Showing papers by "Memorial University of Newfoundland published in 1975"
TL;DR: Heliotropic flowers act, in sunshine, as solar reflectors, their corollas focusing heat on the sporophylls, and these phenomena are important in maximizing the small heat budget.
Abstract: Heliotropic flowers (Dryas integrifolia, Papaver radicatum) act, in sunshine, as solar reflectors, their corollas focusing heat on the sporophylls. Considerable intrafloral temperatures are generated. Winds above 3.8 meters per second and cloud abolish the effect. Insects that bask in the flowers also gain heat. The phenomena areimportant in maximizing the small heat budget.
191 citations
TL;DR: In this article, it was shown that the power required from precession to stir the core of a geomagnetic dynamo cannot exceed 108 W if the core flow remains stable.
Abstract: Summary
The power requirement of a stationary geomagnetic dynamo driven by some agency external to the core (e. g. precession) is equal to the ohmic dissipation in the core, Q1. For a dynamo in which differential rotation is important we show that Q1ασ1−2, where σ1∼ 5 × 105 ohm−1 m−1 is the electrical conductivity of the core. Estimates of Q1 for kinematic dynamo models range from 109 to over 1012 Watts, depending on the particular regenerative scheme characterizing the dynamo. Precessional power input to the magnetic field can be estimated in terms of the electromagnetic part of the core-mantle coupling and the tiltover angle (inclination of the core angular momentum vector to that of the mantle). We correct Stacey's estimate of core-mantle coupling to take into account the diurnal frequency of precession-induced flow relative to the mantle, and show that the power available from precession to stir the core cannot exceed 108 W if the core flow remains stable. As a caution against the widespread uncritical acceptance of Malkus’ claims to have demonstrated the energetic adequacy of precession-driven hydromagnetic turbulence, we enumerate the mathematical and physical errors which cast doubt on his theoretical arguments.
141 citations
TL;DR: In the gray squirrel, the prairie dog, and the Mexican and 13‐line ground squirrels, there exist two distinct classes of photoreceptors that have cone‐ like and rod‐like anatomical features respectively, but only the cone‐like (C) receptor had been observed in the other species.
Abstract: In the gray squirrel (Sciurus carolinensis), the prairie dog (Cynomys ludovicianus), and the Mexican and 13-line ground squirrels (Citellus mexicanus and C. tridecemlineatus) there exist two distinct classes of photo-receptors that have cone-like and rod-like anatomical features respectively. These two receptor classes were previously known to exist in the gray squirrel, but only the cone-like (C) receptor had been observed in the other species. We have now found small numbers of rod-like (R) receptors in the other species as well. R-receptors comprise about 40% of the receptors in the gray squirrel, 10% of the receptors in the prairie dog, and 4-5% of the receptors in the two species of ground squirrel. This paper describes certain light and electron microscopic features of these two receptor classes including their synaptic connections with second-order cells and with each other. We find that the C-receptor has a morphology and synaptic organization characteristic of other mammalian cones. However, the R-receptor differs from other mammalian rods in certain morphological respects, and its synaptic organization has both cone and rod characteristics as well as some unusual features.
125 citations
TL;DR: Sexual maturity of males and females was related to significant increases in plasma gonadotropin with the highest values observed for females near the time of ovulation.
111 citations
TL;DR: The ground field k is algebraically closed and of characteristic p ≠ O. The p-rank of an abelian variety A/k is σA if there are σ A copies of Z/pZ in the group of points of order p in A(k) as discussed by the authors.
Abstract: The groundfield k is algebraically closed and of characteristic p ≠ O. The p-rank of an abelian variety A/k is σA if there are σA copies of Z/pZ in the group of points of order p in A(k). The p-rank σX of a curve X/k is the p-rank of its Jacobian. In general the genus of X is ≥ σX. X is ordinary if equality holds.
108 citations
TL;DR: The organic hydroperoxide, cumene hydro peroxide was capable of supporting the O-dealkylation of a variety of methoxy and ethoxy compounds in the presence of hepatic microsomes — NADPH and molecular oxygen were not required for this reaction.
102 citations
TL;DR: It was concluded that the associative capacity of sickness can be reduced through pre-exposure.
101 citations
TL;DR: It is concluded that iron enters the cell, then is probably reduced inside the cell by NADPH via the NADPH-cytochrome P-450 reductase, and in the reduced state initiates lipid peroxidation.
