that of collagen, and since the hydroxyproline content of elastin is only 

 about one-tenth that of collagen, its contribution to the total hydroxy- 

 prolin content is negligible (Green eXal. t 1968). The synthesis of colla- 

 gen, like that of other proteins, occurs on the ribosomes in fibroblasts, 

 osteoblasts, and chondroblasts. However, hydroxyproline and hydroxylysine 

 in the collagen molecule are not derived from incorporation of the free 

 amino acid into the polypeptide, but instead are derived from the hydroxy- 

 lation of their respective precursors, proline and lysine, after incorpor- 

 ation of proline and lysine into the polypeptide protocol 1 agen. The en- 

 zyme collagen hydroxylase, or peptidyl proline hydroxylase, which begins 

 its activity during gastrulation, catalyzes hydroxylation; vitamin C, 

 a-ketoglutarate, and ferrous ion serve as cofactors for the enzyme 

 (Mussini oX at., 1967). 



The importance of collagen in animals in shown by its wide distribution 

 and many functions during growth and development. One of its major func- 

 tions is to serve as the structural support for bones. Dried bone consists 

 of one-third organic matrix and two-thirds minerals. About 90 percent of 

 the organic matrix is collagen, and the rest consists of mucopolysaccha- 

 rides, mucoproteins, and lipids (Nusagens dtat., 1972). Calcification 

 and mineralization take place around and within the collagen fibrils in 

 bone and, as development proceeds, the deposition of calcium and phosphate 

 produces mature bone. 



The use of collagen as a representative "differentiated" protein in 

 the study of embryonic development has been reported in amphibian embryo- 

 logical investigations (Green &£al., 1968; Rollins and Flickner 1972). 

 Collagen synthesis, though repressed during the first cleavage stages of 

 the embryo of a frog [XcnopuA laavu), begins during gastrulation and in- 

 creases 500-fold through neutrulation, hatching, and posthatching stages. 

 Also, decreased hydroxyproline excretion in urine has shown promise as a 

 detector of nutritional deficiency and reduced growth rates in humans 

 (Whitehead and Coward, 1969). Fish continue to grow throughout life, and 

 their vertebrae continue to elongate and enlarge with growth. It has 

 therefore hypothesized that backbone development should increase in pro- 

 portion to increase in growth, and that increases in collagen and hydro- 

 xyproline would be indicators of this growth. 



RELATION OF COLLAGEN AND HYDROXYPROLINE TO GROWTH 



Brook trout {Salvo.JU.nai, iontlnaLU) , fathead minnows [Vumpkalu* 

 pfiomzla.6 ) , and channel catfish {IctaCuuu punctata*) were continuously ex- 

 posed to toxaphene in water; the proportional diluter systems used were 

 modeled after Mount and Brungs (1967) and modified as recommended by 

 McAllister zt aJL, (1972). The diluter systems delivered five concentra- 

 tions of toxaphene, with a dilution factor of 0.5 between the concentra- 

 tions, and a control (Table 1). We used flow-splitting chambers as 

 designed by Benoit and Puglisi (1973) to thoroughly mix and divide each 

 toxaphene concentration for delivery to duplicate exposure tanks. Artifi- 

 cial daylight was provided by the method of Drummond and Dawson (1970), 

 and water temperatures were maintained within + 0.2 °C. 



93 



