bluuebunny/crossref_metadata_2025 huggingface dataset:
Photodynamics of a PV Trimer in High‐Viscosity Solvents and in PMMA Films: A New Insight into Energy Transfer versus Conformational Relaxation in Conjugated Polymers
Authors: Di Paolo Roberto E. , Burrows Hugh D. , Morgado Jorge , Maçanita António L.
Published: December 2008

Non‐Stokes–Einstein relaxation: The rate constant of conformational relaxation of a phenylenevinylene trimer (see picture) in different solvents is proportional to η−α, with α values decreasing from close to unity (low viscosity) to zero at sufficiently high solvent viscosity. This behaviour is attributed to the flexible methylbutyl side chains of the trimer, which partially screen the solvent friction.

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The p‐phenylenevinylene (PV) trimer (MBOPV3) was used to probe the effect of conformational relaxation on fluorescence decays of PV‐based polymers in the high solvent viscosity regime, from n‐hexadecane (3.45 cP at 293 K) to liquid paraffin (123 cP at 293 K), and in dilute poly(methyl methacrylate) (PMMA) solid films. The effect of intermolecular energy transfer and radiative transport on the fluorescence decays was also analysed by increasing the concentration of MBOPV3 in the PMMA films up to a pure MBOPV3 film. The rate constant of conformational relaxation was found to decrease with increasing solvent viscosity up to about 23 cP, but then becomes viscosity independent. The non‐Stokes–Einstein behaviour of kCR versus η over the whole viscosity range apparently results from the presence of the flexible methylbutyl side chains of MBOPV3, which partially screens the solvent friction. Conformational relaxation is not observed in very dilute PMMA solid films, where the fluorescence decay becomes single exponential. The decays become multi‐exponential again with an increase of MBOPV3 concentration in the PMMA films, but in this case it is due to intermolecular (interchain) energy transfer from less planar to more planar conformations of MBOPV3. In the pure MBOPV3 film, interchain energy transfer (radiative and non‐radiative) is the major process responsible for the observed (tetra‐exponential) decays.
Heterogeneous Photochemistry Relevant to the Troposphere: H2O2 Production during the Photochemical Reduction of NO2 to HONO on UV‐Illuminated TiO2 Surfaces
Authors: Beaumont Simon K. , Gustafsson R. Joel , Lambert Richard M.
Published: December 2008

Bleached out: The detection of an oxidized co‐product, hydrogen peroxide, during an important tropospheric reaction, combined with the detection of photoaccelerated surface nitrate formation (a competing pathway), allows a likely mechanism to be proposed (see figure) which explains previously observed experimental stoichiometries.

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How Does Your MOF Grow?
Authors: Morris Russell E.
Published: December 2008

Metal–organic frameworks (MOFs) are one of the most important classes of material in current chemistry. One open question is what is the mechanism of their crystal growth? In situ atomic force microscopy (see image) can be used to look at the surface of crystals as they grow, revealing a number of interesting features and giving clues to the molecular species that are important in the growth mechanism.

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A novel self‐consistent Nývlt‐like equation for metastable zone width determined by the polythermal method
Authors: Sangwal K.
Published: December 2008

Using a power‐law relation between three‐dimensional nucleation rate J and dimensionless supersaturation ratio S, and the theory of regular solutions to describe the temperature dependence of solubility, a novel Nývlt‐like equation of metastable zone width of solution relating maximum supercooling ΔTmax with cooling rate R is proposed in the form: ln(ΔTmax/T0) = Φ + β lnR, with intercept Φ = {(1–m)/m }ln(ΔHs/RGTlim) + (1/m)ln(f/KT0) and slope β = 1/m. Here T0 is the initial saturation temperature of solution in a cooling experiment, ΔHs is the heat of dissolution, RG is the gas constant, Tlim is the temperature of appearance of first nuclei, m is the nucleation order, and K is a new nucleation constant connected with the factor f defined as the number of particles per unit volume. It was found that the value of the term Φ for a system at saturation temperature T0 is essentially determined by the constant m and the factor f. The value of the factor f for a solute–solvent system at initial saturation temperature T0 is determined by solute concentration c0. Analysis of the experiment data for four different solute‐water systems according to the above equation revealed that: (1) the values of Φ and m for a system at a given temperature depend on the method of detection of metstable zone width, and (2) the value of slope β = 1/m for a system is practically a temperature‐independent constant characteristic of the system, but the value of Φ increases with an increase in saturation temperature T0, following an Arrhenius‐type equation with an activation energy Esat. The results showed, among others, that solubility of a solute is an important factor that determines the value of the nucleation order m and the activation energy Esat for diffusion. In general, the lower the solubility of a solute in a given solvent, the higher is the value of m and lower is the value of Esat. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Zinc‐finger paralogues tsh and tio are functionally equivalent during imaginal development in Drosophila and maintain their expression levels through auto‐ and cross‐negative feedback loops
Authors: Bessa José , Carmona Laura , Casares Fernando
Published: December 2008

