三种野生和四个栽培棉种的核型研究

作者对棉属 D 组的瑟伯氏棉(Gossypium thurberi)、戴维逊氏棉(C.davidsonii)、雷蒙德氏棉(G.raimondii)、A 组的草棉(G.herbaceum)、中棉(G.arboreum)、AD 组的陆地棉(G.htrsutum)和海岛棉(C.barbadense)等7个种的核型进行了研究。各个种的核型可简式为:瑟伯氏棉2n=2x=26=24m 2Sm(2SAT);戴维逊氏棉20=2x=26=20m 6Sm(4SAT);雷蒙德氏棉2n=2x=26=20m 6Sm(2SAT);草棉2n=2x=26=18m 4Sm 4St(4SAT);中棉2n=2x=26=18m 6Sm(2SAT) 2St(2SAT);陆地棉2n=4x=52=32m 18Sm(4SAT) 2St(2SAT);海岛棉20=4x=52=38m 12Sm(2SAT) 2St(2SAT)。此外,作者对四倍体种的 A 组和 D 组的供体问题进行了讨论。     

东北地区小麦族11种植物的核型报道

本文对中国东北地区小麦族11种植物的核型进行了研究。 结果如下：冰草2n=4x=28=20m +8sm;偃麦草2n=6x=42=34m(2SAT)+8sm;短芒大麦草2n=4x=28=20m+8sm(4SAT);吉林 鹅观草2n=4x=28=20m+8sm(4SAT);大芒鹅观草2n=4x=28=20m(2SAT)+8sm(2SAT);老芒 麦2n=4x=28=20m+8sm(4SAT); 披碱草2n=6x=42=32m+10sm(6SAT); 肥披碱草 2n=6x=42=32m+10sm(6SAT);羊草2n=4x=28=20m(4SAT)+8sm;纤毛鹅观草2n=4x=28= 22m(2SAT)+6sm(2SAT);鹅观草2n=6x=42=30m+12sm(4SAT);其中前5种的核型为首次报道。     

仙茅属三个国产种的核型研究

本文报道了中国产三种仙茅植物的核型。1.绒叶仙茅Curculigo crassifolia (Baker) Hook. f., 2n=2x=18=10m(4SAT) 8 sm;2.大叶仙茅C.capitulata(Lour.)O. Kuntze,2n=2x=18=10(2SAT) 8sm;3.中华仙茅C.sinensis S.C.Chen,2n=2x=18=8m(3SAT) 10sm(2SAT)。其中中华仙茅的核型为首次报道。虽然三种仙茅的核型都是“2B”型,但中华仙茅的核型不对称性比绒叶仙茅和大叶仙茅强。     

云南淡黄花百合10居群核型研究

对云南淡黄花百合 10个居群核型进行了研究 ,结果如下 :普洱居群 2n =2x =2 4 =4m(4SAT ) 8st (1SAT ) 12t;大湾居群 2n =2x =2 4 =4m (4SAT ) 4sm (1SAT ) 6st 10t ;宝山居群 2n =2x =2 4 =4m (4SAT ) 4st (1SAT ) 16t ;元阳居群 2n =2x =2 4 =4m (4SAT ) 8st(1SAT ) 12t;玉屏山居群 2n =2x =2 4 =4m (4SAT ) 4sm (1SAT ) 12st 4t;易门居群 2n =2x =2 4 =4m (4SAT ) 2sm 14st (1SAT ) 4t ;峨山居群 2n =2x =2 4 =4m (4SAT ) 2sm 14st(1SAT ) 4t;老鹰地居群 2n =2x =4m (4SAT ) 2sm 14st (1SAT ) 4t;双柏居群 2n =2x =2 4 =4m (4SAT ) 12st (1SAT ) 8t;牟定居群 2n =2x =2 4 =4m (4SAT ) 8st (1SAT ) 12t。研究表明各居群的核型都属于Stebbins的 3B型 ,不同居群间存在染色体类型和随体染色体的多型性 ,同时还发现了B染色体和 4倍体染色体数目变异 ,本文最后讨论了云南淡黄花百合种内居群间核型分化的原因。     

辽宁地区产6种乌头(Aconitum)的细胞分类学研究

对我国辽宁地区毛莨科(Ranunculaceae)乌头属(Aconitum) 6个种的染色体的数目和形态进行了研究,并进行了核型分析。其染色体基数为X=8,核型公式为:两色乌头:2n=2x=2m+10sm+4st;蛇岛乌头为:2n=4x=10m+20sm(SAT)+2st+2B;黄花乌头为:2n=4x=4m+12sm(SAT)+8st+1B;北乌头三倍体为:2n=3x=2M+4m+18sm;北乌头4倍体为2n=4x=4m+28sm。同时,对乌头属下某些种的分类学问题进行了探讨。     

