bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations of Apparent C-Type Particles in Baboon (
Papio cynocephalus
) Placentas
Authors: Kalter S. S. , Helmke R. J. , Panigel M. , Heberling R. L. , Felsburg P. J. , Axelrod L. R.
Published: October 2006

Ultrastructural investigations have revealed the presence of apparent endogenously derived C-type particles in the placental villi of each of 13 baboons studied. Both budding and mature forms were observed in the syncytiotrophoblast of these animals at various stages of pregnancy.
Electrically Coupled, Photosensitive Neurons Control Swimming in a Jellyfish
Authors: Anderson Peter A. V. , Mackie George O.
Published: October 2006

Central neurons in
Polyorchis
(Hydromedusae) were impaled with microelectrodes, and conventional resting potentials were obtained. The waveform of action potentials recorded concurrently with swimming events shows evidence of electrotonic coupling between these neurons, which are also directly photosensitive and receive excitatory synaptic input from other conduction systems.
Appetitive and Replacement Naps: EEG and Behavior
Authors: Evans Frederick J. , Cook Mary R. , Cohen Harvey D. , Orne Emily Carota , Orne Martin T.
Published: October 2006

Consistent subjective, behavioral, and electroencephalographic sleep-stage differences were found between afternoon naps of 11 habitual appetitive nappers (who nap lightly for psychological reasons apparently unrelated to reported sleep needs) and 10 replacement nappers (who apparently nap regularly in response to temporary sleep deficits). Both types of naps were compared with naps of 12 confirmed non-nappers.
Mechanisms of Trace Metal Transport in Rivers
Authors: Gibbs Ronald J.
Published: October 2006

Trace metals transported by the Amazon and Yukon rivers were analytically partitioned among the transport phases: in solutions, ion exchange, organic materials, metallic coatings, and crystalline solids. The distribution for both rivers is similarly proportioned, with copper and chromium transported mainly in the crystalline solids, manganese in coatings, and iron, nickel, and cobalt distributed equally between precipitated metallic coatings and crystalline solids.
DNA Polymerase Activities of Human Milk
Authors: Gerwin Brenda I. , Ebert Paul S. , Chopra Harish C. , Smith Susan G. , Kvedar John P. , Albert Sam , Brennan Michael J.
Published: October 2006

DNA polymerases have been partially purified from human milk. A DNA polymerase detected by phosphocellulose chromatography is similar to the enzymes of RNA tumor viruses in that a hybrid of polyriboadenylate and oligodeoxythymidylate is a better template than is DNA. However, this polymerase differed from that of the RNA tumor viruses in its chromatographic behavior. Three different methods of detecting "reverse transcriptase" activity failed to correlate with the donor's family history of cancer.
Learning: Classical and Avoidance Conditioning in the Mollusk
Pleurobranchaea
Authors: Mpitsos George J. , Davis William J.
Published: October 2006

Naive specimens of the marine gastropod
Pleurobranchaea
withdraw from tactile stimulation of the oral veil and show feeding responses to food chemicals. Experimental subjects, trained by pairing touch (conditioned stimulus) with food chemicals (unconditioned stimulus), soon acquired a classically conditioned feeding response to touch alone. Control subjects that received touch alone or unpaired touch and food chemicals showed significantly fewer feeding responses to touch than did experimentals. Classically conditioned specimens were used for avoidance conditioning. Subjects that received aversive electrical stimulation when they did not withdraw from touch rapidly learned to withdraw rather than to feed in response to touch alone. Controls that received touch alone or unpaired touch and shock continued to exhibit the feeding response to touch alone. The learned responses persisted for up to 2 weeks without reinforcement before extinction, and could be demonstrated in the isolated nervous system.
Selective Visual Experience Fails to Modify Receptive Field Properties of Rabbit Striate Cortex Neurons
Authors: Mize R. Ranney , Murphy E. H.
Published: October 2006

During development, rabbits were exposed only to vertical or horizontal lines to determine if the receptive field characteristics of visual cortex cells would be altered as they are in the cat. Motion and directional selectivity were preserved, and orientation specificity remained unaffected by the restricted experience, which suggests that the rabbit may lack the neural plasticity seen in some other mammals.
Host Immunoglobulin G and Complement Deposits in the Choroid Plexus during Spontaneous Immune Complex Disease
Authors: Lampert Peter W. , Oldstone Michael B. A.
Published: October 2006

Hybrid (NZB × W)F
1
mice spontaneously develop antibodies to nuclear antigens (ANA) and DNA (ADNA) and are an animal model of human systemic lupus erythematosus. Immunofluorescent and electron microscopic observations of the choroid plexus and renal glomeruli of (NZB × W)F
1
mice reveal deposits of host immunoglobulin G (IgG) and the third complement component which appear shortly after the development of ANA and ADNA in the circulation. Additionally, enhancement of ADNA responses accelerates the appearance and severity of IgG deposits in the choroid plexus. The choroid plexus may be a favored site for the deposition of immune complexes and the neuropsychiatric findings in patients with systemic lupus erythematosus and some patients with acute or chronic infections may be related in part to immune complex disease of the choroid plexus.
Brain Aluminum Distribution in Alzheimer's Disease and Experimental Neurofibrillary Degeneration
Authors: Crapper D. R. , Krishnan S. S. , Dalton A. J.
Published: October 2006

