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  • 1
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    Antarctic krill Thysanoessa macrura fills a major gap in marine lipogenic pathways (1996)
    In:  EPIC3Marine Ecology Progress Series, 134, pp. 295-298
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
    Electronic Resource
    Electronic Resource
    Biosynthesis of neutral lipids by Euchaeta norvegica (1980)
    Springer
    Marine biology 56 (1980), S. 1-6 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparison was made of neutral lipid biosynthesis by intact Euchaeta norvegica, gut tissue isolated from E. norvegica and the E. norvegica from which the gut tissue had been removed. Incorporation of radioactive glucose and alanine into triacylglycerols by all three systems exceeded that into wax esters. Whereas 86.7% of the glucose incorporated into triacylglycerols by gut tissue was located in the glycerol moiety, only 21.8 and 23.8% of glucose incorporated into triacylglycerols by intact and disembowelled copepods, respectively, was recovered in the glycerol moiety. Incorporated alanine in triacylglycerols was always located preferentially in the fatty acid moiety. Radioactive hexadecanol was always extensively incorporated into wax esters, with internal tissues being much more active than gut tissue. The major portion of glucose and alanine incorporated into wax esters was in the fatty alcohol moiety. Gut tissue was much more active than internal tissues in oxidising hexadecanol to hexadecanoic acid. We conclude that gut tissue synthesises glycerol 3-phosphate for use in the esterification of dietary fatty acids to form triacylglycerols. Gut tissue is also activenin oxidising dietary fatty alcohols. Fatty acid biosynthesis, leading to wax ester formation, is a property of internal tissues rather than of the gut.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390587
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  • 3
    Electronic Resource
    Electronic Resource
    Lipogenesis in the arctic euphausiid Thysanoessa inermis (1981)
    Springer
    Marine biology 63 (1981), S. 235-240 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Biosynthesis of lipids by Thysanoessa inermis collected from Balsfjorden, northern Norway, in May 1980, was examined in vitro. The highest concentration of lipid within the krill was in the “hepatopancreas”, and this organ was the most active in esterifying free fatty acids into wax esters. The “hepatopancreas” (i.e., thoracic contents) incorporated (14C) glucose, (14C) alanine and 3H2O into wax esters, with the fatty alcohol moieties being labelled more than the fatty acids. (14C) fatty acid was incorporated preferentially into the fatty acid moieties of wax esters, this incorporation being markedly stimulated by free fatty alcohol. It is concluded that the fatty alcohols of wax esters are preferentially biosynthesized de novo from dietary protein and carbohydrates, whereas the fatty acids derive preferentially from dietary lipid. On the basis of 3H incorporated from 3H2O, the hepatopancreas in a 50 mg II-group (2 yr old) individual of T. inermis is capable of biosynthesizing de novo, approximately 0.1 mg of lipid (as fatty acids) per day at 5°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395992
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  • 4
    Electronic Resource
    Electronic Resource
    Changes in the content and fatty acid composition of lipid in an isolated population of the capelin Mallotus villosus during sexual maturation and spawning (1984)
    Springer
    Marine biology 78 (1984), S. 255-263 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the wet weights and lipid contents of muscle, liver and gonad were determined in male and female Mallotus villosus in Balsfjorden, northern Norway, in 1981, from January, when gonadal development becomes noticeable, until May when the fish are spawning. Fatty acid compositions of tissue lipids were also determined. Over 4 mo prior to spawning, the weight of muscle in female capelin decreased by 32% while the weight of the ovary increased exponentially by 830%. In males the weight of the muscle remained constant and that of the testis decreased slightly. The lipid contents of the muscle of both males and females decreased by 76% over the period and an inverse relationship existed between the water and lipid contents of muscle in both sexes. Male liver weight remained constant over the period of study whereas female liver weight increased transiently by 300% between January and March. 38% of the lipid lost from female muscle was accounted for by lipid deposited in ovary whereas negligible amounts of the lipid lost from male muscle was accounted for by lipid in the testis. Gonadal lipid was always richer in polyunsaturated fatty acids than muscle lipid and, immediately prior to spawning, 42% of the fatty acids in ovarian lipid were polyunsaturated. Muscle lipid of males and females showed a progressive increase in the percentage of the long-chain monoenes 20:1 and 22:1 between January and May. It is concluded that male capelin catabolise more of their muscle lipid reserves than females in the 4 mo prior to spawning and that most of the lipid catabolism in males is associated with physical activity. Conversely, females deposit much more of their muscle lipid in gonads than males, although considerable selectivity occurs in the mobilisation of fatty acids from muscle lipid into ovarian lipid. Additionally, biosynthesis of gonadal constituents accounts for a considerable proportion of the lipid catabolised in females.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393011
