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Showing papers in "Science in 1980"


Journal ArticleDOI
11 Jan 1980-Science
TL;DR: In a sentence reading task, words that occurred out of context were associated with specific types of event-related brain potentials that elicited a late negative wave (N400).
Abstract: In a sentence reading task, words that occurred out of context were associated with specific types of event-related brain potentials. Words that were physically aberrant (larger than normal) elecited a late positive series of potentials, whereas semantically inappropriate words elicited a late negative wave (N400). The N400 wave may be an electrophysiological sign of the "reprocessing" of semantically anomalous information.

4,226 citations


Journal ArticleDOI
06 Jun 1980-Science
TL;DR: A hypothesis is suggested which accounts for the extinctions and the iridium observations, and the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the Cretaceous and Tertiary limestones, which are chemically similar to each other.
Abstract: Direct physical evidence is presented for an unusual event at exactly the time of extinctions in the planktonic realm. Deep-sea limestones exposed in Italy, Denmark, and New Zealand indicate iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given that this iridium is of extraterrestrial origin, but did not come from a nearby supernova. A hypothesis is set forth which accounts for the extinctions and the iridium observations. One prediction of this hypothesis is verified, that the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the chemically similar Cretaceous and Tertiary limestones.

3,357 citations


Journal ArticleDOI
04 Jan 1980-Science
TL;DR: The role of calcium ions (Ca2+) in cell function is beginning to be unraveled at the molecular level as a result of recent research on calcium-binding proteins and particularly on calmodulin.
Abstract: The role of calcium ions (Ca2+) in cell function is beginning to be unraveled at the molecular level as a result of recent research on calcium-binding proteins and particularly on calmodulin. These proteins interact reversibly with Ca2+ to form a protein . Ca2+ complex, whose activity is regulated by the cellular flux of Ca2+. Many of the effects of Ca2+ appear to be exerted through calmodulin-regulated enzymes.

2,367 citations


Journal ArticleDOI
21 Nov 1980-Science
TL;DR: The microencapsulated islets remained morphologically and functionally intact throughout long-term culture studies lasting over 15 weeks.
Abstract: Single implantation of microencapsulated islets into rats with streptozotocin-induced diabetes corrected the diabetic state for 2 to 3 weeks. The microencapsulated islets remained morphologically and functionally intact throughout long-term culture studies lasting over 15 weeks.

2,344 citations


Journal ArticleDOI
10 Oct 1980-Science
TL;DR: The results indicate that the class of preserved learning skills in amnesia is broader than previously reported and support the hypothesis that such a distinction is honored by the nervous system.
Abstract: Amnesic patients acquired a mirror-reading skill at a rate equivalent to that of matched control subjects and retained it for at least 3 months. The results indicate that the class of preserved learning skills in amnesia is broader than previously reported. Amnesia seems to spare information that is based on rules or procedures, as contrasted with information that is data-based or declarative--"knowing how rather than "knowing that." The results support the hypothesis that such a distinction is honored by the nervous system.

2,204 citations


Journal ArticleDOI
20 Jun 1980-Science
TL;DR: Although a sizable body of knowledge is prerequisite to expert skill, that knowledge must be indexed by large numbers of patterns that, on recognition, guide the expert in a fraction of a second to relevant parts of the knowledge store.
Abstract: Although a sizable body of knowledge is prerequisite to expert skill, that knowledge must be indexed by large numbers of patterns that, on recognition, guide the expert in a fraction of a second to relevant parts of the knowledge store. The knowledge forms complex schemata that can guide a problem's interpretation and solution and that constitute a large part of what we call physical intuition.

2,038 citations


Journal ArticleDOI
25 Jul 1980-Science
TL;DR: Analysis of the cell culture fluid from two new human hepatoma-derived cell lines reveals that 17 of the major human plasma proteins are synthesized and secreted by these cells.
Abstract: Analysis of the cell culture fluid from two new human hepatoma-derived cell lines reveals that 17 of the major human plasma proteins are synthesized and secreted by these cells. One of these cell lines, Hep 3B, also produces the two major polypeptides of the hepatitis B virus surface antigen. When Hep 3B in injected into athymic mice, metastatic hepatocellular carcinomas appear. These cell lines provide experimental models for investigation of plasma protein biosynthesis and the relation of the hepatitis B viru genome to tumorigenicity.

