bluuebunny/crossref_metadata_2025 huggingface dataset:
The Fluid Mosaic Model of the Structure of Cell Membranes
Authors: Singer S. J. , Nicolson Garth L.
Published: October 2006

A fluid mosaic model is presented for the gross organization and structure of the proteins and lipids of biological membranes. The model is consistent with the restrictions imposed by thermodynamics. In this model, the proteins that are integral to the membrane are a heterogeneous set of globular molecules, each arranged in an
amphipathic
structure, that is, with the ionic and highly polar groups protruding from the membrane into the aqueous phase, and the nonpolar groups largely buried in the hydrophobic interior of the membrane. These globular molecules are partially embedded in a matrix of phospholipid. The bulk of the phospholipid is organized as a discontinuous, fluid bilayer, although a small fraction of the lipid may interact specifically with the membrane proteins. The fluid mosaic structure is therefore formally analogous to a two-dimensional oriented solution of integral proteins (or lipoproteins) in the viscous phospholipid bilayer solvent. Recent experiments with a wide variety of techniques and several different membrane systems are described, all of which are consistent with, and add much detail to, the fluid mosaic model. It therefore seems appropriate to suggest possible mechanisms for various membrane functions and membrane-mediated phenomena in the light of the model. As examples, experimentally testable mechanisms are suggested for cell surface changes in malignant transformation, and for cooperative effects exhibited in the interactions of membranes with some specific ligands.

Note added in proof
: Since this article was written, we have obtained electron microscopic evidence that the concanavalin A binding sites on the membranes of SV40 virus-transformed mouse fibroblasts (3T3 cells) are more clustered than the sites on the membranes of normal cells, as predicted by the hypothesis represented in Fig. 7B. There has also appeared a study by Taylor
et al.
showing the remarkable effects produced on lymphocytes by the addition of antibodies directed to their surface immunoglobulin molecules. The antibodies induce a redistribution and pinocytosis of these surface immunoglobulins, so that within about 30 minutes at 37°C the surface immunoglobulins are completely swept out of the membrane. These effects do not occur, however, if the bivalent antibodies are replaced by their univalent Fab fragments or if the antibody experiments are carried out at 0°C instead of 3°C. These and related results strongly indicate that the bivalent antibodies produce an aggregation of the surface immunoglobulin molecules in the plane of the membrane, which can occur only if the immunoglobulin molecules are free to diffuse in the membrane. This aggregation then appears to trigger off the pinocytosis of the membrane components by some unknown mechanism. Such membrane transformations may be of crucial importance in the induction of an antibody response to an antigen, as well as in other processes of cell differentiation.
Evidence of Pollen Tubes in Paleozoic Pteridosperms
Authors: Rothwell Gar W.
Published: October 2006

A saccate pollen grain with a branched pollen tube has been discovered within the pollen chamber of a fossil seed-fern ovule of Middle Pennsylvanian age. This suggests that microgametophytes comparable to those of living gymnosperms were produced by some Paleozoic pteridosperms.
Inhibition of Antibodies to Nuclear Antigen and to DNA in New Zealand Mice Infected with Lactate Dehydrogenase Virus
Authors: Oldstone Michael B. A. , Dixon Frank J.
Published: October 2006

New Zealand mice developed antibodies to nuclear antigen leading to immune-complex nephritis. Humoral antibody was directed primarily against denatured DNA, although antibody to native DNA was also found. Persistent infection with lactate dehydrogenase virus significantly lowered antibodies both to nuclear antigen and to DNA in these mice. In addition, female (NZB × W)F
1
mice infected with lactate dehydrogenase virus were protected from the usual nephritic death occurring after the trapping of complexes of nuclear antigen and its antibody and of DNA and its antibody in the glomerular filter.
Isozymes of Phenylalanine Hydroxylase
Authors: Barranger John A. , Geiger Paul J. , Huzino A. , Bessman Samuel P.
Published: October 2006

Three isozymes of phenylalanine hydroxylase exist in adult rat liver. They are chromatographically unique. Partial characterization suggests that they are similar in chemical properties and differ only in charge. Estimation of the Stokes radii indicates that the isozymes have similar molecular weights of about 200,000. Two isozymes exist in human fetal liver. Alterations of the relative amounts of these isozymes may control the phenotype of the disease phenylketonuria.
Gene Therapy for Human Genetic Disease?
Authors: Friedmann Theodore , Roblin Richard
Published: October 2006

In our view, gene therapy may ameliorate some human genetic diseases in the future. For this reason, we believe that research directed at the development of techniques for gene therapy should continue. For the foreseeable future, however, we oppose any further attempts at gene therapy in human patients because (i) our understanding of such basic processes as gene regulation and genetic recombination in human cells is inadequate; (ii) our understanding of the details of the relation between the molecular defect and the disease state is rudimentary for essentially all genetic diseases; and (iii) we have no information on the short-range and long-term side effects of gene therapy. We therefore propose that a sustained effort be made to formulate a complete set of ethicoscientific criteria to guide the development and clinical application of gene therapy techniques. Such an endeavor could go a long way toward ensuring that gene therapy is used in humans only in those instances where it will prove beneficial, and toward preventing its misuse through premature application.