teashirt (tsh) and tiptop (tio) are two Drosophila gene paralogues encoding zinc‐finger transcription factors. While tsh is an important developmental regulator, tio null individuals are viable and fertile. Here, we show that tio and tsh have coincident expression domains in the imaginal discs, the precursors of the adult body, and that both genes show similar functional properties when expressed ectopically. Furthermore, tio is able to rescue the development of tsh mutants, indicating that both genes are functionally equivalent during imaginal development. Of interest, the transcriptional regulation of tio and tsh is linked by a negative feedback loop. This mechanism might be required to maintain a tight control on the total levels of tio/tsh and could help explaining why Drosophila keeps an apparently dispensable gene. Developmental Dynamics 238:19–28, 2009. © 2008 Wiley‐Liss, Inc.
Transcriptional dynamics of endodermal organ formation
Authors: Sherwood Richard I. , Chen Tzong‐Yang Albert , Melton Douglas A.
Published: December 2008

Although endodermal organs including the liver, pancreas, and intestine are of significant therapeutic interest, the mechanism by which the endoderm is divided into organ domains during embryogenesis is not well understood. To better understand this process, global gene expression profiling was performed on early endodermal organ domains. This global analysis was followed up by dynamic immunofluorescence analysis of key transcription factors, uncovering novel expression patterns as well as cell surface proteins that allow prospective isolation of specific endodermal organ domains. Additionally, a repressive interaction between Cdx2 and Sox2 was found to occur at the prospective stomach–intestine border, with the hepatic and pancreatic domains forming at this boundary, and Hlxb9 was revealed to have graded expression along the dorsal–ventral axis. These results contribute to understanding the mechanism of endodermal organogenesis and should assist efforts to replicate this process using pluripotent stem cells. Developmental Dynamics 238:29–42, 2009. © 2008 Wiley‐Liss, Inc.
Expression of active Notch1 in avian coronary development
Authors: Yang Ke , Doughman Yong‐Qiu , Karunamuni Ganga , Gu Shi , Yang Yu‐Chung , Bader David M. , Watanabe Michiko
Published: December 2008

Notch1 is an important regulator of intercellular interactions in cardiovascular development. We show that the nuclear‐localized, cleaved and active form of Notch1, the Notch1 intracellular domain (N1ICD), appeared in mesothelial cells of the pro‐epicardium during epicardial formation at looped heart stages. N1ICD was also present in mesothelial cells and mesenchymal cells specifically within the epicardium at sulcus regions. N1ICD‐positive endothelial cells were detected within the nascent vessel plexus at the atrioventricular junction and within the compact myocardium (Hamburger and Hamilton stage [HH] 25–HH30). The endothelial cells expressing N1ICD were surrounded by N1ICD‐positive smooth muscle cells after coronary orifice formation (HH32–HH35), while N1ICD expression was absent in the mesenchymal and mesothelial cells surrounding mature coronary vessels. We propose that differential activation of the hypoxia/HIF1‐VEGF‐Notch pathway may play a role in epicardial cell interactions that promote epicardial epithelial/mesenchymal transition and coronary progenitor cell differentiation during epicardial development and coronary vasculogenesis in particularly hypoxic sulcus regions. Developmental Dynamics 238:162–170, 2009. © 2008 Wiley‐Liss, Inc.
The extracellular matrix protein TGFBI promotes myofibril bundling and muscle fibre growth in the zebrafish embryo
Authors: Kim H. Rosemary , Ingham Philip W.
Published: December 2008

