Effect of long-term culture of a human laryngeal carcinoma cell line on epitectin production and tumorigenicity in athymic mice

Epitectin is a high molecular weight mucin-type glycoprotein over-expressed on the surface of human carcinoma cells. In cancer cells, it is proposed to play a protective function and to modulate cell surface properties such as antigenicity and cell adhesion. We have examined the effect of long-term culture on the cell curface expression of epitectin by a human laryngeal carcinoma cell line and the correlation between epitectin expression and tumor production in athymic mice. Indirect immunofluorescence labelling using an epitectin specific monoclonal antibody showed that the level of epitectin on the cell surface was significantly reduced after 78 or more generations in culture. Gel electrophoresis of cell extracts, followed by wheat germ agglutinin and peanut agglutinin overlay analyses, demonstrated similar losses in total cellular epitectin as a result of prolonged passage in culture. The levels of other glycoproteins reacting with wheat germ agglutinin were not significantly altered in high passage cells. Similar results were obtained when HMFG-2 monoclonal antibody was used to probe the levels of cell surface epitectin. In contrast to the above probes, the binding of HMFG-2 to epitectin is independent of glycosylation, therefore it can be concluded that the observed changes are not due to aberration in epitectin glycosylation with increasing passage number but rather due to lack of synthesis of epitectin. The ability of the low epitectin producing H.Ep.2 cells to grow as tumors in athymic mice was reduced compared to the high epitectin producing cells.This work comprises part of a doctoral thesis by N.A.D. submitted to the Pennsylvania State University.     

Plain faces are more expressive: comparative study of facial colour,mobility and musculature in primates

Facial colour patterns and facial expressions are among the most important phenotypic traits that primates use during social interactions. While colour patterns provide information about the sender''s identity, expressions can communicate its behavioural intentions. Extrinsic factors, including social group size, have shaped the evolution of facial coloration and mobility, but intrinsic relationships and trade-offs likely operate in their evolution as well. We hypothesize that complex facial colour patterning could reduce how salient facial expressions appear to a receiver, and thus species with highly expressive faces would have evolved uniformly coloured faces. We test this hypothesis through a phylogenetic comparative study, and explore the underlying morphological factors of facial mobility. Supporting our hypothesis, we find that species with highly expressive faces have plain facial colour patterns. The number of facial muscles does not predict facial mobility; instead, species that are larger and have a larger facial nucleus have more expressive faces. This highlights a potential trade-off between facial mobility and colour patterning in primates and reveals complex relationships between facial features during primate evolution.     

Monitoring Bacillus thuringiensis-susceptibility in insect pests that occur in large geographies: how to get the best information when two countries are involved

The adoption of cotton producing insecticidal proteins of Bacillus thuringiensis, commonly referred to as Bt cotton, around the world has proven to be beneficial for growers and the environment. The effectiveness of this important genetically-modified crop can be jeopardized by the development of resistance to Bt cotton by pests it is meant to control, with the possibility that this phenomenon could develop in one country and spread to another by means of insect migration. To preserve the effectiveness of this agricultural biotechnology, regulatory agencies have developed plans to mitigate the development of resistance, and research institutions constantly monitor for shifts in Bt-susceptibility in important pests. If Bt-resistance is detected, this finding needs to be corroborated by an independent laboratory according to current regulatory requirements; a process that presents numerous challenges. We investigated the biological activity of Bt-incorporated diet on Helicoverpa virescens L. after it was stored for several days at different temperatures. Diet stored up to nine days at different temperatures (-14 to 27 degrees C) produced the same biological effect on H. virescens as freshly-prepared diet. Elevating the temperature of Bt stock solution to 76 degrees C as compared to 26 degrees C yielded significantly higher reading of apparent Cry1Ac concentration from MVP II, but not enough to elicit a significant biological response when these stock solutions were incorporated into insect artificial diet. These findings are important particularly when the confirmation of resistance is done at a distant location, such as Mexico, or when diet is shared between laboratories, and must be stored for later use, as in the case of international collaboration.     

