在琼脂双向扩散中植物病毒非特异带的产生和消除

检测植物病毒,通常采用琼脂双向扩散、对流免疫电泳和酶联免疫吸附测定(ELIsA)等三种方法,而在研究一些植物病毒之间的亲缘关系方面,琼脂双向扩散则能提供其他方法所不能提供的免疫学图谱。我们在做琼脂双向扩散时发现,植物病毒的某些寄主与提纯病毒时所用磷酸盐缓冲液之间常能形成非特异带。本文报道非特异带的干扰现象及其消除方法。     

A covalently constrained congener of the Saccharomyces cerevisiae tridecapeptide mating pheromone is an agonist

An analog of alpha-factor, the Saccharomyces cerevisiae tridecapeptide mating pheromone (Trp-His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln-Pro-Met-Tyr), in which the side chains of Lys7 and Gln10 were covalently linked, was synthesized using solid phase methodologies. The yield of the purified cyclic analog cyclo7,10[Nle12]alpha-factor was 30%, and its structure was verified by amino acid analysis, peptide sequencing, fast atom bombardment-mass spectrometry, and proton nuclear magnetic resonance spectroscopy. Cyclo7,10[Nle12]alpha-factor caused growth arrest and morphological alterations in S. cerevisiae MATa cells qualitatively identical to those induced by linear pheromone and was one-fourth to one-twentieth as active as the linear alpha-factor depending upon the S. cerevisiae strain tested. Consistent with the relative activities of the linear and cyclic peptides, binding competition studies indicated that cyclo7,10[Nle12]alpha-factor had approximately 20-40-fold less affinity for the alpha-factor receptor. Hydrolysis of the cyclic peptide by the target cells did not lead to opening of the ring and was less rapid than that of linear alpha-factor. The alpha-factor antagonist des-Trp1-[Ala3,Nle12]alpha-factor reversed the activity of the cyclic analog, and cyclo7,10[Nle12]alpha-factor was not active at the restrictive temperature in a temperature-sensitive receptor mutant. These results support the conclusion that the cyclic alpha-factor occupies the same binding site within the receptor as is occupied by the natural pheromone. The cyclic alpha-factor represents a rare example of an agonist among covalently constrained congeners of small linear peptide messengers.     

Comparative properties of hydroquinone and hydroxylamine reduction of the Ca(2+)-stabilized O2-evolving complex of photosystem II: reductant-dependent Mn2+ formation and activity inhibition.

Calcium binding to photosystem II slows NH2OH inhibition of O2 evolution; Mn2+ is retained by the O2-evolving complex [Mei, R., & Yocum, C. F. (1991) Biochemistry 30, 7836-7842]. This Ca(2+)-induced stability has been further characterized using the large reductant hydroquinone. Salt-washed photosystem II membranes reduced by hydroquinone in the presence of Ca2+ retain 80% of steady-state O2 evolution activity and contain about 2 Mn2+/reaction center that can be detected at room temperature by electron paramagnetic resonance. This Mn2+ produces a weak enhancement of H2O proton spin-lattice relaxation rates, cannot be easily extracted by a chelator, and is reincorporated into the O2-evolving complex upon illumination. A comparison of the properties of Ca(2+)-supplemented photosystem II samples reduced by hydroquinone or NH2OH alone or in sequence reveals the presence of a subpopulation of manganese atoms at the active site of H2O oxidation that is not accessible to facile hydroquinone reduction. At least one of these manganese atoms can be readily reduced by NH2OH following a noninhibitory hydroquinone reduction step. Under these conditions, about 3 Mn2+/reaction center are lost and O2 evolution activity is irreversibly inhibited. We interpret the existence of distinct sites of reductant action on manganese as further evidence that the Ca(2+)-binding site in photosystem II participates in regulation of the organization of manganese-binding ligands and the overall structure of the O2-evolving complex.     

草莓花药培养获得无病毒植株的技术研究

以花粉发育为单核期的花药接种,在MS附加IAA 4ppm、K 2ppm、BA 2ppm的培养基上诱导愈伤组织,并可直接分化出“沙尔普斯”、“红岗利德”、“春香”3个品种的花药植株。稍加调整附加激素成分和浓度,可在“索非亚”、“宝交早生”、“戈雷拉”、“红衣”、“丽红”等品种的花药上直接经愈伤组织分化出植株。其中有“沙尔普斯”、“红岗利德”、“春香”、“宝交早生”、“索非亚”等5个品种的花药植株经过病毒检测确认不带SMoV、SCrV、SMYEV和SVBV4种病毒。对无病毒植株进行了田间对比试验,植株生长势和果实产量都明显超过对照品种。     

人体基因组随机单拷贝顺序的分离及其在染色体上的定位

本文从构建杂种细胞14-7-1的基因组文库出发,用种特异的探针分离出含有人体基因组顺序的重组子,并进一步分析了其中13个克隆,得到8个单拷贝顺序。通过与已建立的杂种细胞克隆分布板杂交以及染色体的原位杂交方法,将1个单拷贝顺序FD11-1定位在11p11-q11上。由于已经报道在11号染色体上具有3个连锁群,它们分别位于11p15、11p13和11q13上,因此,FD11-1有可能为11号染色体连锁基因图的建立提供1个有意义的座位。     

Phosphorylation and nuclear localization of the varicella-zoster virus gene 63 protein.

