Microbial transformations in phosphonate biosynthesis and catabolism, and their importance in nutrient cycling

Phosphorus cycling in the biosphere has traditionally been thought to involve almost exclusively transformations of the element in its pentavalent oxidation state. Recent evidence, however, suggests that a significant fraction of environmental phosphorus may exist in a more reduced form. Most abundant of these reduced phosphorus compounds are the phosphonates, with their direct carbon–phosphorus bonds, and striking progress has recently been made in elucidating the biochemistry of microbial phosphonate transformations. These advances are now presented in the context of their contribution to our understanding of phosphorus biogeochemistry and of such diverse fields as the productivity of the oceans, marine methanogenesis and the discovery of novel microbial antimetabolites.

The role of papyrus plants (Cyperus papyrus) and internal waves in the nutrient balance of Lake Victoria, East Africa

Dissertação mest., Gestão da água e da costa, Universidade do Algarve, 2007

Effects of nutrient and light enrichment on phytoplankton growth

Alterations of freshwater flow regimes and increasing eutrophication lead to alterations in light availability and nutrient loading into adjacent estuaries and coastal areas. Phytoplankton community respond to these changes in many ways. Harmful phytoplankton blooms, for instance, may be a consequence of changes in nutrient supply, as well as the replacement of some phytoplankton species (like diatoms, that contribute for the development of large fish and shellfish populations) by ohers (like cyanobacteria, that may be toxic and represent an undesirable food source for higher trophic levels). Nutrient and light enrichment experiments allow us to understand and predict the effects of eutrophication on the growth of phytoplankton. This is a fundamental tool in water management issues, since it enables the prediction of changes in the phytoplankton community that may be harmful to the whole ecosystem, and the design of mitigation strategies (Zalewski 2000).

Temperature, pH, and conductivity control of the nutrient solution of an hydroponic greenhouse

One of the aspects of modern agriculture is characterised by a culture without soil (hydroponic cultures). These culture techniques are identified by possessing automatic control systems to control the nutrient solution. In first hydroponic cultures this control was accomplished by “on- off” analog controllers that applied a single control law implemented in hardware. Therefore, the changes of the control law resulted in the change of all interface electronics. In digital control implemented by micro-controllers the alteration of such control law is easily performed by changing only a computer program, leaving untouched all the interface hardware. In this way, the use and substitution of the control strategy is improved, as well, the use of advanced control strategies.

Interaction between water and nutrient deficiencies in helianthus annuus

The physiological response of plants to water deficits are known to vary according to the conditions of application of drought stress and the rate of development of leaf water deficits. At the whole plant level the effect of the water shess is usually perceived as a decrease in photosynthesis and growth, and is associated with alterations in C and N metabolism (McDonald and Davies, 1996). The decrease in water potential affects transpiration and hence xylem transport of nitrate or reduced N into growing regions. The response of the photo-synthetic apparatus either to water stress or rehydration seems to be dependent "on leaf age (O'Neill, 1983; Wolfe et al., 1988). Degradation of both thylakoid and stromal N-containing compounds can occur in response to water stress, recovery from which may pequire more than a week (Chaves, 1991).

A proteomic study of the effects of nutrient restriction in utero on postnatal metabolism

It is widely recognized that protein restriction in utero may cause metabolic and endocrine adaptations, which may be of benefit to the neonate on a short-term basis but may cause adverse long-term conditions such as obesity, Type 2 diabetes, metabolic syndrome, hypertension and cardiovascular diseases. Adequate foetal and early post natal nutrient and energy supply is therefore essential for adult animal health, performance and life span. In this project it was investigated the progressive adaptations of the hepatic proteome in male mink offspring exposed to either a low protein (FL) or an adequate protein (FA) diet in utero fed either on a low protein (LP) or on an adequate (AP) diet from weaning until sexual maturity. Specifically, the aim was to determine the metabolic adaptations at selected phases of the animal’s first annual cycle and establish the metabolic priorities occurring during those phases. The three different morphological stages studied during the first year of development included, end of bone growth at 4 months of age, maximal fat accretion at 6 months of age and sexual maturity at 12 months of age. A reference proteome of mink liver coming from these different animal groups were generated using 2D electrophoresis coupled to MALDI-TOF analysis and the way in which dietary treatment affect their proteome was established. Approximately 330 proteins were detected in the mink liver proteome. A total of 27 comparisons were carried out between all different animal groups which resulted in 20 differentially expressed proteins. An extensive survey was conducted towards the characterization of these proteins including their subcellular localization, the biological processes in which they are involved and their molecular functions. This characterization allowed the identification of proteins in various processes including the glycolysis and fatty acid metabolism. The detailed analysis of the different dietary treatment animal groups was indicative of differences in metabolism and also to changes associated with development in mink.

