Pergamon 0300-9629(95)02017-E zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Camp. B&hem. Physiol. Vol. lIZA, Nos. 314, pp. 487- 494, 1995 Copyright 0 1995 Elsevier Science Inc. Printed in Great Britain. All rights reserved 0300-%29/95 $9.50 + .OO Ultrastructural cytology of maturing erythroid cells in a fossorial reptile (Amphisbaena alba) with reference to hemoglobin biosynthesis C. Jared,* M. M. Antoniazzi,” I. S. Sano-Martins? and A. Brunner, Jr.* *Laboratory of Cellular Biology and tLaboratory of Pathophysiology, Instituto Butantan, Sao Paulo, SP, Brasil Ultrastructural changes of organelles involved in hemoglobin (Hb) biosynthesis were studied in immature peripheral erythrocytes of zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Amphisbuena dba (Amphisbaenia: Reptilia). Iron uptake (probably via transferrin) and accumulation results in formation of siderosomes, which serve as an iron source for heme biosynthesis. Differentiation of the mitochondrial inner zyxwvutsrqponmlkjihgfedcbaZYXW chamber results in a lamellated body, which then produces a lateral expansion; this expansion retains ferrugiuous compounds and globin polypeptides and, later, folds upon itself to form a prehemosomal vesicle. Vesicle content condenses, and iron in an amorphous state associates with the partially coiled vesicle membrane. Invagination of the membrane gives rise to a prohemosome; narrowing of the broad intralamellar spaces and reduction of overall diameter results in formation of a hemosome. Stages of hemosomegenesis in maturing erythroid cells of Amphisbuena alba are similar to those in other vertebrate groups; the significant difference is the periodical and temporary transverse alignment of Hb molecules in the organelle matrix of some of the hemosomes. Electrophoresis reveals a similar light Hb migration rate pattern in both organellar and cytoplasmic fractions; the cytoplasmic fraction also shows a heavy Hb pattern with a lower migration rate. Key words: Reptiles; Amphisbaenia; Amphisbaena afba; Erythroid cells; Hemoglobin synthesis; Hemosome; Hemosome formation; Organellar hemoglobin; Erythroid cell maturation. Comp. Biochem. Physiol. 112A, 487- 494, 1995. Introduction The hemoglobin (Hb) molecule is made up of a heme prosthetic group and (Yand j3 globin (G) polypeptides. Three structural sites are probably involved in molecule biosynthesis and in the process whereby erythroid cells mature to become erythrocytes. Heme pros- thetic group synthesis occurs in the mitochon- Correspondence to: Dr. A. Brunner Jr., Lab. of Cellular Biology, Instituto Butantan, Av. Vital Brazil, 1500, CEP 05503-900, S&o Paulo, SP, Brasil. Received 24 October 1994; revised 24 February and 23 May 1995; accepted 8 June 1995. dria and depends on the activity of a mito- chondrial enzyme system (Rimington, 1957; Granick and Levere, 1965). The CY and p G polypeptides are synthesized at the erythroid cell polysomes (Warner et al., 1962; Gierer, 1963). The integration of heme into the G polypeptides and the formation of the tetra- mer Hb molecule (c&) may take place in a mitochondrion-derived and Hb-containing or- ganelle, the hemosome (Brunner ef al., 1972). This hypothesis is supported by studies that show a close and constant relationship be- tween Hb biosynthesis and hemosome forma- 487