芦苇变异植株的细胞学鉴定

芦苇变异植株是从 EMS 处理的愈伤组织再生的。植株是混倍体·染色体数目变异范围在100—33之间。在它们的分蘖植株中,存在类似的染色体数目变异。     

芦苇耐盐变异植株及其细胞学鉴定

用甲基磺酸乙酯（ＥＭＳ）处理芦苇（Ｐｈｒａｇｍ ｉｔｅｓｃｏｍ ｍ ｕｎｉｓ Ｔｒｉｎ．）胚性愈伤组织。从处理后的愈伤组织诱导获得芦苇耐盐变异植株Ｒ５００２－１２。变异植株能在含有１％ ＮａＣｌ的ＭＳ培养基上生长。细胞学检查变异植株是混倍体,染色体数目变异范围在１００至３３ 之间。分蘖植株具有相似的形态学及染色体变异特性     

不同激素对伊贝母组织培养中染色体不稳定性的研究

伊贝母鳞茎培养在附加2,4—D、IAA、NAA和2,4—D+KT、IAA+KT、NAA+KT的MS培养基上(2,4—D、IAA、NAA1毫克/升,KT0.1毫克/升),研究了愈伤组织细胞染色体的变异及愈伤组织的分化和再生植株的染色体倍性。结果表明,2,4—D能有效地引起染色体数目的变化,当和KT结合使用时,可诱导高频率的多倍化细胞。IAA的作用次之,NAA较小。各种激素均能程度不同地引起各种类型的有丝分裂异常及染色体结构变异,其效应与对染色体数目变异的影响呈现明显的一致性。研究还得出,染色体的整倍性是愈伤组织得以分化的重要因素,所以再生植株主要是二倍体,也有少量的四倍体,混倍体仅占少数。根据实验结果,对染色体变异的原因以及染色体数目变异与愈伤组织分化的关系进行了讨论。     

起源于籼稻体细胞培养的联会消失变异的细胞遗传学研究

对表现不育的体细胞培养再生植株作减数分裂细胞遗传学分析发现,一株由IR54幼穗外植体起源的不育株(二倍体)为部分联会消失变异。其减数分裂早前期染色体配对正常,在终变期及中期Ⅰ观察到了数目不等的单价染色体,后期Ⅰ出现各种数目的落后染色体。由于减数分裂时染色体不平衡而导致该再生植株不育。     

不定胚再生植株的染色体数目变异

本实验以甜瓜“小麦瓜”和“青皮绿肉”品种为试材,经不定胚诱导再生植株。分别调查了不同继代培养时间后形成再生植株的染色体数目,并将之与对照染色体数目相比较,发现通过诱导不定胚所得到的再生植株中存在着一定的变异,而且经过不同继代培养时间后,所得到的不定胚再生植株的变异程度不同,随着时间的增加,染色体数目的变异率从3.3%增加到30%,变异幅度也从2n=23~24增加到2n=13~48。从而得出结论：不定胚再生植株染色体数目变异程度随着培养时间的增加而增加;培养时间在1~2个月内所得到的不定胚再生植株的变异较少。此外,不定胚再生植株的染色体数目变异程度也因品种而异。 Abstract:Chromosomal number of different of somatic embryos regenerated plants were investigated in melon variety “xiaomaigua” and “Qingpilurou”.Certain variations of chromosomal number were found among the regenerated plants compared with normal sample,and range of variation covered from 2n=23～24 to 2n=13～48 with the increase of generation,the rate from 3.3% to 30%.The results indicated that degree of variation in chromosomal number of somatic embryos regenerated melon plants increased with the time of culture,and those cultured in one to two months had the least variation.It was also found that degree of chromosomal number variations varied with melon varieties.     

小麦再生植株的变异研究 Ⅱ.再生植株当代(R_1代)的细胞学和形态学变异

再生植株具有高频率的染色体异常,其中有20.61％表现为染色体数量变异,最常见的为2n—1类型,其次为2n—2类型,也有2n 1、2n—3个体以及染色体数嵌合株。再生植株减数分裂各期均有染色体异常行为,可以见到的有落后染色体、染色体桥、断片、二分体延迟、微核,还有粗线期十字型配对等结构变异,以及五分体、六分体和畸型四分体等异常现象。微核率随培养时间延长而增加,可用作染色体伤害的一个指标。再生植株R_1代存在着许多形态学变异。性状变异与染色体数目变异没有明显关系。     

缺体小麦与黑麦杂种幼胚愈伤组织再生植株的染色体变异

对中国春6A缺体小麦与黑麦杂种幼胚愈伤组织不同无性世代再生植株体细胞染色体鉴定结果表明,随着愈伤组织培养时间的延长,再生植株染色体变异频率及变异范围明显增加。在分化的共计224株再生植株中,发生染色体变异的植株为80株,占35.7％,其中有3株为染色体嵌合株,1株发生了染色体结构变异。     

“染色体变异”的教学组织

在新课程理念和建构主义理论的指导下,基于问题情境创设,组织了“染色体变异”一节的课堂教学,通过创设突破“染色体组”概念、辨析二倍体、多倍体、单倍体等问题情境,让学生在思考、讨论和分析、解决问题的过程中获取染色体结构变异和数目变异等方面的知识。     

