Employing Dictyostelium as an Advantageous 3Rs Model for Pharmacogenetic Research.

Increasing concern regarding the use of animals in research has triggered a growing need for non-animal research models in a range of fields. The development of 3Rs (replacement, refinement, and reduction) approaches in research, to reduce the reliance on the use of animal tissue and whole-animal experiments, has recently included the use of Dictyostelium. In addition to not feeling pain and thus being relatively free of ethical constraints, Dictyostelium provides a range of distinct methodological advantages for researchers that has led to a number of breakthroughs.

How blebs and pseudopods cooperate during chemotaxis.

Two motors can drive extension of the leading edge of motile cells: actin polymerization and myosin-driven contraction of the cortex, producing fluid pressure and the formation of blebs. Dictyostelium cells can move with both blebs and actin-driven pseudopods at the same time, and blebs, like pseudopods, can be orientated by chemotactic gradients. Here we ask how bleb sites are selected and how the two forms of projection cooperate.

Bleb-driven chemotaxis of Dictyostelium cells.

Blebs and F-actin-driven pseudopods are alternative ways of extending the leading edge of migrating cells. We show that Dictyostelium cells switch from using predominantly pseudopods to blebs when migrating under agarose overlays of increasing stiffness. Blebs expand faster than pseudopods leaving behind F-actin scars, but are less persistent.

A novel human receptor involved in bitter tastant detection identified using Dictyostelium discoideum.

Detection of substances tasting bitter to humans occurs in diverse organisms including the social amoeba Dictyostelium discoideum. To establish a molecular mechanism for bitter tastant detection in Dictyostelium, we screened a mutant library for resistance to a commonly used bitter standard, phenylthiourea. This approach identified a G-protein-coupled receptor mutant, grlJ(-), which showed a significantly increased tolerance to phenylthiourea in growth, survival and movement.

The distribution of Dishevelled in convergently extending mesoderm.

Convergent extension (CE) is a conserved morphogenetic movement that drives axial lengthening of the primary body axis and depends on the planar cell polarity (PCP) pathway. In Drosophila epithelia, a polarised subcellular accumulation of PCP core components, such as Dishevelled (Dvl) protein, is associated with PCP function. Dvl has long been thought to accumulate in the mediolateral protrusions in Xenopus chordamesoderm cells undergoing CE.

Quantitative analysis of human ras localization and function in the fission yeast Schizosaccharomyces pombe.

Ras signalling is central to fundamental and diverse cellular processes. In higher eukaryotes ras signalling is highly complex, involving multiple isoforms, regulatory proteins and effectors. As a consequence, the study of ras activity in mammalian systems presents a number of technical challenges.

Presence of electroencephalogram burst suppression in sedated, critically ill patients is associated with increased mortality.

Objectives: This study investigates the possibility of a relationship between oversedation and mortality in mechanically ventilated patients. The presence of burst suppression, a pattern of severely decreased brain wave activity on the electroencephalogram, may be unintentionally induced by heavy doses of sedatives. Burst suppression has never been studied as a potential risk factor for death in patients without a known neurologic disorder or injury.