Showing papers by "University of St Andrews published in 1973"
142 citations
105 citations
TL;DR: It is suggested that these properties enable the flood-tolerant species to facilitate the re-oxidation of NADH2 under conditions of anoxia and that this is associated with the greater ability of the species to withstand a reduction in the partial pressure of oxygen.
Abstract: SUMMARY
Flood-tolerant species from natural habitats differ from flood-intolerant species by being able to make more effective use of nitrate as an alternative electron acceptor to oxygen during periods of partial anaerobiosis. When flooded, tolerant species show marked increases in nitrate-reductase activity in roots and leaves. A greater ability to synthesize amino-acids under anoxia was also found in the tolerant species than in the intolerant. It is suggested that these properties enable the flood-tolerant species to facilitate the re-oxidation of NADH2 under conditions of anoxia and that this is associated with the greater ability of the species to withstand a reduction in the partial pressure of oxygen.
90 citations
TL;DR: The question of whether DNA sequences which specify protein structure are reiterated are still open and a special mechanism has been proposed to overcome this difficulty.
Abstract: BECAUSE of the large DNA content of the eukaryotic genome1,2 and the existence of reiterated DNA sequences3,4, it has been thought that the DNA sequences which specify protein structure are present in many copies per genome. The idea is not immediately compatible with the simple dominance relationships which alleles at many genetic loci show. A special mechanism has been proposed to overcome this difficulty5, which can also be surmounted in many other ways. From a theoretical standpoint, the question of whether DNA sequences which specify protein structure are reiterated is still open.
72 citations
TL;DR: Some initial findings are presented on the reflexes produced by input from these tension receptors and the integration of such reflexes in the intact animal.
Abstract: THE decapod crustaceans have many advantages for the study of the neuronal mechanisms controlling simple behaviour1–3. Numerous authors have investigated the functions of the walking legs, but models of the control mechanisms have been presented in terms of central programmes and reflexes related simply to the positions and movements of the joints4,5; little attention has been paid to the control of tension in the chief working muscles. It has been shown, however, that the tension of some of these muscles is monitored by sense organs6. We present here some initial findings on the reflexes produced by input from these tension receptors and the integration of such reflexes in the intact animal.
69 citations
TL;DR: Nineteen marine species were analyzed for caloric value; 7 of these were analysed for seasonal trends and Meganyctiphanes norvegica (krill) had more complex seasonal changes involving winter and summer maxima.
Abstract: Nineteen marine species were analyzed for caloric value; 7 of these were analysed for seasonal trends. Variation in caloric value for the polychaetesNephtys incisa andLumbrineris fragilis was not related to season.Pandalus montagui (decapod shrimp),Leptocheirus pinguis (gammarid amphipod),Astarte undata, Arctica islandica (pelecypods) had summer maxima.Meganyctiphanes norvegica (krill) had more complex seasonal changes involving winter and summer maxima.
67 citations
01 Aug 1973
TL;DR: In this article, the authors show that the attractive substance in cod muscle is soluble in distilled water and in sea water and withstands boiling, and that it is dialysable.
Abstract: Tank water from intact prey and extract of Echinoderms are practically non‐stimulatory to lobsters whereas extracts of molluscs crustaceans and fish are highly stimulatory. Extract of cod muscle prepared by freeze‐drying drip from thawing cod chunks is more effective in terms of concentration required to produce 50% response from lobsters than extracts prepared by homogenization or stirring of muscle tissue in sea water. Homogenized cod muscle extract and freeze‐dried material prepared from the latter (yield 8.8 %) elicit similar responses provided equivalent weights are used. Stirred cod, herring and flounder muscle extracts elicit similar responses at equivalent concentrations. The attractive substance in cod muscle is soluble in distilled water and in sea water and withstands boiling. It is dialysable. Preliminary tests with ion exchange resin columns indicate amphoteric and basic compounds are stimulatory, neutral acidic and volatile compounds are non‐stimulatory. The substance is soluble in ethyl alc...
