Structural and immunological similarities between simian sarcoma virus gene product(s) and human platelet-derived growth factor

The predicted amino acid sequence of the simian sarcoma virus (SSV) transforming gene product, p28sis, closely corresponds to that of human platelet-derived growth factor (PDGF). We demonstrate that p28sis rapidly undergoes a series of discrete processing steps including dimer formation and proteolytic digestion to yield molecules structurally and immunologically resembling biologically active PDGF.     

Antibodies against platelet-derived growth factor inhibit acute transformation by simian sarcoma virus

A clue to the molecular mechanism of neoplastic transformation was provided by the finding of a near identity in amino-acid sequence between the platelet-derived growth factor (PDGF) B-chain and a region in the transforming protein, p28sis, of simian sarcoma virus (SSV), an agent that causes sarcomas and gliomas in experimental animals. This finding infers a direct link between the molecular biology of normal mitogenesis and oncogenesis since it suggests that the transforming activity of SSV is caused by a growth factor. Although PDGF agonist activity has been isolated from conditioned medium of SSV-transformed cells, it is not clear whether infection of responsive cells by SSV leads solely to autocrine stimulation of growth by a secreted PDGF-like factor or whether other, possibly intracellular, activities of p28sis or its processed products contribute to the transformation. To distinguish between these possibilities, we have studied the effect of anti-PDGF antibodies on acute SSV-transformation, and report here that these antibodies inhibit both proliferation and SSV-induced morphological changes in human diploid fibroblasts.     

Antisera to a synthetic peptide of the sis viral oncogene product recognize human platelet-derived growth factor

It has recently been reported that the sequences of the sis oncogene of simian sarcoma virus (SSV) and of human platelet-derived growth factor (PDGF) are very similar, establishing the most solid link yet between the mitogenic actions of growth factors and the transforming proteins of retroviruses. To investigate molecular mechanisms of transformation I have produced antisera against synthetic peptides corresponding to segments of the protein sequences predicted by the nucleotide sequences of viral oncogenes. Applying this approach to the case of sis and PDGF, I report here the results of probing outdated human platelets with an antiserum directed against a synthetic peptide representing residues 139-155 of the predicted sequence of the SSV transforming protein, p28sis (ref. 3). I detected peptides of apparent molecular weights (MWs) 30,000 to 31,000 (30-31K) and 16-18K, which correspond to the apparent molecular weights of nonreduced and reduced PDGF. In addition, a peptide of MW 21,000 was detected in platelets and a protein of MW 56,000 was detected in SSV-infected marmoset cells.     

逐点比较法进给速度的稳恒研究

根据逐点比较法的控制原理，分析了在加工直线时，由于水平和垂直方向的进给只以串行方式工作，从而造成进给速度不稳恒．由此提出按照加工直线和水平方向的夹角大小，分别对进给速度采取不同程度的修正措施．从理论计算和实践上都证明了对进给速度不稳的分析是正确的，稳速的举措极其有效．速度的变化范围从原来的３０％缩小至１％．逐点比较法能适用于更大的加工范围．     

昆明小鼠未成熟卵母细胞OPS和SSV冷冻保存的比较

目的寻找昆明小鼠卵母细胞冷冻保存效率的新途径。方法选用5~6周龄雌性昆明小鼠的未成熟卵母细胞,在不同前处理液(10%EG或10%EG+10%DMSO)中平衡5 min,然后在冷冻液(EFS30、EFS40、EDFS30或EDFS40)中平衡30 s后进行OPS(Open pulled straw)法和SSV(Solid-surface vitrification)法玻璃化冷冻保存。结果小鼠未成熟卵母细胞的OPS法冷冻保存中,用EFS液冷冻的卵母细胞解冻后形态正常率最高为84.4%,成熟率低于16.7%;而在SSV法冷冻保存中,用EFS液冷冻的卵母细胞解冻后形态正常率最高为86.0%,成熟率为46.5%。OPS法和SSV法冷冻小鼠未成熟卵母细胞形态正常率为91.6%和91.4%,与对照组间差异较显著(P>0.01);成熟率为42.9%和59.1%,与对照组差异极显著(P<0.01)。结论多种抗冻保护剂组合使用效果好于单种抗冻保护剂;EDFS冷冻液冷冻保存效果好于EFS,尤其是EDFS30;OPS法可以有效地冷冻保存小鼠未成熟卵母细胞,且新型玻璃化冷冻法SSV法冷冻保存效果优于OPS法。     

Isolation of a novel antifungal peptide from the bark of Eucommia ulmoides Oliv

A novel Eucommia antifungal peptide, named EAFP3, was isolated from the bark of Eucommia ul- moides by NaC1 extract, gel filtration and reverse phase high performance liquid chromatography. The molecular mass of EAFP3 is 4157.3 Da, and its partial amino acid sequence is -. LYQQLIAGITLNK.-. EAFP3 exerts an inhibitory activity against Candida albicans in vitro and the drug concentration required for 50% growth inhibition （IC50） is 31.25μg/mL.     

