Seasonal variation in natural mortality factors of Tuta absoluta (Lepidoptera: Gelechiidae) in open‐field tomato cultivation

The seasonal variation in natural mortality of phytophagous insects is determined by the relative importance of biotic and abiotic factors in agroecosystems. Knowledge regarding these factors throughout the year represents a key concern for IPM programmes. Seasonal population fluctuations of tomato pinworm, Tuta absoluta, led to an investigation of its natural mortality factors during the rainy season when the population level is low and during the dry season when population peaks occur. The aim of this study was to verify the seasonal variation in T. absoluta mortality factors in tomato crops. Immature stages of T. absoluta were obtained from laboratory‐rearing in the laboratory. These were taken to the field and monitored over two years. The mortality causes for each stage of insect development from egg to adult were assessed daily. Multiple biotic and abiotic mortality factors affected the immature T. absoluta stages such as rainfall, physiological disturbances, diseases, parasitoids and predators. The key T. absoluta mortality factor during summer–spring was predation. In addition, larvae predation correlated positively with temperature, wind velocity, photoperiod and rainfall. Nevertheless, during winter–fall, the key mortality factor was parasitism. Therefore, the critical stage for mortality was 3rd‐ and 4th‐instar larvae, being more vulnerable to natural control factors. Finally, the results showed the importance of vertical and horizontal action on natural mortality factors.     

Tuberculosis Exacerbates HIV-1 Infection through IL-10/STAT3-Dependent Tunneling Nanotube Formation in Macrophages

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Synchrotron X-ray imaging via ultra-small-angle scattering: principles of quantitative analysis and application in studying bone integration to synthetic grafting materials

Optimized experimental conditions for extracting accurate information at subpixel length scales from analyzer-based X-ray imaging were obtained and applied to investigate bone regeneration by means of synthetic β-TCP grafting materials in a rat calvaria model. The results showed a 30% growth in the particulate size due to bone ongrowth/ingrowth within the critical size defect over a 1-month healing period.     

Invasive species and climate change: <Emphasis Type="Italic">Conyza canadensis</Emphasis> (L.) Cronquist as a tool for assessing the invasibility of natural plant communities along an aridity gradient

The predicted reduction in precipitation in the eastern Mediterranean due to climate change may expose the natural plant communities to invasive species. We assessed whether natural plant communities along an aridity gradient in Israel were resistant to invasion by considering differences in abiotic conditions and community characteristics in these regions. We considered Conyza canadensis as a model plant as it is a common invader in the region. We examined the mechanisms and functional traits of both the plant communities and C. canadensis that promote or discourage invasion. Study sites represented a rainfall gradient with four ecosystem types: mesic Mediterranean, Mediterranean, semiarid and arid. Our results showed that the mechanisms of community invasion resistance varied along the aridity gradient. At the arid and semiarid sites, water deficiency impaired the establishment of C. canadensis. At the mesic Mediterranean site, plant competition had a negative effect on C. canadensis performance, thus greatly reducing the likelihood of its establishment. We conclude that a decrease in regional precipitation due to climate change may not affect intrinsic resistance characteristics of natural plant communities to invasion in the area.     

Solution structure of the Tn3 resolvase-crossover site synaptic complex

Tn3 resolvase is a site-specific DNA recombinase, which catalyzes strand exchange in a synaptic complex containing twelve resolvase subunits and two res sites. Hyperactive mutants of resolvase can form a simpler complex (X synapse) containing a resolvase tetramer and two shorter DNA segments at which strand exchange takes place (site I). We have solved the low-resolution solution structure of the purified, catalytically competent X synapse from small-angle neutron and X-ray scattering data, using methods in which the data are fitted with models constructed by rigid body transformations of a published crystallographic structure of a resolvase dimer bound to site I. Our analysis reveals that the two site I fragments are on the outside of a resolvase tetramer core and provides some information on the quaternary structure of the tetramer. We discuss implications of our structure for the architecture of the natural synaptic complex and the mechanism of strand exchange.     

TLR4 recognizes Pseudallescheria boydii conidia and purified rhamnomannans

Pseudallescheria boydii (Scedosporium apiospermum) is a saprophytic fungus widespread in the environment, and has recently emerged as an agent of localized as well as disseminated infections, particularly mycetoma, in immunocompromised and immunocompetent hosts. We have previously shown that highly purified α-glucan from P. boydii activates macrophages through Toll-like receptor TLR2, however, the mechanism of P. boydii recognition by macrophage is largely unknown. In this work, we investigated the role of innate immune receptors in the recognition of P. boydii. Macrophages responded to P. boydii conidia and hyphae with secretion of proinflammatory cytokines. The activation of macrophages by P. boydii conidia required functional MyD88, TLR4, and CD14, whereas stimulation by hyphae was independent of TLR4 and TLR2 signaling. Removal of peptidorhamnomannans from P. boydii conidia abolished induction of cytokines by macrophages. A fraction highly enriched in rhamnomannans was obtained and characterized by NMR, high performance TLC, and GC-MS. Preparation of rhamnomannans derived from P. boydii triggered cytokine release by macrophages, as well as MAPKs phosphorylation and IκBα degradation. Cytokine release induced by P. boydii-derived rhamnomannans was dependent on TLR4 recognition and required the presence of non-reducing end units of rhamnose of the rhamnomannan, but not O-linked oligosaccharides from the peptidorhamnomannan. These results imply that TLR4 recognizes P. boydii conidia and this recognition is at least in part due to rhamnomannans expressed on the surface of P. boydii.