Showing papers in "Science in 1979"

Submarine Thermal Springs on the Galápagos Rift

Abstract: The submarine hydrothermal activity on and near the Galapagos Rift has been explored with the aid of the deep submersible Alvin Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galapagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley The vent areas are populated by animal communities They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis

Cognitive deficit caused by regional depletion of dopamine in prefrontal cortex of rhesus monkey.

Abstract: Depletion of dopamine in a circumscribed area of association cortex in rhesus monkeys produces an impairment in spatial delayed alternation performance nearly as severe as that caused by surgical ablation of the same area. This behavioral deficit can be pharmacologically reversed with dopamine agonists such as L-dopa and apomorphine. These data provide direct evidence that dopamine plays an important role in a specific cortical function.

Calcium dependence of toxic cell death: a final common pathway

Abstract: Primary cultures of adult rat hepatocytes were treated in the presence or absence of extracellular calcium with ten different membrane-active toxins. In all cases more than half the cells were killed in 1 to 6 hours in the presence but not in the absence of extracellular calcium. An effect of calcium on the primary mechanism of membrane injury by any of the agents cannot be implicated. Viability, as determined by trypan blue exclusion correlated well with other indices of viability such as plating efficiency and the hydrolysis of fluorescein diacetate. It is concluded that the cells are killed by processes that involve at least two steps. In each type of injury, disruption of the integrity of the plasma membrane by widely differing mechanisms is followed by a common functional consequence involving extracellular calcium, and most likely representing an influx of calcium across the damaged plasma membrane and down a steep concentration gradient. This later step represents, or at least initiates, a final common pathway for the toxic death of these cells.

Monoclonal antibodies defining distinctive human T cell surface antigens

Abstract: Three novel nonoclonal antibodies (designed OKT1, OKT3, and OKT4) were generated against surface determinants of human peripheral T cells. Both OKT1 and OKT3 reacted with all human peripheral T cells and 5 to 10 percent of thymocytes but differed in their reactivities with T cel- lines. By contrast, OKT4 reacted with 55 percent of human peripheral T cells and 80 percent of thymocyted in that they did not react with normal B cells, null cells, monocytes, or granulocytes.

Tree Dispersion, Abundance, and Diversity in a Tropical Dry Forest

Abstract: Patterns of tree abundance and dispersion in a tropical deciduous (dry) forest are summarized. The generalization that tropical trees have spaced adults did not hold. All species were either clumped or randomly dispersed, with rare species more clumped than common species. Breeding system was unrelated to species abundance or dispersion, but clumping was related to mode of seed dispersal. Juvenile densities decreased approximately exponentially away from adults. Rare species gave evidence of poor reproductive performance compared with their performance when common in nearby forests. Patterns of relative species abundance in the dry forest are compared with patterns in other forests, and are explained by a simple stochastic model based on random-walk immigration and extinction set in motion by periodic community disturbance.

A Physical Concept of Soil-Water Equilibria for Nonionic Organic Compounds

Abstract: Soil-water equilibrium data suggest that the transfer of nonionic chemicals from water to soil may be described in terms of a hypothesis of solute partitioning in the soil organic matter. This concept allows estimation of soil-water distribution coefficients either from solvent-water partition coefficients or aqueous solubilities.

Brain grafts reduce motor abnormalities produced by destruction of nigrostriatal dopamine system

Abstract: In order to determine if brain tissue grafts can provide functional input to recipient central nervous system tissue, fetal rat dopamine-containg neurons were implanted adjacent to the caudate nucleus of adult recipients whose endogenous dopaminergic input had been destroyed. The grafts showed good survival and axonal outgrowth. Motor abnormalities, which had been induced by the destruction of the endogenous dopaminergic input to the caudate, were significantly reduced after grafting of the fetal brain tissue. These data suggest that such implants may be potentially useful in reversing deficits after circumscribed destruction of brain tissue.

Determination of the Pore Size of Cell Walls of Living Plant Cells

Abstract: The limiting diameter of pores in the walls of living plant cells through which molecules can freely pass has been determined by a solute exclusion technique to be 35 to 38 angstroms for hair cells of Raphanus sativus roots and fibers of Gossypium hirsutum, 38 to 40 angstroms for cultured cells of Acer pseudoplatanus, and 45 to 52 angstroms for isolated palisade parenchyma cells of the leaves of Xanthium strumarium and Commelina communis. These results indicate that molecules with diameters larger than these pores would be restricted in their ability to penetrate such a cell wall, and that such a wall may represent a more significant barrier to cellular communication than has been previously assumed.

