No description available.

Variable fluorescence of chlorophyll a (Fv/Fm), measured by pulse amplitude modulated (PAM) fluorometers, is an attractive target for phytoplankton-related water quality management. Lowered Fv/Fm is believed to reflect the magnitude of nutrient sufficiency or deficiency in phytoplankton. This rapid and specific metric is relevant to Lake Erie, which often experiences problematic Cyanobacteria blooms. It is unknown whether PAMs reliably measure phytoplankton nutrient status or if different PAMs provide comparable results. Water samples collected from Lake Erie and two Lake Ontario sites in July and September 2011 were analysed using alkaline phosphatase assay (APA), P-debt, and N-debt to quantify phytoplankton nutrient status and with three different PAM models (PhytoPAM, WaterPAM and DivingPAM) to determine Fv/Fm. The Lake Ontario, Lake Erie East and Central Basin sites were all N- and P-deficient in July, but only the East and Central Basin and one Lake Ontario site were P-deficient in September. The West Basin sites were P-deficient in July and one West Basin site and a river site were N-deficient in September. Between-instrument Fv/Fm comparisons did not show the expected 1:1 relationship. Fv/Fm from the PhytoPAM and WaterPAM were well-correlated with each other but not with nutrient deficiency. DivingPAM Fv/Fm did not correlate with the other PAM models, but correlated with P-deficiency. Spectral PAM fluorometers (PhytoPAM) can potentially resolve Fv/Fm down to phytoplankton group by additionally measuring accessory pigment fluorescence. The nutrient-induced fluorescent transient (NIFT) is the observation that Fv/Fm drops immediately and recovers when the limiting nutrient is reintroduced to nutrient-starved phytoplankton. A controlled laboratory experiment was conducted on a 2x2 factorial mixture design of P-deficient and P-sufficient Asterionella formosa and Microcystis aeruginosa cultures. Patterns consistent with published reports of NIFT were observed for P-deficient M. aeruginosa in mixtures; the pattern for A. formosa was less clear. This thesis showed that Fv/Fm by itself was not a reliable metric of N or P deficiency and care must be taken when interpreting results obtained by different PAM fluorometers. NIFT analysis using spectral PAM fluorometers may be able to discriminate P-deficiency in M. aeruginosa, and possibly other Cyanobacteria, in mixed communities.

Variable fluorescence of chlorophyll a (Fv/Fm), measured by pulse amplitude modulated (PAM) fluorometers, is an attractive target for phytoplankton-related water quality management. Lowered Fv/Fm is believed to reflect the magnitude of nutrient sufficiency or deficiency in phytoplankton. This rapid and specific metric is relevant to Lake Erie, which often experiences problematic Cyanobacteria blooms. It is unknown whether PAMs reliably measure phytoplankton nutrient status or if different PAMs provide comparable results. Water samples collected from Lake Erie and two Lake Ontario sites in July and September 2011 were analysed using alkaline phosphatase assay (APA), P-debt, and N-debt to quantify phytoplankton nutrient status and with three different PAM models (PhytoPAM, WaterPAM and DivingPAM) to determine Fv/Fm. The Lake Ontario, Lake Erie East and Central Basin sites were all N- and P-deficient in July, but only the East and Central Basin and one Lake Ontario site were P-deficient in September. The West Basin sites were P-deficient in July and one West Basin site and a river site were N-deficient in September. Between-instrument Fv/Fm comparisons did not show the expected 1:1 relationship. Fv/Fm from the PhytoPAM and WaterPAM were well-correlated with each other but not with nutrient deficiency. DivingPAM Fv/Fm did not correlate with the other PAM models, but correlated with P-deficiency. Spectral PAM fluorometers (PhytoPAM) can potentially resolve Fv/Fm down to phytoplankton group by additionally measuring accessory pigment fluorescence. The nutrient-induced fluorescent transient (NIFT) is the observation that Fv/Fm drops immediately and recovers when the limiting nutrient is reintroduced to nutrient-starved phytoplankton. A controlled laboratory experiment was conducted on a 2x2 factorial mixture design of P-deficient and P-sufficient Asterionella formosa and Microcystis aeruginosa cultures. Patterns consistent with published reports of NIFT were observed for P-deficient M. aeruginosa in mixtures; the pattern for A. formosa was less clear. This thesis showed that Fv/Fm by itself was not a reliable metric of N or P deficiency and care must be taken when interpreting results obtained by different PAM fluorometers. NIFT analysis using spectral PAM fluorometers may be able to discriminate P-deficiency in M. aeruginosa, and possibly other Cyanobacteria, in mixed communities.

