Changes In Tissue Chemistry Research Articles

Bog plant/lichen tissue nitrogen and sulfur concentrations as indicators of emissions from oil sands development in Alberta, Canada

Increasing gaseous emissions of nitrogen (N) and sulfur (S) associated with oil sands development in northern Alberta (Canada) has led to changing regional wet and dry N and S deposition regimes. We assessed the potential for using bog plant/lichen tissue chemistry (N and S concentrations, C:N and C:S ratios, in 10 plant/lichen species) to monitor changing atmospheric N and S deposition through sampling at five bog sites, 3–6 times per growing season from 2009 to 2016. During this 8-year period, oil sands N emissions steadily increased, while S emissions steadily decreased. We examined the following: (1) whether each species showed changes in tissue chemistry with increasing distance from the Syncrude and Suncor upgrader stacks (the two largest point sources of N and S emissions); (2) whether tissue chemistry changed over the 8 year period in ways that were consistent with increasing N and decreasing S emissions from oil sands facilities; and (3) whether tissue chemistry was correlated with growing season wet deposition of NH4+-N, NO3−-N, or SO42−-S. Based on these criteria, the best biomonitors of a changing N deposition regime were Evernia mesomorpha, Sphagnum fuscum, and Vaccinium oxycoccos. The best biomonitors of a changing S deposition regime were Evernia mesomorpha, Cladonia mitis, Sphagnum fuscum, Sphagnum capillifolium, Vaccinium oxycoccos, and Picea mariana. Changing N and S deposition regimes in the oil sands region appear to be influencing N and S cycling in what once were pristine ombrotrophic bogs, to the extent that these bogs may effectively monitor future spatial and temporal patterns of deposition.

Litters of photosynthetically divergent grasses exhibit differential metabolic responses to warming and elevated CO2

Climatic stress such as warming would alter physiological pathways in plants leading to changes in tissue chemistry. Elevated CO2 could partly mitigate warming induced moisture stress, and the degree of this mitigation may vary with plant functional types. We studied the composition of structural and non‐structural metabolites in senesced tissues of Bouteloua gracilis (C4) and Pascopyrum smithii (C3) at the Prairie Heating and CO2 Enrichment experiment, Wyoming, USA. We hypothesized that P. smithii and B. gracilis would respond to unfavorable global change factors by producing structural metabolites and osmoregulatory compounds that are necessary to combat stress. However, due to the inherent variation in the tolerance of their photosynthetic pathways to warming and CO2, we hypothesized that these species will exhibit differential response under different combinations of warming and CO2 conditions. Due to a lower thermo‐tolerance of the C4 photosynthesis we expected B. gracilis to exhibit a greater metabolic response under warming with ambient CO2 (cT) and P. smithii to exhibit a similar response under warming combined with elevated CO2 (CT). Our hypothesis was supported by the differential response of structural compounds in these two species, where cT increased the content of lignin and cuticular‐matrix in B. gracilis. In P. smithii a similar response was observed in plants exposed to CT, possibly due to the partial alleviation of moisture stress. With warming, the total cell‐wall bound phenolic acids that cross link polysaccharides to lignins increased in B. gracilis and decreased in P. smithii, indicating a potentially adaptive response of C4 pathway to warming alone. Similarly, in B. gracilis, extractable polar metabolites such as sugars and phenolic acids increased with the main effect of warming. Conversely, in P. smithii, only sugars showed a higher abundance in plants exposed to warming treatments indicating that warming alone might be metabolically too disruptive for the C3 photosynthetic pathway. Here we show for the first time, that along with traditionally probed extractable metabolites, warming and elevated CO2 differentially influence the structural metabolites in litters of photosynthetically divergent grass species. If these unique metabolite responses occur in other species of similar functional types, this could potentially alter carbon cycling in grasslands due to the varying degradability of these litters.

