首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
2.
3.
《Autophagy》2013,9(4):549-551
When an autophagosome or an amphisome fuse with a lysosome, the resulting compartment is referred to as an autolysosome. Some people writing papers on the topic of autophagy use the terms “autolysosome” and “autophagolysosome” interchangeably. We contend that these words should be used to denote 2 different compartments, and that it is worthwhile maintaining this distinction—the autophagolysosome has a particular origin in the process of xenophagy that makes it distinct from an autolysosome.  相似文献   

4.
When an autophagosome or an amphisome fuse with a lysosome, the resulting compartment is referred to as an autolysosome. Some people writing papers on the topic of autophagy use the terms “autolysosome” and “autophagolysosome” interchangeably. We contend that these words should be used to denote 2 different compartments, and that it is worthwhile maintaining this distinction—the autophagolysosome has a particular origin in the process of xenophagy that makes it distinct from an autolysosome.  相似文献   

5.
Beyond the energy requirement of maintenance, the assimilated energy, occurring in bioproducts, is linearly proportional to the intake of metabolizable energy in non‐underfed conditions. In contrast, resting metabolic rate is differing between individuals within a population of an animal species. As adaptability to changed environmental conditions may play a role, young bulls were exposed to thermoneutral (18°C) and low (4°C) ambient temperatures and were fed at two feeding levels (1.0 and 1.6 times energy requirement in maintenance) to produce metabolic rate differences, using the same animals, metabolic rate was altered by reducing the sympathetic outflow in each case. Expression of sulfonylurea receptors in circulating mononuclear leukocytes and cells from skeletal muscle (m. semitendinosus) was studied by flow cytom‐etry. Changes of metabolic rate at rest corresponded to the portion of cells with sulfonylurea receptors expression. The data from reducing the sympathetic outflow and those from sulfonylurea receptors expression are useful to explain metabolic rate differences among individuals of an animal population.  相似文献   

6.
Many health effects can be attributed to the Mediterranean herb oregano (Origanum vulgare L.) and several studies demonstrated the improving effect on performance, changes in blood count, antibacterial, antifungal and immunmodulating abilities. The majority of these investigations were carried out with processed essential oil, while whole plant material was only used in a few studies. Thus, the aim of the present experiment was to test the effect of increasing proportions of dried oregano in piglet feed on health and performance, with a special focus on immune modulation. A total of 80 male castrated weaned piglets (body weight [BW] 7.9 kg ±1.0 kg) were used in a feeding experiment lasting 5 weeks. They were assigned to 4 experimental groups: a control diet, and three diets with an oregano supplementation at 2 g, 4 g and 8 g per kg feed, respectively, corresponding to 23.5 mg, 46.9 mg and 93.9 mg carvacrol/kg DM. After 3 weeks, half of each group was challenged with 5 µg lipopolysaccharides (LPS) per kg BW. Blood samples were collected 2 h after LPS stimulation and analysed for T-cell phenotypes, granulocyte activity, clinical-chemistry as well as white and red blood count. The results indicate no effects of oregano on performance. In contrast, oregano altered the lymphocyte proportion and the ratio of CD4+ and CD8+ T-cells as well as the triglyceride concentration in the serum of non-stimulated and in LPS-stimulated piglets. In conclusion, whole plant supplementation of oregano to piglet feed altered immune-related parameters, but did not modulate the acute inflammatory response induced by LPS stimulation.  相似文献   

7.
The objective of the present study was to investigate physiological effects of a marginal copper and iron supply on pigs. Therefore an experiment was conducted with 4 × 12 growing pigs of the crossbreed Pietrain × Deutsche Landrasse. The animals were fed for a period of 119 days with a diet poor of copper (1.5 mg Cu/kg diet) and/or poor of iron (35 mg Fe/kg diet). Control animals were supplied adequately with copper (4.8 mg Cu/kg diet) and iron (85 mg Fe/kg diet). The diet was given according to weight. After reaching an average weight of 102.6 ± 3.5 kg the animals were slaughtered. Due to the activity of the coerulplasmin and katalase enzyme and the haematological parameters, the supply of copper and iron could be classified as marginal. There was no interaction between copper deficiency and iron metabolism. The protein metabolism was unchanged. Low copper intake reduced the copper concentrations in serum, liver, muscle and backfat, and low iron intake reduced the iron concentration in serum, liver and muscle. Marginal copper and iron supply had no relevant effect on either food intake and growth performance or carcass characteristics and meat quality.  相似文献   

