Centromere inactivation in a dicentric rice chromosome during sexual reproduction

T0135 is a variant selected from the progeny of a rice line telotrisomic for the short arm of chromosome 11 （2n＋IIS＇）. Fluores- cent in situ hybridization （FISH） results indicated that T0135 contained two telocentric chromosomes, which have two centro- mere-specific molecular markers （5S rDNA） for chromosome 11; thus T0135 is a newly-described rice chromosome variant with two dicentric chromosomes, named 22＋11L-＋11L＇＋I IS.11S-＋I 1S-11S. （22 represents the 22 chromosomes excluding chromo- some 11 in the rice genome, ＂-＂ represents the centromere）. To investigate the genetic stability of the rice dicentric chromosomes during sexual reproduction, we observed the chromosome types in the progeny. Ninety-four percent of the progeny had the same chromosome type as the parental line. This result indicates that the dicentric chromosomes are mostly stable during mitosis and meiosis. Immunofluorescence analysis for centromere specific histone H3 （CENH3） revealed that only one centromere is active and the other centromere is inactivated in the rice dicentric chromosomes.     

Physical location of the ricePi-5(t), Glh andRTSV genes by ISH of BAC clones

Mapping of low or single-copy sequences on plant chromosomes has proven difficult because of very low frequency of signal detection. Rice BAC library is being used widely in rice genome research due to its distinctive advantages over other library systems. In this study, two biotin-labeled rice BAC clones closely linked to a rice blast resistance, green leafhopper resistance and tungro spherical virus resistance gene,Pi-5(t), Glh, RTSV, werein situ hybridized to rice chromosomes. They were located on the long arm and short arm of chromosome 4 with FL value of 40% and 100% respectively. The frequency of signal detection reached 46.8% and 59.2%. The signal location were consistent with the selective marker on rice saturated molecular map. The results demonstrated the advantages to locate BAC clones to chromosomes byin situ hybridization and will facilitate the rice low or single-copy gene location by using the BAC library. Supported by the National Natural Science Foundation of China and the Doctorate Vesting Point Foundation of the Education Department of the People's Republic of China Yan Huimin: born in 1964, Lecturer     

Comparative physical mapping of rice BAC clones linked to resistance genes Glh,Bph-3 and xa-5 in Oryza sativa L. and O. granulata Nees et Arn. ex Watt.

Oryza granulata Nees et Arn. ex Watt. is one of the three wild relatives of rice,which are the most valuable for study and utilization in China.In this study,the homology and physical locations of three rice resistance genes,Glh,Bph-3 and xa-5 are comparatively analyzed between O.sativa and O. granulata by Southern blotting and fluorescence in situ hybridization (FISH).The results of Southern blotting indicate that there exist homologous sequences of the tested RFLP markers in O. granulata.By using three bacterial artificial chromosome (BAC) clones scanned by the tested RFLP as probes, FISH signals are detected on both mitotic and pachytene chromosomes in O.sativa and O.granulata.Dual-color FISH demonstrates that two of the three BAC clones (14E16 and 38J9) are located on the short arm of the same chromosome pair in O. granulata. Additionally, colinearity is shown for the two clones between O.sativa and O.granulata. Another BAC clone 44B4 is located on the end of the short arm of other chromosome pair in these two species.Although the phylogenetic relationship between O.sativa and O.granulata is the most distinct in Oryza and these two species have evidently different biological features and ecological habits, the relative lengths and arm ratios of the detected chromosomes and the relative positions of the tested clone signals on chromosomes in O. granulata are quite similar to those in O. sativa.     