The extracellular matrix protein Tgfbi has been shown to localise to myotendinous junctions in mouse and postulated to interact with the transmembrane protein Integrin α7β1, which, in parallel with the Dystrophin‐associated protein complex, is critical for linkage between the extracellular matrix and the cytoskeleton of muscle fibres. Here we use a GFP‐tagged form of Tgfbi to analyse its distribution in the developing skeletal muscle of the zebrafish embryos and antisense morpholino oligonucleotides to investigate the function of the endogenous protein. We find that although tagged Tgfbi accumulates at the myosepta, the attachment of muscle fibres to the myosepta is established and maintained normally in morphant embryos; however, the fibres show a marked reduction in their growth and a disruption of their myofibril bundles. Developmental Dynamics 238:56–65, 2009. © 2008 Wiley‐Liss, Inc.
Identification and characterization of two zebrafish nectin‐1 genes that are differentially expressed in the developing eye and brain
Authors: Helvik Jon Vidar , Rødahl Eyvind , Drivenes Øyvind , Haarr Lars
Published: December 2008

Nectins are cell adhesion molecules of the immunoglobulin type that play important roles in the development of the nervous system. We have characterized two paralogous zebrafish nectin‐1 genes, nectin‐1a and nectin‐1b, that differ in expression. Nectin‐1a expression is first found in the anterior neural keel and later in the optic cup. In the retina, nectin‐1a appears in the outer part and extends inwards, while nectin‐1b starts in the inner part and spreads outwards. Only nectin‐1a was detected in the cornea, the lens, and in the region of photoreceptor cell differentiation in the retina. Both genes were expressed in ganglion cells and inner nuclear neurons. In the brain, nectin‐1a was restricted to the epiphysis and a cluster of cells in the posterior hindbrain, whereas nectin‐1b was found in several brain areas. Zebrafish may, therefore, be a useful model for identifying different functions of nectin‐1 in the developing eye and nervous system. Developmental Dynamics 238:43–55, 2009. © 2008 Wiley‐Liss, Inc.
Many ribosomal protein mutations are associated with growth impairment and tumor predisposition in zebrafish
Authors: Lai Kevin , Amsterdam Adam , Farrington Sarah , Bronson Roderick T. , Hopkins Nancy , Lees Jacqueline A.
Published: December 2008

We have characterized 28 zebrafish lines with heterozygous mutations in ribosomal protein (rp) genes, and found that 17 of these are prone to develop zebrafish malignant peripheral nerve sheath tumors (zMPNST). Heterozygotes from the vast majority of tumor‐prone rp lines were found to be growth‐impaired, though not all growth‐impaired rp lines were tumor‐prone. Significantly, however, the rp lines with the greatest incidence of zMPNSTs all displayed a growth impairment. Furthermore, heterozygous cells from one tumor‐prone rp line were out‐competed by wild‐type cells in chimeric embryos. The growth impairment resulting from heterozygosity for many rp genes suggests that a global defect in protein translation exists in these lines, raising the possibility that a translation defect that precedes tumor development is predictive of tumorigenesis. Developmental Dynamics 238:76–85, 2009. © 2008 Wiley‐Liss, Inc.
Cloning and expression analysis of the anterior parahox genes, Gsh1 and Gsh2 from Xenopus tropicalis
Authors: Illes Jean C. , Winterbottom Emily , Isaacs Harry V.
Published: December 2008

