bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution, ecological attributes and trade of the New Guinea carpet python (Morelia spilota) in Indonesia
Authors: Natusch Daniel J. D. , Lyons Jessica A.
Published: March 2012

Carpet pythons (Morelia spilota) are medium-sized non-venomous snakes inhabiting most of continental Australia and a small area of New Guinea. They have been relatively well studied in Australia, but little is known about the New Guinea population, even though it is harvested and exported from Indonesia for the international pet trade. In total, 281 locality records were compiled for two distinct populations south of latitude 7°S in Papua New Guinea and the Indonesian province of Papua. Traders in Papua collected 274 carpet pythons (most of which were recently hatched neonates) for the pet trade. Data from a sample of 174 individuals revealed little sexual dimorphism in any traits, although males appear to grow larger than females despite females maturing at greater lengths. Fecundity was high (average 17 eggs) and reproduction was highly seasonal, with hatching in December and January. Harvest quotas for the province of Papua were exceeded in all years between 2000 and 2009 due to 50% of the national quota being allocated to West Papua province where this species is yet to be recorded. The present study provides distribution, trade and ecological information to inform conservation management of this species in Indonesia.
Mesoamerican origin of the common bean (
Phaseolus vulgaris
L.) is revealed by sequence data
Authors: Bitocchi Elena , Nanni Laura , Bellucci Elisa , Rossi Monica , Giardini Alessandro , Zeuli Pierluigi Spagnoletti , Logozzo Giuseppina , Stougaard Jens , McClean Phillip , Attene Giovanna , Papa Roberto
Published: March 2012

Knowledge about the origins and evolution of crop species represents an important prerequisite for efficient conservation and use of existing plant materials. This study was designed to solve the ongoing debate on the origins of the common bean by investigating the nucleotide diversity at five gene loci of a large sample that represents the entire geographical distribution of the wild forms of this species. Our data clearly indicate a Mesoamerican origin of the common bean. They also strongly support the occurrence of a bottleneck during the formation of the Andean gene pool that predates the domestication, which was suggested by recent studies based on multilocus molecular markers. Furthermore, a remarkable result was the genetic structure that was seen for the Mesoamerican accessions, with the identification of four different genetic groups that have different relationships with the sets of wild accessions from the Andes and northern Peru–Ecuador. This finding implies that both of the gene pools from South America originated through different migration events from the Mesoamerican populations that were characteristic of central Mexico.
Mechanism for Burgess Shale-type preservation
Authors: Gaines Robert R. , Hammarlund Emma U. , Hou Xianguang , Qi Changshi , Gabbott Sarah E. , Zhao Yuanlong , Peng Jin , Canfield Donald E.
Published: March 2012

Exceptionally preserved fossil biotas of the Burgess Shale and a handful of other similar Cambrian deposits provide rare but critical insights into the early diversification of animals. The extraordinary preservation of labile tissues in these geographically widespread but temporally restricted soft-bodied fossil assemblages has remained enigmatic since Walcott’s initial discovery in 1909. Here, we demonstrate the mechanism of Burgess Shale-type preservation using sedimentologic and geochemical data from the Chengjiang, Burgess Shale, and five other principal Burgess Shale-type deposits. Sulfur isotope evidence from sedimentary pyrites reveals that the exquisite fossilization of organic remains as carbonaceous compressions resulted from early inhibition of microbial activity in the sediments by means of oxidant deprivation. Low sulfate concentrations in the global ocean and low-oxygen bottom water conditions at the sites of deposition resulted in reduced oxidant availability. Subsequently, rapid entombment of fossils in fine-grained sediments and early sealing of sediments by pervasive carbonate cements at bed tops restricted oxidant flux into the sediments. A permeability barrier, provided by bed-capping cements that were emplaced at the seafloor, is a feature that is shared among Burgess Shale-type deposits, and resulted from the unusually high alkalinity of Cambrian oceans. Thus, Burgess Shale-type preservation of soft-bodied fossil assemblages worldwide was promoted by unique aspects of early Paleozoic seawater chemistry that strongly impacted sediment diagenesis, providing a fundamentally unique record of the immediate aftermath of the “Cambrian explosion.”
Lateral prefrontal cortex contributes to maladaptive decisions
Authors: Xue Gui , Juan Chi-Hung , Chang Chi-Fu , Lu Zhong-Lin , Dong Qi
Published: March 2012

Humans consistently make suboptimal decisions involving random events, yet the underlying neural mechanisms remain elusive. Using functional MRI and a matching pennies game that captured subjects’ increasing tendency to predict the break of a streak as it continued [i.e., the “gambler's fallacy” (GF)], we found that a strong blood oxygen level-dependent response in the left lateral prefrontal cortex (LPFC) to the current outcome preceded the use of the GF strategy 10 s later. Furthermore, anodal transcranial direct current stimulation over the left LPFC, which enhances neuronal firing rates and cerebral excitability, increased the use of the GF strategy, and made the decisions more “sticky.” These results reveal a causal role of the LPFC in implementing suboptimal decision strategy guided by false world models, especially when such strategy requires great resources for cognitive control.
Salience network integrity predicts default mode network function after traumatic brain injury
Authors: Bonnelle Valerie , Ham Timothy E. , Leech Robert , Kinnunen Kirsi M. , Mehta Mitul A. , Greenwood Richard J. , Sharp David J.
Published: March 2012

