协青早B//协青早B/东乡野生稻BC1F9群体低磷耐性鉴定及其生理机制

通过水培法对协青早B//协青早B/东乡野生稻BC₁F₉群体221个株系低磷耐性进行了鉴定,测定了株高、叶龄、黄叶数、地上部干物质量等形态指标及丙二醛（MDA）、可溶性糖和地上部磷含量等生理指标,计算了磷效率,并对各指标间相关性进行了分析.结果表明：221个株系的7个指标均显示出差异性,耐性株系在低磷胁迫下表现为相对叶龄、相对株高、相对地上部干物质量和相对可溶性糖含量较高,相对黄叶数和相对MDA含量较低,相对地上部磷含量差异不明显;磷效率与磷利用效率和磷吸收效率均呈正相关,其中磷利用效率与磷效率达到极显著水平（P<0.01）,表明东乡野生稻回交重组自交系中耐性株系低磷耐性原因主要是具有高磷利用效率,即其单位吸磷量干物质合成力较高.     

Anti-Rous sarcoma response of major histocompatibility (B) complex haplotypes B23, B24 and B30

Responses to Rous sarcoma virus (RSV) induced tumours were studied in UNH 105, a non-inbred line of New Hampshire chickens. Six single male matings encompassing a total of 50 dams produced 345 progeny which segregated for B complex genotypes B23/B23, B23/B24, B23/B30, B24/B24, B24/B30 and B30/B30. Six-week-old chicks were wingweb inoculated with a pseudotype of Bryan high titre Rous sarcoma virus, BH RSV (RAV-1). Tumours were scored for size six times over a 10-week period post-inoculation. Each chick was assigned a tumour profile index (TPI) as an indicator of immunological response. The number of days to death (DTD) was recorded for 148 chicks with terminal tumours. Genotypes B23/B23, B23/B24 and B23/B30, with TPIs of 1.8, 1.7 and 2.0 respectively, did not differ significantly from each other, suggesting dominance of response of B23 over B24 and B30 haplotypes. B24/B30 chicks with the highest TPI (3.4) and shortest DTD (34.6) were significantly different from B30/B30 (2.8; 41.6) but not from B24/B24 (3.1; 34.9) suggesting dominance of response of the B24 haplotype over B30 in the absence of B23.     

A 13C-n.m.r. spectral study of chondroitin sulfates A,B, and C: evidence of heterogeneity

Chondroitin sulfates A, B, and C produce well-resolved ¹³C-n.m.r. spectra which allow for a more complete characterization than that available from their p.m.r. spectra. The ¹³C data fully support earlier evidence as to the main structural features of these glycosaminoglycans, but they also show that many chondroitin preparations are substantially heterogeneous in composition. Thus, spectra of chondroitin A and C have the appearance of composites representative of both types of polymer: specimens of A may contain 25% of the C-type of structural sequence, and C, 30% of the A-type of sequence; 10–20% of unidentified constituents, including a residue bearing a 6-sulfate group, are present in the specimens of chondroitin B. Chemical-shift and ¹J_C-H values found for the L-iduronic acid residues of chondroitin B, as well as the effect of gadolinium nitrate on the relaxation properties of its ¹³C nuclei, indicate that this moiety possesses the α configuration and favors the ¹C₄(L) conformation. Corresponding data for the acetamidodeoxy-D-galactose and D-glucuronic acid residues of the chondroitins are consistent with the β-anomeric configuration and ⁴C₁(D) conformation in all instances.     

沉默大豆GmWRKY33B基因导致大豆抗病性降低

WRKY转录因子基因家族是植物特有的转录因子,在防御中起着重要作用。通过生物信息学分析,本研究在古四倍体大豆(Glycine max)基因组中找到一对同源性高达93%的WRKY33同源基因,并将其命名为GmWRKY33B。从GmWRKY33B的两个同源基因保守区域选取一个315 bp片段构建至菜豆豆荚斑驳病毒(bean pod mosaic virus, BPMV)沉默载体(BPMV-VIGS)上,以期同时沉默上述2个GmWRKY33B基因。结果表明,同时沉默2个GmWRKY33B基因并不显著改变沉默植株的表型,但却显著降低了大豆对大豆斑点病菌以及大豆花叶病毒的抗性,说明GmWRKY33B在大豆免疫反应中起正调控作用。激酶分析表明,GmWRKY33B沉默植株中flg22诱导的GmMPK6的磷酸化水平较空载体BPMV-0植株显著降低,说明GmWRKY33B可以通过调控GmMPK6的激酶活性而参与大豆的免疫反应。抗毒素为大豆中主要起防御作用的植保素,而大豆异黄酮类特异性异戊烯基转移酶(prenyltransferase, PT)基因家族是参与大豆抗毒素生物合成的主要基因,许多PT基因启动子区含有与WRKY特异性结合的W-box序列。在丁香假单胞菌pv.甘氨酸(Pseudomonas syringae pv. glycinea, Psg)侵染条件下,4个PT基因的表达水平在沉默株系中显著降低,说明GmWRKY33B参与PT基因的转录激活。综上所述,GmWRKY33B通过调控GmMPK6的激活以及调控大豆抗毒素生物合成途径中关键酶编码基因的表达而参与免疫反应。     

