bluuebunny/crossref_metadata_2025 huggingface dataset:
The Fe-Mn phosphate aplite ‘Silbergrube’ near Waidhaus, Germany: epithermal phosphate mineralization in the Hagendorf-Pleystein pegmatite province
Authors: Dill H. G. , Weber B. , Gerdes A. , Melcher F.
Published: March 2009

The Silbergrube Aplite (SA) in the Hagendorf-Pleystein Pegmatite District, near Waidhaus, Germany, is a mildly peraluminous NW-SE directed leucogranite dyke. It occurs in association with quartz dykes and aplitic metamorphic mobilizates in the NE Bavarian crystalline basement. The SA differs from other aplitic mobilizates in the region in having a less well developed strain-related mineral orientation and in containing only minor amounts of garnet and tourmaline. The aplitic metamorphic mobilizates and the SA are chemically and mmeralogically almost identical and yield the same age of formation of ∼302 Ma (stage I). The age of formation of the Hagendorf pegmatites seemingly post-dates the emplacement of the SA. The SA was emplaced at the boundary between fine-grained biotite granites and metamorphic country rocks within a zone of structural weakness, favouring the formation of disseminated late magmatic to hydrothermal mineralization of Li-bearing Fe-Mn phosphates (stages II and III). Brittle deformation along this zone was conducive to the faultbound Fe-Mn-Ca phosphates. Mineral telescoping is evident from the presence of Fe2+, Fe3+ and Mn2+ phosphates in fissures and vugs in a texturally highly variable host-rock environment (stage IV). This intimate intergrowth of phosphate minerals reflects contrasting physical and chemical conditions prevailing in a near-surface/ shallow epithermal S-deficient phosphate system (stage IV), similar to what is known from Cu-Au epithermal systems. The most recent mineral assemblages that formed under predominantly oxidizing conditions are correlated with the subtropical weathering during the Neogene which resulted in the formation of a peneplain truncating the SA and its country rocks (stage V). The SA is the root zone of the felsic aplitic-pegmatitic mobilizates in this region and is overprinted by an epithermal phosphate system.
Induction of type I IFN is required for overcoming tumor-specific T-cell tolerance after stem cell transplantation
Authors: Horkheimer Ian , Quigley Michael , Zhu Jiangao , Huang Xiaopei , Chao Nelson J. , Yang Yiping
Published: March 2009

Tumor-specific T-cell tolerance represents one major mechanism of tumor-induced immune evasion. Myeloablative chemotherapy with stem cell transplantation may offer the best chance of achieving a state of minimal residual disease and, thus, minimize tumor-induced immune evasion. However, studies have shown that tumor-specific T-cell tolerance persists after transplantation. Here, we showed that CD4+CD25+ regulatory T (TReg) cells play a critical role in tumor-specific CD8+ T-cell tolerance after transplantation. Removal of TReg cells from the donor lymphocyte graft did not overcome this tolerance because of rapid conversion of donor CD4+CD25− T cells into CD4+CD25+Foxp3+ TReg cells in recipients after transplantation, and depletion of TReg cells in recipients was necessary for the reversal of tumor-specific tolerance. These results suggest that strategies capable of overcoming T-cell tolerance in recipients are required to promote antitumor immunity after transplantation. Toward this goal, we showed that dendritic cell (DC) vaccines coadministered with the TLR9 ligand, CpG could effectively overcome tumor-specific tolerance, leading to significant prolongation of tumor-free survival after transplantation. We further showed that CpG-induced type I interferon was critical for the reversal of tumor-specific tolerance in vivo. Collectively, these results may suggest effective immunotherapeutic strategies for treating cancer after stem cell transplantation.
HIV-1 transactivator protein induction of suppressor of cytokine signaling-2 contributes to dysregulation of IFNγ signaling
Authors: Cheng Sherman M. , Li James C. B. , Lin San San , Lee Davy C. W. , Liu Li , Chen Zhiwei , Lau Allan S. Y.
Published: March 2009

HIV infection remains a worldwide threat. HIV-1 transactivator protein Tat is one of the retroviral proteins identified as a key immunomodulator in AIDS pathogenesis. Although the primary function of Tat is to regulate HIV-1 replication in the infected cell, it also dysregulates cytokine production resulting in perturbation of the host immune response and enhancement of the retrovirus survival. Because interferon-γ (IFNγ) is a pleiotropic cytokine with potent antiviral and immunoregulatory effects, we investigated whether Tat interferes with the IFNγ signal transduction in primary monocytes. We demonstrated that Tat impaired the IFNγ-receptor signaling pathway at the level of STAT1 activation, possibly via Tat-dependent induction of suppressor of cytokine signaling-2 (SOCS-2) activity. We delineated the inhibitory role of SOCS-2 in IFNγ signaling pathway by overexpression of exogenous SOCS-2 in HEK293 cell. The results showed that SOCS-2 suppressed the IFNγ-activated STAT1 phosphorylation and consequent IFNγ-regulated transcription of specific genes. To confirm the role of SOCS2 in the Tat-induced process, we demonstrated that SOCS-2 siRNA in human blood monocytes abrogated the Tat-dependent inhibition of IFNγ signaling. Our data suggested a possible mechanism implicating the role of SOCS-2 in mediating HIV-1–induced immune evasion and dysregulation of IFNγ signaling in primary human monocytes.
Novel autoantigens immunogenic in COPD patients
Authors: Leidinger Petra , Keller Andreas , Heisel Sabrina , Ludwig Nicole , Rheinheimer Stefanie , Klein Veronika , Andres Claudia , Hamacher Jürg , Huwer Hanno , Stephan Bernhard , Stehle Ingo , Lenhof Hans-Peter , Meese Eckart
Published: March 2009

Background

Chronic obstructive pulmonary disease (COPD) is a respiratory inflammatory condition with autoimmune features including IgG autoantibodies. In this study we analyze the complexity of the autoantibody response and reveal the nature of the antigens that are recognized by autoantibodies in COPD patients.

