Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| dna replication in cell-free extracts from xenopus laevis. | 1991 | 1811152 | |
| early embryonic development of xenopus laevis. | 1991 | 1811154 | |
| xenopus laevis: practical uses in cell and molecular biology. solutions and protocols. | 1991 | 1811156 | |
| xenopus laevis: practical uses in cell and molecular biology. injections of oocytes and embryos. | 1991 | 1811157 | |
| mutants of xenopus laevis. | 1991 | 1811158 | |
| codon usage table for xenopus laevis. | 1991 | 1811159 | |
| xenopus laevis: practical uses in cell and molecular biology. pictorial collage of embryonic stages. | 1991 | 1811160 | |
| emigration of bilayered epidermal cell sheets from tadpole tails (xenopus laevis). | migration of bilayered epidermal cell sheets out of explants of tadpole tails (xenopus laevis) were investigated with time-lapse cinemicrography using reflection-contrast optics. cell-sheet formation begins beneath the explant in a region where it is closely attached to the coverslip. a single basal cell extends a lamellipodium through the outer (surface) epidermal layer and starts moving in a direction free of attached cells. this cell remains connected to the following basal cell, which then a ... | 1991 | 1811887 |
| retinoic acid causes abnormal development and segmental patterning of the anterior hindbrain in xenopus embryos. | retinoic acid is a very potent teratogen and has also been implicated as an endogenous developmental signalling molecule in vertebrate embryos. one of the regions of the embryo reliably affected by exogenously applied ra is the hindbrain. in this paper, we describe in detail the hindbrain of xenopus laevis embryos briefly treated with various levels of ra at gastrula stages. such treatments lead to development of embryos with loss of anterior structures. in addition, ra has a general effect on r ... | 1991 | 1811933 |
| notochord morphogenesis in xenopus laevis: simulation of cell behavior underlying tissue convergence and extension. | cell intercalation and cell shape changes drive notochord morphogenesis in the african frog, xenopus laevis. experimental observations show that cells elongate mediolaterally and intercalate between one another, causing the notochord to lengthen and narrow. descriptive observations provide few clues as to the mechanisms that coordinate and drive these cell movements. it is possible that a few rules governing cell behavior could orchestrate the shaping of the entire tissue. we test this hypothesi ... | 1991 | 1811939 |
| ep-cadherin in muscles and epithelia of xenopus laevis embryos. | ep-cadherin is a novel xenopus ca+2-dependent adhesion molecule, which shares comparable homology with mouse e- and p-cadherins (ginsberg, de simone and geiger; 1991, development 111, 315-325). we report here the patterns of expression of this molecule in xenopus laevis embryos at different developmental stages ranging from cleavage to postmetamorphic. ep-cadherin is already expressed in the oocyte and egg and can then be detected in close association with the membrane of all blastomeres up to l ... | 1991 | 1811947 |
| peptide transport across the animal cell plasma membrane: recent developments. | transfer of intact peptides across the plasma membrane of animal cells, especially in the small intestine and the kidney, is a well established phenomenon. this process plays an important role in the maintenance of protein nutrition. evidence is accumulating which suggests that the process may also have a great potential for pharmacological and clinical applications. it is therefore important to understand various aspects of peptide transport such as its function, chemical nature of the transpor ... | 1991 | 1812062 |
| amiloride block of the mechanosensitive cation channel in xenopus oocytes. | 1. patch clamp recording techniques have been used to investigate the block by amiloride of the mechanosensitive cation-selective channel in frog (xenopus laevis) oocytes. 2. cell-attached and outside-out patch recording configurations were employed to study the differences in block produced when amiloride was present at either the extracellular (external) or intracellular (internal) membrane face. 3. external amiloride causes a highly voltage-dependent 'flickery' block of single mechanosensitiv ... | 1991 | 1816379 |
| a recombinant vaccinia virus infects xenopus melanophores. | a recombinant vaccinia virus was employed to demonstrate infection of cultured xenopus laevis melanophores. the recombinant virus contains one copy each of the escherichia coli lac z and human growth hormone genes under the transcriptional control of two separate viral promoters. western blot analysis and in situ staining revealed the dependency of beta-galactosidase production in infected xenopus cells on time and multiplicity of infection (moi). western blot analysis was used to demonstrate th ... | 1991 | 1816550 |
| the genes encoding the major 42s storage particle proteins are expressed in male and female germ cells of xenopus laevis. | as components of the 42s storage particles (thesaurisomes), thesaurin a and thesaurin b are involved in the long-term storage of trna and 5s rna in previtellogenic oocytes of xenopus laevis. thesaurin a and thesaurin b are among the most abundant proteins in previtellogenic oocytes. we show here that the mrnas encoding thesaurin a and thesaurin b are present not only in previtellogenic oocytes but also in pre-meiotic germ cells (oogonia). these mrnas can also be detected in spermatogonia and ear ... | 1991 | 1821854 |
| a potassium current evoked by growth hormone-releasing hormone in follicular oocytes of xenopus laevis. | 1. electrophysiological properties of the growth hormone-releasing hormone (grh) receptor were studied in xenopus oocytes with an intact follicle cell layer (i.e. follicular oocytes) by measuring whole-cell current using the two-electrode voltage-clamp method. 2. a slow transient outward current was elicited in oocytes, clamped at -60 mv, by the application of rat grh but not bovine, porcine, or human grh. 3. the response to grh was not suppressed by blockers known to inhibit other endogenous re ... | 1991 | 1822542 |
| expression of a leukocyte-specific antigen during ontogeny in xenopus laevis. | the monoclonal antibody cl21 recognizes a determinant present on the surface of leukocytes, but not on erythrocytes or nonhemopoietic tissue. the cl21 antigen was first expressed at 48 hr of development at 20 degrees c (stage 28) on embryonic cells cultured from lateral plate mesoderm. based on immunofluorescence staining and flow cytometric analysis, the distribution of fluorescence intensity of larval thymocytes and splenocytes was unimodal. distributions of dull and bright cells were detected ... | 1991 | 1822989 |
| expression of firefly luciferase gene in xenopus laevis oocyte. | fusion plasmid psv-luc20 and psv-luc19 were constructed by using the larger bamhi restricted fragments of plasmid pdo432 containing the firefly luciferase (luc) gene and hindiii-bamhi restricted fragment of plasmid psvk100 containing the sv-40 promoter as insert and vector, respectively. the fusion plasmid had different ligation orientations between the encoding sequence of luc gene and the sv-40 promoter, i.e., they were sense and antisense plasmid. when they were introduced into xenopus oocyte ... | 1991 | 1824240 |
