Soliton surfaces associated with CP^{N-1} sigma models

Soliton surfaces associated with CP^{N-1} sigma models are constructed using the Generalized Weierstrass and the Fokas-Gel'fand formulas for immersion of 2D surfaces in Lie algebras. The considered surfaces are defined using continuous deformations of the zero-curvature representation of the model and its associated linear spectral problem. The theoretical framework is discussed in detail and several new examples of such surfaces are presented.Comment: 14 page

Conjunctival MicroRNA expression in inflammatory trachomatous scarring.

PURPOSE: Trachoma is a fibrotic disease of the conjunctiva initiated by Chlamydia trachomatis infection. This blinding disease affects over 40 million people worldwide yet the mechanisms underlying its pathogenesis remain poorly understood. We have investigated host microRNA (miR) expression in health (N) and disease (conjunctival scarring with (TSI) and without (TS) inflammation) to determine if these epigenetic differences are associated with pathology. METHODS: We collected two independent samples of human conjunctival swab specimens from individuals living in The Gambia (n = 63 & 194). miR was extracted, and we investigated the expression of 754 miR in the first sample of 63 specimens (23 N, 17 TS, 23 TSI) using Taqman qPCR array human miRNA genecards. Network and pathway analysis was performed on this dataset. Seven miR that were significantly differentially expressed between different phenotypic groups were then selected for validation by qPCR in the second sample of 194 specimens (93 N, 74 TS, 22 TSI). RESULTS: Array screening revealed differential expression of 82 miR between N, TS and TSI phenotypes (fold change >3, p<0.05). Predicted mRNA targets of these miR were enriched in pathways involved in fibrosis and epithelial cell differentiation. Two miR were confirmed as being differentially expressed upon validation by qPCR. miR-147b is significantly up-regulated in TSI versus N (fold change = 2.3, p = 0.03) and miR-1285 is up-regulated in TSI versus TS (fold change = 4.6, p = 0.005), which was consistent with the results of the qPCR array. CONCLUSIONS: miR-147b and miR-1285 are up-regulated in inflammatory trachomatous scarring. Further investigation of the function of these miR will aid our understanding of the pathogenesis of trachoma

Dissecting comimetic radiations in Heliconius reveals divergent histories of convergent butterflies

Mimicry among Heliconius butterflies provides a classic example of coevolution but unresolved relationships among mimetic subspecies have prevented examination of codiversification between species. We present amplified fragment length polymorphism and mtDNA datasets for the major comimetic races of Heliconius erato and H. melpomene. The AFLP data reveal unprecedented resolution, clustering samples by geography and race in both species. Our results show that, although H. erato and H. melpomene co-occur, mimic each other, and exhibit parallel shifts in color pattern, they experienced very different modes of diversification and geographic histories. Our results suggest that H. erato originated on the western side of South America whereas H. melpomene originated in the east. H. erato underwent rapid diversification and expansion with continued gene-flow following diversification, resulting in widely dispersed sister taxa. In contrast, H. melpomene underwent a slower pace of diversification with lower levels of gene flow, producing a stepwise directional expansion from west to east. Our results also suggest that each of the three main wing pattern phenotypes originated and/or was lost multiple times in each species. The rayed pattern is likely to be the ancestral phenotype in H. erato whereas postman or red patch is likely to be ancestral in H. melpomene. Finally, H. cydno and H. himera are monophyletic entities clearly nested within H. melpomene and H. erato, rather than being their respective sister species. Estimates of mtDNA divergence suggest a minimum age of 2.8 and 2.1 My for H. erato and H. melpomene, respectively, placing their origins in the late Pliocene

Discovery of Novel Ligands for Mouse Olfactory Receptor MOR42-3 Using an In Silico Screening Approach and In Vitro Validation

The ligands for many olfactory receptors remain largely unknown despite successful heterologous expression of these receptors. Understanding the molecular receptive range of olfactory receptors and deciphering the olfactory recognition code are hampered by the huge number of odorants and large number of olfactory receptors, as well as the complexity of their combinatorial coding. Here, we present an in silico screening approach to find additional ligands for a mouse olfactory receptor that allows improved definition of its molecular receptive range. A virtual library of 574 odorants was screened against a mouse olfactory receptor MOR42-3. We selected the top 20 candidate ligands using two different scoring functions. These 40 odorant candidate ligands were then tested in vitro using the Xenopus oocyte heterologous expression system and two-electrode voltage clamp electrophysiology. We experimentally confirmed 22 of these ligands. The candidate ligands were screened for both agonist and antagonist activity. In summary, we validated 19 agonists and 3 antagonists. Two of the newly identified antagonists were of low potency. Several previously known ligands (mono- and dicarboxylic acids) are also confirmed in this study. However, some of the newly identified ligands were structurally dissimilar compounds with various functional groups belonging to aldehydes, phenyls, alkenes, esters and ethers. The high positive predictive value of our in silico approach is promising. We believe that this approach can be used for initial deorphanization of olfactory receptors as well as for future comprehensive studies of molecular receptive range of olfactory receptors