Showing papers by "University of Aberdeen published in 1970"

The effects of adrenaline, noradrenaline and isoprenaline on inhibitory α- and β-adrenoceptors in the longitudinal muscle of the guinea-pig ileum

Abstract: 1. Two preparations, a segment of the ileum and the myenteric plexuslongitudinal muscle preparation, have been used for an analysis of the inhibitory effects of adrenaline, noradrenaline and isoprenaline on the contractor responses of the longitudinal muscle to acetylcholine or to electrical, coaxial or field, stimulation.2. Since the inhibitory effects of adrenaline, noradrenaline and isoprenaline on the acetylcholine-induced contractions were not affected by phenoxybenzamine but were antagonized by propranolol, it is concluded that beta-adrenoceptors are present on the muscle cells.3. The responses to electrical stimulation were suppressed by adrenaline or noradrenaline but only partly inhibited by isoprenaline. Propranolol antagonized the effect of isoprenaline and, to some extent, that of noradrenaline, but scarcely affected the action of adrenaline. Phenoxybenzamine, on the other hand, antagonized most of the effect of adrenaline and, to some extent, that of noradrenaline; it usually potentiated the effect of isoprenaline.4. The output of acetylcholine evoked by electrical stimulation was diminished by adrenaline or noradrenaline but was not affected by isoprenaline. The depressant effect on acetylcholine release was antagonized by phenoxybenzamine but not affected by propranolol; therefore these effects of adrenaline and noradrenaline are mediated by alpha-adrenoceptors.5. It may be assumed that alpha-adrenoceptors in situ are stimulated mainly by circulating adrenaline and possibly noradrenaline and thus cause a prejunctional inhibition at the nerve-smooth muscle junction.

Life history of the Mountain hare (Lepus timidus scoticus) in north‐east Scotland

Abstract: A general description of the life history of Mountain hares is given, base on a three year field study of about 200 wild hares on a moor near Morven, Aberdeenshire, and laboratory examination of over 360 dead specimens from surrounding areas. Growth and body size, behaviour, range and movements, food and reingestion are described. More detailed information on reproduction, mortality and population counts are presented to give an outline of the population dynamics in this species.

Specificity of cycloheximide in higher plant systems.

Abstract: Although cycloheximide is extremely inhibitory to protein synthesis in vivo in higher plants, the reported insensitivity of some plant ribosomes suggests that it may not invariably act at the ribosomal level. This suggestion is reinforced by results obtained with red beet storage tissue disks, the respiration of which is stimulated by cycloheximide at 1 microgram per milliliter. Inorganic ion uptake by these disks is inhibited by cycloheximide at 1 microgram per milliliter while the uptake of organic compounds, by comparison, is unaffected. Ion uptake by all nongreen tissues tested is inhibited by cycloheximide, but leaf tissue is unaffected, indicating that the ion absorption mechanism in the leaf may differ fundamentally from that in the root. It is concluded that cycloheximide can affect cellular metabolism other than by inhibiting protein synthesis and that the inhibition of ion uptake may be due to disruption of the energy supply.

Pure-Cone Retinae and Retinomotor Responses in Larval Teleosts

Abstract: A pure-cone retina has been reported in the larval stages of teleosts from three families, viz. the salmon Oncorhynchus spp. by Ali (1959), the herring Clupea harengus by Blaxter & Jones (1967) and plaice Pleuronectes platessa by Blaxter (1968 a). There is also an absence of any retinomotor responses (movement of retinal masking pigment and changes in the relative positions of the visual cells) until the rods develop, which is usually at metamorphosis where this is clear-cut. Most adult teleosts are known to have a duplex retina.

Non‐specificity of symbotic infection in orchid mycorrhiza

Abstract: Summary Symbiosis tests carried out between orchids from several geographical localities and thirty-two Rhizoctonias isolated from orchids, non-orchid hosts and soils of worldwide distribution, showed no evidence of any species-to-species relationship between orchid and fungus. Dactylorhiza purpurella established a symbiotic relationship with most fungi tested while Coeloglossum wide, Goodyera repens and Cymbidium canaliculatum, although less frequently symbiotic, established compatible infections with many isolates. Among orchids with photo-synthetic protocorms, Epidendrum radicans was compatible with several fungi but three other species of Epidendrum together with Spathoglottis plicata and a Laeliocattleya cultivar were symbiotic only with Tulasnella calospora and certain Ceratobasidium isolates. Tulasnella calospora may be a universal orchid symbiont. Ceratobasidium cornigerum and Thanatephorus orchidicola commonly occur as root endophytes but are doubtfully symbiotic with most orchids. T. cucumeris is frequently symbiotic with Dactylorhiza purpurella but less commonly so with other orchids tested.

