bluuebunny/crossref_metadata_2025 huggingface dataset:
Lambda Int Protein Bridges Between Higher Order Complexes at Two Distant Chromosomal Loci
att
L and
att
R
Authors: Kim Sunghoon , Landy Arthur
Published: October 2006

The excisive recombination reaction of bacteriophage lambda involves a specific and efficient juxtaposition of two distant higher order protein-DNA complexes on the chromosome of
Escherichia coli
. These complexes, which mediate synapsis and strand exchange, consist of two DNA sequences,
att
L and
att
R, the bivalent DNA binding protein Int, and the sequence-specific DNA bending proteins, IHF, Xis, and Fis. The protein-protein and protein-DNA interactions within, and between, these complexes were studied by various biochemical techniques and the patterns of synergism among pairs of mutants with marginally impaired recombination function were analyzed. The DNA bending proteins facilitated long-range tethering of high- and low-affinity DNA sites by the bivalent Int protein, and a specific map is proposed for the resulting Int bridges. These structural motifs provide a basis for postulating the mechanisms of site-specific recombination and may also be relevant to other pathways in which two distant chromosomal sites become associated.
Disinhibition of Visually Masked Stimuli
Authors: Robinson Daniel N.
Published: October 2006

Backward-masking conditions were established for a pair of circular-patch stimuli. A third stimulus was then selected so as to mask the second when the second and the third were presented in the absence of the first. When all three stimuli were presented in serial order, the first and third were reliably detected but the second was not. Apparently, by masking the second flash, the third "disinhibited" the first.
Death in Embryonic Systems
Authors: Saunders John W.
Published: October 2006

The principal conclusion to be drawn from the foregoing discussion is that the death of cells and the destruction of tissues, organs, and organ systems are programmed as normal morphogenetic events in the development of multicellular organisms. Death in embryonic systems may thus be explored within the same conceptual framework as growth and differentiation.

The present exploration has revealed that death during embryogenesis serves utilitarian goals in some instances, at least, that its occurrence is subject to control by factors of the immediate cellular and humoral environment, and that aberrations in its normal pattern of expression provide the mechanism for realization of many mutant phenotypes. Hopefully, it has also pointed toward the appropriate formulation of some of the problems that confront us in understanding the control of death at the level of genetic transcription, the biochemical events which determine and accompany its occurrence, and the pathways of disposition and the developmental significance of disassembled cellular building blocks.
Deep Layer of Sediments in Alpine Lake in the Tropical Mid-Pacific
Authors: Woodcock Alfred H. , Rubin Meyer , Duce R. A.
Published: October 2006

Sediments from a unique high-altitude lake on Hawaii indicate ash falls and other airborne and waterborne materials for a period estimated to extend into the Pleistocene.
Auditory System of Noctuid Moths
Authors: Roeder Kenneth D.
Published: October 2006

Insect-eating bats find their aerial food by sonar, through emitting ultrasonic chirps and locating sources of echoes. Certain moths have ears sensitive to these chirps and can detect bats well beyond the range of the bats' sonar. On hearing a distant bat, many moths turn and fly directly away from the source of ultrasound. Only one sense cell in each ear of a moth provides the primary nervous information for this response. This article describes my initial attempts to find out how a moth's central nervous system processes the train of chirps reaching its two ears.

The ear of a restrained moth is exposed to a sequence of artificially generated ultrasonic pulses that approximates the cries made by a bat. This stimulus can be varied with respect to ultrasonic frequency (pitch), pulse intensity, pulse duration, the interval between pulses, and pulse-train duration.

The more sensitive acoustic sense cell responds to all frequencies between about 15,000 and 80,000 cycles per second, but the signal that it transmits to the moth's central nervous system contains no measure of frequency within this range. However, this nerve signal reports variations in the other parameters of the stimulus. The acoustic fiber connects, in the central nervous system, with various nerve cells that transform the signal farther. The signal from a pulse-marker neuron contains no measures of pulse intensity or pulse duration, reporting only changes in interpulse interval and pulse-train duration. A train-marker neuron reports only the duration of the pulse train. The stimulus parameters may be likened to keys, each of which is necessary to gain admittance through a given door but becomes superfluous once this door has been passed. This analogy suggests one of the ways in which a signal is transformed in its passage through the nervous system, and how its specificity is assured in eliciting a given response.

In addition to undergoing this kind of transformation, neural signals generated in the two directionally sensitive ears must be combined if a flying moth is to steer a course away from a distant bat. Neurons have been discovered in the central ganglia which summate signals from the right and left ears. Other neurons are inhibited in their activity by stimulation of one ear. The moth may combine signals from these neurons with motor-nerve information on the attitude of its own wings, which act as oscillating baffles modifying its directional acoustic sensitivity 20 to 40 times a second as it flaps an erratic path through the darkness.
Electrode for Sensing Fluoride Ion Activity in Solution
Authors: Frant Martin S. , Ross James W.
Published: October 2006

Electrodes constructed from single-crystal sections of rare earth fluorides respond to fluoride ion activity over more than five orders of magnitude and show a high selectivity for fluoride over other common anions. These electrodes can be used for either direct measurement of fluoride ion activity or detection of the end point in titration.
Cytochemistry of Synapses: Selective Staining for Electron Microscopy
Authors: Bloom Floyd E. , Aghajanian George K.
Published: October 2006

