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In mammals, dosage compensation between XX and XY individuals occurs through X chromosome inactivation (XCI). The noncoding Xist RNA is expressed and initiates XCI only when more than one X chromosome is present. Current models invoke a dependency on the X-to-autosome ratio (X:A), but molecular factors remain poorly defined. Here, we demonstrate that(More)
In Drosophila melanogaster, the gene Sex-lethal (Sxl) controls all aspects of female development. Since melanogaster males lacking Sxl appear wild type, Sxl would seem to be functionally female specific. Nevertheless, in insects as diverse as honeybees and houseflies, Sxl seems not to determine sex or to be functionally female specific. Here we describe(More)
Once protein-coding, the X-inactivation center (Xic) is now dominated by large noncoding RNAs (ncRNA). X chromosome inactivation (XCI) equalizes gene expression between mammalian males and females by inactivating one X in female cells. XCI requires Xist, an ncRNA that coats the X and recruits Polycomb proteins. How Xist is controlled remains unclear but(More)
To understand how postmating isolation is connected to the normal process of species divergence and why hybrid male sterility is often the first sign of speciation, we analyzed the Odysseus (OdsH) gene of hybrid male sterility in Drosophila. We carried out expression analysis, transgenic study, and gene knockout. The combined evidence suggests that the(More)
The importance of gene duplication in evolution has long been recognized. Because duplicated genes are prone to diverge in function, gene duplication could plausibly play a role in species differentiation. However, experimental evidence linking gene duplication with speciation is scarce. Here, we show that a hybrid-male sterility gene, Odysseus (OdsH),(More)
Homotypic membrane fusion of the endoplasmic reticulum is mediated by dynamin-like guanosine triphosphatases (GTPases), which include atlastin (ATL) in metazoans and Sey1p in yeast. In this paper, we determined the crystal structures of the cytosolic domain of Sey1p derived from Candida albicans. The structures reveal a stalk-like, helical bundle domain(More)
In eukaryotic cells, the endoplasmic reticulum (ER) is a continuous membrane system with interconnected tubules and sheets. The formation of a typical network requires constant fusion between ER membranes. A class of membrane bound dynamin-like GTPases called atlastins (ATLs) has been identified as mediating ER fusion (Hu et al., 2009; Orso et al., 2009).(More)
X-chromosome inactivation (XCI) is the mammalian dosage compensation strategy for balancing sex chromosome content between females and males. While works exist on initiation of symmetric breaking, the underlying allelic choice mechanisms and dynamic regulation responsible for the asymmetric fate determination of XCI remain elusive. Here we combine(More)
In eukaryotic cells, the endoplasmic reticulum (ER) is a continuous membrane system involved in many critical cellular processes, including protein synthesis, lipid synthesis, and calcium storage. Morphologically, the ER is composed of cistern-like sheet structures and a reticular network of tubules. Classes of integral membrane proteins that shape the ER(More)
  • Sha Sun, Jinqiang Yang, Minghui Li
  • 2013
We propose a tractable model of entrepreneur dynamics where the investment conditions are stochastic. Applying the approach of stochastic control and optimization, we solve the dynamics of the entrepreneur's optimal investment, consumption and portfolio allocation under regime switching. We find that the interactions of precautionary savings and liquidation(More)
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