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  • 5
    Electronic Resource
    Electronic Resource
    The composition and biosynthesis of lipids in Thysanoessa raschi from the Clyde Estuary, Scotland (1982)
    Springer
    Marine biology 70 (1982), S. 7-12 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lipid composition and biosynthesising activity of Thysanoessa raschi collected from the Clyde Estuary, Scotland, in May 1981 were examined. Triacylglycerols were the major lipid class present, although 16.7% of the total lipid were wax esters in which phytol was the dominant fatty alcohol. The thoracic contents (“hepatopancreas”) of the krill were capable of biosynthesising lipids in vitro from various labelled substrates. Radioactivity from [1-14C] palmitic acid was incorporated into lipids in the order phospholipids〉triacylglycerols〉wax esters; the bulk of the radioactivity was present in all cases in the fatty acyl moieties of the lipids. [U-14C] glucose labelled lipids in the order phospholipids〉triacylglycerols〉free fatty acids〉 was esters; in the first two lipids the radioactivity was mainly in the glycerol moieties, whereas in was esters it was solely in the fatty acyl moieties. The extent of labelling of these lipids from [U-14C] alanine was less than that from [U-14C] glucose, but the pattern of labelling was generally similar. More than 90% of the radioactivity incorporated into total lipid from 3H2O was present in free fatty acids from which it was calculated that the “hepatopancreas” of T. raschi can synthesise 2.5 μg of fatty acid per hour at 15°C. This value is approximately three times lower than that previously determined for T. inermis from Balsfjorden, northern Norway. The results are discussed in terms of the sources of the dietary lipids of krill and the role of endogenous biosynthesis in contributing to its lipid reserves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397290
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  • 6
    Electronic Resource
    Electronic Resource
    Incorporation of 14C-labelled polyunsaturated fatty acids by juvenile turbot, Scophthalmus maximus (L.) in vivo (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 38 (1991), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The ability of juvenile turbot, Scophthalmus maximus (L.), to elongate and desaturate various polyunsaturated fatty acids (PUFA) was examined in relation to their lipid composition. Triacylglycerols were the most abundant lipid class present in the fish and phosphatidylcholine was the predominant phospholipid. In all lipid classes examined the levels of (n-3) PUFA exceeded that of (n-6) PUFA. 18C PUFA were minor components in comparison with 20:5(n-3) and 22:6(n-3). 20:4(n-6) was present in highest concentration in phosphatidylinositol in which it accounted for 16.9% of the fatty acids. When the fish were injected with either 14C-labelled 18:2(n-6), 18:3(n-3), 20:4(n-6), 20:5(n-3) or 22:6(n-3) the highest percentage recovery of radioactivity (69%) in body lipid was observed with 22:6(n-3). With all labelled substrates free fatty acids contained only a small proportion of the total recovered radioactivity whereas triacylglycerols were highly labelled. Phosphatidylcholine/sphingomyelin was the most highly labelled polar lipid fraction. With 14C-20:4(n-6) as injected substrate, 23.2% of the radioactivity recovered in total lipid was present in phosphatidylinositol in comparison with less than 6% with the other substrates. Only small proportions of radioactivity from 14C-18:2(n-6) and 14C-18:3(n-3) were recovered in the 20 and 22C fatty acids of triacylglycerols and total polar lipid. With 14C-20:5(n-3) as substrate, 27 and 33% of the total radioactivity recovered in the fatty acids of triacylglycerols and polar lipids respectively was present in 22C fatty acids. The corresponding values for l4C-20:4(n-6) as substrate were 19 and 18%. The results confirm the limited capacity of turbot to convert 18C PUFA to longer chain PUFA but demonstrate their ability to synthesize 22C PUFA from 20C PUFA. They also suggest a small but specific requirement for 20:4(n-6).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1991.tb03124.x
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  • 7
    Electronic Resource
    Electronic Resource
    Renormalized contact potential in two dimensions (1998)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 39 (1998), S. 749-759 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: We obtain for the attractive Dirac δ-function potential in two-dimensional quantum mechanics a renormalized formulation that avoids reference to a cutoff and running coupling constant. Dimensional transmutation is carried out before attempting to solve the system, and leads to an interesting eigenvalue problem in N−2 degrees of freedom (in the center of momentum frame) when there are N particles. The effective Hamiltonian for N−2 particles has a nonlocal attractive interaction, and the Schrodinger equation becomes an eigenvalue problem for the logarithm of this Hamiltonian. The three-body case is examined in detail, and in this case a variational estimate of the ground-state energy is given. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.532350