Two recent papers have provided new demonstrations of directed genetic modification of mammalian cells. Munyon et al. restored the ability to synthesize the enzyme thymidine kinase to thymidine kinase-deficient mouse cells by infection with ultraviolet-irradiated herpes simplex virus. In their experiments the DNA from herpes simplex virus, which contains a gene coding for thymidine kinase, may have formed a hereditable association with the mouse cells. Merril et al. reported that treatment of fibroblasts from patients with galactosemia with exogenous DNA caused increased activity of a missing enzyme, α-D-galactose-1-phosphate uridyltransferase. They also provided some evidence that the change persisted after subculturing the treated cells. If this latter report can be confirmed, the feasibility of directed genetic modification of human cells would be clearly demonstrated, considerably enhancing the technical prospects for gene therapy.
Antigenic Relationships in Mammalian DNA Polymerase
Authors: Chang Lucy M. S. , Bollum F. J.
Published: October 2006

Rabbit antibody was prepared against a high-molecular-weight DNA polymerase purified from the soluble fraction of calf thymus gland. This antibody does not inhibit terminal deoxynucleotidyl transferase isolated from that source, but does inhibit both low-molecular-weight and high-molecular-weight DNA polymerases isolated from cytoplasmic and nuclear fractions of a number of mammalian tissues (mouse L cells, calf thymus, phytohemagglutinin-stimulated human lymphocytes, rat liver, and rabbit bone marrow). The results suggest that (i) no antigenic relationship exists between terminal transferase and DNA polymerase, (ii) common antigenic determinants exist in the DNA polymerases from all mammalian sources, and (iii) multiple forms of DNA polymerase found in mammalian, cells are related by having polypeptide sequences or subunits in common.
Electric Enhancement of Bone Healing
Authors: Lavine Leroy S. , Lustrin Irving , Rinaldi Robert A. , Shamos Morris H. , Liboff Abraham R.
Published: October 2006

A human congenital pseudarthrosis of the tibia, unresponsive to conventional treatment, was stimulated to healing by direct electric current. The method was modeled after prior experimental work in vivo in rabbits. X-ray photographs, histological techniques, and electron microscopy confirmed the presence of newly formed bone in the defect region.
Selenium: Relation to Decreased Toxicity of Methylmercury Added to Diets Containing Tuna
Authors: Ganther H. E. , Goudie C. , Sunde M. L. , Kopecky M. J. , Wagner P. , Oh Sang-Hwan , Hoekstra W. G.
Published: October 2006

Japanese quail given 20 parts per million of mercury as methylmercury in diets containing 17 percent (by weight) tuna survived longer than quail given this concentration of methylmercury in a corn-soya diet. Tuna has a relatively high content of selenium and tends to accumulate additional selenium when mercury is present. A content of selenium in the diet comparable to that supplied by tuna decreased methylmercury toxicity in rats. Selenium in tuna, far from being a hazard in itself, may lessen the danger to man of mercury in tuna.
Classic to Postclassic in Highland Central Mexico
Authors: Dumond D. E. , Muller Florencia
Published: October 2006

The data and argument we have presented converge on three points.

1) With the decline and abandonment of Teotihuacan by the end of the Metepec phase (Teotihuacan IV), the valleys of Mexico and of Puebla-Tlaxcala witnessed the development of a ceramic culture that was represented, on the one hand, by obvious Teotihuacan derivations in presumably ritual ware and possible Teotihuacan derivations in simpler pottery of red-on-buff, and, on the other hand, by elements that seem to represent a resurgence of Preclassic characteristics. Whether the development is explained through a measure of outside influence or as a local phenomenon, the direct derivation of a substantial portion of the complex from Classic Teotihuacan is unmistakable. This transitional horizon predated the arrival of plumbate tradeware in highland central Mexico.

2) The transitional horizon coincided with (and no doubt was an integral part of) an alteration of Classic settlement patterns so drastic that it must bespeak political disruption. Nevertheless, there is no evidence that the Postclassic center of Tula represented a significant force in the highlands at that time. There is no evidence that the center of Cholula, which may even have been substantially abandoned during the previous period, was able to exert any force at this juncture; it appears more likely that Cholula was largely reoccupied after the abandonment of Teotihuacan. There is no direct evidence of domination by Xochicalco or any other known major foreign center, although some ceramic traits suggest that relatively minor influences may have emanated from Xochicalco; unfortunately, the state of research at that center does not permit a determination at this time. Thus the most reasonable view on the basis of present evidence is that the abandonment of Teotihuacan was not the direct result of the strength of another centralized power, although some outside populations may have been involved in a minor way. Whatever the proximate cause, however, it is now clear that the abandonment of Teotihuacan led to a period of Balkanization in which no single center, or pair of centers, were dominant in the highlands.

