bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Functionalities in Amber
Authors: Lambert Joseph B. , Frye James S.
Published: October 2006

High-resolution nuclear magnetic resonance spectra of the carbon nuclei in powdered amber, obtained by using the techniques of magic angle spinning and cross polarization, provide detailed information about the types of carbon functionalities. The entire spectrum of Baltic amber (succinite) is identical for several samples. Baltic amber shows minor differences from Sicilian amber and drastic differences from Burmese, Romanian, and Bohemian ambers.
Resource Partitioning and Interspecific Competition in Two Two-Species Insular
Anolis
Lizard Communities
Authors: Pacala Stephen , Roughgarden Jonathan
Published: October 2006

Population experiments with
Anolis
lizard species demonstrate a relation between the amount of between-species competition and the degree of interspecific resource partitioning (the more the partitioning the less the competition). Specifically, the amount of resource partitioning between the two species (
Anolis gingivinus
and
Anolis wattsi pogus
) on the island of St. Maarten is less than that between the two species (
Anolis bimaculatus
and
Anolis wattsi schwartzi
) on the island of St. Eustatius. The presence of Anolis wattsi both lowers the growth rates and raises the perch heights of
Anolis gingivinus
individuals. In contrast,
Anolis wattsi
has no effect on
Anolis bimaculatus
. Thus, when there is less resource partitioning,
Anolis wattsi
has a greater competitive effect. This verifies, for these species, a central assumption of competition theory: the strength of between-species competition is inversely related to the amount of interspecific resource partitioning.
Chemical Fossils: The Geological Fate of Steroids
Authors: Mackenzie A. S. , Brassell S. C. , Eglinton G. , Maxwell J. R.
Published: October 2006

Steroids are used to illustrate some of the significant advances that have been made in recent years in understanding the biological origin and geological fate of the organic compounds in sediments. The precursor sterols are transformed, initially by microbial activity and later by physicochemical constraints, into thermodynamically more stable saturated and aromatic hydrocarbons in mature sediments and petroleums. The steps in this transformation result in a complex web linking biogenesis, diagenesis, and catagenesis. Indeed, the complexity and variety of biological lipids such as the steroids are evidently matched in the corresponding geolipids. The extent of preservation of the biochemical imprint in the structures and stereochemistry of these geolipids, even over hundreds of millions of years, is startling, as is the systematic and sequential nature of the geochemical changes they evidently undergo. This new understanding of molecular organic geochemistry has applications in petroleum geochemistry, where biological marker compounds are valuable in the assessment of sediment maturity and in correlation work.
Variation in the Social Grouping Tendency of a Communal Web-Building Spider
Authors: Uetz George W. , Kane Thomas C. , Stratton Gail E.
Published: October 2006

The orb web-building spider,
Metepeira spinipes
, from Mexico occurs solitarily and, more frequently, in aggregations of 5 to 150 or more individuals. Although communal, individuals maintain webs and retreats within the colony and capture their own prey. Group size and interindividual distance apparently vary in response to climate and availability of prey.
Androgens Alter the Tuning of Electroreceptors
Authors: Meyer J. Harlan , Zakon Harold H.
Published: October 2006

Weakly electric fish possess electroreceptors that are tuned to their individual electric organ discharge frequencies. One Genus,
Sternopygus
, displays both ontogenetic and seasonal shifts in these frequencies, possibly because of endocrine influences. Systemic treatment with androgens lowers the discharge frequencies in these animals. Concomitant with these changes in electric organ discharge frequencies are decreases in electroreceptor best frequencies; hence the close match between discharge frequency and receptor tuning is maintained. These findings indicate that the tuning of electroreceptors is dynamic and that it parallels natural shifts in electric organ discharge frequency.
Melting of Two-Dimensional Solids
Authors: Brinkman W. F. , Fisher Daniel S. , Moncton D. E.
Published: October 2006

Recent theoretical predictions indicate that melting of a two-dimensional solid may be caused by spontaneous creation of dislocations. The theory predicts that melting occurs by a two-step process involving an intermediate phase, called the hexatic phase, in which there is order in the local crystalline axes but not in the positions of atoms. These ideas are being tested by numerical simulations and by experiments on electrons on liquid helium, liquid crystal films, and rare gas layers adsorbed on graphite. Experiments on liquid crystal films indicate that the three-dimensional analog of the hexatic phase exists, and xenon on graphite exhibits a melting transition close to the form predicted.
Long-Term Consistency of Dominance Relations Among Female Baboons (
Papio cynocephalus
)
Authors: Hausfater Glenn , Altmann Jeanne , Altmann Stuart
Published: October 2006

At maturity, female baboons in the Amboseli National Park of Kenya generally attain a rank position among adults near to that of their mothers. However, the age of a female's mother and the difference in ages between sisters also influence the rank acquisition process. These latter demographic variables, which are sensitive to changes in resource availability, may account for the close association both within and among primate species of specific patterns of rank organization and specific environmental conditions.
Anasazi Solar Marker: The Use of a Natural Rockfall
Authors: Newman Evelyn B. , Mark Robert K. , Vivian R. Gwinn
Published: October 2006

