Identification and analysis of serpin-family genes by homology and synteny across the 12 sequenced Drosophilid genomes.

BACKGROUND: The Drosophila melanogaster genome contains 29 serpin genes, 12 as single transcripts and 17 within 6 gene clusters. Many of these serpins have a conserved "hinge" motif characteristic of active proteinase inhibitors. However, a substantial proportion (42%) lacks this motif and represents non-inhibitory serpin-fold proteins of unknown function. Currently, it is not known whether orthologous, inhibitory serpin genes retain the same target proteinase specificity within the Drosophilid lineage, nor whether they give rise to non-inhibitory serpin-fold proteins or other, more diverged, proteins. RESULTS: We collated 188 orthologues to the D. melanogaster serpins from the other 11 Drosophilid genomes and used synteny to find further family members, raising the total to 226, or 71% of the number of orthologues expected assuming complete conservation across all 12 Drosophilid species. In general the sequence constraints on the serpin-fold itself are loose. The critical Reactive Centre Loop (RCL) sequence, including the target proteinase cleavage site, is strongly conserved in inhibitory serpins, although there are 3 exceptional sets of orthologues in which the evolutionary constraints are looser. Conversely, the RCL of non-inhibitory serpin orthologues is less conserved, with 3 exceptions that presumably bind to conserved partner molecules. We derive a consensus hinge motif, for Drosophilid inhibitory serpins, which differs somewhat from that of the vertebrate consensus. Three gene clusters appear to have originated in the melanogaster subgroup, Spn28D, Spn77B and Spn88E, each containing one inhibitory serpin orthologue that is present in all Drosophilids. In addition, the Spn100A transcript appears to represent a novel serpin-derived fold. CONCLUSION: In general, inhibitory serpins rarely change their range of proteinase targets, except by a duplication/divergence mechanism. Non-inhibitory serpins appear to derive from inhibitory serpins, but not the reverse. The conservation of different family members varied widely across the 12 sequenced Drosophilid genomes. An approach considering synteny as well as homology was important to find the largest set of orthologues.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Neonicotinoid insecticides severely affect honey bee queens

Queen health is crucial to colony survival of social bees. Recently, queen failure has been proposed to be a major driver of managed honey bee colony losses, yet few data exist concerning effects of environmental stressors on queens. Here we demonstrate for the first time that exposure to field realistic concentrations of neonicotinoid pesticides during development can severely affect queens of western honey bees (Apis mellifera). In pesticide-exposed queens, reproductive anatomy (ovaries) and physiology (spermathecal-stored sperm quality and quantity), rather than flight behaviour, were compromised and likely corresponded to reduced queen success (alive and producing worker offspring). This study highlights the detriments of neonicotinoids to queens of environmentally and economically important social bees, and further strengthens the need for stringent risk assessments to safeguard biodiversity and ecosystem services that are vulnerable to these substances

Identification and analysis of serpin-family genes by homology and synteny across the 12 sequenced Drosophilid genomes.

BACKGROUND: The Drosophila melanogaster genome contains 29 serpin genes, 12 as single transcripts and 17 within 6 gene clusters. Many of these serpins have a conserved "hinge" motif characteristic of active proteinase inhibitors. However, a substantial proportion (42%) lacks this motif and represents non-inhibitory serpin-fold proteins of unknown function. Currently, it is not known whether orthologous, inhibitory serpin genes retain the same target proteinase specificity within the Drosophilid lineage, nor whether they give rise to non-inhibitory serpin-fold proteins or other, more diverged, proteins. RESULTS: We collated 188 orthologues to the D. melanogaster serpins from the other 11 Drosophilid genomes and used synteny to find further family members, raising the total to 226, or 71% of the number of orthologues expected assuming complete conservation across all 12 Drosophilid species. In general the sequence constraints on the serpin-fold itself are loose. The critical Reactive Centre Loop (RCL) sequence, including the target proteinase cleavage site, is strongly conserved in inhibitory serpins, although there are 3 exceptional sets of orthologues in which the evolutionary constraints are looser. Conversely, the RCL of non-inhibitory serpin orthologues is less conserved, with 3 exceptions that presumably bind to conserved partner molecules. We derive a consensus hinge motif, for Drosophilid inhibitory serpins, which differs somewhat from that of the vertebrate consensus. Three gene clusters appear to have originated in the melanogaster subgroup, Spn28D, Spn77B and Spn88E, each containing one inhibitory serpin orthologue that is present in all Drosophilids. In addition, the Spn100A transcript appears to represent a novel serpin-derived fold. CONCLUSION: In general, inhibitory serpins rarely change their range of proteinase targets, except by a duplication/divergence mechanism. Non-inhibitory serpins appear to derive from inhibitory serpins, but not the reverse. The conservation of different family members varied widely across the 12 sequenced Drosophilid genomes. An approach considering synteny as well as homology was important to find the largest set of orthologues.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