玉斑锦蛇染色体研究

目的通过研究玉斑锦蛇Elaphe mandarina的染色体核型和带型,为探讨锦蛇属的分类和亲缘关系提供重要的证据。方法以产于贵州的玉斑锦蛇Elaphe mandarina为研究材料,应用染色体的核型、C带、银带分析技术。结果玉斑锦蛇的核型为2n=38,含有20个大型染色体和18个小型染色体;每条大型染色体两端均具端粒区C带;第1,2,5,7号染色体具着丝粒区C带;第4号和第5号染色体中的一条同源染色体C带浓染,几乎占据整条染色体;标准NORs位于第11号染色体。结论玉斑锦蛇是迄今已报道的锦蛇属中染色体数目最多、端粒区C带最多的物种;锦蛇属的标准NORs具有属的银染特征。     

Chromosome sorting and its applications in common wheat (Triticum aestivum) genome sequencing

The large genome size (～17000 Mb) and complicated DNA structures of common wheat (Triticum aestivum) hamper its genome sequencing.By means of flow cytometry,systematic investigations on individual chromosome sorting have been carried out to construct chromosome-specific bacterial artificial chromosome (BAC) libraries since the 1980s.Several wheat chromosome-specific BAC libraries,such as chromosome 3B,three D genome chromosomes (1D,4D and 6D),and the short arm of chromosome 1B,have been developed,and the ph...     

Knob-associated tandem repeats on mitotic chromosomes in maize,Zea diploperennis and their hybrids

Knob-associated tandem repeats, 180-bp repeats and TR-1 elements, together with 45S rDNA were located on mitotic chromosomes of Zea diploperennis (DP),maize inbred line F102 and their hybrid. In DP, knobs on the short arm of chromosomes 1 and 4 and on the long arm ofthe chromosomes 4 and 5 are composed predominantly of the 180-bp repeats. In addition, 180-bp repeats existed together with TR-1 elements were also detected on the short arm ofchromosomes 2 and 5 and on the long arm of the chromosomes 2, 6, 7, 8 and 9. In maize inbred line F102, 180-bp repeats were present in chromosomes 7S and one homologue of chromosomes 8L. TR-1 elements appeared on satellite of chromosome 6 and no detectable hybridization site co-located with 180-bp repeats was observed in maize F102.Polymorphism of size, number, and distribution of 180-bp and TR-1 signals were revealed among different chromosomes in these two species and heteromorphism existed between some homologous chromosomes in the same species.Using these excellent landmarks, the interspecific hybrid of maize and DP were identified. The results suggest that comparative analysis of 180-bp repeats and TR-1 elements may help understand the genome organization and the evolution in Zea.     

泸定百合根尖染色体C-带分析

利用Giemsa C-带方法对泸定百合(Lilium sargentiae Wilson)进行了研究.结果表明:泸定百合的染色体数目为2n=24,每条染色体都显示出了可以明显区别的特征带;强带主要集中在染色体的着丝粒区域,在长短臂上也显示出可以相互识别的深浅不一的带纹.通过Giemsa C-带方法可以将泸定百合的每条染色体区分开.     

Genetic analysis of rice allelopathy

A double haploid population derived from anther culture of ZYQ8/JX17,a typical indica and japonica hybrid,was used in this study.The inhibited effect of water-soluble extract of 123 DH pure lines leaves on the lettuce roots growth was investigated,and the QTLs analysis of rice allelopathy was carried out.Totally,four QTLs related to rice allelopathy were detected,and they were on chromosomes,3,9,10 and 12,respectively.The LOD scores were 3.40,2.68,2.75 and 3.08,respectivel.Among them,additive effects of the QTLs on chromosomes 3 and 10 were 1.65 and 1.43,on chromosomes 9 and 12 were-1.44 and -1.58 respectively.Allelopathy characteristics of another three common rice varieties were also studied.     

长爪沙鼠1～5号染色体G显带特征初步研究

目的　通过易于区分的 1～ 5号长爪沙鼠染色体G显带特性研究 ,逐步建立完整的长爪沙鼠G带染色体细胞遗传学背景资料。方法　取 6只成熟长爪沙鼠 ,雌雄各半 ,采用外周血进行淋巴细胞培养 ,获得分裂中期细胞染色体标本制片 ,以胰蛋白酶处理 ,选 1周龄标本染色观察。结果　长爪沙鼠染色体指数表明 ,1～ 5号染色体以相对长度、着丝点位置易于排列。 1号染色体与 2号染色体各有八条深染带纹 ,可以着丝点位置加以区分。 3号染色体有六条深染带纹 ,位于着丝点附近和长臂与短臂中部无穷侧端。 4号染色体与 5号染邑体均有四条深染带 ,5号染色体短臂深染带纹位于着丝点一侧可予以区分。结论　长爪沙鼠 1～ 5号染色体有较稳定的基本深染G带型 ,可做为染色体区带划分的重要标界。     

