生长激素对蛋白质动态代谢与氨基酸利用的调控

生长激素是调节动物生长的众多激素中最重要的一种 ,它通过在肌肉与脂肪组织之间极强的营养重分配作用 ,增加体蛋白沉积 ,减少脂肪沉积 ,从而改变这两种组织的生长状况来实现其促生长功能。动物体内蛋白沉积是蛋白合成与降解同时进行的两个过程动态平衡的结果。本文综述了近年来有关生长激素对动物蛋白质动态代谢与氨基酸利用调控方面的研究结果 ,指出生长激素使蛋白质合成与降解速率均增加 ,整体蛋白质周转代谢强度加大 ,从而导致蛋白质沉积增加。

生长猪氨基酸利用的数量观点：理论与实践

综述了影响生长猪氨基酸利用的主要因素，探讨了养猪生产中有关氨基酸营养问题。结果表明，通过测定体沉积蛋白质（PD）中氨摹酸的沉积、生理氨摹酸损失（主要是皮肤和毛发、肠道内源氨基酸损失）与不可避免的氨基酸的分解代谢来估测氨基酸的需要量，估测氨基酸需要量的数据必须建立在蛋白质沉积、活体重、饲喂水平、饲料原料组成和饲料原料的可利用氨基酸含量上。既然PD是氧基酸需要量的决定因素，在建立日粮最佳氨基酸水平时，必须认真考虑活体重或动物问的差异对PD的影响。因此，饲料组成与机体蛋白质中氨基酸组成的变化对用于蛋白质沉积需要的可利用氨基酸利用的影响必须进行更精确的定量。

利用可消化氨基酸配制动物日粮

利用可消化氨基酸配制动物日粮徐州协尔动物营养保健有限公司卞德民从动物营养角度来讲，动物的生产性能取决于饲料配方中各种营养成分，尤其是微量元素和氨基酸的平衡性。由于动物的微量元素营养是一个复杂的综合体，人们对各元素间的拮抗性、协同性机理尚不明确，因此确...

餐厨垃圾蛋白质酸水解及产油微生物圆红冬孢酵母的氨基酸吸收

生物法资源化餐厨垃圾生产微生物油脂,是一种经济环保安全有效的处理途径;优化水解预处理工艺和研究微生物对水解液氮源的利用规律有助于推动餐厨垃圾资源化的工业化进程.首先酸水解餐厨垃圾,再使用高效液相色谱分析产油酵母对氨基酸的生物吸收规律.结果显示,优化的水解条件为硫酸浓度1.5%(φ),液固比33:1(V/m),温度383 K,反应时间60 min.在优化条件下,阿伦尼乌斯方程拟合的水解反应指前因子为23.088 kJ/mol.餐厨垃圾水解后部分蛋白质以游离氨基酸形式存在,成分与常见氮源(蛋白胨)类似.以餐厨垃圾水解液作为唯一底物,培养产油酵母——圆红冬孢酵母,收获23.5 g/L的生物量和4.6 g/L的油脂产量,对水解液凯式氮和游离氨基酸的利用率分别达到43.3%和94.0%.酵母对氨基酸的利用具有选择性:首先在延迟期吸收第一组氮源(天冬氨酸、谷氨酸、丝氨酸,组氨酸、苏氨酸、酪氨酸、缬氨酸、异亮氨酸);其次在对数期吸收第二组氮源(丙氨酸、精氨酸、甘氨酸);最后在稳定期吸收第三组氮源(脯氨酸);部分氨基酸不能被明显吸收,被归类为第四组氮源(苯丙氨酸、赖氨酸、亮氨酸).本研究表明餐厨垃圾的营养成分能够支持圆红冬孢酵母的生长和产油,是潜在的微生物油脂的廉价底物;结果为有机废弃物生产高附加值生物质产品和餐厨垃圾的资源化处理提供了基础理论数据.(图4表4参40)

Enzymatic Hydrolysis of Defatted Mackerel Protein with Low Bitter Taste

Ultrasound-assisted solvent extraction was confirmed as a novel,effective method for separating lipid from mackerel pro-tein,resulting in a degreasing rate (DR) of 95% and a nitrogen recovery (NR) of 88.6%.To obtain protein hydrolysates with high ni-trogen recovery and low bitter taste,enzymatic hydrolysis was performed using eight commercially available proteases.It turned out that the optimum enzyme was the ‘Mixed enzymes for animal proteolysis’.An enzyme dosage of 4%,a temperature of 50℃,and a hydrolysis time of 300 min were found to be the optimum conditions to obtain high NR (84.28%) and degree of hydrolysis (DH,16.18%) by orthogonal experiments.Glutamic acid was the most abundant amino acid of MDP (defatted mackerel protein) and MDPH (defatted mackerel protein hydrolysates).Compared with the FAO/WHO reference protein,the essential amino acid chemical scores (CS) were greater than 1.0 (1.0 1.7) in MDPH,which is reflective of high nutritional value.This,coupled with the light color and slight fishy odor,indicates that MDPH would potentially have a wide range of applications such as nutritional additives,functional ingredients,and so on.

