The yeast nascent polypeptide-associated complex initiates protein targeting to mitochondria in vivo

The yeast nascent polypeptide-associated complex (NAC) is encoded by two genes, EGD1 and EGD2, and is associated with cytoplasmic ribosomes. Yeast mutants lacking NAC (Deltaegd2) are viable but suffer slight defects in the targeting of nascent polypeptides to several locations including the endoplasmic reticulum and mitochondria. If both NAC and Mft52p are missing from yeast cells, inefficient targeting of mitochondrial precursor proteins leads to defects in both mitochondrial function and morphology. We suggest that NAC provides a ribosomal environment for nascent mitochondrial targeting sequences to achieve secondary structure, thereby enhancing the efficiency of protein targeting.     

New fault diagnosis of circuit breakers

Wavelet packets and neural networks have been used to analyze the vibration data of circuit breakers (CBs) for the detection of incipient CB faults. Wavelet packets are used to convert measured vibration data from healthy and defective CBs into wavelet features. Selected features highlighting the differences between healthy and faulty condition are processed by a backpropagation neural network for classification. Testing has been done for three 66-kV CBs with simulated faults. Detection accuracy is shown to be far better than other classical techniques such as the windowed Fourier transform, stand alone artificial neural networks or expert system. The accuracy of detection for some faults can be as high as 100%.     

Acidic receptor domains on both sides of the outer membrane mediate translocation of precursor proteins into yeast mitochondria

Mitochondrial precursor proteins made in the cytosol bind to a hetero-oligomeric protein import receptor on the mitochondrial surface and then pass through the translocation channel across the outer membrane. This translocation step is accelerated by an acidic domain of the receptor subunit Mas22p, which protrudes into the intermembrane space. This 'trans' domain of Mas22p specifically binds functional mitochondrial targeting peptides with a Kd of < 1 microM and is required to anchor the N-terminal targeting sequence of a translocation-arrested precursor in the intermembrane space. If this Mas22p domain is deleted, respiration-driven growth of the cells is compromised and import of different precursors into isolated mitochondria is inhibited 3- to 8-fold. Binding of precursors to the mitochondrial surface appears to be mediated by cytosolically exposed acidic domains of the receptor subunits Mas20p and Mas22p. Translocation of a precursor across the outer membrane thus appears to involve sequential binding of the precursor's basic and amphiphilic targeting signal to acidic receptor domains on both sides of the membrane.     

Noise cross PSD estimation using phase information in diffuse noise field

Among various speech enhancement methods, two-microphone noise reduction systems are utilized for their low cost implementation and acceptable performance. Coherence-based methods are well known as efficient two-microphone noise reduction techniques. These techniques, however, do not work well when the received noise signals are correlated. Coherence-based methods can be improved when the cross power spectral density (CPSD) of input noises is available. In this paper, we propose a new method for estimating noise CPSD based on the assumption of a diffuse noise field. With this assumption, we estimate the noise CPSD using phase information. Then, the estimated noise CPSD is used to calculate a coherence-based gain filter which is then employed to enhance noisy signals. We compare the proposed phase-based noise CPSD estimation with a noise CPSD estimation technique based on a voice activity detector (VAD), both of which are herein separately employed in a two-microphone speech enhancement configuration. The comparison shows that the two-microphone speech enhancement scheme utilizing the proposed noise CPSD estimation technique outperforms the enhancement system using the VAD-based noise CPSD estimation.     

Highways for protein delivery to the mitochondria

Messenger RNA (mRNA) localisation is one of the prime mechanisms to ensure protein localisation in the cytoplasm of polarised embryonic cells, and has been well-studied in the development of Xenopus and Drosophila embryos. But what of other cells? Here, we discuss whether the directed transport of mRNA out of the nucleus, following cytoplasmic highways to a specified organelle in the cytoplasm, might also contribute to the exquisite fidelity of protein targeting observed in all eukaryotic cells.     

Graduates as Entrepreneurs*

When the private Scott-Lithgow shipbuilding business was nationalized, Sir William Lithgow set to work to develop his estate in Ormsary, Argyllshire, as well as a new industrial group. This has resulted in a vertically integrated business of which a core is the largest juvenile salmon farm in Europe. The Scottish Salmon industry now annually earns more revenue and employs more people in Scotland than both British Steel and British Coal. Industries which interact with this new activity within Lithgows include trawler-building, precision engineering, electronics and also brick manufacture.     

