无花果曲霉原生质体形成与再生条件的探讨

根据正交试验得出无花果曲霉原生质体形成的最佳条件,用１％的混合酶液（０．５％纤维素酶＋０．２５％蜗牛酶＋０．２５％溶菌酶）作用无花果曲霉菌体细胞,原生质体产量达３．２×１０７个·ｍｌ－１,渗透压稳定剂为０．６ｍｏｌ·Ｌ－１ＫＣｌ于０．２ｍｏｌ·Ｌ－１ＰＯ３＋４（ｐＨ５．８）中,酶解时间和酶解温度分别为３．０ｈ、３０℃．比较不同酶解时间、再生稳定剂和碳源等因素对原生质体再生的影响,可确定最佳再生条件,再生率达３０％以上．     

角质蛋白酶固态发酵工艺及酶解条件的研究

曲霉Ａ２８－８是一株优良的角蛋白酶分泌突变菌株。其最佳固体发酵培养基为：２０％羽毛粉,８０％麸皮和微量无机氮（每克培养基中加０．５ｍｇ）;最适产酶条件为：起始ｐＨ７．５～８．０,温度２８℃～３０℃,时间为６０～７０小时,酶活高达２５００ＫＵ／ｇ曲;最适酶解条件为ｐＨ７．０～９．０,温度４５℃～５０℃。     

新月弯孢霉原生质体制备及再生条件的研究

以从自然界中筛选的新月弯孢霉（Ｃｕｒｖｕｌａｒｉａｌｕｎａｔａ）Ｄ－１为出发菌株,进行原生质体制备及再生条件的研究。将培养至１６ｈ的Ｄ－１菌丝体经ＤＴＴ溶液处理３０ｍｉｎ后,用溶壁酶和纤维素酶的混合酶液于３０℃下酶解４ｈ,原生质体释放量达到６．０×１０^６个／ｍＬ,原生质体再生率为８．３％。     

米曲霉原生质体融合及杂合二倍体的形成

采用混合酶液处理纤维素酶高产苗株３０４２_Ｎ－２（天冬酰胺缺陷型“Ａｓｎ^－”）及蛋白酶高产菌株３０４２_Ｎ－１９（蛋氨酸缺陷型“Ｍｅｔ^－”）的营养菌丝,获得原生质体,以ＰＥＧ为助融剂进行融合处理,成功地获得了米曲霉（Ａｓｐｅｒｇｉｌｌｕｓｏｒｙｚａｅ）原生质体的营养互补融合。将异核体菌落的菌丝转接到合有０．１％樟脑的新鲜ＭＭ上,２５℃诱导培养７─１５天,挑取绿色角变菌落的孢子,将其转接到ＭＭ上能迅速生长,经孢     

辣椒子叶原生质体分离条件的研究

以不同基因型的辣椒子叶为供体组织进行辣椒原生质体分离条件的研究,结果表明：幼龄子叶的原生质体产量与活力均高于老龄子叶;酶解过程中酶液渗透压、酶液浓度、酶解时间均对原生质体分离效果产生重要影响。对于辣椒子叶原生质体,最佳分离条件为酶液甘露醇浓度０．５ｍｏｌ／Ｌ,纤维素酶Ｃｅｌｌｕｌａｓｅ Ｏｎｚｕｋａ Ｒ－１０ １．５,果胶酶Ｍａｃｅｒｏｚｙｍｅ Ｒ－１０ ０．６％,酶解时间８－１０ｈ。不同基因型辣     

