Astaxanthin digestibility as affected by ration levels for Atlantic salmon, Salmo salar

The objective of this study was to determine the effect of feed intake on the apparent digestibility coefficient (ADC) of astaxanthin including the major geometrical E/Z-isomers in Atlantic salmon (Salmo salar). Atlantic salmon (50 per pen, initial weight 2 kg) were kept in 125 m³ sea pens equipped with an excess feed collection system to monitor and quantify accurate feed intake, and subjected to three treatments in triplicate. All salmon were fed the same diet supplemented with 47 mg astaxanthin per kg. Two treatments were fed full or restricted rations corresponding to 100 or 40% of apparent satiation, respectively, with a switch in ration between two consecutive feeding periods (14 and 3 d, respectively), whereas the control treatment was fed to 100% of apparent satiation during both periods. The corresponding feed intakes were 0.45 and 0.16% of biomass for salmon fed 100% or 40% of apparent satiation, respectively. Faeces were collected by stripping at the end of each feeding period and ADCs of astaxanthin were determined by an indirect method using yttrium oxide (Y₂O₃) as an indigestible marker. Feed intake and astaxanthin ADC were negatively correlated (R² = 0.64; p = 0.0001). Astaxanthin ADC was 1.5 times higher at the low compared to the high ration level (p < 0.05), but due to the low feed intake the total amount of digested astaxanthin was only about 50% of that in fish fed to satiation. The ADCs of the all-E and 13Z-isomers of astaxanthin were similar and considerably higher than for 9Z-astaxanthin (p < 0.05). The amount of digested astaxanthin/TGC (estimated thermal growth coefficient) decreased with increasing feed intake. Estimates of astaxanthin retention indicated that a higher feed intake cause a lower muscle concentration of astaxanthin compared to that obtained at low feed intakes due to the lower digestibility. Blood samples were collected at the end of the second feeding period to examine possible relationships between plasma carotenoids, feed intake and ADC. Salmon without faeces in the hindgut had a lower plasma astaxanthin concentration compared to salmon with faeces in the hindgut (p < 0.05). In conclusion, feed intake and astaxanthin ADC are negatively correlated, and may thus explain reductions in muscle retention of Atlantic salmon.     

Near-synchronous interhemispheric termination of the last glacial maximum in mid-latitudes

Isotopic records from polar ice cores imply globally asynchronous warming at the end of the last glaciation. However, 10Be exposure dates show that large-scale retreat of mid-latitude Last Glacial Maximum glaciers commenced at about the same time in both hemispheres. The timing of retreat is consistent with the onset of temperature and atmospheric CO2 increases in Antarctic ice cores. We suggest that a global trend of rising summer temperatures at the end of the Last Glacial Maximum was obscured in North Atlantic regions by hypercold winters associated with unusually extensive winter sea ice.     

Blood appearance, metabolic transformation and plasma transport proteins of 14C-astaxanthin in Atlantic salmon (Salmo salar L.)

The time of appearance in blood, and transport of astaxanthin, and catabolic transformation of astaxanthin to idoxanthin were investigated in Atlantic salmon (Salmo salar) that had been force-fed a single dose of ¹⁴C-astaxanthin. In addition to the LPs, a major protein, associated with radiolabeled astaxanthin was detected. The maximum level of radiolabeled carotenoids in blood was attained 30 h after administration of ¹⁴C-astaxanthin. Radioactive idoxanthin (combined 3,4-cis and 3,4- trans glycolic isomers of idoxanthin) appeared after 6 h and a stable level was obtained after 18 h. LPDP and LP, separated by ultracentrifugation, contained on average 89 and 11% of the total radioactivity in plasma, respectively. During the 168 h experiment, maximum radioactivity in LP appeared after 22 h. Separation of plasma by ultracentrifugation on a discontinuous NaCl/KBr-gradient and an iodixanol-gradient confirmed that most of the radiolabeled carotenoids were present in the HDPF that did not contain LPs (58%), whereas HDL and LDL contained 36 and 6% of the radioactivity, respectively. Of the recovered radioactivity, astaxanthin in the HDPF comprised 82%, idoxanthin 5% and unidentified compounds 12%, whereas HDL contained 78% astaxanthin, 22% idoxanthin and no unidentified compounds. Proteins from the fractions with the high density and high radioactivity (iodixanol-gradient) were separated by PAGE under non-denaturing conditions and showed a radioactive band with parallel migration length to BSA and salmon albumin. These results show that astaxanthin is rapidly converted to idoxanthin and that the majority of astaxanthin in the plasma is associated with a protein other than LPs, presumably albumin. The identity of this protein requires verification.     

