白Qian胚性愈伤组织长期继代培养中的分化能力及染色体稳定性 …

白Ｑｉａｎ（Ｐｉｃｅａ ｍｅｙｅｒｉ Ｒｅｈｄ．ｅｔ．Ｗｉｌｓ．）的胚性愈伤组织ＭＳ＋２,４－Ｄ１ｍｇ／Ｌ＋ＫＴ１ｍｇ／Ｌ的培养基上继代３年,增殖能力和分化潜力仍保持在原来的水平,没有明显降低的趋势。但随着继代时间的增长,胚性愈伤组织内有细胞的染色体数目发生了无规律的变化,而再生植株根尖细胞染色体数目比较稳定（２ｎ＝２８）。     

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。     

黄槐叶片培养过程中器官发生的研究

以黄槐（ＣａｓｓｉａｓｕｒａｔｔｅｎｓｉｓＢｕｒｍ．ｆ．）幼嫩叶片为材料,接种于ＭＳ＋ＮＡＡ１ｐｐｍ＋２,４－Ｄ１ｐｐｍ＋６－ＢＡ２ｐｐｍ的培养基上,诱导形成两种形态的愈伤组织,即致密愈伤组织与雪花状愈伤组织．将愈伤组织转移到ＭＳ＋ＮＡＡ：１ｐｐｍ＋６－ＢＡ２ｐｐｍ的分化培养基上．仅致密型愈伤组织经过球状体至不定芽途径形成大量再生植株。扫描电镜及组织细胞学观察表明,致密愈伤组织表层细胞排列紧密,有许多分生细胞团,而雪花状愈伤组织表层细胞薄壁化,分裂能力很低。球状体起源于致密愈伤组织表层的分生细胞团,其细胞有极强的分生能力,顶端可以分化发育成不定芽原基,最后形成不定芽并发育成小植株。球状体可以看成是具有形成不定芽能力的繁殖单位．     

小麦愈伤组织及再生植株的染色体变异

对培养在含有不同附加成分的MS培养基上的小麦愈伤组织染色体进行了跟踪研究。结果表明,在整个培养过程中各培养基上愈伤组织都有一定程度的染色体变异。在培养初期,高浓度2,4-D可增加愈伤组织中的染色体变异率,AgNO_3可降低染色体变异率。6-BA对培养初期愈伤组织染色体变异率没有显著影响。但高浓度6-BA可加大长期培养愈伤组织中的超倍体细胞频率。蔗糖浓度对最初9代愈伤组织染色体变异率无显著影响。但之后,低浓度蔗糖培养基上亚倍体细胞频率明显减小。随着培养时间的延长,各培养基上愈伤组织中正常二倍体细胞的频率都有逐渐上升的趋势。在再生植株中,大部分核型正常,只有少数植株具有染色体数目或结构变异。有些核型正常植株也有表型变异。     

水母雪莲愈伤组织培养和黄酮类化合物的形成

８种基本培养基对水母雪莲（Ｓａｕｓｓｕｒｅａ ｍｅｄｕｓａ Ｍａｘｉｍ）愈伤组织生长和黄酮类形成影响不同,ＭＳ培养基较有利于愈伤组织生长和黄酮类形成。碳源、氮源、植物激素对愈伤组织生长和黄酮类形成影响较为显著。从ＭＳ培养基修饰得到的Ｍ－１３培养基培养的愈伤组织生长量和黄酮类产量比原培养基分别提高３３％和８２％,达到２１．００ｇＤＷ／Ｌ和１．８９ｇ／Ｌ。通过ＴＬＣ和ＨＰＬＣ初步分析和鉴定,证明Ｍ－１     

白皮松和油松雌配子体愈伤组织的诱导和分化

以白皮松（Ｐｉｎｕｓ ｂｕｎｇｅａｎａ Ｚｕｃｃ．）和油松（Ｐ．ｔａｂｕｌａｅｆｏｒｍ ｉｓ Ｃａｒｒ．）的未成熟胚乳,即雌配子体为外植体进行培养,将雌配子体分别接种在添加不同激素种类和不同浓度配比的改良ＭＳ培养基上诱导愈伤组织。经过２０多天的培养,在含有１—６ ｍ ｇ／Ｌ 萘氧乙酸（ＮＯＡ）和０．５ｍ ｇ／Ｌ６－ＢＡＰ及３％ 蔗糖浓度的培养基上诱导产生了愈伤组织,愈伤组织的诱导频率最高为２５％ 。经细胞学观察证明：愈伤组织细胞确为单倍性的,染色体数目为ｎ＝ １２,正常的体细胞染色体数目为２ｎ＝ ２４,并在含有ＡＢＡ 的原诱导愈伤组织培养基上分化出绿色小芽     

