The moose, purine degradation, and environmental adaptation

Abstract

It is accepted that allantoin is the end-product of purine degradation in mammals, except that uricase activity has been lost during the evolution of humans in which uric acid protects the brain from oxidative damage. However, we have found that the moose Alces americanus excretes extremely low urinary concentrations of allantoin and high concentrations of uric acid very similar to those of humans. Exposure to extreme cold is known to cause oxidative damage, and we suggest that the retention of uric acid by the moose represents an adaptation enabling the species to survive at high latitudes.

Pyrolysis versus hydrolysis behavior during steam decomposition of polyesters using18O-labeled steam

“…Scheme 1 Identification of (a) pyrolysis and (b) hydrolysis products in the 18 O-labeled steam decomposition of PET. 36 We conrmed that neither TPA nor NDC decomposed under the reaction conditions.…”

“…The ester bonds in polyester chains are well known to be cleaved by pyrolysis and hydrolysis. Both reactions enable the depolymerization of high-molecular-weight polyesters into monomers; thus, are commonly applied for the feedstock recycling of waste polyesters such as polyethylene terephthalate (PET), [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] polybutylene terephthalate (PBT), 8,[20][21][22] and polyethylene 2,6naphthalate (PEN). 13,14,22,23 On the other hand, pyrolysis is an attractive method because it only requires heat.…”

“…Thus, the manner in which pyrolysis affects hydrolysis still remains unclear, and vice versa. Hence, we developed a novel approach for quantifying the selectivities for pyrolysis and hydrolysis during the steam decomposition of PET using 18 O-labeled steam (Scheme 1). 36 Selectivity is calculated from the ratio of labeled and unlabeled TPA determined by gas chromatographymass spectroscopy (GC-MS).…”

“…In addition, by the comparison of the three polyesters, the inuence of the polymer structure on the pyrolysis and hydrolysis selectivities for each transformation was claried during steam decomposition. For this purpose, the inuence of steam concentration and decomposition temperature on the pyrolysis and hydrolysis selectivities in PET, PBT, and PEN was investigated using 18 O-labeled steam. In addition, kinetic analyses of the steam decomposition of these polyesters were conducted by model-tting techniques using a thermogravimetric analyzer.…”

“…In addition, kinetic analyses of the steam decomposition of these polyesters were conducted by model-tting techniques using a thermogravimetric analyzer. The results obtained from the 18 O-labeling tests and kinetic analyses were compared for consistency. Our previously published letter briey describes some of the results for PET.…”