满族新生儿血红蛋白F中G_γ／A_γ比值测定及其异常者γ－珠蛋白基因图谱分析

以聚丙烯酰胺凝胶电泳方法测定了３３１例辽宁满族新生儿脐带血血红蛋白Ｆ中Ｇγ／Ａγ比值。结果显示：高Ｇγ（＞８０％）者４例,占１．２１％,其基因频率（ｆ）为０．００６０４,低Ｇγ（３０－４８％）者６例,占１．８１％,其基因频率为０．００９０６,其余正常,Ｇγ平均值为６５．２３±６．３８％。未发现ＡγＴ链。对其中八例异常者（４例高Ｇγ值,４例低Ｇγ值）的染色体ＤＮＡ进行了基因图谱分析,确定４例高Ｇγ值者基因型有两种：Ｇγ－Ｇγ／Ｇγ－Ａγ二例,Ｇγ－ＡＧγ－Ａγ／Ｇγ－Ａγ二例;４例低Ｇγ值者基因型有二种,分别为：Ａγ－Ａγ／Ｇγ－Ａγ二例和－ＧＡγ／Ｇγ－Ａγ二例。其中Ａγ－Ａγ基因型在中国人群中未见报道过。     

Construction and characterisation of a yeast artificial chromosome library containing five haploid sugarbeet (Beta vulgaris L.) genome equivalents

A yeast artificial chromosome (YAC) genomic library of Beta vulgaris was constructed in the pYAC4 vector. High-molecular-weight DNA was prepared from agarose-embedded leaf protoplasts from a triploid cultivar. The library was found to contain 33,500 clones in an ordered array of microtiter plates. Mean size of the inserts was estimated to be 135 kb, and the library should therefore represent the equivalent of five haploid genomes. The library was characterised for the presence of highly repetitive, chloroplast and single-copy sequences. In order to isolate single-copy sequences, 18 pools of DNA, each from 1920 individual YAC clones, were prepared for rapid screening of the library by the polymerase chain reaction. The results of these screenings showed that the number of isolated clones was at or near the frequency expected.     

Using homology modeling to interrogate binding affinity in neutralization of ricin toxin by a family of single domain antibodies

In this report we investigated, within a group of closely related single domain camelid antibodies (V_HHs), the relationship between binding affinity and neutralizing activity as it pertains to ricin, a fast‐acting toxin and biothreat agent. The V1C7‐like V_HHs (V1C7, V2B9, V2E8, and V5C1) are similar in amino acid sequence, but differ in their binding affinities and toxin‐neutralizing activities. Using the X‐ray crystal structure of V1C7 in complex with ricin's enzymatic subunit (RTA) as a template, Rosetta‐based homology modeling coupled with energetic decomposition led us to predict that a single pairwise interaction between Arg29 on V5C1 and Glu67 on RTA was responsible for the difference in ricin toxin binding affinity between V1C7, a weak neutralizer, and V5C1, a moderate neutralizer. This prediction was borne out experimentally: substitution of Arg for Gly at position 29 enhanced V1C7's binding affinity for ricin, whereas the reverse (ie, Gly for Arg at position 29) diminished V5C1's binding affinity by >10 fold. As expected, the V5C1_R29G mutant was largely devoid of toxin‐neutralizing activity (TNA). However, the TNA of the V1C7_G29R mutant was not correspondingly improved, indicating that in the V1C7 family binding affinity alone does not account for differences in antibody function. V1C7 and V5C1, as well as their respective point mutants, recognized indistinguishable epitopes on RTA, at least at the level of sensitivity afforded by hydrogen‐deuterium mass spectrometry. The results of this study have implications for engineering therapeutic antibodies because they demonstrate that even subtle differences in epitope specificity can account for important differences in antibody function.     

Matching structural densities from different biophysical origins with gain and bias

The registration of volumetric structures in real space involves geometric and density transformations that align a target map and a probe map in the best way possible. Many computational docking strategies exist for finding the geometric transformations that superimpose maps, but the problem of finding an optimal density transformation, for the purposes of difference calculations or segmentation, has received little attention in the literature. We report results based on simulated and experimental electron microscopy maps, showing that a single scale factor (gain) may be insufficient when it comes to minimizing the density discrepancy between an aligned target and probe. We propose an affine transformation, with gain and bias, that is parameterized by known surface isovalues and by an interactive centering of the “cancellation peak” in the surface thresholded difference map histogram. The proposed approach minimizes discrepancies across a wide range of interior densities. Owing to having only two parameters, it avoids overfitting and requires only minimal knowledge of the probe and target maps. The linear transformation also preserves phases and relative amplitudes in Fourier space. The histogram matching strategy was implemented in the newly revised volhist tool of the Situs package, version 2.6.     

基于F—2群体的鸡重要生长性状遗传分析

采用F-2设计,以丝羽乌骨鸡(C系)为一亲本,分别与农大褐蛋鸡(B系),及法国明星肉鸡(A系)进行正反交,产生了包含A×C,C×A;B×C,C×B4个杂交组合的F2代群体,建立了可用于定位产肉及产蛋等性状QTL的资源群体.基于这一F-2群体,对体重及日增重等性状表型值进行分析,结果显示,亲本间均值差异显著,分离群体变异大,这组性状间有中等或较高的相关,各性状潜在的QTL座位数不超过10,所建资源家系能够满足QTL定位所需的样本数量,达到了预期的效果.     

