氨基酸营养当量和整齐性指数

化学法以蛋白质的氨基酸组成评价蛋白质营养价值。在分析化学法的一般思想和方法的基础上,本文引进氨基酸营养当量和营养当量数的概念,并提出一个称为“整齐性指数”的新化学指数。使化学评价蛋白质营养价值的方法理论化,并使化学指数在反映蛋白质营养价值上更加精确可靠;本文同时还揭示了化学法中常用的化学分指标能较理想反映蛋白质营养价值的内在原因,通过实例分析,本文还证实了蛋白质的氨基酸组成对蛋白质的消化率存在影响的作用。     

Location of a Bombyx mori receptor binding region on a Bacillus thuringiensis delta-endotoxin.

Receptor binding studies were performed with 125I-labeled trypsin-activated insecticidal toxins, CryIA(a) and CryIA(c), from Bacillus thuringiensis on brush-border membrane vesicles (BBMV) prepared from Bombyx mori larval midgut. Bioassays were performed by gently force feeding B. mori with diluted toxins. CryIA(a) toxin (LD50; 0.002 micrograms) was 200 times more active against B. mori larvae than CryIA(c) toxin (LD50; 0.421 micrograms) and showed high-affinity saturable binding. The Kd and the binding site concentration for CryIA(a) toxin were 3.5 nM and 7.95 pmol/mg, respectively. CryIA(c) toxin (Kd, 50.35 nM; Bmax, 2.85 pmol/mg) did not demonstrate high-affinity binding to B. mori BBMV. Control experiments with CryIA(a) and CryIA(c) toxins revealed no binding to mouse small intestine BBMV and nonspecific binding to pig kidney BBMV. These data provide evidence that binding to a specific receptor on the membrane of midgut epithelial cells is an important determinant with respect to differences in insecticidal spectrum of insecticidal crystal proteins. To locate a B. mori receptor binding region on the CryIA(a) toxin, homologous and heterologous competition binding studies were performed with a set of mutant proteins which had previously been used to define the B. mori "specificity domain" on this toxin (Ge, A. Z., Shivarova, N. I., and Dean, D. H. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 4037-4041). These mutant proteins have had regions of their genes reciprocally exchanged with the cryIA(c) gene. A B. mori receptor binding region on CryIA(a) toxin includes the amino-terminal portion of the hypervariable region, amino acids 332-450, which is identical to the previously described B. mori specificity determining region. These data provide direct evidence that delta-endotoxins contain a tract of amino acids that comprise a binding region and as a results determines the specificity of a toxin.     

A hybrid cell mapping panel for regional localization of probes to human chromosome 8

We have characterized a panel of somatic cell hybrids that carry fragments of human chromosome 8 and used this panel for the regional localization of anonymous clones derived from a chromosome 8 library. The hybrid panel includes 11 cell lines, which were characterized by Southern blot hybridization with chromosome 8-specific probes of known map location and by fluorescent in situ hybridization with a probe derived from a chromosome 8 library. The chromosome fragments in the hybrid cell lines divide the chromosome into 10 intervals. Using this mapping panel, we have mapped 56 newly derived anonymous clones to regions of chromosome 8. We have also obtained physical map locations for 7 loci from the genetic map of chromosome 8, thus aligning the genetic and physical maps of the chromosome.     

~(125)Ⅰ标记单抗LC-I与肺腺癌细胞体内外结合特性的研究

本文用~(125)Ⅰ标记LC-1进行了一些体内外实验。实验结果表明:LC-1单抗的结合常数为4.8×10~8M~(-1),LC-1针对的SPC-A_1细胞表面抗原的位点数为7.2×10~4/细胞;LC-1与LAC-122两单抗针对的抗原决定簇没有交叉;用蛋白酶和过碘酸钠处理SPC-A_1细胞,前者对LC-1的结合抑制39%,后者抑制66%;LC- 1不但有较强的体外结合靶细胞的能力,从LC-1在荷瘤裸鼠中的组织器官分布来看,LC-1与肿瘤有较高的体内亲和性,并且是特异性的结合。     

Studies on antigens of human lung adenocarcinoma with McAb LC-1]