1,918 citations


Journal ArticleDOI
07 Nov 1980-Science
TL;DR: There is now reason to believe, from recent studies, that DNA methylation is a key element in the hierarchy of control mechanisms that govern vertebrate gene function and differentiation.
Abstract: In most higher organisms, DNA is modified after synthesis by the enzymatic conversion of many cytosine residues to 5-methylcytosine. For several years, control of gene activity by DNA methylation has been recognized as a logically attractive possibility, but experimental support has proved elusive. However, there is now reason to believe, from recent studies, that DNA methylation is a key element in the hierarchy of control mechanisms that govern vertebrate gene function and differentiation.

1,907 citations


Journal ArticleDOI
06 Jun 1980-Science
TL;DR: The neonate's preference for the maternal voice suggests that the period shortly after birth may be important for initiating infant bonding to the mother.
Abstract: By sucking on a nonnutritive nipple in different ways, a newborn human could produce either its mother's voice or the voice of another female. Infants learned how to produce the mother's voice and produced it more often than the other voice. The neonate's preference for the maternal voice suggests that the period shortly after birth may be important for initiating infant bonding to the mother.

1,852 citations


Journal ArticleDOI
12 Dec 1980-Science
TL;DR: Findings establish that the human response to light is qualitatively similar to that of other mammals.
Abstract: Bright artificial light suppressed nocturnal secretion of melatonin in six normal human subjects. Room light of less intensity, which is sufficient to suppress melatonin secretion in other mammals, failed to do so in humans. In contrast to the results of previous experiments in which ordinary room light was used, these findings establish that the human response to light is qualitatively similar to that of other mammals.

1,776 citations


Journal ArticleDOI
11 Apr 1980-Science
TL;DR: When tissue cells are cultured on very thin sheets of cross-linked silicone fluid, the traction forces the cells exert are made visible as elastic distortion and wrinkling of this substratum.
Abstract: When tissue cells are cultured on very thin sheets of cross-linked silicone fluid, the traction forces the cells exert are made visible as elastic distortion and wrinkling of this substratum. Around explants this pattern of wrinkling closely resembles the "center effects" long observed in plasma clots and traditionally attributed to dehydration shrinkage.

Journal ArticleDOI
25 Jul 1980-Science
TL;DR: For the first time, a single experimental approach, 16S ribosomal RNA sequence characterization, has been used to develop an overview of phylogenetic relationships in the bacterial world as mentioned in this paper.
Abstract: For the first time a single experimental approach, 16S ribosomal RNA sequence characterization, has been used to develop an overview of phylogenetic relationships in the bacterial world. The techni...

Journal ArticleDOI
14 Nov 1980-Science
TL;DR: Recordings of the alarms played back when predators were absent caused Vervet monkeys to run into trees for leopard alarms, look up for eagle alarms, and look down for snake alarms.
Abstract: Vervet monkeys give different alarm calls to different predators. Recordings of the alarms played back when predators were absent caused the monkeys to run into trees for leopard alarms, look up for eagle alarms, and look down for snake alarms. Adults call primarily to leopards, martial eagles, and pythons, but infants give leopard alarms to various mammals, eagle alarms to many birds, and snake alarms to various snakelike objects. Predator classification improves with age and experience.

Journal ArticleDOI
31 Oct 1980-Science
TL;DR: Evidence of this permits resolution of the long-standing controversy over the neural basis of rhythmic behavior and aids in the identification of this mechanism as a general principle of neural organization applicable to all animals with central nervous systems.
Abstract: Timing of the repetitive movements that constitute any rhythmic behavior is regulated by intrinsic properties of the central nervous system rather than by sensory feedback from moving parts of the body. Evidence of this permits resolution of the long-standing controversy over the neural basis of rhythmic behavior and aids in the identification of this mechanism as a general principle of neural organization applicable to all animals with central nervous systems.