Efficient behavior involves the coordinated activity of large-scale brain networks, but the way in which these networks interact is uncertain. One theory is that the salience network (SN)—which includes the anterior cingulate cortex, presupplementary motor area, and anterior insulae—regulates dynamic changes in other networks. If this is the case, then damage to the structural connectivity of the SN should disrupt the regulation of associated networks. To investigate this hypothesis, we studied a group of 57 patients with cognitive impairments following traumatic brain injury (TBI) and 25 control subjects using the stop-signal task. The pattern of brain activity associated with stop-signal task performance was studied by using functional MRI, and the structural integrity of network connections was quantified by using diffusion tensor imaging. Efficient inhibitory control was associated with rapid deactivation within parts of the default mode network (DMN), including the precuneus and posterior cingulate cortex. TBI patients showed a failure of DMN deactivation, which was associated with an impairment of inhibitory control. TBI frequently results in traumatic axonal injury, which can disconnect brain networks by damaging white matter tracts. The abnormality of DMN function was specifically predicted by the amount of white matter damage in the SN tract connecting the right anterior insulae to the presupplementary motor area and dorsal anterior cingulate cortex. The results provide evidence that structural integrity of the SN is necessary for the efficient regulation of activity in the DMN, and that a failure of this regulation leads to inefficient cognitive control.
Phase separation and rotor self-assembly in active particle suspensions
Authors: Schwarz-Linek J. , Valeriani C. , Cacciuto A. , Cates M. E. , Marenduzzo D. , Morozov A. N. , Poon W. C. K.
Published: March 2012

Adding a nonadsorbing polymer to passive colloids induces an attraction between the particles via the “depletion” mechanism. High enough polymer concentrations lead to phase separation. We combine experiments, theory, and simulations to demonstrate that using active colloids (such as motile bacteria) dramatically changes the physics of such mixtures. First, significantly stronger interparticle attraction is needed to cause phase separation. Secondly, the finite size aggregates formed at lower interparticle attraction show unidirectional rotation. These micro-rotors demonstrate the self-assembly of functional structures using active particles. The angular speed of the rotating clusters scales approximately as the inverse of their size, which may be understood theoretically by assuming that the torques exerted by the outermost bacteria in a cluster add up randomly. Our simulations suggest that both the suppression of phase separation and the self-assembly of rotors are generic features of aggregating swimmers and should therefore occur in a variety of biological and synthetic active particle systems.
A requirement for the neuromodulators octopamine and tyramine in
Drosophila melanogaster
female sperm storage
Authors: Avila Frank W. , Bloch Qazi Margaret C. , Rubinstein C. Dustin , Wolfner Mariana F.
Published: March 2012

Female sperm storage is common among organisms with internal fertilization. It is important for extended fertility and, in cases of multiple mating, for sperm competition. The physiological mechanisms by which females store and manage stored sperm are poorly understood. Here, we report that the biogenic amines tyramine (TA) and octopamine (OA) in
Drosophila melanogaster
females play essential roles in sperm storage.
D. melanogaster
females store sperm in two types of organs, a single seminal receptacle and a pair of spermathecae. We examined sperm storage parameters in females mutant in enzymes required for the biochemical synthesis of tyrosine to TA and TA to OA, respectively. Postmating uterine conformational changes, which are associated with sperm entry and accumulation into storage, were unaffected by the absence of either TA or OA. However, sperm release from storage requires both TA and OA; sperm were retained in storage in both types of mutant females at significantly higher levels than in control flies. Absence of OA inhibited sperm depletion only from the seminal receptacle, whereas absence of both OA and TA perturbed sperm depletion from both storage organ types. We find innervation of the seminal receptacle and spermathecae by octopaminergic-tyraminergic neurons. These findings identify a distinct role for TA and OA in reproduction, regulating the release of sperm from storage, and suggest a mechanism by which
Drosophila
females actively regulate the release of stored sperm.
Inhibition of cytochrome P4501-dependent clearance of the endogenous agonist FICZ as a mechanism for activation of the aryl hydrocarbon receptor
Authors: Wincent Emma , Bengtsson Johanna , Bardbori Afshin Mohammadi , Alsberg Tomas , Luecke Sandra , Rannug Ulf , Rannug Agneta
Published: March 2012

Altered systemic levels of 6-formylindolo[3,2-
b
]carbazole (FICZ), an enigmatic endogenous ligand for the aryl hydrocarbon receptor (AHR), may explain adverse physiological responses evoked by small natural and anthropogenic molecules as well as by oxidative stress and light. We demonstrate here that several different chemical compounds can inhibit the metabolism of FICZ, thereby disrupting the autoregulatory feedback control of cytochrome P4501 systems and other proteins whose expression is regulated by AHR. FICZ is both the most tightly bound endogenous agonist for the AHR and an ideal substrate for cytochrome CYP1A1/1A2 and 1B1, thereby also participating in an autoregulatory loop that keeps its own steady-state concentration low. At very low concentrations FICZ influences circadian rhythms, responses to UV light, homeostasis associated with pro- and anti-inflammatory processes, and genomic stability. Here, we demonstrate that, if its metabolic clearance is compromised, femtomolar background levels of this compound in cell-culture medium are sufficient to up-regulate CYP1A1 mRNA and enzyme activity. The oxidants UVB irradiation and hydrogen peroxide and the model AHR antagonist 3′-methoxy-4′-nitroflavone all inhibited induction of CYP1A1 enzyme activity by FICZ or 2,3,7,8-tetrachlorodibenzo-
p
-dioxin, thereby subsequently elevating intracellular levels of FICZ and activating AHR. Taken together, these findings support an indirect mechanism of AHR activation, indicating that AHR activation by molecules with low affinity actually may reflect inhibition of FICZ metabolism and raising questions about the reported promiscuity of the AHR. Accordingly, we propose that prolonged induction of AHR activity through inhibition of CYP1 disturbs feedback regulation of FICZ levels, with potential detrimental consequences.
Continent-wide risk assessment for the establishment of nonindigenous species in Antarctica
Authors: Chown Steven L. , Huiskes Ad H. L. , Gremmen Niek J. M. , Lee Jennifer E. , Terauds Aleks , Crosbie Kim , Frenot Yves , Hughes Kevin A. , Imura Satoshi , Kiefer Kate , Lebouvier Marc , Raymond Ben , Tsujimoto Megumu , Ware Chris , Van de Vijver Bart , Bergstrom Dana Michelle
Published: March 2012

