MDR1, cholesterol certification and cell growth: a comparative study in normal and multidrug-resistant KB cell lines

The product of the MDR1 gene (P-gp) has been implicated in the transport of cholesterol from plasma membrane to endoplasmic reticulum for esterification. In previous studies on leukemia cell lines, we suggested that cholesterol esterification may regulate the rate of cell growth and that the MDR1 gene might be involved in this process by modulating intracellular cholesterol esters levels. To further investigate this matter, the rate of cell growth, cholesterol metabolism, expression of the MDR1 gene, and P-gp activity were compared in KB cell lines displaying differences in expression and function of P-gp (drug-sensitive phenotype versus MDR phenotype). The rate of cell growth correlated with cholesterol esterification in all KB cell lines, whereas the over-expression of MDR1 observed in the MDR cell lines was not always associated with an increased capacity of cells to esterify cholesterol. Two known inhibitors of P-gp activity, progesterone and verapamil, strongly inhibited both cholesterol esterification and cell proliferation in all KB cell lines, but they affected intracellular accumulation of labeled vinblastine only in MDR cell lines. These results further support a role for cholesterol esters in the regulation of cell growth and suggest that the P-gp expressed in MDR KB cells is not involved in the general process leading to cholesterol esterification. Received 14 February 2000; received after revision 10 April 2000; accepted 8 May 2000     

Negative phototaxis inDrosophila associated with a morphological change in the compound eye

Summary The ultrastructure of the compound eyes of several photonegative selection lines and their unselected photopositive controls of five species of themelanogaster subgroup was analyzed. A qualitative phenotypic change concerning the rhabdomeres in one of the photonegative selection lines ofD. mauritiana could be detected. It was proved that this structural aberration of the rhabdomeres is caused by a parallel mutation of the mutantora (outer rhabdomeres absent) ofD. melanogaster.     

Role of toxins in evolution and ecology of plant pathogenic fungi

Many fungal pathogens of plants adapt readily to changes in agriculture. Among the most revealing is a fungal group whose species produce host-selective toxins as key determinants of disease. Several lines of evidence support the hypothesis that these fungi evolved from opportunistic, low-grade pathogens by gaining new genetic information leading to toxin production; in some species, toxin production is known to be under single gene control. as a result of this evolution, these fungi became virulent and host-specialized. The best-known model cases belong to the generaCochliobolus andAlternaria; there are suggestions of evolutionary lines among these genera, with species that range from saprophytes to opportunists to specialized pathogens. Host specialization can lead to genetic isolation, a first step in speciation. Ability to produce host-selective toxin has allowed these fungi to exploit the monocultures and genetic uniformity of modern agriculture. Destructive epidemics have been the result.     

Possible involvement of the phloem sealing system in the acceptance of a plant as host by an aphid

Possible reasons for the rejection of some lines ofTriticum monococcum (Tm44 and Tm46) by the aphidSitobion avenae were explored. In allT. monococcum lines studied, whether unfavourable (non-host/resistant plant) or favourable (host/susceptible plant), the concentrations of hydroxamic acids, a family of aphid-resistance factors in cereals, were significantly lower than the levels in the favourable host-plantTriticum aestivum cv. Therefore, hydroxamic acids did not account for the host/non-host patterns observed. Phloem sap was collected by stylectomy from young seedlings of favourable and unfavourable plants. In non-aphid-resistant genotypes, the success in stylectomy, the proportion of amputated stylets resulting in long (>1 min) exudations, the average duration of exudation, and the final volume of sap exuded, were higher than in the aphid-resistant genotypes. It is concluded that aphid interference with the phloem sealing system of the plant is a likely mechanism of rejection ofT. monococcum lines Tm44 and Tm46 as hosts byS. avenae.     

