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Showing papers in "Nature in 1977"


Journal ArticleDOI
01 May 1977-Nature

6,044 citations


Journal ArticleDOI
01 Jun 1977-Nature
TL;DR: A review of dielectric data for a wide range of solids proves the existence of a remarkable "universality" of frequency and time responses which is essentially incompatible with the multiplicity of currently accepted detailed interpretations as discussed by the authors.
Abstract: A review of dielectric data for a wide range of solids proves the existence of a remarkable ‘universality’ of frequency and time responses which is essentially incompatible with the multiplicity of currently accepted detailed interpretations. Certain unique features of the universal behaviour strongly suggest the dominant role of many-body interactions.

4,234 citations


Journal ArticleDOI
21 Apr 1977-Nature
TL;DR: Results presented below indicate that immobility is reduced by different treatments known to be therapeutic in depression including three drugs, iprindole, mianserin and viloxazine which although clinically active show little or no ‘antidepressant’ activity in the usual animal tests.
Abstract: A MAJOR problem in the search for new antidepressant drugs is the lack of animal models which both resemble depressive illness and are selectively sensitive to clinically effective antidepressant treatments. We have been working on a new behavioural model in the rat which attempts to meet these two requirements. The method is based on the observation that a rat, when forced to swim in a situation from which there is no escape, will, after an initial period of vigorous activity, eventually cease to move altogether making only those movements necessary to keep its head above water. We think that this characteristic and readily identifiable behavioural immobility indicates a state of despair in which the rat has learned that escape is impossible and resigns itself to the experimental conditions. This hypothesis receives support from results presented below which indicate that immobility is reduced by different treatments known to be therapeutic in depression including three drugs, iprindole, mianserin and viloxazine which although clinically active1–3 show little or no ‘antidepressant’ activity in the usual animal tests4–6.

4,172 citations


Journal ArticleDOI
09 Jun 1977-Nature
TL;DR: It is concluded that the opioid peptidergic system has agonists of different characteristics which interact with more than one type of receptor.
Abstract: Opioid peptides were assayed by inhibition of 3H-naloxone and 3H-leu-enkephalin binding in brain homogenates and by depression of contractions of the guinea pig ileum and mouse vas deferens. We conclude that the opioid peptidergic system has agonists of different characteristics which interact with more than one type of receptor.

2,443 citations


Journal ArticleDOI
24 Nov 1977-Nature
TL;DR: The derivation from myeloid leukaemic cells of a leukocyte culture is described here for the first time that by morphological and histochemical criteria clearly and persistently differentiates along the myeloids series without an exogenous source of conditioned medium.
Abstract: ATTEMPTS to develop long-term suspension cultures of human myeloid leukaemic cells have met with limited success. Lymphoblastoid lines carrying the Epstein–Barr virus genome occasionally arise during such attempts but these lymphoid cells originate from contaminating B lymphocytes and not from the leukaemic myeloid cells1. A line established from the pleural fluid of a patient with chronic myeloid leukaemia in blast crisis2 (designated K-562) has no B-cell or T-cell markers3–4 and does not seem to be of lymphoid origin4. Its lack of morphological and histochemical differentiation2–4, however, makes it difficult to determine whether these cells are derived from myeloblasts or more primitive stem cells4. Another less documented cell line (8261) derived from the peripheral blood of a patient with acute myelogenous leukaemia showed apparent morphological and functional differentiation in agar in the presence of a feeder layer of peripheral blood leukocytes but did not differentiate in suspension culture5. Our laboratory previously reported that cultures of differentiating myeloid leukaemic cells can be maintained for several months in suspension culture but only when enriched with conditioned media (CM) from certain monolayer fibroblastic cultures of first trimester whole human embryos (ref. 6 and Ruscetti et al. in preparation). We describe here for the first time the derivation from myeloid leukaemic cells of a leukocyte culture that by morphological and histochemical criteria clearly and persistently differentiates along the myeloid series without an exogenous source of conditioned medium.