Invasive alien species are among the primary causes of biodiversity change globally, with the risks thereof broadly understood for most regions of the world. They are similarly thought to be among the most significant conservation threats to Antarctica, especially as climate change proceeds in the region. However, no comprehensive, continent-wide evaluation of the risks to Antarctica posed by such species has been undertaken. Here we do so by sampling, identifying, and mapping the vascular plant propagules carried by all categories of visitors to Antarctica during the International Polar Year's first season (2007–2008) and assessing propagule establishment likelihood based on their identity and origins and on spatial variation in Antarctica's climate. For an evaluation of the situation in 2100, we use modeled climates based on the Intergovernmental Panel on Climate Change's Special Report on Emissions Scenarios Scenario A1B [Nakićenović N, Swart R, eds (2000)
Special Report on Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change
(Cambridge University Press, Cambridge, UK)]. Visitors carrying seeds average 9.5 seeds per person, although as vectors, scientists carry greater propagule loads than tourists. Annual tourist numbers (∼33,054) are higher than those of scientists (∼7,085), thus tempering these differences in propagule load. Alien species establishment is currently most likely for the Western Antarctic Peninsula. Recent founder populations of several alien species in this area corroborate these findings. With climate change, risks will grow in the Antarctic Peninsula, Ross Sea, and East Antarctic coastal regions. Our evidence-based assessment demonstrates which parts of Antarctica are at growing risk from alien species that may become invasive and provides the means to mitigate this threat now and into the future as the continent's climate changes.
X-ray repair cross-complementing protein 1 (XRCC1) deficiency enhances class switch recombination and is permissive for alternative end joining
Authors: Han Li , Mao Weifeng , Yu Kefei
Published: March 2012

DNA double-strand breaks (DSBs) are essential intermediates in Ig gene rearrangements: V(D)J and class switch recombination (CSR). In contrast to V(D)J recombination, which is almost exclusively dependent on nonhomologous end joining (NHEJ), CSR can occur in NHEJ-deficient cells via a poorly understand backup pathway (or pathways) often termed alternative end joining (A-EJ). Recently, several components of the single-strand DNA break (SSB) repair machinery, including XRCC1, have been implicated in A-EJ. To determine its role in A-EJ and CSR,Xrcc1was deleted by targeted mutation in the CSR proficient mouse B-cell line, CH12F3. Here we demonstrate that XRCC1 deficiency slightly increases the efficiency of CSR. More importantly, Lig4 and XRCC1 double-deficient cells switch as efficiently as Lig4-deficient cells, clearly indicating that XRCC1 is dispensable for A-EJ in CH12F3 cells during CSR.
Scanning probe-enabled nanocombinatorics define the relationship between fibronectin feature size and stem cell fate
Authors: Giam Louise R. , Massich Matthew D. , Hao Liangliang , Shin Wong Lu , Mader Christopher C. , Mirkin Chad A.
Published: March 2012

We report the development of a powerful analytical method that utilizes a tilted elastomeric pyramidal pen array in the context of a scanning probe lithography experiment to rapidly prepare libraries having as many as 25 million features over large areas with a range of feature sizes from the nano- to microscale. This technique can be used to probe important chemical and biological processes, opening up the field of nanocombinatorics. In a proof-of-concept investigation of mesenchymal stem cell (MSC) differentiation, combinatorial patterns first enabled a rapid and systematic screening of MSC adhesion, as a function of feature size, while uniform patterns were used to study differentiation with statistically significant sample sizes. Without media containing osteogenic-inducing chemical cues, cells cultured on nanopatterned fibronectin substrates direct MSC differentiation towards osteogenic fates when compared to nonpatterned fibronectin substrates. This powerful and versatile approach enables studies of many systems spanning biology, chemistry, and engineering areas.
Rapid self-healing hydrogels
Authors: Phadke Ameya , Zhang Chao , Arman Bedri , Hsu Cheng-Chih , Mashelkar Raghunath A. , Lele Ashish K. , Tauber Michael J. , Arya Gaurav , Varghese Shyni
Published: March 2012

Synthetic materials that are capable of autonomous healing upon damage are being developed at a rapid pace because of their many potential applications. Despite these advancements, achieving self-healing in permanently cross-linked hydrogels has remained elusive because of the presence of water and irreversible cross-links. Here, we demonstrate that permanently cross-linked hydrogels can be engineered to exhibit self-healing in an aqueous environment. We achieve this feature by arming the hydrogel network with flexible-pendant side chains carrying an optimal balance of hydrophilic and hydrophobic moieties that allows the side chains to mediate hydrogen bonds across the hydrogel interfaces with minimal steric hindrance and hydrophobic collapse. The self-healing reported here is rapid, occurring within seconds of the insertion of a crack into the hydrogel or juxtaposition of two separate hydrogel pieces. The healing is reversible and can be switched on and off via changes in pH, allowing external control over the healing process. Moreover, the hydrogels can sustain multiple cycles of healing and separation without compromising their mechanical properties and healing kinetics. Beyond revealing how secondary interactions could be harnessed to introduce new functions to chemically cross-linked polymeric systems, we also demonstrate various potential applications of such easy-to-synthesize, smart, self-healing hydrogels.
Agonist binding evokes extensive conformational changes in the extracellular domain of the ATP-gated human P2X1 receptor ion channel
Authors: Roberts Jonathan A. , Allsopp Rebecca C. , El Ajouz Sam , Vial Catherine , Schmid Ralf , Young Mark T. , Evans Richard J.
Published: March 2012