Journal ArticleDOI
01 Feb 1980-Science
TL;DR: Experimental evidence is presented that these preferences can develop even when the exposures are so degraded that recognition is precluded and animal and human subjects readily develop strong preferences for objects that have become familiar through repeated exposures.
Abstract: Animal and human subjects readily develop strong preferences for objects that have become familiar through repeated exposures. Experimental evidence is presented that these preferences can develop even when the exposures are so degraded that recognition is precluded.

Journal ArticleDOI
05 Sep 1980-Science
TL;DR: The methylation of phospholipids is coupled to Ca2+ influx and the release of arachidonic acid, lysophosphatidylcholine, and prostaglandins, resulting in the generation of adenosine 3',5'-monophophate in many cell types, release of histamine in mast cells and basophils, mitogenesis in lymphocytes, and chemotaxis in neutrophils.
Abstract: Many types of cells methylate phospholipids using two methyltransferase enzymes that are asymmetrically distributed in membranes. As the phospholipids are successively methylated, they are translocated from the inside to the outside of the membrane. When catecholamine neurotransmitters, lectins, immunoglobulins or chemotaxic peptides bind to the cell surface, they stimulate the methyltransferase enzymes and reduce membrane viscosity. The methylation of phospholipids is coupled to Ca2+ influx and the release of arachidonic acid, lysophosphatidylcholine, and prostaglandins. These closely associated biochemical changes facilitate the transmission of many signals through membranes, resulting in the generation of adenosine 3',5'-monophophate in many cell types, release of histamine in mast cells and basophils, mitogenesis in lymphocytes, and chemotaxis in neutrophils.

Journal ArticleDOI
18 Apr 1980-Science
TL;DR: The elemental content of neurons of the hippocampus was studied in autopsy-derived brain tissue from three cases of senile dementia (Alzheimer type) and three nondemented elderly controls to suggest that the association of aluminum to Alzheimer's disease extends to the neuronal level.
Abstract: The elemental content of neurons of the hippocampus was studied by a combination of scanning electron microscopy and x-ray spectrometry in autopsy-derived brain tissue from three cases of senile dementia (Alzheimer type) and three nondemented elderly controls. Foci of aluminum were detected within the nuclear region of a high percentage of neurons containing neurofibrillary tangles from the cases of senile dementia as well as the elderly controls. The adjacent normal-appearing neurons from both groups of patients were virtually free of detectable aluminum. These findings suggest that the association of aluminum to Alzheimer's disease extends to the neuronal level.

Journal ArticleDOI
29 Feb 1980-Science
TL;DR: This article summarizes how the theory has evolved since the pioneer studies of James Croll and Milutin Milankovitch, reviews recent evidence that supports the theory, and argues that a major opportunity is at hand to investigate the physical mechanisms by which the climate system responds to orbital forcing.
Abstract: According to the astronomical theory of climate, variations in the earth's orbit are the fundamental cause of the succession of Pleistocene ice ages. This article summarizes how the theory has evolved since the pioneer studies of James Croll and Milutin Milankovitch, reviews recent evidence that supports the theory, and argues that a major opportunity is at hand to investigate the physical mechanisms by which the climate system responds to orbital forcing. After a survey of the kinds of models that have been applied to this problem, a strategy is suggested for building simple, physically motivated models, and a time-dependent model is developed that simulates the history of planetary glaciation for the past 500,000 years. Ignoring anthropogenic and other possible sources of variation acting at frequencies higher than one cycle per 19,000 years, this model predicts that the long-term cooling trend which began some 6000 years ago will continue for the next 23,000 years.

