Publications

inhibition by phenothiazine derivatives of the adenylate cyclase of amphibian oocytes.	the adenylate cyclase activity of membranes of xenopus laevis oocytes and follicle cells was affected by the presence of 2-chloro-10-(3-aminopropyl)phenothiazine (capp) and two other antipsychotic drugs, fluphenazine and penfluridol. capp, at concentrations of 10 and 100 microm, had opposite effects on the activation of the oocyte adenylate cyclase by effectors that act through the g/f regulatory subunit. under these conditions, the drug stimulated the activation by fluoride and drastically inhi ...	1983	6139113
voltage-operated channels induced by foreign messenger rna in xenopus oocytes.	poly(a)+ messenger rna (mrna) extracted from rat brains or from cat muscles was injected into xenopus laevis oocytes. this led to the incorporation of voltage-operated na+ and k+ channels into the oocyte membrane. these channels are not normally present in the oocyte and presumably result from the synthesis and processing of proteins coded by the injected mrna. tetrodotoxin blocked the na+ channels induced by mrna derived from either innervated or denervated muscle.	1983	6140681
somatostatin-immunoreactive cells in the gastro-entero-pancreatic endocrine system of xenopus laevis.	somatostatin-like immunoreactivity has been demonstrated in cells of the gastro-entero-pancreatic endocrine system of xenopus laevis (amphibia) using peroxidase-anti-peroxidase immunohistochemistry. the identified cells of the gastro-intestinal tract correspond to the "open-paraneurons" of fujita (1974). somatostatin-immunoreactive cells were found in the stomach (fundic and pyloric region), the duodenum and in the anterior ileum, but not in the colon. the dimensions of these 'somatostatin-open- ...	1983	6142568
comparative actions of glutamate and related substances on the lateral line of xenopus laevis.	the effects of compounds structurally related to l-glutamate were compared on spontaneous activity of afferent nerve fibres in xenopus laevis lateral-line. the potencies (epmr) of several compounds relative to l-glutamate (epmr = 1) were: l-aspartate (epmr = 1), d-aspartate (epmr = 1), d-glutamate (epmr = 1.98), quisqualate (epmr = 0.0015), kainate (epmr = 0.0045), dihydrokainate (epmr = 0), ibotenate (epmr = 1.5), l-homocysteate (epmr = 0.17), 2,4,5-trihydroxyphenylalanine (6-oh-dopa, epmr = 0. ...	1983	6138189
in contrast to other xenopus genes the estrogen-inducible vitellogenin genes are expressed when totally methylated.	the methylation-sensitive restriction enzymes hha i and hpa ii were used to analyze the methylation pattern of four xenopus laevis genes in dna of embryos, of erythrocytes, and of untreated and estrogen-treated hepatocytes. within these four genes all sites tested are fully modified in embryonic dna. however, the adult beta 1-globin gene is unmethylated in dna of erythrocytes, where it is expressed, and the 68 kd albumin gene, active only in hepatocytes, is specifically hypomethylated in hepatic ...	1983	6088055
in vivo effects of microinjected alkaline phosphatase and its low molecular weight substrates on the first meiotic cell division in xenopus laevis oocytes.	xenopus laevis oocytes were microinjected with low molecular weight phosphoesters such as 2-glycerophosphate, phosphotyrosine, phosphoserine, phosphothreonine, 4-nitrophenyl phosphate, and orthophosphate. these compounds were able to induce a considerable reduction in the time course of progesterone-induced maturation, with 2-glycerophosphate being the most effective. the basal level of camp and its drop during maturation were not affected by the microinjection of 2-glycerophosphate. the injecti ...	1984	6089179
induction of human interleukin 1 mrna measured by collagenase- and prostaglandin e2-stimulating activity in rheumatoid synovial cells.	human blood peripheral monocyte/macrophages release in culture a mononuclear cell factor (mcf) which stimulates the production of collagenase and prostaglandin e2 by human rheumatoid synovial cells and dermal fibroblasts. these two products play a role in connective tissue destruction. mcf has an apparent molecular weight of approximately 15 000 and is biologically and biochemically indistinguishable from interleukin 1. mcf therefore belongs to the well-documented nonimmune biological activities ...	1984	6092094
intracellular acetylation of desacetyl alpha msh in the xenopus laevis neurointermediate lobe.	high performance liquid chromatography (hplc) followed by radioimmunoassay (ria) of the chromatographic fractions were used to separate and quantify, respectively, the alpha msh-like peptides stored in the neurointermediate lobe (nil) of the xenopus laevis (x. laevis) pituitary gland and released from the x. laevis nil, in vitro. immunoreactive (ir) material eluting with a similar hplc retention time as desacetyl alpha msh was the major ir peptide in the nil. material with a retention time simil ...	1984	6099561
slowly inactivating potassium channels induced in xenopus oocytes by messenger ribonucleic acid from torpedo brain.	poly(a+) messenger rna was extracted from the electric lobe and medulla of torpedo and injected into oocytes of xenopus laevis. the synthesis and processing of proteins coded by the injected messenger rna led to the incorporation of voltage-activated channels in the oocyte membrane. a large, well maintained outward current was recorded from injected oocytes in response to depolarization. non-injected oocytes did not show this current. the reversal potential of the current varied according to the ...	1984	6090641
digitoxigenin, a digitalis steroid, induces meiotic maturation of xenopus laevis oocytes.	digitoxigenin, a c23 digitalis steroid induces meiotic maturation of xenopus oocyte. the dose of digitoxigenin which induces half maximal response is 3.3 +/- 2.10(-5)m. in contrast the conjugated digitalis steroid, digitoxin (digitoxigenine + 3 digitoxoses) never triggered maturation at any of the doses tested. these experiments which show that only free digitoxigenin mimics progesterone action, suggest that both digitoxigenin and progesterone possess a common initial site of action which is not ...	1984	6087028
the complete nucleotide sequence of a rice 17s rrna gene.	the complete nucleotide sequence of a rice nuclear 17s rrna gene (rdna) has been determined. the rice rdna is 1812 bp long and its g + c content is 51.3%. this nucleotide sequence shows 79%, 80% and 80% homology to those of yeast, xenopus laevis and rat 18s rdnas, respectively. divergency of nucleotide sequences is largely attributed to five blocks of highly variable regions, where eukaryotic specific sequences can be observed.	1984	6087286
the primary structure of the larval beta 1-globin gene of xenopus laevis and its flanking regions.	we present the complete nucleotide sequence of the larval beta i-globin gene of xenopus laevis including 240 nucleotides of the 5' flanking region and 594 nucleotides beyond the polyadenylation site. the site of transcription initiation was mapped by s1 nuclease, and the site of polyadenylation was determined by comparison with corresponding cdna clones. the larval xenopus beta i-gene shows the same internal structure as the beta-globin genes of higher vertebrates, viz. 3 exons interrupted by 2 ...	1984	6093050
atp and the processivity of xenopus laevis dna polymerase alpha.	we use specific restriction fragments as defined primers for dna synthesis on single-stranded circular phage fd dna. these structures are relatively poor templates for a highly purified dna polymerase alpha from xenopus laevis eggs. however, dna synthesis is stimulated about 5-fold by addition of atp to the reaction mixture. we show that the deoxynucleotide polymers, synthesized in the presence of atp, are significantly longer than those produced in the absence of atp. we also show that this eff ...	1984	6093886
