Artykuły w czasopismach na temat „Transport of nutrients”
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Burgoa, Nadia, Francisco Machín, Ángel Rodríguez-Santana, Ángeles Marrero-Díaz, Xosé Antón Álvarez-Salgado, Bieito Fernández-Castro, María Dolores Gelado-Caballero i Javier Arístegui. "Cape Verde Frontal Zone in summer 2017: lateral transports of mass, dissolved oxygen and inorganic nutrients". Ocean Science 17, nr 3 (11.06.2021): 769–88. http://dx.doi.org/10.5194/os-17-769-2021.
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Abstract. The circulation patterns in the confluence of the North Atlantic subtropical and tropical gyres delimited by the Cape Verde Front (CVF) were examined during a field cruise in summer 2017. We collected hydrographic data, dissolved oxygen (O2) and inorganic nutrients along the perimeter of a closed box embracing the Cape Verde Frontal Zone (CVFZ). The detailed spatial (horizontal and vertical) distribution of water masses, O2 and inorganic nutrients in the CVF was analyzed, allowing for the independent estimation of the transports of these properties in the subtropical and tropical domains down to 2000 m. Overall, at surface and central levels, a net westward transport of 3.76 Sv was observed, whereas at intermediate levels, a net 3 Sv transport northward was obtained. We observed O2 and inorganic nutrient imbalances in the domain consistent with O2 consumption and inorganic nutrient production by organic matter remineralization, resulting in a net transport of inorganic nutrients to the ocean interior by the circulation patterns.
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Doughty, Christopher E., Joe Roman, Søren Faurby, Adam Wolf, Alifa Haque, Elisabeth S. Bakker, Yadvinder Malhi, John B. Dunning i Jens-Christian Svenning. "Global nutrient transport in a world of giants". Proceedings of the National Academy of Sciences 113, nr 4 (26.10.2015): 868–73. http://dx.doi.org/10.1073/pnas.1502549112.
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The past was a world of giants, with abundant whales in the sea and large animals roaming the land. However, that world came to an end following massive late-Quaternary megafauna extinctions on land and widespread population reductions in great whale populations over the past few centuries. These losses are likely to have had important consequences for broad-scale nutrient cycling, because recent literature suggests that large animals disproportionately drive nutrient movement. We estimate that the capacity of animals to move nutrients away from concentration patches has decreased to about 8% of the preextinction value on land and about 5% of historic values in oceans. For phosphorus (P), a key nutrient, upward movement in the ocean by marine mammals is about 23% of its former capacity (previously about 340 million kg of P per year). Movements by seabirds and anadromous fish provide important transfer of nutrients from the sea to land, totalling ∼150 million kg of P per year globally in the past, a transfer that has declined to less than 4% of this value as a result of the decimation of seabird colonies and anadromous fish populations. We propose that in the past, marine mammals, seabirds, anadromous fish, and terrestrial animals likely formed an interlinked system recycling nutrients from the ocean depths to the continental interiors, with marine mammals moving nutrients from the deep sea to surface waters, seabirds and anadromous fish moving nutrients from the ocean to land, and large animals moving nutrients away from hotspots into the continental interior.
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MUSIELAK, MAGDALENA M., LEE KARP-BOSS, PETER A. JUMARS i LISA J. FAUCI. "Nutrient transport and acquisition by diatom chains in a moving fluid". Journal of Fluid Mechanics 638 (18.09.2009): 401–21. http://dx.doi.org/10.1017/s0022112009991108.
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The role of fluid motion in delivery of nutrients to phytoplankton cells is a fundamental question in biological and chemical oceanography. In the study of mass transfer to phytoplankton, diatoms are of particular interest. They are non-motile, are often the most abundant components in aggregates and often form chains, so they are the ones expected to benefit most from enhancement of nutrient flux due to dissipating turbulence. Experimental data to test the contribution of advection to nutrient acquisition by phytoplankton are scarce, mainly because of the inability to visualize, record and thus imitate fluid motions in the vicinities of cells in natural flows. Laboratory experiments have most often used steady Couette flows to simulate the effects of turbulence on plankton. However, steady flow, producing spatially uniform shear, fails to capture the diffusion of momentum and vorticity, the essence of turbulence. Thus, numerical modelling plays an important role in the study of effects of fluid motion on diffusive and advective nutrient fluxes. In this paper we use the immersed boundary method to model the interaction of rigid and flexible diatom chains with the surrounding fluid and nutrients. We examine this interaction in two nutrient regimes, a uniform background concentration of nutrients, such as might be typical of an early spring bloom, and a contrasting scenario in which nutrients are supplied as small, randomly distributed pulses, as is more likely for oligotrophic seas and summer conditions in coastal and boreal seas. We also vary the length and flexibility of chains, as whether chains are straight or bent, rigid or flexible will affect their behaviour in the flow and hence their nutrient fluxes. The results of numerical experiments suggest that stiff chains consume more nutrients than solitary cells. Stiff chains also experience larger nutrient fluxes compared to flexible chains, and the nutrient uptake per cell increases with increasing stiffness of the chain, suggesting a major advantage of silica frustules in diatoms.
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Burgoa, Nadia, Francisco Machín, Ángeles Marrero-Díaz, Ángel Rodríguez-Santana, Antonio Martínez-Marrero, Javier Arístegui i Carlos Manuel Duarte. "Mass, nutrients and dissolved organic carbon (DOC) lateral transports off northwest Africa during fall 2002 and spring 2003". Ocean Science 16, nr 2 (24.04.2020): 483–511. http://dx.doi.org/10.5194/os-16-483-2020.
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Abstract. The circulation patterns and the impact of the lateral export of nutrients and organic matter off NW Africa are examined by applying an inverse model to two hydrographic datasets gathered in fall 2002 and spring 2003. These estimates show significant changes in the circulation patterns at central levels from fall to spring, particularly in the southern boundary of the domain related to zonal shifts of the Cape Verde Frontal Zone. Southward transports at the surface and central levels at 26∘ N are 5.6±1.9 Sv in fall and increase to 6.7±1.6 Sv in spring; westward transports at 26∘ W are 6.0±1.8 Sv in fall and weaken to 4.0±1.8 Sv in spring. At 21∘ N a remarkable temporal variability is obtained, with a northward mass transport of 4.4±1.5 Sv in fall and a southward transport of 5.2±1.6 Sv in spring. At intermediate levels important spatiotemporal differences are also observed, and it must be highlighted that a northward net mass transport of 2.0±1.9 Sv is obtained in fall at both the south and north transects. The variability in the circulation patterns is also reflected in lateral transports of inorganic nutrients (SiO2, NO3, PO4) and dissolved organic carbon (DOC). Hence, in fall the area acts as a sink of inorganic nutrients and a source of DOC, while in spring it reverses to a source of inorganic nutrients and a sink of DOC. A comparison between nutrient fluxes from both in situ observations and numerical modeling output is finally addressed.
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Goldsztein, Guillermo H. "Transport of Nutrients in Bones". SIAM Journal on Applied Mathematics 65, nr 6 (styczeń 2005): 2128–40. http://dx.doi.org/10.1137/040616632.
