bluuebunny/crossref_metadata_2025 huggingface dataset:
Lethal Alleles in
Mus musculus
: Local Distribution and Evidence for Isolation of Demes
Authors: Anderson Paul K.
Published: October 2006

In the vicinity of Calgary, Alberta, 20.5 percent of wild house mice tested were found to be heterozygous for the lethal allele designated t
w5
, and an additional 3.4 percent were heterozygous for one or more alleles not belonging to the t
w5
group. The distribution patterns of wild-type and lethal alleles within and between clusters of small demes supports the postulate that random drift plays a significant role in the evolution of these populations. Distribution patterns also suggest that the demes are reproductively isolated to a greater degree than has been generally assumed.
Enhancement of Evoked Cortical Potentials in Humans Related to a Task Requiring a Decision
Authors: Davis Hallowell
Published: October 2006

The averaged, slow response evoked by auditory stimuli and recorded from the vertex of the human skull can usually be enhanced by requiring the listener to make a rather difficult auditory discrimination. An easy routine reaction is not effective.
Structural Differences between Two Types of "Heavy Chain" Disease Proteins and Myeloma Globulins of Corresponding Types
Authors: Takatsuki Kiyoshi , Osserman Elliott F.
Published: October 2006

Structural differences between two antigenic types (designated C and Z) of γ-globulins, both of low molecular weight, produced in "Heavy chain" disease are revealed by their relative susceptibilities to enzymatic degradation by papain and the nature of the cleavage products. Corresponding structural differences exist between the respective type C and type Z myeloma γ
2
-globulins. These structural differences are tentatively assigned to the H-chains, and more specifically to the portion of the H-chain contained in the fast-moving (F) fragment of papain-treated γ
2
-globulins.
Calcite-Dolomite-Magnesite Stability Relations in Solutions at Elevated Temperatures
Authors: Rosenberg P. E. , Holland H. D.
Published: October 2006

The stability relations of calcite, dolomite, and magnesite in aqueous CaCl
2
-MgCl
2
-CO
2
solutions have been determined between 275° and 420°C. Small quantities of the carbonates were allowed to equilibrate with large volumes of aqueous solutions, permitting the approach of phase boundaries from two directions. Experimental data indicate that the stability field of calcite narrows toward higher temperatures, dolomite is incongruently soluble, and magnesite stability extends into the calcium-rich portion of the system.
Histones: Species and Tissue Specificity
Authors: Neidle Amos , Waelsch Heinrich
Published: October 2006

Within a given species (rat, mouse, guinea pig, rabbit) the histones of brain, liver, and kidney are indistinguishable on disc electrophoresis in polyacrylamide gels. However, characteristic species differences were observed. In the immature rat, the histones of brain and liver, while very similar to each other, differ from those of the adult. The histones of the thymus of the immature and adult rat exhibited a pattern corresponding to that of the immature brain and liver.
Regulation of the Differentiation of Teratocarcinoma Cells into Primitive Endoderm by Gβ
i2
Authors: Watkins David C. , Johnson Gary L. , Malbon Craig C.
Published: October 2006

The amount of the heterotrimeric G protein subunit Gα
i2
decreases after the induction of F9 teratocarcinoma cells to become primitive endoderm in the presence of retinoic acid (RA). The reduction of the Gα
i2
protein in F9 cells by antisense RNA expression was associated with (i) loss of receptor-mediated inhibition of adenylyl cyclase; (ii) decreased cell doubling time; (iii) induction of a primitive, endoderm-like phenotype in the absence of RA; and (iv) production of the differentiation marker tissue-type plasminogen activator. Expression of a constitutively active, mutant Gα
i2
blocked RA-induced differentiation. These data suggest the involvement of Gα
i2
in the control of stem cell differentiation and provide insight into the involvement of G proteins in growth regulation.
Growth of Oxalic Acid Single Crystals from Solution: Solvent Effects on Crystal Habit
Authors: Torgesen John L. , Strassburger John
Published: October 2006

Single crystals of oxalic acid dihydrate are difficult to grow from pure water solution, but good single crystals of the material may be obtained by growth from mixtures of acetone and water. The solvent markedly affects the crystal habit. Crystals grown in mixtures of acetone and water develop the prismatic habit, while those grown in water alone develop the tabular or equant habit. The forms {001}, {110}, and {101} predominate in all cases. Single crystals of anhydrous oxalic acid may also be grown from solution in glacial acetic acid, although specimens more than 2 centimeters in length are difficult to produce.
Phytohemagglutinin Elicitation of Specific Anamnestic Immune Response in vitro
Authors: Tao Tien-Wen
Published: October 2006

Fragments of lymph nodes from rabbits hyperimmunized with human chorionic gonadotropin or bovine plasma albumin were cultivated in organ culture for 1 month. An anamnestic response was elicited in vitro by the sensitizing antigen. Phytohemagglutinin also produced such a response. Throughout cultivation the cultures showed excellent preservation of morphological integrity and of capacity to produce antibody.
Hue-Wavelength Relation Measured by Color-Naming Method for Three Retinal Locations
Authors: Boynton Robert M. , Schafer William , Neun Mary Ellen
Published: October 2006

A method of hue measurement, in which an absolute color-naming procedure is utilized, has been applied to spectral stimuli delivered as flashes at 0 degrees, 20 degrees, and 40 degrees eccentricity in an otherwise dark field. The method yields very reliable measures, especially at 0 degrees. Color-naming at 0 degrees differs little from that at 20 degrees, but a marked deterioration of performance occurs between 20 and 40 degrees. This is reflected by a reduction in red and especially green responses, and a lower reliability of the measurements. Additional estimates were also obtained which showed a decrease in measured saturation but increasing reliability of the saturation measurements with increasing eccentricity.
Esterase Inhibitors as Pesticides
Authors: Casida John E.
Published: October 2006

