ID Number		1797
Study Type		In Vitro
Model		Small Temperature Effects in Vitro (catch all)
Details		Small Temperature Effects in Vitro (catch all). In studies by Sisken et al: Human amnion cells were exposed to non-RF heating and followed through the cell cycle. The authors report delays in cell cycle progression when cells were cultured at temperatures other than the optimum temperature. These changes occurred immediately after temperature shifts and the new rate of progression was maintained throughout the duration of the experiment. The duration of metaphase did not increase more than the initial prolongation during culturing at 40ºC. Baffou et al. 2014: "The preceding derivations cast doubt on the validity of endogenous thermogenesis studies reporting temperature rises of a few Kelvins at the single-cell level. The natural concern is now to decipher what could be the origin of the signal in these measurements. As further experiments would be required to definitively ascertain the origin of these signals, here we only make some speculative suggestions. Some reported techniques may simply suffer from too large a standard deviation. For instance, some authors measure an average temperature increase of 1.84 K among 31 cells after a Ca2+ shock, while the standard deviation is 2.9 K (ref. 10), with 23% of the cells showing an apparent temperature decrease after the shock. Such large standard deviations suggest that factors other than temperature affect the signal. Without identifying these factors, it is unwise to attribute the signal variation solely to temperature variation. Fluorescence properties such as the fluorescence spectrum or fluorescence lifetime are indeed known to depend on many parameters. In particular, fluorescence lifetime is dependent on the microenvironment of the fluorophores, such as the microviscosity, pH or ion concentrations. Whereas most authors do assess these effects to some extent in test tubes, any such observations must be tempered by the fact that the interior of a living cell is more complex. For instance, the optical properties of genetically encoded fluorescent thermosensors (17) are dependent on the folding and unfolding of an a-helical coiled-coil protein, which will be governed by many more constraints in the cytosolic compartment of a cell. To conclude, thermal imaging techniques that have been reported in the literature may indeed be temperature-sensitive, but they certainly do not report only on temperature changes when used in a system as complex as the interior of a living cell." (p. 901)
Findings
Status		Completed With Publication
Principal Investigator
Funding Agency		?????
Country		UNITED STATES
References		Lacetera, N et al. J Dairy Sci, (2006) 89:4606-4612 Sisken, JE et al. Exp Cell Res, (1965) 39:103-116 Sisken, JE Exp Cell Res, (1965) 40:436-438 Purrott, RJ et al. Experientia, (1981) 37:407-408 Takashima, Y et al. Exp Cell Res, (1965) 39:103-116 Shimoda, T et al. Nippon Sanka Fujinka Gakkai Zasshi, (1983) 35:183-188 Saito, M et al. In Vitro Cell Dev Biol., (1990) 26:181-186 Flour, MP et al. Biol Cell., (1992) 75:83-87 Baffou, G et al. Nature Methods. , (2014) 11:899-901
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