dl‐methionine enrichment in diets fed to Atlantic salmon increases apparent digestibility     

Marit Espe  Bjørn Liaset  Ernst Morten Hevrøy  Adel El‐Mowafi 《Aquaculture Research》2011,42(8):1123-1130

In the current study, we tested whether the addition of a small amount of crystalline dl ‐methionine to a fishmeal‐based diet would affect general sulphur metabolism and apparent digestibility in Atlantic salmon (Salmo salar). Triplicate tanks of salmon with mean BW of half a kilo were fed a control diet or the control diet supplemented with 0.2 wt%dl ‐methionine (+17% methionine relative to control diet) for a period of 3 months. Feed intake and thus nutrient intake did not differ significantly between treatments. Fish fed the diet supplemented with dl ‐methionine had 18% higher mean intake of methionine. The apparent energy digestibility was significantly improved in the salmon fed the methionine‐enriched diet as was the methionine digestibility. Salmon fed the methionine‐supplemented diet had about 32% higher plasma‐free methionine concentration and 25% more total homocysteine 5 h post prandial. No difference was observed in hepatic‐free methionine, but hepatic cystathionine (～62%) and taurine (～20%) were significantly higher in fish fed the methionine‐enriched diet due to a higher transsulphuration. In the liver, taurine might be conjugated to bile acids (BAs), and conjugation of BAs increases their solubility and enhances their biliary secretion affecting the digestibility. Both faecal and plasma BA concentrations were elevated in fish fed the methionine‐enriched diet, although the differences did not reach statistical significance. Taken together, our data show that feeding salmon a fishmeal‐based diet supplemented with a small amount of crystalline dl ‐methionine increased the apparent energy digestibility, possibly through an increased liver transsulphuration and taurine production, which might enhance BA conjugation and biliary secretion.  相似文献   

Breeding for disease resistance of Penaeid shrimps     

James Cock  Thomas Gitterle  Marcela Salazar  Morten Rye 《Aquaculture (Amsterdam, Netherlands)》2009,286(1-2):1-11

Diseases are a major constraint on the intensive production of shrimps. Conditions in production ponds favour disease development, and epidemics of several previously unreported diseases have occurred and caused severe losses. When elimination, eradication or cultural control is difficult, selective breeding for host resistance to the pathogen may be an attractive option for disease control. However, host resistance is not a panacea and should only be considered when (a) the disease causes severe damage (b) there are no other existing simple cost effective control measures and (c) there is demonstrable genetic variation in resistance and this is not coupled with an excessive level of negative associations with other desirable characteristics. Shrimp have only recently been domesticated and breeding for resistance only began in the mid 1990s; there is limited experience with shrimp breeding in particular and crustaceans in general. Consequently, the principles and concepts behind breeding programmes are based largely on experiences with other species in both the plant and animal kingdoms. Commercial growers now seed ponds with shrimp populations selected for resistance to Taura Syndrome Virus with excellent results, whilst up to now development of White Spot Syndrome Virus resistant populations has been an elusive goal. The original TSV resistant populations were developed using simple mass selection techniques (Colombia). In later generations family based selection has been applied on populations, which initially had survival rates of about 30%, with care taken to reduce inbreeding and loss of genetic variation. This suggests that when the original populations have a reasonable level of resistance, and straightforward, effective selection protocols exist, it is relatively simple to breed for resistance. With catastrophic diseases, such as WSSV, which cause mortalities of 98% or more the frequency of resistance is low and it is suggested that for theoretical reasons single gene, rather than polygenic, resistance is likely to develop. The low frequency of resistance genes in breeding populations may cause genetic bottlenecks which will greatly reduce the genetic variation in the populations. In order to maintain the genetic variation the genes from the small numbers of survivors should be introgressed into populations with broader genetic variability. Furthermore, in order to minimize the probability of breakdown of resistance pyramiding of resistant genes on different loci would be advantageous.Genetic variation in resistance may be encountered either in the initial base populations or may spontaneously arise due to mutations or new recombinants. With extremely prolific species such as shrimps, millions of animals can readily be screened for survival and hence resistant mutants or recombinants may be identified. Once genetic variation has been detected the most appropriate breeding methodology will depend on the nature of both the resistance and the disease or diseases that are of interest to the producers.  相似文献   

Identification of novel secaloindoline-a and secaloindoline-b alleles in CIMMYT hexaploid triticale lines   总被引：4，自引：1，他引：4  

Genying Li  Zhonghu He  Roberto Javier Pea  Xianchun Xia  Morten Lillemo  Qixin Sun 《Journal of Cereal Science》2006,43(3):378-386