3) The transitional horizon saw the immediate development of a cultural distinction between the Valley of Mexico and the Valley of Puebla-Tlaxcala, a distinction in which differential degrees of outside cultural influence may have played a part. This distinction was magnified in the early Postclassic, with the rising power of Tula on the west and of Cholula on the east, and Balkanization ended with the growth of empire.
Nerve Growth Factor: Stimulation of Regenerative Growth of Central Noradrenergic Neurons
Authors: Björklund Anders , Stenevi Ulf
Published: October 2006

The growth of new axonal sprouts was studied from transected, ascending noradrenergic axons into transplants of iris tissue in the caudal hypothalamus of the rat. A single intraventricular injection of nerve growth factor, given at the time of axonal damage, resulted in an increased formation and growth of new noradrenaline sprouts 7 days later. The effect seemed to be proportional to the administered dose of nerve growth factor.
Coexistence of Two Asexual Strains on a Single Resource
Authors: Levin Bruce R.
Published: October 2006

A stable equilibrium was obtained for two F
-
strains of
Escherichia coli
in a glucose minimal medium. This equilibrium cannot readily be explained by traditional models of population genetics and apparently violates some forms of the ecological principle of competition exclusion. A mechanism involving an inverse relationship between the growth rates of these strains at the exponential and "stationary" phases is suggested as a possible explanation for the observed stable equilibrium.
Proprioceptive Illusions Induced by Muscle Vibration: Contribution by Muscle Spindles to Perception?
Authors: Goodwin Guy M. , McCloskey D. Ian , Matthews Peter B. C.
Published: October 2006

When vibration of 100 hertz was applied to the tendon of the biceps or the triceps muscle, the subject made a systematic misjudgment of the angle at the elbow. During contraction the error could be as much as 40 degrees. The subject thought that the elbow was in the position that it would have assumed if the vibrated muscle had been stretched.
Silk Moth Eclosion: Hormonal Triggering of a Centrally Programmed Pattern of Behavior
Authors: Truman James W. , Sokolove Philip G.
Published: October 2006

The emergence of the adult cecropia silk moth from the pupal skin involves a stereotyped series of abdominal movements—the pre-eclosion behavior. This behavior, triggered by a neurosecretory hormone, consists of three phases that are characterized by the relative frequency and pattern of movements. Electrical recordings from a nerve cord with severed peripheral nerves demonstrate that the pre-eclosion behavior is prepatterned in the abdominal ganglia. In response to the hormone, the entire 1.25-hour behavioral program can be activated and "read off" in the absence of sensory feedback.
Photoreceptor-Bipolar Cell Transmission in the Perfused Retina Eyecup of the Mudpuppy
Authors: Dacheux Ramon F. , Miller Robert F.
Published: October 2006

The hypothesis that a synaptic transmitter is released by photoreceptors in the dark is supported by experiments in which cobalt was used as a synaptic blocking agent, while intracellular recordings of receptors and neurons that are directly postsynaptic to receptors were maintained. In the dark the depolarizing bipolars are hyperpolarized, whereas the hyperpolarizing bipolars are depolarized.
Epoxides of Carcinogenic Polycyclic Hydrocarbons Are Frameshift Mutagens
Authors: Ames Bruce N. , Sims P. , Grover P. L.
Published: October 2006

K-region epoxides of the carcinogens benz
[a]
anthracene, dibenz [
a
,
h
]anthracene, and 7-methylbenz
[a]
anthracene are mutagenic in strains of Salmonella typhimurium designed to detect frameshift mutagens. Parent hydrocarbons, K-region diols and phenols and some other epoxides are inactive as mutagens in these tests. Polycyclic hydrocarbon epoxides, and other presumed proximal carcinogens, are discussed as examples of intercalating agents with reactive side chains. It has been shown previously that intercalating agents with reactive side chains are potent frameshift mutagens.
Radula Tooth Structure of the Gastropod
Conus imperialis
Elucidated by Scanning Electron Microscopy
Authors: Kohn Alan J. , Nybakken James W. , Van Mol Jean-Jacques
Published: October 2006

Scanning electron microscopy of the hollow, harpoon-like radula tooth of the toxoglossan gastropod
Conus
has elucidated the structure and relationships of its component parts: apex, cutting edge, barbs, serration, adapical and basal openings of the lumen, external and internal folds of the shaft, and base. The functional roles of these components in prey capture are proposed.
Nutritional and Environmental Interactions in the Behavioral Development of the Rat: Long-Term Effects
Authors: Levitsky David A. , Barnes Richard H.
Published: October 2006

The behavioral effects of early malnutrition and early environmental isolation were observed in male rats. Dietary and environmental manipulations occurred during the first 7 weeks of life, after which followed a 10-week recovery period. On the basis of several different responses, it was found that the behavioral effects of early malnutrition were exaggerated by the environmental isolation. In most cases, the behavioral effects of early malnutrition were completely eliminated by supplying "additional stimulation" early in life. Two theoretical mechanisms are proposed to explain these findings.
Color Adaptation of Spatial Frequency Detectors in the Human Visual System
Authors: Lovegrove W. J. , Over Ray
Published: October 2006

Observers exposed alternately to a vertical grating of one spatial frequency in red light and a vertical grating of different spatial frequency in green light subsequently report frequency-specific color aftereffects when shown gratings in white light. Aftereffects occur, however, only when inspection gratings differ in spatial frequency by one octave or more and the frequency of at least one grating is above 3 cycles per degree. This spatial selectivity of the aftereffect is considered in terms of a neural adaptation model incorporating evidence on the tuning of spatial frequency detectors in the human visual system.
Tongue Cooling during Drinking: A Regulator of Water Intake in Rats
Authors: Kapatos Gregory , Gold Richard M.
Published: October 2006

Rats that had been deprived of water for 23½ hours were presented with water for 30 minutes per day. As the temperature of the water was increased from 12° to 36° C (body temperature), the total water intake for 30 minutes increased 71 percent. Tongue cooling during drinking appears to suppress drinking in anticipation of extracellular hydration.
Feedback: Real-Time Delayed Vision of One's Own Tracking Behavior
Authors: Smith William M.
Published: October 2006

