普通小麦栽培品种丰抗13的4B—1D染色体易位的鉴定

通过细胞学观察,在普通小麦栽培品种“丰抗13”和“京红1号”的杂交后代中,发现有多价体出现,这就表明有染色体易位发生。为进一步弄清究竟是哪条染色体发生了易位,我们采用单体测交方法,观察鉴定所有各单体系F_1的花粉母细胞第一次减数分裂中期Ⅰ(以下简称PMCs中Ⅰ)染色体构型。从鉴定结果发现,凡2n=42的F_1 PMCs中Ⅰ出现19~Ⅱ 1~Ⅳ,而2n=41的F_1PMCs中Ⅰ的染色体构型不同,单体与易位有关的两个单体系4B和1D F_1 PMCs中的Ⅰ构型中有部分呈现为19个二价体加1个三价体,即19~Ⅱ 1~Ⅲ,没有单价体,而其余各单体系F_1 PMCs中Ⅰ构型则表现为18个二价体,1个四价体和1个单价体,即18~Ⅱ 1~Ⅰ 1~Ⅳ。因此,可以肯定“丰抗13”存在1个染色体易位,其有关染色体就是4B和1D。     

籼稻体细胞培养再生植株染色体变异的研究

以IR36及IR54等品种的成熟种子及幼穗为外植体,获得籼稻体细胞培养再分化植株,并研究了再生植株当代(即第一代,SC_1)的染色体变异。在319株SC_1植株中发现四倍体10株,占总数的3.1％。在二倍体中发现不育株7株(占2.2％),其中经细胞学分析发现2株(1984及1985年各发现1株)为多染色体相互易位杂合子。减数分裂的研究表明,MRT植株终变期时染色体构形呈十分复杂的情况。除正常的12 Ⅱ外,还呈现出一系列的多价体。配对最高价性为拾价体,7 Ⅱ+1Ⅹ的构形占各种染色体构形总数的50.7％,分布最多。在这类染色体构形中,拾价染色体或呈环形(以7 Ⅱ+1⑩表示),或呈链形(以7 Ⅱ+1(?)表示)。这表明该植株12对染色体中有5条非同源染色体发生了相互易位,而这两株植株正是这种染色体易位的杂合子。     

粘型小麦雄性不育系减数分裂特征及育性恢复研究

调查了粘型1B／1R和非1B／1R小麦雄性不育系,保持系及其F2的花粉母细胞减数分裂中期Ⅰ染色体联会情况、后期Ⅰ出现落后染色体的细胞频率以及末期Ⅱ含有微核的四分体的频率,结果表明：（1）粘果山羊细胞质对1B／1R型不育系减数分裂染色体配对水平具有特异性降低作用;（2）粘型1B／1R不育系减数分裂中期Ⅰ出现单价体细胞频率与后期Ⅰ出现落后染色体细胞的频率呈正相关,也与含微核的四分体频率呈正相关,而对应保持系则没有相关性;（3）粘果山羊草细胞质对非1B／1R不育系减数分裂过程影响不大,5个1B／1R不育系减数分裂过程中,3个时期染色体行为变异率的差异是特定的1B／1R核型与粘果山羊草细胞质互作的结果;（4）粘型1B／1R不育系杂交R2单株减数分裂3个时期染色体行为变异率与其恢复度成反比,这类不育系减数分裂中染色体行为不同步是其恢复不高且变异较大的一重要原因。     

水稻花药培养植株后代的DNA变异

对籼稻圭６３０和粳稻０２４２８及其Ｆ１通过花药培养获得的８１个ＤＨ系进行了ＲＦＬＰ分析,有２８个探针揭示了ＤＮＡ变异。８１个ＤＨ系不同程度地发生了变异,并具有以下特点：（１）ＤＮＡ变异类型包括限制性片段长度的变化、９ＮＡ片段的丢失以及ＤＮＡ序列的扩增;（２）变异发生在籼稻圭６３０供体片段中的频率高于粳稻０２４２８,表现出基因型差异;（３）染色体组中第３、８、９和１０染色体较少发生变异,在其它染色体上均存在易变异位点;（４）在染色体的一些区段,相邻的探针均揭示了ＤＮＡ变异,表明在染色体上存在ＤＮＡ易变异区域;（５）变异位点和变异类型具有特异性,在同一位点不同的ＤＨ系中发生相同的变异。     

