Concentration of Selenium in Liver in Relation to Copper Level in Normal and Copper-Poisoned Sheep

Copper absorption, liver accumulation and development of copper toxicosis in sheep are influenced by a variety of other elements, in particular molybdenum, sulphur and zinc (Underwood 1977). In a previous study on liver concentrations of copper, molybdenum and zinc in normal and copper-poisoned sheep, no direct correlation was found between the concentrations of the three metals, but molybdenum was significantly lower in the livers from sheep dead from chronic copper poisoning than in normal animals (Frøslie & Norheim 1976).     

Genetic parameters for grain angle in 28-year-old Norway spruce progeny trials and their parent seed orchard

? Sawn wood which acquires twist during drying is a substantial problem for the sawmill industry and is to a large extent caused by spiralled grain in the tree.

? In this study, the feasibility of using spiral grain angles as a selection trait in Norway spruce (Picea abies (L.) Karst) tree breeding and the extent of grain angle and its breeding values were investigated. Grain angles under bark and diameter were measured at breast height in three 28-year-old Norway spruce progeny trials and in their parent seed orchard.

? The mean grain angle value was 1.76° in the progeny trials and 1.84° in the seed orchard. Estimated genetic standard deviations for grain angle were almost 1°. Progeny trial heritabilities (H ² > 0.3) were larger than the seed orchard heritability (H ² = 0.24). Genotype by environment interaction among the progeny trials was negligible for grain angle. Progeny trial grain angles exhibited genetic correlation with seed orchard grain angles in the range 0.66 to 0.84.

? Thus, mature wood grain angles are also under considerable genetic control, raising the opportunity to reduce the occurence of left-grained trees, which are prone to producing twisted wood.

     

Seasonal and nutritional effects on the fatty acids of three species of shrimp, Penaeus setiferus,P. aztecus and P. duorarum

The fatty acids of three species of shrimp from the Gulf of Mexico, white (Penaeus setiferus), brown (P. aztecus), and pink (P. duorarum), were analyzed periodically for 1 year. The fatty acid patterns of varied species of shrimp collected at the same time of the year differed very little from each other. On the other hand, a slight but distinctive seasonal variation of the fatty acid composition, irrespective of Penaeus species, was observed. Saturated fatty acids increased during the warm seasons and decreased during the cold months, while the opposite behavior was exhibited by monoenoic and polyenoic fatty acids. When the variations in fatty acid levels were compared to the temperature of the water, there was a 2-month lag period between a change in water temperature and the corresponding variation in fatty acid composition. This slow alteration of the shrimp fatty acids suggests that the changes are effected through the food chain rather than by endogenous adjustment to an alteration in water temperature.Further studies were performed in which the fatty acid patterns of pond- and laboratory-reared shrimp were compared with those of their food. Evidence was obtained confirming the significant effect of diet on the fatty acids of shrimp lipids. Shrimp incorporated certain dietary fatty acids readily but showed little ability for the conversion of C₁₈ polyunsaturated fatty acids into C₂₀ and C₂₂ fatty acids of higher unsaturation. Thus, the C₂₀ and C₂₂ fatty acids which are essential for shrimp growth cannot be substituted in the diet by C₁₈ precursors.Considered in toto, these experiments suggest that diet exerts a strong influence on the composition of shrimp body lipids and that, contrarily, endogenous synthesis or modification occurs to a low degree.     

Drainage in Sweden -the past and new developments

Land drainage in Sweden has been regulated in various laws since the Middle Ages. The lowering of lake surfaces and the ditching of wetlands has been considered a valuable task to gain cultivable land, and more recently, to promote forest growth. However, in recent years the debate surrounding drainage in forests has been a matter of considerable discussion. The dry and hot summer of 2018 has awakened new views on the subject. Monitoring has shown an exceptionally low groundwater levels countrywide. Especially the islands of Öland and Gotland have faced groundwater shortages and the groundwater levels are still low in both small and large aquifers. Drainage within forest land has lacked any scientific basis until rather recently. Still, it has been a supported activity during the twentieth century. However, this has gradually as knowledge on the activity has increased and the ecology of downstream water bodies has been considered. Today, only the rinsing of existing drainage is actively practised, and it is surrounded by a number of recommendations which are still under discussion.     

