Rex1p Deficiency Leads to Accumulation of Precursor Initiator tRNA\u3csup\u3eMet\u3c/sup\u3e and Polyadenylation of Substrate RNAs in \u3cem\u3eSaccharomyces cerevisiae\u3c/em\u3e

A synthetic genetic array was used to identify lethal and slow-growth phenotypes produced when a mutation in TRM6, which encodes a tRNA modification enzyme subunit, was combined with the deletion of any non-essential gene in Saccharomyces cerevisiae. We found that deletion of the REX1 gene resulted in a slow-growth phenotype in the trm6-504 strain. Previously, REX1 was shown to be involved in processing the 3′ ends of 5S rRNA and the dimeric tRNAArg-tRNAAsp. In this study, we have discovered a requirement for Rex1p in processing the 3′ end of tRNAiMet precursors and show that precursor tRNAiMet accumulates in a trm6-504 rex1Δ strain. Loss of Rex1p results in polyadenylation of its substrates, including tRNAiMet, suggesting that defects in 3′ end processing can activate the nuclear surveillance pathway. Finally, purified Rex1p displays Mg2+-dependent ribonuclease activity in vitro, and the enzyme is inactivated by mutation of two highly conserved amino acids

An open environment CT-US fusion for tissue segmentation during interventional guidance.

Therapeutic ultrasound (US) can be noninvasively focused to activate drugs, ablate tumors and deliver drugs beyond the blood brain barrier. However, well-controlled guidance of US therapy requires fusion with a navigational modality, such as magnetic resonance imaging (MRI) or X-ray computed tomography (CT). Here, we developed and validated tissue characterization using a fusion between US and CT. The performance of the CT/US fusion was quantified by the calibration error, target registration error and fiducial registration error. Met-1 tumors in the fat pads of 12 female FVB mice provided a model of developing breast cancer with which to evaluate CT-based tissue segmentation. Hounsfield units (HU) within the tumor and surrounding fat pad were quantified, validated with histology and segmented for parametric analysis (fat: -300 to 0 HU, protein-rich: 1 to 300 HU, and bone: HU>300). Our open source CT/US fusion system differentiated soft tissue, bone and fat with a spatial accuracy of ∼1 mm. Region of interest (ROI) analysis of the tumor and surrounding fat pad using a 1 mm(2) ROI resulted in mean HU of 68±44 within the tumor and -97±52 within the fat pad adjacent to the tumor (p<0.005). The tumor area measured by CT and histology was correlated (r(2) = 0.92), while the area designated as fat decreased with increasing tumor size (r(2) = 0.51). Analysis of CT and histology images of the tumor and surrounding fat pad revealed an average percentage of fat of 65.3% vs. 75.2%, 36.5% vs. 48.4%, and 31.6% vs. 38.5% for tumors <75 mm(3), 75-150 mm(3) and >150 mm(3), respectively. Further, CT mapped bone-soft tissue interfaces near the acoustic beam during real-time imaging. Combined CT/US is a feasible method for guiding interventions by tracking the acoustic focus within a pre-acquired CT image volume and characterizing tissues proximal to and surrounding the acoustic focus

Predicting Older Drivers\u27 Difficulties Using the Roadwise Review

There has been a substantial growth in research attempting to predict accidents and performance in older drivers. The Roadwise Review and the substantively identical Driver Health Inventory have been reported to provide a valid and cost-effective means of assessing crash risk in older communitydwelling adults. We administered the DHI to a community-dwelling sample of older (45 - 85 years) drivers. We also asked them to report on the difficulties they experienced while driving and on the frequency and type of crashes and moving violations the experienced in the previous two years. Results indicated on several of the tests there are substantial floor or ceiling effects, as well as barriers to usability and acceptance. Low inter-test correlations are consistent with the notion that different capacities are being indexed with the DHI. However, generally there were only low correlations between DHI performance and self-reported difficulties in driving, accidents or moving violations. While the DHI and Roadwise Review may well be valuable in providing older drivers with information on skills related to driving performance, in its current form it does not appear to be a useful tool in licensure or the prediction of driver risk

