Status and habitat associations of the threatened northern abalone: importance of kelp and coralline algae

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食糜样本中11种生物胺同步检测方法的建立

旨在建立一种利用液质联用（liquid chromatography mass spectrometry,LC-MS）技术实现对猪肠道食糜中多种生物胺进行同步检测的方法。试验首先优化了丹磺酰氯（dansyl chloride,DNS）对生物胺的衍生条件,并进一步确定了肠道食糜样品中生物胺的最佳净化方法。结果显示,衍生条件在衍生剂浓度为8 mg·mL^-1,衍生温度为40℃的条件下,衍生90 min为最佳。生物胺净化方法确定为先用乙酸乙酯进行提取,衍生结束后再用乙酸乙酯进行萃取的组合方式提取生物胺的效果最好;11种生物胺在5～1 000 μg·L^-1的质量浓度范围内定量结果呈良好的线性关系（R²>0.99）,检出限和定量限分别为0.01～0.23 μg·L^-1和0.03～0.76 μg·L^-1;各生物胺的日内相对标准偏差在0.73%～ 7.92%,日间相对标准偏差在0.07%～8.67%。最后采用本方法对仔猪回肠、盲肠、结肠和直肠食糜样品中的生物胺进行检测,初步确定了11种生物胺在不同肠段食糜中的含量分布。通过对仔猪回肠、盲肠、结肠和直肠中的食糜样品进行检测,发现食糜中的生物胺主要为亚精胺、腐胺、尸胺、精胺和组胺,而酪胺、1,7-二氨基庚烷、5-羟色胺和胍基丁胺4种生物胺含量较少,色胺和苯乙胺未检出。综上所述,本试验建立的方法具有结果准确、灵敏度高、重现性好等优点,可用于仔猪不同肠道段食糜中多种生物胺的同步检测。     

ON THE RIVER WATER QUALITY MODEL

This paper presents the development of water quality modelat home and abroad and built up methods and course of water quality modelas well as the fundamental form of its equation. The above built up waterquality model of river is beneficial to spreading.     

初级芳香胺的高分辨质谱裂解规律研究

为探究初级芳香胺类化合物的质谱裂解规律,本研究采用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法,在电喷雾正离子模式下采集数据,根据一、二级质谱离子的精确质荷比推导14种初级芳香胺类化合物可能的裂解途径。结果表明,由于分子结构中存在氨基基团,因此初级芳香胺类化合物极易被质子化,更易形成[M+H]⁺。断裂过程主要发生NH₃中性碎片的丢失,产生[M+H-NH₃]⁺特征碎片离子,在此基础上,氯代苯胺类化合物发生碳正离子重排后,丢失氯原子形成[·M+H-NH₃-Cl]⁺碎片离子。甲氧基取代苯胺类化合物可丢失CH₃O基团产生碎片离子[M+H-NH₃-CH₃O]⁺,或发生碳正离子转移重排至苯甲基,进一步丢失CH₃和CH₃O基团。甲基或甲氧基取代的联苯胺类化合物还会发生CN键断裂形成[M+H-NH]⁺,继而丢失NH₃中性碎片形成[M+H-NH-NH₃]⁺。偶氮苯类化合物中高键能的偶氮键不易断裂,碎片离子主要通过两侧的CN键断裂形成。本研究提出的最佳电离方式和质谱裂解规律为初级芳香胺类化合物的快速鉴定提供了重要依据。     

Short‐term and residual availability of nitrogen after long‐term application of organic fertilizers on arable land

Knowledge on short‐term and long‐term availability of nitrogen (N) after application of organic fertilizers (e.g., farmyard manure, slurry, sewage sludge, composts) provides an important basis to optimize fertilizer use with benefits for the farmer and the environment. Nitrogen from many organic fertilizers often shows little effect on crop growth in the year of application, because of the slow‐release characteristics of organically bound N. Furthermore, N immobilization after application can occur, leading to an enrichment of the soil N pool. However, this process finally increases the long‐term efficiency of organic fertilizers. Short‐term N release from organic fertilizers, measured as mineral‐fertilizer equivalents (MFE), varies greatly from 0% (some composts) to nearly 100% (urine). The most important indicators to be used for predicting the short‐term availability of N are total and NH ‐N contents, C : N ratio (especially of the decomposable organic fraction), and stability of the organic substances. Processing steps before organic fertilizers are applied in the field particularly can influence N availability. Composting reduces mineral‐N content and increases the stability of the organic matter, whereas anaerobic fermentation increases NH ‐N content as well as the stability of organic matter, but decreases the C : N ratio remarkably, resulting in a product with a high content of directly available N. Nevertheless, long‐term effects of organic fertilizers rather slowly releasing N have to be considered to enable optimization of fertilizer use. After long‐term application of organic fertilizers, the overall N‐use efficiency is adequate to a MFE in the range of 40%–70%.     