Material at synapses and in some synaptic vesicles becomes selectively stained when glutaraldehyde-fixed rat brain that has not been treated with osmium is stained with phosphotungstic acid. The material stained at synapses is distinct from the adjacent unstained synaptic membranes and has cytochemical properties of protein. The specialized spatial arrangement exhibited by this synaptic material suggests its close involvement in synaptic function.
Lower Cretaceous Rocks (Neocomian-Albian) Dredged from Blake Escarpment
Authors: Heezen Bruce C. , Sheridan Robert E.
Published: October 2006

Algal calcarenites, Neocomian to Aptian in age, dredged from 3000 to 5000-meter depth on Blake Escarpment, are the oldest rocks yet obtained from deep-sea outcrops. Five thousand meters of post-Aptian subsidence of the Blake Plateau is thus established. Aptian-Albian calcilutites obtained from depths of less than 3000 meters mark the establishment of an offshore environment.
Oncostatin M as a Potent Mitogen for AIDS-Kaposi's Sarcoma-Derived Cells
Authors: Miles Steven A. , Martínez-Maza Otoníel , Rezai Ahmad , Magpantay Larry , Kishimoto Taditnitsu , Nakamura Shuji , Radka Susan F. , Linsley Peter S.
Published: October 2006

Oncostatin M, a cytokine produced by activated lymphoid cells, regulates the growth and differentiation of a number of tumor and normal cells. In contrast to its effects on normal endothelial and aortic smooth muscle cell cultures, Oncostatin M was a potent mitogen for cells derived from acquired immunodeficiency syndrome-related Kaposi's sarcoma (AIDS-KS). After exposure to Oncostatin M, AIDS-KS cells assumed a spindle morphology, had an increased ability to proliferate in soft agar, and secreted increased amounts of interleukin-6. Oncostatin M RNA and immunoreactive Oncostatin M protein were found in AIDS-KS-derived cell isolates. These results suggest that Oncostatin M may play a role in the pathogenesis of AIDS-KS.
A Freeze-Frame View of Eukaryotic Transcription During Elongation and Capping of Nascent mRNA
Authors: Hagler Jeremiah , Shuman Stewart
Published: October 2006

Ribonuclease footprinting of nascent messenger RNA within ternary complexes of vaccinia RNA polymerase revealed an RNA binding site that encompasses an 18-nucleotide RNA segment. The dimensions of the binding site did not change as the polymerase moved along the template. Capping of the 5′ end of the RNA was cotranscriptional and was confined to nascent chains 31 nucleotides or greater in length. Purified capping enzyme formed a binary complex with RNA polymerase in solution in the absence of nucleic acid. These findings suggest a mechanism for cotranscriptional establishment of messenger RNA identity in eukaryotes.
Overlapping Nucleotide Determinants for Specific Aminoacylation of RNA Microhelices
Authors: Francklyn Christopher , Shi Jian-Ping , Schimmel Paul
Published: October 2006

A seven-base pair microhelix that recapitulates a glycine transfer RNA (tRNA) acceptor helix can be specifically aminoacylated with glycine. A single base pair and the single-stranded discriminator base near the attachment site are essential for aminoacylation. These nucleotide sequence elements, and those in microhelices that can be charged with histidine and alanine, occur in the same positions and therefore overlap. Studies on a systematic set of sequence variants showed that no microhelix could be charged with more than one amino acid. Also, none of the three cognate aminoacyl-tRNA synthetases (aaRSs) gave a detectable amount of aminoacylation of the CCA trinucleotide that is common to the 3′ ends of all tRNAs, showing that the specific acceptor stem nucleotide bases confer aminoacylation. An analysis of the relative contributions of these microhelices to overall tRNA recognition indicates that their interaction with aaRSs constitutes a substantial part of the recognition of the whole tRNAs.
Human Growth Hormone and Extracellular Domain of Its Receptor: Crystal Structure of the Complex
Authors: de Vos Abraham M. , Ultsch Mark , Kossiakoff Anthony A.
Published: October 2006

Binding of human growth hormone (hGH) to its receptor is required for regulation of normal human growth and development. Examination of the 2.8 angstrom crystal structure of the complex between the hormone and the extracellular domain of its receptor (hGHbp) showed that the complex consists of one molecule of growth hormone per two molecules of receptor. The hormone is a four-helix bundle with an unusual topology. The binding protein contains two distinct domains, similar in some respects to immunoglobulin domains. The relative orientation of these domains differs from that found between constant and variable domains in immunoglobulin Fab fragments. Both hGHbp domains contribute residues that participate in hGH binding. In the complex both receptors donate essentially the same residues to interact with the hormone, even though the two binding sites on hGH have no structural similarity. Generally, the hormone-receptor interfaces match those identified by previous mutational analyses. In addition to the hormone-receptor interfaces, there is also a substantial contact surface between the carboxyl-terminal domains of the receptors. The relative extents of the contact areas support a sequential mechanism for dimerization that may be crucial for signal transduction.
Actin-Binding Protein Requirement for Cortical Stability and Efficient Locomotion
Authors: Cunningham C. Casey , Gorlin Jed B. , Kwiatkowski David J. , Hartwig John H. , Janmey Paul A. , Byers H. Randolph , Stossel Thomas P.
Published: October 2006

Three unrelated tumor cell lines derived from human malignant melanomas lack actin-binding protein (ABP), which cross-links actin filaments in vitro and connects these filaments to plasma membrane glycoproteins. The ABP-deficient cells have impaired locomotion and display circumferential blebbing of the plasma membrane. Expression of ABP in one of the lines after transfection restored translocational motility and reduced membrane blebbing. These findings establish that ABP functions to stabilize cortical actin in vivo and is required for efficient cell locomotion.
Composition Measurements of the Topside Ionosphere
Authors: Hoffman John H.
Published: October 2006