P2X receptors for ATP have a wide range of physiological roles and comprise a structurally distinct family of ligand-gated trimeric ion channels. The crystal structure of a P2X4 receptor, in combination with mutagenesis studies, has provided a model of the intersubunit ATP-binding sites and identified an extracellular lateral portal, adjacent to the membrane, that funnels ions to the channel pore. However, little is known about the extent of ATP-induced conformational changes in the extracellular domain of the receptor. To address this issue, we have used MTSEA-biotinylation (
N
-Biotinoylaminoethyl methanethiosulfonate) to show ATP-sensitive accessibility of cysteine mutants at the human P2X1 receptor. Mapping these data to a P2X1 receptor homology model identifies significant conformational rearrangement. Electron microscopy of purified P2X1 receptors showed marked changes in structure on ATP binding, and introducing disulphide bonds between adjacent subunits to restrict intersubunit movements inhibited channel function. These results are consistent with agonist-induced rotation of the propeller-head domain of the receptor, sliding of adjacent subunits leading to restricted access to the upper vestibule, movement in the ion conducting lateral portals, and gating of the channel pore.
The cell biology of regeneration
Authors: King Ryan S. , Newmark Phillip A.
Published: March 2012

Regeneration of complex structures after injury requires dramatic changes in cellular behavior. Regenerating tissues initiate a program that includes diverse processes such as wound healing, cell death, dedifferentiation, and stem (or progenitor) cell proliferation; furthermore, newly regenerated tissues must integrate polarity and positional identity cues with preexisting body structures. Gene knockdown approaches and transgenesis-based lineage and functional analyses have been instrumental in deciphering various aspects of regenerative processes in diverse animal models for studying regeneration.
Stimulation of the neurotrophin receptor TrkB on astrocytes drives nitric oxide production and neurodegeneration
Authors: Colombo Emanuela , Cordiglieri Chiara , Melli Giorgia , Newcombe Jia , Krumbholz Markus , Parada Luis F. , Medico Enzo , Hohlfeld Reinhard , Meinl Edgar , Farina Cinthia
Published: March 2012

Neurotrophin growth factors support neuronal survival and function. In this study, we show that the expression of the neurotrophin receptor TrkB is induced on astrocytes in white matter lesions in multiple sclerosis (MS) patients and mice with experimental autoimmune encephalomyelitis (EAE). Surprisingly, mice lacking TrkB specifically in astrocytes were protected from EAE-induced neurodegeneration. In an in vitro assay, astrocytes stimulated with the TrkB agonist brain-derived neurotrophic factor (BDNF) released nitric oxide (NO), and conditioned medium from activated astrocytes had detrimental effects on the morphology and survival of neurons. This neurodegenerative process was amplified by NO produced by neurons. NO synthesis in the central nervous system during EAE depended on astrocyte TrkB. Together, these findings suggest that TrkB expression on astrocytes may represent a new target for neuroprotective therapies in MS.
THE CLUSTERED NATURE OF STAR FORMATION. PRE-MAIN-SEQUENCE CLUSTERS IN THE STAR-FORMING REGION NGC 602/N90 IN THE SMALL MAGELLANIC CLOUD*
Authors: Gouliermis Dimitrios A. , Schmeja Stefan , Dolphin Andrew E. , Gennaro Mario , Tognelli Emanuele , Prada Moroni Pier Giorgio
Published: March 2012

Located at the tip of the wing of the Small Magellanic Cloud (SMC), the star-forming region NGC 602/N90 is characterized by the H ii nebular ring N90 and the young cluster of pre-main-sequence (PMS) and early-type main-sequence stars NGC 602, located in the central area of the ring. We present a thorough cluster analysis of the stellar sample identified with Hubble Space Telescope/Advanced Camera for Surveys in the region. We show that apart from the central cluster low-mass PMS stars are congregated in 13 additional small, compact sub-clusters at the periphery of NGC 602, identified in terms of their higher stellar density with respect to the average background density derived from star counts. We find that the spatial distribution of the PMS stars is bimodal, with an unusually large fraction (∼60%) of the total population being clustered, while the remaining is diffusely distributed in the intercluster area, covering the whole central part of the region. From the corresponding color–magnitude diagrams we disentangle an age difference of ∼2.5 Myr between NGC 602 and the compact sub-clusters, which appear younger, on the basis of comparison of the brighter PMS stars with evolutionary models, which we accurately calculated for the metal abundance of the SMC. The diffuse PMS population appears to host stars as old as those in NGC 602. Almost all detected PMS sub-clusters appear to be centrally concentrated. When the complete PMS stellar sample, including both clustered and diffused stars, is considered in our cluster analysis, it appears as a single centrally concentrated stellar agglomeration, covering the whole central area of the region. Considering also the hot massive stars of the system, we find evidence that this agglomeration is hierarchically structured. Based on our findings, we propose a scenario according to which the region NGC 602/N90 experiences an active clustered star formation for the last ∼5 Myr. The central cluster NGC 602 was formed first and rapidly started dissolving into its immediate ambient environment, possibly ejecting also massive stars found away from its center. Star formation continued in sub-clusters of a larger stellar agglomeration, introducing an age spread of the order of 2.5 Myr among the PMS populations.
Characterization of transient discharges under atmospheric-pressure conditions applying nitrogen photoemission and current measurements
Authors: Keller Sandra , Rajasekaran Priyadarshini , Bibinov Nikita , Awakowicz Peter
Published: March 2012