Gsx class proteins are members of the ParaHox homeodomain transcription factor family with conserved roles in specification and patterning of the nervous system. We report the cloning of two Gsx genes, Gsh1 and Gsh2, from the frog Xenopus tropicalis. We demonstrate the existence of a single, intact Xenopus ParaHox cluster, containing Gsh1, Pdx, and Cdx2, plus three degenerate clusters containing Gsh2, Cdx1, and Cdx4. Anterior expression boundaries of genes from the intact ParaHox cluster are co‐linear with respect to their genomic organization. We show that Gsh1 and Gsh2 exhibit complex, overlapping patterns of expression within the anterior nervous system from open neural plate stages. We also find that expression of Gsh2, Nkx6, and Msx1 across the medio‐lateral axis of the amphibian neural plate is strikingly similar to that of related genes in the Drosophila neuroectoderm. These findings provide further evidence for a conserved pathway regulating dorso‐ventral patterning in the Bilateria. Developmental Dynamics 238:194–203, 2009. © 2008 Wiley‐Liss, Inc.
The unfulfilled/DHR51 gene of Drosophila melanogaster modulates wing expansion and fertility
Authors: Sung Carl , Wong Laura E. , Chang Sen Lauren Q. , Nguyen Elizabeth , Lazaga Nelson , Ganzer Gavin , McNabb Susan L. , Robinow Steven
Published: December 2008

This is the first functional analysis in Drosophila of unfulfilled (unf; DHR51), the NR2E3 nuclear receptor superfamily ortholog of C. elegans fax‐1 and human PNR. Both fax‐1 and PNR mutations disrupt developmental events in a limited number of neurons, resulting in behavioral or sensory deficits. An analysis of two independent unf alleles revealed that unf mutants are characterized by one of two phenotypes. A proportion of the mutants eclosed but failed to expand their wings and were poorly coordinated. The remainder completed wing expansion but displayed severely compromised fertility. Consistent with the restricted neural expression of fax‐1 and PNR, unf expression was detected in situ only in mushroom body neurons and a small number of other cells of the central nervous system (CNS). These data support the hypothesis that the wing expansion failure and the compromised fertility of unf mutants are the result of underlying neural defects. Developmental Dynamics 238:171–182, 2009. © 2008 Wiley‐Liss, Inc.
RNA profiling of FAC‐sorted neurons from the developing zebrafish spinal cord
Authors: Cerda Gustavo A. , Hargrave Murray , Lewis Katharine E.
Published: December 2008

In this report, we describe a successful protocol for isolating and expression‐profiling live fluorescent‐protein‐labelled neurons from zebrafish embryos. As a proof‐of‐principle for this method, we FAC‐sorted and RNA‐profiled GFP‐labelled spinal CiA interneurons and compared the expression profile of these cells to those of post‐mitotic spinal neurons in general and to all trunk cells. We show that RNA of sufficient quality and quantity to uncover both expected and novel transcription profiles via Affymetrix microarray analysis can be extracted from 5,700 to 20,000 FAC‐sorted cells. As part of this study, we also further confirm the genetic homology of mammalian and zebrafish V1 interneurons, by demonstrating that zebrafish V1 cells (CiAs) express genes that encode for the transcription factors Lhx1a and Lhx5. This protocol for dissociating, sorting and RNA‐profiling neurons from organogenesis‐stage zebrafish embryos should also be applicable to other developing organs and tissues and potentially other model organisms. Developmental Dynamics 238:150–161, 2009. © 2008 Wiley‐Liss, Inc.
Podoplanin deficient mice show a rhoa‐related hypoplasia of the sinus venosus myocardium including the sinoatrial node
Authors: Mahtab Edris A.F. , Vicente‐Steijn Rebecca , Hahurij Nathan D. , Jongbloed Monique R.M. , Wisse Lambertus J. , DeRuiter Marco C. , Uhrin Pavel , Zaujec Jan , Binder Bernd R. , Schalij Martin J. , Poelmann Robert E. , Gittenberger‐De Groot Adriana C.
Published: December 2008

