Subcellular partitioning of MRP RNA assessed by ultrastructural and biochemical analysis.

A small RNA encoded within the nucleus is an essential subunit of a RNA processing endonuclease (RNase MRP) hypothesized to generate primers for mitochondrial DNA replication from the heavy strand origin of replication. Controversy has arisen, however, concerning the authenticity of an intramitochondrial pool of MRP RNA, and has called into question the existence of pathways for nucleo-mitochondrial transport of nucleic acids in animal cells. In an effort to resolve this controversy, we combined ultrastructural in situ hybridization and biochemical techniques to assess the subcellular partitioning of MRP RNA. Cryosections of mouse cardiomyocytes were hybridized with biotin-labeled RNA probes complementary to different regions of MRP RNA and varying in length from 115 to 230 nucleotides, followed by immunogold labeling. In addition, we transfected mouse C2C12 myogenic cells with constructs bearing mutated forms of the mouse MRP RNA gene and compared the relative abundance of the resulting transcripts to that of control RNAs within whole cell and mitochondrial fractions. In the former analysis we observed preferential localization of MRP RNA to nucleoli and mitochondria in comparison to the nucleoplasm and cytoplasm. In the latter series of studies we observed that wild-type MRP RNA partitions to the mitochondrial fraction by comparison to other RNA transcripts that are localized to the extramitochondrial cytoplasmic space (28S rRNA) or to the nucleoplasm (U1 snRNA). Deletions within 5' or 3' regions of the MRP RNA gene produced transcripts that remain competent for mitochondrial targeting. In contrast, deletion of the midportion of the coding region (nt 118 to 175) of the MRP RNA gene resulted in transcripts that fail to partition to the mitochondrial fraction. We conclude that an authentic intramitochondrial pool of MRP RNA is present in these actively respiring cells, and that specific structural determinants within the MRP RNA molecule permit it to be partitioned to mitochondria

An Extended Differential Flatness Approach for the Health-Conscious Nonlinear Model Predictive Control of Lithium-Ion Batteries

This brief paper examines the problem of optimizing lithium-ion battery management online, in a health-conscious manner. This is a computationally intensive problem. Previous work by the authors addresses this challenge by exploiting the differential flatness of Fick's law of diffusion to improve computational efficiency, but is limited by the fact that the dynamics of a full battery cell are not differentially flat, even when the individual battery electrode dynamics are. The brief paper addresses this challenge by extending the application of differential flatness to a full single particle model. In particular, we use the conservation of charge to express the flat output trajectory of one electrode as an affine function of the other electrode's flat output trajectory. In this way, we enforce differential flatness for the full battery model. This makes it possible to express the battery charge/discharge trajectory in terms of one flat output trajectory. We optimize this trajectory using a pseudospectral method. This reduces the computational cost of the optimization by about a factor of 5 compared with pseudospectral optimization alone. In addition, the robustness of the nonlinear model predictive control strategy is demonstrated in simulation by adding state-of-health parameter uncertainties

Synthesis of an anion receptor for acetate based on the frame of ferrocene

An anion receptor was synthesized with ferrocene as binding frame. Anion recognition can be monitored by anion complexation-induced changes in UV-vis absorption spectra. Interaction between the receptor and acetate was described on the basis of 1H NMR experiments

Study of BNKLBT-1.5 lead-free ceramic/epoxy 1-3 composites

2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Dental attitudes of patients towards SARS in Hong Kong

published_or_final_versio

A novel coumarin-based switching-on fluorescent and colorimetric sensor for F-

A novel turn-on fluorescent and colorimetric sensor, N-(4'-nitrophenyl)-2-oxo-6-(phenylazo)2H-chromene-3-carbohydrazide (1), for fluoride in dimethyl sulfoxide (DMSO) was designed and synthesized. The binding ability evaluated by UV-vis and fluorescence titration experiments reveals that I can selectively recognize fluoride. In particular, addition of F- to the DMSO solution of I resulted in an enhancement in fluorescence intensity at 338 and 352 nm, which can provide a way of 'naked-eye' detection for fluorides. The spectral change of I is due to the anion-induced increase of the charge density in and the rigidity of the host molecule. Furthermore, the binding mode with F- was investigated by H-1 NMR experiments. (C) 2008 Elsevier B.V. All rights reserved

An Efficient Novel Acetate Anion Receptor based on Isatin

An anion recognition receptor, a kind of thiourea derivative, was designed and synthesized by combining indoline-2,3-dione and 1,3-diaminothiourea. The anion recognition can be easily monitored by anion complexation induced changes in UV-vis absorption spectra. In particular, the binding ratio between the receptor and fluoride is 1:2 but in the case of dihydrogenphosphate and acetate are 1:1. Moreover, the affinity constants revealed that the receptor can recognize acetate well. Finally, H-1 NMR experiments were carried out to explore the nature of interaction between this new receptor and acetate

A simple colorimetric sensor for biologically important anions based on intramolecular charge transfer (ICT)

A sensitive colorimetric sensor (1) based on 4,5-dinitrobenzene-1,2-diamine was designed and synthesized. Binding of anions such as AcO(-), F(-) and H(2)PO(4)(-) results in a notable change in the visible region of spectrum (an approximately 90 nm red shift), which can be detected by the 'naked-eye'. Furthermore, the binding ability was evaluated by UV-vis titration experiments as following: AcO(-) > F(-) > H(2)PO(4) >> Cl(-), Br(-), I(-). The nature of the color change of I induced by AcO(-) was due to the intramolecular charge transfer (ICT) which was confirmed by X-ray crystal structure and (1)H NMR titration spectra. (c) 2009 Elsevier B.V. All rights reserved

A high selective anion colorimetric sensor based on salicylaldehyde for fluoride in aqueous media

A new and simple salicylaldehyde-based sensor 1 designed for fluoride sensing has been investigated in DMSO and even in the 9/1 DMSO/H(2)O (v/v) Mixtures. The affinity constants of receptor 1 for anionic species in the 9/1 DMSO/H(2)O (v/v) reveal that it is sensitive to F. Also, the color changes induced by anions can provide a way of detection by 'naked-eye'. These result can be substantiated by the spectrum changes upon the addition of 25 equiv. anions to 1 in the 9/1 DMSO/H(2)O solution. The further insights to the nature of interactions between the sensor 1and F were investigated by (1)H NMR titration experiments in 9/1 DMSO-d(6)/H(2)O (v/v). In addition, the proposed binding mode between 1 and F(-) was suggested. (C) 2009 Elsevier B.V. All rights reserved

Study on the selectivity of anion receptors by adjusting the distance of two urea fragments and their analytical application

Three anion receptors based on urea: 1 N, N'-bis-(p-nitrophenylaminocarbonyl)-Hydrazine, 2 N, N'-bis-(p-nitrophenylaminocar-bonyl)-ethylenediamine and 3 N, N'-bis-(p-nitrophenylaminocarbonyl)-1, 3-propane-diamine are designed and synthesized. Studies of UV-vis spectra presented that 1 was an excellent sensor of F- and 2 was sensitive to H2PO4 (-). Unfortunately, 3 can not distinguish the anions investigated in this paper. The color changes of the hosts upon the addition of a variety of structurally different anions were also utilized as naked-eye detection which is very convenient. It also revealed significantly that the distance between two recognition sites of receptor had an immediate effect on the selectivity of receptor for anions, which had been confirmed by the H-1 NMR titration and IR