Human epidermal growth factor receptor cDNA sequence and aberrant expression of the amplified gene in A431 epidermoid carcinoma cells

The complete 1,210-amino acid sequence of the human epidermal growth factor (EGF) receptor precursor, deduced from cDNA clones derived from placental and A431 carcinoma cells, reveals close similarity between the entire predicted v-erb-B mRNA oncogene product and the receptor transmembrane and cytoplasmic domains. A single transmembrane region of 23 amino acids separates the extracellular EGF binding and cytoplasmic domains. The receptor gene is amplified and apparently rearranged in A431 cells, generating a truncated 2.8-kilobase mRNA which encodes only the extracellular EGF binding domain.     

Complete nucleotide sequence of an influenza virus haemagglutinin gene from cloned DNA

A synthetic fowl plague virus (FPV) haemagglutinin gene has been cloned in bacteria and the complete sequence of the RNA gene deduced. It is 1,742 nucleotides long and the mRNA codes for 56.3 amino acids in an uninterrupted sequence. The nature of some of the important domains in the haemagglutinin has been established, and their structure is discussed in relation to their function. Extensive amino acid sequence homologies exist between FPV and human influenza haemagglutinins.     

Molecular cloning of a full-length cDNA for ECBP21 from Angelica dahurica

ECBP21 is an extracellular calmodulin-binding protein which was first detected and purified from extracellular extracts of suspension-cultured cells of Angelica dahurica. The purified protein was electroblotted onto PVDF membrane and the amino acid sequences from 1 to 20 were determined. Using degenerate oligonucleotides of the sequence, a full-length cDNA coding for ECBP21 was isolated by a combination of RT-PCR and 5′-RACE cloning. The cDNA contains 947 nucleotides and codes for a precursor protein of 216 amino acids. The N-terminal 1-25 amino acid sequence is a predicted signal peptide and the other 26-216 amino acid sequence is a mature peptide. The 26-45 amino acid sequence shows identity with the N-terminal amino acid sequence of purified ECBP21 from Angelica dahurica. The fragment of encoding the mature protein was cloned into pET-28b(+) and transformed into E. coli BL21(DE3). A protein with relative molecular mass 21 ku was expressed in E. coli. Using a biotinylated-CaM gel overlay technique, the expression protein was tested for its ability to bind CaM. The results indicated that the expression protein is a Ca2+- dependent CaM-binding protein. Thus, these results further defined the cDNA clone for ECBP21. This work laid a foundation for elucidating biological functions of ECBP21 by using molecular biological means.     

Structural comparison of glycophorins and immunochemical analysis of genetic variants

Differences in amino acid sequence of erythrocyte membrane glycophorin A are correlated with M or N blood group activity. A second sialoglycoprotein, glycophorin B, has an amino acid sequence identical to that of glycophorin AN in the first 23 positions and carries N activity only, suggesting that different structural genes code for the glycoproteins carrying these antigens. Certain genetically variant cells lack glycophorin A, as determined by immunochemical methods, and serological MN activity. Other variants lack MN activity, but contain normal amounts of glycophorin A in the membrane.     

Sequence of cDNA encoding human insulin-like growth factor I precursor

Somatomedins (SM) or insulin-like growth factors (IGF) constitute a heterogeneous group of peptides with important growth-promoting effects in vitro as well as in vivo. Amino acid sequences have been determined for only two of them, IGF-I and IGF-II, which are highly homologous. IGF-I, which is identical with SM-C, is composed of 70 amino acid residues and IGF-II contains 73 amino acids and may be identical with SM-A. Other peptides with different charge properties but with similar SM-like or insulin-like behaviour in biological and receptor assays, have been described but have not yet been fully characterized. The liver is known to be a major site of production of these peptides, but many other tissues--especially in the fetus--may synthesize them as well. We report here the nucleotide sequence of a human liver cDNA encoding the complete amino acid sequence of IGF-I. The IGF-I coding region is flanked by sequences encoding an amino-terminal peptide of at least 25 amino acid residues and a carboxyl-terminal peptide of 35 amino acids. This provides evidence that IGF-I is synthesized as a precursor protein and that formation of IGF-I from this precursor requires proteolytic processing at both ends.     