Thirty years of testing has yielded over 120 esterase inhibitors in current use for pest control. Several hundred million pounds of these organophosphates and carbamates are employed each year as insecticides and acaricides and, to a much lesser extent, as anthelmintic agents, nematocides, and herbicides. Systemics or chemotherapeutic agents for control of insect pests of plants and animals first became practical with the organophosphates. Compounds of lower mammalian toxicity and other favorable biological properties continue to appear and displace established compounds and broaden the use areas. Problems of resistance and residues in certain areas of insect control by chlorinated hydrocarbons will result in a further shift to esterase-inhibitors for pest control. Interpretation of the potential hazards of pesticides to man is dependent on the availability of fundamental information on their modes of action combined with use experience; this knowledge is available for the organophosphates and carbamates that act as acetylcholinesterase inhibitors.
High-Pressure B-Type Polymorphs of Some Rare-Earth Sesquioxides
Authors: Hoekstra Henry R. , Gingerich Karl A.
Published: October 2006

New high pressure forms of the sesquioxides of holmium, erbium, thulium, ytterbium, lutetium, and yttrium have been obtained by exposure of the C-type sesquioxides to pressures between 25 and 40 kilobars and temperatures between 900° and 1020°C. X-ray diffraction analysis shows that these new high-pressure phases are of the monoclinic B-type which is known for several of the lighter rare-earth sesquioxides (samarium through dysprosium).
Replacement Rates for Human Tissue from Atmospheric Radiocarbon
Authors: Libby W. F. , Berger Rainer , Mead J. F. , Alexander G. V. , Ross J. F.
Published: October 2006

Carbon-14, derived from the testing of thermonuclear weapons in the atmosphere of the Northern Hemisphere during 1961-62, has been found in human tissues including the brain in amounts which reflect the atmospheric concentration of carbon-14 as of several months earlier. In collagen of cartilage, the rate of uptake of carbon-14 is much slower than in other tissues; essentially no radioactive carbon was found in the collagen of 70-year-old adults that had been exposed to the comparatively high concentrations of carbon-14 in the atmosphere during the years 1954 to 1964. Individuals from the Southern Hemisphere show little increase in the carbon-14 content of their tissues at present, and detailed tests with individuals traveling to the Northern Hemisphere from the Southern allow closer scrutiny of the tissue replacement rates.
Catnip: Its
Raison d'Être
Authors: Eisner Thomas
Published: October 2006

Catnip (nepetalactone) is closely related chemically to certain cyclopentanoid monoterpenes recently isolated from insects, and it shares with some of these terpenes an ability to repel insects. It is suggested that the adaptive function of catnip is to protect the plants that produce it against phytophagous insects.
Interferon-Like Viral Inhibitor in Rabbits after Intravenous Administration of Endotoxin
Authors: Ho Monto
Published: October 2006

Intravenous injection into rabbits of endotoxin or killed cells of
Escherichia coli
induced, in 1 hour, a viral inhibitor detectable in serum. The inhibitor disappeared from the serum in 7 to 24 hours, and was only active after incubation with rabbit cell cultures. Like interferon, it did not preferentially inactivate virus directly, was ineffective in chick cells, was inactivated by trypsin, and was not sedimentable. Unlike interferon, the inhibitor was heat labile. Nucleic acid or nucleotides apparently play no role in its induction.
Allergic Encephalomyelitis: A Hyperacute Form
Authors: Levine Seymour , Wenk Eugene J.
Published: October 2006

The hyperacute form of allergic encephalomyelitis is characterized by its short incubation period, 100 percent incidence, overwhelming severity, and high mortality and by the massive quantities of polymorphonuclear neutrophils, fibrin, and edema fluid which infiltrate the central nervous system. The hyperacute form has been produced with the aid of aqueous pertussis vaccine as an adjuvant. This is the first reproducible laboratory model for human acute necrotizing hemorrhagic encephalopathy.
Boron: Another Form
Authors: Wentorf R. H.
Published: October 2006

A hitherto undescribed form of boron can be prepared by subjecting ordinary forms of boron to pressures exceeding about 100 kilobars and temperatures between about 1500° to 2000°C. The new form has a density of about 2.52 g/cm
3
and yields a characteristic DeBye-Scherrer pattern. No large crystals have been prepared.
Long-Lived Messenger RNA: Evidence from Cotton Seed Germination
Authors: Dure Leon , Waters Larry
Published: October 2006

In germinating cotton embryos the partial inhibition of RNA synthesis by actinomycin D does not inhibit the incorporation of leucine-
14
C into soluble protein nor cause a loss of polyribosomes during the first 16 hours of germination. This suggests that the protein synthesis observed during this period is directed by messenger RNA which exists in the mature seed and which is not rapidly degraded and resynthesized.
Carbonate in Hydroxylapatite
Authors: Simpson Dale R.
Published: October 2006

Unit cell dimensions of hydroxylapatite synthesized hydrothermally are
a
0
= 9.42
6
Å and
c
0
= 6.88
5
Å, whereas carbonate apatite (2.29 CO
2
) gave
a
0
= 9.43
6
Å and
c
0
= 6.88
5
Å. A deficiency of both calcium and phosphorus in the carbonate apatite suggests a coupled substitution of hydronium and carbonate ions in the structure.
Adrenal Response to Fighting in Mice: Separation of Physical and Psychological Causes
Authors: Bronson F. H. , Eleftheriou B. E.
Published: October 2006