a ca2+-activated channel from xenopus laevis oocyte membranes reconstituted into planar bilayers.	plasma membrane fractions from xenopus laevis oocytes were incorporated into planar lipid bilayers. we show the existence of numerous ca2+-activated nonspecific channels that are more permeable to anions. these channels are activated by ca2+ at micromolar concentration but not by mg2+, zn2+, or mn2+, even at millimolar concentrations. decreasing ca2+ concentration to less than 1 microm decreases the time of channel opening until channels close completely in the absence of ca2+ and in the presenc ...	1984	6089180
co-linear organization of xenopus laevis and mouse mitochondrial genomes.	cloned fragments of xenopus laevis mitochondrial dna and pleurodeles waltlii mitochondrial cdnas have been hybridized together and with mouse mtdna. in the three cases cross-hybridization was observed. the overall organization of the x. laevis fragments appeared to be co-linear with the mouse mtdna, most sequences being conserved except for the d-loop and the urf6 regions. the use of mouse mtdna has enabled us to identified several mitochondrial genes in x. laevis and p. waltlii.	1984	6089785
exonucleases participating in the 3'end turnover of trna in xenopus laevis.	nuclei and enucleated xenopus laevis oocytes were used as a source of exonucleases that hydrolyze the 3'terminus sequence of trna. the majority of the total activity was found in the cytoplasm. several forms of enzyme activity are obtained upon fractionation in s-200 column. both nuclear and cytoplasmic activities display a preferential cleavage of the terminal amp residue. similar results are obtained in vivo by microinjection of trna labelled in the cca sequence. aminoacylation of trna, on the ...	1984	6089833
beta-endorphins (beta-ep) in amphibians: higher beta-ep levels during regenerating stages of anuran life cycle and immunocytochemical localization of beta-ep in regeneration blastemata.	plasma beta-endorphin (beta-ep) levels were measured at different stages of metamorphosis in anuran species, namely rana catesbeiana, r. pipiens, and xenopus laevis. the mean levels of beta-ep in tadpoles and postmetamorphic juveniles were significantly higher than adult levels in all three species examined. the pattern of high tadpole levels and low adult levels corresponds with the limb regeneration ability of the tadpole and restriction in the adult. we have also reported plasma beta-ep level ...	1984	6094701
the absence of calcium blocks impulse-evoked release of acetylcholine but not de novo formation of functional neuromuscular synaptic contacts in culture.	we have examined the role of calcium-dependent, impulse-evoked release of acetylcholine (ach) in the formation of functional neuromuscular contacts. dissociated cell cultures prepared from xenopus laevis embryos were maintained either in standard medium containing calcium or in calcium-free medium. both the number of neuron-myocyte contacts and the number of terminations of neurites on myocytes were reduced in ca-free medium. intracellular recordings from neuron-myocyte pairs during perfusion wi ...	1984	6094749
synthesis of an ochre suppressor trna gene and expression in mammalian cells.	we have used site-specific mutagenesis to change the anticodon of a xenopus laevis tyrosine trna gene so that it would recognize ochre codons. this trna gene is expressed when amplified in monkey cells as part of a sv40 recombinant and efficiently suppresses termination at both the ochre codon separating the adenovirus 2 hexon gene from a 23-kd downstream gene and the ochre codon at the end of the ns1 gene of influenza virus a/tex/1/68. termination at an amber codon of a ns1 gene of another infl ...	1984	6096120
direct demonstration of impaired functionality of a purified desensitized beta-adrenergic receptor in a reconstituted system.	long-term exposure of various cell types to beta-adrenergic agonists such as isoproterenol leads to an attenuated responsiveness ("desensitization") of the adenylate cyclase system to further challenge with these agonists. the turkey erythrocyte model system was used earlier to show that a covalent modification of the receptor (phosphorylation) is associated with this process. the functionality of the "desensitized" beta-adrenergic receptor was assessed by implanting purified beta-adrenergic rec ...	1984	6089331
human u2 and u1 rna genes use similar transcription signals.	we have analyzed the requirements for human u2 rna transcription by injection of cloned u2/6 rna genes into nuclei of xenopus laevis oocytes. two forms of human u2 rnas accumulate, a major species corresponding to mature-sized u2 rna and a minor species corresponding to a 3'-extended precursor. this rna polymerase ii transcription requires only 258 and 94 bp of 5'- and 3'-flanking region sequences, respectively. efficient u2 rna synthesis depends on a promoter element located between positions - ...	1984	6084596
the development of the pars intermedia and its role in the regulation of dermal melanophores in the larvae of the amphibian xenopus laevis.	the ontogenesis of biosynthesis of pro-opiomelanocortin (pomc)-related peptides in the pars intermedia of xenopus laevis tadpoles was studied. the results were related to the capacity of the animal to adapt to background color through regulation of pigment dispersion in dermal melanophores. using immunocytochemical techniques with antisera to alpha-melanophore-stimulating hormone (alpha-msh), it was revealed that this peptide first appeared at developmental stage 37/38, just prior to the animal' ...	1984	6086446
5s rna structure and interaction with transcription factor a. 2. ribonuclease probe of the 7s particle from xenopus laevis immature oocytes and rna exchange properties of the 7s particle.	the 5s rna complexed in the 7s particle of immature xenopus laevis oocytes was 32p labeled at its 3' end and then subjected in situ to partial digestion using ribonucleases t1, t2, a, and v1 in order to study the conformation of the complexed rna and its interaction with the transcription factor a (tfiiia). digested samples were gel purified to retrieve 5s rna that was still complexed with the transcription factor protein, and the cleavages in these rnas were analyzed on sequencing gels. the rna ...	1984	6084516
evidence for an intracellular precursor for human b-cell growth factor.	human b-cell growth factor has been described as a trypsin-sensitive protein of mr 12,000-14,000. evidence is provided herein that this relatively low molecular weight product may be released from a larger precursor molecule of mr 60,000-80,000. the precursor protein is confined to the cytosol of freshly isolated t lymphocytes, and only the mr 12,000-14,000 moiety is released upon lectin stimulation. the precursor protein was subjected to limited tryptic digestion, which demonstrated that the bi ...	1984	6083564
expression of two xenopus laevis ribosomal protein genes in injected frog oocytes. a specific splicing block interferes with the l1 rna maturation.	the expression of two xenopus laevis ribosomal protein genes (l1 and l14) has been analysed by microinjection of the cloned genomic sequences into frog oocyte nuclei. while the injection of the l14 gene causes the accumulation of the corresponding protein in large excess with respect to that synthesized endogenously, the l1 gene does not. analysis of the rna shows that both genes are actively transcribed. the seven-intron-containing l14 transcript is completely processed to a mature form, while ...	1984	6084725
