Nanoparticles Associate with Intrinsically Disordered RNA-Binding Proteins.

Nanoparticles are capable of penetrating cells, but little is known about the way they interact with intracellular proteome. Here we show that inorganic nanoparticles associate with low-complexity, intrinsically disordered proteins from HeLa cytosolic protein extracts in nondenaturing in vitro nanoparticle pull-down assays. Intrinsic protein disorder associates with structural mobility, suggesting that side-chain flexibility plays an important role in the driving of a protein to nanoparticle absorption. Disordered protein domains are often found in a diverse group of RNA-binding proteins. Consequently, the nanoparticle-associated proteomes were enriched in subunits of RNA-processing protein complexes. In turn, this indicates that within a cell, nanoparticles might interfere with protein synthesis triggering a range of cellular responses.

Wintertime loss of ultradian and circadian rhythms of body temperature in the subterranean euthermic mole vole, ellobius talpinus.

Subterranean common mole voles, Ellobius talpinus, were implanted with long-term recording electronic thermometers to obtain hourly body temperature (T(b)) data during either the wintertime or summertime. The two individuals tested during the summertime had significant circadian and ultradian rhythms in their T(b). Four of the five mole voles tested during the wintertime lacked rhythmicity in their T(b). The fifth individual lacked circadian rhythms but had ultradian rhythms in its T(b). A loss of circadian rhythms in T(b) during deep torpor or hibernation has been reported for a few species of mammals. Inasmuch as the mole voles' wintertime T(b) remained at euthermic levels, our results show that a loss of circadian body temperature rhythms in mole voles does not require the low T(b) of deep torpor or hibernation. A tentative conclusion, based on these few animals, is that in common mole voles the T(b) rhythms may disappear during the wintertime even though their T(b) remains high.