Methods

An array of 1827 gridded immunogenic peptide clones was established and screened with 17 sera of COPD patients and 60 healthy controls. Protein arrays were evaluated both by visual inspection and a recently developed computer aided image analysis technique. By this computer aided image analysis technique we computed the intensity values for each peptide clone and each serum and calculated the area under the receiver operator characteristics curve (AUC) for each clone and the separation COPD sera versus control sera.

Results

By visual evaluation we detected 381 peptide clones that reacted with autoantibodies of COPD patients including 17 clones that reacted with more than 60% of the COPD sera and seven clones that reacted with more than 90% of the COPD sera. The comparison of COPD sera and controls by the automated image analysis system identified 212 peptide clones with informative AUC values. By in silico sequence analysis we found an enrichment of sequence motives previously associated with immunogenicity.

Conclusion

The identification of a rather complex humoral immune response in COPD patients supports the idea of COPD as a disease with strong autoimmune features. The identification of novel immunogenic antigens is a first step towards a better understanding of the autoimmune component of COPD.
Dissecting the bacterial type VI secretion system by a genome wide in silico analysis: what can be learned from available microbial genomic resources?
Authors: Boyer Frédéric , Fichant Gwennaële , Berthod Jérémie , Vandenbrouck Yves , Attree Ina
Published: March 2009

Background

The availability of hundreds of bacterial genomes allowed a comparative genomic study of the Type VI Secretion System (T6SS), recently discovered as being involved in pathogenesis. By combining comparative and phylogenetic approaches using more than 500 prokaryotic genomes, we characterized the global T6SS genetic structure in terms of conservation, evolution and genomic organization.

Results

This genome wide analysis allowed the identification of a set of 13 proteins constituting the T6SS protein core and a set of conserved accessory proteins. 176 T6SS loci (encompassing 92 different bacteria) were identified and their comparison revealed that T6SS-encoded genes have a specific conserved genetic organization. Phylogenetic reconstruction based on the core genes showed that lateral transfer of the T6SS is probably its major way of dissemination among pathogenic and non-pathogenic bacteria. Furthermore, the sequence analysis of the VgrG proteins, proposed to be exported in a T6SS-dependent way, confirmed that some C-terminal regions possess domains showing similarities with adhesins or proteins with enzymatic functions.

Conclusion

The core of T6SS is composed of 13 proteins, conserved in both pathogenic and non-pathogenic bacteria. Subclasses of T6SS differ in regulatory and accessory protein content suggesting that T6SS has evolved to adapt to various microenvironments and specialized functions. Based on these results, new functional hypotheses concerning the assembly and function of T6SS proteins are proposed.
Regulation of callose synthase activity in situ in alamethicin-permeabilized Arabidopsisand tobacco suspension cells
Authors: Aidemark Mari , Andersson Carl-Johan , Rasmusson Allan G , Widell Susanne
Published: March 2009

Background

The cell wall component callose is mainly synthesized at certain developmental stages and after wounding or pathogen attack. Callose synthases are membrane-bound enzymes that have been relatively well characterized in vitro using isolated membrane fractions or purified enzyme. However, little is known about their functional properties in situ, under conditions when the cell wall is intact. To allow in situ investigations of the regulation of callose synthesis, cell suspensions of Arabidopsis thaliana (Col-0), and tobacco (BY-2), were permeabilized with the channel-forming peptide alamethicin.

Results

Nucleic acid-binding dyes and marker enzymes demonstrated alamethicin permeabilization of plasma membrane, mitochondria and plastids, also allowing callose synthase measurements. In the presence of alamethicin, Ca2+ addition was required for callose synthase activity, and the activity was further stimulated by Mg2+ Cells pretreated with oryzalin to destabilize the microtubules prior to alamethicin permeabilization showed significantly lower callose synthase activity as compared to non-treated cells. As judged by aniline blue staining, the callose formed was deposited both at the cell walls joining adjacent cells and at discrete punctate locations earlier described as half plasmodesmata on the outer walls. This pattern was unaffected by oryzalin pretreatment, showing a quantitative rather than a qualitative effect of polymerized tubulin on callose synthase activity. No callose was deposited unless alamethicin, Ca2+ and UDP-glucose were present. Tubulin and callose synthase were furthermore part of the same plasma membrane protein complex, as judged by two-dimensional blue native SDS-PAGE.

Conclusion

Alamethicin permeabilization allowed determination of callose synthase regulation and tubulin interaction in the natural crowded cellular environment and under conditions where contacts between the cell wall, the plasma membrane and cytoskeletal macromolecules remained. The results also suggest that alamethicin permeabilization induces a defense response mimicking the natural physical separation of cells (for example when intercellulars are formed), during which plasmodesmata are transiently left open.
Sunitinib treatment for patients with clear-cell metastatic renal cell carcinoma: clinical outcomes and plasma angiogenesis markers
Authors: Kontovinis Loukas F , Papazisis Konstantinos T , Touplikioti Panagiota , Andreadis Charalambos , Mouratidou Despoina , Kortsaris Alexandros H
Published: March 2009

Background

Sunitinib is a protein tyrosine kinase-inhibitor targeting VEGFR, c-kit and PDGFR. It has been approved for the treatment of metastatic renal-cell carcinoma and gastrointestinal stromal tumors. Although it has been shown to prolong disease-free and overall survival in renal-cell carcinoma patients, only 70% of the treated population receive a clinical benefit (CB) from the treatment. Markers that could predict clinical benefit to sunitinib would be an important aid in monitoring and following their treatment. We assessed the outcome and plasma proangiogenic factors in patients with metastatic renal cell carcinoma (mRCC) treated with sunitinib in our institution.

