bluuebunny/crossref_metadata_2025 huggingface dataset:
Wave-Making by Whirligig Beetles (Gyrinidae)
Authors: Tucker Vance A.
Published: October 2006

Swimming whirligig beetles (
Dineutes carolinus
) either make no waves at all or make conspicuous circular or vee-shaped patterns of capillary waves. The beetle's swimming speed can be determined from these wave patterns (or lack of them). Capillary waves precede the beetle for several body lengths, and their reflections may help the beetle avoid solid objects by echolocation. The gravity waves produced by a beetle are always longer than the beetle's hull length. Hence the waves do not interact with the hull to impose an upper limit on speed as they do with conventional ships. Although the beetles swim at high speeds, they apparently do not hydroplane.
Structure of "Polywater"
Authors: Donohue Jerry
Published: October 2006

A structure for "polywater" is proposed. It consists of hydrogen-bonded clusters of water molecules lying at the vertices of rhombic dodecahedra. This structure contains features which are less unattractive than those which are part of several earlier models.
Zinc-Deficient Embryos: Reduced Thymidine Incorporation
Authors: Swenerton Helene , Shrader Ruth , Hurley Lucille S.
Published: October 2006

The 12-day-old embryos of rats with a deficiency of zinc showed a reduced uptake of tritiated thymidine when compared with controls, as shown by liquid scintillation and autoradiography. The high incidence of gross congenital malformations resulting from zinc deficiency may thus be caused by impaired DNA synthesis.
Silica in Developing Epidermal Cells of
Avena
Internodes: Electron Microprobe Analysis
Authors: Kaufmian P. B. , Bigelow W. C. , Petering L. B. , Drogosz F. B.
Published: October 2006

Silica is present in significant amounts in mature guard and subsidiary cells of stomata, in trichomes and silica cells, and in the walls of long epidermal cells of
Avena
. No silica was detectable in cork cells of cork-silica cell pairs. Silica must be accumulated in these specialized epidermal cells quite rapidly.
m-Hydroxyphenylacetic Acid Formation from L-Dopa in Man: Suppression by Neomycin
Authors: Sandler M. , Karoum F. , Ruthven C. R. J. , Calne D. B.
Published: October 2006

The increased excretion ofm-hydroxyphenylacetic acid in the urine of patients with parkinsonism being treated with L-dopa was reduced by gut sterilization with neomycin. Thep-dehydroxylation step is thus brought about solely by the action of gut flora; the pathway is unlikely to be involved in the events within the brain leading to the therapeutic benefit effected by L-dopa.
Tobacco Smoke Toxicity: Loss of Human Oral Leukocyte Function and Fluid-Cell Metabolism
Authors: Eichel Bertram , Shahrik H. Arto
Published: October 2006

The human mouth has been utilized as a new and significant in vivo open bioassay system for tracing undesirable substances present in tobacco smoke, in an exact milieu where the smoking "problem" begins and must be dealt with directly. The associated in vitro closed test systems described herein have provided new, sensitive bioassays that help to explain the in vivo effects.
Choroid Plexus and Cerebrospinal Fluid Production
Authors: Milhorat Thomas H.
Published: October 2006

Acute progressive hydrocephalus occurred in 76 rhesus monkeys undergoing ventricular obstruction 2 to 6 months after choroid plexectomy and was only slightly less pronounced than in 73 nonplexectomized animals with similar ventricular obstructions. The composition of cerebrospinal fluid after choroid plexectomy was essentially normal. Experiments with ventricular perfusion techniques indicate only a slight reduction in cerebrospinal fluid production after choroid plexectomy. Thus, the choroid plexus is probably not the sole or even the major source of cerebrospinal fluid within the primate ventricular system.
Neuronal Network Triggering a Fixed Action Pattern
Authors: Willows A. O. D. , Hoyle G.
Published: October 2006

Bursts of impulses in groups of brain cells of the nudibranch
Tritonia
trigger prolonged swimming that is identical to the natural escape response. The cells in which the activity occurs form two bilaterally symmetrical groups of at least 30 cells in each pleural ganglion. These neurons are interconnected by pathways that have a low electrical resistance, both within a ganglion and across the brain. Together they form a network that determines whether a swimming escape response will occur or not by filtering out weak neural activity yet responding with a burst of impulses to intensive specific input to either group.
Codon Recognition by Enzymatically Mischarged Valine Transfer Ribonucleic Acid
Authors: Grunberger Dezider , Weinstein I. Bernard , Jacobson K. Bruce
Published: October 2006

Direct evidence for the adaptor hypothesis has been obtained by examining the codon recognition of a purified
Escherichia coli
valine transfer ribonucleic acid which was enzymatically mischarged with phenylalanine labeled with carbon-14 by reaction with purified phenylalanyl-transfer ribonucleic acid synthetase from
Neurospora crassa
. The mischarged transfer ribonucleic acid recognized the valine codons but failed to recognize the phenylalanine codon when tested in trinucleotide-directed ribosomal binding assay.
Lactate Dehydrogenase Isozymes: Kinetic Properties at High Enzyme Concentrations
Authors: Wuntch Thomas , Chen Raymond F. , Vesell Elliot S.
Published: October 2006

