title: Analysis of the membrane-associated poly(A)+RNA in the cytoplasm of dormant Artemia cysts by DNA excess hybridization. Evidence for a nuclear origin.
abstract: Encysted embryos of Artemia contain latent mRNA, to a large extent associated with a fraction of cytoplasmic membranes. The membranes, purified by EDTA treatment and banding in a sucrose gradient at 1.17 g/cm3, include endoplasmic vesicles and mitochondria. The origin of the membrane-associated poly(A)+RNA was therefore investigated. In gel electrophoresis poly(A)+RNA from the purified membranes of dormant cysts forms two distinct bands at approx. 3 . 10(5) and 5 . 10(5) Da. Later during development the lighter component decreases. Nuclei from dormant cysts are devoid of poly(A)+RNA, while nuclei from developing embryos (50% emergence) contain a predominant poly(A)+RNA component of approx. 5 . 10(5) Da. 125I-labelled preparations of nuclear DNA and of nuclear and membrane-associated poly(A)+RNA were used in reassociation and hybridization experiments with excess nuclear DNA. Poly(A)+RNA from the membranes of dormant cysts hybridized to nuclear DNA to the same extent as the nuclear poly(A)+RNA from developing embryos. The hybridization of labelled, nuclear poly(A)+RNA to nuclear DNA was strongly inhibited by unlabelled membrane RNA from either dormant cysts or developing embryos. It is concluded that the stored, membrane-associated poly(A)+RNA in dormant cysts is essentially of nuclear origin. The 5 . 10(5)-Da component is largely homologous with the corresponding component of nuclear poly(A)+RNA at later stages.
mesh_terms: D000818:Animals; D001156:Artemia / Q000032:analysis*; D002462:Cell Membrane / Q000032:analysis; D002467:Cell Nucleus / Q000032:analysis*; D004625:Embryo, Nonmammalian / Q000032:analysis; D007700:Kinetics; D009693:Nucleic Acid Hybridization; D009695:Nucleic Acid Renaturation; D011061:Poly A / Q000032:analysis*; D012313:RNA / Q000032:analysis*; D012333:RNA, Messenger / Q000032:analysis
chemical_list: D012333:RNA, Messenger; D011061:Poly A; D012313:RNA