The midday "sun dagger" solstice and equinox marker on Fajada Butte in Chaco Canyon, New Mexico, is formed by three sandstone slabs that collimate sunlight onto two spiral petroglyphs. The slabs appear to be the result of a natural rockfall and not a construct of the Chacoan Anasazi. Although neither the rockfall nor the petroglyphs can be dated accurately, it is likely that the petroglyphs were designed after the rockfall by people who observed the details of the light pattern for several annual cycles.
Voltage-Independent Calcium Release in Heart Muscle
Authors: Niggli Ernst , Lederer W. Jonathan
Published: October 2006

The Ca
2+
that activates contraction in heart muscle is regulated as in skeletal muscle by processes that depend on voltage and intracellular Ca
2+
and involve a positive feedback system. How the initial electrical signal is amplified in heart muscle has remained controversial, however. Analogous protein structures from skeletal muscle and heart muscle have been identified physiologically and sequenced; these include the Ca
2+
channel of the sarcolemma and the Ca
2+
release channel of the sarcoplasmic reticulum. Although the parallels found in cardiac and skeletal muscles have provoked valuable experiments in both tissues, separation of the effects of voltage and intracellular Ca
2+
on sarcoplasmic reticulum Ca
2+
release in heart muscle has been imperfect. With the use of caged Ca
2+
and flash photolysis in voltage-clamped heart myocytes, effects of membrane potential in heart muscle cells on Ca
2+
release from intracellular stores have been studied. Unlike the response in skeletal muscle, voltage across the sarcolemma of heart muscle does not affect the release of Ca
2+
from the sarcoplasmic reticulum, suggesting that other regulatory processes are needed to control Ca
2+
-induced Ca
2+
release.
A Mouse Model of the Aniridia-Wilms Tumor Deletion Syndrome
Authors: Glaser Tom , Lane Joan , Housman David
Published: October 2006

Deletion of chromosome 11p13 in humans produces the WAGR syndrome, consisting of aniridia (an absence or malformation of the iris), Wilms tumor (nephroblastoma), genitourinary malformations, and mental retardation. An interspecies backcross between
Mus musculus/domesticus
and
Mus spretus
was made in order to map the homologous chromosomal region in the mouse genome and to define an animal model of this syndrome. Nine evolutionarily conserved DNA clones from proximal human 11p were localized on mouse chromosome 2 near
Small-eyes
(
Sey
), a semidominant mutation that is phenotypically similar to aniridia. Analysis of Dickie's Small-eye (

Sey
Dey

), a poorly viable allele that has pleiotropic effects, revealed the deletion of three clones,
f3
,
f8
, and
k13
, which encompass the aniridia (
AN2
) and Wilms tumor susceptibility genes in man. Unlike their human counterparts,

Sey
Dey

/+ mice do not develop nephroblastomas. These findings suggest that the Small-eye defect is genetically equivalent to human aniridia, but that loss of the murine homolog of the Wilms tumor gene is not sufficient for tumor initiation. A comparison among
Sey
alleles suggests that the
AN2
gene product is required for induction of the lens and nasal placodes.
Mapping of Herpes Simplex Virus-1 Neurovirulence to γ
1
34.5, a Gene Nonessential for Growth in Culture
Authors: Chou Joany , Kern Earl R. , Whitley Richard J. , Roizman Bernard
Published: October 2006

The gene designated γ
1
34.5 maps in the inverted repeats flanking the long unique sequence of herpes simplex virus-1 (HSV-1) DNA, and therefore it is present in two copies per genome. This gene is not essential for viral growth in cell culture. Four recombinant viruses were genetically engineered to test the function of this gene. These were (i) a virus from which both copies of the gene were deleted, (ii) a virus containing a stop codon in both copies of the gene, (iii) a virus containing after the first codon an insert encoding a 16-amino acid epitope known to react with a specific monoclonal antibody, and (iv) a virus in which the deleted sequences were restored. The viruses from which the gene was deleted or which carried stop codons were avirulent on intracerebral inoculation of mice. The virus with the gene tagged by the sequence encoding the epitope was moderately virulent, whereas the restored virus reacquired the phenotype of the parent virus. Significant amounts of virus were recovered only from brains of animals inoculated with virulent viruses. Inasmuch as the product of the γ
1
34.5 gene extended the host range of the virus by enabling it to replicate and destroy brain cells, it is a viral neurovirulence factor.
Calcium-Sensitive Inactivation in the Gating of Single Calcium Channels
Authors: Yue David T. , Backx Peter H. , Imredy John P.
Published: October 2006

Voltage-activated calcium channels open and close, or gate, according to molecular transition rates that are regulated by transmembrane voltage and neurotransmitters. Here evidence for the control of gating by calcium was found in electrophysiological records of single, L-type calcium channels in heart cells. Conditional open probability analysis revealed that calcium entry during the opening of a single channel produces alterations in gating transition rates that evolve over the course of hundreds of milliseconds. Such alteration of calcium-channel gating by entry of a favored permeant ion provides a mechanism for the short-term modulation of single-ion channels.
Thermal-Wave Imaging
Authors: Rosencwaig Allan
Published: October 2006

Thermal features on and beneath the surface of a sample can be detected and imaged with a thermal-wave microscope. Various methodologies for the excitation and detection of thermal waves are discussed, and several applications, primarily in microelectronics, are presented.
Tin and Methyltin Species in Seawater: Concentrations and Fluxes
Authors: Byrd James T. , Andreae Meinrat O.
Published: October 2006