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Liu, S. M., G. H. Hong, X. W. Ye, J. Zhang i X. L. Jiang. "Nutrient budgets for large Chinese estuaries and embayment". Biogeosciences Discussions 6, nr 1 (8.01.2009): 391–435. http://dx.doi.org/10.5194/bgd-6-391-2009.
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Abstract. Nutrient concentrations among the Chinese rivers and bays vary 10–75 fold depending on nutrient elements. The silicic acid levels in South China rivers are higher than those from North China rivers and the yields of dissolved silicate increased from the north to the south of China, indicating the effect of climate on weathering. The nutrient levels in Chinese rivers are higher than those from the large and less-disturbed world rivers such as Amazon and Zaire, but comparable to the values for European and North American polluted and eutrophic rivers like the Loire and Po. This may be ascribed to both of extensive leaching and influences from agricultural and domestic activities over the drainage basins of Chinese rivers. DIN:PO3−4 ratios in most of Chinese rivers and bays are higher (up to 2800) than the other rivers in the world. The atomic ratios of DIN to PO43− in the major Chinese rivers and embayment decrease in exponential trend with increase in the atomic ratios of PO43− to Si(OH)4, indicating that primary production in coastal environments changes with the nutrients transport when the urbanization develops to a certain extent, and the potential limited nutrient elements can be changed from phosphorus to nitrogen limitation, which can modify aquatic food webs and then the ocean ecosystem. A simple steady-state mass-balance box model was employed. The output shows that the estuaries and embayment behave as a sink or source of nutrients. For the major Chinese estuaries, both residual and mixing flow transport nutrients off the estuaries, and nutrient transport fluxes in summer is 3–4 fold that in winter except comparable for NH4+. These fluxes are 1.0–1.7 fold that estimated by timing riverine nutrient concentrations and freshwater discharge. For the major Chinese embayment, nutrient elements are transported to China Seas except PO43− and Si(OH)4 in Sanggou Bay and Jiaozhou Bay. Seasonally, nutrients transport fluxes off the bays in the summer are 2.2–7.0 fold that in the winter. In the embayment, the exchange flow dominated the water budgets, resulting in average system salinity approaching the China seas salinity where river discharge is limited. The major Chinese estuaries and embayment transport 1.0–3.1% of nitrogen, 0.2–0.5% of phosphorus and 3% of silicon necessary for phytoplankton growth for the China Seas. This demonstrates regenerated nutrients in water column and sediments and nutrients transport fluxes between the China Seas and open ocean play an important role for phytoplankton growth. Atmospheric deposition may be another important source of nutrients for the China Seas.
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Havlin, John, i Ron Heiniger. "Soil Fertility Management for Better Crop Production". Agronomy 10, nr 9 (8.09.2020): 1349. http://dx.doi.org/10.3390/agronomy10091349.
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Increasing crop productivity per unit of land area to meet future food and fiber demand increases both soil nutrient removal and the importance of replenishing soil fertility through efficient nutrient management practices. Significant progress in enhancing nutrient-use efficiency in production agriculture requires improved estimates of plant-available nutrients in the root zone, enhanced crop response to applied nutrients, and reduced offsite nutrient transport. This special issue, Soil Fertility Management for Better Crop Production, presents 15 manuscripts that advance our knowledge of interrelated soil, plant, and management factors important to increasing the nutrient availability and crop recovery of applied nutrients.
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Mahmood-Ul-Hassan, Muhammad, Muhammad Rashid i Ejaz Rafique. "Nutrients transport through variably structured soils". Soil Science and Plant Nutrition 57, nr 2 (kwiecień 2011): 331–40. http://dx.doi.org/10.1080/00380768.2011.559576.
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Pardridge, William M. "BLOOD-BRAIN BARRIER TRANSPORT OF NUTRIENTS". Nutrition Reviews 44 (27.04.2009): 15–25. http://dx.doi.org/10.1111/j.1753-4887.1986.tb07674.x.
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Moore, Jonathan W., i Daniel E. Schindler. "Nutrient export from freshwater ecosystems by anadromous sockeye salmon (Oncorhynchus nerka)". Canadian Journal of Fisheries and Aquatic Sciences 61, nr 9 (1.09.2004): 1582–89. http://dx.doi.org/10.1139/f04-103.
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Anadromous and semelparous salmon transport nutrients from the ocean to fresh waters when they return to spawn and die, a process inspiring a large body of research on the role of salmon-derived nutrients in coastal ecosystems. However, salmon also transport nutrients out of fresh waters when they migrate to the ocean as smolts. Using a total of 76 years of age-specific smolt-migration and adult-escapement data, we calculated the amounts of nitrogen and phosphorus that sockeye salmon (Oncorhynchus nerka) imported and exported from four major systems in Bristol Bay, Alaska. Smolts removed an average of 16% of the phosphorus and 12% of the nitrogen that their parents transported into fresh waters. The percentage of parental nutrients that smolts exported varied through time and among sites, ranging from 1% to 65% of the phosphorus and from less than 1% to 47% of the nitrogen. In systems where smolts were larger, they exported a higher percentage of nutrients. Depending on the strength of density-dependence, smolts could theoretically export more nutrients than their parents import to freshwater ecosystems at low spawning densities. Ignoring nutrient export by outgoing smolts will consistently lead to overestimation of nutrient import by Pacific salmon to freshwater ecosystems.
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Hall, Jr., Robert, i Jennifer Tank. "Relating Transient Storage and Whole-System Metabolism with Nitrogen Uptake in Streams". UW National Parks Service Research Station Annual Reports 23 (1.01.1999): 93–97. http://dx.doi.org/10.13001/uwnpsrc.1999.3379.
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Streams are important landscape features because they provide an avenue for nitrogen loss from a watershed to downstream ecosystems and eventually the ocean; however, in-stream processes can control nutrient transport and export (e.g. Burns 1998). Nitrogen is an important element because it limits rates of primary production in many terrestrial and aquatic ecosystems. Alteration of the forms, timing, and concentration of nutrients is a central property of lotic systems (Fisher et al. 1998). Understanding controls on both transport and retention are central to predicting how streams influence nutrient loss from watersheds (Hedin et al. 1995, Likens and Bormann 1995, Burns 1998) and nutrient loading to downstream ecosystems (Howarth et al. 1996). With increased global nutrient loading from atmospheric sources and fertilizers, streams may play an important role in the retention, transformation and export of nutrients from the upland landscape. We know little about what controls nutrient uptake and transport in streams. There are many studies that show effects of hydrologic, biologic, and geomorphic influences on nutrient transport, but rarely have all aspects been considered in the same study. One potentially important geomorphic control is transient storage. Transient storage is water that is separated from the main channel flow and therefore, moves downstream more slowly than water in the main stream channel, which should facilitate nutrient uptake. Transient storage has been suggested to play an important role in nutrient retention in streams from both theoretical (Mulholland and DeAngelis 2000) and empirical perspectives (Valett et al. 1996, Mulholland et al. 1997). Additionally no studies have linked whole stream measures of metabolism with stream nutrient uptake, though we expect that greater C fixation or respiration will cause higher demand for nutrients. The objective of our study was to relate nutrient uptake with geomorphic and whole stream metabolism in 8 streams in Grand Teton National Park.
