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[effects of cyclic amp treatment on the migration of primordial germ cells in the embryo of xenopus laevis].after a treatment of early embryos by ampc, only 40% of the primordial germ cells are found in the gonads; the others are found in the dorsal mesentery and especially in the intestinal wall.1978226281
two cell-free systems constructed from xenopus laevis oocytes: generalized genetic recombination; dna supercoiling. 1979225119
eukaryotic dna replication: the first steps toward a multienzyme system from xenopus laevis. 1979225118
morphological and physiological aspects of melanophores in primary culture from tadpoles of xenopus laevis.melanophores from tadpoles of xenopus laevis (daudin) were isolated by digestion of tail fins with acetyltrypsin and collagenase and maintained in primary culture for 6 weeks up to 3 months. within 36 to 72 h the melanophores develop one to eight dendritic processes per cell; secondary and tertiary branchings of the processes were frequently observed. the melanophores in primary culture disperse under the influence of alpha-msh or cyclic amp; upon rinsing out these substances the cells aggregate ...1979223762
mitochondrial dna polymerase from xenopus laevis oocytes. 1979223552
dual innervation of end-plate sites and its consequences for neuromuscular transmission in muscles of adult xenopus laevis.1. electrophysiological study of dually innervated end-plate sites was carried out in xenopus laevis pectoral muscle fibres. end-plate potentials (e.p.p.s) and miniature end-plate potentials (m.e.p.p.s) have been recorded in mg-blocked preparations. 2. the mean quantal content (m) of each e.p.p. at dually innervated end-plates was significantly smaller than the corresponding values obtained at singly innervated ones. at a given doubly innervated end-plate site the values of m tended to be invers ...1979222897
the role of the carbohydrate in the stabilization, processing, and packaging of the glycosylated adrenocorticotropin-endorphin common precursor in toad pituitaries.the neurointermediate lobes of dark adapted toads, xenopus laevis, were incubated for 30 min in [3h]arginine, [3h]arginine plus [14c]glucosamine, or [3h]glucosamine and then chased for various time periods ranging from 1--3 h. the labeled polypeptides synthesized and secreted by the lobes were analyzed by acid-urea polyacrylamide gel electrophoresis. a glycosylated acth-endorphin precursor (32,000 mol wt) was synthesized during the pulse and identified by immunoprecipitation by acth-(11--24) ant ...1979222574
follicle-stimulating-hormone receptors in the testis of the frog, xenopus laevis. 1979221307
histone 1 phosphotransferase activities during the maturation of oocytes of xenopus laevis. 1979220911
translation of avian sarcoma virus rna in xenopus laevis oocytes. 1979218572
biochemical data on subtotally hypophysectomized xenopus laevis (daudin) adult specimens treated or not with prolactin.xenopus laevis (daudin) adult specimens were submitted to hypophysectomy. although the operation resulted subtotal, it served the purpose of removing the prolactin-producing cells, whereby the involvement of endogenous prolactin in osmoregulation phenomena was excluded. in the operated animals treated with ovine prolactin the following metabolic parameters, which are closely dependent upon interrenal activity, were estimated: 1) intestine alkaline phosphomonoesterase activity (e.c. 3.1.3.1); 2) ...1976218525
effects of fasting and cortisol administration on carbohydrate metabolism in xenopus laevis daudin. 1978217800
dna supercoiling by xenopus laevis oocyte extracts: requirement for a nuclear factor.a purified system is described for the introduction of negative supercoils into simian virus 40 dna. the system consists of histones h2a, h2b, h3, and h4, dna-relaxing enzyme, and a purified factor from xenopus laevis stage 6 oocyte nuclei. the nuclei are prepared en masse by the technique of f. scalenghe, m. buscaglia, c. steinheil, and m. crippa [(1978) chromosoma 60, 299-308]. the supercoiled simian virus 40 dna prepared by this method is indistinguishable from simian virus 40 supercoiled dna ...1978217004
[properties of sex steroid-binding protein from xenopus laevis blood serum and detection of an estradiol-binding component in frog liver cytosol which differs from sex steroid-binding protein].binding and physico-chemical properties of sex steroid-binding protein (sbp) from blood serum and those of estrogen-binding components from liver cytosol of pubertal male and female species of clawed frog xenopus laevis were studied. it was shown that sbp from both sex species of x. laevis specifically binds estradiol (e2) (ka=5 . 10(6) m-1). concentration of sbp binding sites for e2 is 7 . 10(-12) mole per mg of protein. testosterone 5alpha-dihydrotestosterone and e2 effectively compete with [3 ...1978216428
progesterone-induced meiosis in xenopus laevis oocytes: a role for camp at the "maturation-promoting factor" level.cholera toxin inhibition of progesterone-induced meiosis of xenopus laevis oocytes in vitro has been correlated with increased camp levels. inhibition of germinal vesicle breakdown (gvbd) and camp increase occurred after a lag period of 2 hr, when cholera toxin was injected, or 4--5 hr, when applied externally. the ability of the maturation-promoting factor (mpf) to provoke gvbd when injected into recipient oocytes was found to be dependent upon whether the oocytes had been exposed to cholera to ...1978215320