缺体小麦与黑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３株为染色体嵌合株,１株发生了染色体结构变异。     

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。     

一品红离体培养诱导体细胞胚的研究（简报）

一品红的嫩茎离体培养在附加不同浓度的２,４－Ｄ和６－ＢＡ的ＭＳ培养基上,２．４Ｄ浓度为１．０～２．０ ｍｇ· Ｌ~（－１）的愈伤组织生长量最大。这些愈伤组织转移到ＭＳ＋６－ＢＡ１．０ ｍｇ·Ｌ~（－１）＋ＮＡＡ０．１ ｍｇ·Ｌ~（－１）的分化培养基上后,产生了胚性愈伤组织,观察到大量不同时期体细胞胚。带有体细胞胚的愈伤组织进一步转移到无激素 ＭＳ培养基上,便发育成小植株。     

Incidence of chromosome aberrations among 11148 newborn children.

Chromosome analysis has been made of 11148 children; 29 had sex chromosome abnormalities (2.60 per 1000) and 64 autosomal abnormalities (5.74 per 1000). The total incidence of major chromosome abnormalities was 8.34 per 1000. The incidence of chromosome variations was 16.8 per 1000. The most common variants were those with variation in size of short arms-satellites in D and G chromosomes and variations in Y chromosome size. So far, very little is known about the significance of such chromosome variations. The incidence of most chromosome abnormalities in liveborn children is well established by now from studies of a total of 54749 consecutively liveborn children in 6 studies as shown in Table 1. More chromosome studies of liveborn children are, however, needed for several purposes such as finding families with chromosome translocations, studying segregation rates and giving genetic advice to families with inheritable chromosome aberrations and an increased risk of getting children with unbalanced chromosome abnormalities, mental retardation and physical abnormalities. One of the main purposes in chromosome examination of newborn children is to study the development of children with different chromosome abnormalities, especially those with sex chromosome abnormalities, and compare then with controls, treat them when needed and give advice to the parents of such children.     

Achiasmate Segregation of a B Chromosome from the X Chromosome in Two Species of Psyllids (Psylloidea, Homoptera)

The segregation of a B chromosome from the X chromosome was studied in male meiosis in two psyllid species, Rhinocola aceris (L.) and Psylla foersteri (Flor.) (Psylloidea, Homoptera). The frequency of segregation was determined from cells at metaphase II. In R. aceris, the B chromosome was mitotically stable and segregated quite regularly from the X chromosome in four geographically distant populations, while it showed less regular, but preferential segregation in one population. This was attributed to the presence of B chromosome variants that differ in their ability to interact with the X chromosome in segregation. In P. foersteri, the B chromosome was mitotically unstable and segregated preferentially from the X chromosome in spermatocyte cysts, which displayed one B chromosome in every cell. Behaviour of the B chromosome and X chromosome univalents during meiotic prophase and at metaphase I in R. aceris, and during anaphase I in P. foersteri suggested that the regular segregation resulted from the incorporation of B chromosomes in achiasmate segregation mechanisms with the X chromosome in the place occupied by the Y chromosome in species with XY system. The regular segregation of a B chromosome from the X chromosome may obscure the distinction of a B chromosome and an achiasmate Y chromosome in some cases. This revised version was published online in August 2006 with corrections to the Cover Date.     

Coexistence of inverted Y, chromosome 15p+ and abnormal phenotype.