The concentration of unbound corticosterone in mice exposed to the presence of a trained fighter is much greater if the mice have previously experienced physical defeat than if they have not. There is little difference in the concentration of the hormone between mice placed in the presence of a fighter, given a background of physical defeat, and mice actually attacked and defeated. Two possible categories of stimuli which could be responsible for hyperactivity of the adrenal cortex following defeat by another mouse are psychological and physical (for example, bite wounds); the former is apparently by far the more important under the conditions of these experiments.
Nuclear Magnetic Resonance Studies of Living Muscle
Authors: Bratton Clyde B. , Hopkins A. L. , Weinberg Joseph W.
Published: October 2006

Measurements of nuclear magnetic relaxation times for protons of water in living skeletal frog muscle show the transverse relaxation time,
T
2
, increases when a muscle contracts isometrically. This result and other experimental data suggest that a fraction of the intracellular water molecules have restricted rotational freedom and that this fraction decreases when contraction occurs.
Protein Synthesis Inhibition: Mechanism for the Production of Impaired Fat Absorption
Authors: Sabesin Seymour M. , Isselbacher Kurt J.
Published: October 2006

Treatment of rats with puromycin and acetoxycycloheximide results in a defect in intestinal lipid transport. Under these conditions rats given corn oil accumulate triglyceride within the intestinal cells and fail to develop the normal postprandial hyperlipemia. The observed interference in lipid transport appears to be a consequence of impaired chylomicron formation.
Dicyandiamide: Possible Role in Peptide Synthesis during Chemical Evolution
Authors: Steinman Gary , Lemmon Richard M. , Calvin Melvin
Published: October 2006

Dicyandiamide promotes certain dehydration condensations under conditions possible on primitive Earth. The effect of this compound in promoting peptide syntheses was studied.
Ciguatera Fish Poison: A Cholinesterase Inhibitor
Authors: Li Kwan-Ming
Published: October 2006

The substance responsible for the poisoning effect of ciguatera poison from fish is an anticholinesterase. In rats, mice, and rabbits ciguatera poison causes death by asphyxiation. Protopam chloride with atropine is an effective antidote.
Isolation and Structure of a Brain Constituent That Binds to the Cannabinoid Receptor
Authors: Devane William A. , Hanuš Lumir , Breuer Aviva , Pertwee Roger G. , Stevenson Lesley A. , Griffin Graeme , Gibson Dan , Mandelbaum Asher , Etinger Alexander , Mechoulam Raphael
Published: October 2006

Arachidonylethanolamide, an arachidonic acid derivative in porcine brain, was identified in a screen for endogenous ligands for the cannabinoid receptor. The structure of this compound, which has been named "anandamide," was determined by mass spectrometry and nuclear magnetic resonance spectroscopy and was confirmed by synthesis. Anandamide inhibited the specific binding of a radiolabeled cannabinoid probe to synaptosomal membranes in a manner typical of competitive ligands and produced a concentration-dependent inhibition of the electrically evoked twitch response to the mouse vas deferens, a characteristic effect of psychotropic cannabinoids. These properties suggest that anandamide may function as a natural ligand for the cannabinoid receptor.
Miocene Mammals and Central American Seaways
Authors: Whitmore Frank C. , Stewart Robert H.
Published: October 2006

The presence of Miocene mammals of North American affinity in the Panama Canal Zone indicates that Central America was attached to North America. That this attachment was a broad and stable land mass is shown by the close relation of the Panama Miocene herbivores to the widely distributed Miocene herbivore fauna of North America. A continuous connection existed probably throughout the Tertiary, to the west and north of the isthmian region, but the tectonically active isthmus probably was broken up into an archipelago during most of Tertiary time. Between the islands ran the Strait of Panama; from time to time parts of the isthmian area were connected to the stable land to the west, allowing eastward migration of land animals. The mammals of North American affinity in the Cucaracha Formation were found only a few kilometers from the western end of the San Blas Area, a stable land mass in eastern Panama that was separated from South America by the Bolivar Trough during most of the interval between Oligocene and Pliocene time. The Strait of Panama was a less stable barrier than the Bolivar Trough; this being so, it is likely that the San Blas Area was inhabited by land animals of North American rather than South American affinity. Thus, the disappearance of the Bolivar seaway in Pliocene time would have allowed, probably for the first time, mingling of the North and South American mammal faunas.
Circulating DNA as a Possible Factor in Oncogenesis
Authors: Bendich Aaron , Wilczok Tadeusz , Borenfreund Ellen
Published: October 2006

Infectious DNA from the tumor-inducing polyoma virus and pneumococcal-transforming DNA can be recovered from the blood of mice in biologically active form after intraperitoneal injection. Polyoma DNA appeared to undergo less inactivation than did transforming DNA. In light of these observations, the metastatic spread of cancer may possibly be favored by circulation of tumorigenic DNA in the blood stream.
Seed Dispersal Velocity in Four Dwarfmistletoes
Authors: Hinds T. E. , Hawksworth F. G.
Published: October 2006

By means of a high-speed photographic technique, the initial velocities of seeds were studied as they were expelled from the fruits of four Colorado dwarfmistletoes:
Arceuthobium douglasii
,
A. campylopodum
f.
cyanocarpum
,
A. vaginatum
f.
cryptopodum
, and
A. americanum
. Velocities of the seeds of the latter two species averaged 2600 centimeters per second and were significantly greater than those of the first two, which averaged 2200 centimeters per second. The initial velocity of 526 seeds of the four dwarfmistletoes averaged 2400 centimeters per second.
Linkage in Control of Allotypic Specificities on Two Different γG-Immunoglobulins
Authors: Lieberman Rose , Dray Sheldon , Potter Michael
Published: October 2006