甘蔗UGPase cDNA的克隆及序列分析

以甘蔗(FN95-1702)为材料,通过RT-PCR,首次克隆得到了甘蔗UGPase cDNA片段.该片段长1 495 bp,其中包含完整的ORF为1 431 bp,共编码476个氨基酸,并含有5个重要的Lys残基位点,分别为Lys257、Lys321、 Lys367、 Lys408、 Lys409,它们对维持UGPase活性及与底物结合方面发挥着重要作用.     

内蒙古额吉淖尔盐碱湖一株产视紫红质的极端嗜盐古菌的分离及其bop基因核心序列及最适生长条件的分析

从内蒙古额吉淖尔湖分离得到一株产视紫红质的极端嗜盐古菌,初步鉴定为属于Natrinema属;并扩增出了其bop基因,该bop基因序列已在Genbank中注册,编号为KF863690,分析了其核心序列。结果表明bop基因开放阅读框为303 bp,编码101个氨基酸。blastp结果表明该蛋白属于Bac-rhodopsin蛋白家族,具有典型的细菌视紫红质蛋白结构域。利用BLAST进行相似性分析发现bop编码蛋白氨基酸序列与Genbank中编号AAS87571.1、WP-007110705和AFB77278.1的视紫红质蛋白相似性达到98%以上。此结果表明视紫红质蛋白在细菌及古菌中结构上具有很高的保守性,与其质子泵功能紧密相关。最后分析了该菌株的最适生长条件。该菌株在分离培养基中适宜生长的NaCl浓度范围为1.0~3.0 mol/L,适宜生长pH为6.5~8.5,适宜生长镁离子浓度为0.4~0.8 mol/L。通过分析比较得出该嗜盐古生菌株生长最适NaCl盐浓度为1.5 mol/L,最适pH值为7.5,最适镁离子浓度为0.4 mol/L。该实验结果为今后进一步研究产视紫红质的极端嗜盐古生菌株的生理生化特征及遗传学特征奠定了基础。     

Structure and expression of a cloned cDNA for human interleukin-2

A cDNA coding for human interleukin-2 (IL-2) has been cloned from a cDNA library prepared from partially purified IL-2 mRNA. The DNA sequence codes for a polypeptide which consists of 153 amino acids including a putative signal sequence. A biologically active polypeptide, characteristic of human IL-2, was produced when the cDNA was fused to a simian virus 40 promoter sequence and used to transfect cultured monkey COS cells.     

Isolation and structure of a human fibroblast interferon gene

Chimaeric plasmids containing double-stranded cDNA copies of mRNA induced in human fibroblasts by poly I . C were screened by an RNA selection method. A series of clones to which human fibroblast interferon mRNA selectively hybridized was identified. From the nucleotide sequence of the gene, the complete amino acid sequence of human fibroblast interferon was deduced. The protein is 166 amino acids long and is preceded by a 21-amino acid signal sequence.     

Molecular cloning of a fulllength cDNA for ECBP21 from Angelica dahurica

ECBP21 is an extracellular calmodulin-binding protein which was first detected and purified from extracellular extracts of suspension-cultured cells of Angelica dahurica. The purified protein was electroblotted onto PVDF membrane and the amino acid sequences from 1 to 20 were determined. Using degenerate oligonucleotides of the sequence, a full-length cDNA coding for ECBP21 was isolated by a combination of RT-PCR and 5′-RACE cloning. The cDNA contains 947 nucleotides and codes for a precursor protein of 216 amino acids. The N-terminal 1–25 amino acid sequence is a predicted signal peptide and the other 26–216 amino acid sequence is a mature peptide. The 26–45 amino acid sequence shows identity with the N-terminal amino acid sequence of purified ECBP21 from Angelica dahurica. The fragment of encoding the mature protein was cloned into pET-28b(+) and transformed into E. coli BL21(DE3). A protein with relative molecular mass 21 ku was expressed in E. coli. Using a biotinylated-CaM gel overlay technique, the expression protein was tested for its ability to bind CaM. The results indicated that the expression protein is a Ca²⁺-dependent CaM-binding protein. Thus, these results further defined the cDNA clone for ECBP21. This work laid a foundation for elucidating biological functions of ECBP21 by using molecular biological means.