60 citations
TL;DR: Elongation of a single axopodium after rapid contraction, when all other axopodia are of normal length, proceeds at the same rate as it does when all the axopadia are growing out after microtubule-breakdown induced by cold treatment; in both cases the rate of elongation decreases as axobodia increase in length.
58 citations
TL;DR: A very large dopamine-containing cell has recently been discovered in the left pedal ganglion of Planorbis corneus and experiments are described to locate it, to impale it with a microelectrode and to analyse post-synaptic responses in any follower cells.
Abstract: THERE is evidence that dopamine acts as a synaptic transmitter in the brain of gastropod molluscs, for example, it is localized in certain cell bodies and in terminal varicosities which are believed to be the areas of synaptic contact1–6. Many cells undergo a permeability change when exposed to low concentrations of dopamine7–11. Certain inhibitory potentials, elicited by stimulation of nerve trunks, appear to be mediated by dopamine by virtue of their response to dopamine antagonists and to drugs affecting dopamine levels in the brain8,9. As yet no effort has been made to impale an identified dopaminergic neurone and to study transmission at synaptic contacts made with other neurones. One reason for this may be that most of the dopamine-containing cells so far found in the molluscan brain have been small and unsuitable for electrophysiological studies. A very large dopamine-containing cell, however, has recently been discovered in the left pedal ganglion of Planorbis corneus by Marsden and Kerkut4 and we describe experiments to locate it, to impale it with a microelectrode and to analyse post-synaptic responses in any follower cells.
57 citations
TL;DR: In this article, the authors measured the helium singlet and triplet metastable densities by a line absorption technique in a 3 mm bore capillary tube over the pressure range 0.5-15 Torr and current range 10-200 mA.
Abstract: Helium singlet and triplet metastable densities have been measured by a line absorption technique in a 3 mm bore capillary tube over the pressure range 0.5-15 Torr and current range 10-200 mA. With constant discharge current the singlet and triplet densities show pronounced maxima of 2*1012 cm-3 and 9*1012 cm-3 respectively at about 2 Torr. At constant pressure the metastable densities saturate for currents above approximately 20 mA. Experimental values are in fair agreement with those calculated using known cross sections for production and loss mechanisms. The addition of cadmium vapour to simulate the conditions of laser oscillation at 4416 AA and 3250 AA in Cd II has two principal effects; cadmium vapour reduces the metastable populations-almost halving them when the optimum cadmium pressure for lasing is reached, and further the metastable densities now saturate at much higher currents (60-120 mAA). The observed optimum performance of the He-Cd laser with respect to discharge current, helium filling pressure and cadmium partial pressure is related directly to the behaviour of the helium metastable densities as these parameters are varied.
56 citations
TL;DR: Evidence is presented which suggests that dense-cored vesicles of mean diameter 100 nm were observed in the perikarya and the axon branches of the GSCs within the cerebral ganglia of Helix pomatia and Limax maximus and suggests that these vesicle sequester serotonin.
Abstract: There is a giant serotonin-containing neurone (GSC) in each cerebral ganglion of Helix pomatia and Limax maximus. In Helix, presynaptic endings of the GSCs are located in the buccal ganglia and peripheral musculature. Dense-cored vesicles of mean diameter 100 nm were observed in the perikarya and the axon branches of the GSCs within the cerebral ganglia. Evidence is presented which suggests that these vesicles sequester serotonin. Vesicles with a similar appearance are present in the presumed presynaptic endings of the GSC in Helix. These endings selectively accumulate tritiated serotonin. Axonal processes containing agranular vesicles (mean diameter 50 nm), or granular vesicles (50–100 nm diameter), or both, make close contact with the fine axon branches of the GSCs within the cerebral ganglion neuropile. Some of these axon processes appear to be presynaptic endings making synaptic connections with the GSCs.
TL;DR: It is suggested that the ribonucleoprotein particles isolated from homogenates of newt oocytes represent primary transcription units of polycistronic RNA, stabilized with protein and perhaps processed by the addition of poly(U) segments, which are released into the nucleoplasm.