When a televised display of a person's own behavior in pursuit tracking is delayed, his performance, as measured by time on target, is seriously degraded. Data for six subjects on two tracking patterns under seven delay values reveal a linear inverse relationship between the logarithm of the time on target and the magnitude of delay.
Carbonic Anhydrase and Bone Remodeling: Sulfonamide Inhibition of Bone Resorption in Organ Culture
Authors: Minkin Cedric , Jennings Joan M.
Published: October 2006

Five sulfonamide inhibitors of carbonic anhydrase inhibited parathyroid hormone-induced resorption of bone in organ culture. The relative activities of the sulfonamides as resorption inhibitors were such as to suggest the presence of a functional carbonic anhydrase system in bone linked to the mechanism of bone resorption.
Free-Floating Mucus Webs: A Novel Feeding Adaptation for the Open Ocean
Authors: Gilmer Ronald W.
Published: October 2006

Observations by means of conventional scuba techniques have revealed that highly modified planktonic gastropods, in the order Thecosomata, utilize a free and unsupported mucus web for collecting food particles. Their delicate bodies, quick reactions, and apparent abundance suggest that traditional plankton-sampling methods may be inadequate to assess their importance in the blue-water plankton communities.
Microbial Uptake of Lead
Authors: Tornabene T. G. , Edwards H. W.
Published: October 2006

Micrococcus luteus
and
Azotobacter
sp. cells grown in broth in contact with a dialysis membrane containing lead bromide were found to immobilize 4.9 and 3.1 × 10
2
milligrams of lead per gram of whole cells, on a dry weight basis, respectively. Culture turbidity and cell count measurements on these and other cell cultures show that lead bromide, lead iodide, and lead bromochloride in concentrations approaching solubility limits have no detectable effect on overall growth rate and cell viability. Analyses of cellular subfractions reveal that fractions of cell wall plus membrane contain 99.3 and 99.1 percent of the lead found associated with
Micrococcus luteus
and
Azotobacter
sp., respectively. The remainder is found associated with the cytoplasmic fractions.
Endosperm Protein Synthesis in Maize Mutants with Increased Lysine Content
Authors: Misra Prem S. , Jambunathan Ramamurthi , Mertz Edwin T. , Glover David V. , Barbosa Helio M. , McWhirter Kenneth S.
Published: October 2006

The endosperm proteins of the maize mutants,
opaque-2
,
opaque-7
,
floury-2
,
brittle-2
, and the double mutant of
opaque-2
and
brittle-2
, were separated into five soluble fractions by the Landry-Moureaux method. As compared to their isogenic normal counterparts, the mutant endosperms had higher concentrations of albumins, globulins, and glutelin-3, and lower concentrations of prolamines. The combination of the
opaque-2
and
brittle-2
genes enhanced this difference. Although the four mutant genes are located on three different chromosomes, they exert a similar effect on endosperm protein composition. Five other starch-modifying mutants with high lysine content resemble the
brittle-2
mutant in endosperm protein composition, when the gene is present either singly or combined with
opaque-2
. Therefore, the pattern of protein synthesis in all maize mutants with high lysine concentrations may be either identical or very similar. Because no synergistic effect on lysine concentration is obtained when
floury-2
is combined with
opaque-2
, different pathways leading to reduced zein synthesis may exist in the floury and starch-modifying mutants with high lysine concentrations.
Rearing Complexity Affects Branching of Dendrites in the Visual Cortex of the Rat
Authors: Volkmar Fred R. , Greenough William T.
Published: October 2006

Higher-order dendritic branching is considerably greater in Golgi-stained neurons from the occipital cortex of rats reared in groups in a complex environment than in similar neurons of littermates reared individually in laboratory cages. Littermates reared in pairs in cages have intermediate amounts of branching, while lower-order branching did not appear to be affected by any rearing environment.
Earth and Mars: Evolution of Atmospheres and Surface Temperatures
Authors: Sagan Carl , Mullen George
Published: October 2006

Solar evolution implies, for contemporary albedos and atmospheric composition, global mean temperatures below the freezing point of seawater less than 2.3 aeons ago, contrary to geologic and paleontological evidence. Ammonia mixing ratios of the order of a few parts per million in the middle Precambrian atmosphere resolve this and other problems. Possible temperature evolutionary tracks for Earth and Mars are described. A runaway greenhouse effect will occur on Earth about 4.5 aeons from now, when clement conditions will prevail on Mars.
Daily Variation in Concentration of Cortisol in Plasma in Intact and Hypophysectomized Gulf Killifish
Authors: Srivastava Anil K. , Meier Albert H.
Published: October 2006

A daily variation in concentration of cortisol in plasma is synchronized by a 12-hour daily photoperiod in intact as well as in hypophysectomized fish. The daily rhythm in concentration of the adrenal steroid does not depend on a daily rhythm in the concentration of pituitary adrenocorticotropic hormone.
Coral Chronometers: Seasonal Growth Bands in Reef Corals
Authors: Knutson David W. , Buddemeier Robert W. , Smith Stephen V.
Published: October 2006

Autoradiographs and x-radiographs have been made of vertical sections through the centers of reef corals from Eniwetok. Radioactivity bands in the coral structure are caused by strontium-90 and are related to specific series of nuclear tests, thus making possible calculation of long-term growth rates. These data indicate that the cyclic variations in radial density revealed by x-radiography are annual.
Spongy Mesophyll Remains in Fossil Leaf Compressions
Authors: Chandrasekharam A.
Published: October 2006

