Ahipa (Pachyrhizus ahipa (Wedd.) Parodi) in Bolivia

A field survey/collection trip to Bolivia was carried out in 1994 in order to examine the present status of the leguminous tuber/root crop Pachyrhizus ahipa. The germplasm available prior to the field trip was very limited, only one accession of known origin and two of unknown origin were available for genetic analysis and agronomic evaluation. However, in order to ensure that information on cultivation practices, genetic variation and the need for conservation initiatives would become available to the biosystematic Yam Bean Project (funded by the EU/STD3 Programme), a detailed questionnaire was developed and used in the survey. The field trip succeeded in establishing the urgent need for conservation measurements, the considerable genetic variation available within the extant landraces, and the objectives of any future breeding programme. This species possesses numerous agronomically attractive traits.     

Hydrochemical modelling of a stream dominated by organic acids and organically bound aluminium

An existing hydrogeochemical model, the Birkenes model (BIM), has been extended to include production of dissolved organic carbon (DOC) in the soil/water system and its chemical interactions with H⁺ and A1³⁺. The model has been calibrated and verified using precipitation and runoff data from the Svartberget catchment in northern Sweden. The catchment is impacted by moderate amounts of sulphur deposition (6 kg S ha^?1 a^?1; the stream is high in DOC (7–35 mg L^?1) and experiences episodically low pH-values (～4.0). The refined BIM is able to simulate the main variations in major chemical components of the stream water (H⁺, Ca²⁺, Mg²⁺, Al_i, Al₀, Cl^?, SO₄ ^?2 and DOC), as well as stream discharge and ¹⁸O, while Na⁺ is not well reproduced. Although very simplified relationships are used for the chemical interactions between DOC and H⁺ and aluminium, the model shows that these interactions are essential to stream acidity and aluminiumspecies content. Some of the model parameters are poorly determined by calibration with runoff data only. Soil and soil water investigations may contribute to the evaluation and development of the model structure and the representation of chemical processes. Further improvements of the model should emphasize DOC-production/absorption, detailed studies on DOC chemical behaviour and hydrological structure.     

Technical note: Modifying Atlantic salmon (Salmo salar) jumping behavior to facilitate innovation of parasitic sea lice control techniques

Industrial salmon farms are reservoirs of parasitic sea lice (Lepeophtheirus salmonis and Caligus spp.), which causes both production inefficiencies and contributes to population-level declines of wild salmon and trout. Current control methods vary in effect and stimulate controversy by the discharge of chemicals into the environment. An alternate control method uses a thin, chemical-infused oil layer on the sea surface. As farmed salmon jump through the surface, the treatment makes contact with the lipophilic carapace of sea lice and kills them. To enhance the effectiveness of this method, we tested whether the natural jumping behavior of salmon could be increased and directed. In a 2,000-m(3) experimental sea-cage, we removed the ability of groups of salmon to access the surface for different periods (0 to 48 h) and measured their surface behaviors after the surface became accessible again. Surface removal for 24 and 48 h induced 93% of salmon to jump in the 2 h after surface access was reinstated, a result that differed (P < 0.001) from the shorter duration (0 to 12 h) treatments. Salmon without surface access for 24 and 48 h jumped 2 to 3 times more often (P < 0.001), and made their first jump 2 to 3 times sooner (P = 0.003) on average after surface access became available than salmon in the shorter duration treatments. Our results indicate that removal of surface access for short periods may lead to loss of air from the physostomous swim bladder and cause negative buoyancy. This creates a behavioral drive for salmon to jump, swallow air and fill their swim bladders once surface access is reinstated. By combining the increased jumping behavior induced by this technique with a floating, oil-infused treatment, efficiency of sea lice treatments may be improved and treatment chemicals can be re-collected, thus decreasing environmental pollution.     

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.