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Ferraris, R. P., i J. Diamond. "Regulation of intestinal sugar transport". Physiological Reviews 77, nr 1 (1.01.1997): 257–302. http://dx.doi.org/10.1152/physrev.1997.77.1.257.
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The recent surge in knowledge of cellular and molecular mechanisms of intestinal sugar transport has fueled an enormous interest in adaptive mechanisms regulating sugar transport. We first review several functional considerations that help us interpret the different patterns of adaptation for different nutrients. We then distinguish nonspecific adaptive mechanisms leading to parallel changes in transport of different nutrients from specific adaptive mechanisms only affecting the transport of a single nutrient. Nonspecific adaptive mechanisms include changes in mucosal surface area and in the ratio of transporting to nontransporting cells; specific mechanisms include changes in site density of transporters and in affinity constants. We also enumerate the patterns of regulation and describe how sugar transport is affected by changes in diet, energy budgets, and environmental salinity as well as by intestinal resection, starvation, stress, and age. We relate the various signals linking these stimuli to adaptive mechanisms and make predictions about the nature of these signals. Finally, we describe the significance of the interactions among sugar, fluid, and electrolyte transport mechanisms and of the paracellular pathway to transepithelial transport of sugars. We close by drawing attention to promising directions for future research.
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Tiani, Kendra A., Patrick J. Stover i Martha S. Field. "The Role of Brain Barriers in Maintaining Brain Vitamin Levels". Annual Review of Nutrition 39, nr 1 (21.08.2019): 147–73. http://dx.doi.org/10.1146/annurev-nutr-082018-124235.
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It is increasingly recognized that tissue-specific nutrient deficiencies can exist in the absence of whole-body deficiency and that these deficiencies may result from disease or disease-related physiological processes. Brain and central nervous system tissues require adequate nutrient levels to function. Many nutrients are concentrated in the cerebrospinal fluid relative to the serum in healthy individuals, and other nutrients resist depletion in the presence of whole-body nutrient depletion. The endothelial, epithelial, and arachnoid brain barriers work in concert to selectively transport, concentrate, and maintain levels of the specific nutrients required by the brain while also blocking the passage of blood-borne toxins and pathogens to brain and central nervous system tissues. These barriers preserve nutrient levels within the brain and actively concentrate nutrients within the cerebrospinal fluid and brain. The roles of physical and energetic barriers, including the blood–brain and blood–nerve barriers, in maintaining brain nutrient levels in health and disease are discussed.
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Sundaram, Shanmuga, i Alip Borthakur. "Altered intestinal epithelial nutrient transport: an underappreciated factor in obesity modulated by diet and microbiota". Biochemical Journal 478, nr 5 (4.03.2021): 975–95. http://dx.doi.org/10.1042/bcj20200902.
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Dietary nutrients absorbed in the proximal small intestine and assimilated in different tissues have a profound effect on overall energy homeostasis, determined by a balance between body's energy intake and expenditure. In obesity, altered intestinal absorption and consequently tissue assimilation of nutrients may disturb the energy balance leading to metabolic abnormalities at the cellular level. The absorption of nutrients such as sugars, amino acids and fatty acids released from food digestion require high-capacity transporter proteins expressed in the intestinal epithelial absorptive cells. Furthermore, nutrient sensing by specific transporters/receptors expressed in the epithelial enteroendocrine cells triggers release of gut hormones involved in regulating energy homeostasis via their effects on appetite and food intake. Therefore, the intestinal epithelial cells play a pivotal role in the pathophysiology of obesity and associated complications. Over the past decade, gut microbiota has emerged as a key factor contributing to obesity via its effects on digestion and absorption of nutrients in the small intestine, and energy harvest from dietary fiber, undigested component of food, in the large intestine. Various mechanisms of microbiota effects on obesity have been implicated. However, the impact of obesity-associated microbiota on the intestinal nutrient transporters needs extensive investigation. This review marshals the limited studies addressing the altered structure and function of the gut epithelium in obesity with special emphasis on nutrient transporters and role of diet and microbiota. The review also discusses the thoughts and controversies and research gaps in this field.
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Ruiz-Palacios, María, Antonio José Ruiz-Alcaraz, María Sanchez-Campillo i Elvira Larqué. "Role of Insulin in Placental Transport of Nutrients in Gestational Diabetes Mellitus". Annals of Nutrition and Metabolism 70, nr 1 (2017): 16–25. http://dx.doi.org/10.1159/000455904.
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Background: Gestational diabetes mellitus (GDM) is associated with increased fetal adiposity, which may increase the risk of obesity in adulthood. The placenta has insulin receptors and maternal insulin can activate its signaling pathways, affecting the transport of nutrients to the fetus. However, the effects of diet or insulin treatment on the placental pathophysiology of GDM are unknown. Summary: There are very few studies on possible defects in the insulin signaling pathway in the GDM placenta. Such defects could influence the placental transport of nutrients to the fetus. In this review we discuss the state of insulin signaling pathways in placentas of women with GDM, as well as the role of exogenous insulin in placental nutrient transport to the fetus, and fetal adiposity. Key Messages: Maternal insulin in the third trimester is correlated with fetal abdominal circumference at that time, suggesting the important role of insulin in this process. Since treatment with insulin at the end of pregnancy may activate placental nutrient transport to the fetus and promote placental fatty acid transfer, it would be interesting to improve maternal hyperlipidemia control in GDM subjects treated with this hormone. More research in this area with high number of subjects is necessary.
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Smith, FA, i SE Smith. "Membrane Transport at the Biotrophic Interface: an Overview". Functional Plant Biology 16, nr 1 (1989): 33. http://dx.doi.org/10.1071/pp9890033.
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Many studies of interactions between the organisms which form biotrophic symbioses have concentrated on extracellular events such as signals and responses that involve modifications to cell wall metabolism. It is clear, however, that formation of a biotrophic association must also involve signals and responses at the membrane level and modifications to membrane activity resulting in changes in the transfer of nutrients. In parasitic biotrophs the modifications to membrane transport result in unidirectional transport (at least in the long term). In mycorrhizal associations, lichens and N2-fixing symbioses, it appears that well regulated bidirectional transport of nutrients between symbionts must occur, thus allowing a persistent compatible (and mutualistic) symbiosis. Evidence for such membrane modifications comes from changes in ATPase activity. The overall question to be considered in mutualistic symbioses is whether nutrient transfer processes have analogies elsewhere in the physiology of plants or whether 'new' transport events are switched on as a result of interactions between the organisms.
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Rubin, Bruce K., Chris I. Cheeseman, Sita Gourishankar i Malcolm King. "Is there a seasonal variation in mucus transport and nutrient absorption in the leopard frog?" Canadian Journal of Physiology and Pharmacology 70, nr 4 (1.04.1992): 442–46. http://dx.doi.org/10.1139/y92-056.
