Inheritance Of Resistance To Mammalian Herbivores and Of Plant Defensive Chemistry In A <Emphasis Type="Italic">Eucalyptus</Emphasis> Species

Hybridization in plants provides an opportunity to investigate the patterns of inheritance of hybrid resistance to herbivores, and of the plant mechanisms conferring this resistance such as plant secondary metabolites. We investigated how inter-race differences in resistance of Eucalyptus globulus to a generalist mammalian herbivore, Trichosurus vulpecula, are inherited in their F₁ hybrids. We assessed browsing damage of three-year-old trees in a common environment field trial on four hybrid types of known progeny. The progency were artificial intra-race crosses and reciprocal inter-race F₁ hybrids of two geographically distinct populations (races) of E. globulus; north-eastern Tasmania and south-eastern Tasmania. Populations of trees from north-eastern Tasmania are relatively susceptible to browsing by T. vulpecula, while populations from south-eastern Tasmania are more resistant. We assessed the preferences of these trees in a series of paired feeding trials with captive animals to test the field trial results and also investigated the patterns of inheritance of plant secondary metabolites. Our results demonstrated that the phenotypic expression of resistance of the inter-race F₁ hybrids supported the additive pattern of inheritance, as these hybrids were intermediate in resistance compared to the pure parental hybrids. The expression of plant secondary metabolites in the F₁ hybrids varied among groups of individual compounds. The most common pattern supported was dominance towards one of the parental types. Together, condensed tannins and essential oils appeared to explain the observed patterns of resistance among the four hybrid types. While both chemical groups were inherited in a dominant manner in the inter-race F₁ hybrids, the direction of dominance was opposite. Their combined concentration, however, was inherited in an additive manner, consistent with the phenotypic differences in browsing.     

Sediment storage and shallow groundwater response to beaver dam analogues in the Colorado Front Range,USA

Enthusiasm for using beaver dam analogues (BDAs) to restore incised channels and riparian corridors has been increasing. BDAs are expected to create a similar channel response to natural beaver dams by causing channel bed aggradation and overbank flow, which subsequently raise water tables and support vegetation growth. However, lack of funding for monitoring projects post‐restoration has limited research on whether BDAs actually cause expected channel change in the Front Range and elsewhere. Geomorphic and hydrologic response to BDAs was monitored in two watersheds 1 year post‐restoration. BDAs were studied at Fish Creek, a steep mountainous catchment, and Campbell Creek, a lower gradient piedmont catchment from May to October 2018. At each restoration site, the upstream‐ and downstream‐most BDAs were chosen for intensive study in comparison with unrestored reference reaches. Monitoring focused on quantifying sediment volumes in BDA ponds and recording changes to stream stage and riparian groundwater. Despite differences in physical basin characteristics, BDA pools at both sites stored similar volumes of sediment and stored more sediment than reference pools. Sediment storage is positively correlated to BDA height and pool surface area. However, BDAs did not have a significant influence on shallow groundwater. The lack of groundwater response proximal to BDAs could indicate that local watershed factors have a stronger influence on groundwater response than restoration design 1 year post‐restoration. Systematic, long‐term studies of channel and floodplain response to BDAs are needed to better understand how BDAs will influence geomorphology and hydrology.     

Optimal Filters from Calibration Data for Image Deconvolution with Data Acquisition Error

Data acquisition errors due to dead pixels or other hardware defects can cause undesirable artifacts in imaging applications. Compensating for these defects typically requires knowledge such as a defective pixel map, which can be difficult or costly to obtain and which is not necessarily static. However, recent calibration data is readily available in many applications. In this paper, we compute optimal filters for image deconvolution with denoising using only this calibration data, by minimizing the empirical Bayes risk. We derive a bound on how the reconstruction changes as the number of dead pixels grows. We show that our approach is able to reconstruct missing information better than standard filtering approaches and is robust even in the presence of a large number of defects and to defects that arise after calibration.     

Influence of the storage orientation on the aerodynamic particle size of a suspension metered dose inhaler containing propellant HFA-227

Presented in this work are the results of a study designed to investigate the impact of the storage position on the particle size distribution (PSD) of a steroid suspension metered dose inhaler (MDI) containing propellant HFA-227. It was hypothesized that the orientation of MDI samples upon storage could influence the PSD of the emitted dose, since it determines the amount of contact the liquid formulation has with the valve and therefore the quantity of nonvolatile leachable materials from the valve components that may enter the product and potentially impact the aerosol spray dynamics. Samples stored in the valve down orientation (i.e., complete contact of the liquid formulation with the valve) showed a higher level of leachables compared to those samples stored valve up (i.e., minimal contact of the formulation with the valve). The valve down samples were found to produce larger particles in the emitted aerosol spray using both cascade impaction, the preferred method of regulatory submission, as well as laser diffraction. It was postulated that the larger particle size of the inverted samples was attributed to its higher levels of leachables. Based on our findings, it is recommended that in order to set appropriate controls on the product PSD, the storage orientation of the product will need to be considered.     

