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Showing papers in "Nature in 1984"


Journal ArticleDOI
01 Apr 1984-Nature
TL;DR: Protein kinase C probably serves as a receptor for the tumour promoters and further exploration of the roles of this enzyme may provide clues for understanding the mechanism of cell growth and differentiation.
Abstract: Protein kinase C has a crucial role in signal transduction for a variety of biologically active substances which activate cellular functions and proliferation. When cells are stimulated, protein kinase C is transiently activated by diacylglycerol which is produced in the membrane during the signal-induced turnover of inositol phospholipids. Tumour-promoting phorbol esters, when intercalated into the cell membrane, may substitute for diacylglycerol and permanently activate protein kinase C. The enzyme probably serves as a receptor for the tumour promoters. Further exploration of the roles of this enzyme may provide clues for understanding the mechanism of cell growth and differentiation.

6,917 citations


Journal ArticleDOI
01 Nov 1984-Nature
TL;DR: Diacylglycerol operates within the plane of the membrane to activate protein kinase C, whereas inositol trisphosphate is released into the cytoplasm to function as a second messenger for mobilizing intracellular calcium.
Abstract: There has recently been rapid progress in understanding receptors that generate intracellular signals from inositol lipids. One of these lipids, phosphatidylinositol 4,5-bisphosphate, is hydrolysed to diacylglycerol and inositol trisphosphate as part of a signal transduction mechanism for controlling a variety of cellular processes including secretion, metabolism, phototransduction and cell proliferation. Diacylglycerol operates within the plane of the membrane to activate protein kinase C, whereas inositol trisphosphate is released into the cytoplasm to function as a second messenger for mobilizing intracellular calcium.

5,712 citations


Journal ArticleDOI
02 Feb 1984-Nature
TL;DR: The voltage dependence of the NMDA receptor-linked conductance appears to be a consequence of the voltage dependenceof the Mg2+ block and its interpretation does not require the implication of an intramembrane voltage-dependent ‘gate’.
Abstract: The responses of vertebrate neurones to glutamate involve at least three receptor types. One of these, the NMDA receptor (so called because of its specific activation by N-methyl-D-aspartate), induces responses presenting a peculiar voltage sensitivity. Above resting potential, the current induced by a given dose of glutamate (or NMDA) increases when the cell is depolarized. This is contrary to what is observed at classical excitatory synapses, and recalls the properties of 'regenerative' systems like the Na+ conductance of the action potential. Indeed, recent studies of L-glutamate, L-aspartate and NMDA-induced currents have indicated that the current-voltage (I-V) relationship can show a region of 'negative conductance' and that the application of these agonists can lead to a regenerative depolarization. Furthermore, the NMDA response is greatly potentiated by reducing the extracellular Mg2+ concentration [( Mg2+]o) below the physiological level (approximately 1 mM). By analysing the responses of mouse central neurones to glutamate using the patch-clamp technique, we have now found a link between voltage sensitivity and Mg2+ sensitivity. In Mg2+-free solutions, L-glutamate, L-aspartate and NMDA open cation channels, the properties of which are voltage independent. In the presence of Mg2+, the single-channel currents measured at resting potential are chopped in bursts and the probability of opening of the channels is reduced. Both effects increase steeply with hyperpolarization, thereby accounting for the negative slope of the I-V relationship of the glutamate response. Thus, the voltage dependence of the NMDA receptor-linked conductance appears to be a consequence of the voltage dependence of the Mg2+ block and its interpretation does not require the implication of an intramembrane voltage-dependent 'gate'.