Multi-nuclear (119Sn, 13C, 1H), fourier-transform,N.M.R. studies of di- and tri-butylstannyl ethers of carbohydrates

¹¹⁹Sn-N.m.r. spectra are reported for toluene solutions of the tributylstannyl ethers of 2,3,4,6-tetra-O-methyl-d)-glucose, 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose, methyl 2,3-di-O-methyl-α-d-glucopyranoside, and methyl 4,6-O-benzylidene-α-d-glucopyranoside, and the dibutylstannyl ether of the last sugar. In the reaction of bis(tributyltin) oxide with methyl 4,6-O-benzylidene-α-d-glucopyranoside in toluene, HO-3 is much more reactive than HO-2. The presence of the various tin-containing species is readily apparent from the ¹¹⁹Sn-spectra. The importance of suppressing the nuclear Overhauser effect is demonstrated. The appearance of ¹¹⁹Sn satellites in the ¹³C-n.m.r. spectra demonstrates couplings of the types, ²J(¹¹⁹Sn-O-¹³C) and ³J(¹¹⁹Sn-O-C-¹³C), forthe first time, and, together with the ¹³C-chemical shifts, facilitates the determination of the site of substitution. The ¹¹⁹Sn-chemical shifts show that different states of coordination may be recognised. However, although different sites of substitution produce separate resonances, no simple relationship between shift and position is found. ¹³C-Chemical shifts are reported for methyl 4,6-O-benzylidene-α-d-glucopyranoside and its tributylstannyl ethers, and substituent effects are discussed.     

木薯UGT41基因对细菌性枯萎病的抗性研究北大核心CSCD

糖基转移酶广泛存在于植物中,其中UDP依赖型糖基转移酶(UDP-glycosyltransferases,UGTs)基因家族是糖基转移酶中的一大类。该研究以华南124木薯品种(Manihot esculenta cv.SC124)为材料,利用RT-PCR技术克隆木薯MeUGT41基因,以病毒诱导干扰木薯MeUGT41基因的表达量,并对基因干扰植株进行细菌性枯萎病抗性评价,为研究MeUGT41基因在木薯抵抗细菌性枯萎病的抗病机理奠定基础。结果表明:(1)地毯草黄单胞菌(Xamthomonas axonopodis pv.Manihotis,Xam)可显著诱导木薯MeUGT41基因表达。(2)成功构建MeUGT41的病毒诱导基因沉默(VIGS)载体,将干扰载体转化至木薯叶片进行MeUGT41基因沉默,荧光定量PCR检测结果显示,木薯叶片中MeUGT41基因的表达量显著下降。(3)Xam侵染实验表明,干扰抑制MeUGT41基因表达可显著降低木薯植株叶片对Xam病菌侵染的抵抗能力。研究认为,木薯叶片中MeUGT41基因具有抵抗Xam病菌侵染的能力。     

Evolution of Tom, 297, 17.6 and rover retrotransposons in Drosophilidae species

LTR retrotransposons are the most abundant transposable elements in Drosophila and are believed to have contributed significantly to genome evolution. Different reports have shown that many LTR retrotransposon families in Drosophila melanogaster emerged from recent evolutionary episodes of transpositional activity. To contribute to the knowledge of the evolutionary history of Drosophila LTR retrotransposons and the mechanisms that control their abundance, distribution and diversity, we conducted analyses of four related families of LTR retrotransposons, 297, 17.6, rover and Tom. Our results show that these elements seem to be restricted to species from the D. melanogaster group, except for 17.6, which is also present in D. virilis and D. mojavensis. Genetic divergences and phylogenetic analyses of a 1-kb fragment region of the pol gene illustrate that the evolutionary dynamics of Tom, 297, 17.6 and rover retrotransposons are similar in several aspects, such as low codon bias, the action of purifying selection and phylogenies that are incongruent with those of the host species. We found an extremely complex association among the retrotransposon sequences, indicating that different processes shaped the evolutionary history of these elements, and we detected a very high number of possible horizontal transfer events, corroborating the importance of lateral transmission in the evolution and maintenance of LTR retrotransposons.     

The accumulation from sea water of 65Zn, 54Mn, 58Co and 59Fe by the thornback ray, Raja clavata L.