Data from a magnetic mass spectrometer flown on the Explorer 31 satellite show that the ionosphere above 1000 kilometers usually consists of hydrogen ions as the predominant species. Between this altitude and perigee (500 kilometers) the dominant ion species shifts to atomic oxygen, with a significant amount of atomic nitrogen ions also present. Helium ions are present in small quantities at all altitudes. Other minor ions observed are those of 2, 7, 8, 15, 18, and 20 atomic mass units.
Mammalian Ribosomal Protein: Analysis by Electrophoresis on Polyacrylamide Gel
Authors: Low Robert B. , Wool Ira G.
Published: October 2006

Ribosomal protein from five mammalian tissues when analyzed by discontinuous electrophoresis on polyacrylamide gel at
p
H 4.5 yielded 24 bands. Densitometric tracings indicated that the patterns of the basic ribosomal proteins from the several tissues were qualitatively similar. Protein from
Escherichia coli
ribosomes analyzed at
p
H 4.5 gave 29 bands, and the pattern was different from that of mammalian ribosomal protein. No distinct band was found when mammalian ribosomal protein was analyzed at
p
H 8.3 (acidic proteins). Ribosomal protein from
Escherichia coli
gave eight bands at
p
H 8.3. Thus, the structure of the genes responsible for synthesis of ribosomal protein in several mammalian tissues is the same, and different genes direct synthesis of ribosomal protein in bacteria.
Seizure Discharges Evoked in Vitro in Thin Section from Guinea Pig Hippocampus
Authors: Yamamoto Chosaburo , Kawai Nobufumi
Published: October 2006

A thin section prepared from guinea pig hippocampus produced, in chloride-free medium, a train of seizure discharges in response to a single shock applied to the section. Generation of these discharges was ascribed to the lack of inhibitory processes in an absence of chloride ion.
Axonal Delivery of Neuroplasmic Components to Muscle Cells
Authors: Korr I. M. , Wilkinson P. N. , Chornock F. W.
Published: October 2006

Substances labeled with phosphate-32 and carbon-14 and applied to hypoglossal nuclei in rabbits traveled down the hypoglossal nerves and after several days began entering only the muscle cells of the tongue. Prevention of axonal delivery on one side caused unilateral labeling of the tongue. Labeled substances delivered by extracellular fluids labeled all cells indiscriminately. The axonal conveyance of neuroplasmic components to peripheral cells may provide a basis for trophic influences of neurons on other cells.
Training without Reward: Traditional Training of Pig-Tailed Macaques as Coconut Harvesters
Authors: Bertrand Mireille
Published: October 2006

Macaca nemestrina
, the pig-tailed macaque, is the only monkey regularly and extensively used for work. For centuries it has been trained in Southeast Asia to pick coconuts and other fruits. The training is based exclusively on punishment and avoidance of punishment.
Mouse Immunoglobulin Allotypes: Detection with Rabbit Antiserums
Authors: Coe John E.
Published: October 2006

An antiserum with allotypic specificity for mouse γ
2a
-globulins was prepared in a rabbit by injection of 7S γ
2
-globulin of C
57
BL/6 mice. The antibody reacted with an isoantigen in the 7S γ
2
-globulins of normal serum of mouse strains belonging to the lg-1
b
allotype class (C
57
BL/6, C
57
BL/10, and SJL strains). No precipitin reaction was observed with serum from 18 other inbred mice strains representing other lg-1 allotype classes.
Volatile Principle from Oak Leaves: Role in Sex Life of the Polyphemus Moth
Authors: Riddiford Lynn M. , Williams Carroll M.
Published: October 2006

An emanation from oak leaves is necessary for the mating of polyphemus moths under laboratory conditions. This requirement can be satisfied by placing the moths in the presence of oak leaves or aqueous or alcoholic extracts prepared from oak leaves. The active principle is a volatile, heat-stable, polar material which has been partially purified. The oak emanation acts on the female and not on the male, and the sensory receptors are located on the female antennae. The reception of the oak emanation is prerequisite for the female's release of her sex pheromone, which in turn, is necessary for the sexual activation of the male.
Fatty Acids in Eleven Species of Blue-Green Algae: Geochemical Significance
Authors: Parker Patrick L. , Van Baalen Chase , Maurer Larry
Published: October 2006

Analyses of the total lipids of 11 species of blue-green algae showed a simple but qualitatively variable fatty acid composition. The species can be grouped in three categories on the basis of their oleic, linoleic, and linolenic acid content. One species was unusual in that the ten-carbon acid accounts for one-half of its total fatty acid. Branched chain acids are absent in the algae, but are major components of marine bacteria. The geochemical significance of the data is discussed.
Fossil Alpha-Particle Recoil Tracks: A New Method of Age Determination
Authors: Huang W. H. , Walker R. M.
Published: October 2006

