bluuebunny/crossref_metadata_2025 huggingface dataset:
Predatory Salamanders Reverse the Outcome of Competition Among Three Species of Anuran Tadpoles
Authors: Morin Peter J.
Published: October 2006

The outcome of competition among three species of anuran tadpoles in replicated artificial pond communities depends on the density of predatory salamanders present in the community. Predators differentially affect the survival of anuran species to metamorphosis and reverse the pattern of anuran relative abundance resulting from interspecific competition among tadpoles in the absence of predators.
Cell-Adhesive Motif in Region II of Malarial Circumsporozoite Protein
Authors: Rich Kathryn A. , George F. W. , Law Judy L. , Martin W. John
Published: October 2006

The segment of the malarial circumsporozoite (CS) protein designated Region II is highly conserved among different malarial species. A similar sequence is also present in several other proteins, including thrombospondin, properdin, and a blood-stage antigen of
Plasmodium falciparum
. By means of peptides synthesized from sequences of the
Plasmodium vivax
CS protein in the vicinity of Region II, it was found that two overlapping 18- to 20-amino acid peptides promoted the adhesion of a variety of human hematopoietic cell lines. The amino acid sequence valine-threonine-cysteineglycine (VTCG), contained within this common motif, was shown to be the critical sequence for the observed cell-adhesive properties.
An Ancient Group I Intron Shared by Eubacteria and Chloroplasts
Authors: Kuhsel Maria G. , Strickland Roderick , Palmer Jeffrey D.
Published: October 2006

Introns have been found in the genomes of all major groups of organisms except eubacteria. The presence of introns in chloroplasts and mitochondria, both of which are of eubacterial origin, has been interpreted as evidence either for the recent acquisition of introns by organelles or for the loss of introns from their eubacterial progenitors. The gene for the leucine transfer RNA with a UAA anticodon [tRNA
Leu
(UAA)] from five diverse cyanobacteria and several major groups of chloroplasts contains a single group I intron. The intron is conserved in secondary structure and primary sequence, and occupies the same position, within the UAA anticodon. The homology of the intron across chloroplasts and cyanobacteria implies that it was present in their common ancestor and that it has been maintained in their genomes for at least 1 billion years.
Diketopiperazine Formation During Investigations of Amino Acid Racemization in Dipeptides
Authors: Steinberg Spencer , Bada Jeffrey L.
Published: October 2006

The formation of diketopiperazines from the dipeptides isoleucylglycine and glycylisoleucine was investigated at 132°C over the
p
H range ∼ 2 to 10. At
p
H 6.2, ∼ 50 percent of the original dipeptides were converted to the diketopiperazines during the heating experiments. Hydrolysis of the diketopiperazines can yield either the original dipetide or an inverted dipeptide product. The isoleucine in the diketopiperazines was the most highly epimerized component in the system. Previous racemization and epimerization studies with dipeptides have not taken into account the formation of diketopiperazines and, as a result, the conclusions about the mechanism and geochemical implications of amino acid racemization in dipeptides will require revision.
National Strategic Petroleum Reserve
Authors: Davis Ruth M.
Published: October 2006

The Strategic Petroleum Reserve is intended to reduce the vulnerability of the United States to interruptions in the oil supply from foreign sources. Storage for 248 million barrels of crude oil in salt caverns and mines, with equipment for pumping and distribution, was constructed and operationally tested in a 4-year period. Its present inventory is the largest known crude oil reserve in the world. Facilities for expanding the reserve's capacity by another 290 million barrels are being developed by solution-mining in salt domes.
Polycrystalline Echinoderm Calcite and Its Fracture Mechanics
Authors: O'Neill Patricia L.
Published: October 2006

Polycrystalline calcite was revealed by scanning electron microscopy of fractured skeletal ossicles of the sea star
Echinaster spinulosus
(Echinodermata, Asteroidea). Whisker-like calcite crystals were observed in specimens that were loaded in stress relaxation before being fractured; rapidly broken surfaces were smooth and glassy. The crystallites were 1300 angstroms wide and at least 3600 angstroms long and were packed together in lamellae. The lamellae were wound into spirals that formed the trabecular bars. All the crystallites in an ossicle appear to be aligned in the same direction. Geometric considerations indicate that the requirement for packing the crystallites smoothly may explain the high magnesium ion concentration of echinoderm calcite.
Sparrows Learn Adult Song and More from Memory
Authors: Marler Peter , Peters Susan
Published: October 2006

Male swamp sparrows reared in the laboratory and exposed to taped songs during infancy produce accurate imitations of the material following an 8-month interval with no rehearsal. When the first rehearsal occurs, at about 300 days of age, large numbers of syllables are perfected. They are developed through invention and improvisation as well as imitation. Most are discarded at the time of song crystallization. Hence, these songbirds learn more than they manifest in full adult song.
Trace Water Content of Salt in Louisiana Salt Domes
Authors: Knauth L. Paul , Kumar Madhurendu B.
Published: October 2006

The trace water content of salt in six Louisiana salt domes has been determined and has been found to be the lowest of any terrestrial rock type. The average water content of normal domal salt is on the order of 0.003 percent by weight, but anomalous zones within salt stocks can have more than ten times this amount. From the average value, the minimum amount of water in liters
, W,
available to collect around a radioactive waste repository is given as
W = 0.28 r

