家猪品种间染色体显带核型的比较研究

研究了东北民猪和姜曲海猪的几种显带核型,两品种间G带、C带、DA/DAPI带无显薯差异,Ag- NOR的多项频率有显著差异。     

限制酶AluI显带和CA_3/DA/DAPI染色表达的家猪染色体结构异染色质

采用限制酶AluI显带、CA_(?)/DA/DAPI荧光染色和常规C带技术研究了家猪染色体着丝粒结构异染色质,结果表明:着丝粒结构异染色质至少可被区分为3类,并且在染色体组内各有其特异的染色体分布。将家猪染色体DA/DAPI荧光带和限制酶AluI显带与人类染色体比较,发现家猪13—18号端着丝粒染色体显带特征与人染色体1,9、16、Y一致。提示家猪13—18号端着丝粒区结构异染色质存在与人类随体DNA相似的DNA组成。     

水牛染色体的限制酶显带

本文用限制酶HaeIII、AluI和胰酶显代技术处理了水牛染色体,并且用CMA₃/DA/DAPI三重染色,在荧光显微镜下观察了水牛染色体的荧光染色情况。结果表明：HaeIII处理水牛染色体18小时产生G样带带纹,处理20小时产生C样带带纹。AluI处理水牛染色体20小时也能产生G样带带纹。CMA3使染色体的着丝粒区发出明亮荧光,DA/DAPI则不能说明着丝粒区的结构异染色质相对富含GC碱基。     

少花龙葵与黄果龙葵染色体核型分析

利用DAPI显带技术对少花龙葵和黄果龙葵染色体进行了核型分析。结果表明,少花龙葵染色体数目为24,为二倍体,核型公式为K(2n)=24=6sm+18m;黄果龙葵染色体数目为48,为四倍体,核型公式为K(4n)=48=48m,并进一步构建了这两个种的核型模式图。此外,还初步探讨了染色体的DAPI带型及其异染色质的分布。为中国龙葵的系统分类和进化趋向研究,以及育种和资源的开发利用提供帮助。     

三峡库区消落带农作区镉污染特征研究

为了研究三峡库区消落带农作区重金属镉的污染状况,对三峡库区典型支流-苎溪河消落带农作区耕作情况及镉污染状况进行了调查。结果表明:苎溪河消落带农作区土壤镉含量普遍偏高,均超过了国家土壤环境质量三级标准,远高于四川省土壤环境背景值,并存在中等程度变异,说明镉污染存在普遍性。相应地上作物不同部位对镉均有一定程度富集,叶的富集能力最大,而果实的富集能力相对较小。作物可食部分镉富集能力顺序为:蕹菜>香菜>花生>豇豆>绿豆。其中,香菜和蕹菜的风险商HQ值>1,暴露风险高,对三峡库区生态安全存在一定潜在健康风险。     

鱼类染色体的荧光显带研究

应用GC碱基特异性荧光染料色霉素A,辅以AT减基特异性荧光染料Hoechst33258,DAPI或喹吖因对鲤鱼,鲫鱼,大鳞副泥鳅和的有丝分裂染色体及黄鳝的有丝分裂和减数分裂染色体进行了荧光显带研究,结果发现,色霉素A3可以特异性地显示鱼类有丝分裂及减数分裂各个时期核仁组织区NORS的存在,Hoechst33258,DAPI或喹吖因则使这些区域（NORs)淡染,大鳞副泥鳞的染色体NORs 分布位置具有性别,根据实验结果,对有关鱼类染色体的荧光染色研究及其应用进行了讨论。     

苜蓿核糖体基因物理定位及染色体荧光分带

利用核糖体基因为探针对,二倍体和四倍体苜蓿(Medicago sativa)进行原位杂交,结果表明,45s在四倍体、二倍体种中总是以单位点位于核仁组织区,5s则有2～3个位点;以二倍体种的基因组DNA为探针的原位杂交表明,蓝花苜蓿(M.coerulea)和黄花苜蓿(M.falcata)均能与四倍体染色体进行杂交,仅杂交信号强弱的染色体数目有差别;荧光染料DAPI使苜蓿的染色体显示带纹,蓝花苜蓿的DAPI带与C-带基本一致.文章对四倍体苜蓿的可能来源进行了讨论.     