Extensive characterization of sphere models established from colorectal cancer cell lines

Links between cancer and stem cells have been proposed for many years. As the cancer stem cell (CSC) theory became widely studied, new methods were developed to culture and expand cancer cells with conserved determinants of “stemness”. These cells show increased ability to grow in suspension as spheres in serum-free medium supplemented with growth factors and chemicals. The physiological relevance of this phenomenon in established cancer cell lines remains unclear. Cell lines have traditionally been used to explore tumor biology and serve as preclinical models for the screening of potential therapeutic agents. Here, we grew cell-forming spheres (CFS) from 25 established colorectal cancer cell lines. The molecular and cellular characteristics of CFS were compared to the bulk of tumor cells. CFS could be isolated from 72 % of the cell lines. Both CFS and their parental CRC cell lines were highly tumorigenic. Compared to their parental cells, they showed similar expression of putative CSC markers. The ability of CRC cells to grow as CFS was greatly enhanced by prior treatment with 5-fluorouracil. At the molecular level, CFS and parental CRC cells showed identical gene mutations and very similar genomic profiles, although microarray analysis revealed changes in CFS gene expression that were independent of DNA copy-number. We identified a CFS gene expression signature common to CFS from all CRC cell lines, which was predictive of disease relapse in CRC patients. In conclusion, CFS models derived from CRC cell lines possess interesting phenotypic features that may have clinical relevance for drug resistance and disease relapse.     

Genetic analysis of modifier variability inDrosophila subobscura

Summary The previously detected modifier variability acting on the expression of the Bare (Ba) locus inDrosophila subobscura is demonstrated to be due to polygenes situated along the chromosome O. From crosses between isogenic lines of high and low modifier effect we ascertained the presence of approximately 5 modifier loci.We are grateful to Dr M. Green for valuable comments on the experimental design used in this paper.     

Karyological studies on established mosquito cell lines

Chromosome frequency distribution and cellular DNA estimations in different established mosquito cell lines were studied. These cell lines exhibited a wide range of cell types with a diploid stem-line comprising 50-55% and a haploid substem-line comprising 12-30% of the population. Estimation of cellular DNA contents by impulse cytoflowmetry and by Feulgen cytophotometry supported these observations. Because of their low diploid counts, these cell lines cannot be classified as diploid.     

Plants as a direct source of fuel

Summary Euphorbia lathyris, a plant which has been proposed as an energy farm candidate yields a total of 35% of its dry weight as simple organic extractables. Chemical analyses of the extracts show that 5% of the dry weight is a mixture of reduced terpenoids, in the form of triterpenoids, and 20% of the dry weight is simple sugars in the form of hexoses. The terpenoids can be converted to a gasoline-like substance and the sugars can be fermented to alcohol. Based on a biomass yield of about 25 dry tons ha^–1 year^–1, the total energy that can be obtained from this plant in the form of liquid fuels is 48 MJ ha^–1 year^–1, 26 MJ in the form of hydrocarbons and 22 MJ in the form of ethanol. A conceptual process study for the large scale recovery ofEuphorbia lathyris products indicates that this crop is a net energy producer. Several lines of investigation have been started to increase the hydrocarbon yield of this plant. Tissue cultures ofE. lathyris have been established and will be used for selection, with the aim of regenerating a superior plant. Biochemical studies have been initiated to elucidate regulation of terpenoid metabolism. Future plans include eventual genetic engineering to select the most desirable plant for hydrocarbon production.This work was supported by the Assistant Secretary for Conservation and Solar Energy, Office of Solar Energy, Solar Applications for Industry Division of the US Department of Energy under Contract No. W-7405-ENG-48.     

