Home About us Contact
|
Home About us Contact | ||
|
|
||
Lower Sections (lower + section)
Selected AbstractsCell wall phenolics of white and green asparagusJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2005Rocío Rodríguez Abstract Cinnamic acids influence physical and textural attributes of plant foods as they play an important role in lignification and cross-linking of cell-wall polymers. Several trans -cinnamic acids have been detected in asparagus cell wall (CW), and, of these, amounts of ferulic acid (FA) and its dehydrodimers have been found to increase significantly during post-harvest storage. The distribution of these compounds along the different sections of white and green spears, as well as their modifications during postharvest storage, has been investigated. It has been observed that the cell walls from the apical, middle and lower sections of the green spears contain equivalent amounts of FA derivatives (about 400 µg g,1 CW), while these compounds are mainly located in the middle (681 µg g,1 CW) and lower section (975 µg g,1 CW) of the white ones. During asparagus post-harvest storage a general increase of FA monomers and dimers took place that affected every section of both green and white spears. Major changes occurred in the middle and lower sections of the white asparagus, where the amounts of ferulic derivatives increased to 1700 and 1678 µg g,1 CW after storage. A similar but less pronounced trend was observed for the green spears. Copyright © 2005 Society of Chemical Industry [source] Distribution of several microorganisms and activity of alkaline phosphatase in sediments from Baihua LakeASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Jia-jun Deng Abstract The distribution characteristics of ammonifiers, ammonium-oxidizing bacteria, nitrite-oxidizing bacteria, and denitrifiers, and activities of alkaline phosphatase (ALP) in sediments from Baihua Lake (a man-made deep plateau canyon reservoir in Guizhou Province, China) were studied. The results suggested that the population number of ammonifiers in the sediments was higher at sampling sites Pingpu, Laojiutu, Yapengzhai, and Jiangjiapu than at the other sites. Ammonium-oxidizing bacteria had the highest population number at sampling site Meituwan. The population number of nitrite-oxidizing bacteria in the upper and middle sections of the lake was higher than that in the lower section. The population of denitrifiers was the highest at sampling site Jiangjiapu, and all the other sampling sites gave lower population numbers. Change in the activity of ALP was of a strong regularity, and the basic tendency was that the activity increased from the upper to the lower portion of the lake. Specifically, the activity at sampling site Yapengzhai was the strongest. The statistical analysis for four groups of bacteria, ALP, organic matter, and so on were carried out to shed more light on their correlativity. This research will likely provide relevant data useful for establishment of bacteriological and zymological indicator systems for environmental monitoring. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Effect of environmental variables on eukaryotic microbial community structure of land-fast Arctic sea iceENVIRONMENTAL MICROBIOLOGY, Issue 3 2010Brian Eddie Summary Sea ice microbial community structure affects carbon and nutrient cycling in polar seas, but its susceptibility to changing environmental conditions is not well understood. We studied the eukaryotic microbial community in sea ice cores recovered near Point Barrow, AK in May 2006 by documenting the composition of the community in relation to vertical depth within the cores, as well as light availability (mainly as variable snow cover) and nutrient concentrations. We applied a combination of epifluorescence microscopy, denaturing gradient gel electrophoresis and clone libraries of a section of the 18S rRNA gene in order to compare the community structure of the major eukaryotic microbial phylotypes in the ice. We find that the community composition of the sea ice is more affected by the depth horizon in the ice than by light availability, although there are significant differences in the abundance of some groups between light regimes. Epifluorescence microscopy shows a shift from predominantly heterotrophic life styles in the upper ice to autotrophy prevailing in the bottom ice. This is supported by the statistical analysis of the similarity between the samples based on the denaturing gradient gel electrophoresis banding patterns, which shows a clear difference between upper and lower ice sections with respect to phylotypes and their proportional abundance. Clone libraries constructed using diatom-specific primers confirm the high diversity of diatoms in the sea ice, and support the microscopic counts. Evidence of protistan grazing upon diatoms was also found in lower sections of the core, with implications for carbon and nutrient recycling in the ice. [source] Soil pipe distribution and hydrological functioning within the humid tropics: a synthesisHYDROLOGICAL PROCESSES, Issue 12 2010Nick A. Chappell Abstract Some of the most responsive runoff systems in the world are found within the humid tropics. These runoff responses are likely to be affected by the presence of natural pipes within the soil. This study provides a synthesis of the hydrological aspects of these phenomena within the humid tropics. Of the studies reporting the presence of soil piping within the humid tropics, most are associated with Ultisol soils, and, locally, most pipe outlets are observed on the lower sections of hillslopes. While the drainage role of pipes has been observed (providing faster and slower components of stream hydrographs), the mechanism of their recharge remains less clear. In part, this is because their spatial extent is poorly mapped within the hillslopes of the humid tropics. Further studies quantifying the length and recharge of soil pipe networks within the humid tropics are needed. Copyright © 2010 John Wiley & Sons, Ltd. [source] A flexible sand coating (Conniflex) for the protection of conifer seedlings against damage by the pine weevil Hylobius abietisAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2009Göran Nordlander Abstract 1 A new method for the physical protection of conifer seedlings against feeding damage by Hylobius abietis (L.), is described and evaluated in field trials in Swedish forest plantations. 