3,977 citations


Journal ArticleDOI
01 Jan 1984-Nature
TL;DR: It is concluded that the CD4 antigen is an essential and specific component of the receptor for the causative agent of AIDS.
Abstract: Acquired immune deficiency syndrome (AIDS) is characterized by opportunistic infections and by 'opportunistic neoplasms' (for example, Kaposi's sarcoma). Persistent generalized lymphadenopathy (PGL) is epidemiologically associated with AIDS, especially in male homosexuals. A subset of T lymphocytes positive for the CD4 antigen (also termed T4 antigen), is depleted in AIDS and PGL patients. A retrovirus found in T-cell cultures from these patients is strongly implicated in the aetiology of AIDS because of the high frequency of isolation and the prevalence of specific antibodies in the patients. Here we have detected cell-surface receptors for the AIDS retrovirus (human T-cell leukaemia virus-III (HTLV-III) and lymphadenopathy-associated virus-1 (LAV-1) isolates) by testing the susceptibility of cells to infection with pseudotypes of vesicular stomatitis virus bearing retroviral envelope antigens, and by the formation of multinucleated syncytia on mixing virus-producing cells with receptor-bearing cells. Receptors were present only on cells expressing CD4 antigen; among 155 monoclonal antibodies tested, each of the 14 anti-CD4 antibodies inhibited formation of syncytia and blocked pseudotypes. Productive infection of CD4+ cells with HTLV-III or LAV-1 markedly reduced cell-surface expression of CD4. In contrast, receptors for HTLV-I and HTLV-II were not restricted to CD4+ cells, were not blocked by anti-CD4 antibodies; cells productively infected with HTLV-I and HTLV-II expressed surface CD4. Hence, we conclude that the CD4 antigen is an essential and specific component of the receptor for the causative agent of AIDS.

3,631 citations


Journal ArticleDOI
03 May 1984-Nature
TL;DR: The ability of fibronectin to bind cells can be accounted for by the tetrapeptide L-arginyl-glycyl- L-aspartyl-L-serine, a sequence which is part of the cell attachment domain of fibronsectin and present in at least five other proteins.
Abstract: The ability of fibronectin to bind cells can be accounted for by the tetrapeptide L-arginyl-glycyl-L-aspartyl-L-serine, a sequence which is part of the cell attachment domain of fibronectin and present in at least five other proteins. This tetrapeptide may constitute a cellular recognition determinant common to several proteins.

3,574 citations


Journal ArticleDOI
15 Nov 1984-Nature
TL;DR: It is reported here that microtubules in vitro coexist in growing and shrinking populations which interconvert rather infrequently and this dynamic instability is a general property of micro Tubules and may be fundamental in explaining cellular microtubule organization.
Abstract: We report here that microtubules in vitro coexist in growing and shrinking populations which interconvert rather infrequently. This dynamic instability is a general property of microtubules and may be fundamental in explaining cellular microtubule organization.

3,108 citations


Journal ArticleDOI
17 May 1984-Nature
TL;DR: Using voltage-clamp experiments on mouse spinal cord neurones, it is shown that the voltage-sensitivity of NMDA action is greatly reduced on the withdrawal of physiological concentrations (∼1 mM) of Mg2+ from the extracellular fluid, providing further evidence that Mg 2+ blocks inward current flow through ion channels linked to NMDA receptors.
Abstract: Acidic amino acids are putative excitatory synaptic transmitters1,2, the ionic mechanism of which is not well understood. Recent studies with selective agonists and antagonists suggest that neurones of the mammalian central nervous system possess several different receptors for acidic amino acids3,4, which in turn are coupled to separate conductance mechanisms5. N-methyl-D-aspartic acid (NMDA) is a selective agonist for one of these receptors3,4. The excitatory action of amino acids acting at NMDA receptors is remarkably sensitive to the membrane potential and it has been suggested that the NMDA receptor is coupled to a voltage-sensitive conductance6–9. Recently, patch-clamp experiments have shown the voltage-dependent block by Mg2+ of current flow through ion channels activated by L-glutamate10. We now show using voltage-clamp experiments on mouse spinal cord neurones that the voltage-sensitivity of NMDA action is greatly reduced on the withdrawal of physiological concentrations (∼1 mM) of Mg2+ from the extracellular fluid. This provides further evidence that Mg2+ blocks inward current flow through ion channels linked to NMDA receptors.

