Genome-wide analysis of the UDP-glucose dehydrogenase gene family in Arabidopsis, a key enzyme for matrix polysaccharides in cell walls

Arabidopsis cell walls contain large amounts of pectins and hemicelluloses, which are predominantly synthesized via the common precursor UDP-glucuronic acid. The major enzyme for the formation of this nucleotide-sugar is UDP-glucose dehydrogenase, catalysing the irreversible oxidation of UDP-glucose into UDP-glucuronic acid. Four functional gene family members and one pseudogene are present in the Arabidopsis genome, and they show distinct tissue-specific expression patterns during plant development. The analyses of reporter gene lines indicate gene expression of UDP-glucose dehydrogenases in growing tissues. The biochemical characterization of the different isoforms shows equal affinities for the cofactor NAD+ (~40 µM) but variable affinities for the substrate UDP-glucose (120–335 µM) and different catalytic constants, suggesting a regulatory role for the different isoforms in carbon partitioning between cell wall formation and sucrose synthesis as the second major UDP-glucose-consuming pathway. UDP-glucose dehydrogenase is feedback inhibited by UDP-xylose. The relatively (compared with a soybean UDP-glucose dehydrogenase) low affinity of the enzymes for the substrate UDP-glucose is paralleled by the weak inhibition of the enzymes by UDP-xylose. The four Arabidopsis UDP-glucose dehydrogenase isoforms oxidize only UDP-glucose as a substrate. Nucleotide-sugars, which are converted by similar enzymes in bacteria, are not accepted as substrates for the Arabidopsis enzymes

Cell wall remodeling under abiotic stress

Plants exposed to abiotic stress respond to the unfavorable conditions at multiple levels. One challenge under drought stress is to reduce shoot growth while maintaining root growth, a process requiring differential cell wall synthesis and remodeling. Key players in this process are the formation of reactive oxygen species (ROS) and peroxidases, which initially cross-link phenolic compounds and glycoproteins of the cell walls causing stiffening. The function of ROS shifts after having converted all of the peroxidase substrates in the cell wall. If ROS-levels remain high during prolonged stress, OH°-radicals are formed which lead to polymer cleavage. In concert with xyloglucan modifying enzymes and expansins, the resulting cell wall loosening allows further growth of stressed organs

Everyday Leaders

For years business writers and speakers have focused on larger than life, charismatic Leaders, with a capital “L”. The implication is that the success of an organization is dependent on this one person and his or her ability to inspire everyone else to follow a unique vision. This focus on the Leader is at least a partial cause of the lack of trust we are witnessing in business organizations today. Leaders believe they must behave in some larger than life way. With the expectation that they must see things the rest of us do not, they make riskier and riskier decisions, desperate to prove they deserve the role. Perhaps now that we have seen the problems resulting from this Leader-focused approach to running our organizations, we can return to a more reasonable approach - one that is actually attainable by mere mortals - where many are called upon to be good, competent, everyday leaders. If educational institutions begin to focus on developing the skills and character of these everyday leaders, our organizations will not only be more successful, but surely more trusted than they are today

When Good Management Isnt Enough: The Story Of A Czech Business In The Twentieth Century

We teach management as a rational process: if you conscientiously apply the concepts learned, you will succeed.  However, for this equation to work certain underlying factors must be in place.  No matter how well prepared managers may be, events unfold around them that profoundly affect their organizations.  We may take the basic infrastructure of democratic capitalism for granted when we teach management education, but it doesn’t hurt to remind our students occasionally that these ‘givens’ aren’t always there.  By teaching our students to appreciate how remarkable is the achievement of democratic capitalism, will we be more likely to protect it and perhaps even improve upon it

Survival Behaviors Of 100-Year-Old West Michigan Retail And Service Companies

This study of small and medium size retail and service companies over 100 years old looks for common strategies that enabled the organizations to prosper for an unusually long period of time.  Four common behaviors are identified and compared to factors identified in previous studies of very large multinational companies of a similar age

DCD – a novel plant specific domain in proteins involved in development and programmed cell death

BACKGROUND: Recognition of microbial pathogens by plants triggers the hypersensitive reaction, a common form of programmed cell death in plants. These dying cells generate signals that activate the plant immune system and alarm the neighboring cells as well as the whole plant to activate defense responses to limit the spread of the pathogen. The molecular mechanisms behind the hypersensitive reaction are largely unknown except for the recognition process of pathogens. We delineate the NRP-gene in soybean, which is specifically induced during this programmed cell death and contains a novel protein domain, which is commonly found in different plant proteins. RESULTS: The sequence analysis of the protein, encoded by the NRP-gene from soybean, led to the identification of a novel domain, which we named DCD, because it is found in plant proteins involved in development and cell death. The domain is shared by several proteins in the Arabidopsis and the rice genomes, which otherwise show a different protein architecture. Biological studies indicate a role of these proteins in phytohormone response, embryo development and programmed cell by pathogens or ozone. CONCLUSION: It is tempting to speculate, that the DCD domain mediates signaling in plant development and programmed cell death and could thus be used to identify interacting proteins to gain further molecular insights into these processes

Entrepreneurial Attitudes Of MBA Students In The United States Relative To The CIS: The Case Of Armenia

This paper compares the entrepreneurial attributes of MBA students in Armenia to those in the United States.  If entrepreneurial attributes are more learned cultural behaviors and not only inherent personality factors, business students in a recently-privatized economy such as Armenia would not score as high on an entrepreneurial personality index as would business students in the U.S. where both models of entrepreneurship and expectations of certain proactive characteristics in individuals entering the business world are widespread

2006 NASA Range Safety Annual Report

Throughout 2006, Range Safety was involved in a number of exciting and challenging activities and events, from developing, implementing, and supporting Range Safety policies and procedures-such as the Space Shuttle Launch and Landing Plans, the Range Safety Variance Process, and the Expendable Launch Vehicle Safety Program procedures-to evaluating new technologies. Range Safety training development is almost complete with the last course scheduled to go on line in mid-2007. Range Safety representatives took part in a number of panels and councils, including the newly formed Launch Constellation Range Safety Panel, the Range Commanders Council and its subgroups, the Space Shuttle Range Safety Panel, and the unmanned aircraft systems working group. Space based range safety demonstration and certification (formerly STARS) and the autonomous flight safety system were successfully tested. The enhanced flight termination system will be tested in early 2007 and the joint advanced range safety system mission analysis software tool is nearing operational status. New technologies being evaluated included a processor for real-time compensation in long range imaging, automated range surveillance using radio interferometry, and a space based range command and telemetry processor. Next year holds great promise as we continue ensuring safety while pursuing our quest beyond the Moon to Mars