植物体细胞无性系变异的分子基础

TheMoleculBasicofSomaclonalVariationinPlantsZhangChunyiYangHanmin(BiologyDepartmentofLanzhouUniversityLanzhou730000)近年来,随着植物细胞和组织培养技术的迅速发展与广泛应用,不断发现在培养细胞和再生植株中存在着各种不同的变异,其中有些是可以遗传的,这种可遗传的变异被称为体细胞无性系变异[39]．变异的发生有其遗传学基础,具体表现在显微水平上的染色体数目和结构变异与分子水平上的基因突变、碱基修饰、基因扩增或丢失、基因重排以及转座因子的激活而影响核及细胞质基因的表达等等．目前,人们在已经积累的大量有…     

小冰麦异附加系的体细胞无性系建立及其变异的研究

从7种小冰麦异附加系的幼叶和成熟胚诱导出愈伤组织,建立了体细胞无性系,获得大量试管苗,并移栽成活。实验设计了适于小冰麦异附加系组织培养的 WG 培养基。愈伤组织诱导采用二次诱导方法。第一诱导培养基为 WG_2附加4mg/1 2,4-D、1mg/1 NAA。第二诱导培养基为 WG_2附加2m//1 2,4-D、0.5mg/1 NAA,和0.25mg/1KT。分化培养基为 WG_3附加0.5mg/1 KT、1mg/1 NAA 和100mg/1 Ad。再生植株的染色体检查表明,异附加系无性系的染色体数变异明显。保持2n=44的再生植株只有34.4%,而且变异植株中回复到2n=42的植株较多。再生植株中约有1/2发生了形态变异。在变异植株的花粉母细胞中观察到染色体的交换、易位等结构变化。特别在愈伤组织细胞中观察到多条染色体融合成多着丝点染色体和体细胞的染色体交叉,说明无性系中发生了染色体的交换和易位。     

Chromosome number variation in the polyploid Cerastium alpinum-C. arcticum complex (Caryophyllaceae)

Chromosome numbers of Cerastium alpinum, C. arcticum , and C. nigrescens were studied from the main part of their distribution area. No chromosome number variation was found within C. alpinum , which seems to be octoploid throughout its range. Dodecaploid chromosome numbers (2n = 108) were found in both C. arcticum and C. nigrescens. A higher, possibly aneuploid, chromosome number was reported for plants from Southwest Greenland, and the intermediate chromosome number of 2n = 90 was found in potential hybrids between C. alpinum and C. nigrescens. Despite sporadic reports of deviating chromosome numbers, the chromosome number variation within the C. alpinum-C. arcticum complex seems to be restricted mainly to the octo- and dodecaploid levels.     

山东昆嵛山细形山地涡虫染色体组型的研究

首次报道了胶东半岛昆嵛山细形山地涡虫Phagocata vivida的形态特征,运用组织再生的方法获得中期分裂相分析了体细胞染色体组型,其2倍体细胞具有36条染色体,核型公式为:2n=2x=10m+26sm,并与产于日本的细形山地涡虫核型进行了比较,发现二者染色体数目相同,但核型参数存在一定差别.     

Morphology, cytology and taxonomic remarks of four species of Stigeoclonium (Chaetophorales, Chlorophyceae) from Argentina

Four species of Stigeoclonium from Argentina were studied by means of transmission electron microscopy and light microscopy. For species identification, we collected data related to the prostrate system and zoospore germination. We also determined the chromosome number for each species. Stigeoclonium aestivale showed a more developed erect system than the prostrate one, zoospore germination was predominantly of erect type and the chromosome number was 8. Stigeoclonium tenue presented well developed, erect and prostrate systems, zoospore germination was initially of the prostrate type and the chromosome number was 5. In Stigeoclonium variabile the prostrate system predominated over the erect one, zoospore germination was strictly of the prostrate type and the chromosome number was 3. Stigeoclonium farctum presented a more developed prostrate system than the erect one, zoospore germination was strictly of the prostrate type and the chromosome number was 8. The ontogeny of the zoospore germination was related to the final relative development of the prostrate and erect portions of adult thalli.     

Chromosome numbers of some species of Salvia (Lamiaceae) from the Sichuan Province, China

The present study reports the chromosome number of 12 accessions belonging to 10 species of Salvia from the Sichuan Province in China. Most accessions have the chromosome number 2n=2x=16. However, three species ( S. evansiana, S. przewalskii and S. brevilabra ) are tetraploid with a chromosome number of 2n=4x=32. A B-chromosome was observed in S. tricuspis . The basic chromosome number x=8 was inferred for all accessions studied. The chromosome number of all the species was determined for the first time, except for S. evansiana, S. przewalskii , S. flava and S. miltiorrhiza . The chromosomes in this genus are mostly small (0.46–2.94 μm). The small size of the chromosomes, together with their unclear centromeres, has hampered a detailed karyotype analysis.     

