RH 5849, a Nonsteroidal Ecdysone Agonist: Effects on Larval Lepidoptera

The ecdysone agonist RH 5849 (1,2-dibenzoyl-1-tert-butylhydrazine) causes the premature initiation of molting at all stages of larval development of the tobacco hornworm, Manduca sexta. This phenomenon occurs without an increase in the endogenous ecdysone (20-hydroxyecdysone) titers. RH 5849 likewise provokes the initiation of molting in larval abdomens in the absence of a source of endogenous hormone. Although substantially less active than 20-hydroxyecdysone in vitro, RH 5849 was 30 to >670 times as active as the authentic molting hormone in bioassays with isolated larval abdomens or intact hornworms. This reversal in potency can be attributed to the superior transport properties and metabolic stability of RH 5849 relative to 20-hydroxyecdysone. Thus RH 5849 and its analogs are relatively persistent ecdysone agonists that halt feeding in larval lepidoptera by forcing an ultimately lethal, developmentally premature molt.     

Lysergic acid diethylamine: mutagenic effects in Drosophila

d-Lysergic acid diethylamide causes a significant increase in recessive lethal mutations in the X chromosome of Drosophila males after intraperitoneal injection of massive doses.     

Phenotypic effects of heterozygous,x-rayinduced mutations in Drosophila

Heterozygous mutations produced by 3000 r delay pupation in about 9 percent of larvae of Drosophila melanogaster under nutritional stress and kill approximately 6 percent. The effects are less, though appreciable, when there is excess nutrient; no effects are detectable after o?gonia are irradiated. Irradiated sperm and o?cytes cause detriment, partly via different types of mutations, in approximately equal amounts.     

Spermatogenesis in cultured testes of the cynthia silkworm: effects of ecdysone and of prothoracic glands

In vitro spermatogenesis takes place when intact testes are cultured in blood plasma containing ecdysone or certain other steroids possessing ecdysone activity. The ecdysone requirement can be satisfied by culturing the testes in the presence of living, active prothoracic glands. The most likely explanation of these results is that the prothoracic glands constitute the principal source of ecdysone.     

Insulin as a potent, specific growth factor in a rat hepatoma cell line

A line or rat hepatoma cells in culture which, in response to serum starvation, become arrested in the early G1 phase of growth, can be stimulated by insulin alone to enter the cell cycle and traverse S phase. A half-maximum response is observed at 30 to 70 picomolar concentrations and the maximum response is essentially identical to that found with optimum serum concentrations.     

Identification of nuclear receptors for VIP on a human colonic adenocarcinoma cell line

Vasoactive intestinal peptide (VIP) is a neuropeptide with broad tissue distribution. Although its precise function is unknown, it is thought to exert its effect, at least in part, by interacting with cell surface receptors. Nuclear receptors for VIP have now been identified by specific binding of 125I-labeled VIP to nuclei of a human colonic adenocarcinoma cell line (HT29) and by cross-linking of 125I-labeled VIP to its receptor on intact nuclei. In contrast, 125I-labeled transferrin shows only background binding to nuclei but significant binding to intact cells. Purity of the isolated nuclei was further substantiated by electron microscopy. The apparent molecular sizes of the VIP--cross-linked nuclear and cell surface receptors are similar but not identical.     

Generation and in vitro differentiation of a spermatogonial cell line

Spermatogenesis is the process by which spermatogonial stem cells divide and differentiate to produce sperm. In vitro sperm production has been difficult to achieve because of the lack of a culture system to maintain viable spermatogonia for long periods of time. Here we report the in vitro generation of spermatocytes and spermatids from telomerase-immortalized mouse type A spermatogonial cells in the presence of stem cell factor. This differentiation can occur in the absence of supportive cells. The immortalized spermatogonial cell line may serve as a powerful tool in elucidating the molecular mechanisms of spermatogenesis. Furthermore, through genomic modification and transplantation techniques, this male germ cell line may be used to generate transgenic mice and to develop germ cell gene therapy.     

HEL cells: a new human erythroleukemia cell line with spontaneous and induced globin expression

A new human erythroleukemia cell line has been established. This line, designated HEL, is capable of spontaneous and induced globin synthesis, producing mainly G gamma and A gamma chains. Embryonic chains (epsilon, zeta) and alpha chains are detectable in very small amounts; beta chains are undetectable. This line provides a new model system for studying aspects of erythroid cell differentiation and differential globin gene expression.     

