富硒生物样品中硒的价态和形态分析

本文利用2,3—二氨基萘(DAN)荧光法测定了富硒玉米粉、硒酵母蛋白等样品中四价硒、六价硒、有机硒含量及总硒量。进一步验证了差减法测定不同价态硒含量的实验方法     

微波消解-石墨炉原子吸收光谱法测定大鼠组织中的微量硒

目的:建立微波消解石墨炉原子吸收光谱法(GFAAS)测定大鼠组织中的微量硒的检测方法.方法:采用微波消解法处理样品,用硝酸作为消解剂进行微波消解;采用氯化钯则作为基体改进剂来测定样品中的微量硒.结果:最佳灰化温度为900℃,原子化温度为2500℃;脑组织和肺组织的相对标准偏差(RSD)分别为2.83％和3.05％,样品加标回收率为97％～105％.结论:该方法用于检测大鼠组织中的硒含量,操作简便、快速、准确度好、结果满意,能够适用于生物体内多种组织器官中硒含量的测定与分析.     

两种北虫草硒含量的比较

目的:比较富硒北虫草和普通北虫草的总硒含量、无机硒含量和有机硒含量。方法:采用紫外分光光度法测定富硒北虫草和普通北虫草的总硒含量和无机硒含量,然后通过计算得出有机硒含量。结果:富硒北虫草中总硒含量高于普通北虫草70倍左右,而有机硒含量则大约是普通北虫草的100倍,且富硒北虫草中有机硒含量为总硒含量的97%左右。结论:鞍山华宇生物科技有限公司开发的富硒北虫草中有机硒的含量明显高于普通北虫草,具有良好的使用前景。     

沼泽红假单胞菌富硒发酵条件的研究

通过对沼泽红假单胞菌富硒发酵条件的研究,确定最优的富硒培养方式。采用单一因素变量法,利用微波消解与紫外分光光度法测定沼泽红假单胞菌在不同发酵条件下的生物量变化与富硒效果,确定其最佳培养方式。结果表明,最佳富硒培养条件为:培养温度30℃,环境硒浓度100μg/mL,培养基初始pH为7,硒添加方式应为梯度分次添加,添加时间应为培养周期的第3天、第4天。利用得到的富硒菌种,在最优条件下培养7 d后,测得环境硒浓度下降为10.9μg/mL,硒的转化率为89.1%,菌体富硒量可达到73.54 mg/g(干菌种),其中有机硒含量为97.1%。利用沼泽红假单胞菌生产有机硒具有可行性,富硒菌体可以作为动物饲料添加剂,也可以为人类提供富含有机硒的食品。在以后的实验中,将进一步进行验证和工业化应用。     

亚硒酸钠浓度和培养时间对中华羊茅内生真菌液体培养菌丝体矿质元素的影响

为测定亚硒酸钠浓度和培养时间对中华羊茅内生真菌液体培养菌丝体干物质和矿质元素的影响,菌丝体样品经微波消化后,采用钼蓝比色法、四苯硼钠法、偶氮氯膦III法、邻菲啰啉比色法、氢化物原子荧光光谱法分别测定磷、钾、钙、铁、硒的含量.结果表明,当培养时间为4周、5周、6周、7周或8周时,亚硒酸钠浓度0.1～0.4 mmol/L抑...     

酵母同化无机硒作用的研究

本文报道了酵母在同化无机硒为有机硒的过程中，培养基的种类、亚硒酸钠浓度以及蛋氨酸浓度与生成的硒酵母中的硒蛋氨酸量的某些规律。实验结果表明：硒酵母中硒蛋氨酸的量与培养基的种类有关，随培养基中亚硒酸钠浓度的增加而增加，而随蛋氨酸浓度的增加而减少。提出了一个准确测定生物物质中硒代氰基酸的分析方法。     

