Ultrarapid extraction of insecticides from soil using a new ultrasonic technique     

R E Johnsen  R I Starr 《Journal of agricultural and food chemistry》1972,20(1):48-51

  相似文献   

Pesticide effects on bacterial diversity in agricultural soils – a review   总被引：20，自引：0，他引：20  

Kaare Johnsen  Carsten S. Jacobsen  Vigdis Torsvik  Jan Sørensen 《Biology and Fertility of Soils》2001,33(6):443-453

According to guidelines for the approval of pesticides, side-effects on soil microorganisms should be determined by studying functional parameters such as carbon or nitrogen mineralisation. However, the microbial diversity may have been markedly changed following pesticide use despite unaltered metabolism, and such changes may affect soil fertility. This review evaluates new methods for measuring pesticide effects on bacterial diversity, and discusses how sampling should take temporal and spatial heterogeneity into account. Future research on pesticide approval protocols should establish the relationships between mineralisation assays and new and rapid bacterial diversity profiling methods, and should include the possible ecological implications of altered bacterial diversity for soil fertility.  相似文献   

Long-term effects of dietary fat level and feeding rate on growth, feed utilization and carcass quality of Atlantic salmon   总被引：4，自引：0，他引：4  

Hillestad  Johnsen  Austreng  & Åsgård 《Aquaculture Nutrition》1998,4(2):89-97

Two extruded diets designed to have fat levels of 220 g kg⁻¹ (F22) and 300 g kg⁻¹ (F30) were fed to Atlantic salmon Salmo salar L. in two different experiments during the sea rearing period (from 0.2–0.3 kg to 3–4 kg). Each diet was fed restricted and isoenergetically at two feeding rates to fish in triplicate groups. In one of the experiments, a supplementary group of fish was fed to satiation with the F30 diet. All fish were slaughtered and evaluated for quality according to a commercial standard.
No difference in growth was observed between fish fed the two diets at similar feeding rates and the growth was proportional to the amount of dietary energy offered. Feed conversion ratios decreased according to higher energy content in the F30 diet, and the nitrogen and phosphorus retention increased significantly. Fish fed the F30 diet revealed a higher incidence of sexual maturity. Fat content in cutlets and dressed carcasses were significantly affected by feeding rate but not by dietary fat level. Fish fed the F30 diet had more visceral fat and, consequently, lower dress-out percentage. Mortality, liver size and liver colour were not significantly affected by dietary fat level.
These experiments showed that even large differences in dietary fat level employed for the entire sea rearing period of Atlantic salmon, did not, or only marginally affected the cutlet and dressed carcass fat content. The high fat diet improved the feed utilization, thus decreasing the discharge to the environments. Furthermore, it resulted in greater growth at ad libitum feeding.  相似文献   

Increased dietary protein‐to‐lipid ratio improves survival during naturally occurring pancreas disease in Atlantic salmon,Salmo salar L.     

Jens‐Erik Dessen  Turid Mrkre  Jan Ivar Bildy  Stig N. Johnsen  Lars Thomas Poppe  Bjarne Hatlen  Magny S. Thomassen  Kjell‐Arne Rrvik 《Journal of fish diseases》2019,42(1):21-34

This study demonstrated that increased dietary protein‐to‐lipid ratio (P/L‐ratio) improved survival of farmed Atlantic salmon naturally affected by pancreas disease (PD). In addition to diet, body weight (BW) and delousing mortality prior to the PD outbreak also contributed significantly (p < 0.05) to explain the observed variation in PD‐associated mortality. Subsequent to the PD outbreak, large amount of fish failed to grow and caused thin fish with poor condition (runts). At the end of the trial, significantly (p < 0.05) lower amounts of runt fish and increased amount of superior graded fish where detected among fish fed increased P/L‐ratio and within the fish with the largest BWs prior to PD. Diet, BW and delousing mortality contributed significantly (p < 0.05) to explain the variation in the amount of superior graded fish, whereas BW and diet explained the variation in the amount of runt fish. A significant (p < 0.01) negative linear relationship was observed between the amount of superior graded fish and the total mortality, whereas a positive linear relationship was detected between percentage of fillets with melanin and the total mortality. Thus, increased dietary P/L‐ratio seem to reduce the mortality and impaired slaughter quality associated with PD.  相似文献   

