TY - JOUR
AB - Contrary to the pattern seen in mammalian sex chromosomes, where most Y-linked genes have X-linked homologs, the Drosophila X and Y chromosomes appear to be unrelated. Most of the Y-linked genes have autosomal paralogs, so autosome-to-Y transposition must be the main source of Drosophila Y-linked genes. Here we show how these genes were acquired. We found a previously unidentified gene (flagrante delicto Y, FDY) that originated from a recent duplication of the autosomal gene vig2 to the Y chromosome of Drosophila melanogaster. Four contiguous genes were duplicated along with vig2, but they became pseudogenes through the accumulation of deletions and transposable element insertions, whereas FDY remained functional, acquired testis-specific expression, and now accounts for ∼20% of the vig2-like mRNA in testis. FDY is absent in the closest relatives of D. melanogaster, and DNA sequence divergence indicates that the duplication to the Y chromosome occurred ∼2 million years ago. Thus, FDY provides a snapshot of the early stages of the establishment of a Y-linked gene and demonstrates how the Drosophila Y has been accumulating autosomal genes.
AU - Carvalho, Antonio
AU - Vicoso, Beatriz
AU - Russo, Claudia
AU - Swenor, Bonnielin
AU - Clark, Andrew
ID - 1577
IS - 40
JF - PNAS
TI - Birth of a new gene on the Y chromosome of Drosophila melanogaster
VL - 112
ER -
TY - JOUR
AB - We prove that the dual of the digital Voronoi diagram constructed by flooding the plane from the data points gives a geometrically and topologically correct dual triangulation. This provides the proof of correctness for recently developed GPU algorithms that outperform traditional CPU algorithms for constructing two-dimensional Delaunay triangulations.
AU - Cao, Thanhtung
AU - Edelsbrunner, Herbert
AU - Tan, Tiowseng
ID - 1578
IS - 7
JF - Computational Geometry
TI - Triangulations from topologically correct digital Voronoi diagrams
VL - 48
ER -
TY - JOUR
AB - We show that the Galois group of any Schubert problem involving lines in projective space contains the alternating group. This constitutes the largest family of enumerative problems whose Galois groups have been largely determined. Using a criterion of Vakil and a special position argument due to Schubert, our result follows from a particular inequality among Kostka numbers of two-rowed tableaux. In most cases, a combinatorial injection proves the inequality. For the remaining cases, we use the Weyl integral formulas to obtain an integral formula for these Kostka numbers. This rewrites the inequality as an integral, which we estimate to establish the inequality.
AU - Brooks, Christopher
AU - Martin Del Campo Sanchez, Abraham
AU - Sottile, Frank
ID - 1579
IS - 6
JF - Transactions of the American Mathematical Society
TI - Galois groups of Schubert problems of lines are at least alternating
VL - 367
ER -
TY - JOUR
AB - Synapsins (Syns) are an evolutionarily conserved family of presynaptic proteins crucial for the fine-tuning of synaptic function. A large amount of experimental evidences has shown that Syns are involved in the development of epileptic phenotypes and several mutations in Syn genes have been associated with epilepsy in humans and animal models. Syn mutations induce alterations in circuitry and neurotransmitter release, differentially affecting excitatory and inhibitory synapses, thus causing an excitation/inhibition imbalance in network excitability toward hyperexcitability that may be a determinant with regard to the development of epilepsy. Another approach to investigate epileptogenic mechanisms is to understand how silencing Syn affects the cellular behavior of single neurons and is associated with the hyperexcitable phenotypes observed in epilepsy. Here, we examined the functional effects of antisense-RNA inhibition of Syn expression on individually identified and isolated serotonergic cells of the Helix land snail. We found that Helix synapsin silencing increases cell excitability characterized by a slightly depolarized resting membrane potential, decreases the rheobase, reduces the threshold for action potential (AP) firing and increases the mean and instantaneous firing rates, with respect to control cells. The observed increase of Ca2+ and BK currents in Syn-silenced cells seems to be related to changes in the shape of the AP waveform. These currents sustain the faster spiking in Syn-deficient cells by increasing the after hyperpolarization and limiting the Na+ and Ca2+ channel inactivation during repetitive firing. This in turn speeds up the depolarization phase by reaching the AP threshold faster. Our results provide evidence that Syn silencing increases intrinsic cell excitability associated with increased Ca2+ and Ca2+-dependent BK currents in the absence of excitatory or inhibitory inputs.
AU - Brenes, Oscar
AU - Vandael, David H
AU - Carbone, Emilio
AU - Montarolo, Pier
AU - Ghirardi, Mirella
ID - 1580
JF - Neuroscience
TI - Knock-down of synapsin alters cell excitability and action potential waveform by potentiating BK and voltage gated Ca2 currents in Helix serotonergic neurons
VL - 311
ER -
TY - JOUR
AB - In animal embryos, morphogen gradients determine tissue patterning and morphogenesis. Shyer et al. provide evidence that, during vertebrate gut formation, tissue folding generates graded activity of signals required for subsequent steps of gut growth and differentiation, thereby revealing an intriguing link between tissue morphogenesis and morphogen gradient formation.
