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Cool Cell Tricks

Cells do the neatest tricks. If they were as big as pets, people would be showing them off on YouTube.

Consider:

Magic repulsion: How do cells keep from sticking to each other? Their secret is to use water as a force field. Lipid membranes surrounding cells and their organelles arrange their molecules in such a way that water molecules cling to them in a particular orientation, generating an electrical field. When another organelle gets too close, the water molecules gently push them apart. (Technical University at Munich)

Jackhammer zipper: Just like a jackhammer opens up concrete, a "nano-piston" opens up double-stranded RNA molecules. Helicases called DEAD-box proteins, found in all domains of life, clamp onto the RNA strands and drive them apart using a piston-like action as a wedge. One side grabs ATP for fuel; the other clamps onto the RNA. Then "the 'piston' comes down. It has a sharp edge that drives between the two strands and also grabs on one strand and bends it out of the way." (University of Texas at Austin)

"If you want to couple fuel energy to mechanical work to drive strand separation, this is a very versatile mechanism."
Geodesic architect is a multitasker: Clathrin is a cool-looking protein with three equally-spaced crooked arms (picture). Scientists have long known that clathrin proteins join together in elaborate spherical cages (picture) that transport cargo safely inside membranes. Now, this "well known cell protein reveals new tricks," a press release from University of California at San Francisco states. They found that clathrin also stabilizes centrosomes and the mitotic spindle - vital structures involved in cell division.

Security guards: This one might be called, "MINOS meets SAM and TOM." These are the names of membrane cops that control what goes in through the double membranes surrounding mitochondria. A press release from the University of Freiburg told about "Molecular Switches in the Cellular Power Plants." MINOS is the acronym for a new protein they found, named "Mitochondrial Inner Membrane Organizing System." It works with SAM and TOM (the outer membrane guards) to bring in the components needed to build the energy factory, "essential for the survival of the cells."

"These findings show how molecular switches affecting the connectivity of mitochondrial membranes control the assembly and function of the cellular power plants."
Marching in formation: Do you like watching a marching band scatter and form into recognizable patterns? Then you'll like Figure 1 in an open-access PNAS paper about cytoplasmic streaming -- a process involved in transforming a spherical zygote into an asymmetric embryo. Cytoplasmic streaming is a collective motion made by thousands of molecular robots called kinesins, marching on filaments (microtubules) in formation. The authors said, "we suggest that the disordered character of transport at mid-oogenesis, as revealed by streaming, is an important component of the localization dynamics of the body plan determinant."

And that's it for this episode of Cool Cell Tricks. More contestants keep lining up at the door, as scientists continue to probe the secrets of living cells. Are you surprised that Darwin got the cold shoulder in all these articles? In their fascination at the design of life, the scientists and reporters unintentionally insulted the old guy by ignoring him and his pet theory completely.