Spider venoms are an incredibly rich source of disulfide-rich insecticidal peptides that have been tuned over millions of years to target a wide range of receptors and ion channels in the insect ...nervous system. These peptides can act individually, or as part of larger toxin cabals, to rapidly immobilize envenomated prey owing to their debilitating effects on nervous system function. Most of these peptides contain a unique arrangement of disulfide bonds that provides them with extreme resistance to proteases. As a result, these peptides are highly stable in the insect gut and hemolymph and many of them are orally active. Thus, spider-venom peptides can be used as stand-alone bioinsecticides, or transgenes encoding these peptides can be used to engineer insect-resistant crops or enhanced entomopathogens. We critically review the potential of spider-venom peptides to control insect pests and highlight their advantages and disadvantages compared with conventional chemical insecticides.
•Oxidation tests in air on RR1000 at 600–900°C for times to 5000h.•Parabolic weight gain kinetics but Cr, Ti and Al all oxidise.•Protective chromia layer thickens with sub-parabolic kinetics.•Chromia ...thickening rates are initially much higher than expected due to Ti doping.•Ti depletion in the alloy results in the sub-parabolic chromia growth kinetics.
Oxidation of the Ni-based superalloy RR1000 has been undertaken in air over the temperature range 600–900°C for times up to 5000h. The surface oxide consisted of a protective Ti-doped chromia layer but with rutile forming on its outer surface. Sub-surface oxidation of Al and Ti also occurred. The thickening kinetics of the chromia layer were sub-parabolic with initial rates around two orders of magnitude higher than expected for Ti-free chromia. This enhancement and the sub-parabolic kinetics are accounted for by Ti-doping of the chromia layer. Over time the enhancement reduced because of Ti-depletion in the alloy.
The risks, hazards, and relative severity of wildland fires are presented here within the ecological context of historical natural fire regimes, time, space, and process. As the public dialogue on ...the role and impacts of wildland fire increases, it is imperative for all partners to converge on clear and concise terminology that defines risk, hazard, and the characteristic (or uncharacteristic) nature of wildland fire. These terms must be defined in the context of scale—both spatial and temporal. The concept of historical natural fire regimes involves a classification of the characteristic, or “natural” processes and effects associated with wildland fire occurring in sustainable ecosystems. When a wildland fire occurs within the time, space, and severity parameters of the historical natural fire regime, the fire can be called natural, or “characteristic”. The milieu of disturbance effects we call catastrophic, such as economic losses, damages to communities and structures, or impacts on short-term aesthetic values involve social, cultural, and economic values and risks—none is directly associated with ecological values, damages, or risks. In the context of technical risk assessments, the term “risk” considers not only the probability of an event, but also includes values and expected losses. However, within the fire community it refers only to the probability of ignition (both man- and lightning-caused). ‘Hazard’ refers to the state of the fuel, exclusive of weather or the environs in which the fuel is found. Unlike many common uses of the term ‘severity’, fire severity refers specifically to the effect a fire has on wildland systems. It is inappropriate to use the term severity to describe the behavior of the fire phenomenon itself. Instead, we should confine its use to that relating only to a fire's effect. Finally, I discuss the limitations and conflicts to integrating all social, cultural, economic, health, and safety values in our public and policy-forming dialogue relating to fire risk, hazard, and severity. Typical risk assessments consider all relevant endpoints, including socio-economic, management, as well as ecological elements. Herein, I use the Black Mountain 2 Fire from August 2003 in the northern Rockies to illustrate the spatiotemporal extent of fire's impacts on the endpoints. When expressed over all affected spatiotemporal scales, the overlay of all endpoints from this synthetic scenario results in a “decision space” ranging in time from an hour to a century, and in space ranging from a few square meters to the continent.
Hamilton's theory of local mate competition (LMC) describes how competition between male relatives for mating opportunities favours a female‐biased parental investment. LMC theory has been extended ...in many ways to explore a range of genetic and life‐history influences on sex allocation strategies, including showing that increasing genetic homogeneity within mating groups should favour greater female bias. However, there has been no quantitative theoretical prediction as to how females should facultatively adjust their sex allocation in response to co‐foundress number and kinship. This shortfall has been highlighted recently by the finding that sex ratios produced by sub‐social parasitoid wasps in the family Bethylidae are affected by the number of co‐foundresses and by whether these are sisters or unrelated females. Here we close this gap in LMC theory by taking an inclusive‐fitness approach to derive explicit theoretical predictions for this scenario. We find that, in line with the recent empirical results, females should adopt a more female‐biased sex allocation when their co‐foundresses are less numerous and are their sisters. Our model appears to predict somewhat more female bias than is observed empirically; we discuss a number of possible model extensions that would improve realism and that would be expected to result in a closer quantitative fit with experimental data.
Sub‐social parasitoids are predicted to adjust their sex allocation behaviour when co‐foundresses are sisters.