Allotypic specificities were identified on two different myeloma proteins and the corresponding normal γG-immunoglobulins of BALB/c mice. When the sera of F
2
progeny from a cross between BALB/c mice having the a1 allotype and AL mice having the a4 allotype were tested for these specificities, it was found that the two allotypic specificities of the BALB/c mice were either both present (87 mice) or both absent (36 mice), an indication of linkage in their genetic control.
Annelid Ciliary Photoreceptors
Authors: Lawrence Peter A. , Krasne Franklin B.
Published: October 2006

The photoreceptor cells of the tube-dwelling polychaete
Branchiomma vesiculosum
contain stacked disc-shaped membranous sacs which are the expanded and flattened outer membranes of cilia.
Atmospheric Noble Gases: Solar-Wind Bombardment of Extraterrestrial Dust as a Possible Source Mechanism
Authors: Tilles David
Published: October 2006

A source mechanism for the noble gases in the earth's atmosphere may be the solar-wind bombardment of extraterrestrial dust. Calculations based on estimates of recent influx of dust to the earth, quiet solar-wind intensity, argon abundance in the solar wind, and assumed Poynting-Robertson lifetimes of small particles in space agree within a factor of 5 with the present amounts of argon-36 and argon-38 in the atmosphere.
Mosquito Transmission of a Reticulum Cell Sarcoma of Hamsters
Authors: Banfield William G. , Woke Paul A. , MacKay Carol M. , Cooper Herbert L.
Published: October 2006

A transplantable reticulum cell sarcoma with leukemic manifestations can be transmitted from one hamster to another by means of a mosquito,
Aëdes aegypti
(L.). The transmission seems to be by a transfer of tumor cells, and not by passage of some other oncogenic agent.
Smooth Muscle: An Ultrastructural Basis for the Dynamics of Its Contraction
Authors: Rosenbluth Jack
Published: October 2006

Electron micrographs of vertebrate and invertebrate smooth muscle indicate that the myofilaments are oriented obliquely to the long axis of the muscle fibers containing them and insert along the sides of the fibers. As a result, a greater proportion of the contractile elements are in parallel with one another and a smaller proportion are in series than would be possible if the myofilaments were strictly parallel to the fiber axis. From this ultrastructural organization it is possible to predict several well-known, but previously unexplained, physiological properties of smooth muscle.
Control of Enzyme Activity in Growing Bacterial Cells by Concerted Feedback Inhibition
Authors: Burlant Louise , Datta Prasanta , Gest Howard
Published: October 2006

Amino acids of the aspartic acid family are synthesized in bacteria through a multistep branched pathway. In the photosynthetic bacterium
Rhodopseudomonas capsulatus
, the enzyme that catalyzes the first step is specifically inhibited by a combination of two end-product amino acids. Evidence is presented for operation of this kind of "concerted" feedback control as a regulatory device in growing cells.
Particles Resembling Papova Viruses in Human Cerebral Demyelinating Disease
Authors: Zu Rhein Gabriele M. , Chou Shi-Ming
Published: October 2006

Degenerated brain tissue obtained from a deceased patient who had progressive multifocal leukoencephalopathy had been fixed in formalin prior to processing for electron microscopy. In ultrathin sections virus-like particles resembling papova virions were frequently observed in glial nuclei. Correlation with light-microscopy findings suggests that demyelination resulted from the cytocidal effect of the virus on oligodendroglia.
Visual Perception of Direction for Stimuli Flashed During Voluntary Saccadic Eye Movements
Authors: Matin Leonard , Pearce Douglas G.
Published: October 2006

In two different experiments, subjects reported on the visual direction of a flash presented during a voluntary saccade relative to the visual direction of a stimulus viewed prior to the saccade. Under the conditions of the first experiment the report given by the subject was primarily determined by the relative retinal positions of the two stimuli. In the second experiment evidence was obtained for precisely timed shifts in local signs which are due to proprioceptive compensation for changes in ocular position during the saccade.
Transepidermal Potential Difference: Development in Anuran Larvae
Authors: Taylor R. E. , Barker S. B.
Published: October 2006

Skin from bullfrog tadpoles does not show the potential difference characteristic of adult frog skin until several days after the emergence of the forelimbs, presumably because the mechanism for active sodium transport is absent or nonfunctional. Exposure to low concentrations of thyroxine accelerates appearance of the transepidermal potential difference at rates which are related to the dosage. This system may provide a new basis for evaluating the importance of specific biochemical mechanisms in active sodium transport.
Repellency of Skin-Surface Lipids of Humans to Mosquitoes
Authors: Skinner W. A. , Tong H. , Maibach H. , Khan A. A. , Pearson T.
Published: October 2006

Skin lipids obtained from the washings, in acetone or diethyl ether, of the foreheads or arms of humans are very repellent to female
Aedes aegypti
when evaluated in a dual-port olfactometer. By means of thin-layer chromatography, the repellent substances can be separated from nonrepellent material also present in skin lipids.
Pigmented Nevi and Malignant Melanomas as Studied with a Specific Fluorescence Method
Authors: Falck B. , Jacobsson S. , Olivecrona H. , Rorsman H.
Published: October 2006

