A Monomer-to-Trimer Transition of the Human Mitochondrial Transcription Termination Factor (mTERF) Is Associated with a Loss of in Vitro Activity

The human mitochondrial transcription termination factor (mTERF) is a nuclear-encoded 39-kDa protein that recognizes a mtDNA segment within the mitochondrial tRNALeu(UUR) gene immediately adjacent to and downstream of the 16 S rRNA gene. Binding of mTERF to this site promotes termination of rDNA transcription. Despite the fact that mTERF binds DNA as a monomer, the presence in its sequence of three leucine-zipper motifs suggested the possibility of mTERF establishing intermolecular interactions with proteins of the same or different type. When a mitochondrial lysate from HeLa cells was submitted to gel filtration chromatography, mTERF was eluted in two peaks, as detected by immunoblotting. The first peak, which varied in proportion between 30 and 50%, appeared at the position expected from the molecular mass of the monomer (41 ± 2 kDa), and the gel filtration fractions that contained it exhibited DNA binding activity. Most interestingly, the material in this peak had a strong stimulating activity on in vitro transcription of the mitochondrial rDNA. The second peak eluted at a position corresponding to an estimated molecular mass of 111 ± 5 kDa. No mTERF DNA binding activity could be detected in the corresponding gel filtration fractions. Therefore, we propose that mTERF exists in mitochondria in two forms, an active monomer and an inactive large size complex. The estimated molecular weight of this complex and the fact that purified mTERF can be eluted from a gel filtration column as a complex of the same molecular weight strongly suggest that this inactive complex is a homotrimer of mTERF

Post-transcriptional nucleotide modification and alternative folding of RNA

Alternative foldings are an inherent property of RNA and a ubiquitous problem in scientific investigations. To a living organism, alternative foldings can be a blessing or a problem, and so nature has found both, ways to harness this property and ways to avoid the drawbacks. A simple and effective method employed by nature to avoid unwanted folding is the modulation of conformation space through post-transcriptional base modification. Modified nucleotides occur in almost all classes of natural RNAs in great chemical diversity. There are about 100 different base modifications known, which may perform a plethora of functions. The presumably most ancient and simple nucleotide modifications, such as methylations and uridine isomerization, are able to perform structural tasks on the most basic level, namely by blocking or reinforcing single base-pairs or even single hydrogen bonds in RNA. In this paper, functional, genomic and structural evidence on cases of folding space alteration by post-transcriptional modifications in native RNA are reviewed

A Model, Integrated Language Arts and U.S. History Curriculum Developed in Alignment with the Washington State Essential Academic Learning Requirements

The purpose of this project was to develop a model, integrated Language Arts and U.S. History curriculum at Foothills Middle School, Wenatchee, Washington, in alignment with the Washington State Essential Academic Learning Requirements (EALR\u27s). To accomplish this purpose, current research and literature was reviewed. Additionally, related information from selected sources was obtained and analyzed

Magnetotransport evidence of irreversible spin reorientation in the collinear antiferromagnetic state of underdoped Nd2−xCexCuO4\mathrm{Nd}_{2-x}\mathrm{Ce}_x\mathrm{CuO}_4

We make use of the strong spin-charge coupling in the electron-doped cuprate $\mathrm{Nd}_{2-x}\mathrm{Ce}_x\mathrm{CuO}_4$ to probe changes in its spin system via magnetotransport measurements. We present a detailed study of the out-of-plane magnetoresistance in underdoped single crystals of this compound, including the nonsuperconducting, $0.05\,\leq x\,\leq 0.115$, and superconducting, $0.12\,\leq x\,\leq 0.13$, compositions. Special focus is put on the dependence of the magnetoresistance on the field orientation in the plane of the CuO$_2$ layers. In addition to the kink at the field-induced transition between the noncollinear and collinear antiferromagnetic configurations, a sharp irreversible feature is found in the angle-dependent magnetoresistance of all samples in the high-field regime, at field orientations around the Cu--O--Cu direction. The obtained behavior can be explained in terms of field-induced reorientation of Cu$^{2+}$ spins within the collinear antiferromagnetic state. It is, therefore, considered as an unambiguous indication of the long-range magnetic order

Use of induced acceleration to quantify the (de)stabilization effect of external and internal forces on postural responses

Due to the mechanical coupling between the body segments, it is impossible to see with the naked eye the causes of body movements and understand the interaction between movements of different body parts. The goal of this paper is to investigate the use of induced acceleration analysis to reveal the causes of body movements. We derive the analytical equations to calculate induced accelerations and evaluate its potential to study human postural responses to support-surface translations. We measured the kinematic and kinetic responses of a subject to sudden forward and backward translations of a moving platform. The kinematic and kinetics served as input to the induced acceleration analyses. The induced accelerations showed explicitly that the platform acceleration and deceleration contributed to the destabilization and restabilization of standing balance, respectively. Furthermore, the joint torques, coriolis and centrifugal forces caused by swinging of the arms, contributed positively to stabilization of the center of mass. It is concluded that induced acceleration analyses is a valuable tool in understanding balance responses to different kinds of perturbations and may help to identify the causes of movement in different pathologies

