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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2007.11.011 Byline: Martin Connors (a), R. Greg Stacey (a)(b), Paul Wiegert (c), Ramon Brasser (d) Keywords: Celestial mechanics; Resonances; orbital; Pluto; Asteroids; dynamics Abstract: By studying orbits of asteroids potentially in 3:2 exterior mean motion resonance with Earth, Venus, and Mars, we have found plutino analogs. We identify at least 27 objects in the inner Solar System dynamically protected from encounter through this resonance. These are four objects associated with Venus, six with Earth, and seventeen with Mars. Bodies in the 3:2 exterior resonance (including those in the plutino resonance associated with Neptune) orbit the Sun twice for every three orbits of the associated planet, in such a way that with sufficiently low libration amplitude close approaches to the planet are impossible. As many as 15% of Kuiper Belt objects share the 3:2 resonance, but are poorly observed. One of several resonance sweeping mechanisms during planetary migration is likely needed to explain the origin and properties of 3:2 resonant Kuiper Belt objects. Such a mechanism likely did not operate in the inner Solar System. We suggest that scattering by the next planet out allows entry to, and exit from, 3:2 resonance for objects associated with Venus or Earth. 3:2 resonators of Mars, on the other hand, do not cross the paths of other planets, and have a long lifetime. There may exist some objects trapped in the 3:2 Mars resonance which are primordial, with our tests on the most promising objects known to date indicating lifetimes of at least tens of millions of years. Identifying 3:2 resonant systems in the inner Solar System permits this resonance to be studied on shorter timescales and with better determined orbits than has been possible to date, and introduces new mechanisms for entry into the resonant configuration. Author Affiliation: (a) Centre for Science, Athabasca University, 1 University Drive, Athabasca AB, T9S 3A3, Canada (b) Department of Physics, University of Alberta, c/o 1 University Drive, Athabasca AB, T9S 3A3, Canada (c) Department of Physics and Astronomy, University of Western Ontario, London ON, N6A 3K7, Canada (d) Department of Physics, Queen's University, Kingston ON, K7L 3N6, Canada Article History: Received 31 August 2006; Revised 4 November 2007

Extracellular vesicles (EVs) are secreted by myriad cells in culture and also by unicellular organisms, and their identification in mammalian fluids suggests that EV release also occurs at the organism level. However, although it is clearly important to better understand EVs' roles in organismal biology, EVs in solid tissues have received little attention. Here, we modified a protocol for EV isolation from primary neural cell culture to collect EVs from frozen whole murine and human neural tissues by serial centrifugation and purification on a sucrose gradient. Quantitative proteomics comparing brain-derived EVs from nontransgenic (NTg) and a transgenic amyotrophic lateral sclerosis (ALS) mouse model, superoxide dismutase 1 (SOD1)G93A, revealed that these EVs contain canonical exosomal markers and are enriched in synaptic and RNA-binding proteins. The compiled brain EV proteome contained numerous proteins implicated in ALS, and EVs from SOD1G93A mice were significantly depleted in myelin-oligodendrocyte glycoprotein compared with those from NTg animals. We observed that brain- and spinal cord-derived EVs, from NTg and SOD1G93A mice, are positive for the astrocyte marker GLAST and the synaptic marker SNAP25, whereas CD11b, a microglial marker, was largely absent. EVs from brains and spinal cords of the SOD1G93A ALS mouse model, as well as from human SOD1 familial ALS patient spinal cord, contained abundant misfolded and nonnative disulfide-cross-linked aggregated SOD1. Our results indicate that CNS-derived EVs from an ALS animal model contain pathogenic disease-causing proteins and suggest that brain astrocytes and neurons, but not microglia, are the main EV source. [ABSTRACT FROM AUTHOR]

Proteins generally achieve their functions through interactions with other proteins, so being able to determine which proteins interact with which other proteins underlies much of molecular biology. Co-fractionation (CF) is a mass spectrometry-based method for detecting proteome-wide protein-protein interactions. An attractive feature of CF is that it is not necessary to label or otherwise alter samples. Although we have previously published a widely used protocol for a label-incorporated CF methodology, no published protocols currently exist for the label-free variation. In this chapter, we describe a label-free CF-MS protocol. This protocol takes a minimum of a week, excluding the time for cell/tissue culture. It begins with cell/tissue lysis under non-denaturing conditions, after which intact protein complexes are isolated using size exclusion chromatography (SEC) where they are fractionated according to size. The proteins in each fraction are then prepared for mass spectrometry analysis where the constituent proteins are identified and quantified. Finally, we describe an in-house bioinformatics pipeline, PrInCE, to accurately predict protein complexes. Taken together, co-fractionation methodologies combined with mass spectrometry can identify and quantify thousands of protein-protein interactions in biological systems., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Extracellular vesicles (EVs) are secreted by myriad cells in culture and also by unicellular organisms, and their identification in mammalian fluids suggests that EV release also occurs at the organism level. However, although it is clearly important to better understand EVs' roles in organismal biology, EVs in solid tissues have received little attention. Here, we modified a protocol for EV isolation from primary neural cell culture to collect EVs from frozen whole murine and human neural tissues by serial centrifugation and purification on a sucrose gradient. Quantitative proteomics comparing brain-derived EVs from nontransgenic (NTg) and a transgenic amyotrophic lateral sclerosis (ALS) mouse model, superoxide dismutase 1 (SOD1) G93A , revealed that these EVs contain canonical exosomal markers and are enriched in synaptic and RNA-binding proteins. The compiled brain EV proteome contained numerous proteins implicated in ALS, and EVs from SOD1 G93A mice were significantly depleted in myelin-oligodendrocyte glycoprotein compared with those from NTg animals. We observed that brain- and spinal cord-derived EVs, from NTg and SOD1 G93A mice, are positive for the astrocyte marker GLAST and the synaptic marker SNAP25, whereas CD11b, a microglial marker, was largely absent. EVs from brains and spinal cords of the SOD1 G93A ALS mouse model, as well as from human SOD1 familial ALS patient spinal cord, contained abundant misfolded and nonnative disulfide-cross-linked aggregated SOD1. Our results indicate that CNS-derived EVs from an ALS animal model contain pathogenic disease-causing proteins and suggest that brain astrocytes and neurons, but not microglia, are the main EV source., (© 2019 Silverman et al.)

Brain is an electrochemical system and recent studies suggest simultaneous measurement of interrelated brain's electrical and neurochemical activity may lead to better understanding of brain function in addition to developing optimal neural prosthetics. By exploiting opamp Time-sharing technique to minimized power dissipation and silicon area, we have fabricated a power efficient implantable CMOS microsystem for simultaneous measurement of Action Potential (AP) and neurotransmitter concentration. Both AP-recording and neurotransmitter sensing subsystems share a single 653 nW amplifier which senses picoscale to microscale current that corresponds to micromolar neurotransmitter concentration and microscale AP voltage. This microsystem is fabricated in CMOS 0.18 μm technology and tested using recorded signals from dorsal premotor cortex (PMd) area of a macaque monkey in our lab.