8.
Barley, probably the oldest cultivated cereal, is widely grown in cooler areas of the world. The annual world production of nearly two and a half billion bushels exceeds that of rye but is less than that of rice, wheat, corn and oats, respectively. Most of the annual 300 million dollar crop of the U.S. is fed to livestock, but about one- third is manufactured into malt.  相似文献   

9.
10.
Liu YX 《生理科学进展》2005,36(2):97-101
刘以训教授是我国著名的生物学家,中国科学院院士。他致力于生殖生物学研究,在排卵、黄体萎缩、精子发生和胚胎植入等系列研究上,成绩卓著,享有国际声誉。读罢此文,钦敬之情油然而生。  相似文献   

11.
Photosynthetic capacity is known to vary considerably among species. Its physiological cause and ecological significance have been one of the most fundamental questions in plant ecophysiology. We studied the contents of Rubisco (a key enzyme of photosynthesis) and cell walls in leaves of 26 species with a large variation in photosynthetic rates. We focused on photosynthetic nitrogen-use efficiency (PNUE, photosynthetic rate per nitrogen), which can be expressed as the product of Rubisco-use efficiency (RBUE, photosynthetic rate per Rubisco) and Rubisco nitrogen fraction (RNF, Rubisco nitrogen per total leaf nitrogen). RBUE accounted for 70% of the interspecific variation in PNUE. The variation in RBUE was ascribed partly to stomatal conductance, and other factors such as mesophyll conductance and Rubisco kinetics might also be involved. RNF was also significantly related to PNUE but the correlation was relatively weak. Cell wall nitrogen fraction (WNF, cell wall nitrogen per total leaf nitrogen) increased with increasing leaf mass per area, but there was no correlation between RNF and WNF. These results suggest that nitrogen allocation to cell walls does not explain the variation in PNUE. The difference in PNUE was not caused by a sole factor that was markedly different among species but by several factors each of which was slightly disadvantageous in low PNUE species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

12.
Photosynthetic nitrogen use efficiency (PNUE, photosynthetic capacity per unit leaf nitrogen) is one of the most important factors for the interspecific variation in photosynthetic capacity. PNUE was analysed in two evergreen and two deciduous species of the genus Quercus. PNUE was lower in evergreen than in deciduous species, which was primarily ascribed to a smaller fraction of nitrogen allocated to the photosynthetic apparatus in evergreen species. Leaf nitrogen was further analysed into proteins in the water‐soluble, the detergent‐soluble, and the detergent‐insoluble fractions. It was assumed that the detergent‐insoluble protein represented the cell wall proteins. The fraction of nitrogen allocated to the detergent‐insoluble protein was greater in evergreen than in deciduous leaves. Thus the smaller allocation of nitrogen to the photosynthetic apparatus in evergreen species was associated with the greater allocation to cell walls. Across species, the fraction of nitrogen in detergent‐insoluble proteins was positively correlated with leaf mass per area, whereas that in the photosynthetic proteins was negatively correlated. There may be a trade‐off in nitrogen partitioning between components pertaining to productivity (photosynthetic proteins) and those pertaining to persistence (structural proteins). This trade‐off may result in the convergence of leaf traits, where species with a longer leaf life‐span have a greater leaf mass per area, lower photosynthetic capacity, and lower PNUE regardless of life form, phyllogeny, and biome.  相似文献   

13.
Li Z  Zhang S  Hu H  Li D 《Journal of plant research》2008,121(6):559-569
Photosynthesis, leaf structure, nitrogen content and nitrogen allocation in photosynthetic functions of Cypripedium flavum were studied in a naturally varying light regime. Light-saturated leaf net photosynthetic rate (A (max)) was strongly correlated with leaf dry mass per area (LMA), mesophyll conductance (g (m)) and area-based leaf nitrogen content (N(area)), with all variables increasing with increasing irradiance. Such coordinate variation of all these parameters illustrates the plastic response of leaf structure to high light (HL). Leaf N(area) was greater under HL than in low light (LL). The fractions of leaf nitrogen partitioning in carboxylation (P (R)) and bioenergetics (P (B)) were positively related to LMA. In contrast, P (R) and P (B) decreased with increasing mass-based leaf nitrogen content (N(mass)). However, no correlation was found between leaf nitrogen investment in light harvesting (P (L)) and either LMA or N(mass). Like maximum rate of carboxylation (V (cmax)) and electron transport (J (max)), the J (max)/V (cmax) ratio, which was strongly correlated to LMA, also increased significantly with irradiance. Under HL, leaf maximum photosynthetic nitrogen efficiency (ANUE) and intrinsic water use efficiency (WUE) were greater than in LL conditions, despite a small difference in WUE. This suggests that a functional balance in the photosynthetic machinery favors leaf photosynthetic plasticity of C. flavum in response to different light conditions. Given an ample soil nitrogen supply, C. flavum may offset its susceptibility to HL by efficient nitrogen use and higher stomatal and mesophyll conductance against photoinhibition so as to keep leaf photosynthesis positive.  相似文献   

