Showing papers in "Science in 1970"
TL;DR: On the basis of analytical chemical data for numerous rain, river, lake, and ocean samples, the three major mechanisms controlling world surface water chemistry can be defined as atmospheric precipitation, rock dominance, and the evaporation-crystallization process.
Abstract: On the basis of analytical chemical data for numerous rain, river, lake, and ocean samples, the three major mechanisms controlling world surface water chemistry can be defined as atmospheric precipitation, rock dominance, and the evaporation-crystallization process.
2,885 citations
TL;DR: Plasminogen was prepared from human plasma by affinity chromatography on L-lysine-substituted Sepharose with a specific activity of 100 caseinolytic units per milligram of nitrogen.
Abstract: Plasminogen was prepared from human plasma by affinity chromatography on L-lysine-substituted Sepharose. Thirty milligrams of plasminogen, with a specific activity of 100 caseinolytic units (Committee on Thrombolytic Agents) per milligram of nitrogen, were obtained from 340 milliliters of plasma. This corresponds to over 200-fold purification from plasma. Disc-gel electrophoresis at pH 8.3 indicated seven distinct bands, all of which contained activity.
2,051 citations
TL;DR: The foregoing requirements provide an explanation for self-nonself discrimination, which involves a specific deletion in the activity of both the humoral- and the carrier-antigen-sensitive cells.
Abstract: 1) Induction of humoral antibody formation involves the obligatory recognition of two determinants on an antigen, one by the receptor antibody of the antigen-sensitive cell and the other by carrier antibody (associative interaction). 2) Paralysis of antibody formation involves the obligatory recognition of only one determinant by the receptor antibody of the antigen-sensitive cell; that is, a nonimmunogenic molecule (a hapten) can paralyze antigen-sensitive cells. 3) There is competition between paralysis and induction at the level of the antigen-sensitive cell. 4) The mechanisms of low- and high-zone paralysis, and maintenance of the unresponsive state, are identical. 5) High-zone paralysis occurs when both the carrier antibody and the receptor antibody are saturated, so that associated interactions cannot take place. 6) The mechanisms of paralysis and induction for the carrier-antigen-sensitive cell are identical to those for the humoral-antigen-sensitive cell. 7) The formation of carrier-antigen-sensitive cells is thymus-dependent, whereas humoral-antigen-sensitive cells are derived from bone marrow. Since carrier antibody is required for induction, all antigens are thymus-dependent. 8) The interaction of antigen with the receptor antibody on an antigen-sensitive cell results in a conformational change in an invariant region of the receptor and consequently paralyzes the cell. As the receptor is probably identical to the induced antibody, all antibody molecules are expected to be able to undergo a conformational change on binding a hapten. The obligatory associated recognition by way of carrier antibody (inductive signal) involves a conformational change in the carrier antibody, leading to a second signal to the antigen-sensitive cell. 9) The foregoing requirements provide an explanation for self-nonself discrimination. Tolerance to self-antigens involves a specific deletion in the activity of both the humoral- and the carrier-antigen-sensitive cells.
1,701 citations
TL;DR: The rate-determining step in the oxidation of iron pyrite and the formation of acidity in streams associated with coal and copper mines isThe oxidation of ferrous iron, and effective pollution abatement necessitates control ling this reaction.
Abstract: The rate-determining step in the oxidation of iron pyrite and the formation of acidity in streams associated with coal and copper mines is the oxidation of ferrous iron. Effective pollution abatement necessitates control ling this reaction.
1,655 citations
1,533 citations
TL;DR: A polypeptide, which has potent and diverse biological action—including systemic vasodilation, hypotension, increased cardiac output, respiratory stimulation, and hyperglycemia—was isolated from the small intestine of the hog.
Abstract: A polypeptide, which has potent and diverse biological action-including systemic vasodilation, hypotension, increased cardiac output, respiratory stimulation, and hyperglycemia-was isolated from the small intestine of the hog. The peptide has 28 amino acid residues and is chemically distinct from the kinins, "substance P," glucagon, and secretin.
1,520 citations
TL;DR: The circumscription theory in its elaborated form explains why states arose where they did, and why they failed to arise elsewhere, and shows the state to be a predictable response to certain specific cultural, demographic, and ecological conditions.
Abstract: In summary, then, the circumscription theory in its elaborated form goes far toward accounting for the origin of the state. It explains why states arose where they did, and why they failed to arise elsewhere. It shows the state to be a predictable response to certain specific cultural, demographic, and ecological conditions. Thus, it helps to elucidate what was undoubtedly the most important single step ever taken in the political evolution of mankind.