Localisation of reiterated nucleotide sequences in Drosophila and mouse by in situ hybridisation of complementary RNA.

Abstract: The location of highly reiterated nucleotide sequences on the chromosomes has been studied by the technique of in situ hybridisation between the DNA of either Drosophila melanogaster salivary gland chromosomes or mouse chromosomes and tritium labelled complementary RNA (c-RNA) transcribed in vitro from appropriate templates with the aid of DNA dependent RNA polymerase extracted from Micrococcus lysodeikticus. The location of the hybrid material was identified by autoradiography after RNase treatment. — When Drosophila c-RNA, transcribed from whole DNA, was annealed with homologous salivary chromosomes in the presence of formamide the well defined labelling was confined to the chromocentre. With heat instead of formamide denaturation there was evidence of discontinuous labelling in various chromosome regions as well, apparently associated with banding. Xenopus ribosomal RNA showed no evidence of annealing to Drosophila chromosomes with the comparatively short exposure times used here. — When mouse satellite DNA was used as template the resulting c-RNA showed no hybridisation to Drosophila chromosomes but, when annealed with mouse chromosomes, the centromeric regions were intensely labelled. The interphase nuclei showed several distinct regions of high activity which suggested aggregation of centromeric regions of both homologous and non-homologous chromosomes. The results of annealing either c-RNA or labelled satellite DNA to homologous chromosomes were virtually indistinguishable. Incubation of Drosophila c-RNA with mouse chromosomes provided no evidence of localisation of grains. — It is inferred that both in mouse and Drosophila the centromeric regions of all chromosomes are enriched in highly reiterated sequences. This may be a general phenomenon and it might be tentatively suggested that the highly reiterated sequences play some role in promoting the close physical approximation of homologous and non-homologous chromosomes or chromosome regions to facilitate regulation of function.

Epibenthic algal production in an intertidal mudflat

Abstract: Epibenthic algal production in an estuarine mudflat was measured during 1968 by a 14C method. Seasonal production was correlated with solar radiation, temperature, and standing crop of functional chlorophyll, but not with the amount of organic carbon. Standing crop of living plant material in the sediments was equivalent to 15% of organic carbon in summer and 10% in winter. Annual production (31 g C/m2) was equivalent to about a third of mean organic carbon in the sediments.

13C frequency shifts and the general harmonic force fields of methyl chloride, bromide and iodide

Abstract: General harmonic and hybrid orbital force fields have been calculated for methyl chloride, bromide and iodide using the best available frequency, Coriolis coefficient, and centrifugal distortion data, including the recent 13C frequencies for the chloride and iodide. Anharmonicity corrections were made to the fundamental frequencies using Dennison's rule and x values of 0·04 for CH stretching, 0·02 for CH bending, and 0·01 for CX stretching modes. These were the most reasonable values which did not seriously over-compensate for the product rule deficiencies in the 12C and 13C frequencies. The 13C and CD3X frequency information was input in the form of frequency shifts from the 12CH3X frequencies. All 12 parameters in the most general harmonic force fields are determined with significance for the first time, although the previously uncertain parameters F12 and F13 are only determined with good precision when the 13C frequency data are utilized in addition to the other information. The signs of F12, F45 and ...