The discovery of a new type of fossil nuclear track in mica is reported. This track is produced by the recoil nucleus accompanying the α-particle decay of uranium and thorium impurities. The tracks are very short and can be seen with phase contrast microscopy. Measurement of fossil α-recoil track densities, coupled with determinations of the thorium and uranium contents, provides a new dating technique analogous to the previously discovered "fission-track method." The primary advantage of the α-recoil method is a several-thousand-fold increase in sensitivity over the fission-track technique. The α-recoil method should also prove useful in studying the problem of extinct isotopes in meteorites.
D-Glucose: Preferential Binding to Brush Borders Disrupted with Tris(hydroxymethyl)aminomethane
Authors: Faust Robert G. , Wu Shih-min L. , Faggard Mary L.
Published: October 2006

The actively transported sugar D-glucose binds to brush borders disrupted with tris(hydroxymethyl)aminomethane in preference to D-mannose and L-glucose, which are not actively transported. This preferential binding of D-glucose is not dependent on either added Na
+
or adenosine triphosphatase activity stimulated by Na
+
with K
+
and Mg
2+
, but it is temperature-dependent and is completely inhibited by 0.1 millimolar phlorizin and 1 millimolar mercuric chloride.
Ciguatoxin: Isolation and Chemical Nature
Authors: Scheuer Paul J. , Takahashi Wataru , Tsutsumi Junzo , Yoshida Tamao
Published: October 2006

Ciguatoxin, the agent responsible for ciguatera, a disease produced in humans from ingestion of certain fishes, has been isolated from specimens of the moray eel,
Gymnothorax javanicus
. The toxin is apparently a lipid containing quaternary nitrogen, hydroxyl, and carbonyl functions.
Autologous Immune-Complex Pathogenesis of Experimental Allergic Glomerulonephritis
Authors: Edgington Thomas S. , Glassock Richard J. , Dixon Frank J.
Published: October 2006

A renal tubular epithelial antigen is deposited in association with gamma globulin and complement in glomeruli from rats with experimental allergic glomerulonephritis induced by immunization with renal tubular antigens. Apparently, in normal kidneys this antigen is concentrated in the distal segment of the proximal convoluted tubular epithelium, and the principal source of this antigen in the glomerular deposits is autologous. This form of glomerulonephritis provides an experimental prototype for what may be termed "autologous immune-complex" diseases.
Red Cell Slip at a Wail in vitro
Authors: Bennett Leon
Published: October 2006

Interferometric microscope observations of flowing blood indicate that the absolute number of red cells maintaining sliding contact with a wall is of the order 10
4
per square centimeter at low flow rates. Contacting cell oscillation and orientation results are given. The near wall local hematocrit is found to be relatively low.
Molecular Code for Cooperativity in Hemoglobin
Authors: Ackers Gary K. , Doyle Michael L. , Myers David , Daugherty Margaret A.
Published: October 2006

Although tetrameric hemoglobin has been studied extensively as a prototype for understanding mechanisms of allosteric regulation, the functional and structural properties of its eight intermediate ligation forms have remained elusive. Recent experiments on the energetics of cooperativity of these intermediates, along with assignments of their quaternary structures, have revealed that the allosteric mechanism is controlled by a previously unrecognized symmetry feature: quaternary switching from form T to form R occurs whenever heme-site binding creates a tetramer with at least one ligated subunit on each dimeric half-molecule. This "symmetry rule" translates the configurational isomers of heme-site ligation into six observed switchpoints of quaternary transition. Cooperativity arises from both "concerted" quaternary switching and "sequential" modulation of binding within each quaternary form, T and R. Binding affinity is regulated through a hierarchical code of tertiary-quaternary coupling that includes the classical allosteric models as limiting cases.
Biological Significance of Unwinding Capability of Nuclear Matrix-Associating DNAs
Authors: Bode J. , Kohwi Y. , Dickinson L. , Joh T. , Klehr D. , Mielke C. , Kohwi-Shigematsu T.
Published: October 2006

Matrix attachment regions (MARs) are thought to separate chromatin into topologically constrained loop domains. A MAR located 5′ of the human β-interferon gene becomes stably base-unpaired under superhelical strain, as do the MARs flanking the immunoglobulin heavy chain gene enhancer; in both cases a nucleation site exists for DNA unwinding. Concatemerized oligonucleotides containing the unwinding nucleation site exhibited a strong affinity for the nuclear scaffold and augmented SV40 promoter activity in stable transformants. Mutated concatemerized oligonucleotides resisted unwinding, showed weak affinity for the nuclear scaffold, and did not enhance promoter activity. These results suggest that the DNA feature capable of relieving superhelical strain is important for MAR functions.
Predisposition to Renal Cell Carcinoma Due to Alteration of a Cancer Susceptibility Gene
Authors: Walker Cheryl , Goldsworthy Thomas L. , Wolf Douglas C. , Everitt Jeffrey
Published: October 2006

A single germ line gene mutation at a tumor susceptibility locus in a rodent model of hereditary human renal cancer caused a 70-fold increase in susceptibility to chemical carcinogenesis. A carcinogen that targeted both renal epithelial and mesenchymal cells caused an increase in tumors of epithelial origin in susceptible animals; the number of carcinogen-induced mesenchymal tumors was unaffected by the presence of the mutation at the susceptibility locus. Thus, this mutation defines a genetic locus for susceptibility to carcinogen-induced tumors and modulation of carcinogen susceptibility by this locus exhibits cell-type specificity.
An Amino Acid Mutation in a Potassium Channel That Prevents Inhibition by Protein Kinase C
Authors: Busch Andreas E. , Varnum Michael D. , North R. Alan , Adelman John P.
Published: October 2006