translation of type c viral rnas in xenopus laevis oocytes: evidence that the 120,000-molecular-weight polyprotein expressed in abelson leukemia virus-transformed cells is virus coded.the genomic rna of abelson leukemia virus (ablv) has been purified and translated in xenopus laevis oocytes. the primary ablv-specific protein synthesized is a polyprotein corresponding in molecular weight and immunological properties to a previously described p15 and p12 containing 110,000- to 130,000-molecular-weight polyprotein expressed in ablv-transformed cells. in contrast, translation of woolly monkey sarcoma virus genomic rna resulted in symthesis of a 55,000-molecular-weight polyprotein ...1978214586
discussion paper: induction by progesterone and a "maturation-promoting factor" of soluble proteins in xenopus laevis oocytes in vitro.in vitro incubation of isolated x. laevis oocytes with progesterone induces the specific labeling of proteins during maturation. they are detected as several discrete peaks with a double-labeling technique that involves the injection of [3h] leucine into hormone-treated and [14c] leucine into control cells. the peaks are separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. identical proteins are obtained with two other steroids that provoke maturation and with p-chloromercurib ...1977214005
stimulation of poly(adenosine diphosphate ribose) synthase activity of xenopus germinal vesicle by progesterone.a practical procedure for the isolation of massive numbers of gv from oocytes of xenopus laevis at various stages of oogenesis was developed. the method is simple, rapid, and easy to perform. the isolated gv possess high activity of poly(adp-ribose) synthase. incubation of class-a oocytes (stages v and vi) with progesterone resulted in a stimulation of the poly(adp-ribose) synthase activity in the gv. the stimulation of enzymatic activity occurred prior to gvbd. this stimulatory effect of proges ...1977214004
cap analogues do not inhibit mrna translation in xenopus laevis oocytes. 1978212317
a biochemical comparison of xenopus laevis and mammalian myelin from the central and peripheral nervous systems.myelin purified from the central nervous system of xenopus laevis contained the same major lipid and protein components as human myelin. however, some minor differences in the myelin proteins were noted. the xenopus basic protein had a higher apparent mol wt. on sodium dodecyl sulfate gels than the corresponding mammalian protein. the absolute specific activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase in the xenopus myelin was considerably higher than in mammals. there were differences in ...1978211203
cytochrome oxidase activity of mitochondria in xenopus laevis previtellogenic oocytes. 1978211159
the effects of alpha and beta adrenergic agents on spleen cell antigen binding in four amphibian species.adults of two urodele amphibian species (triturus cristatus carnifex and cynops hongkongensis) and two anuran species (rana temporaria and xenopus laevis laevis) were immunized with a 25% suspension of sheep or horse erythrocytes. after eight or 14 days, splenic lymphocytes were removed, and their specific red cell-binding capacities tested by immunocytoadherence. antigen-binding cells were classified as high-dose nonsecretory (s-) or secretory (s+), according to whether they bound a single laye ...1978211039
high affinity of carozolol for beta-adrenoceptors coupled to the adenylyl cyclase in ventricular myocardium of kitten and xenopus laevis.catecholamine-induced stimulation of adenylyl cyclase in ventricular membranes of kitten and xenopus laevis was antagonized competitively by carazolol. apparent equilibrium constants ranging between 100-170 pm were estimated for the beta-adrenoceptor-carazolol complex.1978210404
chromatin assembly and transcription in eggs and oocytes of xenopus laevis. 1978209936
embryopathies due to spermatozoal impairment in xenopus laevis.an in vitro test system, involving gametes of xenopus laevis has been used to study the effect of antifertility agents upon spermatozoa as manifest in developing embryos. exposure to either the isomeric forms of dimethylmyleran, methyl methanesulphonate or gamma-radiation led to development of a range of embryopathies, whereas treatment with steroidal drugs or the rodent epididymal chemosterilants alpha-chlorohydrin and trimethylphosphate was compatible with production of apparently normal offsp ...1978209323
method for the preparation of active maturation promoting factor (mpf) from in vitro matured oocytes of xenopus laevis.a method for the large scale extraction of maturation promoting factor (mpf) from in vitro matured oocytes of xenopus laevis is described. mpf has been previously described only as a component(s) of hormone-matured cytoplasm within amphibian oocytes (or eggs) which is able to induce the reinitiation of the meiotic process from late diplotene stage until second metaphase arrest, when microinjected into diplotene arrested (fully grown) recipient oocytes. standard biochemical methods for the extrac ...1978207616
