The association of Xenopus nuclear factor 7 with subcellular structures is dependent upon phosphorylation and specific domains.

The function of proteins is often regulated by their association with specific subcellular structures. Xenopus nuclear factor 7 (xnf7) is a putative transcription factor that is selectively retained in the cytoplasm from fertilization through the mid blastula transition (MBT). Cytoplasmic retention is dependent upon the presence of a 22-amino-acid cytoplasmic retention domain and the phosphorylation of two sites (site 1 and site 2) within the protein.

Cytoplasmic retention of Xenopus nuclear factor 7 before the mid blastula transition uses a unique anchoring mechanism involving a retention domain and several phosphorylation sites.

Xenopus nuclear factor 7 (xnf7) is a maternally expressed protein that belongs to the B-box zinc finger gene family consisting of transcription factors, protooncogenes, and ribonucleoproteins. Its function is regulated by retention in the cytoplasm from oocyte maturation until the mid blastula transition (MBT) when it reenters the nucleus. We defined a 22-amino acid cytoplasmic retention domain (CRD) in xnf7 that functioned cooperatively with two phosphorylation sites within the xnf7 molecule to retain the protein in the cytoplasm until the MBT.

Translocation of repetitive RNA sequences with the germ plasm in Xenopus oocytes.

Xlsirts are a family of interspersed repeat RNAs from Xenopus laevis that contain from 3 to 13 repeat units (each 79 to 81 nucleotides long) flanked by unique sequences. They are homologous to the mammalian Xist gene that is involved in X chromosome inactivation. Xlsirt RNA appears first in the mitochondrial cloud (Balbiani body) in stage 2 oocytes and is then translocated as island-like structures to the vegetal cortex at early stage 3 coincident with the localization of the germ plasm.

Two upstream cysteines and the CAAX motif but not the polybasic domain are required for membrane association of Xlcaax in Xenopus oocytes.

We have analyzed the role of several protein motifs in controlling the membrane association of the xlcaax-1 protein in Xenopus oocytes. Xlcaax-1 is a maternally expressed protein that during development is associated with the basal lateral membrane of polarized epithelial cells. It is enriched in the tubule cells of the adult kidney and several other organs that are involved in osmoregulation.

The cloning and characterization of a localized maternal transcript in Xenopus laevis whose zygotic counterpart is detected in the CNS.

We have cloned a cDNA (xlan4) from a Xenopus laevis oocyte cDNA library whose cognate mRNA is localized in the animal pole region of full grown oocytes. The cDNA can be translated in vitro to produce a predicted size protein of 35 kDa and, is also expressed in E. coli as a fusion protein.

Xlcaax-1 is localized to the basolateral membrane of kidney tubule and other polarized epithelia during Xenopus development.

Xlcaax-1 is a novel, maternally expressed, 110-kDa, CAAX box containing protein that undergoes isoprenylation and palmitoylation through which it associates with the plasma membrane. We report here the cellular and subcellular localization of the xlcaax-1 protein during development of Xenopus laevis. Whole-mount immunocytochemistry and immunoperoxidase staining of tissue sections show that during development the xlcaax-1 protein accumulation is coincident with the differentiation of the epidermis, pronephros, and mesonephros.

The cloning and characterization of a maternally expressed novel zinc finger nuclear phosphoprotein (xnf7) in Xenopus laevis.

We report the cloning of a cDNA (xnf7) coding for a maternally expressed Xenopus protein that becomes highly enriched in nuclei of the central nervous system during later development and in nuclei of adult brain. The protein also shows stage-specific nuclear/cytoplasmic partitioning and phosphorylation that may be related to its function. In addition, it binds to double-stranded DNA in vitro.

The nuclear-cytoplasmic distribution of the Xenopus nuclear factor, xnf7, coincides with its state of phosphorylation during early development.

We describe the characterization in Xenopus laevis of a nuclear protein, xnf7, which is first detected in the oocyte GV and is eventually enriched in nuclei of cells of the adult brain. Previous studies have shown that this protein contains zinc-finger-like structures and acidic domains typical of transcriptional activators, and is phosphorylated in vitro by p34cdc2 protein kinase. The protein also binds to double-stranded DNA.

Identification of the cDNA for xlcaax-1, a membrane associated Xenopus maternal protein.

xlcaax-1 is a cDNA coding for a CAAX box containing protein in Xenopus laevis that undergoes isoprenylation and palmitoylation. Here we report on the confirmation that this clone (formerly xlgv7) codes for a 110 kDa membrane associated protein and not an 80 kDa nuclear protein as originally believed (1). The reason for the misidentification was the presence of a common epitope on these two proteins recognized by the monoclonal antibody 37-1A9.

A novel 110-kDa maternal CAAX box-containing protein from Xenopus is palmitoylated and isoprenylated when expressed in baculovirus.

We describe a unique 110-kDa protein, xlcaax-1, that is a member of a group of membrane-associated proteins such as the ras and ras-related proteins and nuclear lamins. Many of these proteins are involved in signal transduction or cell signaling, possess a C-terminal CAAX box, and undergo fatty acid acylation (Glomset, J. A.

x121: a localized maternal transcript in Xenopus laevis.

