bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parasitic suppression of feeding in the tobacco hornworm,Manduca sexta: Parallels with feeding depression after an immune challenge
Authors: Adamo Shelley A. 
Published: November 2005

AbstractThe parasitic wasp,Cotesia congregata, suppresses feeding in its hostManduca sexta. Feeding suppression in the host coincides with the emergence of the wasps through the host's cuticle. During wasp emergence, host hemocyte number declined, suggesting that the host mounts a wound/immune response against the exiting parasitoids and/or resulting tissue damage. Eliciting a different type of immune response by injecting heat‐killedSerratia marcescensalso resulted in a decline in feeding and a reduction in hemocyte number. Both the emerging wasps and the bacteria induced an increase in hemolymph octopamine concentration and a decrease in foregut peristalsis inM. sexta. The emerging parasitoids produced the largest changes. The source of the additional octopamine appeared to be the host in both cases.S. marcescenswas found to contain no detectable amounts of octopamine. The parasitoids had insufficient octopamine to account for the amount found in host hemolymph and they did not secrete octopamine in vitro. One cause for the high concentration of octopamine in parasitizedM. sextawas that octopamine was removed from the hemolymph approximately 23 times more slowly after the wasps emerged than prior to wasp emergence. The striking similarity between the effects of parasitoids and bacteria onM. sextafeeding, hemocyte number, hemolymph octopamine concentration, and foregut peristalsis supports the possibility that the immune/wound reaction induced by the emerging wasps could play a role in the suppression of host feeding. These results also support the hypothesis thatM. sextaexhibit an immune‐activated anorexia. Arch. Insect Biochem. Physiol. 60:185–197, 2005. © 2005 Wiley‐Liss, Inc.
Long‐range coordination of planar polarity in Drosophila
Authors: Strutt Helen , Strutt David 
Published: November 2005

AbstractThe mechanisms by which cells become polarised in the plane of an epithelium have been studied in Drosophila for many years. Work has focussed on two key questions: firstly, how individual cells adopt a defined polarity, and secondly how the polarity of each cell within a tissue is aligned with its neighbours. It has been established that asymmetric subcellular localisation of a number of polarity proteins is an essential mechanism underlying polarisation of single cells. The process by which this polarity is coordinated between cells however is less well understood, but is thought to involve gradients of activity of the atypical cadherins Dachsous and Fat. Subsequently, this long‐range polarity signal is refined by local cell–cell interactions involving the transmembrane molecules Frizzled, Strabismus and Flamingo. The role of these factors in coordinating polarity will be discussed. BioEssays 27:1218–1227, 2005. © 2005 Wiley Periodicals, Inc.
My favorite animal, Trichoplax adhaerens
Authors: Schierwater Bernd 
Published: November 2005

AbstractTrichoplax adhaerens is more simply organized than any other living metazoan. This tiny marine animal looks like a irregular “hairy plate” (“tricho plax”) with a simple upper and lower epithelium and some loose cells in between. After its original description by F.E. Schulze 1883, it attracted particular attention as a potential candidate representing the basic and ancestral state of metazoan organization. The lack of any kind of symmetry, organs, nerve cells, muscle cells, basal lamina and extracellular matrix originally left little doubt about the basal position of T. adhaerens. Nevertheless, the interest of zoologists and evolutionary biologists suddenly vanished for more than half a century when Trichoplax was claimed to be an aberrant hydrozoan planula larva. Recently, Trichoplax has been rediscovered as a key species for unraveling early metazoan evolution. For example, research on regulatory genes and whole genome sequencing promise insights into the genetics underlying the origin and development of basal metazoan phyla. Trichoplax offers unique potential for understanding the minimal requirements of metazoan animal organization. BioEssays 27:1294–1302, 2005. © 2005 Wiley Periodicals, Inc.
The Y chromosome as a target for acquired and amplified genetic material in evolution
Authors: Gvozdev Vladimir A. , Kogan Galina L. , Usakin Lev A. 
Published: November 2005