An Examination of Intragroup Process in Service-Learning Teams

Small group work performed in the context of university service-learning projects has been seen as a vehicle well-suited to teaching students about group dynamics and how to work on real world problems as members of a team. Little research, however, has focused on the intragroup processes involved in service-learning. The present study was conducted in the context of a service-learning project in which twenty groups of four to five university business school students taught continuation high school students a series of lessons regarding life skills such as goal setting and career readiness. The lesson planning sessions of the university students were video recorded and the videos were then analyzed for patterns of utterances by group participants (questions; instructions; suggestions; etc.) that occurred during the sessions. An iterative process of coding and recoding was employed to capture each behavior for further study. The results suggest that the groups engaged in a surprising level of meaningful collaboration, with leadership shared among group members, and little evidence of individual dominance of groups, or conflict between students

Use of Specific Chemical Reagents for Detection of Modified Nucleotides in RNA

Naturally occurring cellular RNAs contain an impressive number of chemically distinct modified residues which appear posttranscriptionally, as a result of specific action of the corresponding RNA modification enzymes. Over 100 different chemical modifications have been identified and characterized up to now. Identification of the chemical nature and exact position of these modifications is typically based on 2D-TLC analysis of nucleotide digests, on HPLC coupled with mass spectrometry, or on the use of primer extension by reverse transcriptase. However, many modified nucleotides are silent in reverse transcription, since the presence of additional chemical groups frequently does not change base-pairing properties. In this paper, we give a summary of various chemical approaches exploiting the specific reactivity of modified nucleotides in RNA for their detection

Natural convection in high heat flux tanks at the Hanford Waste Site / [by] Mark van der Helm and Mujid S. Kazimi

"February 1996."Series statement handwritten on title-pagePage 118 blankAlso issued as an M.S. thesis written by the first author, and supervised by the second author, MIT Dept. of Nuclear EngineeringIncludes bibliographical references (pages 115-117)A study was carried out on the potential for natural convection and the effect of natural convection in a High Heat Flux Tank, Tank 241-C-106, at the Hanford Reservation. To determine the existence of natural convection, multiple computations based on analytical models were made knowing the tank geometry and contents' thermal characteristics. Each computation of the existence of natural convection was based on the determination of the onset of natural convection generalizing the tank as a 1-D porous medium. Computations were done for a range of permeabilities considering the porous medium alone, with a superposed fluid layer, and with a salt gradient. Considering only the porous medium, the higher permeability value, 3.2 *10-10 ft2, allowed convection, though the lower permeability, 2.6*10-14 ft2, did not. The presence of the superposed layer induced convection throughout the porous medium for the full range of permeabilities.Considering the effect of the salt gradient and superposed layer together, the effect of the superposed layer is expected to induce convection despite the stabilizing salt gradient. Therefore, natural convection is expected to exist in Tank 241-C-106. Secondly, because temperature measurements indicated lower temperatures at a location near the center of the tank, a thermal model was used to compute the local effects of a convective annulus around a thermocouple tree at that location. A conduction model of the tank and surroundings was used to bound the local model. The local model allowing convection in the annulus set the size of the annulus based on the known temperature measurements of the thermocouple tree and the boundary conditions set by the conduction model. Previous published calculations on Tank 241-C-106, allowing for only conduction within the tank, reported a steam region at the bottom of the tank with an approximately 24 foot radius.In the present analysis, using the computer code, TEMPEST, it is found that the cooling effect of the annulus creates a region with a 12 foot radius surrounding the thermocouple tree in which the temperature is suppressed below the saturation temperature due to the effects of the convective annulus. The annulus gap width for matching temperatures and the boundary conditions is on the order of 1 inch

Critical Analysis of the Value of Drought Information and Impacts on Land Management and Public Health

This paper reviews previous efforts to assign monetary value to climatic or meteorological information, such as public information on drought, climate, early warning systems, and weather forecast information. Methods and tools that have been explored to examine the benefits of climatic and meteorological information include the avoided cost, contingent valuation, choice experiments, benefit transfer, and descriptive approaches using surveys. The second part of this paper discusses specific considerations related to valuing drought information for public health and the Bureau of Land Management. We found a multitude of connections between drought and the land management and health sectors in the literature. The majority of the papers that we summarized only report biophysical change, because the economic losses of drought are not available. Only a few papers reported economic loss associated with drought. To determine the value of drought information, we need to know more about the role it plays in decision making and what sources of drought information are used in different sectors. This inventory of methods and impacts highlights opportunities for further research in valuing drought information in land management and public health