The kinetic properties of lactate dehydrogenase (LDH) isozymes have been determined at high enzyme concentrations. Spectrophotofluorometric assays revealed that the extent of substrate inhibition of LDH-1 and LDH-5 depends on enzyme concentration. At high enzyme concentrations, in the range of those that exist in most mammalian cells, no inhibition by pyruvate occurred. Pyruvate concentrations up to and including 20.0 millimoles per liter were used for each isozyme at 25° and 40°C at
p
H 7.0 and 7.4. These results suggest that substrate inhibition of LDH may not occur in vivo but only in vitro after appreciable dilution from physiologic enzyme concentrations. These experiments provide further evidence against the theory that substrate inhibition of LDH-1 in vivo accounts for the distribution of LDH isozymes within various tissues. They raise the possibility that, for other enzymes, kinetic properties determined at highly dilute concentrations in vitro may also be quite different from kinetic properties at the much higher concentrations that exist in vivo.
Ages, Irradiation History, and Chemical Composition of Lunar Rocks from the Sea of Tranquillity
Authors: Albee A. L. , Burnett D. S. , Chodos A. A. , Eugster O. J. , Huneke J. C. , Papanastassiou D. A. , Podosek F. A. , Russ G. Price , Sanz H. G. , Tera F. , Wasserburg G. J.
Published: October 2006

The
87
Rb-
87
Sr internal isochrons for five rocks yield an age of 3.65 ± 0.05 × 10
9
years which presumably dates the formation of the Sea of Tranquillity. Potassium-argon ages are consistent with this result. The soil has a model age of 4.5 × 10
9
years, which is best regarded as the time of initial differentiation of the lunar crust. A peculiar rock fragment from the soil gave a model age of 4.44 × 10
9
years. Relative abundances of alkalis do not suggest differential volatilization. The irradiation history of lunar rocks is inferred from isotopic measurements of gadolinium, vanadium, and cosmogenic rare gases. Spallation xenon spectra exhibit a high and variable
131
Xe/
126
Xe ratio. No evidence for
129
I was found. The isotopic composition of solar-wind xenon is distinct from that of the atmosphere and of the average for carbonaceous chondrites, but the krypton composition appears similar to average carbonaceous chondrite krypton.
Trace Elements and Radioactivity in Lunar Rocks: Implications for Meteorite Infall, Solar-Wind Flux, and Formation Conditions of Moon
Authors: Keays Reid R. , Ganapathy R. , Laul J. C. , Anders Edward , Herzog G. F. , Jeffery P. M.
Published: October 2006

Lunar soil and type C breccias are enriched 3- to 100-fold in Ir, Au, Zn, Cd, Ag, Br, Bi, and Tl, relative to type A, B rocks. Smaller enrichments were found for Co, Cu, Ga, Pd, Rb, and Cs. The solar wind at present intensity can account for only 3 percent of this enrichment; an upper limit to the average proton flux during the last 4.5 × 10
9
years thus is 8 × 10
9
cm
-2
yr
-1
. The remaining enrichment seems to be due to a 1.5 to 2 percent admixture of carbonaceous-chondrite-like material, corresponding to an average influx rate of meteoritic and cometary matter of 2.9 × 10
-9
g cm
-2
yr
-1
at Tranquility Base. This is about one-quarter the terrestrial rate. Type A, B rocks are depleted 10- to 100-fold in Ag, Au, Zn, Cd, In, Tl, and Bi, relative to terrestrial basalts. This suggests loss by high-temperature volatilization, before or after accretion of the moon. Positron activities due mainly to
22
Na and
26
Al range from 90 to 220 β
+
min
-1
kg
-1
in five small rocks or fragments (9 to 29 g). The higher activities presumably indicate surface locations. Th and U contents generally agree with those found by the preliminary examination team.
Trace Elements and Accessory Minerals in Lunar Samples
Authors: Reed George W. , Jovanovic Stanka , Fuchs Louis H.
Published: October 2006

Halogen contents similar to those in meteorites are reported in Apollo 11 samples. Concentrations of 0.6 to 13 parts mercury, 0.2 to 0.8 part uranium, 1 to 17 parts lithium, and 1 to 800 parts osmium per million and 0.5 to 1 percent chromium oxide by weight have been measured. In contrast to meteorites and terrestrial rocks a large mercury release below 110°C is observed. Some implications of these results are presented. Fluorapatite, quartz, tridymite, fayalite, and iron-rich, manganese-poor pyroxmangite, previously unreported, have been identified. The small amount of fluorapatite found does not account for the fluorine contents.
Elastic Wave Velocities of Lunar Samples at High Pressures and Their Geophysical Implications
Authors: Kanamori Hiroo , Nur Amos , Chung D. , Wones D. , Simmons Gene
Published: October 2006

Ultrasonic measurement of P and S velocities of Apollo 11 lunar samples 10020, 10057, and 10065 to 5 kilobars pressure at room temperature shows a pronounced increase of velocity (as much as twofold) for the first 2 kilobars. The travel times predicted from the velocity-depth curve of sample 10057 are consistent with the results of the Apollo 12 seismic experiments. At pressures below 200 bars, the samples are highly attenuating; for both P and S waves, the value of
Q
is about 10.
Infrared and Thermal Properties of Lunar Rock
Authors: Bastin J. A. , Clegg P. E. , Fielder G.
Published: October 2006

The infrared absorption properties of lunar rock throughout the range 2 to 2000 micrometers were investigated and, in addition, direct measurements of specific heat and thermal conductivity of rock samples were made. The results suggest that pure radiation is an important, if not dominant, process in heat flow in the lunar surface layer. A new method for determining the mean conductivity of this layer gives somewhat lower values than earlier earth-based measurements. There is also evidence to suggest that, at depths of about 10 meters, the rock is still of a porous and fragmental nature.
Uranium Localization on Hydroxyapatite by Analysis of Fission Fragment Tracks
Authors: Thompson Robert C.
Published: October 2006

