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Highest Accumulation (highest + accumulation)
Selected AbstractsMaximum limits of organic and inorganic mercury in fish feedAQUACULTURE NUTRITION, Issue 2 2004M.H.G. Berntssen Abstract The relatively high levels of mercury found in fish feeds might form a fish health and food safety risk. The present study aims to establish sublethal toxic threshold levels in fish and assess feed-fillet transfer of dietary mercury. Atlantic salmon (Salmo salar L.) parr were fed for 4 months on fish meal-based diets supplemented with mercuric chloride (0, 0.1, 1, 10 or 100 mg Hg kg,1 dry weight (DW)) or methylmercuric chloride (0, 0.1, 0.5, 5 or 10 mg MeHg kg,1 DW). At the end of the experiment, dietary inorganic mercury mainly accumulated in intestine (80% of body burden) and assimilation was low (6%). In contrast, methylmercury readily accumulated in internal organs and muscle (80% of body burden) and had a relatively high assimilation (23%). Highest accumulation of dietary inorganic mercury was observed in the gut and kidney. Fish fed 10 mg Hg kg,1 had an early (after 2 months) significant increase in renal metallothionein (MT) level and intestinal cell proliferation, followed by intestinal pathological conditions after 4 months of exposure. At 100 mg Hg kg,1, intestinal and renal function were reduced as seen from the significantly reduced protein and glycogen digestibility and increased plasma creatinine levels. For dietary methylmercury (MeHg), highest accumulation was found in blood and muscle. Intestinal cell proliferation and liver MT significantly increased at 5 mg MeHg kg,1 after 2 months of exposure. At the end of the experiment, blood haematology was significantly affected in fish fed 5 mg MeHg kg,1 and these fish exceeded the current food safety limit for mercury. Tissue MT induction and intestinal cell proliferation appeared to be useful and quantifiable early indicators of toxic mercury exposures. Based on the absence of induction of these early biological markers such as MT and cell proliferation, nonobserved effect levels (NOELs) could be set to 0.5 mg Hg kg,1 for dietary methylmercury and 1 mg Hg kg,1 for inorganic mercury. Lowest observed effect levels (LOELs) levels could be set to 5 mg kg,1 for methylmercury and 10 mg Hg kg,1 for inorganic mercury. [source] PHOTOSYNTHETIC PERFORMANCE, LIGHT ABSORPTION, AND PIGMENT COMPOSITION OF MACROCYSTIS PYRIFERA (LAMINARIALES, PHAEOPHYCEAE) BLADES FROM DIFFERENT DEPTHS,JOURNAL OF PHYCOLOGY, Issue 6 2006Marķa Florencia Colombo-Pallotta Macrocystis pyrifera (L.) C. Agardh is a canopy-forming species that occupies the entire water column. The photosynthetic tissue of this alga is exposed to a broad range of environmental factors, particularly related to light quantity and quality. In the present work, photosynthetic performance, light absorption, pigment composition, and thermal dissipation were measured in blades collected from different depths to characterize the photoacclimation and photoprotection responses of M. pyrifera according to the position of its photosynthetic tissue in the water column. The most important response of M. pyrifera was the enhancement of photoprotection in surface and near-surface blades. The size of the xanthophyll cycle pigment pool (XC) was correlated to the nonphotochemical quenching (NPQ) of chl a fluorescence capacity of the blades. In surface blades, we detected the highest accumulation of UV-absorbing compounds, photoprotective carotenoids, ,XC, and NPQ. These characteristics were important responses that allowed surface blades to present the highest maximum photosynthetic rate and the highest PSII electron transport rate. Therefore, surface blades made the highest contribution to algae production. In contrast, basal blades presented the opposite trend. These blades do not to contribute significantly to photosynthetate production of the whole organism, but they might be important for other functions, like nutrient uptake. [source] Biosynthesis profile and endogenous titers of polyamines differ in totipotent and recalcitrant plant protoplastsPHYSIOLOGIA PLANTARUM, Issue 1 2005Anastasia K. Papadakis The expression of totipotency in plant protoplasts is a complex developmental phenomenon and is affected by genetic and physiological factors. Polyamines (PAs) are known to be involved in a variety of growth and developmental processes in higher plants, as well as in adaptation to stresses. In this study, we present the homeostatic characteristics of the endogenous PA putrescine (Put), spermidine (Spd), and spermine (Spm) in totipotent (T) and non-totipotent (NT) tobacco protoplasts and in recalcitrant (R) grapevine protoplasts. T-tobacco protoplasts, with high division rates, have the highest level of endogenous PAs. In these