nucleotide sequence of human monocyte interleukin 1 precursor cdna.	interleukin 1 (il-1) is a protein with several biological activities regulating host defense and immune responses. we report here the isolation of human il-1 cdna. it encodes a precursor polypeptide of 269 amino acids (30,747 mr). mrna isolated by hybridization to this cdna was translated in a reticulocyte cell-free system, yielding immunoprecipitable il-1. furthermore, this hybrid-selected mrna was injected into xenopus laevis oocytes, which subsequently secreted biologically active il-1. the c ...	1984	6083565
the two embryonic u1 small nuclear rnas of xenopus laevis are encoded by a major family of tandemly repeated genes.	we have identified a large family of u1 rna genes in xenopus laevis that encodes two distinct species of u1 rna. these genes are expressed primarily at the onset of transcription in the 4,000-cell embryo (d. j. forbes, m. w. kirschner, d. caput, j. e. dahlberg, and e. lund, cell 38:681-689, 1984). the two types of embryonic u1 rna genes are interspersed and are organized in large tandem arrays. the basic 1.9-kilobase repeating unit contains a single copy of each of the embryonic genes and is rei ...	1984	6084809
methylation of the sv40 hpaii site does not affect late viral gene expression in microinjected tissue culture cells.	intranuclear coinjection of the late sv40 kpni/bcli dna fragment and the early promotor/enhancer hpaii/bgli dna segment into permissive monkey and non-permissive mouse cells allows late sv40 gene expression without t-antigen synthesis and dna replication. these conditions were chosen to analyse the effect of dna methylation on v-antigen synthesis detached from the process of dna replication. we found that in vitro methylation of a single cytosine nucleotide proximal to the major late mrna cap si ...	1984	6086395
inositol incorporation into phosphoinositides in retinal horizontal cells of xenopus laevis: enhancement by acetylcholine, inhibition by glycine.	the absorption of light by photoreceptor cells leads to an increased incorporation of [2-3h]inositol into phosphoinositides of horizontal cells in the retina of xenopus laevis in vitro. we have identified several retinal neurotransmitters that are involved in regulating this response. incubation with glycine, the neurotransmitter of an interplexiform cell that has direct synaptic input onto horizontal cells, abolishes the light effect. this inhibition is reversed by preincubation with strychnine ...	1984	6086673
5s rna structure and interaction with transcription factor a. 1. ribonuclease probe of the structure of 5s rna from xenopus laevis oocytes.	the structure of xenopus laevis oocyte (xlo) 5s ribosomal rna has been probed with single-strand-specific ribonucleases t1, t2, and a with double-strand-specific ribonuclease v1 from cobra venom. the digestion of 5'- or 3'-labeled renatured 5s rna samples followed by gel purification of the digested samples allowed the determination of primary cleavage sites. results of these ribonuclease digestions provide support for the generalized 5s rna secondary structural model derived from comparative se ...	1984	6084515
splicing of xenopus laevis ribosomal protein rnas is inhibited in vivo by antisera to ribonucleoproteins containing u1 small nuclear rna.	the activity of antisera against ribonucleoproteins containing u1 small nuclear rna (sm and rnp) has been analysed on pol ii transcripts in an in vivo system. xenopus laevis ribosomal protein gene transcripts are accumulated in the form of precursor rna when either of the two kinds of antisera are injected into the germinal vesicles of x. laevis oocytes before the injection of purified l1 and l14 ribosomal protein genes. no effect on the accumulation of mature histone mrna is detected when x. la ...	1984	6084721
pharmacological regulation in vitro of meiotic resumption in oocytes of xenopus laevis.	the pharmacological control in vitro of meiotic resumption in xenopus laevis oocytes was undertaken with a variety of drugs or agents which either mimic a steroidal hormone, progesterone, the physiological inducer of meiosis in vivo and in vitro, potentiate progesterone-induced meiosis (e.g. insulin) or inhibit the action of steroidal and non-steroidal inducers. most steroidal and non-steroidal inducers trigger a cascade of cellular events which seem to be initiated at the oocyte membrane. one m ...	1984	6100710
efficient expression of cloned complementary dnas for secretory proteins after injection into xenopus oocytes.	cloned complementary dnas encoding chicken ovalbumin, chicken prelysozyme and calf preprochymosin, prochymosin and chymosin were inserted downstream from various viral promoters in modified recombinant "shuttle" vectors. microinjection of the ovalbumin, prelysozyme and preprochymosin constructs into the nuclei of xenopus laevis oocytes resulted in the synthesis, segregation in membranes and secretion into the extracellular medium of ovalbumin, lysozyme and prochymosin, respectively. judging from ...	1984	6098686
properties of non-junctional acetylcholine receptor channels on innervated muscle of xenopus laevis.	patch-clamp recordings of current through acetylcholine-activated channels were made from non-junctional membrane of innervated myotomal muscle from xenopus laevis. two classes of acetylcholine (ach) receptor channels were identified on the basis of current amplitudes. both amplitude classes exhibited current-voltage relations which deviated from linearity as the extrapolated reversal potential was approached (-5 to -12 mv). over the range of greatest linearity the conductances of the two classe ...	1984	6086900
xenopus oocyte resting potential, muscarinic responses and the role of calcium and guanosine 3',5'-cyclic monophosphate.	resting potential (r.p.) and muscarinic response mechanisms were studied in xenopus laevis oocytes using the voltage-clamp technique. insertion of micro-electrodes into the oocyte produced a 'shunt' membrane conductance which partially sealed after a few minutes. the oocyte resting potential (measured with a single intracellular electrode) ranged from -40 to -60 mv. ouabain and low k+ solution depolarized both follicles and denuded oocytes. the electrogenic na+-k+ pump was more active in the lat ...	1984	6086916
induction and disappearance of excitability in the oocyte of xenopus laevis: a voltage-clamp study.	electrically excitable, sodium-selective channels are induced in the membrane of the oocytes of xenopus laevis when it is submitted to prolonged positive potentials (kado, marcher & ozon, 1979; baud, kado & marcher, 1982). under a long positive voltage-clamp step, the membrane current, initially outward, becomes inward with a sigmoidal time course. the mean time to half-maximal inward current (t 1/2) is about 18 s at 16 degrees c when stepping the membrane potential to +55 mv. the rate of channe ...	1984	6097673
translation in xenopus oocytes of messenger rna from a431 cells for human epidermal growth factor receptor proteins.	translation of messenger rnas (mrnas) for human epidermal growth factor receptor (egf-r) proteins was accomplished in a xenopus oocyte translation system. translation of these mrnas in rabbit reticulocyte lysates and wheat germ extracts were unsuccessful, in accordance with the general difficulty in translating mrnas for membrane-bound glycoproteins in conventional heterologous cell-free systems. total poly(a)+rna from a human epidermoid carcinoma cell line a431 was injected into oocytes from xe ...	1984	6096098
