牛泌乳素mRNA的分离及鉴定

本文报道了从牛脑垂体提取总RNA,经寡聚脱氧胸苷纤维素亲合层析分离获得牛脑垂体Poly(A)~+RNA。牛泌乳素mRNA经含羟甲基汞琼脂糖凝胶电泳分析,估计其长度约为1200个核苷酸。根据牛泌乳素的部分氨基酸序列推断并合成寡聚核苷酸探针,经Northern印迹杂交及放射自显影分析,证实了该mRNA中含有牛泌乳素mRNA的序列。在兔网织红细胞体外翻译体系中,牛泌乳素mRNA促进了~35S-甲硫氨酸参入,翻译合成的初级翻译产物能与兔抗羊PRL抗血清发生特异性免疫沉淀反应,SDS聚丙烯酰胺凝胶电泳及放射自显影分析结果表明,牛泌乳素前体的分子量约25000。     

香菇和侧耳属间原生质体的电融合研究

从培养在液体培养基中的香菇、美味侧耳和平菇的单核菌丝用酶法分离了原生质体。施加0.5MHz、500PV/cm的正弦波和μs、6000PV/cm方形脉冲的电场诱导下使其电融合。电融合后的融合子和原生质体在固体培养基上植板培养成菌落。在显微镜下检查融合子菌株菌丝的锁状联合选出从融合子长成的菌株。香菇和美味侧耳的融合菌株产生频率为61.53%,香菇和平菇的融合菌株产生频率为32.58%。根据融合菌株与亲本的拮抗作用和他们的过氧化物同工酶和酯酶同工酶的电泳酶谱与其亲本酶谱的不同,证实这些融合菌株是从融合的异核体生长成的。同时讨论了电融合方法和结果。     

Effects of dideoxyforskolin on proteoglycan synthesis and structure in embryonic chick chondrocyte cultures

1,9-Dideoxyforskolin inhibits proteoglycan synthesis and xyloside-initiated glycosaminoglycan (GAG) synthesis in chick embryo chondrocytes. Dideoxyforskolin does not affect the length of xyloside-initiated GAG chains secreted into the medium but chains from the dense proteoglycan secreted into the medium appear slightly longer. Incorporation of labeled serine into the dense proteoglycan and subsequent digestion with Pronase revealed a dramatic decrease in percent of total radioactivity associated with GAG chains in the proteoglyean from cultures treated with forskolin or dideoxyforskolin. These observations suggest that these diterpenes have a specific inhibitory effect on chain initiation reactions and thus may be useful tools in the study of proteoglycan synthesis and processing.     

Isolation and characterization of two novel rat ovarian lactogen receptor cDNA species

Two novel lactogen receptor cDNA clones (2.1 and 1.2 kb) were isolated from a rat ovarian cDNA library. Nucleotide sequence of the 2.1 kb clone codes for a 610 aa receptor (nonglycosylated mol. wgt. 66,000 D) with an extracellular domain, a transmembrane region and an intracellular domain, and exhibited significant overall similarity with the rat liver receptor (310 aa) and both rabbit mammary and human hepatoma receptors (616 and 622 aa). However, the ovarian lactogen receptor sequence contains a unique cytoplasmic domain of 110 aa and consensus sequences for both a tyrosine phosphorylation site and an ATP/GTP type A binding site, and thus has potential for signal transduction and mitogenic activity. The 1.2 kb clone codes for a truncated binding form of 150 aa that is identical with the ovarian long form over only the first 130 residues, and lacks the transmembrane region. Differences between long and short forms of the ovarian lactogen receptors and the truncated liver species may result from alternative splicing. The prolactin holoreceptor gene(s) has the potential for producing several receptor subtypes that differ in tissue-specific expression, size, compartmentalization and mode of signal transduction, and may subserve the divergent functions of prolactin in its several target cells.     

Isolation and partial characterization of a lactotransferrin receptor from mouse intestinal brush border

Several lines of evidence have recently suggested the occurrence of a specific lactotransferrin receptor in the small intestinal brush-border membrane in several animal species, which is thought to be involved in lactotransferrin-mediated intestinal iron absorption. We report here for the first time the isolation and partial characterization of this receptor from mouse intestinal brush border. The receptor has been purified to homogeneity by affinity chromatography on an immobilized human lactotransferrin column. The purified receptor was found to be active in that it binds iron-free and iron-saturated lactotransferrin with a Kd of 0.1 microM. Anti-receptor antibodies were prepared, and the receptor was further isolated by immunoaffinity chromatography in higher yield but in a denatured form. The purified receptor was revealed by sodium dodecyl sulfate-polyacrylamide electrophoresis to be a protein of about Mr = 130,000, consisting of a single polypeptide chain. The isoelectric point was determined to be 5.8. The receptor was further shown to bear concanavalin A and phytohemagglutinin L binding glycans. Digestion by N-glycanase and endo-N-acetyl-beta-D-glucosaminidase B led to a decrease of Mr = 25,000, while the endo-N-acetyl-beta-D-glucosaminidase H was uneffective, suggesting that the lactotransferrin receptor is mainly glycosylated by bi- and triantennary glycans. To gain further insight into the interaction of the receptor with lactotransferrin, namely, the number of ligand molecules bound per molecule of receptor, mouse lactotransferrin was cross-linked to its membrane-bound enterocyte receptor by use of radiolabeled sulfosuccinimidyl 3-[[2-(p-azidosalicylamido)ethyl]dithio]propionate (SASD).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cell volume measurement as an estimation of mammalian cell biomass