Extreme ultraviolet observations from Voyager 1 encounter with Jupiter

Abstract: The global hydrogen Lyman alpha, helium (584 angstroms), and molecular hydrogen band emissions from Saturn are qualitatively similar to those of Jupiter, but the Saturn observations emphasize that the H(2) band excitation mechanism is closely related to the solar flux. Auroras occur near 80 degrees latitude, suggesting Earth-like magnetotail activity, quite different from the dominant Io plasma torus mechanism at Jupiter. No ion emissions have been detected from the magnetosphere of Saturn, but the rings have a hydrogen atmosphere; atomic hydrogen is also present in a torus between 8 and 25 Saturn radii. Nitrogen emission excited by particles has been detected in the Titan dayglow and bright limb scans. Enhancement of the nitrogen emission is observed in the region of interaction between Titan's atmosphere and the corotating plasma in Saturn's plasmasphere. No particle-excited emission has been detected from the dark atmosphere of Titan. The absorption profile of the atmosphere determined by the solar occultation experiment, combined with constraints from the dayglow observations and temperature information, indicate that N(2) is the dominant species. A double layer structure has been detected above Titan's limb. One of the layers may be related to visible layers in the images of Titan.

Keilin's respiratory chain concept and its chemiosmotic consequences.

Abstract: It was obviously my hope that the chemiosmotic rationale of vectorial metabolism and biological energy transfer might one day come to be generally accepted, and I have done my best to argue in favour of that state of affairs for more than twenty years. But, it would have been much too presumptuous to have expected it to happen. Of course, I might have been wrong, and in any case, was it not the great Max Planck (1928, 1933) who remarked that a new scientific idea does not triumph by convincing its opponents, but rather because its opponents eventually die? The fact that what began as the chemiosmotic hypothesis has now been acclaimed as the chemiosmotic theory-at the physiological level, even if not at the biochemical level-has therefore aroused in me emotions of astonishment and delight in full and equal measure, which are all the more heartfelt because those who were formerly my most capable opponents are still in the prime of their scientific lives. I shall presently explain the difference between the physiological and the biochemical levels at which the chemiosmotic theory has helped to promote useful experimental research. But let me first say that my immediate and deepest impulse is to celebrate the fruition of the creative work and benevolent influence of the late David Keilin, one of the greatest of biochemists and-to me, at least-the kindest of men, whose marvellously simple studies of the cytochrome system, in animals, plants and microorganisms (Keilin, 1925), led to the original fundamental idea of aerobic energy metabolism: the concept of the respiratory chain (Keilin, 1929; and see Nicholls, 1963; King, 1966). Perhaps the most fruitful (and surprising) outcome of the development of the notion of chemiosmotic reactions is the experimental stimulus and guidance it has provided in work designed to answer the following three elementary questions about respiratory chain systems and analogous photoredox chain systems: What is it? What does it do? How does it do it? The genius of David Keilin led to the revelation of the importance of these questions. In this lecture, I hope to show that, as a result of the painstaking work of many biochemists, we can now answer the first two in general principle, and that considerable progress is being made in answering the third. Owing to the broad conceptual background, and the very wide range of practical application of the chemiosmotic theory, I have had …

Target cells for 1,25-dihydroxyvitamin D3 in intestinal tract, stomach, kidney, skin, pituitary, and parathyroid.

Abstract: After mature rats that had been fed on a vitamin D3-deficient diet were injected with tritium-labeled 1,25-dihydroxyvitamin D3, radioactivity became concentrated in nuclei of luminal and cryptal epithelium of the duodenum, jejunum, ileum, and colon; in nuclei of the epithelium of kidney distal tubules including the macula densa, and in podocytes of glomeruli; in nuclei of the epidermis including outer hairshafts and sebaceous glands; and in nuclei of certain cells of the stomach, anterior and posterior pituitary, and parathyroid. These results reveal cell types that contain receptors for 1,25-dihydroxyvitamin D3 or metabolites of this compound both in known or hypothesized target tissues and in tissues that were previously unknown to participate in vitamin D3 metabolism.

The jupiter system through the eyes of voyager 1.

