森林生态系统中土壤有机质组分的固态13C核磁共振波谱表征

Forest management practices such as prescribed burning and thinning in forest ecosystems may alter the properties of soil organic matter (SOM).In this study,surface soils from field plots in the Bankhead National Forest,Alabama,USA,were used to investigate possible SOM transformations induced by thinning and burning.Elemental analysis and solid-state 13C cross polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectroscopy were used to characterize SOM fractions in whole soils,humic substances,and density fractions.Our data revealed that the changes in SOM fractions due to the repeated burning carried out in the forest ecosystem studied were involved mainly with alkyl C,O-alkyl C,and carbohydrate functional groups,implying that most prominent reactions that occurred involved dehydrogenation,de-oxygenation,and decarboxylation.In addition,burning and thinning might have also affected the distribution and composition of free and occluded particulate SOM fractions.The limited structural changes in SOM fractions suggested that low-intensity prescribed fire in the forest ecosystem studied will not create major structural changes in SOM fractions.     

Disturbed bovine mitochondrial lipid metabolism: a review

In mammals, excess energy is stored primarily as triglycerides, which are mobilized when energy demands arise and cannot be covered by feed intake. This review mainly focuses on the role of long chain fatty acids in disturbed energy metabolism of the bovine species. Long chain fatty acids regulate energy metabolism as ligands of peroxisome proliferator-activated receptors. Carnitine acts as a carrier of fatty acyl groups as long-chain acyl-CoA derivatives do not penetrate the mitochondrial inner membrane. There are two different types of disorders in lipid metabolism which can occur in cattle, namely the hypoglycaemic-hypoinsulinaemic and the hyperglycaemic-hyperinsulinaemic type with the latter not always associated with ketosis. There is general agreement that fatty acid β-oxidation capability is limited in the liver of (ketotic) cows. In accord, supplemental L-carnitine decreased liver lipid accumulation in periparturient Holstein cows. Of note, around parturition concurrent oxidation of fatty acids in skeletal muscle is highly activated. Also peroxisomal β-oxidation in liver of dairy cows may be part of the hepatic adaptations to a negative energy balance (NEB) to break down fatty acids. An elevated blood concentration of nonesterified fatty acids is one of the indicators of NEB in cattle among others like increased β-hydroxy butyrate concentration, and decreased concentrations of glucose, insulin, and insulin-like growth factor-I. Assuming that liver carnitine concentrations might limit hepatic fatty acid oxidation capacity in dairy cows, further study of the role of acyl-CoA dehydrogenases and/or riboflavin in bovine ketosis is warranted.     

不同品种紫花苜蓿酚酸类化感物质含量的研究

采用高效液相色谱法对10个品种紫花苜蓿地上部和根水浸提液中的绿原酸、香豆酸、羟基苯甲酸、咖啡酸和阿魏酸5种酚酸类化感物质的含量进行分析。研究表明,无论是地上部还是根水浸提液中,不同品种的紫花苜蓿酚酸类化感物质的含量存在差异,艾丽丝地上部和根水浸提液中绿原酸的含量分别为94.72和23.98μg/g,咖啡酸含量分别为30.49和6.33μg/g,与其他品种相比均较高;艾格地上部和根水浸提液阿魏酸含量分别为48.97和6.75μg/g,均明显高于其他品种。紫花苜蓿地上部和根水浸提液羟基苯甲酸含量分别与咖啡酸、绿原酸、阿魏酸含量呈极显著的正相关。紫花苜蓿地上部水浸提液中,香豆酸含量分别与咖啡酸和阿魏酸含量呈极显著的正相关,羟基苯甲酸与香豆酸呈显著正相关;根水浸提液中,咖啡酸含量分别与绿原酸和阿魏酸含量、绿原酸含量与阿魏酸含量呈显著正相关。另外,同一品种紫花苜蓿地上部与根水浸提液中同一种酚酸类含量存在差异。     

苎麻叶药材质量标准研究

描述了苎麻叶的显微特征和薄层色谱特征,并测得苎麻叶药材水分分、总灰分、酸不溶性灰分、醇溶性浸出物和绿原酸的平均含量为分别为7.47%、16.29%、1.71%、12.66%和0.05%。     

不同地理居群山桐子的果实含油率与脂肪酸含量

随着煤炭、石油等化石能源价格的不断上涨,加快可再生能源,尤其是生物质能源的发展,以推进能源替代,被认为是解决全球能源危机的最理想途径之一(唐红英,2008)。目前,世界各国,尤其是发达国家,都致力于开发高效、无污染的生物质能源利用技术,以保障能源安全,实现CO2减排,促进经济、社会的可持续发展(Holdren,1991)。根据专家预     

新疆伽师瓜籽油提取及脂肪酸成分分析

[目的]研究伽师瓜籽油微波提取工艺,对所得油脂成分进行分析,为新疆伽师瓜籽资源开发利用提供参考.[方法]用正交试验法优选微波提取工艺条件,采用气相色谱质谱联用技术分析伽师瓜籽油脂肪酸成分.[结果]优化后,微波辅助提取伽师瓜籽油得率为46.13;,其脂肪酸主要成分为棕榈酸、亚油酸、油酸和硬脂酸,其中不饱和脂肪酸含量为80.85;,亚油酸含量高达62.56;.[结论]与传统索氏提取工艺相比,微波提取伽师瓜籽油工艺效率更高;与常见食用油相比,伽师瓜籽油含更多不饱和脂肪酸,是一种极具开发潜力的药食两用保健植物资源.     