| expression of vasopressin v2 receptor in xenopus laevis oocytes by porcine kidney cell line (llc-pk1) messenger rna. | vasopressin v2 receptor was expressed in xenopus laevis oocytes which were injected with poly(a) +rna from porcine kidney cell line llc-pk1. pharmacological antagonism of the expressed v2 receptor was observed between arginine vasopressin and two potent and selective vasopressin antagonists: [d(ch2)5, d2-phe2 ile4, ala9-nh2]arginine vasopressin and [d(ch2)5,d-ile2, ile4]arginine vasopressin. activation constant for arginine vasopressin concentration was 1.32 x 10(-10)m. the nucleotide length of ... | 1991 | 1824918 |
| cyclin b in xenopus oocytes: implications for the mechanism of pre-mpf activation. | using a polyclonal antibody raised against b2 cyclin from xenopus laevis, we show that prophase-arrested xenopus oocytes contain a stockpile of cyclin b2 protein. during progesterone-induced maturation, an increase in the synthesis of cyclin b2 is observed, although western blotting experiments show that this new synthesis does not significantly increase the mass of cyclin over the maternal stockpile. in the oocyte cyclin b2 is already present in two forms which differ in the extent of phosphory ... | 1991 | 1824935 |
| meiotic induction by xenopus cyclin b is accelerated by coexpression with mosxe. | we have investigated the relationship between xenopus laevis c-mos (mosxe) and the cyclin b component of maturation-promoting factor. microinjection of xenopus oocytes with in vitro-synthesized rnas encoding xenopus cyclin b1 or cyclin b2 induces the progression of meiosis, characterized by germinal vesicle breakdown (gvbd). by preinjecting oocytes with a mosxe-specific antisense oligonucleotide, we show that gvbd induced by cyclin b does not require expression of the mosxe protein. gvbd induced ... | 1991 | 1825350 |
| latency and temporal overlap of visually elicited contralateral and ipsilateral firing in xenopus tectum during and after the critical period. | the mechanisms underlying the development of proper topographic registration of binocular maps in the tectum of xenopus laevis involve correlation of activity patterns of ipsilateral and contralateral inputs. recent evidence implicates nmda-type glutamate receptors in this process. in general, nmda receptors are considered to function optimally when there are multiple, simultaneous excitatory inputs to a dendrite. in the binocular system of the frog, however, the ipsilateral eye's response to a ... | 1991 | 1826641 |
| cloning and sequence analysis of brain cdna encoding a xenopus d2 dopamine receptor. | a d2 dopamine receptor pharmacologically different from the mammalian d2 receptor has previously been characterized in the amphibian xenopus laevis. here we report the cloning of a xenopus d2 receptor which revealed about 75% amino acid sequence identity with its mammalian counterpart and the presence of an additional 33 amino acid sequence in the 3rd cytoplasmic loop instead of the additional 29 residues in the large form of the mammalian d2 receptor. all 7 predicted transmembrane domains are h ... | 1991 | 1826663 |
| the carboxyterminal zinc fingers of tfiiia interact with the tip of helix v of 5s rna in the 7s ribonucleoprotein particle. | immature xenopus laevis oocytes contain large quantities of a 7s ribonucleoprotein particle containing transcription factor iiia (tfiiia) and 5s rna in a 1:1 molar ratio. we have reconstituted rnps containing 5s rna and either intact tfiiia or proteolytic fragments that represent progressive c-terminal deletions of the protein. a partial trypsin digestion fragment encompassing the amino terminal seven zinc fingers of tfiiia rebinds 5s rna with nearly the same affinity as intact tfiiia. we have c ... | 1991 | 1827669 |
| two zinc finger proteins from xenopus laevis bind the same region of 5s rna but with different nuclease protection patterns. | immature oocytes from xenopus laevis contain a 42s ribonucleoprotein particle (rnp) containing 5s rna, trna, a 43 kda protein, and a 48 kda protein. a particle containing 5s rna and the 43 kda protein (p43-5s) liberated from the 42s particle upon brief treatment with urea can be purified by anion exchange chromatography. the purified p43-5s rna migrates as a distinct species during electrophoresis on native polyacrylamide gels. radiolabeled 5s rna can be incorporated into the p43-5s complex by a ... | 1991 | 1827670 |
| conserved amino acid residues within and outside of the n-terminal ribonucleoprotein motif of u1a small nuclear ribonucleoprotein involved in u1 rna binding. | by the use of hybrids between a u1 small nuclear ribonucleoprotein (snrnp: u1a) and a u2 snrnp (u2b") we have identified regions containing 29 u1a-specific amino acid residues scattered throughout the 117 n-terminal residues of the protein, which are involved in binding to u1 rna. the u1a-specific amino acid residues have been arbitrarily divided into seven contiguous groups. none of these groups is sufficient for u1 binding when transferred singly into the u2b" context, and none of the groups i ... | 1991 | 1829114 |
| on the synthesis and destruction of a- and b-type cyclins during oogenesis and meiotic maturation in xenopus laevis. | we have measured the levels of cyclin mrnas and polypeptides during oogenesis, progesterone-induced oocyte maturation, and immediately after egg activation in the frog, xenopus laevis. the mrna for each cyclin is present at a constant level of approximately 5 x 10(7) molecules per oocyte from the earliest stages of oogenesis until after fertilization. the levels of polypeptides show more complex patterns of accumulation. the b-type cyclins are first detectable in stage iv and v oocytes. cyclin b ... | 1991 | 1831203 |
| primary structure of human, chicken, and xenopus laevis p11, a cellular ligand of the src-kinase substrate, annexin ii. | the p11 protein is a member of the s-100 family of ca(2+)-binding proteins and serves within the cell as a ligand of the tyrosine kinase substrate, annexin ii. to obtain more structural information on this molecule, we have isolated and characterized p11 cdna clones from several different species. a comparison of the deduced amino acid (aa) sequences reveals that mammalian and avian p11 are highly similar (at least 90% identical at the aa level), whereas p11 from xenopus laevis shows a considera ... | 1991 | 1831433 |
| resistance to fatigue of single muscle fibres from xenopus related to succinate dehydrogenase and myofibrillar atpase activities. | this report describes how the resistance to fatigue of a muscle fibre relates to the fibre's most important atp-producing and atp-consuming reactions. twelve intact single muscle fibres were dissected from lumbrical muscles of xenopus laevis. their resistance to fatigue induced by repeated tetanic stimulation was determined, as well as their succinate dehydrogenase activity and calcium-stimulated myofibrillar atpase activity. the enzyme activities were determined by means of quantitative histoch ... | 1991 | 1832877 |