In this study, we report conventional and molecular cytogenetic studies in a patient with multiple anomalies who is a carrier of a pericentric inversion on chromosome Y and a chromosome 15p+. His parents were phenotypically normal. The father is a carrier of a pericentric inversion of chromosome Y, and the mother carries a large chromosome 15p+ variant. The inverted Y chromosome was demonstrated by GTG- and CBG-banding, and DAPI-staining. The presence of extra chromosomal material on the chromosome 15p, that was C-band and DAPI positive, was demonstrated by trypsin G-banding. This suggests that the extra chromosomal material contained repetitive DNA sequences. NOR-staining indicated the presence a nuclear organizer region at the junction of the chromosome 15p+ material. Fluorescence in situ hybridization (FISH), with chromosome X and Y painting probes, alpha- and classic-satellite probes specific for chromosome Y, alpha- and beta-satellite III probes for chromosome 15 were used to elucidate the nature of both the inverted Y chromosome and chromosome 15p+. The result with chromosome X and Y painting probes, alpha-satellite, classic-satellite, and DYS59 probes specific for chromosome Y revealed the rearrangement of the Y chromosome was an inv(Y)(p11.2q11.22 or q11.23). FISH with alpha-satellite and beta-satellite III probes for chromosome 15 demonstrated that the extra chromosomal material on the chromosome 15 probably represents beta-satellite III sequences. The possible roles of the simultaneous occurrence of an inverted Y and the amplified DNA sequence on chromosome 15p in the abnormal phenotype of the proband are discussed.     

The Origin of the Achiasmatic XY Sex Chromosome System in Cacopsylla peregrina (Frst.) (Psylloidea, Homoptera)

The status of an extra univalent, if it is a B chromosome or an achiasmatic Y chromosome, associating with the X chromosome in male meiosis of Cacopsylla peregrina (Frst.) (Homoptera, Psylloidea) was analysed. One extra univalent was present in all males collected from three geographically well separated populations, it was mitotically stable, and showed precise segregation from the X chromosome. These findings led us to propose that the univalent represents in fact a Y chromosome. The behaviour of the X and Y chromosomes during meiotic prophase suggested that their regular segregation was based on an achiasmatic segregation mechanism characterised by a 'touch and go' pairing of segregating chromosomes at metaphase I. To explain the formation of the achiasmatic Y within an insect group with X0 sex chromosome system, it was suggested that the Y chromosome has evolved from a mitotically stable B chromosome that was first integrated into an achiasmatic segregation system with the X chromosome, and has later become fixed in the karyotype as a Y chromosome.     

Presence of various rye-specific repeated DNA sequences on the midget chromosome of rye.

The chromosome 1R of rye, or the midget chromosome, is necessary for plump, viable seed development and fertility restoration in the alloplasmic line with rye cytoplasm and a hexaploid wheat nucleus. The midget chromosome of rye represents 1/15th of the physical length of the chromosome 1R of rye. C-banding analysis indicated that the centromeric and pericentric region (approximately 30% physical length) of the midget chromosome is heterochromatic and the distant 70% physical length is euchromatic. These data suggest that the midget chromosome may represent the pericentric region of the long arm of chromosome 1R. In contrast with earlier reports, our results indicate that an array of rye-specific repeated sequences (both dispersed and tandem) are present on the midget chromosome. Various rye-specific repeated DNA sequences that are present on the midget chromosome will be useful in constructing a long-range map and studying the genomic organization of the midget chromosome. It is unclear if any of these repeated DNA sequences are involved in the origin of the midget chromosome.     

Chromosomal Evolution in the Genus Brachyscome (Asteraceae, Astereae): Statistical Tests Regarding Correlation Between Changes in Karyotype and Habit Using Phylogenetic Information

Brachyscome and 8 taxa of its allied genera, Australian Astereae. Statistical tests regarding correlations between changes in chromosome number, total chromosome length, mean chromosome length, karyotypic asymmetry and chromosome length heterogeneity and changes in habit were performed based on the matK molecular phylogenetic tree. The reductions in chromosome number and total chromosome length, and the increases in mean chromosome length, chromosome length heterogeneity and karyotypic asymmetry were found to be correlated with the change in habit from perennial to annual. A reduction in total chromosome length is favored to shorten the mitotic cell cycle and to produce smaller cells conducive to more rapid development of smaller annuals under the time-limited environment. Stepwise dysploidal reductions in chromosome number were achieved through the translocation of large chromosome segments onto other chromosomes, followed by the loss of a centromere, resulting in one fewer linkage group and one fewer haploid chromosome. The correlations between the dysploidal reduction in chromosome number and the increases in mean chromosome length, length heterogeneity and asymmetry in karyotype can be attributed to this mode of chromosomal change. These changes occurred independently in several different lineages in Brachyscome. Received 27 May 1998/ Accepted in revised form 18 January 1999     