Methods

We have treated 42 patients with metastatic clear-cell renal carcinoma with sunitinib. Plasma concentrations of VEGF-A, sVEGFR2 and PDGF were determined by ELISA.

Results

At the time of analysis 39 patients were evaluable for response and 30 patients had obtained a clinical benefit (CB). Median progression-free survival was 268 days (8.93 months) and median overall survival was 487 days (16.23 months). Interestingly, disease stabilization or objective response resulted in comparable overall survival. Most treatment-related adverse events were of mild-to-moderate intensity with one treatment-related death. Plasma sVEGFR2 and PDGF levels had no predictive value. Fold-increase in plasma VEGF was significantly lower in patients that obtained a CB as compared to patients that progressed after two cycles of treatment. Plasma VEGF did not increase in patients with initial CB at the time of progression.

Conclusion

Sunitinib showed substantial activity in mRCC. Disease stabilization or objective response resulted in comparable overall survival and both outcomes should be considered positive. Fold-increase in plasma VEGF predicts for CB and could be a candidate marker. Progression after initial CB is not associated with elevated plasma VEGF, implying a different mechanism of resistance.
T regulatory cells: an overview and intervention techniques to modulate allergy outcome
Authors: Nandakumar Subhadra , Miller Christopher WT , Kumaraguru Uday
Published: March 2009

Dysregulated immune response results in inflammatory symptoms in the respiratory mucosa leading to asthma and allergy in susceptible individuals. The T helper type 2 (Th2) subsets are primarily involved in this disease process. Nevertheless, there is growing evidence in support of T cells with regulatory potential that operates in non-allergic individuals. These regulatory T cells occur naturally are called natural T regulatory cells (nTregs) and express the transcription factor Foxp3. They are selected in the thymus and move to the periphery. The CD4 Th cells in the periphery can be induced to become regulatory T cells and hence called induced or adaptive T regulatory cells. These cells can make IL-10 or TGF-b or both, by which they attain most of their suppressive activity. This review gives an overview of the regulatory T cells, their role in allergic diseases and explores possible interventionist approaches to manipulate Tregs for achieving therapeutic goals.
Gastric outlet obstruction due to adenocarcinoma in a patient with Ataxia-Telangiectasia syndrome: a case report and review of the literature
Authors: Otabor Iyore A , Abdessalam Shahab F , Erdman Steven H , Hammond Sue , Besner Gail E
Published: March 2009

Background

Ataxia-Telangiectasia syndrome is characterized by progressive cerebellar dysfunction, conjuctival and cutaneous telangiectasias, severe immune deficiencies, premature aging and predisposition to cancer. Clinical and radiographic evaluation for malignancy in ataxia-telangiectasia patients is usually atypical, leading to delays in diagnosis.

Case presentation

We report the case of a 20 year old ataxia-telangiectasia patient with gastric adenocarcinoma that presented as complete gastric outlet obstruction.

Conclusion

A literature search of adenocarcinoma associated with ataxia-telangiectasia revealed 6 cases. All patients presented with non-specific gastrointestinal complaints suggestive of ulcer disease. Although there was no correlation between immunoglobulin levels and development of gastric adenocarcinoma, the presence of chronic gastritis and intestinal metaplasia seem to lead to the development of gastric adenocarcinoma. One should consider adenocarcinoma in any patient with ataxia-telangiectasia who presents with non-specific gastrointestinal complaints, since this can lead to earlier diagnosis.
Identification of subtelomeric genomic imbalances and breakpoint mapping with quantitative PCR in 296 individuals with congenital defects and/or mental retardation
Authors: Auber Bernd , Bruemmer Verena , Zoll Barbara , Burfeind Peter , Boehm Detlef , Liehr Thomas , Brockmann Knut , Wilichowski Ekkehard , Argyriou Loukas , Bartels Iris
Published: March 2009

Background

Submicroscopic imbalances in the subtelomeric regions of the chromosomes are considered to play an important role in the aetiology of mental retardation (MR). The aim of the study was to evaluate a quantitative PCR (qPCR) protocol established by Boehm et al. (2004) in the clinical routine of subtelomeric testing.

Results

296 patients with MR and a normal karyotype (500–550 bands) were screened for subtelomeric imbalances by using qPCR combined with SYBR green detection. In total, 17 patients (5.8%) with 20 subtelomeric imbalances were identified. Six of the aberrations (2%) were classified as causative for the symptoms, because they occurred either de novo in the patients (5 cases) or the aberration were be detected in the patient and an equally affected parent (1 case). The extent of the deletions ranged from 1.8 to approximately 10 Mb, duplications were 1.8 to approximately 5 Mb in size. In 6 patients, the copy number variations (CNVs) were rated as benign polymorphisms, and the clinical relevance of these CNVs remains unclear in 5 patients (1.7%). Therefore, the overall frequency of clinically relevant imbalances ranges between 2% and 3.7% in our cohort.

