条件培养基对昆虫细胞BTI-Tn5B1-4及克隆株特性的影响

研究了条件培养基对细胞BTI-Tn5B1-4及其克隆株特性的影响。用含20%条件培养基以2×105cells/ml浓度测定细胞生长曲线,并与新鲜培养基作比较。结果显示,含条件培养基的细胞培养中的最大浓度比对照培养基的浓度高,同时细胞群体倍增时间比对照培养基中缩短3～5小时。当用野生型病毒AcMNPV感染时,两种培养基中细胞敏感性均在93%以上,OB产量差异不显著。重组蛋白半乳糖苷酶和碱性磷酸酶表达量测定比较,结果显示条件培养基中两种重组蛋白表达量均比对照培养基中高大约10%。     

Lability of host-cell DNA in growing cell cultures due to Mycoplasma

In HeLa-cell cultures chronically infected with Mycoplasma, (PPLO) host-cell DNA is unstable as detected by incorporation of H(3)-or C1 i-thymidine into DNA and subsequent release into the medium as acidsoluble radioactivity. This characteristic can be transmitted to PPLO-free cultures of strain L cells by inoculation with preparations of PPLO from the HeLa cells, although chronically infected cultures of L cells continue to multiply. In addition, virus preparations also may carry PPLO contamination through numerous passages.     

Endogenous regulation of macrophage proliferative expansion by colony-stimulating factor-induced interferon

Stimulation of cultures of murine bone-marrow cells with specific macrophage growth factor (colony-stimulating factor I) resulted in the production of type I interferon. Neutralization of this endogenous interferon by antiserum directed against interferons alpha and beta resulted in a significant enhancement of mononuclear phagocyte proliferation from committed marrow precursors. The effect of the antiserum was lost in cultures depleted of adherent cells, an indication that an adherent regulatory cell (or cells) in the marrow limits mononuclear phagocyte proliferation by producing antiproliferative interferon in response to high levels of specific growth factor.     

Phytochelatins: the principal heavy-metal complexing peptides of higher plants

A set of novel heavy-metal complexing peptides was isolated from plant cell suspension cultures; the structure of the peptides was established as (gamma-glutamic acid-cysteine)n-glycine (n = 3 to 7). These peptides appear upon induction of plant cells with heavy metals and represent the principal metal-binding activities in the cells. The name phytochelatin is proposed for this new class of natural products.     

白花曼陀罗细胞悬浮培养生物转化外源氢醌合成熊果苷的研究*

 研究了白花曼陀罗细胞悬浮培养对外源氢醌的糖基化。转化细胞来自白花曼陀罗嫩茎在LS固体培养基上诱导产生的愈伤组织。白花曼陀罗悬浮培养细胞不能分泌熊果苷,但能糖基化外源氢醌合成熊果苷。当氢醌添加量达240μmol/100mL培养物时,约有93.4%的氢醌转化形成了熊果苷,并应用多种色谱技术进行分离纯化,进行了HPLC分析和结构鉴定。     

渗透胁迫与植物细胞的氮代谢

比较了在渗透胁迫下苜蓿耐旱（ＭＥＳ—３）和非耐旱（ＭＥＳ—０）两个悬浮细胞系，它们的生长速率，细胞内ＮＨ３－ＮＨ４＋浓度的变化以及与精氨酸生物合成的关系。用１６％ＰＥＧ（聚乙二醇）处理作为渗透胁迫。在胁迫下培养１４天，ＭＥＳ—０的细胞生长速度明显下降，比对照降低８５．９７％；ＭＥＳ—３比对照下降３３．３６％；ＮＨ３—ＮＨ４＋含量ＭＥＳ—０高于对照１．９倍；ＭＥＳ—３则低于对照３４．８３％。精氨酸生物合成量ＭＥＳ—０低于对照５３．０１％，ＭＥＳ—３则相反，高于对照５４．２３％。     

Type C RNA tumor viruses as determinants of chemical carcinogenesis: effects of sequence of treatment

Fischer rat embryo cells were treated with 3-methylcholanthrene before or after inoculation with Rauscher murine leukemia virus. Transformation was not observed in untreated control cultures, cultures given virus or 3-methyl-cholanthrene alone, or cultures treated first with 3-methylcholanthrene followed by inoculation with the virus after removal of the chemical. Transformation was dependent upon the presence of Rauscher murine leukemia virus at the time of chemical treatment.     

Neurotoxicity of a fragment of the amyloid precursor associated with Alzheimer's disease

Amyloid deposition in senile plaques and the cerebral vasculature is a marker of Alzheimer's disease. Whether amyloid itself contributes to the neurodegenerative process or is simply a by-product of that process is unknown. Pheochromocytoma (PC12) and fibroblast (NIH 3T3) cell lines were transfected with portions of the gene for the human amyloid precursor protein. Stable PC12 cell transfectants expressing a specific amyloid-containing fragment of the precursor protein gradually degenerated when induced to differentiate into neuronal cells with nerve growth factor. Conditioned medium from these cells was toxic to neurons in primary hippocampal cultures, and the toxic agent could be removed by immunoabsorption with an antibody directed against the amyloid polypeptide. Thus, a peptide derived from the amyloid precursor may be neurotoxic.     

Nucleoside incorporation into strain L cells: inhibition by pleuropneumonia-like organisms

Contamination of Strain L cell cultures by pleuropneumonia-like organismtis (PPLO) resulted in a complete inhibition of the incorporation of tritiated thymnidine and uridine. Contanminated cultures were characterized by a concentration of PPLO along the margins of the cells and in the intercellular-spaces of the cultures. Autoracliograins of PPLO-contaminated cultures were characterized by exposed silver grains over the margins of the cells. Kanamnycin was efjective in the elimination of PPLO and the restoration of nucleoside incorporation.     