Reconstitution of Membrane Proteins into Model Membranes: Seeking Better Ways to Retain Protein Activities

The function of any given biological membrane is determined largely by the specific set of integral membrane proteins embedded in it, and the peripheral membrane proteins attached to the membrane surface. The activity of these proteins, in turn, can be modulated by the phospholipid composition of the membrane. The reconstitution of membrane proteins into a model membrane allows investigation of individual features and activities of a given cell membrane component. However, the activity of membrane proteins is often difficult to sustain following reconstitution, since the composition of the model phospholipid bilayer differs from that of the native cell membrane. This review will discuss the reconstitution of membrane protein activities in four different types of model membrane—monolayers, supported lipid bilayers, liposomes and nanodiscs, comparing their advantages in membrane protein reconstitution. Variation in the surrounding model environments for these four different types of membrane layer can affect the three-dimensional structure of reconstituted proteins and may possibly lead to loss of the proteins activity. We also discuss examples where the same membrane proteins have been successfully reconstituted into two or more model membrane systems with comparison of the observed activity in each system. Understanding of the behavioral changes for proteins in model membrane systems after membrane reconstitution is often a prerequisite to protein research. It is essential to find better solutions for retaining membrane protein activities for measurement and characterization in vitro.     

Laser-induced breakdown spectroscopy detection and classification of biological aerosols

Laser-induced breakdown spectroscopy (LIBS) is examined as a potential method for detecting airborne biological agents. A spectrally broadband LIBS system was used for laboratory measurements on some common biological agent simulants. These measurements were compared to those of common, naturally occurring biological aerosol components (pollen and fungal spores) to determine the potential of LIBS for discriminating biological agents from natural background aerosols. A principal components analysis illustrates that linear combinations of the detected atomic lines, which are present in different ratios in each of the samples tested, can be used to discriminate biological agent simulants from other biological matter. A more sensitive, narrowband LIBS instrument was used to demonstrate the detection of single simulant (Bg) particles in the size range 1-5 microns. Ca, Mg, and Na, which are present in varying concentrations between 0.3 and 11% (by mass) in the Bg particles, were observed in single particles using LIBS.     

Self-stimulation in 7- and 10-day-old rats.

It has been shown that the infant rat exhibits learned behaviors characteristic of the adult. With a modified self-stimulation paradigm, the present study explored whether 7- and 10-day-old Long-Evans rat pups could learn a discriminated operant to obtain direct electrical stimulation in neural sites that support self-stimulation in adults. By nudging 1 of 2 response manipulanda, at 2 ages (7 and 10 days) and temperatures (22 and 35°C), Ss self-stimulated with electrodes implanted in a variety of forebrain sites, including the prefrontal cortex, bed nucleus of the stria terminalis, medial nucleus of the amygdala, and the medial forebrain bundle. The only temperature-sensitive site might be the nucleus accumbens, which was positive only at the higher temperature in 10-day-olds. Results indicate that several forebrain sites demonstrate rewarding properties of stimulation in the preweanling rat pup. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

AN ONTOLOGY FOR COORDINATION

Independent agents that interact within open, distributed, and decentralized environments need to collaboratively regulate their activities in order to facilitate the harmonious and successful achievement of possibly conflicting tasks. Coordination is the process of managing these interactions by identifying and possibly resolving the interdependencies occurring between such activities. A successful coordination mechanism facilitates mutually beneficial interdependencies (e.g., by ensuring activities are not duplicated) while avoiding adverse outcomes (e.g., by preventing two processes simultaneously accessing the same non-shareable resource, potentially causing deadlock). However, for such a mechanism to work effectively within open systems, agents need to communicate and reason about activities, resources, and their properties; i.e., to commit to a shared ontology of coordination that defines the semantics underlying the different coordination regimes. This article describes an ontological approach to coordination in which agents dynamically manage the interdependencies that arise during their interactions. A proof-of-concept implementation in the insurance domain is described and empirically evaluated.