| primary structure and expression of the xenopus laevis gene encoding annexin ii. | annexin ii (anxii) is one of the ca(2+)-dependent membrane- and phospholipid-binding proteins (annexins) which are encoded by a multigene family. anxii was originally described as a major cellular substrate for the tyrosine kinase encoded by the src oncogene, and is also phosphorylated by protein kinase c in vivo and in vitro. to obtain more information about structurally conserved regions in anxii, which could be of structural and/or functional importance, we have identified anxii in a nonmamma ... | 1991 | 1833269 |
| effects of retinal detachment on rod disc membrane assembly in cultured frog retinas. | the authors compared rod outer segment (ros) disc membrane assembly rates in detached and attached frog retinas to determine if there was a rapid impairment of membrane assembly in response to retinal detachment. membrane assembly was quantified in vitro by incubating retinas in medium containing lucifer yellow, which is entrapped by nascent discs. video microscopy was used to detect incorporation of the dye. during the first 10 hr after separation of the retina from the retinal pigment epitheli ... | 1991 | 1833357 |
| zinc transfer from transcription factor iiia fingers to thionein clusters. | the rapid induction of thionein (apometallothionein) by many endogenous stimuli such as steroid hormones, cytokines, and second messengers suggests that this cysteine-rich, metal binding protein participates in an as yet undefined role in cellular regulatory processes. this study demonstrates with dna and rna binding assays and in vitro transcription measurements that thionein suppresses the binding of the xenopus laevis zinc finger transcription factor iiia (tfiiia) to 5s rna and to the 5s rna ... | 1991 | 1835092 |
| developmental expression of fibrillarin and u3 snrna in xenopus laevis. | fibrillarin is one of the protein components that together with u3 snrna constitute the u3 snrnp, a small nuclear ribonucleoprotein particle involved in ribosomal rna processing in eucaryotic cells. using an antifibrillarin antiserum for protein detection and a fibrillarin cdna and a synthetic oligonucleotide complementary to u3 snrna as hybridization probes, the expression of these two components has been studied during xenopus development. fibrillarin mrna is accumulated early in oogenesis, li ... | 1991 | 1837522 |
| characterization of muscle and non muscle xenopus laevis tropomyosin mrnas transcribed from the same gene. developmental and tissue-specific expression. | we have isolated and characterized three xenopus laevis tropomyosin cdnas (xtm alpha 2, xtm alpha 4 and xtm05). xtm alpha 2 and xtm alpha 4 were isolated from a stage-42 embryo cdna library and xtm05 from an oocyte cdna library. xtm alpha 2 and xtm alpha 4 both code for a 284-amino-acid protein homologous to the skeletal alpha tropomyosin but diverge in their 3' untranslated sequences. this divergence is due to an absence of splicing in the early embryo. xtm05 codes for a 248-amino-acid non-musc ... | 1991 | 1840524 |
| cloning and functional expression of a tea-sensitive a-type potassium channel from rat brain. | a rat brain cdna (raw3) related to the drosophila shaw k+ channel family has been characterized. raw3 crna leads to the formation of tea-insensitive, fast inactivating (a-type) k+ channels when injected into xenopus laevis oocytes. raw3 channels have markedly different properties from the previously cloned rat a-type k+ channel rck4, raw3 channels operate in the positive voltage range. | 1991 | 1840526 |
| changes in tetanic and resting [ca2+]i during fatigue and recovery of single muscle fibres from xenopus laevis. | 1. single muscle fibres were dissected from the toe muscles of xenopus laevis and microinjected with fura-2 to measure myoplasmic calcium concentration ([ca2+]i). injected fibres were illuminated at 340 and 380 nm and the ratio of the resulting fluorescence at 505 nm (the fura-2 ratio) was taken as a measure of [ca2+]i. fibres were fatigued at 21 degrees c by repeated tetani until developed tension had fallen to 50% of control. 2. tetanic tension declined monotonically during fatiguing stimulati ... | 1991 | 1841942 |
| interspecies comparisons of a/d ratios: a/d ratios are not constant across species. | the hypothesis that the ratio of the adult (a) and developmental (d) toxicity of a chemical is constant across animal species has been proposed as the basis for identifying developmental hazards, both from traditional developmental toxicity screens using laboratory mammals and from alternative systems such as the coelenterate hydra attenuata. the purpose of this study was to determine whether a/d ratios are constant across species. the developmental and adult toxicity of 14 chemicals was assesse ... | 1991 | 1843185 |
| the nicotinic acetylcholine receptor channel in embryonic muscle of xenopus laevis. a program to separate channel types. | the single channel activity of nicotinic acetylcholine receptor (achr) channels from xenopus laevis embryonic myotomes in culture, was studied with the patch clamp technique. two types of single channel activity were observed at low agonist concentration (100 nm ach-cl), which were distinguished by their conductance (60 and 40 ps, approximately). both channel types were recorded simultaneously and therefore to carry out the kinetic analysis, we separate them by using a program exploiting the dif ... | 1991 | 1843560 |
| expression of mouse serotonin transporter rna in xenopus laevis oocytes. | the serotonin transporter removes serotonin from the synapse, terminating the action of this neurotransmitter. we have taken an initial step towards cloning the serotonin transporter by obtaining its expression in xenopus oocytes. we found that mouse brainstem is a suitable source of serotonin transporter mrna and that synthesis of the transporter in injected oocytes occurs steadily over a 3 day period. uptake of [3h] serotonin was inhibited by 18 nm citalopram, a specific inhibitor of serotonin ... | 1991 | 1845527 |
| cloning by functional expression of platelet-activating factor receptor from guinea-pig lung. | platelet-activating factor (paf), a unique phospholipid mediator, possesses potent proinflammatory, smooth-muscle contractile and hypotensive activities, and appears to be crucial in the pathogenesis of bronchial asthma and in the lethality of endotoxin and anaphylactic shock. despite this, little is known of the molecular properties of the paf receptor and related signal transduction systems. although several lines of evidence suggest that activation of the paf receptor stimulates phospholipase ... | 1991 | 1846231 |
| the effects of inositol trisphosphates and inositol tetrakisphosphate on ca2+ release and cl- current pattern in the xenopus laevis oocyte. | we report that ins(1,3,4,5)p4 releases calcium from intracellular stores of intact xenopus laevis oocytes, as indicated by two different techniques, ca2(+)-sensitive microelectrodes and a fura-2 imaging system. ins(1,3,4,5)p4 releases only 20% as much ca2+ as the same amount of ins(1,4,5)p3. this effect is not due to the conversion of the injected ins(1,3,4,5)p4 to ins(1,4,5)p3, which is known to release ca2+, because the amount of [3h]ins(1,3,4,5)p4 that is converted to ins(1,4,5)p3 is extremel ... | 1991 | 1846334 |