AbstractThe special properties of the Y chromosome stem form the fact that it is a non‐recombining degenerate derivative of the X chromosome. The absence of homologous recombination between the X and the Y chromosome leads to gradual degeneration of various Y chromosome genes on an evolutionary timescale. The absence of recombination, however, also favors the accumulation of transposable elements on the Y chromosome during its evolution, as seen with both Drosophila and mammalian Y chromosomes. Alongside these processes, the acquisition and amplification of autosomal male benefit genes occur. This review will focus on recent studies that reveal the autosome‐acquired genes on the Y chromosome of both Drosophila and humans. The evolution of the acquired and amplified genes on the Y chromosome is also discussed. Molecular and comparative analyses of Y‐linked repeats in the Drosophila melanogaster genome demonstrate that there was a period of their degeneration followed by a period of their integration into RNAi silencing, which was beneficial for male fertility. Finally, the function of non‐coding RNA produced by amplified Y chromosome genetic elements will be discussed. BioEssays 27:1256–1262, 2005. © 2005 Wiley Periodicals, Inc.
Different species problems and their resolution
Authors: de Queiroz Kevin 
Published: November 2005

AbstractAt least three different issues are commonly referred to by the term “the species problem”: one concerns the necessary properties of species, a second the processes responsible for the existence of species, and a third methods for inferring species limits. Solutions have recently been proposed to the first two problems, which are conceptual in nature (the third is methodological). The first equates species with metapopulation lineages and proposes that existence as a separately evolving metapopulation lineage be considered the only necessary property of species. The second views the species category as a cluster concept and proposes that no single process or set of processes be considered necessary for the existence of species. Although these two solutions have been portrayed as being in conflict, they are, in fact, highly compatible. Moreover, the proposals in question clarify the problem concerning methods for inferring the limits of species, which has for a long time been confused with the problem concerning the necessary properties of species. Together these proposals provide the opportunity for biology to move beyond debates about the definition of the species category and focus on estimating the boundaries and numbers of species as well as studying the diverse processes involved in their origin and persistence. BioEssays 27:1263–1269, 2005. © 2005 Wiley Periodicals, Inc.
Stochastic gene expression, disruption of tissue averaging effects and cancer as a disease of development
Authors: Capp Jean‐Pascal 
Published: November 2005

AbstractDespite the extensive literature describing the somatic genetic alterations in cancer cells, the precise origins of cancer cells remain controversial. In this article, I suggest that the etiology of cancer and the generation of genetic instability in cancer cells should be considered in the light of recent findings on both the stochastic nature of gene expression and its regulation at tissue level. By postulating that gene expression is intrinsically probabilistic and that stabilization of gene expression arises by cellular interactions in “morphogenetic fields”, development and cellular differentiation can be rethought in an evolutionary perspective. In particular, this article proposes that disruptions of cellular interactions are the initial source of abnormal gene expression in cancer cells. Consequently, cancer phenotypes such as genetic and epigenetic instabilities, and also the presence of cells with stem cell‐like properties, may result from inaccurate and aberrant patterns of gene expression generated by microenvironmental alterations. Finally, the therapeutic implications of this view are discussed. BioEssays 27:1277–1285, 2005. © 2005 Wiley Periodicals, Inc.
TIRs of joy: new receptors for auxin
Authors: Napier Richard M. 
Published: November 2005

AbstractBack‐to‐back papers have described the identification of a family of receptors for the plant hormone auxin.(1, 2) Most developmental processes in plants are dependent on auxin signalling making this discovery a landmark in the search for the mechanism of auxin action. The TIR1 gene translates into a protein with recognised motifs including an F‐box domain and TIR1 forms part of an important ubiquitination complex that tags other proteins for degradation.(3) Specific amongst the targets of TIR1 are a set of auxin‐regulated transcription factors.(4) The latest work has shown that TIR1 itself is also the binding site for auxin making it an auxin receptor with no requirement for a biochemical signalling cascade. BioEssays 27:1213–1217, 2005. © 2005 Wiley Periodicals, Inc.
Stabilization of Taq DNA Polymerase at High Temperature by Protein Folding Pathways From a Hyperthermophilic Archaeon, Pyrococcus furiosus
Authors: Laksanalamai Pongpan , Pavlov Andrey R. , Slesarev Alexei I. , Robb Frank T. 
Published: November 2005

