Biological properties of human melanoma cells in culture

Summary Three human melanoma cell lines derived from one primary and two metastatic tumors from three different patients were characterized for growth properties usually associated with malignant transformation; these include cell morphology, growth rate, saturation density, growth in semisolid media, colony-forming ability on contact-inhibited monolayers of normal fibroblasts and epithelial cells, and tumorigenicity in immunosuppressed mice. Variations in expression of aberrant properties were evident among the lines. One of the metastatic lines satisfied all the parameters of malignancy tested and the other showed a number of these properties, whereas the primary essentially fulfilled only one. These results suggest that cultured melanoma cells reflect the clinical variability often observed among melanoma patients and the metastatic melanoma seems to display a higher degree of malignant transformation than the primary. THis work was supported in part by USPHS Grant No. 5 T01 AI00332-06 from the National Institutes of Health, Contract E73-2001-N01-CP-3-3237 from the Virus Cancer Program of the National Cancer Institute, and USPHS Grant No. 0H00714-02 from the National Institute for Occupational Safety and Health.     

Antimetabolic activities of 2-fluoro-L-histidine.

2-Fluoro-L-Histidine inhibits protein synthesis in various cell cultures, as measured by ³H-leucine incorporation. This histidine analog also inhibits the cytopathogenicity of a number of RNA and DNA viruses in primary and continuous cell cultures; it blocks the transformation of normal mouse (MO) cells by murine sarcoma virus, and partially suppresses the release of murine leukemia virus by a continuously infected mouse cell line (JLSV5). In human skin fibroblasts, it reduces the interferon-inducing capacity of poly(I)·poly(C). Inhibition of cell protein synthesis may be the common cause of the various effects. 4-Fluoro-L-histidine is essentially inert in all of the test systems examined.     

Molecular changes in cell surface membranes resulting from trypsinization of sarcoma 180 tumor cells

Sarcoma-180 tumor cells in culture or grown as an ascites form in the CD-1 mouse have been subjected to mild trypsinization procedures in order to study morphological and molecular changes resulting from proteolysis. The cells attached to a substratum become rounded within 20 min and most undergo cell division, but they do not detach from the substratum. Removal of trypsin permits the cells to go back to their original spindle shape over an 8–20 h period.Surface membranes were isolated from trypsinized ascites and cultured cells and subjected to dodecyl sulfate-acrylamide gel electrophoresis. Both cell types showed the same two kinds of changes in electrophoretic patterns. First, there was a loss of glycoproteins from both cell types, even though they show different complements of cell surface glycoproteins. Second, there is a loss of high molecular weight polypeptides, which have previously been suggested to play a role in membrane stabilization and cell shape. These results further implicate these polypeptides in the control of cell morphology and offer circumstantial evidence for transmembrane interactions of surface glycoproteins with the high molecular weight polypeptides as a factor in controlling cell morphology.     

Perturbation of the chemotactic tumbling of bacteria

The bacterial sensing system has been studied on three levels. First, a quantitative method has been devised for measuring the “action spectrum” of the bacterium in response to a sudden addition of attractant. Second, a technique has been developed for the rapid isolation of mutants defective in the transmission part of the sensing system. Third, a study of the effects of light on the transmission system reveals two components, one which generates tumbling and another which inhibits it.     

Cell shape changes and transmembrane receptor uncoupling induced by tertiary amine local anesthetics

Tertiary amine local anesthetics (dibucaine, Tetracaine, procaine, etc.) modify cell morphology, concanavalin A (Con A)-mediated agglutinability and redistribution of Con A receptors. Con A agglutination of untransformed mouse 3T3 cells was enhanced at low concentrations of local anesthetics, and the dynamics of fluorescent-Con A indicated that ligand-induced clustering was increased in the presence of the drugs. In contast, these drugs inhibited Con A-induced receptor capping on mouse spleen cells. These effects can be duplicated by combinations of vinblastine (or colchicine) and cytochalasin B suggesting that local anesthetics act on microtubule cell surface receptor mobility and distribution. It is proposed that tertiary amine local anesthetics displace plasma membrane-bond Ca²⁺, resulting in disengagement of microfilament systems from the plasma membrane and increased cellular Ca²⁺ concentration to levels which disrupt microtubular organization. The possible involvement of cellular Ca²⁺ in cytoskeletal destruction by local anesthetics was investigated utilizing Ca²⁺-specific ionophores A23187 and X537A. In media containing Ca²⁺ and cytochalasin B these ionophores caused effects similar to tertiary amine local anesthetics.     