A slowly activating, voltage-dependent potassium channel protein cloned from rat kidney was expressed in
Xenopus
oocytes. Two activators of protein kinase C, 1-oleoyl-2-acetyl-
rac
-glycerol and phorbol 12,13-didecanoate, inhibited the current. This inhibition was blocked by the kinase inhibitor staurosporine. Inhibition of the current was not seen in channels in which Ser
103
was replaced by Ala, although other properties of the current were unchanged. These results indicate that inhibition of the potassium current results from direct phosphorylation of the channel subunit protein at Ser
103
.
Evidence for a Computational Distinction Between Proximal and Distal Neuronal Inhibition
Authors: Vu Eric T. , Krasne Franklin B.
Published: October 2006

Most neurons have inhibitory synapses both "proximally" near the spike-initiating zone and "distally" on dendrites. Although distal inhibition is thought to be an adaptation for selective inhibition of particular dendritic branches, another important distinction exists between proximal and distal inhibition. Proximal inhibition can attenuate excitatory input absolutely so that no amount of excitation causes firing. Distal inhibition, however, inhibits relatively; any amount of it can be overcome by sufficient excitation. These properties are used as predicted in the circuit-mediating crayfish escape behavior. Many neuronal computations require relative inhibition. This could partly account for the ubiquity of distal inhibition.
Oxygen-18 Variations in Sulfate Ions in Sea Water and Saline Lakes
Authors: Longinelli A. , Craig H.
Published: October 2006

A new method measures the oxygen-isotopic composition of dissolved sulfate ions and barium sulfate. Sulfate ions in the oceans are enriched in oxygen-18 by 9.5 per mille relative to mean ocean water and show only minor variations, probably because the exchange rate with water is slow enough to prevent local equilibrium with surface waters. Sulfate ions in saline lakes and brines have oxygen-18 enrichment of from 7 to 23 per mille relative to mean ocean water; the value of the highest enrichment observed is about the same as that of atmospheric oxygen.
Radiocarbon Dating of Biogenetic Opal
Authors: Wilding L. P.
Published: October 2006

Approximately 75 grams of biogenetic opal were isolated from 45 kilograms of soil by employing gross particle-size and sink-float specific gravity fractionation procedures. After pretreatment of the sample to remove extraneous organic and inorganic carbon contaminants, the carbon occluded within opal phytoliths was dated at 13,300 ± 450 years before the present. Therefore, biogenetic opal is stable for relatively long periods.
Plasma Membranes of Rat Liver: Isolation of Lipoprotein Macromolecules
Authors: Barclay M. , Barclay R. K. , Essner E. S. , Skipski V. P. , Terebus-Kekish O.
Published: October 2006

Three high-density lipoprotein classes and one protein were separated from rat-liver plasma membranes that had been treated with mild sonic oscillation. The lipoproteins were separated and identified by techniques in which ultracentrifugation was used. Enzyme markers and electron-microscopic examination revealed membrane preparations essentially free of contaminating cellular particulates.
Sex Differences in Taste Preference for Glucose and Saccharin Solutions
Authors: Valenstein Elliot S. , Kakolewski Jan W. , Cox Verne C.
Published: October 2006

Taste preferences of mature male and female rats for caloric and noncaloric sweet solutions have been found to differ. Although females do not drink more water than males, they consume significantly greater quantities of a slightly sweet 3 percent glucose and a very sweet 0.25 percent saccharin solution. When given a choice, males switch their initial preference for a saccharin solution to a preference for a glucose solution after several days, while females maintain a preference for the saccharin solution. Females also prefer significantly higher concentrations of saccharin than males do.
Geomagnetic Polarity Change and Faunal Extinction in the Southern Ocean
Authors: Watkins N. D. , Goodell H. G.
Published: October 2006

Paleomagnetic polarity changes have been detected in nine deep-sea sedimentary cores (from the Pacific-Antarctic Basin) in which an extinction horizon of a radiolarian assemblage was previously independently determined. The depths of the polarity change 0.7 million years ago and the faunal boundary are closely correlated, confirming that the faunal extinction was locally virtually synchronous. Although the reason for the faunal extinction is unknown. the possibility of causal relationships between faunal extinction and factors directly involved with sedimentation rate, sedimentation rate variation, and sediment type appears to be excluded.
Pyrimidine Nucleotide Synthesis: Regulatory Control during Transformation of Lymphocytes in vitro
Authors: Lucas Zoltan J.
Published: October 2006

The incorporation of uridine into RNA in lymphocytes undergoing transformation induced by phytohemagglutinin parallels its incorporation into the intracellular pool of acid-soluble nucleotides and coincides with a 20-fold increase in the specific activity of uridine kinase. This increase is dependent upon synthesis of both RNA and protein and is subject to both repression and end-product inhibition by cytidine.
Regulation of Intracellular Sodium Concentrations in Rat Diaphragm Muscle
Authors: Fozzard Harry A. , Kipnis David M.
Published: October 2006

The concept is suggested that the sodium pump mechanism is influenced by the transmembrane electrical potential, and that the pump acts to maintain a constant electrochemical gradient for sodium. Evidence leading to this suggestion was obtained in rat diaphragm muscle by altering systematically the transmembrane chemical gradient for sodium ions and the transmembrane voltage. The voltage changes were produced by varying the extracellular and intracellular potassium ion concentrations. In each case the intracellular sodium concentration changed, presumably by activity of the sodium pump, so that the total electrochemical gradient for sodium was restored.
Force, Shortening, and Work in Muscular Contraction: Relative Contributions to Overall Energy Utilization
Authors: Jöbsis Frans F. , Duffield James C.
Published: October 2006