2,115 citations


Journal ArticleDOI
01 Dec 1977-Nature
TL;DR: The present report describes the isolation of a cloned population of myogenic cells, derived from adult dystrophic mouse muscle, that can proliferate and differentiate in cell culture.
Abstract: THE muscular dystrophies are a group of hereditary disorders manifested by a progressive wasting of the skeletal muscles. In spite of extensive studies, the nature of the primary lesion is unknown (for review see ref. 1). Because of the complex interaction between tissues, it is difficult to study this question in vivo. Therefore attempts have been made to investigate this question in cultures of dystrophic muscles of human or animal origin. Tissue explants as well as monolayer primary cell cultures contain, in addition to the myogenic cells, a heterogeneous cell population, the composition of which might differ in normal and dystrophic muscle cultures. It is difficult in such experiments to distinguish between properties intrinsic to the myogenic cells and effects exerted by other cell types. Indeed, previous experiments have yielded conflicting conclusions2–6. We therefore tested the possibility of obtaining cell cultures consisting of pure populations of myogenic cells obtained from dystrophic muscles. The present report describes the isolation of a cloned population of such cells, derived from adult dystrophic mouse muscle, that can proliferate and differentiate in cell culture.

2,039 citations


Journal ArticleDOI
24 Feb 1977-Nature
TL;DR: The sequence identifies many of the features responsible for the production of the proteins of the nine known genes of the organism, including initiation and termination sites for the proteins and RNAs.
Abstract: A DNA sequence for the genome of bacteriophage phi X174 of approximately 5,375 nucleotides has been determined using the rapid and simple 'plus and minus' method. The sequence identifies many of the features responsible for the production of the proteins of the nine known genes of the organism, including initiation and termination sites for the proteins and RNAs. Two pairs of genes are coded by the same region of DNA using different reading frames.

2,023 citations


Journal ArticleDOI
16 Jun 1977-Nature
TL;DR: The dynamics of a folded globular protein have been studied by solving the equations of motion for the atoms with an empirical potential energy function and suggest that the protein interior is fluid-like in that the local atom motions have a diffusional character.
Abstract: The dynamics of a folded globular protein (bovine pancreatic trypsin inhibitor) have been studied by solving the equations of motion for the atoms with an empirical potential energy function. The results provide the magnitude, correlations and decay of fluctuations about the average structure. These suggest that the protein interior is fluid-like in that the local atom motions have a diffusional character.

1,840 citations


Journal ArticleDOI
07 Apr 1977-Nature
TL;DR: FUSION between myeloma cells and spleen cells from immunised donors has been shown to be a successful method of deriving homogeneous anti-SRBC (anti-sheep red blood cell) and anti-TNP antibodies.
Abstract: FUSION between myeloma cells and spleen cells from immunised donors has been shown to be a successful method of deriving homogeneous anti-SRBC (anti-sheep red blood cell) and anti-TNP antibodies1,2. One of the most powerful features of this approach is that, by cloning, one may easily derive cell lines synthesising monoclonal antibodies despite using non-purified immunogens. The multiple components of a heterogeneous population of hybrid cells are resolved by cloning techniques. This feature makes the system a very powerful tool in the study of complex antigenic structures. The established cell lines offer the further advantage of unlimited permanent supply of material, and the possibility of worldwide standardisation.

1,749 citations


Journal ArticleDOI
01 Jan 1977-Nature
TL;DR: Bergh and P.J.Dean as discussed by the authors proposed a light-emitting diode (LEDD) for light-aware Diodes, which was shown to have promising performance.
Abstract: Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

1,560 citations


Journal ArticleDOI
24 Nov 1977-Nature
TL;DR: This work has shown that mortality may be due to an energy-saving strategy of reduced error regulation in somatic cells, which supports Orgel's ‘error catastrophe’ hypothesis and offers a new basis for the study of normal and abnormal ageing syndromes and of apparently immortal transformed cell lines.
Abstract: An evolutionary view of ageing suggests that mortality may be due to an energy-saving strategy of reduced error regulation in somatic cells. This supports Orgel's ‘error catastrophe’ hypothesis and offers a new basis for the study of normal and abnormal ageing syndromes and of apparently immortal transformed cell lines.

Journal ArticleDOI
01 Oct 1977-Nature
TL;DR: This review discusses how alternate stable states can arise in simple 1- and 2-species systems, and applies these ideas to grazing systems, to insect pests, and to some human host–parasite systems.
Abstract: Theory and observation indicate that natural multi-species assemblies of plants and animals are likely to possess several different equilibrium points. This review discusses how alternate stable states can arise in simple 1- and 2-species systems, and applies these ideas to grazing systems, to insect pests, and to some human host–parasite systems.

