Effects of reflective groundcovers on ground beetles (Coleoptera: Carabidae) in red raspberry (Rubus idaeus) cropping systems

Reflective groundcovers are management tools used in temperate regions where light can be a limiting factor to crop productivity. Although their effects on crops have been extensively studied, little is known about their ecological impacts on ground‐dwelling organisms. Theoretically, reflective groundcovers add structural complexity to the system and thus have the potential to create refuges for ground‐dwelling invertebrates. At the same time, groundcovers can create abiotic conditions underneath them that could potentially cause declines in the abundance and richness of ground‐dwelling invertebrates. During the summers of 2006 and 2007, white, woven, reflective polymer groundcovers were placed in two red raspberry (Rubus idaeus L.) cropping systems (organic and conventional) in south‐eastern New Brunswick to assess their effects on ground beetle richness, activity density and overall assemblage structure. A total of 8723 ground beetles belonging to 23 species were collected using pitfall traps. In contrast with the combined effects of cropping systems and sampling years, the use of a groundcover accounted for a small proportion of the variance in trap catches and caused little change in ground beetle richness, activity density and overall assemblage structure. Based on these results, we suggest that reflective groundcovers constitute promising management tools to increase light environment quality in row crops without being detrimental to ground beetle species that may contribute to pest suppression.     

Spatial patterns of richness and abundance of benthic decapod crustaceans and fishes in the North-west Atlantic as measured by cobble-filled bio-collectors

Examination of spatial patterns of organisms in the rocky subtidal zone is logistically challenging, particularly over large geographic distances. In the present study, we describe patterns of richness and abundance of decapod crustaceans and small demersal fishes colonizing cobble-filled bio-collectors in 2008 and 2009 at nearshore sites across an important oceanographic and biogeographic gradient in the North-west Atlantic from Rhode Island, USA to Newfoundland, Canada. At least 17 decapod and 24 fish genera were caught, including cryptic fish taxa not readily sampled with other gear. Species richness and abundance of decapods and fishes in collectors at shallow sites (5–10 m) was similar among nearby sites and was greatest in the southernmost region, but did not follow a simple latitudinal cline. The lack of clear latitudinal patterns is likely to be a result of the complex geography of summer temperatures along this coast, with the lowest temperatures at the mouth of the Bay of Fundy, the centre of the study domain. In 2008, the abundance of crabs was positively related to temperature while that of shrimp was negatively related. There was also a significant interaction between depth and study area, with greater similarity among areas at greater depths (up to 76 m), and greater similarity among depths in areas with little temperature stratification. Our results indicate that bio-collectors are a powerful tool for sampling decapod crustaceans and small demersal fishes in nearshore rocky habitats. Given the anthropogenic impacts in coastal habitats, this information is likely to prove useful for detecting changes in rocky subtidal habitats.     

Sex attraction specificity in the Tortricidae

Sex attraction by pheromones seems general among the Tortricidae. Using virgin live females, female gland extracts or synthetic chemicals similar to known tortricid pheromones, it is shown that the species are attracted very specifically to their own pheromones. However, because of differences in seasonal cycles, circadian rhythms and secondary chemicals, many species may use the same primary attractant, without much interspecific attraction. There is some correlation between taxonomic groupings and pheromone structures.

---

Résumé L'attraction sexuelle par les phéromones semble être la règle chez les Tortricidae. L'attraction interspécifique a été étudiée dans la nature au moyen de femelles vierges vivantes, et de produits chimiques synthétiques semblables aux phéromones de Tortricidae dont la structure chimique a été élucidée. En général, les mâles d'une espèce donnée sont attirés très spécifiquement par un produit ou par un mélange qui, à leur égard, a valeur de phéromone.Cependant, le même produit attractif est souvent utilisé par plusieurs espèces. Il existe dans ce cas des différences de cycle saisonnier, de rythme circadien ou de produit chimique additionnel servant à l'attraction, de sorte que l'attraction interspécifique demeure un évènement rare. On observe une corrélation entre les groupements taxonomiques et la structure chimique des phéromones: dans la sous-famille des Olethreutinae, il y a surtout des alcools insaturés à 12 carbones et leurs acetates; dans la sous-famille des Tortricinae, surtout des alcools à `4 carbones et leurs acetates, généralement avec une double liaison en position 11.

     

Structural and functional evidence for the role of the TLR2 DD loop in TLR1/TLR2 heterodimerization and signaling

The Toll/Interleukin-1 receptor (TIR) domain of the Toll-like receptors (TLRs) plays an important role in innate host defense signaling. The TIR-TIR platform formed by the dimerization of two TLRs promotes homotypic protein-protein interactions with additional cytoplasmic adapter molecules to form an active signaling complex resulting in the expression of pro- and anti-inflammatory cytokine genes. To generate a better understanding of the functional domains of TLR2 we performed a random mutagenesis analysis of the human TLR2 TIR domain and screened for TLR2/1 signaling-deficient mutants. Based upon the random mutagenesis results, we performed an alanine scanning mutagenesis of the TLR2 DD loop and part of the alphaD region. This resulted in the identification of four residues crucial for TLR2/1 signaling: Arg-748, Phe-749, Leu-752, and Arg-753. Computer-assisted energy minimization and docking studies indicated three regions of interaction in the TLR2/1 TIR-docked heterodimer. In Region I, residues Arg-748 and Phe-749 in TLR2 DD loop were involved in close contacts with Gly-676 in the TLR1 BB loop. Because this model suggested that steric hindrance would significantly alter the binding interactions between DD loop of TLR2 and BB loop of TLR1, Gly-676 in TLR1 was rationally mutated to Ala and Leu. As expected, in vitro functional studies involving TLR1 G676A and TLR1 G676L resulted in reduced PAM(3)CSK(4) mediated NF-kappaB activation lending support to the computerized predictions. Additionally, mutation of an amino acid residue (TLR2 Asp-730) in Region II also resulted in decreased activity in agreement with our model, providing new insights into the structure-function relationship of TLR2/1 TIR domains.     

