As population structure can result in spurious associations, it has constrained the use of association studies in human and plant genetics. Association mapping, however, holds great promise if true ...signals of functional association can be separated from the vast number of false signals generated by population structure. We have developed a unified mixed-model approach to account for multiple levels of relatedness simultaneously as detected by random genetic markers. We applied this new approach to two samples: a family-based sample of 14 human families, for quantitative gene expression dissection, and a sample of 277 diverse maize inbred lines with complex familial relationships and population structure, for quantitative trait dissection. Our method demonstrates improved control of both type I and type II error rates over other methods. As this new method crosses the boundary between family-based and structured association samples, it provides a powerful complement to currently available methods for association mapping.
Plant phenolic compounds such as flavonoids and lignin precursors are important constituents of the human diet. These dietary phytophenolics have been recognized largely as beneficial antioxidants ...that can scavenge harmful active oxygen species including O
2
−, H
2O
2,
OH, and
1O
2. Here we review our current understanding of the antioxidant and prooxidant actions of phenolics in plant cells. In plant systems, phytophenolics can act as antioxidants by donating electrons to guaiacol-type peroxidases (GuPXs) for the detoxification of H
2O
2 produced under stress conditions. As a result of such enzymatic as well as non-enzymatic antioxidant reactions, phenoxyl radicals are formed as the primary oxidized products. Until recently, phenoxyl radicals had been difficult to detect by static electron spin resonance (ESR) because they rapidly change to non-radical products. Application of Zn exerts spin-stabilizing effects on phenoxyl radicals that enables us to analyze the formation and decay kinetics of the radicals. The ESR signals of phenoxyl radicals are eliminated by monodehydroascorbate radical (MDA) reductase, suggesting that phenoxyl radicals, like the ascorbate radical, are enzymatically recycled to parent phenolics. Thus, phenolics in plant cells can form an antioxidant system equivalent to that of ascorbate. In contrast to their antioxidant activity, phytophenolics also have the potential to act as prooxidants under certain conditions. For example, flavonoids and dihydroxycinnamic acids can nick DNA via the production of radicals in the presence of Cu and O
2. Phenoxyl radicals can also initiate lipid peroxidation. Recently, Al, Zn, Ca, Mg and Cd have been found to stimulate phenoxyl radical-induced lipid peroxidation. We discuss the mechanism of phenoxyl radical prooxidant activity in terms of lifetime prolongation by spin-stabilizing agents.
Acorn worms, also known as enteropneust (literally, 'gut-breathing') hemichordates, are marine invertebrates that share features with echinoderms and chordates. Together, these three phyla comprise ...the deuterostomes. Here we report the draft genome sequences of two acorn worms, Saccoglossus kowalevskii and Ptychodera flava. By comparing them with diverse bilaterian genomes, we identify shared traits that were probably inherited from the last common deuterostome ancestor, and then explore evolutionary trajectories leading from this ancestor to hemichordates, echinoderms and chordates. The hemichordate genomes exhibit extensive conserved synteny with amphioxus and other bilaterians, and deeply conserved non-coding sequences that are candidates for conserved gene-regulatory elements. Notably, hemichordates possess a deuterostome-specific genomic cluster of four ordered transcription factor genes, the expression of which is associated with the development of pharyngeal 'gill' slits, the foremost morphological innovation of early deuterostomes, and is probably central to their filter-feeding lifestyle. Comparative analysis reveals numerous deuterostome-specific gene novelties, including genes found in deuterostomes and marine microbes, but not other animals. The putative functions of these genes can be linked to physiological, metabolic and developmental specializations of the filter-feeding ancestor.
To assess the prospective associations of circulating levels of omega 3 polyunsaturated fatty acid (n-3 PUFA) biomarkers (including plant derived α linolenic acid and seafood derived eicosapentaenoic ...acid, docosapentaenoic acid, and docosahexaenoic acid) with incident chronic kidney disease (CKD).
Pooled analysis.
A consortium of 19 studies from 12 countries identified up to May 2020.
Prospective studies with measured n-3 PUFA biomarker data and incident CKD based on estimated glomerular filtration rate.