Journal ArticleDOI
21 Apr 1977-Nature
TL;DR: Experiments suggest that another important group of psychoactive drugs, the benzodiazepines, bind to specific receptors on the membranes of rat brain cells, and this suggests that there may be an unknown endogenous neurotransmitter which is the natural ligand for the Benzodiazepine receptor.
Abstract: HIGH affinity binding of tritium labelled morphine and morphine-like drugs to membranes in brain homogenates1–3 was a decisive advance in the characterisation of opiate receptors and the discovery of enkephalines and endorphines We report here experiments which suggest that another important group of psychoactive drugs, the benzodiazepines, bind to specific receptors on the membranes of rat brain cells This suggests that there may be an unknown endogenous neurotransmitter which is the natural ligand for the benzodiazepine receptor The binding sites are distributed unevenly through the brain, and displacement potencies of benzodiazepines correlate with pharmacological effects predictive of anxiolytic activity

Journal ArticleDOI
14 Jul 1977-Nature
TL;DR: An adaptation of this method which allows the long term culture of antigen-selected cytotoxic T cells which continue to demonstrate high levels of syngeneic tumour-specific cytotoxicity after more than 4 months in culture is described.
Abstract: MANY investigators have been successful in the maintenance of long term tissue culture of human bone marrow-derived (B) cells. These cell lines have been established from both normal subjects1 and from patients with lymphoproliferative disorders2. In most cases, long term B-cell lines have been shown to harbour the Epstein–Barr virus genome which some investigators feel is required for establishment and maintenance of long-term cultures3. There are fewer reports describing continuous culture of human thymus derived (T) cell lines, and when successful, the lines have only been established from patients with acute lymphocytic leukaemia4. Although these cell lines have been shown to bear surface markers of normal human T lymphocytes, there have been no reports which suggest that they possess the ability to respond to immunologic stimuli or to differentiate into antigen-specific lymphocytes. Cytotoxic murine T cells have been kept in continuous culture only through repetitive mixed-lymphocyte stimulation5. In contrast to long term human lymphocyte lines, these cells proliferated only when stimulated with allogeneic lymphocytes and eventually died after a few weeks in culture. Morgan, Ruscetti and Gallo recently reported a method by which medium conditioned by phytohaemagglutinin-stimulated normal human lymphocytes allowed for the selective long-term growth of normal T cells6. In contrast to the previously mentioned cell lines, the proliferation of these reported T-cell cultures was totally dependent on the presence of an exogenously-produced growth factor supplied by the conditioned medium. In this report we describe an adaptation of this method which allows the long term culture of antigen-selected cytotoxic T cells which continue to demonstrate high levels of syngeneic tumour-specific cytotoxicity after more than 4 months in culture.

Journal ArticleDOI
01 Oct 1977-Nature
TL;DR: Simple mathematical models show that adaptations for achieving dispersal retain great importance even in uniform and predictable environments and provide a case where the evolutionarily stable dispersal strategy for individuals is suboptimal for the population as a whole.
Abstract: Simple mathematical models show that adaptations for achieving dispersal retain great importance even in uniform and predictable environments. A parent organism is expected to try to enter a high fraction of its propagules into competition for sites away from its own immediate locality even when mortality to such dispersing propagules is extremely high. The models incidentally provide a case where the evolutionarily stable dispersal strategy for individuals is suboptimal for the population as a whole.

Journal ArticleDOI
01 Dec 1977-Nature
TL;DR: It is reported here that selective degeneration of neurones with a highly specific function can be produced by chemical agents in the somatosensory system as well.
Abstract: PHARMACOLOGICALLY evoked selective degeneration of neurones with a specific function or functioning with known transmitter substances, has been reported only in the monoaminergic neurone systems1,2. We report here that selective degeneration of neurones with a highly specific function can be produced by chemical agents in the somatosensory system as well. Capsaicin given to newborn rats induces selective degeneration of a distinct population of primary sensory neurones involved in mediation of chemogenic pain.

Journal ArticleDOI
01 Sep 1977-Nature
TL;DR: In this article, the relative dominance of different burial diagenesis processes within specific depth intervals is given by the isotopic composition of incorporated oxygen which is temperature dependent (1) 0 to −2‰, (2) −1.5 to −5'
Abstract: Organic matter is modified by several processes operating at different depths during burial diagenesis: (1) sulphate reduction; (2) fermentation; (3) thermally-induced decarboxylation, and so on. CO2, one common product of each, can be distinguished by its carbon isotope composition: approximately (1) −25‰, (2) +15‰, (3) −20‰ relative to PDB. These values are preserved in diagenetic carbonates of the Upper Jurassic Kimmeridge Clay. Independent corroboration of the relative dominance of each process within specific depth intervals is given by the isotopic composition of incorporated oxygen which is temperature dependent (1) 0 to −2‰, (2) −1.5 to −5‰,(3) −3.5 to −7.0‰.

