Showing papers by "University of St Andrews published in 1969"
TL;DR: In this article, the authors describe profitable methods for measuring lethal levels of pollutants for aquatic organisms, and advocate the use of standard toxicological methods and terminology and encourage the same principles to be applied in field work.
772 citations
TL;DR: Scanning electron microscopic study of tile pattern of ciliary coordination and the form of the ciliary beat is now possible and such stuidies have been made on the ciliate Opalina with this new technique.
Abstract: Scanning electron microscopic study of tile pattern of ciliary coordination and the form of the ciliary beat is now possible. Rapid fixation stops tile ciliary activity instantaneously, and critical point drying avoids distortion of the cilia by surface tension forces. Such stuidies have been made on the ciliate Opalina with this new technique.
209 citations
TL;DR: By fitting the measurements to a model, it is found that coupling between drone retinulas is stronger than in the locust but weaker than in Limulus, and the degree of coupling accounts satisfactorily for the difference in input resistance between Apis and Locusta cells.
152 citations
TL;DR: Comparison of the rates of cis-cyclopropane acid derivatives and cis-octadecenoic acid derivatives showed that the presence of π bonds in the acyl residue is not an important factor for the enzyme or enzymes transferring cis-acyl groups to the 1 position of acylglycerophospholipids.
111 citations
01 Jan 1969
100 citations
TL;DR: Results obtained previously showed that the basic polarized-light absorption ratio of single visual receptors in the crabCarcinus was typically about 9:1, and this is confirmed, and extended to the crayfishAstacus and crabOvalipes.
94 citations
TL;DR: Acyltransferase rates for the esterification of the naturally occurring 7-,9-,11-, and 13-octadecenoates to position 1 and 2 of diacyl-GPC indicated a preferred position for each acid which is in accord with that reported for the distribution of these monoenoic acids in phospholipids isolated from rat liver.
86 citations
01 Mar 1969-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: The dorsal part of the adult eye contains mainly uniform blue-sensitive receptors with peak near 380 nm in Anax and near 410 nm in Libellula, which is not a simple rhodopsin type of curve.
Abstract: The dorsal part of the adult eye contains mainly uniform blue-sensitive receptors with peak near 380 nm in Anax and near 410 nm in Libellula. This is not a simple rhodopsin type of curve.
2.
The larval eye and the ventral part of the adult eye contain receptors with a wide range of spectral sensitivity curves, with peaks from 420–520 nm in Anax and 450–550 nm in Libellula. Many of these can be derived from a typical rhodopsin curve when allowance is made for self-absorption in very long receptors.
3.
For most adult receptors, rotation of the plane of polarization by 90° from the optimum is equivalent to a decrease of only 60–70 % in intensity.
4.
The acceptance angle curve is approximately a Gaussian normal curve with width of 1.0–1.8° at linear half height. A few units have complex fields which may be artefacts.
5.
Retinula unit responses in larval compound eyes resemble those of the adult but the larval units are slower in response and usually more sensitive to rotation of the plane of polarization.
6.
There are eight retinula cells arranged in two tiers in each ommatidium.
7.
In the dark, pigment grains move away from the tip of the cone and the palisade around the rhabdom increases. These effects could increase the sensitivity by a change in the anatomy.
8.
In an eye of this type the ERG is an unsatisfactory tool, the angles of acceptance must be measured very carefully, and experiments with a single electrode have only a limited interpretation.
84 citations
TL;DR: The form and interrelationship of the collagen fibrils and proteinpolysaccharide complex of rabbit corneal stroma were studied by electron microscopy and appeared to lack some of the interfilament cross-links present in tendon.
