Alteration of host cell ubiquitination by the intracellular bacterial pathogen Coxiella burnetii

The intracellular bacterial agent of Q fever, Coxiella burnetii, replicates within a phagolysosomelike parasitophorous vacuole (PV) in human macrophages and delivers effector proteins to the host cytosol via a Dot/Icm type IV secretion system (T4SS). The T4SS effectors are critical for PV formation and prevention of host cell death that allows sufficient time for bacterial replication. Recruitment of ubiquitin-related components to the C. burnetii PV is also predicted to be involved in PV formation and bacterial replication and is likely controlled by effector proteins. In this study, we assessed the role of the Dot/Icm T4SS in regulating ubiquitination by comparing subcellular localization of ubiquitinated proteins between cells infected with C. burnetii and a mutant that lacks a functional T4SS. Fluorescence microscopy showed ubiquitinated proteins surrounding wild-type C. burnetii PV but not phagosomes harboring T4SS-defective organisms. Immunoblot analysis showed altered ubiquitinated protein profiles throughout infection, suggesting C. burnetii impacts post-translational modification of host cell and/or bacterial proteins. Future studies will determine how T4SS-mediated recruitment of ubiquitinated proteins impacts C. burnetii-host cell interactions and eventual development of diseas

Components, production processes, and recommendations for future research in organic light emitting diodes

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 29).Organic Light Emitting Diodes (OLEDs) are small, optoelectronic devices that can be used in the production of energy-efficient, high definition displays in cell phones, computers, and televisions. These devices have great potential to replace light emitting diodes (LEDs) completely because they are more environmentally friendly to produce, they are more efficient, and they can create displays much thinner than current LED displays. Moreover, OLEDs allow for the creation of brighter, flexible screens. While these devices have great potential, it has not been realized yet due to cost and difficulty in optimizing production processes. Many companies have been attempting to produce affordable OLED displays for years, but have not been successful due to lack of optimization of production processes. Work should continue to be done in economic optimization of the processes and also optimization of energy efficiency of the devices.by Lindsay Hunting.S.B

SPS fiber optic link assessment

Fiber optic technology was tentatively selected in the SPS baseline design to transmit a stable phase reference throughout microwave array. Over a hundred thousand microwave modules are electronically steered by the phase reference signal to form the power beam at the ground receiving station. The initially selected IF distribution frequency of the phase reference signal was at 980 MHz or a submultiple of it. Fiber optics offers some significant advantages in view of the SPS application. Optical transmission is highly immune to EMI/RFI, which is expected to be severe when considering the low distribution power. In addition, there are savings in both mass, physical size, and potentially in cost