82,833 research outputs found
Female mating preferences in blind cave tetras Astyanax fasciatus (Characidae, Teleostei).
The Mexican tetra Astyanax fasciatus has evolved a variety of more or less color- and eyeless cave populations. Here we examined the evolution of the female preference for large male body size within different populations of this species, either surface- or cave-dwelling. Given the choice between visual cues from a large and a small male, females from the surface form as well as females from an eyed cave form showed a strong preference for large males. When only non-visual cues were presented in darkness, the surface females did not prefer either males. Among the six cave populations studied, females of the eyed cave form and females of one of the five eyeless cave populations showed a preference for large males. Apparently, not all cave populations of Astyanax have evolved non-visual mating preferences. We discuss the role of selection by benefits of non-visual mate choice for the evolution of non-visual mating preferences
Detailed Analysis of the Human Mitochondrial Contact Site Complex Indicate a Hierarchy of Subunits
Mitochondrial inner membrane folds into cristae, which significantly increase its surface and are important for mitochondrial function. The stability of cristae depends on the mitochondrial contact site (MICOS) complex. In human mitochondria, the inner membrane MICOS complex interacts with the outer membrane sorting and assembly machinery (SAM) complex, to form the mitochondrial intermembrane space bridging complex (MIB). We have created knockdown cell lines of most of the MICOS and MIB components and have used them to study the importance of the individual subunits for the cristae formation and complex stability. We show that the most important subunits of the MIB complex in human mitochondria are Mic60/Mitofilin, Mic19/CHCHD3 and an outer membrane component Sam50. We provide additional proof that ApoO indeed is a subunit of the MICOS and MIB complexes and propose the name Mic23 for this protein. According to our results, Mic25/CHCHD6, Mic27/ApoOL and Mic23/ApoO appear to be periphery subunits of the MICOS complex, because their depletion does not affect cristae morphology or stability of other components
A Splicing Mutation in the Novel Mitochondrial Protein DNAJC11 Causes Motor Neuron Pathology Associated with Cristae Disorganization, and Lymphoid Abnormalities in Mice
Mitochondrial structure and function is emerging as a major contributor to neuromuscular disease, highlighting the need for the complete elucidation of the underlying molecular and pathophysiological mechanisms. Following a forward genetics approach with N-ethyl-N-nitrosourea (ENU)-mediated random mutagenesis, we identified a novel mouse model of autosomal recessive neuromuscular disease caused by a splice-site hypomorphic mutation in a novel gene of unknown function, DnaJC11. Recent findings have demonstrated that DNAJC11 protein co-immunoprecipitates with proteins of the mitochondrial contact site (MICOS) complex involved in the formation of mitochondrial cristae and cristae junctions. Homozygous mutant mice developed locomotion defects, muscle weakness, spasticity, limb tremor, leucopenia, thymic and splenic hypoplasia, general wasting and early lethality. Neuropathological analysis showed severe vacuolation of the motor neurons in the spinal cord, originating from dilatations of the endoplasmic reticulum and notably from mitochondria that had lost their proper inner membrane organization. The causal role of the identified mutation in DnaJC11 was verified in rescue experiments by overexpressing the human ortholog. The full length 63 kDa isoform of human DNAJC11 was shown to localize in the periphery of the mitochondrial outer membrane whereas putative additional isoforms displayed differential submitochondrial localization. Moreover, we showed that DNAJC11 is assembled in a high molecular weight complex, similarly to mitofilin and that downregulation of mitofilin or SAM50 affected the levels of DNAJC11 in HeLa cells. Our findings provide the first mouse mutant for a putative MICOS protein and establish a link between DNAJC11 and neuromuscular diseases
Rapid degradation of mutant SLC25A46 by the ubiquitin-proteasome system results in MFN1/2-mediated hyperfusion of mitochondria.