L-肉碱对胖头鱥肌肉细胞和草鱼性腺细胞抗氧化功能的调节作用

为研究L-肉碱对胖头鱥Pimephales promelas肌肉细胞(FHM)和草鱼Ctenopharyngodon idellus性腺细胞(GCO)抗氧化酶功能的调节作用,以两种鲤科鱼细胞FHM和GCO为研究对象,在培养基中添加不同浓度的L-肉碱(0、0. 001、0. 01、0. 1、0. 5、1、5 mmol/L)分别孵育FHM细胞6 h、GCO细胞12 h,采用生物化学法和荧光定量PCR法检测L-肉碱对细胞抗氧化酶活性和基因相对表达量的影响。结果表明:0. 01～5 mmol/L L-肉碱组FHM细胞SOD、CAT活性显著高于对照组(P<0. 05),仅5 mmol/L L-肉碱组GCO细胞SOD、CAT、GPX、γ-GCS活性显著高于对照组(P<0. 05);与对照组相比,L-肉碱组FHM细胞Cu Zn-SOD mRNA相对表达水平无显著变化(P>0. 05),0. 5、1、5 mmol/L L-肉碱组GCO细胞Cu ZnSOD mRNA相对表达水平显著上调(P<0. 05); 0. 01～5 mmol/L L-肉碱组FHM细胞CAT mRNA相对表达水平显著上调(P<0. 05),所有L-肉碱组GCO细胞CAT mRNA的相对表达水平显著上调(P<0. 05); 0. 5mmol/L L-肉碱组GCO细胞GPX mRNA相对表达水平显著上调(P <0. 05);仅0. 1 mmol/L L-肉碱处理FHM细胞GCLC mRNA相对表达量水平显著上调(P<0. 05),L-肉碱添加范围为0. 5～5 mmol/L时,GCO细胞GCLC mRNA的相对表达水平均显著上调(P<0. 05)。研究表明,在培养基中添加L-肉碱能明显上调FHM和GCO细胞的抗氧化酶活性及其相关基因的相对表达水平,在本试验条件下,细胞培养基中推荐L-肉碱的适宜添加浓度为0. 1～1 mmol/L。     

柴胡皂甙-d对人肝癌HepG2细胞增殖及细胞周期的影响

目的 探讨柴胡皂甙-d(SSd)对人肝癌HepG2细胞增殖和细胞周期的影响.方法 (1)常规培养人肝癌HepG2细胞;(2)噻唑蓝(MTT)实验观察不同质量浓度SSd处理HepG2细胞72 h后以及10mg/L的SSd作用HepG2细胞不同时间对HepG2细胞生长指数的影响;(3)流式细胞术(FCM)检测SSd处理HepG2细胞48h后细胞周期的分布.结果 SSd能明显抑制HepG2细胞的增殖,以10mg/L的SSd作用48h的抑制作用最明显.FCM检测显示SSd作用48h后实验组处于S期的细胞数较对照组明显减少(P<0.01).结论 SSd对人肝癌HepG2细胞的体外增殖具有抑制作用,并能使细胞周期中处于S期的细胞数减少.     

Atrotoxin: a specific agonist for calcium currents in heart

A specific label for voltage-dependent calcium channels is essential for the isolation and purification of the membrane protein that constitutes the calcium channel and for a better understanding of its function. A fraction of Crotalus atrox that increases voltage-dependent calcium currents in single, dispersed guinea pig ventricular cells was isolated. In the doses used, neither sodium nor potassium currents were changed. The fraction was active in the absence of detectable phospholipase or protease activity, and the active component, designated atrotoxin, produced its effect rapidly and reversibly. The effect was produced by extracellular but not intracellular application of the agent. The increase in Ca2+ current was blocked by the Ca2+ channel blockers cobalt and nitrendipine. The active fraction completely blocked specific [3H]nitrendipine binding to guinea pig ventricular membrane preparations. The inhibition of nitrendipine binding by atrotoxin was apparently via an allosteric mechanism. Thus atrotoxin was shown to bind to the Ca2+ channel and to act as a specific Ca2+ channel agonist.     

Korean hemorrhagic fever: propagation of the etiologic agent in a cell line of human origin

The etiologic agent of Korean hemorrhagic fever has been propagated in a human cultured cell line derived from a carcinoma of the lung. The cells, described as type II, alveolar epithelial, support replication of the agent and successive passages. Antigen of the Korean hemorrhagic fever agent is readily detected in infected cells by means of direct or indirect fluorescent antibody techniques. Previous attempts to propagate this agent in vitro had been unsuccessful.     

