The Independence of Homarine from the Osmoregulatory Mechanisms in the Ventral Nerve Cord of Limulus Polyphemus L

摘要

Homarine (1-methyl-2-pyridinecarboxylic acid) contributes to a mean of about 17.1% to the total osmotic pressure in Limulus ventral nerve cord. Cryoscopic measurements show that Limulus living at salinities from 14.3 to 33.5% are slightly hyperosmotic to the environment but lack of correlation between homarine concentration in the cord and environmental salinity indicates that the compound is not regulated to maintain this hyperosmoticity. In addition, homarine varies neither with size of animal nor duration of acclimation to salinity. Chromatographic separation of the components of deproteinized nerve cord extracts reveals homarine as the major absorber of 275 mu radiation; two additional compounds absorbing at this wavelength have been discovered but remain unidentified. (Author)