The distribution of enriched uranium on individual hydroxyapatite crystals after an exchange reaction has been investigated by means of thermal neutron irradiation followed by electron microscopic analysis of fission fragment tracks in plastic support films. One uranyl ion for every two to three surface calcium ions became associated with the mineral but in a nonuniform distribution that strongly favors crystal end regions.
Polywater: Polymer or Artifact?
Authors: Rousseau D. L. , Porto S. P. S.
Published: October 2006

Several polywater samples were prepared by the standard methods and have the same physical and spectroscopic properties as those made in other laboratories. However, a variety of chemical analyses show high concentrations of impurities which may account for many of the anomalous properties.
Neuronal Mechanisms of Habituation and Dishabituation of the Gill-Withdrawal Reflex in
Aplysia
Authors: Castellucci Vincent , Pinsker Harold , Kupfermann Irving , Kandel Eric R.
Published: October 2006

The cellular mechanisms of habituation and dishabituation of the gill-withdrawal reflex in
Aplysia
were studied with an isolated abdominal ganglion connected to a piece of skin from the tactile receptive field of the reflex. By obtaining simultaneous intracellular recordings from both the sensory neurons and one of the main identified motor neurons, we have been able to reduce the reflex to its monosynaptic components. The monosynaptic excitatory postsynaptic potentials showed a profound low-frequency depression when repeatedly elicited and showed heterosynaptic facilitation after application of a strong stimulus to another pathway. Thus, both habituation and dishabituation can be explained in part and perhaps entirely by changes in the efficacy of specific excitatory synapses.
Facilitation of the Induction of Long-term Potentiation by GABA
B
Receptors
Authors: Mott David D. , Lewis Darrell V.
Published: October 2006

Long-term potentiation (LTP), an in vitro model of learning, was induced in hippocampal slices by 5-hertz stimulation. During induction, γ-aminobutyric acid A (GABA
A
) inhibition decreased, causing the
N
-methyl-D-aspartate receptor-mediated excitation to increase. 2-OH Saclofen, a GABA
B
receptor antagonist, prevented the reduction of inhibition, the increase of excitation, and the induction of LTP. Therefore, disinhibition caused by GABA
B
receptors is required for induction of LTP by 5-hertz stimulation. GABA
B
receptor modulation of synaptic plasticity occurs at frequencies in the range of the endogenous hippocampal theta rhythm, which has been shown to modulate LTP in vivo.
Deregulation of a Homeobox Gene, HOX11, by the t(10;14) in T Cell Leukemia
Authors: Hatano Masahiko , Roberts Charles W. M. , Minden Mark , Crist William M. , Korsmeyer Stanley J.
Published: October 2006

Molecular cloning of the t(10;14)(q24;q11) recurrent breakpoint of T cell acute lymphoblastic leukemia has demonstrated a transcript for the candidate gene TCL3. Characterization of this gene from chromosome segment 10q24 revealed it to be a new homeobox, HOX11. The HOX11 homeodomain is most similar to that of the murine gene
Hlx
and possesses a markedly glycine-rich variable region and an acidic carboxyl terminus. HOX11, while expressed in liver, was not detected in normal thymus or T cells. This lineage-restricted homeobox gene is deregulated upon translocation into the T cell receptor locus where it may act as an oncogene.
Crustal Layer of Seismic Velocity 6.9 to 7.6 Kilometers per Second under the Deep Oceans
Authors: Maynard G. Lafayette
Published: October 2006

Refraction measurements made in the deep ocean between the Marshall and Hawaiian islands reveal a layer of seismic velocity 7.3 kilometers per second between the 6.8 kilometer per second oceanic crustal layer and the mantle. This layer, normally masked as a second arrival, is revealed by continuous air gun refraction data. The layer may be widespread in the deep oceans.
Dodder Weevils in Simultaneous Association with Parasitic Plants and Their Hosts
Authors: Anderson D. M.
Published: October 2006

The weevil
Smicronyx quadrifer
(broad sense) is restricted in host preference to the parasitic dodders (
Cuscuta
species) during its adult life, but its larvae consistently move from dodder stems into living stems of certain hosts of dodders, where they feed, grow to maturity, and undergo metamorphosis. Such associations, involving three interacting organisms, are very unusual among phytophagous insects.
Helium Isotope Effect in Solution in Water and Seawater
Authors: Weiss R. F.
Published: October 2006

The isotope effect in the solution of helium in water from 0° to 40°C has been determined by microgasometric measurements of the solubilities of pure helium-3 and helium-4. At 0°C helium-3 is less soluble than helium-4 in both distilled water and seawater by 1.2 percent. The observed fractionation factor is 0.988 ± 0.002 at 0°C and appears to decrease with increasing temperature at the rate of 0.0001 per degree Centigrade, although the existence of this trend is of limited statistical certainty. The measured isotope effect is in agreement with the ratio of helium-3 to helium-4 in surface ocean water reported by Clarke, Beg, and Craig.
Differential Isotopic Fractionation in Benthic Foraminifera and Paleotemperatures Reassessed
Authors: Duplessy Jean Claude , Lalou Claude , Vinot Annie Claude
Published: October 2006

Different species of benthic Foraminifera taken at the same level in an Atlantic core yielded different oxygen isotopic values. It was therefore impossible to deduce paleotemperature values. In addition, pelagic and benthic species showed the same isotopic variations, an indication that pelagic and benthic species reflect only the variation of oxygen-18 composition of the ocean.
Sex Attractant of the Grass Grub Beetle
Authors: Henzell R. F. , Lowe M. D.
Published: October 2006