Journal ArticleDOI
09 Jun 1977-Nature
TL;DR: It is found that there is no strict correlation between cell morphology and type of collagen synthesised in cartilage colonies kept in monolayer culture at low density.
Abstract: WHEN chondrocytes from sternal or articular cartilage are kept in monolayer culture at low density, they eventually lose their cartilage phenotype1–4. Within four passages or approximately 1 month in culture they change from a polygonal or round to a flattened, amoeboid-like shape5–7, and instead of cartilage collagen (type II collagen8) they synthesise the genetically different type I collagen. It is not known whether there is a strict correlation between the occurrence of cell flattening and the change in collagen synthesis within individual cells. We have reported that preferentially flattened, fibroblast-like cells at the edge of cartilage colonies synthesise type I collagen, whereas round or polygonal chondrocytes generally synthesise type II collagen1–3. The change is nearly complete in a culture at a time when excessive flattening is observed4. Using an immunofluorescence double staining technique9,10, we have now found that there is no strict correlation between cell morphology and type of collagen synthesised.

Journal ArticleDOI
03 Feb 1977-Nature
TL;DR: The culture lifetime of epidermal cells of newborn humans is increased from 50 to 150 generations by adding to the medium epidermis growth factor, a polypeptide mitogen, which seems to delay senescence of the cells by maintaining them in a state further removed from terminal differentiation.
Abstract: The culture lifetime of epidermal cells of newborn humans is increased from 50 to 150 generations by adding to the medium epidermal growth factor, a polypeptide mitogen. EGF seems to delay senescence of the cells by maintaining them in a state further removed from terminal differentiation. This effect is revealed by a greater ability of the cells to survive subculture and initiate new colonies, but not necessarily by an increased growth rate.

Journal ArticleDOI
01 Jun 1977-Nature
TL;DR: In this article, a history of geodynamic evolution of the Mediterranean leading to the salinity crisis is outlined, based on the 'desiccated deep-basin model' and an accurate portrayal of the crisis is presented.
Abstract: A history of geodynamic evolution of the Mediterranean leading to the salinity crisis is outlined, based on the ‘desiccated deep-basin model’. An accurate portrayal of the crisis is presented, based on data from new drilling and studies of on-land geology.

Journal ArticleDOI
11 Aug 1977-Nature
TL;DR: It is reported here that opiate analgesics are able to suppress the stimulus-evoked release of SP, which may represent a mechanism for the direct spinal analgesic actions of opiates.
Abstract: THE undecapeptide substance P (SP) may act as a transmitter released from the terminals of primary sensory nerves in the spinal cord1–2. SP has been shown to be highly concentrated in the terminals of small diameter fibres in the substantia gelatinosa of the dorsal horn in mammalian spinal cord, and these terminals disappear after dorsal root section3–6. Sensory nuclei of some of the cranial nerves, such as the spinal trigeminal nucleus, also contain a high density of SP nerve terminals6–7. SP is released by a calcium-dependent mechanism from the isolated rat spinal cord during electrical stimulation of the dorsal roots8. The peptide is also a powerful excitant of neurones in the spinal cord2, and seems to excite selectively those cells in dorsal horn that respond to noxious stimuli9–10. SP may, therefore, represent the excitatory transmitter, or one of the transmitters, released from primary fibres involved in the transmission of pain. We have examined the stimulus-evoked release of SP from rat spinal trigeminal nucleus slices in vitro to explore the factors which may control its release from primary sensory terminals. We report here that opiate analgesics are able to suppress the stimulus-evoked release of SP. These findings may represent a mechanism for the direct spinal analgesic actions of opiates.