Abstract: Lipid peroxide formation was initiated by the addition of either ADP-complexed Fe3+ or cumene hydroperoxide to a suspension of isolated hepatocytes. The reaction was monitored by malonaldehyde measurements. Upon the addition of iron, malonaldehyde production in the cells started immediately but ceased within 30–60 min, and the response was dose-related with iron concentrations ranging from 19 to 187 μM. Malonaldehyde formation was associated with increased oxygen uptake and conjugated diene production. The addition in vitro of N,N,N′;N′-tetramethyl-p-phenylenediamine, menadione or p-benzoquinone inhibited the iron-induced malonaldehyde production. It was also possible to demonstrate an apparent disappearance of malonaldehyde from fresh cells by addition of adequate amounts of N,N,N′,N′-tetramethyl-p-phenylenediamine (100 μM).
The attenuation of the iron-induced malonaldehyde production was found to be correlated with an increased binding of iron to an intracellular ferritin fraction. Further, malonaldehyde formation was also associated with a conversion of reduced glutathione to the oxidized form which, in turn, revealed a faster permeation out of the cells into the surrounding medium of the oxidized than of the reduced thiol. So, concomitant with the redox alterations, there was also an overall loss of glutathione from the cells.
Cumene hydroperoxide-induced malonaldehyde production could be initiated by the addition of this peroxide in concentrations ranging from 150 μM to the liver cell incubate. With concentrations below 150 μM, a lag phase was present which seemed to be glutathione-dependent.
It is concluded that iron enters the cell, then is probably reduced inside the cell by NADPH via the NADPH–cytochrome P-450 reductase, and in the reduced state initiates lipid peroxidation. The reaction is inhibited by intracellular mechanisms, the glutathione redox system being of principal importance, and possibly terminated by the iron-apoferritin complex formation.
97 citations
TL;DR: It is concluded that blueberry fields and their immediate surrounds received doses of the pesticide Fenitrothion, and that crop failures have, in part, been caused by drifts or indiscriminate applications, or both, of the pesticides.
92 citations
TL;DR: The duration of embryonic development is inversely correlated with egg size in Crustacea, and development is faster in amphipods and mysids than in decapods, isopods and cumaceans of the same size.
Abstract: The duration of embryonic development is inversely correlated with egg size in Crustacea. Development is faster in amphipods and mysids than in decapods, isopods and cumaceans of the same size. The relationships are of considerable significance in the ecology of these animals.
89 citations
01 Jan 1975
TL;DR: A highly purified gonadotropic hormone preparation has been obtained from chum salmon pituitaries by extraction with ethanolic or aqueous buffer, affinity chromatography on Con A Sepharose and gel filtration on Sephadex G-75 superfine.
Abstract: A highly purified gonadotropic hormone preparation has been obtained from chum salmon (Oncorhynchus keta) pituitaries by extraction with ethanolic or aqueous buffer, affinity chromatography on Con A Sepharose and gel filtration on Sephadex G-75 superfine. A purified fraction from Sephadex G-75 averaged 448 mug NIH-LH-S18/mg glycoprotein as measured by the uptake of radiophosphate into chick testes. A total of 1.1 g of salmon gonadotropin (s) (SG)/kg fresh tissue was recovered when the isolation began with an aqueous extraction. Analytical polyacrylamide gel electrophoresis (P.A.G.E.) of the purified fraction from Sephadex G-75 displayed a single broad zone in non-dissociating conditions and two bands in 8 M urea. Polyacrylamide gel electrofocusing yielded six sharp bands with an isoelectric point range of 4.38 to 5.05, and four bands with an isoelectric point range of 4.31 to 4.95 in 8 M urea. A molecular weight of 41,000 was determined by gel filtration. A subunit molecular weight of 17,800 +/- 10% was found by P.A.G.E. in 0.1% sodium dodecyl sulphate (SDS), suggesting that native SG consists of two subunits. Purified preparations were highly stable in Tris-Cl buffers and retained their activity for several months when stored at -73 degrees C.
TL;DR: Results had been expected on the basis of Revusky's (1971) hypothesis that removal of the rat from the learning situation to spend the delay elsewhere facilitates long delay learning by reducing associative interference.
TL;DR: The Uivak gneisses are the oldest quartzo-feldspathic suite in the area and are distinguished from the undifferentiated ones by the presence of porphyritic basic dykes (Saglek dykes) as mentioned in this paper.
TL;DR: The enhanced oxidase activity under hypotonic conditions decreased to normal values when the medium was made isotonic and suggested that a reversible conformational change in the plasma membrane was responsible for the activation of oxidase activities.
TL;DR: In this paper, the latent heat of fusion of mantle material is the greatest buffer on degrees of melting in upwelling diapirs, and it is shown that diapiric up-rise alone requires that the diapirus originate at depths in excess of 300 km, whereas melting of an irregular geotherm is preferred for the origin of these liquids.
