Human chromosomal bands: nested structure,high-definition map and molecular basis

In this paper, we report investigations on the nested structure, the high-definition mapping, and the molecular basis of the classical Giemsa and Reverse bands in human chromosomes. We found the rules according to which the approximately 3,200 isochores of the human genome are assembled in high (850-band) resolution bands, and the latter in low (400-band) resolution bands, so forming the nested mosaic structure of chromosomes. Moreover, we identified the borders of both sets of chromosomal bands at the DNA sequence level on the basis of our recent map of isochores, which represent the highest-resolution, ultimate bands. Indeed, beyond the 100-kb resolution of the isochore map, the guanine and cytosine (GC) profile of DNA becomes turbulent owing to the contribution of specific sequences such as exons, introns, interspersed repeats, CpG islands, etc. The isochore-based level of definition (100 kb) of chromosomal bands is much higher than the cytogenetic definition level (2-3 Mb). The major conclusions of this work concern the high degree of order found in the structure of chromosomal bands, their mapping at a high definition, and the solution of the long-standing problem of the molecular basis of chromosomal bands, as these could be defined on the basis of compositional DNA properties alone.     

杂种猪染色体的核型与显带研究

应用常规方法获得了杂种猪( 野猪（♂）×家猪（♀）)的核型、C带和174条带纹的G带,应用微量秋水仙素法得到了258条带纹的高分辨G带。结果表明,杂种猪的二倍体细胞染色体数目2n=38,C带具有多态性,G带和高分辨G带与家猪相比无明显差异,它们属于同一种。 Abstract:Using usual method,we got karyotype of hybrid pig (wild soar（♂）×domestic pig（♀）),C-band and approximate 174 bands of G-band,and we also obtained approximate 258 bands of high resolution G-band by micro-Colchicin method.The result indicate that the diploid chromosome number is 2n=38;there is polymorphism in C-band,and compared with domestic pig in G-band and high resolution G-band there is no distinguish difference.They belong to the same seed.     

DNA replication asynchrony between the paternal and maternal alleles of imprinted genes does not straddle the R/G transition

Imprinted autosomal loci apparently reside in very large chromosomal domains that exhibit asynchrony in replication of homologous alleles during the DNA synthesis phase. Replication asynchrony can be cytogenetically visualized by a replication-banding discordance between homologous bands of a given pair of chromosomal homologs. The replication time of a chromosomal band at high resolution can be determined by blocking DNA synthesis at the R/G-band transition and using replication banding. The R/G transition reflects the transition from early (R-) to late (G- and C-) band DNA replication. We studied discordance between two groups of homologous chromosomal bands: (a) four bands, 6q26–27, 11p13, 11p15.5 and 15q11.2–12, each containing at least one imprinted gene; and (b) nine bands containing no known imprinted genes. Fifty pairs of chromosomes were analyzed at high resolution after R/G transition blocking and late 5-bromo-2′-deoxyuridine incorporation. The rate of discordance was the same for bands containing imprinted genes and for control bands. Both homologous bands of a pair replicate either before or after the R/G transition and do not straddle the R/G transition. Repression associated with imprinting does not appear to involve late replication at the band level of resolution. Tissue-specific inactivation is associated with DNA methylation and late replication, whereas allele-specific inactivation is associated with DNA methylation but not with delayed or late replication. Received: 7 May 1996; in revised form: 27 January 1997 / Accepted: 31 July 1997     

Pulse electrophoresis of muscle myosin heavy chains in sodium dodecyl sulfate-polyacrylamide gels

We have developed a new method that provides enhanced resolution of myosin heavy chain (MHC) isoforms by sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE). The key feature of this protocol involves the application of current to slab SDS gels in a pulsatile, repetitive manner rather than continuously as in standard gel systems. This protocol, designated pulse electrophoresis, was achieved by means of a device that intermittently gates the output of a conventional power supply. When used in long (32 cm) separating gels, pulse electrophoresis not only significantly improves the resolution of MHC isoforms compared to conventional systems, but also reduces common artifacts associated with long running times, such as blurred bands and comingling of closely spaced bands. In addition to the increased resolution of protein bands, pulse electrophoresis also allows detection of bands corresponding to previously unidentified MHC isoforms in mammalian and avian tissue. In rat myocardium, for example, pulse electrophoresis revealed three MHC isoform bands, two of which appeared to correspond to two alpha-MHC subspecies. Alternative splicing of the rat alpha-MHC gene is known to generate two isoform species differing by inclusion (or exclusion) of a single glutamine residue, whose relative levels of expression correspond nicely with the amounts of each band identified in this study. Therefore, we cannot rule out that the system presented here may be sufficiently sensitive to differentiate between high molecular weight proteins differing in a single amino acid.     