The capsid of the T4 phage superfamily: the evolution, diversity, and structure of some of the most prevalent proteins in the biosphere

The Escherichia coli bacteriophage T4 has served as a classic system in phage biology for more than 60 years. Only recently have phylogenetic analyses and genomic comparisons demonstrated the existence of a large, diverse, and widespread superfamily of T4-like phages in the environment. We report here on the T4-like major capsid protein (MCP) sequences that were obtained by targeted polymerase chain reaction (PCR) of marine environmental samples. This analysis was then expanded to include 1,000 s of new sequences of T4-like capsid genes from the metagenomic data obtained during the Sorcerer II Global Ocean Sampling (GOS) expedition. This data compilation reveals that the diversity of the major and minor capsid proteins from the GOS metagenome follows the same general patterns as the sequences from cultured phage genomes. Interestingly, the new MCP sequences obtained by PCR targeted to MCP sequences in environmental samples are more divergent (deeper branching) than the vast majority of the MCP sequences coming from the other sources. The marine T4-like phage population appears to be largely dominated by the T4-like cyanophages. Using approximately 1,400 T4-like MCP sequences from various sources, we mapped the degree of sequence conservation on a structural model of the T4-like MCP. The results indicate that within the T4 superfamily there are some clear phylogenetic groups with regard to the more conserved and more variable domains of the MCP. Such differences can be correlated with variations in capsid morphology, the arrangement of the MCP lattice, and the presence of different capsid accessory proteins between the subgroups of the T4 superfamily.     

Reversal of thymic stromal lymphopoietin-induced airway inflammation through inhibition of Th2 responses

Lung-specific thymic stromal lymphopoietin (TSLP) expression is sufficient for the development of an asthma-like chronic airway inflammatory disease. However, the nature of the downstream pathways that regulate disease development are not known. In this study, we used IL-4- and Stat6-deficient mice to establish the role of Th2-type responses downstream of TSLP. IL-4 deficiency greatly reduced, but did not eliminate, TSLP-induced airway hyperresponsiveness, airway inflammation, eosinophilia, and goblet cell metaplasia, while Stat6 deficiency eliminated these asthma-like symptoms. We further demonstrate, using the chronic model of TSLP-mediated airway inflammation, that blockade of both IL-4 and IL-13 responses, through administration of an anti-IL-4R alpha mAb, reversed asthma-like symptoms, when given to mice with established disease. Collectively these data provide insight into the pathways engaged in TSLP-driven airway inflammation and demonstrate that simultaneous blockade of IL-4 and IL-13 can reverse established airway disease, suggesting that this may be an effective approach for the therapy of Th2-mediated inflammatory respiratory disease.     

Susceptibility of quagga mussels (Dreissena rostriformis bugensis) to hot-water sprays as a means of watercraft decontamination

The recent spread of dreissenid mussels to various bodies of water in the western US has sparked interest by many state and federal agencies to develop protocols to stop further expansion. Quagga mussels (Dreissena rostriformis bugensis) are of particular importance as they are currently the most widespread dreissenid species in the region. This project examined the susceptibility of quagga mussels to hot-water sprays at different temperatures and durations of spray contact at Lake Mead (Nevada-Arizona, USA). Emersed adult quagga mussels were exposed to hot-water sprays at 20, 40, 50, 54, 60, 70, and 80°C for 1, 2, 5, 10, 20, 40, 80, and 160 s. Sprays at ≥60°C for 5 s were shown to be 100% lethal. Sprays of 54°C for 10 s, 50°C for 20 s, and 40°C for 40 s also resulted in 100% mortality. A spray temperature of 60°C for 5 s is recommended for mitigating fouling by quagga mussels.     

Byssus attachment strength of two mytilids in mono-specific and mixed-species mussel beds

The mussel Xenostrobus securis is endemic to the brackish waters of New Zealand and Australia, but has successfully invaded the inner Galician Rías of NW Spain, where it coexists with the indigenous mussel Mytilus galloprovincialis. In this laboratory study, the plasticity of the byssus attachment strength of two mytilids was compared by manipulating substratum, salinity, and bed assembly. M. galloprovincialis showed stronger byssus detachment strength than X. securis, despite lower byssus coverage. Both species responded similarly to the substratum, with substantially lower byssus strength on methacrylate, which offered the lowest surface free energy. Byssus detachment values for M. galloprovincialis were lower at lower salinity. In mixed beds, a number of mussels moved upwards, eventually colonising the upper layers of the assemblage. This behaviour increased byssus strength but only for X. securis. X. securis is adapted to a wide spectrum of abiotic conditions, a trait that may promote its dissemination within estuarine environments.