Biogenic amines and pheromones as feed attractants for the freshwater prawn Macrobrachium rosenbergii

The use of attractants in formulated feeds has become paramount to economic success owing to the need to optimize feed conversion rates by maximizing consumption and reducing feed waste so as to lower production costs. Taking into account the importance of attractants, a series of experiments designed to evaluate the potential of natural molecules was carried out with the freshwater prawn, Macrobrachium rosenbergii (De Man, 1879). Two biogenic amines (putrescine and cadaverine) and two sexual pheromones (crab urine and freshwater prawn green gland extracts) were compared with reference products proven to be major attractants, such as squid extracts and a commercial product. These were incorporated in a basal diet designed to be non-attractive. Results were obtained by three different approaches. First, a laboratory bioassay was conducted to evaluate the time that lapsed as an animal presented the different alimentary stages (perception, orientation, movement, arrival and ingestion). A second approach was developed in a commercial farm, to test the performance of the attractants in the presence of other stimuli and in conditions of water movement that may cause rapid dilution. The test consisted of placing a quantity of feed on a tray, which was submerged in a cage (1 m³) in which 10 animals (five males and five females) of 20 g mean weight were placed. The tray was lifted at different times (10, 20, 40 and 80 rain) and the number of pellets left was counted. Three replicates were performed for each treatment. A third approach consisted of incorporating an antibody in the feed. Following a methodology similar to the above-mentioned, hepatopancreas and mouth parts of the prawns were collected at different times. Later, immunodiffusion tests were executed to assess the actual ingestion of the feed. The results obtained from the different approaches indicated that cadaverine included at 0.2% was the best attractant. On the other hand, the crab urine and freshwater prawn green gland extracts exhibited good results only with males, so their utilization could be recommended for monosexual cultures.     

中华绒螯蟹离体卵巢发育的调控作用

通过卵巢离体实验研究性激素、大豆黄酮、生物胺及神经组织对中华绒螯蟹(Eriocheir sinensis)卵巢发育的影响。结果表明，雌二醇可显著地增大卵黄发生前期、初级卵黄发生期和次级卵黄发生期卵巢卵母细胞的直径，黄体酮可显著增大卵黄发生前期卵巢卵母细胞直径，对初级卵黄发生期和次级卵黄发生期的卵母细胞直径有极显著地促进作用；大豆黄酮具有增大卵母细胞直径的作用，但作用不显著；脑和胸神经团对卵黄发生前期、初级卵黄发生期的卵母细胞直径有显著增大作用，对于次级卵黄发生期卵母细胞直径有极显著增大作用；视神经节作用不明显；5-羟色胺通过脑可显著促进卵黄发生前期、初级卵黄发生期卵巢卵母细胞直径的增大，极显著促进次级卵黄发生期卵巢卵母细胞直径的增大，还通过胸神经节极显著增大各期卵巢的卵母细胞直径；多巴胺作用不明显。     

以生物胺变化评价冷藏罗非鱼片腐败进程

为了探讨生物胺指标评价鱼肉腐败进程的可能性及其安全范围,应用反相高效液相色谱法测定冷藏罗非鱼片贮藏过程的生物胺变化,用以判断鱼片的腐败进程。结果表明:新鲜鱼片初始单胺和多胺总量较高,二胺总量很低。贮藏过程中单胺和多胺波动变化并呈下降趋势,尸胺、腐胺含量快速增加成为主要生物胺。含有尸胺+腐胺的二胺、生物胺指数、总生物胺等指标与其两者增长趋势相似。相关分析表明尸胺、腐胺、二胺、生物胺指数、总生物胺与贮藏时间、微生物数量和氨基态氮具有高度相关性。经回归分析表明假单胞菌、肠杆菌的增长与尸胺、腐胺具有重要的对应关系。尸胺、腐胺和二胺可简便有效评价鱼片腐败进程;但综合考虑组胺和酪胺的毒性,则生物胺指数(BAI)更适用,冷藏罗非鱼片生物胺指数的初步判别范围为:<20mg/kg,新鲜;20～40mg/kg,可接受;>40mg/kg,腐败。该研究为冷藏罗非鱼片生物胺的限量标准提供数据参考。     

Effect of cinnamon essential oil on the microbiological and physiochemical characters of fresh Italian style sausage during storage

In order to study the effect of cinnamon essential oil (CEO) on the microbiological and physiochemical characters of fresh Italian style sausage, CEO (0%, 0.1%, and 0.5%, v/w) was added into ground meat, cased, and stored at 4°C. Lipid oxidation, instrument color, total viable aerobic counts, Enterobacteriaceae, biogenic amines, and total volatile basic nitrogen (TVB‐N) were investigated during 10 days (day). Results showed that CEO treatments had lower thiobarbituric acid reactive substances (TBARS), b* value, aerobic and Enterobacteriaceae counts, biogenic amine contents, and TVB‐N and higher a* values at 4, 6, 8, and 10 days compared to the control, whereas 0.5% CEO treatment had better effect than 0.1% CEO. CEO improved color shelf‐life by inhibiting lipid oxidation and prevented the increase in biogenic amines and TVB‐N by reducing microbial counts of fresh sausage during storage. This study suggested that CEO could be applied in the food industry to improve the shelf‐life of meat products.     

液相色谱法测定食品中的生物胺

[目的]为测定食品中的生物胺寻求一种快速、简单的方法。[方法]采用以丹磺酰氯作为衍生剂,室温离子液体作为萃取、富集和衍生介质,以超声作为反应条件的液相色谱法测定食品中的生物胺。[结果]测定食品中的生物胺较理想的衍生条件是：衍生剂量1.5ml,硼砂缓冲液的pH9.10,硼砂缓冲液量为2 ml,1 ml[OMIM]PF6离子液,超声时间为20 min。[结论]液相色谱法是测定食品中生物胺含量的一种快速、简单的方法。 更多还原