Neurofibrillary degeneration is an important pathological finding in senile and presenile dementia of the Alzheimer type. Experimentally, aluminum induces neurofibrillary degeneration in neurons of higher mammals. Aluminum concentrations approaching those used experimentally have been found in some regions of the brains of patients with Alzheimer's disease.
Short- and Long-Term Lithium Administration: Effects on the Brain's Serotonergic Biosynthetic Systems
Authors: Knapp Suzanne , Mandell Arnold J.
Published: October 2006

Short-term treatment with lithium chloride stimulates the uptake of tryptophan and its conversion to serotonin by striate synaptosomes. Preincubation of striate synaptosomes with L-tryptophan and in vivo administration of L-tryptophan appear to act in a similar manner. Midbrain tryptophan hydroxylase activity is reduced in temporal continuity with the lithium-induced activation of tryptophan uptake and conversion. By 10 days, conversion of tryptophan to serotonin in nerve endings becomes a joint function of the maintained increased uptake of tryptophan and a decreased level of tryptophan hydroxylase activity in nerve endings. The occurrence of this delayed alteration corresponds in time to the previously described axoplasmic flow rate for tryptophan hydroxylase.
Pronase Effect on Pancreatic Beta Cell Secretion and Morphology
Authors: Orci L. , Amherdt M. , Henquin J. C. , Lambert A. E. , Unger R. H. , Renold A. E.
Published: October 2006

Pronase at low concentration (4 micrograms per milliliter) produces a reversible increase of glucose-stimulated insulin release in isolated islets of Langerhans. Pronase also affects the ultrastructure of the beta cells by inducing extensive development of tight junctions as well as the accumulation of secretory product within the extracellular spaces.
Detection of a Nonuniform Distribution of Polonium-210 on the Moon with the Apollo 16 Alpha Particle Spectrometer
Authors: Bjorkholm Paul , Golub Leon , Gorenstein Paul
Published: October 2006

The polonium-210 activity of the lunar surface is significantly larger than the activity of its progenitor radon-222. This result establishes unequivocally that radon emanation from the present-day moon varies considerably within the 21-year half-life of lead-210, the parent nuclide of polonium-210. There are large variations and well-localized enhancements in polonium-210 activity over much of the moon's surface.
Enzyme Release from Polymorphonuclear Leukocyte Lysosomes: Regulation by Autonomic Drugs and Cyclic Nucleotides
Authors: Ignarro Louis J. , Colombo Carmelo
Published: October 2006

Osmotic release of β-glucuronidase from polymorphonuclear leukocyte lysosomes is inhibited by catecholamines and adenosine 3′,5′-monophosphate, and accelerated by cholinergic agents and guanosine 3′,5′-monophosphate. These actions are specific for the sympathetic and parasympathetic neurotransmitters and for the two cyclic nucleotides, as phenylephrine, tyramine, choline, adenosine 5′-monophosphate and guanosine 5′-monophosphate do not inodify lysosomal enzyme release.
Control of Their Environment Reduces Emotionality in Rats
Authors: Joffe J. M. , Rawson Richard A. , Mulick James A.
Published: October 2006

Rats reared from birth in a "contingent environment" in which they controlled lighting conditions and the delivery of food and water were compared as adults to rats reared in an environment in which they received the same food, water, and lighting conditions, but without control over their occurrence. Rats reared in the contingent environment were less emotional, as judged by activity and defecation scores in open-field testing.
Electrotonic Processing of Information by Brain Cells
Authors: Schmitt Francis O. , Dev Parvati , Smith Barry H.
Published: October 2006

In contrast to well-studied through-projection neurons that propagate information from one region to another in the central nervous system, short-axon or axonless neurons form local circuits, transmitting signals through synapses and electrical junctions between their dendrites. Interaction in this dendritic network proceeds without spike action potentials. Interaction is mediated by graded electrotonic changes of potential and is transmitted through high sensitivity (submillivolt threshold) synapses rather than by the lower sensitivity (20 to 100-mv threshold) synapses typical of projection neurons. A crucial feature of local circuits is their high degree of interaction both through specialized junctional structures and through the extracellular fields generated by local and more distant brain regions.

The anatomical evidence for the nature and distribution of neuronal local circuits in the nervous system is surveyed. Bioelectric mechanisms are discussed in relation to the special properties of local circuits, including dendrodendritic synapses, synaptic sensitivity, electrotonic coupling, and field effects. Intraneuronal and interneuronal transport of various types of substances suggests that the biochemical and the bioelectrical parameters are functionally interwoven. Through such interactions neuronal local circuits, with their distinctive properties, may play an essential role in higher brain function.
Methane in Lake Kivu: New Data Bearing on Its Origin
Authors: Deuser W. G. , Degens E. T. , Harvey G. R. , Rubin M.
Published: October 2006

Lake Kivu, an African rift lake, contains about 50 cubic kilometers of methane (at standard temperature and pressure) in its deep water. Data resulting from two recent expeditions to the lake and a reevaluation of earlier data suggest that most of the methane was formed by bacteria from abiogenetic carbon dioxide and hydrogen, rather than being of volcanic origin or having formed from decomposing organic matter.
L-Dopa in Legume Seeds: A Chemical Barrier to Insect Attack
Authors: Rehr S. S. , Janzen D. H. , Feeny P. P.
Published: October 2006