control of msh synthesis and release in the aquatic toad, xenopus laevis. 1977207601
amphibian oocyte maturation and protein synthesis: related inhibition by cyclic amp, theophylline, and papaverine.two inhibitors of cyclic amp phosphodiesterase (3':5'-cyclic-amp 5'-nucleotidohydrolase, ec 3.1.4.17), theophylline and papaverine, inhibit the maturation of xenopus laevis oocytes induced by four different stimuli: human chorionic gonadotropin, progesterone, testosterone, and lanthanum ions. addition of 1 mm cyclic amp to the medium delays maturation by approximately 2 hr. papaverine, theophylline, and cyclic amp inhibit amino acid incorporation into oocyte proteins by 50% or more but do not in ...1978206889
the activity of some intracellular oxidative enzymes in the thyroid follicular epithelium of xenopus laevis daud. in experimental long-term hypokinesia.histoenzymological methods were applied to examine the activities of previously little studied intracellular oxidative enzymes in the cells of the thyroid follicular epithelium of xenopus laevis daud. specimens kept in aquarium. succinate, lactate, alpha-glycerophosphate, glucose-6-phosphate and reduced nad and nadp dehydrogenases and cytochrome oxidase were studied. in comparison with other chordate species a very strong activity was revealed particularly by lactate dehydrogenase. the data obta ...1977202546
formation of branched dna structures by xenopus laevis oocyte extract. 1977201869
frog oocytes synthesize and completely process the precursor polypeptide to virion structural proteins after microinjection of avian myeloblastosis virus rna.after microinjection of xenopus laevis oocytes with rna from avian myeloblastosis virus, viral structural proteins p27, p19, p15, and p12 are formed by a sequence of posttranslational cleavages of a high-molecular-weight precursor polypeptide. the 60-70s rna aggregate or its 30-40s rna subunits obtained by heat or formamide treatment possess the same ability to serve as template in x. laevis oocytes. the processing pattern of virus-specific precursor polypeptides is the same in x. laevis oocytes ...1977198776
the activity of poly(adenosine diphosphate ribose) polymerase during the embryonic development of the south african clawed toad xenopus laevis [proceedings]. 1977198268
coupled transcription-translation of dna injected into xenopus oocytes.a previous report from this laboratory showed that purified dnas are transcribed after injection into the nucleus of xenopus laevis oocytes (mertz and gurdon, 1977). here we demonstrate that at least some of the rna synthesized is translated within these injected cells to produce the correct protein products. injection of simian virus 40 dna into oocytes induces the synthesis of at least two proteins not normally synthesized in these cells. using two-dimensional polyacrylamide gel electrophoresi ...1977198138
kynureninase-type enzymes and the evolution of the aerobic tryptophan-to-nicotinamide adenine dinucleotide pathway.kynureninase-type (l-kynurenine hydrolase, ec 3.7.1.3) activity has been found to be present in the livers of fish, amphibia, reptiles, and birds. in addition to past information concerning this enzyme activity in mammalian liver, it is now clear that all the major classes of vertebrates carry a highly specialized kynureninase-type enzyme, which we have termed a hydroxykynureninase. to compare the reactivities of these enzymes with l-kynurenine and l-3-hydroxykynurenine, ratios of tau values (km ...1977195620
developmental immunohistology of melanotrophs in xenopus laevis tadpoles.the adenohypophysial primordium of xenopus laevis tadpoles at stages 33/34 to 46 (nieuwkoop and faber, 1956) were examined immunohistologically for alpha-msh, beta-msh and acth. beta-msh was demonstrated from stage 37/38 onwards, and alpha-msh from stage 39. no signs of acth production were detected. alpha-msh and beta-msh occurred in the same cells. no differences were found in the intensity of immunofluorescence between tadpoles which were kept on a black and a white background. the present st ...1977194700
cyclic gmp accumulation causes degeneration of photoreceptor cells: simulation of an inherited disease.guanosine 3',5'-monophosphate (cyclic gmp) metabolism in developing eye rudiments of xenopus laevis embryos in culture is disrupted by the phosphodiesterase inhibitor isobutylmethylxanthine. at low concentrations of inhibitor the rudiments develop normally, but at higher concentrations of the inhibitor, cyclic gmp accumulates in the rudiments and the retinal photoreceptor cells degenerate selectively. the isobutylmethylxanthine-induced photoreceptor degeneration is associated with an accumulatio ...1977193183
purified dnas are transcribed after microinjection into xenopus oocytes.the possibility of using dna-injected xenopus laevis oocytes and eggs for studying the control of transcription in eukaryotes has been investigated. when purified dna of simian virus 40 (sv40) is injected into xenopus laevis oocytes, tritiated rna precursors are incorporated into dnase-i-resistant, rnase-a- and alkali-sensitive material that hybridizes specifically to sv40 dna. this viral transcription continues for at least 5 days and occurs only when the injected dna is directed to the nucleus ...1977193103