The plasma parameters such as electron distribution function and electron density of three atmospheric-pressure transient discharges namely filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of an argon plasma coagulation (APC) system are determined. A combination of numerical simulation as well as diagnostic methods including current measurement and optical emission spectroscopy (OES) based on nitrogen emissions is used. The applied methods supplement each other and resolve problems, which arise when these methods are used individually. Nitrogen is used as a sensor gas and is admixed in low amount to argon for characterizing the APC discharge. Both direct and stepwise electron-impact excitation of nitrogen emissions are included in the plasma-chemical model applied for characterization of these transient discharges using OES where ambiguity arises in the determination of plasma parameters under specific discharge conditions. It is shown that the measured current solves this problem by providing additional information useful for the determination of discharge-specific plasma parameters.
Crystal structure, electronic structure and thermoelectric properties of n-type BiSbSTe2
Authors: Aminorroaya-Yamini Sima , Zhang Chao , Wang Xiaolin , Nevirkovets Ivan
Published: March 2012

N-type bismuth telluride sulfide has received attention as a potential thermoelectric material due to its large thermopower and ability to form solid solutions with bismuth antimony sulfide. Here, we fabricated an n-type tetradymite BiSbSTe2 by solid-state reaction. The crystal structure was found to be rhombohedral, and the thermoelectric properties were measured for the temperature range 50–390 K. A high Seebeck coefficient of −190 µV K−1 was achieved at 385 K. The electronic structure of BiSbSTe2 was investigated using first-principles calculations and compared with its parent counterpart (Bi2STe2). The results have shown that BiSbSTe2 is a narrow band-gap semiconductor. For the first time, we have demonstrated that the vacancies in substitutional atomic sites, which can be altered through different fabrication techniques, can determine the charge carrier nature of tetradymite thermoelectrics. As a proof of concept, we have shown that the vacancies in antimony sites result in a p-type compound while a sulfur deficiency produces an n-type phase with lower electrical conductivity.
Preparation and characterization of titanium dioxide nanotube array supported hydrated ruthenium oxide catalysts
Authors: Giang Thi Phuong Ly , Tran Thi Nhu Mai , Le Xuan Tuan
Published: March 2012

This work aimed at preparing and characterizing TiO
2 nanotube supported hydrated ruthenium oxide catalysts. First of all, we succeeded in preparing TiO
2 nanotube arrays by electrochemical anodization of titanium metal at 20 V for 8 h in a 1M H
3
PO
4+0.5 wt% HF solution as evidenced from scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) results. The hydrated ruthenium oxide was then deposited onto TiO
2 nanotubes by consecutive exchange of protons by Ru
3+ ions, followed by formation of hydrated oxide during the alkali treatment. Further XPS measurements showed that the modified samples contain not only hydrated ruthenium oxide but also hydrated ruthenium species Ru(III)-OH.
Test ideals via algebras of 𝑝^{-𝑒}-linear maps
Authors: Blickle Manuel
Published: March 2012

Building on previous work of Schwede, Böckle, and the author, we study test ideals by viewing them as minimal objects in a certain class of modules, called

F
F

-pure modules, over algebras of

p

−
e

p^{-e}

-linear operators. We develop the basics of a theory of

F
F

-pure modules and show an important structural result, namely that

F
F

-pure modules have finite length. This result is then linked to the existence of test ideals and leads to a simplified and generalized treatment, also allowing us to define test ideals in non-reduced settings.

Combining our approach with an observation of Anderson on the contracting property of

p

−
e

p^{-e}

-linear operators yields an elementary approach to test ideals in the case of affine

k
k

-algebras, where

k
k

is an

F
F

-finite field. As a byproduct, one obtains a short and completely elementary proof of the discreteness of the jumping numbers of test ideals in a generality that extends most cases known so far; in particular, one obtains results beyond the

Q

\mathbb {Q}

-Gorenstein case.
EZH2 couples pancreatic regeneration to neoplastic progression
Authors: Mallen-St. Clair Jon , Soydaner-Azeloglu Rengin , Lee Kyoung Eun , Taylor Laura , Livanos Alexandra , Pylayeva-Gupta Yuliya , Miller George , Margueron Raphaël , Reinberg Danny , Bar-Sagi Dafna
Published: March 2012

Although the polycomb group protein Enhancer of Zeste Homolog 2 (EZH2) is well recognized for its role as a key regulator of cell differentiation, its involvement in tissue regeneration is largely unknown. Here we show that EZH2 is up-regulated following cerulein-induced pancreatic injury and is required for tissue repair by promoting the regenerative proliferation of progenitor cells. Loss of EZH2 results in impaired pancreatic regeneration and accelerates KRasG12D-driven neoplasia. Our findings implicate EZH2 in constraining neoplastic progression through homeostatic mechanisms that control pancreatic regeneration and provide insights into the documented link between chronic pancreatic injury and an increased risk for pancreatic cancer.
Arabidopsis WRKY33 Is a Key Transcriptional Regulator of Hormonal and Metabolic Responses toward Botrytis cinerea Infection
Authors: Birkenbihl Rainer P. , Diezel Celia , Somssich Imre E.
Published: March 2012