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We postulated that as a hibernating species, frogs might have variable demands for nutrients at different seasons of the year and that this must be reflected in seasonal variations of physiologic processes related to nutrient transport and absorption. We examined the rate of mucus transport on the ciliated palate and the movement of nutrients across the intestinal lumen of leopard frogs, Rana pipiens. Mucus transport on the frog palate was strongly influenced by season, with maximal transport occurring in late June (Julian day 178, p = 0.0001; r = 0.58). This increased transport rate was associated with a summertime increase in mucus recoil (lower tangent δ) and a decrease in mucus hydration (increase in percent solids composition). Intestinal transport of leucine, lysine, and galactose did not appear to exhibit seasonal variability. These data suggest that different mechanisms may operate in determining seasonal variability in physiologic responses.Key words: mucociliary clearance, mucus viscoelasticity, intestinal absorption, Anura, seasonal variation.
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Baker, Alex R., Maria Kanakidou, Athanasios Nenes, Stelios Myriokefalitakis, Peter L. Croot, Robert A. Duce, Yuan Gao i in. "Changing atmospheric acidity as a modulator of nutrient deposition and ocean biogeochemistry". Science Advances 7, nr 28 (lipiec 2021): eabd8800. http://dx.doi.org/10.1126/sciadv.abd8800.
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Anthropogenic emissions to the atmosphere have increased the flux of nutrients, especially nitrogen, to the ocean, but they have also altered the acidity of aerosol, cloud water, and precipitation over much of the marine atmosphere. For nitrogen, acidity-driven changes in chemical speciation result in altered partitioning between the gas and particulate phases that subsequently affect long-range transport. Other important nutrients, notably iron and phosphorus, are affected, because their soluble fractions increase upon exposure to acidic environments during atmospheric transport. These changes affect the magnitude, distribution, and deposition mode of individual nutrients supplied to the ocean, the extent to which nutrient deposition interacts with the sea surface microlayer during its passage into bulk seawater, and the relative abundances of soluble nutrients in atmospheric deposition. Atmospheric acidity change therefore affects ecosystem composition, in addition to overall marine productivity, and these effects will continue to evolve with changing anthropogenic emissions in the future.
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Lager, Susanne, i Theresa L. Powell. "Regulation of Nutrient Transport across the Placenta". Journal of Pregnancy 2012 (2012): 1–14. http://dx.doi.org/10.1155/2012/179827.
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Abnormal fetal growth, both growth restriction and overgrowth, is associated with perinatal complications and an increased risk of metabolic and cardiovascular disease later in life. Fetal growth is dependent on nutrient availability, which in turn is related to the capacity of the placenta to transport these nutrients. The activity of a range of nutrient transporters has been reported to be decreased in placentas of growth restricted fetuses, whereas at least some studies indicate that placental nutrient transport is upregulated in fetal overgrowth. These findings suggest that changes in placental nutrient transport may directly contribute to the development of abnormal fetal growth. Detailed information on the mechanisms by which placental nutrient transporters are regulated will therefore help us to better understand how important pregnancy complications develop and may provide a foundation for designing novel intervention strategies. In this paper we will focus on recent studies of regulatory mechanisms that modulate placental transport of amino acids, fatty acids, and glucose.
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Bannink, A., J. Dijkstra, S. J. Koopmans i Z. Mroz. "Physiology, regulation and multifunctional activity of the gut wall: a rationale for multicompartmental modelling". Nutrition Research Reviews 19, nr 2 (grudzień 2006): 227–53. http://dx.doi.org/10.1017/s0954422407334094.
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A rationale is given for a modelling approach to identify the mechanisms involved in the functioning and metabolic activity of tissues in the wall of the gastrointestinal tract. Maintenance and productive functions are discussed and related to the distinct compartments of the gastrointestinal tract and the metabolic costs involved. Functions identified are: tissue turnover; tissue proliferation; ion transport; nutrient transport; secretions of digestive enzymes, mucus and immunoglobulins; production of immune cells. The major nutrients involved include glucose, amino acids and volatile fatty acids.In vivomeasurements of net portal fluxes of these nutrients in pigs and ruminants are evaluated to illustrate the complexity of physiology and metabolic activity of the gastrointestinal tract. Experimental evidence indicates that high, but variable and specific, nutrient costs are involved in the functioning of the gastrointestinal tract.
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Xu, Guohua. "Sensing and transport of nutrients in plants". Seminars in Cell & Developmental Biology 74 (luty 2018): 78–79. http://dx.doi.org/10.1016/j.semcdb.2017.09.020.
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Kannan, Seshadri, i Andre Charnel. "Foliar absorption and transport of inorganic nutrients". Critical Reviews in Plant Sciences 4, nr 4 (styczeń 1986): 341–75. http://dx.doi.org/10.1080/07352688609382231.
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Segal, Malcolm B. "Transport of nutrients across the choroid plexus". Microscopy Research and Technique 52, nr 1 (2000): 38–48. http://dx.doi.org/10.1002/1097-0029(20010101)52:1<38::aid-jemt6>3.0.co;2-j.
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Hay, Jr., William W. "Placental Transport of Nutrients to the Fetus". Hormone Research 42, nr 4-5 (1994): 215–22. http://dx.doi.org/10.1159/000184196.
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Zhao, L., i X. Guo. "Influence of cross-shelf water transport on nutrients and phytoplankton in the East China Sea: a model study". Ocean Science 7, nr 1 (17.01.2011): 27–43. http://dx.doi.org/10.5194/os-7-27-2011.
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Abstract. A three dimensional coupled biophysical model was used to examine the supply of oceanic nutrients to the shelf of the East China Sea (ECS) and its role in primary production over the shelf. The model consisted of two parts: the hydrodynamic module was based on a nested model with a horizontal resolution of 1/18 degree, whereas the biological module was a lower trophic level ecosystem model including two types of phytoplankton, three elements of nutrients, and biogenic organic material. The model results suggested that seasonal variations occurred in the distribution of nutrients and chlorophyll a over the shelf of the ECS. After comparison with available observed nutrients and chlorophyll a data, the model results were used to calculate volume and nutrients fluxes across the shelf break. The annual mean total fluxes were 1.53 Sv for volume, 9.4 kmol s−1 for DIN, 0.7 kmol s−1 for DIP, and 18.2 kmol s−1 for silicate. Two areas, northeast of Taiwan and southwest of Kyushu, were found to be major source regions of oceanic nutrients to the shelf. Although the onshore fluxes of nutrients and volume both had apparent seasonal variations, the seasonal variation of the onshore nutrient flux did not exactly follow that of the onshore volume flux. Additional calculations in which the concentration of nutrients in Kuroshio water was artificially increased suggested that the oceanic nutrients were distributed in the bottom layer from the shelf break to the region offshore of the Changjiang estuary from spring to summer and appeared in the surface layer from autumn to winter. The calculations also implied that the supply of oceanic nutrients to the shelf can change the consumption of pre-existing nutrients from rivers. The response of primary production over the shelf to the oceanic nutrients was confirmed not only in the surface layer (mainly at the outer shelf and shelf break in winter and in the region offshore of the Changjiang estuary in summer) but also in the subsurface layer over the shelf from spring to autumn.
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Hofmann, Julia, i Florian Grundler. "How do nematodes get their sweets? Solute supply to sedentary plant-parasitic nematodes". Nematology 9, nr 4 (2007): 451–58. http://dx.doi.org/10.1163/156854107781487305.