assembly of sv40 chromatin in a cell-free system from xenopus eggs.a cell-free system is described which assembles chromatin from purified dna in 1 hr under physiological incubation conditions. it consists of a 145,000 x g (maximum) supernatant fraction from eggs of xenopus laevis. it converts sv40 dna to a nucleoprotein which co-sediments with naturally occurring sv40 chromatin and which can be cleaved by micrococcal nuclease to a highly ordered pattern of dna fragments resembling those from digestion of liver chromatin. it inserts superhelical turns into rela ...1977189936
the structure of the mitochondrial cloud of xenopus laevis oocytes.the ultrastructure of the mitochondrial cloud (balbiani body) of the pre-vitellogenic oocytes of xenopus laevis has been examined using transmission and stereoscan electron microscopy. examination of conventional thin sections confirm previous observations which suggest that the cloud consists essentially of many thousands mitochondria and numerous small vesicles; larger clouds, in oocytes greater than 200 mum in diameter, contain relatively more vesicles. using a standard electron microscope at ...1976188969
dna-relaxing activity and endonuclease activity in xenopus laevis oocytes.complex simian virus 40 dna produced by a soluble cell-free extract derived from stage 6 oocytes of xenopus laevis consists of fully relaxed circles (i.e., with no superhelical turns). an endonuclease and a dna-relaxing protein, either or both of which could be responsible for the relaxation of the complex dna, have been purified from the extract. the endonuclease(s) produces nicked circles (having a single-strand scission) and linear full-size molecules. the dna-relaxing protein is in the nucle ...1976188045
synthesis of the mitochondrial inner membrane in cultured xenopus laevis oocytes.the purpose of this study was to investigate the contribution of mitochondrial and cytoplasmic protein synthesis to the biogenesis of cytochrome oxidase (ferrocytochrome c:oxygen oxidoreductase ec 1.9.3.1) and rutamycin-sensitive adenosine triphosphatase (atp phosphohydrolase ec 3.6.1.3) in cultured oocytes of the toad, xenopus laevis. x. laevis cytochrome oxidase was purified over 23-fold with respect to specific activity and over 29-fold with respect to specific heme a content from oocyte subm ...1976184093
[extra- and intra-mitochondrial distribution of respiratory enzymes in oocytes of xenopus laevis]. 1975183439
[enzymatic aspects of the mitochondria of xenopus laevis oocytes]. 1975183438
the stimulatory effect of hypothalamic and mesencephalic tissue on the interrenal of tadpoles of xenopus laevis daudin. 1976182611
morphological and biochemical changes in the hepatic endoplasmic reticulum and golgi apparatus of male xenopus laevis after induction of egg-yolk protein synthesis by oestradiol-17 beta.this report describes morphological and biochemical changes accompanying oestrogen induced synthesis of the egg-yolk protein precursor, vitellogenin, in male xenopus liver. extensive proliferation of the rough and smooth endoplasmic reticulum and the golgi apparatus occurs between 3 and 9 days after administration of oestradiol-17 beta. subcellular fractionation showed that microsomal fractions have an increased number of ribosomes available for protein synthesis, hormone treatment enhances the ...1976181282
[meiosis: role of a histone kinase in the condensation of ovarian oocyte chromosomes of xenopus laevis and ambystoma mexicanum].by injecting heterologous histone-kinase preparations into ovarian axolotl oocytes, it has been possible to speed up the progesterone-induced process of chromosome condensation. moreover, in some instances, this condensation and even complete maturation have been obtained after injection of protein kinase alone, thus in the absence of hormone stimulation. two different histone kinase preparations have been used: one was prepared from ascites cell chromatin and the other from in vitro ovulated xe ...1975177222
translation of oncogenic virus rna in xenopus laevis oocytes. 1976175294
effect of xenopus laevis oocyte extract on supercoiled simian virus 40 dna: formation of complex dna.a soluble cell-free extract derived from stage 6 xenopus laevis oocytes is described. from supercoiled simian virus 40 dna the extract produces nicked circles (having a single-strand scission), linear molecules of full unit size, shorter length fragments, and various forms of complex dna.1976174111
translation of messenger ribonucleic acid from isolated pancreatic islets and human insulinomas.rna preparations from isolated rat pancreatic islets and from human insulinomas were injected into oocytes of xenopus laevis which were then incubated with [3h]leucine. acid-ethanol extracts of the oocytes were immunoprecipitated with anti-insulin serum using the double antibody technique. sodium dodecyl sulfate disc gel electrophoresis of the immunoprecipitates showed the presence of an insulin-displaceable immunoreactive material with a molecular weight of about 18,000 in extracts from oocytes ...1975174093
changes in the content of cyclic amp and cyclic gmp during the development of xenopus laevis. 1975172338
