Agriculture and Agri-Food Canada

About: Agriculture and Agri-Food Canada is a facility organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Soil water. The organization has 10921 authors who have published 21332 publications receiving 748193 citations. The organization is also known as: Department of Agriculture and Agri-Food.

HISTONE DEACETYLASE19 interacts with HSL1 and participates in the repression of seed maturation genes in Arabidopsis seedlings.

Abstract: The seed maturation genes are specifically and highly expressed during late embryogenesis. In this work, yeast two-hybrid, bimolecular fluorescence complementation, and coimmunoprecipitation assays revealed that HISTONE DEACETYLASE19 (HDA19) interacted with the HIGH-LEVEL EXPRESSION OF SUGAR-INDUCIBLE GENE2-LIKE1 (HSL1), and the zinc-finger CW [conserved Cys (C) and Trp (W) residues] domain of HSL1 was responsible for the interaction. Furthermore, we found that mutations in HDA19 resulted in the ectopic expression of seed maturation genes in seedlings, which was associated with increased levels of gene activation marks, such as Histone H3 acetylation (H3ac), Histone H4 acetylation (H4ac), and Histone H3 Lys 4 tri-methylation (H3K4me3), but decreased levels of the gene repression mark Histone H3 Lys 27 tri-methylation (H3K27me3) in the promoter and/or coding regions. In addition, elevated transcription of certain seed maturation genes was also found in the hsl1 mutant seedlings, which was also accompanied by the enrichment of gene activation marks but decreased levels of the gene repression mark. Chromatin immunoprecipitation assays showed that HDA19 could directly bind to the chromatin of the seed maturation genes. These results suggest that HDA19 and HSL1 may act together to repress seed maturation gene expression during germination. Further genetic analyses revealed that the homozygous hsl1 hda19 double mutants are embryonic lethal, suggesting that HDA19 and HSL1 may play a vital role during embryogenesis.

A collagen–chitosan hydrogel for endothelial differentiation and angiogenesis.

Abstract: Cell therapy for the treatment of cardiovascular disease has been hindered by low cell engraftment, poor survival, and inadequate phenotype and function. In this study, we added chitosan to a previously developed injectable collagen matrix, with the aim of improving its properties for cell therapy and neovascularization. Different ratios of collagen and chitosan were mixed and chemically crosslinked to produce hydrogels. Swell and degradation assays showed that chitosan improved the stability of the collagen hydrogel. In culture, endothelial cells formed significantly more vascular-like structures on collagen–chitosan than collagen-only matrix. While the differentiation of circulating progenitor cells to CD31+ cells was equal on all matrices, vascular endothelial-cadherin expression was increased on the collagen–chitosan matrix, suggesting greater maturation of the endothelial cells. In addition, the collagen–chitosan matrix supported a significantly greater number of CD133+ progenitor cells than the collagen-only matrix. In vivo, subcutaneously implanted collagen–chitosan matrices stimulated greater vascular growth and recruited more von Willebrand factor (vWF+) and CXCR4+ endothelial/angiogenic cells than the collagen-only matrix. These results indicate that the addition of chitosan can improve the physical properties of collagen matrices, and enhance their ability to support endothelial cells and angiogenesis for use in cardiovascular tissue engineering applications.

Using a modified ferrous oxidation-xylenol orange (FOX) assay for detection of lipid hydroperoxides in plant tissue.

Abstract: The ferrous oxidation−xylenol orange (FOX) assay was adapted for quantifying lipid hydroperoxides (LOOHs) in plant extracts. Excised pieces of several fruit and vegetable species were exposed to 83 kJ m-2 day-1 of biologically effective ultraviolet B irradiance (UV-BBE) for 10−12 days to induce cellular oxidation. The LOOH and thiobarbituric acid reactive substance (TBARS) concentrations of these plant tissues were assessed with the FOX and iodometric assays for the former and a modified TBARS assay for the latter. There was generally good agreement between the FOX and iodometric methods both prior to and following the UV exposure. However, the iodometric assay appeared to have some difficulty in consistently quantifying lower LOOH levels (<11 μM), whereas the FOX assay measured LOOH concentrations as low as 5 μM. All tissues exhibited UV-induced increases in TBARS, indicating a marked degree of cellular oxidation in the exposed tissue segments. Compared with the iodometric assay, the FOX method consisten...