We investigated the role of podoplanin in development of the sinus venosus myocardium comprising the sinoatrial node, dorsal atrial wall, and primary atrial septum as well as the myocardium of the cardinal and pulmonary veins. We analyzed podoplanin wild‐type and knockout mouse embryos between embryonic day 9.5–15.5 using immunohistochemical marker podoplanin; sinoatrial‐node marker HCN4; myocardial markers MLC‐2a, Nkx2.5, as well as Cx43; coelomic marker WT‐1; and epithelial‐to‐mesenchymal transformation markers E‐cadherin and RhoA. Three‐dimensional reconstructions were made and myocardial morphometry was performed. Podoplanin mutants showed hypoplasia of the sinoatrial node, primary atrial septum, and dorsal atrial wall. Myocardium lining the wall of the cardinal and pulmonary veins was thin and perforated. Impaired myocardial formation is correlated with abnormal epithelial‐to‐mesenchymal transformation of the coelomic epithelium due to up‐regulated E‐cadherin and down‐regulated RhoA, which are controlled by podoplanin. Our results demonstrate an important role for podoplanin in development of sinus venosus myocardium. Developmental Dynamics 238:183–193, 2009. © 2008 Wiley‐Liss, Inc.
Short limbs, cleft palate, and delayed formation of flat proliferative chondrocytes in mice with targeted disruption of a putative protein kinase gene, Pkdcc (AW548124)
Authors: Imuta Yu , Nishioka Noriyuki , Kiyonari Hiroshi , Sasaki Hiroshi
Published: December 2008

During long bone development, round proliferative chondrocytes (RPCs) differentiate into flat proliferative chondrocytes (FPCs), and then into hypertrophic chondrocytes (HCs). FPCs and HCs support longitudinal bone growth. Here we show that a putative protein kinase gene, Pkdcc (AW548124), is required for longitudinal bone growth. We originally found Pkdcc expressed in the head organizer, but it is also expressed throughout embryogenesis and in various adult tissues. Pkdcc−/− embryos had no head organizer‐related defects, but showed various morphological abnormalities at birth, including short limbs, cleft palate, sternal dysraphia, and shortened intestine. In the long bones of the limbs, only the mineralized regions were shortened, and the cartilage length was normal. In the humerus, Pkdcc was strongly expressed in the early FPCs, and FPC and HC formation was delayed in Pkdcc−/− mutants. Together, these data indicate that Pkdcc encodes a protein kinase that is required for the appropriate timing of FPC differentiation. Developmental Dynamics 238:210–222, 2009. © 2008 Wiley‐Liss, Inc.
Nasal embryonic LHRH factor plays a role in the developmental migration and projection of gonadotropin‐releasing hormone 3 neurons in zebrafish
Authors: Palevitch Ori , Abraham Eytan , Borodovsky Natalya , Levkowitz Gil , Zohar Yonathan , Gothilf Yoav
Published: December 2008

The initiation of puberty and the functioning of the reproductive system depend on proper development of the hypophysiotropic gonadotropin‐releasing hormone (GnRH) system. One critical step in this process is the embryonic migration of GnRH neurons from the olfactory area to the hypothalamus. Using a transgenic zebrafish model, Tg(gnrh3:EGFP), in which GnRH3 neurons and axons are fluorescently labeled, we investigated whether zebrafish NELF is essential for the development of GnRH3 neurons. The zebrafish nelf cDNA was cloned and characterized. During embryonic development, nelf is expressed in GnRH3 neurons and in target sites of GnRH3 projections and perikarya, before the initiation of their migration. Nelf knockdown resulted in a disruption of the GnRH3 system which included absence or misguiding of GnRH3 axonal outgrowth and incorrect or arrested migration of GnRH3 perikarya. These results suggest that Nelf is an important factor in the developmental migration and projection of GnRH3 neurons in zebrafish. Developmental Dynamics 238:66–75, 2009. © 2008 Wiley‐Liss, Inc.
Samba, a Xenopus hnRNP expressed in neural and neural crest tissues
Authors: Yan Chao Yun Irene , Skourides Paris , Chang Chenbei , Brivanlou Ali
Published: December 2008