ultrastructural and pharmacological studies on the afferent synapse of lateral-line sensory cells of the african clawed toad, xenopus laevis.lateral-line sensory cells of xenopus show considerable similarity to central nervous system synapses in their responses to the zinc iodide-osmium tetroxide, and bismuth-iodide cytochemical staining techniques. both reserpine and fla-63 cause a reduction in the diameter and electron density of the synaptic bars, and a dramatic loss of synaptic vesicles surrounding the bars. aminooxy acetic acid and 3-mercaptopropionic acid cause no significant changes in the sensory-cell afferent synaptic appara ...1975171077
light-induced formation of dense-core vesicles in rod photoreceptors in retina of xenopus laevis. 1975170537
mechanism of action of progesterone on amphibian oocytes. uptake and metabolism of progesterone by isolated oocytes of pleurodeles waltlii and xenopus laevis. 1975170033
inhibitor induced alterations of chromatoid bodies in male germ line cells of xenopus laevis.the action of inhibitors of protein synthesis on the structure of cytoplasmic inclusions found in the male germ cell line of the anuran, xenopus laevis, has been studied by light and electron microscopy. results indicate that one such inclusion, the chromatoid body, is sensitive to treatment with either chloramphenicol or puromycin. these drugs administered in vivo or in vitro cause up to a thirty-fold increase in the volume of the chromatoid body in all stages where it is normally present. maxi ...1975169993
synthesis and secretion of a large glycoprotein in the pars intermedia.the biosynthesis, intracellular transport and release of [3-h]-leucine-containing secretory product has been followed in the pars intermedia of xenopus laevis and, in particular, the synthesis and secretion of a large molecular weight glycoprotein secretory product was demonstrated. however, if xenopus adrenocorticotrophin does contain a leucine residue the results obtained provided no support for the view that it serves as a precursor for melanocytestimulating hormone in this species.1975168285
[the effects of cortisol and progesterone injected directly into the oocytes of xenopus laevis]. 1975167990
molecular weights of estrogen and androgen binding proteins in the liver of xenopus laevis.[3-h]estradiol-17beta and [3-h]dihydrotestosterone binding proteins in the cytosol fraction of liver from both male and female xenopus laevis were characterized by electrophoresis on polyacrylamide gels. these binding proteins, which were indistinguishable based upon their mobilities on gels of different acrylamide concentrations, migrated as single components with a molecular weight of 2.0 x 10-4. separation of native or sodium dodecyl sulfate denatured specific estrogen-binding components on d ...1975167818
template specificity of the cytoplasmic dna polymerase in xenopus laevis oocytes. 1975167780
studies on the liver of xenopus laevis. i. the ultrastructure of the parenchymal cell.the liver of xenopus laevis was examined with electron microscopy. its structure was found to be markedly different from that of mammals, particularly regarding the morphology of the hepatocytes to be classified as typical. it was established that the main function of such a cell is the storage of glycogen, and further that it possesses only scant organelles and other inclusions. since this type of cell was found most frequently in the liver of untreated animals, it was designated as normal cell ...1975167614
in vitro progesterone binding to xenopus laevis oocytes. 1975166010
response of large oocytes of xenopus laevis to progesterone in vitro in relation to oocyte size and time after previous hcg-induced ovulation. 1975166003
the mucosubstance coating the pneumonocytes in the lungs of xenopus laevis and lacerta viridis.the layer of mucosubstance that is associated with the free surface membranes of the pneumonocytes in the lungs of the toad xenopus laevis and the lizard lacerta viridis was demonstrated by electron microscopy using iron oxide stain. the form and staining reactions of the mucosubstance layer were similar in both animals. in electron micrographs the mucosubstance was represented by a band of densely stained material (25-50 nm thick) which coated the entire free surface of the pneumonocytes. it ap ...1975165163
[the topographical localization of spinal motoneurons of the rat and its numerical alternation in regard to development (author's transl)].the topographical localization of spinal motoneurons innervating the forelimb muscles of the rat and its numerical alternation in regard to development was observed by hrp (horseradish peroxidase) method. hrp method is a histochemical technique to trace the cellular origin of axon terminal net work. when hrp is injected into the muscles, the enzyme is taken up by nerve endings and transported retrogradely by the axoplamic flow to the original cell body, and does not transported hematogenously an ...1979159327
[alterations in concanavalin a binding during retinal development in xenopus laevis].changes in concanavalin a binding were observed in the retina of xenopus laevis throughout development. prior to stage 37, the optic cup and nervous sysetm displayed a light, diffuse staining. abruptly at stage 37, however, intense staining reaction occurred in the ganglionic fibers, both plexiform layers and photoreceptor inner segments, remaining thus throughout larval and adult life. our results suggest that important structural modifications occur in retinal cells at the time of establishmen ...1979158407