含油脂量高的生物样品的消化及其元素的测定

油脂样品,尤其是含油脂量高的生物样品,很难消化。目前还没有一种简便易行的通用方法。本文对此类样品,提出了碳化一消化法。该法较彻底地解决了油脂样品的消化,并适用于所有含油脂的生物样品。这为油脂样品中元素含量的测定,开辟了一条新的途径。通过用冷原子荧光测汞仪测定油脂样品中汞含量,说明本法不仅操作简便,而且用于回收汞这类极易挥发的物质,也能得到满意的结果。     

富硒产品中硒的形态分析及化学评分模式的建立

采用微波水解、HPLC-HG-AFS法测定了硒蛋白粉、硒蛋白片、肽粉、富硒原料等19种硒产品中的总硒、硒代氨基酸和亚硒酸根离子[Se(IV)],分析了硒代氨基酸、Se(IV)和其他形态硒占总硒的百分比及不同形态硒代氨基酸的组成比例。以此为依据,将硒产品分为硒蛋白型、单一硒代氨基酸型、其它形态硒型及有机无机硒混合型。根据DBS42/002-2014规定建立了富有机硒产品评分模式,其中18种为富有机硒产品;根据适硒地区母乳中硒代氨基酸的组成比例提出了硒代氨基酸的化学评分模式,评分结果显示13种以蛋白态硒为主的硒产品中硒代氨基酸的组成比例均与母乳相差甚远,不利于人体平衡吸收利用,其中10种SeMet含量远远超过人体所需,SeCys_2为限制硒代氨基酸。该评分模式的建立对硒产品的开发具有指导意义。     

微波高压罐水解法在氨基酸分析中的应用简报

本文报导了采用微波高压罐水解技术快速水解食物蛋白质,并测定其１７种氨基酸含量的方法。研制的高压罐具有密闭性、微波穿透性好,耐热、耐压、耐腐蚀等特点。采用该高压罐研究了微波强度及作用时间等条件对氨基酸稳定性的影响,在微波输出功率１００Ｗ３５～４５分钟水解了３份食品样品,其氨基酸含量测定结果与传统的１１０℃２２左水解基本相符,１７种氨基酸５次平行测定结果ＣＶ值均＜１０％。     

硒肥对马铃薯硒素吸收、转化及产量、品质的影响

通过设对照(CK)、保水缓释硒肥(W)、生物炭基硒肥(C)、硒酸钠硒肥(S)4个处理来研究不同硒肥对马铃薯(品种为早大白)硒素吸收、转化及产量、品质的影响。结果表明:各处理马铃薯各器官硒含量在生育期内总体上呈下降趋势,马铃薯各器官的硒含量呈现:苗期根茎叶片;成熟期叶片茎块茎的特点;随着硒肥用量的增加,W处理下的总硒、无机硒、有机硒含量呈增大趋势,产量、有机硒转化率、粗蛋白、还原糖和Vc呈先升高后降低的趋势;C处理和S处理下,马铃薯以上各指标均呈先升高后降低的趋势,在低施硒量(0.126 kg/hm2)时,3种硒肥显著降低了马铃薯块茎淀粉含量,之后随着施硒量的增加淀粉含量变化不显著;与对照相比,3种硒肥在适宜施硒量(0.379 kg/hm2)时,马铃薯产量提高了4.87%—5.44%,粗蛋白含量增加了12.18%—20.03%,还原糖提高了6.45%—12.90%,Vc含量提高-0.54%—3.11%,有机硒转化率增加13.00%—15.10%,淀粉含量增加了-0.73%—1.12%;综合考虑3种硒肥对马铃薯含硒量、产量、品质的影响,W处理最佳,C处理次之,S处理最差。     

Determination of denaturated proteins and biotoxins by on-line size-exclusion chromatography-digestion-liquid chromatography-electrospray mass spectrometry

A multidimensional analytical method for the rapid determination and identification of proteins has been developed. The method is based on the size-exclusion fractionation of protein-containing samples, subsequent on-line trypsin digestion and desalination, and reversed-phase high-performance liquid chromatography-electrospray mass spectrometry detection. The present system reduces digestion times to 20 min and the total analysis time to less than 100 min. Using bovine serum albumin and myoglobin as model proteins, optimization of key parameters such as digestion times and interfacing conditions between the different pretreatment steps was performed. The automated system was tested for the identification of infectious disease agents such as cholera toxin and staphylococcal enterotoxin B. This resulted typically in a positive identification by a total sequence coverage of approximately 40%.     