2,810 citations


Journal ArticleDOI
04 Oct 1984-Nature
TL;DR: Transcription of the c-fos proto-oncogene is greatly increased within minutes of administering purified growth factors to quiescent 3T3 cells, and this stimulation is the most rapid transcriptional response to peptide growth factors yet described, implying a role for c- fos in cell-cycle control.
Abstract: Transcription of the c-fos proto-oncogene is greatly increased within minutes of administering purified growth factors to quiescent 3T3 cells. This stimulation is the most rapid transcriptional response to peptide growth factors yet described, and implies a role for c-fos in cell-cycle control. Transformation by c-fos may result from a temporal deregulation of this control.

2,762 citations


Journal ArticleDOI
31 May 1984-Nature
TL;DR: The complete 1,210-amino acid sequence of the human epidermal growth factor (EGF) receptor precursor, deduced from cDNA clones derived from placental and A431 carcinoma cells, reveals close similarity between the entire predicted ν-erb-B mRNA oncogene product and the receptor transmembrane and cytoplasmic domains.
Abstract: The complete 1,210-amino acid sequence of the human epidermal growth factor (EGF) receptor precursor, deduced from cDNA clones derived from placental and A431 carcinoma cells, reveals close similarity between the entire predicted v-erb-B mRNA oncogene product and the receptor transmembrane and cytoplasmic domains. A single transmembrane region of 23 amino acids separates the extracellular EGF binding and cytoplasmic domains. The receptor gene is amplified and apparently rearranged in A431 cells, generating a truncated 2.8-kilobase mRNA which encodes only the extracellular EGF binding domain.

2,657 citations


Journal ArticleDOI
26 Jan 1984-Nature
TL;DR: Early studies suggested that simple ecosystems were less stable than complex ones, but later studies came to the opposite conclusion as discussed by the authors. Confusion arose because of the many different meanings of "complexity" and "stability".
Abstract: Early studies suggested that simple ecosystems were less stable than complex ones, but later studies came to the opposite conclusion. Confusion arose because of the many different meanings of ‘complexity’ and ‘stability’. Most of the possible questions about the relationship between stability–complexity have not been asked. Those that have yield a variety of answers.

2,519 citations


Journal ArticleDOI
01 Jan 1984-Nature
TL;DR: Preincubation of T4+ lymphocytes with three individual monoclonal antibodies directed at the T4 glycoprotein blocked cell infection by LAV, strongly support the view that a surface molecule directly involved in cellular functions acts as, or is related to, the receptor for a human retrovirus.
Abstract: Many viruses, including retroviruses, are characterized by their specific cell tropism. Lymphadenopathy-associated virus (LAV) is a human lymphotropic retrovirus isolated from patients with acquired immune deficiency syndrome (AIDS) or related syndromes, that displays selective tropism for a subset of T lymphocytes defined by the expression of a surface glycoprotein of relative molecular mass 62,000 (62K) termed T4 (refs 6-8). This glycoprotein delineates a subset of T lymphocytes with mainly helper/inducer functions, while T lymphocytes of the reciprocal subset express a glycoprotein termed T8, have mainly cytotoxic/suppressor activities, and are unable to replicate LAV. Such a tropism may be controlled at the genomic level by regulatory sequences, as described for the human T-cell leukaemia viruses HTLV-I and -II (refs 2, 3). Alternatively or concomitantly, productive cell infection may be controlled at the membrane level, requiring the interaction of a specific cellular receptor with the virus envelope, as demonstrated recently for Epstein-Barr virus (EBV). Therefore, we have investigated whether the T4 molecule itself is related to the receptor for LAV. We report here that preincubation of T4+ lymphocytes with three individual monoclonal antibodies directed at the T4 glycoprotein blocked cell infection by LAV. This blocking effect was specific, as other monoclonal antibodies--such as antibody to histocompatibility locus antigen (HLA) class II or anti-T-cell natural killer (TNK) target--directed at other surface structures strongly expressed on activated cultured T4+ cells, did not prevent LAV infection. Direct virus neutralization by monoclonal antibodies was also ruled out. These results strongly support the view that a surface molecule directly involved in cellular functions acts as, or is related to, the receptor for a human retrovirus.