Conclusion

This study illustrates that the qPCR/SYBR green technique represents a rapid and versatile method for the detection of subtelomeric imbalances and the option to map the breakpoint. Thus, this technique is highly suitable for genotype/phenotype studies in patients with MR/developmental delay and/or congenital defects.
Efficacy of Amitraz plus Metaflumizone for the treatment of canine demodicosis associated with Malassezia pachydermatis
Authors: Tarallo Viviana D , Lia Riccardo P , Sasanelli Mariateresa , Cafarchia Claudia , Otranto Domenico
Published: March 2009

This case reports the efficacy of metaflumizone plus amitraz spot-on formulation (ProMeris Duo®; Fort Dodge) against generalized demodectic mange. A two year-old male dog presented at clinical examination with poor general condition, diffused alopecia, crusted lesions, pruritus, skin scales and pustules.Demodexmites,Malassezia pachydermatisyeasts and bacteria were diagnosed. The dog was treated with cephalexin and topically with metaflumizone plus amitraz spot on formulation at two weeks intervals until two consecutive skin scrapings resulted negative for mites. The number of adult mites statistically decreased at follow-up with a reduction of approximately 42 and 94% at +14 and +28 days post treatment (p.t.) respectively. Nymphs and larvae could not be detected from +28 day p.t. while eggs were no longer present +42 day p.t. The dog was negative for both bacteria andM. pachydermatisat 14 days p.t., coinciding with improved general clinical conditions, recovering skin lesions and no further signs of pruritus. These results show that metaflumizone plus amitraz associated with the antibiotic therapy is highly effective for treating generalized demodectic mange and could also be effective toward controllingM. pachydermatisopportunistic infections.
The prevalence of the duodenal ulcer promoting gene (dupA) in Helicobacter pylori isolates varies by ethnic group and is not universally associated with disease development: a case-control study
Authors: Schmidt Heather-Marie A , Andres Sönke , Kaakoush Nadeem O , Engstrand Lars , Eriksson Lena , Goh Khean-Lee , Fock Kwong Ming , Hilmi Ida , Dhamodaran Subbiah , Forman David , Mitchell Hazel
Published: March 2009

Background

The putative H. pylori pathogenicity-associated factor dupA has been associated with IL-8 induction in vitro, and duodenal ulcer (DU) and gastric cancer (GC) development in certain populations, but this association is inconsistent between studies. We aimed to investigate dupA prevalence in clinical isolates from Sweden, Australia and from ethnic Chinese, Indians and Malays resident in Malaysia and Singapore and to examine the association with DU and GC. In addition we investigated the sequence diversity between isolates from these diverse groups and compared the level of IL-8 secretion in isolates possessing and lacking dupA.

Methods

PCR primers were designed to amplify over the C/T insertion denoting a continuous dupA. PCR products from 29 clinical isolates were sequenced and compared with sequences from three additional strains obtained from GenBank. Clinical isolates from 21 Malaysian patients (8 dupA-positive, 14 dupA-negative) were assessed for their ability to induce IL-8 in AGS cells in vitro. Statistical analysis was performed using Fisher's exact test.

Results

The prevalence of dupA in isolates from Swedish functional dyspepsia (FD) control patients (65%, 13/20) was higher and in isolates from Indian FD patients (7.1%, 3/42) was lower as compared with isolates from Chinese (28.9%, 13/49, P = 0.005, P = 0.025), Malay (35.7%, 5/14, P = 0.16, P = 0.018) and Australian (37.8%, 17/45, P = 0.060, P < 0.001) FD patients. dupA was associated with DU and GC development in Chinese with 62.5% (10/16) and 54.6% (12/22) of isolates possessing dupA respectively as compared with FD controls (28.9%) (P = 0.015, P = 0.032). No significant difference in prevalence of dupA between FD controls, DU (63.6%, 7/11) and GC (61.9%, 13/21) cases (P = 1.000) was observed in the Swedish population. Sequence analysis revealed a pairwise variation of 1.9% and all isolates possessed the C/T insertion. The average IL-8 induction was 1330 pg/mL for dupA-positive isolates and 1378 pg/mL for dupA-negative isolates.

Conclusion

Although dupA is highly conserved when present, we identified no consistent association between dupA and DU or GC development across the ethnic groups investigated, with the dupA prevalence in control groups varying significantly. Our results would suggest that in the clinical isolates investigated dupA is not associated with IL-8 induction in vitro.
Comparison of seismic upscaling methods: From sonic to seismic
Authors: Tiwary Dileep K. , Bayuk Irina O. , Vikhorev Alexander A. , Chesnokov Evgeni M.
Published: March 2009

The term “upscaling” used here means a prediction of elastic-wave velocities at lower frequencies from the velocities at higher frequencies. Three different methods of upscaling are considered, including the simple averaging, Backus averaging, and pair correlation function methods. These methods are applied to upscale the elastic-wave velocities measured at sonic frequencies ([Formula: see text], logging data) available for a well penetrating layers of gas-bearing shales and carbonates. As a result, a velocity distribution over depth for [Formula: see text] and [Formula: see text] is found in the frequency range of [Formula: see text]. The difference in the results obtained for a particular depth by the three theoretical methods in the surface seismic frequency bandwidth [Formula: see text] is [Formula: see text] for P-wave and [Formula: see text] for S-wave velocity. This difference is attributed to different theoretical backgrounds underlying these methods.
Instantaneous spectral attributes using scales in continuous-wavelet transform
Authors: Sinha Satish , Routh Partha , Anno Phil
Published: March 2009