Abstract: The cameras aboard Voyager 1 have provided a closeup view of the Jupiter system, revealing heretofore unknown characteristics and phenomena associated with the planet's atmosphere and the surfaces of its five major satellites. On Jupiter itself, atmospheric motions-the interaction of cloud systems-display complex vorticity. On its dark side, lightning and auroras are observed. A ring was discovered surrounding Jupiter. The satellite surfaces display dramatic differences including extensive active volcanism on Io, complex tectonism on Ganymede and possibly Europa, and flattened remnants of enormous impact features on Callisto.

Multiple representations of the body within the primary somatosensory cortex of primates.

Abstract: Microelectrode mapping experiments indicate that the classical primary somatosensory cortex of monkeys consists of as many as four separate body representations rather than just one. Two complete body surface representations occupy cortical fields 3b and 1. In addition, area 2 contains an orderly representation of predominantly "deep" body tissues. Area 3a may constitute a fourth representation.

Endothermy and Activity in Vertebrates

Abstract: Resting and maximal levels of oxygen consumption of endothermic vertebrates exceed those of ectotherms by an average of five- to tenfold. Endotherms have a much broader range of activity that can be sustained by this augmented aerobic metabolism. Ectotherms are more reliant upon, and limited by, anaerobic metabolism during activity. A principal factor in the evolution of endothermy was the increase in aerobic capacities to support sustained activity.

Opioid Peptides May Excite Hippocampal Pyramidal Neurons by Inhibiting Adjacent Inhibitory Interneurons

Abstract: The atypical excitation by opiates and opioid peptides of hippocampal pyramidal cells can be antagonized by iontophoresis of naloxone, the gamma-aminobutyric acid antagonists bicuculline, or magnesium ion. The recurrent inhibition of these cells evoked by transcallosal stimulation of the contralateral hippocampus is blocked by enkephalin but only shortened by acetylcholine. The results suggest that the opioids excite pyramidal neurons indirectly by inhibition of neighboring inhibitory interneurons (probably containing gamma-aminobutyric acid). This mechanism may be pertinent to the electrographic signs of addictive drugs.

Evergreen coniferous forests of the pacific northwest.

Abstract: The massive, evergreen coniferous forests in the Pacific Northwest are unique among temperate forest regions of the world. The region's forests escaped decimation during Pleistocene glaciation; they are now dominated by a few broadly distributed and well-adapted conifers that grow to large size and great age. Large trees with evergreen needle- or scale-like leaves have distinct advantages under the current climatic regime. Photosynthesis and nutrient uptake and storage are possible during the relatively warm, wet fall and winter months. High evaporative demand during the warm, dry summer reduces photosynthesis. Deciduous hardwoods are repeatedly at a disadvantage in competing with conifers in the regional climate. Their photosynthesis is predominantly limited to the growing season when evaporative demand is high and water is often limiting. Most nutrients needed are also less available at this time. The large size attained by conifers provides a buffer against environmental stress (especially for nutrients and moisture). The long duration between destructive fires and storms permits conifers to outgrow hardwoods with more limited stature and life spans.

Management of multispecies fisheries.

Abstract: With the overexploitation of many conventional fish stcocks, and growing interest in harvesting new kinds of food from the sea, there is increasing need for managers of fisheries to take account of interactions among species. In particular, as Antarctic krill-fishing industries grow, there is a need to agree upon sound principles for managing the Southern Ocean ecosystem. Using simple models, we discuss the way multispecies food webs respond to the harvesting of species at differrent trophic levels. These biological and economic insights are applied to a discussion of fisheries in the Southern Otean and the North Sea and to enunciate some for harvesting in multispecies systems.

Induction of Differentiation in Human Promyelocytic Leukemia Cells by Tumor Promoters

Abstract: Phorbol diester tumor promoters and the promoter mezerein convert human promyelocytic leukemia cells in culture into adherent, nonproliferating cells with many of the characteristics of macrophages. Other types of promoters such as anthralin, phenobarbital, and saccharin do not have this effect. Various compounds that can inhibit some of the biological and biochemical effects of tumor promoters do not interfere with the induction of cell adherence and differentiation by the effective promoters.

Identifying Environmental Chemicals Causing Mutations and Cancer

Abstract: Damage to DNA appears to be the major cause of most cancer and genetic birth defects and may contribute to aging and heart disease as well. The agents that cause this damage must be identified. Many of these agents are natural chemicals present in the human diet as complex mixtures. The tens of thousands of man-made chemicals that have been introduced into the environment in the last few decades must also be tested for their ability to damage DNA. Existing animal tests and human epidemiology alone are inadequate for this task because of time, expense, and the difficulty of dealing with complex mixtures, Newly developed short-term tests, most of them assaying for mutagenicity, are discussed as key tools in identifying environmental mutagens and carcinogens.