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  • 8
    Electronic Resource
    Electronic Resource
    Yang–Mills theory on a cylinder coupled to point particles (1994)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 35 (1994), S. 3845-3865 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: A model of quantum Yang–Mills theory with a finite number of gauge invariant degrees of freedom is studied. The gauge field has only a finite number of degrees of freedom since it is assumed that space–time is a two-dimensional cylinder. The gauge field is coupled to matter, modeled by either one or two nonrelativistic point particles. These problems can be solved without any gauge fixing, by generalizing the canonical quantization methods of S. G. Rajeev [Phys. Lett. B 212, 203 (1988)] to the case including matter. For this, the geometry of the space of connections is used, which has the structure of a principal fiber bundle with an infinite-dimensional fiber. Both problems are reduced to finite-dimensional, exactly solvable, quantum mechanics problems. In the case of one particle, it is found that the ground state energy will diverge in the limit of infinite radius of space, consistent with confinement. In the case of two particles, this does not happen if they can form a color singlet bound state ("meson'').
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.530451
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  • 9
    Electronic Resource
    Electronic Resource
    Renormalized path integral in quantum mechanics (1997)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 38 (1997), S. 2171-2180 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: We obtain direct, finite, formulations of a renormalized quantum mechanical system with no reference to ultraviolet cutoffs and running coupling constants, in both the Hamiltonian and path integral pictures. The path integral description requires a modification to the Wiener measure on continuous paths that describes an unusual diffusion process wherein colliding particles occasionally stick together for a random interval of time before going their separate ways. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.531967
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  • 10
    Electronic Resource
    Electronic Resource
    Muscle fatty acid composition and oxidative stress indices of Arctic charr, Salvelinus alpinus (L.), in relation to dietary polyunsaturated fatty acid levels and temperature (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture nutrition 3 (1997), S. 0 
    Details
    ISSN: 1365-2095
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The influence of feeding high levels of polyunsaturated fatty acids (PUFA) on muscle fatty acid composition and indices of oxidative damage was examined in Arctic charr, Salvelinus alpinus (L.). All diets contained 100 g kg−1 lipid of dry weight. Two diets contained marine fish oils giving a PUFA level of 250 g kg−1 and 500 g kg−1 of lipid. The remaining two diets contained vegetable oils high in either 18:2n-6 or 18:3n-3, giving a PUFA level of more than 500 g kg−1 of dietary lipid. The charr were maintained at 8°C until their weight doubled, and were then transferred to 0.8°C for 30 days. Growth was similar in all groups. The fatty acid compositions of muscle were influenced by dietary PUFA but were less diverse than those of the diets. The overall pattern of fatty acid compositions indicated preferential desaturation and elongation of n-3 PUFA coupled with selective oxidation of 18:2n-6. Total n-3 PUFA content in TAG was always lowered compared with the diet, suggesting a specific mechanism for the removal of these fatty acids. Subjecting the fish to low temperature increased PUFA content in muscle of charr fed the 250 g kg−1 marine n-3 PUFA diet, but had no effect on the other treatments. For fish at 8°C, no significant differences were found between groups in terms of haematocrit, plasma alanine aminotransferase (ALAT), and plasma and muscle thiobarbituric acid reactive substances (TBARS), although there was a tendency towards increased levels of TBARS in the group receiving 500 g kg−1 marine n-3 PUFA of lipid. Subjecting the muscle to forced oxidative conditions resulted in increases in TBARS in all groups, particularly those fed 500 g kg−1 marine n-3 PUFA. Lowering the environmental temperature corresponded with a further increase in the plasma ALAT and muscle TBARS in this group. It is concluded that feeding diets containing high levels of long-chain n-3 PUFA may be detrimental to the fish's health and flesh quality, particularly at low environmental temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2095.1997.00091.x
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