14.
The relative importance that biomechanical and biochemical leaf traits have on photosynthetic capacity would depend on a complex interaction of internal architecture and physiological differences. Changes in photosynthetic capacity on a leaf area basis and anatomical properties during leaf development were studied in a deciduous tree, Prunus persica, and an evergreen shrub, Olea europaea. Photosynthetic capacity increased as leaves approached full expansion. Internal CO2 transfer conductance (g i) correlated with photosynthetic capacity, although, differences between species were only partially explained through structural and anatomical traits of leaves. Expanding leaves preserved a close functional balance in the allocation of resources of photosynthetic component processes. Stomata developed more rapidly in olive than in peach. Mesophyll thickness doubled from initial through final stages of development when it was twice as thick in olive as in peach. The surface area of mesophyll cells exposed to intercellular air spaces per unit leaf area tended to decrease with increasing leaf expansion, whereas, the fraction of mesophyll volume occupied by the intercellular air spaces increased strongly. In the sclerophyllous olive, structural protection of mesophyll cells had priority over efficiency of photochemical mechanisms with respect to the broad-leaved peach. The photosynthetic capacity of these woody plants during leaf development relied greatly on mesophyll properties, more than on leaf mass per area ratio (LMA) or nitrogen (N) allocation. Age-dependent changes in diffusion conductance and photosynthetic capacity affected photosynthetic relationships of peach versus olive foliage, evergreen leaves maturing functionally and structurally a bit earlier than deciduous leaves in the course of adaptation for xeromorphy.  相似文献   

15.
南亚热带人工林16种木本植物重要叶特征参数的相互关系   总被引:1,自引:0,他引:1  
以南亚热带退化丘陵生态恢复进程中16种3 a生木本植物为对象,研究叶片重要特征参数间的相互关系.结果表明,植物叶片的N、P含量平均值低于全国平均值,N:P平均值则高于全国的平均水平;成熟叶片的N和P含量之间有极显著正相关关系(P<0.00001),N:P与N有弱的正相关关系(r=0.322,P<0.01),与P显著负相关,推断植物叶N:P主要由P决定(r=0/639,P<0.00001).含N量高的植物具有高的最大净光合速率(Pmax)、光合N利用效率(PNOE)和低的比叶重(LMA),反之,含N量低植物具有低的Pmax、PNUE和高的LMA;Pmax与PNUE极显著正相关,LMA与PNUE极显著负相关.  相似文献   

16.
白坤栋  蒋得斌  万贤崇 《生态学报》2013,33(16):4930-4938
分析广西猫儿山不同海拔常绿和落叶树种的光合作用-氮关系,探讨光合氮利用效率(PNUE)是否受到叶片习性和海拔的影响。落叶树种的PNUE都显著高于常绿树种,这与前者有较低的比叶重(LMA)和较高的单位叶重光合速率(Amass)、氮含量和气孔导度(gs)有密切关系。高海拔树种的PNUE显著低于中低海拔树种的PNUE,这与前者较高的LMA和较低的Amass和gs相关。PNUE和相关的叶片特征的主成分分析表明常绿-落叶树种和低海拔-中海拔-高海拔树种的分布是一个自然过渡的过程。此外,PNUE与土壤碳:氮比没有显著相关性,但与年均温正相关,这表明温度气候是调节PNUE沿海拔变化的主要环境因素。因此,这种叶片习性和温度气候调节的PNUE变化可能是调节猫儿山常绿树种沿海拔形成双峰分布的一种机制。  相似文献   