显微镜光度计扫描测量人中期染色体的面积与DNA相对含量

应用显微镜光度计扫描测量人中期染色体的面积与DNA相对含量,结果显示出人染色体相对面积与相对长度之间密切的相关性。染色体DNA相对含量的高低,与染色体面积大小呈正相关。此外,DNA在染色体二维图形的分布是不均匀的,边缘与着丝粒部位的含量低,在纵向范围内变化较大,在横向范围内的变化较小。     

Radiation-induced cytogenetic damage in relation to changes in interphase chromosome conformation

The premature chromosome condensation (PCC) technique was used to study several factors that determine the yield of chromosome fragments as observed in interphase cells after irradiation. In addition to absorbed dose and the extent of chromosome condensation at the time of irradiation, changes in chromosome conformation as cells progressed through the cell cycle after irradiation affected dramatically the yield of chromosome fragments observed. As a test of the effect of chromosome decondensation, irradiated metaphase Chinese hamster ovary (CHO) cells were allowed to divide, and the prematurely condensed chromosomes in the daughter cells were analyzed in their G1 phase. The yield of chromosome fragments increased as the daughter cells progressed toward S phase and chromosome decondensation occurred. When early G1 CHO cells were irradiated and analyzed at later times in G1 phase, an increase in chromosome fragmentation again followed the gradual increase in chromosome decondensation. As a test of the effect of chromosome condensation, G0 human lymphocytes were irradiated and analyzed at various times after fusion with mitotic CHO cells, i.e., as condensation proceeded. The yield of fragments observed was directly related to the amount of chromosome condensation allowed to take place after irradiation and inversely related to the extent of chromosome condensation at the time of irradiation. It can be concluded that changes in chromosome conformation interfered with rejoining processes. In contrast, resting chromosomes (as in G0 lymphocytes irradiated before fusion) showed efficient rejoining. These results support the hypothesis that cytogenetic lesions become observable chromosome breaks when chromosome condensation or decondensation occurs during the cell cycle.     

Chromosome abnormalities in newborn children. Physical aspects

Summary A chromosome examination was made on 11,148 consecutively live-born children: 93 had a chromosome abnormality and 192 a chromosome variant. The physical aspects of the children with chromosome abnormalities and variants were compared with those of the children with normal karyotypes. Children with aneuploid or unbalanced chromosome abnormalities were more frequently immature or not fully developed at birth than those with normal karyotypes. Birth weight was lower in children with all types of chromosome abnormalities, including reciprocal translocations and chromosome variants. The low birth weight in children with chromosome variants was mainly due to the low birth weight of children with G variants. These children were also subject to a higher frequency of special delivery treatment. Heart disorders were increased in children with aneuploid or unbalanced chromosome abnormalities. The frequency of foetal erythroblastosis was increased in children with short Y as well as in children with acentric fragments. Neonatal mortality was higher in children with aneuploid or unbalanced chromosome abnormalities than in children with normal karyotypes.     

Resolution of Dicentric Chromosomes by Ty-Mediated Recombination in Yeast

We have integrated a plasmid containing a yeast centromere, CEN5, into the HIS4 region of chromosome III by transformation. Of the three transformant colonies examined, none contained a dicentric chromosome, but all contained a rearranged chromosome III. In one transformant, rearrangement occurred by homologous recombination between two Ty elements; one on the left arm and the other on the right arm of chromosome III. This event produced a ring chromosome (ring chromosome III) of about 60 kb consisting of CEN3 and all other sequences between the two Ty elements. In addition, a linear chromosome (chromosome IIIA) consisting of sequences distal to the two Ty elements including CEN5, but lacking 60 kb of sequences from the centromeric region, was produced. Two other transformants also contain a similarly altered linear chromosome III as well as an apparently normal copy of chromosome III. These results suggest that dicentric chromosomes cannot be maintained in yeast and that dicentric structures must be resolved for the cell to survive.--The meiotic segregation properties of ring chromosome III and linear chromosome IIIA were examined in diploid cells which also contained a normal chromosome III. Chromosome IIIA and normal chromosome III disjoined normally, indicating that homology or parallel location of the centromeric regions of these chromosomes are not essential for proper meiotic segregation. In contrast, the 60-kb ring chromosome III, which is homologous to the centromeric region of the normal chromosome III, did not appear to pair with fidelity with chromosome III.