Some Aspects of Water Relations

Abstract: Publisher Summary This chapter focuses on some aspects of water relations. In past years, the basic concepts of cell-water relations, osmotic pressure, suction force, diffusion pressure deficit, and turgor pressure have been critically examined from a thermodynamic standpoint. The state of water in the cell is best expressed in terms of free energy. If a cell is at equilibrium with its surroundings, all its various parts—cell wall, cytoplasm organelles, and vacuole—are at the same water potential. In the vacuole, the lowering of water potential results almost entirely from solutes, while in the cell wall it results from surface tension and adsorptive forces that make up the matric potential. There are two pathways available for water movement through tissues, such as the root cortex or the leaf mesophyll. Water can pass from vacuole to vacuole by osmosis across the cell membranes in response to a gradient in water potential, or it can flow along the cell walls in response to gradients of hydrostatic tension in the intermicellar spaces of the walls. This picture of water movement through the root is supported by considerations of the velocity of water movement across the cortex in relation to the permeability of the cells.

Thiol and disulphide contents of hen ovalbumin. C-Terminal sequence and location of disulphide bond

Abstract: 1. The thiol and disulphide contents of hen ovalbumin were investigated by p-chloromercuribenzoate titration, by determination of cysteic acid content after performic acid oxidation, by measurement of uptake of radioactive iodoacetic acid, and by assay of S-aminoethylcysteine after reaction with ethyleneimine. All results showed that ovalbumin had 6 half-cystine residues. Experiments with and without reducing agents demonstrated that there were 4 thiol groups and 1 disulphide bond. 2. A peptide containing equimolar amounts of S-carboxymethyl-cysteine, serine, valine and proline, but no lysine or arginine, was obtained by radioactive labelling of the cysteine residues with iodo[(14)C]acetic acid followed by electrophoretic and chromatographic separation of tryptic digests. It was concluded that the C-terminal sequence of ovalbumin is -Cys-Val-Ser-Pro. 3. The location of the disulphide bond was studied by using a double-labelling technique. It was shown that one end of the disulphide was located in this C-terminal peptide.

The morphology of vegetative regeneration in calluna vulgaris

Abstract: Summary Calluna vulgaris, in certain habitats, provides useful grazing for herbivores; management is generally by burning, with the aim of promoting vigorous production of young shoots by vegetative regeneration for the stem base. However, the capacity for such vegetative regeneration declines with age. The general morphology of the plant is described, with particular reference to the sequence of development in a single season's growth and to the stages in resumption of growth after overwintering. On this basis, an interpretation is given of the responses to grazing and burning, with evidence derived from detailed observation of treated plants and from transverse sections of stems. Light grazing at the periphery of the plant causes (i) the growth of a few of the uppermost short shoots into new long shoots, and (ii) the appearance of clusters of shoots from lower, woody, parts of the branches. Heavier or more sustained grazing emphasizes the second of these responses. Vegetative regeneration after burning is also of the second category, confined to undamaged positions near the base of the stem. The clusters of shoots appear at the points of origin of existing or former branches. The conclusion, derived both from morphological observations and from evidence of the deep-seated origin of these new shoots, is that they are derived from persisting dormant buds on the close-packed nodes just below the base of each long shoot. These nodes belonged to the overwintering end-of-season short shoot from which the long shoot developed.

Mortality among psychiatric patients.

Abstract: A 5-year follow-up study was carried out of all referrals to the psychiatric services in a Regional Board area. The death registers of the Registrar General for Scotland were searched for all patie...

Permeability and structure of the wood of Sitka spruce

Abstract: directions has been measured at various mean pressures between 1 and 700 mmHg. From these measurements it has been shown that both the tracheid lumina and the pores in the membranes of the bordered pits make significant contributions to the total resistance tolongitudinal fluid flow through the wood, and the number and equivalent radii of the conducting tracheid lumina and the pit membrane pores have been derived. The conducting tracheids have been observed directly by examination of transverse wood sections, after staining the flow-paths with reduced basic fuchsin solution. The conducting tracheids were found mainly in the latewood and their radii and number were in agreement with the values derived from permeability measurements. Direct carbon replicas of bordered pit membranes have been examined in the electron microscope. Unaspirated, i.e. conducting bordered pits were found only in the latewood region and the size and number of the pores in the latewood pit membranes were in agreement with values derived from permeability measurements, which predicted about 250 pit membrane pores of radius 0.14 ,um in series with each conducting tracheid lumen. The effect of a possible distribution of pore size on the results is considered, and the significance of this work in relation to previous work on the gaseous permeability of conifer wood is discussed.