The sex attractant produced by adult females of the grass grub beetle
Costelytra zealandica
(White) has been isolated and identified as phenol. Field tests with phenol-water mixtures were attractive to male beetles in particular.
Cigarette Smoke: The Effect of Residue on Mitochondrial Structure
Authors: Kennedy John R. , Elliott Alfred M.
Published: October 2006

Cigarette smoke residue is ciliatoxic to
Tetrahymena pyriformis
. Principal sites of activity are the mitochondria of the cell. The internal membranes of the mitochondria are degraded with time, correlating well with loss of ciliary activity and cell death.
Physiological Concentrations of Lactate Dehydrogenases and Substrate Inhibition
Authors: Everse Johannes , Berger Robert L. , Kaplan Nathan O.
Published: October 2006

Lactate dehydrogenases at physiological concentrations are inhibited by high concentrations of pyruvate when the enzyme and the pyruvate are incubated in the presence of oxidized nicotinamide-adenine dinucleotide before assay. The inhibition is much more pronounced with the H-type than with the M-type lactate dehydrogenase. These results suggest that substrate inhibition may be operative in vivo.
Amphetamine: Differentiation bydandlIsomers of Behavior Involving Brain Norepinephrine or Dopamine
Authors: Taylor Kenneth M. , Snyder Solomon H.
Published: October 2006

d-Amphetamine is markedly more potent an inhibitor of catecholamine uptake by norepinephrine neurons in the brain than isl-amphetamine, whereas the two isomers are equally active in inhibiting catecholamine uptake by the dopamine neurons of the corpus striatum. In behavioral studies,d-amphetamine is ten times as potent asl-amphetamine in enhancing locomotor activity, while it is only twice as potent in eliciting a compulsive gnawing syndrome. This suggests that the locomotor stimulation induced by amphetamine involves central norepinephrine, while dopamine neurons play an important role in the induced compulsive gnawing behavior. Assessment of differential actions ofd- andl-amphetamine may be an efficient method to differentiate behaviors involving norepinephrine or dopamine in the brain.
Cyclic AMP and Cyclic GMP: Mediators of the Mechanical Effects on Bone Remodeling
Authors: Rodan Gideon A. , Bourret Lizabeth A. , Harvey Alan , Mensi Thomas
Published: October 2006

Compressive forces of physiological magnitude (60 grams per square centimeter) reduce the adenosine 3′,5′-monophosphate and guanosine 3′,5′-monophosphate content of the epiphyses of tibiae from 16-day-old chick embryos. An equivalent hydrostatic pressure applied directly to cells isolated from this tissue also affects cyclic nucleotide accumulation. The tissue response is uniform throughout the epiphysis, whereas the cell response varies according to the area of origin.
Anomalous Water: Attempts at High-Pressure Synthesis
Authors: Wentorf R. H.
Published: October 2006

The high density, 1.4 grams per cubic centimeter, reported for anomalous water suggests that high pressures should be conducive to the formation of anomalous water. Six attempts at 60 kilobars in which water was cooled from about 600°C in nickel or platinum tubes, with or without the presence of silica, did not produce any detectable amounts of anomalous water.
Habituation and Dishabituation in the Absence of a Central Nervous System
Authors: Peretz Bertram
Published: October 2006

Habituation and dishabituation have been observed in a semi-intact
Aplysia
preparation in which the central nervous system is removed. The amplitude of withdrawal responses in the gill decreases in proportion to the rate of water drops applied (one drop per 0.5 minute to one drop per 2.5 minutes at 15°C). The effects of habituation last for at least 2 hours. A dishabituated response is elicited by stopping the water drops or electrically stimulating the preparation. Furthermore, the gill contains nerve cell bodies, and habituation and dishabituation appear to be properties of these peripheral neurons.
Retinal Tapetum Lucidum: A Novel Reflecting System in the Eye of Teleosts
Authors: Arnott H. J. , Maciolek N. J. , Nicol J. A. C.
Published: October 2006

A new type of tapetum lucidum has been found in eyes of bony fishes (teleosts). It is retinal, lying in the processes of the pigment epithelial cells; it has a white appearance and reflects light diffusely. The cell processes are loaded with highly refractile lipid particles; as examined by electron microscopy these are about 400 nanometers in diameter, spherical, and homogeneous. This tapetum lucidum has been found in seven families of teleost fishes occurring in inshore waters and rivers of South Texas, all of which have high turbidity; the correlation indicates a role in dim-light vision.
Phenotypic Reversion of
Flacca
, a Wilty Mutant of Tomato, by Abscisic Acid
Authors: Imber Dorot , Tal Moshe
Published: October 2006

The tomato mutant
flacca
wilts rapidly under water deficit because its stomata resist closure. Application of abscisic acid to intact mutant plants changes their morphology toward the phenotype of the control normal variety, Rheinlands Ruhm. The treated mutant plants do not show wilting symptoms, and the resistance to closure of their stomata decreases with hormone treatment.
Strontium-90: Effects of Chronic Ingestion on Farrowing Performance of Miniature Swine
Authors: Clarke William J. , Palmer Ray F. , Howard Edwin B. , Hackett Patricia L. , Thomas John M.
Published: October 2006