Abstract: The form and interrelationship of the collagen fibrils and proteinpolysaccharide complex of rabbit corneal stroma were studied by electron microscopy. The intact tissue was examined as Araldite sections stained with alkaline lead citrate and uranyl acetate, and the mechanically disintegrated cornea after positive or negative staining with phosphotungstic acid or after treatment with 0.5% bismuth nitrate in 0.1 M nitric acid. The corneal collagen fibrils vary in cross-sectional area from 4.6 to 9.6 x 10 4 sq. A and do not exhibit a regular hexagonal distribution. Like tendon fibrils they consist of longitudinal filaments, but their appearance suggests that they lack some of the interfilament cross-links present in tendon. In sections of intact cornea and in negatively stained disintegrated cornea, filaments which are considered to be the protein cores of proteinpolysaccharide macromolecules are evident. They are about 40 A wide and 2000 A long. They appear to run an angular course, orthogonal to the collagen fibrils, and to be tangentially attached to several fibrils in the region of the a band. After treatment with bismuth nitrate disintegrated cornea contains coarsely beaded filaments. The filaments are about 2000 A long and the beads about 70 A in diameter. It is considered that these are again proteinpolysaccharide macromolecules and that each bead represents one or more polysaccharide chains in coiled configuration.
76 citations
75 citations
TL;DR: The pseudocone eye of Photuris has long corneal cones that are laminated in a series of concentric paraboloids which have the effect of bending rays towards the optical axis within the cone.
Abstract: 1. The pseudocone eye of Photuris has long corneal cones that are laminated in a series of concentric paraboloids which have the effect of bending rays towards the optical axis within the cone. 2. Between the proximal end of each cone and the receptor layer is a crystalline thread which conducts light by internal reflexion to the receptors. Not all light travels by this path in the dark-adapted eye. 3. The receptor layer has proximal and distal rhabdomeres in a pattern unlike that of any other known eye. The enormously developed rhabdoms form two superimposed continuous sheets across the eye. 4. The eighth retinula fibre in each bundle at the basement membrane comes from the basal retinula cell. 5. Off-axis light which escapes the route down the crystalline thread in the dark-adapted eye is refracted by the curved end of the cone in such a direction that it tends towards a receptor in the ommatidium which points towards the origin of the light. There is no functional superposition image at the level of the receptors.
TL;DR: It is suggested that the transparency of the cornea is the result of the close similarity of these two values rather than the arrangement of the collagen fibrils in a regular lattice.
TL;DR: In this article, it was shown that the DNA-containing axes of all lateral loops of lampbrush chromosomes continually engage in RNA synthesis while extended, and carry the associated RNP matrix along as they move towards the return insertions in the parent chromomeres, where loop axis retraction occurs.
Abstract: Actinomycin D inhibits RNA synthesis on the lateral loops of newt lampbrush chromsomes. Partial inhibition does not provoke marked morphological alteration of ordinary lateral loops, most of which recover to the full their capacity for RNA synthesis within 2 days of treatment. However, occasional ordinary loops do not recover completely within the first few days after treatment, and in such loops RNA-synthesizing capacity is restricted to a region adjoining the thinner insertion in the parent chromomere. A greater degree of inhibition of RNA synthesis is accompanied by loss of matrix from ordinary lateral loops, and in the extreme case the loop axes retract to their parent chromomeres and neighbouring chromomeres coalesce; for the ordinary loops, full recovery from this stripped condition is nevertheless possible. Some 20 µ per loop extends during the first day following exposure to actinomycin, and normal morphology and RNA-synthesizing capacity are regained within 2-4 days. The giant granular loop of Triturus cristatus cristatus chromosome XII responds to extreme actinomycin D poisoning in different fashion. Matrix does not at once slough off its loop axis, but the loop present at the time of treatment is progressively replaced by a new granular loop which develops between the parent chromomere and the original loop9s dense tip. These observations support the theory that the DNA-containing axes of all lateral loops of lampbrush chromosomes continually extend from their parent chromomeres, engage in RNA synthesis while extended, and carry the associated RNP matrix along as they move towards the return insertions in the parent chromomeres, where loop axis retraction occurs.
TL;DR: The electrical properties of the nerves and roots suggest that the fast muscles are innervated by a single class of fast axons and possibly by a few slow axons, and polyneuronal innervation of the muscle fibres by 8-22 different axons in the absence of multiterminal innervation is postulated.