The effects of particle size on the absorption of phenacetin in man

Abstract: In separate experiments 6 volunteers received 1.5 Gm. of phenacetin (acetophenetidin) as a fine suspension (particle size less than 75/1,) with and without Tween 80 (polysorbate 80), a medium suspension (particle size 150 to 180IL), and a coarse suspension (particle size greate:\" than 250IL). They also received four tablets of two proprietary brands of phenacetincontaining analgesics. The absorption of drug from these different preparations was assessed by estimation of the plasma concentrations of phenacetin and its ma;or metabolite, N-acetylp-amillophenol (APAP, acetaminophen, paracetamol), at intervals and by measuring the urinary excretion of free and con;ugated AP AP. The highest levels of both phenacetin and free AP AP were observed after the fine suspension of phenacetin with Tween 80, followed in decreasing order by the fine without Tween 80, medium and coarse. The mean maximum plasma concentration of phenacetin ranged from 13.5 ILg per milliliter for the fine suspension with Tween 80 to 1.4 ILg per milliliter for the coarse suspension. Differences in the plasma levels of APAP and the urinary excretion of APAP were less marked. Particle size is an important factor in the absorption of phenacetin, and absorption is apparently enhanced by Tween 80.

The effects of drying on the structure and permeability of the wood of Abies grandis.

Abstract: The effects of air-drying and solvent-drying on the sapwood of Abies grandis have been investigated by a new method for the determination of the size and number of conducting tracheid lumina and pit membrane pores which involves the measurement of gaseous permeability at various mean pressures. Both earlywood and latewood tracheids (83% of the total) were found to be conducting in solvent-dried wood, but in air-dried wood only latewood tracheids (32% of the total) were conducting. In solvent-dried wood there were on average 27,000 pit membrane pores per conducting tracheid compared with only 600 in air-dried wood. In both, the average pit membrane pore radius was about 0.1 μm.

Crystallisation of lithium zinc silicates

Abstract: Phase relations on the Li4SiO4-Zn2SiO4 join of the Li2O-ZnO-SiO2 system have been studied. Extensive ranges of solid solutions form, and many of these have structures which are related to those of Li3PO4; the mechanism of lithium ⇌ zinc replacement is discussed. Ten binary phases have been found; seven probably occur at equilibrium. In addition, the high-temperature polymorphism of Li4SiO4 has been studied. Physical data are presented to characterise the thermodynamically stable phases, and their stability relations depicted on a temperature-composition equilibrium diagram.

The evaluation of a device for feeding group-housed animals individually†

Abstract: A system which allows group-housed animals to feed individually is described. In this systm animals have sole access to their individual feeding point and this access is unlimited in duration and frequency. The food intake and performance of growing Friesian castrated male calves housed and fed by two arrangemente of this feeding device have been compared with cattle that were group-housed and group-fed, and cattle individually penned. A4 × 4 latin square design was used.No significant treatment differences were detected and the feeding device did not appear to affect the food intake, performance or behaviour of the cattle.

Hudson's Pictures in Pandora's Box

Abstract: Highly sophisticated Europeans and unsophisticated Zambians responded to two of Hudson's Pictorial Perception Test stimuli displayed in "Pandora's Box. " Neither the application of Hudson's nor of "Pandora's Box" procedure yielded evidence of depth perception in the case of the Zambian samples. The European sample responding to the "Pandora's Box" procedure did perceive depth in the stimulus containing both overlap and familiar size cues, and failed to do so in response to the stimulus containing familiar size cues only. The hypothesis that the two populations will not differ on the task and will both fail to perceive depth as measured by "Pandora's Box" was therefore rejected, as was the hypothesis that the reduction of background cues occurring in the box would lead to an increase in the number of 3-D responses.

Further similarities between chloroplast and bacterial ribosomes.

Abstract: Protein synthesis by chloroplasts isolated under aseptic conditions from Phaseolus vulgaris leaves is inhibited by the bacterial antibiotics spectinomycin, lincomycin, and erythromycin; that by chloroplasts from Nicotiana tabacum leaves is inhibited by spectinomycin and lincomycin but not by erythromycin. Protein synthesis by cytoplasmic ribosomes from plants and animals is not inhibited by these compounds, nor is amino acid activation by the soluble fraction from bean chloroplasts. These results suggest that chloroplast ribosomes possess sites which bind several unrelated bacterial antibiotics and support the idea that chloroplasts originated from prokaryotic cells. These antibiotics may be useful in studying the process of chloroplast formation in intact cells.