抗白粉病小麦-中间偃麦草二体异附加系与杀配子材料杂交后代的细胞遗传学研究

利用已选育的抗白粉病烟农15-中间偃麦草二体异附加系与农林26-离果山羊草3C染色体附加系杂交．对其F1、F2、F3的细胞遗传学进行研究．结果表明：F1花粉母细胞减数分裂中期Ⅰ染色体构型紊乱,在39．48％的细胞中发现染色体断片、单价体,后期Ⅰ、后期Ⅱ出现落后染色体、染色体桥．四分体期微核出现频率达48．65％,说明杀配子染色体可有效诱导染色体发生断裂等结构变异;F2代在细胞学方面仍不稳定,表现为染色体数目发生变异,花粉母细胞减数分裂染色体构型紊乱。多价体、落后染色体、染色体桥及微核的普遍出现．说明染色体问可能发生断裂、重接、交换或易位等现象,F2代白粉病抗性也出现分离;F3代虽然染色体数日和白粉病抗性仍在分离,但花粉母细胞减数分裂中期Ⅰ染色体构型较F2稳定,相对紊乱系数下降．从F3代鉴定出了染色体数目为42、构型稳定且对白粉病表现免疫的单株。     

小钻‘白城杨2号’小孢子发生及花粉大小变异

利用醋酸洋红染色压片技术,以温室水培小钻‘白城杨2号’(Populus×xiaozhuanica W.Y.Hsu et Liangcv.‘Baicheng-2’)为材料,对其小孢子发生过程中染色体行为及花粉大小变异进行研究。结果表明:(1)‘白城杨2号’小孢子母细胞减数分裂过程中染色体行为存在一定比例的异常现象,包括终变期单价体、中期Ⅰ染色体提前分离、后期Ⅰ和Ⅱ落后染色体和染色体桥、末期Ⅰ和Ⅱ微核、中期Ⅱ纺锤体定位异常以及胞质分裂异常等,这些异常现象的发生与‘白城杨2号’杂种起源有密切关系。(2)‘白城杨2号’小孢子母细胞减数分裂过程中核仁数目存在动态变化,末期Ⅰ和Ⅱ的子核中最多可看到8个小核仁,可能与杨属树种的多倍体起源有关,其染色体组中可能包含8对具核仁组织者区的染色体。(3)‘白城杨2号’产生空瘪花粉率为3.67%,饱满花粉直径在21.3～52.2μm之间,频率分布总体呈近似高斯分布,0.69%的花粉直径超过37μm,表明其可能产生少量未减数的2n花粉。     

小麦-簇毛麦种质系‘山农030713＇的细胞学和SSR鉴定

利用形态学、细胞学以及SSR标记技术对从硬簇麦和Am3的杂种后代中选育的种质系‘山农030713＇进行了鉴定,结果表明：种质系‘山农030713＇大田生长整齐一致,农艺性状较好,且对白粉病免疫;其根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期Ⅰ（PMC M Ⅰ）染色体构型为2n=21Ⅱ;它与普通小麦的杂种F1PMC MⅠ多数细胞中形成21个二价体,且常有四价体出现,可能伴有染色体的结构变异;SSR分析证明‘山农030713＇基本染色体组成为AABBDD,引物Xgwm99-1A在‘山农030713＇中扩增出簇毛麦的特异带,表明‘山农030713＇中有来自于簇毛麦的遗传物质,此特异带可作为识别‘山农030713＇的SSR标记.综合形态学、细胞学和SSR分析结果推测,‘山农030713＇可能是一个小麦-簇毛麦易位系.     

