Avian and Mammalian mitochondrial ammonia-detoxifying systems in tortoise liver

Liver mitochondria from the desert tortoise Gopherus agassizii and the Texas tortoise G. berlandieri contain glutamine synthetase, the enzyme used by birds and higher reptiles to detoxify ammonia generated intramitochondrially during amino acid catabolism. Tortoise mitochondria also contain carbamyl phosphate synthetase-I and ornithine transcarbamylase, the enzymes used by mammals for this purpose. Since chelonid reptiles have changed little since their divergence from the stem reptiles, this finding suggests that both systems were present in the latter before the emergence of the ruling reptile, avian, and mammalian lines of descent.     

A SYSTEM OF "DEFINITIVE UNITS" PROPOSED FOR UNIVERSAL USE

It is proposed that physicists discard the CGS and Heaviside units, which are responsible for much confusion and needless mental effort, and employ exclusively a single system of "definitive units." The units suggested include the international meter, the international kilogram, the second, the mechanical watt, the international mercury ohm and they conform with the other international units as closely as is compatible with self-consistency. The system is not only definite and absolute, but also comprehensive, readily visualized and, in large part, already employed under well-established names. The system was proposed in 1901 by Giorgi and in 1904 by Robertson but received scant attention on account of the artificial prestige of the CGS system. A single universal system of units should be the ultimate goal, and the "definitive units" are chosen with a view to their adoption not only by all scientists but also by the butcher, the baker and the candlestick-maker. The definitive system of units makes it perfectly feasible to employ a single system much more generally than has ever been the case in the past; the natural ultimate goal is the universal use of these units for all purposes. In the attempt to extend the application of metric units in the United States the meter-stere-kilogram, rather than the meter-liter-gram, should form the basis for legislation, in order to give definitive units their proper legalized status and to secure to the full the advantages of a comprehensive system consistently interrelated with the legalized international electrical units. The gradual discarding of CGS and other redundant units would inevitably follow. Even in the absence of official recognition of definitive units, individuals may advantageously employ the system. This would cause confusion neither to authors nor readers, since these units, in the main, have already acquired vital existence through world-wide, daily use under familiar, well-established names.