Structural analysis of flagellar axonemes from inner arm dynein knockdown strains of Trypanosoma brucei

Trypanosoma brucei is a protozoan flagellate that causes African sleeping sickness. Flagellar function in this organism is critical for life cycle progression and pathogenesis, however the regulation of flagellar motility is not well understood. The flagellar axoneme produces a complex beat through the precisely coordinated firing of many proteins, including multiple dynein motors. These motors are found in the inner arm and outer arm complexes. We are studying one of the inner arm dynein motors in the T. brucei flagellum: dynein-f. RNAi knockdown of genes for two components of dynein-f: DNAH10, the α heavy chain, and IC138, an intermediate chain, cause severe motility defects including immotility. To determine if motility defects result from structural disruption of the axoneme, we used two different flagellar preparations to carefully examine axoneme structure in these strains using transmission electron microscopy (TEM). Our analysis showed that inner arm dynein size, axoneme structural integrity and fixed central pair orientation are not significantly different in either knockdown culture when compared to control cultures. These results support the idea that immotility in knockdowns affecting DNAH10 or IC138 results from loss of dynein-f function rather than from obvious structural defects in the axoneme.     

Comments on ‘Design of stochastic discrete-time linear optimal regulators’

A state-space one-stage optimal control problem discussed by Lam (1982) is reexamined. Contradictions found in Lam are resolved by the certainty equivalence approach.     

EFFECT OF FISH PROTEIN PREPARATIONS ON RHEOLOGICAL PROPERTIES OF MEAT SAUSAGES

The properties of sausage emulsions, containing up to 30% fish proteins in respect to total N × 6.25, were characterized by viscosity and water holding capacity and after heating by yield, quantity of expressible fluid, water holding capacity, yield limit, creep curve, and sensory quality. Substitution of 15% meat protein by fish protein does not decrease the sausage yield nor impair the rheological properties of the formulation or of the cooked product. Sensory differences were detectable between the controls and sausages containing up to 10% of fish isolate or 20% concentrate.     

On identification of block orientated systems by non-parametric techniques

The identification of block orientated systems is discussed. Particular attention is devoted to memoryless and dynamic systems with cascade structure. An optimal model of a memoryless cascade system is derived and estimated by kernel regression. Nonlinear dynamic systems of the Hammerstein and Wiener type are identified by means of non-parametric techniques. Convergence of the identification procedures is investigated.     

Optimizing a random access system by biased source blocking

The paper considers the theoretical problems associated with control of a random access system. The dynamic flow model of a simple pure-Aloha multiple access scheme is described first, which serves as a basis for the consideration of catastrophic system behaviour in the parameter space. Then the design of the optimal control system using the Pontryagin theory is discussed. As a result of those considerations the theoretical requirements for optimizing the system operation are formulated. Finally, the control scheme of ICP-type which complies with those requirements is presented.     

Catalytic Oxidation and Reduction of Polycyclic Aromatic Hydrocarbons (PAHs) Present as Mixtures in Hydrothermal Media

The reactivity of fluorene, anthracene, and fluoranthene under oxidation and reduction conditions were investigated in this study. This project looks at catalytic and green approaches of converting PAHs to less toxic and/or less stable derivatives that are amenable to further degradation. Hydrothermal reactions have been performed at 300°C with pure H₂O and Nafion-SiO₂ catalyst for oxidation, and pure H₂O, HCOOH, Pd-C, and Nafion-SiO₂ catalysts for reductive hydrogenation. Time series has been performed for both the oxidation and hydrogenation systems. The products of the reaction were identified and quantified by the use of Gas Chromatography-Mass Spectrometry and the NIST Library. The reaction products include oxidized products of anthracene and fluorene; and hydrogenated derivatives of anthracene and fluoranthene. Fluoranthene did not undergo oxidation, and fluorene did not undergo hydrogenation under the conditions of this research.     

Optimal and asymptotically optimal linear regulators resulting from a one-stage performance index

An optimal control algorithm is derived which minimizes at each time instant the one-stage k-step-ahead performance index for the state-space representation of the CARMA model. Equivalence of the input-output representation in its asymptotic form and in the Clarke-Hastings-James algorithm is proved. Formulae for computing the output and control variances at any time instant for both optimal and asymptotic algorithms are given. The results are illustrated by a numerical example.