Showing papers by "Swedish University of Agricultural Sciences published in 1983"

A New Non-Thrombogenic Surface Prepared by Selective Covalent Binding of Heparin Via a Modified Reducing Terminal Residue

Abstract: A new method for the covalent binding of heparin to artificial surfaces has been developed. The heparinized surface releases insignificant amounts of heparin and can be regarded as stable. The blood contact properties as studied in vitro revealed that the surface was highly thromboresistant in terms of reduced platelet adhesion, surface catalyzed adsorption and inhibition of thrombin and capacity to prevent clotting of nonanticoagulated blood.

The distribution and productivity of fine roots in boreal forests

Abstract: The important role of fine roots in the energy expenditure of boreal forests has only recently been illuminated in ecosystem research. As demonstrated in recent research, fine roots are in constant flux, with death and replacement taking place simultaneously. Closely related to the energy costs of development and maintenance of the different roots systems are their functional effectiveness as organs for the absorption of water and nutrients. In forests the dynamics of fine roots need to be considered further in order to make reliable comparisons of plant productivity on an ecosystemic level.

Aluminium chemistry and acidification processes in a shallow podzol on the Swedish westcoast

Abstract: Processes pertinent to soil acidification with special emphasis on the solution chemistry of A1, were studied in three adjacent small catchments on the Swedish westcoast, with mixed coniferous forest and shallow podzols (average soil depth 50 cm). Soil solution from different depths, groundwater and stream-water were sampled. Separation of organic and inorganic Al species was done with an ion exchange technique. The concentration of organic A1 species was linearly correlated with the concentration of dissolved organic C (r,2, varied from 0.38 to 0.69 with p, < 0.001). In the A horizon 83 to 97 % of the dissolved A1 consisted of organic species. The average concentration of total A1 varied from 3.3 to 9.8 μmole 1−1, in soil leachates collected below the A0, horizon, and from 29.3 to 47.0 pmole 1−1, in leachates collected below the A2, horizon. The organic Al species decreased in importance with increasing soil depth. Leachates collected below the B horizon had average total A1 concentrations ranging from 95.3 to 115 pmole 1−1, with a contribution of organic species varying between 8 and 20% of the total concentration.

Nitrogen Immobilization in Decomposing Needle Litter at Variable Carbon: Nitrogen Ratios

Abstract: The nitrogen dynamics in decomposing needle litter incubated in a clear—cut area were seen to be very different from those of the same types of litter incubated in a mature forest. In each stand 10 different sets of Scots pine needle litter with different initial nitrogen concentrations were incubated. A nonlinear regression model of loss and nitrogen dynamics estimates that the C/N ratio above which net immobilization and below which net mineralization takes place differs significantly between the systems (109 in the mature forest and °63 in the clear—cut area).

Hereditary progressive retinal atrophy in the Abyssinian cat

Abstract: Progressive retinal atrophy (PRA), a hereditary eye disease leading to blindness, was found in the Abyssinian breed of cat. Sixty-eight cases of a bilateral generalized retinopathy, at different stages of the disease process, were seen in the breed during ophthalmoscopic examinations of cats throughout Sweden during a 2-year period. Forty-five percent of cats aged 2 years or older were affected in the examined group. The earliest case was diagnosed in a 16-month-old cat. At the age of 3-4 years a bilateral retinal atrophy was usually present in affected cats. Genetic analysis indicates that PRA in the Abyssinian cat is caused by an autosomal recessive gene.

Variation among species and varieties in uptake and utilization of potassium

Abstract: In uptake experiments from water cultures K+-influx in roots of sunflower (Helianthus annuus L.), cucumber (Cucumis sativus L.), birch (Betula verrucosa Ehrh.), lingonberry (Vaccinium vitis-idaea L.), and pine (Pinus silvestris L.) was related to the K+-contents of the roots. However, due to genotypic variation, no universal “optimum” K+-state of the roots for maximum K+-influx could be defined.