Seeds of the genus
Mucuna
display both a remarkable immunity to attack by seed-eating insects and an unusually high concentration of free L-dopa. When seed powders or pure L-dopa were incorporated into artificial diets and fed to southern armyworm larvae, mortality increased, and abnormal pupae and adults resulted. At higher concentrations L-dopa acted as a feeding repellent.
Eruption of Soufrière Volcano on St. Vincent Island, 1971-1972
Authors: Aspinall W. P. , Sigurdsson Haraldur , Shepherd J. B.
Published: October 2006

The Soufrière volcano in St. Vincent erupted from October 1971 to March 1972, as 80 × 10
6
m
3
of basaltic andesite lava was quietly extruded inside the mile-wide crater. The eruption was largely subaqueous, taking place in the 180-m-deep crater lake, and resulted in the emergence of a steep-sided island. The mild character of the eruption and the absence of seismic activity stand in direct contrast to the highly explosive character of the eruption of 1902 to 1903.
Observation Is Insufficient for Discovering that the Surface of Still Water Is Invariantly Horizontal
Authors: Thomas Hoben , Jamison Wesley , Hummel Donna D.
Published: October 2006

Among women college students who did not know that the surface of still water in a bottle is always horizontal, two types of specific task procedures designed to elicit self-discovery of the principle were ineffective. Failure to acquire the concept was reflected in inaccurate responses on the adjustment task and by inability of students to verbalize a correct strategy.
Visual Effects on Alpha Feedback Training
Authors: Paskewitz David A. , Orne Martin T.
Published: October 2006

Presenting an audible indication of subjects' electroencephalographic alpha activity under conditions of dim ambient illumination led to systematic increases in alpha density, while in total darkness the same procedure did not. These results support the view that feedback training can be clearly demonstrated only when factors leading to a suppression of alpha activity are present in the environment.
Methylmercury as Percentage of Total Mercury in Flesh and Viscera of Salmon and Sea Trout of Various Ages
Authors: Westöö Gunnel
Published: October 2006

The proportion of methylmercury to total mercury in the flesh of salmon (
Salmo salar
) 1 to 7 years old and sea trout (
Salmo ocla
) 1 and 2 years old was found to average 93 percent with a range of 81 to 98 percent, and to be independent of the age of the fish. In salmon and sea trout 1 and 2 years old, methylmercury constituted 26 to 67 percent of the total visceral mercury, without age dependence.
Photoacoustic Spectroscopy of Biological Materials
Authors: Rosencwaig A.
Published: October 2006

A new technique for performing optical spectroscopy on solids has been developed. Photoacoustic spectra of cytochrome c and hemoglobin show how this technique can be used to obtain information about optical absorptions and subsequent de-excitations in solid biological materials, particularly those which cannot readily be studied by conventional means.
Tubular Packing of Spheres in Biological Fine Structure
Authors: Erickson Ralph O.
Published: October 2006

The symmetrical arrangements of monomers into such cylindrical structures as microfilaments of actin, flagella of bacteria, microtubules of many organisms, and the protein coats of viruses can be specified by citing the index numbers of two or three sets of contact parastichies, or helical ranks of monomers, as has been done in classical studies of phyllotaxis. This specification has the form
k(m, n)
or
k(m, n, m+n),
where
m, n,
and (
m+n
) are parastichy numbers specifying screw displacements, and
k
is the jugacy, or frequency of rotational symmetry. For simple structures,
k
= 1. This notation has the advantage of terseness and of indicating the basic isometries of these helically symmetrical structures.

Theoretical models of the packing of spheres whose centers lie on the surface of a cylinder have been investigated geometrically. Their symmetry properties are discussed. Parameters of these models, such as the angular divergence, α, the longitudinal displacement between successive spheres,
h,
the radius of the cylinder, and the angles of inclination of the parastichies, have been computed for representative patterns.

The ultrastructural symmetry of several biological structures of this sort has been inferred by comparison with these models. Actin, for example, has the symmetry (1, 2),
Salmonella
flagella, 2(2, 3, 5), the tobacco mosaic virus, (1, 16, 17) and the microtubules of many higher organisms, (6, 7, 13).
Contemporary Phosphorites on the Continental Margin of Peru
Authors: Veeh H. Herbert , Burnett William C. , Soutar Andrew
Published: October 2006

Phosphorite nodules occurring along the biologically productive continental margin of Peru have been dated by uranium-series methods. The radiometric ages range from late Pleistocene to Recent, indicating that phosphorites are currently forming in this area.
Infusion of 2-Deoxy-D-Glucose into the Hepatic-Portal System Causes Eating: Evidence for Peripheral Glucoreceptors
Authors: Novin Donald , VanderWeele Dennis A. , Rezek Milan
Published: October 2006

Injections of 2-deoxyglucose into the hepatic-portal system of normal rabbits increased eating to a greater extent and with shorter latency than comparable injections of 2-deoxyglucose into the jugular vein or into the hepaticportal circulation of the vagotomized rabbit. These differences suggest the existence of vagally mediated peripheral glucoreceptors important in the initiation of food intake.
Clarification of the Chemical Status of the Pink Bollworm Sex Pheromone
Authors: Hummel H. E. , Gaston Lyle K. , Shorey H. H. , Kaae R. S. , Byrne Kevin J. , Silverstein Robert M.
Published: October 2006