1,409 citations
Journal Article•
1,335 citations
TL;DR: After prolonged exposure to their reflected images in mirrors, chimpanzees marked with red dye showed evidence of being able to recognize their own reflections, and monkeys did not appear to have this capacity.
Abstract: After prolonged exposure to their reflected images in mirrors, chimpanzees marked with red dye showed evidence of being able to recognize their own reflections. Monkeys did not appear to have this capacity.
1,329 citations
1,086 citations
TL;DR: Hybridization of radioactive nucleic acids with the DNA of cytological preparations shows that the sequences of mouse satellite DNA are located in the centromeric heterochromatin of the mouse chromosomes.
Abstract: Hybridization of radioactive nucleic acids with the DNA of cytological preparations shows that the sequences of mouse satellite DNA are located in the centromeric heterochromatin of the mouse chromosomes. Other types of heterochromatin in the cytological preparations do not contain satellite DNA.
TL;DR: The changes in membrane potentials indicate the likelihood of widespread changes in the properties of the cell membrane, for example, changes in Na+ and K+ transport and distribution.
Abstract: The hypothesis advanced in this article requires further validation. Undoubtedly it will require modification as our knowledge of biochemical control increases. Nevertheless, it should prove useful in focusing attention on the apparent similarity in the response of a large number of specific cell types to particular stimuli. Emphasis has been placed on a few common and apparently key elements in these responses. It is recognized that other factors are undoubtedly involved. Specifically, the changes in membrane potentials indicate the likelihood of widespread changes in the properties of the cell membrane, for example, changes in Na(+) and K(+) transport and distribution. These aspects of cellular responses may eventually prove to be of equal or greater importance than those common aspects of the system already identified.
TL;DR: When an extraneous sound (such as a cough or tone) completely replaces a speech sound in a recorded sentence, listeners believe they hear the missing sound.
Abstract: When an extraneous sound (such as a cough or tone) completely replaces a speech sound in a recorded sentence, listeners believe they hear the missing sound. The extraneous sound seems to occur during another portion of the sentence without interfering with the intelligibility of any phoneme. If silence replaces a speech sound, the gap is correctly localized and the absence of the speech sound detected.
TL;DR: For instance, this paper described the linguistic differences between aphasias resulting from brain damage in different anatomical locations and outlined a theory of the organization of language in the brain, which has been the only one which has permitted the prediction of new phenomena or has been able to account for new observations.
Abstract: The study of the organization of the brain for language has been based of necessity on investigations in man. The bulk of our information in this area has come from careful studies of patients suffering from isolated damage as a result of vascular disease, whose brains have, after death, been subjected to careful anatomical examination. Disorders of language resulting from brain damage, almost always on the left side, are called aphasias. Carl Wernicke, nearly 100 years ago. described the linguistic differences between aphasias resulting from damage in different anatomical locations and outlined a theory of the organization of language in the brain. Not only have Wernicke’s localizations stood up under repeated examinations but his theory has been the only one which has permitted the prediction of new phenomena, or has been able to account for new observations. Several remarkable disorders, such as isolated disturbances of reading and the symptomatology of the corpus callosum, are examples of the explanatory power of this theory.
TL;DR: The most interesting developments in semiconductor physics that have occurred in the last few years and that are anticipated in the next few years appear to lie in the realm between physics and chemistry as mentioned in this paper.
Abstract: Many of the most interesting developments in semiconductor physics that have occurred in the last few years and that are anticipated in the next few years appear to lie in the realm between physics and chemistry. In this article I have tried to show how this realm can be treated accurately and realistically within the framework of theory.
TL;DR: The diversity of a planktonic foraminiferal assemblage on the ocean floor depends on the state of preservation of that assemblages, and as dissolution progresses, species diversity decreases, but compound diversity first increases and then decreases; species dominance first decreases and then increases.
Abstract: The diversity of a planktonic foraminiferal assemblage on the ocean floor depends on the state of preservation of that assemblage. As dissolution progresses, species diversity (number of species in the assemblage) decreases, but compound diversity (based on relative species abundance) first increases and then decreases; species dominance first decreases and then increases. The reason for these changes is that the species most susceptible to solution deliver moresediment to the ocean floor than do species with solution-resistant shells, possibly because the more soluble tests are produced in surface waters, where growth and production are greatest.
TL;DR: Silicon, a relatively unknown trace element in nutritional research, has been uniquely localized in active calcification sites in young bone and is suggested to be associated with calcium in an early stage of calcification.
Abstract: Silicon, a relatively unknown trace element in nutritional research, has been uniquely localized in active calcification sites in young bone. Silicon increases directly with calcium at relatively low calcium concentrations and falls below the detection limit at compositions approaching hydroxyapatite. It is suggested that silicon is associated with calcium in an early stage of calcification.
