共查询到18条相似文献，搜索用时 694 毫秒
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采用15N-甘氨酸单剂量终产物法研究了妊娠和非妊娠母猪在不同阶段整体蛋白质代谢的周转速率以及氨基酸利用效率的差异。结果表明:刚配种时,妊娠母猪与非妊娠母猪蛋白质代谢参数差异不显著(P>0.05);妊娠30d时,妊娠母猪蛋白质合成速率,降解速率、周转速率显著低于非妊娠母猪(P<0.05),但沉积速率提高了25%(P<0.05);妊娠后期,妊娠母猪氨基酸代谢库氮流量、周转速率以及蛋白质合成速率和降解速率显著(P<0.01)提高,蛋白质的沉积速率增加了71.1%(P<0.01)。 相似文献
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研究了1 4 C 葡萄糖在 1 3种土壤中的周转。周转可以分为 3个阶段 :0～ 3d ,周转速率为 1 3× 1 0 - 1 ～ 2 5× 1 0 - 1 /d ,半周转期为 3～ 5d;3～ 2 8d,周转速率为 0 7×1 0 - 2 ～ 1 2× 1 0 - 2 /d ,半周转期为 5 8～ 97d ;2 8～ 2 94d,周转速率为 0 5× 1 0 - 3× 1 4×1 0 - 3/d ,半周转期为 491～ 1 5 0 4d。相关性分析表明 ,1 4 C 葡萄糖周转速率与土壤代谢熵 (qCO2 )呈显著性正相关 ;3～ 2 8d周转速率与土壤理化性质和生物学性质都无显著的相关性 ;2 8～ 2 94d周转速率与土壤总有机碳、全氮、CEC呈显著或极显著负相关 ,与土壤砂粒含量呈显著正相关。这一阶段1 4 C 葡萄糖的周转与土壤性质密切相关。 相似文献
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支链氨基酸(branch chain amino acids,BCAA)作为一种重要的信号调节分子,参与动物机体蛋白质周转等重要生物学过程。此过程涉及两条进化上高度保守的感知氨基酸水平的信号通路,对氨基酸丰度敏感的哺乳动物雷帕霉素靶蛋白(mammals target of rapamycin,mTOR)和感知一种或多种未负载氨基酸的t RNA而活化的一般氨基酸调控阻遏蛋白2(general amino acid control non-derepressible 2,GCN2)。本文主要探讨BCAA对mTOR和GCN2通路的影响,旨在阐述BCAA调控蛋白质合成和降解的机制,为研究调控哺乳动物蛋白质周转的机理提供借鉴,为BCAA在饲料添加剂应用方面提供理论依据。 相似文献
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简述了目前国内外常用的3种测定土壤微生物生物量C周转分析方法及其影响因素、改进的土壤微生物生物量C周转动力学测定方法及其应用前景,并分析了国内外不同生态环境、土壤质地和耕作管理制度等的土壤微生物生物量C周转的研究结果。 相似文献
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土壤微生物生物量碳周转对土壤有机质和养分循环起着决定作用。本研究建立了土壤微生物生物量碳周转时间的测定方法。培养条件下 (2 5℃、10 0 %湿度 ) ,加入14 C标记葡萄糖标记土壤微生物生物量碳 ,在 10 0d培养期内 ,每隔 2 0d测定一次14 C标记微生物生物量碳 (14 C BC) ,采用一级热力学方程拟合测定期内 (2 0～ 10 0d) 14 C BC 的周转速率常数 (k) ,由此计算土壤微生物生物量碳的表观周转时间。测定的 5个土壤在培养条件下微生物生物量碳的周转时间为 93～ 4 0 0d ,根据培养温度和实际田间年平均温度推算得到田间条件下土壤微生物生物量碳的周转时间为 1 0～ 4 1a。其主要影响因子为土壤质地 ,土壤利用方式的影响较小。土壤微生物生物量碳的周转时间能较好地反映土壤微生物生物量的周转状况及其与土壤有机质的周转和积累的关系。 相似文献
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土壤有机碳周转SCNC模型的研究与开发 总被引：4，自引：0，他引：4
本文介绍土壤有机碳周转SCNC模型的研究与开发，阐述了土壤有机碳周转的基本理论，模型设计与模型结构。介绍了模型的功能与特点。 相似文献
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不同秸秆还田模式对土壤有机碳周转的影响 总被引：2，自引：0，他引：2
《土壤与作物》2019,(1)
秸秆还田可以有效增加土壤有机质含量,改善土壤肥力,同时影响土壤微生物的活性,促进土壤碳氮循环,有利于农业生产可持续发展。本文主要从秸秆还田后的碳周转特征及研究方法,以及秸秆还田的作物类型、还田秸秆部位、秸秆还田量和还田方式对土壤有机碳的影响进行综述,旨在全面了解还田后秸秆的分解转化以及对土壤碳周转的影响。指出未来研究中应该更加关注如何高效地进行秸秆还田,结合秸秆自身条件以及土壤环境,选择一种适合作物生长、可以最大化提高土壤肥力的还田方式。 相似文献
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土壤孔隙结构与土壤微环境和有机碳周转关系的研究进展 总被引：7，自引：1，他引：6
土壤结构是土壤功能的基础,不仅影响土壤养分的供应、水分的保持及渗透、气体的交换等过程,还为土壤微生物提供了物理生境,并调控土壤有机碳的周转这一关键过程。土壤的孔隙特征能够直接、真实地反映土壤结构的好坏;用土壤的孔隙特征作为试验指标能更好地反映土壤结构对这些过程的调节作用。在此基础上,将高度异质性的土壤孔隙结构同土壤微环境的变化和土壤有机碳的周转过程进行定量分析,对深入了解土壤结构在土壤生态系统中的功能至关重要。因此,着重从土壤孔隙结构对土壤微环境的影响及其与有机碳的关系两方面展开,剖析土壤孔隙结构调控作用下的土壤微环境响应过程,阐述土壤孔隙结构对土壤有机碳周转产生的直接、间接影响,强调土壤孔隙结构在调节土壤有机碳周转进程中的重要作用,并对土壤孔隙结构在调节土壤有机碳周转、植物残体分解及其与微生物协调作用机制等方面研究提出展望。 相似文献
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不同土壤耕作模式对冬小麦籽粒品质的影响 总被引：4，自引：1，他引：4
冬小麦籽粒的品质受土壤环境影响。为了研究不同土壤耕作模式对冬小麦籽粒品质的影响，采用了5种土壤耕作模式(常规耕作秸秆不还田、常规耕作秸秆还田、旋耕秸秆还田、缺口圆盘耙耕秸秆还田、免耕秸秆覆盖)在山东龙口进行了3年田间试验，测定了冬小麦籽粒蛋白质品质、面团流变学特性和淀粉糊化特性。结果表明：少耕模式特别是旋还模式有利于改善籽粒蛋白质质量、改善面粉的加工品质，免覆模式对改变面条蒸煮品质有利。土壤耕作可改变土壤环境，但耕作方式对冬小麦品质的长期影响仍有待于进一步研究。 相似文献
