玉米根尖细胞染色体G带诱导

本研究以玉米为材料,采用放线菌素 D(AMD)前处理,防止染色体过度收缩;利用气干片技术,洗脱染色质,使染色体分散良好;应用稍加改良的Seabright 法,Utakoji法及醋酸地衣红技术处理染色体,都诱导出染色体的横纹带。其图象与哺乳动物的染色体 G 带相似,每条染色体均显示带纹,带纹分布于整条染色体,并且从同一细胞取得玉米染色体 G 带核型照片。     

大麦染色体G带技术的探索

染色体G带技术在细胞遗传学中已得到了广泛应用,它推动了人类细胞遗传学在近几年中的迅速发展。可是,在植物方面染色体分带技术的应用价值却很有限,因为它仅能显示C, N及Q带。这些带纹在每条植物染色体上数量太少,且多数集中在染色体端粒、副溢痕和着丝粒附近。为此,突破G带技术已成为植物染色体分带研究的当务之急。     

大麦染色体G带技术的探索

染色体G带技术在细胞遗传学中已得到了广泛应用,它推动了人类细胞遗传学在近几年中的迅速发展。可是,在植物方面染色体分带技术的应用价值却很有限,因为它仅能显示C、N及Q带。这些带纹在每条植物染色体上数量太     

孟氏裂头绦虫染色体G分带和G带定量分析

本文应用胰酶法对孟氏裂头绦虫染色体作G分带研究,获得比较清晰的G带带纹。并运用显微分 光光度计对G带带纹进行了扫描定量分析。     

植物染色体G带及螺旋的研究

本文报道了采用胰酶,尿素,SDS和NaOH原位诱导黑麦,小麦和蚕豆染色体G带和螺旋的结果,所得的G带带纹众多,分布于整个染色体上,带纹数目与染色体收缩程度相关,个别细胞的同源染色体带纹可以配对,一些晚前期染色体的带纹已达高分辨水平,G显带处理时间过长,染色体螺旋结构往往被诱导出来,螺纹数与染色体收缩程序有关,螺旋方向具有多样性,本文还首次报道了植物染色体G带到螺旋的转化现象,在光镜下显G带的染色体在扫描电镜下呈现出螺旋的特征,作者还对植物染色体G带与螺旋的关系作了初步的讨论。     

恙螨染色体分带的初步研究

本文报道应用胰酶法对微红纤恙螨Leptotrombidium rubellum,苍白纤恙螨L. pallidum和小板纤恙满L. scutellarc进行G带带型分析.三种恙螨染色体分别显示17、21、19条深带带纹,用CS-190机对每条显带的染色体进行薄层扫描,结果每一条深带显示一个峰,对微红纤螨和巨螯齿恙螨Odontaearus majestivus进行BSG法的C显带实验,均未见到带纹,从C带结果及对敬红纤慧螨染色体扫描电镜的初步观察结果,提示恙螨染色体可能为泛着丝粒类型,本文根据恙螨染色体的分带情况,探讨了几种恙螨间的亲缘关系以及恙螨染色体的研究在分类上的意义.     

植物染色体G带及螺旋的研究

本文报道了采用胰酶,尿素,SDS和NaOH原位诱导黑麦,小麦和蚕豆染色体G带和螺旋的结果,所得的G带带纹众多,分布于整个染色体上,带纹数目与染色体收缩程度相关,个别细胞的同源染色体带纹可以配对,一些晚前期染色体的带纹已达高分辨水平,G显带处理时间过长,染色体螺旋结构往往被诱导出来,螺纹数与染色体收缩程序有关,螺旋方向具有多样性,本文还首次报道了植物染色体G带到螺旋的转化现象,在光镜下显G带的染色体在扫描电镜下呈现出螺旋的特征,作者还对植物染色体G带与螺旋的关系作了初步的讨论。     

人(Homo sapiens)、金丝猴(Rhinopithecus roxellanae)和恒河猴(Macaca mulatta)染色体同源性的初步比较

本研究通过外周血淋巴细胞的微量血培养方法,制备染色体标本;同时又采用T—G分带技术使染色体显出T—G带。比较分析人、金丝猴和恒河猴的T—G带染色体。结果表明:同种的不同细胞每号同源染色体的带纹和带型是相同的。从不同物种之间的,进行了分析的T—G带染色体的比较结果来看,大多数染色体的带纹和带型都属于部分相似;只有少数染色体的带纹和带型是高度相似的。     

节节麦细胞不同分裂时期和阶段的G-带核型及其变动性分析

采用改良的ASG法获得了中期和3个染色体凝缩程度不同的早中期阶段(分别称为早中期Ⅰ、Ⅱ、Ⅲ)染色体的G_带,并进行了G_带核型和变动性分析。所分析的分裂时期和阶段,每条染色体的全长显示出了密切邻近的多重的带纹,带纹细窄、大小较相近,带间区小,带纹分布较密集而均匀。随着有丝分裂进程推进,染色体的带纹数目减少,早中期Ⅰ、Ⅱ、Ⅲ至中期单倍染色体组的G_带带纹总数分别减少41%、36%、28%,而染色体组的绝对长度分别缩短43%、37%、27%,带数减少幅度与染色体长度缩短的幅度几乎相等。早中期Ⅰ至早中期Ⅱ、Ⅲ和早中期Ⅱ至早中期Ⅲ的带纹减少幅度与染色体长度缩短幅度也基本一致。染色体组中各染色体之间带纹减少和染色体缩短的比例不尽相同,有一定的变幅。早中期Ⅰ、Ⅱ、Ⅲ和中期染色体组中每单位绝对长度的带数(带/μm)分别为2.19、2.22、2.32和2.29,差异不大。对节节麦G_带的特性等问题进行了讨论。     