Impact of UV-A radiation on the performance of aphids and whiteflies and on the leaf chemistry of their host plants

Ultraviolet (UV) radiation directly regulates a multitude of herbivore life processes, in addition to indirectly affecting insect success via changes in plant chemistry and morphogenesis. Here we looked at plant and insect (aphid and whitefly) exposure to supplemental UV-A radiation in the glasshouse environment and investigated effects on insect population growth. Glasshouse grown peppers and eggplants were grown from seed inside cages covered by novel plastic filters, one transparent and the other opaque to UV-A radiation. At a 10-true leaf stage for peppers (53days) and 4-true leaf stage for eggplants (34days), plants were harvested for chemical analysis and infested by aphids and whiteflies, respectively. Clip-cages were used to introduce and monitor the insect fitness and populations of the pests studied. Insect pre-reproductive period, fecundity, fertility and intrinsic rate of natural increase were assessed. Crop growth was monitored weekly for 7 and 12weeks throughout the crop cycle of peppers and eggplants, respectively. At the end of the insect fitness experiment, plants were harvested (68days and 18-true leaf stage for peppers, and 104days and 12-true leaf stage for eggplants) and leaves analysed for secondary metabolites, soluble carbohydrates, amino acids, total proteins and photosynthetic pigments. Our results demonstrate for the first time, that UV-A modulates plant chemistry with implications for insect pests. Both plant species responded directly to UV-A by producing shorter stems but this effect was only significant in pepper whilst UV-A did not affect the leaf area of either species. Importantly, in pepper, the UV-A treated plants contained higher contents of secondary metabolites, leaf soluble carbohydrates, free amino acids and total content of protein. Such changes in tissue chemistry may have indirectly promoted aphid performance. For eggplants, chlorophylls a and b, and carotenoid levels decreased with supplemental UV-A over the entire crop cycle but UV-A exposure did not affect leaf secondary metabolites. However, exposure to supplemental UV-A had a detrimental effect on whitefly development, fecundity and fertility presumably not mediated by plant cues as compounds implied in pest nutrition – proteins and sugars – were unaltered.

Vegetation Response to a One-Time Spent Drilling Mud Application to Semiarid, Mixed-Grass Prairie

Landspraying while drilling (LWD) is an approved disposal method for water-based drilling mud (WBM) systems in western Canada. The mud is applied either on cultivated land, where it is incorporated by cultivation, or on vegetated land where it is not incorporated. This study examined the effects of summer WBM application (0, 15, 20, 40, and 80 m3 · ha−1) on native vegetation properties. Our results indicated that LWD increased bare ground but decreased lichen cover at the 80 m3 · ha−1 rate relative to the untreated control. Nitrogen (N), sulfur (S), and magnesium (Mg) concentrations in aboveground plant tissue increased with increasing LWD rate in samples taken 45 d after WBM application, but these differences disappeared 1 yr after treatment. Increase in tissue concentration of phosphorus (P) with LWD rate, however, was only detected 3 yr after LWD. Nonetheless, these changes in tissue chemistry were not associated with significant changes in biomass yield or species composition. Overall, our results suggest that single WBM applications at rates (≤ 20 m3 · ha−1) commonly used in western Canada, if properly managed, are unlikely to adversely affect native prairie vegetation. El rociado del terreno durante la perforación (LWD) es un sistema aprobado de eliminación de lodo en sistemas de perforación basados en el uso de agua (WBM) en el oeste de Canadá. El lodo puede aplicarse a tierras arables, donde es incorporado al suelo mediante la labranza, o a tierras con cobertura de vegetación donde no es incorporada al suelo. Este estudio examinó el efecto de la aplicación de WBM durante el verano (0, 15, 20, 40, y 80 m3 · ha−1) sobre las propiedades de la vegetación nativa de la pradera. Nuestros resultados indicaron que el LWD incrementó el suelo desnudo pero provocó una disminución en la cobertura de líquenes comparado con el testigo cuando la aplicación fue de 80 m3 · ha−1. La concentración de nitrógeno (N), azufre (S), y magnesio (Mg) en los tejidos vegetales aéreos aumentó con incrementos en la dosis de LWD en muestras tomadas 45 días luego de la aplicación del WBM, pero estas diferencias desaparecieron un año después del tratamiento. El aumento en la concentración de fósforo (P), sin embargo, sólo se detectó tres años después del LWD. No obstante, estos cambios en la composición química de los tejidos no estuvieron asociados a cambios significativos en la producción de biomasa o en la composición de especies. Nuestros resultados sugieren que en general, una única aplicación de WBM en dosis (≤ 20 m3 · ha−1) comúnmente usadas en el oeste de Canadá, no tendría un efecto negativo sobre la vegetación de la pradera si la misma es manejada correctamente.

