Physiology of pepper fruit and the metabolism of antioxidants: chloroplasts,mitochondria and peroxisomes

Background and Aims Pepper (Capsicum annuum) contains high levels of antioxidants, such as vitamins A and C and flavonoids. However, information on the role of these beneficial compounds in the physiology of pepper fruit remains scarce. Recent studies have shown that antioxidants in ripe pepper fruit play a key role in responses to temperature changes, and the redox state at the time of harvest affects the nutritional value for human consumption. In this paper, the role of antioxidant metabolism of pepper fruit during ripening and in the response to low temperature is addressed, paying particular attention to ascorbate, NADPH and the superoxide dismutase enzymatic system. The participation of chloroplasts, mitochondria and peroxisomes in the ripening process is also investigated.Scope and Results Important changes occur at a subcellular level during ripening of pepper fruit. Chloroplasts turn into chromoplasts, with drastic conversion of their metabolism, and the role of the ascorbate–glutathione cycle is essential. In mitochondria from red fruits, higher ascorbate peroxidase (APX) and Mn-SOD activities are involved in avoiding the accumulation of reactive oxygen species in these organelles during ripening. Peroxisomes, whose antioxidant capacity at fruit ripening is substantially affected, display an atypical metabolic pattern during this physiological stage. In spite of these differences observed in the antioxidative metabolism of mitochondria and peroxisomes, proteomic analysis of these organelles, carried out by 2-D electrophoresis and MALDI-TOF/TOF and provided here for the first time, reveals no changes between the antioxidant metabolism from immature (green) and ripe (red) fruits.Conclusions Taken together, the results show that investigation of molecular and enzymatic antioxidants from cell compartments, especially chloroplasts, mitochondria and peroxisomes, is a useful tool to study the physiology of pepper fruit, particularly in the context of expanding their shelf-life after harvest and in maintaining their nutritional value.     

Gaseous emissions from management of solid waste: a systematic review

The establishment of sustainable soil waste management practices implies minimizing their environmental losses associated with climate change (greenhouse gases: GHGs) and ecosystems acidification (ammonia: NH₃). Although a number of management strategies for solid waste management have been investigated to quantify nitrogen (N) and carbon (C) losses in relation to varied environmental and operational conditions, their overall effect is still uncertain. In this context, we have analyzed the current scientific information through a systematic review. We quantified the response of GHG emissions, NH₃ emissions, and total N losses to different solid waste management strategies (conventional solid storage, turned composting, forced aerated composting, covering, compaction, addition/substitution of bulking agents and the use of additives). Our study is based on a meta‐analysis of 50 research articles involving 304 observations. Our results indicated that improving the structure of the pile (waste or manure heap) via addition or substitution of certain bulking agents significantly reduced nitrous oxide (N₂O) and methane (CH₄) emissions by 53% and 71%, respectively. Turned composting systems, unlike forced aerated composted systems, showed potential for reducing GHGs (N₂O: 50% and CH₄: 71%). Bulking agents and both composting systems involved a certain degree of pollution swapping as they significantly promoted NH₃ emissions by 35%, 54%, and 121% for bulking agents, turned and forced aerated composting, respectively. Strategies based on the restriction of O₂ supply, such as covering or compaction, did not show significant effects on reducing GHGs but substantially decreased NH₃ emissions by 61% and 54% for covering and compaction, respectively. The use of specific additives significantly reduced NH₃ losses by 69%. Our meta‐analysis suggested that there is enough evidence to refine future Intergovernmental Panel on Climate Change (IPCC) methodologies from solid waste, especially for solid waste composting practices. More holistic and integrated approaches are therefore required to develop more sustainable solid waste management systems.     