Elimination of metabolic cooperation in Chinese hamster cells by a tumor promoter

Abstract: Wild-type Chinese hamster V79 cells (6-thioguanine-sensitive) reduce the recovery of 6-thioguanine-resistant cells when they are cultured together at high densities, through a form of intercellular communication (metabolic cooperation). Cooperation is inhibited by 12-O-tetradecanoyl phorbol-13-acetate, rescuing the 6-thioguanine-resistant cells. These results may be useful in the study of an aspect of the mechanism of tumor promotion and in assaying for promoters.

Can an ape create a sentence

Abstract: More than 19,000 multisign utterances of an infant chimpanzee (Nim) were analyzed for syntactic and semantic regularities. Lexical regularities were observed in the case of two-sign combinations: particular signs (for example, more) tended to occur in a particular position. These regularities could not be attributed to memorization or to position habits, suggesting that they were structurally constrained. That conclusion, however, was invalidated by videotape analyses, which showed that most of Nim's utterances were prompted by his teacher's prior utterance, and that Nim interrupted his teachers to a much larger extent than a child interrupts an adult's speech. Signed utterances of other apes (as shown on films) revealed similar non-human patterns of discourse.

Melting of Io by Tidal Dissipation

Abstract: The dissipation of tidal energy in Jupiter's satellite Io is likely to have melted a major fraction of the mass. Consequences of a largely molten interior may be evident in pictures of Io's surface returned by Voyager I.

Risk and responsibility

Abstract: our minds these days due to many recent tragedies around the world. For example, in Oak Creek, Wisconsin, USA, an intruder raided a Sikh temple and took seven lives. And earlier, in Aurora, Colorado, USA, a gunman killed 12 people at a movie theater. In both cases, the attacker managed to get inside the facility with a gun. Most public places in India seem to have learned a hard lesson following the 2008 terrorist attacks in Mumbai where 195 people lost their lives and 295 were wounded. However, the question of what is an acceptable level of risk is more complex; everyone thinks, “It just cannot happen to me.” A determination of an acceptable level of risk is normally the responsibility of some individual or group designated, formally or otherwise, to manage the risk. If we agree that in our profession, a primary concern is risk assessment and risk management,1 it is imperative that we comprehend the fundamental nature of risk. ISACA’s glossary describes risk as “the combination of the probability of an event and its consequence; an event is something that happens at a specific place and/or time.”2 Simply, we understand the concept of risk as a consequence, the combined effect of probability of something occurring—an unwanted event—and its likely impact. A quantification of risk in this manner allows us to proceed to mitigate any unacceptable levels of risk. At first glance, making the choice seems like a question of a few calculations: Determine the probability of an unwanted event, assess its consequences and combine the two to estimate the impact. A comparison of this result with the cost of instituting and operating appropriate controls guides the decision regarding what to do to protect from an unwanted event. A quantification of risk in this manner technically allows us to proceed to mitigate any unacceptable levels of risk. But there is more to this than meets the eye. What many of these disparate approaches (e.g., environmental impact assessment; multicriterion evaluation; probabilistic, comparative, and environmental risk assessment; cost-benefit and cost effectiveness analysis) hold in common is the tendency to treat the concept of risk as an objectively determinate quantity, with the task of appraisal being simply to identify the “best” of a series of options. To this extent, they share the objective of converting the sociopolitical problems of risk into precisely defined and relatively tractable analytical puzzles.3 The point is that significant uncertainties in the consequences cannot be adequately handled by standard cost-benefit analyses.4 In this thinking, Andrew Stirling5 is not alone. S. Rayner and R. Cantor reject the essential character of the quantitative definition of risk. An agreement on which consequences are unwanted, followed by an assessment of the factors of probability and magnitude, are not enough to meet the necessary and sufficient conditions of risk choices. Other factors that might be relevant are not mere byproducts, but rather could be inherent parts of the risk itself.6 Rayner asserts that the notion of risk can be better grasped if we are to think of risk as an open concept comprised of two components: the scientific and the societal. The scientific component is illustrated by the traditional means of risk analysis. The societal component is fairly new; it concerns trust put in the institutions regulating the technology, acceptability of the principle used to apportion liabilities and acceptability of the procedure by which collective consent is obtained. However, we should note that the elements in this chain of concepts may not be equally important across all situations of risk.7 The talk of risk devoid of responsibility is incoherent. In reality, the two are inseparable and not mutually exclusive. In a thought-provoking treatise on risk and responsibility, Anthony Giddens sets the ground for considering the notion of responsibility as closely linked to risk. He asserts that new technologies penetrate more Vasant Raval, DBA, CISA, is a professor of accountancy at Creighton University (Omaha, Nebraska, USA). Raval is the coauthor of two books on information systems (IS) and security. His areas of teaching and research interests include information security and corporate governance. He can be reached at vraval@creighton.edu. Risk and Responsibility

