Two novel classes of small ribonucleoproteins detected by antibodies associated with lupus erythematosus

The RNP and Sm antigens recognized by lupus erythematosus antibodies are located on discrete particles containing single small nuclear RNA's complexed with proteins. The antigens Ro and La are also on ribonucleoproteins. The small RNA's in ribonucleoproteins with Ro are discrete, like those associated with RNP and Sm; in contrast, ribonucleoproteins with La contain a striking highly banded spectrum of small RNA's from uninfected cells as well as virus-associated RNA from adenovirus-infected cells.     

小鼠胚胎嵌合的研究

选用昆白.CI_(57)及B/L_(615)三个品系小鼠,对其8细胞期(8C),桑椹期(M)和囊胚期(B)的全胚和半胚(半)进行聚合,培养和移植试验。8细胞期及桑椹期胚胎的聚合发育率显著高于囊胚期(P<0.05),全胚聚合的发育率显著高于半胚(P<0.05)。将同品系和不同品系的8细胞期,桑椹期和囊胚期胚胎嵌合移植给27只受体,9只妊娠,妊娠率分别为17％(1/6),40％(6/15)及33％(2/6),平均为33％(9/27),共产仔35只,其中不同品系胚胎的嵌合胚移植,产仔15只,4只为皮毛嵌合体。     

嵌合猪圆环病毒的构建

[目的]为了构建猪圆环病毒1型(PCV1)和猪圆环病毒2型(PCV2)的嵌合病毒,并为PCV2疫苗研究奠定基础.[方法]以PCV1基因组为骨架,将其衣壳基因替换为PCV2衣壳基因,来构建嵌合猪圆环病毒(PCV1-2)DNA克隆,将PCV1-2 DNA克隆转染PK-15细胞以获得拯救病毒PCV1-2,并测定PCV1-2在PK-15细胞中的增殖特性.[结果]酶切和序列测定显示成功构建出PCV1-2 DNA克隆;免疫荧光试验和PCR检测显示成功获得拯救病毒PCV1-2,其效价达到1060 TCIDs0/mL以上;一步生长曲线显示PCV1-2在PK-15细胞中的增殖特性与其亲本病毒近似.[结论]成功构建了1种具有较高体外增殖能力的嵌合猪圆环病毒.     

Somatic cell mating and segregation in chimeric frogs

Both pentaploid and haploid cells were observed in a short-term culture of bone marrow of a diploid-triploid frog chimera. Apparently, diploid and triploid marrow cells fused to form "hybrid" pentaploid cells, which subsequently gave rise by somatic reduction to haploid daughter cells. The hybrid marrow cells and their haploid segregants are presumably at a selective disadvantage, as neither type of cell has been detected in the circulating blood of chimeric frogs.     

Birth of two chimeric genes in the Hominidae lineage

How genes with newly characterized functions originate remains a fundamental question. PMCHL1 and PMCHL2, two chimeric genes derived from the melanin-concentrating hormone (MCH) gene, offer an opportunity to examine such an issue in the human lineage. Detailed structural, expression, and phylogenetic analysis showed that the PMCHL1 gene was created near 25 million years ago (Ma) by a complex mechanism of exon shuffling through retrotransposition of an antisense MCH messenger RNA coupled to de novo creation of splice sites. PMCHL2 arose 5 to 10 Ma by an event of duplication involving a large chromosomal region encompassing the PMCHL1 locus. The RNA expression patterns of those chimeric genes suggest that they have been submitted to strong regulatory constraints during primate evolution.     

Active human-yeast chimeric phosphoglycerate kinases engineered by domain interchange

Phosphoglycerate kinase (PGK) is a monomeric protein composed of two domains of approximately equal size, connected by a hinge. Substrate-induced conformational change results in the closure of the active site cleft, which is situated between these two domains. In a study of the relations between structure and function of this enzyme, two interspecies hybrids were constructed, each composed of one domain from the human enzyme and one domain from the yeast enzyme. Despite a 35% difference in the amino acid composition between human and yeast PGK, catalytic properties of the hybrid enzymes are very similar to those of the parental proteins. This result demonstrates that the evolutionary substitutions within these two distantly related molecules do not significantly affect formation of the active site cleft, mechanism of domain closure, or enzyme activity itself.     