The contribution of trees to ecosystem methane emissions in a temperate forested wetland

Wetland‐adapted trees are known to transport soil‐produced methane (CH₄), an important greenhouse gas to the atmosphere, yet seasonal variations and controls on the magnitude of tree‐mediated CH₄ emissions remain unknown for mature forests. We examined the spatial and temporal variability in stem CH₄ emissions in situ and their controls in two wetland‐adapted tree species (Alnus glutinosa and Betula pubescens) located in a temperate forested wetland. Soil and herbaceous plant‐mediated CH₄ emissions from hollows and hummocks also were measured, thus enabling an estimate of contributions from each pathway to total ecosystem flux. Stem CH₄ emissions varied significantly between the two tree species, with Alnus glutinosa displaying minimal seasonal variations, while substantial seasonal variations were observed in Betula pubescens. Trees from each species emitted similar quantities of CH₄ from their stems regardless of whether they were situated in hollows or hummocks. Soil temperature and pore‐water CH₄ concentrations best explained annual variability in stem emissions, while wood‐specific density and pore‐water CH₄ concentrations best accounted for between‐species variations in stem CH₄ emission. Our study demonstrates that tree‐mediated CH₄ emissions contribute up to 27% of seasonal ecosystem CH₄ flux in temperate forested wetland, with the largest relative contributions occurring in spring and winter. Tree‐mediated CH₄ emissions currently are not included in trace gas budgets of forested wetland. Further work is required to quantify and integrate this transport pathway into CH₄ inventories and process‐based models.     

Soil nutrient budgets following projected corn stover harvest for biofuel production in the conterminous United States

Increasing demand for food and biofuel feedstocks may substantially affect soil nutrient budgets, especially in the United States where there is great potential for corn (Zea mays L) stover as a biofuel feedstock. This study was designed to evaluate impacts of projected stover harvest scenarios on budgets of soil nitrogen (N), phosphorus (P), and potassium (K) currently and in the future across the conterminous United States. The required and removed N, P, and K amounts under each scenario were estimated on the basis of both their average contents in grain and stover and from an empirical model. Our analyses indicate a small depletion of soil N (?4 ± 35 kg ha^?1) and K (?6 ± 36 kg ha^?1) and a moderate surplus of P (37 ± 21 kg ha^?1) currently on the national average, but with a noticeable variation from state to state. After harvesting both grain and projected stover, the deficits of soil N, P, and K were estimated at 114–127, 26–27, and 36–53 kg ha^?1 yr^?1, respectively, in 2006–2010; 131–173, 29–32, and 41–96 kg ha^?1 yr^?1, respectively, in 2020; and 161–207, 35–39, and 51–111 kg ha^?1 yr^?1, respectively, in 2050. This study indicates that the harvestable stover amount derived from the minimum stover requirement for maintaining soil organic carbon level scenarios under current fertilization rates can be sustainable for soil nutrient supply and corn production at present, but the deficit of P and K at the national scale would become larger in the future.     

Effects of the addition of different nitrogen sources in the tequila fermentation process at high sugar concentration

AIMS: To study the effect of the addition of different nitrogen sources at high sugar concentration in the tequila fermentation process. METHODS AND RESULTS: Fermentations were performed at high sugar concentration (170 g l(-1)) using Agave tequilana Weber blue variety with and without added nitrogen from different sources (ammonium sulfate; glutamic acid; a mixture of ammonium sulfate and amino acids) during the exponential phase of growth. All the additions increased the fermentation rate and alcohol efficiency. The level of synthesis of volatile compounds depended on the source added. The concentration of amyl alcohols and isobutanol were decreased while propanol and acetaldehyde concentration increased. CONCLUSIONS: The most efficient nitrogen sources for fermentation rate were ammonium sulfate and the mixture of ammonium sulfate and amino acids. The level of volatile compounds produced depended upon types of nitrogen. The synthesis of some volatile compounds increased while others decreased with nitrogen addition. SIGNIFICANCE AND IMPACT OF THE STUDY: The addition of nitrogen could be a strategy for improving the fermentation rate and efficiency in the tequila fermentation process at high sugar Agave tequilana concentration. Furthermore, the sensory quality of the final product may change because the synthesis of the volatile compounds is modified.     

