980 resultados para primary elements


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The importance of the ocean as a source of cheap protein food is too well-known to be emphasised. In recent years there has been a tremendous increase in the fishing activity in all maritime nations and during the last few years the total world production has markedly grown. This study explains the importance of a planned exploitation according to scientific principles to preserve the availability and natural fluctuations in the abundance of stocks of marine fish and other commercially important organisms.

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The review report on Kyoga basin lakes (NAFIRRI 2007) described Kyoga basin lakes as important natural resource for the communities within the basin and the surrounding areas. Fisheries of the basin provide a source of protein, income, and employment to generally poor communities in the area. The lakes also generate revenue to the local Governments within the catchment. This indicates that the fisheries of Kyoga basin lakes are a key instrument in poverty eradication and food security. The lakes also act as a source of water for domestic, agricultural and transport purposes. Some of the Kyoga small lakes harbour fish species, which have disappeared from the main lakes Victoria and Kyoga and are therefore important for biodiversity conservation

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Kalyani lake (P sub(1)), a weed infested recreational water body and a weed chocked derelict water body (P sub(2)) in the heart of Kalyani city of West Bengal were studied for a period of one year for their primary productivity and other physicochemical parameters. Very low primary productivity (GPP=360-1237mg C m super(-2) d super(-1); NPP=157-787 mg C m super(-2) d super(-1)) was recorded in P sub(2) in spite of having a high concentration of nutrients (PO sub(4)–P=0.052-0.260mg l super(- 1); NO sub(3)-N=0.110-0.412mg l super(-1)). On the other hand, moderate primary productivity (GPP=1687-3195mg C m super(-2) d super(-1); NPP=900-2700mg C m super(-2) d super(-1)) was found in P sub(1) with comparatively low range of nutrients (P0 sub(4)-P =0.010-0.058mg l super(-1); NO sub(3)-N=0.032-0.118mg l super(-1)). After studying the other physicochemical parameters (temperature, transparency, dissolved oxygen, free carbon dioxide, pH, alkalinity and macrophytic biomass), it was found that the overall hydro-biological conditions of the weed-chocked derelict water body (P sub(2)) is not congenial for biological production as compared to Kalyani Lake (P sub(1)). Kalyani Lake may be used for fish culture with proper management practices.

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Seasonal variations in the phytoplankton density, diversity, gross production and related physicochemical parameters of Poonthura estuary have been followed for a period of one year. The polluted nature of the water body favored a higher density of phytoplankters, which exhibited a positive correlation with gross production. The influence of various physicochemical parameters, phytoplankton density and species diversity on gross production is discussed.

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A novel short neurotoxin, cobrotoxin c (CBT C) was isolated from the venom of monocellate cobra (Naja kaouthia) using a combination of ion-exchange chromatography and FPLC. Its primary structure was determined by Edman degradation. CBT C is composed of 61 amino acid residues. It differs from cobrotoxin b (CBT B) by only two amino acid substitutions, Thr/Ala11 and Arg/Thr56, which are not located on the functionally important regions by sequence similarity. However, the LD50 is 0.08 mg/g to mice, i.e. approximately five-fold higher than for CBT B. Strikingly, a structure-function relationship analysis suggests the existence of a functionally important domain on the outside of Loop III of CBT C. The functionally important basic residues on the outside of Loop III might have a pairwise interaction with alpha subunit, instead of gamma or delta subunits of the nicotinic acetylcholine receptor (nAChR). (C) 2002 Elsevier Science Inc. All rights reserved.

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The effect of primary incubation temperature on the growth temperature range was studied with reference to 296 bacterial cultures isolated from sardine using streak plate technique. The primary incubation temperature used during bacteriological sampling caused a selection of strains according to their growth temperature requirements. Incubation at 8°C caused greater recoveries of psychrotrophs while 30°C favored mesophiles. An incubation temperature of 30°C facilitated the growth of both psychrotrophs and mesophiles.

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The penetrance of Leber's hereditary optic neuropathy (LHON) in families with primary mitochondrial DNA (mtDNA) mutations is very complex. Matrilineal and nuclear genetic background, as well as environmental factors, have been reported to be involved in d