A specific fluorescence is developed in melanocytes, nevus cells, and cells of malignant melanoma by treatment of the tissue with dry formaldehyde gas. The fluorescence is often stronger in melanocytes adjacent to nevi or melanomas than in normal melanocytes. The strongest fluorescence occurs in cells of malignant melanoma. Among the limited number of compounds that condense with formaldehyde to fluorescent derivatives, DOPA [β-(3,4-dihydroxyphenyl)L-alanine] seems the most likely substance to give rise to the fluorescence observed in these lesions.
Triploidy in Parthenogenetic Species of the Teiid Lizard, Genus
Cnemidophorus
Authors: Pennock Lewis A.
Published: October 2006

Mitotic figures from the bone marrow of three parthenogenetic species of
Cnemidophorus
(whiptail lizards) exhibit chromosome numbers in the triploid range. The species are
C. velox
with 68 chromosomes,
C. tesselatus
with 69, and
C. exsanguis
with 70. A fourth parthenogenetic species,
C. perplexus
, has 46 chromosomes, the same number as the bisexual subspecies
C. tigris septentrionalis
.
Circadian Rhythm in Pineal Serotonin: Effect of Monoamine Oxidase Inhibition and Reserpine
Authors: Snyder Solomon H. , Axelrod Julius
Published: October 2006

The pineal gland of the rat shows a circadian rhythm in its serotonin content, the amount of serotonin decreasing at night. This decrease can be prevented by inhibiting the action of monoamine oxidase. Reserpine abolishes the circadian rhythm in pineal serotonin in the same manner as does interruption of the sympathetic nervous connections of the central nervous system and the pineal gland. These observations suggest that circadian changes in release and binding of serotonin may occur in the pineal gland, and that a central mechanism in which monoamines participate may control the circadian pineal-serotonin rhythm.
Brucite in the Calcareous Alga
Goniolithon
Authors: Weber Jon N. , Kaufman John W.
Published: October 2006

Brucite, Mg(OH)
2
, identified by differential thermal analysis, has been found in the high-magnesian calcite skeleton of
Goniolithon
, a marine calcareous alga. This mineral amounts to about 5 percent of the skeleton by weight, and can account for the discrepancy between total amount of magnesium determined by chemical analysis and the magnesium in metastable solid solution in calcite as determined by the size of the unit cell of calcite.
Liquid Waves by Computer
Authors: Harlow Francis H. , Shannon John P. , Welch J. Eddie
Published: October 2006

A numerical, fluid-dynamics technique for high-speed computers is described and illustrated. It applies to the solution of problems dealing with incompressible viscous fluids and involving nonsteady motions in several dimensions in space. The ability to handle free-surface boundary conditions allows waves to be studied through all phases of breaking and splashing, as well as a number of related phenomena.
Adrenaline and Noradrenaline: Relation to Performance in a Visual Vigilance Task
Authors: O'Hanlon J. F.
Published: October 2006

Concentrations of adrenaline and noradrenaline in the circulating blood were measured in blood samples taken from subjects as they performed a visual vigilance task or viewed movies, both under identical conditions. For those subjects whose vigilance performance deteriorated it was concluded that the concentration of circulating adrenaline decreases as a function of time in a vigilance task but not under "relaxed" conditions, such as watching motion pictures.
Sperm Capacitation by Uterine Fluid or Beta-Amylase in vitro
Authors: Kirton Kenneth T. , Hafs Harold D.
Published: October 2006

Rabbit sperm developed the capacity to fertilize ova when incubated in utero or in vitro in fluids from estrous uteri. Incubation of sperm with beta-amylase in phosphate-buffered Locke's solution also resulted in capacitation. The data suggest that sperm capacitation involves enzymatic alteration of carbohydrate-containing seminal macromolecules which coat sperm and inhibit fertilization.
The Earliest Primates
Authors: Van Valen Leigh , Sloan Robert E.
Published: October 2006

The known range of the Primates is extended down from the middle Paleocene to the early Paleocene and late Cretaceous by a new genus and two new species from Montana,
Purgatorius unio
and
P. ceratops
. These species approach condylarths and leptictid and erinaceoid insectivores in structure.
Purgatorius
is referred to a new subfamily, Purgatoriinae, of the Paromomyidae, but is probably not the stem primate. The fauna of Purgatory Hill indicates a late early Paleocene age.
Bacterial Contamination of Some Carbonaceous Meteorites
Authors: Oró J. , Tornabene T.
Published: October 2006

Three types of bacteria were isolated from samples of two carbonaceous chondrites and identified as common contaminants that are widely distributed.
Growth Hormone: Important Role in Muscular Exercise in Adults
Authors: Hunter W. M. , Fonseka C. C. , Passmore R.
Published: October 2006

Measurement by radio-immunoassay of growth hormone in the plasma of adults showed consistently low concentrations in subjects in bed in the morning. Exercise caused marked increases except when the subjects ingested carbohydrate during the exercise.
Lysosomal and Free Acid Phosphatase in Salivary Glands of
Chironomus tentans
Authors: Schin Ki Ssu , Clever Ulrich
Published: October 2006

In cells of salivary glands of last-instar larvae of
Chironomus tentans
, acid phosphatase activity is bound to (probable) lysosomes and a few other cell organelles. At the end of the pupal molt the salivary gland breaks down. While acid phosphatase in areas of nondegenerated cells is still restricted to the structures mentioned, in degenerated areas the enzyme is freely distributed in the cytoplasm.
Sleep: Changes in Threshold to Electroconvulsive Shock in Rats after Deprivation of "Paradoxical" Phase
Authors: Cohen Harry B. , Dement William C.
Published: October 2006