Targeting specific nutrient deficiencies in proteinrestricted diets: some practical facts in PKU dietary management

Among aminoacidopathies, phenylketonuria (PKU) is the most prevalent one. Early diagnosis in the neonatal period with a prompt nutritional therapy (low natural-protein and phenylalanine diet, supplemented with phenylalanine-free amino acid mixtures and special low-protein foods) remains the mainstay of the treatment. Data considering nutrient contents of cooked dishes is lacking. In this study, fourteen dishes specifically prepared for PKU individuals were analysed, regarding the lipid profile and iron and zinc contents. These dishes are poor sources of essential nutrients like Fe, Zn or n-3 fatty acids, reinforcing the need for adequate supplementation to cover individual patients’ needs. This study can contribute to a more accurate adjustment of PKU diets and supplementation in order to prevent eventual nutritional deficiencies. This study contributes to a better understanding of nutrient intake from PKU patients’ meals, showing the need for dietary supplementation.

Cation transporters/channels in plants: Tools for nutrient biofortification

Cation transporters/channels are key players in a wide range of physiological functions in plants, including cell signaling, osmoregulation, plant nutrition and metal tolerance. The recent identification of genes encoding some of these transport systems has allowed new studies toward further understanding of their integrated roles in plant. This review summarizes recent discoveries regarding the function and regulation of the multiple systems involved in cation transport in plant cells. The role of membrane transport in the uptake, distribution and accumulation of cations in plant tissues, cell types and subcellular compartments is described. We also discuss how the knowledge of inter- and intra-species variation in cation uptake, transport and accumulation as well as the molecular mechanisms responsible for these processes can be used to increase nutrient phytoavailability and nutrients accumulation in the edible tissues of plants. The main trends for future research in the field of biofortification are proposed.

Production of polyhydroxyalkanoates from cheese whey - pH effect on the acidogenic fermentation stage and nutrient needs of the culture selection stage

Dissertação para obtenção do Grau de Mestre em Biotecnologia

Temporal changes in mRNA expression of the brain nutrient transporters in the lithium-pilocarpine model of epilepsy in the immature and adult rat.

The lithium-pilocarpine model mimics most features of human temporal lobe epilepsy. Following our prior studies of cerebral metabolic changes, here we explored the expression of transporters for glucose (GLUT1 and GLUT3) and monocarboxylates (MCT1 and MCT2) during and after status epilepticus (SE) induced by lithium-pilocarpine in PN10, PN21, and adult rats. In situ hybridization was used to study the expression of transporter mRNAs during the acute phase (1, 4, 12 and 24h of SE), the latent phase, and the early and late chronic phases. During SE, GLUT1 expression was increased throughout the brain between 1 and 12h of SE, more strongly in adult rats; GLUT3 increased only transiently, at 1 and 4h of SE and mainly in PN10 rats; MCT1 was increased at all ages but 5-10-fold more in adult than in immature rats; MCT2 expression increased mainly in adult rats. At all ages, MCT1 and MCT2 up-regulation was limited to the circuit of seizures while GLUT1 and GLUT3 changes were more widespread. During the latent and chronic phases, the expression of nutrient transporters was normal in PN10 rats. In PN21 rats, GLUT1 was up-regulated in all brain regions. In contrast, in adult rats GLUT1 expression was down-regulated in the piriform cortex, hilus and CA1 as a result of extensive neuronal death. The changes in nutrient transporter expression reported here further support previous findings in other experimental models demonstrating rapid transcriptional responses to marked changes in cerebral energetic/glucose demand.