Spongy mesophyll tissue has been discovered preserved in fossil leaf compressions. The fossils occur in an outcrop at Genesee, Alberta, Canada. The fossiliferous beds belong to the Edmonton formation of Upper Cretaceous-lower Tertiary age. The mesophyll characteristic, when taken in conjunction with other characteristics, was found useful in the identification of some fossil leaves. Numerous detailed observations as well as comparisons of both living and fossil leaves show that the remains represent neither the epidermal nor the palisade tissue.
Cochlear Inner and Outer Hair Cells: Functional Differences
Authors: Dallos Peter , Billone N. C. , Durrant J. D. , Wang C.-y. , Raynor S.
Published: October 2006

The cochlear microphonic response was measured with differential electrodes from the first and third cochlear turns of normal guinea pigs and those treated with the ototoxic drug kanamycin. Histological controls showed that the outer hair cells in treated animals were missing over the basal half of the damaged cochleas, while the inner hair cells were intact. Measurements are consistent with the hypothesis that the potentials produced by inner hair cells are proportional to the velocity of the basilar membrane, whereas potentials generated by outer hair cells (which dominate the response of normal cochleas) are proportional to the displacement of the basilar membrane.
Intestinal Uptake of Macromolecules: Effect of Oral Immunization
Authors: Walker W. Allan , Isselbacher Kurt J. , Bloch Kurt J.
Published: October 2006

Animals were orally immunized with horseradish peroxidase and bovine serum albumin, and absorption of these antigens was studied. In comparison with controls, a consistent and significant decrease in peroxidase uptake was noted in both germ-free and conventional rats immunized with peroxidase; a similar decrease in serum albumin uptake was also noted in animals immunized with serum albumin. There was no difference in the uptake of an unrelated macromolecule. These observations suggest that local immunization interferes specifically with the intestinal uptake of macromolecular antigens.
Inhibition of Bacterial Adherence by Secretory Immunoglobulin A: A Mechanism of Antigen Disposal
Authors: Williams R. C. , Gibbons R. J.
Published: October 2006

Preparations of secretory immunoglobulin A (S-IgA) isolated from human parotid fluid specifically inhibited the adherence of
Streptococcus
strains to epithelial cells. Since bacterial adherence is a prerequisite for colonization of mucous surfaces. S-IgA-mediated inhibition of adherence would limit bacterial colonization. This mechanism can explain how secretory immunoglobulins function in the disposal of bacterial antigens.
Atmospheric Carbon Dioxide: Its Role in Maintaining Phytoplankton Standing Crops
Authors: Schindler D. W. , Brunskill G. J. , Emerson S. , Broecker W. S. , Peng T.-H.
Published: October 2006

The rate of invasion of carbon dioxide into an artificially eutrophic Canadian Shield lake with insufficient internal sources of carbon was determined by two methods: measuring the carbon : nitrogen : phosphorus ratios of seston after weekly additions of nitrogen and phosphorus, and measuring the loss of radon-222 tracer from the epilimnion. Both methods gave an invasion rate of about 0.2 gram of carbon per square meter per day. The results demonstrate that invasion of atmospheric carbon dioxide may be sufficient to permit eutrophication of any body of water receiving an adequate supply of phosphorus and nitrogen.
Siliceous Algal and Bacterial Stromatolites in Hot Spring and Geyser Effluents of Yellowstone National Park
Authors: Walter Malcolm R. , Bauld John , Brock Thomas D.
Published: October 2006

Growing algal and bacterial stromatolites composed of nearly amorphous silica occur around hot springs and geysers in Yellowstone National Park, Wyoming. Some Precambrian stromatolites may be bacterial rather than algal, which has important implications in atmospheric evolution, since bacterial photosynthesis does not release oxygen.
Conophyton
stromatolites were thought to have become extinct at the end of the Precambrian, but are still growing in hot spring effluents.
Electrical Responses of Insect Central Neurons: Augmentation by Nerve Section or Colchicine
Authors: Pitman Robert M. , Tweedle Charles D. , Cohen Melvin J.
Published: October 2006

Intracellular recording from the somata of central motor neurons in the cockroach
Periplaneta americana
normally shows little or no electrical response evoked by soma depolarization or by antidromic stimulation. Within 4 days after either cutting the axon or administration of colchicine, large action potentials can regularly be recorded from cell bodies of metathoracic motor neurons. Each experimental procedure evokes formation of a dense, perinuclear ribonucleic acid ring in the soma of neurons showing augmented electrical responses.
Synapses onto Different Morphological Types of Retinal Ganglion Cells
Authors: West Roger W. , Dowling John E.
Published: October 2006

The percentage of bipolar and amacrine synapses onto ganglion cell dendrites of the ground squirrel has been determined by electron microscopy of cells impregnated by the Golgi method. One group of ganglion cells has mainly amacrine input (approximately 97 percent); the other group has an approximately equal bipolar and amacrine input. Morphologically distinct types of ganglion cells usually have a consistent synaptic input, but exceptions may exist.
Hemoglobin Lepore Trait: Globin Synthesis in Bone Marrow and Peripheral Blood
Authors: Gill Frances , Atwater Jean , Schwartz Elias
Published: October 2006