Rats were deprived of paradoxical (rapid eye movement or REM) sleep for a 6-day period but were allowed substantial non-REM (slow wave) sleep. Thresholds for electroconvulsive shock dropped significantly after deprivation in all these animals, but thresholds in control animals treated in a similar manner, but allowed REM sleep exhibited no change. Deprivation seems to heighten neural excitability.
Avifauna: Turnover on Islands
Authors: Mayr Ernst
Published: October 2006

The percentage of endemic species of birds on islands increases with island area at a double logarithmic rate. This relation is apparently due to extinction, which is more rapid the smaller the island. The turnover resulting from extinction and replacement appears to be far more rapid than hitherto suspected.
Defensive Secretion of a Caterpillar (
Papilio
)
Authors: Eisner Thomas , Meinwald Yvonne C.
Published: October 2006

The eversible cervical gland (osmeterium) of the caterpillar of the swallowtail butterfly,
Papilio machaon
, produces a secretion containing isobutyric and 2-methylbutyric acid. The gland is effective in defense against ants. Even when caterpillars were fed on one of three unbelliferous plants (fennel, carrot, parsnip) the secretion contained the same two acids.
Sex-Linkage of Erythrocyte Glucose-6-Phosphate Dehydrogenase in Two Species of Wild Hares
Authors: Ohno Susumu , Poole Jackie , Gustavsson Ingemar
Published: October 2006

Glucose-6-phosphate dehydrogenase specific to the erythrocytes of each of two wild hares found in Europe was discerned by starch-gel electrophoresis at p
H
7.0 and p
H
8.6. The single, sharp band of the dehydrogenase of
Lepus europaeus
was faster than that of
L. timidus
, at both p
H
levels. The sex-linkage of this enzyme was tested through reciprocal hybrids between the two species. Each male hybrid had a single band of enzyme identical with that of its mother, while both parental types of this enzyme coexisted in female hybrids. Thus, sex-linkage of glucose-6-phosphate dehydrogenase has been suggested not only in man and in the family Equidae, but now in the family Leporidae of placental mammals as well.
Lead Isotopes and the Age of the Earth
Authors: Tilton G. R. , Steiger R. H.
Published: October 2006

Calculations based on comparison of the isotopic composition of lead from iron meteorites with that of various modern terrestrial leads have placed the age of the earth at around 4550 million years. However, recent data from young volcanic rocks reveal that modern terrestrial lead can have a wide range in isotopic composition. The variations in its composition mean that one or more of the assumptions used in the age calculation have been violated. We modified the usual approach by comparing meteorite lead with lead from rocks 2700 million years old, from the Canadian Shield. Using this method and the same constants and assumptions utilized in the earlier calculations we calculated an age of 4750 ± 50 million years for the earth. The earth may be approximately 200 million years older than previously thought; alternatively, primordial terrestrial lead may not have had the same isotopic composition as lead in iron meteorites does.
Flora and Fauna on Backs of Large Papuan Moss-Forest Weevils
Authors: Gressitt J. L. , Sedlacek J. , Szent-Ivany J. J. H.
Published: October 2006

Large, living, flightless weevils feeding on leaves of woody plants in high moss forest on various New Guinea mountain ranges have plant growth on their backs. Fungi and algae have been found on 11 species of Gymnopholus, lichens on six species, and liverworts on one species. In other genera of weevils, on the same mountains, there are additional specific associations with fungi, algae, lichens, and liverworts. The fungi and lichens, at least, are inhabited by oribatid mites of a new family, which may spread the plants from beetle to beetle. Also, nematodes, rotifers, psocids, and diatoms occur among the plants. Specialized scales or hairs, and a secretion, in depressions on the weevils' backs, appear to be associated with encouragement of the plant growth. Mutualistic symbiotic relationships seem to be clearly indicated.
Gravitational Lens Effect: An Observational Test
Authors: Feibelman Walter A.
Published: October 2006

The large proper motion of the nearby star 40 Eridani-A will pass a distant star in 1988. It should be possible to observe the gravitational lens effect of this eclipse by existing photoelectric methods.
Uncoupling of an Epithelial Cell Membrane Junction by Calcium-Ion Removal
Authors: Nakas M. , Higashino S. , Loewenstein W. R.
Published: October 2006

Calcium takes part in maintaining ion communication between salivary gland cells (
Chironomus thummi
). Its withdrawal from the cell systems results in virtual disconnection of ion communication, at Ca
++
concentrations which do not noticeably affect cell adhesion. The junctional membrane surfaces, which are normally quite freely permeable to ions, become as impermeable as the nonjunctional membrane surfaces; each cell seals itself off irreversibly as a unit. In maintaining ion communication Mg
++
substitutes for Ca
++
.
Spectral Sensitivity of the Scallop
Pecten maximus
Authors: Cronly-Dillon J. R.
Published: October 2006

The spectral sensitivity of the scallop
Pecten maximus
was determined behaviorally; the shadow reflex was used as the index of sensitivity. The photopic visibility curve displays two prominent peaks, one at approximately 480 mμ, and the other with wavelength maximum at approximately 540 mμ. Reduction of background illumination results in a great increase in sensitivity at 480 mμ relative to the 540-mμ peak. This suggests that the scallop may possess photoreceptors that behave like rods in vertebrates.
Chloroquine: Mode of Action
Authors: Ciak Jennie , Hahn Fred E.
Published: October 2006