Journal ArticleDOI
22 Sep 1977-Nature
TL;DR: The identification of a 60,000-MW transformation-specific antigen detectable in ASV-transformed chicken cells andASV-induced hamster tumour cells is described by immunoprecipitation of radiolabelled cell extracts with serum from tumour-bearing rabbits.
Abstract: GENETIC analyses of avian sarcoma viruses (ASV) have led to the identification of a gene, designated src, which encodes a product required for the initiation and maintenance of neoplastic transformation in infected fibroblasts1–5. Because the src gene product has not been identified biochemically, this study was initiated to detect a transformation-specific protein, using serum from rabbits bearing ASV-induced tumours. We describe here the identification of a 60,000-MW transformation-specific antigen detectable in ASV-transformed chicken cells and ASV-induced hamster tumour cells by immunoprecipitation of radiolabelled cell extracts with serum from tumour-bearing rabbits. Moreover, the expression of this antigen is temperature dependent in chicken cells transformed by an ASV temperature-sensitive mutant in the src gene. The use of this antiserum may lead to the unequivocal identification and characterisation of the ASV src gene product and this, in turn, may lead to the elucidation of the mechanism of ASV-induced oncogenesis.

Journal ArticleDOI
17 Feb 1977-Nature
TL;DR: The use of heparin is reported here to suppress intimal SMC hyperplasia in a rat model of arterial endothelial injury and possible mechanisms for the heparIn effect are suggested.
Abstract: INTIMAL smooth muscle cell (SMC) proliferation dominates the early phase of healing after arterial endothelial injury1–6; what growth factors are responsible for this mitotic activity of an otherwise quiescent cell is not known. SMC growth in vitro is enhanced by platelet factors, insulin and lipoproteins7–11 and, according to some reports, can be diminished in vivo with various antiplatelet agents. Harker et al.6 have reported decreased myointimal thickening in homocystinaemic baboons treated with dipyridamole, and Friedman et al.11 and Moore et al.12 have reported suppression of SMC proliferation in the injured arteries of rabbits injected with anti-platelet serum. Intimal thickening was not diminished, however, in the injured carotid arteries of rats given various anti-platelet drugs13. Because the clotting system is inextricably linked to arterial injury and because thrombin is used to generate the platelet growth factor9 and may itself be a mitogen14,15, we speculated that heparin might inhibit myointimal thickening. We report here the use of heparin to suppress intimal SMC hyperplasia in a rat model of arterial endothelial injury and suggest possible mechanisms for the heparin effect.

Journal ArticleDOI
01 Apr 1977-Nature
TL;DR: The Blood–Brain Barrier in Physiology and Medicine, by Stanley I. Rapoport.
Abstract: Blood–Brain Barrier in Physiology and Medicine. By Stanley I. Rapoport. Pp. xii + 316. (Raven: New York, 1976.) $28.

Journal ArticleDOI
27 Oct 1977-Nature
TL;DR: It is reported here that macrophages activated in vivo and in vitro, and media conditioned by these cells, induce vascular proliferation in the guinea pig cornea.
Abstract: MICROVASCULAR proliferation is essential to many biological processes, such as wound healing, but the mechanisms underlying this vascular response are poorly understood1. Neovascularisation can be induced by extracts from various cell types, including malignant solid tumour cells2, normal and viral-transformed (SV40) BALB/c 3T3 cells, and diploid human embryonic lung fibroblasts3, and neutrophils4. Extracts of mouse salivary gland5 and skin6 have been reported to induce vascular growth, but the relevance of these observations to the vascular proliferation that occurs in wound healing and chronic inflammation is unclear. Neovascularisation is also an important component of immunological reactions. Sidky and Auerbach reported increased vessel density in the skin during graft-versus-host reactions and attributed it to the lymphocyte7. Herman and associates8 and Anderson et al.9 found an increase in capillary density, and extensive proliferation of postcapillary venular endothelium, respectively, in lymph nodes undergoing strong immunological reactions. We have shown significant endothelial proliferation in delayed hypersensitivity reactions in the skin of guinea pigs at the time of maximal mononuclear cell infiltration10 and so we have investigated whether macrophages, an important component of immunological and non-immunological inflammatory reactions, might be involved in this vascular response. We report here that macrophages activated in vivo and in vitro, and media conditioned by these cells, induce vascular proliferation in the guinea pig cornea.

Journal ArticleDOI
04 Aug 1977-Nature
TL;DR: Rapid, dramatic, and reversible increases in histone acetylation in the presence of n-butyrate are described.
Abstract: LEDER and Leder1 have reported that low concentrations of n-butyrate cause Friend erythroleukaemia cells to begin globin synthesis. Apparently n-butyrate can reverse that part of viral transformation which prevents the expression of differentiation in these cells. Prasad and Sinha2 have summarised the effects of n-butyrate on neuroblastoma, HeLa, and other cell types. They and others3–10 have seen reversible inhibition of proliferation, decrease of DNA content, morphological modifications, and increases in the production of specific enzymes, such as adenylate cyclase, alkaline phosphatase, and a sialyltransferase. The present paper describes rapid, dramatic, and reversible increases in histone acetylation in the presence of n-butyrate.