The protein encoded by varicella-zoster virus open reading frame 63 and carboxy-terminal deletions of the same were expressed either as fusion proteins at the carboxy terminus of the maltose-binding protein in Escherichia coli or independently in transfected mammalian cells. The truncations contained amino acids 1 to 142 (63 delta N) or 1 to 210 (63 delta K) of the complete 278-amino-acid primary sequence. Recombinant casein kinase II phosphorylated the 63F and 63 delta KF fusion proteins in vitro but did not phosphorylate the 63 delta NF fusion protein, implying that phosphorylation occurred between amino acids 142 and 210. Immunoprecipitation of 35S- or 32P-labelled extracts of cells transfected with plasmids expressing 63, 63 delta N, or 63 delta K also indicated that in situ phosphorylation most likely occurred between amino acids 142 and 210. These combined results suggest that casein kinase II plays a significant role in the phosphorylation of the varicella-zoster virus 63 protein. Indirect immunofluorescence of transfected cells indicated nuclear localization of the 63 protein and cytoplasmic localization of 63 delta K and 63 delta N, implying a requirement for sequences between amino acids 210 and 278 for efficient nuclear localization.     

Epitopes and hemagglutination binding domain on subgenus B:2 adenovirus fibers.

The adenovirus fiber serves as a ligand between the virus and the host cell receptor and manifests hemagglutination (HA) activity and antigenic domains. We have screened both the antigenic and immunogenic epitopes on the adenovirus fibers of subgenus B:2 by using recombinant fiber proteins (rfibers) expressed in Escherichia coli, synthesized peptides (P1 to P8), and the corresponding antisera. The results indicated that P4 (amino acids [aa] 201 to 220), P5 (aa 231 to 250), and P7 (aa 275 to 295) presented both antigenic and immunogenic epitopes in adenovirus type 11 prototype (Ad11p), Ad34a, and Ad11a fibers. P6 (aa 251 to 270) presented both epitopes in Ad11a fiber but only an antigenic epitope in other fibers. The C-terminal 20 amino acids of the fiber, corresponding to P8, manifested an epitope of low-level immunogenicity. P5, localized at the N-terminal aa 231 to 250, displayed an epitope that reacted with fibers of all the members of subgenus B analyzed. The rfibers of Ad11p and Ad34a displayed HA activity with monkey erythrocytes, though those of Ad11a did not. Mutagenesis of the rfibers revealed that neither the fragment replacements, 11p20211a, llp26011a,and 11a28011p, nor the Ad11p rfiber with the substitutions of Tyr-260-->H (Tyr260H)and Arg279Q displayed HA activity. The Ad11a fiber knob was sensitive to proteolytic digestion, whereas that of Ad11p was resistant. The results demonstrated that the decisive HA binding domain was presented at aa 260 to 280 and was conformation dependent. Nearby amino acids, aa 283 and 284, may also affect the HA function.     

几种昆虫生长调节剂对家白蚁的毒效试验

在室内条件下测定了卡死克、抑太保、灭幼豚3号、爱力螨克和扑虱灵五种昆虫生长调节剂对家白蚁的毒杀效果。初步筛选结果表明：卡死克、抑太保和爱力螨克对家白蚁的毒杀效果均较好,家白蚁对爱力螨克尤其敏感。2．30pm。yL爱力螨克、327．36pm0VL、卡死克和369．80V＊wL抑太保处理白蚁5～6天后,其死亡率可达100％。忌避性试验表明：卡死克、抑太保和爱力螨克对家白蚁均无明显的驱避作用。     

川百合花粉管的生殖细胞分裂过程中微管骨架的分布变化

应用透射电镜辅以免疫荧光定位技术研究了川百合 (Lilium davidii Duch.)花粉管中生殖细胞分裂过程中染色体动态和微管分布的关系。在生殖细胞分裂前和有丝分裂前期 ,电镜观察一直未见微管结构 ,但免疫荧光图象显示生殖细胞中有微管蛋白存在。直到分裂的前中期—中期 ,染色体出现 ,它们沿花粉管的长轴前后排列 ,横向的着丝点对相应地一对对地纵向排列。这时 ,生殖细胞中才出现大量微管 ,它们分布于细胞周质区和染色体之间 ,并跨越染色体的整个长度。前中期—中期开始时 ,只有 1～ 2对着丝点从横向转为纵向 ,微管垂直插入着丝点形成着丝点微管 ,而非前人用免疫荧光方法观察到的微管与着丝点侧向联接的图象。随着横向的着丝点对逐渐转变成纵向的过程 ,着丝点微管数量逐渐增多 ,但不形成典型的纺锤体。分裂后期 ,染色体交错分离 ,微管的分布与前中期—中期的基本相同。晚后期 ,染色体呈明显的两群 ,除极区和细胞中央区有微管残余外 ,大部分微管消失。通过染色体长度的测量 ,间接证明了分裂后期 B的存在。分裂末期的晚期 ,核膜形成后 ,在两精核之间的区域 ,微管数量开始增多。此区可能代表用免疫荧光所观察到的微管重叠区。细胞板出现后 ,微管消失     

多胚水稻ApⅢ（双13）的胚胎学观察

对多胚水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）ＡｐⅢ的大量成熟颖果、人工萌发的幼苗和开花后３～５ ｄ 的幼嫩颖果进行的整体解剖和显微制片观察表明：ＡｐⅢ的５０００粒成熟颖果中,８９．０％ 含单胚单苗,８．９％ 和１．２％分别含双胚双苗和三胚三苗;７００多粒幼嫩颖果中,９０．０％ ～９５．０％ 含单胚,５．０％ ～７．０％ 含双胚。因制片的数目有限,未见到含三胚的;在含单胚和多胚颖果中,胚均位于同一胚囊的珠孔端,未见到胚囊以外存在不定胚。根据上述结果,似可以认为ＡｐⅢ单粒颖果的双胚和三胚是由同一胚囊内的卵细胞和１或２个助细胞受精或不受精发育而来的