Relative absorption of fatty acids by Atlantic salmon Salmo salar from different diets,as evaluated by multivariate statistics     

R.I. Johnsen  O. Grahl‐Nielsen  A. Roem 《Aquaculture Nutrition》2000,6(4):255-261

By using a rapid and simple chemometric method it was shown that Atlantic salmon Salmo salar absorbed the polyunsaturated fatty acids from highly unsaturated diets more efficiently than the monounsaturated and saturated fatty acids. For the monounsaturated and the saturated fatty acids, the degree of absorption decreased with increasing chain length. The diets, based on oils from five different commercial fish species, had different fatty acid profiles. The differences between the several diet groups were maintained between the corresponding faeces groups, even though the fatty acid composition of the faeces was very different from that of the diet. This was because the proportion which was absorbed of each fatty acid was almost equal for all diets.  相似文献   

A fertile female mule     

William E. Jones DVM  PhD  David W. Johnsen DVM 《Journal of Equine Veterinary Science》1985,5(2):87-90

The case of a female mule giving birth to a colt is documented. The karyotype of the dam is shown to be that of a mule. The colt's karyotype is also that of a mule. The sire has a donkey karyotype. Blood grouping analysis also confirmed the parentage.  相似文献   

Black spruce family growth performance under ambient and elevated atmospheric CO2     

Johnsen  Kurt H.  Major  John E. 《New Forests》1998,15(3):271-281

Seedlings from 20 families of black spruce (Picea mariana (Mill.) B.S.P.), representing a large range in field productivity, were subjected to a greenhouse retrospective test under ambient (409 ppm – year 1, 384 ppm – year 2) and high (686 ppm – year 1, 711 ppm – year 2) atmospheric CO₂ environments. After one and two growth cycles, seedling height and diameter growth significantly increased under elevated CO₂. At the end of the experiment, seedlings grown under high CO₂ had a mean above-ground dry weight of 48.77 g as compared to 26.36 g for seedlings grown under ambient atmospheric CO₂. Families were a significant source of variation for all growth parameters. Although the family × CO₂ environment interaction was not a statistically significant source of variation in the analysis of variance, the correlation between greenhouse and 15-year field height growth was weaker (r = 0.29, p = 0.2177) under elevated CO₂ compared to ambient CO₂ (r = 0.51, p = 0.0223) following the first growth cycle. However, following the second growth cycle, greenhouse-field correlations were similar between the two CO₂ environments (ambient CO₂: r = 0.55, p = 0.0115; elevated CO₂: r = 0.56, p = 0.0101). Thus, with this set of families, growth performance ranking after two years appears relatively stable under ambient and elevated CO₂.  相似文献   

Actinomycetes from sediments in the Trondheim fjord, Norway: diversity and biological activity   总被引：1，自引：0，他引：1       下载免费PDF全文

Bredholt H  Fjaervik E  Johnsen G  Zotchev SB 《Marine drugs》2008,6(1):12-24

The marine environment represents a largely untapped source for isolation of new microorganisms with potential to produce biologically active secondary metabolites. Among such microorganisms, Gram-positive actinomycete bacteria are of special interest, since they are known to produce chemically diverse compounds with a wide range of biological activities. We have set out to isolate and characterize actinomycete bacteria from the sediments in one of the largest Norwegian fjords, the Trondheim fjord, with respect to diversity and antibiotic-producing potential. Approximately 3,200 actinomycete bacteria were isolated using four different agar media from the sediment samples collected at different locations and depths (4.5 to 450 m). Grouping of the isolates first according to the morphology followed by characterization of isolates chosen as group representatives by molecular taxonomy revealed that Micromonospora was the dominating actinomycete genus isolated from the sediments. The deep water sediments contained a higher relative amount of Micromonospora compared to the shallow water samples. Nine percent of the isolates clearly required sea water for normal growth, suggesting that these strains represent obligate marine organisms. Extensive screening of the extracts from all collected isolates for antibacterial and antifungal activities revealed strong antibiotic-producing potential among them. The latter implies that actinomycetes from marine sediments in Norwegian fjords can be potential sources for the discovery of novel anti-infective agents.  相似文献   