小麦-黑麦二体异附加系分子细胞遗传学鉴定

用形态学、细胞学、生化及分子标记方法,对小麦-黑麦衍生系N9436-0-2-29-9进行分析鉴定,以明确N9436-0-2-29-9中具体的外源染色体。农艺性状调查表明,N9436-0-2-29-9衍生系在形态上整齐一致,对白粉病高抗;细胞学分析表明,染色体构型稳定,2n=44=22Ⅱ;Giemsa C-分带和SSR分析表明,该衍生系为普通小麦-黑麦6R二体异附加系;高分子量麦谷蛋白亚基分析(HMW-GS)表明,外源染色体的导入使该衍生系的高分子量麦谷蛋白亚基表达受到影响。     

应用荧光原位杂交技术研究小冰麦异附加系TAI-27的变异

常规染色体观察表明 :原初的小冰麦异附加系TAI 2 7为 2n =44,其中所有的染色体都是中部或近中着丝点染色体 .但后来发现有 2种植株形态不同的后代均有 1对染色体变成小染色体 .经用荧光原位杂交技术 (fluorescenceinsituhybridiza tion ,FISH)检测发现 ,一种变异类型的 1对小染色体是来自冰草 ,另一种变异类型除变异的 1对小染色体来自冰草 ,还有 1对冰草染色体代换了小麦染色体形成异附加代换系 .TAI -2 7及其变异类型均表现高抗大麦黄矮病 (barleyyellowdwarfvirus ,BYDV) .对这种变异发生的原因及变异类型的用途做了简短讨论     

小麦-簇毛麦种质系''山农030713''的细胞学和SSR鉴定

利用形态学、细胞学以及SSR标记技术对从硬簇麦和Am 3的杂种后代中选育的种质系‘山农030713’进行了鉴定,结果表明:种质系‘山农030713’大田生长整齐一致,农艺性状较好,且对白粉病免疫;其根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期Ⅰ(PM C MⅠ)染色体构型为2n=21Ⅱ;它与普通小麦的杂种F1PM C MⅠ多数细胞中形成21个二价体,且常有四价体出现,可能伴有染色体的结构变异;SSR分析证明‘山农030713’基本染色体组成为AABBDD,引物X gwm 99-1A在‘山农030713’中扩增出簇毛麦的特异带,表明‘山农030713’中有来自于簇毛麦的遗传物质,此特异带可作为识别‘山农030713’的SSR标记.综合形态学、细胞学和SSR分析结果推测,‘山农030713’可能是一个小麦-簇毛麦易位系.     

Number and distribution of silver-stained nucleolar organizer regions and evolutionary relationships in domestic pigs

Variation in the numbers of silver-stained nucleolar organizer regions (Ag-NORS) were examined in 36 breeds of domestic pig of different geographic origins and five subspecies of wild boar. The relationship between Ag-NORs and evolution of domestic pigs was investigated. In all pigs observed, Ag-NORs were localized on the secondary constriction of chromosomes 10 and 8. The mean Ag-NOR numbers varied from 2.0–4.0, and decreased gradually with the different geographical distribution from south to north in China and from east to west in Europe. This regular change was caused mainly by the differences of frequency in chromosome 8 Ag-NOR type and was closely related to the evolution of domestic pig breeds.     

Simultaneous high resolution localization of Ag-NOR proteins and nucleoproteins in interphasic and mitotic nuclei

Summary Silver stainable proteins of the Nucleolar Organizer Regions (Ag-NOR proteins) of human breast cancer tissues have been localized at the electron microscopical level with a new method which combines a simple and reproducible one step Ag-NOR staining method combined with an acetylation procedure. This new method allows the fine identification of nucleolar components, particularly those which are stained by silver.In order to determine the cytochemical nature of the components associated with Ag-NOR proteins, the EDTA regressive preferential staining procedure for ribonucleoproteins has been applied to sections. By this means the precise localization of the Ag-NOR proteins was studied simultaneously with that of ribonucleoprotein within interphasic nucleoli and mitotic chromosomes.In interphasic nucleoli, stainable Ag-NOR proteins were localized in fibrillar centres and part of the dense fibrillar component. No silver deposits were seen on perichromatin or interchromatin fibrils and granules.In metaphasic nuclei, Ag-NOR proteins were only found on roundish fibrillar ribonucleoprotein structures, which could correspond to secondary constrictions. No silver deposits were seen on the well defined ribonucleoprotein sheet surrounding the chromosomes.In telophasic nuclei, Ag-NOR proteins were seen on the central part of roundish ribonucleoprotein fibrillar structures integrated in decondensing chromosomes. These structures have been interpreted as the nucleolar organizer regions around which rRNA synthesis resumes.In interphasic and mitotic nuclei, Ag-NOR proteins were never found within condensed chromatin but always in association with ribonucleoprotein components.The new method proposed here appears to be a useful tool for the simultaneous study of the localization of ribonucleoprotein and Ag-NOR proteins during the cell cycle.     