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AbstractSedentary cyst and root-knot nematodes withdraw large amounts of solutes from feeding structures induced in host roots. The feeding structures are specialised cells with a high metabolic activity and a tremendous capacity in translocation of nutrients. The required nutrients are provided by the plant transport systems – water and inorganic solutes from the xylem, assimilates such as sugars and amino acids from the phloem. Here we discuss the available data on the mechanisms by which nutrients are translocated into the nematode feeding sites. The interaction between Heterodera schachtii and Arabidopsis thaliana serves as a model system for cyst nematodes. In this case sufficient data are available to propose a conclusive concept for the mechanisms of nutrient flow: basically, in the early stages of nematode development syncytia are symplasmically isolated, so that transport proteins are responsible for the nutrient supply. Later, connections to the phloem via plasmodesmata are established, so that developing females are well supplied with assimilates. The interactions of root-knot nematodes with their hosts share a number of similarities but the data currently available are not sufficient to draw similar conclusions. As nutrient supply and functionality of feeding structures are the basis of biotrophic parasitism of sedentary nematodes, it is tempting to unravel the mechanisms by which both plant and nematodes influence each other via nutrient fluxes.
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Kinoshita, Takafumi, i Masaharu Masuda. "Differential Nutrient Uptake and Its Transport in Tomato Plants on Different Fertilizer Regimens". HortScience 46, nr 8 (sierpień 2011): 1170–75. http://dx.doi.org/10.21273/hortsci.46.8.1170.
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Application of controlled-release fertilizer (CRF) to a root-proof capillary wick irrigation system (a type of subirrigation method) has both economical and environmental benefits, because it does not require any equipment for fertigation and minimizes water leaching. In this study, we examined the effects of CRF and liquid fertilizer (LF), a conventional fertigation method, on fruit production and nutrient uptake and transport in forcing tomato cultures for harvesting 15 trusses per plant from October to June. No significant difference was noted in marketable fruit yield between CRF- and LF-treated plants. The quantity of nutrient uptake per plant and per fruit yield was lower with CRF than with LF, indicating that nutrients were used more efficiently for fruit production in plants grown with CRF. Analysis of the volume and mineral concentrations of xylem exudates indicated that the amount of nutrients absorbed was greater with LF than with CRF, particularly after the tenth truss was harvested. Mineral concentrations in the substrate solution of CRF-treated plants were initially higher than those in the substrate solution of LF-treated plants but extremely low after the second truss was harvested, whereas mineral concentrations in the xylem exudates were similar in CRF and LF plants until the eighth truss was harvested. Thus, the difference in mineral concentrations between the xylem exudates and substrate solution was much larger in the case of CRF than in the case of LF, indicating that the plants absorbed the bulk of nutrients immediately after their release from the CRF surface. Therefore, CRF is suitable in this system, because it combines high fruit production with high nutrient utilization efficiency.
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Sims, J. T., N. Goggin i J. McDermott. "Nutrient management for water quality protection: integrating research into environmental policy". Water Science and Technology 39, nr 12 (1.06.1999): 291–98. http://dx.doi.org/10.2166/wst.1999.0558.
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Agriculture's impacts on water quality have been the focus of basic and applied research in Delaware for more than 25 years. Research has examined nutrient cycling in soils, nutrient transport from soils to water, and the environmental consequences of ground water contamination and surface water eutrophication by nutrients. Much of the research has specifically been oriented towards the development of agricultural management practices to prevent the degradation of water quality by nutrients. Other research has focused on increasing our understanding of the chemical, physical, and biological processes that control nutrient cycling and transport and improving the monitoring techniques needed to document how changing management practices affects water quality. Agencies responsible for water quality protection have sought to integrate this research into environmental policy, but have often been frustrated by the fragmented and sometimes contradictory nature of the information provided to them. This paper reviews key advances in research on nutrient management and water quality in Delaware and discusses the obstacles faced in translating research into widely accepted management practices and environmental policies.
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Han, A. Q., M. H. Dai, J. P. Gan, S. J. Kao, X. Z. Zhao, S. Jan, Q. Li i in. "Inter-shelf nutrient transport from the East China Sea as a major nutrient source supporting winter primary production on the northeast South China Sea shelf". Biogeosciences 10, nr 12 (11.12.2013): 8159–70. http://dx.doi.org/10.5194/bg-10-8159-2013.
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Abstract. The East China Sea (ECS) and the South China Sea (SCS) are two major marginal seas of the North Pacific with distinct seasonal variations of primary productivity. Based upon field observations covering both the ECS and the northern SCS (NSCS) during December 2008–January 2009, we examined southward long-range transport of nutrients from the ECS to the northeastern SCS (NESCS) carried by the China Coastal Current (CCC) driven by the prevailing northeast monsoon in wintertime. These escaped nutrients from the ECS shelf, where primary production (PP) was limited in winter, might however refuel the PP on the NESCS shelf at lower latitude, where the water temperature remained favorable, but river-sourced nutrients were limited. By combining the field observation of nitrate+nitrite (NO3+NO2, DIN) with our best estimate of volume transport of the CCC, we derived a first-order estimate for DIN flux of 1430 ± 1024 mol s−1. Under the assumption that DIN was the limiting nutrient, such southward DIN transport would have stimulated 8.84 ± 6.33 × 1011 gC of new production (NP), accounting for 33–74% of the NP or 14–22% of PP in winter on the NESCS shelf shallower than 100 m.
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Blewett, Tamzin A., i Greg G. Goss. "A novel pathway of nutrient absorption in crustaceans: branchial amino acid uptake in the green shore crab ( Carcinus maenas )". Proceedings of the Royal Society B: Biological Sciences 284, nr 1868 (6.12.2017): 20171298. http://dx.doi.org/10.1098/rspb.2017.1298.
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Estuaries are environments enriched with dissolved nutrients such as amino acids. To date, marine arthropods are the only invertebrate group that have not been demonstrated to access this potentially important nutrient resource. Using in vitro gill perfusion techniques, we sought to investigate the ability of the green shore crab ( Carcinus maenas ) to take up the amino acid l -leucine directly from the water. Investigation of the concentration-dependent transport kinetics of radiolabelled l -leucine showed that there are two specific transport pathways across Carcinus gills, one with high affinity and low capacity, and the other with high capacity and low affinity. Using putative competitive substrates and reduced sodium preparations, we were able to identify the putative amino acid transport system associated with high-affinity uptake. This is the first study to demonstrate the absorption of dissolved organic nutrients across the gill epithelium of a marine arthropod.
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Nabilla, Sarah, Retno Hartati i Ria Azizah Tri Nuraini. "Hubungan Nutrien Pada Sedimen dan Penutupan Lamun Di Perairan Jepara". Jurnal Kelautan Tropis 22, nr 1 (13.04.2019): 42. http://dx.doi.org/10.14710/jkt.v22i1.4252.
