醇对SDS-CTAB-H2O体系双水相性质的影响

研究了短链一元醇(乙醇、正丁醇)和二元醇(乙二醇、1,4—丁二醇)对正负离子表面活性剂混合溶液(十二烷基硫酸钠—十六烷基三甲基溴化铵—水)双水相的影响。结果表明：一元醇的加入不但缩短了双水相的成相时间、使原水溶液双水相的区域得到扩展而且还会导致新双水相区域的出现,这种影响随着醇类链长的增长而增大。而二元醇的加入对双水相的相图影响不大,只是对形成双水相的表面活性剂最低总浓度稍有影响。实验结果也表明,出现双水相的表面活性剂最低总浓度与混合溶液的临界胶束浓度(CMC)有关,但CMC并不是决定出现双水相表面活性剂最低浓度的唯一因素。     

Aged murine killer T-cell clones acquire specific cytotoxicity for P815 mastocytoma cells

T-cell clones that grow continuously in tissue culture have become a major tool for studying the properties of T lymphocytes. It is therefore important to know to what extent such clones resemble their normal counterparts. Several reports have appeared recently which demonstrate that long-term T-cell lines may lose the specificity for which they were initially selected and acquire cytotoxic activity to a variety of targets, typical of the activity displayed by natural killer cells. We now report a number of instances in which murine cytotoxic T-cell clones have lost their original specific cytotoxic activity but have acquired strong specific cytotoxic activity for P815 mastocytoma target cells. Loss of the original specificity was usually observed after continuous in vitro cultivation for more than 6 months. We propose that this novel type of cytotoxicity should be called aged killer activity.     

Cloning and expression of murine interleukin-1 cDNA in Escherichia coli

Interleukin-1 (IL-1), a peptide hormone produced by activated macrophages, possesses the ability to modulate the proliferation, maturation and functional activation of a broad spectrum of cell types and may play a major role in the initiation and amplification of immune and inflammatory responses through its action on these diverse cell populations. IL-1 exhibits microheterogeneity in terms of its relative molecular mass (Mr, 13,000-19,000) and charge properties, and although murine IL-1 has been purified and some of its basic structure-function relationships have been elucidated, it has proved difficult to prepare sufficient amounts of IL-1 for direct and detailed sequence and structural studies. Here we report the cloning, sequence analysis and expression of murine IL-1 cDNA in Escherichia coli. The IL-1 cDNA codes for a polypeptide precursor of 270 amino acids. Biologically active IL-1 was produced in E. coli by expressing the carboxy-terminal 156 amino acids of the IL-1 precursor.     

Karyotype and chromosome banding in the reed frogHyperolius viridiflavus ommatostictus (Amphibia,Anura, Hyperoliidae)

Summary C-banding and mithramycin staining were used to characterize the karyotypes of 10 specimens of the African reed frogHyperolius viridiflavus ommatostictus from Tanzania. The diploid chromosome number is 2n=24. Although no heteromorphic sex chromosomes were present in the mitotic karyotypes, in many diakineses of male meiosis one or two bivalents exhibited an end-to-end arrangement. In the laboratory 7 out of 24 females changed sex spontaneously. This indicates that an XY/XX system of sex determination operates inH. viridiflavus ommatostictus.This study was supported by the Deutsche Forschungsgemeinschaft (Schm 484/2-4). We thank K. E. Linsenmair and C. M. Richards for helpful comments on an earlier draft.     

Detection of caprine arthritis-encephalitis- and maedi-visna viruses using the polymerase chain reaction

Summary The polymerase chain reaction (PCR) was used to demonstrate proviral DNA of lentiviruses of small ruminants in cultured cells. Primers for the Taq polymerase were selected in the GAG gene of Icelandic maedi-visna virus and POL gene of caprine arthritis-encephalitis (CAE) virus. Using PCR, proviral DNA of CAE virus was detected at 1 day post infection, 4 days beforeviral protein could be demonstrated using a sensitive immunoblotting protocol and 6 days before the appearance of syncytia. Primers derived from the published sequence of CAE virus successfully primed for the synthesis of homologous virus and Icelandic maedi-visna viruss but not for maedi-visna virus isolated in The Netherlands. In contrast, primers derived from the GAG region of Icelandic maedi-visna virus allowed the amplification of DNA of homologous virus, maedi-visna virus isolated in The Netherlands as well as CAE virus.