not Availabl

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It is review article.Pheromones are defined as chemical signals that are released from one individual and induce specific endocrine or behavioural reactions in another individual of the same species. Odours play a significant role in signalling the stage of reproduction of the cow, and the bull can use a combination of factors displayed by the female to determine its receptivity. During oestrus, females release olfactory molecules, thus signalling the stage of their cycle and stimulating sexual behaviour and functions of males. Attempts were made to review the chemical nature of olfactory signals of oestrus in milk, urine, blood, saliva, skin gland secretion during the proestrous and oestrous cycle. Several behavioural studies indicated that bovine milk from different stages of the oestrous cycle had different odours. Bulls have also been found to detect pheromone odours and differentiate between oestrus and non-oestrus urine. Bioassay involving rats revealed the presence of maximal pheromone activity during proestrus. Vaginal fluid is also reported to act as a chemical signal. Saliva, serum, skin gland secretions and faeces have also been studied for their pheromonal properties. Systemic evaluation of either urine or vaginal secretions over the whole cycle has yet to be investigated. The use of artificial olfaction could enable more accurate detection of oestrus and potentially increase fertility in cows. The current status of chemical signals (pheromones) of oestrus and their identification in farm animals is reviewed in this article with emphasis on cows.Not Availabl

Fine structure and physicochemical analysis of the nymphal and imaginal scent gland systems of Lincus spurcus (Rolston) (Heteroptera : Pentatomidae)

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Phéromones de l’oestrus et potentialisation de la libido chez le taureau

National audienceLa communication chimique joue un rôle essentiel dans la mise en place de nombreux comportements chez les mammifères et en particulier du comportement sexuel. Ainsi, la femelle en oestrus attire le male via l’émission de phéromones dans ses urines. Afin d’identifier, les phéromones impliquées dans ce processus, plusieurs séries de collectes d’urine ont été réalisées à différents stades d’un cycle oestral sur des vaches synchronisées (N=30). La comparaison de leur composition chimique (déterminée par GC/MS) a permis de caractériser six molécules produites spécifiquement aux stades pré-oestrus et/ou oestrus. Cinq de ces molécules (le coumarin, le squalène, l’acide oléique, la 2-butanone, le 1,2-dichloro-éthylène), disponibles commercialement, ont été testées, seules ou en mélange, pour leur activité biologique sur les taureaux. Solubilisées à concentration physiologique (25 pg/ml) dans une solution de glycérol/eau (50/50), les différentes combinaisons ont été pulvérisées dans les cavités nasales des taureaux

Biochemical and chemical supports for a transnatal olfactory continuity through sow maternal fluids

International audienceRecognition of the mother is of major importance for the survival of mammalian neonates. This recognition is based, immediately after birth, on the detection of odours that have been learned by the fetus in utero. If the ethological basis of a transnatal olfactory continuity is well established, little is known on the nature of its olfactory cues, and nothing about the presence of potential carrier proteins in the maternal fluids such as amniotic fluid, colostrum and milk. We have identified the components of the pig putative maternal pheromone in these fluids of the sow. We also used a ligand-oriented approach to functionally characterize carrier proteins for these compounds in the maternal fluids. Six proteins were identified, using binding assay, immunodetection and peptide mapping by mass spectrometry. These proteins are known to transport hydrophobic ligands in biological fluids. Among them, alpha-1 acid glycoprotein (AGP) and odorant-binding protein (OBP) have been described in the oral sphere of piglets as being involved in the detection of pig putative maternal pheromone components. These are the first chemical and biochemical data supporting a transnatal olfactory continuity between the fetal and the postnatal environments

Heterologous expression of piglet odorant-binding protein in Pichia pastoris: a comparative structural and functional characterization with native forms

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