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In the last decades many aspects of nitrogen turnover have been studied by 15N methods. In this article contemporary 15N tracer as well as natural 15N abundance methods for the study of animal manure turnover are briefly reviewed. The nitrogen dynamics after application of farmyard manure and slurry are elucidated. Here, emphasis was put on results from 15N stable isotope work in the fields of nitrogen immobilization, nitrogenous trace gas emissions, turnover of organic nitrogen fractions, and finally plant uptake. Added nitrogen interactions, which must be considered when interpreting 15N studies, are discussed. Finally promising research fields for the use of stable isotopes are outlined. 相似文献
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A radiocarbon approach was used to investigate the roles of temperature and soil fauna activity in the turnover of ‘old’ non-labile carbon in a peatland ecosystem. We investigated the impacts of enchytraeids on carbon turnover in two different soil layers, with different incorporation of the ‘bomb’ peak, when incubated at two different temperatures. Results showed that, in agreement with previous studies, warmer temperatures promoted reproduction rates of enchytraeids, with the top layer supporting higher animal densities and biomass. With independence of the animal treatment, soil respiration in the top 5 cm was four times higher than in the deeper layer suggesting that decomposition was greater in the upper layer, with the response being greater at the highest temperature treatment. Furthermore, independent of temperature, the presence of enchytraeids in the top layer significantly enhanced the release of non-labile C as DOC. Similarly, at the bottom layer, ‘older’ C sources were mobilised in response to warming and a greater amount of pre-bomb carbon was released into the soil solution at 20 °C when the worms were present. A strong positive link between the ages of the C assimilated by the animals and released through mineralization suggests an important role of soil biology in the mobilisation of the older C pools in soils and should be taken into account in developing global C models to predict the response of soil C dynamics to climate change. 相似文献
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Chuang CY Shi YC You HP Lo YH Pan TM 《Journal of agricultural and food chemistry》2011,59(7):3027-3034
γ-Aminobutyric acid (GABA) has several well-known physiological functions including antihypertension and antidepression. In this research, we focus on the antidepressant effects of oral administration of GABA-rich Monascus-fermented product in depression animal model (forced swimming test, FST) by Sprague-Dawley rats, and try to find its possible mechanism in the brain monoamine system. GABA and the Monascus-fermented product (MFP) significantly decreased the duration of immobility time in a short-term test. In a long-term test, the antidepressant-like effect of MFP was better than that of GABA at the same dosage (2.6 mg/kg), and the efficacy of MFP was similar to that of fluoxetine. Moreover, GABA might recover the level of monoamines norepinephrine, dopamine (DA), and 5-hydroxytryptamine (5-HT) in hippocampus and normalize the turnover ratio of 5-HT and DA in hippocampus and amygdala. In addition to the functions of GABA, the MFP has more potential in decreasing the turnover ratio of DA in the frontal cortex and striatum to improve depressive symptoms. 相似文献