Propylure, 10-
n
-propyl-
trans
-5,9-tridecadienyl acetate, and deet,
N
,
N
,-diethyl-
m
-toluamide, were previously reported as the sex pheromone and a sex pheromone activator, respectively, of the pink bollworm. Neither chemical in three extracts of female moth abdomen tips could be detected by gas-liquid chromatographic analysis. These compounds, alone or in combination, exhibited little or no biological activity in the laboratory or in the field. Hexalure,
cis
-7-hexadecenyl acetate, a synthetic attractant for pink bollworm males, could not be detected in female moth abdomen tip extracts. The pink bollworm sex pheromone was identified as a mixture of
cis
,
cis
and
cis
,
trans
isomers of 7,11-hexadecadienyl acetate.
Scroll-Shaped Waves of Chemical Activity in Three Dimensions
Authors: Winfree Arthur T.
Published: October 2006

Ferric ions catalyze the oxidation of malonate by bromate in acid solution, sometimes at a spatially uniform, steady rate, but sometimes in a self-regenerating three-dimensional wave which resembles a rotating scroll, often with its axis closed in a ring. In cross section perpendicular to the axis, one sees an involute spiral emerging from a thin cylindrical core. This "dissipative structure" organizes reaction stages periodically in space and time everywhere except along its rotation axis, which may therefore be a thermodynamically unique locus.
Mouse Immunoglobulin Kappa Chain MPC 11: Extra Amino-Terminal Residues
Authors: Smith George P.
Published: October 2006

The kappa chain from the immunoglobulin of myeloma tumor MPC 11 has 12 extra residues at its amino terminus, the first six of which are identical to the residues at positions 1 to 6 of typical mouse kappa chains and at positions 13 to 18 of MPC 11 itself. Two of the peptide bonds within this extra 12-residue segment are cleaved under very mild conditions.
Climatic Change on Mars
Authors: Sagan Carl , Toon O. B. , Gierasch P. J.
Published: October 2006

The equatorial sinuous channels on Mars detected by Mariner 9 point to a past epoch of higher pressures and abundant liquid water. Advective instability of the martian atmosphere permits two stable climates—one close to present conditions, the other at a pressure of the order of 1 bar depending on the quantity of buried volatiles. Variations in the obliquity of Mars, the luminosity of the sun, and the albedo of the polar caps each appear capable of driving the instability between a current ice age and more clement conditions. Obliquity driving alone implies that epochs of much higher and of much lower pressure must have characterized martian history. Climatic change on Mars may have important meteorological, geological, and biological implications.
Dopamine-Sensitive Adenylate Cyclase Occurs in a Region of Substantia Nigra Containing Dopaminergic Dendrites
Authors: Kebabian John W. , Saavedra Juan M.
Published: October 2006

The zona reticulata, the subdivision of the substantia nigra containing dendrites of the dopaminergic nigro-neostriatal neurons, contains dopamine-sensitive adenylate cyclase activity. This nigral dopamine receptor is similar to the striatal dopamine receptor. These and previous data suggest a physiological role (or roles) for dopamine in the substantia nigra.
The Lunar Laser Ranging Experiment
Authors: Bender P. L. , Currie D. G. , Poultney S. K. , Alley C. O. , Dicke R. H. , Wilkinson D. T. , Eckhardt D. H. , Faller J. E. , Kaula W. M. , Mulholland J. D. , Plotkin H. H. , Silverberg E. C. , Williams J. G.
Published: October 2006

The lunar ranging measurements now being made at the McDonald Observatory have an accuracy of 1 nsec in round-trip travel time. This corresponds to 15 cm in the one-way distance. The use of lasers with pulse-lengths of less than 1 nsec is expected to give an accuracy of 2 to 3 cm in the next few years. A new station is under construction in Hawaii, and additional stations in other countries are either in operation or under development. It is hoped that these stations will form the basis for a worldwide network to determine polar motion and earth rotation on a regular basis, and will assist in providing information about movement of the tectonic plates making up the earth's surface. Several mobile lunar ranging stations with telescopes having diameters of 1.0 m or less could, in the future, greatly extend the information obtainable about motions within and between the tectonic plates.

The data obtained so far by the McDonald Observatory have been used to generate a new lunar ephemeris based on direct numerical integration of the equations of motion for the moon and planets. With this ephemeris, the range to the three Apollo retroreflectors can be fit to an accuracy of 5 m by adjusting the differences in moments of inertia of the moon about its principal axes, the selenocentric coordinates of the reflectors, and the McDonald longitude. The accuracy of fitting the results is limited currently by errors of the order of an arc second in the angular orientation of the moon, as derived from the best available theory of how the moon rotates in response to the torques acting on it. Both a new calculation of the moon's orientation as a function of time based on direct numerical integration of the torque equations and a new analytic theory of the moon's orientation are expected to be available soon, and to improve considerably the accuracy of fitting the data.