| a retinoic acid receptor expressed in the early development of xenopus laevis. | we have isolated cdnas coding for a putative retinoic acid receptor (rar) of the gamma-type from a xenopus laevis neurula cdna library. by transient cotransfection of cos cells with an expression vector and a reporter plasmid, this cdna is shown to direct the synthesis of a retinoic acid-dependent transcription factor. in embryos of x. laevis, transcription of the corresponding gene is greatly enhanced during gastrulation and early neurulation. two distinct areas with high abundance of rar gamma ... | 1991 | 1846602 |
| cdna cloning and sequencing of human fibrillarin, a conserved nucleolar protein recognized by autoimmune antisera. | we have isolated a 1.1-kilobase cdna clone that encodes human fibrillarin by screening a hepatoma library in parallel with dna probes derived from the fibrillarin genes of saccharomyces cerevisiae (nop1) and xenopus laevis. rna blot analysis indicates that the corresponding mrna is approximately 1300 nucleotides in length. human fibrillarin expressed in vitro migrates on sds gels as a 36-kda protein that is specifically immunoprecipitated by antisera from humans with scleroderma autoimmune disea ... | 1991 | 1846968 |
| insulin and insulin-like-growth-factor-i (igf-i) receptors in xenopus laevis oocytes. comparison with insulin receptors from liver and muscle. | insulin and insulin-like-growth-factor-i (igf-i) receptors were partially purified from full-grown (stages v-vi) xenopus laevis oocytes by affinity chromatography on wheat-germ agglutinin-agarose. competitive-binding assays revealed high-affinity binding sites for both insulin and igf-i (kd = 2.5 x 10(-10) m and 8 x 10(-10) m respectively). however, igf-i receptors were about 15 times more abundant than insulin receptors (22.5 x 10(11) versus 1.5 x 10(11)/mg of protein). moreover, comparison of ... | 1991 | 1847619 |
| expression of adenylate cyclase-coupled osseous parathyroid hormone and parathyroid hormone-like peptide receptors in xenopus oocytes. | functional parathyroid hormone (pth) and pth-like peptide receptors were expressed in xenopus laevis oocytes after injection of poly(a)+ rna isolated from the rat osteogenic sarcoma cell line, umr 106. increases in camp were seen in individual oocytes in response to added bovine (b) pth-(1-34) (10(-6) m), human (h) plp-(1-34) (hplp-(1-34), 10(-6) m), isoproterenol (10(-4) m), and forskolin (10(-4) m). although both intracellular and extracellular camp levels were stimulated approximately 1.5-2-f ... | 1991 | 1848224 |
| regulation of pp90rsk phosphorylation and s6 phosphotransferase activity in swiss 3t3 cells by growth factor-, phorbol ester-, and cyclic amp-mediated signal transduction. | somatic cell homologs to the xenopus laevis s6 protein kinases (referred to collectively as pp90rsk) have recently been identified and partially characterized. here we examine alterations in pp90rsk phosphorylation and s6 phosphotransferase activity in response to regulators of multiple signal transduction systems: purified growth factors, phorbol ester, changes in cyclic amp (camp) levels, and sodium vanadate. all reagents tested increased pp90rsk serine and threonine phosphorylation, but only ... | 1991 | 1848664 |
| persistence of bovine papillomavirus (pbpv-1) as an extrachromosomal element in tissues of microinjected xenopus laevis. | 1991 | 1849256 | |
| the crf-related peptide sauvagine stimulates and the gabab receptor agonist baclofen inhibits cyclic-amp production in melanotrope cells of xenopus laevis. | release of alpha-msh from the pars intermedia melanotrope cells of xenopus laevis is regulated by various classical neurotransmitters and neuropeptides. we have examined the effect of two of these regulatory substances, the neurotransmitter gaba and the crf-related peptide sauvagine, on the adenylate cyclase system of the melanotrope cells. sauvagine treatment, which stimulates alpha-msh release, lead to an elevation in the level of cyclic-amp, an effect which was potentiated by cholera toxin. t ... | 1991 | 1850060 |
| cdna cloning and developmental expression of fibroblast growth factor receptors from xenopus laevis. | the heparin-binding growth factors constitute a family of homologous polypeptides including basic and acidic fibroblast growth factors (fgfs). these factors participate in a variety of processes, including wound healing, angiogenesis, neuronal survival, and inductive events in the early amphibian embryo. we have isolated three closely related species of cdna clones for xenopus fgf receptors. one of these, designated xfgfr-a1, encodes an open reading frame of 814 amino acids. a second class encod ... | 1991 | 1850097 |
| modulation of na,k-atpase expression during early development of xenopus laevis. | in amphibian and mammalian systems, regulation of na+ transport via the na,k-atpase plays an important role in distinct developmental processes such as blastocoele formation and neurulation. in this study, we have followed the na,k-atpase activity, the biosynthesis, and the cellular accumulation of catalytic alpha-subunits after fertilization of xenopus laevis eggs up to neurula formation. our data show that na,k-atpase activity increases significantly between stages 4 and 6 and again between st ... | 1991 | 1850368 |
| interaction of 5-bromowillardiine with non-nmda receptors expressed in xenopus laevis oocytes injected with chick brain mrna. | excitatory amino acid (eaa) receptors were studied in xenopus laevis oocytes microinjected with 1-day-old chick brain mrna using a two-electrode voltage clamp technique. eaa agonists could be differentially characterised according to their current/voltage (i/v) relationships; i/v plots to kainate (ka) and domoate (dom) inwardly rectified at positive membrane potentials whereas quisqualate (qa), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (ampa) and l-glutamate (l-glu) produced linea ... | 1991 | 1850505 |
| exogeneous diacylglycerols downregulate the activity of na(+)-k+ pump in xenopus laevis oocytes. | in this study, cell permeable diacylglycerols, sn-1,2-dioctanoglycerol (dic8), and sn-1-oleoyl-2-acetylglycerol (oag) were found to downregulate the activity of na(+)-k+ pump in xenopus laevis oocytes. both dic8 and oag decreased the binding of [3h]ouabain to intact oocytes while phorbol esters did not appreciably influence the same. these diacylglycerols inhibited the amiloride-sensitive 22na+ influx and ouabain-sensitive 86rb+ uptake in the oocytes. furthermore, dic8 prevented the 22na+ efflux ... | 1991 | 1851097 |
| the insulin-like growth factor 1 (igf-1) receptor is responsible for mediating the effects of insulin, igf-1, and igf-2 in xenopus laevis oocytes. | competitive hormone binding studies with membrane and partially purified receptors from xenopus laevis oocytes revealed that the oocyte possesses high affinity (kd = 1-3 nm) binding sites for both insulin growth factors 1 and 2 (igf-1 and igf-2), but not for insulin. consistent with these findings, igf-1 activates hexose uptake by xenopus oocytes with a ka (3 nm) identical with its kd, while igf-2 and insulin activate hexose uptake with ka values of 50 nm and 200-250 nm, respectively, suggesting ... | 1991 | 1851744 |