氮高效水稻种质资源筛选及相关特性分析

在不施氮和施氮量180 kg/hm22个水平下,对45份水稻种质的氮吸收与利用等相关性状进行分析,并根据参试品种在2个施氮水平下的产量差异将其分为双高效型、高氮高效型、低氮高效型和双低效型等4种类型,重点研究不同氮效率水稻产量、吸氮量以及氮素利用率等性状的相关性及差异分析。结果表明,单株子粒重、单株秸秆重、植株吸氮量和氮生理利用率变幅分别为4.50~29.65 g、6.35~18.70 g、4.80~21.28 g/m2和19.88~62.05 g/g。无论是在低氮还是高氮水平下,水稻产量与有效穗数、穗粒数、结实率、生物量、子粒吸氮量、吸氮量和氮生理利用率均呈显著或极显著正相关,与子粒和秸秆氮浓度呈显著负相关。4种氮效率类型品种间的产量与生物量、吸氮量和氮生理利用率差异均达到极显著水平,双高效型和高氮高效型水稻受氮肥的影响最大,低氮高效型水稻受氮肥的影响最小。研究认为,青马早和陆财早不论是在低氮还是高氮水平下均表现出氮高效利用特性,为典型氮高效型;广陆矮4号在低氮水平下表现出氮高效利用特性,适于低氮条件种植,为典型耐低氮型;早89-01和早籼152在高氮水平下表现出氮高效利用特性,适于高氮条件种植。     

干旱过程中荒漠生物土壤结皮-土壤系统的硝化作用对温度和湿度的响应——以沙坡头地区为例

以腾格里沙漠东南缘天然植被区由藻类、藓类结皮所覆盖的土壤和流沙为研究对象,采用原状土室内培养法,在15和20 ℃两个温度、10%和25%两个湿度下连续培养20 d,分别在培养后的第1、2、5、8、12、20天连续测定土壤样品中的NO₃^--N含量,探讨不同温度和湿度条件下荒漠土壤的净硝化速率在干旱过程中的变化规律.结果表明： 藓类结皮的NO₃^--N含量（2.29 mg·kg^-1）高于藻类结皮（1.84 mg·kg^-1）和流沙（1.59 mg·kg^-1）,3种类型的土壤净硝化速率介于-3.47～2.97 mg·kg^-1·d^-1之间.10%湿度条件下,藻类和藓类结皮在25 ℃下的净硝化速率比15 ℃分别减少75.1%和0.7%;25%湿度条件下,分别减少99.1%和21.3%;15 ℃、10%湿度条件下藻类和藓类结皮的净硝化速率比25 ℃、25%湿度条件下增加193.4%和107.3%.表明在全球变暖背景下,无论土壤湿度增加或减少,干旱过程中的荒漠生物土壤结皮-土壤系统净硝化速率在一定程度上都会受到抑制.     

Effects of starch-rich or lipid-supplemented diets that induce milk fat depression on rumen biohydrogenation of fatty acids and methanogenesis in lactating dairy cows