a study of the organisation of the ribosomal ribonucleic acid gene cluster of neurospora crassa by means of restriction endonuclease analysis and cloning in bacteriophage lambda.1. total neurospora crassa dna was restricted with endonucleases and fragments carrying rrna coding sequences were identified by hybridization with xenopus laevis ribosomal dna probes. 2. the repeating unit of the rrna gene cluster was found to be 8.6 kbp, arranged in a head-to-tail fashion. 3. digestion with hind iii yielded fragments of 3.4 kbp and 5.2 kbp and both were cloned. 4. digestion with eco ri yielded fragments of 2.2 kbp, 3.0 kbp and 3.4 kbp; the 3.0 kbp fragment was cloned. 5. seque ...1979158122
light and electron microscopic investigation of atpase activity in musculature during anuran tail resorption.the histochemical activity of adenosine triphosphatase (atpase) was studied at light and electron microscopic levels in larval tail musculature of rana catesbeiana and rana ornativentris during late metamorphic stages. the presence of low, moderate or dark reaction of k2-edta-preincubated ca++-atpase was correlated with the variable degree of degeneration of white fibres even at the late stage of tail resorption. the reasons for an increase in this atpase activity in degenerating white muscle fi ...1978153341
the regulation of growth in the mesonephric kidney of adult xenopus laevis by an endogenous inhibitor of proliferation. 1978151645
[effects of alpha-amanitin on the development of xenopus (xenopus laevis daud.) heart in vitro].the differentiation of xenopus heart is studied in vitro, in the presence of alpha-amanitin. the results obtained depend on the concentration of the inhibitor, the length of treatment and the stage of primordium. the mrna pool assures the differentiation of explants, removed from young stages, for 12 hours. this time is half for the primordia removed from stages greater than 3,5 mm.1977143992
[the tail of the tadpole of alytes obstetricans in organ culture with or without the addition of thyroxine. ultrastructural controls].the tail of the alytes obstetricans tadpole, isolated at different stages (end of proclimax and climax), was studied in organ culture. the addition of thyroxine at a concentration of 5.10(-7) induces an involution slower than in vivo. besides, this regression is comparatively slower in similar conditions, than in xenopus laevis. this delay could be explained by the important volume and the very developed musculature of this anuran tail. ultrastructural controls reveal the form of the muscles, th ...1976139991
'immobile' (im), a recessive lethal mutation of xenopus laevis tadpoles.'immobile' (im) is a recessive lethal mutation discovered in the f3 of a xenopus (xenopus laevis laevis) originating from a mesodermal nucleus of a neurula transplanted into an enucleated egg. the im embryos do not contract after mechanical stimulation nor do they present any spontaneous contraction from the neurula stage onwards. development proceeds normally during the first days after which deformation of the lower jaw and tail are observed. the im tadpoles die when normal controls are at the ...1975127824
[invariability of the h-y antigen expression in the heterogametic sex of some amphbians and evidence for sexual dimophrism of the antigen expression in pelodytes punctatus d (amphibia, anura)].the h-y antigen is studied in some amphibians whose sexual genetic constitution is known. thus, in pelurodeles waltlii, ambystoma mexicanum, xenopus laevis and rana ridibunda, the invariability of the h-y antigen expression in the heterogametic, sex is confirmed. in pelodytes punctatus the genetic sex is unknown but the existence of the h-y antigen in phenotypic males leads to the conclusion of a male heterogamety of the xy type.1979121269
measurement of calcium ion concentrations in the lateral line cupulae of xenopus laevis.1. ion selective microelectrodes were used to measure the distribution of ca2+ in the cupulae of xenopus laevis, and to observe the effects of the ca2+ blocker, la3+, and a ca2+ chelating agent (egta) on the endocupular potential and k+ concentration. 2. measurements of the endocupular ca2+ and potential were found to be in the range of 2-30 mum and 55-10 mv respectively, and their relationship indicates that ca2+ is passively distributed in the cupula. 3. the concentration of endocupular k+ and ...1979119824
[teratogenic effect of mercury bichloride on the embryonic development of the amphibian xenopus laevis daud]. 1979116463
[demonstration of a long depolarization in the oocytes of xenopus laevis]. 1979111840
[immunohistochemical identification, in an anuran amphibian (xenopus laevis daud.) of infundibular neurons reacting with antigastrin serum].neurons containing peptides immunocytologically related to gastrin have been revealed by immuno-cytology in the post-chiasmatic hypothalamus of xenopus laevis. their pericarya are localized in the postero-dorsal zone of the pars ventralis of the tuber cinereum; their axons end on the capillaries of the external zone of the median eminence.1979110481