Leaching of Electronic Waste Using Biometabolised Acids

The revolution in information and communication technology has brought huge technical benefits and wealth, but has created a major global problem： the generation of vast amounts of electronic waste, or e-waste through product obsolesce. The challenge in managing e-waste will be in developing sustainable recycling tech- nologies that are able to address the volume and complexity of this waste using cost effective and ecologically sen-sitive methods. In this study, the capability or microorganism metabolic acids in dissolving the metallic tractions from waste printed circuit boards was examined. Several factors were considered in the examination of the activityof the acids-including secondary reactions, solution pH, temperature and the nature of ligands in solutions （or bioacid constituents）. The leaching tests were cgnducted ex-situ, using synthetic organic acids. Leaching was performed for periods of up to 6 hat 70-90 ℃ and 1000 r-min-1.

Energy Value and Amino Acid Bioavailability of Faba Bean Seeds in Broilers Diets

The aim of this study was to determine the apparent （AME） and true metabolizable energy （TMEn） as well as the crude protein （CP） and amino acid （AA） total tract （by excreta collection） digestibility （bioavailability） of faba bean seeds （FBS） of the Greek cultivar ＂Polikarpi＂. Forty eight broilers were placed in individual cages and randomly allocated into 4 dietary treatments. Birds consumed 80 g d1 of either a typical commercial diet or the same diet in which 100, 200 or 300 g kg^-1 had been substituted by ground FBS. The experiment lasted 15 d. Apparent and true CP bioavailability of FBS were significantly decreased （P 〈 0.05） only at the inclusion rate of 300 g kg-1. AA bioavailability remained at high levels （-0.80） with the exception of cystine and was similar to CP mean. The mean AME and TMEn values of FBS were estimated equal to 11.1 and 11.4 MJ ME kg^-1, respectively.

Suppression of glutamate synthase genes significantly affects carbon and nitrogen metabolism in rice (Oryza sativa L.)

Rice (Oryza sativa) glutamate synthase (GOGAT,EC 1.4.1.14) enzymes have been proposed to have great potential for improving nitrogen use efficiency,but their functions in vivo and their effects on carbon and nitrogen metabolism have not been systematically explored.In this research,we analyzed transcriptional profiles of rice GOGAT genes using a genome-wide microarray database,and investigated the effects of suppression of glutamate synthase genes on carbon and nitrogen metabolism using GOGAT co-suppressed rice plants.Transcriptional profiles showed that rice GOGAT genes were expressed differently in various tissues and organs,which suggested that they have different roles in vivo.Compared with the wild-type,tiller number,total shoot dry weight,and yield of GOGAT co-suppressed plants were significantly decreased.Physiological and biochemical studies showed that the contents of nitrate,several kinds of free amino acids,chlorophyll,sugars,sugar phosphates,and pyridine nucleotides were significantly decreased in leaves of GOGAT co-suppressed plants,but the contents of free ammonium,2-oxoglutarate,and isocitrate in leaves were increased.We conclude that GOGATs play essential roles in carbon and nitrogen metabolism,and that they are indispensable for efficient nitrogen assimilation in rice.

Effect of Carbon and Nitrogen Availability on Metabolism of Amino Acids in Germinating Spores of Arbuscular Mycorrhizal Fungi

The effects of carbon （C） and nitrogen （N） sources on N utilization and biosynthesis of amino acids were examined in the germinating spores of the arbuscular mycorrhizal （AM） fungus Glomus intraradices Schenck ＆ Smith after exposure to various N substrates, CO2, glucose, and/or root exudates. The N uptake and de novo biosynthesis of amino acids were analyzed using stable isotopic labeling with mass spectrometric detection. High-performance liquid chromatography-based analysis was used to measure amino acid levels. In the absence of exogenous N sources and in the presence of 25 mL L^-1 CO2, the germinating AM fungal spores utilized internal N storage as well as C skeletons derived from the degradation of storage lipids to biosynthesize the free amino acids, in which serine and glycine were produced predominantly. The concentrations of internal amino acids increased gradually as the germination time increased from 0 to 1 or 2 weeks. However, asparagine and glutamine declined to the low levels; both degraded to provide the biosynthesis of other amino acids with C and N donors. The availability of exogenous inorganic N （ammonium and nitrate） and organic N （urea, arginine, and glutamine） to the AM fungal spores using only CO2 for germination generated more than 5 times more internal free amino acids than those in the absence of exogenous N. A supply of exogenous nitrate to the AM fungal spores with only CO2 gave rise to more than 10 times more asparagine than that without exogenous N. In contrast, the extra supply of exogenous glucose to the AM fungal spores generated a significant enhancement in the uptake of exogenous N sources, with more than 3 times more free amino acids being produced than those supplied with only exogenous CO2. Meanwhile, arginine was the most abundant free amino acid produced and it was incorporated into the proteins of AM funsal spores to serve as an N storage compound.