荔枝果皮多酚氧化酶酶促褐变的研究

从荔枝果皮分别提取多酚氧化酶及其天然底物,两者相作用,形成褐色产物,酶促褐变是荔枝果皮变褐的原因。 从荔枝果皮提取的酚类物质中分离出多酚氧化酶的天然底物。此底物的紫外吸收光谱分别在215和280 nm有一强的和一弱的吸收峰,它的红外吸收光谱在3190、1600、1500 cm~(-1)有很强的吸收峰。     

鸭梨黑心病的研究 Ⅱ.酚类物质的酶促褐变

通过对鸭梨贮存过程中发生的黑心病问题的研究。发现:(1)多酚氧化酶活性和总多酚类化合物的含量,在鸭梨果实的不同部位中是不相同的,果心最高、果皮次之、果肉最低。当鸭梨发生黑心病后,果心总多酚类化合物含量下降。(2)应用纸上层析和高压电泳对多酚类化合物进行分离和鉴定。证明在果心内有7种多酚类化合物,在果肉中有5种,果皮中有6种。其中以绿原酸为多酚类化合物的主要成分,并在果心内的含量最高。(3)鸭梨黑心后绿原酸在果心内的含量下降。应用绿原酸作为多酚氧化酶的作用底物,酶作用后绿原酸在324毫微米的最大吸收峰下降,在200毫微米处出现新的最大吸收区,与鸭梨自然褐变产物相似。根据以上实验结果,我们认为多酚类化合物的酶促褐变是造成鸭梨黑心病的生理原因,绿原酸可能是主要的产物。     

椰子褐变底物的初步研究(简报)

经高效液相色谱分析,椰子褐变底物主要是绿原酸和多巴胺,其分部收集液能与已初步纯化的椰子多酚氧化酶作用,形成褐变产物,其吸收光谱与标准的绿原酸、多巴胺的氧化产物相似。     

香蕉后熟过程中多酚氧化酶活性和酚类物质含量的分布变化

用乙烯利处理青熟香蕉,跃变后六天老熟,果皮出现芝麻点褐斑。跃变后果皮中的多酚氧化酶活性较跃变前低;果肉中的酶活性则跃变后较之跃变前高5—7倍。跃变前果肉中酚类物质较果皮高1—3倍,跃变后下降,果皮则不同,酚类物质跃变后较跃变前高。在香蕉整个后熟过程中,果肉酚含量与多酚氧化酶活性变化无相关性;果皮则呈显著负相关。     

甘蔗茎尖离体培养褐变影响因素及细胞区室结构分析

该研究通过综合分析对甘蔗(ROC 22)茎尖离体培养褐变不同条件因素的影响以及褐变细胞区室结构的变化,探讨了甘蔗茎尖离体培养褐变的机理机制。结果表明:不同芽位茎尖诱导成活率具有明显差异,随着芽位的增加,诱导成活率不断降低;不同季节取芽对外植体茎尖总酚类物质含量无明显影响;但不同芽位及不同催芽天数,外植体芽的总多酚含量明显不同,随着催芽天数的增加,不同芽位的多酚含量呈现由低升高的趋势;蔗芽在培养4周时多酚含量较低,适宜进行采芽接种培养;从褐变甘蔗茎尖的解剖结构变化分析,褐变甘蔗茎尖细胞离体培养初期细胞核结构出现变形,线粒体有肿胀拉长,部分液泡膜开始分解;中后期质壁分离更为严重,胞质中出现大量溶酶体,线粒体等细胞器全分解,细胞膜、液泡膜、核膜、线粒体膜的双层膜结构出现破损和缺口;而正常发育的茎尖细胞,能基本保持细胞核的形态结构,只有少量的溶酶体出现。因此,可以推测细胞核和线粒体结构变形以及膜系统的大量破损是甘蔗茎尖培养褐变死亡的原因。     

防止速冻荔枝果皮变褐的研究

荔枝(Litchi chinensis Sonn.)果实采收后容易变褐变质。三年来,我们研究了荔枝果皮的多酚氧化酶与变褐的关系以及防止速冻荔枝果皮变褐的各种枝术措施。证明:荔枝果皮中具有氧化邻苯二酚的多酚氧化酶,在果皮褐变过程中该酶起着重要的作用,采用热处理及化学药物处理能抑制多酚氧化酶活性,达到防止速冻荔枝果皮变褐的目的。     