EGFR-Aurka Signaling Rescues Polarity and Regeneration Defects in Dystrophin-Deficient Muscle Stem Cells by Increasing Asymmetric Divisions

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Neuronal HSF-1 coordinates the propagation of fat desaturation across tissues to enable adaptation to high temperatures in C. elegans

To survive elevated temperatures, ectotherms adjust the fluidity of membranes by fine-tuning lipid desaturation levels in a process previously described to be cell autonomous. We have discovered that, in Caenorhabditis elegans, neuronal heat shock factor 1 (HSF-1), the conserved master regulator of the heat shock response (HSR), causes extensive fat remodeling in peripheral tissues. These changes include a decrease in fat desaturase and acid lipase expression in the intestine and a global shift in the saturation levels of plasma membrane’s phospholipids. The observed remodeling of plasma membrane is in line with ectothermic adaptive responses and gives worms a cumulative advantage to warm temperatures. We have determined that at least 6 TAX-2/TAX-4 cyclic guanosine monophosphate (cGMP) gated channel expressing sensory neurons, and transforming growth factor ß (TGF-β)/bone morphogenetic protein (BMP) are required for signaling across tissues to modulate fat desaturation. We also find neuronal hsf-1 is not only sufficient but also partially necessary to control the fat remodeling response and for survival at warm temperatures. This is the first study to show that a thermostat-based mechanism can cell nonautonomously coordinate membrane saturation and composition across tissues in a multicellular animal.

In response to heat, ectotherms exhibit an adaptive response characterized by changes in membrane fluidity. This study in the nematode Caenorhabditis elegans shows that neuronal HSF-1 is critical for this remodeling, suggesting a neuronal thermostat-based mechanism that can non-cell-autonomously coordinate the animal’s response to heat.     

Identification of an Intragenic Ribosome Binding Site That Affects Expression of the uncB Gene of the Escherichia coli Proton-Translocating ATPase (unc) Operon

The uncB gene codes for the a subunit of the F_o proton channel sector of the Escherichia coli F₁ F_o ATPase. Control of expression of uncB appears to be exerted at some step after translational initiation. Sequence analysis by the perceptron matrices (G. D. Stormo, T. D. Schneider, L. Gold, and A. Ehrenfeucht, Nucleic Acids Res. 10:2997–3011, 1982) identified a potential ribosome binding site within the uncB reading frame preceding a five-codon reading frame which is shifted one base relative to the uncB reading frame. Elimination of this binding site by mutagenesis resulted in a four- to fivefold increase in expression of an uncB′-′lacZ fusion gene containing most of uncB. Primer extension inhibition (toeprint) analysis to measure ribosome binding demonstrated that ribosomes could form an initiation complex at this alternative start site. Two fusions of lacZ to the alternative reading frame demonstrated that this site is recognized by ribosomes in vivo. The results suggest that expression of uncB is reduced by translational frameshifting and/or a translational false start at this site within the uncB reading frame.     

A pilot study of combined working memory and inhibition training for children with AD/HD

Building on recent favourable outcomes using working memory (WM) training, this study examined the behavioural and physiological effect of concurrent computer-based WM and inhibition training for children with attention-deficit hyperactivity disorder (AD/HD). Using a double-blind active-control design, 29 children with AD/HD completed a 5-week at-home training programme and pre- and post-training sessions which included the assessment of overt behaviour, resting EEG, as well as task performance, skin conductance level and event-related potentials (ERPs) during a Go/Nogo task. Results indicated that after training, children from the high-intensity training condition showed reduced frequency of inattention and hyperactivity symptoms. Although there were trends for improved Go/Nogo performance, increased arousal and specific training effects for the inhibition-related N2 ERP component, they failed to reach standard levels of statistical significance. Both the low- and high-intensity conditions showed resting EEG changes (increased delta, reduced alpha and theta activity) and improved early attention alerting to Go and Nogo stimuli, as indicated by the N1 ERP component, post-training. Despite limitations, this preliminary work indicates the potential for cognitive training that concurrently targets the interrelated processes of WM and inhibition to be used as a treatment for AD/HD.     

Ectopic expression of the Stabilin2 gene triggered by an intracisternal A particle (IAP) element in DBA/2J strain of mice

Mammalian Genome - Stabilin2 (Stab2) encodes a large transmembrane protein which is predominantly expressed in the liver sinusoidal endothelial cells (LSECs) and functions as a scavenger receptor...