Instantaneous spectral properties of seismic data — center frequency, root-mean-square frequency, bandwidth — often are extracted from time-frequency spectra to describe frequency-dependent rock properties. These attributes are derived using definitions from probability theory. A time-frequency spectrum can be obtained from approaches such as short-time Fourier transform (STFT) or time-frequency continuous-wavelet transform (TFCWT). TFCWT does not require preselecting a time window, which is essential in STFT. The TFCWT method converts a scalogram (i.e., time-scale map) obtained from the continuous-wavelet transform (CWT) into a time-frequency map. However, our method includes mathematical formulas that compute the instantaneous spectral attributes from the scalogram (similar to those computed from the TFCWT), avoiding conversion into a time-frequency spectrum. Computation does not require a predefined window length because it is based on the CWT. This technique optimally decomposes a multiscale signal. For nonstationary signal analysis, spectral decomposition from [Formula: see text] has better time-frequency resolution than STFT, so the instantaneous spectral attributes from CWT are expected to be better than those from STFT.
Statistical characterization of gas-patch distributions in partially saturated rocks
Authors: Toms-Stewart Julianna , Müller Tobias M. , Gurevich Boris , Paterson Lincoln
Published: March 2009

Reservoir rocks are often saturated by two or more fluid phases forming complex patterns on all length scales. The objective of this work is to quantify the geometry of fluid phase distribution in partially saturated porous rocks using statistical methods and to model the associated acoustic signatures. Based on X-ray tomographic images at submillimeter resolution obtained during a gas-injection experiment, the spatial distribution of the gas phase in initially water-saturated limestone samples are constructed. Maps of the continuous variation of the percentage of gas saturation are computed and associated binary maps obtained through a global thresholding technique. The autocorrelation function is derived via the two-point probability function computed from the binary gas-distribution maps using Monte Carlo simulations.The autocorrelation function can be approximated well by a single Debye correlation function or a superposition of two such functions. The characteristic length scales and show sensitivity (and hence significance) with respect to the percentage of gas saturation. An almost linear decrease of the Debye correlation length occurs with increasing gas saturation. It is concluded that correlation function and correlation length provide useful statistical information to quantify fluid-saturation patterns and changes in these patterns at the mesoscale. These spatial statistical measures are linked to a model that predicts compressional wave attenuation and dispersion from local, wave-induced fluid flow in randomly heterogeneous poroelastic solids. In particular, for a limestone sample, with flow permeability of 5 darcies and an average gas saturation of [Formula: see text], significant [Formula: see text]-wave attenuation is predicted at ultrasonic frequencies.
Control of convergent yolk syncytial layer nuclear movement in zebrafish
Authors: Carvalho Lara , Stühmer Jan , Bois Justin S. , Kalaidzidis Yannis , Lecaudey Virginie , Heisenberg Carl-Philipp
Published: March 2009

Nuclear movements play an essential role in metazoan development. Although the intracellular transport mechanisms underlying nuclear movements have been studied in detail, relatively little is known about signals from surrounding cells and tissues controlling these movements. Here, we show that, in gastrulating zebrafish embryos, convergence movements of nuclei within the yolk syncytial layer (YSL) are guided by mesoderm and endoderm progenitors migrating along the surface of the yolk towards the dorsal side of the developing gastrula. Progenitor cells direct the convergence movements of internal yolk syncytial nuclei (iYSN) by modulating cortical flow within the YSL in which the iYSN are entrained. The effect of mesoderm and endoderm progenitors on the convergence movement of iYSN depends on the expression of E-cadherin, indicating that adhesive contact between the cells and the YSL is required for the mesendoderm-modulated YSL cortical flow mediating nuclear convergence. In summary, our data reveal a crucial function for cortical flow in the coordination of syncytial nuclear movements with surrounding cells and tissues during zebrafish gastrulation.
Function of the epaxial muscles during trotting
Authors: Schilling Nadja , Carrier David R.
Published: March 2009

In mammals, the epaxial muscles are believed to stabilize the trunk during walking and trotting because the timing of their activity is not appropriate to produce bending of the trunk. To test whether this is indeed the case, we recorded the activity of the m. multifidus lumborum and the m. longissimus thoracis et lumborum at three different sites along the trunk (T13, L3, L6) as we manipulated the moments acting on the trunk and the pelvis in dogs trotting on a treadmill. Confirming results of previous studies, both muscles exhibited a biphasic and bilateral activity. The higher burst was associated with the second half of ipsilateral hindlimb stance phase, the smaller burst occurred during the second half of ipsilateral hindlimb swing phase. The asymmetry was noticeably larger in the m. longissimus thoracis et lumborum than in the m. multifidus lumborum. Although our manipulations of the inertia of the trunk produced results that are consistent with previous studies indicating that the epaxial muscles stabilize the trunk against accelerations in the sagittal plane, the responses of the epaxial muscles to manipulations of trunk inertia were small compared with their responses when moments produced by the extrinsic muscles of the hindlimb were manipulated. Our results indicate that the multifidus and longissimus muscles primarily stabilize the pelvis against(1) vertical components of hindlimb retractor muscles and (2) horizontal components of the hindlimb protractor and retractor muscles. Consistent with this, stronger effects of the manipulations were observed in the posterior sampling sites.
Mechanisms of food provisioning of honeybee larvae by worker bees
Authors: Heimken Christina , Aumeier Pia , Kirchner Wolfgang H.
Published: March 2009