SCL25A46 is a mitochondrial carrier protein that surprisingly localizes to the outer membrane and is distantly related to Ugo1. Here we show that a subset of SLC25A46 interacts with mitochondrial dynamics components and the MICOS complex. Decreased expression of SLC25A46 results in increased stability and oligomerization of MFN1 and MFN2 on mitochondria, promoting mitochondrial hyperfusion. A mutation at L341P causes rapid degradation of SLC25A46, which manifests as a rare disease, pontocerebellar hypoplasia. The E3 ubiquitin ligases MULAN and MARCH5 coordinate ubiquitylation of SLC25A46 L341P, leading to degradation by organized activities of P97 and the proteasome. Whereas outer mitochondrial membrane-associated degradation is typically associated with apoptosis or a specialized type of autophagy termed mitophagy, SLC25A46 degradation operates independently of activation of outer membrane stress pathways. Thus SLC25A46 is a new component in mitochondrial dynamics that serves as a regulator for MFN1/2 oligomerization. Moreover, SLC25A46 is selectively degraded from the outer membrane independently of mitophagy and apoptosis, providing a framework for mechanistic studies in the proteolysis of outer membrane proteins
My Land Is My Flesh Silver Bluff, the Creek Indians, and the Transformation of Colonized Space in Early America
This essay explores how Native peoples like the Creek (Muscogee) Indians invested colonized spaces in early American society with their own material, commercial, political, and spiritual meanings and importance. In particular, Creek Indians from the town of Coweta transformed Silver Bluff, the plantation of the trader and merchant George Galphin, into a “white ground,” as a place connected to Creek Country by a “white path,” and as a space where Creek and British leaders congregated to conduct business and negotiate politics. For it is no coincidence that the treaties of Augusta in 1763 and 1773, peaceful resolutions agreed to by the Creeks with the British Empire in 1760, 1764, 1773, 1774, and 1776, the negotiations over boundary lines in 1768 and 1774, and several other instances of cross-cultural dialogue all unfolded, started, or ended at Silver Bluff. The Creeks thereby enfolded occupied spaces like Silver Bluff—and the peoples who inhabited or congregated at such places—into their own worlds and according to their own understandings of those spaces. This process of spatial assimilation by the Creeks was as much collaborative as it was contested with Europeans throughout the eighteenth century
The Crustacean and Molluscan Fisheries of Honduras
Honduras has many communities of artisanal fishermen who land various species of crustaceans and mollusks, using hands, nets, traps, and free diving from shore and from dugout canoes. It also has industrial fisheries for spiny lobster, Panulirus argus; queen conch, Strombus gigas; and mainly pink shrimp, Penaeus notialis, using traps, scuba divers, and trawl nets
The Phase-Contrast Imaging Instrument at the Matter in Extreme Conditions Endstation at LCLS
We describe the Phase-Contrast Imaging instrument at the Matter in Extreme
Conditions (MEC) endstation of the Linac Coherent Light Source. The instrument
can image phenomena with a spatial resolution of a few hundreds of nanometers
and at the same time reveal the atomic structure through X-ray diffraction,
with a temporal resolution better than 100 femtosecond. It was specifically
designed for studies relevant to High-Energy-Density Science and can monitor,
e.g., shock fronts, phase transitions, or void collapses. This versatile
instrument was commissioned last year and is now available to the MEC user
community
Factores Macroecon�micos en Retornos Accionarios Chilenos
We evaluate the growth effects of real exchange rate (RER) misalignments and their volatility. We calculate RER misaligments as deviations of actual RERs from their equilibrium for 60 countries over 1965-2003 using panel and time series cointegration methods. Using dynamic panel data techniques we find that RER misalignments hinder growth but the effect is non-linear: growth declines are larger, the larger the size of the overvaluation. Although large undervaluations hurt growth, small to moderate undervaluations enhance growth. However, we find that it is difficult to follow a pro-growth RER policy. Finally, growth is hampered by highly volatile RER misalignments.
A special family of stacked central configurations: Lagrange plus Euler in one
This is a post-peer-review, pre-copyedit version of an article published in Journal of dynamics and differential equations. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10884-018-9647-1We show the existence of a family of stacked central configurations in the planar five-body problem with a special property. Three bodies m1, m2 and m3, ordered from left to right, are collinear and form an Euler central configuration, and the other two bodies m4 and m5, together with m2 are at the vertices of an equilateral triangle and form a Lagrange central configuration.Peer ReviewedPostprint (author's final draft
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