The accumulation of ⁶⁵Zn and ⁵⁴Mn from water by the thornback ray, Raja clavata L., has been studied at tissue level and their levels of accumulation have been related to stable element concentrations. The accumulation of ⁵⁸Co and ⁵⁹Fe has also been studied on a whole body basis and comparisons have been made of the ⁵⁹Fe levels in the tissues after 84 days with those of the stable element. It was found that lower values of accumulation of the radionuclides were obtained than in the case of the teleost Pleuronectes platessa L.. Such differences are discussed in relation to the relative permeabilities of the two species to sea water and the relative ratios of the radionuclides from sea water to blood plasma, and of blood plasma to organ. It is concluded that for both species direct input from water plays only a minor rôle in the accumulation of the four radionuclides studied.     

Complete cDNA Sequence, Genomic Structure, and Chromosomal Localization of the LPA Receptor Gene,lpA1/vzg-1/Gpcr26

Thelp_A1/Gpcr26locus encodes the first cloned and identified G-protein-coupled receptor that specifically interacts with lysophosphatidic acid. A murine full-length cDNA of size consistent with that seen on Northern blots (3.7 kb) was determined using 3′ rapid amplification of cDNA ends. Analysis of genomic clones revealed that the gene is divided into five exons, with one intron inserted in the coding region for transmembrane domain VI and one exon encoding the divergent 5′ sequence in another published cDNA clone variant (orphan receptor mrec1.3). This structure differs from the intronless coding region for a homologous receptor,Edg1,but is identical to another more similar orphan receptor (lp_A2) that has been deposited with GenBank. Using backcross analysis, both exons 1 and 4 mapped to a proximal region of murine Chromosome 4 indistinguishable from the vacillans gene. Exon 4 also mapped to a second locus on proximal Chromosome 6 inMus spretus,and this partial duplication was confirmed by Southern blot. The genomic structure indicates a distinct, divergent evolutionary lineage for thevzg-1/lp_A1subfamily of receptors compared to those of homologous orphan receptor genes.     

入侵种薇甘菊防治措施及策略评估

薇甘菊Mikania micrantha H.B.K.是入侵中国南部地区的一种危害极大的外来入侵种。防治薇甘菊的措施和策略,应根据薇甘菊的物种特性及所能支配的防除资源,综合考虑、统筹安排。薇甘菊能快速生长覆盖其他植物,其残株断枝易成为独立生长的新个体、种子量巨大且极易扩散,喜入侵次生植被。物理清除适用于小面积,对大面积出现的薇甘菊不应采用。化学防除主要用于应急,但未能改变适于薇甘菊生长的生境,薇甘菊仍可能在数年后再次为害。田野菟丝子Cuscuta campestris控制薇甘菊适用于大面积危害区域,当只以控制而不以根除自然群落的薇甘菊为目标时效果很好。群落改造能一劳永逸地解除薇甘菊的危害,但只适用于宜林地,且成本较高。天敌控制和植物化感防治都尚在探索阶段。未来还应发掘有效天敌,研发综合防治措施,揭示宏观分布规律。薇甘菊防治的正确策略是:对于已形成区域性危害的薇甘菊,根除已经不可能,应采取持久战而非速决战,防止薇甘菊入侵新区域是防治的重中之重,必须优先治理轻度入侵地和能向周边区域甚至是遥远区域扩散的传播源,建立防治示范区或样地。     

Preparation of an unusual fluoroalkyl phosphinoyl chelate complex, {k-P,C,P,k-O-(CF3)2PCH2C6H3CH2P(CF3)O}2Pt2

Electron poor cationic complexes [(^CF₃PCP)Pt(L)]⁺ (where L = CO, NC₅F₅, or acetone) react with H₂O in polar solvents via selective hydrolysis of a single P-CF₃ substituent to afford the spectroscopically-characterized phosphinoyl-bridged complex {k³-P,C,P,k¹-O-(CF₃)₂PCH₂C₆H₃CH₂P(CF₃)O}₂Pt₂ (1) in good yield. X-ray diffraction confirms the presence of a six-member Pt-P-O-Pt-P-O ring in a chair conformation. The presumed intermediate aqua complex, (^CF₃PCP)Pt(H₂O)⁺, is stable in dichloromethane, but when dissolved in more polar solvents readily converts to 1.     

Pyridine and phosphine reactions with [CPh3][B(C6F5)4]

Trityl borate salts [4-RPyCPh₃][B(C₆F₅)₄] (R = H 1, ^tBu 2, Et 3, NMe₂4) and [R₃PCPh₃][B(C₆F₅)₄] (R = Me 5, ⁿBu 6, Ph[1] 7, p-MeC₆H₄8) are readily prepared via equimolar reaction of the appropriate pyridine or phosphine and trityl borate [CPh₃][B(C₆F₅)₄]. The analogous reactions of PⁱPr₃ affords the product [(p-ⁱPr₃P-C₆H₄)Ph₂CH][B(C₆F₅)₄] (9) while the corresponding reactions of Cy₃P and ^tBu₃P gave the cyclohexadienyl derivatives [(p-R₃PC₆H₅)CPh₂][B(C₆F₅)₄] (R = Cy 10, ^tBu 11). X-ray structures of 5 and 9 are reported.