TL;DR: α-Amanitin, a toxic substance from the mushroom Amanita phalloides, is a potent inhibitor of DNA-dependent RNA polymerase II (the nucleoplasmic form) from sea urchin, rat liver, and calf thymus.
Abstract: alpha-Amanitin, a toxic substance from the mushroom Amanita phalloides, is a potent inhibitor of DNA-dependent RNA polymerase II (the nucleoplasmic form) from sea urchin, rat liver, and calf thymus. This compound exerts no effect on the activity of polymerase I (nucleolar form) or polymerase III (also nucleoplasmic). The inhibition is due to a specific interaction with polymerase II or with a complex of DNA and polymerase II.
TL;DR: It is interesting that plants can eventually acclimate fully in response to low temperatures in the absence of inductive photoperiods, and this suggests that there is more than one route to resistance or more thanone ignition key to start the machinery.
Abstract: It is interesting that plants can eventually acclimate fully in response to low temperatures in the absence of inductive photoperiods (67). This suggests that there is more than one route to resistance or more than one ignition key to start the machinery. In either case, the ability of plants to acclimate in response to more than one environmental stimulus provides adaptive flexibility which enhances survival potential.
TL;DR: Experiments in vitro indicate that norepinephrine, not serotonin, regulates the activity of N-acetyl-transferase through a highly specific receptor.
Abstract: The activity of N-acetyltransferase in the rat pineal gland is more than 15 times higher at night than during the day. This circadian rhythm persists in complete darkness, or in blinded animals, and is suppressed in constant lighting. The N-acetyltransferase rhythm is 180 degrees out of phase with the serotonin rhythm and is similar to the norepinephrine and melatonin rhythms. Experiments in vitro indicate that norepinephrine, not serotonin, regulates the activity of N-acetyl-transferase through a highly specific receptor.
TL;DR: Comparison with laboratory measurements on meteorites and Apollo 11 samples indicates that the surface of Vesta has a composition very similar to that of certain basaltic achondrites.
Abstract: The spectral reflectivity (0.30 to 1.10 microns) of several asteroids has been measured for the first time. The reflection spectrum for Vesta contains a strong absorption band centered near 0.9 micron and a weaker absorption feature between 0.5 and 0.6 micron. The reflectivity decreases strongly in the ultraviolet. The reflection spectrum for the asteroid Pallas and probably for Ceres does not contain the 0.9-micron band. Vesta shows the strongest and best-defined absorption bands yet seen in the reflection spectrum for the solid surface of an object in the solar system. The strong 0.9-micron band arises from electronic absorptions in ferrous iron on the M2 site of a magnesian pyroxene. Comparison with laboratory measurements on meteorites and Apollo 11 samples indicates that the surface of Vesta has a composition very similar to that of certain basaltic achondrites.
TL;DR: Auditory potentials recorded from the vertex of humans by a modified averaging technique have very short latencies and are probably generated by brain stem structures located at a considerable distance from the recording point.
Abstract: Auditory potentials recorded from the vertex of humans by a modified averaging technique have very short latencies and are probably generated by brain stem structures located at a considerable distance from the recording point. The evoked waves, which shOW considerable detail and consistency within and across subjects, may be clinically useful in evaluating subcortical function.
TL;DR: It is argued that selection is both the primary cohesive and disruptive force in evolution, and that the selective regime itself determines what influence gene flow (or isolation) will have.
Abstract: Most contemporary biologists think of species as evolutionary units held together by gene flow. For instance Mayr (1) writes \"The nonarbitrariness of the biological species is the result of ... internal cohesion of the gene pool.\" Merrell (2) states \"The species is a natural biological unit tied together by bonds of mating and sharing a common gene pool.\" This idea is founded in the pioneering work of Dobzhansky, Mayr, Stebbins, and others integrating the theory of population genetics with laboratory and field experiments and observations to produce the neo-Darwinian or synthetic theory of evolution. These workers quite logically concluded that differentiation of populations would be prevented by gene flow, and they focused their discussions of speciation on various means of interrupting that flow. In other words, they emphasized the role of mechanisms isolating populations from one another. Until quite recently there has been little reason to question this view. In the past few years, however, growing evidence from field experiments has led us to reevaluate the processes leading to organic diversity, and to conclude that a revision of this section of evolutionary theory is in order. In this paper we suggest that many, if not most, species are not evolutionary units, except in the sense that they (like genera, families, and so forth) are products of evolution. We will argue that selection is both the primary cohesive and disruptive force in evolution, and that the selective regime itself determines what influence gene flow (or isolation) will have. Threefold evidence is presented for this. We will show that (i) gene flow in nature is much more restricted than commonly thought; (ii) populations that have been completely
TL;DR: Theoretical and experimental studies indicate that, with a high-resolution scanning electron microscope, it is now possible to obtain pictures of a single heavy atom resting on a thin carbon substrate.