Journal ArticleDOI
01 Feb 1984-Nature
TL;DR: Six peptides derived from the human epidermal growth factor receptor very closely matches a part of the deduced sequence of the v-erb-B transforming protein of avian erythroblastosis virus (AEV).
Abstract: Each of six peptides derived from the human epidermal growth factor (EGF) receptor very closely matches a part of the deduced sequence of the v-erb-B transforming protein of avian erythroblastosis virus (AEV). In all, the peptides contain 83 amino acid residues, 74 of which are shared with v-erb-B. The AEV progenitor may have acquired the cellular gene sequences of a truncated EGF receptor (or closely related protein) lacking the external EGF-binding domain but retaining the transmembrane domain and a domain involved in stimulating cell proliferation. Transformation of cells by AEV may result, in part, from the inappropriate acquisition of a truncated EGF receptor from the c-erb-B gene.

Journal ArticleDOI
28 Jun 1984-Nature
TL;DR: The authors showed that the isotopic mantle anomaly is globe-encircling in extent, centred on latitude 30° S. They also showed that this mantle anomaly has been in existence for billions of years and placed severe constraints on mantle convection models.
Abstract: Basalts from many Southern Hemisphere regions have anomalous Sr and Pb isotopic characteristics. This article shows that the isotopic mantle anomaly is globe-encircling in extent, centred on latitude 30° S. Arguments suggesting that this mantle anomaly has been in existence for billions of years place severe constraints on mantle convection models.

Journal ArticleDOI
19 Jul 1984-Nature
TL;DR: The complete (172,282 base pairs) nucleotide sequence of the B95-8 strain of Epstein–Barr virus has been established using the dideoxynucleotide/M13 sequencing procedure.
Abstract: The complete (172,282 base pairs) nucleotide sequence of the B95-8 strain of Epstein-Barr virus has been established using the dideoxynucleotide/M13 sequencing procedure. Many RNA polymerase II promoters have been mapped and the mRNAs from these promoters have been assigned to the latent or early/late productive virus cycles. Likely protein-coding regions have been identified and three of these have been shown to encode a ribonucleotide reductase, a DNA polymerase and two surface glycoproteins.

Journal ArticleDOI
01 Jan 1984-Nature
TL;DR: The amplitude of the N400 component of the e.r.p.ps was found to be an inverse function of the subject's expectancy for the terminal word as measured by its ‘Cloze probability’, which suggests N400 may reflect processes of semantic priming or activation.
Abstract: The neuroelectric activity of the human brain that accompanies linguistic processing can be studied through recordings of event-related potentials (erp components) from the scalp The erps triggered by verbal stimuli have been related to several different aspects of language processing For example, the N400 component, peaking around 400 ms post-stimulus, appears to be a sensitive indicator of the semantic relationship between a word and the context in which it occurs Words that complete sentences in a nonsensical fashion elicit much larger N400 waves than do semantically appropriate words or non-semantic irregularities in a text In the present study, erps were recorded in response to words that completed meaningful sentences The amplitude of the N400 component of the erp was found to be an inverse function of the subject's expectancy for the terminal word as measured by its 'Cloze probability' In addition, unexpected words that were semantically related to highly expected words elicited lower N400 amplitudes These findings suggest N400 may reflect processes of semantic priming or activation

Journal ArticleDOI
01 Dec 1984-Nature
TL;DR: Recombinant tumour necrosis factor can be obtained by expression of its complementary DNA in Escherichia coli and induces the haemorrhagic necrosis of transplanted methylcholanthrene-induced sarcomas in syngeneic mice.
Abstract: Human tumour necrosis factor has about 30% homology in its amino acid sequence with lymphotoxin, a lymphokine that has similar biological properties. Recombinant tumour necrosis factor can be obtained by expression of its complementary DNA in Escherichia coli and induces the haemorrhagic necrosis of transplanted methylcholanthrene-induced sarcomas in syngeneic mice.