医学图书馆应为循证医学服务

 

在简述循证医学和传统医学区别的基础上，论述了循证医学和临床医师与图书馆工作的关系及文献检索在循证医学实践中的重要作用；提出在新的临床医学模式下，医学图书馆应认识到自己所处位置，抓住机遇，拓宽服务，在宣传、推广循证医学模式方面发挥重要作用。

     

Escherichia coli secretion of an active chimeric antibody fragment

A chimeric mouse-human Fab protein that binds specifically to the human carcinoma cell line C3347 has been expressed and secreted from Escherichia coli. This molecule, which contains functionally assembled kappa and Fd proteins, binds as effectively to sites on the surface of C3347 cells as Fab fragments prepared proteolytically from whole chimeric or mouse antibody. The production in Escherichia coli of foreign heterodimeric protein reagents, such as Fab, should prove useful in the management of human disease.     

Ecology/paleontology. Colorado River clams provide benchmark

Conservationists have long contended, largely in impressionistic terms, that 70 years of American dam building and water diversion have destroyed the biological richness of the Colorado River delta, a key nursery of marine life at the end of the Southwest's great watercourse. Now researchers have confirmed those suspicions, using an important ecological player--clams--as a quantitative marker.     

梨黑星病发病特点和防治技术

阐述梨黑星病在江淮地区发病特点,总结防治经验和综合防治技术.     

油菜素内酯(BR)超敏感嵌合受体的构建和水稻转基因表达

将油菜素内酯(brassinosteroids,BR)超敏感受体激酶基因Sud1与水稻抗病受体激酶基因Xa21经体外点突变后构建了带SUD1 LRR-JM结构域与XA21激酶域 (kinase)的合成受体(chimera)基因SNRG1, 同时构建了SUD1 LRR突变体对照受体基因SNRGmL和XA21 kinase突变体对照受体基因SNRGmK.应用基因枪(particle bombardment)转化技术成功将SNRG1, SNRGmL和SNRGmK导入粳稻模式品种台北309的胚性愈伤组织中,并由此获得了再生植株和细胞株.经PCR、Northern blot 分子检测和表型观察证实外源基因已经转入并整合到水稻基因组.防卫基因表达的结果表明SNRG1可能已在体内微量的BR作用下,激发了水稻的防卫反应.该结果为进一步研究XA21激酶的抗性激发奠定了基础.     

影响水稻雄性不育嵌合基因PMN29遗传转化的因素

水稻是一种重要的农作物,采用的育种方法是杂交选育为主的常规育种.随着分子生物学的发展,细胞工程育种和基因工程育种日益显示出优越性.杂交育种、细胞工程育种及基因工程育种,已成为现代育种学的三个方面.加快基因工程育种的步伐,是我国育种工作者的当务之急.     

Blue-fluorescent antibodies

The forte of catalytic antibodies has resided in the control of the ground-state reaction coordinate. A principle and method are now described in which antibodies can direct the outcome of photophysical and photochemical events that take place on excited-state potential energy surfaces. The key component is a chemically reactive optical sensor that provides a direct report of the dynamic interplay between protein and ligand at the active site. To illustrate the concept, we used a trans-stilbene hapten to elicit a panel of monoclonal antibodies that displayed a range of fluorescent spectral behavior when bound to a trans-stilbene substrate. Several antibodies yielded a blue fluorescence indicative of an excited-state complex or "exciplex" between trans-stilbene and the antibody. The antibodies controlled the isomerization coordinate of trans-stilbene and dynamically coupled this manifold with an active-site residue. A step was taken toward the use of antibody-based photochemical sensors for diagnostic and clinical applications.