To characterize kernel hardness, an important trait in triticale breeding, and to identify secaloindoline alleles present in hexaploid triticale lines developed at International Maize and Wheat Improvement Center (CIMMYT) a total of 171 secondary hexaploid lines were analyzed for grain hardness using the Single Kernel Characterization System. They showed a large spectrum of kernel hardness types, from very soft to very hard, with values ranging from 8.6 to 84.9. The occurrence of starch granule-associated friabilin was studied in 30 lines, including 10 hard, 9 mixed and 11 soft genotypes. All soft lines displayed a high level of friabilin, whereas the hard lines showed almost no friabilin, indicating that friabilin is directly involved in the formation of grain texture in secondary hexaploid triticales. Two novel secaloindoline alleles were identified and designated as Sina-R1b and Sinb-R1c. Compared with SINAa, the deduced amino acid sequence of SINAb showed a Trp to Arg substitution at position 44. SINBc had a Gly to Ser substitution at position 78 and a Gly to Arg substitution at position 115, as well as a Cys insertion in the signal peptide, in comparison to SINBa. The novel alleles Sina-R1b and Sinb-R1c were detected in both the soft and hard triticale lines.  相似文献   

Is European research on aquatic food product technology dead?     

Morten Sivertsvik 《Journal Of Aquatic Food Product Technology》2019,28(1)

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Serum chemistry of free-ranging white whales (Delphinapterus leucas) in Svalbard     

Tryland M  Thoresen SI  Kovacs KM  Lydersen C 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2006,35(2):199-203

BACKGROUND: Abnormal physiological conditions and diseases can change the concentrations of enzymes, metabolites, and minerals in the body. Serum chemistry information may thus be indicative of a specific disease; interpretation of such information requires knowledge of serum chemistry reference intervals from a seemingly healthy population of the species. OBJECTIVE: The aim of this study was to obtain serum chemistry reference intervals for a population of white whales. METHODS: Blood samples were collected from 21 free-ranging white whales (beluga; Delphinapterus leucas). The whales were live-captured in nets during 1996-2001 in Storfjorden, Van Mijenfjorden, and Van Keulenfjorden (Svalbard, Norway). While the whales were briefly physically restrained, blood was collected from the caudal vein into vacuum tubes without anticoagulant. The blood was left to clot for 4-6 hours before serum was obtained by centrifugation. The serum samples were then kept at -20 degrees C until analysis. Enzymes (aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase [ALP], creatine kinase, lactate dehydrogenase [LDH], amylase, lipase), metabolites (urea, creatinine, bilirubin, cholesterol, triglycerides, nonesterified fatty acids, glucose), and minerals (calcium, phosphate, magnesium, sodium, potassium, chloride) were analyzed in an Advia 1650 System (Bayer, Tarrytown, NY, USA). Cortisol was analyzed in an Immulite One system (Diagnostic Products Corporation, Los Angeles, CA, USA). The major blood proteins (albumin and globulins) were separated by gel electrophoresis in a Beckman Paragon electrophoresis system (Beckman Coulter, Inc., Fullerton, CA, USA). RESULTS: Serum values for all analytes were reported as median and range, and reference intervals were calculated as 10-90th percentiles. Activities of ALP and LDH and cortisol concentration were higher, and protein and bilirubin concentrations were lower compared with those previously reported for white whales from Canada; remaining results were strikingly similar in these 2 white whale populations. CONCLUSIONS: These data provide valuable serum chemistry reference intervals for future health assessments of white whales in Svalbard and other white whale populations, as well as captive individuals.  相似文献   

Molecular mapping of partial resistance to powdery mildew in winter wheat cultivar Folke     

Morten Lillemo  ?smund Bj?rnstad  Helge Skinnes 《Euphytica》2012,185(1):47-59

The Swedish winter wheat (Triticum aestivum L.) cultivar Folke has a long record of partial and race non-specific resistance to powdery mildew (caused by Blumeria graminis f. sp. tritici) in the field. The aim of the present study was to map the main genetic factors behind the partial resistance in Folke and identify molecular markers for use in marker-assisted selection. A population of 130 recombinant inbred lines was developed from a cross between Folke and the moderately susceptible spring wheat line T2038. The population was tested for powdery mildew resistance over two years at two locations in Norway and genotyped with DArT and SSR markers. Composite interval mapping detected a total of eight quantitative trait loci (QTL) for powdery mildew resistance; six with resistance from Folke on 2BS, 2DL, 5AL, 5BS and 6BS and two with resistance from T2038 on 5BS and 7AL. None of the loci with resistance from Folke mapped to chromosomal regions with known race-specific resistance genes, which confirmed the race non-specific nature of the resistance in this cultivar. The molecular markers linked to the reported QTL will be useful as a tool for selecting partial and potentially durable resistance to powdery mildew based on the resistance in Folke.  相似文献   

Phosphorus dynamics and export in streams draining micro‐catchments: Development of empirical models     

Brian Kronvang  Marianne Bechmann  Morten L. Pedersen  Nicola Flynn 《植物养料与土壤学杂志》2003,166(4):469-474

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Estimation of conversion factors for fungal biomass determination in compost using ergosterol and PLFA 18:2ω6,9     