Journal ArticleDOI
12 Dec 1980-Science
TL;DR: The data contradict the hypothesis that differential course-taking accounts for observed sex differences in mathematical ability, but support the hypotheses that these differences are somewhat increased by environmental influences.
Abstract: A substantial sex difference in mathematical reasoning ability (score on the mathematics test of the Scholastic Aptitude Test) in favor of boys was found in a study of 9927 intellectually gifted junior high school students. Our data contradict the hypothesis that differential course-taking accounts for observed sex differences in mathematical ability, but support the hypothesis that these differences are somewhat increased by environmental influences.

Journal ArticleDOI
12 Dec 1980-Science
TL;DR: Two- to threefold variations in sleep length were observed in 12 subjects living on self-selected schedules in an environment free of time cues and the duration of polygraphically recorded sleep episodes was highly correlated with the circadian phase of the body temperature rhythm at bedtime.
Abstract: Two- to threefold variations in sleep length were observed in 12 subjects living on self-selected schedules in an environment free of time cues. The duration of polygraphically recorded sleep episodes was highly correlated with the circadian phase of the body temperature rhythm at bedtime and not with the length of prior wakefulness. Furthermore, the rate of REM (rapid eye movement) sleep accumulation , REM latency, bedtime selection, and self-rated alertness assessments were also correlated with the body temperature rhythm.

Journal ArticleDOI
28 Nov 1980-Science
TL;DR: A backswimmer, Notonecta hoffmanni, was capable of balancing these two conflicting factors adaptively and was able to compare the observed behaviors with predictions derived from fitness considerations.
Abstract: According to much current theory, organisms should be able to balance the conflicting demands of the need to feed efficiently and the need to avoid preadtors while feeding. In an experimental conflict situation, it was possible to evaluate the relative fitnesses associated with the available choices and to compare the observed behaviors with predictions derived from fitness considerations. A backswimmer, Notonecta hoffmanni, was capable of balancing these two conflicting factors adaptively.

Journal ArticleDOI
03 Oct 1980-Science
TL;DR: The decrease in the number of receptor sites is most marked for [3H]spiroperidol-labeled serotonin receptors and is characteristic for antidepressants of several classes.
Abstract: Antidepressants compete at several neurotransmitter receptor binding site, but drug affinities do not correlate with clinical efficacy. Long-term, but not short-term, antidepressant treatment decreases the numbers of both serotonin and beta-adrenergic receptors. The decrease in the number of receptor sites is most marked for [3H]spiroperidol-labeled serotonin receptors and is characteristic for antidepressants of several classes.

Journal ArticleDOI
19 Sep 1980-Science
TL;DR: Sequences which are essential for the initiation of specific transcription in vitro were shown to be located between 12 and 32 base pairs upstream from the 5' end of these genes.
Abstract: In vitro genetic techniques were used to study the sequence requirements for the initiation of specific transcription. Deletion mutants were constructed around the putative promoter of the adenovirus-2 major late and chicken conalbumin genes. Specific transcription in vitro by RNA polymerase B together with a HeLa cell cytoplasmic extract was used as the test for promoter function. With this approach sequences which are essential for the initiation of specific transcription in vitro, were shown to be located between 12 and 32 base pairs upstream from the 59 end of these genes.

Journal ArticleDOI
26 Sep 1980-Science
TL;DR: The concentration of airborne soil dust at Enewetak Atoll in April 1979 was 2.3 micrograms per cubic meter but decreased steadily to 0.02 microgramper cubic meter over the next 5 months, suggesting that the spring dust is probably derived from China.
Abstract: The concentration of airborne soil dust at Enewetak Atoll(11°N, 162°E) in April 1979 was 2.3 micrograms per cubic meter but decreased steadily to 0.02 microgram per cubic meter over the next 5 months. The spring dust is probably derived from China; its deposition rate (∼0.3 millimeter per 1000 years) suggests that it may be a significant contributor to the deep-sea sediments of the North Pacific.