In experiments involving the ingestion of strontium-90 by nearly 800 female miniature swine and extending over three generations, no significant differences in litter size, percentage of stillborn, or birth weight were observed between controls and animals ingesting up to 625 microcuries of strontium-90 per day. At 625 microcuries per day, these animals were ingesting more than a million times the peak value of strontium-90 ever reported in the American diet. Animals on 3100 microcuries per day did not survive the gestation period. From these studies, it is evident that feeding levels of strontium-90 high enough to affect fetal or neonatal mortality in this species will not permit maternal survival long enough for the bearing of young.
Monosodium Glutamate: Lack of Effects on Brain and Reproductive Function in Rats
Authors: Adamo N. J. , Ratner A.
Published: October 2006

Monosodium glutamate was injected subcutaneously in infant rats of both sexes. The lateral preoptic and arcuate nuclei and median eminence were examined by light and electron microscopy for possible monosodium glutamate effects. As adults, treated animals showed no adverse monosodium glutamate effects on the reproductive system and neural morphology.
Formaldehyde Absorption Coefficients in the Vacuum Ultraviolet (650 to 1850 Angstroms)
Authors: Gentieu E. P. , Mentall J. E.
Published: October 2006

The absorption spectrum of formaldehyde has been measured photo-electrically from 650 to 1850 angstroms. A broad continuum observed at wavelengths shorter than 1570 angstroms will be the major spectral feature contributing to the formaldehyde lifetime in the interstellar radiation field.
Amnesia Produced by Electroconvulsive Shock or Cycloheximide: Conditions for Recovery
Authors: Quartermain David , McEwen Bruce S. , Azmitia Efrain C.
Published: October 2006

Retrograde amnesia for a passive avoidance response was produced in rats by electroconvulsive shock and in mice by cycloheximide, an inhibitor of protein synthesis. One day after training the memory could be restored if a "reminder" of the original foot shock was given after the retention test on which the amnesia was demonstrated. Memory did not return if the reminder was given without the prior retention test or if the reminder and the test were separated by 23 hours.
Water-Degradable Polymers for Controlled Release of Herbicides and Other Agents
Authors: Beasley M. L. , Collins R. L.
Published: October 2006

A new class of polymeric substances that degrade in the presence of water are formed by the reaction of carboxylic acids with metal ions in the presence of an aldehyde catalyst. Possible uses may be found in agricultural chemicals, packaging, and medicine. Important antipollution aspects are present in many of these applications.
Early Human Cultural and Skeletal Remains from Guitarrero Cave, Northern Peru
Authors: Lynch Thomas F. , Kennedy Kenneth A. R.
Published: October 2006

An early man site in highland Peru yielded a rich cultural assemblage in stratigraphic association with faunal remains, botanical remains, and campfire remnants that furnished secure radiocarbon dates. A human mandible and teeth, showing interesting patterns of occlusal wear, were found in a stratum dated by a charcoal sample to 10,610 B.C., the oldest such date in South America.
Water on the Moon?
Authors: Anders Edward
Published: October 2006

If the planets formed at falling temperatures with volatile substances accreting last, the low abundance of lead, bismuth, indium, and thallium in lunar rocks implies an initial water content of no more than 370 grams per square centimeter, and probably much less. The depletion of volatile substances might be expected a priori if the moon accreted as an original satellite of the earth.
Selectivity Changes in Site-Directed Mutants of the VDAC Ion Channel: Structural Implications
Authors: Blachly-Dyson Elizabeth , Peng Songzhi , Colombini Marco , Forte Michael
Published: October 2006

The gene encoding the yeast mitochondrial outer membrane channel VDAC was subjected to site-directed mutagenesis to change amino acids at 29 positions to residues differing in charge from the wild-type sequence. The mutant genes were then expressed in yeast, and the physiological consequences of single and multiple amino acid changes were assessed after isolation and insertion of mutant channels into phospholipid bilayers. Selectivity changes were observed at 14 sites distributed throughout the length of the molecule. These sites are likely to define the position of the protein walls lining the aqueous pore and hence, the transmembrane segments. These results have been used to develop a model of the open state of the channel in which each polypeptide contributes 12 β strands and one α helix to form the aqueous transmembrane pathway.
Direct Gene Transfer into Mouse Muscle in Vivo
Authors: Wolff Jon A. , Malone Robert W. , Williams Phillip , Chong Wang , Acsadi Gyula , Jani Agnes , Felgner Philip L.
Published: October 2006

RNA and DNA expression vectors containing genes for chloramphenicol acetyltransferase, luciferase, and β-galactosidase were separately injected into mouse skeletal muscle in vivo. Protein expression was readily detected in all cases, and no special delivery system was required for these effects. The extent of expression from both the RNA and DNA constructs was comparable to that obtained from fibroblasts transfected in vitro under optimal conditions. In situ cytochemical staining for β-galactosidase activity was localized to muscle cells following injection of the β-galactosidase DNA vector. After injection of the DNA luciferase expression vector, luciferase activity was present in the muscle for at least 2 months.
Characterization of Naturally Occurring Minor Histocompatibility Peptides Including H-4 and H-Y
Authors: Rötzschke Olaf , Falk Kirsten , Wallny Hans-Joachim , Faath Stefan , Rammensee Hans-George
Published: October 2006

Minor histocompatibility (H) antigens can be peptides derived from cellular proteins that are presented on the cell surface by major histocompatibility complex (MHC) class I molecules. This is similar to viral antigens, because in both cases cytotoxic T lymphocytes (CTLs) recognize artificially produced peptides loaded on target cells. Naturally processed minor H peptides were found to be similar to those artificial CTL-epitopes, as far as size and hydrophobicity is concerned. The peptides studied were isolated from a transfectant that expressed a model CTL-defined antigen, β-galactosidase, from male cells that express H-Y, which has been known operationally since 1955, and from cells that express H-4, known since 1961.
Use of Prior Vaccinations for the Development of New Vaccines
Authors: Etlinger H. M. , Gillessen D. , Lahm H.-W. , Matile H. , Schönfeld H.-J. , Trzeciak A.
Published: October 2006