The accuracy already achieved routinely in lunar laser ranging represents a hundredfold improvement over any previously available knowledge of the distance to points on the lunar surface. Already, extremely complex structure has been observed in the lunar rotation and significant improvement has been achieved in our knowledge of lunar orbit. The selenocentric coordinates of the retroreflectors give improved reference points for use in lunar mapping, and new information on the lunar mass distribution has been obtained. Beyond the applications discussed in this article, however, the history of science shows many cases of previously unknown phenomena discovered as a consequence of major improvements in the accuracy of measurements. It will be interesting to see whether this once again proves the case as we acquire an extended series of lunar distance observations with decimetric and then centimetric accuracy.
Crowding among Hunter-Gatherers: The !Kung Bushmen
Authors: Draper Patricia
Published: October 2006

Highly crowded living conditions exist among the !Kung Bushmen, hunter-gatherers who live on the edges of the Kalahari Desert in Botswana and South-West Africa. The !Kung appear to be crowded by choice, and biological indicators of stress are absent. Data indicate that residential crowding alone does not produce symptoms of pathological stress.
Species Introduction in a Tropical Lake
Authors: Zaret Thomas M. , Paine R. T.
Published: October 2006

Probably in early 1967, a piscivore from South America,
Cichla ocellaris
, was introduced to Gatun Lake in the Panama Canal Zone. As this predator population spread through the lake, the initial effect was dramatic reductions in almost all secondary consumers. These species reductions produced, in turn, second- and third-order changes at other trophic levels of the ecosystem. The resulting changes in the lake community can be seen best by examining the general Gatun Lake food web. The decrease in numbers of the important planktivore
Melaniris
has resulted in changes within the zooplankton community, as illustrated by the cladoceran
Ceriodaphnia
. The tertiary-consumer populations, such as tarpon, black terns, kingfishers, and herons, formerly dependent on small fishes for food, appear less frequently in the
Cichla
areas of the lake. There has also been, possibly, a resurgence of the local mosquito populations (which are malaria vectors), caused by the reduction in the populations of insect-eating fishes. Even the primary producers may be affected by this introduction. Although at present the Gatun Lake ecosystem is undergoing rapid changes, we anticipate an eventual return to some form of equilibrium. However, it will be some time before we can evaluate the permanence or transience of the many changes produced in the trophic levels by the introduction of a single, top-level predator to this lake system.
Pentobarbital: Selective Depression of Excitatory Postsynaptic Potentials
Authors: Barker Jeffery L. , Gainer Harold
Published: October 2006

The effects of pentobarbital (Nembutal) on synaptic transmission and postsynaptic potentials were studied by the use of several invertebrate preparations. Pentobarbital selectively and reversibly depressed both excitatory postsynaptic potentials and sodium-dependent postsynaptic responses to putative excitatory transmitters without affecting either inhibitory postsynaptic potentials or chloride- and potassium-dependent postsynaptic responses to putative transmitters. A selective depression of postsynaptic excitatory events was also observed with other central nervous system depressants (ethanol, chloroform, chloralose, diphenylhydantoin, and urethane). The results suggest that central and peripheral depression observed during general anesthesia is due to a selective depression of excitatory synaptic events.
Predatory Attack, Grooming, and Consummatory Behaviors Evoked by Electrical Stimulation of Cat Cerebellar Nuclei
Authors: Reis Donald J. , Doba Nobutaka , Nathan Marc A.
Published: October 2006

Electrical stimulation at single sites in the rostral fastigial nucleus elicits hypertension, grooming, feeding, and attack behaviors in the cat. The stimulus intensity and availability of suitable goal objects determines the behavior. Bilateral lesions of the area fail to produce motor deficits. The rostral fastigial nucleus may be a cerebellar area for behavioral and autonomic regulation.
Social Rank in House Mice: Differentiation Revealed by Ultraviolet Visualization of Urinary Marking Patterns
Authors: Desjardins Claude , Maruniak J. A. , Bronson F. H.
Published: October 2006

Ultraviolet light has been used to examine urine marks deposited by adult male house mice on filter paper on the floors of their cages during overnight tests. Both the urination frequency and the pattern in which urine was deposited on the filter paper depended upon social rank. Dominant males vigorously marked their entire cage floor, whereas subordinate males typically voided urine in only two to four pools in the corners of their cages.
Direct Evidence for a Colchicine-Induced Impairment in the Mobility of Membrane Components
Authors: Wunderlich F. , Müller R. , Speth V.
Published: October 2006

Freeze-etch electron microscopy was used to show that colchicine interacts with membranes of the ciliate protozoan
Tetrahymena pyriformis
. Colchicine impairs the temperature-induced translational and vertical mobility of the membrane-intercalating particles of the freeze-fractured alveolar membranes lying just below the plasma membranes.
Neuron Geometry and Circuitry via the Electron Microscope: Intracellular Staining with Osmiophilic Polymer
Authors: Gillette Rhanor , Pomeranz Bruce
Published: October 2006

Intracellularly injected cobalt catalyzes the generation of an osmiumbinding polymer from 3,3′-diaminobenzidine in neurons of
Aplysia californica
Excellent structural preservation of nervous tissue is coupled with easy recognition of fine branches of the injected neurons in the electron microscope. This permits detailed structural analysis of synaptology.
Neurons of the Hypothalamus Concentrate [
3
H]Progesterone or Its Metabolites
Authors: Sar Madhabananda , Stumpf Walter E.
Published: October 2006

Selective concentration of [
3
H]progesterone or its metabolites is observed in nuclei of neurons in certain hypothalamic regions of the guinea pig 15 minutes after injection of [1,2,6,7-
3
H]progesterone, by use of dry-mount autoradiography. Highest concentrations of progestin target neurons exist in the nucleus arcuatus, the nucleus preopticus periventricularis, and the nucleus preopticus suprachiasmaticus. Previous administration of unlabeled progesterone inhibits the nuclear concentration of radioactivity, but cortisol has no effect. Estradiol priming enhances the nuclear uptake of radioactivity. The results demonstrate the existence of progestin target sites in the hypothalamus and suggest a direct action of progestin on certain hypothalamic structures.
A Model for the Adjustment of the Mitotic Clock by Cyclin and MPF Levels
Authors: Norel R. , Agur Z.
Published: October 2006