Journal ArticleDOI
01 Apr 1984-Nature
TL;DR: In this article, a new method, slit island analysis, is introduced to estimate the fractal dimension, D. The estimate is shown to agree with the value obtained by fracture profile analysis, a spectral method.
Abstract: When a piece of metal is fractured either by tensile or impact loading (pulling or hitting), the fracture surface that is formed is rough and irregular. Its shape is affected by the metal's microstructure (such as grains, inclusions and precipitates, whose characteristic length is large relative to the atomic scale), as well as by ‘macrostructural’ influences (such as the size, the shape of the specimen, and the notch from which the fracture begins). However, repeated observation at various magnifications also reveals a variety of additional structures that fall between the ‘micro’ and the ‘macro’ and have not yet been described satisfactorily in a systematic manner. The experiments reported here reveal the existence of broad and clearly distinct zone of intermediate scales in which the structure is modelled very well by a fractal surface. A new method, slit island analysis, is introduced to estimate the basic quantity called the fractal dimension, D. The estimate is shown to agree with the value obtained by fracture profile analysis, a spectral method. Finally, D is shown to be a measure of toughness in metals.

Journal ArticleDOI
01 May 1984-Nature
TL;DR: The results of blastocyst injection studies using three independently isolated XY embryo-derived cell lines, which produce a very high proportion of live-born animals that are overtly chimaeric, are reported.
Abstract: The recent availability in culture of embryo-derived pluripotential cells which exhibit both a normal karyotype and a high differentiative ability has encouraged us to assess the potential of these cells to form functional germ cells following their incorporation into chimaeric mice We report here the results of blastocyst injection studies using three independently isolated XY embryo-derived cell lines (EK CP1 , EK CC1 1 and EKCC1 2) which produce a very high proportion (greater than 50%) of live-born animals that are overtly chimaeric Seven chimaeric male mice, derived from these three lines, have, so far, proved to be functional germ-line chimaeras

Journal ArticleDOI
01 Oct 1984-Nature
TL;DR: The cold dark matter hypothesis as mentioned in this paper suggests that the dark matter that appears to be gravitationally dominant on all scales larger than galactic cores may consist of axions, stable photinos, or other collisionless particles whose velocity dispersion in the early Universe is so small that fluctuations of galactic size or larger are not damped by free streaming.
Abstract: The dark matter that appears to be gravitationally dominant on all scales larger than galactic cores may consist of axions, stable photinos, or other collisionless particles whose velocity dispersion in the early Universe is so small that fluctuations of galactic size or larger are not damped by free streaming. An attractive feature of this cold dark matter hypothesis is its considerable predictive power: the post-recombination fluctuation spectrum is calculable, and it in turn governs the formation of galaxies and clusters. Good agreement with the data is obtained for a Zeldovich (|δk|2 ∝ k) spectrum of primordial fluctuations.

Journal ArticleDOI
01 Feb 1984-Nature
TL;DR: The development of an immunocytochemical procedure suitable for localizing oestrophilin directly in frozen tissue sections or cells from human and several non-human sources is reported.
Abstract: Although it is widely accepted that specific intracellular receptor proteins are involved in the oestrogenic regulation of gene expression and growth in reproductive tissues, the precise nature of the regulation is poorly understood. Among the unresolved issues are the distribution and dynamics of the oestrogen receptor protein (oestrophilin) in target tissues in the presence and absence of oestrogens and antioestrogens. The use of radio-labelled and unlabelled receptor ligands to detect and measure oestrogen receptors in tissues has been complicated by the presence of other intracellular steroid-binding proteins1 and by the low concentration of receptors in responsive tissues. We report here the development of an immunocytochemical procedure that is suitable for localizing oestrophilin directly in frozen tissue sections or cells from human and several non-human sources. When monoclonal antibodies to oestrophilin were used to detect receptor in various oestrogen-sensitive tissues, specific staining was confined to the nucleus of all stained cells, suggesting that both cytosol and nuclear forms of the receptor protein may reside in the nuclear compartment.