AU - Bollenbach, Mark Tobias
AU - Heisenberg, Carl-Philipp J
ID - 1581
IS - 3
JF - Cell
TI - Gradients are shaping up
VL - 161
ER -
TY - JOUR
AB - We investigate weighted straight skeletons from a geometric, graph-theoretical, and combinatorial point of view. We start with a thorough definition and shed light on some ambiguity issues in the procedural definition. We investigate the geometry, combinatorics, and topology of faces and the roof model, and we discuss in which cases a weighted straight skeleton is connected. Finally, we show that the weighted straight skeleton of even a simple polygon may be non-planar and may contain cycles, and we discuss under which restrictions on the weights and/or the input polygon the weighted straight skeleton still behaves similar to its unweighted counterpart. In particular, we obtain a non-procedural description and a linear-time construction algorithm for the straight skeleton of strictly convex polygons with arbitrary weights.
AU - Biedl, Therese
AU - Held, Martin
AU - Huber, Stefan
AU - Kaaser, Dominik
AU - Palfrader, Peter
ID - 1582
IS - 2
JF - Computational Geometry: Theory and Applications
TI - Weighted straight skeletons in the plane
VL - 48
ER -
TY - JOUR
AB - We study the characteristics of straight skeletons of monotone polygonal chains and use them to devise an algorithm for computing positively weighted straight skeletons of monotone polygons. Our algorithm runs in O(nlogn) time and O(n) space, where n denotes the number of vertices of the polygon.
AU - Biedl, Therese
AU - Held, Martin
AU - Huber, Stefan
AU - Kaaser, Dominik
AU - Palfrader, Peter
ID - 1583
IS - 2
JF - Information Processing Letters
TI - A simple algorithm for computing positively weighted straight skeletons of monotone polygons
VL - 115
ER -
TY - JOUR
AB - We investigate weighted straight skeletons from a geometric, graph-theoretical, and combinatorial point of view. We start with a thorough definition and shed light on some ambiguity issues in the procedural definition. We investigate the geometry, combinatorics, and topology of faces and the roof model, and we discuss in which cases a weighted straight skeleton is connected. Finally, we show that the weighted straight skeleton of even a simple polygon may be non-planar and may contain cycles, and we discuss under which restrictions on the weights and/or the input polygon the weighted straight skeleton still behaves similar to its unweighted counterpart. In particular, we obtain a non-procedural description and a linear-time construction algorithm for the straight skeleton of strictly convex polygons with arbitrary weights.
AU - Biedl, Therese
AU - Held, Martin
AU - Huber, Stefan
AU - Kaaser, Dominik
AU - Palfrader, Peter
ID - 1584
IS - 5
JF - Computational Geometry: Theory and Applications
TI - Reprint of: Weighted straight skeletons in the plane
VL - 48
ER -
TY - JOUR
AB - In this paper, we consider the fluctuation of mutual information statistics of a multiple input multiple output channel communication systems without assuming that the entries of the channel matrix have zero pseudovariance. To this end, we also establish a central limit theorem of the linear spectral statistics for sample covariance matrices under general moment conditions by removing the restrictions imposed on the second moment and fourth moment on the matrix entries in Bai and Silverstein (2004).
AU - Bao, Zhigang
AU - Pan, Guangming
AU - Zhou, Wang
ID - 1585
IS - 6
JF - IEEE Transactions on Information Theory
TI - Asymptotic mutual information statistics of MIMO channels and CLT of sample covariance matrices
VL - 61
ER -
TY - JOUR
AB - Through metabolic engineering cyanobacteria can be employed in biotechnology. Combining the capacity for oxygenic photosynthesis and carbon fixation with an engineered metabolic pathway allows carbon-based product formation from CO2, light, and water directly. Such cyanobacterial 'cell factories' are constructed to produce biofuels, bioplastics, and commodity chemicals. Efforts of metabolic engineers and synthetic biologists allow the modification of the intermediary metabolism at various branching points, expanding the product range. The new biosynthesis routes 'tap' the metabolism ever more efficiently, particularly through the engineering of driving forces and utilization of cofactors generated during the light reactions of photosynthesis, resulting in higher product titers. High rates of carbon rechanneling ultimately allow an almost-complete allocation of fixed carbon to product above biomass.
AU - Angermayr, Andreas
AU - Gorchs, Aleix
AU - Hellingwerf, Klaas
ID - 1586
IS - 6
JF - Trends in Biotechnology
TI - Metabolic engineering of cyanobacteria for the synthesis of commodity products
VL - 33
ER -