Acrylamide gel analysis of sucrose gradient-derived RNA B fractions transferring delayed sensitivity in vitro

Sucrose-derived RNA fractions transferring specific delayed sensitivity in vitro were extracted from mono-(p-azobenzenearsonate)-N-chloracetyl-l-tyrosine (ARSNAT)- or keyhole limpet hemocyanin (KLH)-sensitized guinea pigs. Fractions having biological activity were assessed by acrylamide gel analysis to enumerate the number of RNA species in active fractions, and to compare and examine the banding patterns of each RNA fraction. Each isolated B fraction of RNA exhibited multiple bands of RNA with molecular weights ranging from 4.0 × 10⁵ to 8.5× 10⁵. Depending on the source and antigen sensitivity of the RNA donor, several differences were observed among the analyzed fractions. These were bands of varying intensity, presence of additional RNA bands, absence of bands in certain positions, and RNA bands migrating in different positions on the gels. Acrylamide gel analysis separation, and resolution of B fractions with specific immunobiological activity now offers an approach for further isolation and resolution of the active species.     

中国家猪高分辨G—带及模式图

采用氨甲喋呤或胸苷阻断法使细胞分裂同步化,并结合胰酶G-带技术,对中国7个家猪品种高分辨G-带进行了研究,发现家猪品种间带型基本一致,从而参照人类细胞遗传学命名法的国际体制,提出了中国家猪高分辨G-带标准化核型及模式图,对显带核型界标进行了少许修改,对每对染色体进行了区带划分和描述。单倍染色体组所显示的G-带数目,包括X和Y染色体,巳达444条,近于中期染色体带纹数目的两倍。     

Use of a particular cellulose acetate supporting agent in the electrophoretic evaluation of human hemoglobin

576 subjects of whom 450 with hereditary anaemia and 116 normal are studied to establish the haemoglobin pattern. The assay is carried out using the standard cellulose acetate and an particular cellulose acetate medium cellogel RS "Wedge". The results show that cellogel RS in comporation with standard medium permits either an better resolution of the hemoglobin bands or a better detection of the pathologic bands.     

The G-banded prophase chromosomes of man.

Using a simple G-banding technique developed in our laboratory, analysis of late prophases enables the visualization of approximately 1000 bands in the haploid set of human chromosomes. These bands have been classified according to the recommendations of the Paris Conference. The increased resolution offered by this technique is likely to be useful in the study of the structure and molecular organization of chromosomes and in identifying minute chromosome defects in birth defects and neoplasia.     

High resolution G-banded chromosomes of the mouse

High resolution G-banded mouse chromosomes were prepared using an actinomycin D and acridine orange pretreatment protocol, resulting in late prophase mouse chromosomes which reveal over twice the number of bands as compared with mid metaphase. These elongated chromosomes, described here in detail and used to construct a precise schematic representation of the late prophase banding patterns, should be generally useful in high resolution mouse chromosome analysis.     

新一代Landsat系列卫星：Landsat8遥感影像新增特征及其生态环境意义

美国Landsat 8卫星的成功发射使一度中断的Landsat对地观测得以继续。Landsat 8除了保持Landsat 7卫星的基本特征外,还在波段的数量、波段的光谱范围和影像的辐射分辨率上进行了改进。基于该卫星的首幅影像,针对这些新的特性进行了分析和研究。研究发现:(1)新增的卷云波段有助于区别点云和高反射地物;(2)卷云波段设计的波长范围位于粘土矿物光谱反射的强吸收带,有利于土壤与建筑不透水面信息的区别;(3)新增的深蓝波段有助于水体悬浮物浓度的监测;(4)全色影像波长范围的收窄有利于该影像上植被和非植被的区别;(5)辐射分辨率的提高可避免极亮/极暗区的灰度过饱和现象,这对反射率极低的水体的细微特征识别有很大帮助。显然,Landsat 8这些新增的优点将会对全球生态环境变化的监测产生积极的作用。     

High resolution chromosome banding in the Norway rat, Rattus norvegicus

High resolution banded chromosomes were prepared from a synchronized culture of rat fibroblasts. A maximum of 457 bands per haploid chromosome set were observed. This represents a two-fold increase when compared to the number of bands visualized in mid-metaphases using standard procedures. By reference to both G- and Q-banded karyotypes, we constructed improved idiograms of rat chromosomes at 300- and 400-band stages, respectively.     

Early and late replication patterns of increased resolution in human lymphocyte chromosomes

High resolution patterns of DNA replication in human lymphocyte chromosomes during early and late S-phases were studied by means of the BrdU-Hoechst-Giemsa technique. The late replicating bands were found to be identical with highly detailed G-bands. Between early replicating bands and R-bands subtile differences were observed. A possible correlation between a replication band seen on the chromosomal level and a replication cluster observed after fiber autoradiography is discussed. Dedicated to Professor Dr. Wolfgang Beermann on the occasion of his 60th birthday     

Mapping of the pattern of DNA replication in polytene chromosome from Chironomus thummi using monoclonal anti-bromodeoxyuridine antibodies

We present results from a nonautoradiographic study of DNA replication in polytene chromosomes from dipteran larvae. Monoclonal antibodies with specificity for 5-bromodeoxyuridine (BrdUrd) were used to localize by indirect immunofluorescence the sites of BrdUrd incorporation and to follow the dynamics of DNA synthesis in salivary gland cells of 4th instar Chironomus thummi larvae. This technique presents numerous advantages over autoradiographic procedures and allows mapping of DNA synthesis patterns at the level of resolution of one chromosomal band. Several replication patterns were observed, classified according to characteristic features, and tentatively assigned to specific periods of the S-phase. In early S-phase, DNA synthesis is first detectable in puffs and interbands, later in bands. Most chromosomal bands appear to initiate DNA synthesis synchronously; however, in bands within centromeric and heterochromatic regions the start of synthesis is delayed. At mid S-phase, all the bands show uniform staining. Subsequent staining patterns are increasingly differential with the bands displaying characteristic fluorescence intensities. As replication progresses through the late S-phase period, the chromosomes show a decreasing number of fluorescent bands. The last bands to terminate replication are located in centromeric and heterochromatic DNA-rich regions and a few bands of low DNA content in region IIAa-c.     

