Characterization of yolk proteins during oocyte development of tilapia, Oreochromis mossambicus

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Comparisons of yolk proteins in tilapia, Oreochromis mossambicus, during oocyte development indicate differences between early and late vitellogenic stages. Changes during oocyte development were observed in the abundance of yolk proteins and in the immunoreactivity to VTG-200 and VTG-130 antibodies. Some of these yolk proteins were observed at early viteliogenic stages, 145, 48, 44, 42, 32, 32, 30, 11.7, and 11.5 kDa; others were observed at late vitellogenic stages, 87 and 64 kDa; whereas some were observed at both vitellogenic stages, 116, 105, 78, 22, 36, 25.5, 18, 16.5, 14, 13.8, and 12 kDa. Immunological analysis and staining with Coomassie Brilliant Blue indicate that VTG-130 appears intact in the oocytes only at early stages. Intact VTG-200 is present in both early and late oocyte developmental stages. Crossreaction of the two different antibodies with smaller molecular mass proteins from the oocytes suggests that they are proteolytic cleavage products of the vitellogenins. Phosvitins such as 21, 17, 13.5, and 8 kDa and lipovitellins measuring 116, 105, 18, 16.5, and 14 kDa were observed throughout oocyte development. Several yolk proteins, including 105, 87, 78, 14, and 13.8 kDa, crossreacted with wheat germ agglutinin and concanavalin A lectins, suggesting that these contain N-acetylglucosamine and glucose and/ or mannose. © 1995.

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Comparative Biochemistry and Physiology -- Part B: Biochemistry and