The life cycle of Basilia hispida Theodor 1967 (Diptera: Nycteribiidae) in Malaysia*

Abstract: Basilia hispida is the only insect parasite of the flat-headed bats Tylonycteris pachypus and T. robustula in Selangor, Malaysia where this study was conducted between September 1966 and August 1968. The climatic conditions in the laboratory closely approximated to those in the field: seasonal variations in climate were small but diurnal fluctuations occurred. The life cycle of the fly was not affected either by the season or by the sex or species of the host.A typical life cycle was as follows: adult B. hispida reached sexual maturity within 5 or 6 days of their emergence from the puparium. Copulation largely occurred with newly emerged flies or with females at the time of prepupal deposition; one copulation sufficed for numerous subsequent offspring. The entire larval life of three instars was passed within the female, nourished by maternal secretions. After reaching maturity the female deposited prepupae at 9-day-intervals on the host's roosting quarters, deposition occurring during the day, stimulated by increasing temperature. The length of the pupal stadium depended upon the presence of a host bat; if one was present the pupal period was ca. 25 days. Thus the total life cycle from emergence of the female to the emergence of her first offspring was typically 39 (5 + 9 + 25) days. The sexes were produced in equal numbers. The greater part of postembryonic mortality occurred in the adult instar and was largely due to host-predation. Females were longer lived than males, and it was suggested that they had an average life expectancy of 5–6 weeks in the field.The life cycle of five other species of Nycteribiidae from two other species of host were briefly examined and no major differences from B. hispida were noted. The results of this and of previous studies indicate that the life cycle is fairly uniform throughout the family.

Digestion and nitrogen metabolism in sheep and red deer given large or small amounts of water and protein.

Abstract: I. The interaction between nitrogen and water intake was studied in two ewes and two red deer hinds. They were given pelleted diets, at maintenance level, containing equal amounts of roughage but either rich or poor in nitrogen. The deer received 50 yo more food than the sheep. Water was given either in large amounts (sheep 5.0 1, deer 7.0 1 daily) or in small amounts (sheep 1.1 1, deer 2.4 1 daily). 2. Nearly three-quarters of the nitrogen of the high-nitrogen rations but less than half of that of the low-nitrogen rations was excreted in the urine. Restriction of water intake reduced urinary nitrogen excretion by only about I g daily, mainly as a result of decreases in the excretion of urea and ammonia, but did not affect the excretion of nitrogen in the faeces. 3. The urinary excretions of creatinine, creatine, hippuric acid, uric acid and allantoin were also examined. The excretion of creatinine was not related to either nitrogen or water intake. The excretion of uric acid and of allantoin was greater in the sheep than in the deer. 4. The concentrations of urea in the plasma and of ammonia in the rumen fluid were measured before and after feeding. The plasma urea value was related to dietary nitrogen intake and was higher on the low- than on the high-water regime. The rumen ammonia value also was related to the nitrogen intake but, while it generally increased after feeding when the high-nitrogen diet was given, it fell almost to zero z h after feeding when the low-nitrogen diet was given. 5. The sheep digested dry matter, cellulose and nitrogen a little more fully than the deer. The high-water regime slightly increased the digestibility of dry matter and cellulose but did not affect the digestibility of nitrogen.

A non-doubling DNA series in somatic tissues of the locusts Schistocerca gregaria (Forskål) and Locusta migratoria (Linn.).

Abstract: Locusta migratoria has only 70% of the germ line DNA value of the related species Schistocerca gregaria in spite of a uniform karyotype. This difference is maintained in the nuclei of the testis wall, ovariole tip, mid-gut diverticulum, Malpighian tubule and fat. The distribution of nuclear DNA contents is tissue specific but the peaks in the distributions do not conform with members of a doubling series. It is suggested that both phenomena may be connected with the mechanism of tissue differentiation in insects, the latter by differential replication of those chromosome regions which are active in particular tissues.