Targeted inhibition of Livin resensitizes renal cancer cells towards apoptosis

Cancer cells are typically characterized by apoptosis deficiency. In order to investigate a possible role for the anti-apoptotic livin gene in renal cell cancer (RCC), we analyzed its expression in tumor tissue samples and in RCC-derived cell lines. In addition, we studied the contribution of livin to the apoptotic resistance of RCC cells by RNA interference (RNAi). Livin gene expression was detected in a significant portion of RCC tumor tissue specimens (13/14, 92.9%) and tumor-derived cell lines (12/15, 80.0%). Moreover, targeted inhibition of livin by RNAi markedly sensitized RCC cells towards proapoptotic stimuli, such as UV irradiation or the chemotherapeutic drugs etoposide, 5-fluorouracil, and vinblastine. These effects were specific for livin expressing tumor cells. We conclude that livin can contribute significantly to the apoptosis resistance of RCC cells. Targeted inhibition of livin could represent a novel therapeutic strategy to increase the sensitivity of renal cancers towards pro-apoptotic agents. Received 30 November 2006; received after revision 22 February 2007; accepted 20 March 2007     

Arachidonic acid release by ionomycin and phorbol ester is similar in C127 epithelial cells expressing wild-type or mutated (ΔF508) cystic fibrosis transmembrane conductance regulator

The Ca²⁺ ionophore ionomycin induced cytosolic [Ca²⁺]_i elevation as well as strong activation of Cl⁻ efflux in mouse mammary epithelial cell lines expressing wild-type or mutated (deletion of phenylalaline 508) cystic fibrosis transmembrane conductance regulator (CFTR) or vector. Ionomycin-induced Cl⁻ efflux was abolished by the intracellular Ca²⁺ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid, whereas both activators and inhibitors of phospholipase A₂ had no effect, indicating the involvement of Ca²⁺-dependent Cl^- channels. Stimulation of arachidonic acid release by ionomycin and phorbol ester was not significantly different between wild-type or mutated cell lines, whereas vector-transfected cells exhibited a significant higher release, which was shown to be due to larger amount of immunoreactive cytosolic phospholipase A₂. These results indicate that phospholipase A₂ activity of C127 cells was not influenced by the presence of wild-type or mutated CFTR. Received 27 April 1999; received after revision 11 June 1999; accepted 23 July 1999     

Radial skeletal dissolution to promote vegetative reproduction in a solitary coralDiaseris distorta

The solitary, free-living coralDiaseris distorta (Michelin) (Fungiidae, Scleractinia) reproduces asexually by fragmentation along radially oriented slits. Localized skeletal dissolution, which can be recognized as white, opaque and chalky lines along the thecal wall between segments, ultimately results in autotomy. We suggest that the skeletal dissolution which dissolves the weakest part of the corallum for easy breakage, is a species-specific character.     

Biotransformation of the flavonoid tiliroside to 7-methylether tiliroside: bioactivity of this metabolite and of its acetylated derivative

Incubation of kaempferol-3-O-β-D-(6"-E-p-coumaroyl)-glucopyranoside (tiliroside) (1) with Aspergillus nidulans gives the 7-methyl ether of tiliroside (2) which is a new compound. Its structure is determined by spectroscopic methods. Cytotoxic studies of 2 and of its acetylated derivative 2a were carried out in vitro against fourteen human leukemic cell lines. Results clearly show that compound 2 is ineffective against all leukemic cell lines tested. On the contrary, compound 2a exhibited cytotoxic activity against four of the cell lines (HL60, DAUDI, HUT78 and MOLT3) and additionally, a dose- and time-dependent effect on DNA synthesis. Received 18 February 1997; received after revision 8 April 1997; accepted 6 May 1997     

Comparative studies on the covalent binding of the carcinogen benzo(a)pyrene to DNA in various model systems

Summary The covalent binding of tritiated benzo(a) pyrene (BP) to DNA has been determined in rat liver in vivo, in rat liver perfused in situ, after incubation of BP with liver single cells, with liver homogenate, with liver microsomes and DNA, with fibroblasts from a rat granuloma pouch, and with 2 cell lines. Liver single cells were found to be a valuable compromise between the most sensitive system (microsomal incubation of BP with DNA) and the biologically most relevant system (in vivo).Presented in part at the 10th Annual Meeting of the Union of Swiss Societies of Experimental Biology, Experientia34, 925 (1978), abstract.Acknowledgment. We thank Dr G. Kistler, Institute of Anatomy, University of Zurich, for generously supplying the SIRC and VERO cell lines, and Mr P. Manser for the preparation of the granuloma pouch fibroblasts.     