There was decreased synthesis of the β-globin chain in the peripheral blood, and equal synthesis of α- and non-α-chains in the bone marrow of three patients with hemoglobin Lepore trait, similar to the findings in patients with heterozygous β-thalassemia. There is a relative instability of the synthetic mechanism for normal β-chain in these patients.
Inactivation of Horizontal Cells in Turtle Retina by Glutamate and Aspartate
Authors: Cervetto Luigi , MacNichol Edward F.
Published: October 2006

Glutamate and aspartate completely suppress the activity of horizontal cells but only partially affect the response of receptor cells to light. The changes observed in the receptor responses are consistent with the interruption of a synaptically mediated process rather than with a direct action on the receptor membrane.
Electrical Behavior of Cartilage during Loading
Authors: Bassett C. Andrew L. , Pawluk Robert J.
Published: October 2006

When cartilage is deformed, it becomes electrically polarized. At least two mechanisms seem to underlie this phenomenon, namely, a short-duration, high-amplitude, piezoelectric-like response and a longer-duration, lower-amplitude response secondary to streaming potentials. The polarity of articular cartilage during loading could hypothetically facilitate joint lubrication.
Inhibition of Sperm-Egg Interaction by Specific Antibody
Authors: Shivers C. A. , Dudkiewicz A. B. , Franklin L. E. , Fussell E. N.
Published: October 2006

Treatment of hamster ova, in vitro, with ovary specific antibody interferes with sperm-egg interaction by inhibiting sperm attachment to the zona pellucida and subsequent zona penetration. This inhibition results from precipitation of the zona by the specific antibody.
Natural Selection of Parental Ability to Vary the Sex Ratio of Offspring
Authors: Trivers Robert L. , Willard Dan E.
Published: October 2006

Theory and data suggest that a male in good condition at the end of the period of parental investment is expected to outreproduce a sister in similar condition, while she is expected to outreproduce him if both are in poor condition. Accordingly, natural selection should favor parental ability to adjust the sex ratio of offspring produced according to parental ability to invest. Data from mammals support the model: As maternal condition declines, the adult female tends to produce a lower ratio of males to females.
Calcium-Induced Ciliary Reversal in the Extracted Models of "Pawn," a Behavioral Mutant of
Paramecium
Authors: Kung Ching , Naitoh Yutaka
Published: October 2006

"Pawn," a genic mutant of
Paramecium aurelia
, cannot swim backward as the wild type can upon proper stimulation. In contrast, after membrane disruption by Triton X-100, the adenosine triphosphate-magnesium reactivated models of Pawns swim backward in the presence of calcium as wild-type models do. Thus, the mutant phenotype is due to an impairment in the membrane and not in the calcium-sensitive motile system.
Maternally Acquired Runt Disease
Authors: Beer A. E. , Billingham R. E.
Published: October 2006

Without altering the structural integrity of the placenta by irradiation or drugs, we have shown that it is possible to immunize females both adoptively and actively against the paternally inherited transplantation antigens of their fetuses. Such immunization causes a high incidence of runt disease among the litters. Although the putative chimeric status of the affected offspring has yet to be confirmed, the results of our experiments support the thesis that runt disease is caused by the activities of "unwanted" immigrant lymphocytes from the maternal circulation. Our results suggest that immunologically activated cells are more likely to cross the placenta than normal cells and that this greater mobility may not be related to the immunologic specificity of the activated cells.

Two factors may have contributed to the apparent failure of numerous previous attempts to demonstrate the capacity of transplantation immunity to affect the well-being of a fetus or, more correctly, its placenta, in the way that might be expected of a homograft. (i) Investigators were preoccupied with obtaining a classic type of rejection, in utero, analogous to the rejection of an orthotopic skin homograft. The birth of consistently healthy-looking litters, interpreted as a failure of the experiment, convinced the investigators of the efficacy of nature's solution of the homograft problem and there was no reason for them to suspect its possible limitations. Observation of the litters for several weeks might have uncovered the phenomenon of maternally induced runt disease. (ii) Most investigators resorted to hyperimmunization of the mothers. This would have facilitated the synthesis of protective isoantibodies capable of interfering with the expression of the potentially harmful cellular immune response.

Ever since the abnormalities of runt disease were first described they have repeatedly been compared to those observed in patients with certain lymphomas. Various theories have been propounded as to how maternally transmitted graft-versus-host reactivity might lead to the development of these tumors. In mice it has been established that graft-versus-host reactivity may result in a high incidence of lymphomas . Recent analysis indicates that this graft-versus-host reactivity unmasks and activates normally latent and undemonstrable oncogenic viruses. The work we describe in this article may have some relevance to the possible clinical significance of transplacental cellular mobility in man. We suggest that the relatively high incidence of lymphomas in children might also be, in part at least, due to unmasking of oncogenic viruses by subclinical graft-versus-host reactivity mediated by immunocompetent cells of maternal origin. The statistical evidence that male infants are at greater risk than females is concordant with our observation that maternally induced runts include a significantly higher proportion of males than females.
Lunar Shape via the Apollo Laser Altimeter
Authors: Sjogren W. L. , Wollenhaupt W. R.
Published: October 2006