3

,
where
r
is the radius in meters of the sphere in which water may be thermally activated to migrate completely to the repository
.
Clear Air Turbulence: An Airborne Alert System
Authors: Stearns L. P. , Kuhn P. M. , Kurkowski R. L. , Caracena F.
Published: October 2006

An infrared radiometer system has been developed that can alert a pilot of an aircraft 2 to 9 minutes in advance of an encounter with clear air turbulence. The time between the warning and the clear air turbulence event varies with the flight altitude of the aircraft. In turbulence-free areas, the incidence of false alarms is found to be less than one in 3.4 hours of flight time compared to less than one per 10 hours of flight time in areas with turbulence.
Universities and the New National Effort
Authors: Bok Derek C.
Published: October 2006

In reassessing the role of government, many Americans have agreed that public expenditures should be curtailed. Although our universities must bear their full share of the sacrifices, some of the Administration's recent proposals would be to the detriment of the country. Drastic cuts in student aid, for example, will not encourage young people to seek the best possible education and training; reductions in federal funds for scientific instruments and facilities will mean that our laboratories will deteriorate, our accomplishments will be fewer. The success of American science has depended heavily on the talent that came from Europe at the time of World War II. Today that source has largely disappeared, and if we cannot replace it with exceptional young investigators of our own, the quality of our universities and the vitality of our science will diminish.
Radar Mapping, Archeology, and Ancient Maya Land Use
Authors: Adams R. E. W. , Brown W. E. , Culbert T. Patrick
Published: October 2006

A severe incongruity has long existed between the well-known complexity of ancient Maya civilization and the relatively feeble economic base that could be reconstructed for it. Recent fieldwork has indicated that much more intensive cultivation patterns were used than was previously thought. Data from the use of synthetic aperture radar in aerial surveys of the southern Maya lowlands suggest that large areas were drained by ancient canals that may have been used for intensive cultivation. Ground checks in several limited areas have confirmed the existence of canals, and excavations and ground surveys have provided valuable comparative information. Taken together, the new data suggest that Late Classic period Maya civilization was firmly grounded in large-scale and intensive cultivation of swampy zones.
Remote Sensing in Development
Authors: Paul Charles K. , Mascarenhas Adolfo C.
Published: October 2006

Remote sensing is used to acquire statistics on crops in developing countries and to locate petroleum and mineral deposits. It has increasing potential for forest monitoring and subsurface water location. Problems related to Third World use of the technology include sensitivity about the dissemination of data with high spatial resolution, exploitation by multinational companies, absorptive capacity of countries for advanced technology, autonomy in acquiring resource information, and competing foreign policy interests of the industrialized world in the global search for raw materials. The attitude of Third World countries toward use of remote sensing tends to depend on the development model they adopt.
Changes in Sediment Storage in the Coon Creek Basin, Driftless Area, Wisconsin, 1853 to 1975
Authors: Trimble Stanley W.
Published: October 2006

For any time period, total basin sediment yield can be used to make reliable estimates of upland erosion rates only when no significant change in sediment storage is in progress. In the case of Coon Creek, almost 50 percent of human-induced sediment has historically gone into floodplain storage and less than 7 percent has left the basin. However, some of the stored sediment is becoming mobile, and the present yield per unit area may actually be increasing downstream with the augmentation coming from the storage loss.
Solar Chemistry of Metal Complexes
Authors: Gray Harry B. , Maverick Andrew W.
Published: October 2006

Electronic excited states of certain transition metal complexes undergo oxidation-reduction reactions that store chemical energy. Such reactions have been extensively explored for mononuclear complexes. Two classes of polynuclear species exhibit similar properties, and these complexes are now being studied as possible homogeneous sensitizer-catalysts for hydrogen production from aqueous solutions.
Suppression of Human Colorectal Carcinoma Cell Growth by Wild-Type p53
Authors: Baker Suzanne J. , Markowitz Sanford , Fearon Eric R. , Willson James K. V. , Vogelstein Bert
Published: October 2006

Mutations of the p53 gene occur commonly in colorectal carcinomas and the wild-type p53 allele is often concomitantly deleted. These findings suggest that the wild-type gene may act as a suppressor of colorectal carcinoma cell growth. To test this hypothesis, wild-type or mutant human p53 genes were transfected into human colorectal carcinoma cell lines. Cells transfected with the wild-type gene formed colonies five- to tenfold less efficiently than those transfected with a mutant p53 gene. In those colonies that did form after wild-type gene transfection, the p53 sequences were found to be deleted or rearranged, or both, and no exogenous p53 messenger RNA expression was observed. In contrast, transfection with the wild-type gene had no apparent effect on the growth of epithelial cells derived from a benign colorectal tumor that had only wild-type p53 alleles. Immunocytochemical techniques demonstrated that carcinoma cells expressing the wild-type gene did not progress through the cell cycle, as evidenced by their failure to incorporate thymidine into DNA. These studies show that the wild-type gene can specifically suppress the growth of human colorectal carcinoma cells in vitro and that an in vivo-derived mutation resulting in a single conservative amino acid substitution in the p53 gene product abrogates this suppressive ability.
Flurazepam Effects on Slow-Wave Sleep: Stage 4 Suppressed but Number of Delta Waves Constant
Authors: Feinberg Irwin , Fein George , Walker James M. , Price Leonard J. , Floyd Thomas C. , March Jonathan D.
Published: October 2006