The Arabidopsis (Arabidopsis thaliana) transcription factor WRKY33 is essential for defense toward the necrotrophic fungus Botrytis cinerea. Here, we aimed at identifying early transcriptional responses mediated by WRKY33. Global expression profiling on susceptible wrky33 and resistant wild-type plants uncovered massive differential transcriptional reprogramming upon B. cinerea infection. Subsequent detailed kinetic analyses revealed that loss of WRKY33 function results in inappropriate activation of the salicylic acid (SA)-related host response and elevated SA levels post infection and in the down-regulation of jasmonic acid (JA)-associated responses at later stages. This down-regulation appears to involve direct activation of several jasmonate ZIM-domain genes, encoding repressors of the JA-response pathway, by loss of WRKY33 function and by additional SA-dependent WRKY factors. Moreover, genes involved in redox homeostasis, SA signaling, ethylene-JA-mediated cross-communication, and camalexin biosynthesis were identified as direct targets of WRKY33. Genetic studies indicate that although SA-mediated repression of the JA pathway may contribute to the susceptibility of wrky33 plants to B. cinerea, it is insufficient for WRKY33-mediated resistance. Thus, WRKY33 apparently directly targets other still unidentified components that are also critical for establishing full resistance toward this necrotroph.
Pseudopolymorphism in hydroxybenzophenones: the dihydrate of 2,2′,4,4′-tetrahydroxybenzophenone
Authors: Landre I. M. R. , Martins F. T. , Ellena J. A. , Dos Santos M. H. , Doriguetto A. C.
Published: March 2012

A dihydrate pseudopolymorph of bis(2,4-dihydroxyphenyl)methanone, C13H10O5·2H2O, (I), was obtained during polymorphism screening of hydroxybenzophenone derivatives. This structure, in which the molecule sits on a twofold axis, was compared with the known anhydrous form of (I) [Schlemper (1982).Acta Cryst.B38, 554–559]. The role of water in the crystal assembly was established on the basis of the known monohydrate pseudopolymorph of 3,4-dihydroxybenzophenone [Landre, Souza, Corrêa, Martins & Doriguetto (2010).Acta Cryst.C66, o463–o465].
Alkyl-chain disorder in tetraisohexylammonium bromide
Authors: Kelland Malcolm A. , Thompson Amber L.
Published: March 2012

Tetraisohexylammonium bromide [systematic name: tetrakis(4-methylpentyl)azanium bromide], C24H52N+·Br−, is a powerful structure II clathrate hydrate crystal-growth inhibitor. The crystal structure, in the space groupP3221, contains one ammonium cation and one bromide anion in the asymmetric unit, both on general positions. At 100 K, the ammonium cation exhibits one ordered isohexyl chain and three disordered isohexyl chains. At 250 K, all four isohexyl chains are disordered. In an effort to reduce the disorder in the alkyl chains, the crystal was thermally cycled, but the disorder remained, indicating that it is dynamic in nature.
(Z)-2-(2-Oxoindolin-3-ylidene)-N-phenylhydrazinecarbothioamide
Authors: Qasem Ali Amna , Eltayeb Naser Eltaher , Teoh Siang Guan , Salhin Abdussalam , Fun Hoong-Kun
Published: March 2012

In the title compound, C15H12N4OS, the dihedral angle between the nine-membered indolin-2-one ring system and the phenyl ring is 2.72 (7)°. Intramolecular cyclic N—H...O and C—H...S hydrogen-bonding interactions [graph setS(6)] are present, as are weak N—H...N interactions [graph setS(5)]. In the crystal, molecules form centrosymmetric cyclic dimers through pairs of N—H...O hydrogen bonds [graph setR22(8)] and these are extended by C—H...S interactions. The crystal structure also features weak C—H...π interactions.
4-Chlorobenzoyl-meso-octamethylcalix[2]pyrrolidino[2]pyrrole: an acyl chloride derivative of a partially reduced calix[4] pyrrole
Authors: Journot Guillaume , Neier Reinhard , Stoeckli-Evans Helen
Published: March 2012

In the title compound, C35H47ClN4O, the two pyrrolidine rings have envelope conformations. The conformation of the macrocycle is stabilized by N—H...N hydrogen bonds and a C—H...N interaction. The benzoyl ring is inclined to the adjacent pyrrole ring by 11.66 (11)°, with a centroid–centroid distance of 3.7488 (13) Å. In the crystal, molecules are linked by N—H...O hydrogen bonds into helical chains propagating in [010] and C—H...O and C—H...π interactions are also observed.
4-Methoxy-N-(4-nitrobenzyl)aniline
Authors: Kapoor Kamini , Gupta Vivek K. , Kumar Indresh , Mir Nisar A. , Kant Rajni
Published: March 2012

In the title compound, C14H14N2O3, the nitro group is nearly coplanar with the benzene ring to which it is bonded [dihedral angle = 1.70 (2)°], and this ring ispara-substituted by the aminomethylene group. The dihedral angle between the benzene rings is 57.8 (1)°. The crystal structure is stabilized by N—H...O and C—H...O hydrogen bonds and weak C—H...π interactions are also observed.
A new polymorph of 5,5′-(ethane-1,2-diyl)bis(1H-tetrazole)
Authors: Qiao Cheng-Fang , Zhou Chun-Sheng , Wei Qing , Xia Zheng-Qiang
Published: March 2012

The asymmetric unit of the title compound, C4H6N8, contains a quarter of the molecule, which possesses a crystallographically imposed centre of symmetry with all non-H atoms situated on a mirror plane. The crystal packing exhibits intermolecular N—H...N hydrogen bonds and π–π stacking interactions between the tetrazole rings of adjacent molecules [centroid–centroid distance = 3.4402 (10) Å].
Diisopropylammonium nitrite
Authors: Wang Ying-Chun , Jie Xu
Published: March 2012

In the title molecular salt, C6H16N+·NO2−, the cation forms two N—H...O hydrogen bonds to nearby nitrite anions which link the ionic units into chains propagating along theb-axis direction.
A triclinic polymorph ofN-[4-(4-methylbenzenesulfonamido)phenylsulfonyl]acetamide
Authors: Hayat Khizar , Asghar Muhammad Nadeem , Tahir M. Nawaz , Shafiq Muhammad , Ahmad Dildar
Published: March 2012