Deposition of lignified secondary cell walls in plants involves a major commitment of carbon skeletons in both the form of polysaccharides and phenylpropanoid constituents. This process is spatially ...and temporally regulated by transcription factors, including a number of MYB family transcription factors. MYB75, also called PRODUCTION OF ANTHOCYANIN PIGMENT1, is a known regulator of the anthocyanin branch of the phenylpropanoid pathway in Arabidopsis (Arabidopsis thaliana), but how this regulation might impact other aspects of carbon metabolism is unclear. We established that a loss-of-function mutation in MYB75 (myb75-1) results in increased cell wall thickness in xylary and interfascicular fibers within the inflorescence stem. The total lignin content and S/G ratio of the lignin monomers were also affected. Transcript profiles from the myb75-1 inflorescence stem revealed marked up-regulation in the expression of a suite of genes associated with lignin biosynthesis and cellulose deposition, as well as cell wall modifying proteins and genes involved in photosynthesis and carbon assimilation. These patterns suggest that MYB75 acts as a repressor of the lignin branch of the phenylpropanoid pathway. Since MYB75 physically interacts with another secondary cell wall regulator, the KNOX transcription factor KNAT7, these regulatory proteins may form functional complexes that contribute to the regulation of secondary cell wall deposition in the Arabidopsis inflorescence stem and that integrate the metabolic flux through the lignin, flavonoid, and polysaccharide pathways.
Synthetic chemical pesticides can enhance crop yields but also have undesired effects. Alternative 'botanical insecticides' may also have non-target effects on pollinators and biocontrol services. ...Employing action thresholds (ATs) can reduce pesticide (whether synthetic or botanical) use compared to fixed-interval applications. Here the azadirachtin-based botanical formulation NeemAzal and a neem seed extract (NSE) were evaluated in field spraying trials alongside commonly-used synthetics (Voliam Flexi chlorentraniliprole plus thiamethoxam and imidacloprid) in developing ATs for the regular and cosmopolitan cauliflower pests Brevicoryne brassicae, Plutella xylostella and Spodoptera litura. We considered the size of the S. litura larvae infesting the crop in order to derive ATs. ATs per plant were higher for NeemAzal (0.55 larvae for P. xylostella and 3 larvae for large-sized S. litura) than for Voliam Flexi (0.30 larvae for P. xylostella and 0.80 larvae for S. litura) but were similar for B. brassicae (50 individuals). Higher ATs when using azadirachtin were associated with the diverse modes of action of botanicals, for instance NeemAzal and NSE deterred oviposition of S. litura. Although the exact values of ATs are likely to have regional limits, our approach can be applied for determining ATs against common lepidopteran and aphid pests in many other vegetable crop agro-ecosystems.
Maximizing crop yields relies on the use of agrochemicals to control insect pests. One of the most widely used classes of insecticides are neonicotinoids that interfere with signalling of the ...neurotransmitter acetylcholine, but these can also disrupt crop-pollination services provided by bees. Here, we analysed whether chronic low dose long-term exposure to the neonicotinoid thiamethoxam alters gene expression and alternative splicing in brains of Africanized honey bees, Apis mellifera, as adaptation to altered neuronal signalling. We find differentially regulated genes that show concentration-dependent responses to thiamethoxam, but no changes in alternative splicing. Most differentially expressed genes have no annotated function but encode short Open Reading Frames, a characteristic feature of anti-microbial peptides. As this suggested that immune responses may be compromised by thiamethoxam exposure, we tested the impact of thiamethoxam on bee immunity by injecting bacteria. We show that intrinsically sub-lethal thiamethoxam exposure makes bees more vulnerable to normally non-pathogenic bacteria. Our findings imply a synergistic mechanism for the observed bee population declines that concern agriculturists, conservation ecologists and the public.
To determine the limitations of using light-curable resin-based luting composites (RBLCs) to bond indirect ceramic/resin-composite restorations by measuring light transmittance through indirect ...restorative materials and the resulting degree of conversion (DC) of the luting-composites placed underneath.
Various thicknesses (0–4mm) and shades of LAVA Zirconia and LAVA Ultimate were prepared and used as light curing filters. A commercial, light curable RBLC, RelyX Veneer (control) was compared with four experimental RBLCs of the following composition: TEGDMA/BisGMA (50/50 or 30/70wt%, respectively); camphorquinone/amine (0.2/0.8wt%) or Lucirin-TPO (0.42wt%); microfillers (55wt%) and nanofillers (10wt%). RBLCs covered with the LAVA filter were light-cured for 40s, either with the dual-peak BluephaseG2 or an experimental device emitting either in the blue or violet visible band. The samples were analyzed by Raman spectroscopy to determine DC. Light transmittance through the filters was measured using a common spectroscopy technique.
All the factors studied significantly influenced DC (p<0.05). RBLCs with increased TEGDMA content exhibited higher DC. Only small differences were observed comparing DC without filters and filters ≤1mm (p>0.05). For thicknesses ≥2mm, significant reductions in DC were observed (p<0.05). Transmittance values revealed higher filter absorption at 400nm than 470nm. A minimal threshold of irradiance measured through the filters that maintained optimal DC following 40s irradiation was identified for each RBLC formulation, and ranged between 250–500mW/cm2.
This work confirmed that optimal photopolymerization of RBLCs through indirect restorative materials (≤4mm) and irradiation time of 40s is possible, but only in some specific conditions. The determination of such conditions is likely to be key to clinical success, and all the factors need to be optimized accordingly.
Bothersome urinary symptoms plague many older adults and disproportionally affect women. Underreporting of symptoms and general stigma/embarrassment associated with incontinence has negatively ...impacted the availability of treatments, as research cannot be championed if the severity of the problem is not apparent. Available therapeutics have limited efficacy and are often not recommended in aged patients. Lower urinary tract function has a long and rich history in animal studies; while much of the underlying anatomy has been described, including neural control mechanisms, the impact of aging has only just begun to be addressed. Recent work has provided strong evidence that neural control over micturition is significantly impacted by aging processes. This mini review discusses recent findings regarding how aging impacts the neural control mechanisms of micturition.
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