A cell-cycle constraint on the regulation of gene expression by platelet-derived growth factor

In density-arrested monolayer cultures of Balb/c 3T3 cells, platelet-derived growth factor (PDGF) stimulates expression of the c-myc and c-fos proto-oncogenes, as well as the functionally uncharacterized genes, JE, KC, and JB. These genes are not coordinately regulated. Under ordinary conditions, c-fos, JE, KC, and JB respond to PDGF only when the cells are in a state of G0 growth arrest at the time of PDGF addition. The c-myc gene is regulated in opposition to the other genes, responding best to PDGF in cycling cultures.     

Cellular Response to Ecdysterone in vitro

Organ cultures of hindgut from diapausing tobacco hornworm pupae, Manduca sexta (Johannson), produce an abundance of migrant cells around the original explant. With time-lapse cinematography, these cells were seen to move slowly and tended to aggregate. The addition of ecdysterone (beta-ecdysone) to these cultures stimulated a large increase in individual cell movements and the eventual disruption of cell sheets.     

Phenotypic expression of transformation: induction in cell culture by a phorbol ester

A biologically potent, tumor-promoting phorbol ester from Croton tiglium L. induces the appearance of transformed clones in a population of contact-inhibited fibroblasts of the mouse cell line 3T3. Mixed populations of cells with 10,000 3T3 cells and 100 virus-transformed cells were exposed to the phorbol ester and, in comparison with untreated cells, showed a marked increase in the numbers of transformed clones that grew. Exposure of 3T3 cultures to the carcinogen 7,12-dimethylbenz(a)anthracene alone or prior to exposure to the phorbol ester did not cause any increase in the number of transformed clones.     

Specific tropism of HIV-1 for microglial cells in primary human brain cultures

Human immunodeficiency virus (HIV) frequently causes neurological dysfunction and is abundantly expressed in the central nervous system (CNS) of acquired immunodeficiency syndrome (AIDS) patients with HIV encephalitis or myelopathy. The virus is found mostly in cells of the monocyte-macrophage lineage within the CNS, but the possibility of infection of other glial cells has been raised. Therefore, the effects of different HIV-1 and HIV-2 strains were studied in primary cultures of adult human brain containing microglial cells, the resident CNS macrophages, and astrocytes. These cultures could be productively infected with macrophage-adapted HIV-1 isolates but not with T lymphocyte-adapted HIV-1 isolates or two HIV-2 isolates. As determined with a triple-label procedure, primary astrocytes did not express HIV gag antigens and remained normal throughout the 3-week course of infection. In contrast, virus replicated in neighboring microglial cells, often leading to their cell fusion and death. The death of microglial cells, which normally serve immune functions in the CNS, may be a key factor in the pathogenesis of AIDS encephalitis or myelopathy.     

Neuronal properties of nymphal and adult insect neurosecretory cells in vitro

Neurosecretory brain cells from late nymphal and adult cockroaches were grown for 1 to 3 months in a chemically defined medium in combined cultures with embryonic organs or oocytes from nymphal and adult specimens. Under these conditions, neurosecretory cells show vigorous axonal growth. Electron dense granules in cell perikarya and axons of 3-month-old cultures are suggestive of neurosecretory activity in vitro.     

Subacute sclerosing panencephalitis: propagation of measles virus from brain biopsy in tissue culture

Measles virus was propagated in monolayer cultures established from brain tissue of a patient with subacute sclerosing panencephalitis. Syncytial cells were rendered fluorescent with measles specific antiserums only, by means of an indirect technique. The ultrastructural appearance of the microtubular aggregates was identical in brain tissue and in the cultured cells. Fusion experiments produced a cytopathic effect in humnan embryonic kidney and VERO cell cultures. The virus was identified by hemiagglutination-inhibition, but only in the supernatant of disrupted cultured cells.     

Homeostasis of the antibody response: immunoregulation by NK cells

When injected into mice, the synthetic double-stranded polynucleotide poly(inosinic) X poly(cytidylic) acid induces high natural killer (NK) cell activity within 4 to 12 hours. Induction of NK activity in mice immunized 2 or 3 days previously, or the addition of NK cells to cultures immunized in vitro 2 or 3 days previously, promotes early termination of the ongoing primary immunoglobulin M antibody response. A target for NK cells is a population of accessory cells that has interacted with antigen and is necessary for sustaining the antibody response. The inference is strong that NK cells induced normally by immunization also terminate the usual antibody response in vivo by elimination of antigen-exposed accessory cells.     

Cyclic changes in enzyme activity in synchronized mammalian cell cultures

Activity of the enzymes glucose-6-phosphate dehydrogenase and lactate dehydrogenase increases intermittently in synchronized cultures of Chinese hamster cells. During G(1) phase (3 hours after mitosis), midway through S phase (7 hours after mitosis) and again in late S phase (10 hours after mitosis), rapid increases in activity were observed and correlated with a net increase in cell size and total protein. The evidence suggests that this is a general phenomenon which affects a whole population of proteins and may be the expression of an endogenous cellular rhythm.     

Antigen solubilized from human leukemia: lymphocyte stimulation

Soluble antigen was extracted with hypertonic (3 molar) potassium chloride from the malignant cells of seven patients with acute leukemia. The antigen and leukemia cells were used to stimulate autologous patients' and allogeneic normal donors' lymphocytes in mixed lymphocyte cultures. The lymphocytes of six patients showed significant blastogenic responses to autologous antigen. In contrast, the lymphocytes of only one of seven normal donors responded to the soluble antigens. Both patients' and normal subjects' lymphocytes responded to the intact leukemia cells. The use of these antigens should facilitate the study of specific tumor immunity in human leukemia.