genetic recombination of xenopus laevis 5 s dna in bacteria.	the behavior in genetic recombination of xenopus laevis 5 s dna has been examined, with particular emphasis on the role of 15-base-pair tandem repeats in the a + t-rich spacer. fragments of 5 s dna were introduced into escherichia coli cells as inserts in the recombination vectors, lambda rva and lambda rvb. intermolecular recombinants were selected in which, because of properties of the phage vectors, the crossover event must have occurred within the 5 s dna inserts. inserts from individual rec ...	1984	6092642
stimulation of uridine phosphorylation in primary cultures of xenopus laevis hepatocytes by estradiol-17 beta.	the effects of estrogen on the uridine uptake into cells were examined in primary cultures of liver parenchymal cells from xenopus laevis. the total uptake of [3h]uridine into the estrogen-treated cells and its incorporation into rna were about 1.5 times higher than the values for control cells. the uptake of [3h]adenosine and its incorporation into rna were not affected by estrogen. an experiment in which liver parenchymal cells were double labeled with [3h]uridine and [3h]adenosine showed that ...	1984	6094021
na+/k+-atpase from xenopus laevis (daudin) kidney and epidermis: high sensitivity towards regulatory compounds.	na+/k+-atpase was prepared from xenopus laevis epidermis. purification was obtained by ultracentrifugation on sucrose discontinuous gradient. the maximum of enzyme-containing membranes was concentrated in the denser sucrose layer, exhibiting a good and long-lasting activity (specific activity about 55 mumoles of atp hydrolyzed/mg of protein/hour). the kd for the ouabain of kidney and epidermis enzymes were very low (in purified preparations respectively 16 nm for kidney enzyme and 4 nm for skin ...	1984	6094094
effects of synthetic mammalian thyrotrophin releasing hormone, somatostatin and dopamine on the secretion of prolactin and growth hormone from amphibian and reptilian pituitary glands incubated in vitro.	pituitary glands of grassfrog (rana pipiens), bullfrog (rana catesbeiana), clawed toad (xenopus laevis) and two species of terrapin (chrysemys picta and pseudemys scripta) were incubated in medium containing hypothalamic extract (he), thyrotrophin releasing hormone (trh), somatostatin, dopamine, or combinations of these treatments. prolactin and gh concentrations in the medium were determined by densitometry after polyacrylamide-gel electrophoretic separation. hypothalamic extract stimulated sec ...	1984	6146654
translation of mrna for human lymphotoxin in microinjected xenopus oocytes.	synthesis and secretion of biologically active human lymphotoxin (lt) can be detected in xenopus laevis oocytes following their inoculation with poly(a+) rna from human stimulated peripheral blood lymphocytes, but not in oocytes inoculated with rna from unstimulated lymphocytes or from fibroblastoid cells. in size-fractionating mrna of stimulated lymphocytes most lt activity is found to be coded for by rna with an approximate sedimentation value of 19 s.	1984	6150867
effects of atp and related compounds on the ca-induced ca release mechanism of the xenopus sr.	the effects of atp and related compounds on the ca2+ release mechanism of the sarcoplasmic reticulum (sr) was studied by using skinned skeletal muscle fibers of xenopus laevis. atp evoked marked ca2+ release at very low level of mg2+. beta, gamma-methylene analogue of atp was almost as effective as atp, which suggests ca2+ release evoked by atp is elicited without atp hydrolysis. adp and amp also evoked ca2+ release from the sr, but the effect of them became gradually weaker than that of atp as ...	1984	6143296
adrenergic regulation of glycogenolysis in liver of xenopus laevis in vitro.	glycogenolysis was stimulated by catecholamines in in vitro cultures of hepatic tissue of xenopus laevis. dose response curves showed that adrenaline and isoprenaline were equally effective while noradrenaline and phenylephrine were progressively less effective in eliciting glycogen breakdown. neither oxymetazoline nor methoxamine had any effect on glycogenolysis. administration of adrenaline to cultures was followed within 1 min by a rise in tissue cyclic amp concentration and within 2 min by a ...	1984	6144450
region-specific regulation of the actin multi-gene family in early amphibian embryos.	the actin multi-gene family shows both spatial and temporal regulation during early embryogenesis in the amphibian xenopus laevis. both muscle-specific and ubiquitous cytoskeletal actin genes are activated at the end of gastrulation; transcription of the alpha-cardiac and alpha-skeletal actin genes is restricted to the somitic mesoderm and its muscle-forming derivatives providing a convenient molecular marker for this early embryonic tissue.	1984	6151706
inhibitors of metalloendoprotease activity prevent k+-stimulated neurotransmitter release from the retina of xenopus laevis.	metalloendoprotease activity was identified in retinal homogenates using a synthetic fluorogenic metalloendoprotease substrate and specific metalloendoprotease inhibitors. the requirement of metalloendoprotease activity in neurotransmitter release was examined during the depolarization-induced release of [3h]glycine from the retina of xenopus laevis. neurons with high affinity uptake and calcium-dependent, k+-stimulated release of glycine have been described previously in this retina. when isola ...	1984	6150072
analysis of embryonic induction by using cell lineage markers.	three distinct inductive interactions have been demonstrated in early embryos of xenopus laevis: mesoderm induction, dorsalization and neural induction. the experiments were done with grafts from embryos uniformly labelled with passive cell lineage markers, either fitc-lysine-dextran (fldx) or horseradish peroxidase (hrp), which allow the provenance of regions to be determined down to the single cell level. in each case the fate of the target tissue in the presence of the appropriate inductor wa ...	1984	6151705
glutamate and kainate receptors induced by rat brain messenger rna in xenopus oocytes.	xenopus laevis oocytes injected with poly(a)+ mrna extracted from rat brain became sensitive to serotonin, glutamate, kainate, acetylcholine and gamma-aminobutyrate. application of these substances to mrna-injected oocytes elicited membrane currents. the glutamate- and acetylcholine-induced currents usually showed oscillations, while the kainate current was smooth. the current oscillations during glutamate application reversed direction at about the chloride equilibrium potential (-24 mv), but t ...	1984	6145158
the relation between soma position and fibre trajectory of neurons in the mesencephalic trigeminal nucleus of xenopus laevis.	in adult xenopus laevis the mandibular and ophthalmic branches of the trigeminal nerve were backfilled with cocl2 or cobaltous lysine and whole brains silver intensified to reveal neurons of the mesencephalic vth nucleus (mes. v). the nucleus contains about 100 cells arranged in a band extending arch-like from the ventrolateral margin of the optic tectum to the midline. many cells possess a small number of short dendritic processes that arborize in the tectal neuropil; in some cells one dendrite ...	1984	6146985
xenopus laevis 28s ribosomal rna: a secondary structure model and its evolutionary and functional implications.	based upon the three experimentally derived models of e. coli 23s rrna (1-3) and the partial model for yeast 26s rrna (4), which was deduced by homology to e. coli, we derived a secondary structure model for xenopus laevis 28s rrna. this is the first complete model presented for eukaryotic 28s rrna. compensatory base changes support the general validity of our model and offer help to resolve which of the three e. coli models is correct in regions where they are different from one another. eukary ...	1984	6147812
