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

M1-linked ubiquitination by LUBEL is required for inflammatory responses to oral infection in Drosophila

Post-translational modifications such as ubiquitination play a key role in regulation of inflammatory nuclear factor-κB (NF-κB) signalling. The Drosophila IκB kinase γ (IKKγ) Kenny is a central regulator of the Drosophila Imd pathway responsible for activation of the NF-κB Relish. We found the Drosophila E3 ligase and HOIL-1L interacting protein (HOIP) orthologue linear ubiquitin E3 ligase (LUBEL) to catalyse formation of M1-linked linear ubiquitin (M1-Ub) chains in flies in a signal-dependent manner upon bacterial infection. Upon activation of the Imd pathway, LUBEL modifies Kenny with M1-Ub chains. Interestingly, the LUBEL-mediated M1-Ub chains seem to be targeted both directly to Kenny and to K63-linked ubiquitin chains conjugated to Kenny by DIAP2. This suggests that DIAP2 and LUBEL work together to promote Kenny-mediated activation of Relish. We found LUBEL-mediated M1-Ub chain formation to be required for flies to survive oral infection with Gram-negative bacteria, for activation of Relish-mediated expression of antimicrobial peptide genes and for pathogen clearance during oral infection. Interestingly, LUBEL is not required for mounting an immune response against systemic infection, as Relish-mediated antimicrobial peptide genes can be expressed in the absence of LUBEL during septic injury. Finally, transgenic induction of LUBEL-mediated M1-Ub drives expression of antimicrobial peptide genes and hyperplasia in the midgut in the absence of infection. This suggests that M1-Ub chains are important for Imd signalling and immune responses in the intestinal epithelia, and that enhanced M1-Ub chain formation is able to drive chronic intestinal inflammation in flies

Proteomic resolution of IGFN1 complexes reveals a functional interaction with the actin nucleating protein COBL

The Igfn1 gene produces multiple proteins by alternative splicing predominantly expressed in skeletal muscle. Igfn1 deficient clones derived from C2C12 myoblasts show reduced fusion index and morphological differences compared to control myotubes. Here, we first show that G:F actin ratios are significantly higher in differentiating IGFN1-deficient C2C12 myoblasts, suggesting that fusion and differentiation defects are underpinned by deficient actin remodelling. We obtained pull-downs from skeletal muscle with IGFN1 fragments and applied a proteomics approach. The proteomic composition of IGFN1 complexes identified the cytoskeleton and an association with the proteasome as the main networks. The actin nucleating protein COBL was selected for further validation. COBL is expressed in C2C12 myoblasts from the first stages of myoblast fusion but not in proliferating cells. COBL is also expressed in adult muscle and, as IGFN1, localizes to the Z-disc. We show that IGFN1 interacts, stabilizes and colocalizes with COBL and prevents the ability of COBL to form actin ruffles in COS7 cells. COBL loss of function C2C12-derived clones are able to fuse, therefore indicating that COBL or the IGFN1/COBL interaction are not essential for myoblast fusion

Total and CO-reactive heme content of actinorhizal nodules and the roots of some non-nodulated plants

The concentration of total and CO-reactive heme was measured in actinorhizal nodules from six different genera. This gave the upper limit to hemoglobin concentration in these nodules. Quantitative extraction of CO-reactive heme was achieved under anaerobic conditions in a buffer equilibrated with CO and containing Triton X-100. The concentration of CO-reactive heme in nodules of Casuarina and Myrica was approximately half of that found in legume nodules, whereas in Comptonia, Alnus and Ceanothus the concentrations of heme were about 10 times lower than in legume nodules. There was no detectable CO-reactive heme in Datisca nodules, but low concentrations were detected in roots of all non-nodulating plants examined, including Zea mays . Difference spectra of CO treated minus dithionite-reduced extracts displayed similar wavelengths of maximal and minimal light absorption for all extracts, and were consistent with those of a hemoglobin. The concentration of CO-reactive heme was not correlated to the degree to which CO inhibited nitrogenase activity nor was it affected by reducing the oxygen concentration in the rooting zone. However, there was a positive correlation between heme concentration and suberization or lignification of the walls of infected host cells. These observations demonstrate that, unlike legume nodules, high concentrations of heme or hemoglobin are not needed for active nitrogen fixation in most actinorhizal nodules. Nonetheless, a significant amount of CO-reactive heme is found in the nodules of Alnus, Comptonia, and Ceanothus, and in the roots of Zea mays . The identity and function of this heme is unknown.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43460/1/11104_2006_Article_BF02370943.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

Adaptive Significance Of Nyctinastic And Related Leaf Movements.

PhDBotanyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/188431/2/7014639.pd