The amounts of energy used during muscular contraction under different loads have been compared by measurement of the total amount of disturbance of the concentration of reduced nicotinamide-adenine dinucleotide during the period of oxidative recovery. The results are in quantitative agreement with the concept that three parameters determine the energy utilization: namely the time-integral of the force development, the time-integral of the shortening process, and the mechanical work.
Potency Difference between the Zwitterion Form and the Cation Forms of Tetrodotoxin
Authors: Camougis George , Takman Bertil H. , Rene J. , Tasse P.
Published: October 2006

Tetrodotoxin can exist as a zwitterion or two different cations in aqueous solutions. The cation forms are more potent in nerve block. Thus the lactone-hemilactal configuration of tetrodotoxin influences potency. Electrostatic attraction, hydrogen bonding, and intermolecular hemilactal formation are possible mechanisms of interaction with membrane receptors.
Specific Binding of Chromosomal Protein HMG1 to DNA Damaged by the Anticancer Drug Cisplatin
Authors: Pil Pieter M. , Lippard Stephen J.
Published: October 2006

The mechanism of action of the anticancer compound
cis
-diamminedichloroplatinum(II) (cisplatin) involves covalent binding to DNA. In an effort to understand the tumor-specific cytotoxicity of such DNA damage, the interactions of these lesions with cellular proteins have been studied. One such protein has been identified as the high-mobility group protein HMG1. Recombinant rat HMG1 binds specifically (dissociation constant 3.7 ± 2.0 × 10
-7
molar) to DNA containing cisplatin d(GpG) or d(ApG) intrastrand cross-links, which unwind and bend DNA in a specific manner, but not to DNA modified by therapeutically inactive platinum analogs. These results suggest how HMG1 might bind to altered DNA structures and may be helpful in designing new antitumor drugs.
Positive Control of Pre-mRNA Splicing in Vitro
Authors: Tian Ming , Maniatis Tom
Published: October 2006

Positive control of the sex-specific alternative splicing of
doublesex
(
dsx
) precursor messenger RNA (pre-mRNA) in
Drosophila melanogaster
involves the activation of a female-specific 3′ splice site by the products of the
transformer
(
tra
) and
transformer-2
(
tra-2
) genes. The mechanisms of this process were investigated in an in vitro system in which the female-specific 3′ splice site could be activated by recombinant Tra or Tra-2 (or both). An exon sequence essential for regulation in vivo was shown to be both necessary and sufficient for activation in vitro. Nuclear proteins in addition to Tra and Tra-2 were found to bind specifically to this exon sequence. Therefore, Tra and Tra-2 may act by promoting the assembly of a multiprotein complex on the exon sequence. This complex may facilitate recognition of the adjacent 3′ splice site by the splicing machinery.
Reformation of Functional Liver Polyribosomes from Ribosome Monomers in the Absence of RNA Synthesis
Authors: Stewart Gloria A. , Farber Emmanuel
Published: October 2006

The administration to rats of the ethyl analog of methionine, ethionine, results in the rapid decrease in the hepatic concentration of adenosine triphosphate followed by an extensive disaggregation of polysomes to ribosome monomers and a concomitant inhibition of protein synthesis. These effects are readily reversed by the injection of methionine or precursors of adenine nucleotides such as adenine. The reformation of liver polyribosomes in such animals following the administration of adenine plus methionine was found to occur under conditions in which new RNA synthesis was markedly inhibited. Free messenger RNA without attached ribosomes must be capable of remaining functionally active in the liver cytoplasm for many hours.
Stretch Receptors in the Foregut of the Blowfly
Authors: Gelperin Alan
Published: October 2006

Two bipolar neurons are located in a nerve branch connecting the recurrent nerve and foregut of the blowfly
Phormia regina
Spike activity accompanying peristalsis or controlled enlargement of the foregut region is recorded from two cells in the recurrent nerve. The spikes are abolished by section of the nerve branch connecting recurrent nerve and foregut. It is concluded that the two neurons are the foregut stretch receptors predicted from results of behavioral experiments and vital to the regulation of feeding by the fly.
Release of Slow-Reacting Substance of Anaphylaxis in the Rat: Polymorphonuclear Leukocyte
Authors: Orange Robert P. , Valentine Martin D. , Austen K. Frank
Published: October 2006

The antigen-induced release of slow-reacting substance of anaphylaxis was studied in rats previously treated with different biological and pharmacological agents to deplete these animals of specific cellular elements. The polymorphonuclear leukocyte appears necessary as a crucial cell type for optimum release of the slow-reacting substance of anaphylaxis, whereas the mast cell and lymphocyte are not required.
Delayed Hypersensitivity: Bone Marrow as the Source of Cells in Delayed Skin Reactions
Authors: Lubaroff David M. , Waksman Byron H.
Published: October 2006

Adult Lewis rats were thymectomized, irradiated, and restored with bone marrow from allogeneic (or F
1
) donors. They were passively sensitized to tuberculin by a subsequent transfer of Lewis lymph node cells and were given intradermal skin tests with tuberculoprotein. In 24-hour skin reactions the majority of cells, in successive experiments, were shown to be allogeneic (or F
1
) with the use of isoantibody against the antigens of the transplanted marrow cells and by the indirect fluorescent antibody technique. Our results demonstrate that the nonspecific cells making up a large proportion of the infiltrating elements in tuberculin skin reactions probably originate in the bone marrow.
Sleep: Effects on Incorporation of Inorganic Phosphate into Brain Fractions
Authors: Reich Peter , Driver Judith K. , Karnovsky Manfred L.
Published: October 2006

