Cell-sized liposome doublets reveal active tension build-up driven by acto-myosin dynamics

Cells modulate their shape to fulfill specific functions, mediated by the cell cortex, a thin actin shell bound to the plasma membrane. Myosin motor activity, together with actin dynamics, contributes to cortical tension. Here, we examine the individual contributions of actin polymerization and myosin activity to tension increase with a non-invasive method. Cell-sized liposome doublets are covered with either a stabilized actin cortex of preformed actin filaments, or a dynamic branched actin network polymerizing at the membrane. The addition of myosin II minifilaments in both cases triggers a change in doublet shape that is unambiguously related to a tension increase. Preformed actin filaments allow us to evaluate the effect of myosin alone while, with dynamic actin cortices, we examine the synergy of actin polymerization and myosin motors in driving shape changes. Our assay paves the way for a quantification of tension changes triggered by various actin-associated proteins in a cell-sized system.

Reference gene selection for real-time quantitative polymerase chain reaction normalization in "Swingle" citrumelo under drought stress

We describe the first systematic evaluation of reference genes for use in real-time quantitative polymerase chain reaction (qPCR) for water deficit stress studies in the citrus rootstock "Swingle" citrumelo. The expression levels of seven reference genes-cyclophilin (CYP), cathepsin (CtP), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), elongation factor 1alpha (EF1alpha), beta-tubulin (TUB), and ADP ribosylation factor (ADP)-during drought stress were tested using geNorm and NormFinder programs. Results from four experimental conditions indicated that EF1alpha and ADP were the most stable reference genes. Relative expression levels of Delta1-pyrroline-5-carboxylate synthetase (P5CS) was used for reference gene validation.

Using Virtual Reality to Study Alcohol Intoxication Effects on the Neural Correlates of Simulated Driving

The use of virtual reality in the form of simulated tasks can provide a realistic environment in which to study complex naturalistic behaviors. Many of the behavioral effects of alcohol intoxication are well known, but there is relatively little imaging evidence examining how alcohol exposure might transiently modulate brain function, especially in the context of task performance. In this review, we provide a brief synopsis of previous work using functional magnetic resonance imaging (fMRI) to study the neural correlates of alcohol intoxication. We describe in detail two studies from our published work, the first involving a visual perception paradigm, and the second involving virtual reality through a naturalistic behavior; simulated driving. Participants received single-blind individualized doses of beverage alcohol designed to produce blood alcohol content (BAC) of 0.04 and 0.08 or placebo. Subjects were fMRI scanned after training to asymptote performance. In both studies we found specific circuits that were differentially modulated by alcohol, we revealed both global and local effects of alcohol, and we examined relationships between behavior, brain function, and alcohol blood levels.

Lymphatic filariasis in children: adenopathy and its evolution in two young girls

Lymphatic filariasis is a widespread infectious disease of children in endemic areas, but little is known about the early lymphatic damage in children and its evolution, either with or without treatment. Two girls (ages 6 and 12 years) from a Wuchereria bancrofti endemic region of Brazil presented with chronic inguinal adenopathy. Neither had microfilaremia. By ultrasound both were shown to have living adult worms in their enlarged inguinal nodes and had occult local lymphatic damage (lymphangiectasis). One girl spontaneously developed acute adenitis in the affected node prior to any intervention; this adenitis resolved within 10 days and was associated with the progressive disappearance over 45-90 days of all local abnormalities detectable by ultrasound. In the other child, after treatment with a single dose of diethylcarbamazine (DEC), the same clinical picture of transient adenitis and resolving abnormalities (detectable by ultrasound) occurred. These findings demonstrated filariasis as the cause of adenopathy in children, and also both spontaneous and treatment-induced worm-death, with subsequent reversal of lymphatic abnormalities.