TL;DR: It is concluded that the isolated liver cell system provides a valuable tool for the study of lipid peroxidation and its pathological implications.
Abstract: Lipid peroxidation was initiated by the addition of either ADP-complexed Fe3+ or cumene hydroperoxide to isolated rat hepatocytes and the resultant biochemical and morphological alterations investigated. As previously observed with microsomes, malonaldehyde formation was associated with the inactivation of glucose-6-phosphatase. Inhibition of microsomal oxidative drug metabolism was correlated with the release and subsequent inactivation of NADPH-cytochrome c reductase, whereas cytochrome P-450 destruction occurred only in the presence of high concentrations of the organic hydroperoxide which were associated with extensive malonaldehyde formation. Under these conditions there were also marked ultrastructural alterations in the hepatocytes which were not apparent after incubation in the presence of iron (less than or equal to 187 muM Fe3+). The latter treatment was, however, associated with moderate biochemical effects such as glucose-6-phosphatase inactivation and increased membrane permeability. The cellular defence system against lipid peroxidation is discussed and it is concluded that the isolated liver cell system provides a valuable tool for the study of lipid peroxidation and its pathological implications.
TL;DR: In this paper, the authors present an analysis of catches made with rectangular midwater trawls (RMTs) in the North Atlantic at about 20°W and at about 60°N, 53°N and 40°N.
Abstract: The present work is part of an analysis of catches made with rectangular midwater trawls (RMTs) in the North Atlantic at about 20°W and at 60°N, 53°N, 40°N (all in Lu & Clarke, 1975), 30°N (Clarke & Lu, 1974), 18°N and 11°N (Lu & Clarke, 1975). The collections were made for the ecological programme of the National Institute of Oceanography, Wormley, England (now part of the Institute of Oceanographic Sciences).
TL;DR: An organization of enzymes in mitochondrial matrix was proposed and the significance of this finding was discussed with reference to the efficient operation and regulation of the Krebs cycle.
TL;DR: A large inbred family is described in which there were seven cases of Hodgkin's disease, three of lymphosarcoma, two of thymoma,Two of common variable immunodeficiency, and single cases of retinoblastoma, neuroblastoma, and rhabdomyosarComa.
TL;DR: Assessing the state of knowledge of such showy plants as are emblematic in Canada finds that the reproductive biology of the plants is incompletely known, and if pollen vectors are involved they, too, are unknown.
Abstract: Pollination interrelationships constitute vital, and often very precise, links in environmental productivity. The co-dependence of much of the native fauna and flora in these terms is cause for grave concern in the light of continuing environmental pollution. In New Brunswick, as an established case-history, wide-scale forest applications of the organophosphorus insecticide Fenitrothion have severely damaged the native pollinator fauna of lowbush blueberries, and. have apparently disrupted bird populations so that they have become unprecedented agricultural pests.Unfortunately, little is known of the pollination interrelationships in natural or semi-natural environments. Very often the reproductive biology of the plants is incompletely known, and if pollen vectors are involved they, too, are unknown. This point is illustrated by assessing the state of knowledge of such showy plants as are emblematic in Canada (Table I).
TL;DR: Studies with eBGR-/ebgR+ merdiploids have shown that ebgR- is recessive, and it is concluded that the synthesis of ebg enzyme is under negative control.
Abstract: The ebg (evolved β-galactosidase) regulatory locus has been mapped. The map order is argG–ebgA–ebgR–tolC–metC , and there is 1.6% recombination between ebgR and ebgA . Studies with ebgR-/ebgR+ merdiploids have shown that ebgR- is recessive, and it is concluded that the synthesis of ebg enzyme is under negative control.
TL;DR: In this article, a novel solution of sodium saccharin which was followed by intubation of a.9, 2.7, 8.1, or 12.15% NaCl solution was found to produce aversions at a delay of 7.5 h.
Abstract: Adult male rats were allowed to drink a novel solution of sodium saccharin which was followed .5, 1.5, 4.5, 7.0, 13.5, or 24.0 h later by intubation of a .9, 2.7, 8.1, or 12.15% (w/v) solution of sodium chloride (NaCl). Three days after the single training trial, consumption of saccharin was again measured. Significant differences between groups were found. When consumption by the experimental groups at each CS-UCS delay was compared with that of the isotonic NaCl (.9%) control group, it was found that all groups showed aversions at delays of .5, 1.5, and 4.5 h. Animals intubated with 8.1% or 12.15% NaCl solution also showed aversions at a delay of 7.0 h, and those intubated with the 12.15% solution showed an aversion at a delay of 13.5 h. No NaCl concentration used produced aversions at a CS-UCS interval of 24.0. These results reflect differences in the effectiveness of a range of NaCl concentrations in producing one-trial aversions at long CS-UCS intervals.
