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991.
Hybrid breeding can exploit heterosis and thus offers opportunities to maximize yield, quality and resistance traits in crop species. Cytoplasmic male sterility (CMS) is a widely applied tool for efficient hybrid seed production. Encoded in the mitochondrial genome, CMS is maternally inherited, and thus, it can be challenging to apply in breeding schemes of allogamous self‐incompatible plant species, such as perennial ryegrass. Starting with a general introduction to the origin and the function of mitochondria in plants, this review focuses on the genetics and biology of CMS systems in plants to identify conserved and system‐specific mechanisms. We examine prospects of comparative mitochondrial genomics to identify candidate genes and causative polymorphisms associated with CMS across species and discuss specificities, obstacles and potentials of CMS as a breeding tool for maximizing heterosis in forage grasses. The purpose of the review is to highlight the importance of CMS and hybrid breeding in grasses, with the aim of facilitating research and development of novel breeding strategies to address the future needs for food, feed and biomass production. 相似文献
992.
Distribution,structure and function of Nordic eelgrass (Zostera marina) ecosystems: implications for coastal management and conservation 下载免费PDF全文
Christoffer Boström Susanne Baden Anna‐Christina Bockelmann Karsten Dromph Stein Fredriksen Camilla Gustafsson Dorte Krause‐Jensen Tiia Möller Søren Laurentius Nielsen Birgit Olesen Jeanine Olsen Leif Pihl Eli Rinde 《水产资源保护:海洋与淡水生态系统》2014,24(3):410-434
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993.
994.
Camilla S. Landa Geir Ottersen Svein Sundby Gjert E. Dingsør Jan E. Stiansen 《Fisheries Oceanography》2014,23(6):506-520
Climate change is expected to have major effects on the distribution and abundance of fish. In spite of extensive research on the topic in high‐latitude marine ecosystems, the mechanistic understanding of how temperature impacts recruitment and distribution of arcto‐boreal fish stocks remains elusive. Exemplified by an arcto‐boreal gadoid in the Barents Sea, the Northeast Arctic (NEA) haddock (Melanogrammus aeglefinus), we investigate the effect of ecosystem temperature (here temperature from a fixed reference section) on abundance and distribution boundaries between 1981 and 2008. During this time interval there has been a trend of increasing temperature in the ecosystem. We compare the ecosystem temperature with the species habitat temperature of NEA haddock (i.e., ambient temperature of the population) – two temperature approaches representing the indirect and direct environmental impacts on fish, respectively. In addition to the temperature effects, density‐dependent effects on distribution boundaries are considered. The study is based on swept area density estimates and spatial temperature data collected annually in winter surveys. We found a positive relationship between ecosystem temperature and abundance, a connection related to both direct and indirect mechanisms with short‐term and long‐term pathways. Distribution boundaries are, on a year‐to‐year basis, more related to abundance than ecosystem temperature. The long‐term trends, however, indicate a north‐eastward shift in distribution boundaries, probably indirectly related to the coinciding ecosystem temperature increase. In spite of the gradual increase in ecosystem temperature, the abundance of 4‐ to 7‐ year old NEA haddock expanded into colder waters. Thus, our results show how different the two temperature approaches may be. 相似文献
995.
M.C. Røjbek J.G. Støttrup C. Jacobsen J. Tomkiewicz A. Nielsen E.A. Trippel 《Aquaculture Nutrition》2014,20(6):654-666
Cultivated Atlantic cod (Gadus morhua) entering their first year of gamete maturation were fed diets with different levels of arachidonic acid (ARA) and eicosapentaenoic acid (EPA) for 6.5 months prior to commencement of spawning. Gravid females were stripped three times: at the beginning, peak and end of spawning. Lipid composition and egg and larval quality of 34 family crosses were investigated. Results indicated that ARA uptake into eggs from broodstock diet was highly efficient achieving proportions of ARA up to 84% higher in eggs than in the diet. EPA was 42–76% higher, and DHA was 155–173% higher in eggs than in diets. Cod fed the diet with the lowest EPA/ARA ratio had the greatest egg production. Eggs from fish on a diet with high ARA level had significantly higher fertilization and hatching success than those fed low levels of ARA. This diet produced on average 71 viable eggs g?1 female compared with 32.5 and 4 eggs in diet B and C, respectively. Furthermore, larval survival until 8 days posthatch was higher in diets with lower ARA levels. The combined results showed that ARA dietary supplementation and low EPA/ARA ratio yielded a greater number of viable larvae kg?1 female. 相似文献
996.