Journal ArticleDOI
01 Oct 1984-Nature
TL;DR: Natural systems from snowflakes to mollusc shells show a great diversity of complex patterns that can be investigated through mathematical models termed ‘cellular automata’, which consist of many identical components, each simple.
Abstract: Natural systems from snowflakes to mollusc shells show a great diversity of complex patterns. The origins of such complexity can be investigated through mathematical models termed ‘cellular automata’. Cellular automata consist of many identical components, each simple., but together capable of complex behaviour. They are analysed both as discrete dynamical systems, and as information-processing systems. Here some of their universal features are discussed, and some general principles are suggested.

Journal ArticleDOI
01 Apr 1984-Nature
TL;DR: It is reported here that the eggs which receive a male pronucleus develop to term but those with two female pronuclei develop only poorly after implantation, suggesting that the cytoplasm of activated eggs is fully competent to support development toterm but not if the genome is entirely of maternal origin.
Abstract: It has been suggested that the failure of parthenogenetic mouse embryos to develop to term is primarily due to their aberrant cytoplasm and homozygosity leading to the expression of recessive lethal genes. The reported birth of homozygous gynogenetic (male pronucleus removed from egg after fertilization) mice and of animals following transplantation of nuclei from parthenogenetic embryos to enucleated fertilized eggs, is indicative of abnormal cytoplasm and not an abnormal genotype of the activated eggs. However, we and others have been unable to obtain such homozygous mice. We investigated this problem further by using reconstituted heterozygous eggs, with haploid parthenogenetic eggs as recipients for a male or female pronucleus. We report here that the eggs which receive a male pronucleus develop to term but those with two female pronuclei develop only poorly after implantation. Therefore, the cytoplasm of activated eggs is fully competent to support development to term but not if the genome is entirely of maternal origin. We propose that specific imprinting of the genome occurs during gametogenesis so that the presence of both a male and a female pronucleus is essential in an egg for full-term development. The paternal imprinting of the genome appears necessary for the normal development of the extraembryonic membranes and the trophoblast.

Journal ArticleDOI
01 Nov 1984-Nature
TL;DR: Cloning and sequence analysis of cDNA for the Electrophorus electricus electroplax sodium channel indicate that this protein exhibits four repeated homology units, which are presumably oriented in a pseudosymmetric fashion across the membrane.
Abstract: Cloning and sequence analysis of cDNA for the Electrophorus electricus electroplax sodium channel indicate that this protein, consisting of 1,820 amino acid residues, exhibits four repeated homology units, which are presumably oriented in a pseudosymmetric fashion across the membrane. Each homology unit contains a unique segment with clustered positively charged residues, which may be involved in the gating structure, possibly in conjunction with negatively charged residues clustered elsewhere.

Journal ArticleDOI
01 Jan 1984-Nature
TL;DR: Stimulation of fibroblasts with serum or purified growth factors leads to a dramatic induction of expression of both c-fos mRNA and protein within a few minutes, followed by activation of c-myc.
Abstract: Stimulation of fibroblasts with serum or purified growth factors leads to a dramatic induction of expression of both c-fos mRNA and protein within a few minutes, followed by activation of c-myc. This suggests that c-fos induction is a primary event and the earliest known effect on gene expression by growth factors.