During sleep there is a two- to threefold increase in the incorporation of inorganic orthophosphate-
32
P into a chemical fraction of the brain of the 20-day-old rat. This increase is not in the lipids or nucleic acids, but is associated with an acid-labile phosphate entity of the tissue residue after extraction of these fractions and phosphorus-containing substances of low molecular weight.
Problematical Pleistocene Artifact Assemblage from Northwestern Spain
Authors: de Aguirre Emiliano , Butzer Karl W.
Published: October 2006

Interdisciplinary study of a Paleolithic site at Budiño, Louro Valley (province of Pontevedra), Spain, shows the presence of various tool-making techniques and types of tools in a single undisturbed site complex found
in situ
within Middle Würm colluvial deposits.
Reward and Learning in the Goldfish
Authors: Lowes Gillian , Bitterman M. E.
Published: October 2006

An experiment with goldfish showed the effects of change in amount of reward that are predicted from reinforcement theory. The performance of animals shifted from small to large reward improved gradually to the level of unshifted large-reward controls, while the performance of animals shifted from large to small reward remained at the large-reward level. The difference between these results and those obtained in analogous experiments with the rat suggests that reward functions differently in the instrumental learning of the two animals.
Archosaurian Reptiles: A New Hypothesis on Their Origins
Authors: Reig Osvaldo A.
Published: October 2006

The characteristics of the first archosaurs, the proterosuchian thecodonts, show that neither of the supposed common ancestors of archosaurs and lepidosaurs could actually be an ancestor of archosaurs. Instead, the evidence seems to indicate that the archosaurian ancestors are probably in the ophiacodont-varanopsid group of the pelycosaurian synapsids. In particular, the Varanopsidae are strongly indicative of proterosuchian relationships, as they have evolved some characters which are elsewhere found only in archosaurs. Archosaurs and lepidosaurs apparently have different origins; the former come from the pelycosaurs, and the latter come from the captorhinomorph cotylosaurs through the Millerettiformes.
Inferior Olive of the Cat: Intracellular Recording
Authors: Crill Wayne E. , Kennedy Thelma T.
Published: October 2006

The action potential evoked from inferior olivary neurons of the cat by orthodromic, antidromic, or intracellular stimulation has a large prolonged depolarization, frequently with several superimposed smaller spikes. The all-or-nothing unitary response appears to be a property of the cell, and the later spikes are not secondary to synaptic excitation by recurrent axon collaterals.
Radio Observations of Interstellar Hydroxyl Radicals
Authors: Barrett Alan H.
Published: October 2006

The discovery of the radio frequency lines of OH gave the first positive evidence of the existence of OH in the interstellar medium. In the 3½ years that have intervened, many observations have revealed totally unexpected anomalies in the radio-spectral properties of interstellar OH. As a result, no reliable astrophysical information has been derived from the OH observations, but a large body of information is waiting to be unraveled. The interpretations of the data which have been made, such as the values derived for OH/H abundance ratios or for the kinetic temperatures of interstellar gas clouds, must be viewed with caution. They may turn out to be drastically in error, once the origin of the OH emission and absorption is fully understood.
Ornithine-Urea Cycle Activity in
Xenopus laevis
: Adaptation in Saline
Authors: McBean Ralph L. , Goldstein Leon
Published: October 2006

The concentration of urea in the blood and the rate of urea excretion were markedly elevated in
Xenopus
maintained in hypertonic saline for 2 to 3 weeks. These changes were accompanied by a twofold increase in the activity of the ornithine-urea cycle as measured in liver slices. The activity of carbamoyl phosphate synthetase rose threefold in frogs adapted to saline. These results suggest that changes in activities of urea cycle enzymes may be important in the adaptation of aquatic organisms to environments of varying salinities.
Chemoprophylactic Agent in Schistosomiasis: 14,15-Epoxygeranylgeraniol
Authors: Mors Walter B. , dos Santos Fo. Miguel Fascio , Monteiro Hugo J. , Gilbert B. , Pellegrino J.
Published: October 2006

The occurrence of all-
trans
(-)-14,15-epoxygeranyl-geraniol in
Pterodon pubescens
Benth. is established, and its prophylactic activity against infection by
Schitsosma mansoni
demonstrated. Two other diterpenes present in the oil are inactive.
Perhydro-β-Carotene in the Green River Shale
Authors: Murphy Mary T. J. , McCormick A. , Eglinton G.
Published: October 2006

Several triterpenes and the tetraterpene perhydro-β-carotene have been identified in the branched-cyclic hydrocarbon fraction of this Eocene shale. The analytical procedure included thiourea adduction followed by combined gas chromatography and mass spectrometry.
Lateral Hypothalamic Stimulation in Satiated Rats: The Rewarding Effects of Self-Induced Drinking
Authors: Mendelson Joseph
Published: October 2006

It is well known that thirsty rats will press a lever for water. The purpose of the present experiment was to demonstrate that, when water is freely available, nonthirsty rats will press a lever for thirst. Three satiated rats, bearing permanently implanted electrodes, were trained to press a lever which caused stimulation to be applied to an area of the lateral hypothalamus which induces thirst. The animals were tested with and without water available. Two of the rats pressed the lever to induce thirst only when water was available. Thus, thirst-inducing stimulation was not rewarding by itself, but only in combination with drinking.
Sodium Humate Solution Studied with Small-Angle X-Ray Scattering
Authors: Wershaw R. L. , Burcar P. J. , Sutula C. L. , Wiginton B. J.
Published: October 2006