烟草多酚氧化酶的分离与固定化技术研究

多酚氧化酶属于氧化还原酶类,国际酶学委员会推荐名为儿茶酚氧化酶（ＥＣ１．１０．３．１ｐｏｌｙｐｈｅｎｏｌｏｘｉｄａｓｅ,ＰＰＯ）．该酶与食品工业、三废处理、医药卫生关系较为密切,因而研究较多．如近年来鸭梨［１］、蘑菇［２］、香蕉果肉组织［３］、荔枝果皮［４］等等中的多酚氧化酶均有研究报道．目前研究用固定化多酚氧化酶检测废水中酚类物质含量,进行环境检测;及其从工业废水中除去酚类,达到治理三废的目的．Ｍｏｓｂａｃｎ［５］（１９７６）研制成多酚氧化酶固定化酶柱,与氧电极检测器组合联用,可检测水中２０…     

香蕉低温酶促褐变

7℃低温导致香蕉果皮变褐,褐变程度可用提取液的OD_(450)值表示。随低温处理时间的延长,OD_(450)增大;还原性物质抗坏血酸、谷胱甘肽含量迅速下降;多酚氧化酶底物多巴胺先有增加,接着降低。 低温下,多酚氧化酶(PPO)、过氧化物酶(POD)和过氧化氢酶(CAT)活性较常温低,PPO和POD的游离态酶活性增高。此外,H_2O_2处理加速果皮变褐,刺激PPO及POD活性;棓酸丙酯处理起相反的效应。故认为香蕉低温褐变是低温损伤、酶促褐变引起的一个复杂过程。     

梨果实采后果心褐变与细胞膜结构变化的关系

作为采后贮藏中经常发生的一种生理病害——梨果心褐变,与细胞膜结构的变化、酚类底物和多酚氧化酶（PPO）的分布、PPO的存在形式和活性有关。细胞膜结构变化或遭受玻坏时,PPO与底物易接触。PPO主要以游离态形式存在且活性高,可导致严重的果心褐变。诱发果心竭变的主要因素冷害、果实缺钙和高二氧化碳伤害都与细胞膜结构的稳定性密切相关。     

拟茎点霉侵染对采后龙眼果皮LOX活性和膜脂脂肪酸组分的影响

用拟茎点霉(Phomopsis longanae Chi)侵染福眼龙眼(Dimocarpus longan Lour. ‘Fuyan’)果实,研究龙眼果皮脂氧合酶(LOX)活性、膜脂脂肪酸组分和细胞膜透性的变化及其与果皮褐变的关系。结果表明：拟茎点霉侵染导致龙眼果皮褐变指数、LOX活性和细胞膜透性增加,不饱和脂肪酸组分[亚油酸(C18∶2)、亚麻酸(C18∶3)和花生一烯酸(C20∶1)]下降而饱和脂肪酸组分[棕榈酸(C16∶0)和硬脂酸(C18∶0)]增加,脂肪酸不饱和指数(IUFA)和脂肪酸不饱和度下降。拟茎点霉侵染提高龙眼果皮LOX活性和加速膜脂不饱和脂肪酸的降解,从而破坏细胞膜系统的完整性,导致膜系统区室化功能丧失,使多酚氧化酶与酚类物质接触,引起酚类物质的酶促氧化和黑褐色高聚物形成,导致龙眼果皮褐变。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

真菌类遗传学分析的知识结构教学

本文以认知结构理论为指导,讨论了真菌类遗传分析与高等动植物遗传分析的内在联系,认为利用这种内在联系进行教学可收到好的效果并说明了作者的具体教学过程。 Abstract:In the paper, the relationship between genetic analysis of Fungi and genetic analysis of high animal and plant was discussed.A good results were obtained when we adopted this method in the teaching.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

Time of detection of recessive genes: effects of system of mating and number of examined individuals

Summary Anthers were cultured from two sets of seven lines of hexaploid wheat (Triticum aestivum L.) with different cytoplasms, the euplasmic nucleus donors, Siete Cerros 66 and Penjamo 62, as well as their six alloplasmic lines derived from wild relative species of the genera Triticum and Aegilops. Significant cytoplasmic and nuclear effects but no cytoplasmic-nuclear interaction were found for embryogenic anther response, with the best performance of Penjamo 62 in Ae. kotschyi cytoplasm. Plant regeneration was not affected significantly by the cytoplasmic background of the lines cultured. The possible genetic implications of the observed cytoplasmic and nuclear influences on the in vitro haploid induction of wheat are discussed.