Apoplastic barriers (exodermis and endodermis) control free movement of substances by apoplast, which is achieved by specific cell wall modifications. Differentiation of these barriers is to some extent variable. It has been demonstrated many times that the differentiation of root apoplastic barriers is strongly influenced by unfavourable environmental conditions. Many stress factors accelerate the deposition of apoplastic barriers. This work deals with the relationship between availability of nutrients and development of root barriers and mechanisms of coordination of developmental processes in roots, including the involvement of auxin and other phytohormones in the coordination of these processes. The exodermis developmental plasticity is followed in maize (Zea mays L.) under conditions of various nutrient deficiencies. The most important results are presented by anatomical analysis, which shows a significant acceleration of exodermis and endodermis differentiation in the N and P deficiency on the contrary, the slowing of differentiation in the absence of Fe and K. This effect is apparently a result of systemic rather than local root system responses because it was not observed with localized deficiency. This thesis also test the influence of some phytohormones on the development of apoplastic...

A recuperação e a restauração florestal de ecossistemas degradados podem não acontecer das maneiras desejadas, se houver carência nutricional ou suprimento inadequado de nutrientes às plantas no estádio inicial de desenvolvimento de espécies florestais nativas. O objetivo da presente investigação foi avaliar os efeitos da deficiência de nutrientes nas plantas na fase inicial de desenvolvimento das espécies florestais nativas Schinus terebinthifolius Raddi (aroeira-pimenteira), Cordia superba Cham. (baba-de-boi) e Cariniana estrellensis (Raddi) Kintze (jequitibá-branco). Foram observadas as alterações ultra-estruturais e teciduais das células do mesofilo das folhas, foi descrita a sintomatologia visual de deficiência nutricional, foram feitas as determinações de teores de macro e micronutrientes, das taxas de assimilação de gás carbônico e de transpiração, e as mensurações da altura e da produção de biomassa. O experimento foi conduzido em casa de vegetação, em blocos ao acaso, com três repetições e treze tratamentos para cada espécie, empregando a técnica de diagnose por subtração (-N, -P, -K, -Ca, -Mg, -S, -B, -Cu, -Fe, -Mn, -Mo, -Zn), sendo que em um dos tratamentos, as espécies nativas foram cultivadas em solução nutritiva completa, com todos os macros e micronutrientes. Durante o experimento e em sua análise, foi observada a seqüência de eventos que motivaram os sintomas de deficiência e a diminuição na produção de biomassa. Sabe-se que falta de um nutriente provoca alteração molecular, o que alterou as ultraestruturas celulares das folhas que foram observadas por microscopia. Essas modificações celulares provocaram alterações no tecido vegetal que induziram nas plantas os sintomas visuais específicos de cada nutriente que foram descritos. Como efeito fisiológico da deficiência nutricional, de forma geral, constataram-se diminuições nas taxas de fotossíntese e de transpiração e, por conseguinte, na produção de biomassa. Estes resultados claramente evidenciam o fato de que projetos de implantação de florestas ou de recuperação e restauração de ecossistemas degradados por meio do plantio das três espécies florestais nativas, em solos que necessitem de suplementação nutricional, poderão ter seu sucesso comprometido se não houver complementação nutricional / The recovery and forest restoration of degraded ecosystems may not be occur as desired if there is a nutritional deficiency or an inadequate supply of nutrients in the initial phase development of native forest species. The objective of this research was to evaluate the macronutrient and micronutrient deficiency effects on Brazilian native species young plants: Schinus terebinthifolius Raddi, Cordia superba Cham. and Cariniana estrellensis (Raddi) Kintze. Ultrastructural and tissue of the mesophyll cells of leaves changes were observed by microscopy, the visual symptom of nutritional deficiencies were described, the nutrient contents were analyzed, the carbon assimilation and transpiration rates were measured, the plant heights and the biomass production were measured. The experiment was carried on a greenhouse in a randomized block design with three replications and thirteen treatments for each species, using the technique of diagnosis by subtraction (-N, -P, -K, -Ca, -Mg, -S, -B, - Cu, -Fe, -Mn, -Mo, -Zn) and in one of the treatments the species were grown in a nutrient solution with all macro and micronutrients. It was observed, during the experiment and its analysis, a sequence of events that caused the visual symptoms and decreased the biomass production. It is known that the nutrient deficiency causes molecular alterations, which consequently led the changes in cellular ultrastructure of the leaves and they were observed by microcopy. These cellular changes caused modifications in the foliar tissue, and the plants showed specific visual symptoms of each nutrient, which they were described. As physiological effect of nutritional deficiency, in general decreases the photosynthesis and transpiration taxes, and consequently the biomass production were decreased. These results clearly project that forest implantation or recovery and restoration of damaged ecosystems by planting the three native species in soils that require nutritional supplementation may have its success compromised if there is no a nutritional supplementation