AbstractPyrococcus furiosus, a hyperthermophilic archaeon growing optimally at 100°C, encodes three protein chaperones, a small heat shock protein (sHsp), a prefoldin (Pfd), and a chaperonin (Cpn). In this study, we report that the passive chaperones sHsp and Pfd from P. furiosus can boost the protein refolding activity of the ATP‐dependent Cpn from the same hyperthermophile. The thermo‐stability of Taq polymerase was significantly improved by combinations of P. furiosus chaperones, showing ongoing protein folding activity at elevated temperatures and during thermal cycling. Based on these results, we propose that the protein folding apparatus in the hyperthermophilic archaeon, P. furiosus can be utilized to enhance the durability and cost effectiveness of high temperature biocatalysts. © 2005 Wiley Periodicals, Inc.
Facile Synthesis and Optimization of Conductive Copolymer Nanoparticles and Nanocomposite Films from Aniline with Sulfodiphenylamine
Authors: Li Xin‐Gui , Lü Qiu‐Feng , Huang Mei‐Rong 
Published: November 2005

AbstractA new series of electrically conductive pure copolymer nanoparticles was facilely synthesized by using oxidative polymerization of aniline (AN) and sodium diphenylamine‐4‐sulfonate (SDP) in acidic media in the absence of stabilizer. The variation of the structure of the copolymer particles was comprehensively studied by carefully choosing several important parameters, such as the comonomer ratio, oxidant/monomer ratio, polymerization time and temperature, monomer concentration, acidic medium, and oxidant species. Analytical techniques used include IR and UV‐visible spectroscopy, X‐ray diffraction, laser particle analysis, atomic force microscopy, and transmission electron microscopy. It was found that the particle size varied significantly with the above‐mentioned polymerization parameters, only changes in the salt concentration in the aqueous testing solution had no noticeable effect. The polymerization conditions were optimized for the formation of copolymer nanoparticles with sought‐after properties. The doped copolymer particles of AN/SDP (50:50) at an oxidant/monomer molar ratio of 0.5 exhibit a minimum length of 50 nm and a minimum diameter of 44 nm. The bulk electrical conductivity of the copolymer particles increases greatly from 5.90×10−4 to 1.15×10−2 S cm−1 with increasing AN content. Compared with barely soluble polyaniline, the copolymers exhibit a remarkably enhanced solubility in most solvents, including NH4OH and even water, due to the presence of the hydrophilic sulfonic groups. Nanocomposite films of the nanoparticles and cellulose diacetate exhibit a percolation threshold of down to 0.1 wt %, at which the film retains 98 % of the transparency, 94 % of the strength, and 5×107 times the conductivity of a pure cellulose diacetate film.
New Insights into the Mechanism of Proton Transfer to Hydride Complexes: Kinetic and Theoretical Evidence Showing the Existence of Competitive Pathways for Protonation of the Cluster [W3S4H3(dmpe)3]+ with Acids
Authors: Algarra Andrés G. , Basallote Manuel G. , Feliz Marta , Fernández‐Trujillo M. Jesús , Llusar Rosa , Safont Vicent S. 
Published: November 2005

AbstractThe reaction of the hydride cluster [W3S4H3(dmpe)3]+ (1, dmpe=1,2‐bis(dimethylphosphanyl)ethane) with acids (HCl, CF3COOH, HBF4) in CH2Cl2 solution under pseudo‐first‐order conditions of excess acid occurs with three kinetically distinguishable steps that can be interpreted as corresponding to successive formal substitution processes of the coordinated hydrides by the anion of the acid (HCl, CF3COOH) or the solvent (HBF4). Whereas the rate law for the third step changes with the nature of the acid, the first two kinetic steps always show a second‐order dependence on acid concentration. In contrast, a single kinetic step with a first‐order dependence with respect to the acid is observed when the experiments are carried out with a deficit of acid. The decrease in the T1 values for the hydride NMR signal of 1 in the presence of added HCl suggests the formation of an adduct with a WH⋅⋅⋅HCl dihydrogen bond. Theoretical calculations for the reaction with HCl indicate that the kinetic results in CH2Cl2 solution can be interpreted on the basis of a mechanism with two competitive pathways. One of the pathways consists of direct proton transfer within the WH⋅⋅⋅HCl adduct to form WCl and H2, whereas the other requires the presence of a second HCl molecule to form a WH⋅⋅⋅HCl⋅⋅⋅HCl adduct that transforms into WCl, H2 and HCl in the rate‐determining step. The activation barriers and the structures of the transition states for both pathways were also calculated, and the results indicate that both pathways can be competitive and that the transition states can be described in both cases as a dihydrogen complex hydrogen‐bonded to Cl− or HCl2−.
Binding of Cationic and Neutral Phenanthridine Intercalators to a DNA Oligomer Is Controlled by Dispersion Energy: Quantum Chemical Calculations and Molecular Mechanics Simulations
Authors: Kubař Tomáš , Hanus Michal , Ryjáček Filip , Hobza Pavel 
Published: November 2005