The soluble antigens extracted from both human lung adenocarcinoma cell line SPC-A-1, and normal adult lung tissue with non-idet P-40 were subjected to 10% SDS-PAGE. The number of bands distinguishable by naked eyes of lung adenocarcinoma are 57, in which 4 bands are more significant. The bands of normal human lung tissue are 52, in which 2 bands are more significant. The molecular weights of these bands mainly are within 30 to 94 KD The thin layer chromatographs of these two antigenic extracts have shown that there is difference in their sugar content, but both of them shown little sialic acid. The Immunoblot pattern of McAb LC-1 reacted with the extracts of SPC-A-1 cells shows that all of 3 bands detected can be stained by alcian blue, indicating that they are glycoproteins. However, of them two bands, M. W. of 70 KD and 51 KD can also be stained by Sudan Black B, indicating that these two bands are glycolipoproteins. The ganglioside and neutral glycolipid can inhibit the binding of LC-1 with the extract of SPC-A-1 cells. The results indicate that the epitopes of SPC-A-1 cell extract reacted with McAb LC-1 are probably located in the polysaccharide.     

Epidemic hemorrhagic fever in Hubei Province, The People's Republic of China: a clinical and serological study

Between July 1975 and April 1980, 71 patients were admitted to the Second Attached Hospital of Hubei Provincial Medical College in Wuchang with the diagnosis of epidemic hemorrhagic fever (EHF). The clinical course among these patients was similar to that described for patients with Korean hemorrhagic fever, and hemorrhagic fever with renal syndrome of the U.S.S.R. The overall mortality was 11.2 percent. Sera obtained from some of these patients as well as from patients admitted to the First Attached Hospital of Hubei Provincial Medical College were tested against an antigen associated with Korean hemorrhagic fever and showed exceedingly high antibody titers. We conclude that EHF in Central China represents the same or a closely related disease process as Korean hemorrhagic fever.     

Centrosome positioning and primary cilia assembly orchestrate neuronal development

Establishment of axon and dendrite polarity, migration to a desired location in the developing brain, and establishment of proper synaptic connections are essential processes during neuronal development. The cellular and molecular mechanisms that govern these processes are under intensive investigation. The function of the centrosome in neuronal development has been examined and discussed in few recent studies that underscore the fundamental role of the centrosome in brain development. Clusters of emerging studies have shown that centrosome positioning tightly regulates neuronal development, leading to the segregation of cell factors, directed neurite differentiation, neuronal migration, and synaptic integration. Furthermore, cilia, that arise from the axoneme, a modified centriole, are emerging as new regulatory modules in neuronal development in conjunction with the centrosome. In this review, we focus on summarizing and discussing recent studies on centrosome positioning during neuronal development and also highlight recent findings on the role of cilia in brain development. We further discuss shared molecular signaling pathways that might regulate both centrosome and cilia associated signaling in neuronal development. Furthermore, molecular determinants such as DISC1 and LKB1 have been recently demonstrated to be crucial regulators of various aspects of neuronal development. Strikingly, these determinants might exert their function, at least in part, via the regulation of centrosome and cilia associated signaling and serve as a link between these two signaling centers. We thus include an overview of these molecular determinants.     

Multiple species of wild tree peonies gave rise to the ‘king of flowers’, Paeonia suffruticosa Andrews

The origin of cultivated tree peonies, known as the ‘king of flowers'' in China for more than 1000 years, has attracted considerable interest, but remained unsolved. Here, we conducted phylogenetic analyses of explicitly sampled traditional cultivars of tree peonies and all wild species from the shrubby section Moutan of the genus Paeonia based on sequences of 14 fast-evolved chloroplast regions and 25 presumably single-copy nuclear markers identified from RNA-seq data. The phylogeny of the wild species inferred from the nuclear markers was fully resolved and largely congruent with morphology and classification. The incongruence between the nuclear and chloroplast trees suggested that there had been gene flow between the wild species. The comparison of nuclear and chloroplast phylogenies including cultivars showed that the cultivated tree peonies originated from homoploid hybridization among five wild species. Since the origin, thousands of cultivated varieties have spread worldwide, whereas four parental species are currently endangered or on the verge of extinction. The documentation of extensive homoploid hybridization involved in tree peony domestication provides new insights into the mechanisms underlying the origins of garden ornamentals and the way of preserving natural genetic resources through domestication.