A recuperação e a restauração florestal de ecossistemas degradados podem não acontecer das maneiras desejadas, se houver carência nutricional ou suprimento inadequado de nutrientes às plantas no estádio inicial de desenvolvimento de espécies florestais nativas. O objetivo da presente investigação foi avaliar os efeitos da deficiência de nutrientes nas plantas na fase inicial de desenvolvimento das espécies florestais nativas Schinus terebinthifolius Raddi (aroeira-pimenteira), Cordia superba Cham. (baba-de-boi) e Cariniana estrellensis (Raddi) Kintze (jequitibá-branco). Foram observadas as alterações ultra-estruturais e teciduais das células do mesofilo das folhas, foi descrita a sintomatologia visual de deficiência nutricional, foram feitas as determinações de teores de macro e micronutrientes, das taxas de assimilação de gás carbônico e de transpiração, e as mensurações da altura e da produção de biomassa. O experimento foi conduzido em casa de vegetação, em blocos ao acaso, com três repetições e treze tratamentos para cada espécie, empregando a técnica de diagnose por subtração (-N, -P, -K, -Ca, -Mg, -S, -B, -Cu, -Fe, -Mn, -Mo, -Zn), sendo que em um dos tratamentos, as espécies nativas foram cultivadas em solução nutritiva completa, com todos os macros e micronutrientes. Durante o experimento e em sua análise, foi observada a seqüência de eventos que motivaram os sintomas de deficiência e a diminuição na produção de biomassa. Sabe-se que falta de um nutriente provoca alteração molecular, o que alterou as ultraestruturas celulares das folhas que foram observadas por microscopia. Essas modificações celulares provocaram alterações no tecido vegetal que induziram nas plantas os sintomas visuais específicos de cada nutriente que foram descritos. Como efeito fisiológico da deficiência nutricional, de forma geral, constataram-se diminuições nas taxas de fotossíntese e de transpiração e, por conseguinte, na produção de biomassa. Estes resultados claramente evidenciam o fato de que projetos de implantação de florestas ou de recuperação e restauração de ecossistemas degradados por meio do plantio das três espécies florestais nativas, em solos que necessitem de suplementação nutricional, poderão ter seu sucesso comprometido se não houver complementação nutricional / The recovery and forest restoration of degraded ecosystems may not be occur as desired if there is a nutritional deficiency or an inadequate supply of nutrients in the initial phase development of native forest species. The objective of this research was to evaluate the macronutrient and micronutrient deficiency effects on Brazilian native species young plants: Schinus terebinthifolius Raddi, Cordia superba Cham. and Cariniana estrellensis (Raddi) Kintze. Ultrastructural and tissue of the mesophyll cells of leaves changes were observed by microscopy, the visual symptom of nutritional deficiencies were described, the nutrient contents were analyzed, the carbon assimilation and transpiration rates were measured, the plant heights and the biomass production were measured. The experiment was carried on a greenhouse in a randomized block design with three replications and thirteen treatments for each species, using the technique of diagnosis by subtraction (-N, -P, -K, -Ca, -Mg, -S, -B, - Cu, -Fe, -Mn, -Mo, -Zn) and in one of the treatments the species were grown in a nutrient solution with all macro and micronutrients. It was observed, during the experiment and its analysis, a sequence of events that caused the visual symptoms and decreased the biomass production. It is known that the nutrient deficiency causes molecular alterations, which consequently led the changes in cellular ultrastructure of the leaves and they were observed by microcopy. These cellular changes caused modifications in the foliar tissue, and the plants showed specific visual symptoms of each nutrient, which they were described. As physiological effect of nutritional deficiency, in general decreases the photosynthesis and transpiration taxes, and consequently the biomass production were decreased. These results clearly project that forest implantation or recovery and restoration of damaged ecosystems by planting the three native species in soils that require nutritional supplementation may have its success compromised if there is no a nutritional supplementation