Targeting Hispanic Immigrants with Food Safety Communications

Hispanics are the largest minority population in the United States, according to the 2000 U.S. Census, and the fastest growing. If they are immigrants, they are often dealing with cultural issues as well as new technological applications and social systems. The need for education programs and dissemination of food safety information to this growing segment of the population is evident. This study sought to determine the group’s knowledge of food safety and its primary channels for receiving such information. A questionnaire was developed and translated into Spanish. Face-to-face data collection facilitated by a trusted community partner proved to be a successful means of collecting data from this audience, who are often difficult to reach and may be unwilling to speak with people associated with government. Specific areas of lack of knowledge emerged. The respondents struggled most with questions about proper handling of leftovers containing meat, accurate water temperature for washing and rinsing dishes, handling frozen foods, and defrosting meat. From the attitude questions, the authors found that the target group felt food safety was important, was more threatened in food service outlets than in the home, and was overemphasized. The channel used most frequently and trusted most was television

Identification of Saccharomyces cerevisiae Spindle Pole Body Remodeling Factors

The Saccharomyces cerevisiae centrosome or spindle pole body (SPB) is a dynamic structure that is remodeled in a cell cycle dependent manner. The SPB increases in size late in the cell cycle and during most cell cycle arrests and exchanges components during G1/S. We identified proteins involved in the remodeling process using a strain in which SPB remodeling is conditionally induced. This strain was engineered to express a modified SPB component, Spc110, which can be cleaved upon the induction of a protease. Using a synthetic genetic array analysis, we screened for genes required only when Spc110 cleavage is induced. Candidate SPB remodeling factors fell into several functional categories: mitotic regulators, microtubule motors, protein modification enzymes, and nuclear pore proteins. The involvement of candidate genes in SPB assembly was assessed in three ways: by identifying the presence of a synthetic growth defect when combined with an Spc110 assembly defective mutant, quantifying growth of SPBs during metaphase arrest, and comparing distribution of SPB size during asynchronous growth. These secondary screens identified four genes required for SPB remodeling: NUP60, POM152, and NCS2 are required for SPB growth during a mitotic cell cycle arrest, and UBC4 is required to maintain SPB size during the cell cycle. These findings implicate the nuclear pore, urmylation, and ubiquitination in SPB remodeling and represent novel functions for these genes

CU Defense - Lightweight Cranial Protection and Low Altitude Parachute Systems

The Clemson family proudly embraces its school\u27s rich military heritage and students in every department regularly demonstrate patriotism and respect for our nation\u27s armed forces. Our multidisciplinary team of undergraduates has sought to study and improve currently used technology to give soldiers an advantage in the field. We currently have two active projects, as described below. Lightweight Cranial Protection Current standard-issue combat helmets weigh more and offer less protection than desired. Equipment weight reduction is a constant goal for the armed forces, and enhanced safety is always favored. With recent technological developments in the application of dilatants, or shear-thickening fluids (STF), it appears that a helmet\u27s design and construction can be improved. We intend to apply several STF compositions to selected ballistic fibers using multiple impregnation methods. The resulting fibers will be tested for variations in ballistic performance. Low Altitude Parachute System currently used parachutes are designed to inflate slowly to avoid injury on opening. As a result, there is a range of heights that are too low for current parachutes to behave effectively. Using past current research and simulation software, we intend to study the various shapes and sizes of parachutes used throughout history and design a parachute system that will be effective at these low altitudes. This research could lead to the development of products that vastly increase the quality of life and safety of military, law enforcement, and rescue operations

Functional Link Between Mitochondria and Rnr3, the Minor Catalytic Subunit of Yeast Ribonucleotide Reductase

International audienceRibonucleotide reductase (RNR) is an essential holoenzyme required for de novo synthesis of dNTPs. The Saccharomyces cerevisiae genome encodes for two catalytic subunits, Rnr1 and Rnr3. While Rnr1 is required for DNA replication and DNA damage repair, the function(s) of Rnr3 is unknown. Here, we show that carbon source, an essential nutrient, impacts Rnr1 and Rnr3 abundance: Non-fermentable carbon sources or limiting concentrations of glucose down regulate Rnr1 and induce Rnr3 expression. Oppositely, abundant glucose induces Rnr1 expression and down regulates Rnr3. The carbon source dependent regulation of Rnr3 is mediated by Mec1, the budding yeast ATM/ATR checkpoint response kinase. Unexpectedly, this regulation is independent of all currently known components of the Mec1 DNA damage response network, including Rad53, Dun1, and Tel1, implicating a novel Mec1 signalling axis. rnr3Δ leads to growth defects under respiratory conditions and rescues temperature sensitivity conferred by the absence of Tom6, a component of the mitochondrial TOM (translocase of outer membrane) complex responsible for mitochondrial protein import. Together, these results unveil involvement of Rnr3 in mitochondrial functions and Mec1 in mediating the carbon source dependent regulation of Rnr3