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4 posts tagged with bacteria by Blasdelb.
Displaying 1 through 4 of 4.

Protein Packing

Harvard University and XVIVO have come together again (Previouslyw/ a commercial focus, Previouslierw/an Academic focus) to add to the growing series of scientific animations for BioVisions -- Harvard's multimedia lab in the department of Molecular and Cellular Biology. 'Protein Packing' strives to more accurately depict the molecular chaos in each and every cell, with proteins jittering around in what may seem like random motion. Proteins occupy roughly 40% of the cytoplasm, creating an environment that risks unintentional interaction and aggregation. Via diffusion and motor protein transport, these molecules are directed to sites where they are needed.
Much of this is no doubt inspired by the beautiful art and explained illustrations of David Goodsell, a biologist at Scripps who has been accurately portraying the crowdedness of the cellular landscape for a long time now.
[more inside]
posted by Blasdelb on Apr 10, 2014 - 9 comments

As Paracelsus put it, "the dose makes the poison."

Dr Bruce Ames, a toxicologist and one of the world's most cited scientists, discusses the impact of his Ames test, "toxic chemicals," and scaremongering [more inside]
posted by Blasdelb on Nov 6, 2013 - 22 comments

The players in a mutualistic symbiosis: insects, bacteria, viruses, and virulence genes.

One of the many problems farmers of various kinds of legumes need to deal with is the pea aphid. They reproduce incredibly fast and live by sucking the sap out of the plants, an electron micrograph of one in action. However, while they are terrifying parasites of legumes, they have their own yet more horrific parasites, a parasitoid wasp. Here is a really nice close up picture of one doing its thing, a video of the act, and here is a brain meltingly horrific video of a dissection of the mummified aftermath 8 days later. Essentially, these wasps deposit their eggs in a pea aphid and the growing larva feeds on it, developing there for about a week, and then consuming the host from the inside out like a Xenomorph. When it’s done, the wasp larva dries the aphid’s cuticle into a papery brittle shell and an adult wasp emerges from the aphid mummy. Legume farmers love them, and you can even order their mummies online these days. However, farmers noticed that the wasps didn't work as effectively on all of the aphids, and so researchers went to work figuring out why. It turns out that all aphids have a primary bacterial endosymbiont living inside their cells, in addition to and just like a mitochondria, and that many have some combination of five other secondary endosymbionts. Interestingly, two of those other five, Hamiltonella defensa and Serratia symbiotica have been shown to confer varying levels of resistance to the parasitoid wasp, allowing the aphid to survive infection. However, it turns out that there is yet one more layer to this story, [more inside]
posted by Blasdelb on Oct 22, 2012 - 50 comments

Constitutive formation of caveolae in a bacterium.

Constitutive formation of caveolae in a bacterium. [Full Text]
Caveolin plays an essential role in the formation of characteristic surface pits, caveolae, which cover the surface of many animal cells. The fundamental principles of caveola formation are only slowly emerging. Here we show that caveolin expression in a prokaryotic host lacking any intracellular membrane system drives the formation of cytoplasmic vesicles containing polymeric caveolin. Vesicle formation is induced by expression of wild-type caveolins, but not caveolin mutants defective in caveola formation in mammalian systems. In addition, cryoelectron tomography shows that the induced membrane domains are equivalent in size and caveolin density to native caveolae and reveals a possible polyhedral arrangement of caveolin oligomers. The caveolin-induced vesicles or heterologous caveolae (h-caveolae) form by budding in from the cytoplasmic membrane, generating a membrane domain with distinct lipid composition. Periplasmic solutes are encapsulated in the budding h-caveola, and purified h-caveolae can be tailored to be targeted to specific cells of interest.
Elio Schaechter writes in plain English about how fantastically amazing and unexpected the researchers actually pulling this off is, and he also talks about it in more detail in his podcast.
posted by Blasdelb on Oct 18, 2012 - 22 comments

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