Transposition patterns of unlinked transposed Ds elements from two T-DNA loci on tomato chromosomes 7 and 8

We have previously reported that unlinked transposed Ds elements originating from chromosome 4 of tomato preferentially inserted in chromosome 2. This observation, together with data from other studies, suggested that there may be absolute preferences for transposition, irrespective of the chromosomal location of the donor site. The aim of the present work was to verify whether the distribution of transposed Ds elements on chromosome 2 was non-random and thus whether, unlike the case in maize, unlinked transpositions in tomato are not distributed randomly. To do this, unlinked acceptor sites of Ds elements originating from two donor T-DNA loci lying on chromosomes 7 and 8 were mapped. Receptor sites for tr Ds elements transposed from the 1601D locus on chromosome 8 exhibited a non-random distribution (P<0.01). Eleven out of 46 independent transpositions mapped to chromosome 2 and, as this was statistically significant (P<0.01), proves that receptor sites for this element are not randomly distribution on the chromosomes. In addition, deviation of the observed number from the expected number of tr Dss was close to being significant for chromosome 4 (P=0.05-0.1). In contrast, the distribution of unlinked receptor sites for tr Dss derived from the 1481J locus on chromosome 7 was random. Chi(2)tests were performed for each chromosome, and for chromosome 4 the difference between the observed and the expected number of tr Dss was very high but statistically non-significant (P=0.05-0.1). For chromosome 2 the difference was statistically negligible. Therefore, we conclude that chromosome 2 does not serve as a preferential receptor for the transposition of Ds elements independently of the location of the donor site.     

黑唇鼠兔的核型分析

本文报道黑唇鼠兔的染色体组型。证明黑唇鼠兔染色体数目2n=46,有别于达乌尔鼠兔,是一个独立的种。     

Molecular Cytological Characterization of Somatic Variation in Rice Aneuploids

Aneuploids cannot be stably preserved by sexual propagation, though they can maintain their genetic identity by asexual propagation. However, it is possible for somaclonal variation to occur during asexual propagation. Surveys taken from 2005 to 2007 showed that there were 26 lines with morphological variations from a total of 114 asexually propagated rice lines. Among these, 12 lines were detected that had either increased or decreased chromosome numbers, while the other 14 lines did not show any changes in chromosome number. Lines with increased chromosome numbers include the following four classes: (1) an extra chromosome was retained, and another normal individual chromosome was increased; (2) an extra chromosome was increased, and the normal chromosome numbers did not change; (3) an extra chromosome was lost, and another chromosome was increased; and (4) the genome was doubled. We studied 543 somatic cells from the 12 lines during mitosis and observed abnormal mitotic behaviors such as chromosome lagging, uneven distribution, and chromosome breakage at anaphase. These results show that abnormal mitotic behavior led to the somaclonal variation in chromosome number. However, cytological variation can only explain a minority of the asexual separated lines.     

Chromosome study of Lithobius forficatus (Lithobiomorpha, Chilopoda)

The diploid number 2n = 46 and the chromosome arm number NF = 74 are described in Lithobius forficatus from Olsztyn (Poland). Analyses of silver and CMA3-stained mitotic chromosomes suggest that a single chromosome pair has active NORs which correspond to G-C-rich (CMA3-positive) chromatin. Heteromorphism of the largest metacentric chromosome pair was observed. The sex chromosomes were not identified. Size polymorphism of the first chromosome pair was found.     

阿拉善黄鼠模式产地标本染色体核型

采用骨髓细胞直接制备染色体的方法,对采自阿拉善黄鼠(Spermophilus alaschanicus Buchner,1888)模式标本产地,内蒙古阿拉善南部典型荒漠区的5号黄鼠(Spermophilus spp.)标本进行染色体研究.结果表明,该种二倍体体细胞的染色体数为2n=38,与达乌尔黄鼠(草原黄鼠)(S.dauricus Brandt,1843)二倍体体细胞的染色体数2n=36,完全不同,且形态特征与达乌尔黄鼠具有明显差异.基于该种的染色体和形态特征以及分布区域,并与国内外相关研究比较的结果,确认该种为阿拉善黄鼠.     

Electron microscopic band-interband pattern of polytene chromosomes in Drosophila nasuta albomicans. 2. Salivary gland chromosome 2L.

The band-interband pattern (division 28-52) of salivary gland chromosome 2L in Drosophila nasuta albomicans was studied by light (LM) and electron microscopy (EM) using squash preparations and surface-spread polytene (SSP) chromosome preparations, respectively. LM and EM maps were complied. Based on the digitized EM patterns of five homologous SSP chromosomes a computerized EM chromosome map was plotted. The EM pattern analysis showed a total number of 479 chromosome bands with an almost 83% increase compared with the LM analysis of squash preparations. By extrapolation of the data from 39% of the polytene genome analysed so far in D. n. albomicans, a total number of 2,926 chromosome bands was calculated. This is almost the same number of bands as was calculated earlier for Drosophila hydei using the same SSP chromosome preparation technique. The data in the literature concerning variations in the number of chromosome bands in different Drosophila species, the various chromosome preparation techniques adopted, and the different criteria used for the EM pattern analyses, are discussed.