Cell Wall Composition and Bioenergy Potential of Rice Straw Tissues Are Influenced by Environment,Tissue Type,and Genotype

Breeding has transformed wild plant species into modern crops, increasing the allocation of their photosynthetic assimilate into grain, fiber, and other products for human use. Despite progress in increasing the harvest index, much of the biomass of crop plants is not utilized. Potential uses for the large amounts of agricultural residues that accumulate are animal fodder or bioenergy, though these may not be economically viable without additional efforts such as targeted breeding or improved processing. We characterized leaf and stem tissue from a diverse set of rice genotypes (varieties) grown in two environments (greenhouse and field) and report bioenergy-related traits across these variables. Among the 16 traits measured, cellulose, hemicelluloses, lignin, ash, total glucose, and glucose yield changed across environments, irrespective of the genotypes. Stem and leaf tissue composition differed for most traits, consistent with their unique functional contributions and suggesting that they are under separate genetic control. Plant variety had the least influence on the measured traits. High glucose yield was associated with high total glucose and hemicelluloses, but low lignin and ash content. Bioenergy yield of greenhouse-grown biomass was higher than field-grown biomass, suggesting that greenhouse studies overestimate bioenergy potential. Nevertheless, glucose yield in the greenhouse predicts glucose yield in the field (ρ?=?0.85, p?<?0.01) and could be used to optimize greenhouse (GH) and field breeding trials. Overall, efforts to improve cell wall composition for bioenergy require consideration of production environment, tissue type, and variety.     

Loss of lysosomal membrane protein NCU-G1 in mice results in spontaneous liver fibrosis with accumulation of lipofuscin and iron in Kupffer cells

Human kidney predominant protein, NCU-G1, is a highly conserved protein with an unknown biological function. Initially described as a nuclear protein, it was later shown to be a bona fide lysosomal integral membrane protein. To gain insight into the physiological function of NCU-G1, mice with no detectable expression of this gene were created using a gene-trap strategy, and Ncu-g1^gt/gt mice were successfully characterized. Lysosomal disorders are mainly caused by lack of or malfunctioning of proteins in the endosomal-lysosomal pathway. The clinical symptoms vary, but often include liver dysfunction. Persistent liver damage activates fibrogenesis and, if unremedied, eventually leads to liver fibrosis/cirrhosis and death. We demonstrate that the disruption of Ncu-g1 results in spontaneous liver fibrosis in mice as the predominant phenotype. Evidence for an increased rate of hepatic cell death, oxidative stress and active fibrogenesis were detected in Ncu-g1^gt/gt liver. In addition to collagen deposition, microscopic examination of liver sections revealed accumulation of autofluorescent lipofuscin and iron in Ncu-g1^gt/gt Kupffer cells. Because only a few transgenic mouse models have been identified with chronic liver injury and spontaneous liver fibrosis development, we propose that the Ncu-g1^gt/gt mouse could be a valuable new tool in the development of novel treatments for the attenuation of fibrosis due to chronic liver damage.KEY WORDS: NCU-G1, Lysosome, Fibrosis     

Exosome-producing follicle associated epithelium is not involved in uptake of PrPd from the gut of sheep (Ovis aries): an ultrastructural study

In natural or experimental oral scrapie infection of sheep, disease associated prion protein (PrP(d)) often first accumulates in Peyer's patch (PP) follicles. The route by which infectivity reaches the follicles is unknown, however, intestinal epithelial cells may participate in intestinal antigenic presentation by delivering exosomes as vehicles of luminal antigens. In a previous study using an intestinal loop model, following inoculation of scrapie brain homogenate, inoculum associated PrP(d) was detected by light microscopy shortly (15 minutes to 3.5 hours) after inoculation in the villous lacteals and sub-mucosal lymphatics. No PrP(d) was located within the follicle-associated epithelium (FAE), sub-FAE domes or the PP follicles. To evaluate this gut loop model and the transportation routes in more detail, we used electron microscopy (EM) to study intestinal tissues exposed to scrapie or control homogenates for 15 minutes to 10 days. In addition, immuno-EM was used to investigate whether exosomes produced in the FAE may possess small amounts of PrP(d) that were not detectable by light microscopy. This study showed that the integrity of the intestinal epithelium was sustained in the intestinal loop model. Despite prominent transcytotic activity and exosome release from the FAE of the ileal PP in sheep, these structures were not associated with transportation of PrP(d) across the mucosa. The study did not determine how infectivity reaches the follicles of PPs. The possibility that the infectious agent is transported across the FAE remains a possibility if it occurs in a form that is undetectable by the methods used in this study. Infectivity may also be transported via lymph to the blood and further to all other lymphoid tissues including the PP follicles, but the early presence of PrP(d) in the PP follicles during scrapie infection argues against such a mechanism.     

Conflict resolution attempts in self-determination disputes: the significance of local minority groups concerns in the Philippines and Sri Lanka

The way in which the minority within minority question is solved has implications for settlement of self-determination conflicts. This paper examines how this question plays out in connection with negotiations of peace agreements. It focuses on the negotiations on the Bangsamoro Juridical Entity in the Philippines in 2008 and the Fifth Peace Process in Sri Lanka in 2002–06. By analysing constitutional design options in terms of integration, power sharing and power dividing, it outlines how minority concerns are articulated and eventually how they have implications for negotiations. The absence of power-sharing guarantees was a major concern among elites not associated with the self-determination project, both at the national and the local level. They blocked implementation of the deals, insisting instead on integration and power dividing. These findings highlight the shortcomings of negotiations that overlook the multifaceted majority/minority conflicts at national and local levels and how they are interlinked.     

Floating Ice-Algal Aggregates below Melting Arctic Sea Ice

During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year.     

Metabolism of gibberellin A19 is under photoperiodic control in Populus, Salix and Betula, but not in daylength-insensitive Populus overexpressing phytochrome A

Application experiments have suggested that short‐day‐induced cessation of elongation growth in trees is caused by photoperiodic regulation of the conversion of gibberellin GA₁₉ to GA₂₀. In the present study we examined further the photoperiodic control of GA metabolism in trees with focus on the conversion of GA₁₉ in Salix pentandra, hybrid aspen (Populus tremula × tremuloides) and silver birch (Betula pendula) using [17,17‐²H₂]‐GA₁₉ or unlabelled GAs in application studies. GA₂₀ and GA₁ were able to restore growth also in hybrid aspen and silver birch under short days (SD), whereas GA₁₉ had no or only a very small activity. Contrary to hybrid aspen and S. pentandra, the activity of GA₂₀ in silver birch was significantly lower than that of GA₁. Gas chromatography‐mass spectrometry (GC‐MS) analysis revealed a smaller turnover of [²H₂]‐GA₁₉ in SD than in long days (LD) in hybrid aspen. No such difference in turnover of [²H₂]‐GA₁₉ was observed in photoperiod‐insensitive hybrid aspen overexpressing PHYA. Application of unlabelled GAs to seedlings of S. pentandra, hybrid aspen and silver birch under SD followed by quantification of metabolites by GC‐MS analysis, showed that applied GA₁₉ was not readily converted to GA₂₀ and GA₁. Although the sensitivity to GAs is also known to decrease under SD, the present data are in favour of a photoperiodic regulation of the metabolism of GA₁₉in vivo in the woody species S. pentandra, hybrid aspen and silver birch. The data might also suggest that silver birch differs from S. pentandra and hybrid aspen by exhibiting a possible photoperiodic control also of the conversion of GA₂₀ to GA₁.