Tyramine-H3: deaminated metabolites in neuroblastoma tumors and in continuous cell line of a neuroblastoma

Neuroblastoma tumors, as well as cultured cells of neuroblastoma, contain high monoamine oxidase activity. The major deaminated metabolite of tyramine-H(3) in the incubation mixtures with the tumors or with the cultured cells is p-hydroxyphenylacetaldehyde. Upon addition of reduced nicotinamide-adenine dinucleotide phosphate, the aldehyde was further metabolized by the reductive pathway to p-hydroxyphenylethanol, whereas upon addition of nicotinamide-adenine dinucleotide phosphate the aldehyde was only metabolized to a minor extent by the oxidative pathway to p-hydroxyphenylacetic acid. Aldehyde dehydrogenase activity is very low in the neuroblastoma tumors and in the cultured neuroblastoma cells. The generation of aldehydes and alcohols by the action of monoamine oxidase suggests that the deaminated metabolites of biogenic amines might exhibit some toxic effects in neuroblastoma patients.     

Hybrid cell line from a cloned immunoglobulin-producing mouse myeloma and a nonproducing mouse lymphoma

A hybrid cell line was established by cell fusion between a cloned Balbic myeloma that is resistant to 8-azaguanine and produces immunoglobulin (gammaG and free kappa chain) and C57BL/6N lymphoma that is resistant to bromo-deoxyuridine and does not produce immunoglobulins. The hybrid cells contained the membrane antigens of both parents; they synthesized free kappa chain; no synthesis of gammaG (gamma(2a)) heavy chain was detected.     

Evidence of a pluripotent human embryonic stem cell line derived from a cloned blastocyst

Somatic cell nuclear transfer (SCNT) technology has recently been used to generate animals with a common genetic composition. In this study, we report the derivation of a pluripotent embryonic stem (ES) cell line (SCNT-hES-1) from a cloned human blastocyst. The SCNT-hES-1 cells displayed typical ES cell morphology and cell surface markers and were capable of differentiating into embryoid bodies in vitro and of forming teratomas in vivo containing cell derivatives from all three embryonic germ layers in severe combined immunodeficient mice. After continuous proliferation for more than 70 passages, SCNT-hES-1 cells maintained normal karyotypes and were genetically identical to the somatic nuclear donor cells. Although we cannot completely exclude the possibility that the cells had a parthenogenetic origin, imprinting analyses support a SCNT origin of the derived human ES cells.     

Cytokine-induced expression of HIV-1 in a chronically infected promonocyte cell line

A model system for cytokine-induced up-regulation of human immunodeficiency virus type 1 (HIV-1) expression in chronically infected promonocyte clones was established. The parent promonocyte cell line U937 was chronically infected with HIV-1 and from this line a clone, U1, was derived. U1 showed minimal constitutive expression of HIV-1, but virus expression was markedly up-regulated by a phytohemagglutinin-induced supernatant containing multiple cytokines and by recombinant granulocyte/macrophage colony-stimulating factor alone. Recombinant interleukin-1 (IL-1), IL-2, interferon-gamma, and tumor necrosis factor-alpha did not up-regulate virus expression. Concomitant with the cytokine-induced up-regulation of HIV-1, expression of membrane-bound IL-1 beta was selectively induced in U1 in the absence of induction of other surface membrane proteins. This cytokine up-regulation of IL-1 beta was not seen in the uninfected parent U937 cell line. These studies have implications for the understanding of the mechanism of progression from a latent or low-level HIV-1 infection to a productive infection with resulting immunosuppression. In addition, this model can be used to delineate the potential mechanisms whereby HIV-1 infection regulates cellular gene expression.     

Tyrosine transaminase induction by dexamethasone in a new rat liver cell line

A cell line derived from normal, adult rat liver has been established; the cells are similar to hepatocytes, as shown by electron microscopy. The addition of dexamethasone to the culture medium induced a three- to sixfold increase in the specific activity of tyrosine alpha-ketoglutarate transaminase; this increase was inhibited by the simultaneous addition of cycloheximide or actinomycin D. The latter, when added to cells given prior treatment with dexamethasone, further enhanced the transaminase activity. Contact-inhibited cells showed a lower response to dexamethasone than exponentially growing cells.     

Measles virus matrix protein synthesized in a subacute sclerosing panencephalitis cell line

Measles virus generally produces acute illness. Rarely, however, persistent infection of brain cells occurs, resulting in a chronic and fatal neurological disease, subacute sclerosing panencephalitis (SSPE). Evidence indicates that expression of the measles virus matrix protein is selectively restricted in this persistent infection, but the mechanism underlying this restriction has not been identified. Defective translation of matrix messenger RNA has been described in one SSPE cell line. This report presents evidence that in a different SSPE tissue culture cell line IP-3-Ca, the matrix protein is synthesized but fails to accumulate. A general scheme is proposed to reconcile the different levels at which restriction of matrix protein has been observed.