Changes in the nucleic acid and protein composition of the nasal glands from the duck (Anas platyrhynchos) during the period of adaptation to hypertonic saline.

The early observations of Heinroth & Heinroth (1927) established that the nasal glands in the marine eider duck (Somateria mollisima) were reduced in size when the birds were given fresh water. These experiments were later confirmed in the domestic duck and the glaucous-winged gull, LOTUS glaucescens, (Schildmacher, 1932; Holmes, Butler & Phillips, 1961; Holmes, Phillips & Chester Jones, 1963). The physiological significance of the earlier observations, however, was not realized until 1958 when Schmidt-Nielsen, Jorgensen and Osaki described the presence of an extra-renal excretory pathway associated with the nasal glands in marine birds. The glands were shown to excrete a fluid which contained sodium, potassium and chloride at higher concentrations than those found in sea water. Clearly, in the absence of an adequate renal concentrating mechanism, this excretory pathway would enable the birds to gain osmotically free water and at the same time excrete the excess salt. The nasal glands of the freshwater-maintained duck are inactive but the excretory mechanism may be initiated within a few minutes after the administration of hypertonic saline (Scothorne, 1958; Holmes, Phillips & Butler, 1961). If the birds are maintained on a diet of hypertonic saline or sea water then the excretory capacity of the nasal glands is enhanced (Fletcher, Stainer & Holmes, 1967) and simultaneously certain structural and enzymic changes occur in the nasal gland tissue (Ellis, Goertemiller, DeLellis & Kablotsky, 1963; Holmes et al. 1963; Fletcher et at. 1967). The recent studies on nucleic acids have begun to elucidate their role in the control of protein synthesis. The changes known to occur in the developing nasal gland would seem to implicate the nucleic acids in the control mechanisms associated with the development of the gland and its associated active sodium-transport system. The purpose of the present investigation, therefore, was to determine the nature of the gross changes occurring in the protein and nucleic acid composition of the nasal glands during the period of adaptation to a hypertonic saline diet.