Repeated administration of flurazepam reduced stage 4 sleep (high delta-wave concentration) but produced a greater increase in stage 2 duration so that total sleep time was increased. Computer analysis revealed that the increased amount of stage 2 (low delta-wave concentration) sleep provided a number and duration of delta waves sufficient to offset the loss of delta activity in stage 4. However, the amplitude of the average delta wave was reduced. These results demonstrate the value of direct quantification of delta-wave activity, the variable that underlies visual classification of slow-wave sleep into stages 2 to 4. They also give rise to new hypotheses regarding the relative absence of side effects in spite of profound stage 4 suppression by flurazepam and the mechanisms by which total sleep time is increased by this drug.
Octopamine Receptors, Adenosine 3′,5′-Monophosphate, and Neural Control of Firefly Flashing
Authors: Nathanson James A.
Published: October 2006

An adenylate cyclase activated as much as 25-fold by low concentrations of octopamine has been identified in the firefly lantern. The relative potency of octopamine and various other amines in stimulating this enzyme, and effects of antagonists in blocking octopamine activation, correlate well with the known effects of these agents in affecting light production. In addition to suggesting a role for adenosine 3′,5′-monophosphate (or pyrophosphate) in the neural control of firefly flashing, identification of this potent enzyme should facilitate the characterization of phenylethylamine receptors in excitable tissue.
Secretion of Neurotoxins by Mononuclear Phagocytes Infected with HIV-1
Authors: Giulian Dana , Vaca Ken , Noonan Christine A.
Published: October 2006

Mononuclear phagocytes (microglia, macrophages, and macrophage-like giant cells) are the principal cellular targets for human immunodeficiency virus-1 (HIV-1) in the central nervous system (CNS). Since HIV-1 does not directly infect neurons, the causes for CNS dysfunction in acquired immunodeficiency syndrome (AIDS) remain uncertain. HIV-1-infected human monocytoid cells, but not infected human lymphoid cells, released toxic agents that destroy chick and rat neurons in culture. These neurotoxins were small, heat-stable, protease-resistant molecules that act by way of
N
-methyl-D-aspartate receptors. Macrophages and microglia infected with HIV-1 may produce neurologic disease through chronic secretion of neurotoxic factors.
Radio Science with Voyager 2 at Saturn: Atmosphere and Ionosphere and the Masses of Mimas, Tethys, and Iapetus
Authors: Tyler G. L. , Eshleman V. R. , Anderson J. D. , Levy G. S. , Lindal G. F. , Wood G. E. , Croft T. A.
Published: October 2006

Voyager 2 radio occultation measurements of Saturn's atmosphere probed to the 1.2-bar pressure level, where the temperature was 143 ± 6 K and the lapse rate apparently equaled the dry adiabatic value of 0.85 K per kilometer. The tropopause at both mid-latitude occultation locations (36.5°N and 31°S) was at a pressure level of about 70 millibars and a temperature of approximately 82 K. The stratospheric structures were very similar with the temperature rising to about 140 K at the 1-millibar pressure level. The peak electron concentrations sensed were 1.7 × 10
4
and 0.64 × 10
4
per cubic centimeter in the predawn (31°S) and late afternoon (36.5°N) locations. The topside plasma scale heights were about 1000 kilometers for the late afternoon profile, and 260 kilometers for the lower portions and 1100 kilometers for the upper portions of the topside predawn ionosphere. Radio measurements of the masses of Tethys and Iapetus yield (7.55 ± 0.90) × 10
20
and (18.8 ± 1.2) × 10
20
kilograms respectively; the Tethys-Mimas resonance theory then provides a derived mass for Mimas of (0.455 ± 0.054) × 10
20
kilograms. These values for Tethys and Mimas represent major increases from previously accepted ground-based values, and appear to reverse a suggested trend of increasing satellite density with orbital radius in the Saturnian system. Current results suggest the opposite trend, in which the intermediate-sized satellites of Saturn may represent several classes of objects that differ with respect to the relative amounts of water, ammonia, and methane ices incorporated at different temperatures during formation. The anomalously low density of lapetus might then be explained as resulting from a large hydrocarbon content, and its unusually dark surface markings as another manifestation of this same material.
The Other Frontiers of Science
Authors: Bromley D. Allan
Published: October 2006

Frontiers of science are usually considered as those areas where the boundaries of human knowledge are being pushed most vigorously into the unknown. These are the internal frontiers. But no less important are the external frontiers. Those bordering on the federal government, on education, on private industry, and on international affairs and the developing world are among the most critical and demanding. Some of the outstanding problems facing science, and scientists, in these external interactions, are discussed within the context of our changing national and international priorities.
Transport of Dissolved Amino Acids by the Mussel,
Mytilus edulis
: Demonstration of Net Uptake from Natural Seawater
Authors: Manahan Donal T. , Wright Stephen H. , Stephens Grover C. , Rice Michael A.
Published: October 2006