Abstract: 1. Histological and electrophysiological studies of the spinal nerves, nerve roots and muscles of the abdominal wall of the marine teleost Cottus scorpius have been undertaken to determine the extent and nature of polyneuronal innervation of the fast muscles.
2. Spinal nerves at proximal and distal levels, and the dorsal roots, contain axons in a single mixed population with a mean diameter of 2-4 µm., while the ventral roots contain axons in two diameter classes with means at 4-6 and 12-14 µm.
3. Between 8 and 22 distributed nerve terminations were counted on fifty-two teased intact single muscle fibres stained for acetylcholinesterase activity. The average distance between the terminals is 0.64 mm. (range 0.094-2.050 mm.).
4. The compound action potential of the nerve comprises two principal peaks with conduction velocities of 17.0-23.8 m./sec. and 1.5-12.2 m./sec. at 10-12° C.
5. Fast muscle fibres gave two types of electrical response--all-or-none spike potentials that are propagated with a conduction velocity of c . I.I m.7/sec. at 10-120° C., and quantized distributed junction potentials.
6. The electrical properties of the nerves and roots suggest that the fast muscles are innervated by a single class of fast axons and possibly by a few slow axons.
7. Simultaneous recordings of nerve and muscle activities were made at different stimulus intensities. In all cases muscle responses were correlated with the first peak of the compound action potential, and appeared with the same or only slightly different latencies.
8. Each muscle fibre is shown electrophysiologically to be polyneuronally innervated by 2-5 axons from a single spinal nerve, and to receive a similar axonic complement from each of four spinal nerves.
9. Polyneuronal innervation of the muscle fibres by 8-22 different axons in the absence of multiterminal innervation is postulated.
TL;DR: Results are presented that expand those of Hagiwara and Morita on the mechanoreceptor cells of the body wall, and the interneurones of the cord, especially when stimulated via photoreceptors.
Abstract: The central nervous system of leeches has received less attention than that of the other annelid classes, the Oligochaeta and the Polychaeta. Knowledge of the morphology of the group has advanced little since the review of Scriban & Autrum (1934), though Hagadorn (1958) has added some details in dealing with the neurosecretory properties of the leeches. Physiological studies have been almost entirely confined to the giant cells of Retzius (Hagiwara & Morita, 1962; Eckert, 1963; Kerkut, Seddon & Walker, 1966) but a little is now known of other cells of the ventral cord (Baylor Nicholls & Stuart, 1966; Bianchi, 1967). The connexions and pathways of these cells with others in the nervous system have not been demonstrated. The properties of sensory cells in the leech are almost unknown. Walther (1966) has presented some details of the photoreceptor cells of the anterior regions, and Bullock & Horridge (1965) quote some observations made by Hagiwara and Morita. The only information available on interneurones in the Hirudinea is contained in this work. Hagiwara (personal communication) has indicated that these studies are no longer in progress. Wilson (i960) has shown that the segmental nerves carry motor neurones. The fine structure of the nerve cords, and of the nerve cell somata, has received excellent treatment from Gray & Guillery (1963), Coggeshall & Fawcett (1964) and Coggeshall (1966), and consequently there is a wealth of information on synapses, fibre diameters, cellular inclusions and sheath structure. Some of the physiological properties of the glial cells have been examined by Kuffler & Potter (1964) and Kuffler (1967). The present paper presents results that expand those of Hagiwara and Morita on the mechanoreceptors of the body wall, and the interneurones of the cord, especially when stimulated via photoreceptors. MATERIALS AND METHODS
TL;DR: In this article, a description of an explosion crater area in the eastern Rift Valley of Northern Tanzania is given, which includes maar-type explosion craters, tuff rings and tuff cones, the location of which is controlled by minor faults on the floor of the Rift Valley.