Measurements of volume distributions and dry weight are made on hybridoma cells in culture. The volume of viable hybridoma cells is significantly larger than that of nonviable cells. During exponential growth, the volume of the viable hybridoma cells is found to be significantly larger than that during other stages of batch culture. Proportionality is found between the volume of the cells and their dry weight, indicating that the volume data can be used in conjunction with cell concentration data as a practical technique for indirect measurement of the biomass concentration present in a culture. Comparison of dry weight concentrations in continuous culture to predictions from the volume data shows very good agreement.     

Cytostatic and growth-stimulating effects of alveolar macrophages of rats on tumor cells

Cytostatic and growth-stimulating effects of alveolar macrophages (AM) of rats on tumor cells were studied. The experimental results are summarized as follows. 1. The cytotoxicity of AM activated with BCG to tumor cells was increasing with the increase of effector cells/target cells (E/T) ratio. AM without the treatment with BCG expressed slight cytotoxicity to tumor cells at a high E/T, and growth-stimulating effect on tumor cells, at a low E/T. 2. AM after 24-hour culture had a lower manifestation of cytotoxicity to human lung adenocarcinoma cell line than that of AM without 24-hour culture, and had a growth-stimulating effect on B-16 cell line. 3. Cytostatic and growth-stimulating effects of AM without or with 24-hour culture were decreasing with the increase of irradiation doses.     

鲍氏志架氏菌的一个新血清型

Two strains which belong to the same serotype of Shigella were isolated from the bloody-pus stool of two patients (in 1986) and is reported in this paper. The results were identical both showing agglutination in low titer with serotype 8 of S. dysenteriae and serotype 4 of S. boydii when the two strains were checked well with all kinds of diagnostic antisera and vice versa, ie the antisera produced by the two strains were also checked well with sera prepared with the representative strains of all Shigella spp. No cross agglutination with O6, O7, and O150 of E. coli were found. Consequently, It appears to be a new serotype of Shigella. These two strains possess the ability of causing keratitis in guinea-pigs as well as invading epithelial cells, the DNA of both strains in agarose-electrophoresis showed a large plasmid, indicating that they are virulent strains possessing invasive ability. It was concluded that these two strains belonged to Shigella boydii as they fermented mannitol and non-related antigenically with Shigella flexneri. Since serotype 1-18 of S. boydii have been reported recently, we propose that this new serotype should be serotype 19 of Shigella boydii.     

竹飞虱属一新种记述(同翅目:飞虱科)

黄氏竹飞虱 Bambusiphaga huangi新种(图1—5) 头顶近方形,基部宽为中央长度的1.2倍,大于同一线一个复眼的宽度,略宽于端部,端部多少向二侧扩张,端缘呈弧形突出,脊明显,中侧脊起自侧缘离端部约1/3处,彼此呈角状延伸相遇于端缘;侧面观,头顶与额呈钝角但圆曲相接;额长方形,二侧脊几乎平行,中脊单一,中长为其宽度的2倍,于近基端具一微弱的横脊;唇基发达,为额长的0.85     

Studies on the lysine-binding sites of human plasminogen. The effect of ligand structure on the binding of lysine analogs to plasminogen

A method is described for measuring relative binding constants of lysine and analogs of lysine to plasminogen and plasminogen 'kringle' fragments. Plasminogen or kringle fragments adsorbed to lysine-Sepharose are eluted with increasing concentrations of lysine or other ligands, the concentration of ligand required to elute 50% of the protein being taken as a measure of the binding constant. The method is simple and is not dependent on monitoring conformational changes. We confirm earlier reports that the best ligands for the lysine binding sites of plasminogen are omega-amino acids containing five or six carbons. We show further that both Glu-plasminogen (the native form with N-terminal glutamic acid) and Lys-plasminogen (a degraded form with N-terminal lysine), as well as the heavy chain fragments, kringle 4 and kringle 1+2+3, have very similar properties with regard to binding specificity for omega-amino acids. For all species optimal binding is observed when the distance between the amino and carboxyl carbon is about 0.68 nm. The finding of ligands is decreased by the presence of polar atoms on the alpha and beta positions of the carbon chain of amino acids. Arginine binds relatively weakly at the lysine site and there does not appear to be a separate arginine binding site in plasminogen.