Role of family eating practices on daily nutrient intakes, dietary patterns and measures of body composition in peri-adolescents

Although family eating practices (FEPs) playa role in the formation of eating practices in children, there is a lack of evidence regarding the role of FEPs on obesity (DB) risk. The purpose of this thesis was to assess the role of child, mother 'and father eating practices (CEPs; MEPS; FaEPs) on nutrient intakes, dietary patterns and body composition. Data were collected on approximately 2,400 peri-adolescents (s250 with complete covariate data). Dietary patterns were assessed using scores that reflected how closely participants followed DASH and Health Canada (HC) recommendations. In girls, poor CEPs, MEPs and FaEPs were associated with increased BMI and risk of overweight and poor dietary patterns according to DASH, and DASH and HC, respectively. In boys, poor CEPs and FaEPs were associated with increased monounsaturated and trans fat, and Vitamin C intakes, respectively. These findings suggest FEPs are associated with DB risk, particularly in girls.

Studies on the Role of Sediments on the Nutrient Dynamics and Fertility of Kuttanad Waters

In the present study the nutrient dynamics and fertility of Kuttanad waters is addressed. Kuttanad represent a wetland system with considerable agricultural activities. The hydrographical features of the Kuttanad waters are controlled by discharges from Manimala, Meenachil, Pamba, Achencoil and Muvattupuzha rivers and also by tidal intrusions of saline waters from Cochin backwaters during summers. The fertility of these water bodies were significantly high and supported good agricultural production. Kuttanad water forms the southern part of this aquatic systems and is considered as the most productive zones. As a part of the management scheme for a higher agricultural activity, the Thannermukkam bund was constructed to block and regulate the intrusion of saline water. The increased use of artificial fertilizers along with stagnant character of the water body in this area has resulted in sharp decline in the water quality, productivity and aquatic resources.

Nutrient Dynamics in the EEZ of the West Coast of India with Special Reference to the Oxygen Minimum Zone and Denitrification

The present work aims at deciphering the processes that control the nutrient distribution along the EEZ (Exclusive Economic Zone of India) of the west coast of India and to bring out its linkage with primary and secondary productivity. This work assume utmost importance as very few studies have hitherto focused entirely on the EEZ of the west coast of India to address the biochemical responses brought about by monsoons. The present study examines the seasonal variations in physicochemical parameters and associated primary biological responses along the west coast of India. This study targets to measure and understand the shelf ocean exchange in a typical coastal upwelling region of the southeast Arabian Sea, and the influence of convective mixing along the northern part of the west coast of India. The study focuses more directly on coastal upwelling along the southwest coast of India, within the EEZ. The effects of coastal upwelling, eddy formation and the offshore advection are apparent in the present investigation. This has consequences to fisheries and climate, in energy transfer to the food chain and the increased sequestering of carbon in the ocean. The study also focuses on the Oxygen Minimum Zone (OMZ) and dentrification observed along the EEZ of the west coast of India on a seasonal scale. In the study, an attempt is also made to demarcate the geographical boundaries of the denitrification zone in the EEZ of India and on the nature and magnitude of these variations, on a seasonal and inter annual scales

Studies on the Role of Sediments on the Nutrient Dynamics and Fertility of Kuttanad Waters

In the present study the nutrient dynamics and fertility of Kuttanad waters is addressed. Kuttanad represent a wetland system with considerable agricultural activities. The hydrographical features of the Kuttanad waters are controlled by discharges from Manimala, Meenachil, Pamba, Achencoil and Muvattupuzha rivers and also by tidal intrusions of saline waters from Cochin backwaters during summers. The fertility of these water bodies were significantly high and supported good agricultural production. Kuttanad water forms the southern part of this aquatic systems and is considered as the most productive zones. As a part of the management scheme for a higher agricultural activity, the Thannermukkam bund was constructed to block and regulate the intrusion of saline water. The increased use of artificial fertilizers along with stagnant character of the water body in this area has resulted in sharp decline in the water quality, productivity and aquatic resources.