High-performance liquid chromatography provides direct evidence for substantial removal of naturally occurring specific free amino acids during a single passage of water through the mantle cavity of mussels. This occurs during the few seconds required for passage of the water across the gill, and removal proceeds unabated at ambient substrate concentrations as low as 38 nanomoles per liter.
The Calcium Channel Blocker Nifedipine Attenuates Slow Excitatory Amino Acid Neurotoxicity
Authors: Weiss J. H. , Hartley D. M. , Koh J. , Choi D. W.
Published: October 2006

High concentrations of potent
N
-methyl-D-aspartate (NMDA) agonists can trigger degeneration of cultured mouse cortical neurons after an exposure of only a few minutes; in contrast, selective non-NMDA agonists or low levels of NMDA agonists require exposures of several hours to induce comparable damage. The dihydropyridine calcium channel antagonist nifedipine was used to test whether this slow neurotoxicity is mediated by a calcium influx through voltage-gated channels. Nifedipine had little effect on the widespread neuronal degeneration induced by brief exposure to high concentrations of NMDA but substantially attenuated the neurotoxicity produced by 24-hour exposure to submaximal concentrations of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate, kainate, or quinolinate. Calcium ion influx through dihydropyridine-sensitive, voltage-dependent calcium channels may be an important step in the neuronal injury induced by the prolonged activation of NMDA or non-NMDA glutamate receptors.
Molecular Cloning and Expression of a Complementary DNA for Inositol 1,4,5-Trisphosphate 3-Kinase
Authors: Choi Kwan Yong , Kim Ha Kun , Lee Sang Yeol , Moon Kyung Ho , Sim Sang Soo , Kim Jae Won , Chung Hong Keun , Rhee Sue Goo
Published: October 2006

A complementary DNA (cDNA) clone that encodes inositol 1,4,5-trisphosphate 3-kinase was isolated from a rat brain cDNA expression library with the use of monoclonal antibodies. This clone had an open reading frame that would direct the synthesis of a protein consisting of 449 amino acids and with a molecular mass of 49,853 daltons. The putative protein revealed a potential calmodulin-binding site and six regions with amino acid compositions (PEST regions) common to proteins that are susceptible to calpain. Expression of the cDNA in COS cells resulted in an approximately 150-fold increase in inositol 1,4,5-trisphosphate 3-kinase activity of these cells.
Changing Role of Public and Private Sectors in Agricultural Research
Authors: Ruttan Vernon W.
Published: October 2006

The considerations involved in defining appropriate roles for the public and private sectors in agricultural research are examined with respect to mechanization, plant variety, and insecticide research and development. It is concluded that the public sector should continue to give mechanization a low priority. Varietal improvement should remain a relatively high priority until the effects of plant variety protection legislation become more apparent. Simultaneous achievement of safety, environmental, and productivity objectives in insect pest control will require that the public sector play a larger role in research and development.
An Upheaval in U.S. Strategic Thought
Authors: Smith R. Jeffrey
Published: October 2006

Early this year, the U.S. land-based force of nuclear missiles became vulnerable to a preemptive attack by the Soviet Union, as the Soviets deployed a large number of highly accurate warheads on their own missiles. They first demonstrated this capability in 1977. Since then, U.S. missile vulnerability has come to assume great importance in superpower relations. Western observers have portrayed the Soviet achievement as a sign of aggression, and made missile vulnerability into a symbol of declining American military strength. The government has proposed a vast military buildup of nuclear weapons, supposedly made necessary by this new threat. But the public is increasingly skeptical, and support for some form of arms control is growing.

The first article in this series examines how the United States learned of the Soviet accuracy, and why it caused such great alarm. The next article will examine the Reagan Administration's response to this threat.
Tiering in Suspension-Feeding Communities on Soft Substrata Throughout the Phanerozoic
Authors: Ausich William I. , Bottjer David J.
Published: October 2006

Tiering of benthic marine suspension-feeding communities on soft substrata has varied throughout the Phanerozoic. Epifaunal tiering was most developed during the middle and late Paleozoic and the Triassic to Jurassic, with large-scale reductions in tiering occurring during the Permian-Triassic extinctions and after the Jurassic. Infaunal tiering reached its highest level of organization after the Paleozoic.
Locomotion in Moles (Insectivora, Proscalopidae) from the Middle Tertiary of North America
Authors: Barnosky Anthony D.
Published: October 2006

The locomotion of proscalopid moles, an extinct group restricted to North America, differed from that of other animals. Analysis of a newly discovered and relatively complete and articulated skeleton shows that the digging technique of proscalopids involved a combination of motions that has not been observed in modern fossorial insectivores. The many anatomical peculiarities of proscalopids are related to their specialized digging technique and justify their assignment to a new family of insectivores, the Proscalopidae.
Conservation and Duplication of Isozymes in Plants
Authors: Gottlieb L. D.
Published: October 2006

Many enzymes in plants have isozymes because the same catalytic reaction is often present in several subcellular compartments, most frequently the plastids and the cytosol. The number and subcellular locations of the isozymes appear to be highly conserved in plant evolution. However, gene duplication in diploid species and the addition of genomes in polyploid species have increased the number of isozymes.
Accumulation of Airborne Polychlorinated Biphenyls in Foliage
Authors: Buckley Edward H.
Published: October 2006

