Biological Results Of The University-Of-Miami Deep-Sea Expeditions .136. A New Eelpout (Teleostei, Zoarcidae) From The Eastern Tropical Pacific-Ocean

A new ee]pout, Lycenchelys rnonstrosa, is described from the lower continental slope of the Gulf of Panama, eastern Pacific Ocean. It is distinguished from all other Lycenchelys in the region by possessing nine preopercu]omandibular pores, eight or nine suborbital pores, one postorbital pore, no occipital or interorbital pores, 126-132 vertebrae and far posterior dorsal fin origin, with three to seven free dorsal pterygiophores. The species appears to be somewhat peculiar among eel pouts in that 11 of the 12 known specimens lack pelvic fins; one of the fish without pelvic fins is the only one known with palatine teeth. Both characters have been used at the generic level in eelpouts . The species appears closest to three other congeners with nine preopercu]omandibular pores, known from the North Pacific and Antarctic lower slopes. Characters of the new species lend support to earlier conclusions that the deeper living Lycenchelys have undergone morphological modification in a similar manner, though they do not necessarily form a monophyletic group

Distribution Of Demersal Fishes Of The Caribbean Sea Found Below 2,000 Meters

Abyssal fishes of the Caribbean Sea are known from the work of six research vessels, yet only one ofthese collections has been reported. The most recent collection, that of the USNS BARTLETTin 1981, contains 13 new records of rare fish to the Caribbean, including two undescribed species. Twelve species accounts are given, documenting the new finds, along with some taxonomic changes from previous reports. Zoogeographical analysis revealed that the abyssal fish fauna of the Caribbean basins reflects a depauperate, tropical, western Atlantic subunit of a broader, circumglobal pattern of the world\u27s abyssal fish fauna

A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase

Background: Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle. Methods: Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change. Results: PSSM1-affected horse muscle had significantly higher glycogen content than control horse muscle despite no difference in GS expression. GS activity was significantly higher in muscle from homozygous mutants than from heterozygote and control horses, in the absence and presence of the allosteric regulator, glucose 6 phosphate (G6P). Muscle from homozygous mutant horses also had significantly increased GS phosphorylation at sites 2 + 2a and significantly higher AMPKα1 (an upstream kinase) expression than controls, likely reflecting a physiological attempt to reduce GS enzyme activity. Recombinant mutant GS was highly active with a considerably lower Km for UDP-glucose, in the presence and absence of G6P, when compared to wild type GS, and despite its phosphorylation. Conclusions: Elevated activity of the mutant enzyme is associated with ineffective regulation via phosphorylation rendering it constitutively active. Modelling suggested that the mutation disrupts a salt bridge that normally stabilises the basal state, shifting the equilibrium to the enzyme's active state. General significance: This study explains the gain of function pathogenesis in this highly prevalent polyglucosan myopathy

Skyrmion Multi-Walls

Skyrmion walls are topologically-nontrivial solutions of the Skyrme system which are periodic in two spatial directions. We report numerical investigations which show that solutions representing parallel multi-walls exist. The most stable configuration is that of the square $N$-wall, which in the $N\to\infty$ limit becomes the cubically-symmetric Skyrme crystal. There is also a solution resembling parallel hexagonal walls, but this is less stable.Comment: 7 pages, 1 figur

Quantum dimer models and exotic orders

We discuss how quantum dimer models may be used to provide "proofs of principle" for the existence of exotic magnetic phases in quantum spin systems.Comment: 12 pages, 6 figures. Contributed talk at the PITP-Les Houches Summer School on "Quantum Magnetism", June 200

Measuring vortex charge with a triangular aperture

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)A triangular aperture illuminated with a vortex beam creates a truncated lattice diffraction pattern that identifies the charge of the vortex. In this Letter, we demonstrate the measurement of vortex charge via this approach for vortex beams up to charge +/- 7. We also demonstrate the use of this technique for measuring femtosecond vortices and noninteger vortices, comparing these results with numerical modeling. It is shown that this technique is simple and reliable, but care must be taken when interpreting the results for the noninteger case. (C) 2011 Optical Society of America366787789Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundo de Apoio ao Ensino, Pesquisa e Extensao-UNICAMP (FAEPEX)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

DNA end resection by Dna2–Sgs1–RPA and its stimulation by Top3–Rmi1 and Mre11–Rad50–Xrs2

The repair of DNA double-strand breaks (DSBs) by homologous recombination requires processing of broken ends. For repair to start, the DSB must first be resected to generate a 3′-single-stranded DNA (ssDNA) overhang, which becomes a substrate for the DNA strand exchange protein, Rad51 (ref. 1). Genetic studies have implicated a multitude of proteins in the process, including helicases, nucleases and topoisomerases. Here we biochemically reconstitute elements of the resection process and reveal that it requires the nuclease Dna2, the RecQ-family helicase Sgs1 and the ssDNA-binding protein replication protein-A (RPA). We establish that Dna2, Sgs1 and RPA constitute a minimal protein complex capable of DNA resection in vitro. Sgs1 helicase unwinds the DNA to produce an intermediate that is digested by Dna2, and RPA stimulates DNA unwinding by Sgs1 in a species-specific manner. Interestingly, RPA is also required both to direct Dna2 nucleolytic activity to the 5′-terminated strand of the DNA break and to inhibit 3′ to 5′ degradation by Dna2, actions that generate and protect the 3′-ssDNA overhang, respectively. In addition to this core machinery, we establish that both the topoisomerase 3 (Top3) and Rmi1 complex and the Mre11–Rad50–Xrs2 complex (MRX) have important roles as stimulatory components. Stimulation of end resection by the Top3–Rmi1 heterodimer and the MRX proteins is by complex formation with Sgs1 (refs 5, 6), which unexpectedly stimulates DNA unwinding. We suggest that Top3–Rmi1 and MRX are important for recruitment of the Sgs1–Dna2 complex to DSBs. Our experiments provide a mechanistic framework for understanding the initial steps of recombinational DNA repair in eukaryotes

Proof Theory and Ordered Groups

Ordering theorems, characterizing when partial orders of a group extend to total orders, are used to generate hypersequent calculi for varieties of lattice-ordered groups (l-groups). These calculi are then used to provide new proofs of theorems arising in the theory of ordered groups. More precisely: an analytic calculus for abelian l-groups is generated using an ordering theorem for abelian groups; a calculus is generated for l-groups and new decidability proofs are obtained for the equational theory of this variety and extending finite subsets of free groups to right orders; and a calculus for representable l-groups is generated and a new proof is obtained that free groups are orderable