There is currently a need for vaccine development to improve the immunogenicity of protective epitopes, which themselves are often poorly immunogenic. Although the immunogenicity of these epitopes can be enhanced by linking them to highly immunogenic carriers, such carriers derived from current vaccines have not proven to be generally effective. One reason may be related to epitope-specific suppression, in which prior vaccination with a protein can inhibit the antibody response to new epitopes linked to the protein. To circumvent such inhibition, a peptide from tetanus toxoid was identified that, when linked to a B cell epitope and injected into tetanus toxoid-primed recipients, retained sequences for carrier but not suppressor function. The antibody response to the B cell epitope was enhanced. This may be a general method for taking advantage of previous vaccinations in the development of new vaccines.
External Guide Sequences for an RNA Enzyme
Authors: Forster Anthony C. , Altman Sidney
Published: October 2006

Ribonuclease P (RNase P) from
Escherichia coli
or its catalytic RNA subunit can efficiently cleave small RNA substrates that lack the conserved features of natural substrates of RNase P if an additional small RNA is also present. This additional RNA must contain a sequence complementary to the substrate [external guide sequence (EGS)] and a 3′-proximal CCA sequence to ensure cleavage. The aminoacyl acceptor stem and some additional 5′- and 3′-terminal sequences of a precursor transfer RNA are sufficient to allow efficient cleavage by RNase P, and the 2′-hydroxyl group at the cleavage site is not absolutely necessary for cleavage. In principle, any RNA could be targeted by a custom-designed EGS RNA for specific cleavage by RNase P in vitro or in vivo.
5-Methylcytosine as an Endogenous Mutagen in the Human LDL Receptor and p53 Genes
Authors: Rideout William M. , Coetzee Gerhard A. , Olumi Aria F. , Jones Peter A.
Published: October 2006

Direct genomic sequencing revealed that cytosine residues known to have undergone a germ-line mutation in the low density lipoprotein receptor gene or somatic mutations in the p53 tumor suppressor gene were methylated in all normal human tissues analyzed. Thus, these mutations should be scored as transitions from 5-methylcytosine to thymine rather than from cytosine to thymine. Methylated cytosines occur exclusively at CpG dinucleotides, which, although markedly underrepresented in human DNA, are sites for more than 30 percent of all known disease-related point mutations. Thus, 5-methylcytosine functions as an endogenous mutagen and carcinogen in humans, in that methylation seems to increase the potential for mutation at cytosine residues at least by a factor of 10.
L-Dopa-Induced Release of Cerebral Monoamines
Authors: Ng K. Y. , Chase T. N. , Colburn R. W. , Kopin I. J.
Published: October 2006

L-Dopa markedly increased the efflux of tritiated dopamine and tritiated serotonin from rat brain slices. This action appeared contingent on the decarboxylation of L-dopa to dopamine, since it could be blocked by an inhibitor of L-amino acid decarboxylase. Selective destruction of catecholamine-containing nerve terminals by 6-hydroxydopamine significantly decreased the uptake and release of tritiated dopamine but not that of tritiated serotonin. These observations support the hypothesis that a portion of exogenously administered L-dopa may enter central serotonin terminals and undergo decarboxylation to the amine with resultant displacement of the endogenous indoleamine from vesicular stores.
Demonstration of Biological Activity of a Murine Leukemia Virus of New Zealand Black Mice
Authors: Levy Jay A. , Pincus Theodore
Published: October 2006

Although New Zealand Black mouse embryo and adult tissues show evidence of murine leukemia viral particles and antigens, efforts to demonstrate biological activity of a murine leukemia virus by standard methods have proved negative. Cocultivation of tissues of these mice with non-virus-yielding hamster cells transformed by Moloney sarcoma virus, however, has resulted in the rescue of a pseudotype sarcoma virus, presumably carrying the New Zealand Black mouse leukemia virus coat. This virus has an unusual host restriction, producing foci of cell alteration only in rat cells.
Mammoth Hair: Stability of α-Keratin Structure and Constituent Proteins
Authors: Gillespie J. M.
Published: October 2006

Hair from a woolly mammoth (
Mammuthus primigenius
, age about 32,000 years) retains the ordered structure characteristic of α-keratins, but the proteins of this hair differ in composition from and are smaller than similar proteins isolated from other keratins, for example, elephant hair. It is suggested that these changes have been caused by limited proteolysis.
Celestial Rotation: Its Importance in the Development of Migratory Orientation
Authors: Emlen Stephen T.
Published: October 2006

Three groups of indigo buntings were hand-raised in various conditions of visual isolation from celestial cues. When they had been prevented from viewing the night sky prior to the autumn migration season, birds tested under planetarium skies were unable to select the normal migration direction. By contrast, when they had been exposed as juveniles to a normal, rotating, planetarium sky, individuals displayed typical southerly directional preferences. The third group was exposed to an incorrect planetarium sky in which the stars rotated about a fictitious axis. When tested during the autumn, these birds took up the "correct" migration direction relative to the new axis of rotation. These results fail to support the hypothesis of a "genetic star map." They suggest, instead, a maturation process in which stellar cues come to be associated with a directional reference system provided by the axis of celestial rotation.
Probing Immunosuppressant Action with a Nonnatural Immunophilin Ligand
Authors: Bierer Barbara E. , Somers Patricia K. , Wandless Thomas J. , Burakoff Steven J. , Schreiber Stuart L.
Published: October 2006