regional distribution of polyadenylated mrna in xenopus laevis embryos.	xenopus laevis embryos were dissected into dorsal and ventral regions in post-gastrula stages. polyadenylated and nonpolyadenylated ribonucleic acids were separated on oligo (dt) cellulose and translated in vitro. the radioactivity incorporated into the translation products directed by polyadenylated and nonpolyadenylated messenger ribonucleic acids shows that in the dorsal region most proteins are synthesized on polyadenylated messenger ribonucleic acid templates in all the stages, while in the ...	1984	6148270
myosin isoenzymes in single muscle fibres of xenopus laevis: analysis of five different functional types.	an analysis has been performed of the native myosin isoenzyme composition of isolated skeletal muscle fibres from xenopus laevis with well-defined isotonic contraction properties. fast twitch 'white' (type 1) fibres contained three isomyosins; fast twitch 'red' (type 2) fibres showed two major myosin bands with migration velocities very similar to those of the two slower bands in type 1. slow twitch (type 3) fibres yielded a single, slowly migrating band as did slow tonic (type 5) fibres, wherea ...	1984	6149559
a temporal variation in nonneuronal protein synthesis in dorsal root ganglia and nerve and its significance to studies of axonal transport.	protein synthesis and fast axonal transport were studied in vitro using dorsal root ganglia (drg)-sciatic nerve preparations from the amphibian xenopus laevis. it was observed that the rate of incorporation of [3h]leucine into protein in drg and isolated segments of nerve began to increase 9 to 11 h after killing the animal, attaining at 13 to 17 h a maximum of 5- to 10-times preincrease (less than 9 h) values. at the same time as an increase in the rate of incorporation began, synthesis commenc ...	1984	6199227
patterns of junctional communication in the early amphibian embryo.	it has long been recognized that cells in early embryos can communicate with each other via a direct cell-to-cell pathway, probably mediated by gap junctions. low electrical resistance pathways, detected electrophysiologically, have been identified in all species examined so far. however, studies in various embryos on the transfer of molecules larger than small ions (for example, fluorescent dyes in the molecular weight range 350-500) have given conflicting results. in all these studies the abil ...	1984	6206399
a monoclonal antibody against nuclear lamina proteins reveals cell type-specificity in xenopus laevis.	immunofluorescence microscopy shows that the monoclonal murine antibody pkb8 stains the nuclear lamina of various somatic cells from vertebrates as diverse as mammals, birds and amphibia. it also decorates the nuclear periphery of oocytes from rat and chicken but does not react with spermatocytes, spermatids and spermatozoa. immunoblotting experiments demonstrate reaction with lamina polypeptides a, b and c of rat, with lamina polypeptide a of chicken, and with lamina polypeptides li and lii of ...	1984	6198191
helper activity for antibody synthesis encoded by mrna extracted from human peripheral blood mononuclear cells.	translation products in xenopus laevis of mrna from human peripheral blood mononuclear cells were tested for their capacity to replace t cells in the anti-srbc response of nude spleen cells. when the starting material came from pha or fcs-stimulated lymphocytes, the translated lymphokines, displaying such a b cell helper activity were found to be encoded by mrna sedimenting at 6-7s and 13s on a sucrose density gradient. 6-7s mrna from control, non-stimulated lymphocytes was also able to code for ...	1984	6201168
in vitro methylation of hpaii sites in xenopus laevis rdna does not affect its transcription in oocytes.	the effect of methylation of x. laevis rdna on its transcription was tested by methylating all of the hpaii sites in a series of rdna plasmids and injecting the methylated rdna into x. borealis oocytes. analysis of rna transcribed from the injected plasmids showed that methylation of rdna in vitro does not affect transcription of x. laevis ribosomal genes. this result suggests that despite the observed correlation between demethylation of rdna and synthesis of ribosomal rna in x. laevis embryos ...	1984	6199746
cyclosporin a is a differential inhibitor of eukaryotic rna polymerases.	in order to investigate the molecular mechanism of biological action of the drug cyclosporin a (csa), we have studied its effect on eukaryotic rna polymerase activities in two systems: (a) in vitro transcription; (b) injection into frog oocytes. the electron microscopic transcription r-loop method [1] has been used to assay for specific transcription of an immunoglobulin gene clone in hela cell lysates. in this system, csa inhibits efficiently the transcription of immunoglobulin genes. dilution ...	1984	6200340
coincidence of endoplasmic reticulum pattern as visualized by fitc-con a-fluorescence and electron microscopy.	fitc-con a-fluorescence and electron microscopy have been used in parallel for the visualization of rough endoplasmic reticulum in xenopus laevis tadpole heart primary tissue culture cells. rer distribution pattern as revealed by both methods is compared by superimposition of images of the same cell. coincidence of rer distribution is established.	1984	6201466
sensory physiology, anatomy and immunohistochemistry of rohon-beard neurones in embryos of xenopus laevis.	rohon-beard neurones show substance p-like immunoactivity in their somas and in their centrally projecting axons. peripherally, the morphology of their free nerve endings within the trunk skin has been shown using horseradish peroxidase staining. the excitation of rohon-beard neurones by natural and electrical stimulation of the skin has been examined using intracellular micro-electrodes in the late embryo of xenopus laevis. rohon-beard cells are sensitive to transient, local indentation of the ...	1984	6201612
immunological identity of proteins that bind stored 5s rna in xenopus oocytes.	in small oocytes of xenopus laevis, the three most abundant proteins are isolated as basic polypeptides with molecular weights of 48 kd (p48), 43 kd (p43) and 40 kd (p40, also known as transcription factor iiia). all three proteins share common properties in being able to bind specifically ribosomal 5s rna molecules and influence, in different ways, their rates of production and utilization. it has been shown by biochemical analysis and immunological characterization that the three proteins are ...	1984	6203770
early cellular interactions promote embryonic axis formation in xenopus laevis.	we have attempted to define the location and mode of action of axial determinants in the egg of xenopus laevis. to this end, we transplanted small numbers of blastomeres from normal 64-cell stage embryos into synchronous recipient embryos which had been irradiated with ultraviolet light prior to first cleavage. without transplantation, such embryos fail to develop dorsal structures of the embryonic body axis. we found that one to three blastomeres transplanted from the vegetal-most octet of cell ...	1984	6203792
synthesis of human u1 rna. ii. identification of two regions of the promoter essential for transcription initiation at position +1.	we have analyzed the requirements for human u1 rna transcription catalyzed by rna polymerase ii. in xenopus laevis oocytes, a human u1 rna gene with only 231 and 35 nucleotides of the 5' and 3' flanking regions, respectively (lund, e. and dahlberg, j. e. (1984) j. biol. chem. 259, 2013-2021), is able to support accumulation of human u1 rna. we show that the point in the template corresponding to the 5' end of u1 rna is a site of transcription initiation. that result rules out the possibility tha ...	1984	6203910