The drug chloroquine is bactericidal forBacillus megaterium; it inhibits DNA and RNA biosynthesis and produces rapid degradation of ribosomes and dissimilation of ribosomal RNA. Inhibition of protein synthesis is also observed, evidently as a secondary effect. Inhibition of DNA replication is proposed as a general mechanism of the antimicrobial action of chloroquine.
Endocarditis in Mice Infected with Coxsackie Virus B
4
Authors: Burch G. E. , DePasquale N. P. , Sun S. C. , Mogabgab W. J. , Hale A. R.
Published: October 2006

Endocarditis has not been generally considered to be a complication of viral infection. We show that mural and valvular endocarditis can be produced in mice infected with Coxsackie virus B
4
. Because this virus commonly infects man and is highly cardiotropic, it is important to know whether it produces valvular lesions in man similar to those we describe in mice.
Atlantic Deep-Sea Stratigraphy: Extension of Absolute Chronology to 320,000 Years
Authors: Ku Teh-Lung , Broecker Wallace S.
Published: October 2006

Thorium-230 measurements on a core of globigerina ooze from the Caribbean Sea substantiate the prediction of Ericson
et al.
that the paleontological boundary U-V (Sangamon-Illinoian boundary in their scheme) in the Atlantic sediments has an age of close to 320,000 years. As the ages derived by Ericson
et al.
were based on extrapolations of mean sedimentation rates established by carbon-14 and protactinium-231 dating of the upper sections of this and other cores, this result confirms the assumption that sedimentation rates in the Caribbean Sea have not changed significantly during the past several hundred thousand years. The uranium content of the ocean as indicated by the deposition rate of thorium-230 was no more than 30 percent higher during glacial than during interglacial periods.
Rubidium-Strontium Age of the Bosumtwi Crater Area, Ghana, Compared with the Age of the Ivory Coast Tektites
Authors: Schnetzler C. C. , Pinson W. H. , Hurley P. M.
Published: October 2006

Rocks from the vicinity of Bosumtwi crater, Ghana, and a representative collection of Ivory Coast tektites have been analyzed mass spectrometrically for rubidium, strontium, and strontium isotopic composition. The data from the rocks of the crater area yield an age of 1.97 × 10
9
years (λ
Rb
= 1.47 × 10
-11
year
-1
). The data for the Ivory Coast tektites fall on this isochron. This identity of age values for the Ivory Coast tektites and the Birrimian basement rocks of West Africa strongly supports the hypothesis of terrestrial formation for these tektites. The evidence available at present suggests that the Ivory Coast tektites are most probably the fusion products of meteoritic impact at the Bosumtwi crater site.
Rotifer Ecology and Embryological Induction
Authors: Gilbert John J.
Published: October 2006

The rotifer
Asplanchna
releases into its environment a water-soluble, nondialyzable, pronase-sensitive factor which causes uncleaved eggs of another rotifer,
Brachionus calyciflorus
, to develop into individuals with a pair of long, movable spines which neither their mothers nor the unaffected controls have. These appendages protect the
Brachionus
from
Asplanchna
predation.
Dreaming Sleep in Man: Changes in Urine Volume and Osmolality
Authors: Mandell A. J. , Chaffey B. , Brill P. , Mandell M. P. , Rodnick J. , Rubin R. T. , Sheff R.
Published: October 2006

Epochs of dreaming sleep, as measured by rapid eye movements, consistently correlated with biphasic change in urine volume and osmolality in catheterized human subjects. Marked decrease in volume and increase in osmolality were followed by a hypotonic diuresis.
Parturient Mice: Effect of Environment on Labor
Authors: Newton Niles , Foshee Donald , Newton Michael
Published: October 2006

More first-born pups and greater numbers of pups were born in a familiar cage having a covered nesting box than in a glass bowl, when pregnant mice at term were alternated between contrasting environments. Current theories emphasize the influence on labor of mechanical and hormonal factors; these data suggest that environmental factors also may play a role.
Inhibition of Long-Term Potentiation by NMDA-Mediated Nitric Oxide Release
Authors: Izumi Yukitoshi , Clifford David B. , Zorumski Charles F.
Published: October 2006

Activation of
N
-methyl-D-aspartate (NMDA) receptors before tetanic stimulation blocks long-term potentiation (LTP) in the CA1 region of the hippocampus. This NMDA-mediated inhibition of LTP can be reversed by the nitric oxide (NO) inhibitors L-
N
G
-monomethyl-arginine or hemoglobin and mimicked by sodium nitroprusside. These results indicate that the timing of NO release relative to high-frequency activation of CA1 synapses may be an important determinant of LTP generation and suggest that NO may play a positive or negative modulatory role in LTP depending on prior events at the tetanized synapse and the ambient concentration of excitatory amino acids.
Dehydration and Rehydration in a Prebiological System
Authors: Smith Adolph E. , Bellware Frederick T.
Published: October 2006

A proteinoid microsphere suspension system was subjected to cyclic dehydration and rehydration. Particles having somewhat coacervate properties were observed, suggesting a relation between the coacervate and proteinoid origin of cells.
Cilia in Nematode Sensory Organs
Authors: Roggen D. R. , Raski D. J. , Jones N. O.
Published: October 2006

Electron microscopic studies revealed the presence of true cilia in nerve processes connected with sensory organs of a nematode. These structures are important in evaluating the relation between nematodes and the other aschelminths, from which they were separated partially on the basis of the supposed total absence of cilia.
Neurosecretory Cells: Daily Rhythmicity in
Leiobunum longipes
Authors: Fowler Dona J. , Goodnight Clarence J.
Published: October 2006