partial mapping of methylated sequences in xenopus laevis ribosomal rna by preparative hybridization to cloned fragments of ribosomal dna.xenopus laevis rrna was hybridised to either of two cloned fragments of ribosomal dna. one fragment, designated x1r11, contains a short region of the 18 s rrna gene and most of the 28 s rrna gene. the other fragment, x1r14, contains a short region of the 28 s gene and most of the 18 s gene. after hybridization the non-complementary rrna was removed by digestion with t1 rnase and the hybridized rna was then eluted and examined by fingerprinting analysis. the 3' terminal sequence and the dimethyl- ...1979108668
characteristics of immunoglobulin synthesized early in the development of xenopus laevis. 1979108156
synthesis and processing of the mouse mopc-321 kappa chain in xenopus laevis oocytes. 1979107859
in vitro studies on the control of myoepithelial cell contraction in the granular glands of xenopus laevis skin. 1978104900
immunoglobulin evolution: chemical study of clawed toad (xenopus laevis) heavy and light chains.nh2 terminal amino acid sequence determinations of clawed toad (xenopus laevis) immunoglobulins indicate that approximately 30% of the heavy chains and less than 5% of the light chains have unblocked nh2 termini. the major amino acid sequence of the x. laevis 7s immunoglobulin heavy chains is the same as that of the 19s immunoglobulin heavy chains. thus in the synthesis of the heavy chains, the vh genes coding for unblocked heavy chains can associate with ch genes of both the 19s and 7s classes. ...1978103971
clustered and interspersed repetitive dna sequences in four amphibian species with different genome size.we have compared the amount of clustered and interspersed repetitive sequences in the genome of four amphibia with different dna contents per haploid nucleus: two anura (xenopus laevis, 3 pg and bufo bufo, 7 pg) and two urodela (triturus cristatus, 23 pg and necturus maculosus, 52 pg). high molecular weight dna of the four species was denatured and reassociated to the same cot in order to obtain duplex sequences with a similar reiteration frequency. single-stranded dna was digested off with the ...1978101246
[histochemistry of the ball cell in larval epidermis of xenopus laevis daudin].presented investigations of chemical composition and metabolism of ball cell in larval epidermis of xenopus point to a regressive shape of cell corresponding to former light and electron microscopical findings. the lower requirements of energy of this cell are covered by glycolysis and possibly by pentose phosphate cycle. our hypothesis of pressure-elastic ball of cell as structural element of larval epidermis could been further supported.197897905
[inhibition by the enterotoxin of vibrio cholerase of meiosis reinitiation of the xenopus laevis oocyte induced in vitro by progesterone].progesterone reinitiates in vitro meiosis in xenopus laevis oocytes. this action of the hormone can be abolished by the exotoxin of vibrio cholerae. the concentration of toxin which inhibits 50% of the progesterone (10 mum) action in about 2.5 pm. binding experiments using 125i labelled toxin demonstrated the existence of high affinity binding sites (kd approximately 0.2 nm) located probably on the surface of the oocytes.197895900
probing the program of gene expression utilized in early development.somatic cell nuclei injected into amphibian oocytes enlarge, exchange protein with the surrounding cytoplasm, and actively synthesize rna for weeks. the message activity of the rnas synthesized within the oocytes can be detected as new proteins made a few days after the injection of somatic nucleic. the oocyte cytoplasm seems to reprogram the injected nuclei, allowing the expression only of those genes which are normally active in oocytes (de robertis and gurdon, 1977). genes which are unexpress ...197995388
isolation and characterization of the nuclear matrix from the male xenopus laevis following estrogen administration: kinetics of [3h] uridine incorporation.at various times following estrogen administration, the nuclear matrix was isolated from the liver of male xenopus laevis by sucrose gradient centrifugation of nuclei treated with a high-salt buffer and dnase i in the presence of a proteolytic inhibitor (pmsc--phenylmethyl sulfonyl chloride). electron micrographs of the nuclear matrix demonstrate a sponge-like network attached to a well-defined inner envelope with a ribosome-free outer envelope. chemical analyses show that the hsb-dnase-treated ...197995125
a detergent-citric acid technique for isolating nuclear and cytoplasmic fractions containing undegraded rna from cells of xenopus laevis. 197994513
[immunohistochemical identification of specific antigens in stained and balsam-embedded eye lens sections].localization of specific proteins at preliminary stained with azan and embedded in balsam sections of amphibian eye lens (rana temporaria, xenopus laevis) was studied by indirect immunofluorescence. the analysis was performed on the lens of intact animals as well as on lens induced in amphibia gastrula ectoderm in vitro. to remove balsam the lens sections were successively washed by xylene, ethanol and saline (ph 7.1). then they were treated according to the general principles of immunohistochem ...197993003