We describe the cloning and characterization of a partial cDNA, x121, that represents an RNA, which is localized in the animal hemisphere of Xenopus oocytes. This RNA is also detected in an animal to vegetal gradient during early cleavage stages. The x121 RNA titer decreases from fertilization through the gastrula stage, after which it is not detectable on northern blots.

The maternal store of the xlgv7 mRNA in full-grown oocytes is not required for normal development in Xenopus.

We have attempted to analyze the function of a maternal mRNA xlgv7 which is distributed as an animal-vegetal gradient in stage 6 oocytes using a combination of antisense oligodeoxynucleotide injection into oocytes followed by in vitro maturation and fertilization. Injection of 20 ng of the antisense oligodeoxynucleotide resulted in the destruction of the xlgv7 mRNA to undetectable levels. Upon maturation and fertilization the resulting embryos develop with no specific defects suggesting that the maternal store of xlgv7 in stage 6 oocytes is not required and that the embryo can develop solely with the maternal store of the xlgv7 protein.

xlgv7: a maternal gene product localized in nuclei of the central nervous system in Xenopus laevis.

The Xenopus oocyte nucleus (GV) is a storehouse for a large number of proteins that are used during early development. We have cloned and characterized a cDNA coding for a maternal gene product that is localized in the GV and then becomes highly enriched in the nuclei of the central nervous system (CNS) of tadpoles and adult frogs. This cDNA (xlgv7) is 2.

Heat-shock response is associated with enhanced postischemic ventricular recovery.

In cells, hyperthermia induces synthesis of heat-shock proteins and the acquisition of thermotolerance. Thermotolerant cells are resistant to subsequent oxidative stress. In this study, heat-shocked hearts were examined for evidence of protection during ischemia and reperfusion.

Decay of the oocyte-type heat shock response of Xenopus laevis.

Xenopus oocytes have a complex heat shock response. During transition of the oocyte into fertilized egg, the heat shock response undergoes several qualitative and quantitative changes culminating in its complete extinction. Heat shock induces oocytes to synthesize four heat shock proteins (hsps): 83, 76, 70, and 57.

Acquisition of the heat-shock response and thermotolerance during early development of Xenopus laevis.

The ability to synthesize a 68,000- to 70,000-Da protein (hsp) in heat-shocked early Xenopus laevis embryos is dependent on the stage of development. Whereas late blastula and later stage embryos synthesize hsp68-70 after heat shock, cleavage stages are incompetent with respect to hsp synthesis. In vitro translation experiments and RNA blot analyses demonstrate that enhanced synthesis of hsp68-70 is associated with an accumulation of hsp68-70 mRNA.

Extrachromosomal DNA and its activity in RNA synthesis in oogonia and oocytes in the pupal ovary of Creophilus maxillosus (Staphylinidae, Coleoptera-Polyphaga).

The participation of extrachromosomal DNA (extra DNA) in RNA synthesis in the nuclei of terminal oogonial cells and oocytes in the pupal ovary of Creophilus maxillosus (Staphylinidae, Coleoptera) was examined by autoradiography. It was found that extra DNA in the nuclei of terminal oogonial cells, although predominantly in a condensed and heterochromatic state, produces numerous nucleoli and incorporates 3H-uridine during the interphases between successive differential divisions. Moreover, it was shown that extra DNA is active in RNA synthesis at the same stage of pupal development in which it is synthesized and accumulated, i.

Extrachromosomal DNA and the origin of oocytes in the telotrophic-meroistic ovary ofCreophilus maxillosus (L.) (Staphylinidae, Coleoptera-Polyphaga).

The development of the telotrophic ovary in the Staphylinid beetle,Creophilus maxillosus was examined. Cells, termed chordoblasts were identified in the germarium of 1-day-old pupae. Each of the chordoblasts undergoes a series of synchronous mitoses.

Extrachromosomal DNA and RNA-synthesis in oocytes of Creophilus maxillosus (Staphylinidae, Coleoptera, Polyphaga).

It has been found that the transcriptional activity of nuclear extra DNA in Creophilus maxillosus oocytes, as examined by autoradiography, increases parallel with its dispersion during the previtellogenic period of oocyte growth. The RNA, after being synthesized in the greatly enlarged oocyte nucleus, is subsequently transported into the cytoplasm. The oocyte chromosomes form a karyosphere and synthesize the RNA more weakly than other parts of the nucleus, which contain the extra DNA in a highly dispersed condition.

Gene amplification in oocytes of the rove beetle Creophilus maxillosus (Staphylinidae, Coleoptera-Polyphaga).

The extra-DNA body was found, for the first time, in oocytes of an insect with telotrophic ovary. Dispersion of this body is accompanied by an enormous increase of nuclear volume and production of multiple nucleoli. It is suggested that the extra-DNA contains a huge mass of nucleolus organizers.