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The availability of nutrients in seagrass beds can act as growth limiting factors. Absorption of nutrients in the water column is carried out by the leaves while the absorption of nutrients from the sediment is carried out by the roots but does not rule out the transport of nutrients by the roots will also arrive at the leaves of the seagrass. If the nutrient requirement is not met properly, then the growth will be disrupted. Like the difference in distribution and density of seagrass itself. Nutrient concentrations in waters vary. Nitrate and phosphate levels in the waters are strongly influenced by sources of organic material from outside/land (allochthonous) or from the water itself (autocthonous). This research was conducted with the aim of nothing: to determine the relationship between nutrient content (nitrate and phosphate) in sediment to seagrass cover in Teluk Awur and Pantai Blebak, JeparaData collection of seagrass and sediment was carried out on March 2018 in the waters of Teluk Awur and Blebak Beach, Kabupaten Jepara. Type identification, density, and coverage are carried out at the research location. Nitrate and phosphate analysis in sediments is carried out in Laboratorium Pengujian dan Peralatan. Based on the results of research that has been carried out, it can be concluded that there is a very strong positive relationship between nutrients and seagrass closure in the two research locations, each of which is 0.955 (91.1%) in Teluk Awur waters and 0.962 (92.6%) in Blebak Beach.Ketersediaan nutrien di perairan padang lamun dapat berperan sebagai faktor pembatas pertumbuhan. Penyerapan nutrien pada lamun pada kolom air dilakukan oleh daun sedangkan penyerapan nutrien dari sedimen dilakukan oleh akar namun tidak menutup kemungkinan pengangkutan nutrien oleh akar juga akan sampai pada bagian daun. Jika kebutuhan nutrien tidak terpenuhi dengan baik, maka pertumbuhannya mengalami gangguan. Seperti perbedaan sebaran dan kepadatan lamun itu sendiri. Konsentrasi nutrien di perairan bervariasi. Kadar nitrat dan fosfat di perairan sangat dipengaruhi oleh sumber bahan organik yang berasal dari luar/ daratan (allochthonous) maupun dari dalam perairan itu sendiri (autocthonous). Penelitian ini dilakukan dengan tujuan: untuk mengetahui hubungan antara kandungan nutrien (nitrat dan fosfat) pada sedimen terhadap tutupan lamun di Teluk Awur dan Pantai Blebak, Jepara. Identifikasi jenis, kepadatan dan penutupan dilakukan pada lokasi penelitian. Analisa nitrat dan fosfat dalam sedimen dilakukan di Laboratorium Pengujian dan Peralatan. Berdasarkan hasil penelitian yang telah dilakukan dapat di ambil kesimpulan bahwa terdapat hubungan sangat kuat positif antara nutrien dengan penutupan lamun pada dua lokasi penelitian, nilainya masing-masing sebesar 0,955 (91,1%) di Perairan Teluk Awur dan 0,962 (92,6%) di Pantai Blebak.
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Han, A., M. Dai, J. Gan, S. J. Kao, X. Zhao, S. Jan, Q. Li i in. "Inter-shelf nutrient transport from the East China Sea as a major nutrient source supporting winter primary production on the northeast South China Sea shelf". Biogeosciences Discussions 10, nr 2 (28.02.2013): 3891–923. http://dx.doi.org/10.5194/bgd-10-3891-2013.
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Abstract. The East China Sea (ECS) and the South China Sea (SCS) are two major marginal seas of the north Pacific with distinct seasonal primary productivity. Based upon field observation in December 2008–January 2009 covering both the ECS and the northern SCS (NSCS) in wintertime, we examined southward long-range nutrient-transport from the ECS to the northeast SCS (NESCS) carried by the China Coastal Current (CCC) driven by the northeast prevailing monsoon. These nutrients escaped from the cold ECS shelf to refuel the primary production on the NESCS shelf where river-sourced nutrients were limited yet water temperature remained favorable. By coupling the field observation of nitrate + nitrite (DIN) with the volume transport of the CCC, we derived a first order estimate of DIN flux of ~ 1430 ± 260 mol s−1. This DIN flux was ~ 7 times the wintertime DIN input from the Pearl River, a primary riverine nutrient source to the NSCS. By assuming DIN was the limiting nutrient, such southward DIN transport would have stimulated ~ 8.8 ± 1.6 × 1011 gC of new production (NP), accounting for ~ > 58 ± 10% of the total NP or ~ 38 ± 7–24 ± 4% of primary production on the NESCS shelf shallower than 100 m.
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Sundarambal, P., P. Tkalich i R. Balasubramanian. "Modelling the effect of atmospheric nitrogen deposition on marine phytoplankton in the Singapore Strait". Water Science and Technology 61, nr 4 (1.02.2010): 859–67. http://dx.doi.org/10.2166/wst.2010.357.
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Atmospheric deposition is an important source of nutrients to the ocean, potentially stimulating primary production, but its relative effect on coastal eutrophication remains largely unknown. This paper presents data generated by the 3-D modelling program NEUTRO to assess the proportion of atmospheric nutrient fluxes, allowing a quantification of the relative contribution of atmospheric and ocean fluxes in the Singapore Strait. This work included an assessment of the importance of high concentration episodic inputs of nitrate-nitrogen associated with transport of polluted air onto the surface water. The NEUTRO model features a nutrient-fuelled food web composed of nutrients, plankton, and dissolved oxygen dynamics. Model simulations show that atmospheric deposition fluxes alone might contribute nitrate-nitrogen mass up to 15% into the Singapore Strait. This amount might be a significant contributor toward regional eutrophication when the system is under nutrient-depleted conditions. Model calibrations for temporal and spatial variability of nutrients qualitatively and quantitatively agreed with available measurements.
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Bolton, S. M., T. J. Ward i R. A. Cole. "Sediment‐Related Transport of Nutrients from Southwestern Watersheds". Journal of Irrigation and Drainage Engineering 117, nr 5 (wrzesień 1991): 736–47. http://dx.doi.org/10.1061/(asce)0733-9437(1991)117:5(736).
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Beaumont, N. J. "Modelling the Transport of Nutrients in Early Animals". Evolutionary Biology 36, nr 2 (10.01.2009): 256–66. http://dx.doi.org/10.1007/s11692-008-9047-2.
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Tran, M. L., J. Bahng, S. Pankratz i I. H. Suffet. "Transport of nutrients and eutrophication control by an urban runoff diversion system protecting a drinking water reservoir". Water Supply 8, nr 2 (1.07.2008): 173–80. http://dx.doi.org/10.2166/ws.2008.062.
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Urban runoff from five storms during the 2003–2004 and 2004–2005 rainy seasons was sampled at the exit point of runoff diversion forebays leading to engineered retention ponds to protect a drinking water reservoir. Samples were collected from three different drainage areas both years and were analysed for water quality parameters including total dissolved solids, electrical conductivity (EC), dissolved organic carbon, bacterial count and nutrients in the water phase. In the second year of the study, samples were also taken at the entry point into the forebays and analysed to determine if the forebays contributed to removal of analytes prior to diversion in the retention ponds. EC, which had been used as the determining factor of whether runoff is used to recharge or diverted to holding ponds, did not relate to nutrient levels. This indicated that EC is insufficient to determine water quality because runoff with low EC may contain high levels of nutrients that can support eutrophication. Monitoring of nutrients themselves is essential for decisions.
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Fernandes, Lina L., Pratima M. Kessarkar, Suresh Suja, Durbar Ray i Mithila Bhat. "Seasonal variations in the water quality of six tropical micro- and mesotidal estuaries along the central west coast of India". Marine and Freshwater Research 69, nr 9 (2018): 1418. http://dx.doi.org/10.1071/mf17181.