Treadmill for equine locomotion analysis

Abstract: A treadmill for equine locomotion analysis is described and its potential considered for locomotive research and clinical investigation. The treadmill comprised an endless belt driven by a hydraulic motor at various speeds up to 14 m/sec and the direction of belt movement was reversible. The carrying side of the belt ran over a steel-concrete table which acted as a flat support. The belt itself consisted of a steel base on to which was glued a rubber belt and the surface was covered with a layer of coir matting which permitted some forward sliding of the landing hooves simulating the conditions on an ordinary track. The treadway could be inclined up to 10 degree in the longitudinal and 7.5 degrees in the transverse direction. To minimise the risk of injuries a special emergency stop system was installed. Horses adapted well to exercising on the treadmill, even without any previous experience. A good correlation was found between the gait repetitiveness on the racetrack and that displayed on the treadmill. One horse recorded both on the racetrack and on the treadmill showed significantly shorter strides on the treadmill but this did not invalidate the treadmill as a useful research tool in the study of equine locomotion.

Silage fermentation of fish or fish waste products with lactic acid bacteria

Abstract: Silage fermentation of minced fish and fish offal after inoculation with cereals prefermented with Pediococcus acidilactici and Lactobacillus plantarum initiates a rapid fall in pH to below 4.5 within 30 h, and the content of competing gram-negative fermenters and fish pathogens, such as Vibrio anguillarum and Aeromonas salmonicida, is eliminated. The addition of 0.1% sorbic acid inhibits the growth of yeasts during the initial fermentation period and during storage but does not affect the lactic acid fermentation. Degradation of nitrogen components proceeds during storage and is manifested as an increase in volatile basic nitrogen compounds, amino acids and peptides. These substances increase the pH and/or force the bacteria to produce more acid. The rate of production of these basic substances is mainly temperature-dependent and cannot be attributed to microbial activity. The proteolytic activity is mainly caused by tissue proteases (e.g., cathepsins) and, to a lower degree, by gut proteases. It is doubtful whether fish fermentation can be utilised on an industrial scale without improving the technique. Such improvements consist of the selection and use of psychotrophic lactic acid fermenters and commercially acceptable inhibitors of proteolytic activity and yeast growth.

Exogenous Prostaglandin F2α Promotes Uterine Involution in the Cow

Abstract: Three newly delivered dairy cows were given prostaglandin F2α during the immediate postpartum period. PGF2α was administered from day 3–13 post partum in doses of 25 mg twice daily. Endogenous release of PGF2α and progesterone was studied in blood plasma during the experimental period. Rectal examination of the uterus was performed every second day in order to establish the end of uterine involution. Uterine involution in the three cows was completed days 16, 23 and 20, respectively. These figures are to be compared with earlier investigations of uterine involution times, which show about 27 days. It was concluded that PGF2α had a positive effect on the uterine muscular tone.

Low protein variability and genetic similarity between populations of the polar bear (Ursus maritimus)

Abstract: Blood samples from a total of 460 polar bears (Ursus maritimus) from various Arctic regions, but excluding the USSR, were collected during the period 1967-1981 to study electrophoretic variation in different proteins. Two hundred and one samples from Alaska, 48 from the Canadian Arctic, 89 from Svalbard, and 21 from Northeast Greenland were collected during the period 1967-1973 and were analysed by vertical polyacrylamide gel electrophoresis to study transferrin and hemoglobin polymorphism, Thirty-one samples collected in 1974 were analysed by starch gel electrophoresis for 14 enzyme systems in serum and red blood cells. Seventy samples collected from Alaska, the Barents Sea, and Canada in 198&81 were studied by starch gel electrophoresis, and further analysed for protein variation by thin-layer isoelectric focusing, horizontal polyacrylamide gel electrophoresis, and two-dimensional electrophoresis. In all, about 75 loci were analysed for variation. The degree of protein and enzyme variation in the polar bear was observed to be relatively low. Starch gel electrophoresis revealed variation of an unidentified serum protein. The distribution of this protein indicates a closer connection between bears in Alaska and Canada compared to those in Greenland and Svalbard, but the differences were not significant. As in many large mammals, the information from protein variation in polar bears has limited use for management purposes. We could not find any simple system usable for identification of discrete populations. On the basis of protein variation as sole criterion, the populations investigated could not be separated. Possible explanations for the uniformity of blood proteins can be exchange of bears between geographical areas and/or a high selective pressure in polar bears.