Plant foliage accumulates the vapor of polychlorinated biphenyls (PCB's) from the atmosphere, and there is a variation in the amount that is accumulated from one plant species to another. This differential accumulation factor between species remains constant over more than two orders of magnitude of PCB concentrations in plants. The relationships between foliar and atmospheric PCB concentrations hold promise for cost-effective atmospheric PCB monitoring through foliar analyses.
Soufriere Volcano, St. Vincent: Observations of Its 1979 Eruption from the Ground, Aircraft, and Satellites
Authors: Fiske Richard S. , Sigurdsson Haraldur
Published: October 2006

Rapid response by earth, atmospheric, and space scientists made possible diverse observations during the explosive phase of the 1979 eruption of Soufriere Volcano. The 11 reports that follow indicate that, with the availability of appropriate personnel, equipment, and logistical support, a significant body of geophysical data can be gathered on short notice at erupting volcanoes in remote parts of the world.
Energy Self-Sufficiency for Hawaii
Authors: Shupe John W.
Published: October 2006

Currently, Hawaii is almost totally dependent for energy on imported oil. The island state has a wide variety of renewable energy resources, however, and for the past decade has supported the development of these resources as substitutes for seaborne petroleum. Sufficient progress has been made to date in commercializing a number of these alternative energy sources to give cause for optimism that Hawaii will be able to achieve energy self-sufficiency with its indigenous renewable resources.
Micronutrients and Kelp Cultures: Evidence for Cobalt and Manganese Deficiency in Southern California Deep Seawater
Authors: Kuwabara James S.
Published: October 2006

It has been suggested that naturally occurring copper and zinc concentrations in deep seawater are toxic to marine organisms when the free ion forms are overabundant. The effects of micronutrients on the growth of gametophytes of the ecologically and commercially significant giant kelp (
Macrocystis pyrifera
) were studied in defined media. The results indicate that toxic copper and zinc ion concentrations as well as cobalt and manganese deficiencies may be among the factors controlling the growth of marine organisms in nature.
The Tabun Cave and Paleolithic Man in the Levant
Authors: Jelinek Arthur J.
Published: October 2006

Recent excavations at the deeply stratified Late Pleistocene cave site of Tabun on Mount Carmel have yielded a long sequence of Middle and Lower Paleolithic industries and associated geological and environmental evidence that has important implications for the understanding of man's cultural and biological development in that period. An analysis of these materials strongly supports a continuity in cultural development at this site from about 130,000 to 50,000 years ago and suggests that a continuous biological evolution from Neanderthal to anatomically modem
Homo sapiens
took place in the southern Levant.
Endothelin Stimulation of Cytosolic Calcium and Gonadotropin Secretion in Anterior Pituitary Cells
Authors: Stojilković Stanko S. , Merelli Francesco , Iida Toshihiko , Krsmanović Lazar Z. , Catt Kevin J.
Published: October 2006

The presence of endothelin, a vasoconstrictor peptide, in the hypothalamus and posterior pituitary suggests that it also regulates neural and other nonvascular target cells. In pituitary gonadotrophs, low doses of endothelin evoked oscillations in the intracellular calcium concentration, and high doses induced a biphasic calcium response. Mobilization of intracellular calcium predominated during the spike phase of the calcium response to endothelin, whereas calcium entry through dihydropyridine-sensitive channels contributed to both the spike and plateau phases of the calcium response. Endothelin was as potent as hypothalamic gonadotropin-releasing hormone (GnRH) in stimulation of gonadotropin release in perifused pituitary cells. Endothelin bound specifically to pituitary cells with a dissociation constant of 70 picomolar, and induced rapid formation of inositol trisphosphate and diacylglycerol. Although intracellular calcium concentration and gonadotropin secretory responses to endothelin were independent of the GnRH receptor, endothelin and GnRH appeared to have a common signal transduction mechanism. These observations suggest that endothelin can act as a neuropeptide to regulate anterior pituitary function.
Mediation of Cardioprotection by Transforming Growth Factor-β
Authors: Lefer Allan M. , Tsao Philip , Aoki Nobuo , Palladino Michael A.
Published: October 2006

Myocardial ischemia causes heart injury that is characterized by an increase in circulating tumor necrosis factor (TNF), the local production of superoxide anions, the loss of coronary vasodilation (relaxation) in response to agents that release endothelial cell relaxation factor, and cardiac tissue damage. Ischemic injury can be mimicked by TNF. When given before or immediately after ischemic injury, transforming growth factor-β (TGF-β) reduced the amount of superoxide anions in the coronary circulation, maintained endothelial-dependent coronary relaxation, and reduced injury mediated by exogenous TNF. Thus, TGF-β prevented severe cardiac injury, perhaps by alleviating damage mediated by increases in circulating TNF.
A Family of AMPA-Selective Glutamate Receptors
Authors: Keinänen Kari , Wisden William , Sommer Bernd , Werner Pia , Herb Anne , Verdoorn Todd A. , Sakmann Bert , Seeburg Peter H.
Published: October 2006