The concentrations of tin and methyltin species in rivers, an estuary, and the surface and deep ocean generally are less than 50 picomoles of tin per liter. Estuarine profiles and river concentrations suggest that the dissolved riverine input of tin is only a minor source of this element to the oceans. Oceanic concentrations of inorganic tin decrease both with distance from land and with increasing depth from the surface, an indication of atmospheric transport to the surface ocean. Most of the contemporaneous eolian influx of tin to the oceans is anthropogenic. The vertical structure of tin concentrations in the northwestern Atlantic can be explained in terms of a model based on eolian input, advective processes, and removal of tin by particulate scavenging.
Biomass Refining
Authors: Bungay Henry R.
Published: October 2006

Processes for refining biomass from trees or from agricultural residues are fast approaching commercialization. Advances have been made in acidic and enzymatic hydrolysis of the cellulose component of biomass and in some newer processes for biomass refining which leave the lignin fraction relatively intact. Rather than low-priced fuels, which have received the most publicity, initial targets will be products with more profit potential, such as chemicals and molasses. Curtailment of government support for alcohol fuel programs is not crucial, because private investment is taking biomass refining from the pilot plant to the demonstration scale.
Ice-Free Conditions on the Queen Charlotte Islands, British Columbia, at the Height of Late Wisconsin Glaciation
Authors: Warner Barry G. , Mathewes Rolf W. , Clague John J.
Published: October 2006

New radiocarbon dates and plant macrofossil data establish that parts of the Queen Charlotte Islands, British Columbia, were ice-free during and subsequent to the late Wisconsin glacial maximum on the Pacific coast of Canada. A paleoecological investigation of dated sediments at Cape Ball has indicated that a varied flora consisting of terrestrial and aquatic plants was present there about 16,000 years ago. This finding provides support for the existence of a heretofore questioned biotic refugium on the Queen Charlotte Islands during the last glaciation. These results shed new light on problems of glacial chronology, climatic change, biogeography, and archeology along the western margin of North America.
Chemical Composition of Acid Fog
Authors: Waldman Jed M. , Munger J. William , Jacob Daniel J. , Flagan Richard C. , Morgan James J. , Hoffmann Michael R.
Published: October 2006

Fog water collected at three sites in Los Angeles and Bakersfield, California, was found to have higher acidity and higher concentrations of sulfate, nitrate, and ammonium than previously observed in atmospheric water droplets. The
p
H of the fog water was in the range of 2.2 to 4.0. The dominant processes controlling the fog water chemistry appear to be the condensation and evaporation of water vapor on preexisting aerosol and the scavenging of gas-phase nitric acid.
Larval Testes of the Tobacco Budworm: A New Source of Insect Ecdysteroids
Authors: Loeb Marcia J. , Woods Charles W. , Brandt Ethel P. , Boakovec Alexej B.
Published: October 2006

Testes of last-instar larvae of the tobacco budworm release five times more ecdysteroid into incubation medium (judged by radioimmunoassay) in 2.5 hours than is found in testis homogenates. Incubation of testicular components indicates that the testis sheath may be the site of ecdysteroid synthesis. Fractionation of hemolymph, testis homogenate, and incubation medium by high-performance liquid chromatography produces a distinct ecdysteroid pattern in each case. Thus, released testis ecdysteroids are probably converted to other forms for use, sequestration, or general circulation. Their functions are unknown.
Air Pollutant Emissions from Kerosene Space Heaters
Authors: Leaderer Brian P.
Published: October 2006

Air pollutant emissions from portable convective and radiant kerosene space heaters were measured in an environmental chamber. Emission factors for nitrogen oxides, sulfur dioxide, carbon monoxide, carbon dioxide, and oxygen depletion are presented. The data suggest that the use of such heaters in residences can result in exposures to air pollutants in excess of ambient air quality standards and in some cases in excess of occupational health standards.
Max Born's Statistical Interpretation of Quantum Mechanics
Authors: Pais A.
Published: October 2006

In the summer of 1926, a statistical element was introduced for the first time in the fundamental laws of physics in two papers by Born. After a brief account of Born's earlier involvements with quantum physics, including his bringing the new mechanics to the United States, the motivation for and contents of Born's two papers are discussed. The reaction of his colleagues is described.
Pollen and Lignin Records of Late Quaternary Vegetation, Lake Washington
Authors: Leopold Estella B. , Nickmann Rudy , Hedges John I. , Ertel John R.
Published: October 2006

Analyses of lignin oxidation products and pollen for an 11-meter core from Lake Washington provide independent but similar reconstructions of the late Quaternary vegetation in the Puget Lowland. An exception is in sediments of the late Pleistocene where pollen percentages and influx values suggest conifer forest whereas lignin compositions suggest a treeless source region. This dissimilarity appears to result from different major provenances: eolian transport of pollen to the lake from adjacent or downstream drainage basins as opposed to fluvial transport of lignified plant debris only from the Lake Washington drainage basin.
Thyroid Hormone Action at the Cellular Level
Authors: Oppenheimer J. H.
Published: October 2006

