“In its natural environment, Drosophila melanogaster feeds on yeasts that grow on sugar-rich substrates such as fermenting fruit. Fruits, however, also harbor toxic microbes, and flies need to distinguish those microbes that are safe and nutritious from the harmful ones. In this issue, Stensmyr et al. (pp. 1345–1357) demonstrate that flies detect toxic molds by sensing a volatile compound called geosmin, which exclusively triggers a dedicated signaling pathway in the flies’ olfactory system. This circuit, upon activation, causes innate aversion and also prevents egg laying and feeding. Cover concept by Rakel and Marcus Stensmyr. Clay modeling and photo by Marcus Stensmyr.”
“Microscopic phytoplankton floating in the upper layers of the ocean use the sun’s energy to photosynthesize carbohydrates. These carbohydrates can be eaten for energy, and these plants - mostly diatoms and algae - are the foundation of the majority of the ocean’s biological community. In areas of the ocean where there is not light, some producers can even create energy by using the process of chemosynthesis instead of photosynthesis.”
Cell movement begins with lamellipodia. A thin sheet of actin filaments (light purple) that stretches out to the cell’s periphery, lamellipodia generate pushing forces that drive the cell forward. Microtubules (cyan) can barely penetrate this actin network, but they direct cell motility in other ways, such as controlling cell adhesion and acting as the cell’s internal compass.
Image: A human HaCat keratinocyte responds to epidermal growth factor by rapidly forming a lamellipod around most of its perimeter. The cell was fixed and processed within minutes after EGF addition. F-actin is stained with fluorescently labeled phalloidin (light purple), and microtubules are labeled with an antibody (cyan). DNA dye stains the nucleus dark purple.
Why are the faces of primates so dramatically different from one another? A very interesting study that examines the differences in faces amongst New World primates.
Humans have pretty bare faces, which may allow us to see facial expressions more easily than if, for example, we had many colors in our faces.
This finding suggests that facial expressions are increasingly important in large groups. If you’re highly social, then facial expressions matter more than having a highly complex pattern on your face.