Physical location of riceGm-6, Pi-5(t) genes inO. officinalis with BAC-FISH

A fluorescence in situ hybridization (FISH) procedure was adopted to physically map two rice BAC clones 24E21 and 4F22 linked to Gm-6 and Pi-5(t) in O. offi-cinalis. FISH results showed that the two BAC clones were located at 4L. The percentage distance from the centromere to the hybridization sites was 72 + 2.62 for 24E21 and 54+ 5.43 for 4F22, the detection rates were 52.70% and 61.2%. The results obtained from the BAC and plasmid clones, RG214 and RZ565 of cultivated rice and O. officinalis were the same. This suggested that the markers, RG214 and RZ565 of cultivated rice and O. officinalis were in the same BAC clones. The homologous sequences of Gm-6 and Pi-5(t) in O. officinalis were positions that signals existed on the 4L. Many signals were observed when no Cot-1 DNA blocked. This also showed that repetitive sequences were some ho-molgous between cultivated rice and O. officinalis. The identification of chromosome 4 of O. officinalis is based on Jena et al. (1994). In our study, we discussed the possibility of physical map in O. officinalis with rice BAC clones.     

Loss of genes on the short arm of chromosome 11 in bladder cancer

Recent studies have shown that normal cellular sequences on chromosome 13 are lost during the development of retinoblastomas and that sequences on chromosome 11 are similarly lost during the development of Wilms' kidney tumours and embryonal tumours. Cells from these tumors have been found to contain either the paternal or maternal copies of loci on the affected chromosome, but not both. Thus, the somatic loss of heterozygosity for sequences on chromosome 13 or 11 is hypothesized to result in homozygosity for a recessive mutant allele on these chromosomes, and in this way the chromosomal loss may contribute to the development of these tumours. We sought to investigate whether similar losses of heterozygosity for chromosome 11 sequences occurred in a common adult tumour. We chose to analyse bladder cancers, since such cancers are common in the adult population and are derived from urogenital tissue, as are Wilms' tumours. We examined constitutional and tumour genotypes at loci on the short arm of chromosome 11 (11p) in 12 patients with transitional cell carcinomas. In five tumours, we observed the somatic loss of genes on 11p resulting in homozygosity or hemizygosity of the non-deleted alleles in the tumour cells. Our results show that the frequency of loss of 11p sequences in bladder cancer approaches that seen in Wilms' tumour (42% compared with 55%), and suggest that recessive genetic changes involving sequences on 11p may contribute to the development of bladder neoplasms.     

吊竹梅的核型研究

本文首次报道了吊竹梅(Zebrina pendula Schnizl.)核型。其体细胞染色体数目2n=24。具有2对中部着丝点染色体,3对近端部着丝点染色体和7对端部着丝点染色体,未见次缢痕和随体。染色体的长度比为2.58,臂比大于2的百分比为0.25,属Stebbins核型分类的“2B”型。     

药百合根尖染色体C带分析

利用Giemsa C带方法对药百合(Lilium speciosum Thunb. var. glorosoides Baker)进行了研究。结果表明：药百合的染色体数目为2n=2x=24,带型公式为：2n=24=8C+4CI++2CI++2CN+4I++2I+T++2,单套染色体条带总数为20条。染色体A、E、H、J、K的着丝点区域和染色体F的短臂上显示出很强的带纹,染色体 A为随体染色体,具有明显的次缢痕带,染色体B的短臂上显示出3条强弱不同的带纹。通过Giemsa C带方法可以将药百合的每条染色体区分开,药百合C带带纹的这些特征将为其在杂交育种中后代的鉴定及特异基因的染色体定位提供可靠的依据。     

舍蝇染色体组型分析

本文对舍蝇的染色体组型进行了分析研究,绘制了组型模式图。舍蝇的染色体组型2n=12,染色体臂数为24(N.F),配成六对。五对染色体属于中部和亚中部着丝粒染色体,其中有一对为异型染色体(X、Y)。舍蝇染色体组型的分析为研究其他家蝇的分类,亲缘关系提供了参考资料。     