Although it has clearly been demonstrated in previous studies that honeybees inspect their worker brood in a non-random fashion, it is still unclear which signals and cues worker bees use to monitor the nutritional state of their brood. Here we show that worker bees can recognize and quantify the larval food present in a brood cell olfactorily and identify potential mechanical signals produced by the brood. There is no evidence for additional chemical hunger signals produced by the larvae. However, the pattern of movement of larvae within their cells changes with their nutritional state and might provide additional information to nurse bees.
Morphological and functional classification of ion-absorbing mitochondria-rich cells in the gills of Mozambique tilapia
Authors: Inokuchi Mayu , Hiroi Junya , Watanabe Soichi , Hwang Pung-Pung , Kaneko Toyoji
Published: March 2009

To clarify ion-absorbing functions and molecular mechanisms of mitochondria-rich (MR) cells, Mozambique tilapia (Oreochromis mossambicus) were acclimated to artificial freshwaters with normal or lowered Na+ and/or Cl– concentration: (1) normal Na+/normal Cl– (control); (2) normal Na+/low Cl–; (3) low Na+/normal Cl–; and (4) low Na+/low Cl–. Scanning electron microscopy (SEM) revealed that concave and convex apical surfaces of MR cells predominantly developed in low Na+ and low Cl– waters, respectively, whereas small apical pits predominated in control conditions. Expression of Na+/H+exchanger-3 (NHE3) mRNA in the gills was increased in low Na+waters (low Na+/normal Cl– and low Na+/low Cl–), whereas that of Na+/Cl– cotransporter (NCC) expression was upregulated in low Cl–, but not in low Na+/low Cl–. Immunofluorescence staining showed that enlarged NHE3-immunoreactive apical regions were concave or flat in low Na+waters, whereas NCC-immunoreactive regions were enlarged convexly in low Cl– waters. Using SEM immunocytochemistry the distribution of NHE3/NCC was compared with SEM images obtained simultaneously, it was further demonstrated that NHE3 and NCC were confined to concave and convex apical surfaces, respectively. These results indicated that small apical pits developed into concave apical surfaces to facilitate Na+ uptake through NHE3, and into convex apical surfaces to enhance Na+/Cl– uptake through NCC. Our findings integrated morphological and functional classifications of ion-absorbing MR cells in Mozambique tilapia.
Bats go head-under-heels: the biomechanics of landing on a ceiling
Authors: Riskin Daniel K. , Bahlman Joseph W. , Hubel Tatjana Y. , Ratcliffe John M. , Kunz Thomas H. , Swartz Sharon M.
Published: March 2009

Bats typically roost head-under-heels but they cannot hover in this position, thus, landing on a ceiling presents a biomechanical challenge. To land, a bat must perform an acrobatic flip that brings the claws of the toes in contact with the ceiling and do so gently enough as to avoid injury to its slender hindlimbs. In the present study, we sought to determine how bats land,to seek a link between landing kinematics and ceiling impact forces, and to determine whether landing strategies vary among bat species. To do this, we measured the kinematics and kinetics of landing behaviour in three species of bats as they landed on a force-measuring platform (Cynopterus brachyotis, N=3; Carollia perspicillata, N=5; Glossophaga soricina, N=5). Kinematics were similar for all bats within a species but differed among species. C. brachyotisperformed four-point landings, during which body pitch increased until the ventral surface of the body faced the ceiling and the thumbs and hindlimbs simultaneously grasped the surface. Bats of the other two species performed two-point landings, whereby only the hindlimbs made contact with the ceiling. During these two-point landings, the hindlimbs were drawn up the side of the body to come in contact with the ceiling, causing simultaneous changes in body pitch, roll and yaw over the course of the landing sequence. Right-handed and left-handed forms of the two-point landing were observed, with individuals often switching back and forth between them among landing events. The four-point landing of C. brachyotis resulted in larger peak forces(3.7±2.4 body weights; median ± interquartile range) than the two-point landings of C. perspicillata (0.8±0.6 body weights)or G. soricina (0.8±0.2 body weights). Our results demonstrate that the kinematics and kinetics of landing vary among bat species and that there is a correlation between the way a bat moves its body when it lands and the magnitude of peak impact force it experiences during that landing. We postulate that these interspecific differences in impact force could result because of stronger selective pressure for gentle landing in cave-roosting(C. perspicillata, G. soricina) versus foliage-roosting(C. brachyotis) species.
Mechanical and biological consequences of repetitive loading: crack initiation and fatigue failure in the red macroalga Mazzaella
Authors: Mach Katharine J.
Published: March 2009

On rocky shores, wave-swept macroalgae experience dramatic and repeated wave-induced hydrodynamic forces. However, previous studies of macroalgal mechanics have shown that individual waves are not forceful enough to account for observed rates of breakage. Instead, fatigue may contribute to algal breakage, with damage accumulating over time in conditions of repeated loading. Here I examine the entire process of fatigue, from crack initiation to eventual specimen fracture, in the common red alga Mazzaella. Propensity for fatigue failure in laboratory tests varied with life history phase and species: at a given repeated loading stress, male gametophytes endured more loading cycles before breakage than tetrasporophytes, which in turn lasted longer than female gametophytes; likewise, M. splendenswithstood more loading cycles at a given repeated loading stress than M. flaccida. Fatigue failure begins with formation of cracks, the timing and location of which were assessed. Cracks formed, on average, after approximately 80–90% of cycles required for failure had passed, although crack timing varied with life history phase. Also, crack formation frequently occurred in association with endophytes and female gametophyte reproductive structures, suggesting a cost of endophyte infection and a tradeoff between reproduction and mechanical survival. Comparison between laboratory and field loading conditions provides robust confirmation that fatigue breaks fronds in natural M. flaccida populations. Large, female gametophyte fronds are predicted to be most susceptible to fatigue failure in the field, whereas small, male gametophyte fronds are least likely to break.
Development of Chiral Spiro Ligands for Metal-Catalyzed Asymmetric Reactions
Authors: Bajracharya Gan B , Arai Midori A , Koranne Priti S , Suzuki Takeyuki , Takizawa Shinobu , Sasai Hiroaki
Published: March 2009

