对一个玉米双重标记新突变基因（os）的染色体定位和初步遗传研究

利用一套１６个玉米Ｂ－Ａ染色体易位的系列材料,和一套１１个由ｗｘ基因标记易位断点的第９染色体相互易位材料,测定了一个新发现的玉米隐性突变基因ｏｓ（ｏｐａｑｕｅ－ｓｍａｌｌ ｇｅｒｍ）所属的染色体。两个结果相互印证,证明该基因位于第２染色体短壁。ｏｓ基因具有产生不透明胚乳和小胚面的双重遗传效应,是一个良好的遗传标记。这一特性有可能来检查异雄核受精或定向受精的存在和比数。ｏｓ基因除缩小种胚体积之外,也     

天兰冰草染色体对小冰麦外植体再生能力的影响及基因的染色体定位

本文研究了天兰冰草（Ａｇｒｏｐｙｒｏｎｉｎｔｅｒｍｅｄｉｕｍ２ｎ＝４２）染色体导入小麦后对小冰麦外植体再生能力的影响,从而分析调控再生能力的基因所在天兰冰草染色体的定位。对异源八倍体小冰麦的研究表明,与天兰冰草强再生能力有关的基因主要分布在附加到中２的冰草染色体组上;对７个异附加系小冰麦的研究进一步表明,冰草强再生能力的性状由多基因调控,这些基因主要分布在附加到ＴＡＩ－１１、ＴＡＩ－１２、ＴＡＩ－１３的冰草染色体上。此外,小冰麦杂种Ｆ１的研究表明,在组织培养中同样能够表现出杂种优势。     

Davydov Soliton Dynamics in Proteins: II. The General Case

We performed long time simulations using the |D₁> approximation for the solution of the Davydov Hamiltonian. In addition we computed expectation values of the relevant operators with the state (_D/J)|D₁> and the deviation |> from the exact solution over long times, namely 10 ns. We found that in the very long time scale the |D₁> ansatz is very close to an exact solution, showing expectation values of the relevant physical observables in the state (_D/J)|D₁> being about 5-6 orders of magnitudes larger than in the deviation state |>. In the intermediate time scale of the ps range such errors, as known from our previous work, are somewhat larger, but still more or less negligibly. Thus we also report results from an investigation of the very short time (in the range 0-0.4 ps) behaviour of the |D₁> state compared with that of an expansion of the exact solution in powers of time t. This expansion is reliable for about 0.12 ps for special cases as shown in the previous paper. However, the accuracy of the exactly known value of the norm and the expectation value of the Hamiltonian finally indicates up to what time a given expansion is valid, as also shown in the preceding paper. The comparison of the expectation values of the operators representing the relevant physical observables, formed with the third order wave function and with the corresponding results of |D₁> simulations has shown, that our expansion is valid up to a time of roughly 0.10-0.15 ps. Within this time the second and third order corrections turned out to be not very important. This is due to the fact that our first order state contains already some terms of the expansion, summed up to inifinite order. Further we found good agreement of the results obtained with our expansion and those from the corresponding |D₁> simulations within the time of about 0.10 ps. At later times, the factors with explicit powers of t in second and third order become dominant, making the expansion meaningless. Possibilities for the use of such expansions for larger times are described. Alltogether we have shown (together with previous work on medium times), that the |D₁> state, although of approximative nature, is very close to an exact solution of the Davydov model on time scales from some femtoseconds up to nanoseconds. Especially the very small time region is of importance, because in this time a possible soliton formation from the initial excitation would start.     

一例智力低下患者7q~ 标记染色体的来源鉴定

以人类染色体显微切割、PCR技术构建的现有人类染色体特异性和染色体区带特异性探针池作为绘画探针,采用正向染色体绘画技术,结合染色体筛查方法,查明了一例7q~ 标记染色体患者的染色体附加片段来源于3q26→3qter。确定该患者的核型为46,XX,-7, der(7)t(7;3)(7pter→7q32::3q26→3qter)。应用这个策略,能够快速有效地鉴定标记染色体的来源。     

大麦G－带变动性以及与染色粒的一致性分析

以大麦为材料,进行了Ｇ－带带纹变动性分析以及Ｇ－带与减数分裂粗线期染色粒的比较。有丝分裂早中期至中期两个不同时期Ｇ－带带纹总数减少３６％,染色体组的绝对长度缩短２５％,带数减少的幅度大于染色体长度缩短的幅度。染色体组中每条染色体之间带纹减少的比例不尽相同,变幅在０．２９－０．５０之间。不同染色体绝对长度减少的幅度在０．２７－３．７０μ之间。从早中期至中期,每单位染色体绝对长度带数具相对减少的趋势。选择第６染色体进行的比较显示,减数分裂的染色粒与有丝分裂的Ｇ－带带纹之间具有很好的对应关系,Ｇ－带带纹和染色粒间的数目、位置和着色程度上都具一致性。对Ｇ－带性质和植物中Ｇ－带的应用等问题进行了讨论。     

Investigations of peptide hydration using NMR and molecular dynamics simulations: A study of effects of water on the conformation and dynamics of antamanide