TL;DR: Stable crystalline arsonium ylides have been prepared by thermal decomposition of diazo compounds in the presence of triphenylarsine, and by condensation reactions of reactive methylene compounds with triphenyarsine oxide as discussed by the authors.
TL;DR: DNA fibre autoradiography has been used to study the replication of chromosomal DNA from chicken cells in tissue culture at 37 °C, with results indicating that Tandemly arranged units replicate bi-directionally from fork-like growing points, the times of initiation of individual replicating sections being staggered.
Abstract: DNA fibre autoradiography has been used to study the replication of chromosomal DNA from chicken cells in tissue culture at 37 °C. The S -phase is estimated to be about 7.5 h. Replication proceeds in the manner first described by Huberman & Riggs. Tandemly arranged units replicate bi-directionally from fork-like growing points, the times of initiation of individual replicating sections being staggered. Evidence against the existence of defined termini is presented. The rate of replication in these chicken cells is some 25-30 µm/h one-way. The mean interval between adjacent initiation points for replication is 63 µm, with a range of some 25-145 µm. Although initiation intervals vary in length, neighbouring intervals tend to be similar in length.
TL;DR: The innervation of each of the muscles involved in mediating head movement in the desert locust Schistocerca gregaria is described in detail and it is concluded that the segmental nature of an insect muscle can not be deduced solely from a knowledge of the ganglion of origin of the motor innervation to that muscle.
Abstract: The innervation of each of the muscles involved in mediating head movement in the desert locust Schistocerca gregaria is described in detail. The number of motor neurones to each muscle and the neutral pathway and ganglion of origin of each are deduced from both histological and electrophysiological evidence. Only two of the muscles are, on histological evidence, innervated by as few as four different neurones, while several receive more than ten, and one at least 13. Individual muscles are shown physiologically to receive, in a few cases, as many as six different motor neurones. At least six muscles are innervated by motor neurones originating in more than one ganglion. One group of four muscles consisting in total of less than 100 muscle fibres receives more than 20 different motor neurones from three different ganglia through three or four different nerve roots. In these muscles, many single muscle fibres receive innervation from at least two different ganglia. It is concluded that the segmental nature of an insect muscle can not be deduced solely from a knowledge of the ganglion of origin of the motor innervation to that muscle. The innervation patterns that exist today must reflect past evolutionary development, but changes in the peripheral distribution of motor neurones, or migration of motor neurone cell bodies from one ganglion to another, or the development of additional motor neurones, or several of these factors together, must have formed a part of that development.
TL;DR: Schottky diodes consisting of a metal contact on n -type ZnSe emit light when biased in the forward direction if there is a layer of insulating or semi-insulating material between the metal and the semiconductor.
Abstract: Schottky diodes consisting of a metal contact on n -type ZnSe emit light when biased in the forward direction if there is a layer of insulating or semi-insulating material between the metal and the semiconductor. The electroluminescence spectrum is characteristic of luminescent centres in the ZnSe. There is a threshold voltage for electroluminescence which corresponds to the difference between the metal Fermi level and the top of the valence band of the semiconductor. For gold on ZnSe the threshold voltage is 1·3 V. Characteristics of the device differ from those of similar MIS systems because the oxide used here has appreciable conductivity.
TL;DR: In this article, the authors presented new systematic age data for four Nigerian subvolcanic granites which suggest that these Mesozoic intrusives can be used to verify the general northerly drift of Africa.
Abstract: THE concept of thermal plumes1,2 of deep mantle material, up to 150 km in diameter, rising through the mantle and burning through the lithosphere to form scar traces of chains of igneous activity on moving oceanic and continental crust3 is providing Earth scientists with a new method for estimating the direction of drift4. Igneous chains such as the Tertiary volcanic province of north-west Britain5, White Mountain Magma Series from New Hampshire6 and the Nigerian younger granites7 have all recently been attributed to scar traces produced by the passage of lithospheric plates over thermal plumes in the mantle3,4, although the geochronological evidence cited5 does not always justify such assumptions. Here we present new systematic age data for four Nigerian sub-volcanic granites which suggest that these Mesozoic intrusives can be used to verify the general northerly drift of Africa.