The immunosuppressants FK506 and rapamycin bind to the same immunophilin, FK506 binding protein (FKBP), and inhibit distinct signal transduction pathways in T lymphocytes. A nonnatural immunophilin ligand, 506BD, which contains only the common structural elements of FK506 and rapamycin, was synthesized and found to be a high-affinity ligand of FKBP and a potent inhibitor of FKBP rotamase activity. Whereas 506BD does not interfere with T cell activation, it does block the immunosuppressive effects of both FK506 and rapamycin. Thus, the common immunophilin binding element of these immunosuppressants, which is responsible for rotamase inhibition, is fused to different effector elements, resulting in the inhibition of different signaling pathways. Inhibition of rotamase activity is an insufficient requirement for mediating these effects.
Chemistry and Biology of the Immunophilins and Their Immunosuppressive Ligands
Authors: Schreiber Stuart L.
Published: October 2006

Cyclosporin A, FK506, and rapamycin are inhibitors of specific signal transduction pathways that lead to T lymphocyte activation. These immunosuppressive agents bind with high affinity to cytoplasmic receptors termed immunophilins (immunosuppressant binding proteins). Studies in this area have focused on the structural basis for the molecular recognition of immunosuppressants by immunophilins and the biological consequences of their interactions. Defining the biological roles of this emerging family of receptors and their ligands may illuminate the process of protein trafficking in cells and the mechanisms of signal transmission through the cytoplasm.
Inability of Malaria Vaccine to Induce Antibodies to a Protective Epitope Within Its Sequence
Authors: Charoenvit Yupin , Collins William E. , Jones Trevor R , Millet Pascal , Yuan Leo , Campbell Gary H. , Beaudoin Richard L. , Broderson J. Roger. , Hoffman Stephen L.
Published: October 2006

Saimiri
monkeys immunized with a recombinant protein containing 20 copies of the nine amino acid repeat of the
Plasmodium vivax
circumsporozoite (CS) protein developed high concentrations of antibodies to the repeat sequence and to sporozoites, but were not protected against challenge. After intravenous injection of an immunoglobulin G3 monoclonal antibody (NVS3) against irradiated
P. vivax
sporozoites, four of six monkeys were protected against sporozoite-induced malaria, and the remaining two animals took significantly longer to become parasitemic. Epitope mapping demonstrated that NVS3 recognizes only four (AGDR) of the nine amino acids within the repeat region of the
P. vivax
CS protein. The monkeys immunized with (DRA
A
D
GQPAG)
20
did not produce antibodies to the protective epitope AGDR. Thus, determination of the fine specificity of protective immune responses may be critical to the construction of successful subunit vaccines.
Recombinant Virus Vaccine-Induced SIV-specific CD8
+
Cytotoxic T Lymphocytes
Authors: Shen Ling , Chen Zheng W. , Miller Michael D. , Stallard Virginia , Mazzara Gail P. , Panicali Dennis L. , Letvin Norman L.
Published: October 2006

Evidence indicates that cytotoxic T lymphocytes (CTLs) may be important in containing the spread of the human immunodeficiency virus (HIV) in the infected host. Although the use of recombinant viruses has been proposed as an approach to elicit protective immunity against HIV, the ability of recombinant viral constructs to elicit CD8
+
CTL responses in higher primates has never been demonstrated. A live recombinant virus, vaccinia-simian immunodeficiency virus of macaques (SIV
mac
), was used to determine whether such a genetically restricted, T lymphocyte-mediated antiviral response could be generated in a primate. Vaccinia-SIV
mac
vaccination elicited an SIV
mac
Gag-specific, CD8
+
CTL response in rhesus monkeys. These CTLs recognized a peptide fragment that spans residues 171 to 195 of the Gag protein. The rhesus monkey major histocompatibility complex (MHC) class I gene product restricting this CTL response was defined. Both the vaccinated and SIV
mac
-infected monkeys that shared this MHC class I gene product developed CTLs with the same Gag epitope specificity. These findings support the use of recombinant virus vaccines for the prevention of HIV infections in humans.
Dormancy of Trees in Winter
Authors: Perry Thomas O.
Published: October 2006

Early dormancy involves a number of phenomena: cessation of active growth, formation of terminal buds, formation of abscission layers in leaves, development of cold resistance, development of winter rest (a chilling requirement), and leaf fall. The buds of some tree species (or some races of a species) have a true rest or winter chilling requirement; usually the roots do not; perhaps the cambium does not. There is a wide range of genetic variation within and between species in response to photoperiod, winter chilling, water nutrients, and other environmental factors which affect the dormancy condition of plants.

During the period of winter rest there are many metabolic and developmental processes going on in the buds and twigs. These processes include respiration, photosynthesis, some cell division, enzyme synthesis, production of growth stimulators, and dissipation of growth inhibitors.

Dormancy of trees can be divided arbitrarily into three phases: early rest, winter rest, and after-rest. Each of these phases is marked by a distinct set of physiological processes. The transition between the three phases is gradual. Some processes of after-rest can proceed even though the winter chilling requirement (winter rest) of a tree has not been completed fully.

Evidence from grafting experiments and chemical treatments to break winter rest, and studies of genetic variability indicate that the processes and phenomena of dormancy are at least partially independent of each other. Different buds and branches and other parts of the same plant may initiate dormancy, break dormancy, and renew vegetative growth independently.