In the asymmetric unit of the title compound, C15H16N2O5S2, there are two symmetry-independent molecules which adopt similar conformations, with dihedral angles between the aromatic rings of 59.30 (8) and 61.81 (8)°, and dihedral angles between acetamide group and the benzene ring of 77.08 (10) and 78.40 (10)°. Each type of molecule forms similar one-dimensional polymeric structures extending along thebaxisviaN—H...O hydrogen bonds. These hydrogen bonds generate two types of centrosymmetric motifs,R22(8) andR22(20). Moreover C—H...O interactions assemble the molecules into a three-dimensional framework. The crystal structure was determined from a non-merohedral twin [ratio of the twin components = 0.322 (4):0.678 (4)].
(2E)-3-(3-Nitrophenyl)-1-[4-(piperidin-1-yl)phenyl]prop-2-en-1-one
Authors: Fun Hoong-Kun , Chia Tze Shyang , Nayak Prakash S. , Narayana B. , Sarojini B. K.
Published: March 2012

In the title compound, C20H20N2O3, the piperidine ring adopts a chair conformation and its mean plane forms dihedral angles of 19.63 (9) and 19.44 (9)°, respectively, with the benzene and the nitro-substituted benzene ring. The benzene and nitro-substituted benzene rings are almost coplanar and make a dihedral angle of 4.78 (8)°. In the crystal, molecules are linked by C—H...O hydrogen bonds into two-dimensional networks parallel to theabplane. The crystal packing is further stabilized by π–π interactions [maximum centroid–centroid distance = 3.7807 (12) Å].
Poly[μ2-aqua-bis[μ4-2-(1H-1,2,3-benzotriazol-1-yl)acetato]dipotassium]
Authors: Liu Qiong
Published: March 2012

In the title compound, [K2(C8H6N3O2)2(H2O)]n, each K+ion is seven-coordinated by one O atom from a bridging water molecule, five carboxylate O atoms and one N atom from a benzotriazole group, forming a distorted mono-capped octahedral geometry. In the crystal, the carboxylate groups act as bridging ligands, forming a two-dimensional polymer parallel to (001). The aqua ligand, which lies on a twofold rotation axis, forms intermolecular O—H...O hydrogen bonds within these layers.
3-[Hydroxy(3-methoxyphenyl)methylidene]-2-(2-oxo-2-phenylethyl)-3,4-dihydro-2H-1λ6,2-benzothiazine-1,1,4-trione
Authors: Siddiqui Hamid Latif , Ahmad Matloob , Gul Salman , Siddiqui Waseeq Ahmad , Parvez Masood
Published: March 2012

In the title molecule, C24H19NO6S, the heterocyclic thiazine ring adopts a half-chair conformation with the S and N atoms displaced by 0.180 (5) and 0.497 (5) Å, respectively, on opposite sides of the mean plane formed by the remaining ring atoms. The benzene rings of the benzothiazine unit and the methoxyphenyl group are almost coplanar, with the dihedral angle between the mean planes of these rings being 5.9 (2)°, while the benzene ring of the 2-oxo-2-phenylethyl group is inclined at 79.68 (11) and 81.01 (10)°, respectively, to these rings. The molecular structure is consolidated by intramolecular O—H...O and C—H...N interactions, and the crystal packing is stabilized by weak C—H...O hydrogen bonds.
4-[3-(Biphenyl-4-yl)-1-phenyl-4,5-dihydro-1H-pyrazol-5-yl]-3-(4-methoxyphenyl)-1-phenyl-1H-pyrazole dioxane monosolvate
Authors: Fun Hoong-Kun , Arshad Suhana , Malladi Shridhar , Isloor Arun M. , Shivananda Kammasandra Nanjunda
Published: March 2012

In the title compound, C37H30N4O·C4H8O2, the dihedral angle between the pyrazole and dihydropyrazole rings is 74.09 (10)°. In the crystal, the components are linked into centrosymmetric tetramers (two main molecules and two solvent molecules) by C—H...O hydrogen bonds. C—H...π and π–π [shortest centroid-centroid separation = 3.6546 (9) Å] interactions are also observed.
Dichlorido[2-(phenyliminomethyl)quinoline-N,N′]palladium(II)
Authors: Motswainyana William M. , Onani Martin O. , Madiehe Abram M.
Published: March 2012

In the title complex, [PdCl2(C16H12N2)], the PdIIion is coordinated by two N atoms [Pd—N 2.039 (2), 2.073 (2) Å] from a bidentate ligand and two chloride anions [Pd—Cl 2.2655 (7), 2.2991 (7) Å] in a distorted square-planar geometry. In the crystal, π–π interactions between the six-membered rings of the quinoline fragments [centroid–centroid distances = 3.815 (5), 3.824 (5) Å] link two molecules into centrosymmetric dimers.
(E)-N′-(5-Chloro-2-hydroxybenzylidene)-2,4-dihydroxybenzohydrazide methanol monosolvate
Authors: Li Kun
Published: March 2012

In the title compound, C14H11ClN2O4·CH3OH, the molecule adopts anEconformation about the C=N bond. The compound is in the enamine–keto form. The two terminal benzene rings make a dihedral angle of 10.53 (9)°. Intra-molecular O—H...O and O—H...N hydrogen bonding stabilizes the molecular structure. In the crystal, O—H...O hydrogen bonds link the molecules, forming chains running along thebaxis.
Ethyl 2-{3-[(6-chloropyridin-3-yl)methyl]-2-(nitroimino)imidazolidin-1-yl}acetate
Authors: Kapoor Kamini , Deshmukh Madhukar B. , Shripanavar Chetan S. , Gupta Vivek K. , Kant Rajni
Published: March 2012