Demospongic acids revisited

The well-known fatty acids with a Δ5,9 unsaturation system were designated for a long period as demospongic acids, taking into account that they originally occurred in marine Demospongia sponges. However, such acids have also been observed in various marine sources with a large range of chain-lengths (C(16)-C(32)) and from some terrestrial plants with short acyl chains (C(18)-C(19)). Finally, the Δ5,9 fatty acids appear to be a particular type of non-methylene-interrupted fatty acids (NMA FAs). This article reviews the occurrence of these particular fatty acids in marine and terrestrial organisms and shows the biosynthetic connections between Δ5,9 fatty acids and other NMI FAs.     

Bacterial pathogens of rice in the Kingdom of Cambodia and description of a new pathogen causing a serious sheath rot disease

A study of rice diseases in Cambodia from 2005 to 2007 showed widespread occurrence of diseases caused by Acidovorax avenae subsp. avenae, Burkholderia gladioli, B. cepacia and Pantoea ananatis. This is the first report of these pathogens in Cambodia. Additionally, a pseudomonad causing a widespread disease similar to sheath brown rot (caused by Pseudomonas fuscovaginae) was isolated. The studied strains were pathogenic to rice cvs Sen Pidau and IR 66, producing similar, though slightly less severe, symptoms to those observed in the field. Based on comparative 16S rDNA gene sequence analysis, combined with cell wall fatty acid analysis and metabolic profiles, the isolated strains were allocated to the genus Pseudomonas. The novel species were differentiated from Pseudomonas fuscovaginae and P. putida by their inability to metabolize d ‐fructose, d ‐galactose, d ‐galactonic acid lactone, d ‐galacturonic acid, d ‐glucosaminic acid, d ‐glucuronic acid, p‐hydroxy phenylacetic acid, d ‐saccharic acid and urocanic acid. The major fatty acids were C_16:0, summed feature 3 (C_16:1ω7c and C_16:1ω6c) and summed feature 8 (C_18:1ω7c), representing 80% of the total. Partial 16S rRNA gene sequences (1460 bp) were identical, except for two nucleotide changes amongst the six strains. Alignment of the causal strains within type‐culture databases revealed similarities of 99·7% with Pseudomonas parafulva AJ 2129^T, 99·2% with P. fulva IAM 1592^T, 98·9% with P. plecoglossicidia FPC 951^T, and 98·1% with P. fuscovaginae MAFF 301177^T. On the basis of data from this polyphasic study, it is proposed that the unknown strains isolated from rice represent a novel species of the genus Pseudomonas.     

The Effects of Dietary Fatty Acid Pattern on Layer＇s Performance and Egg Quality

The feeding trial was conducted to determine the effects of flaxseed on layer＇s performance and egg quality, and the effects of the dietary ratio of ω-6 fatty acid to ω-3 fatty acid on fatty acid deposition in yolk using flaxseed as resource of ω-3 fatty acid and sunflower seed as resource of ω-6 fatty acid. 192 20-wk-old Newroman commercial hens were randomly divided into 4 treatment groups with 6 replicates containing 8 birds. The rations corresponding with the four treatments were formulated with 4% flaxseed ＋ 9% sunflower seed, 8% flaxseed ＋ 18% sunflower seed, 15% flaxseed, and soybean meal, respectively. Sunflower seed was unshelled and flaxseed was whole. Ratios of ω-6 fatty acid to ω-3 fatty acid in 4 dietary treatments were 5.67, 5.21, 1.07, and 11.83, respectively. It can be concluded that long-term feeding 15% flaxseed had no significant （P〉 0.05） influence on egg production, egg weight, eggshell quality, yolk weight, and percentage of yolk weight. Dietary ratio of ω-6 fatty acid to ω-3 fatty acid had impact on the 0-3 fatty acid levels in yolk, nevertheless yolk fatty acid profiles were different from those of dietary fatty acid compositions.     

Recent Advances in Swine Amino Acid Nutrition

Recent advances in swine protein nutrition are characterized by the development of functional amino acids(AA)in regulating fetal and postnatal survival,growth and development. These AA include arginine,glutamine,glutamate,proline,leucine, cysteine and tryptophan. Due to limited knowledge on AA nutrition,pork producers have traditionally paid little attention to supplementing the arginine family of AA to swine diets. Results of recent studies indicate that functional AA serve important regulatory functions in nutrient metabolism,protein turnover, and immune function,therefore enhancing efficiency of feed utilization by pigs. The underlying mechanisms include activation of nitric oxide,mammalian target of rapamycin,gaseous signaling,and AMP-activated protein kinase pathways, as well as anti-oxidative function. Dietary supplementation with arginine,glutamine, proline or leucine to weanling piglets enhances their growth performance. Arginine or glutamine is also effective in increasing milk production by lactating sows. Furthermore,supplementing arginine to the diet of pregnant gilts between days 30 and 114 of gestation increases the number of live-born piglets and litter birth-weight. Availability of feed-grade functional AA holds great promise for improving animal health and nutrient utilization in pig production worldwide. Additionally, feedstuffs of animal origin[e. g. , blood meal (ring dried),feather meal(hydrolyzed),meat and bone meal, porcine protein meal,and poultry by-product meal(both feed- and petfood-grades )]are excellent and cost-effective sources of both essential and functional AA for formulating balanced swine diets.New knowledge on AA nutrition provides a much needed scientific basis for revising the next edition of swine nutrient requirements.