Isolierung anthocyanhaltiger und anthocyanfreier Gewebestämme vonDaucus carota: Einfluss von Auxinen auf die Anthocyanbildung

Summary The isolation of anthocyanin-producing and non-producing cell lines of tissue cultures ofDaucus carota is described. Those clones which are able to synthesize anthocyanins do this in dark only if there is an auxin like 2,4-D, IAA or NAA present. In light no supplementary auxin is necessary for anthocyanin production. It is assumed that there might be relations between auxin and light-induced anthocyanin biosynthesis.     

From William Hyde Wollaston to Alexander von Humboldt - Star Spectra and Celestial Landscape

The discovery of dark lines in the spectrum of the sun as well as in some fixed stars since 1802 by William Hyde Wollaston, Joseph Fraunhofer and Johann Lamont is a relatively isolated phenomenon in the history of astronomy of the first half of the 19th century. Wollaston's representation of the sun's spectrum of 1802 can be seen as a simplification and reduction of the phenomenon by way of a seemingly clear connection with contemporary knowledge. Fraunhofer's famous colour etching of the dark lines, of about 1817, can be regarded as a meticulous and painstaking representation of the known facts, taken to a high aesthetic level.

Lamont's spectra of the fixed stars from 1836 are the first sketches of all of these phenomena. He emphasized the ‘oddness’, that is, the chaotic variety of identifiable lines. What was common to all of these representations was the general belief that something new and unimaginable could now be established as a scientific subject. The observations of these lines were coincidental with the thinking in other fields, as for example, in Alexander Humboldt's understanding of nature, in Johann Wolfgang von Goethe's theory of light and his interest in pictorial representations of nature, and in the new concept of landscape of the romantic painters.     

Die Veränderungen der Succinodehydrase-Aktivität in Detroit-6 (VA) Zellen,infolge der Infektion mit demHepatitis-infectiosa-Virus

Summary The inhibitory action ofHepatitis infectiosa virus on the SDH activity of Detroit-6 (VA) cell lines was investigated. The full inhibition of the SDH activity took place at the end of the third day after the infection. As this phenomenon precedes the cytopathogenetic effect of viral infection, it may be of some help in the early detection of the infection.     

Enrichment of ligands with molecular dockings and subsequent characterization for human alcohol dehydrogenase 3

Alcohol dehydrogenase 3 (ADH3) has been assigned a role in nitric oxide homeostasis due to its function as an S-nitrosoglutathione reductase. As altered S-nitrosoglutathione levels are often associated with disease, compounds that modulate ADH3 activity might be of therapeutic interest. We performed a virtual screening with molecular dockings of more than 40,000 compounds into the active site of human ADH3. A novel knowledge-based scoring method was used to rank compounds, and several compounds that were not known to interact with ADH3 were tested in vitro. Two of these showed substrate activity (9-decen-1-ol and dodecyltetraglycol), where calculated binding scoring energies correlated well with the logarithm of the k _cat/K _m values for the substrates. Two compounds showed inhibition capacity (deoxycholic acid and doxorubicin), and with these data three different lines for specific inhibitors for ADH3 are suggested: fatty acids, glutathione analogs, and cholic acids.     

Atoms, complexes, and demonstration: Posterior analytics 96b15-25

There is agreement neither concerning the point that is being made in Posterior analytics 96b15–25 nor the issue Aristotle intends to address. There are two major lines of interpretation of this passage. According to one, sketched by Themistius and developed by Philoponus and Eustratius, Aristotle is primarily concerned with determining the definitions of the infimae species that fall under a certain genus. They understand Aristotle as arguing that this requires collating definitional predictions, seeing which are common to which species. Pacius, on the other hand, takes Aristotle to be saying that a genus is studied scientifically through first determining the infimae species that fall under that genus. This interpretation attributes to Aristotle a distinction between primary and derivative subjects. I argue for Pacius’s interpretation, defending it against Barnes’s objections.