17.
黄土高原油松和刺槐叶片光合生理适应性比较   总被引:4,自引:0,他引:4  
以黄土高原地区由南向北分布的杨凌、永寿、富县、安塞、米脂、神木等县为研究地点,研究不同地区油松和刺槐的光合特性与叶结构性状间的关系.结果表明,不同地区油松针叶和刺槐叶片的净光合速率(Pn)、光合氮利用效率(PNUE)、水分利用效率(WUE)、比叶质量(LMA)、氮含量(Nmass)和叶绿素相对含量(Chl)差异均达极显著水平(P<0.001),说明不同地区油松和刺槐的光合能力和叶结构性状参数差异很大.由南向北,油松的Pn、WUE和PNUE呈略微增加趋势,而刺槐则呈显著降低趋势,表明油松在干旱生境下仍能维持较高的光合能力,而刺槐光合能力明显受到抑制;油松和刺槐的LMA均呈略微上升趋势,而Nmass和Chl均呈略微下降趋势,且刺槐的变化幅度高于油松,说明油松从生理代谢和叶结构性状上对干旱环境的适应能力均强于刺槐.相关分析表明,不同地区油松和刺槐的LMA与Nmass整体上呈极显著负相关;Pn、PNUE与LMA、Nmass相关不显著,与Chl呈极显著正相关;WUE与LMA呈显著负相关(P<0.05),与Nmass呈显著正相关.  相似文献   

18.
There is a close phylogenetic relationship between Paphiopedilum and Cypripedium, but these two genera diverge considerably in terms of their leaf traits. To understand the evolution and the ecophysiological significance of leaf traits, we investigated the leaf traits of three Paphiopedilum species and three Cypripedium species in southwestern China. Cypripedium tibeticum and C. flavum showed a significantly higher light-saturated photosynthetic rate (P(max) ), stomatal conductance (g(s) ), photosynthetic nitrogen utilization efficiency (PNUE) and specific leaf area (SLA), but lower ratio of leaf carbon to nitrogen content (C/N) and leaf construction cost (CC) than Paphiopedilum. These leaf traits of Cypripedium suggest its high resource use efficiency and high growth rate reflecting adaptation to a short growing period and abundant soil nutrients and water in alpine habitats. Conversely, the low P(max) , g(s) , PNUE, SLA and the ratio of chlorophyll a to chlorophyll b (Chl a/b), but high leaf nitrogen investment in light-harvesting component (P(L) ), CC and C/N in Paphiopedilum indicate its adaptation to a low light, nutrient-poor and limited soil water habitats in karst areas. As a sympatric species of Paphiopedilum, although C. lentiginosum retained the phylogenetic leaf traits of Cypripedium, such as high mass-based light-saturated photosynthetic rate (P(max-M) ), g(s) and PNUE, it had some similar leaf traits to those of Paphiopedilum, such as low mesophyll conductance (g(m) ) and Chl a/b, and high P(L) , which reflected an adaptation to the same habitat. Our results show that the evolution of the leaf traits of Paphiopedilum and Cypripedium are shaped by both phylogeny and environment.  相似文献   

19.
Plants allocate nutrients to specific leaf cell types; eudicots are thought to predominantly allocate phosphorus (P) to epidermal/bundle sheath cells. However, three Proteaceae species have been shown to preferentially allocate P to mesophyll cells instead. These Proteaceae species are highly adapted to P‐impoverished habitats, with exceptionally high photosynthetic P‐use efficiencies (PPUE). We hypothesized that preferential allocation of P to photosynthetic mesophyll cells is an important trait in species adapted to extremely P‐impoverished habitats, contributing to their high PPUE. We used elemental X‐ray mapping to determine leaf cell‐specific nutrient concentrations for 12 Proteaceae species, from habitats of strongly contrasting soil P concentrations, in Australia, Brazil, and Chile. We found that only species from extremely P‐impoverished habitats preferentially allocated P to photosynthetic mesophyll cells, suggesting it has evolved as an adaptation to their extremely P‐impoverished habitat and that it is not a family‐wide trait. Our results highlight the possible role of soil P in driving the evolution of ecologically relevant nutrient allocation patterns and that these patterns cannot be generalized across families. Furthermore, preferential allocation of P to photosynthetic cells may provide new and exciting strategies to improve PPUE in crop species.  相似文献   

20.
The ecophysiological traits of acacia and eucalypt are important in assessing their suitability for afforestation. We measured the gas-exchange rate, the leaf dry mass per area (LMA) and the leaf nitrogen content of two acacia and four eucalypt species. Relative to the eucalypts, the acacias had lower leaf net photosynthetic rate (P N), lower photosynthetic nitrogen-use efficiency (PNUE), higher water-use efficiency (WUE), higher LMA and higher leaf nitrogen per unit area (N area). No clear differences were observed within or between genera in the maximum rate of carboxylation (V cmax) or the maximum rate of electron transport (J max), although these parameters tended to be higher in eucalypts. PNUE and LMA were negatively correlated. We conclude that acacias with higher LMA do not allocate nitrogen efficiently to photosynthetic system, explaining why their P N and PNUE were lower than in eucalypts.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号