ultrastructural localization of nucleolar organizers during oogenesis in xenopus laevis using a silver technique.	silver staining at the electron microscopic level of the nucleolar organizers was carried out on xenopus laevis oocytes at various stages of oogenesis. the results indicate that a positive reaction takes place exclusively in the dense fibrillar component of the extrachromosomal nucleoli. this constituent undergoes morphological changes of distribution and architecture, which have been correlated with modifications of the transcriptional activity of the nucleoli. when nucleolar activity is reduce ...	1984	6201496
cell lineage analysis of neural induction: origins of cells forming the induced nervous system.	horseradish peroxidase (hrp) was used as an intracellular lineage tracer in two experiments designed to reveal the sites of origin of cells that formed the duplicate embryo which developed in relation to an organizer grafted in the ventral marginal zone (vmz) of xenopus laevis embryos. in the first experiment a dorsal blastoporal lip fully labeled with hrp was grafted in the vmz of an unlabeled embryo at the beginning of gastrulation. this resulted in development of a second embryo in which labe ...	1984	6199240
xenopus laevis u1 snrna genes: characterisation of transcriptionally active genes reveals major and minor repeated gene families.	xenopus laevis u1 snrna genes are found in several different genomic arrangements. the major family of genes is organised in tandem repeats of 1.8 kb. the minor u1-family is much less abundant and is present on 1.2-kb hinfi restriction fragments. in addition there are genomic arrangements present in one or very few copies, which could represent the ends of repeating units. there is no evidence for the presence of u1 pseudogenes in xenopus. a cluster of u1 snrna genes consisting of a member of th ...	1984	6203742
persistence, methylation and expression of vitellogenin gene derivatives after injection into fertilized eggs of xenopus laevis.	we report the fate of different derivatives of the vitellogenin genes after injection into fertilized eggs of xenopus. we injected a constructed minigene as well as a 5' fragment of the a2 vitellogenin gene. the minigene survives in embryogenesis much better than the 5' a2 fragment and is retained more frequently and at a higher level in frog tissues. the mosaic distribution of the foreign dna in different frog tissues indicates that no integration occurred before the first cleavage stage. the p ...	1984	6324111
characterization of highly and moderately repetitive 500 bp eco ri fragments from xenopus laevis dna.	three different types of repetitive eco ri fragments, which comigrate within a visible band of approximately 500 bp at gel electrophoresis of xenopus laevis dna eco ri digests have been cloned and sequenced. these sequences are designated as repetitive eco ri monomers: rem 1, rem 2 and rem 3. the sequences contain direct repeats, inverted repeats and palindromic elements. genomic organization of the most abundant sequence (rem 1; 0.4% of total dna) is that of an interspersed sequence. rem 2 (0.0 ...	1984	6330690
calcium sequestering activities of reticulum vesicles from xenopus laevis oocytes.	membrane vesicles isolated from xenopus laevis full-grown stage vi and mature oocytes accumulate 45ca in the presence of atp and oxalate. the ca2+-pumping activity measured in vitro does not appear to be modified during meiotic maturation; it is not affected by the complex ca2+-calmodulin. preliminary experiments have shown that the addition of na+ (30 mm) rapidly discharges accumulated 45ca into oocyte vesicles indicating that a na+/ca2+ exchange system occurs in this membrane fraction. during ...	1984	6238836
multiple ubiquitin mrnas during xenopus laevis development contain tandem repeats of the 76 amino acid coding sequence.	a cdna clone, pxlgc20, was isolated from a library constructed from poly(a)+ rna from stage 10 x. laevis gastrulae. this sequence hybridizes with up to nine different rna species ranging in size from 1600 to 3500 nucleotides, regularly spaced at intervals of about 230 nucleotides. clone pxlgc20 contains two complete repeats of a 228 bp sequence as well as part of a third repeat, all adjacent and in the same orientation. one possible translational reading frame in pxlgc20 completely spans the rep ...	1984	6209017
lectins and substitution for helper function in anti-hapten responses in xenopus laevis.	substitution by lectins for the carrier-priming requirement in thymus-dependent, antigen-binding responses in xenopus laevis has been examined. concanavalin a (con a) was found to substitute for carrier priming in control, early-thymectomized and adult-thymectomized animals, but not in animals given a single, high dose of n-methyl-n-nitrosourea, which has a permanent effect on certain thymus-dependent functions in this species. lipopolysaccharide and other lectins, such as peanut agglutinin and ...	1984	6235180
[expression of hepatitis b virus (hbv) genome in the oocytes of two species of amphibians].	xenopus laevis and pleurodeles waltlii oocyte nuclei are injected with a recombinant plasmid pcp 10, carrying two hepatitis b virus (hbv) genomes in a tandem arrangement. transcription occurs in oocytes of both species and production of viral rnas is demonstrated; better quantitative results are obtained with p. waltlii oocytes. two viral proteins are detected: hepatitis b surface antigen (ag hbs) and hepatitis b core antigen (ag hbc). these proteins can be shown only in oocyte homogenates, and ...	1984	6235876
localization of soluble endogenous lectins and their ligands at specific extracellular sites.	soluble lectins of chicken, rat, frog, and the cellular slime mold, dictyostelium discoideum, were purified and specific antibodies raised against these proteins were used to immunohistochemically localize the lectins in and around the tissues in which they were synthesized. within cells, some of these soluble lectins (chicken-lactose-lectin-ii in intestinal goblet cells, discoidin ii in prespore cells) appear to be concentrated within vesicles whereas others (e.g., rat beta-galactoside lectin i ...	1984	6240298
cell surface expression of murine, rat, and human fc receptors by xenopus oocytes.	we report that xenopus laevis oocytes can efficiently translate and insert heterologous membrane receptors into the oocyte plasma membrane, where they can be detected by the binding of either monoclonal antibodies or ligands. thus, oocytes injected with mrna from the mouse j774 macrophage-like cell line, the rat rbl-1 basophilic leukemia, and the u937 promonocyte cell line, bound 2.4g2 fab, rat ige, and mouse igg2a, respectively. the increase in the high avidity fc gamma r observed after gamma-i ...	1984	6236275
small nuclear u-ribonucleoproteins in xenopus laevis development. uncoupled accumulation of the protein and rna components.	the accumulation of protein and rna components of small nuclear u-ribonucleoprotein particles is non-co-ordinate during oogenesis and early embryogenesis in xenopus laevis. northern blot hybridization of a cloned xenopus u2-rna gene to oocyte and embryo rnas demonstrates that the amount of small nuclear u2-rna per oocyte reaches a plateau early in oogenesis (at the start of yolk deposition); further accumulation is not observed in oogenesis, nor in embryogenesis until the late blastula stage. in ...	1984	6208365