| developmental regulation of transcription factor ap-2 during xenopus laevis embryogenesis. | we have isolated a cdna clone encoding the xenopus homologue of the transcription factor ap-2 (xap-2). the predicted amino acid sequence derived from the xenopus cdna shows very strong conservation with the amino acid sequence of human ap-2, suggesting that this protein is evolutionarily conserved, at least among vertebrates. this is further substantiated by the demonstration that an in vitro translation product of xap-2 cdna bound specifically to an ap-2 binding site from the human mt-iia gene. ... | 1991 | 1852613 |
| [the space-time distribution of the mrna of the nuclear proteins c-myc and p-53 in the development of the clawed toad studied by hybridization in situ]. | we studied distribution of mrna for nuclear protooncogene c-myc and nuclear protein p-53 in mature oocytes and embryos of xenopus laevis from the stage of fertilization up to the stage of hatching by in situ hybridization with histological sections. mrna for c-myc was present in all cells of the embryo at all studied developmental stages. between the stage of fertilization and up to the late blastula, mrna concentration for c-myc decreased progressively in all embryonic cells. during gastrulatio ... | 1991 | 1857586 |
| isolation of histone-like proteins from mitochondria of bovine heart. | two methods for isolating and purifying histone-like proteins from mitochondria of bovine heart are described. in the first, a sonicated extract of the mitochondria was fractionated in three chromatography steps, including affinity chromatography on dna-cellulose, to purify a protein that resembles very closely the histone-like protein (hm) of yeast mitochondria. in the second method, an acid extract of the heart mitochondria was the starting material; two other histone-like proteins were separa ... | 1991 | 1857681 |
| translational control during early development. | early development in many animals is programmed by maternally inherited messenger rnas. many of these mrnas are translationally dormant in immature oocytes, but are recruited onto polysomes during meiotic maturation, fertilization, or early embryogenesis. in contrast, other mrnas that are translated in oocytes are released from polysomes during these later stages of development. recent studies have begun to define the cis and trans elements that regulate both translational repression and transla ... | 1991 | 1859396 |
| presence of activin (erythroid differentiation factor) in unfertilized eggs and blastulae of xenopus laevis. | activin a, a member of the transforming growth factor beta superfamily, has recently been found to have potent mesoderm-inducing activity on isolated early xenopus animal-cap cells. we measured the activin activity of the xenopus egg extract by using an erythroid-differentiating test with friend leukemia cells. the results showed that an activin homologue is, indeed, contained in unfertilized eggs and blastulae of xenopus laevis in a considerable amount. this activity was eluted at the same rete ... | 1991 | 1862079 |
| bone morphogenetic protein 4 (bmp-4), a member of the tgf-beta family, in early embryos of xenopus laevis: analysis of mesoderm inducing activity. | we have screened a xenopus ovary cdna library using a synthetic oligonucleotide derived from that part of the inhibin beta a sequence, which is highly conserved within the tgf-beta family. out of several clones yielding autoradiographic signals four turned out to represent xenopus counterparts to the human bone morphogenetic protein 4 (bmp-4). each two of the four sequences are nearly identical and probably account for different alleles whereas the two pairs showing 5% divergence may have arisen ... | 1991 | 1863557 |
| inhibition of axonal development after injection of neurofilament antibodies into a xenopus laevis embryo. | the ability to target specific cytoskeletal components in axons for disruption within intact developing embryos would provide a valuable tool for studying neuronal development. neurofilaments are an attractive target for such an approach, because they are neuron specific and are expressed late in embryogenesis principally beginning during axon outgrowth. no pharmacological agents are currently available that disrupt neurofilaments without also affecting general development. one approach that has ... | 1991 | 1865017 |
| a novel endopeptidase from xenopus that recognizes alpha-helical secondary structure. | the magainin peptides of xenopus laevis are broad-spectrum antimicrobial agents. upon discharge from the skin glands, these basic, amphipathic peptides are each further processed at a single xaa-lys bond into half-peptides by a cosecreted protease. we describe the characterization and purification to homogeneity of this endopeptidase from xenopus skin. the enzyme is a metalloprotease 110 kd in size. analyses of substrate specificity revealed that the endopeptidase recognizes peptides that share ... | 1991 | 1868549 |
| a major substrate of maturation promoting factor identified as elongation factor 1 beta gamma delta in xenopus laevis. | protein synthesis is believed to be under control of the cell cycle during meiosis and mitosis. any relationship between substrates for cdc2 kinase and components of the protein synthetic apparatus would therefore be of prime importance. during meiosis of xenopus laevis oocytes one of the substrates for this kinase is a p47 protein, which is complexed to two other proteins, p36 and p30. judged from partial amino acid sequence data on p47 and p30, the p30 and p47 proteins were reported to resembl ... | 1991 | 1869528 |
| demonstration of calcium in dermal melanocytes of xenopus laevis and poecilia reticulata with electron energy-loss spectroscopy and electron spectroscopic imaging. | the subcellular distribution of calcium in dermal melanocytes of xenopus laevis and poecilia reticulata has been analysed. using two cytochemical methods, phosphate precipitation and a combined oxalate-pyroantimonate technique, electron energy-loss spectroscopy and electron spectroscopic imaging have been applied for elemental analysis. both precipitation techniques revealed a high calcium content in the melanosomes of both species. calcium was also located in the vicinity of collagen fibrils an ... | 1991 | 1870109 |
| a full-length cdna encoding a mitochondrial dna-specific single-stranded dna binding protein from xenopus laevis. | 1991 | 1870981 | |
| developmental expression of intestinal surfactant-like particles in rats. | we have reported the appearance of surfactant-like particles enriched for intestinal alkaline phosphatase and phosphatidylcholine within enterocytes and in the lumen of adult fat-fed rat intestine. because rat pulmonary surfactant decreases in abundance during the first postnatal days, we examined the developmental expression of these intestinal particles in suckling rats. electron microscopy revealed abundant particles in 1-day-old rats within and surrounding the villus enterocytes, declining i ... | 1991 | 1872397 |