Four cloned cDNAs encoding 900-amino acid putative glutamate receptors with approximately 70 percent sequence identity were isolated from a rat brain cDNA library. In situ hybridization revealed differential expression patterns of the cognate mRNAs throughout the brain. Functional expression of the cDNAs in cultured mammalian cells generated receptors displaying α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-selective binding pharmacology (AMPA = quisqualate > glutamate > kainate) as well as cation channels gated by glutamate, AMPA, and kainate and blocked by 6,7-dinitroquinoxaline-2,3-dione (CNQX).
AIDS—the Leading Cause of Adult Death in the West African City of Abidjan, Ivory Coast
Authors: De Cock Kevin M. , Barrere Bernard , Diaby Lacina , Lafontaine Marie-France , Gnaore Emmanuel , Porter Anne , Pantobe Daniel , Lafontant Georges C. , Dago-Akribi Augustin , Ette Marcel , Odehouri Koudou , Heyward William L.
Published: October 2006

In 1988 to 1989, 698 adult cadavers in Abidjan's two largest morgues were studied, representing 38 to 43% of all adult deaths in the city over the study period, and 6 to 7% of annual deaths. Forty-one percent of male and 32% of female cadavers were infected with human immunodeficiency virus (HIV). Fifteen percent of adult male and 13% of adult female annual deaths are due to acquired immunodeficiency syndrome (AIDS). In Abidjan, AIDS is the leading cause of death and years of potential life lost in adult men, followed by unintentional injuries and tuberculosis. In women, AIDS is the second leading cause of death and premature mortality, after deaths related to pregnancy and abortion. AIDS-specific and AIDS-proportional mortality rates may be higher in other African cities where AIDS has been found for a longer time than in Abidjan.
R & D in the United States: Its Strengths and Challenges
Authors: Ross Ian M.
Published: October 2006

The promise of technology for improving the quality of life has never been greater, and American science and technology has led the way toward fulfillment of that promise. Now this preeminence is threatened by forces that may affect technological progress throughout the world. It is up to those of us in science, industry, and government to strengthen the institutions that have made us the leaders and to restore our initiative.
Fossil Birds from the Hawaiian Islands: Evidence for Wholesale Extinction by Man Before Western Contact
Authors: Olson Storrs L. , James Helen F.
Published: October 2006

Thousands of fossil bird bones from the Hawaiian Islands collected since 1971 include remains of at least 39 species of land birds that are not known to have survived into the historic period; this more than doubles the number of endemic species of land birds previously known from the main islands. Bones were found in deposits of late Quaternary age; most are Holocene and many are contemporaneous with Polynesian culture. The loss of species of birds appears to be due to predation and destruction of lowland habitats by humans before the arrival of Europeans. Because the historically known fauna and flora of the Hawaiian Islands represent only a fraction of natural species diversity, biogeographical inferences about natural processes based only on historically known taxa may be misleading or incorrect.
Alternative Energy Futures: The Case for Electricity
Authors: Colombo Umberto
Published: October 2006

The energy trends of the past and their likely evolution in the next 50 years have been analyzed in the light of technological progress. It is concluded that society will tend to become less centralized than in the past and that it is possible to have future per capita values of energy consumption at the world level similar to those at present, with a substantial redistribution to allow for economic growth of the less developed countries. A condition for this is increasing penetration of electricity. The rationale for the suggested scenario is described, and prospects for electricity for both the industrialized and developing countries are discussed.
Marmosets (
Saguinus fuscicollis
): Are Learning Sets Learned?
Authors: Menzel E. W. , Juno Charles
Published: October 2006

Confronted with a novel object, a social group of marmoset monkeys investigated it. If they found food on it they returned to it readily the next day; whoever had led in eating usually did so again. If they did not find food, day 2 responsiveness decreased. These untrained performances were sufficient for one-trial visual discrimination learning.
Atom Pair Distribution Functions of Liquid Water at 25°C from Neutron Diffraction
Authors: Narten A. H. , Thiessen W. E. , Blum L.
Published: October 2006

The structure of liquid water is described by three atom pair distribution functions
g
OO
(
r
),
g
OH
(
r
), and
g
HH
(
r
). These functions have now been derived from neutron diffraction data on four mixtures of light and heavy water. They will provide a crucial and sensitive test for proposed models of liquid water.
Forecasting Southern California Earthquakes
Authors: Raleigh C. B. , Sieh K. , Sykes L. R. , Anderson D. L.
Published: October 2006

Since 1978 and 1979, California has had a significantly higher frequency of moderate to large earthquakes than in the preceding 25 years. In the past such periods have also been associated with major destructive earthquakes, of magnitude 7 or greater, and the annual probability of occurrence of such an event is now 13 percent in California. The increase in seismicity is associated with a marked deviation in the pattern of strain accumulation, a correlation that is physically plausible. Although great earthquakes (magnitude greater than 7.5) are too infrequent to have clear associations with any pattern of seismicity that is now observed, the San Andreas fault in southern California has accumulated sufficient potential displacement since the last rupture in 1857 to generate a great earthquake along part or all of its length.
Late Quaternary Zonation of Vegetation in the Eastern Grand Canyon
Authors: Cole Kenneth
Published: October 2006

Fossil assemblages from 53 packrat middens indicate which plant species were dominant during the last 24,000 years in the eastern Grand Canyon. Past vegetational patterns show associations that cannot be attributed to simple elevational displacement of the modern zones. A model emphasizing a latitudinal shift of climatic values is proposed.
Cell-Free Circularization of Viroid Progeny RNA by an RNA Ligase from Wheat Germ
Authors: Branch Andrea D. , Robertson Hugh D. , Greer Christopher , Gegenheimer Peter , Peebles Craig , Abelson John
Published: October 2006