Data from the Apollo 15 and Apollo 16 laser altimeters reveal the first accurate elevation differences between distant features on both sides of the moon. The large far-side depression observed in the Apollo 15 data is not present in the Apollo 16 data. When the laser results are compared with elevations on maps from the Aeronautical Chart and Information Center, differences of 2 kilometers over a few hundred kilometers are detected in the Mare Nubium and Mare Tranquillitatis regions. The Apollo 16 data alone would put a 2-kilometer bulge toward the earth; however, the combined data are best fit by a sphere of radius 1737.7 kilometers. The offset of the center of gravity from the optical center is about 2 kilometers toward the earth and 1 kilometer eastward. The polar direction parameters are not well determined.
Gonadal Effects of Vasectomy and Vasoligation
Authors: Sackler Arthur M. , Weltman A. Stanley , Pandhi Vijay , Schwartz Ralph
Published: October 2006

During a 28-week study, vasectomy and vasoligation of immature male Wistar rats revealed that there was a significant decrease in urinary 17-ketosteroid in the vasectomized group at week 15; at week 28 there were significant decreases in the weights of the testes of the test groups, as compared to those receiving sham operations, with maximum alterations in the vasectomized rats. Small, soft discolored testes with cysts in the cauda epididymis and vas deferens regions occurred frequently in the test groups. The output of 17-ketosteroid in the urine and the findings in the testes indicate significant alterations in the morphology and function of the testes and suggest the need for caution and extensive investigations in man before recommending vasectomy as a simple, innocuous, "physiologic" means to ensure conception control.
Feedback: Beyond Behaviorism
Authors: Powers William T.
Published: October 2006

Consistent behavior patterns are created by variable acts, and generally repeat only because detailed acts change. The accepted explanation of this paradox, that "cues" cause the changes, is irrelevant; it is unsupported by evidence, and incapable of dealing with novel situations.

The apparent purposefulness of variations of behavioral acts can be accepted as fact in the framework of a control-system model of behavior. A control system, properly organized for its environment, will produce whatever output is required in order to achieve a constant sensed result, even in the presence of unpredictable disturbances. A control-system model of the brain provides a physical explanation for the existence of goals or purposes, and shows that behavior is the control of input, not output.

A systematic investigation of controlled quantities can reveal an organism's structure of control systems. The structure is hierarchical, in that some quantities are controlled as the means for controlling higher-order quantities. The output of a higher-order system is not a muscle force, but a reference level (variable) for a lower-order controlled quantity. The highest-order reference levels are inherited and are associated with the meta-behavior termed reorganization.

When controlled quantities are discovered, the related stimulus-response laws become trivially predictable. Variability of behavior all but disappears once controlled quantities are known. Behavior itself is seen in terms of this model to be self-determined in a specific and highly significant sense that calls into serious doubt the ultimate feasibility of operant conditioning of human beings by other human beings.
2,3,7,8-Tetrachlorodibenzo-p-dioxin: A Potent Inducer of δ-Aminolevulinic Acid Synthetase
Authors: Poland Alan , Glover Edward
Published: October 2006

2,3,7,8-Tetrachlorodibenzo-p-dioxin, a toxic contaminant frequently formed during the synthesis of the herbicide 2,4,5-trichlorophenoxyacetic acid, was shown to be a potent inducer of hepatic δ-aminolevulinic acid synthetase in the chick embryo. As little as 4.66 × 10-12mole of the contaminant per egg produces a significant increase in the activity of the enzyme. Induction of the enzyme is related to the dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin and, in contrast to that produced with other drugs, is prolonged in time, with 70 percent of the maximum induced activity present 5 days after a single dose. This contaminant is implicated as the likely causative agent in an outbreak of porphyria cutanea tarda in workers in a factory where 2,4,5-trichlorophenoxyacetic acid was being synthesized.
Sexual Differentiation of Pituitary Function: Apparent Difference between Primates and Rodents
Authors: Karsch F. J. , Dierschke D. J. , Knobil E.
Published: October 2006

Surges in luteinizing hormone secretion resembling those which occur spontaneously during the menstrual cycle were induced by acute elevations in circulating estrogen concentrations in both male and female rhesus monkeys gonadectomized in adulthood. These experiments demonstrate that in primates, in contrast to rodents, exposure of the hypothalamohypophyseal unit to androgens throughout fetal and postnatal development does not prevent the differentiation of the control system that governs cyclic gonadotropin secretion.
Sexual Behavior in Rhesus Monkeys after Vasectomy
Authors: Phoenix Charles H.
Published: October 2006

Vasectomy had no statistically significant effect on the sexual behavior of vigorous adult rhesus monkeys. Of two groups of males matched for level of sexual performance, one was vasectomized and the other underwent sham vasectomy. In sex tests administered within the month after surgery, the groups showed no difference (P > .05) in rate of mounting, intromission, or ejaculation, or in any other measure of sexual or sex-related behaviors.
Polychlorinated Biphenyl- and Triphenyl-Induced Gastric Mucosal Hyperplasia in Primates
Authors: Allen J. R. , Norback D. H.
Published: October 2006

Polychlorinated biphenyl or triphenyl ingestion by subhuman primates for 3 months produced hyperplasia and dysplasia of the gastric mucosa. The concentration of the biphenyl within the experimental diet was less than an order of magnitude greater than that occurring in random food samples sold in the United States and less than levels which have occurred in food products as a result of industrial accidents. The increased cellularity, abnormal dysplastic growth pattern, and invasion of the adjacent tissue region indicate compromised gastric function and are suggestive of an eventual neoplastic transformation.
Selenium: Biochemical Role as a Component of Glutathione Peroxidase
Authors: Rotruck J. T. , Pope A. L. , Ganther H. E. , Swanson A. B. , Hafeman D. G. , Hoekstra W. G.
Published: October 2006