Summary The influence of water binding on the conformational dynamics of the cyclic decapeptide antamanide dissolved in the model lipophilic environment chloroform is investigated by NMR relaxation measurements. The water-peptide complex has a lifetime of 35 s at 250 K, which is longer than typical lifetimes of water-peptide complexes reported in aqueous solution. In addition, there is a rapid intracomplex mobility that probably involves librational motions of the bound water or water molecules hopping between different binding sites. Water binding restricts the flexibility of antamanide. The experimental findings are compared with GROMOS molecular dynamics simulations of antamanide with up to eight bound water molecules. Within the simulation time of 600 ps, no water molecule leaves the complex. Additionally, the simulations show a reduced flexibility for the complex in comparison with uncomplexed antamanide. Thus, there is a qualitative agreement between the experimental NMR results and the computer simulations.     

染色体研究的进展与植物分类学(下)

染色体研究的进展与植物分类学（下）徐炳声,张芝玉,陈家宽,洪德元（中国科学院植物研究所系统与进化植物学开放研究实验室北京１０００９３）（上海第二军医大学药学院上海２００４３３）（武汉大学生命科学学院武汉４３００７２）ＡＤＶＡＮＣＥＳＩＮＣＨＲＯＭＯＳ...     

迷宫漏斗蛛Agelena labyrinthica的染色体(蜘蛛目:漏斗蛛科)

报告迷宫漏斗蛛的染色体数目、形态结构和性染色体组成。结果表明,迷宫漏斗蛛体细胞染色体数目是:雄性2n=42,雌性2n=44,性别决定机制属X_1X_2O型。X染色体是全部染色体中最长的和最短的2个(对)。染色体似乎均为端或亚端着丝粒染色体,这由C-显带标本分析所证实,没有亚中着丝粒染色体的证据。C-带标本分析表明,常染色体中,各条染色体的C-带纹,其大小和染色深浅无明显差异,但X_2染色体上有明显宽的C-带纹。C-显带处理没有得到稳定的有重复性的带纹。     

Induction of Blocks in Nuclear Divisions and Overcondensation of Meiotic Chromosomes with Cycloheximide During Conjugation of Tetrahymena thermophila

During conjugation, the micronucleus of Tetrahymena thermophila undergoes five consecutive nuclear divisions: meiosis, third prezygotic division (pregamic mitosis) and two postzygotic mitoses of the synkaryon. The four products of the synkaryon differentiate into macronuclear anlagen and new micronuclei and the old macronucleus is resorbed. The protein synthesis inhibitor cycloheximide, applied during conjugation, induced several developmental blocks. Pairs shifted to the drug during early meiotic prophase (stages I–III) were arrested at prophase. Cycloheximide applied to cells at pachytene (stages IV-VI) to metaphase arrested the conjugants at the stage of modified prometaphase/metaphase with overcondensed, swollen bivalents. In contrast to other systems, in the presence of cycloheximide, separation of chromatids, decondensation of chromosomes and exit from metaphase I were inhibited in both diploid and haploid cells. Pairs shifted to the drug after metaphase I were arrested at postmeiotic interphase after completing one nuclear cycle. The same rule applied to the subsequent cycle; then cells were arrested at the stage of pronuclei, and those pairs with functional pronuclei and synkarya were arrested at the stage of two products of the first postzygotic division (pronuclei were not arrested in nuclear transfer and karyogamy). Only pairs with two products of the first postzygotic division were arrested at the same stage after the cycloheximide treatment. Pairs shifted to cycloheximide during the second postzygotic division were arrested in development of macronuclear anlagen and resorption of old macronuclei. The postmeiotic conjugants pulse-treated with cycloheximide (2 h) yielded heterokaryons retaining parental macronuclei (i.e. they exhibited macronuclear retention).     

Chromosome translocations in wild populations of tetraploid emmer wheat in Israel and Turkey

Translocation frequencies (as compared to the standard chromosome arrangement typified by that in Chinese Spring) in 9 or more genotypes from each of 15 populations of Triticum dicoccoides in Israel were determined. Data also were obtained from 2 genotypes of the southernmost population (Jaba). A single population from Turkey was also investigated. There were 119 genotypes with translocations in the sample of 171 genotypes investigated (70%). The frequency of translocations in different populations varied from 0.27 to 1.00, and all populations had 1 or more genotypes with one or more translocations. Some populations such as Qazrin appeared to be homogeneous for translocations, but most populations were heterogeneous. A sample of 17 genotypes from 12 of the populations were crossed with the Langdon D-genome disomic substitutions to determine the identity of the chromosomes involved in the translocations. There were nine genotypes with translocations and with the exception of a 2A/2B translocation, none of them involved the same chromosomes. The B-genome chromosomes were involved in translocations more frequently than the A-genome chromosomes. Translocation frequencies (TF) of the various populations were correlated with environmental variables, primarily with water availability and humidity, and possibly also with soil type. In general, TF was higher in peripheral populations in the ecologically heterogeneous frontiers of species distribution than in the central populations located in the catchment area of the upper Jordan valley.