Cu、Zn对水蕹菜生长的影响及Se的缓解作用

为了解Cu、Zn对水蕹菜生长的影响以及Se缓解Cu、Zn胁迫的效果,本试验以大叶水蕹菜和柳叶水蕹菜为材料,通过营养液栽培,研究了Cu、Zn处理下水蕹菜产量、生理指标和Cu、Zn含量的变化以及Se对Cu、Zn胁迫下水蕹菜生长的影响。结果表明:低浓度Cu、Zn促进水蕹菜生长;高浓度Cu、Zn抑制其生长,表现为根系活力、抗氧化酶活性和净光合速率(Pn)下降,MDA含量增加。Cu、Zn浓度分别为4.00和8.00 mg·L~(-1)时,水蕹菜产量显著下降。Cu对水蕹菜的毒害高于Zn,柳叶水蕹菜的抗氧化能力高于大叶水蕹菜。水蕹菜中Cu、Zn含量随处理浓度的增加而增加。SOD、POD、CAT和脯氨酸在缓解低浓度Cu、Zn毒害中具有协同作用。高浓度Cu、Zn处理时,水蕹菜抗氧化酶活性受到抑制,则以植物络合素(PCs)和脯氨酸的抗氧化作用为主。Se能提高水蕹菜、抗氧化酶活性以及PCs和脯氨酸含量,增强水蕹菜对Cu、Zn的抗性,提高根系活力和Pn,降低MDA的积累,促进水蕹菜生长。当水蕹菜受到轻度Cu、Zn毒害时,5.00 mg·L~(-1)的Se处理缓解效果较好。Se浓度过高会加剧Cu、Zn对水蕹菜的毒害。     

甘薯栽培种及其近缘野生种的DAPI核型及rDNA FISH分析

利用DAPI显带和rDNA-FISH技术对栽培种甘薯(‘徐薯18’)(Ipomoea batatas cv.Xushu No.18)及2种不同产地近缘野生种(Ipomoea hederacea Jacq.)进行了细胞遗传学研究。DAPI核型分析表明,‘徐薯18’核型公式为2n=6x=90=72m+18sm(18SAT),随体位于第1、3、6染色体上;美国近缘野生种核型公式为2n=2x=30=30m(4SAT),香港近缘野生种核型公式为2n=2x=30=20m+10sm(4SAT),随体均位于第6、12染色体上。rD-NA-FISH结果显示,栽培种甘薯基因组中含有3对5SrDNA位点,分别位于着丝粒区、亚着丝粒区和染色体端部;美国近缘野生种基因组中含有2对5SrDNA位点,香港近缘野生种基因组中含有1对5SrDNA位点,均位于随体部位;两种不同地域来源的近缘野生种基因组中均含有2对45SrDNA位点,分别位于第6和第12染色体上。     

番茄的CPD带型和45S rDNA位点的鉴别

采用CPD（PI和DAPI组合）染色对番茄减数分裂粗线期和有丝分裂中期染色体进行了显带分析,随后用两种不同的45S rDNA克隆在相同的分裂相进行了荧光原位杂交定位分析。CPD染色在8条粗线期染色体上显示出了10条红色的CPD带纹,在6对有丝分裂中期染色体上显示出了12条CPD带纹。有丝分裂中期染色体上的CPD带纹与粗线期染色体上显著的带纹具有对应性。用改良的CPD染色程序清晰而稳定地显示出这些特征性的CPD带纹为番茄的染色体,特别是有丝分裂中期染色体提供了新的识别标记。用番茄的一个45S rDNA克隆进行的荧光原位杂交,不仅在位于2号染色体短臂的随体上显示了强的杂交信号,而且在粗线期染色体的5个CPD带区或有丝分裂中期染色体的4对CPD带区显示了弱的杂交信号。然而,用来自小麦的45S rDNA克隆pTa71进行的原位杂交却只在随体上显示了杂交信号。鉴于所用的两个45S rDNA克隆在序列上的差异,推断在番茄基因组中只有随体含有45S rDNA单位的编码区,即番茄只有一对45S rDNA位点。     

CABAND: Classification of aberrations in multicolor banded chromosomes

A system is presented to describe aberrations in chromosomes painted with the mBAND methodology. The CABAND (classification of aberrations in multicolor banded chromosomes) system is based on the fact that only banded parts of aberrations and not DAPI stained parts can be described accurately.     

旋花科植物雄性细胞的细胞质DNA存在状况及其系统学意义

用DAPI荧光染色方法检测了旋花科4属4种植物——空心菜Ipomoea aquatica Forsk. 、茑萝 Qua- moclit pennata (Desr．)Boj．、月光花 Calonyction aculeatum(L．)House和日本菟丝子Cuscuta japonica Choisy 中生殖细胞和精细胞中细胞质DNA存在的状况。证明除日本菟丝子外,其余3种植物的雄性细胞中都 存在细胞质DNA。此外,在我们曾研究过的5种旋花科种植物的生殖细胞和精细胞中亦显示含有细胞质 DNA,因而可认为这是旋花科较普遍的特性,日本菟丝子精细胞中缺少细胞质DNA,可作为—个新的胚胎学证据,支持此属从旋花科分出独立为菟丝子科。     

Cold-sensitive chromosome regions and heterochromatin inCestrum aurantiacum (Solanaceae)

The karyotype ofCestrum aurantiacum was analyzed for the presence of coldsensitive regions (CSRs) and other types of constitutive heterochromatin. A range of techniques was employed including the fluorescent DAPI, chromomycin/DAPI double staining and actinomycin D/DAPI counter-staining, and the non-fluorescent C-banding applied as single or sequential staining, sequential N-banding and silver impregnation. Four classes of constitutive heterochromatin were recognized: CSRs, nucleolar organizers, non-nucleolar chromomycin-positive bands, and indifferently fluorescent bands. The banded karyotype ofC. aurantiacum is compared with those of otherCestrum species. The sectionsHabrothamnus andCestrum are not karyologically distinct.     