Each participating cohort conducted de novo analysis with prespecified and consistent exposures, outcomes, covariates, and models. The results were pooled across cohorts using inverse variance weighted meta-analysis.
Primary outcome of incident CKD was defined as new onset estimated glomerular filtration rate <60 mL/min/1.73 m
. In a sensitivity analysis, incident CKD was defined as new onset estimated glomerular filtration rate <60 mL/min/1.73 m
and <75% of baseline rate.
25 570 participants were included in the primary outcome analysis and 4944 (19.3%) developed incident CKD during follow-up (weighted median 11.3 years). In multivariable adjusted models, higher levels of total seafood n-3 PUFAs were associated with a lower incident CKD risk (relative risk per interquintile range 0.92, 95% confidence interval 0.86 to 0.98; P=0.009, I
=9.9%). In categorical analyses, participants with total seafood n-3 PUFA level in the highest fifth had 13% lower risk of incident CKD compared with those in the lowest fifth (0.87, 0.80 to 0.96; P=0.005, I
=0.0%). Plant derived α linolenic acid levels were not associated with incident CKD (1.00, 0.94 to 1.06; P=0.94, I
=5.8%). Similar results were obtained in the sensitivity analysis. The association appeared consistent across subgroups by age (≥60
<60 years), estimated glomerular filtration rate (60-89
≥90 mL/min/1.73 m
), hypertension, diabetes, and coronary heart disease at baseline.
Higher seafood derived n-3 PUFA levels were associated with lower risk of incident CKD, although this association was not found for plant derived n-3 PUFAs. These results support a favourable role for seafood derived n-3 PUFAs in preventing CKD.
The cover of the ericaceous shrub Kalmia angustifolia L. (sheep's laurel or lamb's kill) expands rapidly on many clear-cut sites through central Newfoundland and northern Quebec. Previous laboratory ...and greenhouse studies on the effect of Kalmia on black spruce (Picea mariana (Mill.) B.S.P.) germinants and seedlings have demonstrated that extracts of Kalmia leaves and soil can reduce the germination rate and early root and shoot growth of black spruce. Observations in the field have suggested that Kalmia leaves and soil can reduce the germination rate and early rot and shoot growth of black spruce. Observations in the field have suggested that Kalmia reduces the growth of planted spruce seedlings. The experiments presented in this thesis were designed to determine the importance of Kalmia in controlling spruce growth and nutrition, and to document how the importance of Kalmia varies from site to site. Spruce seedlings growing in close proximity to Kalmia were found to be shorter and had lower foliar concentrations of N and P, and the roots of these seedlings had lower rates of mycorrhization and a more frequent occurrence of the pseudo-mycorrhizal/pathogenic fungus Phialocephala dimorphospora Kendrick. Results suggest that Kalmia impedes the N nutrition of spruce seedlings through the reduction of N mineralization rates and N availability. The results of path analysis further suggest that Kalmia had a direct effect on both spruce foliar N concentration and spruce growth. These findings do not demonstrate, though they are consistent with the suggestion, that Kalmia can affect spruce through allelopathic processes. Although we could not demonstrate that the reduction of rates of mycorrhization were due to indirect effects of Kalmia on spruce nutrition, we demonstrated that improving spruce nutrition in close proximity to Kalmia increased, though not significantly, the occurrence of mycorrhizae on spruce roots. Mycorrhizal symbiosis was shown to play a key role in t
Chlorogenic acid (CGA; 3‐o‐caffeoylquinic acid), a phenylpropanoid metabolite of plants, was oxidized by H2O2 in the presence of horseradish peroxidase. The primary and secondary oxidized products ...both were free radicals which gave EPR multiline signals at g=2.0044 and 2.0042 in the presence of zinc as a spin stabilizing agent. The EPR kinetics showed that ascorbate functioned as a cooperative reductant by regenerating CGA from its corresponding radicals. These results provide evidence to support the idea that the ascorbate‐phenolic redox couple in conjunction with guaiacol peroxidase is an efficient H2O2 scavenging mechanism in higher plants.
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