Initiation and cessation of dormancy can be triggered by a number of environmental variables: photoperiod, temperature, nutrition, water, an array of chemicals, and shock treatments. Dormancy regulation must either involve a variety of receptors or involve receptors that are responsive to a variety of stimuli. Unless dormancy is defined in a highly restricted sense (that is, possession of chilling requirement), it is hard to conceive of a single receptor or regulator that controls all of the phenomena of dormancy. A large number of genes are definitely involved and hence a large number of enzymes. The kinds of enzymes, their numbers, and their concentrations can be regulated by manipulating the environment.
Paleomagnetic Chronology of Pliocene-Early Pleistocene Climates and the Plio-Pleistocene Boundary in New Zealand
Authors: Kennett J. P. , Watkins N. D. , Vella P.
Published: October 2006

The paleomagnetic chronology established for a Pliocene-Early Pleistocene sequence of marine sediments in New Zealand reveals that marked climatic coolings based on Foraminifera and oxygen isotope ratios in the late Cenozoic preceded the Pliocene-Pleistocene boundary, which is taken to be at the base of the Gilsá geomagnetic polarity event (1.79 million years ago). Major temperature fluctuations occur from the upper Gauss (Middle Pliocene) to middle Matuyama (Early Pleistocene). The first major Pliocene cooling spans the Gauss-Matuyama boundary (2.43 million years ago). A uniform and rapid (40 centimeters per 1000 years) rate of deposition is shown for the moderately shallow marine environment.
Ordering of V
2+
, Mn
2+
, and Fe
3+
Ions in Zoisite, Ca
2
Al
3
Si
3
O
12
(OH)
Authors: Ghose Subrata , Tsang Tung
Published: October 2006

The presence of very small amounts of Mn
2+
, V
2+
, and Fe
3+
ions in zoisite can be easily detected by the electron paramagnetic resonance technique at room temperature. The Mn
2+
and Fe
3+
ions are completely ordered and are probably located in the Ca(1)- and Al(II)-sites, respectively, whereas the V
2+
ions probably occupy both Ca(1)- and Ca(2)-sites, with a preference for the Ca(1)-site.
Magnetoglow: A New Geophysical Resource
Authors: Johnson Charles Y. , Young James M. , Holmes Julian C.
Published: October 2006

Evidence has been found that the earth is immersed in a large volume of glowing helium ions. This ionic glow, at 304 angstroms, is similar to the geocoronal hydrogen glow in that it extends to very high altitudes, but it is unique in that it is largely confined to the closed field line portion of the magnetosphere. Because of its magnetic containment, this ionic radiation is called the "magnetoglow." Observations of the magnetoglow from inside and outside the magnetospheric cavity promise to provide a valuable means of studying the structural dynamics of the magnetosphere.
Cyclic Adenosine and Guanosine Monophosphates and Glucagon: Effect on Liver Membrane Potentials
Authors: Friedmann Naomi , Somlyo Avril V. , Somlyo Andrew P.
Published: October 2006

Cyclic adenosine monophosphate, cyclic guanosine monophosphate, glucagon, and isoproterenol each hyperpolarized perfused rat liver cells. The hyperpolarization followed a time course similar to the stimulated increase in potassium efflux and was preceded by the increase in calcium efflux. The hyperpolarization induced by cyclic adenosine monophosphate was blocked by tetracaine. The similarity of the action of the cyclic nucleotides to that of glucagon supports the hypothesis that cyclic adenosine monophosphate is the secondary messenger mediating the action of glucagon.
Solifluction: A Model Experiment
Authors: Higashi Akira , Corte Arturo E.
Published: October 2006

Laboratory experiments that subjected soil to repeated freeze-thaw cycles in an inclined container revealed every process of solifluction, especially of frost creep. Multiple slope-angle effects on the amount of particle movement on the soil surface in every cycle are interpreted by several characteristic processes of frost creep. Gelifluction was found to occur in thicker layers of soil, owing to the excess water retained in soil after thawing. For further development of the problem, a similarity law for the model experiment was derived from thermal considerations.
Infant Responses to Impending Collision: Optical and Real
Authors: Ball William , Tronick Edward
Published: October 2006

Twenty-four infants ranging in age from 2 to 11 weeks responded to symmetrically expanding shadows, which optically specify an approaching object, with an integrated avoidance response and upset. This response did not occur for asymmetrically expanding shadows nor for contracting shadows that specify an object on a miss path and a receding object. The response was observed in all the infants regardless of age, and the addition of kinetic depth information to the displays did not increase the intensity or likelihood of the response. In a second experiment, seven infants defensively reacted to the approach of a real object except when it was on a miss path.
Recurrent Excitation of Secondary Olfactory Neurons: A Possible Mechanism for Signal Amplification
Authors: Nicoll R. A.
Published: October 2006

Secondary neurons of the olfactory bulb can be excited monosynaptically after activation of neighboring secondary neurons by antidromic and orthodromic volleys. Recurrent collaterals of secondary neurons are proposed to synapse with other secondary neurons, thus forming a direct recurrent excitatory pathway. Such a positive feedback system could strengthen the original input signal.
Scanning Electron Microscopic Observations of Surface Structure of Isolated Human Chromosomes
Authors: Golomb H. M. , Bahr G. F.
Published: October 2006

Isolated human chromosomes dried by the critical-point method have been assumed to retain their original three-dimensional shape when viewed under a transmission electron microscope. Our scanning electron microscopic study confirms this interpretation and reveals an appearance like that of a skein of yarn. The existence of fiber bridges between chromatid pairs and among chromosomes is demonstrated.