Banding of unfixed mitotic chromosomes in suspension after release from human lymphocytes and fibroblasts

Summary Combined application during chromosome isolation of the non- or weakly fluorescent DNA-intercalators 4-aminomethyl-4,5, 8-trimethylpsoralen and daunomycin as stabilizers of mitotic chromosome structure, and the non-intercalating DNA-binding fluorochromes DAPI and D287/170 as producers of a visible banding pattern, resulted in clearly banded unfixed floating chromosomes. Chromosomes stabilized by intercalation appeared to be sufficiently stable to allow the reproduction of distamycin A/DAPI or netropsin/DAPI staining in suspension, thus highlighting specific heterochromatic regions on the floating chromosomes. The results of this study demonstrate that the inducibility of bands is an inherent characteristic of mitotic chromosome organization. Possible practical applications of these results in flow cytometry are discussed.     

Occurrence of G-banding in metaphase chromosomes of Encarsia berlesei (Hymenoptera: Aphelinidae).

Well-defined G-bands were obtained on somatic metaphase chromosomes of Encarsia berlesei using trypsin and warm 2x SCC in sequence. The G-banded pattern allowed rapid identification of all five metacentric chromosomes, which appeared uniformly lighted when stained with DAPI fluorochrome dye. It is stressed that ageing affects G-banding in this insect species; in fact, good banded chromosomes were obtained on 1-month air-stored chromosomes. Evidence for asynchronous condensation on the chromosomes of this species is also provided.     

Heterochromatin and rDNA sites distribution in the holocentric chromosomes of Cuscuta approximata Bab. (Convolvulaceae).

Cuscuta is a widely distributed genus of holoparasitic plants. Holocentric chromosomes have been reported only in species of one of its subgenera (Cuscuta subg. Cuscuta). In this work, a representative of this subgenus, Cuscuta approximata, was investigated looking for its mitotic and meiotic chromosome behaviour and the heterochromatin distribution. The mitotic chromosomes showed neither primary constriction nor Rabl orientation whereas the meiotic ones exhibited the typical quadripartite structure characteristic of holocentrics, supporting the assumption of holocentric chromosomes as a synapomorphy of Cuscuta subg. Cuscuta. Chromosomes and interphase nuclei displayed many heterochromatic blocks that stained deeply with hematoxylin, 4',6-diamidino-2-phenylindole (DAPI), or after C banding. The banded karyotype showed terminal or subterminal bands in all chromosomes and central bands in some of them. The single pair of 45S rDNA sites was observed at the end of the largest chromosome pair, close to a DAPI band and a 5S rDNA site. Two other 5S rDNA site pairs were found, both closely associated with DAPI bands. The noteworthy giant nuclei of glandular cells of petals and ovary wall exhibited large chromocentres typical of polytenic nuclei. The chromosomal location of heterochromatin and rDNA sites and the structure of the endoreplicated nuclei of C. approximata seemed to be similar to those known in monocentric nuclei, suggesting that centromeric organization has little or no effect on chromatin organization.     

Resistance of sweetpotato genotypes to adult Diabrotica beetles

Production of sweetpotatoes, Ipomoea batatas (L.) Lam. (Convolvulaceae), is limited by several insect pests, including Diabrotica spp. (Coleoptera: Chrysomelidae), and new integrated pest management (IPM) techniques for this crop are needed. Host plant resistance is one attractive approach that fits well into IPM programs. A host plant resistance research program typically depends on reliable bioassay procedures to streamline evaluation of germplasm. Thus, a bioassay technique was developed for evaluating sweetpotato germplasm by using adults of the banded cucumber beetle, Diabrotica balteata LeConte, and spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber. A single beetle was placed on a piece of sweetpotato peel (periderm and cortex with stele removed) that was embedded periderm-side up in plaster in a petri dish. Feeding and longevity of insects on 30 sweetpotato genotypes were evaluated in two experiments by using this procedure. Adult longevity ranged from 7 to 11 d for starved individuals to 211 d for beetles fed a dry artificial diet. Longevity of banded cucumber beetles that fed on sweetpotato peels ranged from 12 d for the most-resistant genotype to 123 d for SC1149-19, a susceptible control cultivar. Longevity of spotted cucumber beetles was slightly shorter than longevity of banded cucumber beetles. For the most resistant sweetpotato genotypes, both Diabrotica species exhibited a significant delay in initiation of feeding, and more beetles died on these genotypes before they had fed. Both antibiosis and nonpreference (antixenosis) are important mechanisms of resistance in sweetpotato genotypes. This bioassay was consistent with field results, indicating that this technique could be useful for evaluating resistance to Diabrotica spp. in sweetpotato genotypes.