Old Country and Farming Words: Gleaned from Agricultural Books

Glosario. -- Various. -- Pertenece a la colección Varia 1800-1950 del Salamanca Corpus. -- James Britten, 1846-1924. -- Old Country and Farming Words: Gleaned from Agricultural Books. . -- 1880.[ES] Colección de palabras dialectales recogidas en textos sobre agricultura de los siglos 17 y 18. [EN] A collection of dialect words gleaned from 17th and 18th century agricultural books

Competitive titration in living sea urchin embryos of regulatory factors required for expression of the CyIIIa actin gene

Previous studies have located some twenty distinct sites within the 2.3 kb 5' regulatory domain of the sea urchin CyIIIa cytoskeletal actin gene, where there occur in vitro high-specificity interactions with nuclear DNA-binding proteins of the embryo. This gene is activated in late cleavage, exclusively in cells of the aboral ectoderm cell lineages. In this study, we investigate the functional importance in vivo of these sites of DNA-protein interaction. Sea urchin eggs were coinjected with a fusion gene construct in which the bacterial chloramphenicol acetyltransferase (CAT) reporter gene is under the control of the entire CyIIIa regulatory domain, together with molar excesses of one of ten nonoverlapping competitor subfragments of this domain, each of which contains one or a few specific site(s) of interaction. The exogenous excess binding sites competitively titrate the available regulatory factors away from the respective sites associated with the CyIIIa.CAT reporter gene. This provides a method for detecting in vivo sites within the regulatory domain that are required for normal levels of expression, without disturbing the structure of the regulatory domain. We thus identify five nonoverlapping regions of the regulatory DNA that apparently function as binding sites for positively acting transcriptional regulatory factors. Competition with a subfragment bearing an octamer site results in embryonic lethality. We find that three other sites display no quantitative competitive interference with CyIIIa.CAT expression, though as shown in the accompanying paper, two of these sites are required for control of spatial expression. We conclude that the complex CyIIIa regulatory domain must assess the state of many distinct and individually necessary interactions in order to properly regulate CyIIIa transcriptional activity in development

Molecular dynamics simulations of copper binding to N-terminus mutants of amyloid-β

We report results of molecular dynamic (MD) simulations on N-terminus mutants of the copper-bound, amyloid-β (Aβ) peptide. Eight structures of Aβ were modelled, including seven mutant peptides in addition to the unaltered wild-type (WT). Trajectories analysed for each individual system were all approximately 1.4 μs in length, yielding a total of over 11 μs in total. The impact of these mutations are marked and varied compared to the wild-type peptide, including effects on secondary structure, stability and conformational changes. Each system showed differing levels of stability with some showing consistent, compact conformations whereas others displayed more flexible structures. Contrasts between comparable mutations at similar sites, such as A2T/A2V and D7H/D7N, show the location as well as the type of mutation have effects on protein structure observed in Ramachandran plots. We also report notable changes in peptide structure at residues remote to the site of substitution showing these mutations influence the entirety of Aβ. Salt-bridge profiles show this most clearly: addition or removal of charged residues affecting all salt-bridge interactions present in WT, even those remote from the site of mutation. Effects on secondary structure differ between mutations, most notably a change in incidence of β-strand, which has been linked to enhanced aggregational properties for the peptide. GFN2-xTB semi-empirical calculations show clear differences in binding energies of the copper-centre for each system

A Dictionary of English Plant Names. Vol. II.

Glosario. -- Varios dialectos. -- Pertenece a la Colección Varia 1800-1950 de The Salamanca Corpus. -- James Britten (1846-1924). -- Robert Holland (1829-1893). -- A Dictionary of English Plant Names. Vol. II. -- 1886.[ES] Glosario de nombres dialectales de plantas inglesas. [EN] A Glossary of dialect names of English plants

Reconceptualising the capital adequacy requirement of short-term insurance companies within the call option framework

Conventional wisdom decrees that in order for insurers to provide cover, they require capital. One of the many methods of calculating capital requirements of short-term insurers is the insolvency put option framework. This technique was originally introduced by Merton (1977). The general argument is that bankruptcy occurs when shareholders exercise a valuable put option. Indeed, the corporation was introduced to protect shareholders from, mainly contractual, liabilities of persons who trade with the corporation. The corporation thus introduced the idea of limited liability of shareholders or as is often called the corporate veil. However, if a company defaults on its debt then equity holders have decided to allow an embedded call option to expire unexercised. As a result shareholders will behave as if they in fact hold a call option, which creates a different incentive than that suggested by the insolvency put idea. This study examines the role of capital and the influence of the insolvency put option within a short-term insurer. Specifically, it is argued that capital is not the cornerstone of a short-term insurer. Moreover, using Brownian motion and Itō calculus as well as continuous time financial models a more complete mathematical description of an insurance company is articulated by explicitly taking the embedded equity call option into account