A mathematical model of cell cycle progression is presented, which integrates recent biochemical information on the interaction of the maturation promotion factor (MPF) and cyclin. The model retrieves the dynamics observed in early embryos and explains how multiple cycles of MPF activity can be produced and how the internal clock that determines durations and number of cycles can be adjusted by modulating the rate of change in MPF or cyclin concentrations. Experiments are suggested for verifying the role of MPF activity in determining the length of the somatic cell cycle.
Aerosols and Climate
Authors: Chlek Petr , Coakley James A.
Published: October 2006

To determine the effects of atmospheric aerosols on the radiative heating of the earth-atmosphere system, the radiative transfer equation is solved analytically in the two-stream approximation. It is found that the sign of the heating is independent of optical thickness of an aerosol layer and the amount of heating approaches a finite limit with increasing thickness of a layer. Limitations of the two-stream approximation are discussed.
Atmospheric Concentrations and Sources of Trace Metals at the South Pole
Authors: Zoller W. H. , Gladney E. S. , Duce R. A.
Published: October 2006

The chemical composition of atmospheric particulate material collected at the geographic South Pole indicates that Al, Sc, Th, Sm, V, Mn, Eu, Fe, La, Ce, Co, Cr, Na, K, Mg, and Ca are derived from either crustal weathering or the ocean. The relatively volatile elements Zn, Cu, Sb, Se, Pb, and Br are apparently derived from other sources. Because of their volatility, vapor-phase condensation or a high-temperature dispersion source is suspected for these elements or their compounds.
Toxic Trace Elements: Preferential Concentration in Respirable Particles
Authors: Natusch D. F. S. , Wallace J. R. , Evans C. A.
Published: October 2006

The toxic trace elements arsenic, antimony, cadmium, lead, selenium, and thallium were found to be most concentrated in the smallest respirable particles emitted from coal-fired power plants. These elements, or their compounds, are probably volatilized during combustion and preferentially adsorb or condense onto the small particles which can most easily pass through conventional control equipment.
Acetylenic Analog of Arachidonate That Acts Like Aspirin on Platelets
Authors: Willis A. L. , Kuhn D. C. , Weiss H. J.
Published: October 2006

Development of irreversible platelet aggregation and the accompanying release of platelet-bound serotonin and production of prostaglandins is suppressed by 5,8,11,14-eicosatetraynoic acid (TYA). These findings may be explained by an ability of TYA to inhibit the enzymatic conversion of arachidonate to a newly recognized factor, labile aggregation-stimulating substance, which induces platelet aggregation, and to prostaglandins E2and F2α.
Slaty Cleavage: Incipient Occurrences in the Deep Sea
Authors: Moore J. Casey , Geigle James E.
Published: October 2006

Highly deformed Pleistocene mudstones from the inner wall of the Aleutian Trench and from the continental rise of the Gulf of Mexico show incipient slaty cleavage defined by the orientation of platy and elongate detrital minerals parallel to the axial surfaces of folds.
Tumor Development after 3-Methylcholanthrene in Immunologically Deficient Athymic-Nude Mice
Authors: Stutman Osias
Published: October 2006

Athymic-nude (
nu/nu
) mice and normal (
nu/+
) mice showed no differences in either latent period or incidence of local sarcomas or lung adenomas within 120 days after administration of 3-methylcholanthrene at birth. However,
nu/nu
mice were incapable of rejecting allogeneic skin grafts for the duration of the experiment. These results argue against an active role of thymus-dependent immunity as a surveillance mechanism preventing tumor development.
Carbon Dioxide Hydrate and Floods on Mars
Authors: Milton Daniel J.
Published: October 2006

Ground ice on Mars probably consists largely of carbon dioxide hydrate, CO
2
⋅ 6H
2
O. This hydrate dissociates upon release of pressure at temperatures between 0° and 10°C. The heat capacity of the ground would be sufficient to produce up to 4 percent (by volume) of water at a rate equal to that at which it can be drained away. Catastrophic dissociation of carbon dioxide hydrate during some past epoch when the near surface temperature was in this range would have produced chaotic terrain and flood channels.
Autogenous Regulation of Gene Expression
Authors: Goldberger Robert F.
Published: October 2006

A new term, autogenous regulation, is used to describe a phenomenon that is not a new discovery but rather is newly appreciated as a mechanism common to a number of systems in both prokaryotic and eukaryotic organisms. In this mechanism the product of a structural gene regulates expression of the operon in which that structural gene resides. In many (perhaps all) cases, the regulatory gene product has several functions, since it may act not only as a regulatory protein but also as an enzyme, structural protein, or antibody, for example. In a few cases, this protein is the multimeric allosteric enzyme that catalyzes the first step of a metabolic pathway, gearing together the two most important mechanisms for controlling the biosynthesis of metabolites in bacterial cells—feedback inhibition and repression. Autogenous regulation may provide a mechanism for amplification of gene expression; for severe and prolonged inactivation of gene expression; for buffering the response of structural genes to changes in the environment; and for maintaining a constant intracellular concentration of a protein, independent of cell size or growth rate. Thus, autogenous regulation provides the cell with means for accomplishing a number of different regulatory tasks, each suited to better satisfying the needs of the organism for its survival.
Infant Color Perception
Authors: Fagan Joseph F.
Published: October 2006