protoplasts, the soluble-hydrolyzed fraction predominates and increases, and the insoluble-hydrolyzed fraction also increases, whereas soluble (S) PAs decrease rapidly during culture. The isolation process contributes to the increased Put levels, which are higher in freshly isolated NT-tobacco protoplasts than in T-protoplasts. During culture, total Put predominates over Spd and Spm, and the highest accumulation is found in T-protoplasts. Ornithine decarboxylase and arginase activities both increase in T-protoplasts, whereas arginine decarboxylase activity causes Put accumulation in NT-tobacco protoplasts. R-grapevine protoplasts show a different PA profile, mostly due to the lower PA content, the higher S-fraction, and the higher ratio of Spm to total PAs. The data suggest that the levels and metabolism of the intracellular PAs could be related to the expression of totipotency of plant protoplasts. [source] Maximum limits of organic and inorganic mercury in fish feedAQUACULTURE NUTRITION, Issue 2 2004M.H.G. Berntssen Abstract The relatively high levels of mercury found in fish feeds might form a fish health and food safety risk. The present study aims to establish sublethal toxic threshold levels in fish and assess feed-fillet transfer of dietary mercury. Atlantic salmon (Salmo salar L.) parr were fed for 4 months on fish meal-based diets supplemented with mercuric chloride (0, 0.1, 1, 10 or 100 mg Hg kg,1 dry weight (DW)) or methylmercuric chloride (0, 0.1, 0.5, 5 or 10 mg MeHg kg,1 DW). At the end of the experiment, dietary inorganic mercury mainly accumulated in intestine (80% of body burden) and assimilation was low (6%). In contrast, methylmercury readily accumulated in internal organs and muscle (80% of body burden) and had a relatively high assimilation (23%). Highest accumulation of dietary inorganic mercury was observed in the gut and kidney. Fish fed 10 mg Hg kg,1 had an early (after 2 months) significant increase in renal metallothionein (MT) level and intestinal cell proliferation, followed by intestinal pathological conditions after 4 months of exposure. At 100 mg Hg kg,1, intestinal and renal function were reduced as seen from the significantly reduced protein and glycogen digestibility and increased plasma creatinine levels. For dietary methylmercury (MeHg), highest accumulation was found in blood and muscle. Intestinal cell proliferation and liver MT significantly increased at 5 mg MeHg kg,1 after 2 months of exposure. At the end of the experiment, blood haematology was significantly affected in fish fed 5 mg MeHg kg,1 and these fish exceeded the current food safety limit for mercury. Tissue MT induction and intestinal cell proliferation appeared to be useful and quantifiable early indicators of toxic mercury exposures. Based on the absence of induction of these early biological markers such as MT and cell proliferation, nonobserved effect levels (NOELs) could be set to 0.5 mg Hg kg,1 for dietary methylmercury and 1 mg Hg kg,1 for inorganic mercury. Lowest observed effect levels (LOELs) levels could be set to 5 mg kg,1 for methylmercury and 10 mg Hg kg,1 for inorganic mercury. [source] Brain Neurons Express Ornithine Decarboxylase-Activating Antizyme Inhibitor 2 with Accumulation in Alzheimer's DiseaseBRAIN PATHOLOGY, Issue 3 2010Laura T. Mäkitie Abstract Polyamines are small cationic molecules that in adult brain are connected to neuronal signaling by regulating inward-rectifier K+ -channels and different glutamate receptors. Antizyme inhibitors (AZINs) regulate the cellular uptake of polyamines and activate ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine synthesis. Elevated levels of ODC activity and polyamines are detected in various brain disorders including stroke and Alzheimer's disease (AD). We originally reported a novel brain- and testis-specific AZIN, called AZIN2, the distribution of which we have now studied in normal and diseased human brain by in situ hybridization and immunohistochemistry. We found the highest accumulation of AZIN2 in a pearl-on-the-string-like distribution along the axons in both the white and gray matter. AZIN2 was also detected in a vesicle-like distribution in the somas of selected cortical pyramidal neurons. Double-immunofluorescence staining revealed co-localization of AZIN2 and N-methyl D-aspartate-type glutamate receptors (NMDARs) in pyramidal neurons of the cortex. Moreover, we found accumulation of AZIN2 in brains affected by AD, but not by other neurodegenerative disorders (CADASIL or Lewy body disease). ODC activity is mostly linked to cell proliferation, whereas its regulation by AZIN2 in post-mitotically differentiated neurons of the brain apparently serves different purposes. The subcellular distribution of AZIN2 suggests a role in vesicular trafficking. [source] | ||||||||||