Abstract: A description is given of an explosion crater area in the eastern Rift Valley of Northern Tanzania. The features comprise maar-type explosion craters, tuff rings and tuff cones, the location of which is controlled by minor faults on the floor of the Rift Valley. In some tuff rings and cones biotite and pyroxene are common, and olivine-biotite pyroxenite is common amongst the ejected blocks. Other blocks are of ijolitic types and spinel harzburgite. The associated lavas are olivine nephelinites and olivine melilitites, which are the sodic analogues of the katungite and ugandite found in the explosion crater area in the western Rift Valley in South-West Uganda.
TL;DR: Onithochiton neglectus a common littoral chiton possesses large numbers of small eyes embedded in the outer layer of the shell, the tegmentum, which it is thought that the lamellate bodies are also sensory.
Abstract: Onithochiton neglectus a common littoral chiton possesses large numbers of small eyes embedded in the outer layer of the shell, the tegmentum. These are arranged in a definite pattern on each shell valve. Each eye lies in a pocket, and is surrounded by pigment laid down in the shell. There is a lens, cup of retina cells and an optic nerve running in an optic canal through the shell. Glial elements are present. The retina cells give rise centrally to a packed array of microvilli, a rhabdom. Cilia are present at the edge of the rhabdom; they have a 9 + 2 arrangement of ciliary filaments and do not appear to be involved in the formation of microvilli. Cells at the periphery of the eye cup give rise to large whorls of membranes, lamellate bodies. These bodies are derived from the membranes of cilia having a 9 + 2 pattern, and form into an extra-cellular space. Nerve processes from the retina cells pass into the optic canal. On the basis of previous work it is thought that the lamellate bodies are also sensory. These structures are discussed in relation to other microvillar and lamellate structures described from photoreceptors.
TL;DR: A dense network of nerve fibres is described in the auriculoventricular junction of the Helix pomatia heart and the results of both light and electron microscope analyses suggest that the system has a neurosecretory function.
TL;DR: In this paper, Raman scattering of the transverse and longitudinal optical frequencies for indium phosphide has been used to determine the high frequency dielectric constant, and this has been combined with the optical frequencies to give the low frequency DIC, the Callen and Szigeti effective charges and the carrier mobilities.
TL;DR: Despite several lines of indirect evidence, there has hitherto been little unambiguous evidence of a volatile bearing phase in the upper mantle of the Earth's upper mantle as mentioned in this paper, although Mica has been found as a primary phase in several specimens of peridotite and one specimen of garnet lherzolite from the Lashaine volcano, northern Tanzania.
Abstract: Despite several lines of indirect evidence, there has hitherto been little unambiguous evidence of a volatile bearing phase in the upper mantle. Mica has been found as a primary phase in several specimens of peridotite and one specimen of garnet lherzolite from the Lashaine volcano, northern Tanzania.
TL;DR: During the summers of 1967 and 1968, the bacterium, Aeromonas liquefaciens, was involved in disease of Atlantic salmon and suckers in the Miramichi River, New Brunswick, and recurred during the summer of 1968.
Abstract: During the summers of 1967 and 1968, the bacterium, Aeromonas liquefaciens, was involved in disease of Atlantic salmon (Salmo salar) and suckers (Catostomus commersoni) in the Miramichi River, New Brunswick. A surge of copper and zinc pollution in late June 1967, and high river temperatures enhanced production of an epizootic. The epizootic recurred during the summer of 1968.
TL;DR: The current approach in numerical taxonomy is directed towards the so-called “minimum-variance” solution, for which it is argued that a population should be partitioned into cluster subsets by minimizing the total within group variation.