AbstractCorrelated ab initio as well as semiempirical quantum chemical calculations and molecular dynamics simulations were used to study the intercalation of cationic ethidium, cationic 5‐ethyl‐6‐phenylphenanthridinium and uncharged 3,8‐diamino‐6‐phenylphenanthridine to DNA. The stabilization energy of the cationic intercalators is considerably larger than that of the uncharged one. The dominant energy contribution with all intercalators is represented by dispersion energy. In the case of the cationic intercalators, the electrostatic and charge‐transfer terms are also important. The ΔG of ethidium intercalation to DNA was estimated at −4.5 kcal mol−1 and this value agrees well with the experimental result. Of six contributions to the final free energy, the interaction energy value is crucial. The intercalation process is governed by the non‐covalent stacking (including charge‐transfer) interaction while the hydrogen bonding between the ethidium amino groups and the DNA backbone is less important. This is confirmed by the evaluation of the interaction energy as well as by the calculation of the free energy change. The intercalation affects the macroscopic properties of DNA in terms of its flexibility. This explains the easier entry of another intercalator molecule in the vicinity of an existing intercalation site.
Density Functional Studies of Dicobalt Octacarbonyl‐Mediated Azobenzene Formation from 4‐Ethynylaniline
Authors: Huang Yi‐Luen , Hong Fung‐E 
Published: November 2005

AbstractTwo adiabatic potential‐energy surfaces are employed for probing the processes of [Co2(CO)8]‐mediated C6H5NNC6H5 formation from NH2C6H5. Elementary steps, including oxidative addition of the coordinated amine proton to the cobalt center, reductive elimination of H2, CO association, and the coupling process of the diamino fragments, are modeled and examined by using DFT methods at the B3 LYP/631 LAN level. The formation of C6H5NNC6H5 from NH2C6H5 through reductive coupling is a thermodynamically unfavorable process. Three hydride‐migration processes, from the proton of NH to the cobalt center, are established as the most energy‐demanding steps. The activation energies (ΔG*) are calculated as 49.4, 55.4, and 33.3 kcal mol−1, respectively, for the proposed reaction route 1. These large activation energies might be reduced slightly by purposely adding small protic molecules, such as H2O, or by changing the active metal from Co to a heavier metal, such as Rh or Ir. An alternative pathway, route 2, is also proposed, in which transition states with four‐membered rings are formed. By this route, severe strain caused by the formation of three‐membered rings during the hydride‐migration processes in route 1 can be avoided. Route 2 is established as the more energy‐feasible reaction pathway.
Solid‐Phase Synthesis and Biological Activity of a Combinatorial Cross‐Conjugated Dienone Library
Authors: Kitade Makoto , Tanaka Hiroshi , Oe Sho , Iwashima Makoto , Iguchi Kazuo , Takahashi Takashi 
Published: November 2005

AbstractThe solid‐phase synthesis of a combinatorial cross‐conjugated dienone library based on the structure of clavulones and their biological activity are reported. Clavulones are a family of marine prostanoids, and are composed of a cross‐conjugated dienone system bearing two alkyl side‐chains. The cross‐conjugated dienone system irreversibly reacted with two nucleophiles. Our strategy for the solid‐phase synthesis of the cross‐conjugated dienones involves the Sonogashira‐coupling reaction of a solid‐supported cyclopentenone 10 bearing an acetylene group, followed by aldol condensation with aldehydes. The diphenyl derivative 7 aA was prepared from the solid‐supported cyclopentenone 10 in 56 % total yield. Combinatorial synthesis of a small library using twelve halides and eight aldehydes resulted in the production of 74 desired compounds from 98 candidates, and were detected by their mass spectra. Antiproliferative effects of the crude compounds against HeLaS3 cells showed that eleven samples showed strong antitumor activity (IC50<0.05 μM). Further biological examination of four purified compounds by using five tumor cell lines (A549, HeLaS3, MCF7, TMF1, and P388) revealed strong cytotoxicity comparable to that of adriamycin.
Unprecedented Stereoselective Synthesis of Catalytically Active Chiral Mo3CuS4 Clusters
Authors: Feliz Marta , Guillamón Eva , Llusar Rosa , Vicent Cristian , Stiriba Salah‐Eddine , Pérez‐Prieto Julia , Barberis Mario 
Published: November 2005