A large body of circumstantial evidence suggests that the basic unit of thyroid hormone action is the triiodothyronine nuclear receptor complex. This complex stimulates the formation, directly or indirectly, of a diversity of messenger RNA (mRNA) sequences. A generalized increase in mRNA as well as a disproportionate increase in a limited number of RNA sequences have been demonstrated. Regulation of thyroid hormone effects may be carried out largely at a local cellular level. Highly selective alterations in sensitivity to the triiodothyronine nuclear receptor complex may occur at specific target genes. Metabolic factors and hormones participate in such regulation. In a given tissue, alterations in the total number of receptor sites has not been shown to be useful as an index of thyroid hormone response, and local modulation of the response to the triiodothyronine receptor complex by a variety of factors other than triiodothyronine may be carried out at a postreceptor level.
An RNA Polymerase-Binding Protein That Is Required for Communication Between an Enhancer and a Promoter
Authors: Herendeen Daniel R. , Williams Kelly P. , Kassavetis George A. , Geiduschek E. Peter
Published: October 2006

Although bacteriophage T4 late promoters are selectively recognized by
Escherichia coli
RNA polymerase bearing a single protein encoded by T4 gene 55 (gp55), efficient transcription at these promoters requires enhancement by the three T4 DNA polymerase accessory proteins, bound to distal "mobile enhancer" sites. Two principles are shown to govern this transcriptional enhancement: (i) Promoter recognition and communication between the enhancer and the promoter require separate phage-coded proteins. Only RNA polymerase that has the T4 gene 33 protein (gp33) bound to it is subject to enhancement by the three DNA replication proteins. (ii) Transcriptional enhancement in this prokaryotic system is promoter-specific. Promoter specificity is generated by a direct competition of phage T4 gp33 and gp55 with the
E. coli
promoter recognition protein, σ
70
, for binding to the
E. coli
RNA polymerase core. Thus, polymerase that contains σ
70
is competent to transcribe T4 early and middle genes, but lacks the ability to be enhanced by the DNA replication proteins, while polymerase that contains gp55 and gp33 is capable of enhancement via gp33, but its activity is restricted to T4 late promoters by gp55.
Topography, Albedo-Temperature Feedback, and Climate Sensitivity
Authors: Birchfield G. Edward , Wertman Johannes
Published: October 2006

Numerical experiments with an energy balance model of the earth's climate suggest an enhancement of albedo-temperature feedback caused by the presence of a high middle-latitude plateau in the zonally averaged Northern Hemisphere topography. The increased climate sensitivity arises from the increased rate of change of snow cover produced by the advance or retreat of the winter snow line over the north slope of this topographic feature.
Sulfide Binding by the Blood of the Hydrothermal Vent Tube Worm
Riftia pachyptila
Authors: Arp Alissa J. , Childress James J.
Published: October 2006

The blood of the deep-sea hydrothermal vent tube worm
Riftia pachyptila
Jones contains a sulfide-binding protein that appears to concentrate sulfide from the environment and may function for sulfide transport to the internal endosymbiotic bacteria contained within the coelomic organ, the trophosome.
Sweden Beyond Oil: The Efficient Use of Energy
Authors: Johansson Thomas B. , Steen Peter , Bogren Erik , Fredriksson Roger
Published: October 2006

Technology now being introduced in industry, buildings, and transportation is much more energy-efficient than today's average technology. Changes in production and consumption are tending to decrease the intensity of energy use. By applying available economic technology, it may be possible to reduce energy use in Sweden from the present 1400 petajoules per year to about 900 petajoules per year soon after the turn of the century, even with a 50 percent increase in the consumption of goods and services. Technology now being developed could reduce energy demand even further.
Biotechnology of Forest Yield
Authors: Farnum Peter , Timmis Roger , Kulp J. Laurence
Published: October 2006

Silvicultural and genetic manipulation of Douglas fir and loblolly pine plantations have increased their productivity 70 and 300 percent, respectively, over natural forests on the same sites. Yet these intensively managed plantations are achieving less than 50 percent of their potential productivity. Future increases in yield will result from optimization of nutritional treatments, control of noncrop vegetation, and advances in tree breeding and tissue culture techniques.
Bioreactors: Design and Operation
Authors: Cooney Charles L.
Published: October 2006

The bioreactor provides a central link between the starting feedstock and the product. The reaction yield and selectivity are determined by the biocatalyst, but productivity is often determined by the process technology; as a consequence, biochemical reaction engineering becomes the interface for the biologist and engineer. Developments in bioreactor design, including whole cell immobilization, immobilized enzymes, continuous reaction, and process control, will increasingly reflect the need for cross-disciplinary interaction in the biochemical process industry.
Pleistocene Sea Levels from Raised Coral Reefs of Haiti
Authors: Dodge Richard E. , Fairbanks Richard G. , Benninger Larry K. , Maurrasse Florentin
Published: October 2006

The elevations and ages of a sequence of three uplifted Pleistocene coral reefs on the Northwest Peninsula of Haiti have been determined. With the assignment of a sea level of +6 meters (relative to the present day) at 130,000 years before present and constant uplift of the reefs, the data indicate that sea level stood –10 and –13 meters at 108,000 and 81,000 years before present, respectively. These results are in substantial agreement with those reported for Barbados and New Guinea and support the hypothesis of constant uplift for each area. Sea level data from raised reefs indicate that the interglacial marine oxygen isotope oscillations during oxygen isotope stage 5 are a result of 30 percent ice volume effects and 70 percent temperature effects.
Interstellar Carbon in Meteorites
Authors: Swart P. K. , Grady M. M. , Pillinger C. T. , Lewis R. S. , Anders Edward
Published: October 2006