Relationships of Milk Somatic Cell Counts to Daily Milk Yield and Composition

Abstract: (1983). Relationships of Milk Somatic Cell Counts to Daily Milk Yield and Composition. Acta Agriculturae Scandinavica: Vol. 33, No. 3, pp. 209-223.

Gill morphology in the zebrafish, Brachydanio rerio (Hamilton‐ Buchanan)

Abstract: A light and electron microscopic study of the gills of the zebrafish, Brachydanio rerio, were made to serve as a morphological basis for future investigations. It was found that for fixation of B. rerio gills, a mixture of 1·5% gluturaldehyde and 1·5% paraformaldehyde gives a mucus-free surface. Morphometric measurements of structural components of the gill secondary lamellae were made. Observations at SEM were correlated with those made at TEM. The different cell types in the branchial epithelium were characterized. Chloride cells were mainly located in the interlamellar regions and on the afferent side of the primary lamellae. Two morphologically different chloride cells were seen. The first type communicates with the external environment through a reservoir-like lumen, which is normally absent in freshwater fishes. The second type of chloride cell has more direct contact with the ambient water, resembling chloride cells from other freshwater fishes. Another cell type with features similar to those of the rodlet cell was frequently observed. This cell is interposed between other types of cells in the epithelium, and sometimes junctional complexes were present between the rodlet cell and surrounding cells.

In vitro rooting of the apple rootstock M 26 in adult and juvenile growth phases and acclimatization of the plantlets

Abstract: In order to obtain optimum conditions for in vitro propagation of the apple rootstock M 26 (Malus pumila Mill.) in adult and juvenile growth phases, several rooting experiments were performed. Supraoptimal concentrations of indole-3-butyric acid (IBA) added to the rooting media resulted in profuse callus formation. Since extensive callus production is detrimental to the survival of the plantlets, modified culture conditions were established to reduce callus formation. A reduction of the time of exposure to IBA to 5 days and, thereafter, transfer to a hormone-free medium did not eliminate callus production. Exposure to darkness during the root initiation phase increased rooting. When the rooting medium was based on the Lepoivre formula instead of the Murashige and Skoog formula, callus formation was reduced. Optimum conditions for rooting were obtained at much lower concentration than earlier reported, being 1.25 μM for the juvenile and 0.5 μM for the adult growth phase in the range of IBA concentrations tested. Anatomical studies revealed that root initials are formed after 5 days of IBA-treatment. Therefore, we transferred shoots directly to non-sterile conditions after the root-inducing phase. This resulted in a 90% survival of the plantlets. Subculture on hormone-free medium can thus be eliminated when the optimum auxin concentration is known.

Improved culture ability of potato protoplasts by use of activated charcoal.

Abstract: Protoplasts were obtained from in vitro grown plants of Solanum tuberosum L. The protoplasts were cultured in X-plate petri dishes with the culture medium joined to a reservoirmedium. When activated charcoal was added to the reservoirmedium the culture ability of the protoplasts was significantly increased. The effect of activated charcoal was mainly due to a less pronounced browning of the developing protoplasts and this technique might be of help in protoplast cultures where browning is a problem.

An energetic basis of equine performance.