基于地高辛标记对小麦进行Southern杂交分析主要影响因素的优化和验证

以转基因小麦和野生型小麦DNA为材料,对利用地高辛标记对小麦基因组DNA进行Southern杂交分析的影响因素进行了优化研究,包括探针制备与纯化、样品DNA量、酶切体系、真空转印条件、杂交条件、免疫检测方法等。结果表明,对随机引物标记的模板和标记后的探针进行纯化可明显提高探针的标记效率,10μg高质量的DNA样品在80μl的体系中,酶切8～12h可获得良好的效果;真空转膜时使用碱性液比中性液获得的转膜效果更干净;试剂纯度、杂交温度及杂交炉转速等均对杂交效果产生重要影响;配合改进的CSPD涂布方法,使用化学发光检测系统比单纯使用X光片显像更易操作,背景更干净;本研究所优化的地高辛标记的小麦Southern杂交分析显示出较高的灵敏度和信噪比,结果稳定,可克服同位素标记对实验条件、设备及实验人员身体状况等限制,在普通实验室推广应用。     

Importance of complete DNA digestion in minimizing variability of 8-oxo-dG analyses.

Estimates of 8-oxo-2'-deoxyguanosine (8-oxo-dG) in DNA vary at least one order of magnitude using different quantitative methods or even the same method. Our hypothesis is that an incomplete DNA hydrolysis to nucleosides by the conventional nuclease P1 (NP1) and alkaline phosphatase (AP) digestion system plays an important role in contributing to the variability of measurements using HPLC coupled with UV and electrochemical (EC) detection. We show here that factors, such as the amount of DNA, choice of enzymes, their activities, and incubation time, can affect DNA digestion and, thus, cause variability in 8-oxo-dG levels. The addition of DNase I and phosphodiesterases I and II to the NP1 + AP system improves the DNA digestion by completely releasing normal nucleosides and 8-oxo-dG, thereby reducing the interday variations of 8-oxo-dG levels. Diethylenetriamine pentaacetic acid (DTPA), an iron chelator, prevented background increases of 8-oxo-dG during DNA digestion, as well as during the waiting period in the autosampler when a batch of DNA samples is analyzed by HPLC. After optimization of the DNA digestion conditions, the interday variability of 8-oxo-dG measurements using commercially available salmon testes DNA (ST DNA) were 26% over a period of 2 years. Under these optimal conditions, our laboratory variability may contribute as little as 13% to the overall variability as shown by assessment of oxidative DNA damage in a population of smokers. Based on our results, we believe that the modified DNA digestion conditions will provide much more accurate 8-oxo-dG determinations and, thus, more reliable estimates of cancer risk.     

Animal digestive strategies versus anaerobic digestion bioprocesses for biogas production from lignocellulosic biomass