Site Variation in Littoral Periphyton Populations: Correlation and Regression with Environmental Factors

Over a six month period, littoral periphyton communities on vertically oriented glass slides were quantitatively sampled from four stations in Elk Lake, British Columbia. Correlation and multiple regression analyses were employed to assess the temporal interrelationships between 15 environmental variables, concurrently measured, and the periphyton populations, expressed as total cell counts and species diversity, for the complete data set of each station. At all stations there was a statistically significant increase in total cell populations with increasing length of slide exposure; positive correlations also occurred with pH, temperature, nitrite, nitrate and copper, while negative ones occurred with oxygen, orthophosphate and hardness (magnesium and total). At all but one station there was a significant decrease in species diversity with increasing slide exposure duration, a decrease attributed to the simultaneous increase in standing crop resulting in intensified competition for diminishing substrate area suitable for cell colonization. Multiple stepwise regression analyses demonstrated that greater than 80% of the variation in periphyton total cells at all four stations could be reliably predicted or described in terms of length of slide exposure, phosphate (ortho and total), and hardness (calcium and total). On the other hand, exposure duration and total cell populations were the most important variables associated with changes in species diversity at three of the four stations. In general, correlations and regressions between standing crop and environmental variables were more statistically reliable and consistent between stations than comparable analyses with species diversity. Use of multiple regression and correlation disclosed the importance of small, non statistically significant variation in ecologically relevant variables and permitted objective comparison of stations.     

Effect of High-Intensity Interval Training on Cardiac Apoptosis Markers in Methamphetamine-Dependent Rats

Chronic methamphetamine use increases apoptosis, leading to heart failure and sudden cardiac death. Previous studies have shown the importance of high-intensity interval training (HIIT) in reducing indices of cardiac tissue apoptosis in different patients, but in the field of sports science, the molecular mechanisms of apoptosis in methamphetamine-dependent rats are still unclear. The present article aimed to investigate the changes in cardiac apoptosis markers in methamphetamine-dependent rats in response to HIIT. Left ventricular tissue was used to evaluate caspase-3, melusin, FAK, and IQGAP1 gene expression. Rats were divided into four groups: sham, methamphetamine (METH), METH-control, and METH-HIIT. METH was injected for 21 days and then the METH-HIIT group performed HIIT for 8 weeks at 5 sessions per week. The METH groups showed increased caspase-3 gene expression and decreased melusin, FAK, and IQGAP1 when compared to the sham group. METH-HIIT showed decreased caspase-3 and increased melusin and FAK gene expression compared with the METH and METH-control groups. The IQGAP1 gene was higher in METH-HIIT when compared with METH, while no difference was observed between METH-HIIT and METH-control. Twenty-one days of METH exposure increased apoptosis markers in rat cardiac tissue; however, HIIT might have a protective effect, as shown by the apoptosis markers.     

抑郁症易感基因和抗抑郁药物靶点相关[]神经细胞类型及相互作用网络分析

基于抑郁症的全基因组关联分析研究(GWAS),对于获得的单核苷酸多态性位点(SNP)使用Haploreg软件进行基因注释,得到SNP注释的102个易感基因.。使用MAGMA软件对GWAS的汇总统计数据做基因水平的分析,获得了270个校正之后显著的基因,两者合并共得到320个抑郁症易感基因。通过药物数据库Drugbank获取133个抗抑郁药物靶点基因。使用EWCE包对抑郁症易感基因和抗抑郁药物靶点在三套脑组织单细胞测序数据中,分别进行神经细胞类型富集分析。结果发现大脑皮质的GABA神经元(抑制性神经元)和谷氨酸能神经元(兴奋性神经元)是抑郁症易感基因和抗抑郁药物靶点共同的神经元。这两种类型的神经细胞可能是抗抑郁药物与抑郁症易感基因相互作用的神经细胞,另外少突胶质前体细胞可能是抑郁症特有的易感神经细胞。使用Network Calculator软件构建网络并进行进行网络拓扑学参数分析。结果表明抑郁症易感基因与抗抑郁药物靶点组成了一个具有显著的相互连接的网络。本研究从单细胞层面揭示抑郁症的遗传机制,在网络层面为寻找新的抗抑郁药物靶点提供了一定的启示。     

Reversible bacteriophage resistance by shedding the bacterial cell wall

Phages are highly abundant in the environment and pose a major threat for bacteria. Therefore, bacteria have evolved sophisticated defence systems to withstand phage attacks. Here, we describe a previously unknown mechanism by which mono- and diderm bacteria survive infection with diverse lytic phages. Phage exposure leads to a rapid and near-complete conversion of walled cells to a cell-wall-deficient state, which remains viable in osmoprotective conditions and can revert to the walled state. While shedding the cell wall dramatically reduces the number of progeny phages produced by the host, it does not always preclude phage infection. Altogether, these results show that the formation of cell-wall-deficient cells prevents complete eradication of the bacterial population and suggest that cell wall deficiency may potentially limit the efficacy of phage therapy, especially in highly osmotic environments or when used together with antibiotics that target the cell wall.