Bibliography of research studies in music at Boston University to 1955.

Thesis (M.S.)--Boston Universit

Precursor proteins are transported into mitochondria in the absence of proteolytic cleavage of the additional sequences

Many nuclear-coded mitochondrial proteins are synthesized as larger precursor polypeptides that are proteolytically processed during import into the mitochondrion. This processing appears to be catalyzed by a soluble, metal-dependent protease localized in the mitochondrial matrix. In this report we employ an in vitro system to investigate the role of processing in protein import. Intact Neurospora crassa mitochondria were incubated with radiolabeled precursors in the presence of the chelator o-phenanthroline. Under these conditions, the processing of the precursors of the beta-subunit of F1-ATPase (F1 beta) and subunit 9 of the F0F1-ATPase was strongly inhibited. Protease- mapping studies indicated that import of the precursor proteins into the mitochondria continued in the absence of processing. Upon readdition of divalent metal to the treated mitochondria, the imported precursors were quantitatively converted to their mature forms. This processing of imported precursors occurred in the absence of a mitochondrial membrane potential and was extremely rapid even at 0 degrees C. This suggests that all or part of the polypeptide chain of the imported precursors had been translocated into the matrix location of the processing enzyme. Localization experiments suggested that the precursor to F1 beta is peripherally associated with the mitochondrial membrane while the precursor to subunit 9 appeared to be tightly bound to the membrane. We conclude that proteolytic processing is not necessary for the translocation of precursor proteins across mitochondrial membranes, but rather occurs subsequent to this event. On the basis of these and other results, a hypothetical pathway for the import of F1 beta and subunit 9 is proposed

On determinism and well-posedness in multiple time dimensions

We study the initial value problem for the wave equation and the ultrahyperbolic equation for data posed on initial surface of mixed signature (both spacelike and timelike). Under a nonlocal constraint, we show that the Cauchy problem on codimension-one hypersurfaces has global unique solutions in the Sobolev spaces $H^{m}$, thus it is well-posed. In contrast, we show that the initial value problem on higher codimension hypersurfaces is ill-posed, at least when specifying a finite number of derivatives of the data, due to the failure of uniqueness. This is in contrast to a uniqueness result which Courant and Hilbert deduce from Asgeirsson's mean value theorem, for which we give an independent derivation. The proofs use Fourier synthesis and the Holmgren-John uniqueness theorem

Transfer of proteins into mitochondria

The precursor form of Neurospora crassa mitochondrial ADP/ATP carrier synthesized in a cell-free protein-synthesizing system can be imported into isolated mitochondria. If the mitochondrial transmembrane potential is abolished, import does not occur but the precursor binds to the mitochondrial surface. Upon reestablishment of the membrane potential, the bound precursor is imported. This occurs without dissociation of the bound precursor from the mitochondrial surface. We conclude that the binding observed represents an interaction with receptor sites and thus is an early step in the import pathway

Proteinaceous receptors for the import of mitochondrial precursor proteins

Mild trypsin treatment of isolated Neurospora mitochondria strongly inhibits their ability to bind and import the precursors of several mitochondrial proteins. Evidence is presented for two proteins, the ADP/ATP carrier and the mitochondrial porin, that specific binding of the precursors to the outer surface of the mitochondria is affected by the protease treatment. We suggest that the receptors that mediate the import of these two precursors are proteinaceous. Treatment of mitochondria with elastase also inhibits the binding and import of the ADP/ATP carrier and the porin. In contrast the import of the precursors of subunits 2 and 9 of the mitochondrial proton-translocating ATPase was unaffected by elastase treatment at the concentrations used. We suggest that the import pathways of the latter two proteins are distinct from those of the ADP/ATP carrier and the porin

Postcard: People Standing In Front of Williams Studio, Madison, Kansas

This black and white photographic postcard features a building in Madison, Kansas. Williams Studio is painted on the window. Three men and three women stand in front of the building. An automobile is on the street to the right of the people. An advertisement for clothing is in the background on the right. Handwriting is on the back of the card.https://scholars.fhsu.edu/tj_postcards/1985/thumbnail.jp

Carrier Phase Recovery for Coherent Optical Transmission Systems

This thesis presents studies concerned with the evaluation of the suitablility of an optical-phase-locked-loop (OPLL) as a component in a coherent optical transmission network. The performance of various binary optical transmission schemes, measured by the probability of error (Bit Error Rate), is presented. The linewidths of semiconductor diode lasers are, in general, not optimally suited to coherent transmission formats and therefore an additional power penalty must be paid if such sources are to be used. This power penalty is included in the analysis of a binary PSK transmission. The performance analysis of coherent transmission schemes is extended to encompass multi-level signalling formats. It is shown that, with the use of a sufficient number of signalling levels, these schemes can provide a receiver sensitivity which is better than a shot noise limited binary PSK transmission even when subject to the effects of high laser line width. A discussion on the properties of the laser diode, which are of interest in the design of a coherent optical transmission scheme (the source linewidth, modulation charateristics, wavelength tunablity and frequency and power stability), is provided. Measurements of these properties is given along with documentation of experimental attempts to reduce the linewidth of the laser emission. Linewidth reductions from between five and ten Megahertz down to tens of kilohertz were obtained. An analysis of the performance of an OPLL, taking into consideration the effect of phase instability of the laser diode source, is given. This analysis predicts that present day laser diodes can be used in the construction of the OPLL provided that the loop bandwidth is sufficiently large to account for the laser instability, while not being excessively large such that the performance is impaired by the influence of shot noise. This analysis is extended to describe the effect which the loop transport delay will have on such a loop, as the required loop bandwidth is extended. Similar calculations are performed to evaluate the effect of the loop receiver amplifier bandwidth. An evaluation of the OPLL response in the time domain, with the use of the Root Locus construction technique and a digital simulation, is presented. This analysis supports the findings of the analysis described above. The simulation of the loop dynamic response is found to be in reasonable agreement with the experimental findings of a previous worker. The components for the construction of an optical heterodyne-phase-locked-loop were assembled and attempts were made to lock both free running laser diodes and external cavity line-narrowed diodes. Reliable aquisition of lock was never achieved in any of the experiments performed despite the fact that beat notes of less than 50 kHz were achieved on a regular basis. The main factor which frustrated the succesful implenentation of the OPLL was deduced to have been mechanical disturbances, of the order of nanometers in magnitude, in the reflecting mirror of the external cavity sources. Hysteresis in the mechanical positioning equipment used to control the external reflector positioning was responsible for limiting the effectiveness of the frequency control loop. Experimentation was terminated by the deterioration of the laser sources, the suspected cause of which was the clustering of material defects within the active region of the device