The Murchison and Allende chondrites contain up to 5 parts per million carbon that is enriched in carbon-13 by up to +1100 per mil (the ratio of carbon-12 to carbon-13 is approximately 42, compared to 88 to 93 for terrestrial carbon). This "heavy" carbon is associated with neon-22 and with anomalous krypton and xenon showing the signature of the
s
-process (neutron capture on a slow time scale). It apparently represents interstellar grains ejected from late-type stars. A second anomalous xenon component ("CCFXe") is associated with a distinctive, light carbon (depleted in carbon-13 by 38 per mil), which, however, falls within the terrestrial range and hence may be of either local or exotic origin.
Mathematics and Science Learning: A New Conception
Authors: Resnick Lauren B.
Published: October 2006

Findings in cognitive science suggest new approaches to teaching in science and mathematics.
Bark Beetle Conversion of a Plant Compound to a Sex-Specific Inhibitor of Pheromone Attraction
Authors: Byers John A.
Published: October 2006

Both sexes of the bark beetle
Dendroctonus brevicomis
convert the (+) and (–) enantiomers of the tree terpene α-pinene to the corresponding enantiomers of trans-verbenol at about equal rates. (–)-
trans
-Verbenol inhibited the response of females, but not of males, to a mixture of attractive pheromone components. Since the female initiates the attack on a pine tree, (–)-
trans
-verbenol may play a role in reducing intraspecific competition for breeding areas.
Isotopic Composition of Cellulose from C
3
, C
4
, and CAM Plants Growing Near One Another
Authors: Sternberg Leonel , DeNiro Michael J.
Published: October 2006

Cellulose from plants having crassulacean acid metabolism was enriched in deuterium but not in oxygen-18 in relation to cellulose from C
3
and C
4
plants growing in the same area, indicating that the deuterium enrichment is due to isotopic fractionation during biochemical reactions rather than during evapotranspiration. Hydrogen and oxygen stable isotope ratios of cellulose from the plants in this restricted area showed more variability than that observed in samples collected across an entire continent. Biological factors appear to be as important as environmental factors in determining the isotope ratios of plant cellulose.
Total Synthesis of the L-Hexoses
Authors: Ko Soo Y. , Lee Albert W. M. , Masamune Satoru , Reed Lawrence A. , Sharpless K. Barry , Walker Frederick J.
Published: October 2006

Enantiomerically pure polyhydroxylated natural products are synthesized by using a reiterative two-carbon extension cycle consisting of four steps. The generality and efficiency of this methodology are demonstrated in the total synthesis of all eight L-hexoses.
Role of Shallow Phase Changes in the Subduction of Oceanic Crust
Authors: Pennington Wayne D.
Published: October 2006

Detailed studies of the seismicity of several subduction zones demonstrate that shallow-dipping thrust zones turn to steeper angles at depths of about 40 kilometers. An increased downward body force resulting from shallow phase changes in subducted oceanic crust may be the cause of this increased dip angle. In addition, the volume reduction associated with phase changes may produce sufficiently large stresses in neighboring rocks to cause the seismicity of the upper Benioff zone.
Fish Schools: An Asset to Corals
Authors: Meyer Judy L. , Schultz Eric T. , Helfman Gene S.
Published: October 2006

Schools of juvenile haemulid fish feed in sea grass beds at night. By day they rest over coral heads, where they excrete substantial quantities of ammonium and particulate nitrogen and phosphorus into the nutrient-poor waters. The percentages of these nutrients contributed by the fish were comparable to those from other sources. Coral heads with resident fish schools grew faster than those without resident schools, indicating that fish may be more beneficial to the corals than has been assumed.
Ecology and Catastrophic Mortality in Wild Horses: Implications for Interpreting Fossil Assemblages
Authors: Berger Joel
Published: October 2006

The identities, sexes, and reproductive status of groups of wild horses (Equus caballus) living in the Great Basin Desert of North America were known prior to their deaths on ridgelines. Another group of very young horses died on a quagmire. Snow accumulation or drought was apparently responsible for the mass deaths. These data have implications for reconstructing some aspects of the social structure of fossil mammals on the basis of skewed sex or age ratios in bone assemblages.
Morphological Correlates of Differences in Pheromone Sensitivity in Insect Sensilla
Authors: O'Connell Robert J. , Grant Alan J. , Mayer M. S. , Mankin R. W.
Published: October 2006

Scanning electron microscopy and single unit recordings of maleTrichoplusia niantennae reveal at least two classes of pheromone-sensitive sensilla trichodea. The longer sensillum contains two receptor neurons each with small amounts of spontaneous activity. One neuron responds to large (10-microgram) doses of (Z)-7-dodecenyl acetate, a component of the female sex pheromone. The shorter sensillum contains two receptor neurons both with larger amounts of spontaneous activity and increased sensitivity to low (0.01-microgram) doses of pheromone.
Nitrogen Fixation by Floating Diatom Mats: A Source of New Nitrogen to Oligotrophic Ocean Waters
Authors: Martínez LeeAnne , Silver Mary W. , King James M. , Alldredge Alice L.
Published: October 2006

Nitrogen fixation, apparently by bacterial endosymbionts, is associated with intertwining chains of two species of the diatom
Rhizosolenia
. In situ fixation rates were enhanced by incubation in the dark, whereas concurrent shipboard experiments either underestimated or did not detect nitrogen fixation. This is the first example of nitrogen fixation associated with a bacteria-diatom symbiosis in the pelagic zone, and it indicates that these systems may contribute a significant amount of "new" nitrogen to oligotrophic waters.
Holocene Timberline Fluctuations in Jasper National Park, Alberta
Authors: Kearney M. S. , Luckman B. H.
Published: October 2006