Herbivorous mammals and wood-eating insects are fairly effective in the digestion of plant polymers, such as lignocellulosics. In order to improve methane production from the lignocellulosic biomass, several kinds of anaerobic digestion processes derived from animal models have been devised. However, the rates of biodegradation occurring in the anaerobic bioreactors still remain lower than in animal guts. The effectiveness of the digestive systems of those animals results from the concerted action of the various enzymes (e.g. cellulases, xylanases, esterases, ligninases) produced in their guts as well as their integration with mechanical and chemical actions. Powerful pretreatment (prefermentation) operations are integrated to and support efficiently the microbial fermentation system, e.g. the rumination (i.e. mechanical) in ruminants and the secretion of endogenous cellulases (i.e. enzymatic) or the alkaline treatment (chemical) at mid-way in xylophagous insects. The oxygen gradients along the gastrointestinal tract may also stimulate the hydrolytic activities of some microbial populations. In addition, the solid retention time, the digesta flow and the removal of the end-products are well ordered to enable animals to thrive on a complex polymer such as lignocellulose. At the same time, technologies were developed to degrade lignocellulosic biomass, such as the rumen derived anaerobic digestion (RUDAD) process and the rumen simulating technique (RUSITEC), more elaborated and using rumen microbial consortia. Overall, they showed that the fermentation taking place in the rumen fermentation and even in the hindgut are biological processes that go beyond the limited environmental conditions generally found in anaerobic digesters. Hence, knowledge on herbivores' digestion mechanisms might be better exploited in the design and operation of anaerobic digesters. This literature review is a cross-analysis of the relevant information about the digestive strategies of herbivorous and wood-eating animals and the bioengineering techniques in lignocelluloses degradation. The aim is to highlight strategies of animals' digestion simulation for more effective anaerobic digestion of lignocellulosic compounds and other solid residues.     

A STUDY OF SIEVE ELEMENT STARCH USING SEQUENTIAL ENZYMATIC DIGESTION AND ELECTRON MICROSCOPY

The fine structure of plastids and their starch deposits in differentiating sieve elements was studied in bean (Phaseolus vulgaris L.). Ultrastructural cytochemistry employing two carbohydrases specific for different linkages was then used to compare the chemical nature of "sieve tube starch" (the starch deposited in sieve elements) with that of the ordinary starch of other cell types. Hypocotyl tissue from seedlings was fixed in glutaraldehyde, postfixed in osmium tetroxide, and embedded in Epon-Araldite. Treatment of thin sections on uncoated copper grids with α-amylase or diastase at pH 6.8 to cleave α-(1 → 4) bonds resulted in digestion of ordinary starch grains but not sieve element grains, as determined by electron microscopy. Since α-(1 → 6) branch points in amylopectin-type starches make the adjacent α-(1 → 4) linkages somewhat resistant to hydrolysis by α-amylase, other sections mounted on bare copper or gold grids were treated with pullulanase (a bacterial α-[1 → 6] glucosidase) prior to digestion with diastase. Pullulanase did not digest sieve element starch, but rendered the starch digestible subsequently by α-amylase. Diastase followed by pullulanase did not result in digestion. The results provide evidence that sieve element starch is composed of highly branched molecules with numerous α-(1 → 6) linkages.     

Effective ethanol production by reutilizing waste distillage anaerobic digestion effluent in an integrated fermentation process coupled with both ethanol and methane fermentations

An integrated ethanol–methane fermentation coupled system characterized with full wastewater reutilization was proposed. The waste distillage originated from ethanol distillation was treated with anaerobic digestion and then recycled for medium preparation in the next ethanol fermentation run. This process could enhance wastewater reutilization, save fresh water and reduce energy consumption in the cassava-based ethanol production. The results indicated that, when using anaerobic effluents from the digestion process with only one tank, an ethanol concentration of 10.5% (v/v) compatible with that of conventional one could be achieved, but ethanol fermentation was partially inhibited and operation time gradually prolonged from 48 to 105 h. Using anaerobic effluents from the digestion process with two subsequently connected tanks, ethanol fermentation performance could be largely improved, and the fermentation lag could be completely eliminated. The performance enhancement was due to the concentrations reduction in organic acids, such as acetic and propionic acids in the digestion effluents using two digestion tanks in-series.     