Fine Structure and Peroxidase Activity of the Bovine Mandibular Gland Cells

The acini of the bovine mandibular gland consist of mucous and demilunar seromucous cells. The mucous cells contain electron-lucid mucigen droplets or mucoid masses, only rarely delimited by membranes. The cisternae of the RER communicate freely. Mitochondria are scarce. The seromucous demilunar cells contain considerably more granules, and perigranular membranes are far more common. Many granules have characteristic alternating electron opaque and less electron dense areas. The prominent RER appears to be associated with a peculiar labyrinth of interconnecting tubules. Mitochondria are numerous. Numerous myoepithelial cells are observed. The cuboidal cells of the intercalated ducts lack signs of secretory activity. The columnar cells of the striated ducts have extensive infoldings of the basal plasma membrane, associated with mitochondria. The cell apex contains many granulated vesicles. Endogenous lactoperoxidase activity could be demonstrated only in the demilunar cells, within the secretory granules, the RER, including the perinuclear cisternae, as well as the labyrinth mentioned above. A positive reaction could be observed over acinar lumina and in intercellular canaliculi. The possible role of peroxidase as a component of a bactericidal system of the bovine saliva is discussed.     

Soil microbial community structure affected by 53 years of nitrogen fertilisation and different organic amendments

The Ultuna long-term soil organic matter experiment in Sweden (59′82° N, 17′65° E) was started in 1956 to study the effects of different N fertilisers and organic amendments on soil properties. In this study, samples were taken from 11 of the treatments, including unfertilised bare fallow and cropped fallow, straw with and without N addition, green manure, peat, farmyard manure, sawdust, sewage sludge, calcium nitrate and ammonium sulphate, with n = 4 for each treatment. Samples were taken from topsoil (0–20 cm) and subsoil (27–40 cm depth) and analysed for concentrations of phospholipid fatty acids (PLFAs), organic C, total N and pH. The results showed that the subsoil samples reflected the total PLFA content of the topsoil, but not the microbial community structure. Total PLFA content was well correlated with total organic C and total N in both topsoil and subsoil. Total PLFA content in topsoil samples was highest in the sewage sludge treatment (89 ± 22 nmol PLFA g dw⁻¹). This contradicts earlier findings on microbial biomass in this sewage sludge-treated soil, which indicated inhibition of microorganisms, probably by heavy metals added with sludge. A switch towards microbial growth and faster decomposition of organic matter occurred around 2000, coinciding with lowered heavy metal content in the sludge. According to the PLFA data, the microbial community in the sewage sludge treatment is now dominated by Gram-positive bacteria. A lack of Gram-negative bacteria was also observed for the ammonium sulphate treatment, obviously caused by a drop in pH to 4.2.     

Browsing of sallow (Salix caprea L.) and rowan (Sorbus aucuparia L.) in the context of life history strategies: a literature review

Sallow (Salix caprea L.) and rowan (Sorbus aucuparia L.) constitute small proportions of the deciduous tree volume in Scandinavia, but are highly preferred winter forage for moose and red deer, which occur at historically high densities. Thus, a possible decline of these tree species has been indicated. Against this background, we have reviewed the life histories of relevance for browsing, as well as the basic biology and genetics of sallow and rowan. The species show similarities with respect to short lifespan, small size and sympodial growth pattern, which are risk factors in a browsing context. They also have high juvenile growth rate, important for growing quickly out of reach of browsers. Sallow depends strongly on disturbance for establishment and is more demanding with respect to soil and light conditions than rowan, possibly important for the substantially lower abundance of sallow on the Norwegian Forest Inventory plots. Similarly, the relative recruitment of small size classes of sallow is less than for rowan. Although recruitment is reported to be hampered in wintering areas with high moose or red deer densities, the inventory data, however, dating only back to 1994, do not suggest a general decrease in any of the species. Sallow and rowan saplings show low mortality in moose and deer dominated areas and the species can be characterised as rather resilient to browsing. Of more concern is that browsing can constrain the development of mature rowan and sallow trees locally, with possible consequences for associated epiphytic biodiversity.