On upwelling, eutrophic lakes, the primitive biosphere, and biological membranes

1981 ◽  
pp. 522-529 ◽  
Author(s):  
Ramon Margalef ◽  
Marta Estrada
Keyword(s):  
Biological Membranes ◽  
Eutrophic Lakes

Electron Diffraction of Wet Biological Membranes

1974 ◽  
Vol 32 ◽  
pp. 158-159
Author(s):  
S.W. Hui ◽  
D.F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Data Collection ◽  
Biological Membranes ◽  
Small Areas ◽  
Electron Diffraction Technique ◽  
Electron Microscopes ◽  
Collection Time ◽  
Camera Length

The development of the hydration stages for electron microscopes has opened up the application of electron diffraction in the study of biological membranes. Membrane specimen can now be observed without the artifacts introduced during drying, fixation and staining. The advantages of the electron diffraction technique, such as the abilities to observe small areas and thin specimens, to image and to screen impurities, to vary the camera length, and to reduce data collection time are fully utilized. Here we report our pioneering work in this area.

Observation of Concanavalin-A receptors on hydrated planar erythrocyte membrane film by in situ electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 608-609
Author(s):  
Neng-Bo He ◽  
S.W. Hui
Keyword(s):  
Lipid Bilayers ◽  
Erythrocyte Membrane ◽  
Lipid Membranes ◽  
Surface Film ◽  
Biological Membranes ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Black Lipid Membranes ◽  
Fine Mesh ◽  
Planar Films

Monolayers and planar "black" lipid membranes have been widely used as models for studying the structure and properties of biological membranes. Because of the lack of a suitable method to prepare these membranes for electron microscopic observation, their ultrastructure is so far not well understood. A method of forming molecular bilayers over the holes of fine mesh grids was developed by Hui et al. to study hydrated and unsupported lipid bilayers by electron diffraction, and to image phase separated domains by diffraction contrast. We now adapted the method of Pattus et al. of spreading biological membranes vesicles on the air-water interfaces to reconstitute biological membranes into unsupported planar films for electron microscopic study. hemoglobin-free human erythrocyte membrane stroma was prepared by hemolysis. The membranes were spreaded at 20°C on balanced salt solution in a Langmuir trough until a surface pressure of 20 dyne/cm was reached. The surface film was repeatedly washed by passing to adjacent troughs over shallow partitions (fig. 1).

scholarly journals Spatio-temporal Variation in Nutrient Profiles and Exchange Fluxes at the Sediment-Water Interface in Yuqiao Reservoir, China

2019 ◽  
Vol 16 (17) ◽  
pp. 3071 ◽  
Author(s):  
Wen ◽  
Wu ◽  
Yang ◽  
Jiang ◽  
Zhong
Keyword(s):  
Pore Water ◽  
Water Source ◽  
Water Soluble ◽  
Drinking Water Source ◽  
Eutrophic Lakes ◽  
Overlying Water ◽  
Total N ◽  
Yuqiao Reservoir ◽  
Nutrient Profiles ◽  
Main Component

Nutrients released from sediments have a significant influence on the water quality in eutrophic lakes and reservoirs. To clarify the internal nutrient load and provide reference for eutrophication control in Yuqiao Reservoir, a drinking water source reservoir in China, pore water profiles and sediment core incubation experiments were conducted. The nutrients in the water (soluble reactive P (SRP), nitrate-N (NO3−-N), nitrite-N (NO2−-N), and ammonium-N (NH4+-N)) and in the sediments (total N (TN), total P (TP) and total organic carbon (TOC)) were quantified. The results show that NH4+-N was the main component of inorganic N in the pore water. NH4+-N and SRP were higher in the pore water than in the overlying water, and the concentration gradient indicated a diffusion potential from the sediment to the overlying water. The NH4+-N, NO3−-N, and SRP fluxes showed significant differences amongst the seasons. The NH4+-N and SRP fluxes were significantly higher in the summer than in other seasons, while NO3−-N was higher in the autumn. The sediment generally acted as a source of NH4+-N and SRP and as a sink for NO3−-N and NO2−-N. The sediments release 1133.15 and 92.46 tons of N and P, respectively, to the overlying water each year.

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