节节麦细胞不同分裂时期和阶段的G—带核型及其变动性分析

采用改良的ASG法获得了中期和3个染色体凝缩程度不同的早中期阶段（分别称为早中期Ⅰ、Ⅱ、Ⅲ）染色体的G-带,并进行了G-带核型和变动性分析。所分析的分裂时期和阶段,每条染色体的全长显示出了密切邻近的多重的带纹,带纹细窄、大小较相近,带间区小,带纹分布较密集而均匀。随着有丝分裂进程推进,染色体的带纹数目减少,早中期Ⅰ、Ⅱ、Ⅲ于中期单倍染色体组的G-带带纹总数分别减少41%、36%、28%,而染色体组的绝对长度分别缩短43%、37%、27%,带数减少幅度与染色体长度缩短的幅度几乎相等。早中期Ⅰ至早中期Ⅱ、Ⅲ和早中期Ⅱ至早中期Ⅲ的带纹减少幅度与染色体长度缩短幅度也基本一致。染色体组中各染色体之间带纹减少和染色体缩短的比例不尽相同,有一定的变幅。早中期Ⅰ、Ⅱ、Ⅲ和中期染色体组中每单位绝对长度的带数（带/μm）分别为2.19、2.22、2.32和2.29,差异不大。对节节麦G-带的特性等问题进行了讨论。     

一串红染色体制片技术优化与计数

以一串红商品种‘展望红’萌发种子根尖、幼苗茎尖生长点以及嫩叶为实验材料,利用常规压片法比较不同材料、不同预处理液及预处理时间对一串红染色体制片的影响,探索实验预处理条件。然后利用去壁低渗法对一串红4个商品种和一串红株型突变体及其野生型进行染色体计数。实验结果显示:以一串红萌发种子的根尖为实验材料,用0.002 mol/L 8-羟基喹啉预处理3~4 h压片所得染色体效果最好;分别观察6个供试品种(系)分散良好、清晰的30个分裂相细胞,86.7%及以上的细胞染色体数目为2n=44。研究表明,一串红株型突变体与野生型及4个商品种在染色体数目上没有差异。     

Chromosome micromanipulation

The relationship of kinetochore orientation and reorientation to orderly chromosome distribution in anaphase has been studied experimentally by micromanipulation of living grasshopper spermatocytes. Bivalents or the X chromosome at prometaphase or metaphase I can be detached from the spindle with a microneedle and moved to any desired location within the cell. Following a pause of variable duration the detached chromosome invariably moved, kinetochores foremost, back to the spindle, reassumed its characteristic metaphase position, and, with one exception, segregated normally at anaphase I. Detachment from the spindle is demonstrated unequivocally (1) by manipulation evidence for the absence of the firm spindle connections seen both before detachment and after reattachment and (2) by a functional criterion: a given kinetochore, oriented to one pole before detachment, often orients to the opposite pole after detachment. The segregation in anaphase was always as expected from the final, post-operation, orientation. Reorientation and prometaphase and anaphase movement after detachment cannot be distinguished from their counterparts in control cells. Kinetochore position after detachment is the primary determinant of the pole to which that kinetochore will orient. Therefore, since the experimenter determines kinetochore position, he can cause any given half-bivalent to segregate to a predetermined pole at anaphase I. Similarly, orientation of both half-bivalents to the same pole can be induced. These mal-oriented bivalents invariably reorient and normal anaphase segregation ensues. Non-disjunction can, however, be produced directly in late anaphase. These experiments are based upon current views of orderly chromosome distribution; their success confirms our understanding of the fundamental orientation process.     

Chromosome micromanipulation

Two types of unusual motion within the spindle have heen studied in a grasshopper (Melanoplus differentialis) spermatocyte. The first is the motion of granules placed by micromanipulation within the normally granule-free spindle. The most specific motions are poleward, approximate the speed of the chromosomes in anaphase, and occur in the area between the kinetochores and the nearer pole during both metaphase and anaphase. Exactly the same transport properties were earlier observed by Bajer inHaemanthus endosperm spindles. The absence of significant motion in the interzone between the separating chromosomes at anaphase has been unequivocally demonstrated inMelanoplus spermatocytes. Thus very specific motion of non-kinetochoric materials is probably a general spindle capability which would much restrict admissible models of mitotic force production,if the same forces move both granules and chromosomes. The second unusual motion is seen following chromosome detachment from the spindle by micromanipulation during anaphase. These tend to move toNearer pole rather than to the pole the chromosome's kinetochoresFace. The latter preference was earlier demonstrated after detachment during prometaphase or metaphase and has been confirmed without exception in the present studies. The apparent preference for motion to the nearer pole in anaphase provides the first evidence for poleward forces within each half-spindle which cannot be entirely specified by the chromosomal spindle fibers. Almost certainly these would be the usual forces responsible for chromosome motion since they act specifically at the kinetochores of detached chromosomes. This evidence requires interpretation, however because additional factors influence chromosome motion following detachment at anaphase. On thesimplest interpretation, certain current models of mitosis clearly are not satisfactory and others are favored.