MD simulations on ionophores at a water-chloroform interface .1. Calix[4]arenes uncomplexed and the 222 cryptand

International audienceComputer experiments are reported on calixarene ionophores at the water-chloroform interface, using an explicit representation of the solvents. The time evolution of the free carriers is simulated by molecular dynamics for timescales ranging from 250 to 600 ps, As ionophores, we consider the t-butylcalix[4]arene-tetra(diethyl)amide the t-butylcalix[4]arene-anion, the 1,3-alternate 1,3-dimethoxy-t-butylcalix[4]arene-crown and calix[4]arene-bis-crown-6. For comparison, the 222 cryptand is also considered. We find that they all behave like surfactants, i.e., are adsorbed at the interface and sit almost entirely in chloroform, without migrating further to the organic phase. This contrasts with n-butane and Cl-, which migrate from the interface to the bulk organic phase and the aqueous phase, respectively. lonophores at the interface are partially hydrated, involving ''water fingers'' in some cases. The interface is found to be very sharp. On the basis of an energy component analysis, we suggest that the ''stationary states'' of ionophores at the interface result from solvent cohesive forces rather than solute-solvent interactions

Drosophila C virus systemic infection leads to intestinal obstruction

Drosophila C virus (DCV) is a positive-sense RNA virus belonging to the Dicistroviridae family. This natural pathogen of the model organism Drosophila melanogaster is commonly used to investigate antiviral host defense in flies, which involves both RNA interference and inducible responses. Although lethality is used routinely as a readout for the efficiency of the antiviral immune response in these studies, virus-induced pathologies in flies still are poorly understood. Here, we characterize the pathogenesis associated with systemic DCV infection. Comparison of the transcriptome of flies infected with DCV or two other positive-sense RNA viruses, Flock House virus and Sindbis virus, reveals that DCV infection, unlike those of the other two viruses, represses the expression of a large number of genes. Several of these genes are expressed specifically in the midgut and also are repressed by starvation. We show that systemic DCV infection triggers a nutritional stress in Drosophila which results from intestinal obstruction with the accumulation of peritrophic matrix at the entry of the midgut and the accumulation of the food ingested in the crop, a blind muscular food storage organ. The related virus cricket paralysis virus (CrPV), which efficiently grows in Drosophila, does not trigger this pathology. We show that DCV, but not CrPV, infects the smooth muscles surrounding the crop, causing extensive cytopathology and strongly reducing the rate of contractions. We conclude that the pathogenesis associated with systemic DCV infection results from the tropism of the virus for an important organ within the foregut of dipteran insects, the crop. IMPORTANCE: DCV is one of the few identified natural viral pathogens affecting the model organism Drosophila melanogaster. As such, it is an important virus for the deciphering of host-virus interactions in insects. We characterize here the pathogenesis associated with DCV infection in flies and show that it results from the tropism of the virus for an essential but poorly characterized organ in the digestive tract, the crop. Our results may have relevance for other members of the Dicistroviridae, some of which are pathogenic to beneficial or pest insect species

Cytokine Diedel and a viral homologue suppress the IMD pathway in Drosophila

International audienceno abstrac

Neonicotinoid pesticides can reduce honeybee colony genetic diversity

Neonicotinoid insecticides can cause a variety of adverse sub-lethal effects in bees. In social species such as the honeybee, Apis mellifera, queens are essential for reproduction and colony functioning. Therefore, any negative effect of these agricultural chemicals on the mating success of queens may have serious consequences for the fitness of the entire colony. Queens were exposed to the common neonicotinoid pesticides thiamethoxam and clothianidin during their developmental stage. After mating, their spermathecae were dissected to count the number of stored spermatozoa. Furthermore, their worker offspring were genotyped with DNA microsatellites to determine the number of matings and the genotypic composition of the colony. Colonies providing the male mating partners were also inferred. Both neonicotinoid and control queens mated with drones originating from the same drone source colonies, and stored similar number of spermatozoa. However, queens reared in colonies exposed to both neonicotinoids experienced fewer matings. This resulted in a reduction of the genetic diversity in their colonies (i.e. higher intracolonial relatedness). As decreased genetic diversity among worker bees is known to negatively affect colony vitality, neonicotinoids may have a cryptic effect on colony health by reducing the mating frequency of queens