01 Jan 1975
TL;DR: One of the bands stimulated cAMP production primarily in trout testes and the other stimulated trout ovaries, providing evidence for two gonadotropins, each of which is sex specific.
Abstract: Two proteins with gonadotropin activity have been isolated from a highly purified chum salmon (Oncorhynchus keta) gonadotropin preparation (G-75 Fraction II) by chromatography on DEAE Bio Gel A. These gonadotropins exhibited distinct behaviour in polyacrylamide gel electrophoresis, chromatography on Sephadex G-75 superfine, and ratios of cAMP stimulation in immature rainbow trout ovaries and testes.Rechromatography of G-75 Fraction II on Sephadex G-75 superfine gave a symmetrical protein peak with a coincident cAMP activity profile. Repeated freezing and thawing elicited a shift in the cAMP activity profile toward the trailing edge of the protein peak. Data are discussed in terms of two gonadotropin molecules which respond differently to phase changes.Charge polymorphism was exhibited by isoelectric focusing in polyacrylamide gels of one of the DEAE fractions. Five UV absorbing bands were observed which stimulated cAMP production in immature rainbow trout gonads. Three of these bands increased adenyl cycl...
TL;DR: The results indicate that a satisfactory general theory of memory must encompass distinctions in both symbolic and sensory modalities as well as differences in the organizational demands of the memory task.
Abstract: Pictures and sounds of familiar objects and their visual and auditory names were compared in free and serial recall tasks. The results of two experiments showed, most notably, that type of task interacted significantly with symbolic (verbal-nonverbal) and sensory (visual-auditory) modalities. Nonverbal items were remembered relatively better in free recall, whereas verbal items were superior in serial recall. In the visual modality, pictures were superior to words in both recall tasks; in the auditory modality, conversely, nonverbal sounds were inferior to words in serial recall but sounds and words did not differ in free recall. The results indicate that a satisfactory general theory of memory must encompass distinctions in both symbolic and sensory modalities as well as differences in the organizational demands of the memory task.
TL;DR: In this paper, it is suggested that these mafic/ultramafic complexes represent remnants of small ocean basins that opened within the continental-rise prisms, and that the later Acadian orogeny may have been the result of convergence of oceanic trenches, leading to formation of transform faults.
TL;DR: In this paper, it was shown that Iherzolite (primitive mantle), harzburgite (residuum of partial melting), cumulus dunite, gabbro, trondhjemite, sheeted diabase dikes, pillow lava (all representing the magma produced by partial melting) and deep-water sediments.
TL;DR: In this paper, a series of hauls made at discrete horizons between o and 2000 m with opening-closing nets during both daylight and darkness were made for the ecological programme of the National Institute of Oceanography, Wormley, Surrey, England.
Abstract: This is one of a series of four papers dealing with vertical distribution of cephalopods in the North Eastern Atlantic at six stations near 20° W and at about 10° intervals from 60°N to 11° N (Clarke & Lu, 1974, 1975 a ; Lu & Clarke, 1975). The present study is based upon a series of hauls made at discrete horizons between o and 2000 m with opening-closing nets during both daylight and darkness. The collections were made for the ecological programme of the National Institute of Oceanography, Wormley, Surrey, England (now part of the Institute of Oceanographic Sciences).
TL;DR: Hooded rats were given conditioned inhibition training in which the taste of saccharin alone was always followed by induced illness, but the smell of amyl acetate was not; it was demonstrated that the odor had acquired active inhibitory properties.
TL;DR: A profile of 25 patients thought to be suffering from hysterical attacks found the operation of either dissociative or conversion mechanisms during the attacks was difficult to demonstrate, and suggestion was sometimes the only factor found to account for the form of the symptoms.
Abstract: Four patients have been described who were believed to be suffering from hysterical attacks. The recent literature on hysterical seizures has been examined and the four new patients were added to two other reported series to provide a profile of 25 cases. Preceding or accompanying physical illness was a common finding, and 32 percent of subjects had a previous history of neurological disease. The existence of a substrate of CNS damage is supported by the finding of EEG abnormalities in 40 percent of patients.In other ways the cases resembled classical descriptions of subjects liable to hysterical illness. The operation of either dissociative or conversion mechanisms during the attacks was difficult to demonstrate, and suggestion was sometimes the only factor found to account for the form of the symptoms. Further studies to examine the nature of the relationship between brain damage and hysterical disorders appear justified.