Human infants 4 to 6 months of age devoted more visual fixation to checkerboards composed of two Munsell hues equated for brightness and saturation than to unpatterned targets of either hue. Strength of pattern preference was positively related to degree of hue difference in the checkerboards.
Radioreceptor Assay for 1α,25-Dihydroxyvitamin D
3
Authors: Brumbaugh Peter F. , Haussler David H. , Bressler Rubin , Haussler Mark R.
Published: October 2006

A competitive protein binding assay with a sensitivity of 80 picograms has been developed for 1α,25-dihydroxyvitamin D
3
, the hormonal form of vitamin D
3
. 1α,25-Dihydroxyvitamin D
3
displaced tritiated hormone from a cytosol-chromatin receptor preparation isolated from chick small intestine, providing a simple assay for the hormone. The concentration of 1α,25-dihydroxyvitamin D
3
in human plasma, as determined by this assay, is approximately 6 nanograms per 100 milliliters; in patients with renal disease the concentration of this kidney-produced hormone is significantly lower.
Diarrhea Toxin Obtained from a Waterbloom-Producing Species,
Microcystis aeruginosa
Ktzing
Authors: Aziz K. M. S.
Published: October 2006

A diarrhea-producing toxin from a blue-green alga,
Microcystis aeruginosa
Ktzing, was obtained from standing laboratory cultures. The non-dialyzable fraction of the lysate from whole cells produced fluid accumulation in the ligated small intestinal loops in guinea pigs.
Separation of IL-4 Production from Th Cell Proliferation by an Altered T Cell Receptor Ligand
Authors: Evavold Brian D. , Allen Paul M.
Published: October 2006

In the presence of antigen presenting cells, a murine T helper (Th) cell specific for murine hemoglobin (Hb) responded to its immunogenic peptide by both cytokine (interleukin-4) secretion and proliferation. An altered Hb peptide with a single amino acid substitution induced only cytokine secretion and did not induce proliferation. Interleukin-1 costimulated and restored the Th proliferative response to normal levels. The altered peptide also supported cognate T cell-B cell interactions indicative of T cell helper function. Thus, this result suggests that the T cell receptor has the capacity of differential signaling.
NMDA Antagonist Neurotoxicity: Mechanism and Prevention
Authors: Olney J. W. , Labruyere J. , Wang G. , Wozniak D. F. , Price M. T. , Sesma M. A.
Published: October 2006

Antagonists of theN-methyl-D-aspartate (NMDA) subtype of glutamate receptor, including phencyclidine (PCP) and ketamine, protect against brain damage in neurological disorders such as stroke. However, these agents have psychotomimetic properties in humans and morphologically damage neurons in the cerebral cortex of rats. It is now shown that the morphological damage can be prevented by certain anticholinergic drugs or by diazepam and barbiturates, which act at the γ-aminobutyric acid (GABA) receptor-channel complex and are known to suppress the psychotomimetic symptoms caused by ketamine. Thus, it may be possible to prevent the unwanted side effects of NMDA antagonists, thereby enhancing their utility as neuroprotective drugs.
Biogenic Amines and Control of Melanophore Stimulating Hormone Release
Authors: Bower Annette , Hadley Mac E. , Hruby Victor J.
Published: October 2006

Release of melanophore stimulating hormone (MSH) from the vertebrate pars intermedia is under inhibitory control by the hypothalamus. Removal of the rat pituitary or the neurointermediate lobe of the frog (
Rana pipiens
) to in vitro incubation medium results in rapid uninhibited release of MSH. This secretion is inhibited by norepinephrine, epinephrine, phenylephrine, and dopamine, and the inhibition is antagonized by α-adrenergic receptor blocking agents. Isoproterenol stimulation of MSH secretion from isolated glands is blocked by pro-pranolol, a β-adrenergic receptor antagonist. These results implicate dopaminergic or classical α-adrenergic receptors (or both) in inhibition of MSH release by catecholamines, and implicate β-adrenergic receptors in stimulation of MSH release by the bioamines.
Norepinephrine-Sensitive Adenylate Cyclases in Rat Brain: Relation to Behavior and Tyrosine Hydroxylase
Authors: Sklnick Phil , Daly John W.
Published: October 2006

Responses of norepinephrine-sensitive adenosine 3′,5′-monophosphate (cyclic AMP)-generating systems in combined midbrain-striatal slices of four rat strains correlate positively with spontaneous behavioral activity and negatively with levels of midbrain and striatal tyrosine hydroxylase. Responses of cerebral cortical norepinephrine-sensitive cyclic AMP systems correlate negatively with spontaneous behavioral activity and positively with midbrain and striatal tyrosine hydroxylase. Such correlations were not found with responses of the cyclic AMP-generating systems to isoproterenol, adenosine, veratridine, or of an adenosine and norepinephrine combination.
Cleaning Symbiosis Provides a Positive Reinforcer for Fish
Authors: Losey George S. , Margules Lynn
Published: October 2006

Chaetodon auriga
, a common marine fish in Hawaii, can be conditioned by presentation of a moving model of a cleaner fish as a positive reinforcement on an instrumental schedule. Reinforcement is probably through tactile stimulation and might help to shape the response of fish to cleaners. Tactile stimulation might serve as a valuable reinforcer in studies of fish learning.
Radioreceptor Assay of Human Chorionic Gonadotropin: Detection of Early Pregnancy
Authors: Saxena B. B. , Hasan S. H. , Haour F. , Schmidt-Gollwitzer M.
Published: October 2006