A long, nontranslatable poly(A) RNA stored in the egg of the sea urchin Strongylocentrotus purpuratus

Nontranslatable transcripts containing interspersed repetitive sequence elements constitute a major fraction of the poly(A) RNA stored in the cytoplasm of both the sea urchin egg and the amphibian oocyte. We report the first complete sequence of a representative interspersed maternal RNA transcript, called ISp1. The transcript is about 3.7 kb in length [including poly(A) tail]; and the 5' half consists of a cluster of repetitive sequences, whereas the 3' half is single copy. Other repetitive sequences occur in the 5' and 3' regions flanking the transcription unit. In several cloned alleles, the flanking repetitive and single-copy sequences differ, indicating a high degree of insertional and deletional rearrangement around, as well as within, the transcription unit. No significant open reading frames exist in any region of the ISp1 transcript, nor is it spliced to give rise to translatable mRNA in egg or embryo. A 620-nucleotide repetitive sequence element at the 5' end of the ISp1 transcript is also represented in a large number of other long interspersed maternal poly(A) RNAs. In addition, this sequence appears in a prevalent set of small polyadenylated RNAs about 600-nucleotides in length, which disappear almost completely by the gastrula stage of development. The structural features of the ISp1 RNA uncovered in this work exclude several hypotheses of interspersed maternal poly(A) RNA origin and function

A multimerizing transcription factor of sea urchin embryos capable of looping DNA

SpGCF1 is a recently cloned sea urchin transcription factor that recognizes target sites in several different sea urchin genes. We find that in gel-shift experiments this factor is able to multimerize. A quantitative simulation of the gel-shift results suggests that SpGCF1 molecules that are bound to DNA target sites may also bind to one another, thus associating several DNA probe molecules. SpGCF1 might therefore be able to loop DNA molecules bearing its target sites at distant locations. We demonstrate this prediction by electron microscopy, and using the well-characterized cis-regulatory domain of the CyIIIa cytoskeletal actin gene, we show that the loop conformations predicted from the known SpGCF1 target site locations are actually formed in vitro. We speculate that the multimerization of this factor in vivo may function to bring distant regions of extended regulatory domains into immediate proximity so that they can interact with one another

Accelerated molecular dynamics to explore the binding of transition metals to amyloid-β

We report the accelerated molecular dynamics (aMD) simulation of amyloid-β (Aβ) peptides of four different lengths (16, 28, 40, and 42 residues) and their complexes when bound to Cu(II), Fe(II), or Zn(II). 600 ns equilibrated trajectory data were analyzed for each structure from three independent 200 ns aMD simulations, generating 16 aMD trajectories. We show that the presence of a metal ion leads to reduced size and decreased mobility relative to the free peptide due to the anchoring effect of the ions. The reduced mobility was shown largely to be due to the restricted movement in N-terminal residues, most notably Asp1 and His6 that are involved in the metal-ion coordination in all cases. Significant disruption of the secondary structure and patterns of salt bridge interactions arise on the coordination of metal ions. In this regard, similarities were noted between results for Zn(II) and Fe(II), whereas results for Cu(II) are more comparable to that of the free peptides. Reweighting of free energy surfaces was carried out from aMD data to identify the properties and descriptions of local minima structures

Forcefield evaluation and accelerated molecular dynamics simulation of Zn(II) binding to N-terminus of amyloid-β

We report conventional and accelerated molecular dynamics simulation of Zn(II) bound to the N-terminus of amyloid-β. By comparison against NMR data for the experimentally determined binding mode, we find that certain combinations of forcefield and solvent model perform acceptably in describing the size, shape and secondary structure, and that there is no appreciable difference between implicit and explicit solvent models. We therefore used the combination of ff14SB forcefield and GBSA solvent model to compare the result of different binding modes of Zn(II) to the same peptide, using accelerated MD to enhance sampling and comparing the free peptide simulated in the same way. We show that Zn(II) imparts significant rigidity to the peptide, disrupts the secondary structure and pattern of salt bridges seen in the free peptide, and induces closer contact between residues. Free energy surfaces in 1 or 2 dimensions further highlight the effect of metal coordination on peptide’s spatial extent. We also provide evidence that accelerated MD provides improved sampling over conventional MD by visiting as many or more configurations in much shorter simulation times