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Vazquez-Dominguez Evaristo; Gasol Josep M.; Agusti Susana; Duarte Carlos M.; Vaque Dolors 《Journal of plankton research》2005,27(10):1055-1066
The trophic relation between prokaryotes and heterotrophic nanoflagellateswas studied during two latitudinal cruises in the central AtlanticOcean. The losses to predation on prokaryotes were determinedin 12 locations covering a wide range of trophic situations,from ultraoligotrophic [<0.05 mg chlorophyll a (Chl a) m3]to moderately eutrophic waters (>1 mg Chl a m3). Inthese locations, the abundance of prokaryotes (P) covaries withthat of heterotrophic nanoflagellates, thus suggesting thatresources controlled the abundance of heterotrophic nanoflagellates(HNF). Besides, the losses to predation were positively relatedto prokaryotic and heterotrophic nanoflagellate biomass, whichpoints toward higher consumption rates associated with largerconcentrations of preys and predators. Conversely, decliningtrends between prokaryotic production (PP) and the fractionof this production lost to predation revealed higher relativelosses in the environments with lower productions. Our studyshows for the central Atlantic that 35% of prokaryotic biomass(BP), equating to between 40 and 83% of PP can be ingested dailyand that 55% of the variability observed in the rate of prokaryoticloss to predation was related with the HNF. As predators grazeon many prey types, in an oligotrophic system containing manyprey species but little numeric loading, there will still beprey for predators but not enough hosts for viruses. In thissense, our study confirms the importance of the preypredatorrelationship between prokaryotes and heterotrophic nanoflagellatesin the flow of carbon of the less productive regions of theocean. 相似文献
94.
Marra P Salvatore L Mironov A Di Campli A Di Tullio G Trucco A Beznoussenko G Mironov A De Matteis MA 《Molecular biology of the cell》2007,18(5):1595-1608
The Golgi complex in mammalian cells forms a continuous ribbon of interconnected stacks of flat cisternae. We show here that this distinctive architecture reflects and requires the continuous input of membranes from the endoplasmic reticulum (ER), in the form of pleiomorphic ER-to-Golgi carriers (EGCs). An important step in the biogenesis of the Golgi ribbon is the complete incorporation of the EGCs into the stacks. This requires the Golgi-matrix protein GM130, which continuously cycles between the cis-Golgi compartments and the EGCs. On acquiring GM130, the EGCs undergo homotypic tethering and fusion, maturing into larger and more homogeneous membrane units that appear primed for incorporation into the Golgi stacks. In the absence of GM130, this process is impaired and the EGCs remain as distinct entities. This induces the accumulation of tubulovesicular membranes, the shortening of the cisternae, and the breakdown of the Golgi ribbon. Under these conditions, however, secretory cargo can still be delivered to the Golgi complex, although this occurs less efficiently, and apparently through transient and/or limited continuities between the EGCs and the Golgi cisternae. 相似文献
95.
Assessing the efficiency of RNA interference for maize functional genomics 总被引:6,自引:0,他引:6 下载免费PDF全文
96.
Gossert AD Hinniger A Gutmann S Jahnke W Strauss A Fernández C 《Journal of biomolecular NMR》2011,51(4):449-456
An easy to use and robust approach for amino acid type selective isotope labeling in insect cells is presented. It relies
on inexpensive commercial media and can be implemented in laboratories without sophisticated infrastructure. In contrast to
previous protocols, where either high protein amounts or high incorporation ratios were obtained, here we achieve both at
the same time. By supplementing media with a well considered amount of yeast extract, similar protein amounts as with full
media are obtained, without compromising on isotope incorporation. In single and dual amino acid labeling experiments incorporation
ratios are consistently ≥90% for all amino acids tested. This enables NMR studies of eukaryotic proteins and their interactions
even for proteins with low expression levels. We show applications with human kinases, where protein–ligand interactions are
characterized by 2D [15N, 1H]- and [13C, 1H]-HSQC spectra. 相似文献
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Chagas disease is caused by Trypanosoma cruzi and is endemic to North, Central and South American countries. Current therapy against this disease is only partially effective and produces adverse side effects. Studies on the metabolic pathways of T. cruzi, in particular those with no equivalent in mammalian cells, might identify targets for the development of new drugs. Ceramide is metabolized to inositolphosphoceramide (IPC) in T. cruzi and other kinetoplastid protists whereas in mammals it is mainly incorporated into sphingomyelin. In T. cruzi, in contrast to Trypanosoma brucei and Leishmania spp., IPC functions as lipid anchor constituent of glycoproteins and free glycosylinositolphospholipids (GIPLs). Inhibition of IPC and GIPLs biosynthesis impairs differentiation of trypomastigotes into the intracellular amastigote forms. The gene encoding IPC synthase in T. cruzi has been identified and the enzyme has been expressed in a cell-free system. The enzyme involved in IPC degradation and the remodelases responsible for the incorporation of ceramide into free GIPLs or into the glycosylphosphatidylinositols anchoring glycoproteins, and in fatty acid modifications of these molecules of T. cruzi have been understudied. Inositolphosphoceramide metabolism and remodeling could be exploited as targets for Chagas disease chemotherapy. 相似文献
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Miloslavich P Klein E Díaz JM Hernández CE Bigatti G Campos L Artigas F Castillo J Penchaszadeh PE Neill PE Carranza A Retana MV Díaz de Astarloa JM Lewis M Yorio P Piriz ML Rodríguez D Yoneshigue-Valentin Y Gamboa L Martín A 《PloS one》2011,6(1):e14631
The marine areas of South America (SA) include almost 30,000 km of coastline and encompass three different oceanic domains--the Caribbean, the Pacific, and the Atlantic--ranging in latitude from 12°N to 55°S. The 10 countries that border these coasts have different research capabilities and taxonomic traditions that affect taxonomic knowledge. This paper analyzes the status of knowledge of marine biodiversity in five subregions along the Atlantic and Pacific coasts of South America (SA): the Tropical East Pacific, the Humboldt Current,the Patagonian Shelf, the Brazilian Shelves, and the Tropical West Atlantic, and it provides a review of ecosystem threats and regional marine conservation strategies. South American marine biodiversity is least well known in the tropical subregions (with the exception of Costa Rica and Panama). Differences in total biodiversity were observed between the Atlantic and Pacific oceans at the same latitude. In the north of the continent, the Tropical East Pacific is richer in species than the Tropical West Atlantic, however, when standardized by coastal length, there is very little difference among them. In the south, the Humboldt Current system is much richer than the Patagonian Shelf. An analysis of endemism shows that 75% of the species are reported within only one of the SA regions, while about 22% of the species of SA are not reported elsewhere in the world. National and regional initiatives focusing on new exploration, especially to unknown areas and ecosystems, as well as collaboration among countries are fundamental to achieving the goal of completing inventories of species diversity and distribution.These inventories will allow accurate interpretation of the biogeography of its two oceanic coasts and latitudinal trends,and will also provide relevant information for science based policies. 相似文献