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TL;DR: Methyl oleate is converted in high yield to methyl 9(10)-methoxystearate by reaction with methanol in the presence of mercuric acetate followed by demercuration with sodium borohydride as discussed by the authors.
TL;DR: The results show that stimulation of the cutaneous cephalicus or the external peri-tentacular nerves causes a biphasic response in each GSC and that glutamic acid brings about a very similar response.
Abstract: IN each cerebral ganglion of the snail Helix pomatia there is a giant serotonin-containing neurone1,2. The serotonin within these giant serotonin cells (GSCs) probably serves a transmitter role3,4. Stimulation of most of the different nerve trunks entering the cerebral ganglia results in the appearance of cholinergic excitatory postsynaptic potentials (EPSPs) in these symmetrically placed neurones5. It has been found that electrical stimulation of the tentacle nerves can result in a wave of hyperpolarization and inhibition of the GSC as well as EPSPs6. Glutamate mimics the synaptic inhibition. We have reported here in more detail the effects of stimulating the different tentacle nerves, to observe the inhibitory process unaffected toy synaptic excitation, and the action of glutamic acid and related compounds on the membrane potential of the GSC. Our results show that stimulation of the cutaneous cephalicus or the external peri-tentacular nerves causes a biphasic response in each GSC and that glutamic acid brings about a very similar response. The initial phase of inhibition in both cases is mainly dependent on an increase in membrane permeability to chloride ions and that of the second phase mainly to an increase in membrane permeability to potassium ions. DL α-aminoadipic acid produces an effect which is superficially similar to the first phase of the glutamate response.
TL;DR: The ways of naming the comedian which happen to survive to us are Plautus, Macci Titi, Maccus, (M)accius, and T. Macci Plauti.
Abstract: The ways of naming the comedian which happen to survive to us are Plautus, Macci Titi, Maccus, (M)accius, and T. Macci Plauti; the best attested oi these names, Plautus, is twice adorned with curiously arch flourishes. The evidence as a whole presents two main problems: how do we interpret and reconcile Macci Titi, Maccus, and Maccius: and how do these names relate to the name Plautus? The purpose of this paper is to emphasize more strongly some known facts and relate them to a point not brought into the discussion before.
TL;DR: The Hermite polynomial approximation in which function values and the first few derivatives of a given function are matched at two points is given in an explicit form and an error term is deduced as discussed by the authors.
Abstract: The Hermite polynomial approximation in which function values and the first few derivatives of a given function are matched at two points is given in an explicit form and an error term is deduced. These results are extended to two dimensions.
TL;DR: In this article, the Lebesgue constants associated with interpolation at the extrema of Chebyshev polynomials were investigated, and it was shown that these constants are smaller than those associated with the zeros of the Chebyhev coefficients.
Abstract: The Lebesgue constants associated with interpolation at the extrema of the Chebyshev polynomials are investigated. It is shown that these constants are smaller than those associated with the zeros of the Chebyshev polynomials.
01 Aug 1973
TL;DR: Suction electrodes attached to tentacles of the sea anemone Calliactis parasitica record regular bursts of activity associated with the through‐conducting nerve net, suggesting that the activity originates from a pacemaker.
Abstract: Suction electrodes attached to tentacles of the sea anemone Calliactis parasitica record regular bursts of activity associated with the through‐conducting nerve net. Most bursts consist of 10–15 pulses at a frequency of 1 every 4 sec to 1 every 10 sec. The interval between bursts is usually 10–20 min. Regularity in pulse number and frequency in successive bursts suggests that the activity originates from a pacemaker. Bursts are always followed by slow contraction of endodermal longitudinal (parietal) muscles after a short delay, and endo‐dermal circular muscles after a long delay. A simple model for nervous pacemaker control of rhythmic contractions cannot be proposed as slow contractions can also occur in the absence of recorded nerve net activity.