Abstract: Summary Although different physiological and behavioural attributes are needed for various types of equine competition, successful racing depends primarily on the animal's metabolic ability to convert chemical energy to mechanical energy — the function of muscle. Components of these energetic processes include the rate, efficiency and interaction of aerobic and anaerobic metabolism in muscle and the supply and utilisation of fuel. In anaerobic work like racing, fatigue processes may be largely regarded as a function of an intramuscular fuel (phosphogen) depletion, despite the fact that substrates are supplied via the circulation. Physical work capacity in the horse depends then mainly on the rate of aerobic metabolism and the capacity of the anaerobic processes to supply energy for continued muscle contraction. Underlying these processes are physiological limitations of the cardiovascular system and the ultrastructure and biochemistry of muscle. A model is proposed whereby prediction of equine performance is based entirely on parameters of energy metabolism. Resume Des aptitudes physiologiques et des qualites de comportement sont necessaires pour satisfaire aux exigences variees de la competition equine. Nonobstant ceci le succes en course depend d'abord de l'aptitude metabolique de l'animal a convertir l'energie chimique en energie mecanique: c'est le role des muscles. Les facteurs de ces phenomenes energetiques sont en particular la rapidite l'efficacite et les interactions des metabolismes aerobies et anaerobies dans le muscle; aussi l'alimentation et l'aptitude a utiliser les sources d'energie. Dans une activite anaerobic telle que la cour se, les phenomenes de fatigue peuvent etre consideres comme dependant largement d'un appauvrissement des sources musculaires d'energie (phosphogene); ceci en depit des apports energetiques du systeme circulatoire. L'aptitude du cheval au travail physique depend donc beaucoup de la rapidite du metabolisme aerobic et de la capacite des phenomenes anaerobics a fournir l'energie pour la contraction musculaire. Mais le muscle — dans sa structure profonde et dans sa biochimieet le systeme cardiovasculaire comportent des limites physiologiques. On propose un modele pour lequel la prevision des performances est fondee sur des parametres du metabolisme energetique. Zusammenfassung Obgleich verschiedene physiologische und verhaltensbestimmende Attribute fur die verschiedenen Zweige des Pferdesports notwendig sind, kann man festhalten, dass Erfolge im Rennsport vor allem abhangen von der Fahigkeit des Tieres, chemische Energie in mechanische zu verwandeln: die Funktion der Muskulatur. Diese energetischen Vorgange setzen sich zusammen aus der Geschwindigkeit, der Effizienz und der Interaktion aerober und anaerober Stoffwechselprozesse im Muskel und der Versorgung und Verbrennung von Brennstoff. Wahrend einer anaeroben Arbeit (Rennen) konnen Ermudungserscheinungen vor allem als Funktion einer intramuskularen Brennstoffunterversorgung (Phosphogen) angesehen werden, trotz des Umstandes, dass Substrate uber die Zirkulation zur Verfugung gestellt werden. Die physikalische Arbeitskapazitat des Pferdes hangt vornehmlich ab von der Umsatzgeschwindigkeit des aeroben Metabolismus und von der Kapazitat der anaeroben Prozesse, Energie fur die kontinuierliche Muskelkontraktion zur Verfugung zu stellen. Physiologisch begrenzt werden diese Vorgange durch das cardiovaskulare System, die Ultrastrukturen und die Biochemie des Muskels. Es wird ein Modell vorgestellt, das eine Leistungsvoraussage allein auf der Grundlage von Parametern des Energiestoffwechsels erlauben soll.

Fertilizer nitrogen budget in a Scots pine ecosystem attained by using root-isolated plots and 15 N tracer technique

Abstract: The distribution and quantitative recovery of isotopically labelled fertilizer N was studied in aPinus sylvestris L. stand in central Sweden. The investigation was carried out with root-isolated plots, area 31.2 m2, having a Scots pine aged 120–140 years in the centre of each plot. The fertilizer application rate was 100 kg ammonium nitrate-N per hectare, with either ammonium or nitrate being enriched with15N. The treatments comprised both a single and a split application. The analyses of needle biomass, collected during the first growing season showed that the proportion of labelled N in Ntot was greater in current needles than in older needles. Moreover, the isotopic enrichment was higher in treatments with labelled nitrate than in those with equivalent amount of labelled ammonium. Two growing seasons after fertilization the trees were felled and the distribution of labelled N in the system was determined. The study proved that the greatest proportion of labelled N in Ntot was in the needles and shoots of current and previous year's growth. The lowest proportion of labelled N was found in the stem wood and coarse roots. The proportion of labelled N in needles and shoots showed a tendency to increase with height in the crown. As regards bark and wood, the corresponding figures increased from the base to the top of the stem, and was higher in bark than in wood. Between 12 and 28% of the supplied N was recovered in trees, half of which in the needle biomass. In the above-ground parts of the shrub layer 3 to 13% of applied N was recovered. The corresponding recovery figure in the soil varied between 37 and 59% (excluding roots, but including litter and bottom layer). Between 5–8% was recovered in roots <30 mm. On the average, 79% of the supplied N was recovered in the studied part of the system. No significant differences in total15n recovery were found between treatments with ammonium or nitrate source of N, or those with different application techniques. The labelled N not recovered in the investigated part of the system, had presumably been lost by leaching.