A rapid, sensitive, and specific radioreceptor assay for the determination of human chorionic gonadotropin and luteinizing hormone in plasma is described. Plasma membranes of bovine corpora lutea of early pregnancy, which bind biologically active labeled human chorionic gonadotropin, have been used as receptor. Pregnancy could be detected by assaying the gonadotropin in plasma samples obtained from day 6 to 8 after conception.
Factors of Human Chronic Pain: An Analysis of Personality and Pain Reaction Variables
Authors: Timmermans Gretchen , Sternbach Richard A.
Published: October 2006

Factor analysis of pain and personality test data obtained from 119 patients with chronic pain syndromes yields seven factors: four composed of personality measures, two involving different psychophysical pain measures, and one sex-related factor. The chief factors, comprising more than 50 percent of the total variance, are "interpersonal alienation and manipulativeness," "clinical pain intensity," and "pain endurance."
Holocene Stratigraphy and Archeology in the Middle Missouri River Trench, South Dakota
Authors: Ahler Stanley A. , Davies David K. , Falk Cari R. , Madsen David B.
Published: October 2006

Shoreline erosion along man-made lakes in North Dakota and South Dakota has led to the discovery of stratified preceramic cultural remains in an area where previously few such materials have been found. One important exposure, the Walth Bay site, contains a 7000-year sequence of alluvial and eolian deposition capping an abandoned Missouri River terrace. Three distinct soil profiles are associated with successive Late Paleo-Indian, Plains Archaic, and Plains Village Tradition occupations.
Possible Consequences of Nearby Supernova Explosions for Atmospheric Ozone and Terrestrial Life
Authors: Ruderman M. A.
Published: October 2006

Hard x-ray pulses or increased cosmic radiation originating in nearby supernova explosions may be capable of temporarily removing most of the earth's atmospheric ozone cover even when direct radiation effects at the earth's surface are negligible. Consequently, terrestrial life may be subject to relatively huge solar ultraviolet fluxes every few hundred million years.
Taurine Concentrations in Congestive Heart Failure
Authors: Huxtable Ryan , Bressler Rubin
Published: October 2006

The concentration of taurine in the left ventricular muscle of hearts of patients who died of chronic congestive heart failure was twice that of patients who died of other causes and had no cardiac pathology. There was no corresponding difference in taurine concentrations in aortic tissue between the two groups. Stress-induced hypertension in rats also led to an increase in taurine concentration in the heart, whereas that in skeletal muscle and brain showed no significant alteration when compared to unstressed animals. Spontaneously hypertensive rats, of the Wistar-derived Okamato strain, showed a similar elevation in cardiac taurine compared to age-matched control Wistar rats.
Operant Conditioning of Single-Unit Response Patterns in Visual Cortex
Authors: Shinkman Paul G. , Bruce Charles J. , Pfingst Bryan E.
Published: October 2006

Unit responses to photic stimuli were studied in cat visual cortex. After the baseline response pattern of a cell was determined, conditioning trials were given during which reinforcement was contingent upon increased firing during a selected segment of the poststimulus interval. Density of reinforcement increased substantially in about half the cells studied; significant increases in firing occurred within, but not outside, the criterion segment.
Pollination by Ants: A Low-Energy System
Authors: Hickman James C.
Published: October 2006

Polygonum cascadense
, a small, apparently self-incompatible, annual plant, is regularly cross-pollinated by the ant
Formica argentea
. Comparison of other purported ant-pollinated plants with traits favoring such pollination suggests that some, but not all, may be ant pollinated. Ant-pollination interactions are characterized by low expenditure of energy by both ant and plant.
"Decision"-Making in Bacteria: Chemotactic Response of
Escherichia coli
to Conflicting Stimuli
Authors: Adler Julius , Tso Wung-Wai
Published: October 2006

Motile bacteria presented simultaneously with both attractant and repellent respond to whichever one is present in the more effective concentration. Apparently bacteria have a processing mechanism that compares opposing signals from the chemoreceptors for positive and negative taxis, sums these signals up, and then communicates the sum to the flagella.
Cell-Cycle Analysis in 20 Minutes
Authors: Crissman Harry A. , Tobey Robert A.
Published: October 2006

Mithramycin added to mammalian cells fixed in aqueous ethanol is bound to DNA and fluoresces in direct proportion to the cellular DNA content. Quantitative fluorescence measurement by means of a high-speed flow system instrument provides a rapid method for cell-cycle analysis and for the first time permits continuous monitoring of cell-cycle kinetics during ongoing experiments.
Permeation of Calcium Ions Through Non-NMDA Glutamate Channels in Retinal Bipolar Cells
Authors: Gilbertson Timothy A. , Scobey Robert , Wilson Martin
Published: October 2006

The conduction of calcium ions through glutamate-gated channels is important in the induction of long-term potentiation and may trigger other cellular changes. In retinal bipolar cells, which lack the
N
-methyl-D-aspartate (NMDA) type of glutamate-gated channel, calcium permeability through non-NMDA channels was examined. Changes in extracellular calcium concentration unexpectedly affected the reversal potential for glutamate-induced currents in a manner consistent with these channels being highly permeable to calcium. External magnesium ions promote desensitization of these non-NMDA channels in a voltage-independent way. Thus, in addition to non-NMDA channels that conduct only sodium and potassium, there is a class that is also permeable to calcium.