Optimizing milk production efficiency implies diets allowing low methane (CH₄) emissions and high dairy performance. We hypothesize that nature of energy (starch v. lipids) and lipid supplement types (monounsaturated fatty acid (MUFA) v. polyunsaturated fatty acid (PUFA) mitigate CH₄ emissions and can induce low milk fat content via different pathways. The main objective of this experiment was to study the effects of starch-rich or lipid-supplemented diets that induce milk fat depression (MFD) on rumen biohydrogenation (RBH) of unsaturated fatty acids (FA) and enteric CH₄ emissions in dairy cows. Four multiparous lactating Holstein cows (days in milk=61±11 days) were used in a 4×4 Latin square design with four periods of 28 days. Four dietary treatments, three of which are likely to induce MFD, were based (dry matter basis) on 56% maize silage, 4% hay and 40% concentrates rich in: (1) saturated fatty acid (SFA) from Ca salts of palm oil (PALM); (2) starch from maize grain and wheat (MFD-Starch); (3) MUFA (cis-9 C18:1) from extruded rapeseeds (MFD-RS); and (4) PUFA (C18:2n-6) from extruded sunflower seeds (MFD-SF). Intake and milk production were measured daily. Milk composition and FA profile, CH₄ emissions and total-tract digestibility were measured simultaneously when animals were in open-circuit respiration chambers. Fermentation parameters were analysed from rumen fluid samples taken before feeding. Dry matter intake, milk production, fat and protein contents, and CH₄ emissions were similar among the four diets. We observed a higher milk SFA concentration with PALM and MFD-Starch, and lower milk MUFA and trans-10 C18:1 concentrations in comparison to MFD-RS and MFD-SF diets, while trans-11 C18:1 remained unchanged among diets. Milk total trans FA concentration was greater for MFD-SF than for PALM and MFD-Starch, with the value for MFD-RS being intermediate. Milk C18:3n-3 content was higher for MFD-RS than MFD-SF. The MFD seems more severe with MFD-SF and MFD-RS than PALM and MFD-Starch diets, because of a decrease in milk SFA concentration and a stronger shift from trans-11 C18:1 to trans-10 C18:1 in milk. The MFD-SF diet increased milk trans FA (+60%), trans-10 C18:1 (+31%), trans-10,cis-12 CLA (+27%) and PUFA (+36%) concentrations more than MFD-RS, which explains the numerically lowest milk fat yield and indicates that RBH pathways of PUFA differ between these two diets. Maize silage-based diets rich in starch or different unsaturated FA induced MFD with changes in milk FA profiles, but did not modify CH₄ emissions.     

Plausible biochemical mechanisms of chemotherapy-induced cognitive impairment (“chemobrain”), a condition that significantly impairs the quality of life of many cancer survivors

Increasing numbers of cancer patients survive and live longer than five years after therapy, but very often side effects of cancer treatment arise at same time. One of the side effects, chemotherapy-induced cognitive impairment (CICI), also called “chemobrain” or “chemofog” by patients, brings enormous challenges to cancer survivors following successful chemotherapeutic treatment. Decreased abilities of learning, memory, attention, executive function and processing speed in cancer survivors with CICI, are some of the challenges that greatly impair survivors' quality of life. The molecular mechanisms of CICI involve very complicated processes, which have been the subject of investigation over the past decades. Many mechanistic candidates have been studied including disruption of the blood-brain barrier (BBB), DNA damage, telomere shortening, oxidative stress and associated inflammatory response, gene polymorphism of neural repair, altered neurotransmission, and hormone changes. Oxidative stress is considered as a vital mechanism, since over 50% of FDA-approved anti-cancer drugs can generate reactive oxygen species (ROS) or reactive nitrogen species (RNS), which lead to neuronal death. In this review paper, we discuss these important candidate mechanisms, in particular oxidative stress and the cytokine, TNF-alpha and their potential roles in CICI.     

Effects of sodium on mineral nutrition in rose plants

The effects of sodium (Na⁺) ion concentration on shoot elongation, uptake of ammonium (NH₄⁺) and nitrate (NO₃^?) and the activities of nitrate reductase (NR) and glutamine synthetase (GS) were studied in rose plants (Rosa hybrida cv. “Lambada”). The results showed that shoot elongation was negatively correlated with sodium concentration, although no external symptoms of toxicity were observed. Nitrate uptake decreased at high sodium levels, specifically at 30 meq litre4 of sodium. As flower development was normal under high saline conditions, this could suggest that nitrogen was being mobilised from shoot and leaf reserves. Ammonium uptake was not affected by any of the salt treatments applied probably because it diffuses through the cell membrane at low concentrations. Nitrate reductase activity was reduced by 50% at 30 meq litre 1 compared with control treatment, probably due to a decrease in the free nitrate related to nitrate uptake pattern. None of the salt treatments used affected total leaf GS activity (both chloroplastic and cytosolic isoforms) or leaf NPK mineral contents. Nitrate reductase activity in leaves increased at 10 meq litre^?1 of sodium and GS activity in roots (cytosolic isoform only) followed the same pattern as NR. It is suggested that the activation of both enzymes at low salt level could be attributed to the beneficial effect of increased sulphur in the nutrient solutions.