Abstract: THE current approach in numerical taxonomy is directed towards the so-called “minimum-variance” solution, for which it is argued that a population should be partitioned into cluster subsets by minimizing the total within group variation. Several classification methods have been compared1 and shown to possess related variance constraints, and a case has been made1–3 for suggesting that such methods are not ideally suited to the taxonomic problem of resolving “natural” classes. Implicit in the minimum variance approach is the concept that cluster should have no significant overall variance or spread, and this implies that in the case of a unimodal swarm the distribution should be split into an arbitrary number of compact sections. By contrast, Forgey has argued2,3 that for a “natural” classification, clusters should correspond to data modes, and there can only be as many classes as there are distinct modes. No variance constraint is implied, or should be induced, for when a mode is elongated rather than spherical the distribution merely reflects some internal factor of variation for the corresponding class. Such factors will be present to some extent, depending on data transformations and the quality of the selected character set, and therefore a subsequent variable search is necessary to discover the hidden constant characteristics of the class. Furthermore, those characters which are non-constant for a cluster mode may be inter-correlated, suggesting that the original character choice was poor, and in such cases the consideration of correlations, ratio variables and regression coefficients is indicated. Forgey interprets2,3 a data mode as a continuous dense swarm of points, separated from other such modes by either empty space or a scattering of “noise” data. It has been suggested that “noise” data usually result from sampling errors, and while this is true, they can also be interpreted as those natural phenomena associated with the intersecting tails of disjoint continuous distributions. We can therefore expect a “natural” cluster to exhibit a dense centre (of any shape) which is surrounded by a haze or cloud of points, and the problem is to isolate the dense centres irrespective of this interference.
TL;DR: The extent to which light can escape from one ommatidium into its neighbors in the compound eye has been examined by recording from single receptors during stimulation of single facets.
Abstract: The extent to which light can escape from one ommatidium into its neighbors in the compound eye has been examined by recording from single receptors during stimulation of single facets. In the "apposition" eye of the drone honeybee and locust, optical interaction is extremely small. In the "superposition" eye of the crayfish, more than half the light captured by the average cell gets in through neighboring facets, even when screening pigments are in the fully lightadapted position.
TL;DR: Electron microscopy of the aesthetes of several American species has failed to reveal any structures recognizable as typical of photoreceptors, and it is assumed that these shell organelles function as light receptors.
Abstract: IT has long been known that certain chitons (Mollusca, Polyplacophora) possess eyes or ocelli1. These ocelli occupy a unique position, being set dorsally in the outer most layer of the shell. No eyes from the soft parts of adult animals have yet been described2. Light microscope investigations distinguished several types of organelles within the shell. These are basically the aesthete3, the intrapigmental ocellus4, and the extrapigmental ocellus1,5. All chitons yet examined seem to possess one or more of these types. Several chitons have been shown to respond to light stimuli6–8 and it is assumed that these shell organelles function as light receptors6,7,9. Electron microscopy of the aesthetes of several American species10,11 has failed to reveal any structures recognizable as typical of photoreceptors.
TL;DR: Measurements of Na and K concentrations in yolky and clear cytoplasm show that both fractions have the same K content and the concentration of K decreases in both fractions as the oocyte grows.
Abstract: Newt oocytes were dissected under liquid paraffin and known volumes of clean nucleoplasm and cytoplasm were obtained from oocytes in different stages of oogenesis. The samples were digested in redistilled nitric acid, diluted with deionized water, and their Na and K contents were measured by flame spectrophotometry. The results were expressed as micro-equivalents of Na and K per millilitre of nucleoplasm or cytoplasm. In oocytes of 0.3-0.5 mm diameter nucleoplasm and cytoplasm have similar Na and K concentrations, and the molar K:Na ratio is about 3:1. As the oocyte grows to maturity the nucleoplasmic Na and K concentrations do not change, but the cytoplasmic K concentration falls steadily until, in nearly mature oocytes, the cytoplasmic K:Na ratio is near 1:1. Measurements of Na and K concentrations in yolky and clear cytoplasm show that both fractions have the same K content and the concentration of K decreases in both fractions as the oocyte grows. The significance of these results is discussed in terms of the possible effects of changes in the intracellular ion balance on the morphology and synthetic activity of the chromosomes.
TL;DR: Experiments in which the eyes view different visual stimuli reveal that, at the start of a response, the eyecups have a considerable degree of independence and can even move in opposite directions.
