辐照外源DNA导入番茄研究——D1、D2代分析

辐照外源DNA导入番茄后,供体叶形不但在D1代上得到表达,而且能遗传到D2代。并且在D1代,其果形、果实大小以及Vc含量等都有明显变化。为验证该技术的效果和重复性,又进行了第二期辐照外源DNA导入番茄试验,发现在D1代幼苗中,供体的显性基因正常叶形,仍有一定的几率在受体中得到表达。结果与第一期试验相同。野生种番茄DNA龙辐照作供体导入后,也获得了野生种叶形在受体中得到表达的D1代植株,说明辐照外源DNA导入番茄技术效果好,重复性好,便于进行远缘杂交。     

辐照外源DNA导入番茄研究——D_1、D_2代分析

辐照外源DNA导入番茄后 ,供体叶形不但在D1 代上得到表达 ,而且能遗传到D2 代。并且在D1 代 ,其果形、果实大小以及VC 含量等都有明显变化。为验证该技术的效果和重复性 ,又进行了第二期辐照外源DNA导入番茄试验 ,发现在D1 代幼苗中 ,供体的显性基因正常叶形 ,仍有一定的几率在受体中得到表达 ,结果与第一期试验相同。野生种番茄DNA经辐照作供体导入后 ,也获得了野生种叶形在受体中得到表达的D1 代植株。说明辐照外源DNA导入番茄技术效果好 ,重复性好 ,便于进行远缘杂交。     

玉米转座因子Ac／Ds导入水稻花药悬浮细胞并再生成植株

使用电激法将分别含玉米转座因子ＡＣ或Ｄｓ因子的质粒ＤＮＡ同时导入水稻花药悬浮系细胞团,得到转化抗性意伤组织,并分化成可育植株。对一些植株的ＤＮＡ进行了Ｓｏｕｔｈｅｒｎ分析和ＰＣ且扩增,发现导入的外源ＤＮＡ已整合到了水稻染色体上而且Ｄｓ因子已发生了转座。抗性测定表明转化植株Ｆ１代和Ｆ２代种子中的大多数仍有Ｄｓ因子存在。     

玉米转座因子Ac／Ds导入水稻花药悬浮细胞并再生成植株

使用电激法将分别含玉米转座因子Ａｃ或Ｄｓ因子的质粒ＤＮＡ同时导入水稻花药悬浮系细胞团,得到转化抗性愈伤组织,并分化成可育植株。对一些植株的ＤＮＡ进行了Ｓｏｕｔｈｅｒｎ分析和ＰＣＲ扩增,发现导入的外源ＤＮＡ已整合到了水稻染色体上而且Ｄｓ因子已发生了转座。抗性测定表明转化植株Ｆ１代和Ｆ２代种子中的大多数仍有Ｄｓ因子存在。     

热带高梁外源DNA导入寒带高梁引起变异的研究

本文报道了高梁自花授粉后,利用其形成的花粉管通道,将热带高梁外源ＤＮＡ直接导人寒带高梁的结果。由实验结果看出：导入后代的变异主要表现在单穗粒重、茎粗、株高、穗型、壳色等方面。变异的Ｄ２代单株的过氧化物酶及酯酶同工酶酶谱显示了明显的差异。实验结果表明：外源ＤＮＡ片段直接导入受体植物卵细胞、合子或早期胚细胞,部分片段可以被受体细胞ＤＮＡ整合和表达。表明了利用花粉管通道途径来实现外源ＤＮＡ直接导入高梁,进行高梁的种质创新和品质改良是可能的。     

利用嵌合RNA：DNA寡聚核苷酸进行核酸序列突变

动物中内源基因的单核苷酸突变可以引起多种单基因疾病。传统的基因疗法大多利用外源基因的导入 ,由于转基因的效率和外源基因表达上存在问题 ,这种基因疗法有一定的局限性。本文介绍的利用嵌合ＲＮＡ :ＤＮＡ寡聚核苷酸 (ＲＤＯ)在ＤＮＡ水平上对突变基因进行修复是一种新的基因疗法。这种基因疗法同样适用于植物 ,并且在植物功能基因组的理论研究中有重要作用。1　嵌合ＲＮＡ :ＤＮＡ寡聚核苷酸 (ＲＤＯ)的分子结构ＲＤＯ有一段五碱基长的ＤＮＡ序列 ,除了突变的位点以外 ,与靶基因互补。五碱基的ＤＮＡ序列两旁各有 1 0个 2’ -Ｏ -甲基…     

经大豆DNA溶液处理的水稻后代种子的粗蛋白的氨基酸含量分？…

以大豆为外源ＤＮＡ供体,用浸种及幼苗期浇灌法和花粉管通道法直接将大豆总ＤＮＡ导入受体水稻,经常规栽培获得水稻后代种子。采用微量凯氏定氮法和氨基酸自动分析仪进行水稻后代种子糙米的粗蛋白含量和氨基酸含量的测定。结果显示：三组经大豆ＤＮＡ溶液处理获得的水稻后代种子糙米粗蛋白平均含量分别为１６．４２％、１６．８０％和１９．８７％,与对照组相比有明显提高,统计分析都达到极显的差异（Ｐ＜０．０１）;在氨基酸     

外源DNA导入小麦引起遗传变异的验证

对由波兰小麦ＤＮＡ注射到普通小麦鄂恩１号子房获得的Ｄ５代稳定遗传变异２个转化株系的种子醇溶蛋白,进行单向和双向聚丙烯酰胺凝胶电泳分析,结果表明由外源ＤＮＡ导入获得转化株系的变异,与其种子醇溶蛋白电泳图谱出现供体的某些组分和缺少受体的某些组分相印证。     

外源DNA直接导入小麦及其在育种上的应用

本研究选用两个白粒小麦品种作供体,提取其总ＤＮＡ,采用花粉管直接携带法导入７５（１９８）红粒品种受体植株。ＤＮＡ导入的第一代（Ｄ１）,目的性状的转化频率为１．７５％和２．９４％。Ｄ２代变异率显著低于Ｄ１代。对Ｄ１,Ｄ２代所得目的性状变异后代,按照常规育种程序进行Ｄ３代观察与鉴定,得到已稳定遗传的后代,从中选取保持原品种其它优良性状而籽粒为的白色的变异类型混合脱粒,获得７５（１９８）改良新品系。     

耐盐辣椒分子育种

利用自花授粉后形成的花粉管通道将海岸耐盐植物红树总ＤＮＡ导入辣椒,其后代的耐盐性明显增强,在海滩上试种。用海水直接浇灌,约５５％的转化株能开花,结果,而对照株全部死亡。进行蛋白质ＳＤＳ－ＰＳＧＥ电泳和ＲＡＰＤ分析,分别发现一条１７．５ＫＤ蛋白质和一条１．１Ｋｂ ＤＮＡ的特异性谱带,表明通过化粉管道导入外源ＤＮＡ是可行的,其后代植株耐盐能力提高与基因组变异有关。     

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.