Microalgae are a rich, largely untapped source of lipids. Algae are underutilized, in part, because lipid formation generally is stimulated by stress, such as nutrient deficiency. Nutrient deficiencies reduce growth, resulting in a tradeoff between elevated cellular lipids and abundant cell division. This tradeoff is not well understood. We also have a poor understanding of the physiological drivers for this lipid formation. Here we report on three sets of research: 1) Assessment of species differences in growth and lipid content tradeoffs with high and low level nitrogen deficiency; 2) Investigation of physiological drivers of lipid formation, by mass balance accounting of cellular nitrogen with progressing deficiency; 3) Examination of the effects of sodium chloride and silicon on lipid production in a marine diatom. 1) Nitrogen deficiency typically had disproportionate effects on growth and lipid content, with profound differences among species. Optimally balancing the tradeoff required a wide range in the rate of nitrogen supply to species. Some species grew first and then accumulated lipids, while other species grew and accumulated lipids concurrently--a characteristic that increased lipid productivity. High lipid content generally resulted from a response to minimal stress. 2) Commonalities among species in cellular nitrogen at the initiation of lipid accumulation provided insight into the physiological drivers for lipid accumulation in nitrogen deficient algae. Total nitrogen uptake and retention differed widely among species, but the ratio of minimum retained nitrogen to nitrogen at the initiation of lipid accumulation was consistent among species at 0.5 ± 0.04. This suggests that lipid accumulation was signaled by a common magnitude of nitrogen deficiency. Among the cellular pools of nitrogen at the initiation of lipid accumulation, the concentration of RNA and the protein to RNA ratio were most similar among species with averages of 3.2 ± 0.26 g L-1 (8.2% variation) and 16 ± 1.5 (9.2% variation), respectively. This implicates critical levels of these parameters as potential signals initiating the accumulation of lipids. 3) In a marine diatom, low levels of either sodium chloride or silicon resulted in at least 50% increases in lipid content. The synergy of simultaneous, moderate sodium chloride and silicon stress resulted in lipid content up to 73%. There was a strong sodium chloride/silicon interaction in total and ash-free dry mass densities that arose because low sodium chloride was inhibitory to growth, but the inhibition was overcome with excessive silicon supply. This suggests that low sodium chloride may have affected metabolism of silicon.