Influence of 11-ketotestosterone, 17β-estradiol, and 3,5,3′-triiodo-L-thyronine on distribution and metabolism of carotenoids in Arctic charr, Salvelinus alpinus L.*     

B. Bjerkeng  K. Johnsen  I. Mayer  T. Storebakken  K.J. Nilssen 《Fish physiology and biochemistry》1999,21(4):353-364

This investigation examines the influence of implants containing 11-ketotestosterone (11KT), 17-estradiol (E₂), and 3,5,3-triiodo-l-thyronine (T₃) on astaxanthin metabolism in sexually immature individually tagged Arctic charr. The fish (initial average weight 427 g) were maintained in freshwater for 40 days, and weekly implanted intraperitoneally with oil-based injections containing either 11 KT, E₂ or T₃ at levels of 0.1, 1.0 and 0.1 mg (100 g body weight (BW))^–1, respectively. The control fish were given the oil medium alone (0.2 ml 100 g BW^–1). The diet contained ca. 50 mg astaxanthin kg^–1. Carotenoid composition was monitored in plasma, fillet, liver and skin, and 11 KT, E₂ and testosterone (T) levels in plasma. All hormone treatments reduced plasma T compared to the control. E₂-treated fish had a higher (p<0.05) hepatosomatic index (HSI) than the other treatments. Hormone treatment did not influence gonadosomatic index (GSI). T₃ administration induced a silvery skin appearance. The fillet and plasma carotenoid content decreased during the experiment. 11 KT implantation reduced astaxanthin and idoxanthin concentrations of plasma and fillets, and increased the amount in liver and skin, compared to the other treatments. The relative proportion of astaxanthin to idoxanthin was higher in the control fish and T₃ implanted fish, than in fish implanted with 11 KT or E₂ (p<0.05). Fish treated with E₂ had the highest skin carotenoid concentration. Male fish had significantly higher carotenoid content in plasma, fillet and skin than female fish. This study reveals that sex hormones affect carotenoid metabolism and partitioning among body compartments of Arctic charr, effects differently displayed by the sexes.  相似文献   

The Spatial Heterogeneity of Polycyclic Aromatic Hydrocarbons in Soil Depends on Their Physico-chemical Properties     

Bjarne Styrishave  Erland Björklund  Anders Johnsen  Bent Halling-Sørensen 《Water, air, and soil pollution》2012,223(3):969-977

The present study investigates the heterogenic distribution of nine polycyclic aromatic hydrocarbons (PAHs) in soil on a microscale. For this purpose, we developed a method allowing for the detailed analysis of PAHs in minute amounts of soil (5 to 25 mg). A certified reference soil with a known PAH content and a diffusely polluted Danish surface soil from central Copenhagen were used in the study. In order to separate soil heterogeneity from analytical variation, we attempted to establish the least amount of soil in which homogeneous and reproducible results could be obtained for the PAHs in question. The results demonstrated that for fluoranthene, analytical results in accordance with the certified reference values could be obtained in quantities of 10 mg of soil or more. For phenanthrene and pyrene, certified reference values could be obtained in quantities of 25 mg of soil or more. Similar results were obtained with the Nyboder soil, using the reference soil for quality and quantity assurance. For quantification of all nine PAHs, a minimum of 100 mg of soil was needed for both soils. In order to obtain an expression for the degree of heterogeneity of PAHs in the soils, a subsample variation was calculated based on overall sample variation and analytical measurements variation. The results demonstrate that the PAHs in the Nyboder soil are much more heterogeneously distributed than the PAHs in the reference soil due to much larger subsample variations. Furthermore, strong relationships between different physico-chemical properties and subsample variation were found. These included molecular weight, water solubility, log octanol/water partition coefficient, and soil–water distribution coefficient of the investigated PAHs, demonstrating that the heterogeneity of PAHs in the Nyboder soil is significantly influenced by such parameters.  相似文献