preparation of complementary dna to 5 s ribosomal rna from xenopus laevis. 197991536
the intra-nucleolar localization of amplified rdna in xenopus laevis oocytes.a fluorescent feulgen-stain was adapted in order to demonstrate dna-containing structures inside the amplified nucleoli of xenopus laevis. at all stages of oogenesis this method reveals granules or complex structures of dna in each nucleolus. the micronucleoli which do not stain with this method and which do not reveal an internal structure in low molarity saline, unlike real nucleoli are considered as nucleolus-like bodies. the dna-containing structures in the nucleoli can be composed of one or ...197990588
incorporation of 35s-sulfate into yolk platelets of xenopus laevis embryos. a study using electron microscope autoradiography.inorganic 35s-sulfate was injected into xenopus laevis embryos before first cleavage to study incorporation of the label into the yolk platelets in order to localize glycosaminoglycan synthesis. electron microscope autoradiography of embryonic thin sections from blastulae and gastrulae revealed that the primary site of label incorporation is at the edge of the yolk platelets, and, to a lesser extent, in their interiors. autoradiography of isolated yolk platelets, lacking unit membranes, indicate ...197989978
[immunochemical study of the water-soluble lens proteins in the embryo of xenopus laevis with the mutation of periodic albinism].the crystallins of ap mutants of xenopus laevis have been studied in comparison with those of normal embryos and adults using the complex of immunochemical methods (immunoelectrophoresis, immunodiffusion, immunoadsorption, immunofluorescence, isoelectrofocusing with immunoidentification). the analysis was carried out with antisera to electrophoretic fractions of the mutant lens. 11 organ-specific antigens were found in the lens of both the normal and mutant animals. these proteins are heterogeno ...197988703
translation of bovine leukemia virus virion rnas in heterologous protein-synthesizing systems.bovine leukemia virus 60 to 70s rna was heat denatured, the polyadenylic acid-containing species were separated by velocity sedimentation, and several size classes were translated in a micrococcal nuclease-treated cell-free system from rabbit reticulocytes. the major rna species sedimented at 38s and migrated as a single component of molecular weight 2.95 x 10(6) when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the predominant polypeptides of the in vitro translation o ...197987518
cyclic amp synthesis in xenopus laevis oocytes: inhibition by progesterone.[alpha-32p]atp was microinjected into xenopus oocyte and neosynthesized cyclic amp was isolated. cholera toxin inhibited progesterone-induced maturation and stimulated after 3 h of preincubation the amount of neosynthesized cyclic amp. progesterone decreased the neosynthesis of cyclic amp during the first hour following addition of the hormone.197983880
further studies of the prospective fates of blastomeres at the 32-cell stage of xenopus laevis embryos.each blastomere in the marginal zone of xenopus laevis embryos at the 32-cell stage was stained with nile blue sulphate. only specimens with the typical arrangement of blastomeres of morulae of this species were used, and special care was taken to prevent the dye from spreading to neighbouring cells and to determine the extent of stained areas. the prospective fate of each blastomere was studied and a new fate-map of the 32-cell embryo was drawn by tracing the movement of stain during the course ...197883458
free rna polymerase activities in isolated nuclei from xenopus laevis embryos. stimulation of endogenous template-bound rna polymerase ii activity by poly d(a-t) [proceedings]. 197881029
synthesis of interferon in heterologous cells, cell-free extracts, and xenopus laevis oocytes. 197780829
quinacrine fluorescence of merkel cells in xenopus laevis.it has been shown by electron microscopy that, in xenopus laevis, merkel cells are usually situated near the ducts of the skin glands. cells which fluorescence in ultra-violet light after treatment of the skin with quinacrine can be identified with these merkel cells by their position, shape and size. the method indicates the presence of purine nucleotides, probably atp. this result is consistent with the view that "large opaque vesicles" are sites of atp storage.197879446
the induction of immunologic tolerance with type iii pneumococcal polysaccharide cross-linked or coupled to protein.type iii pneumococcal polysaccharide molecules were linked to one another, i. e. cross-linked. the product was essentially insoluble in saline. large pieces weighing 1-2 mg were inserted into mice. they produced immunologic paralysis or immune tolerance. when placed intraperitoneally in millipore chambers the cross-linked polysaccharide did not have any apparent effect, for the mice were not tolerized. when pneumococcal polysaccharide was linked to a protein, the amount of polysaccharide require ...197879330
progesterone-induced meiotic reinitation in vitro in xenopus laevis oocytes: a role for the displacement of membrane-bound calcium. 197773488
inhibition of the progesterone-dependent induction of meiosis by gammexane in xenopus laevis oocytes. 197771148
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