A systematic assessment of early African hominids

Abstract: A large sample of Pliocene fossil hominid remains has been recovered from the African sites of Hadar in Ethiopia and Laetolil in Tanzania. These collections, dating approximately between 2.9 and 3.8 million years ago, constitute the earliest substantial record of the family Hominidae. This article assesses the phylogenetic relationships of the newly discovered fossil hominids and provides a taxonomy consistent with that assessment. A new taxon, Australopithecus afarensis, has been created to accommodate these Pliocene hominid fossils.

Dual Function of the Damselfly Penis: Sperm Removal and Transfer

Abstract: The male of Calopteryx maculata (Beauvois) (Odonata) uses its penis not only to transfer sperm to the female but also to remove sperm deposited in the female's sperm storage organs from previous matings. Apparently, no such sperm removal function has previously been attributed to the intromittent organ of any animal.

Neuronal chemotaxis: chick dorsal-root axons turn toward high concentrations of nerve growth factor

Abstract: Micropipettes containing 2 to 50 biological units of beta growth factor (NGF) were placed near growing axons of chick dorsal-root ganglion neurons in tissue culture. The axons turned and grew toward the NGF source within 21 minutes. This turning response to elevated concentrations of NGF appears to represent chemotactic guidance rather than a general enhancement of growth rate.

On the nature of human interlimb coordination

Abstract: Movement time varies as a function of amplitude and requirements for precision, according to Fitts' law, but when subjects perform two-handed movements to targets of widely disparate difficulty they do so simultaneously. The hand moving to an "easy" target moves more slowly to accommodate its "difficult" counterpart, yet both hands reach peak velocity and acceleration synchronously. This result suggests that the brain produces simultaneity of action not by controlling each limb independently, but by organizing functional groupings of muscles that are constrained to act as a single unit.

Magnetite in Freshwater Magnetotactic Bacteria

Abstract: A previously undescribed magnetotactic spirillum isolated from a freshwater swamp was mass cultured in the magnetic as well as the nonmagnetic state in chemically defined culture media. Results of Mossbauer spectroscopic analysis applied to whole cells identifies magnetite as a constituent of these magnetic bacteria.

Dopamine auto- and postsynaptic receptors: electrophysiological evidence for differential sensitivity to dopamine agonists.

Abstract: The responses of dopamine cells in the substantia nigra to iontophoretically administered dopamine and intravenous apomorphine were compared to the responses of spontaneously active neurons in the caudate nucleus. Dopaminergic cells were six to ten times more sensitive to dopamine and intravenous apomorphine than 86 percent of the caudate cells tested. This differential sensitivity of dopamine auto- and postsynaptic receptors may explain the apparently paradoxical behavioral effects induced by small compared to large doses of some dopamine agonists and may provide a means of developing new types of drugs to antagonize dopaminergic influence in the central nervous system.

Phase advance of the circadian sleep-wake cycle as an antidepressant

Abstract: Sleep in depressed patients resembles sleep in normal subjects whose circadian rhythms of temperature and rapid-eye-movement sleep are phase-advanced (shifted earlier) relative to their sleep schedules. If this analogy is relevant to the pathophysiology of depressive illness, advancing the time of sleep and awakening should temporarily compensate for the abnormal timing of depressed patients' circadian rhythms. Four of seven manic-depressive patients studied longitudinally spontaneously advanced their times of awakening (activity onset) as they emerged from the depressive phase of their illness. In a phase-shift experiment, a depressed manic-depressive woman was twice brought out of depression for 2 weeks by advancing her sleep period so that she went to sleep and arose 6 hours earlier than usual. The antidepressant effect of the procedure was temporary and similar in duration to circadian desynchronization induced by jet lag in healthy subjects. This result supports the hypothesis that abnormalities of sleep patterns in some types of depression are due to abnormal internal phase relationships of circadian rhythms.