This account focuses our works on the development of chiral spiro ligands bearing N-heterocycles as metal-coordinating units and their applications in the metal-catalyzed asymmetric reactions. The spiro bis(isoxazoline) ligands (SPRIXs), spiro bis(isoxazole) ligands, and spiro (isoxazole–isoxazoline) ligands were readily synthesized through intramolecular double nitrile oxide cycloaddition of the corresponding dioximes as a key step. An unprecedented activation of olefins was displayed by the PdII complexes of these chiral spiro ligands in the enantioselective oxidative cyclizations, for example; the asymmetric tandem cyclization of dialkenyl alcohol via oxy-palladation produced a bicyclic ether in excellent enantioselectivity and enantioselective version of the aminocarbonylation proceeded for the first time. Other hitherto known chiral ligands we examined failed to promote these reactions.
Roles of Molecular Wires between Fullerenes and Electron Donors in Photoinduced Electron Transfer
Authors: Ito Osamu , Yamanaka Ken-ichi
Published: March 2009

In the photoinduced intramolecular electron transfer events of donor–bridge–acceptor molecular systems, the bridges play important roles. In the first part of this account, we review charge separation and charge recombination of porphyrin–bridge–fullerene systems, in which the porphyrin acts as a photosensitizing electron donor, whereas the ground state of the C60 moiety acts as an electron acceptor. In such systems, the charge separation usually takes place through the LUMO of the bridges via a super-exchange mechanism and/or a hopping mechanism, depending on their relative LUMO energy levels. On the other hand, the charge recombination of the radical ion pairs usually takes place through the HOMO of the bridges. In the second part, research of charge separation via the excited state of fullerene through the HOMO of the bridges is reviewed. So far, very small damping factors have been reported for π-conjugated bridges such as oligophenyleneacetylenes, oligothiophenes, and oligothiophenevinylenes. On summarizing these results, it is revealed that switching from the super-exchange mechanism in short bridges to hopping mechanism in longer bridges is important to achieve long distance electron transfer through the bridges.
ONIOM Study of the Mechanism of the Enzymatic Hydrolysis of Biodegradable Plastics
Authors: Sakae Yoshitake , Matsubara Toshiaki , Aida Misako , Kondo Hidemasa , Masaki Kazuo , Iefuji Haruyuki
Published: March 2009

A cutinase-like enzyme (CLE), which is purified experimentally from the yeast Cryptococcus sp. strain S-2, has been recently found to degrade biodegradable plastics very efficiently. In this study, we theoretically examine the mechanism of hydrolysis of biodegradable plastics by the CLE by means of the ONIOM method. We optimize all the intermediates and the transition states involved in the considered enzymatic reaction and determine the energy surface of the entire catalytic cycle. The calculations show that the amino acid residues inside the pocket of the active site, Thr17 and Gln86, which stabilize the tetrahedral intermediates, and Gly115 in addition to Ser85, His180, and Asp165, which compose the catalytic triad, significantly contribute to the catalytic reaction. This is similar to the case of serine protease reported to date. Moreover, we have newly found that the energy barrier of the catalytic cycle is significantly lowered by the electronic effect of the OH group in the side-chain of Thr17 and bound water. The calculated potential energy surface of the reaction shows that the cleavage of the ester bond is a rate-determining step.
Structural Isomers of {MnII(L)2[AgI(CN)2]2} (L = 3-Methylpyridine or 4-Methylpyridine), Bilayer Structure with Binuclear Argentophilic Interaction and Interpenetrated Structure with 1D Chain Argentophilic Interaction; Synthesis, Crystal Structure, and Magnetic Properties
Authors: Kosone Takashi , Suzuki Yusuke , Kanadani Chikahide , Saito Toshiaki , Kitazawa Takafumi
Published: March 2009

New novel 2D network bimetallic MnIIAgI coordination compounds {MnII(L)2[AgI(CN)2]2}n (L = 3-methylpyridine (1) or 4-methylpyridine (2)) were synthesized and characterized by using single-crystal X-ray analysis and magnetic measurements. MnII ion in both complexes has MnN6 coordination with octahedral geometries, which are linked by a [AgI(CN)2]− unit at the equatorial plane to form a polymeric 2D sheet architecture. The two pyridine rings coordinate at the axial positions. However, coordination polymers for 1 and 2 are structural isomers. The structure of 1 comprises a parallel 2D array and the layers interact by pairs defining bilayers with strong binuclear argentophilic interaction, while 2 comprises a double interpenetration structure with 1D-chain weak argentophilic interaction. Furthermore, intermolecular C···C contacts in these complexes are significantly smaller than the sum of the van der Waals radius. Variable-temperature (2–300 K) magnetic susceptibility measurements of both the compounds have been performed to understand the possibility of spin transition in 1 and 2. However, the susceptibility data of 1 and 2 indicate the existence of high-spin (HS) state manganese(II) throughout the temperature range.
Honeycomb Sheet Structures Achieving High Electrical Conductivities in Alkyl-Substituted Thiazolium Bis(2-thioxo-1,3-dithiole-4,5-dithiolato)nickelate(III) Complex Salts
Authors: Tomiyama Etsuko , Tomono Kazuaki , Hashizume Daisuke , Wada Tatsuo , Miyamura Kazuo
Published: March 2009