Folivory versus florivory—adaptiveness of flower feeding

The distribution of resources and defence is heterogeneous within plants. Specialist insects may prefer tissue with high concentrations of the plant's characteristic defence compounds. Most herbivorous butterfly or sawfly larvae are considered to be folivores, so also the turnip sawfly Athalia rosae (Hymenoptera: Tenthredinidae), a specialist herbivore on Brassicaceae. We investigated which tissue larvae choose to feed upon and how they perform on flowers, young or old leaves of Sinapis alba. Furthermore, constitutive and inducible levels of glucosinolates and myrosinases were investigated and nutrients analysed. Larvae moved from leaves to flowers for feeding from the third larval instar on. Flowers were not actively chosen, but larvae moved upwards on the plant, regardless of how plants were orientated (upright or inverted). Flower-feeding larvae were heavier and developed faster than larvae feeding on young leaves, and adults laid more eggs. Old leaves as food source resulted in the lowest growth rates. Flowers contained three and ten times higher myrosinase activities than young and old leaves, respectively, whereas glucosinolate concentrations and nitrogen levels of flowers and young leaves were comparable. Glucosinolate concentrations of old leaves were very low. Changes in tissue chemistry caused by larval feeding were tissue specific. Defence levels did not change in flowers and old leaves after A. rosae feeding in contrast to young leaves. The high insect performance on flowers cannot be explained by differences in chemical defence. Instead, the lack of mechanical defence (trichomes) is probably responsible. Movement to the flowers and folivory is overall highly adaptive for this sawfly species.

Magnetic properties of human hippocampal tissue—Evaluation of artefact and contamination sources

To investigate the possibility that postmortem chemical alteration or contamination is responsible for recent results indicating the presence of magnetite in human brain tissue and to determine whether magnetite is present in living brain tissue, we examined tissue samples resected from six patients during amygdalohippocampectomy operations. The tissue samples were sealed in sterilized vials in the operating theater and placed into liquid nitrogen directly after removal to prevent changes in tissue chemistry after the death of the brain cells. The low temperature magnetic properties of the tissue were measured to determine the presence of ferro- or ferrimagnetic material in the tissue. The results of these experiments indicate that magnetite is present in the tissue. In addition, results of experiments designed to control for airborne contamination and contamination during cauterization of vessels during surgery indicate that these are not significant sources of magnetite contamination in the tissue.

Studies on the salivary physiology of plant bugs: Function of the catechol oxidase of the rose aphid

“Polyphenol oxidase” activity, similar to that previously demonstrated in the saliva and/or salivary glands of Homoptera and various Heteroptera, was readily detectable histochemically in the salivary glands of Macrosiphum rosae. Damp filter paper probed by M. rosae and their stylet sheaths also showed oxidase activity, and the reaction with various substrates indicated that it should properly be termed a catechol oxidase (EC 1.10.3.1). The feeding activity of the rose aphid caused oxidative polymerization of catechin, catechol, l-DOPA, and dl-DOPA in sucrose diets, and of naturally occurring catechin in deproteinated tissue sap pressed from the pedicels of rose buds. Tissue sap became more acceptable to the aphids as a result of oxidation. When the rose aphid fed on stems of semi-dormant miniature rose bushes, catechin content was reduced in the immediate vicinity of colonies, but rose temporarily to higher than normal levels after the insects had been removed. When the roses were growing vigorously, however, rapid changes in tissue chemistry tended to mask this interaction.

Infrared studies of human and other tissues by the attenuated total reflection technique

Infrared spectra of human and animal tissues have been recorded by the methods of attenuated total reflection (both single- and multiple-reflection equipment). Little preparation of the samples is necessary. Single-reflection spectra have shown the application of the method for examining tissues, both normal and diseased. The changes in tissue chemistry produced by the diseased state are evident. Multiple reflection has afforded more intense bands and increased the resolution of the spectra. The tissues examined were human fat, spleen, and aorta, and rat heart, chicken heart, and veal heart (endocardium and atrium). The useful infrared ATR range for tissues has been extended beyond 2000 cm −1 to approximately 3000 cm −1.