Natural formation of ethylene in forest soils and methods to correct results given by the acetylene-reduction assay

Abstract: Three methods to determine the natural formation of C 2 H 4 by forest soils were studied in connection with the C 2 H 2 -reduction assay. (1) Incubations with 500 μl C 2 H 2 l −1 in ambient air gave a very low N 2 ase activity and strongly suppressed the decomposition of added C 2 H 4 . The natural formation of C 2 H 4 was significantly lower in 100 ml C 2 H 2 l −1 than in 500 μl l −1 . 1. (2) Incubations in 100 ml C 2 H 2 l −1 after amendment of 1 mg g −1 NH 4 + -N to soil. This amendment inhibited N 2 ase activity, and the natural formation of C 2 H 4 was only slightly affected. 2. (3) Incubations in 100 ml C 2 H 2 l −1 with 20ml CO l −1 . This concentration of CO suppressed N 2 ase activity by 95% but did not influence the natural formation of C 2 H 4 and had only a weak effect on respiration. It was concluded that the three methods can be used as controls for the natural formation of C 2 H 4 in connection with the C 2 H 2 -reduction assay, the first only to detect ils occurrence and possible significance and the two other to determine its exact value. Tested on samples from two coniferous forest soils, the third method (C 2 H 2 + CO) gave a higher natural formation of C 2 H 4 and consequently a lower N 2 ase activity than the conventional method in which the control is incubated in ambient air.

High surface hydrophobicity of Staphylococcus aureus as revealed by hydrophobic interaction chromatography

Abstract: Hydrophobic interaction chromatography (HIC) on Octyl SepharoseR in a column procedure was used to compare the relative surface hydrophobicity ofStaphylococcus aureus reference strains, protein A-negative mutants, and strains isolated from bovine mastitis High protein A-producing strains (Cowan 1 and clinical isolate SA 17970) showed a higher relative surface hydrophobicity than did strains producing a low amount of protein A One encapsulatedS aureus strain (Smith diffuse) did not bind to the gel, while an unencapsulated variant showed binding properties similar to weak protein A-producing strains Studies onS aureus strains isolated from bovine mastitis revealed a good correlation between adsorption to Octyl Sepharose and the production of protein A Results indicate that protein A and probably other surface proteins such as fibronectin-binding protein contribute to the high relative surface hydrophobicity ofS aureus

Somatic hybridization in Nicotiana: behavior of organelles after fusion of protoplasts from male-fertile and male-sterile cultivars.

Abstract: Protoplasts from a nitrate reductase-deficient mutant of Nicotiana tabacum (cnx−68) were fused with protoplasts of 3 different cytoplasmically male-sterile cultivars of tobacco. Two cultivars had no stamens in the mature flowers and the third had petaloid structures in place of the stamens. Plants were regenerated from the fused protoplasts and characterized with respect to stamen development, chromosome number, and two chloroplast-coded traits. Nearly all hybrid plants displayed the chloroplast traits of only one parent, indicating that chloroplast segregation had occurred. The frequency of appearance of each chloroplast type differed according to the species origin of the chloroplasts. Chloroplasts from N. undulata competed much better than those from N. tabacum; N. suaveolens somewhat better than N. tabacum; and N. glauca about equally with N. tabacum. These results are compatible with an interpretation that equal frequency of appearance of chloroplast type among the regenerated plants occurs if the chloroplast DNAs of the parents are similar, whereas a bias of chloroplast type appears among the regenerated plants when the chloroplast DNAs are different. The appearance of aberrations in stamen development resembling the cytoplasmic male-sterile parental types was infrequent among the hybrid plants in all three crosses. Thus sterility factors were generally overcome by fertility factors following somatic hybridization.

Leaching of nitrate from arable land into groundwater in Sweden

Abstract: The agricultural influence on the quality of the groundwater in Sweden is mostly associated with infiltration areas. The local conditions here determine the extent of the nitrate leakage. It is evident that certain combinations of factors in normal cropping can give unduly high nitrate concentrations in the groundwater.