AbstractCluster excision of polymeric {Mo3S7Cl4}n phases with chiral phosphane (+)‐1,2‐bis[(2R,5R)‐2,5‐(dimethylphospholan‐1‐yl)]ethane ((R,R)‐Me‐BPE) or with its enantiomer ((S,S)‐Me‐BPE) yields the stereoselective formation of the trinuclear cluster complexes [Mo3S4{(R,R)‐Me‐BPE}3Cl3]+ ([(P)‐1]+) and [Mo3S4{(S,S)‐Me‐BPE}3Cl3]+ ([(M)‐1]+), respectively. These complexes posses an incomplete cuboidal structure with the metal atoms defining an equilateral triangle and one capping and three bridging sulfur atoms. The P and M symbols refer to the rotation of the chlorine atoms around the C3 axis, with the capping sulphur atom pointing towards the viewer. Incorporation of copper into these trinuclear complexes affords heterodimetallic cubane‐type compounds of formula [Mo3CuS4{(R,R)‐Me‐BPE}3Cl4]+ ([(P)‐2]+) or [Mo3CuS4{(S,S)‐Me‐BPE}3Cl4]+ ([(M)‐2]+), respectively, for which the chirality of the trinuclear precursor is preserved in the final product. Cationic complexes [(P)‐1]+, [(M)‐1]+, [(P)‐2]+, and [(M)‐2]+ combine the chirality of the metal cluster framework with that of the optically active diphosphane ligands. The known racemic [Mo3CuS4(dmpe)3Cl4]+ cluster (dmpe=1,2‐bis(dimethylphosphanyl)ethane) as well as the new enantiomerically pure Mo3CuS4 [(P)‐2]+ and [(M)‐2]+ complexes are efficient catalysts for the intramolecular cyclopropanation of 1‐diazo‐5‐hexen‐2‐one (3) and for the intermolecular cyclopropanation of alkenes, such as styrene and 2‐phenylpropene, with ethyl diazoacetate. In all cases, the cyclopropanation products were obtained in high yields. The diastereoselectivity in the intermolecular cyclopropanation of the alkenes and the enantioselectivity in the inter‐ or intramolecular processes are only moderate.
A Photocontrolled β‐Hairpin Peptide
Authors: Dong Shou‐Liang , Löweneck Markus , Schrader Tobias E. , Schreier Wolfgang J. , Zinth Wolfgang , Moroder Luis , Renner Christian 
Published: November 2005

Abstractβ‐Hairpins constitute the smallest β‐type structures in peptides and proteins. The development of highly stable, yet monomeric β‐hairpins based on the tryptophan zipper motif was therefore a remarkable success [A. G. Cochran, N. J. Skelton, M. A. Starovasnik, Proc. Natl. Acad. Sci USA 2001, 98, 5578–5583]. We have been able to design, synthesize and characterize a hairpin based on this motif which incorporates an azobenzene‐based photoswitch, that allows for time‐resolved folding studies of β‐structures with unprecedented time resolution. At room temperature the trans‐azo isomer exhibits a mostly disordered structure; however, light‐induced isomerization to the cis‐azo form leads to a predominantly extended and parallel conformation of the two peptide parts, which are linked by the novel photoswitch, [3‐(3‐aminomethyl)phenylazo]phenylacetic acid (AMPP). While in the original sequence the dipeptide Asn‐Gly forms a type I′ β‐turn which connects the two strands of the hairpin, this role is adopted by the AMPP chromophore in our photoresponsive β‐hairpin that can apparently act as a β I′‐turn mimetic. The β‐hairpin structure was determined and confirmed by NMR spectroscopy, but the folding process can be monitored by pronounced changes in the CD, IR and fluorescence spectra. Finally, incorporation of the structurally and functionally important β‐hairpin motif into proteins by chemical ligation might allow for the photocontrol of protein structures and/or functions.