Pollen, fossil logs, and macrofossils from three high-elevation sites in the Maligne Range, Jasper National Park, Alberta, provide the first detailed record of timberline fluctuations in the Canadian Rockies during the last 8700 years. Timberlines were much higher than at present between 8700 to 5200 years ago but oscillated significantly in elevation, with a major episode of timberline recession punctuating two periods of high timberline between about 6700 to 5900 and about 8700 to 7000 years ago. Since 5200 years ago, regional timberlines have generally receded with perhaps brief reversals, reaching their lowest recorded positions sometime after 500 years ago.
Miocene Burrows of Extinct Bear Dogs: Indication of Early Denning Behavior of Large Mammalian Carnivores
Authors: Hunt Robert M. , Xiang-Xu Xue , Kaufman Joshua
Published: October 2006

Partial skeletons of four species of extinct carnivores have been found in their dens excavated in the floodplain of an early Miocene ephemeral braided stream at Agate Fossil Beds National Monument, Nebraska. Bear dogs (Carnivora: Amphicyonidae) were the principal occupants; their den dimensions and body size are similar to those of living wolves and hyenas. Discovery of this predator community extends the record of denning behavior of large mammalian carnivores to the early Miocene, 20 million years ago.
Intracellular
p
H Regulates Transitions Between Dormancy and Development of Brine Shrimp (
Artemia salina
) Embryos
Authors: Busa William B. , Crowe John H.
Published: October 2006

The intracellular
p
H (
p
H
i
) of encysted gastrula-stage embryos of the brine shrimp,
Artemia
, as previously shown by in vivo phosphorus-31 nuclear magnetic resonance spectroscopy, increases by more than 1 unit during arousal from cryptobiotic dormancy and decreases by the same amount during reinduction of dormancy. These changes in
p
H
i
are now shown to be a fundamental regulator of the transitions between dormancy and metabolism: acidification of activated embryo
p
H
i
by more than 1 unit with carbon dioxide induced a state comparable to natural dormancy, while alkalinization of dormant embryo
p
H
i
with the weak base ammonia terminated natural dormancy. This demonstration of
p
H
i
-mediated regulation of cryptobiotic dormancy extends the known scope for
p
H
i
as a regulator of development to include multicellular stages of the metazoan life cycle.
The Cheetah Is Depauperate in Genetic Variation
Authors: O'Brien Stephen J. , Wildt David E. , Goldman David , Merril Carl R. , Bush Mitchell
Published: October 2006

A sample of 55 South African cheetahs
(Acinonyx jubatus jubatus)
from two geographically isolated populations in South Africa were found to be genetically monomorphic at each of 47 allozyme (allelic isozyme) loci. Two-dimensional gel electrophoresis of 155 abundant soluble proteins from cheetah fibroblasts also revealed a low frequency of polymorphism (average heterozygosity, 0.013). Both estimates are dramatically lower than levels of variation reported in other cats and mammals in general. The extreme monomorphism may be a consequence of a demographic contraction of the cheetah (a population bottleneck) in association with a reduced rate of increase in the recent natural history of this endangered species
.
Spontaneous Vesicles Formed from Hydroxide Surfactants: Evidence from Electron Microscopy
Authors: Talmon Y. , Evans D. F. , Ninham B. W.
Published: October 2006

Dialkyldimethylammonium hydroxide surfactants are highly soluble in water and form spontaneous stable vesicles. These vesicles can be grown to size with added acid, and appear to provide an ideal membrane mimetic system for the study of fusion and ion transport. These phenomena are a consequence of strong hydration forces that are not necessarily limited to the hydroxide ions. The forces can be used to design a variety of model systems whose behavior differs from that of systems in which double-chained surfactants form insoluble liquid crystalline phases in water and unstable vesicle suspensions on prolonged sonication.
Arctic Terrestrial Biota: Paleomagnetic Evidence of Age Disparity with Mid-Northern Latitudes During the Late Cretaceous and Early Tertiary
Authors: Hickey Leo J. , West Robert M. , Dawson Mary R. , Choi Duck K.
Published: October 2006

Magnetostratigraphic correlation of the Eureka Sound Formation in the Canadian high Arctic reveals profound difference between the time of appearance of fossil land plants and vertebrates in the Arctic and in mid-northern latitudes. Latest Cretaceous plant fossils in the Arctic predate mid-latitude occurrences by as much as 18 million years, while typical Eocene vertebrate fossils appear some 2 to 4 million years early.
Drug Policy: Striking the Right Balance
Authors: Goldstein Avram , Kalant Harold
Published: October 2006

Drug policy should strike the right balance between reducing the harm done by psychoactive drugs and reducing the harm that results from strict legal prohibitions and their enforcement. It is concluded, from a cost-benefit analysis based on pharmacologic, toxicologic, sociologic, and historical facts, that radical steps to repeal the prohibitions on presently illicit drugs would be likely, on balance, to make matters worse rather than better. Specific recommendations are offered for ameliorating the dangers to users and to society that are posed by each addictive drug.
"Pure" Human Hematopoietic Progenitors: Permissive Action of Basic Fibroblast Growth Factor
Authors: Gabbianelli Marco , Sargiacomo Massimo , Pelosi Elvira , Testa Ugo , Isacchi Giancarlo , Peschle Cesare
Published: October 2006