Abstract: Theoretical and experimental studies indicate that, with a high-resolution scanning electron microscope, it is now possible to obtain pictures of a single heavy atom resting on a thin carbon substrate.
TL;DR: Oxygen consumption, heart rate, skin resistance, and electroenceph-alograph measurements were recorded before, during, and after subjects practiced a technique called transcendental meditation as mentioned in this paper.
Abstract: Oxygen consumption, heart rate, skin resistance, and electroenceph-alograph measurements were recorded before, during, and after subjects practiced a technique called transcendental meditation There were significant changes between the control period and the meditation period in all measurements During meditation, oxygen consumption and heart rate decreased, skin resistance increased, and the electroencephalogram showed specific changes in certain frequencies These results seem to distinguish the state produced by transcendental meditation from commonly encountered states of consciousness and suggest that it may have practical applications
TL;DR: It is proposed that a critical body weight may trigger each of the major events of adolescence, initiation of the weight growth spurt and maximum rate of weight gain, which occur at an invariant mean weight.
Abstract: Height and weight at menarche were found for each subject in three longitudinal growth studies. Early and late maturing girls have menarche at the same mean weight, but late maturers are taller at menarche. Two other major events of adolescence, initiation of the weight growth spurt and maximum rate of weight gain, also occur at an invariant mean weight. The hypothesis is proposed that a critical body weight may trigger each of these adolescent events. Such an interaction would explain the secular trend to an earlier menarche.
TL;DR: In the case of the salmon, the danger of prejudicing future population studies by the artificial transfer of fish from one area to another was highlighted by the authors of the meeting as well as guidelines to future work as mentioned in this paper.
Abstract: ber of the highlights of the meeting as well as guidelines to future work. One important point, a negative one, was the danger, especially in the case of the salmon, of prejudicing future population studies by the artificial transfer of fish from one area to another. Another, a positive one, was the need to validate the genetic basis of what are essentially studies of phenotypes, by carrying out breeding experiments with every species for which this is possible. The Council (ICES) resolved to publish the papers and the discussions following them in their Rapports et Proces-verbauix des Reunions. A. E. MOURANT Serological Popuilation Genetics Laboratory, St. Bartholomew's Hospital, Lonzdonz E.C.1, England
TL;DR: Habituation and dishabituation were not due to peripheral changes in either the sensory receptors or the gill musculature butt but were caused by changes in the amplitlude of the excitatory synaptic potentials produced at the gills motor neurons.
Abstract: We have examinived the nieural correlates of habittuatiotn atid dishabitiuation of tlhe gill-withdrwal reflex in Aplysia. We obtained intracelllular recordings from identified gill motor neurons in the abdominal ganglionz of a semi-intact preparation of Aplysia wlhile we simultaneously recorded behavior responises of the gill. Habituation and dishabituation were not due to peripheral changes in either the sensory receptors or the gill musculature butt were caused by changes in the amplitlude of the excitatory synaptic potentials produced at the gill motor neurons.
TL;DR: Antibodies to early antigens were detected by indirect immunofluorescence in serums of many patients with infectious mononucleosis, Burkitt's lymphoma, or nasopharyngeal carcinoma, and possibly reflect current or recent disease processes that are associated with the virus.
Abstract: Inoculation of 64-10 or Raji cultures with Epstein-Barr virus derived from the HRI-K clone of the P3J Burkitt's lymphoma line caused abortive infections in most of the lymphoblastoid cells with synthesis of "early antigens" but few, if any, capsids. Antibodies to early antigens were detected by indirect immunofluorescence in serums of many patients with infectious mononucleosis, Burkitt's lymphoma, or nasopharyngeal carcinoma. These antibodies were rarely present in other serums even though some of them showed high titers of antibodies to Epstein-Barr virus when assayed on EB3 Burkitt tumor cells; they also prevented synthesis of early antigens, provided the serums were mixed with the virus prior to inoculation. Antibodies to early antigens possibly reflect current or recent disease processes that are associated with the virus.
TL;DR: Elongated receptive fields of cells in the visual cortex were horizontally or vertically oriented—no oblique fields were found and units with horizontal fields were activated only by the eye exposed to horizontal lines; units with vertical fieldsonly by the eyes exposed to vertical lines.
Abstract: Cats were raised from birth with one eye viewing horizontal lines and one eye viewing vertical lines. Elongated receptive fields of cells in the visual cortex were horizontally or vertically oriented—no oblique fields were found. Units with horizontal fields were activated only by the eye exposed to horizontal lines; units with vertical fields only by the eye exposed to vertical lines.