Numerical variation of nucleolar organizer regions after silver staining in domestic and wild Suidae (Mammalia)

Selective silver staining was used to investigate the cellular distribution of numbers of nucleolar organizer regions (NORs) in domestic pigs (Sus scrofa) of eight different breeds, the European wild boar (S. scrofa scrofa), Indonesian wild boar (S. scrofa vittatus), Javan warty pig (S. verrucosus), Sulawesi warty pig (S. celebensis), and pigmy hog (S. salvanius). In the domestic pig as well as in the wild (sub)species of Sus, actively transcribing ribosomal RNA genes were found to be present in the secondary constrictions of chromosome pairs 10 and 8. Chromosomes 10 were consistently Ag-positive. Chromosomes 8 less frequently showed Ag-NORs, resulting in different mean numbers of Ag-NORs per individual animal. Mean Ag-NOR numbers per breed or (sub)species were generally higher in the wild representatives of Sus than in the domestic breeds. The highest mean numbers of Ag-NORs were observed in the Meishan breed and in S. celebensis and S. salvanius. The Meishan breed appears to be conservative in Ag-NOR staining pattern, being more comparable to the Asian wild Suidae than to the European breeds.     

Homoeologous pairing and recombination in <Emphasis Type="Italic">Solanum lycopersicoides</Emphasis> monosomic addition and substitution lines of tomato

We compared meiotic pairing and recombination between tomato ( Lycopersicon esculentum) and homoeologous Solanum lycopersicoides chromosomes in monosomic additions (MAs) and substitution lines (SLs), each representing a single chromosome of the nightshade in a tomato background. Three configurations of each alien chromosome and its two tomato homoeologues were detected by genomic in situ hybridization in MA-7, -8, and -10 at diakinesis/metaphase-I: 1 trivalent (III), 1 bivalent + 1 univalent (II+I), and 3 univalents (3I). The II+I category was by far the most common, and the univalent was from S. lycopersicoides 91-99.5% of the time, indicating a high degree of preferential (homologous) pairing. In the corresponding substitution lines, association of homoeologous chromosomes was much higher (up to 90% of the cells), presumably due to the absence of homologous partners. However, SL-10 showed a surprisingly high frequency of univalents (about 73%). Genome-wide analysis of chromosome pairing revealed a decrease in the average chiasma frequency for both monosomic additions and substitution lines. Recombination between tomato and the nightshade was restricted in all cases, the reduction being more severe in each monosomic addition than in the corresponding substitution line. Recombination rates in the substitutions were less than those observed for the same chromosomes in the first backcross generation. Chromosomes 8 and 10 showed the highest and the lowest rates of homoeologous recombination, respectively. No recombination was detected between markers on the long arm of chromosome 10, presumably due to the presence of a paracentric inversion differentiating the two genomes in this region. The frequency of homoeologous pairing at diakinesis/metaphase-I was significantly higher than the rate of homoeologous recombination detected in the progeny, suggesting a strong selection against recombinant products in meiotic or post-meiotic stages.     

The effect of hFVIII transgene on the chromosomal aneuploidy rate in rabbits

The aim of this study was to compare the chromosomal aneuploidy rate between transgenic and non-transgenic rabbits derived from the F4 generation. Chromosomal analysis was carried out on bone marrow samples of New Zealand White transgenic (carrying human factor VIII gene) and non-transgenic rabbits (F4 generation) each having a different genetic background (female no. 1-3-5 line I and female no. 1-9-7 line II). C-metaphase plates were obtained from the bone marrow lymphocytes synchronized by the addition of 0.25 microg/ml colcemide. No significant difference in chromosomal aneuploidy between transgenic (61%) and non-transgenic (51.27%) rabbits of line I was observed. A higher but non-significant aneuploidy rate between transgenic and non-transgenic rabbits was found in line II, on the other hand a significant difference (P<0.05) was observed in diploidy rate. In conclusion, chromosomal aneuploidy rates in this experiment were higher than published previously in other reports.     