Journal ArticleDOI
01 Apr 1984-Nature
TL;DR: The bending locus of trypanosome kinetoplast DNA, identified by gel electrophoresis, has tracts of a simple repeat sequence symmetrically distributed about it, with a repeat interval of 10 base pairs.
Abstract: The bending locus of trypanosome kinetoplast DNA, identified by gel electrophoresis, has tracts of a simple repeat sequence (CA5–6 T) symmetrically distributed about it, with a repeat interval of 10 base pairs The analogous bending induced when catabolite gene activating protein binds to its recognition sequence near the promoter of the Escherichia coli lac operon is centred on a site about 5–7 base pairs away from the centre of the protein binding site

Journal ArticleDOI
01 Oct 1984-Nature
TL;DR: The dihydropyridine Ca agonist Bay K 8644 enhances Ca channel current by promoting mode 2, while the Ca antagonists nitrendipine and nimodipine inhibit the current by favouring mode 0.
Abstract: Single cardiac transmembranous Ca channels have three modes of gating behaviour in the absence of drugs, expressed as current records with brief openings (mode 1), with no openings because of channel unavailability (mode 0 or null mode) and with long-lasting openings and very brief closings that appear only rarely (mode 2). The dihydropyridine Ca agonist Bay K 8644 enhances Ca channel current by promoting mode 2, while the Ca antagonists nitrendipine and nimodipine inhibit the current by favouring mode 0.

Journal ArticleDOI
06 Sep 1984-Nature
TL;DR: A point mutation in the simian virus 40 large-T gene, which was generated by mixed oligonucleotide mutagenesis and resulted in the conversion of Lys 128 to Thr, produced a large- T antigen that was detected in the cytoplasm but not the nucleus of cells.
Abstract: A point mutation in the simian virus 40 large-T gene, which was generated by mixed oligonucleotide mutagenesis and resulted in the conversion of Lys 128 to Thr, produced a large-T antigen that was detected in the cytoplasm but not the nucleus of cells Deletions within the surrounding sequence Lys-128Lys-Lys-Arg-Lys-Val-Glu also produce cytoplasmic large-T and define a region of the protein involved in nuclear location

Journal ArticleDOI
01 Mar 1984-Nature
TL;DR: A cloned and sequenced a human mRNA specific for mammalian T-lymphoid cells found to be expressed in human and murine T lymphoblasts, thymocytes and phytohaemagglutinin-stimulated T lymphocytes suggests that the cDNA clone may correspond to a message that specifies part of the human T-cell receptor.
Abstract: We have cloned and sequenced a human mRNA specific for mammalian T-lymphoid cells The message was found to be expressed in human and murine T lymphoblasts, thymocytes and phytohaemagglutinin-stimulated T lymphocytes The protein deduced from the cDNA sequence has a molecular weight of 34,938 and shows extensive similarity to the entire length of the variable, joining and constant regions of mammalian immunoglobulin light chains In addition, the relative positions of the cysteine residues are similar to those of the light chains of murine and human immunoglobulin molecules These properties suggest that the cDNA clone may correspond to a message that specifies part of the human T-cell receptor

Journal ArticleDOI
01 Mar 1984-Nature
TL;DR: Cryo-electron microscopy of vitrified specimens offers possibilities for high resolution observations that compare favourably with any other electron microscopical method.
Abstract: Thin vitrified layers of unfixed, unstained and unsupported virus suspensions can be prepared for observation by cryo-electron microscopy in easily controlled conditions. The viral particles appear free from the kind of damage caused by dehydration, freezing or adsorption to a support that is encountered in preparing biological samples for conventional electron microscopy. Cryo-electron microscopy of vitrified specimens offers possibilities for high resolution observations that compare favourably with any other electron microscopical method.

Journal ArticleDOI
01 Oct 1984-Nature
TL;DR: The motion of the Indian plate is determined in an absolute frame of reference and compared with the position of the southern margin of Eurasia deduced from palaeomagnetic data in Tibet as discussed by the authors.
Abstract: The motion of the Indian plate is determined in an absolute frame of reference and compared with the position of the southern margin of Eurasia deduced from palaeomagnetic data in Tibet. The 2,600±900 km of continental crust shortening observed is shown to have occurred in three different episodes: subduction of continental crust, intracontinental thrusting and internal deformation, and lateral extrusion. The detailed chronology of the collision and plate reorganizations in the Indian and Pacific oceans supports the hypothesis that slab-pull is a dominant driving mechanism of plate tectonics.