Journal ArticleDOI
26 May 1977-Nature
TL;DR: Injection of basic magma into acid magma causes superheating of the acid and vigorous convection as discussed by the authors, which can lead to an explosive acid eruption in volcanic edifices.
Abstract: Injection of basic magma into acid magma causes superheating of the acid magma and vigorous convection. Vesiculation induced by convection and increased magma pressure fractures the volcanic edifice triggering an explosive acid eruption. The 1875 plinian eruption of Askja, Iceland is an example of an explosive eruption triggered by magma mixing.

Journal ArticleDOI
04 Aug 1977-Nature
TL;DR: The purpose of the experiments described here was to explore the molecular basis for antidepressant-induced noradrenergic subsensitivity by examining the kinetic properties of the β-ADrenergic receptors in the microsomal suspension of rat brain by using a potent β- adrenergic receptor antagonist 3H-dihydroalprenolol as a radiolabelled ligand, and results indicate that the main mechanism is a reduction in the number of receptors.
Abstract: CONSIDERABLE evidence exists that the tricyclic antidepressant drugs are selective inhibitors of monoamine uptake into monoaminergic nerve terminals1,2. These drugs also potentiate pharmacological responses to the monoamines in both the peripheral and central nervous systems3–6. These effects do not explain the discrepancy between the time-course of the biochemical and pharmacological responses which are elicited by these antidepressant drugs within minutes or hours and their clinical antidepressant action which requires treatment for weeks for efficacy to be reached. Furthermore, desipramine, an antidepressant drug, can potentiate neuronal responses to noradrenaline and dopamine in the caudate nucleus7, although it does not block the catecholamine uptake in this area of the brain1,2. Finally the antidepressant iprindole does not influence noradrenaline turnover8 or metabolism9,10 or its uptake into catecholaminergic neurones11, but is effective in potentiating the responses of single cortical and caudate neurones to monoamines12. Vetulani and his associates13 suggested that the therapeutic action of tricyclic antidepressants may be related to postsynaptic adaptive changes in the sensitivity of the noradrenergic adenylate cyclase receptor system rather than to acute presynaptic events. The purpose of the experiments described here was to explore the molecular basis for antidepressant-induced noradrenergic subsensitivity by examining the kinetic properties of the β-adrenergic receptors in the microsomal suspension of rat brain by using a potent β-adrenergic receptor antagonist 3H-dihydroalprenolol as a radiolabelled ligand14–19. Our results indicate that the main mechanism is a reduction in the number of receptors.

Journal ArticleDOI
13 Jan 1977-Nature
TL;DR: The elastic materials involved include muscle in every case, but only in insect flight is the proportion of the energy stored in the muscle substantial.
Abstract: Storage of strain energy in elastic materials has important roles in mammal running, insect jumping and insect flight. The elastic materials involved include muscle in every case, but only in insect flight is the proportion of the energy stored in the muscle substantial.

Journal ArticleDOI
06 Jan 1977-Nature
TL;DR: The relative quantity of these steroid receptors at the outer surfaces of cells from diverse tissues corresponds well with the capacity of a given cell to accumulate and retain oestrogen.
Abstract: OESTROGENS are more readily accumulated and retained in responsive cells than in cells that are not their targets1. Cytoplasmic macromolecules2 which specifically interact with oestradiol and other steroid hormones seem to mediate transfer of the agonist to the nuclear chromatin, where the complex is believed to promote expression of the phenotypic effects3–6. It is generally assumed that the hormone diffuses passively to “cytoplasmic” receptors which determine the cellular specificity of response7. But some experiments indicate that steroid hormones interact with components of biological membranes and may enter their respective target cells by a membrane-mediated process8–12 which is saturable and temperature-dependent13–17. We have investigated steroid-binding components associated with the plasma membranes of cells isolated from endometrium, liver and intestinal mucosa. Endometrial and liver cells show substantial binding to oestrogen immobilised by covalent linkage to an inert support, while intestinal cells have no such binding sites. The relative quantity of these steroid receptors at the outer surfaces of cells from diverse tissues corresponds well with the capacity of a given cell to accumulate and retain oestrogen.