A series of [Ni(dmit)2] (1) (dmit = 2-thioxo-1,3-dithiole-4,5-dithiolato) complex salts with 3,4-dimethylthiazolium (2), 2,3,4-trimethylthiazolium (3), and 3,4,5-trimethylthiazolium (4) cations (I, II, and III, respectively) were synthesized and characterized by single-crystal X-ray analysis and conductivity. The molecular structures of 1 were the same in all three complex salts. In the structure of I, the anions were arranged in hexagonal structures. Neighboring hexagons formed honeycomb sheet structures as the result of S···S interactions in the (001) plane. The sheets of the honeycomb structures were arranged along the c axis with translational symmetries that form columnar honeycomb channels along the direction. In the structures of II and III, honeycomb sheet structures were formed as in I. But in contrast to I, the relative position of the stacked sheets in II and III was slightly dislocated, forming zig-zag channels instead. The IR spectra of I, II, and III show that the C=C stretching band is slightly red-shifted to 1337–1339 from 1350 cm−1 for [Ni(dmit)2]−, caused by the partial oxidation of the anion. The measured values of the electrical conductivities were 0.20, 0.094, and 0.16 S cm−1 for I, II, and III, respectively. These high conductivities may be ascribed to the partially oxidation of the anion. The S···S interactions regulate the honeycomb sheet structure of the crystal and should work as conduction pathways effectively.
Structures and Magnetic Properties of Dinuclear Copper(II) Complexes Containing a Bulky Diamine Ligand, 1,2-Dipiperidinoethane
Authors: Arakawa-Itoh Machiko , Tokuman Kana , Mori Yukie , Kajiwara Takashi , Yamashita Masahiro , Fukuda Yutaka
Published: March 2009

A reaction of copper(II) perchlorate with a sterically hindered diamine, 1,2-dipiperidinoethane (dipe), yields two dinuclear complexes: di-μ-hydroxo dinuclear complex [{Cu(ClO4)(dipe)(μ-OH)}2] (1) and di-μ-alkoxo dinuclear complex [{Cu(ClO4)(dipe-O)}2] (2) (dipe-O− is 1-(2-piperidinoethyl)piperidin-3-olate which was newly obtained in this work). The structures of complexes 1 and 2 were confirmed by X-ray crystallography. Complex 2 is meso form containing (R)- and (S)-dipe-O−. Dipe-O− acts as a tridentate ligand with an N,N,O-donor set and bridges two copper(II) ions through the oxygen atom. The oxygen atom is incorporated into dipe from atmospheric molecular oxygen during the reaction of dipe with copper ion. The temperature dependences of χmT values were different between 1 and 2 depending on the bridging structures. Complex 1 shows ferromagnetic interaction and the value of 2J = 117 cm−1 is in agreement with that predicted from the ∠Cu–O–Cu bridging angle of 96.9°. Complex 2, the bridging angle of which is 100.59°, shows a strong antiferromagnetic interaction (−2J > 400 cm−1). The singlet–triplet energy gap for complex 2 was estimated from DFT calculation.
Photoresponse of GaN:ZnO Electrode on FTO under Visible Light Irradiation
Authors: Hashiguchi Hiroshi , Maeda Kazuhiko , Abe Ryu , Ishikawa Akio , Kubota Jun , Domen Kazunari
Published: March 2009

The photoelectrochemical properties of a GaN:ZnO solid solution coated as an electrode on conductive glass are investigated through measurement of voltammograms and current–time curves. The highest photocurrent was achieved by a GaN:ZnO sample with relatively high zinc concentration (Zn/Ga = 0.42) and small particle size, presumably due to more efficient electron transfer through the porous electrode. The electrode exhibits anodic photocurrent under visible light, indicating functionality as an n-type semiconductor electrode. The estimated band-gap position of GaN:ZnO is located at satisfactory potential for water splitting. The bottom of the conduction band is similar to that for GaN, while the top of the valence band is substantially higher than that of either GaN or ZnO. The evolution of H2 and O2 is confirmed during photoelectrolysis at +0.5 V vs. Ag/AgCl. The efficiency of photoelectrolysis is found to decrease with irradiation time due to degradation of the electrode.
Preparation of Iron-Containing Hectorite-Like Swelling Silicate
Authors: Ogawa Makoto , Matsutomo Takayuki , Okada Tomohiko
Published: March 2009

Iron-containing hectorite-like layered silicate was synthesized by the reaction of LiF, Mg(OH)2, colloidal silica, and FeCl3 in aqueous suspension at 100 °C for 2 days. From X-ray diffraction and infrared spectroscopic analysis, the formation of hectorite-like layered silicate was shown. Dimethyldioctadecylammonium and 1,1′-dimethyl-4,4′-bipyridinium (methyl viologen) ions were intercalated by cation-exchange reactions into the interlayer space of the iron-containing silicate. The intercalated amounts of both cationic species were larger compared to iron-free layered silicate, showing increase in the layer charge density of the silicate by the incorporation of iron(III). The increase in the layer charge was thought to be derived from isomorphous substitution of silicon(IV) by iron(III) in the silicate layer. The structural iron(III) was reduced to iron(II) by reaction with sodium dithionite, which was shown by a color-change (yellow to green) and the increase in the intercalated amounts of dimethyldioctadecylammonium and 1,1′-dimethyl-4,4′-bipyridinium ions.