Morten Klamer  Erland Bååth 《Soil biology & biochemistry》2004,36(1):57-65

Eleven species of common fungi from compost were analysed for their content of ergosterol and phospholipid fatty acids (PLFAs) after growth on agar media. Mean content of ergosterol was 3.1 mg g⁻¹ dw of fungal mycelium (range 1-24 mg g⁻¹ dw). Total amount of PLFAs varied between 2.6 and 43.5 μmol g⁻¹ dw of fungi (mean 14.9 μmol g⁻¹ dw). The most common PLFAs were 16:0, 18:2ω6,9 and 18:1ω9, comprising between 79 and 97 mol% of the total amount of PLFAs. The PLFA 18:2ω6,9, suggested as a marker molecule for fungi, comprised between 36 and 61 mol% of the total PLFAs in the Ascomycetes, between 45 and 57 mol% in the Basidiomycetes and 12-22 mol% in the Zygomycetes. There was a good correlation between the content of the two fungal marker molecules, ergosterol and the PLFA 18:2ω6,9, with a mean content of 1 mg ergosterol being equivalent to 2.1 μmol of 18:2ω6,9. Based on results from the fungal isolates, conversion factors were calculated (5.4 mg ergosterol g⁻¹ biomass C and 11.8 μmol 18:2ω6,9 g⁻¹ biomass C) and applied to compost samples in which both the ergosterol and the PLFA 18:2ω6,9 content had been measured. This resulted in similar estimates of fungal biomass C using the two marker molecules, but was three to five times higher than total microbial biomass C calculated using ATP content in the compost. This could partly be explained by the fact that both of the markers used for fungal biomass are cell membrane constituents. Thus, the ergosterol and the PLFA content were related to the hyphal diameter of the fungi, where fungi with thinner hyphae had higher ergosterol concentrations than fungi with thicker hyphae. This could also partly explain the large interspecific variation in content of the two marker molecules.  相似文献   

Pre-Clovis mastodon hunting 13,800 years ago at the Manis site, Washington     

Waters MR  Stafford TW  McDonald HG  Gustafson C  Rasmussen M  Cappellini E  Olsen JV  Szklarczyk D  Jensen LJ  Gilbert MT  Willerslev E 《Science (New York, N.Y.)》2011,334(6054):351-353

The tip of a projectile point made of mastodon bone is embedded in a rib of a single disarticulated mastodon at the Manis site in the state of Washington. Radiocarbon dating and DNA analysis show that the rib is associated with the other remains and dates to 13,800 years ago. Thus, osseous projectile points, common to the Beringian Upper Paleolithic and Clovis, were made and used during pre-Clovis times in North America. The Manis site, combined with evidence of mammoth hunting at sites in Wisconsin, provides evidence that people were hunting proboscideans at least two millennia before Clovis.  相似文献   

Release of emamectin from sediment: effects of oil,organic material or infauna?     

Eirin Sva Stomperudhaugen  Katherine Langford  Morten Schaanning  Ketil Hylland 《Journal of Soils and Sediments》2014,14(8):1469-1478

Purpose

The aim of this study was to quantify the release of the hydrophobic contaminant emamectin (EMA) from marine sediments in response to inputs of organic material (OM) and/or oil, in the presence or absence of two different bioturbating species. Specifically, it was designed to test whether oil would decrease the release of EMA and whether OM and/or the presence of bioturbating macrofauna would increase the release of EMA from sediment.

Materials and methods

Experimental sediments were spiked with EMA (5 μg kg^?1 wet sediment). The different treatments were prepared by the addition of OM (310 g algae m^?2) and/or an aliphatic oil (29.6 g oil m^?2). In addition, two bioturbating species, Brissopsis lyrifera or Ennucula tenuis, were added in some aquaria, resulting in a total of 12 treatments with four replicates each. Water samples for analyses of silicate and EMA and sediment samples for analyses of total organic carbon (TOC) were taken at the start and end of the experimental exposure. In addition, oxygen was measured during the experimental period of 8 days. Fluxes were calculated and compared between treatments using generalised linear models (GLMs).

Results and discussion

The EMA release flux was significantly increased in treatments with added OM, possibly reflecting the presence of soluble complexes formed between EMA and dissolved OM. The presence of B. lyrifera caused a small, but statistically significant, increase in EMA release from sediment. This species would be expected to have a stronger effect on bioirrigation and particle mixing than E. tenuis, particularly when the population density of the latter species is low (as in the present experiment). There were no consistent effects of oil in this experiment, but the presence of oil decreased the EMA release flux when co-occurring with added OM and/or B. lyrifera. Increased retention of hydrophobic contaminants in the presence of oil is consistent with the existing literature on contaminant fate.

Conclusions

The results from this study highlight the need to consider both the infauna present in polluted areas and the level of organic enrichment of the sediment when modelling the environmental fate of hydrophobic contaminants. It also highlights that labile OM and refractory oil appear to differ in their effects on the remobilisation of hydrophobic organic contaminants, by reducing and increasing release, respectively.  相似文献