Nonrandom distribution of exchange points in patients with structural rearrangements

High resolution studies of structural rearrangements were carried out using the G-band technique. A total of 220 breakage points were identified within individual bands from 117 unrelated cases born with a structural rearrangement. Breakage points were not evenly distributed along chromosomes in terms of G-band patterns. There was an excess involvement of light bands and a striking lack of dark bands in both reciprocal translocations and inversions. In reciprocal translocations, the middle part of a chromosome arm has less chance of being the site of an exchange than the terminal and centromeric parts. The implications of these results are briefly discussed.     

Conformation-sensitive gel electrophoresis as an ideal high-throughput strategy for accurate detection of sequence variations in DNA: screening hTomm and hTimm genes

Conformation-sensitive gel electrophoresis is a heteroduplex-based method that is particularly well suited to high-throughput analyses. Its simplicity makes it amenable to various adaptations and modifications to enhance its applicability to genome-wide mutation scans. Technical aspects that markedly improve the conformation-sensitive gel electrophoresis performance by combining high throughput and high resolution of the bands facilitating the interpretation of the results are described here. The authors report some of the results they have obtained in the screening of the exon 1 of human Timm8A gene as an example of the suitability of the conformation-sensitive gel electrophoresis-based protocol that has been adapted to optimize its throughput, speed, and simplicity in the recognition of both heterozygous and homozygous DNA mutations. The higher throughput is achieved by using 12 batches per gel. The length of the gel is sufficient for an adequate well-to-read distance for each batch that allows a clear distinction and resolution of the conformation-sensitive gel electrophoresis bands. Standardization of the procedure using multichannel pipettes reduces the preparation time of the 96-well PCRs to 10 min and also accelerates the gel loading. The resulting bands give high-quality images, allowing easy detection of known as well as novel mutations.     

猕猴桃AFLP分析体系的建立

从64对AFLP分析引物中随机选取了19对引物组合。经过跑小板的聚丙烯酰胺凝胶,银染显带AFLP条带,从中筛选出可做荧光的8对引物。再从中选取了扩增位点丰富,带型质量好,分辨率较高,条带信号强度一致性好,条带分布均匀,且条带较完整的4对引物：E-AAC＋M-CAC、E-AAG＋M-CTG、E-AAC＋M-CAG、EAAC＋M-CTA进行荧光跑带、读带。共在156个位点上扩增出条带,4对引物共扩增出多态性条带132条,多态性比例平均为84．62％,4对引物对10份猕猴桃材料的区分率达100％。说明该4对引物用于猕猴桃属植物的AFLP分析是可行的。     

Preliminary investigation of the phage phi X174 crystal structure

Crystals of the single-stranded DNA bacteriophage phi X174 have been grown. They have a monoclinic unit cell with space group P2(1), unit cell dimensions of a = 306.0 (+/- 0.2) A, b = 361.1 (+/- 0.2) A, c = 299.7 (+/- 0.2 degrees) A, beta = 92.91 degrees (+/- 0.02 degrees) and diffract to at least 2.7 A resolution. There are two virus particles per unit cell. Packing considerations show that the mean diameter of the virus particles is 280 A. The virus separates into two bands in a sucrose gradient. The ratio between the absorbance at 260 nm and 280 nm is 1.45 to 1.65 for the faster and 1.15 to 1.35 for the slower bands, but both bands contain intact particles. Crystals derived from these bands are isomorphous and there is no detectable difference in their structure amplitudes.     

基于小波变换的土壤有机质含量高光谱估测

利用统计分析方法选取了土壤N、P、K元素含量近似而有机质含量差异较大的样本60个,通过高光谱探测分析获得样本反射率对数的一阶导数光谱,采用Bior 1.3函数进行多层离散小波分解,剔除低频近似信号和高频噪声信号,得到反映土壤理化参数的特征光谱曲线;采用相关分析筛选土壤有机质含量的显著相关波段,基于显著相关波段和特征光谱曲线分别构建土壤有机质含量高光谱多元回归估测模型;通过比较分析,确定了提取土壤有机质特征光谱的最佳小波分解尺度并构建了最佳预测模型.结果表明： 提取土壤有机质特征光谱的最佳小波分解层数是9层,其次是8层和10层;基于小波9层分解特征光谱曲线的有机质含量估测模型最佳,其决定系数（R²）为0.89,比基于显著相关波段构建模型的R²增加了0.31,比基于原始光谱所构建模型的R²增加了0.10.