Effects of starvation on iron concentration and deposition in tissues of larval lampreys, Petromyzon marinus L.: morphological and quantitative analyses

Abstract

Light and electron microscopy, inductively coupled plasma atomic emission spectroscopy, and a biochemical assay were used to compare tissue distribution and concentration of iron in larval lampreys (Petromyzon marinus) under conditions of long-term starvation and feeding in the laboratory and in recently captured individuals. There were higher values for serum iron, red blood cell numbers, and haemoglobin in nonfeeding animals compared with the field-sample individuals. Iron concentration was similar in most tissues and organs of the two laboratory-held groups and significantly higher than in similar samples of recently captured individuals. This difference was due to heavy deposition of ferric iron in primary sites of adipose tissue and, to a lesser degree, to deposits of this metal in the liver. Electron microscopy of hepatocytes of starved animals showed both ferric and ferrous iron in dense bodies, ferric iron in the cytoplasmic matrix, an increased role for the cells in carbohydrate metabolism, and some signs of bile stasis. Extended laboratory holding of larvae in both presumed fed and nonfed conditions results in alteration in blood and tissue concentrations of iron that are more likely a result of alterations in metabolism and excretion than a result of uptake of the metal from the environment.