胡子鲶的染色体组型研究

本文报导对胡鲶科(Clariidae)中胡子鲶Clatias fuscus(Lacépède)的染色体组型进行的初步研究。实验结果表明:胡子鲶体细胞的染色体数目为2n=56,核型公式为18m+14sm+14st+10t,NF=88,总的来说m和sm组染色体较st和t组的染色体略为增多,因而基本臂数不高。在t_4染色体的短臂上具有一对明显而恒定的随体。     

两种短棘猬染色体组型分析

本文报道了达乌尔猬和秦岭短棘猬的染色体组型。发现达乌尔猬的染色2n=44,秦岭短棘猬2n=48。对这两种短棘猬染色体组型进行了分析,并对分类上争论的问题进行了探讨。     

Hereditary spherocytosis associated with deletion of human erythrocyte ankyrin gene on chromosome 8

Hereditary spherocytosis (HS) is one of the most common hereditary haemolytic anaemias. HS red cells from both autosound dominant and recessive variants are spectrin-deficient, which correlates with the severity of the disease. Some patients with recessive HS have a mutation in the spectrin alpha-2 domain (S.L.M. et al., unpublished observations), and a few dominant HS patients have an unstable beta-spectrin that is easily oxidized, which damages the protein 4.1 binding site and weakens spectrin-actin interactions. In most patients, however, the cause of spectrin deficiency is unknown. The alpha- and beta-spectrin loci are on chromosomes 1 and 14 respectively. The only other genetic locus for HS is SPH2, on the short arm of chromosome 8 (8p11). This does not correspond to any of the known loci of genes for red cell membrane proteins including protein 4.1 (1p36.2-p34), the anion exchange protein (AE1, band 3; 17q21-qter), glycophorin C (2q14-q21), and beta-actin (7pter-q22). Human erythrocyte ankyrin, which links beta-spectrin to the anion exchange protein, has recently been cloned. We now show that the ankyrin gene maps to chromosome 8p11.2, and that one copy is missing from DNA of two unrelated children with severe HS and heterozygous deletions of chromosome 8 (del(8)(p11-p21.1)). Affected red cells are also ankyrin-deficient. The data suggest that defects or deficiency or ankyrin are responsible for HS at the SPH2 locus.     

辽宁产中国林蛙染色体核型及银带研究

通过对染色体核型及银带的研究来建筑辽宁产中国林蛙在染色体水平上的雌雄差异。核型分析表明,辽宁产中国林蛙有１２对染色体,根据相对长度可以分为组：Ａ为相对长度〉１０％者;Ｂ为相对长度在７％－１０％之间者;Ｃ为相对长度〈７％者,第１１对染色体长臂中部有明显的次缢痕,雌雄个体间略有差异。     

Construction of a BAC library from cucumber （Cucumis sativus L.） and identification of linkage group specific clones

A bacterial artificial chromosome （BAC） library consisting of 19,200 clones with an average insert size of 105 kb has been constructed from a cucumber （Cucumis sativus L.） inbred line S94, derived from a cultivar in North China. The entire library was equivalent to approximately 5 haploid cucumber genomes. To facilitate chromosome engineering and anchor the cucumber genetic linkage map to its chromosomes, 15 sequence-characterized amplified regions （SCAR） and seven simple sequence repeats （SSR） markers from each linkage group of cucumber were used to screen an ordered array of pooled BAC DNA with polymerase chain reaction （PCR）. Fifteen markers gave at least two positive clones. As a result, 22 BAC clones representing 7 linkage groups of cucumber were identified, which further validated the genome coverage and utility of the library. This BAC library and linkage group specific clones provide essential resources for future research of the cucumber genome.     

Occurrence of a transposition from the X-chromosome long arm to the Y-chromosome short arm during human evolution

DXYS1, a site showing greater than 99% DNA sequence homology between the human X and Y chromosomes, maps to the X long arm and to the Y short arm. In great apes, sequences homologous to DXYS1 are found only on the X chromosome. These findings suggest an X-Y transposition during human evolution.