| angiotensin receptors from rat liver, brain and pituitary gland. expression of two subtypes in xenopus oocytes. | xenopus laevis oocytes were used to express angiotensin receptors encoded by mrnas extracted from rat liver, adenohypophysis and brain. groups of ten mrna-injected oocytes were loaded with 45ca2+ and the responsiveness to angiotensin ii (a ii) and related molecules tested by monitoring 45ca2+ outflux. a ii and angiotensin iii (a iii) induced a marked and transient increase in 45ca2+ outflux from mrna, but not from control, water-injected, oocytes. the increase over basal value of 45ca2+ outflux ... | 1991 | 1872809 |
| characterization of n- and c-terminal deletion mutants of the rat serotonin ht2 receptor in xenopus laevis oocytes. | deletion mutants of the serotonin ht2 receptor have been constructed in which the n- and c-terminal sequences have been gradually removed. the mutant constructs were assayed for their biological activity by electrophysiological measurements in xenopus oocytes previously injected with the respective in vitro synthesized crnas. no significant loss of biological activity was observed when either the extracellular n-terminal sequence, including all potential glycosylation sites, up to the beginning ... | 1991 | 1872857 |
| each otoconia polymorph has a protein unique to that polymorph. | 1. otoconia, contained within the vestibular portion of the inner ear, are mineralized by one of three polymorphs of calcium carbonate. each otoconial polymorph contains a unique, major protein. 2. the major protein of calcitic otoconia of members of different vertebrate classes, amphibia (african clawed frog) and mammalia (rat), have similar molecular weights. 3. the major protein of calcitic rat otoconia and of vateritic otoconia of the gar may be calcium binding proteins. no protein from the ... | 1991 | 1873986 |
| homologous radioimmunoassay for bullfrog growth hormone. | antiserum against bullfrog growth hormone (fgh) was produced by immunizing rabbits with the highly purified fgh obtained from adenohypophyses of adult bullfrogs. histological studies on bullfrog adenohypophyses revealed that the cells that immunologically reacted with the antiserum against fgh corresponded to the ones positively stained with the antiserum against rat gh. the antiserum together with fgh and 125i-fgh was employed to develop a radioimmunoassay (ria) for fgh. several dilutions of pl ... | 1991 | 1874383 |
| morphogenesis of adrenergic cells in a frog parasympathetic ganglion. | the development of the parasympathetic cardiac ganglion of the frog xenopus laevis was marked by the differentiation of a population of adrenergic small intensely fluorescent (sif) cells. the neural crest contributes precursors for both sif cells and the well-studied cholinergic cardiac ganglion neurons; this situation provided an opportunity to determine whether morphogenesis of the two cell types was correlated. accordingly, we examined the initial differentiation, developmental regulation, an ... | 1991 | 1874979 |
| repair of a synthetic abasic site involves concerted reactions of dna synthesis followed by excision and ligation. | a synthetic analog of an abasic site in dna is efficiently repaired by a short-patch repair mechanism in soluble extracts of xenopus laevis oocytes (y. matsumoto and d. f. bogenhagen, mol. cell. biol. 9:3750-3757, 1989). we present a detailed analysis of the repair mechanism, using extracts depleted of endogenous nucleotide pools. atp was required for repair with a sharp optimal concentration of 5 mm. the initial rate of repair was increased by preincubation of the dna in the extract in the pres ... | 1991 | 1875931 |
| ornithine decarboxylase immunoreactivity in the pituitary gland. a comparative lightmicroscopical study. | in the present study efforts are made to localize ornithine decarboxylase enzyme protein--the key enzyme of polyamine biosynthesis--in the adenohypophysis of different vertebrates by means of immunocytochemistry. the antigenic expression of ornithine decarboxylase was revealed in the pituitary of the clawed frog (xenopus laevis d.), but not in rat and human adenohypophysis. the immunocytochemical results are compared with the staining pattern of the periodic acid-schiff-reaction. no correlation ... | 1991 | 1878921 |
| differential expression of two cadherins in xenopus laevis. | using a cadherin fraction from xenopus tissue culture cells as an immunogen, two monoclonal antibodies were obtained that allowed the characterization of two distinct cadherins in the xenopus embryo. the two cadherins differ in molecular weight, in their time of appearance during development and in their spatial pattern of expression. one of the antigens was identified as e-cadherin. it appears in the embryonic ectoderm during gastrulation when epidermal differentiation commences and it disappea ... | 1991 | 1879345 |
| deep cytoplasmic rearrangements during early development in xenopus laevis. | the egg of the frog xenopus is cylindrically symmetrical about its animal-vegetal axis before fertilization. midway through the first cell cycle, the yolky subcortical cytoplasm rotates 30 degrees relative to the cortex and plasma membrane, usually toward the side of the sperm entry point. dorsal embryonic structures always develop on the side away from which the cytoplasm moves. details of the deep cytoplasmic movements associated with the cortical rotation were studied in eggs vitally stained ... | 1991 | 1879356 |
| heterogeneity in the xenopus ribosomal transcription factor xubf has a molecular basis distinct from that in mammals. | the xenopus polymerase i transcription factor xubf is an hmg-box protein which has been purified as two polypeptides of approximately 82 and 85 kda. recently a cdna sequence predicted an xubf protein (xubf1) of 677 amino acids (79 kda) containing five tandem hmg-boxes. here a second and distinct xubf cdna has been isolated and characterised. this cdna codes an xubf protein (xubf2) of 701 amino acids (82 kda), having 93% homology with xubf1 but containing an insertion of 22 amino acids between hm ... | 1991 | 1879565 |
| occurrence of h1 subtypes specific to pronuclei and cleavage-stage cell nuclei of anuran amphibians. | male pronuclei were induced in vitro by incubating the lysolecithin-permeabilized sperm nuclei of anuran amphibians bufo japonicus and xenopus laevis with the extracts from homologous eggs, and nuclear basic proteins were analyzed by two-dimensional gel electrophoresis. by 5 min after the incubation, the sperm nuclei had completely lost sperm-specific proteins but possessed a whole set of nucleosomal core histones, except that h2a was mostly replaced by a putative h2a.x. the pronuclei did not po ... | 1991 | 1879604 |
| development of functional sex differences in the larynx of xenopus laevis. | three laryngeal properties associated with the production of masculine song--laryngeal muscle tension, fiber twitch type, and fiber recruitment--are markedly sexually dimorphic in adult xenopus laevis frogs. to elucidate the pattern of sexual differentiation, tension and fiber recruitment in male and female larynges and fiber twitch type in male larynges were examined throughout postmetamorphic development. masculinization of male laryngeal properties begins early in postmetamorphic development ... | 1991 | 1879611 |