The classroom environment and students' reports of avoidance strategies in mathematics: A multimethod study.

The relation between the learning environment (e.g., students' perceptions of the classroom goal structure and teachers' instructional discourse) and students' reported use of avoidance strategies (self-handicapping, avoidance of help seeking) and preference to avoid novelty in mathematics was examined. Quantitative analyses indicated that students' reports of avoidance behaviors varied significantly among classrooms. A perceived emphasis on mastery goals in the classroom was positively related to lower reports of avoidance. Qualitative analyses revealed that teachers in high-mastery/low-avoidance and low-mastery/high-avoidance classrooms used distinctively different patterns of instructional and motivational discourse. High incidence of motivational support was uniquely characteristic of high-mastery/ low-avoidance classrooms, suggesting that mastery goals may include an affective component. Implications of the results for both theory and practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and Evaluation of a Series of Bis(pentylpyridinium) Compounds as Antifungal Agents

A series of bis(4‐pentylpyridinium) compounds with a variety of spacers between the pyridinium headgroups was synthesised, and the antifungal activity of these compounds was investigated. Lengthening the alkyl spacer between the pentylpyridinium headgroups from 12 to 16 methylene units resulted in increased antifungal activity against C. neoformans and C. albicans, but also resulted in increased hemolytic activity and cytotoxicity against mammalian cells. However, inclusion of an ortho‐substituted benzene ring in the centre of the alkyl spacer resulted in decreased cytotoxicity and hemolytic activity, while maintaining antifungal potency. Replacement of the alkyl and aromatic‐containing spacers by more hydrophilic ethylene glycol groups resulted in a loss of antifungal activity. Some of the compounds inhibited fungal PLB1 activity, but the low correlation of this inhibition with antifungal potency indicates PLB1 inhibition is unlikely to be the predominant mode of antifungal action of this class of compounds, with preliminary studies suggesting they may act via disruption of fungal mitochondrial function.     

The Extended Community-Level Effects of Genetic Variation in Foliar Wax Chemistry in the Forest Tree <Emphasis Type="Italic">Eucalyptus globulus</Emphasis>

Genetic variation in foundation trees can influence dependent communities, but little is known about the mechanisms driving these extended genetic effects. We studied the potential chemical drivers of genetic variation in the dependent foliar community of the focal tree Eucalyptus globulus. We focus on the role of cuticular waxes and compare the effects to that of the terpenes, a well-studied group of secondary compounds known to be bioactive in eucalypts. The canopy community was quantified based on the abundance of thirty-nine distinctive arthropod and fungal symptoms on foliar samples collected from canopies of 246 progeny from 13 E. globulus sub-races grown in a common garden trial. Cuticular waxes and foliar terpenes were quantified using gas chromatography - mass spectrometry (GC-MC). A total of 4 of the 13 quantified waxes and 7 of the 16 quantified terpenes were significantly associated with the dependent foliar community. Variation in waxes explained 22.9% of the community variation among sub-races, which was equivalent to that explained by terpenes. In combination, waxes and terpenes explained 35% of the genetic variation among sub-races. Only a small proportion of wax and terpene compounds showing statistically significant differences among sub-races were implicated in community level effects. The few significant waxes have previously shown evidence of divergent selection in E. globulus, which signals that adaptive variation in phenotypic traits may have extended effects. While highlighting the role of the understudied cuticular waxes, this study demonstrates the complexity of factors likely to lead to community genetic effects in foundation trees.     

AFM-based analysis of human metastatic cancer cells

Recently biomechanics of cancer cells, in particular stiffness or elasticity, has been identified as an important factor relating to cancer cell function, adherence, motility, transformation and invasion. We report on the nanomechanical responses of metastatic cancer cells and benign mesothelial cells taken from human body cavity fluids using atomic force microscopy. Following our initial study (Cross et al 2007 Nat. Nanotechnol. 2 780-3), we report on the biophysical properties of patient-derived effusion cells and address the influence of cell morphology on measured cell stiffness. Using a cytocentrifugation method, which yields morphologically indistinguishable cells that can be prepared in 1?min and avoids any possible artifacts due to 12?h ex?vivo culture, we find that metastatic tumor cells are more than?80% softer than benign cells with a distribution over six times narrower than that of normal cells. Consistent with our previous study, which yielded distinguishable cell populations based on ex?vivo growth and morphological characteristics, our results show it is unlikely that morphology alone is sufficient to explain the difference in elastic moduli for these two cell types. Moreover, analysis of non-specific cell adhesion inherent to tumor and normal cells collected from patients show surface adhesion of tumor cells is ～33% less adhesive compared to that of normal cells. Our findings indicate that biomechanical-based functional analysis may provide an additional platform for cytological evaluation and diagnosis of cancer in the future.