J C Streibig J Rasmussen D Andújar C Andreasen T W Berge D Chachalis T Dittmann R Gerhards T M Giselsson P Hamouz C Jaeger‐Hansen K Jensen R N Jørgensen M Keller M Laursen H S Midtiby J Nielsen S Müller H Nordmeyer G Peteinatos A Papadopoulos J Svensgaard M Weis S Christensen 《Weed Research》2014,54(3):223-233
Non‐destructive assessment of herbicide effects may be able to support integrated weed management. To test whether effects of herbicides on canopy variables could be detected by sensors, two crops were used as models and treated with herbicides at BBCH 20 using a logarithmic sprayer. Twelve days after spraying at BBCH 25 and 42 days after sowing, nine sensor systems scanned a spring barley and an oilseed rape field experiment sown at different densities and sprayed with increasing field rates of glyphosate and tribenuron‐methyl. The objective was to compare ED50s for crops and weeds derived by the different sensors in relation to crop density and herbicides. Although sensors were not directly developed to detect herbicide symptoms, they all detected changes in canopy colours or height and crop density. Generally ED50s showed the same pattern in response to crop density within herbicide, but there were marked differences between barley and oilseed rape. We suggest that the results of comparing the various sensor outputs could become a stepping stone to future standardisation for the benefit of the research and development of sensors that will detect herbicide effect on crops and weeds, particularly at the most vulnerable stages of development of the canopy. 相似文献
997.
Nilsson L Osmark P Fernandez C Andersson M Bergenståhl B 《Journal of agricultural and food chemistry》2006,54(18):6881-6887
Water soluble plasma proteins were fractionated from hen's egg yolk, and the molecular weight and pI of the most abundant protein species were characterized with gel electrophoresis. The proteins were identified by mass spectrometry. The protein fraction was used to produce oil-in-water emulsions, both at various protein concentrations and at various pH values, and the surface load was determined through serum depletion. The competitive adsorption was studied through the determination of nonadsorbing species with gel electrophoresis. The results show that it was possible to form an oil-in-water emulsion for which droplet size and maximum surface load depended on the protein concentration and pH. Serum albumin and YGP40 adsorbed selectively at the oil/water interface throughout the pH range investigated, and for albumin the selectivity increased close to its pI. It is suggested that this selective adsorption is due to long hydrophobic stretches in the polypeptide chain, which are present in the selectively adsorbing species but absent in less adsorbing species. 相似文献
998.
Rønning SB Berdal KG Andersen CB Holst-Jensen A 《Journal of agricultural and food chemistry》2006,54(3):682-687
We report the development of a duplex real-time Polymerase Chain Reaction (PCR) for the simultaneous detection and quantification of wheat- and barley-derived DNA. We used a single primer pair to amplify the single-copy gene PKABA1 from wheat and barley, using minor-groove-binding probes to distinguish between the two cereals. The assay was fully specific, and different wheat and barley cultivars exhibited similar Ct values, indicating stability across cultivars with respect to allelic and copy number composition. The limits of detection were 5 and 10 PCR-forming units for wheat and barley, respectively, making the duplex assay as sensitive as other singleplex reference gene systems published. We were able to detect both wheat and barley simultaneously in real food samples, and the duplex assay is considered to be suitable as an endogenous reference gene system for the detection and quantification of wheat and barley in genetically modified organisms (GMO) and other food and feed analyses. 相似文献
999.
Dietz HH Chriél M Andersen TH Jørgensen JC Torpdahl M Pedersen H Pedersen K 《The Canadian veterinary journal. La revue veterinaire canadienne》2006,47(12):1201-1205
Outbreaks of Salmonella Dublin infections were recorded in 25 Danish mink and fox farms. All farms suffered extensive disease problems; clinical and pathological observations included abortion, stillbirths, necrotizing endometritis, and increased mortality. By genotyping with pulsed-field gel electrophoresis and amplified fragment length polymorphism, all isolates of S. Dublin had indistinguishable patterns. The outbreaks took place during April and May, around the time of whelping. During this period, mink are particularly susceptible to Salmonella infections. All affected farms were served by the same feed factory and it was concluded that a batch of contaminated feed was responsible for the outbreaks, although repeated culture of feed samples collected during the same period were negative. No other likely source could be identified. The results emphasize the importance of strict hygiene measures at feed factories and the proper use of ingredients of known Salmonella status, in particular during the whelping season. Infected mink farms did not have a higher risk of outbreak of salmonellosis in the year following the outbreak. 相似文献
1000.
Ken Steen Pedersen Rikke Skrubel Helle Stege ?ystein Angen Marie St?hl Charlotte Hjulsager Lars Erik Larsen Jens Peter Nielsen 《Acta veterinaria Scandinavica》2012,54(1):58