In the title compound, C13H16ClN5O4, the imidazole ring is in a slight envelope conformation. The dihedral angle between the pyridine ring and the four essentially planar atoms [maximum deviation 0.015 (2) Å] of the imidazole ring is 80.8 (1)°. In, the crystal, weak C—H...O and C—H...N hydrogen bonds are present. In addition, there are weak π–π stacking interactions between symmetry-related pyridine rings with a centroid–centroid distance of 3.807 (1) Å.
Dichloridobis[(ferrocenylmethylidene)(furan-2-ylmethyl)amine-κN]palladium(II)
Authors: Motswainyana William M. , Onani Martin O. , Lalancette Roger A.
Published: March 2012

The title compound, [Fe2Pd(C5H5)2(C11H10NO)2Cl2], exhibits a square-planar geometry at the PdIIatom, which is determined by inversion-related chlorine and ferrocenylimine molecules across a center of symmetry. The ferrocenylimine moieties aretransto each other.
N-(2,6-Dimethylphenyl)-N′-propanoylthiourea
Authors: Yusof Mohd Sukeri Mohd , Mutalib Siti Fatimah Abdul , Arshad Suhana , Razak Ibrahim Abdul
Published: March 2012

In the title compound, C12H16N2OS, an intramolecular N—H...O hydrogen bond forms anS(6) ring motif. The propionylthiourea group is approximately planar [with a maximum deviation of 0.135 (2) Å] and forms a dihedral angle of 83.39 (7)° with the benzene ring. In the crystal, molecules are linked by pairs of N—H...S hydrogen bonds, forming centrosymmetric dimers and generatingR22(8) ring motifs.
5-Methoxy-1-[(5-methoxy-1H-indol-2-yl)methyl]-1H-indole
Authors: Attia Mohamed I. , El-Brollosy Nasser R. , Ghabbour Hazem A. , Arshad Suhana , Fun Hoong-Kun
Published: March 2012

In the title compound, C19H18N2O2, the two indole ring systems are essentially planar [maximum deviation = 0.015 (2) Å in both indole ring systems] and make a dihedral angle of 72.17 (7)° with each other. In the crystal, the molecules are linked into a zigzag chain along theaaxisviaN—H...O hydrogen bonds.
4-[Bis(4-fluorophenyl)methyl]piperazin-1-ium bis(trichloroacetate) 0.4-hydrate
Authors: Dayananda A. S. , Yathirajan H. S. , Flörke Ulrich
Published: March 2012

The title compound, C17H20F2N22+·2C2Cl3O2−·0.4H2O, has twofold protonated N atoms. The trichloroacetate anions each show one disordered Cl atom with site occupation factors of 0.945 (7):0.055 (7) 0.945 (8):0.055 (8). In the crystal, N—H...O, O(water)—H...O and O(water)—H...F interactions connect the components into a three-dimensional network.
PDK1 regulates the generation of oligodendrocyte precursor cells at an early stage of mouse telencephalic development
Authors: Watatani Kenji , Hirabayashi Yusuke , Itoh Yasuhiro , Gotoh Yukiko
Published: March 2012

During the development of the mouse telencephalon, multipotent neural precursor cells (NPCs) generate oligodendrocyte precursor cells (OPCs), progenitors restricted to the oligodendrocyte lineage, at various sites in a developmental stage‐dependent manner. Although substantial progress has been made in identifying the transcription factors that control the production of OPCs, the signaling pathways that regulate these transcription factors and the spatiotemporal pattern of OPC production have been only partially clarified. Here, we show that the serine–threonine kinase 3‐phosphoinositide‐dependent kinase 1 (PDK1) contributes to an early wave of OPC production in the developing mouse telencephalon. Ablation of PDK1 in NPCs resulted in a reduction in the number of OPCs positive for Sox10 and platelet‐derived growth factor receptor α (PDGFRα) within the neocortex and striatum at embryonic day (E) 15.5, but not at E18.5. Furthermore, pharmacological inhibition of phosphoinositide 3‐kinase (PI3K) or deletion of the PDK1 gene suppressed the generation of OPCs from NPCs induced by fibroblast growth factor (FGF) 2 in culture. These results implicate the PI3K–PDK1 pathway in the physiological regulation of OPC production in a developmental context‐dependent manner.
Microbial communities and their responses to simulated global change fluctuate greatly over multiple years
Authors: Gutknecht Jessica L. M. , Field Christopher B. , Balser Teri C.
Published: March 2012

We used microbial lipid analysis to analyze microbial biomass and community structure during 6 years of experimental treatment at the Jasper Ridge Global Change Experiment (JRGCE), a long‐term multi‐factor global change experiment in a California annual grassland. The microbial community fingerprint and specific biomarkers varied substantially from year to year, in both control and experimental treatment plots. Possible drivers of the variability included plant growth, soil moisture, and ambient temperature. Surprisingly, background variation in the microbial community was of a larger magnitude than even very significant treatment effects, and this variation appeared to constrain responses to treatment. Microbial communities were mostly not responsive or not consistently responsive to the experimental treatments. Both arbuscular mycorrhizal fungi biomarker abundance (16 : 1 ω5c) and the fungal to bacterial ratio were lower under nitrogen addition in most years. Bacterial lipid biomarker abundances (15 : 0 iso and 16 : 1 ω7c) were higher under nitrogen addition in 2002, the year of largest microbial biomass, suggesting that bacteria could respond more to nitrogen addition in years of better growth conditions. Nitrogen addition and warming led to an interactive effect on the Gram‐positive bacterial biomarker and the fungal to bacterial ratio. These patterns indicate that in California grassland ecosystems, microbial communities may not respond substantially to future changes in climate and that nitrogen deposition may be a determinant of the soil response to global change. Further, year‐to‐year variation in microbial growth or community composition may be important determinants of ecosystem response to global change.