Multi‐decadal variations in spawning ground use in Northeast Arctic haddock (Melanogrammus aeglefinus)

Despite the importance both in an ecological and management context, much uncertainty remains about the underlying factors controlling spawning ground use in marine fish. Here, we investigate how spawning ground use of Northeast Arctic (NEA) haddock (Melanogrammus aeglefinus) has changed over time. By combining data from a Soviet‐Russian egg survey conducted over a 35 year period (1959–1993) with a biophysical drift model, we estimate annual median spawning latitudes of NEA haddock. Furthermore, we test for statistical association between the median latitude of spawning and covariates that are candidates for shaping the spawning distribution of haddock. The results indicate no association with temperature, as measured at the Kola transect, or demographic structure, as measured by the mean weight of spawners. However, we find a positive and significant association between spawning latitude and spawning stock biomass, indicating that density‐dependence may be more important in shaping spawning location than other factors such as temperature and demographic structure. A potential mechanism for the reported effect of spawning stock biomass may act through the distribution at the feeding grounds, which is reported to expand north‐ and eastwards at high population density.     

Effect of sowing methods and sowing rate in organic seed production of timothy (Phleum pratense L.), meadow fescue (Festuca pratensis Huds.) and red clover (Trifolium pratense L.)

Different sowing methods and sowing rates were evaluated in organic seed production of timothy (two trials), meadow fescue (two trials) and red clover (one trial) in Southeast Norway, during 2010–2013. The plan included: (1) broadcast sowing of grass/clover, cover crop sown at 12 cm row distance; (2) sowing of cover and seed crop in crossed rows, both at 12 cm row distance; and (3) sowing of cover crop and seed crop in every other row. The three sowing rates were 5, 10 and 15 kg ha–1 in timothy and meadow fescue and 3, 6 and 9 kg ha–1 in red clover. On average for sowing rates and all trials with timothy, meadow fescue and red clover, first year’s seed yields were 5–6%, 20–25% and 19–25% higher on plots sown with cover crop and seed crop in every other row than on plots where seed crop had been broadcast or sown perpendicularly to the cover crop. The different sowing methods had no effect on weed coverage or weed contamination in the cleaned seed. Increasing sowing rate usually had a negative influence on seed yield, while weed coverage/contamination was not significantly affected. It is concluded that organic seed crops should be established with cover crop and seed crop in every other row at a low sowing rate. However, in an organic production system, even this favorable method will not always be sufficient to meet the requirement for seed crop purity.     

A review of the effects of ingredient composition and processing conditions on the physical qualities of extruded high‐energy fish feed as measured by prevailing methods

Feed comprises the biggest cost in intensive fish farming and the quality of feed is therefore important. A vast body of research has been carried out in order to investigate nutritional quality of alternative ingredients. Effects of ingredients on physical quality are seldom included in these investigations. Physical quality of feed varies with ingredient composition and processing condition and may interfere with feed intake, nutrient digestibility and therefore growth performance of the fish. In this review, physical quality of extruded, high energy feed, and how ingredient composition and processing conditions affect the quality will be addressed. Various pellet properties will be discussed and methods used to evaluate physical quality will be reviewed.     

High Resolution Melt (HRM) analysis is an efficient tool to genotype EMS mutants in complex crop genomes

Background

Targeted Induced Loci Lesions IN Genomes (TILLING) is increasingly being used to generate and identify mutations in target genes of crop genomes. TILLING populations of several thousand lines have been generated in a number of crop species including Brassica rapa. Genetic analysis of mutants identified by TILLING requires an efficient, high-throughput and cost effective genotyping method to track the mutations through numerous generations. High resolution melt (HRM) analysis has been used in a number of systems to identify single nucleotide polymorphisms (SNPs) and insertion/deletions (IN/DELs) enabling the genotyping of different types of samples. HRM is ideally suited to high-throughput genotyping of multiple TILLING mutants in complex crop genomes. To date it has been used to identify mutants and genotype single mutations. The aim of this study was to determine if HRM can facilitate downstream analysis of multiple mutant lines identified by TILLING in order to characterise allelic series of EMS induced mutations in target genes across a number of generations in complex crop genomes.

Results

We demonstrate that HRM can be used to genotype allelic series of mutations in two genes, BraA.CAX1a and BraA.MET1.a in Brassica rapa. We analysed 12 mutations in BraA.CAX1.a and five in BraA.MET1.a over two generations including a back-cross to the wild-type. Using a commercially available HRM kit and the Lightscanner? system we were able to detect mutations in heterozygous and homozygous states for both genes.

Conclusions

Using HRM genotyping on TILLING derived mutants, it is possible to generate an allelic series of mutations within multiple target genes rapidly. Lines suitable for phenotypic analysis can be isolated approximately 8-9 months (3 generations) from receiving M₃ seed of Brassica rapa from the RevGenUK TILLING service.     

Relationships between the Ratio of Plant-Available Phosphorus (P-AL) to Total Phosphorus and Soil Properties

Abstract

The relationships between the ratio of plant-available phosphorus (P-AL) to total P and soil properties were examined in 52 samples of mineral soils collected from different parts of Norway. The ratio P-AL/total P in the soils was used as a measurement of a soil's capacity to bind P in sparsely soluble forms and of the possibility for plants to utilize added P. Simple regression analysis showed that the ratio P-AL/total P was correlated with clay (r= ?0.60???, significant at the 0.1% probability level), Tamm acid oxalate extractable Fe (r= ?0.63???), and Tamm acid oxalate extractable Al (r-= ?0.44???), but not with organic C and pH. Variation of Fe, Al and clay content could explain 50% of the variation of the ratio of P-Al/total P. Partial correlation coefficients showed that Fe was the most important factor explaining the variation of the ratio of P-AL/total P.     

Transport of alpha-tocopherol in Atlantic salmon (Salmo salar) during vitellogenesis

The transport of α-tocopherol was studied during vitellogenesis in Atlantic salmon that were fed diets with two levels of α-tocopherol. α-Tocopherol levels were measured in the flesh, liver, ovary and serum, and in the serum the α-tocopherol levels in the very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL) and very high density lipoprotein (VHDL or vitellogenin) were also measured. Atlantic salmon store α-tocopherol mainly in their flesh because the muscle mass comprises 50% or more of live weight. During vitellogenesis the α-tocopherol content declined to about 10% of the level prior to maturation. The relative range of level of α-tocopherol in the lipoproteins was: HDL> LDL> VLDL> VHDL, irrespective of dietary levels of α-tocopherol. From the recent knowledge on lipid transport during vitellogenesis and the present data, we hypothesize that α-tocopherol is transported from peripheral tissues to liver by HDL and further transported from liver to ovary by LDL. Vitellogenin appears to play a minor role in the transportation of vitamin E to the ovary.