Linear, potato spindle tuber viroid RNA has been used as a substrate for an RNA ligase purified from wheat germ. Linear viroid molecules are efficiently converted to circular molecules (circles) which are indistinguishable by electrophoretic mobility and two-dimensional oligonucleotide pattern from viroid circles extracted from infected plants. In light of recent evidence for multimeric viroid replication intermediates, cleavage followed by RNA ligation by a cellular enzyme may (i) be a normal step in the viroid life cycle and (ii) may also reflect cellular events.
Behavioral Effects of Progesterone Associated with Rapid Modulation of Oxytocin Receptors
Authors: Schumacher Michael , Coirini Héctor , Pfaff Donald W. , McEwen Bruce S.
Published: October 2006

The ventromedial nuclei of the hypothalamus (VMN) are important for the control of feminine mating behavior, and hormone action within these nuclei has been causally related to behavior. Estradiol induces receptors for oxytocin in the VMN and in the area lateral to these nuclei over the course of 1 to 2 days, and progesterone causes, within 30 minutes of its application, a further increase in receptor binding and an expansion of the area covered by these receptors lateral to the VMN. The rapid progesterone effect appears to be a direct and specific effect of this steroid on the receptor or membrane, because it was produced in vitro as well as in vivo and was not mimicked by a variety of other steroids. The effect of progesterone occurred in the posterior part of the VMN, where oxytocin infusion facilitated feminine mating behavior; it did not take place in the anterior part of the VMN, where oxytocin infusion had no effect on mating behavior.
Spacing Differentiation in the Developing
Drosophila
Eye: a Fibrinogen-related Lateral Inhibitor Encoded by
scabrous
Authors: Baker Nicholas E. , Mlodzik Marek , Rubin Gerald M.
Published: October 2006

In the development of multicellular organisms a diversity of cell types differentiate at specific positions. Spacing patterns, in which an array of two or more cell types forms from a uniform field of cells, are a common feature of development. Identical precursor cells may adopt different fates because of competition and inhibition between them. Such a pattern in the developing
Drosophila
eye is the evenly spaced array of R8 cells, around which other cell types are subsequently recruited. Genetic studies suggest that the
scabrous
mutation disrupts a signal produced by R8 cells that inhibits other cells from also becoming R8 cells. The
scabrous
locus was cloned, and it appears to encode a secreted protein partly related to the β and γ chains of fibrinogen. It is proposed that the
sca
locus encodes a lateral inhibitor of R8 differentiation. The roles of the
Drosophila
EGF-receptor homologue (DER) and
Notch
genes in this process were also investigated.
Decay of Female Sexual Behavior Under Parthenogenesis
Authors: Carson Hampton L. , Chang Linda S. , Lyttle Terrence W.
Published: October 2006

A laboratory strain of
Drosophila mercatorum
has existed for 20 years without males and therefore without natural selection operating to maintain the genetic basis of female mating behavior. The females of this strain have recently experienced a genetic impairment of mating capacity. This observation exemplifies the mode of evolution of vestigial characters and supports Muller's theory that random mutation will tend to destroy the genetic basis of a character from which selection has been removed.
Aggressive Signal in "Courtship" Chirps of a Gregarious Cricket
Authors: Boake Christine R. B. , CAPRANICA ROBERT R.
Published: October 2006

Unlike other known species of crickets,
Amphiacusta maya
in Central America mates in groups. Experimentally silenced males experience reduced mating success, not owing to decreased receptivity by females, but owing to increased time spent fighting with other males that persistently interrupt silent courtships. Thus, the data indicate that "courtship" chirping functions as a warning to other males, rather than as a signal to females.
Deep Circulation of the North Atlantic over the Last 200,000 Years: Geochemical Evidence
Authors: Boyle Edward A. , Keigwin Lloyd D.
Published: October 2006

Variations in the cadmium/calcium ratio of North Atlantic Deep Water are recorded in the fossil shells of benthic foraminifera. The oceanic distribution of cadmium is similar to that of the nutrients, hence the cadmium/calcium ratio in shells records temporal variations in nutrient distributions. Data from a North Atlantic sediment core show that over the past 200,000 years there has been a continuous supply of nutrient-depleted waters into the deep North Atlantic. The intensity of this source relative to nutrient-enriched southern waters diminished by about a factor of 2 during severe glaciations. This evidence combined with carbon isotope data indicates that the continental carbon inventory may have been less variable than previously suggested.
Relaxed Energy Outlook Masks Continuing Uncertainties
Authors: Landsberg Hans H.
Published: October 2006

The U.S. energy situation has significantly improved since energy first became a national problem 9 years ago. But easing is not to be confused with solving. Many problems remain and in time might even get worse. The assumptions underlying the prognosis of a carefree energy future merit careful continuing scrutiny. Some do not hold up well. Moreover, in part, greater ease in energy is the mirror image of depressed economic conditions. It is reasonable to relax a little but not to relapse.
Dehalogenation: A Novel Pathway for the Anaerobic Biodegradation of Haloaromatic Compounds
Authors: Suflita Joseph M. , Horowitz Amikam , Shelton Daniel R. , Tiedje James M.
Published: October 2006