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Archile-Contreras AC Cha MC Mandell IB Miller SP Purslow PP 《Journal of agricultural and food chemistry》2011,59(2):608-614
Vitamins influence collagen metabolism in animals grown for meat. This study investigated whether vitamins E and C regulate collagen turnover in muscle by the balance of effects on the synthesis of collagen and its degradation by secretion of matrix metalloproteinases (MMPs) by bovine intramuscular fibroblasts. Fibroblasts isolated from longissimus dorsi (LD) and semitendinosus (ST) muscle were treated with different concentrations of vitamins. Pro-MMP-2, MMP-2, and total soluble collagen (TSC) synthesis were determined. Vitamins E and C each preferentially increased (P < 0.05) MMP-2 in cells derived from LD relative to those derived from ST. Higher TSC values (P < 0.05) were found for ST cells than for LD cells. Both vitamins may increase collagen turnover exerted by intramuscular connective tissue fibroblasts. These results may have implications in vivo on animal production, as a high rate of collagen turnover may lead to increased collagen solubility in muscles, which can affect meat tenderness. 相似文献
16.
Rachel E. Brock 《Biological conservation》2004,118(5):633-640
Roads can have major impacts on animal distribution and movement patterns by destroying or creating habitat, and by acting as both barriers and corridors for movement. Using a combination of live trapping and spool and line tracking, we compare the relative abundance, mass, and demographic turnover of the endangered Stephens' kangaroo rat (Dipodomys stephensi) on dirt and gravel roads in comparison with adjacent grassland habitat. D. stephensi was more active on dirt roads, and less so on gravel roads, relative to adjacent grassland habitat. Dirt roads were used extensively, and animals tended to move greater distances along dirt roads than in surrounding grasslands. In contrast, gravel roads were used much less extensively than adjacent grasslands. Animals using dirt roads were significantly lighter in mass than those on gravel roads and in adjacent grassland, suggesting greater use by juvenile animals. Dirt roads also had lower rates of recapture and higher rates of new arrivals than did adjacent habitat. These findings suggest that dirt roads provide potentially important landscape linkages for D. stephensi, whereas that gravel roads may act as movement barriers. 相似文献
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集约化畜禽生产过程中产生的有害气体NH3对环境酸化、土壤及地表水的污染等问题在公众与科学界都引起了极大的关注，西欧等发达国家对畜禽舍内NH3的排放测定、减排技术及测量方法等方面进行了大量研究。该文对畜禽舍NH3的产生及其影响因素进行了分析，对目前国内外有关畜禽舍NH3的减排与控制技术进行了综述。 相似文献