Physiological roles of group X-secreted phospholipase A2 in reproduction, gastrointestinal phospholipid digestion, and neuronal function

Although the secreted phospholipase A(2) (sPLA(2)) family has been generally thought to participate in pathologic events such as inflammation and atherosclerosis, relatively high and constitutive expression of group X sPLA(2) (sPLA(2)-X) in restricted sites such as reproductive organs, the gastrointestinal tract, and peripheral neurons raises a question as to the roles played by this enzyme in the physiology of reproduction, digestion, and the nervous system. Herein we used mice with gene disruption or transgenic overexpression of sPLA(2)-X to clarify the homeostatic functions of this enzyme at these locations. Our results suggest that sPLA(2)-X regulates 1) the fertility of spermatozoa, not oocytes, beyond the step of flagellar motility, 2) gastrointestinal phospholipid digestion, perturbation of which is eventually linked to delayed onset of a lean phenotype with reduced adiposity, decreased plasma leptin, and improved muscle insulin tolerance, and 3) neuritogenesis of dorsal root ganglia and the duration of peripheral pain nociception. Thus, besides its inflammatory action proposed previously, sPLA(2)-X participates in physiologic processes including male fertility, gastrointestinal phospholipid digestion linked to adiposity, and neuronal outgrowth and sensing.     

厌氧消化酸抑制研究进展

厌氧消化工艺目前已广泛应用于各类废水的处理处置过程中,但在实际运行中,受消化条件和物料性质的影响,消化系统经常遭受由挥发性脂肪酸积累过多导致的酸抑制问题,引发产气量下降、产甲烷率降低等问题。近年来,有研究者发现,挥发性脂肪酸的种类和浓度及pH、温度是影响酸抑制的主要因素。基于此,相关研究者分别尝试了添加碱性化学药剂和微量元素及利用生物强化技术与微生物电化学技术来解除酸抑制的尝试,并都取得了不错的效果。本文综述了厌氧消化过程中酸抑制的产生过程、抑制机理及恢复方法,以期为解决厌氧消化酸抑制问题提供参考。     

Cytochemical studies of pectin digestion in epidermis with specific cell separation

Summary This investigation concerns a unique type of epidermal cells in the anther ofStrelitzia reginae. At dehiscence these cells are released and form multicellular threads. The radial and tangential middle lamella regions of their cell walls disintegrate by the formation of numerous growing and fusing cavities. The possibility that this process could be due to digestion by pectinase was elucidated by use of cytochemical methods. In immature ordinary and thread-forming cells staining for pectin with hydroxylamine-ferric chloride yielded reaction products mainly in the middle lamella region and the subcuticular layer. After the appearance of cavities reaction took place around but not inside these formations. Treatment with fungal pectinase caused degradation of cell walls in ordinary epidermal tissue. Mature cell walls appeared more resistant to the lytic action than immature ones. In thread-forming tissue, independent of the stage of maturation, digestion of the pectin rich regions was induced. However, the fungal enzyme was not able to produce cavities. No pectin reaction with hydroxylamine-ferric chloride was obtained after pectinase treatment.     

Further cytochemical studies on the perichromatin granules

Summary The perichromatin granules were studied in hepatocytes of experimental rats injected with cycloheximide because the increased number of these nuclear components after such treatment facilitated their cytochemical investigation. Most perichromatin granules were sensitive to the digestion with pepsin and ribonuclease. In contrast, small population of perichromatin granules was resistent to such digestion under conditions which remove known RNA containing components such as ribosomes, nucleolar RNP components and interchromatin granules. The size of these resistent perichromatin granules was reduced and they consisted of filaments the width of which was similar to that of filaments in the chromatin. Moreover, a small population of perichromatin granules was sensitive to the digestion with pepsin and deoxyribonuclease. The size of these granules was only slightly reduced. All these observations indicate that most perichromatin granules contain the RNA and some the DNA. A possibility also exists that the perichromatin granules might contain both RNA and DNA but in various proportions. In addition, partial digestion with pepsin followed by a complete digestion with ribonuclease and deoxyribonuclease removed perichromatin granules as well as other nucleoprotein structures. On the other hand, such digestion facilitated the visualization of the nuclear and cytoplasmic skeleton (matrix) in situ.Dedicated to the memmory of Dr. W. Bernhard