CO2浓度对番茄光合特性的影响

为了探讨番茄光合特性对C02浓度变化的生态响应,在番茄生长季节,对2个番茄材料在不同C02浓度条件下叶片的光合特性进行了分析.研究结果表明:随着C02浓度的升高,2个番茄材料的光合量子利用效率出现逐渐升高的趋势,但呼吸作用和光补偿点却随C02浓度的升高而出现下降的趋势;光合作用速率和光饱和点在C02浓度低于800μl/L时随C02浓度升高而增加,高于这一浓度则随C02浓度升高而下降.     

Development of containerized Picea abies (L.) Karst. seedlings grown with heavy watering on various peat,perlite and mineral wool mixtures

Effects of growth medium physical conditions were studied. Peat and two series of peat mixed with hydrophobic mineral wool or perlite in three mixing ratios were prepared. Growth media porosities were characterized by the standardized time method and seedling development by measurements of stem length and fresh and dry weight.Seedlings grown in media containing mineral wool showed less mortality, were larger and had more living root apices than seedlings in media lacking mineral wool. Growth media influenced most the stem length and dry weights and was best at higher porosity. The difference between mineral wool and perlite amendments was greater for dry weight than stem length, although the effect of mixing ratio was observed for mineral wool only.The media induced qualitative differences in shoots (foliage spiralling) and roots (branching, number of living root apices, lenticel intumescence).     

Effect of various electric field strengths and current durations on stunning and spinal injuries of Atlantic herring

The aim of this study was to evaluate the effect of electric field strength and current duration on wild-caught Atlantic herring Clupea harengus stunned with sinusoidal 50-Hz AC in seawater. The fish were exposed to electric field strengths ranging from 16 to 142 V/m and current durations from 1 to 12 s. We recorded the elapsed times between the point at which each fish became unconscious and the points at which it resumed normal behavioral functions. We also investigated injuries such as broken spinal columns and hematomas after the fish were filleted. The threshold electric field strength required to stun all of the fish to unconsciousness was 33 V/m for 1 s. The duration of the unconscious condition increased as both electric field strength and current duration increased. Of a total of 260 Atlantic herring, 60% had broken spinal columns. The proportion of fish with fractured spines was independent of field strength and duration, but the number of fractures per fish increased with field strength. We conclude that electrical stunning would promote the welfare of Atlantic herring that are landed alive but negatively affect fillet quality owing to hematomas associated with the fractures.     

Effect of heating and fortification with lysine on protein quality of minor millets

The effect of heating and fortification with lysine on the protein quality of five minor millets namely Italian millet (S. Italica), French millet (Panicum miliaceum), Barnyard millet (Echinochloa colona), Kodo millet (Paspalum scrobiculatum) and Little millet (Panicum miliare) was carried out. The N content of the millets ranged from 1.69 to 2.76 per cent. Proximate composition and dietary fibre was estimated. A reduction of 19–25 in TD and increase of 4–18 in BV was observed on auto-claving and both the differences were significant (P<0.05) in all millets. However, heat processing did not have a pronounced effect on DE. Fortification with lysine at 0.6 g/100 DM increased both the BV and NPU. Although both heat processing and lysine fortification improved protein utilisation, the effect of fortification was comparatively more than heating.     

Urban storm water transport and wash-off of Cæfesium-137 after the chernobyl accident

Radiation protection planning in urban areas after a radioactive fallout requires knowledge of decontamination caused by storm water transport. This report elucidates the transport of ¹³⁷Cs from a roof and three storm sewers in Uppsala during the first rainfall after those, on 29–30 April 1986, causing the Chernobyl contamination. Runoff and concentration Of ¹³⁷Cs in storm water were determined with an accuracy of 10 to 15%. The origin of storm water was determined from its content of ¹⁸O. Surface contamination was measured on 3 July 1986. Total fallout was 25 kBq m^?2. During the rainfall on 11 May, 4 kBq m^?2 were transported from the roof and approximately 1 kBq m^?2 from the sewered areas. From 30 April to 4 July there was a decontamination of 13 to 20 kBq m^?2. Measurements from another project showed that the fallout rain events washed off 10 to 16 kBq m^?2. The wash-off by the small rainfall on 11 May constituted one third of the remaining decontamination occurring up until 4 July. The transport of ¹³⁷Cs during the 11 May event increased when the runoff increased, but was less efficient as the event proceeded. The relations between ¹³⁷Cs concentrations and runoff implied that the wash-off of ¹³⁷Cs in Uppsala was totally dominated by that bound to particles.