Journal ArticleDOI
05 Dec 1980-Science
TL;DR: Flow cytometry of heated sperm nuclei revealed a significant decrease in resistance to in situ denaturation of spermatozoal DNA in samples from bulls, mice, and humans of low or questionable fertility when compared with others of high fertility.
Abstract: Flow cytometry of heated sperm nuclei revealed a significant decrease in resistance to in situ denaturation of spermatozoal DNA in samples from bulls, mice, and humans of low or questionable fertility when compared with others of high fertility. Since thermal denaturation of DNA in situ depends on chromatin structure, it is assumed that changes in sperm chromatin conformation may be related to the diminished fertility. Flow cytometry of heated sperm nuclei may provide a new and independent determinant of male fertility.

Journal ArticleDOI
18 Jan 1980-Science
TL;DR: Evidence indicates that the benzodiazepines exert their therapeutic effects by interacting with a high-affinity binding site (receptor) in the brain and several naturally occurring compounds, including the purines and nicotinamide, are candidates for this role.
Abstract: Investigation of the actions of the benzodiazepines has provided insights into the neurochemical mechanisms underlying anxiety, seizures, muscle relaxation, and sedation. Behavioral, electrophysical, pharmacological, and biochemical evidence indicates that the benzodiazepines exert their therapeutic effects by interacting with a high-affinity binding site (receptor) in the brain. The benzodiazepine receptor interacts with a receptor for gamma-aminobutyric acid, a major inhibitory neurotransmitter, and enhances its inhibitory effects. The benzodiazepine receptor may also interact with endogenous substances and several naturally occurring compounds, including the purines and nicotinamide, are candidates for this role. Both the purines and nicotinamide possess some benzodiazepine-like properties in vivo, although further work will be required to confirm their possible roles as endogenous benzodiazepines.

Journal ArticleDOI
14 Nov 1980-Science
TL;DR: The limbic potentials reverse polarity over small distances and correlate with unit discharges recorded by the same electrodes, indicating that they are locally generated.
Abstract: Infrequent, attended, auditory and visual stimuli evoke large potentials in the human limbic system in tasks that usually evoke endogenous potentials at the scalp. The limbic potentials reverse polarity over small distances and correlate with unit discharges recorded by the same electrodes, indicating that they are locally generated.

Journal ArticleDOI
30 May 1980-Science
TL;DR: The biosynthesis of the hydroxy, epoxy, and dicarboxylic acids of the polyesters from the common cellular fatty acids is elucidated and the function and possible practical implications of these polyester barriers are briefly discussed.
Abstract: Cutin, a biopolyester composed of hydroxy and epoxy fatty acids, is the barrier between the aerial parts of higher plants and their environment. Suberin a polymer containing aromatics and polyesters, functions as a barrier in underground parts, wound surfaces, and a variety of internal organs. The composition and probable structure of these polymers are discussed. The biosynthesis of the hydroxy, epoxy, and dicarboxylic acids of the polyesters from the common cellular fatty acids is elucidated. An extracellular enzyme transfers the hydroxy and epoxyacyl moieties from their coenzyme A derivatives to the growing polyester. The enzymes acting in the biodegradation of the polyesters have been isolated from fungi, pollen, and mammals and characterized. The function and possible practical implications of these polyester barriers are briefly discussed.

Journal ArticleDOI
25 Jan 1980-Science
TL;DR: Pulse labeling neurons of the hypothalamo-neurohypophysial system with radioactive amino acid indicates that the two hormones and their respective neurophysin carrier proteins are synthesized as parts of separate precursor proteins.
Abstract: Vasopressin and oxytocin are made and released by neurons of the hypothalamo-neurohypophysial system. Pulse labeling these neurons with radioactive amino acid indicates that the two hormones and their respective neurophysin carrier proteins are synthesized as parts of separate precursor proteins. The precursors seem to be processed into smaller, biologically active molecules while they are being transported along the axon.

Journal ArticleDOI
10 Oct 1980-Science
TL;DR: Reduction of the number of axons that contact target cells may be a general feature of neural development and underlie the progressively restricted malleability of the maturing nervous system.
Abstract: Reduction of the number of axons that contact target cells may be a general feature of neural development. This process may underlie the progressively restricted malleability of the maturing nervous system.