TL;DR: A Ringer solution specific for this fish has been devised and tested and has proved a satisfactory physiological saline for use in electrophysiological experiments and in the preparative procedures for electron microscopy.
Abstract: Following analysis of the serum of the blood of the plaice (Pleuronectes platessa L.), a Ringer solution specific for this fish has been devised and tested. It has proved a satisfactory physiological saline for use in electrophysiological experiments and in the preparative procedures for electron microscopy.
TL;DR: A simple theory for electroluminescence by impact excitation is put forward and its extension to impact ionization is demonstrated in this paper, which gives a quantitative description of the processes involved and the performance of the diodes as light sources.
TL;DR: In this paper, a general technique for predicting the conditions of thermodynamic equilibrium in a solid/gaseous system has been applied to the systems In-As-P-Cl-H, Ga-As,P-C-H and Ga-In-As Cl-H. The theory takes account of the mixed dimers and tetramers of arsenic and phosphorus.
TL;DR: It is suggested that the neuroepithelial cell processes, both those distributed over the sensory region and those concentrated in the transitional region, are receptors.
Abstract: The fine structure of the osphradia of Buccinum undatum 1. three Hawaiian Conus spp., Nassarius reticulatus (L), Nucella lapillus (L) and Littorina littorea (L) was examined. There is a remarkable uniformity in the arrangement of ultrastructural cell types in all the ospharadia investigated. The marginal glandular region is characterised by a single layer of cells, bearing a regular pallisade of microvilli and including two types of mucous cell. The epithelium of the sensory region is several cells deep, and bears a complex layer of microvilli in many orientations. Besides indifferent cells it contains two types of cell bodies of ciliated nerve processes. One type ends at the surface of the sensory region. The other, containing an elaborate array of smooth membranes in the perikaryon, has a process which enters the transitional region between sensory and glandular areas. In the transitional region, specialised cells with motile cilia adjoin the glandular region, and similar, but unciliated cells, containing large pigment granules scattered throughout the cytoplasm, adjoin the sensory region. The distal surface of both cell types is dissected by elefts extending 2 to 3 μ proximally, then widening into extensive spaces which contain cytoplasmic processes. The ciliated neurites which enter the transitional region end in the spaces at the base of the unciliated transitional cell elefts. It is suggested that the neuroepithelial cell processes, both those distributed over the sensory region and those concentrated in the transitional region, are receptors.
TL;DR: For example, the authors argues that violence is the means of expression of men who lack any other, and is especially useful to the historian of an otherwise inarticulate working class, starving on die scraps which middle-class sources leave him.
Abstract: Violence is the means of expression of men who lack any other, and is especially useful to the historian of an otherwise inarticulate working class, starving on die scraps which middle-class sources leave him. Everyman is anonymous, but becomes memorable in rebellion; and in die many memorable rebellions of nineteenth-century Europe, that self-proclaimed ‘age of revolution’, historians have rejoiced that trie poor had found voice in violence.
TL;DR: Following exposure to tritiated 5-HTP, silver grains were observed over the perikarya of the GSCs (Giant serotonin cells) of Helix pomatia and other known serotonin-containing neurones in light and electron microscope autoradiograms.
Abstract: Following exposure to tritiated 5-HTP, silver grains were observed over the perikarya of the GSCs (Giant serotonin cells) of Helix pomatia and other known serotonin-containing neurones in light and electron microscope autoradiograms. There was no indication that the 5-HTP was taken up by nerve endings or by non-nervous structures. The distribution of radioactivity was completely different in autoradiograms of tissue exposed to tritiated serotonin. Silver grains, often in very high concentrations, were observed only over certain fine axon branches and processes thought to be nerve endings. Electron microscope autoradiography showed that these processes contained small dense-cored vesicles, morphologically identical to those thought to sequester serotonin in the perikarya of the GSCs. The accumulation of tritiated tryptophan was less specific; all the neurone perikarya showed an accumulation of radioactivity after exposure to this substance.