Methodology has been developed that enables virtually complete purification and abundant recovery of early hematopoietic progenitors from normal human adult peripheral blood. A fraction of the pure progenitors is multipotent (generates mixed colonies) and exhibits self-renewal capacity (gives rise to blast cell colonies). This methodology provides a fundamental tool for basic and clinical studies on hematopoiesis. Optimal in vitro cloning of virtually pure progenitors requires not only the stimulatory effect of interleukin-3, granulocyte-macrophage colony-stimulating factor, and erythropoietin, but also the permissive action of basic fibroblast growth factor. These findings suggest a regulatory role for this growth factor in early hematopoiesis.
Molecular Analysis of Acute Promyelocytic Leukemia Breakpoint Cluster Region on Chromosome 17
Authors: Borrow Julian , Goddard Audrey D. , Sheer Denise , Solomon Ellen
Published: October 2006

Acute promyelocytic leukemia (APL; FAB M3) is characterized by a predominance of malignant promyelocytes that carry a reciprocal translocation between the long arms of chromosomes 15 and 17, t(15;17)(q22;q11.2-q12). This translocation has become diagnostic for APL, as it is present in almost 100 percent of cases. A Not I linking clone was used to detect this translocation initially on pulsed-field gel electrophoresis and subsequently with conventional Southern (DNA) analysis. The breakpoints in ten APL cases examined were shown to cluster in a 12-kb region of chromosome 17, containing two CpG-rich islands. The region is the first intron of the retinoic acid receptor α gene (
RARA
).
Rhodopsin Mutants That Bind But Fail to Activate Transducin
Authors: Franke Roland R. , König Bernd , Sakmar Thomas P. , Khorana H. Gobind , Hofmann Klaus P.
Published: October 2006

Rhodopsin is a member of a family of receptors that contain seven transmembrane helices and are coupled to G proteins. The nature of the interactions between rhodopsin mutants and the G protein, transducin (Gt), was investigated by flash photolysis in order to monitor directly Gtbinding and dissociation. Three mutant opsins with alterations in their cytoplasmic loops bound 11-cis-retinal to yield pigments with native rhodopsin absorption spectra, but they failed to stimulate the guanosine triphosphatase activity of Gt. The opsin mutations included reversal of a charged pair conserved in all G protein-coupled receptors at the cytoplasmic border of the third transmembrane helix (mutant CD1), replacement of 13 amino acids in the second cytoplasmic loop (mutant CD2), and deletion of 13 amino acids from the third cytoplasmic loop (mutant EF1). Whereas mutant CD1 failed to bind Gt, mutants CD2 and EF1 showed normal Gtbinding but failed to release Gtin the presence of guanosine triphosphate. Therefore, it appears that at least the second and third cytoplasmic loops of rhodopsin are required for activation of bound Gt.
Cleaving Yeast and
Escherichia coli
Genomes at a Single Site
Authors: Koob Michael , Szybalski Waclaw
Published: October 2006

The 15-megabase pair
Saccharomyces cerevisiae
and the 4.7-megabase pair
Escherichia coli
genomes were completely cleaved at a single predetermined site by means of the Achilles' heel cleavage (AC) procedure. The symmetric
lac
operator (
lacO
s
) was introduced into the circular Escherichia coli genome and into one of the 16 yeast chromosomes. Intact chromosomes from the resulting strains were prepared in agarose microbeads and methylated with Hha I (5′-GCGC) methyltransferase (M⋅Hha I) in the presence of
lac
repressor (LacI). All Hae II sites (5′-
A
G
GCGC
T
C
) with the exception of the one in
lacO
s
, which was protected by LacI, were modified and thus no longer recognized by Hae II. After inactivation of M⋅Hha I and LacI, Hae II was used to completely cleave the chromosomes specifically at the inserted
lacO
s
. These experiments demonstrate the feasibility of using the AC approach to efficiently extend the specificity of naturally occurring restriction enzymes and create new tools for the mapping and precise molecular dissection of multimegabase genomes.
Free Cupric Ion Activity in Seawater: Effects on Metallothionein and Growth in Crab Larvae
Authors: Sanders Brenda M. , Jenkins Kenneth D. , Sunda William G. , Costlow John D.
Published: October 2006

Crab zoeae (
Rhithropanopeus harrisii
) were exposed during their development to a range of free cupric ion activities regulated in seawater by use of a copper chelate buffer system. Most cytosolic copper was found to be associated with metallothionein. Copper-thionein could be related to free cupric ion activity, and a shift in copper-thionein accumulation was correlated with inhibition of larval growth. These data reveal predictable relations between cupric ion activity in seawater and processes at the cellular and organismic levels.
Phaseolin Gene from Bean Is Expressed After Transfer to Sunflower Via Tumor-Inducing Plasmid Vectors
Authors: Murai Norimoto , Kemp John D. , Sutton Dennis W. , Murray Michael G. , Slightom Jerry L. , Merlo Donald J. , Reichert Nancy A. , Sengupta-Gopalan Champa , Stock Carolyn A. , Barker Richard F. , Hall Timothy C.
Published: October 2006