Abstract: 1. The movements of the two eyecups of the crab, Carcinus , have been recorded simultaneously during optokinetic responses. 2. Experiments in which the eyes view different visual stimuli reveal that, at the start of a response, the eyecups have a considerable degree of independence and can even move in opposite directions. As the response progresses, interaction between the eyes increases, until the eyecups move at similar velocities in the direction of the slower of the two visual inputs, or are stationary. 3. Similar interactions between the eyes were observed during memory responses and during the responses to sinusoidal oscillation of the two sets of stripes. Each eye has its own system for converting perceived motion into eyecup movement. These two systems are linked on the afferent rather than the efferent side of the brain. 5. The fast phase of optokinetic nystagmus is governed by the eye whose fast-phase movement occurs away from the midline, and the fast phases of this eyecup lead the other by 30-80 msec. Also, fast phases only occur at their normal frequency when the governing eye can see the stripes.
TL;DR: One of the major paired nerves in the decapod stomatogastric nervous system innervates the posterior part of the gastric mill and is redescribed for Homarus vulgaris, and less detailed information is given for Palinurus vulgaris and Cancer pagurus.
Abstract: One of the major paired nerves in the decapod stomatogastric nervous system innervates the posterior part of the gastric mill. The morphology has been completely described previously only in Pugettia producta. This nerve is called the posterior stomach nerve (p.s.n.) in this paper. It is redescribed for Homarus vulgaris, and less detailed information is given for Palinurus vulgaris and Cancer pagurus. In these three species the p.s.n. contains numerous cell bodies. The majority of the cells are in one group and the long distal processes of these cells form a large proportion of the fibres in the nerve which runs to the gastric mill. Many of these fibres terminate by ramifying in the connective tissue which invests the ossicles of the gastric mill. The Brachyuran C. pagurus was used for most of the physiological experiments reported here. Only a small percentage of the animals exhibited spontaneous movements of the gastric mill when the carapace was removed and this activity ceased rapidly. However, a cycle of movements was usually observed in the active gastric mills and the p.s.n. contains many elements which respond to these normal movements. The p.s.n. does not appear to contain motor fibres. Intracellular recordings show that cells in the p.s.n. are proprioceptors. The distal processes of the major group of cells are morphologically dendrites, but they probably support action potentials. Repetitive electrical stimulation of a p.s.n. when it is isolated from the gastric mill evokes changes in the output from the stomatogastric ganglion. The p.s.n. sensory system could therefore function in the normal reflex control of the activity of the gastric mill. This investigation may assist in the analysis of the functions of the stomatogastric ganglion.
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TL;DR: This paper pointed out that the Pindaric use is practically limited to statements of the type, ‘I shall sing, glorify, testify, etc.’ and pointed out the conventional nature of these futures and so ended years of misunderstanding.
Abstract: J. Wackernagel and E. Lofstedt have both drawn attention to Pindar's ‘Neigung, das Futurum zu setzen bei Verben, die eine jetzt vorhandene, aber auf zukunftiges Tun abzielende Willensrichtung ausdrucken’. But they regarded this as a purely grammatical phenomenon, and did not note that the Pindaric use is practically limited to statements of the type, ‘I shall sing, glorify, testify, etc.’. It was E. Bundy who first drew attention to the conventional nature of these futures and so ended years of misunderstanding. So, for example, Wilamowitz considered that P. 1.75 represented an optative with while Slotty, following Breyer, thought that N. 9. 10 was an aorist subjunctive ‘auf Grund des pindarischen Sprachgebrauches’! Postgate, following Gildersleeve, thought that 0. 8. 57 represented though the contrary would appear to be more true, cf. 0. 13. 11: and also Hoekstra sees in the future ‘den Nebenbegriff des Konnens’.
TL;DR: Some experimental results can be interpreted as an indication that permeability changes of nerve membranes are mediated by migration of hydrogen ions.
Abstract: Some experimental results can be interpreted as an indication that permeability changes of nerve membranes are mediated by migration of hydrogen ions.