title: A cryptobiosis-specific 19S protein complex of Artemia salina gastrulae.
abstract: The postribosomal supernatant of Artemia salina cryptobiotic embryos contains a large quantity of a 19S protein complex. An amount of 3.6 mg/g of cysts is measured by immunoprecipitation with anti-(19S protein complex) antibody. The quantity of this complex decreases during further development to nauplius larvae to only 15% of the quantity present in cryptobiotic embryos. The complex was no longer detectable after 7 days of growth. The 27000-Mr protein subunit of the 19S complex is not synthesized by mRNA isolated from cryptobiotic embryos. The cryptobiosis-specific complex has Mr 573000 and 610000 as calculated from light-scattering and sedimentation-diffusion measurements respectively. The 19S homocomplex contains 20-23 27000-Mr proteins and has no function in the translation of homologous mRNA. From hydrodynamic data a hydration of 1.25 g of water/g of protein is calculated. The abundant presence of the 19S protein complex in cryptobiotic embryos and the absence of synthesis during development to nauplius larvae indicate a functional role during the cryptobiotic process in early embryogenesis. A role in maintaining the water content of the cytoplasm above a critical threshold during desiccation is suggested.
mesh_terms: D000818:Animals; D001156:Artemia / Q000196:embryology*; D004058:Diffusion; D005775:Gastrula / Q000378:metabolism*; D008970:Molecular Weight; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D013053:Spectrophotometry; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D011506:Proteins; D012333:RNA, Messenger