RNA binding proteins regulate gene expression at the posttranscriptional level and play important roles in embryonic development. Here, we report the cloning and expression of Samba, a Xenopus hnRNP that is maternally expressed and persists at least until tail bud stages. During gastrula stages, Samba is enriched in the dorsal regions. Subsequently, its expression is elevated only in neural and neural crest tissues. In the latter, Samba expression overlaps with that of Slug in migratory neural crest cells. Thereafter, Samba is maintained in the neural crest derivatives, as well as other neural tissues, including the anterior and posterior neural tube and the eyes. Overexpression of Samba in the animal pole leads to defects in neural crest migration and cranial cartilage development. Thus, Samba encodes a Xenopus hnRNP that is expressed early in neural and neural crest derivatives and may regulate crest cells migratory behavior. Developmental Dynamics 238:204–209, 2009. © 2008 Wiley‐Liss, Inc.
Sdmg1 is a component of secretory granules in mouse secretory exocrine tissues
Authors: Best Diana , Adams Ian R.
Published: December 2008

Sdmg1 is a conserved eukaryotic transmembrane protein that is mainly expressed in the gonads where it may have a role in mediating signaling between somatic cells and germ cells. In this study we demonstrate that secretory exocrine cells in the pancreas, salivary gland, and mammary gland also express Sdmg1. Furthermore, we show that Sdmg1 expression is up‐regulated during pancreas development when regulated secretory granules start to appear, and that Sdmg1 colocalizes with secretory granule markers in adult pancreatic acinar cells. In addition, we show that Sdmg1 co‐purifies with secretory granules during subcellular fractionation of the pancreas and that Sdmg1 and the secretory granule marker Vamp2 are localized to distinct subdomains in the secretory granule membrane. These data suggest that Sdmg1 is a component of regulated secretory granules in exocrine secretory cells and that the developmental regulation of Sdmg1 expression is related to a role for Sdmg1 in post‐Golgi membrane trafficking. Developmental Dynamics 238:223–231, 2009. © 2008 Wiley‐Liss, Inc.
Muscular dystrophy candidate gene FRG1 is critical for muscle development
Authors: Hanel Meredith L. , Wuebbles Ryan D. , Jones Peter L.
Published: December 2008

The leading candidate gene responsible for facioscapulohumeral muscular dystrophy (FSHD) is FRG1 (FSHD region gene 1). However, the correlation of altered FRG1 expression levels with disease pathology has remained controversial and the precise function of FRG1 is unknown. Here, we carried out a detailed analysis of the normal expression patterns and effects of FRG1 misexpression during vertebrate embryonic development using Xenopus laevis. We show that frg1 is expressed in and essential for the development of the tadpole musculature. FRG1 morpholino injection disrupted myotome organization and led to inhibited myotome growth, while elevated FRG1 led to abnormal epaxial and hypaxial muscle formation. Thus, maintenance of normal FRG1 levels is critical for proper muscle development, supportive of FSHD disease models whereby misregulation of FRG1 plays a causal role underlying the pathology exhibited in FSHD patients. Developmental Dynamics 238:1502–1512, 2009. © 2008 Wiley‐Liss, Inc.
Fibroblast growth factor 9 signaling inhibits airway smooth muscle differentiation in mouse lung
Authors: Yi Lan , Domyan Eric T. , Lewandoski Mark , Sun Xin
Published: December 2008

In mammalian lungs, airway smooth muscle cells (airway SMCs) are present in the proximal lung adjacent to bronchi and bronchioles, but are absent in the distal lung adjacent to terminal sacs that expand during gas exchange. Evidence suggests that this distribution is essential for the formation of a functional respiratory tree, but the underlying genetic mechanism has not been elucidated. In this study, we test the hypothesis that fibroblast growth factor 9 (Fgf9) signaling is essential to restrict SMC differentiation to the proximal lung. We show that loss of Fgf9 or conditional inactivation of Fgf receptors (Fgfr) 1 and 2 in mouse lung mesenchyme results in ectopic SMCs. Our data support a model where FGF9 maintains a SMC progenitor population by suppressing differentiation and promoting growth. This model also represents our findings on the genetic relationship between FGF9 and sonic hedgehog (SHH) in the establishment of airway SMC pattern. Developmental Dynamics 238:123–137, 2009. © 2008 Wiley‐Liss, Inc.
The embryonic expression patterns and the knockdown phenotypes of zebrafish ADP‐ribosylation factor‐like 6 interacting protein gene
Authors: Huang Hsing‐Yen , Dai En‐Sheng , Liu Jeng‐Ting , Tu Chi‐Tung , Yang Tzu‐Ching , Tsai Huai‐Jen
Published: December 2008