Identification of a stable quantitative trait locus for percentage grains with white chalkiness in rice (Oryza sativa)

High chalkiness is a major problem in many rice-producing areas of the world, especially in hybrid rice (Oryza sativa L.) in China. We previously showed a major quantitative trait locus for the percentage of grains with white chalkiness (QTLqPGWC-8) in the interval G1149-R727 on chromosome 8 using a chromosome segment substitution line (CSSL). Here, we selected the line-CSSL50 harboring the QTLqPGWC-8 allele from the CSSLs derived from a cross between Asominori (as a recurrent parent) and IR24 (as a donor parent), which had higher percentage chalkiness, markedly different from that of Asominori. There were also significant differences in starch granules, appearance of amylose content (AAC) and milling qualities between Asominori and CSSL50, but not in grain size or thousand grain weight (TGW). The BC(4) F(2) and BC(4) F(3) populations from a cross between CSSL50 and Asominori were used for fine mapping of qPGWC-8. We narrowed down the location of this QTL to a 142 kb region between Indel markers 8G-7 and 8G-9. QTLqPGWC-8 accounted for 50.9% of the difference in PGWC between the parents. The markers tightly linked to qPGWC-8 should facilitate cloning of the gene underlying this QTL and will be of value for marker-assisted selection in breeding rice varieties with better grain quality.     

基于CSSLs群体定位和图位克隆水稻长芒基因GAD1-2

水稻是世界上最早驯化的重要粮食作物之一。水稻芒可以保护水稻种子不被鸟琢食,是水稻重要的驯化性状之一。芒在野生稻中普遍存在,对野生稻的生存和传播至关重要,然而在驯化和人工选择过程中该性状逐渐被淘汰。定位和克隆水稻长芒相关基因是研究水稻芒驯化遗传机制的基础。本研究以籼稻恢复系东南恢810为受体、漳浦野生稻为供体构建的146个染色体片段置换系(chromosome segment substitution lines, CSSLs)为研究材料,调查了146个CSSLs株系和双亲的芒长,结果表明在4个置换系中检测到1个控制水稻芒长主效基因GAD1-2,位于水稻第8号染色体;利用重叠代换作图法,将GAD1-2定位在Ind8-10和RM4936标记之间,遗传距离约为4.75 Mb。选择分离群体中的显性单株,利用开发的标记,最终将GAD1-2 基因定位在两个 Indel 标记之间,两者间的物理距离约为27 kb,该区域内只有两个候选基因Os08g0485500和Os08g0485400。经测序和分析表明,Os08g0485500是GAD1-2的候选基因,GAD1-2在保守的ORF区域存在6个碱基缺失,导致丝氨酸和半胱氨酸这两个氨基酸缺失,从而表现长芒的性状;在Os08g0485500基因位点已克隆了1个控制水稻芒长的GAD1基因,推测GAD1-2与GAD1为等位基因。本研究为进一步理解水稻起源演化和水稻芒长发育基因的遗传机制奠定了基础。     

Construction of recombinant plasmids containing rat thyroglobulin mRNA sequences

Two plasmids containing rat thyroglobulin cDNA sequences have been constructed and characterized. A plasmid with a 500-bp insert (pRT6) was isolated and identified as thyroglobulin-specific on the basis of the tissue specificity of the inserted sequence and of its ability to retain thyroglobulin mRNA on a nitrocellulose filter. The cDNA insert in pRT6 was subsequently used to screen a rat thyroid cDNA library constructed with large cDNA. A plasmid was found containing a 1700-bp insert. The polarity and the fidelity of the insert is demonstrated by S1 mapping.     

Comparative mapping of the wheat chromosome 5A Vrn-A1 region with rice and its relationship to QTL for flowering time

 The vernalization gene Vrn-A1 on chromosome 5A is the predominant gene determining the spring/winter habit difference in bread wheat. Vrn-A1 was physically mapped using a set of deletion lines which located it to the region of chromosome 5A flanked by deletion breakpoints 0.68 and 0.78. This interval was shown to be homoeologous to a region of rice chromosome 3 that contains the flowering-time QTL Hd-6, previously mapped in a Nipponbare×Kasalath cross, and FLTQ1, a novel QTL identified by analysis of 78 F₃ families derived from a cross of ‘IR20’ב63–83’. Possible relationships between Vrn-A1 and rice QTL are discussed. Analysis of the chromosome 5A deletion lines showed evidence for a second, more proximal flowering-time effect located between deletion breakpoints 0.56 and 0.64. The proximal part of chromosome 5A is homoeologous to rice chromosome 9, on which two QTL were detected in the ‘IR20ב63–83’ cross. The possible relationship between these effects is also discussed. Received: 23 December 1997 / Accepted: 12 January 1998     

A fine physical map of the rice chromosome 5

A fine physical map of the rice (Oryza sativa spp. Japonica var. Nipponbare) chromosome 5 with bacterial artificial chromosome (BAC) and PI-derived artificial chromosome (PAC) clones was constructed through integration of 280 sequenced BAC/PAC clones and 232 sequence tagged site/expressed sequence tag markers with the use of fingerprinted contig data of the Nipponbare genome. This map consists of five contigs covering 99% of the estimated chromosome size (30.08 Mb). The four physical gaps were estimated at 30 and 20 kb for gaps 1–3 and gap 4, respectively. We have submitted 42.2-Mb sequences with 29.8 Mb of nonoverlapping sequences to public databases. BAC clones corresponding to telomere and centromere regions were confirmed by BAC-fluorescence in situ hybridization (FISH) on a pachytene chromosome. The genetically centromeric region at 54.6 cM was covered by a minimum tiling path spanning 2.1 Mb with no physical gaps. The precise position of the centromere was revealed by using three overlapping BAC/PACs for ~150 kb. In addition, FISH results revealed uneven chromatin condensation around the centromeric region at the pachytene stage. This map is of use for positional cloning and further characterization of the rice functional genomics. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. Chia-Hsiung Cheng and Mei-Chu Chung have equal contributions.