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Seasonal nutrient dynamics were investigated in four rivers with a microtidal range (Terekhol, Chapora, Sal and Talpona rivers) and were compared with those of two rivers with a mesotidal range (Zuari and Mandovi rivers) along the central west coast of India. Rainfall and freshwater discharge during the wet season led to salinity stratification of the water columns at the mouths of these rivers. Nutrient concentrations in all rivers were higher during the wet season than in the dry season due to considerable land run-off. Based on the estuarine mixing diagrams of the nutrients with regard to salinity, the mesotidal rivers showed greater flushing capacity and acted as corridors for the passage of nutrients between the estuary and open ocean. Conversely, of the microtidal rivers, the Terekhol and Chapora seemed to retain nutrients, whereas there was no indication of the presence of a nutrient sink or source in the Talpona River. The Sal River was eutrophic with high nutrient levels and acted as a source of phosphorus and nitrogen. Thus, the present study clearly illustrates the important role played by minor river estuaries in modifying nutrient concentrations during their transport from rivers to coastal waters and vice versa.
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Zhang, Wen-Hao, Yuchan Zhou, Katherine E. Dibley, Stephen D. Tyerman, Robert T. Furbank i John W. Patrick. "Review: Nutrient loading of developing seeds". Functional Plant Biology 34, nr 4 (2007): 314. http://dx.doi.org/10.1071/fp06271.
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Interest in nutrient loading of seeds is fuelled by its central importance to plant reproductive success and human nutrition. Rates of nutrient loading, imported through the phloem, are regulated by transport and transfer processes located in sources (leaves, stems, reproductive structures), phloem pathway and seed sinks. During the early phases of seed development, most control is likely to be imposed by a low conductive pathway of differentiating phloem cells serving developing seeds. Following the onset of storage product accumulation by seeds, and, depending on nutrient species, dominance of path control gives way to regulation by processes located in sources (nitrogen, sulfur, minor minerals), phloem path (transition elements) or seed sinks (sugars and major mineral elements, such as potassium). Nutrients and accompanying water are imported into maternal seed tissues and unloaded from the conducting sieve elements into an extensive post-phloem symplasmic domain. Nutrients are released from this symplasmic domain into the seed apoplasm by poorly understood membrane transport mechanisms. As seed development progresses, increasing volumes of imported phloem water are recycled back to the parent plant by process(es) yet to be discovered. However, aquaporins concentrated in vascular and surrounding parenchyma cells of legume seed coats could provide a gated pathway of water movement in these tissues. Filial cells, abutting the maternal tissues, take up nutrients from the seed apoplasm by membrane proteins that include sucrose and amino acid/H+ symporters functioning in parallel with non-selective cation channels. Filial demand for nutrients, that comprise the major osmotic species, is integrated with their release and phloem import by a turgor-homeostat mechanism located in maternal seed tissues. It is speculated that turgors of maternal unloading cells are sensed by the cytoskeleton and transduced by calcium signalling cascades.
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Nislow, Keith H., John D. Armstrong i Simon McKelvey. "Phosphorus flux due to Atlantic salmon (Salmo salar) in an oligotrophic upland stream: effects of management and demography". Canadian Journal of Fisheries and Aquatic Sciences 61, nr 12 (1.12.2004): 2401–10. http://dx.doi.org/10.1139/f05-006.
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Little is known concerning the role of Atlantic salmon (Salmo salar) in the transport of nutrients to and from river systems. We used demographic data from the River Bran, an oligotrophic river in Scotland, UK, to construct a budget for the transport of phosphorus (P) and applied it to investigate the effects of management strategies and demographic rates on potential transport. At present, because few adults return to their spawning grounds, salmon export 0.20.5 kg P·year1. In contrast, increasing passage rates to a level sufficient to maintain a population without stocking would likely result in a gain of up to several kilograms per year. However, this effect depended on the retention of adult-derived P, which varies across systems and is poorly known at present. Egg-derived P exceeded that from adults at low (<25%) retention rates but was insufficient on its own to balance losses. Increased marine survival rates also increased the potential for positive P flux, while reduction in eggsmolt survival reduced the magnitude of transport. These results indicate the importance of considering within-river movements of individuals and nutrients and the need to fill critical data gaps in assessing the role of Atlantic salmon in nutrient transport.
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Saito, M., S. Onodera, G. Hidaka i M. Tokumasu. "Evaluation for the effect of non-stationary nutrient transport on the coastal seaweed cultivation in western Japan". Proceedings of the International Association of Hydrological Sciences 371 (12.06.2015): 149–55. http://dx.doi.org/10.5194/piahs-371-149-2015.
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Abstract. In order to evaluate the effects of non-stationary nutrient transport on the coastal seaweed cultivation, variations of the seaweed yield, nutrient condition of seawater, rainfall and nutrient transport from the river, observed over the last 40 years were examined to characterize the long-term trends and the influencing factors on the variation of seaweed yield. The results show that seaweed yield increased until 1973, then decreased in recent years. The recent condition of nutrients in seawater is relatively severe for seaweed farming. The results suggest that river-derived nutrient supply to coastal area will decrease further by the decrease of river discharge. For the future prospect, it is important to evaluate the variation of other nutrient supply such as from groundwater, offshore or bottom sediment as well as river discharge.
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Thiesen, A., G. Wild, M. Keelan, M. T. Clandinin, M. McBurney, J. Van Aerde i A. BR Thomson. "Ontogeny of intestinal nutrient transport". Canadian Journal of Physiology and Pharmacology 78, nr 7 (1.06.2000): 513–27. http://dx.doi.org/10.1139/y00-018.
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Children born prematurely lack the ability to digest and to absorb nutrients at rates compatible with their nutritional needs. As a result, total parenteral nutrition may need to be given. While this nutritional support may be life-saving, the baby who receives this therapy is exposed to the risks of possible sepsis, catheter dysfunction, and liver disease. The rodent model of postnatal development provides a useful framework to investigate some of the cellular features of human intestinal development. The up-regulation of intestinal gene expression and precocious development of intestinal nutrient absorption can be achieved by providing growth factor(s) or by modifying the composition of the maternal diet during pregnancy and nursing or the weaning diet of the infant. Accelerating the digestive and absorptive functions of the intestine would thereby allow for the maintenance of infant nutrition through oral food intake, and might possibly eliminate the need for, and risks of, total parenteral nutrition. Accordingly, this review was undertaken to focus on the adaptive processes available to the intestine, to identify what might be the signals for and mechanisms of the modified nutrient absorption, and to speculate on approaches that need to be studied as means to possibly accelerate the adaptive processes in ways which would be beneficial to the newborn young.Key words: absorption, adaptation, diet, peptides.
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Neumann, Wilma, Rose C. Hadley i Elizabeth M. Nolan. "Transition metals at the host–pathogen interface: how Neisseria exploit human metalloproteins for acquiring iron and zinc". Essays in Biochemistry 61, nr 2 (9.05.2017): 211–23. http://dx.doi.org/10.1042/ebc20160084.
