Not so lonely at the top for cancer stem cells

A subpopulation of cancer cells is believed to be responsible for tumor initiation, propagation, and metastasis. In this issue of Cell Stem Cell, Dieter et?al. (2011) show that these functions in colon cancer can be ascribed to distinct tumor-initiating cell populations.     

Sensitivity of the mosquito Aedes aegypti (Culicidae) labral apical chemoreceptors to blood plasma components

The phagostimulants from the cellular fraction of blood induce gorging of Aedes aegypti (L.), and this process is enhanced by some plasma components. This project examines the responses of the labral apical chemoreceptors to plasma components enhancing phagostimulation. From the electrophysiological responses of the labral apical chemoreceptors four cells were identified by the waveform of their action potentials. Three of the cells (Cell 2, Cell 3 and Cell 4) responded in a dose dependent manner to NaCl. The responses of Cell 2 and Cell 3 to NaCl concentrations from 1 to 500 mmol/l can be described by a logarithmic equation. The response of Cell 2 to 150 mmol/l NaCl is modulated when a buffer is added. The magnitude of the modulation of the response is determined by the nature of the buffer: NaHCO(3) inhibits while Na(2)HPO(4) enhances the response. High osmotic pressure inhibits the response of Cell 4, regardless of how it is achieved. Cell 4 responds with a high frequency to the presence of L-alanine, the C-terminal amino acid of albumin, but shows a reduced response to the same concentration of albumin. From these results it can be concluded that labral apical chemoreceptors of A. aegypti are capable of detecting the plasma components involved in blood recognition.     

Stem Cells and β Cells: The Same,but Different?

Researchers have long debated whether new pancreatic β cells derive from stem cells or from pre-existing β cells. A new study in this issue of Cell Stem Cell (Smukler et al., 2011) suggests that both sides may be right.     

Common signaling networks characterize leukemia-initiating cells in acute myeloid leukemia

Identification and characterization of leukemia-initiating cells (LICs) is important to understand leukemogenesis and develop novel therapies for leukemia. In this issue of Cell Stem Cell, Gibbs et?al. (2012) demonstrate that common active signaling pathways in LICs may be targeted to treat acute myeloid leukemia.     

When BMP meets FGF

Bone morphogenic proteins (BMPs) act as inducers of diverse cellular fates in human embryonic stem cells, but the mechanisms responsible remain poorly understood. In this issue of Cell Stem Cell, Bernardo et?al. (2011) demonstrate that different BMP-induced differentiation programs may be orchestrated by similar key target genes.     

Primed for pluripotency

To date, pluripotent epiblast stem cells (EpiSCs) had only been derived from postimplantation mouse embryos. In this issue of Cell Stem Cell, Najm et al. (2011) demonstrate that EpiSCs can be routinely derived from preimplantation embryos, showing that both human and mouse blastocysts can produce the same class of primed pluripotent cells.     

Cancer: Inappropriate Expression of Stem Cell Programs?

Cancer stem cells (CSCs) are a subpopulation of cancer cells that possess characteristics, including self-renewal, associated with normal stem cells. In this issue of Cell Stem Cell, Wong et al. (2008) define a core embryonic stem cell (ESC)-like gene expression program that may be important for CSC function in multiple epithelial cancers.     

Notch in the niche

Notch signaling is essential for hematopoietic stem cell (HSC) formation during embryogenesis, and hitherto it was also thought to be required for HSC maintenance. However, in this issue of Cell Stem Cell, Maillard et al. (2008) demonstrate rather conclusively that inactivation of the Notch pathway in HSCs does not interfere with their self-renewal.     

Synthetic mRNAs: powerful tools for reprogramming and differentiation of human cells

In this issue of Cell Stem Cell, Warren et?al. (2010) describe a new methodology, using synthetic mRNA, for efficiently generating iPSCs without compromising genomic integrity. This powerful approach can also be used for directed differentiation of iPSCs, or even for trans-differentiation to generate clinically relevant differentiated cell types.     

Restoring cell polarity: an HSC fountain of youth

Until recently, aging was viewed as a fixed and irreversible process. However, in this issue of Cell Stem Cell, Florian et?al. (2012) reveal a link between increased activity of the RhoGTPase Cdc42, hematopoietic stem cell polarity, and aging that can be regulated by pharmacological inhibition of Cdc42.     

The pessimist's and optimist's views of adult neurogenesis

The reports by Bonaguidi et?al. (in this issue of Cell) and Encinas et?al. (in Cell Stem Cell) come to differing conclusions about whether and how the proliferation of radial glia-like stem cells of the adult hippocampus impacts their long-term potential for neurogenesis.     

New achievements in human cell toxicology: the 20th annual workshop on in vitro toxicology

The 20th Annual Workshop on In Vitro Toxicology (Oxford, UK, September 22-24, 2002) was convened as part of a European meeting entitled Human Cell Culture 2002. The meeting was arranged by the Scandinavian Society for Cell Toxicology (SSCT), the European Tissue Culture Society and the British Prostate Group. Two sessions, which are summarised in this report, were devoted to in vitro toxicology: Human Cell Toxicology and The SSCT Free Paper Session. Outstanding experts in the field of toxicology outlined contemporary approaches in toxicity testing in their lectures. Short oral presentations demonstrated a variety of in vitro model systems and methodologies, which can be useful for investigating human toxicity, as well as for studies on mechanisms of toxicity.     