When hemolyzates from erythrocytes of selenium-deficient rats were incubated in vitro in the presence of ascorbate or H
2
O
2
, added glutathione failed to protect the hemoglobin from oxidative damage. This occurred because the erythrocytes were practically devoid of glutathione-peroxidase activity. Extensively purified preparations of glutathione peroxidase contained a large part of the
75
Se of erythrocytes labeled in vivo. Many of the nutritional effects of selenium can be explained by its role in glutathione peroxidase.
Association of the HL-A7 Cross-Reacting Group with a Specific Reaginic Antibody Response in Allergic Man
Authors: Marsh David G. , Bias Wilma B. , Hsu Susan H. , Goodfriend Lawrence
Published: October 2006

A relatively small proportion (17 percent) of individuals highly allergic to ragweed were found to develop marked reaginic (immunoglobulin E-mediated) skin sensitivity to a minor ragweed pollen allergen Ra5 (molecular weight 5200). Sensitivity to Ra5 was significantly associated with the possession of a major histocompatibility antigen of the HL-A7 cross-reacting group. This appears to be the first evidence of a strong association between a specific immune response and a specific group of closely related HL-A antigens in man.
Hydrological and Ecological Problems of Karst Regions
Authors: LeGrand H. E.
Published: October 2006

Climate exerts a universal dominant influence on ecology, but processes of karstification have an equally high ecological influence in carbonate rock regions. Development of karst features depends greatly on the degree to which water containing carbon dioxide has been able to move on and through carbonate rocks and to remove some of the rock in solution. Distinctive features of many karst terranes include scarcity of soils, scarcity of surface streams, and rugged topography; less distinctive are the highly permeable and cavernous rocks, especially at the shallow depths. This high permeability gives rise to many practical problems, including (i) scarcity and poor predictability of groundwater supplies, (ii) scarcity of surface streams, (iii) instability of the ground, (iv) leakage of surface reservoirs, and (v) an unreliable waste-disposal environment.

Natural karst processes in some carbonate rock regions have caused a greater restriction in the development of biota than man can ever be suspected of causing.
Reduced Monoamine Oxidase Activity in Platelets: A Possible Genetic Marker for Vulnerability to Schizophrenia
Authors: Wyatt R. J. , Murphy D. L. , Belmaker R. , Cohen S. , Donnelly C. H. , Pollin W.
Published: October 2006

Monoamine oxidase activity in blood platelets was measured, with [
14
C]tryptamine as substrate, in 13 monozygotic twin pairs discordant for schizophrenia and in 23 normal volunteers. The monoamine oxidase activity of both schizophrenic and nonschizophrenic co-twins was significantly lower than it was for the normals, and it was highly correlated between twins. In addition, there was a significant inverse correlation between a measure of the degree of the schizophrenic disorder and the monoamine oxidase activity. These data suggest, but do not prove, that reduced platelet monoamine oxidase activity may provide a genetic marker for vulnerability to schizophrenia.
Androgen-Concentrating Cells in the Midbrain of a Songbird
Authors: Zigmond Richard E. , Nottebohm Fernando , Pfaff Donald W.
Published: October 2006

Androgen-concentrating cells were found in the midbrain of the chaffinch
Fringilla coelebs
by autoradiography using tritiated testosterone. Labeled cells were localized primarily in the nucleus intercollicularis, an area from which vocalizations can be electrically stimulated in birds. These autoradiographic results suggest that the nucleus intercollicularis is a site in the action of androgens on avian vocal behavior.
Opiate Receptor: Demonstration in Nervous Tissue
Authors: Pert Candace B. , Snyder Solomon H.
Published: October 2006

Tritiated naloxone, a powerful opiate antagonist, specifically binds to an opiate receptor of mammalian brain and guinea pig intestine. Competition for the opiate receptor by various opiates and their antagonists closely parallels their pharmacological potency. The opiate receptor is confined to nervous tissue.
Strychnine- and Pentylenetetrazol-Induced Changes of Excitability in
Aplysia
Neurons
Authors: Klee Manfred R. , Faber Donald S. , Heiss Wolf-Dieter
Published: October 2006

In
Aplysia
neurons isolated from their synaptic input strychnine induces doublet discharges associated in voltage clamp with a decrease in the threshold for the inward current and a reduction and delayed onset of the outward current. Pentylenetetrazol causes oscillations and bursting behavior in normally silent cells together with an increased inactivation of the delayed outward current and induced or enhanced anomalous rectification.
Preference Enhancement for Alcohol by Passive Exposure
Authors: Deutsch J. A. , Koopmans H. S.
Published: October 2006

A large and lasting enhancement of alcohol consumption over control levels is reported after direct infusion of 10 percent alcohol into the stomach of rats for 6 days.
Polyadenylic Acid in Visna Virus RNA
Authors: Gillespie D. , Takemoto K. , Robert M. , Gallo R. C.
Published: October 2006

Visna virus 70
S
RNA contains long stretches of polyadenylic acid [poly(A)]. The homogeneity in length of poly(
4
) regions is observed in 70
S
RNA from visna virus and all RNA tumor viruses tested, and not with other types of RNA. By this criterion visna virus resembles RNA tumor viruses.