芽孢杆菌M_(50)产生β甘露聚糖酶的条件研究

从土壤中分离到９ 株产生β甘露聚糖酶的芽孢杆菌（ Ｂａｃｉｌｌｕｓ ｓｐ ．） 。Ｂａｃｉｌｌｕｓｓｐ ． Ｍ５０２５０ｍ Ｌ三角瓶摇瓶培养试验,以４ ％ 的魔芋粉为碳源,１－０ ％ （ ＮＨ４）２ＳＯ４ 为氮源,０－３５ ％Ｎａ２ＣＯ３ ,３０ ～３４ ℃培养６０ｈ 产酶达到高峰。酶活力为１８０ ～２００ｕ／ｍ Ｌ。１００Ｌ 罐发酵,在３０ ～３２ ℃,１∶０ ．７５ｖｖｍ 通气量,２００ｒ／ｍｉｎ 条件下,发酵液酶活力高达３３０ｕ／ｍ Ｌ。酶的最适反应温度和ｐＨ 分别为５０ ℃和６－０ ,低于５０ ℃,ｐＨ５ ．０ ～７ ．０ 酶稳定。Ｆｅ^３＋ 、Ａｌ^３＋ 、ＥＤＴＡ、Ｈｇ^２＋ 对酶有抑制作用,而Ｂａ^２＋ 、Ｍｎ^２＋ 对酶有激活作用。发酵粗酶液对苎麻精干麻精练,显示对精干麻的半纤维素残胶具有降解作用。     

金线莲一促生真菌原生质体制备和再生研究

从药用植物内生真菌中筛选到对植物生长有显著促进作用的粘帚霉属的一种真菌（Ｇｌｉｏｃｌａｄｉｕｍｓｐ.简称Ｙ菌）,以它为出发菌株,进行原生质体制备与再生条件的研究。将培养４８ｈ的Ｙ菌菌丝体经过巯基乙醇处理３０ｍｉｎ,并用１％的纤维素酶和溶壁酶混合液于２８℃酶解３ｈ,原生质体得率可达２．１４Ｘ１０^７个／ｍＬ,在含０.５Ｍ的甘露醇为稳渗剂的再生培养基上,其原生质体的再生率可达３．８６ｘ１０^４。     

灵芝原生质体分离与再生研究

首次详细,系统地探讨了灵芝原生质体分离与再生的条件,结果表明,用０．６ｍｏｌ／Ｌ甘露醇配制成含２％溶壁酶和０．５％崩溃酶的复合醇,在３０℃,ｐＨ为６．０时酶解３小时,可得到最高的原生质体得率,但考虑到原生质体的再生,以酶解２．５小时为最适。     

向日葵下胚轴原生质体高频率愈伤组织形成与根发生

向日葵籽苗下胚轴原生质体,培养在含有ＢＡ０．５ｍｇ／Ｌ,２,４－Ｄ０．５ｍｇ／Ｌ,ＮＡＡ０．１ｍｇ／Ｌ和葡萄糖０．５５ｍｇ／Ｌ的改良Ｋａｏ培养基中,２４～２８ｈ后,原生质体开始分裂。包埋在琼脂糖０．６％中的原生质体,培养５ｄ后,分裂频率达９５％以上。生长旺盛的小愈伤组织转移到含有２ｉｐ０．１ｍｇ／Ｌ,ＩＡＡ０．０１ｍｇ／Ｌ,腺嘌呤４０ｍｇ／Ｌ和ＧＡ３０．０１ｍｇ／Ｌ的Ｔｈｏｍｐｓｏｎ液体培养基上１３ｄ后,原生质体诱导的少数愈伤组织发生根分化。     

面包酵母原生质体的制备、再生及紫外线诱变的初步研究

对面包酵母原生质体制备、再生的适宜条件进行了研究,并对原生质体进行了扫描电镜紫外线诱变。结果表明：对数生长早期的细胞的形成原生质体用１％蜗牛酶＋０．１％β－疏基乙醇酶解６０ｍｉｎ、９０ｍｉｎ,原生质体的形成率地生率分别为４．３１％和０．４％,用０．６ｍｏｌ／Ｌ甘露醇作渗稳地,原生质体的于生效果最佳,０．５ｍｏｌ／Ｌ蔗糖次之。电镜观察表明酵母菌的细胞壁是逐步被降解的。通过紫外线诱变原生质体获得了１株     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.