Microorganisms of lake sediment and sewage sludge anaerobically metabolized halobenzoates by a novel pathway. The primary degradative event was loss of the aryl halide without the alteration of the aromatic ring. Dehalogenation required strict anaerobic conditions and depended on the halogen and position, but not the number of halogen substituents. A stable methanogenic bacterial consortium was enriched from sludge and found capable of dehalogenating and often mineralizing a variety of halobenzoates to CH
4
and CO
2
. The results suggest that reductive dehalogenation of aromatics could be important in removal of some chlorinated xenobiotics from the environment.
Differential Phosphorylation of c-Abl in Cell Cycle Determined by
cdc
2 Kinase and Phosphatase Activity
Authors: Kipreos Edward T. , Wang Jean Y. J.
Published: October 2006

The product of the
c-abl
proto-oncogene (c-Abl) is phosphorylated on three sites during interphase and seven additional sites during mitosis. Two interphase and all mitotic c-Abl sites are phosphorylated by
cdc2
kinase isolated from either interphase or mitotic cells, with the mitotic
cdc2
having an 11-fold higher activity. Inhibition of phosphatases with okadaic acid in interphase cells leads to the phosphorylation of c-Abl mitotic sites, indicating that those sites are preferentially dephosphorylated during interphase. The differential phosphorylation of c-Abl in the cell cycle is therefore determined by an equilibrium between
cdc2
kinase and protein phosphatase activities. Treatment of interphase cells with okadaic acid leads to a rounded morphology similar to that observed during mitosis.
Bleaching of Rhabdoms in Eyes of Intact Butterflies
Authors: Bernard Gary D.
Published: October 2006

The photochemistry of butterfly rhabdoms has properties that had been associated exclusively with the photoreceptor organelles of vertebrates. Noninvasive measurements of the absorbance spectra of rhabdoms in intact butterflies show that their rhodopsins are converted by light to metarhodopsins that decay from the rhabdom in the dark. A total bleach is possible because the first-order decay of metarhodopsin is considerably faster than the kinetically more complicated recovery of rhodopsin.
Blood Components Prevent Sulfide Poisoning of Respiration of the Hydrothermal Vent Tube Worm
Riftia pachyptila
Authors: Powell Mark A. , Somero GEORGE N.
Published: October 2006

Respiration of plume tissue of the hydrothermal vent tube worm
Riftia pachyptila
is insensitive to sulfide poisoning in contrast to tissues of animals that do not inhabit vents. Permeability barriers may not be responsible for this insensitivity since plume homogenates are also resistant to sulfide poisoning. Cytochrome c oxidase of plume, however, is strongly inhibited by sulfide at concentrations less than 10 μ
M
. Factors present in blood, but not in cytosol, prevent sulfide from inhibiting cytochrome c oxidase. Avoidance of sulfide poisoning of respiration in
Riftia pachyptila
thus appears to involve a blood-borne factor having a higher sulfide affinity than that of cytochrome c oxidase, with the result that appreciable amounts of free sulfide are prevented from accumulating in the blood and entering the intracellular compartment.
Ultraviolet Spectroscopy and the Composition of Cometary Ice
Authors: Feldman Paul D.
Published: October 2006

Our current knowledge of the composition of the cometary nucleus is largely inferred from observations of the gas and dust comae that are produced by sublimation of cometary ice when a comet is near the sun. During the past decade, far-ultraviolet spectroscopy from above the terrestrial atmosphere has shed new light on the physics and chemistry of the gaseous component of the coma. The advent of interplanetary missions to Halley's comet in 1986 and the development of a new generation of earth-orbiting observatories promise further insights into the nature of these frozen remnants of the primordial solar system.
Biological Control of the Removal of Abiogenic Particles from the Surface Ocean
Authors: Deuser W. G. , Brewer P. G. , Jickells T. D. , Commeau R. F.
Published: October 2006

Concurrent measurements of particle concentrations in the near-surface water and of particle fluxes in the deep water of the Sargasso Sea show a close coupling between the two for biogenic components. The concentrations of suspended matter appear to follow an annual cycle similar to that of primary production and deepwater particle flux. Although the concentration of particulate aluminum in the surface water appears to vary randomly with respect to that cycle, the removal of aluminum to deep water is intimately linked to the rapid downward transport of organic matter.
Fire Mosaics in Southern California and Northern Baja California
Authors: Minnich Richard A.
Published: October 2006

In spite of suppression efforts, severe wildfires burn large areas of southern California grassland, coastal sage scrub, and chaparral. Such large burns may not have been characteristic prior to the initiation of fire suppression more than 70 years ago. To compare controlled with uncontrolled areas, wildfires of southern California and adjacent northern Baja California were evaluated for the period 1972 to 1980 from Landsat imagery. Fire size and location, vegetation, year, and season were recorded. It was found that suppression has divergent effects on different plant communities depending on successional processes, growth rates, fuel accumulation, decomposition rates, and length of flammability cycles. These variables establish feedback between the course of active fires, fire history, spatial configuration of flammable vegetation, and fire size. Suppression has minimal impact in coastal sage scrub and grassland. Fire control in chaparral reduces the number of fires, not burned hectarage; fires consequently increase in size, spread rate, and intensity and become uncontrollable in severe weather conditions. The Baja California chaparral fire regime may serve as a model for prescribed burning in southern California.