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Several Constituents (several + constituent)
Selected AbstractsAn effective DNA extraction protocol for brown algaePHYCOLOGICAL RESEARCH, Issue 2 2001Naomi Phillips SUMMARY Successful extraction of total DNA from brown algae, which are generally polysaccharide and polyphenol rich, is often problematic using current methods. Persistent polysaccharide and polyphenolic compounds can hinder further application of modern molecular techniques requisite to molecular-based evolutionary studies. Our broad and long-term research goals with fucalean taxa, especially Sargassum, and problems with existing DNA extraction methods were an impetus to develop a reliable DNA extraction method. Initial research established hexadecyltrimethylammonium bromide (CTAB) based total-DNA methods as the most viable for further empirical development. Several constituents effective at either complexing secondary compounds or creating a reductive extraction environment were increased in concentration or added to the extraction buffer. These seemingly minor changes resulted in the creation of a highly reductive extraction buffer and effective total- DNA harvesting technique. We detail these modifications and demonstrate the reliability of the modified protocol with a variety of brown algae and tissue preservation methods. Such DNA is shown to be suitable for a variety of molecular techniques. [source] Effects of urbanization on stream water quality in the city of Atlanta, Georgia, USA,HYDROLOGICAL PROCESSES, Issue 20 2009Norman E. Peters Abstract A long-term stream water quality monitoring network was established in the city of Atlanta, Georgia during 2003 to assess baseline water quality conditions and the effects of urbanization on stream water quality. Routine hydrologically based manual stream sampling, including several concurrent manual point and equal width increment sampling, was conducted ,12 times annually at 21 stations, with drainage areas ranging from 3·7 to 232 km2. Eleven of the stations are real-time (RT) stations having continuous measures of stream stage/discharge, pH, dissolved oxygen, specific conductance, water temperature and turbidity, and automatic samplers for stormwater collection. Samples were analyzed for field parameters, and a broad suite of water quality and sediment-related constituents. Field parameters and concentrations of major ions, metals, nutrient species and coliform bacteria among stations were evaluated and with respect to watershed characteristics and plausible sources from 2003 through September 2007. Most constituent concentrations are much higher than nearby reference streams. Concentrations are statistically different among stations for several constituents, despite high variability both within and among stations. Routine manual sampling, automatic sampling during stormflows and RT water quality monitoring provided sufficient information about urban stream water quality variability to evaluate causes of water quality differences among streams. Fecal coliform bacteria concentrations of most samples exceeded Georgia's water quality standard for any water-usage class. High chloride concentrations occur at three stations and are hypothesized to be associated with discharges of chlorinated combined sewer overflows, drainage of swimming pool(s) and dissolution and transport during rainstorms of CaCl2, a deicing salt applied to roads during winter storms. One stream was affected by dissolution and transport of ammonium alum [NH4Al(SO4)2] from an alum-manufacturing plant; streamwater has low pH (<5), low alkalinity and high metals concentrations. Several trace metals exceed acute and chronic water quality standards and high concentrations are attributed to washoff from impervious surfaces. Published in 2009 by John Wiley & Sons, Ltd. [source] High-pressure-induced changes in bovine milk: a reviewINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 2 2006THOM HUPPERTZ High-pressure (HP) treatment of food products is a novel processing technique during which the product is treated in a vessel of suitable strength at a high pressure, generally in the range 100,1000 MPa. As a result, several constituents and properties of the treated product are altered. HP-induced changes in the constituents and properties of milk are arguably among the most extensive of the range of food products studied to date. HP treatment of milk induces solubilization of minerals associated with the casein micelles, denatures whey proteins and, depending on pressure, can either induce aggregation or disruption of the casein micelles. These HP-induced changes in milk constituents affect the properties of the milk; cheesemaking properties of milk can be enhanced considerably, indicating potential application of HP treatment in this area; furthermore, encouraging results have also been reported for HP treatment of milk prior to yogurt manufacture. HP treatment of milk also affects its microflora; however, considerable variation in baroresistance between bacterial species and strains exists. Further applied research appears warranted to establish the full commercial potential of HP treatment of milk. [source] A robust PCR method for high-dimensional regressorsJOURNAL OF CHEMOMETRICS, Issue 8-9 2003Mia Hubert Abstract We consider the multivariate calibration model which assumes that the concentrations of several constituents of a sample are linearly related to its spectrum. Principal component regression (PCR) is widely used for the estimation of the regression parameters in this model. In the classical approach it combines principal component analysis (PCA) on the regressors with least squares regression. However, both stages yield very unreliable results when the data set contains outlying observations. We present a robust PCR (RPCR) method which also consists of two parts. First we apply a robust PCA method for high-dimensional data on the regressors, then we regress the response variables on the scores using a robust regression method. A robust RMSECV value and a robust R2 value are proposed as exploratory tools to select the number of principal components. The prediction error is also estimated in a robust way. Moreover, we introduce several diagnostic plots which are helpful to visualize and classify the outliers. The robustness of RPCR is demonstrated through simulations and the analysis of a real data set. Copyright © 2003 John Wiley & Sons, Ltd. [source] Immmunohistochemical Study of the Blood and Lymphatic Vasculature and the Innervation of Mouse Gut and Gut-Associated Lymphoid TissueANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2007B. Ma Summary The blood and lymphatic vascular system of the gut plays an important role in tissue fluid homeostasis, nutrient absorption and immune surveillance. To obtain a better understanding of the anatomic basis of these functions, the blood and lymphatic vasculature of the lower segment of mouse gut and several constituents of gut-associated lymphoid tissue (GALT) including Peyer's patch, specialized lymphoid nodules in the caecum, small lymphoid aggregates and lymphoid nodules in the colon were studied by using confocal microscopy. Additionally, the innervation and nerve/immune cell interactions in the gut and Peyer's patch were investigated by using cell surface marker PGP9.5 and Glial fibrillary acidic protein (GFAP). In the gut and Peyer's patch, the nerves have contact with B cell, T cell and B220CD3 double-positive cells. Dendritic cells, the most important antigen-presenting cells, were closely apposed to some nerves. Some dendritic cells formed membrane,membrane contact with nerve terminals and neuron cell body. Many fine nerve fibres, which are indirectly detected by GFAP, have contact with dendritic cells and other immune cells in the Peyer's patch. Furthermore, the expression of Muscarinic Acetylcholine receptor (subtype M2) was characterized on dendritic cells and other cell population. These findings are expected to provide a route to understand the anatomic basis of neuron-immune regulation/cross-talk and probably neuroinvasion of prion pathogens in the gut and GALT. [source] | |||||||||||||