Protein Protection: Characterizing how CowN Protects Nitrogenase

Nitrogen fixation occurs in two major processes, the industrial haber bosch process and fixation via a biological enzyme called nitrogenase. The haber bosch process is how most nitrogen used in agriculture is converted into ammonia. However, one major drawback is that this process requires a lot of fossil fuels and is thereby not an environmentally friendly process. With nitrogenase, the enzyme converts dinitrogen into ammonia using biological energy in the form of ATP, making nitrogen fixation a more biologically friendly process. Carbon Monoxide is known to inhibit the function of nitrogenase, meaning that under conditions where CO is present, nitrogen fixation is unable to occur. In order to prevent CO inhibition, cells containing nitrogenase must find a way to avoid these inhibitory conditions. It was found that Nitrogenase seems to be protected by another protein, CowN. This poster describes the mechanism by which CowN protects Nitrogenase. Specifically, CowN binds to either the entrance to a proposed CO channel or near the active site of nitrogenase. Both potential CowN binding locations could prevent CO from reaching the active site and therefore enable nitrogenase to avoid inhibition by CO

Why They Fight: Combat Motivation in the Iraq War

With the recent lightning swift combat successes of Operation IRAQI FREEDOM, there may be a tendency to view with awe the lethality of U.S. technology and training. The researchers, however, argue that the true strength of America\u27s military might lies not in its hardware or high-tech equipment, but in its soldiers. Dr. Leonard Wong and his colleagues traveled to Iraq to see what motivated soldiers to continue in battle, to face extreme danger, and to risk their lives in accomplishing the mission. As a means of comparison, they began by interviewing Iraqi Regular Army prisoners of war to examine their combat motivation and unit dynamics. The researchers then interviewed U.S. combat troops fresh from the fields of battle to examine their views. What they found was that today\u27s U.S. soldiers, much like soldiers of the past, fight for each other. Unit cohesion is alive and well in today\u27s Army. Yet, Dr. Wong and his fellow researchers also found that soldiers cited ideological reasons such as liberation, freedom, and democracy as important factors in combat motivation. Today\u27s soldiers trust each other, they trust their leaders, they trust the Army, and they also understand the moral dimensions of war. This year marks the 30th anniversary of the all-volunteer Army. This monograph is a celebration of the success of that radical idea and the transformation of the U.S. Army from a demoralized draft army, to a struggling all-volunteer force, to a truly professional Army.https://press.armywarcollege.edu/monographs/1787/thumbnail.jp

Hemodynamic variability and cerebrovascular control after transient cerebral ischemia

We investigated if hemodynamic variability, cerebral blood flow (CBF) regulation, and their interrelationships differ between patients with transient ischemic attack (TIA) and controls. We recorded blood pressure (BP) and bilateral middle cerebral artery flow velocity (MCAv) in a cohort of TIA patients (n = 17), and age?matched controls (n = 15). Spontaneous fluctuations in BP and MCAv were characterized by spectral power analysis, and CBF regulation was assessed by wavelet phase synchronization analysis in the very low? (0.02–0.07 Hz), low? (0.07–0.20 Hz), and high?frequency (0.20–0.40 Hz) ranges. Furthermore, cerebrovascular CO2 reactivity was assessed as a second metric of CBF regulation by inducing hypercapnia with 8% CO2 inhalation followed by hyperventilation driven hypocapnia. We found that TIA was associated with higher BP power (group effect, P < 0.05), but not MCAv power (P = 0.11). CBF regulation (assessed by wavelet phase synchronization and CO2 reactivity) was intact in patients (all P ? 0.075) across both hemispheres (all P ? 0.51). Pooled data (controls and affected hemisphere of patients) showed that BP and MCAv power were positively correlated at all frequency ranges (R2 = 0.20–0.80, all P < 0.01). Furthermore, LF phase synchronization index was a significant determinant of MCAv power (P < 0.05), while VLF and HF phase synchronization index, and TIA were not (all P ? 0.50). These results indicate that CBF stability and control is maintained in TIA patients, but BPV is markedly elevated. BPV attenuation may be an important therapeutic strategy for enhancing secondary stroke prevention in patients who suffer a TIA

Mutational Analysis of the Nitrogenase Carbon Monoxide Protective Protein CowN Reveals That a Conserved C‑Terminal Glutamic Acid Residue Is Necessary for Its Activity

Nitrogenase is the only enzyme that catalyzes the reduction of nitrogen gas into ammonia. Nitrogenase is tightly inhibited by the environmental gas carbon monoxide (CO). Many nitrogen fixing bacteria protect nitrogenase from CO inhibition using the protective protein CowN. This work demonstrates that a conserved glutamic acid residue near the C-terminus of Gluconacetobacter diazotrophicus CowN is necessary for its function. Mutation of the glutamic acid residue abolishes both CowN’s protection against CO inhibition and the ability of CowN to bind to nitrogenase. In contrast, a conserved C-terminal cysteine residue is not important for CO protection by CowN. Overall, this work uncovers structural features in CowN that are required for its function and provides new insights into its nitrogenase binding and CO protection mechanism

Disclosure of sexual orientation to health professionals in China: results from an online cross-sectional study: Tang W et al.

Background: Many men who have sex with men (MSM) in China are “in the closet.” The low rate of disclosure may impact sexual behaviours, testing for HIV and other sexually transmitted infections (STIs), and diseases transmission. This study examines factors associated with overall sexual orientation disclosure and disclosure to healthcare professionals

Using Argo data to investigate the Meridional Overturning Circulation in the North Atlantic

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 57 (2010): 29-36, doi:10.1016/j.dsr.2009.10.003.Using a variety of oceanographic data, including direct volume transports in the Florida 19 Strait, and Argo float profiles and drift velocities at 24 and 36N in the North Atlantic, inverse calculations are presented in which the net meridional transport, 20 down to a depth of approximately 1600 m, is estimated at both latitudes for a five year period 2003-2007. The upper ocean is divided into 7 layers using neutral density, and mass conservation constraints have been applied to a closed box bounded by these latitudes, including the Florida Strait. Ekman layer transports have been included in the top-most layer, and the inverse calculation has solved for changes from the initial reference velocities, Ekman and Florida Strait transports, given a priori estimates on the accuracy of each of these quantities. Solutions with and without transformations due to Mediterranean Water (MW) formation are made. Our results indicate that 1) time-averaged transport estimates derived from Argo have significant less eddy noise than individual hydrographic sections, 2) Argo drift velocities provide information to the inverse solution for the ocean interior, and 3) comparison of the total integrated interior mass transports in the thermocline waters for the period 2003-2007 with the previous estimates based on trans-ocean hydrographic sections shows that the Meridional Overturning Circulation has not significantly changed since 1957.TJ would like to acknowledge support from NSF Grant OCE-0241354 and NOAA/CICOR grant NA17RJ1223