| temporal constraints on androgen directed laryngeal masculinization in xenopus laevis. | temporal constraints on androgen regulated masculinization of three sexually dimorphic laryngeal properties--tension, fiber type, and fiber recruitment--were examined in xenopus laevis frogs. endocrine state was manipulated at pm0 when the larynx is similar in males and females, at pm2 when the larynx begins sexual differentiation, and at pm6 when sexual differentiation is complete. removing the testes in developing males (pm0 or pm2) completely arrests laryngeal masculinization. masculinization ... | 1991 | 1879612 |
| a negative slope in the current-voltage relationship of the na+/k+ pump in xenopus oocytes produced by reduction of external [k+]. | to investigate the voltage dependence of the na+/k+ pump, current-voltage relations were determined in prophase-arrested oocytes of xenopus laevis. all solutions contained 5 mm ba2+ and 20 mm tetraethylammonium (tea) to block k+ channels. if, in addition, the na+/k+ pump is blocked by ouabain, k(+)-sensitive currents no larger than 50 na/cm2 remain. reductions in steady-state current (on the order of 700 na/cm2) produced by 50 microm ouabain or dihydro-ouabain or by k+ removal, therefore, primar ... | 1991 | 1880791 |
| the eye in the brain: retinoic acid effects morphogenesis of the eye and pathway selection of axons but not the differentiation of the retina in xenopus laevis. | we have analyzed the effects of all-trans retinoic acid (ra) on the morphogenesis, differentiation and projection of the eye of xenopus. ra was applied in concentrations of 10(-5), 5 x 10(-6) and 10(-6) m at stages 9-17. animals were reared until stages 40-48. ra applied before stage 11 1/2, abated completely formation of an eye or a retina, at later stages it led to the formation of microphthalmic eyes. even in the absence of an eye parts of the forebrain had characteristics of the retina, but ... | 1991 | 1881624 |
| thymus-replacing activity from the metamorphic spleen of xenopus laevis. | anuran metamorphosis offers an interesting vertebrate immunological paradigm, for adult cells that arise within the immunocompetent larval body are mhc class i disparate from those of the larva. the animals, in order to avoid immune self-destruction during this transition period, are made unresponsive to these modified-self cells by an impairment of t-cell functions. however, it remains to be discovered how an animal with compromised t-cell functions can protect itself from those environmental p ... | 1991 | 1883954 |
| reinvestigation of dna ligase i in axolotl and pleurodeles development. | we have recently shown that the exclusion process causing the replacement of dna ligases ii by dna ligase i in amphibian eggs after fertilization does not occur in the case of xenopus laevis [hardy, s., aoufouchi, s., thiebaud, p., and prigent, c., (1991) nucleic acids res. 19, 701-705]. since this result is in contradiction with the situation reported in axolotl and pleurodeles we decided to reinvestigate such results in both species. three different approaches have been used: (1) the substrate ... | 1991 | 1886765 |
| developmental regulation of a serum response element binding activity in amphibian embryos. | as part of our studies of transcriptional control during early development in vertebrates, we have examined embryos of the amphibian xenopus laevis for the presence of sequence-specific dna-binding proteins, using gel electrophoresis mobility-shift assays. our analysis has focused on sequence elements in the cytoskeletal actin gene, whose embryonic transcription is initially activated at the gastrula stage, approximately 16 hours after fertilization. we detect activities capable of specific bind ... | 1991 | 1888512 |
| assessment of the developmental toxicity of ascorbic acid, sodium selenate, coumarin, serotonin, and 13-cis retinoic acid using fetax. | the developmental toxicity of five compounds was evaluated with the frog embryo teratogenesis assay: xenopus (fetax) and the results were compared to mammalian literature. small cell xenopus laevis blastulae were exposed to ascorbic acid, sodium selenate, coumarin, serotonin and 13-cis retinoic acid for 96 hr. three separate static-renewal assays were conducted for each compound. teratogenic potential of the test materials was determined based on teratogenic index values [ti = lc50/ec50 (malform ... | 1991 | 1889372 |
| assessing the efficacy of an aroclor 1254-induced exogenous metabolic activation system for fetax. | the developmental toxicity of n-nitrosodimethylamine (ndma) and trichloroethylene (tce) was assessed with frog embryo teratogenesis assay: xenopus (fetax). late xenopus laevis blastulae were exposed to ndma and tce for 96-h in two separate static-renewal tests with and without the presence of three differently induced exogenous metabolic activation systems (mas). the mas consisted of aroclor 1254-induced (aroclor 1254 mas), isoniazid-induced (inh mas), and a post-isolation mixture (mixed mas) of ... | 1991 | 1889373 |
| muscle opacity (mo), a new mutant gene in xenopus laevis, linked to the rusty locus. | a new developmental mutant is described in xenopus laevis (amphibia, anura): muscle opacity (mo). homozygotes die at larval stage 48. the underlying defect, visible at stage 47, is a degeneration of cephalic musculature. the mo gene is linked to the rusty locus, with a map distance of 6.1%. | 1991 | 1889742 |
| cloning of complementary dna encoding a functional human interleukin-8 receptor. | interleukin-8 (il-8) is an inflammatory cytokine that activates neutrophil chemotaxis, degranulation, and the respiratory burst. neutrophils express receptors for il-8 that are coupled to guanine nucleotide-binding proteins (g proteins); binding of il-8 to its receptor induces the mobilization of intracellular calcium stores. a cdna clone from hl-60 neutrophils, designated p2, has now been isolated that encodes a human il-8 receptor. when p2 is expressed in oocytes from xenopus laevis, the oocyt ... | 1991 | 1891716 |
| expression of a novel cadherin (ep-cadherin) in unfertilized eggs and early xenopus embryos. | two distinct cadherin cdna clones of xenopus laevis were isolated from a stage 17 embryo cdna library. analysis of the complete deduced amino acid sequences indicated that one of these molecules is closely homologous to chicken and mouse n-cadherin, while the other displays comparable homology to both e- and p-cadherins and was thus denoted ep-cadherin. this molecule has an apparent relative molecular mass of 125 x 10(3) (compared to approx. 138 x 10(3) or approx. 140 x 10(3) of e-cadherin and n ... | 1991 | 1893866 |
| two forms of elongation factor 1 alpha (ef-1 alpha o and 42sp50), present in oocytes, but absent in somatic cells of xenopus laevis. | we have purified and partially sequenced the ef-1 alpha protein from xenopus laevis oocytes (ef-1 alpha o). we show that the two cdna clones isolated by coppared et al. (coppard, n. j., k. poulsen, h. o. madsen, j. frydenberg, and b. f. c. clark. 1991. j. cell biol. 112:237-243) do not encode 42sp50, as claimed by these authors, but two very similar forms of ef-1 alpha o (ef-1 alpha o and ef-1 alpha o1). 42sp50 is the major protein component of a 42s nucleoprotein particle that is very abundant ... | 1991 | 1894690 |