topography of the retinal ganglion cell layer of xenopus.	cell distribution in the retinal ganglion cell layer of xenopus laevis was studied by electron microscopy and the retinal wholemount method. unlike the familiar stratification of the retina, the ganglion cell perikarya and their axons were localised in the same layer, but strictly segregated in alternate rows converging in a radial pattern on the optic disc. rows of perikarya (retinal cords) were two to ten cells wide and clearly defined for a little more than half the distance between the optic ...	1984	6206043
differential expression of multiple u1 small nuclear rnas in oocytes and embryos of xenopus laevis.	the small nuclear rna, u1, is a highly conserved, 165 nucleotide long rna which has been implicated in the processing of mrna precursors. we present evidence that in the amphibian x. laevis there exist at least seven species of u1 rna, which differ in sequence but not in length. strikingly, these rnas are not coordinately expressed. two of the u1 rnas are the predominant u1 species transcribed in the late blastula-early gastrula stages of xenopus embryogenesis. these two rnas, designated xu1a an ...	1984	6207932
alu sequences are processed 7sl rna genes.	7sl rna is an abundant cytoplasmic rna which functions in protein secretion as a component of the signal recognition particle. alu sequences are the most abundant family of human and rodent middle repetitive dna sequences (reviewed in ref. 2). the primary structure of human 7sl rna consists of an alu sequence interrupted by a 155-base pair (bp) sequence that is unique to 7sl rna. in order to obtain information about the evolution of the alu domain of 7sl rna, we have determined the nucleotide se ...	1984	6209580
transcription of a long, interspersed, highly repeated dna element in xenopus laevis.	we have analyzed the transcription of 1723, a long, repeated dna element that is interspersed in the genome of xenopus laevis (b. k. kay and i. b. dawid (1983) j. mol. biol. 170, 583-596). we have detected rna homologous to 1723 in total cellular rna from ovaries, embryos, liver, and cultured kidney cells. transcripts from both strands of the element are present at similar concentrations in these different rna preparations. in oocytes, approximately 100 pairs of lampbrush chromosome loops are ac ...	1984	6207063
altered levels of a 5 s gene-specific transcription factor (tfiiia) during oogenesis and embryonic development of xenopus laevis.	xenopus laevis oocytes contain a 38,000-da protein which serves both as a 5 s gene-specific transcription initiation factor (tfiiia) and to stabilize 5 s rna in ribonucleoprotein complexes. using an antibody to this protein we have measured the levels of tfiiia during oogenesis and embryonic development in x. laevis. the maximal steady state level (approximately 10(12) molecules/oocyte) is reached early in oogenesis but drops 10- to 20-fold in later stages and another 10- to 20-fold during ovula ...	1984	6206067
the histone h5 variant in xenopus laevis.	the presumptive histone h5 of xenopus laevis has been characterized by sds and acid-urea-triton polyacrylamide gel electrophoresis and compared with chicken histone h5. chicken h5 has a lower electrophoretic mobility compared to that of xenopus h5 in both gel systems. it is shown, using a polyclonal antiserum against chicken h5, that the xenopus histone h5 is immunologically related to chicken histone h5. monoclonal antibodies have been prepared to the xenopus histone types h5 and h1a, that do n ...	1984	6205766
studies on xenopus immunoglobulins using monoclonal antibodies.	monoclonal antibodies raised against xenopus ig recognize antigenic determinants on igm and low mol. wt ig (lmw ig or igy ). on sds-page two forms of mu were distinguished in the supernatant and cell lysate of tunicamycin-treated spleen cell culture. the two bands of v observed in serum appear to be the result of carbohydrate heterogeneity. the light chains resolved into two distinct bands which differed in peptide maps; the more slowly migrating band of light chain was preferentially associated ...	1984	6203031
amino acid sequence of the carboxy-terminal part of an acidic type i cytokeratin of molecular weight 51 000 from xenopus laevis epidermis as predicted from the cdna sequence.	the dna sequence of a clone from a cdna library made from xenopus laevis skin is described. this sequence represents the 3'-terminal end of an mrna which codes for an epidermal cytokeratin polypeptide of mol. wt. 51 000 of the acidic (type i) subfamily as identified by hybridization-selection of mrnas, followed by gel electrophoretic identification of the polypeptides synthesized by translation in vitro. the partial amino acid sequence of the amphibian cytokeratin shows strong similarity to type ...	1984	6204859
a qualitative difference in the interleukin 2 (il-2) requirement of helper and cytotoxic t lymphocytes.	a qualitative difference in the requirement of mouse helper and cytotoxic t lymphocytes for interleukin 2 (il-2) was revealed by offering such cells il-2 synthesized in xenopus laevis oocytes that had been microinjected with messenger rna (mrna) encoding human il-2. while both helper and cytotoxic mouse t-cell lines proliferate in response to the il-2 present in medium conditioned by stimulated human lymphocytes, only helper-t-cell lines respond to human il-2 secreted from oocytes. this result d ...	1984	6236885
the onset of activation responsiveness during maturation coincides with the formation of the cortical endoplasmic reticulum in oocytes of xenopus laevis.	immature, stage vi oocytes of xenopus laevis fail to activate (i.e., to propagate a cortical reaction and elevate a fertilization envelope) when pricked or exposed to a23187. we determined the times during maturation when immature oocytes treated with progesterone in vitro developed the capacity to respond to pricking and to ionophore. responsiveness to ionophore first appears at about 3.5-4.5 hr after progesterone treatment; all oocytes are activated by 8-9 hr after progesterone. the capacity t ...	1984	6421640
[does masui's ca-sensitive cytostatic factor exist in the cytoplasm of mature nonactivated eggs of acipenser stellatus, rana temporaria and xenopus laevis?].	the cytoplasm of mature non-activated and cleaving eggs of a. stellatus and r. temporaria had no cytostatic effect. the cytoplasm treated with egta, being injected in one of two blastomeres of the cleaving egg of the same species, inhibits fully or partially the cleavage. the nuclei in the "arrested" blastomeres had, however, vesicular structure but were not blocked at metaphase, as could be expected if the cleavage was inhibited by a cytostatic factor described by masui (1974). the portion of p ...	1984	6422374
in vitro thymus suppression of hemagglutinin production in xenopus laevis: location, drug and temperature sensitivity.	suppression of splenic hemagglutinin (ha) production by allothymuses in vitro was further studied in xenopus laevis, the south african clawed toad. since thymic capacity to suppress splenic ha secretion into the culture medium is retained in animals previously exposed to n-methyl-n-nitrosourea (nmu), which destroys the thymus cortex in this species, suppressor function must be located in the thymus medulla. reciprocal thymus-spleen combinations showed that normal thymus can suppress immunised sp ...	1984	6464095
biosynthesis of thyrotropin releasing hormone in the skin of xenopus laevis: partial sequence of the precursor deduced from cloned cdna.	skin of xenopus laevis contains relatively large quantities of thyrotropin releasing hormone (trh). total mrna isolated from skin was cloned in the plasmid puc8. among 1400 cdna clones, one was found with an insert of 478 nucleotides coding for the amino-terminal part of prepro-trh. this clone was detected using a mixture of two synthetic undecanucleotides for colony hybridization. the single open reading frame starts with a methionine residue and a stretch of hydrophobic amino acids, as is typi ...	1984	6425056