六种犁头属植物（天南星科）的核型研究

报道了6种8个居群犁头尖属（Typhonium Schott）植物的核型,其结果如下：（1）独角莲（T.gigan-teum）北京居群2n＝4x=52=44m 7sm 1st;（2）鞭檐犁头（T.flagelliforme）金平居群2n=3x=24=3m 9sm(4SAT) 12st,河内居群2n＝4x=32=7m 20st 4sm 1t;（3）单籽犁头（T.calcicolum)西畴居群2n=4x=52=21sm 23m(5SAT) 8st;（4）犁头尖（T.blumei）重庆居群2n=4x=52=40m(1SAT) 12sm(3SAT);(5)马蹄犁头（T.roxburgii）个旧居群2n＝2x=18=8sm 10m(2SAT)。其中鞭檐犁头尖2n=24、32,金慈菇2n＝28均为首次报道,同时分析讨论了本属植物染色体基数和倍性的多样性及其可能的原始基数。     

四种野生百合核型分析

对南川百合(Lilium rosthornii Diels)、青岛百合(L.tsingtauense Gilg)、山丹(L.pumilum DC.)和岷江百合(L.regaleWilson)等4种野生百合进行了染色体数目观察和核型分析。结果表明,核型除山丹为3A外,其余3种材料核型均为3B。核型公式分别为:南川百合2n=2x=24=4m(4SAT)+2sm+6st+12t;青岛百合2n=2x=24=8m(4SAT)+2sm(2SAT)+14t;山丹2n=2x=24=2m(2SAT)+6sm(2SAT)+4st(4SAT)+12t;岷江百合2n=2x=24=2m(2SAT)+2sm+6st+14t。核型不对称系数分别是81.68%、76.09%、80.34%和82.26%。其中,南川百合和青岛百合为国内首次报道。     

桤木属7种植物的核型分析

利用改良去壁低渗法对分布于欧美地区的桦木科(Betulaceae)桤木属(Alnus Mill.)7种植物进行染色体数目与核型分析。结果显示:所有材料染色体形态比较一致,多为由中部(m)及近中部(sm)着丝点染色体组成。意大利桤木(A.cordata)为六倍体,体细胞染色体数为2n=6x=42,核型公式为2n=6x=42=36m+6sm;绿桤木(A.viridis)为八倍体,体细胞染色体数为2n=8x=56,核型公式为2n=8x=56=46m+10sm(SAT);薄叶桤木(A.tenuifolia)、灰桤木(A.incana)、欧洲桤木(A.glutinosa)、裂叶桤木(A.sinuata)和红桤木(A.rubra)均为四倍体,体细胞染色体数均为2n=4x=28,其核型公式分别为2n=4x=28=16m(1SAT)+12sm、2n=4x=28=22m+6sm、2n=4x=28=24m+4sm、2n=4x=28=24m+4sm、2n=4x=28=26m+2sm。其中红桤木(A.rubra)的核型属于1B型,其余均为2B型。     

葱属植物物种生物学研究：Ⅰ.葱属6种材料的核型研究

分析了葱属(Allium L.)5个种6个居群的细胞学特征。这些种是太白韭(A.prattii C.H.Wright apud Forb.et Hemsl.),该种包括两个居群(Ⅰ、Ⅱ)。居群Ⅰ:K(2n)=2x=16=9m+1m(SAT)+4sm+2st,居群Ⅱ:K(2n)=2x=16=10m+5sm+1sm(SAT);天蒜(A.PaePalanthoides Airy-Shaw):K(2n)=2x=16=14m+2sm+3B;多叶韭(A.Plurifoliatum Rendle):K(2n)=2x=16=14m+2sm+1B;合被韭(A.tubiflorum Rendle):K(2n)=2x=16=12m+2m(SAT)+2sm;峨眉韭(A.omeiense Z.Y.Zhu):K(2n)=2x=22=2m+18sm+2T(SAT)。所研究的6批材料均为二倍体,除合被韭的核型为“1A”型,蛾眉韭的核型为“3A”型外,其余4批材料的核型均为“2A”型。其中峨眉韭和多叶韭的染色体数目为首次报道,天蒜和多叶韭的细胞中首次发现B染色体,并对其相互关系进行了探讨。     

我国11种披碱草的核型研究

本文报道了中国产的11种披碱草属植物的核型,其中9种为首次报道。结果如下:老芒麦2n=4x=28=24m+4sm(2SAT);披碱草2n=6x=42=36m(2SAT)+6sm(4SAT);青紫披碱草2n=6x=42=32m+10sm(4SAT);垂穗披碱草2n=6x=42=34m+8sm(2SAT);圆柱披碱草2n=6x=42=32m+10sm(2SAT);短芒披碱草2n=6x=42=30m+12sm(4SAT);黑紫披碱草2n=6x=42=36m(6SAT)_1+6sm;毛披碱草2n=6x=42=30m+12sm(6SAT);紫芒披碱草2n=6x=42=22m=12sm(2SAT)+8st(4SAT);肥披碱草2n=6x=42=34m(2SAT)+6sm(4SAT)+2st;麦(?)草2n=6x=42=30m(4SAT)+12sm(2SAT)。     

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.