| modelling the three-dimensional structure and electrostatic potential field of the two cu,zn superoxide dismutase variants from xenopus laevis. | the crystallographic structure of bovine superoxide dismutase has been used as a template for the graphic reconstruction of the three-dimensional structures of the two xenopus laevis variants (schininà, m.e. et al. arch. biochem. biophys. 272:507-515, 1989). in these models the structure-essential residues maintain their position and their structural role, and the interactions between the subunits and the close packing within the beta-barrel are maintained with conservative substitutions and eve ... | 1991 | 1896428 |
| development of the amphibian oculomotor complex: evidences for migration of oculomotor motoneurons across the midline. | the development of the oculomotor nucleus in five species of salamanders and one anuran species was investigated with tracing techniques. the data presented support the hypothesis that oculomotor motoneurons innervating the superior rectus muscle migrate across the midline. in the salamander pleurodeles waltl, only ipsilateral oculomotor motoneurons are labeled in early development. later, these neurons extend dendrites toward the contralateral side into the ventral tegmental neuropil, after whi ... | 1991 | 1897742 |
| observations on the development of ascending spinal pathways in the clawed toad, xenopus laevis. | the development of ascending spinal pathways has been studied in the clawed toad, xenopus laevis. from stage 35 (hatching) on, hrp was applied at the spinomedullary border or to the area of the developing dorsal column nucleus, to analyze the development of ascending spinal pathways to the brain stem, and the onset and development of spinal projections to the dorsal column nucleus, respectively. several populations of spinal neurons with ascending projections at least as far as the spinomedullar ... | 1991 | 1897746 |
| expression of the rabbit intestinal n2 na+/nucleoside transporter in xenopus laevis oocytes. | polyadenylated [poly(a)+] mrna isolated from rabbit small-intestinal mucosa was injected into xenopus laevis oocytes, and expression of the n2 na+/nucleoside co-transporter was assayed by measuring na(+)-dependent thymidine uptake. expression of na(+)-dependent thymidine uptake steadily increased after mrna injection and was on average increased 11-fold by day 6 over background. na(+)-dependent thymidine uptake was saturable (apparent km approximately 30 microm at 22 degrees c) and inhibited by ... | 1991 | 1898349 |
| localization of paxillin, a focal adhesion protein, to smooth muscle dense plaques, and the myotendinous and neuromuscular junctions of skeletal muscle. | in this report we have demonstrated that paxillin, a cytoskeletal protein which is present in focal adhesions, localizes in vivo to regions of cell-extracellular matrix interaction which are believed to be analogous to focal adhesions. specifically, it is enriched in the dense plaques of chicken gizzard smooth muscle tissue and in the myotendinous junctions formed in xenopus laevis tadpole tail skeletal muscle. in addition, paxillin was identified at the rat diaphragm neuromuscular junction. the ... | 1991 | 1899076 |
| inhibition of ras-induced germinal vesicle breakdown in xenopus oocytes by rap-1b. | a cdna clone (krev-1) has recently been identified that possesses the ability to reverse the transformed phenotype when introduced into a k-ras-transformed nih/3t3 cell line. the krev-1 protein, also known as rap-1a, was found to share 50% homology with the ras proteins. the rap-1a protein has also been shown to block the interaction of ras with its gtpase activating protein in vitro, leading to speculation regarding its role in vivo. a closely related protein, rap-1b, has also been identified i ... | 1991 | 1899188 |
| evidence for the involvement of a pertussis toxin-insensitive g-protein in egg activation of the frog, xenopus laevis. | activation responses of the frog egg at fertilization include the release of calcium from intracellular stores and the opening of calcium-dependent chloride channels, which produce the fertilization potential. to investigate the presence of guanine nucleotide-binding proteins (g-proteins), and their role in initiation of these events in the egg of the frog xenopus laevis, we assayed for pertussis and cholera toxin substrates, and applied activators and inhibitors of g-proteins. pertussis toxin c ... | 1991 | 1899403 |
| synthesis of sperm-specific basic nuclear proteins (sps) in cultured spermatids from xenopus laevis. | the accumulation and synthesis of sperm-specific basic nuclear proteins (sps) in xenopus spermatids in vitro were studied by acid-urea-triton polyacrylamide gel electrophoresis and fluorography. in synchronous cultures of round spermatids, the amount of sp2 and sp3-5 accumulated almost linearly with time, while that of sp1 remained almost constant. fluorography showed that round spermatids incorporated [14c]arginine mostly into sp1 and sp3-5, very little into sp2, and none into histones. when [1 ... | 1991 | 1901796 |
| purification of two thermostable components of messenger ribonucleoprotein particles (mrnps) from xenopus laevis oocytes, belonging to a novel class of rna-binding proteins. | we have purified and partially sequenced two proteins from xenopus laevis previtellogenic oocytes, belonging to messenger ribonucleoprotein particles (mrnps). the purification procedure rests on the thermostability of these proteins, which remain soluble after heating the cell extracts at 80 degrees c. the thermostable proteins can be identified with two of the most abundant components (mrnp3 and mrnp4) of the mrnps, described by darnbrough and ford (1981) [eur. j. biochem. 118, 415-424]. mrnp3 ... | 1991 | 1902800 |
| sequence of c region of l chains from xenopus laevis ig. | a cdna expression library, prepared from xenopus laevis splenocytes, was screened with antibodies to xenopus ig. one clone, lambda xig23, reacted with antibodies to igy and to igm; the insert hybridized to approximately 1.3-kb rna from spleen, the approximate size expected for l chain mrna. an additional clone, lambda xig31, was identified by cross-hybridization. the inserts of lambda xig23 and lambda xig31 begin in the third framework region of the v region and extend through the c region to th ... | 1991 | 1903418 |
| the genomic organization of immunoglobulin vh genes in xenopus laevis shows evidence for interspersion of families. | the complete genomic sequences of xenopus laevis immunoglobulin heavy chain variable region (vh) genes comprising families iv-xi are reported. using vh family-specific probes, linkage relationships for xenopus vhi-vhxi have been determined. with the possible exceptions of vhiii and vhvii, xenopus vh genes appear to be interspersed. when from two to five vh segments are identified in individual clones, the elements are found to be in the same relative transcriptional orientation. although the rel ... | 1991 | 1905399 |