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Transition metals are essential nutrients for all organisms and important players in the host–microbe interaction. During bacterial infection, a tug-of-war between the host and microbe for nutrient metals occurs: the host innate immune system responds to the pathogen by reducing metal availability and the pathogen tries to outmaneuver this response. The outcome of this competition, which involves metal-sequestering host-defense proteins and microbial metal acquisition machinery, is an important determinant for whether infection occurs. One strategy bacterial pathogens employ to overcome metal restriction involves hijacking abundant host metalloproteins. The obligate human pathogens Neisseria meningitidis and N. gonorrhoeae express TonB-dependent transport systems that capture human metalloproteins, extract the bound metal ions, and deliver these nutrients into the bacterial cell. This review highlights structural and mechanistic investigations that provide insights into how Neisseria acquire iron from the Fe(III)-transport protein transferrin (TF), the Fe(III)-chelating host-defense protein lactoferrin (LF), and the oxygen-transport protein hemoglobin (Hb), and obtain zinc from the metal-sequestering antimicrobial protein calprotectin (CP).
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Daniel, Hannelore, Britta Spanier, Gabor Kottra i Dietmar Weitz. "From Bacteria to Man: Archaic Proton-Dependent Peptide Transporters at Work". Physiology 21, nr 2 (kwiecień 2006): 93–102. http://dx.doi.org/10.1152/physiol.00054.2005.
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Uptake of nutrients into cells is essential to life and occurs in all organisms at the expense of energy. Whereas in most prokaryotic and simple eukaryotic cells electrochemical transmembrane proton gradients provide the central driving force for nutrient uptake, in higher eukaryotes it is more frequently coupled to sodium movement along the transmembrane sodium gradient, occurs via uniport mechanisms driven by the substrate gradient only, or is linked to the countertransport of a similar organic solute. With the cloning of a large number of mammalian nutrient transport proteins, it became obvious that a few “archaic” transporters that utilize a transmembrane proton gradient for nutrient transport into cells can still be found in mammals. The present review focuses on the electrogenic peptide transporters as the best studied examples of proton-dependent nutrient transporters in mammals and summarizes the most recent findings on their physiological importance. Taking peptide transport as a general phenomenon found in nature, we also include peptide transport mechanisms in bacteria, yeast, invertebrates, and lower vertebrates, which are not that often addressed in physiology journals.
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Bates, Sarah L., Keith A. Sharkey i Jon B. Meddings. "Vagal involvement in dietary regulation of nutrient transport". American Journal of Physiology-Gastrointestinal and Liver Physiology 274, nr 3 (1.03.1998): G552—G560. http://dx.doi.org/10.1152/ajpgi.1998.274.3.g552.
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In omnivores, gradual alterations in dietary nutrient composition are observed. To efficiently absorb dietary nutrients these animals alter intestinal nutrient transporter expression to match the pattern of nutrient intake. This often involves reprogramming the crypt cell to express greater numbers of the relevant transport system. The aim of this study was to determine whether vagal afferents are involved in this adaptive process. Guinea pigs were habituated to a low-carbohydrate diet and then switched to a high-carbohydrate diet. The resultant increase in glucose transporter expression was assessed by determining rates of glucose transport in jejunal brush-border membrane vesicles. Ablation of vagal afferents was accomplished by application of capsaicin to exposed cervical vagi and confirmed using Fast blue tracer studies. We found that animals in which vagal afferents were ablated with capsaicin were unable to alter rates of glucose transport in response to an increase in dietary carbohydrate. This suggests that vagal afferents are involved in this adaptive process. These findings support a role for the vagus nerve in regulating intestinal transport function, which may be important to consider in clinical disease that involves the vagus nerve.
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Elliott, Jane. "Evaluating the potential contribution of vegetation as a nutrient source in snowmelt runoff". Canadian Journal of Soil Science 93, nr 4 (wrzesień 2013): 435–43. http://dx.doi.org/10.4141/cjss2012-050.
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Elliott, J. 2013. Evaluating the potential contribution of vegetation as a nutrient source in snowmelt runoff. Can. J. Soil Sci. 93: 435–443. On the Canadian prairies, most nutrient transport to surface waters takes place during snowmelt. The potential for a range of 11 residue types to release nitrogen (N), phosphorus (P) and carbon (C) was assessed by snowmelt simulation. Interactions between soils and residues were measured for two contrasting residues. Samples (taken in late fall) were frozen prior to snowmelt simulations that consisted of three diurnal temperature cycles from −5°C to +9°C followed by a final melt at +5°C. Releases of total and total dissolved P (TP and TDP), total dissolved N (TDN), and dissolved organic C (DOC) during simulated snowmelt were greater from actively growing residues than from crop stubble and were significantly related to plant moisture and nutrient contents. Nutrient release from wheat stubble (WS) was statistically similar to that from the underlying surface soil but releases of P and ammonia (NH3) from winter wheat (WW) were at least four times greater than for the corresponding soil. When combined samples of residue and soil were tested, releases of most nutrients were less than when the residue and soil were tested separately. Potential release of nutrients from vegetation is a factor for consideration in the design of practices to reduce nutrient transport.
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Villar, C. A., J. Stripeikis, L. D. Huicque, M. Tudino i C. Bonetto. "Concentration and transport of particulate nutrients and metals in the Lower Paraná River during extreme flooding". Fundamental and Applied Limnology 153, nr 2 (27.02.2002): 273–86. http://dx.doi.org/10.1127/archiv-hydrobiol/153/2002/273.
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Shirazi-Beechey, Soraya. "A matter of taste: Nutrient Sensing Through the Plasma Membrane of Eukaryotic Cells, a Biochemical Society Focused Meeting, held at the Royal Agricultural College, Cirencester, 25–29 September 2004". Biochemist 27, nr 1 (1.02.2005): 35–38. http://dx.doi.org/10.1042/bio02701035.
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Sensing nutrients is a fundamental property of all living cells. Indeed, it is an absolute requirement for their ability to adapt to changes in their nutritional environment.There are an increasing number of published reports describing examples of nutrient-sensing molecules in the plasma membrane of fungi, plant and animal cells.These nutrientsensing molecules include nutrient carriers, molecules analogous with nutrient transporters, but without demonstrable transport function, and members of a large superfamily of GPCRs (G-protein-coupled receptors).These reports have added a fascinating new function to the plasma membrane as a nutrient-sensing device.
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Poschet, JF, R. Gilbert i PD Fairclough. "The importance of paracellular transport of nutrients in man". Gastroenterology 114 (kwiecień 1998): A406. http://dx.doi.org/10.1016/s0016-5085(98)81643-0.
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NELSON, D. P., W. L. PAN i V. R. FRANCESCHI. "Xylem and Phloem Transport of Mineral Nutrients fromSolanum tuberosumRoots". Journal of Experimental Botany 41, nr 9 (1990): 1143–48. http://dx.doi.org/10.1093/jxb/41.9.1143.
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Kohan, Alison, Stephanie Yoder i Patrick Tso. "Lymphatics in intestinal transport of nutrients and gastrointestinal hormones". Annals of the New York Academy of Sciences 1207 (październik 2010): E44—E51. http://dx.doi.org/10.1111/j.1749-6632.2010.05753.x.
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