A fluorometric-analysis procedure, used to quantitate indoles, confirmed the presence of 5-hydroxytryptamine (5-HT) in an arachnid; there was unimodal cyclic production of 5-HT in brain and intestinal tissues over a 24-hour period. The same tissues produced 5-HT after 80-day culture; bimodal cyclic output was indicated during continuous 24-hour study. One peak occurred at 0200 hours, at the same time as the peak in vivo, suggesting an endogenously controlled mechanism of secretion. The second peak occurred at midmorning, a time when production in vivo was lowest, suggesting that there is a possible feedback-control mechanism in the organism that inhibits the endogenous output of 5-HT.
Potassium-Argon Geochronology of Deep-Sea Sediments
Authors: Dymond Jack R.
Published: October 2006

A potassium-argon dating method applicable to small quantities of volcanic minerals and glass has been developed and used to determine the ages of North Pacific sediments. Tertiary sedimentation rates range from less than 1.0 millimeter per 10
3
years for deep-sea "red clay" to 1 centimeter per 10
3
years for calcareous-siliceous ooze nearer the continent. The potassium-argon ages obtained from different minerals are concordant, and in samples with associated fossils, these ages are compatible with the paleontologic evidence.
Actinomycete: Isolation and Identification of Agent Responsible for Musty Odors
Authors: Dougherty John D. , Campbell Richard D. , Morris Robert L.
Published: October 2006

A compound produced by certain actinomycete cultures is responsible for a persistent musty odor. It has been isolated in high purity and identified by chemical and spectroscopic properties. Possible structures are discussed.
Tree Shrews: Unique Reproductive Mechanism of Systematic Importance
Authors: Martin R. D.
Published: October 2006

Tupaia offspring are maintained in a separate nest constructed by the male parent and are suckled by the female only once every 48 hours. The young are nevertheless able to maintain a constant external body temperature of 37°C.
Control of Sensory Fields by Stimulation of Hypothalamus
Authors: MacDonnell Malcolm F. , Flynn John P.
Published: October 2006

Stimulation of the cat's hypothalamus, which elicits attack, also establishes sensory fields for two reflexes related to biting. Touching a perioral region leads to head movement, bringing the stimulus to the mouth. Touching the lip-line leads to jaw opening. The size of the fields depends on the intensity of stimulation.
Carnivorous Plants: Phylogeny and Structural Evolution
Authors: Albert Victor A. , Williams Stephen E. , Chase Mark W.
Published: October 2006

The carnivorous habit in flowering plants represents a grade of structural organization. Different morphological features associated with the attraction, trapping, and digestion of prey characterize a diversity of specialized forms, including the familiar pitcher and flypaper traps. Phylogenetic analysis of nucleotide sequence data from the plastid
rbc
L gene indicates that both carnivory and stereotyped trap forms have arisen independently in different lineages of angiosperms. Furthermore, these results demonstrate that flypaper traps share close common ancestry with all other trap forms. Recognition of these patterns of diversification may provide ideal, naturally occurring systems for studies of developmental processes underlying macromorphological evolution in angiosperms.
Trypsin-Sensitive, Rapid Inactivation of a Calcium-Activated Potassium Channel
Authors: Solaro Christopher R. , Lingle Christopher J .
Published: October 2006

Most calcium-activated potassium channels couple changes in intracellular calcium to membrane excitability by conducting a current with a probability that depends directly on submembrane calcium concentration. In rat adrenal chromaffin cells, however, a large conductance, voltage- and calcium-activated potassium channel (BK) undergoes rapid inactivation, suggesting that this channel has a physiological role different than that of other BK channels. The inactivation of the BK channel, like that of the voltage-gated Shaker B potassium channel, is removed by trypsin digestion and channels are blocked by the Shaker B amino-terminal inactivating domain. Thus, this BK channel shares functional and possibly structural homologies with other inactivating voltage-gated potassium channels.
Cohenite in Meteorites: A Proposed Origin
Authors: Brett Robin
Published: October 2006

Cohenite [(Fe, Ni)
3
C] is found almost exclusively in meteorites containing from 6 to 8 percent nickel (by weight). On the basis of iron-nickel-carbon phase diagrams at 1 atmosphere and of kinetic data, the occurrence of cohenite within this narrow composition range as a low-pressure metastable phase and the nonoccurrence of cohenite in meteorites outside the range 6 to 8 percent nickel can be explained. Cohenite formed in meteorites containing less than 6 to 8 percent nickel decomposed to metal and graphite during cooling; it cannot form in meteorites containing more than about 8 percent. The presence of cohenite in meteorites cannot be used as an indicator of pressure of formation. However, the absence of cohenite in meteorites containing the assemblage, metal plus graphite, requires low pressures during cooling.
Qualitative versus Directional Cues in Two Forms of Differentiation
Authors: Dobrzecka Czeslawa , Szwejkowska Genowefa , Konorski Jerzy
Published: October 2006

Dogs given opportunities to base their instrumental conditioned responses in differentiation learning on either the quality of the auditory conditioned stimulus (for example, metronome versus buzzer) or the direction of its source (in front or behind) choose different cues in different tasks. In S
1
→ R
1
, S
2
→ R
2
(left leg-right leg) differentiation they exclusively use directional cues and are almost unable to learn this task when only quality cues are available. When confronted with Pavlovian S + → R, S — → no R (go-no go) differentiation, however, they generally learn on the basis of quality cues, although some animals also attend to the directional cues. Thus an animal's success or failure in a given differentiation procedure depends not only on its ability to discriminate the stimuli but also on the task with which it is confronted.