Food insecurity is a growing issue in the United States. Iron deficiency is the most common form of nutritional deficiency in patients with endothelial dysfunction and vascular-related diseases. This preliminary study lays the groundwork for the “Nutrient deficiency-on-a-chip” model. Endothelial cells are cultured on mechanically tunable, enzymatically cross-linked gelatin and treated with deferoxamine, an iron chelator, or angiotensin II were used to simulate a nutrient deficient and diseased environment, respectively. As oxidative stress and disturbed barrier function are the most prevailing mechanism of angiotensin II and iron deficiency induced endothelial dysfunction, to test our model we investigated the changes in reactive oxygen species production and VE-cadherin expression in engineered endothelium. Both angiotensin II and deferoxamine treated engineered endothelium showed an increase in oxidative stress and disturbed barrier function. This in vitro model can be a useful tool to better understand disease mechanisms associated with nutrient deficiency and identify novel therapeutics.

No description available.

La Phostine (PSN ; PHOSphate STarvation response INductor) est une petite molécule organique de synthèse, identifiée dans une chimiothèque par son effet inducteur de l’expression du gène PHT1;4 codant un transporteur de phosphate chez Arabidopsis thaliana. Au cours de cette thèse, j’ai caractérisé l’effet de la PSN chez Arabidopsis et montré que cette drogue induit plusieurs réponses typiques de la carence en phosphate : expression de gènes régulés localement ou à longue distance, accumulation d’anthocyanes et d’amidon, activité des phosphatases acides, inhibition de la croissance des racines. De plus, la PSN provoque une accumulation de phosphate soluble dans les racines.L’étude d’analogues structuraux de la PSN m’a permis d’identifier un motif commun (#10) nécessaire à son activité biologique. Il apparaît que la PSN et ses analogues actifs sont instables à pH acide, ce qui libère le motif #10. Nous montrons que le motif #10 pénètre dans la plante essentiellement par les racines et qu’il ne circule pas des racines vers les feuilles, et faiblement des feuilles vers les racines. L’accumulation de #10 dans les racines expliquerait l’ensemble des effets observés de la PSN et de ses analogues actifs. Nous avons isolé un mutant d’Arabidopsis dont la croissance racinaire résiste à la PSN. Chez ce mutant, la PSN ne provoque plus l’accumulation d’anthocyanes et d’amidon dans les feuilles, ni celle de phosphate dans les racines. En absence de PSN, et sur un milieu de culture partiellement appauvri en phosphate, les feuilles et les racines de ce mutant accumulent plus de phosphate que celles du type sauvage. Chez les plantes, l’homéostasie du phosphate est soumise à une régulation complexe, la caractérisation approfondie de ce mutant apportera de nouveaux éléments pour sa compréhension. / The Phostin (PSN ; PHOSphate STarvation response INductor) is a small organic synthetic molecule identified in a chemical library by its induction effect on PHT1;4 expression, a gene encoding a phosphate transporter in Arabidopsis thaliana. During my PhD, I characterized the effects of PSN in Arabidopsis and shown that this drug induces several phosphate starvation responses: expression of locally or systemically regulated genes, anthocyanin and starch accumulation, acid phosphatase activity, primary root growth inhibition. Moreover, PSN induces inorganic soluble phosphate accumulation in roots.Thanks to PSN’s structural analogues, we identified a common motif (motif #10) necessary to its biological activity. PSN and its analogues are unstable in acidic conditions, leading to the release of #10 motif. We have shown that #10 motif enters the plant mostly by the roots and do not circulate from roots to shoots, and weakly from shoots to roots. The accumulation of #10 motif in the roots explains all the PSN and analogues observed effects. We characterized an Arabidopsis mutant resistant to PSN for its root growth. In this mutant, PSN does not induce anthocyanin or starch accumulation in leaves, neither phosphate in roots. When growing without PSN, on partially phosphate depleted medium, the mutant presents higher phosphate content than the wild type. Phosphate homeostasis is a very complex process in plant, the deep characterization of this mutant will bring new elements for the comprehension of this pathway.