Sequences coding for the bean seed protein phaseolin were inserted into transferred DNA regions of tumor-inducing plasmids. Constructions were devised in which the coding region of phaseolin was fused in the correct reading frame with the coding region of octopine synthase and placed under the transcriptional control of the octopine synthase promoter. Other plasmids were prepared to permit expression of the phaseolin-encoding sequences from the flanking phaseolin promoter region. The RNA transcribed in sunflower cells transformed with these constructions was characterized by hybridization procedures, SI nuclease mapping, and by translation in vitro of extracted RNA. These tests showed that the genomic intervening sequences were correctly excised. Immunoreactive phaseolin polypeptides were detected by enzyme-linked immunosorbent assay and by antibody hybridization to electrophoretically separated protein extracts of sunflower tissues isolated from crown gall tumors and of transformed sunflower cells grown in tissue culture. These results demonstrate the expression of a plant gene after transfer to a taxonomically distinct botanical family.
From Teosinte to Maize: The Catastrophic Sexual Transmutation
Authors: Iltis Hugh H.
Published: October 2006

An alternative to the theory that the ear of maize (
Zea mays
ssp.
mays
) evolved from a slender female ear of a Mexican annual teosinte holds that it was derived from the central spike of a
male
teosinte inflorescence (tassel) which terminates the primary lateral branches. This alternative hypothesis is more consistent with morphology and explains the anomalous lack of significant genetic and biochemical differences between these taxa. Maize, the only cereal with unisexual inflorescences, evolved through a sudden epigenetic sexual transmutation involving condensation of primary branches, which brought their tassels into the zone of female expression, leading to strong apical dominance and a catastrophic shift in nutrient allocation. Initially, this quantum change may have involved no new mutations, but rather genetic assimilation under human selection of an abnormality, perhaps environmentally triggered.
U.S.-European Cooperation in Space Science: A 25-Year Perspective
Authors: Logsdon John M.
Published: October 2006

In the past 25 years, the National Aeronautics and Space Administration has engaged in a range of cooperative activities in space with other countries and international organizations, most of the scientific interactions being with Europe. The character of U.S.-European cooperation in space science is changing as a result of the increased maturity and level of space capability which Europe is bringing to the partnership; the consequent addition of a competitive dimension to the relationship; the increasing cost of space science missions; and the relative scarcity of funds available for space science. A number of issues flow from the current situation, but in general the outlook is for continued productive cooperation between the United States and Europe in space science.
Herbicide-Resistant Mutants from Tobacco Cell Cultures
Authors: Chaleff R. S. , Ray T. B.
Published: October 2006

Several mutants resistant to the herbicides chlorsulfuron and sulfometuron methyl were isolated form cultured cells of
Nicotiana tabacum
. Resistance was inherited as a single dominant or semidominant mutation in all cases. Linkage analysis of six mutants identified two unlinked genetic loci. Studies of plants homozygous for one mutation showed the mutant plants to be completely resistant to treatment with a concentration of chlorsulfuron 100 times higher than that which produces symptoms of phytotoxicity on normal plants.
Molecular Analysis of
Ds
Controlling Element Mutations at the
Adh1
Locus of Maize
Authors: Sutton W. D. , Gerlach W. L. , Peacock W. J. , Schwartz D.
Published: October 2006

An active maize
Adh1-F
gene, a
Ds
-induced mutant of this gene, and two independent
Ac
-induced revertant alleles have been isolated. The
Ds
mutant differs from the progenitor allele in having a 405-base pair insertion flanked by a direct repeat of 8 bp. The repeat is a duplication of the 8 bp existing at the point of insertion in the 5′ untranslated region of the gene. The insertion sequence is AT-rich (A, adenine; T, thymine) and has 11-bp inverted repeat sequences at its termini. In the revertants the insertion with its inverted repeats is deleted, but the 8-bp direct repeats remain in modified form. These results establish that the 405-bp sequence is a
Ds
element. The
Adh1
messenger RNA level is low in the
Ds
mutant, and it appears that new sites for transcription initiation or RNA processing or both are used. There are at least 30 sequences in the maize genome related to the
Ds
element.
Side Chain Contributions to the Stability of Alpha-Helical Structure in Peptides
Authors: Lyu Pingchang C. , Liff Mark I. , Marky Luis A. , Kallenbach Neville R.
Published: October 2006

Short peptides that contain significant α-helical structure in aqueous solution allow the investigation of the role of amino acid side chains in stabilizing or destabilizing α-helix structure. A host-guest system of soluble synthetic peptides was designed that consisted of chains with the block sequence TyrSerGlu
4
Lys
4
X
3
Glu
4
Lys
4
, denoted EXK, in which X represents any "guest" amino acid residue. Circular dichroism spectroscopy indicates that the extent of helicity of these peptides follows the order Ala > Leu > Met > Gln > Ile > Val > Ser > Thr > Asn > Gly. This order differs from both host-guest copolymer values (Met > Ile > Leu > Ala > Gln > Val > Thr > Asn > Ser > Gly) and the tendencies of these amino acids to occur in helices in globular proteins (Ala > Met > Leu > Gln > Ile > Val > Asn, Thr > Ser > Gly), but matches the order found in a series of synthetic coiled-coil α helices, except for Ser. Proton nuclear magnetic resonance analysis of several EXK peptides indicates that these peptides are partially helical, with the helical residues favoring the amino terminus.