cell cycle dynamics of an m-phase-specific cytoplasmic factor in xenopus laevis oocytes and eggs.	we have examined the regulation of maturation-promoting factor (mpf) activity in the mitotic and meiotic cell cycles of xenopus laevis eggs and oocytes. to this end, we developed a method for the small scale extraction of eggs and oocytes and measured mpf activity in extracts by a dilution end point assay. we find that in oocytes, mpf activity appears before germinal vesicle breakdown and then disappears rapidly at the end of the first meiotic cycle. in the second meiotic cycle, mpf reappears be ...	1984	6425302
effects of ca2+ ions on the formation of metaphase chromosomes and sperm pronuclei in cell-free preparations from unactivated rana pipiens eggs.	nuclei transplanted into unactivated amphibian eggs are known to condense into metaphase chromosomes whereas those transplanted into activated eggs decondense and enlarge. we have made cell-free cytoplasmic preparations from rana pipiens eggs which can induce demembranated xenopus laevis sperm to undergo changes similar to those seen in intact eggs. sperm chromatin which is incubated for 3 hr in unactivated egg preparations made using a buffer containing 3 mm egta is induced to form metaphase ch ...	1984	6427039
calcium ultrastructural localization in xenopus laevis eggs following activation by pricking or by calcium ionophore a 23187.	in the egg of xenopus laevis a cortical network of smooth endoplasmic reticulum (ser) surrounds and interconnects each cortical granule (cg) (campanella and andreuccetti, '77). this network is a possible intracellular site of calcium storage to be called into action for cg exocytosis. in our experiments, xenopus eggs, unfertilized or activated by pricking or by calcium ionophore a 23187, have been fixed in osmium-pyroantimonate for calcium localization. our data show that deposits can be detecte ...	1984	6429269
variations in transcriptional activity of rdna spacer promoters.	we have compared the dna sequences of several different examples of the duplicated polymerase i promoters that are found in rdna spacers of xenopus laevis. although different spacers exhibit different amounts of transcription in vivo, this does not seem to be due to dna sequence differences between spacer promoters. we have found that several different spacer promoters when subcloned and injected into oocytes exhibit similar promoter activities when transcription is assayed by primer extension a ...	1984	6473101
fidelity of transcription of xenopus laevis globin genes injected into xenopus laevis oocytes and unfertilized eggs.	the xenopus laevis alpha 1- and beta 1-globin genes were injected into oocytes and unfertilized eggs of x. laevis. in oocytes, the injected globin genes were actively transcribed, but the majority of the transcripts were incorrectly initiated. in unfertilized eggs, the injected genes were transcribed at a low level but only from the correct start sites. in oocytes, the injected circular plasmid dna containing the cloned globin genes persisted but did not replicate. in contrast, dna injected into ...	1984	6438494
assessment of mutagenic damage by monofunctional alkylating agents and gamma radiation in haploid and diploid frogs, xenopus laevis.	adult male south african clawed frogs, xenopus laevis, were mutagenized by 3-day immersion in aqueous solutions of ethyl methanesulfonate (ems), diethyl nitrosamine (den), or ethyl nitrosourea (enu), or by acute exposure to gamma radiation. they were then spawned repeatedly at 2-week intervals with untreated females, and embryonic survival of the progeny was used to assess genetic damage. recessive lethal effects were assessed from reduced survival of androgenetic haploid progeny. neither recess ...	1984	6479115
oocyte adenylyl cyclase contains ni, yet the guanine nucleotide-dependent inhibition by progesterone is not sensitive to pertussis toxin.	membranes were obtained from xenopus laevis oocytes after removal of follicular cells by collagenase treatment. [32p]adp-ribosylation with pertussis toxin showed them to contain a single mr = 40000 substrate for this toxin that co-migrates on sodium dodecylsufate-polyacrylamide gel electrophoresis with pure human erythrocyte ni, the inhibitory regulatory component of adenylyl cyclase. [32p]adp-ribosylation of oocyte membranes with cholera toxin also showed presence of a single substrate but of m ...	1984	6434346
distribution and utilization of 5 s-rna-binding proteins during the development of xenopus oocytes.	at early stages of oogenesis in xenopus laevis most of the ribosomal 5s rna is complexed with three proteins to form two types of cytoplasmic rnp storage particle. a particle sedimenting at 42s contains 5s rna and trna together with two proteins of mr 48000 (p48) and mr 43000 (p43) and a second particle sedimenting at 7s contains 5s rna plus a protein of mr 40000 (p40, also known as the transcription factor, tfiiia). in this report we use antibodies monospecific for each protein to follow the mo ...	1984	6436024
does the guanine nucleotide regulatory protein ni mediate progesterone inhibition of xenopus oocyte adenylate cyclase?	in xenopus laevis oocytes progesterone is able to inhibit directly the plasma membrane adenylate cyclase activity and induce reinitiation of meiotic maturation. to determine whether progesterone inhibition is mediated by the inhibitory guanine nucleotide-binding regulatory component of adenylate cyclase, ni, the effect of the bordetella pertussis toxin (iap) and limited proteolysis on progesterone action in oocytes was investigated. treatment of oocyte membranes with islet activating protein (ia ...	1984	6439557
the structure of cytoplasm in directly frozen cultured cells. i. filamentous meshworks and the cytoplasmic ground substance.	cultured fibroblasts or epithelial cells derived from xenopus laevis embryos were directly frozen, freeze-substituted by an improved method, and then either critical-point-dried and viewed as whole mounts, or embedded and thin sectioned. in thin regions of these cells, where ice crystal artifacts are absent, the cytoplasm consisted of a dense, highly interconnected meshwork of filaments, embedded in a finely granular ground substance. the meshwork in directly frozen, intact cells was compared wi ...	1984	6436253
fly and frog homoeo domains show homologies with yeast mating type regulatory proteins.	homoeotic genes in the bithorax and antennapedia complexes of drosophila melanogaster appear to specify the developmental fate of segments of the fly. some of these genes (ultrabithorax, antennapedia and fushi tarazu) share homology due to their conservation of a 'homoeo domain'1,2 consisting of 60 amino acids. cross-hybridization and cloning experiments show that the homoeo domain is conserved in a frog (xenopus laevis) gene expressed in early development and may also be present in earthworm, b ...	1984	6429549
variations in aldosterone and corticosterone plasma levels during metamorphosis in xenopus laevis tadpoles.	aldosterone and corticosterone plasma levels have been determined by radioimmunoassay at various stages (st) of metamorphosis in xenopus laevis tadpoles. the aldo level first showed a significant peak at the beginning of the climax (st 58), and again at the middle of the climax (st 61-62); b level increased slightly but significantly at st 59, then showed an important peak at st 62-63. the high levels of these hormones at these stages seem to be associated with the concomitant surge of interrena ...	1984	6489739