Methylation status of ribosomal RNA gene clusters in the flow-sorted human acrocentric chromosomes

Southern blot analysis of the human acrocentric chromosomes that were flow-sorted from B-lymphoblastoid cell line GM130B revealed that the sensitivity of the ribosomal RNA (rDNA) gene clusters to the restriction enzyme NotI differs among these rDNA-containing chromosomes: the rDNA clusters of Chromosomes (Chr) 13, 14, and 15 are much more sensitive to NotI digestion than those of Chrs 21 and 22 in this particular cell line. Detailed analysis by use of methylation-sensitive enzymes HpaII and HhaI and methylation-insensitive enzyme MspI confirmed the significant variation in the methylation status of rDNA clusters among these chromosomes. Quantitative analysis by fluorescent in situ hybridization (FISH) indicated that copy number of rDNA varies among individual chromosomes, but the average copy number in the acrocentric Chrs 21 and 22 is significantly greater than that of the Chrs 13, 14, and 15 in GM130B cells. Similar analysis reveals that the methylation status of rDNA clusters in another B-lymphoblastoid cell line GM131 was different from that of GM130B. These data together indicate that the copy number and methylation patterns of rDNA clusters differ among individual acrocentric chromosomes in a given cell line, and they are different among cell lines.     

NORs and statellite associations in a family with 13/14 translocation

Summary The distribution and size of Ag-NORs and the frequency of satellite associations was investigated in a family where the mother and a son were 13/14 translocation carriers. In cells with good quality silver impregnation and G-banding, Ag-NORs were constant per subject in number and distribution, while Ag-NOR size varied from cell to cell. The father had the maximal number Ag-NORs (10). The mother's translocation chromosome, free chromosome 13 and both chromosomes 22 were Ag-NOR negative and these were transmitted to the children. The mean number of associations per cell for a particular subject was positively correlated with the subject's characteristic number of Ag-NORs. In this family, the positive correlation was also present between mean Ag-NOR sizes of acrocentric homologue chromosome pairs and their coefficient of association. No biological mechanism compensating for the absence of active NORs was demonstrated for this family.     

Localisation of phosphorylated MAP kinase during the transition from meiosis I to meiosis II in pig oocytes

Mitogen-activated protein kinase (MAPK) has been reported to be involved in oocyte maturation in all animals so far examined. In the present study we investigate the expression and localisation of active phosphorylated MAPKs (p44ERK1/p42ERK2) during maturation of pig oocytes. In immunoblot analysis using anti-p44ERK1 antibody which recognised both active and inactive forms of p44ERK1 and p42ERK2, we confirmed that MAPKs were phosphorylated around the time of germinal vesicle breakdown (GVBD) and the active phosphorylated MAPKs (pMAKs) were maintained until metaphase II, as has been reported. On immunofluorescent confocal microscopy using anti-pMAPK antibody which recognised only phosphorylated forms of MAPKs, pMAPK was localised at the spindle poles in pig mitotic cells. On the other hand, in pig oocytes, no signal was detected during GV stage. After GVBD, the area around condensed chromosomes was preferentially stained at metaphase I although whole cytoplasm was faintly stained. At early anaphase I, the polar regions of the meiotic spindle were prominently stained. However, during the progression of anaphase I and telophase I pMAPK was detected at the mid-zone of the elongated spindle, gradually becoming concentrated at the centre. Finally, at the time of emission of the first polar body, pMAPK was detected as a ring-like structure between the condensed chromosomes and the first polar body, and the staining was maintained even after the metaphase II spindle was formed. The inhibition of MAPK activity with the MAPK kinase inhibitor U0126 during the meiosis I/meiosis II transition suppressed chromosome separation, first polar body emission and formation of the metaphase II spindle. From these results, we propose that the spindle-associated pMAPKs play an important role in the events occurring during the meiosis I/meiosis II transition, such as chromosome separation, spindle elongation and cleavage furrow formation in pig oocytes.