2 The lower 60% of the stem of the seedling is protected by the Conniflex coating, consisting of fine sand (grain size = 0.2 mm) embedded in an acrylate dispersion that remains flexible after drying. 3 Seedlings are treated in the nursery by a large-scale application procedure involving four steps: (i) spraying the seedlings with water; (ii) application of fixative to the lower sections of the stems, (iii) application of fine sand to the fixative; and (iv) drying of the fixative. 4 A field experiment over three seasons demonstrated a significant increase in survival for coated seedlings compared with untreated seedlings. The survival rate increased from 29% to 97% for Scots pine and from 26% to 86% for Norway spruce. Coating the lower 30% of the stem (instead of 60%) provided inferior protection, resulting in only 64% survival in spruce. 5 Field trials in 11 commercial plantation areas indicated that the Conniflex sand coating was as effective in protecting seedlings as treatment with the insecticide imidacloprid. 6 The new method of coating conifer seedlings with fine sand provides an effective and environmentally sound alternative to insecticide treatment. [source] Cell wall phenolics of white and green asparagusJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2005Rocío Rodríguez Abstract Cinnamic acids influence physical and textural attributes of plant foods as they play an important role in lignification and cross-linking of cell-wall polymers. Several trans -cinnamic acids have been detected in asparagus cell wall (CW), and, of these, amounts of ferulic acid (FA) and its dehydrodimers have been found to increase significantly during post-harvest storage. The distribution of these compounds along the different sections of white and green spears, as well as their modifications during postharvest storage, has been investigated. It has been observed that the cell walls from the apical, middle and lower sections of the green spears contain equivalent amounts of FA derivatives (about 400 µg g,1 CW), while these compounds are mainly located in the middle (681 µg g,1 CW) and lower section (975 µg g,1 CW) of the white ones. During asparagus post-harvest storage a general increase of FA monomers and dimers took place that affected every section of both green and white spears. Major changes occurred in the middle and lower sections of the white asparagus, where the amounts of ferulic derivatives increased to 1700 and 1678 µg g,1 CW after storage. A similar but less pronounced trend was observed for the green spears. Copyright © 2005 Society of Chemical Industry [source] Hairy Root Culture in a Liquid-Dispersed Bioreactor: Characterization of Spatial HeterogeneityBIOTECHNOLOGY PROGRESS, Issue 3 2000Gary R. C. Williams A liquid-dispersed reactor equipped with a vertical mesh cylinder for inoculum support was developed for culture of Atropa belladonna hairy roots. The working volume of the culture vessel was 4.4 L with an aspect ratio of 1.7. Medium was dispersed as a spray onto the top of the root bed, and the roots grew radially outward from the central mesh cylinder to the vessel wall. Significant benefits in terms of liquid drainage and reduced interstitial liquid holdup were obtained using a vertical rather than horizontal support structure for the biomass and by operating the reactor with cocurrent air and liquid flow. With root growth, a pattern of spatial heterogeneity developed in the vessel. Higher local biomass densities, lower volumes of interstitial liquid, lower sugar concentrations, and higher root atropine contents were found in the upper sections of the root bed compared with the lower sections, suggesting a greater level of metabolic activity toward the top of the reactor. Although gas-liquid oxygen transfer to the spray droplets was very rapid, there was evidence of significant oxygen limitations in the reactor. Substantial volumes of non-free-draining interstitial liquid accumulated in the root bed. Roots near the bottom of the vessel trapped up to 3,4 times their own weight in liquid, thus eliminating the advantages of improved contact with the gas phase offered by liquid-dispersed culture systems. Local nutrient and product concentrations in the non-free-draining liquid were significantly different from those in the bulk medium, indicating poor liquid mixing within the root bed. Oxygen enrichment of the gas phase improved neither growth nor atropine production, highlighting the greater importance of liquid-solid compared with gas-liquid oxygen transfer resistance. The absence of mechanical or pneumatic agitation and the tendency of the root bed to accumulate liquid and impede drainage were identified as the major limitations to reactor performance. Improved reactor operating strategies and selection or development of root lines offering minimal resistance to liquid flow and low liquid retention characteristics are possible solutions to these problems. [source] | |||||||||||||