Chemical And Physical Characteristics Of Shallow Ground Waters In Northern Michigan Bogs, Swamps, And Fens

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141864/1/ajb213368.pd

A comparison of vascular vegetation and protozoan communities in some freshwater wetlands of Northern Lower Michigan

Vascular vegetation and protozoan communities were sampled in seven wetland sites — two bogs, two fens, two marshes, and one ‘swamp’ — in summer 1977. Two similarity indices were used to compare vascular vegetation and Protozoa from each site with all the other sites. Bog sites were the most distinct from other wetland types with respect to chemical and physical characteristics, dominant vascular vegetation, and protozoan species composition. The ‘swamp’ site had the highest similarity to all other sites with respect to both dominant vascular vegetation and protozoan species. Protozoan communities from different wetland types were much more similar than dominant vascular species; however, the pattern of similarity between wetland sites was very similar for both groups (Pearson product-moment correlation coefficient = 0.76).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42912/1/10750_2004_Article_BF02187032.pd

A model describing photosynthesis in terms of gas diffusion and enzyme kinetics

A model predicting net photosynthesis of individual plant leaves for a variety of environmental conditions has been developed. It is based on an electrical analogue describing gas diffusion from the free atmosphere to the sites of CO 2 fixation and a Michaelis-Menten equation describing CO 2 fixation. The model is presented in two versions, a simplified form without respiration and a more complex form including respiration. Both versions include terms for light and temperature dependence of CO 2 fixation and light control of stomatal resistance. The second version also includes terms for temperature, light, and oxygen dependence of respiration and O 2 dependence of CO 2 fixation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47495/1/425_2004_Article_BF00387066.pd

Hemoglobin in Frankia, a Nitrogen-Fixing Actinomycete

Frankia strain CcI3 grown in culture produced a hemoglobin which had optical absorption bands typical of a hemoglobin and a molecular mass of 14.1 kDa. Its equilibrium oxygen binding constant was 274 nM, the oxygen dissociation rate constant was 56 s(−1), and the oxygen association rate constant was 206 μM(−1) s(−1)

Hemoglobin in five genetically diverse Frankia strains

Five strains of Frankia were selected to represent a wide range of genetic diversity and examined for presence of hemoglobin. All five strains produced hemoglobin when grown on media without (N) or with (+N) combined nitrogen. This indicates that hemoglobin is common in Frankia and is not directly associated with nitrogen fixation. Frankia strain EAN1pec was examined in more detail. It showed greater hemoglobin concentration when grown at 2% O2 than at 20% O2 in the N treatment but no effect of oxygen on hemoglobin concentration in the +N treatment. At both oxygen levels, it produced substantially more biomass in +N than in N culture. It also produced significantly more biomass when the medium contained 0.2% CO2 than in the absence of CO2. The molecular mass of the hemo- globin as determined by size exclusion chromatography was 13.4 ± 0.2 kDa (mean ± SE, n = 3) and is consistent with that of a truncated hemoglobin. The hemoglobin had absorption spectra that were typical of a hemoglobin. The oxygen dissociation rate constants for the hemoglobin were 131.2 ± 5.8 s1 for N culture and 166 ± 8.2 s1 for +N culture. These rapid rates are consistent with a function in facilitated diffusion of oxygen.Key words: Frankia, hemoglobin, truncated hemoglobin