Adsorption of chromium (VI) ion from aqueous solution by succinylated mercerized cellulose functionalized with quaternary ammonium groups

Succinylated mercerized cellulose (cell 1) was used to synthesize an anion exchange resin. Cell 1, containing carboxylic acid groups was reacted with triethylenetetramine to introduce amine functionality to this material to obtain cell 2. Cell 2 was reacted with methyl-iodide to quaternize the amine groups from this material to obtain cell 3. Cells 2 and 3 were characterized by mass percent gain, degree of amination and quaternization, FTIR and CHN. Cells 2 and 3 showed degrees of amination and quaternization of 2.8 and 0.9 mmol/g and nitrogen content of 6.07% and 2.13%, respectively. Cell 3 was used for Cr (VI) adsorption studies. Adsorption equilibrium time and optimum pH for Cr (VI) adsorption were found to be 300 min and 3.1, respectively. The Langmuir isotherm was used to model adsorption equilibrium data. The adsorption capacity of cell 3 was found to be 0.829 mmol/g. Kinetic studies showed that the rate of adsorption of Cr (VI) on cell 3 obeyed a pseudo-second-order kinetic model.     

Targeting gene-virotherapy of cancer

Due to concerns regarding the overlapping figures in this review that are identical to those contained in a reviewarticle that we have co-authored and published earlier,we retract the above paper we published in Cell Research.Weapologize for any confusion that may be caused by this matter,although we stand by the scientific contents containedin the Cell Research paper.     

Book reviews

Books review in this article:
The Regulation and Control of Cell Proliferation . Ed. By K. Lapis and A. Jeney.
Cell Kinetics and Cancer Therapy . By Juliana Denekamp. Charles C. Thomas
The Biology of Epithelial Cell Populations (2 Vol.). By N. Wright and M. Alison.     

Cell biology of virus entry: a review of selected topics from the 3rd International Frederick meeting

Following the first two Frederick meetings on virus entry in 1997 [Cell 91 (1997) 721](1) and in 2000 [Cell 101 (2000) 697](2), further developments in our understanding of the multifactorial and multistage process of virus entry, and possible biomedical implications were presented and discussed in a lively fashion by leading scientists from around the world at the third Frederick meeting on the Cell Biology of Viral Entry (May 7-10, Frederick, MD) organized by R. Blumenthal (NCI-Frederick, NIH, Frederick) and E. Hunter (University of Alabama, Birmingham). Unlike the previous two meetings, non-enveloped viruses were not discussed this time, and the focus was how envelope glycoproteins (Envs) mediate entry into cells. Major topics included Env structure, virus receptors, entry intermediates, membrane fusion, fusion kinetics, and rafts. Virus envelope structures will be described in more detail here because the other topics are extensively discussed in the other chapters of this volume.     

Quantitative analysis of random migration of cells using time-lapse video microscopy

Cell migration is a dynamic process, which is important for embryonic development, tissue repair, immune system function, and tumor invasion (1, 2). During directional migration, cells move rapidly in response to an extracellular chemotactic signal, or in response to intrinsic cues (3) provided by the basic motility machinery. Random migration occurs when a cell possesses low intrinsic directionality, allowing the cells to explore their local environment. Cell migration is a complex process, in the initial response cell undergoes polarization and extends protrusions in the direction of migration (2). Traditional methods to measure migration such as the Boyden chamber migration assay is an easy method to measure chemotaxis in vitro, which allows measuring migration as an end point result. However, this approach neither allows measurement of individual migration parameters, nor does it allow to visualization of morphological changes that cell undergoes during migration. Here, we present a method that allows us to monitor migrating cells in real time using video - time lapse microscopy. Since cell migration and invasion are hallmarks of cancer, this method will be applicable in studying cancer cell migration and invasion in vitro. Random migration of platelets has been considered as one of the parameters of platelet function (4), hence this method could also be helpful in studying platelet functions. This assay has the advantage of being rapid, reliable, reproducible, and does not require optimization of cell numbers. In order to maintain physiologically suitable conditions for cells, the microscope is equipped with CO(2) supply and temperature thermostat. Cell movement is monitored by taking pictures using a camera fitted to the microscope at regular intervals. Cell migration can be calculated by measuring average speed and average displacement, which is calculated by Slidebook software.     

The complex relationship between mycobacteria and macrophages: it's not all bliss

Mycobacteria are uniquely adapted to grow inside host macrophages. As Clay et al. show in this issue of Cell Host & Microbe and as van der Wel et al. show in a recent issue of Cell, there are both benefits and drawbacks for the pathogen in adopting this strategy, and some of our fundamental assumptions about how the host cell and bacterium interact might need to be reexamined.     

Homologous recombination is promoted by translesion polymerase poleta

Two new studies provide in vivo ( [this issue of Molecular Cell]) and in vitro ( [this issue of Molecular Cell]) evidence that poleta functions to extend 3' strands exchanged during homologous recombination and raise the issue of how TLS polymerases are selected onto different substrates.     

Connecting mitochondria and innate immunity

Viral infection results in the activation of multiple signaling pathways, but how these pathways are coordinated remains a mystery. Two studies, one published in this issue of Cell (Seth et al., 2005) and the other in Molecular Cell (Xu et al., 2005), identify a new intracellular signaling protein that is required for activating type I interferon expression in response to viral infection. In addition,Seth et al. (2005) show that the function of this protein, which they call MAVS, requires that it be localized to the mitochondria. This observation establishes an unexpected link between innate immunity and an organelle with evolutionary origins in aerobic bacteria.