Small-angle x-ray scattering analyses of sodium humate solutions indicate either that particles of two or more different sizes exist in solution or that all of the particles are the same size but consist of a dense core and a less dense outer shell. Fractionation on a molecular sieve chromatographic column suggests that the first possibility is the more likely of the two. The radius of gyration and molecular weight of the larger particles are respectively 110 Å and 1 × 10
6
and those of the smaller particles 38 Å and 2.1 × 10
5
. These particles are ellipsoidal.
Local Geomagnetic Events Associated with Displacements on the San Andreas Fault
Authors: Breiner Sheldon , Kovach Robert L.
Published: October 2006

The piezomagnetic properties of rock suggest that a change in subsurface stress will manifest itself as a change in the magnetic susceptibility and remanent magnetization and hence the local geomagnetic field. A differential array of magnetometers has been operating since late 1965 on the San Andreas fault in the search for piezomagnetic signals under conditions involving active fault stress. Local changes in the geomagnetic field have been observed near Hollister, California, some tens of hours preceding the onset of abrupt creep displacement on the San Andreas fault.
Temperature-Dependence of the Polarity of Electrical Charges on Ice Crystals
Authors: Odencrantz F. Kirk , Buecher Roger W.
Published: October 2006

The electrical polarity of ice crystals produced from a supercooled cloud is temperature-dependent. The charge polarity appears to be associated with the crystal habit. This phenomenon may be important in precipitation and cloud electrification processes.
Vitamin A Deficiency: Effect on Retinal Structure of the Moth
Manduca sexta
Authors: Carlson Stanley D. , Steeves Harrison R. , VandeBerg Jerry S. , Robbins William E.
Published: October 2006

Sphingid moths (
Manduca sexta
) were reared for several generations on an artificial diet deficient in vitamin A and its precursors. Retinal tissue from depleted moths was removed for histological examination. There was extensive histolysis in the retinal epithelium and underlying nervous and connective tissues. This pathology correlated with severe visual impairment, even though normal growth, metamorphosis, and reproduction occurred. In the adult this pathology could be reversed when the larvae were reared only on tobacco (its usual host) or on the artificial diet supplemented with β-carotene or vitamin A palmitate.
Intracellular Pool of Unhydroxylated Polypeptide Precursors of Collagen
Authors: Bhatnagar Rajendra S. , Prockop Darwin J. , Rosenbloom Joel
Published: October 2006

The hydroxyproline and hydroxylysine in collagen are synthesized by an apparently unique pathway in which proline and lysine are hydroxylated after they are incorporated into a large polypeptide precursor of collagen called protocollagen. When the hydroxylation of protocollagen in isolated tissues is intermittently interrupted, hydroxylation can occur after complete polypeptides are released from ribosomal complexes. Cartilage from chick embryos was incubated with the iron chelator α,α'-dipyridyl for 2 hours to inhibit protocollagen hydroxylase, and then the inhibition was reversed by transferring the tissues to medium containing ferrous iron and no α,α'-dipyridyl. "Pulse labeling" of the tissues during these two periods indicated that both the accumulated protocollagen and the polypeptides synthesized after reversal of the inhibition were hydroxylated at the same rate. Even when no measures are taken to inhibit the hydroxylation of protocollagen, most of the hydroxyproline in collagen is probably synthesized after complete protocollagen polypeptides are released from ribosomes.
Mutarotase in Erythrocytes: Isolation and Properties
Authors: Sacks William
Published: October 2006

Mutarotase was found in lysed human erythrocytes and in hemoglobin. The enzyme was partially purified by treatment with ethanol and chloroform at -15°C. It was nondialyzable and heat sensitive, and was inhibited by D-galactose, L-arabinose, D-ribose, D-xylose, and D-arabinose.
Quishqui Puncu: A Preceramic Site in Highland Peru
Authors: Lynch Thomas F.
Published: October 2006

The complete campsite industry from this early site includes crude chopping tools, microblades, and numerous scraper and projectile point types. A square-based variant of the Ayampitín point is distinctive of the earliest occupation, but the incidence and distribution of other types indicate that seasonal use persisted into agricultural and ceramic periods.
Pesticide Pollution Control
Authors: Nicholson H. Page
Published: October 2006

The suggested methods for evaluating water quality with respect to its content of selected groups of pesticides are based on interpretation of generally available information. They are intended to provide a base for discussion leading to the development of public policy for the inclusion of such values in water quality standards.
Hydrazine-Air Fuel Cells
Authors: Evans George E. , Kordesch Karl V.
Published: October 2006

A fuel cell is an electrochemical device that continues to generate electrical power as long as reactants are supplied and products are removed at properly controlled rates. An assembly of cells is required within which the conversion of chemical to electrical energy occurs; also required is a set of auxiliary components to supply the reactants and remove the products (including waste heat) under controlled steady-state conditions. In addition to the desired energy-conversion reactions, there are deleterious side reactions that can impair fuel economy. From knowledge of these factors influencing the possible reactions, and guided by principles of elementary chemical thermodynamics, the electrochemist can select optimum conditions for cell performance. It is then the job of the engineer to design auxiliary components and controlling devices to provide the electrochemical cells with the best possible approach to these optimum conditions.