ADP‐ribosylation factor‐like 6 (Arl6) mutation is linked to human disease and Arl6 interacts with Arl6 interacting protein (Arl6ip). However, the expression pattern and function of Arl6ip during embryogenesis are unknown. To confirm whether abnormal Arl6ip function might result in embryonic defects in zebrafish, we examined the expression patterns of arl6ip during embryogenesis, and they were maternally expressed and exhibited in the brain, optic primordia, hypochord, spinal cord, myotome, heart, fin‐bud, kidney, trunk, and retina. Knockdown of Arl6ip revealed the following phenotypic defects: microphthalmia, disorganized pigment pattern, flat head, defective tectum, deficient pectoral fins, abnormal pneumatic duct, pericardial edema, and deformed trunk. Particularly, histological dissection of the retinae of arl6ip‐morphants revealed that neuronal differentiation is severely delayed, resulting in no formation of retinal layers. We further confirmed that opsins of arl6ip‐morphants were not transcribed. Based on this evidence, Arl6ip may play important roles in zebrafish ocular, heart, and fin‐bud development. Developmental Dynamics 238:232–240, 2009. © 2008 Wiley‐Liss, Inc.
Osterix‐mCherry transgenic medaka for in vivo imaging of bone formation
Authors: Renn Joerg , Winkler Christoph
Published: December 2008

Intramembranous and chondral bone formation by osteoblasts is found in all vertebrates. The genetic network controlling osteoblast differentiation is highly conserved and regulated by a small number of key factors, including the zinc‐finger transcription factor Osterix. Expression analysis of osterix in the teleost model medaka revealed a highly restricted expression in skeletal regions. For in vivo imaging, we generated transgenic medaka expressing mCherry under control of the osterix promoter. We show that the transgene becomes expressed in early osteoblasts, which have not yet mineralized bone matrix, and remains high in matured and mineralizing osteoblasts. Life imaging of transgenic larvae provided insight into the appearance and behavior of early osteoblasts during development of the teleost cranium, vertebrae, and caudal fin. In summary, osterix‐mCherry transgenic medaka enable us to analyze osteoblasts during different maturation phases in vivo and represent a unique tool to study osteoblast behavior in vertebrate embryos and adults. Developmental Dynamics 238:241–248, 2009. © 2008 Wiley‐Liss, Inc.
Requirement for a core 1 galactosyltransferase in the Drosophila nervous system
Authors: Lin Yuh‐Ru , Reddy B.V.V.G. , Irvine Kenneth D.
Published: December 2008

A Drosophila embryo triply stained to reveal neurons, hemocytes, and O‐glycosylation. The O‐glycosylation is required for nervous system morphogenesis. See Lin et al., Developmental Dynamics 237:3703‐3714. Developmental Dynamics, 2009. © 2008 Wiley‐Liss, Inc.
A Carbazole‐Containing Difunctional RuII Complex That Functions as a pH‐Induced Emission Switch and an Efficient Sensitizer for Solar Cells
Authors: Fan Su‐Hua , Wang Ke‐Zhi , Yang Wei‐Chun
Published: December 2008

A heteroleptic ruthenium(II) complex of [Ru(Hecip)(Hdcbpy) (NCS)2]–·[N(C4H9)4]+ (where Hecip = 2‐(9‐ethyl‐9H‐carbazol‐3‐yl)‐1H‐imidazo[4,5‐f][1,10]phenanthroline and Hdcbpy = monodeprotonated 2,2′‐bipyridyl‐4,4′‐dicarboxylic acid) has been synthesized and characterized by elementary analysis, cyclic voltammetry, MALDI‐TOF mass spectrometry, and 1H NMR, IR, UV/Vis absorption, and emission spectroscopy. The ground‐ and excited‐state acid–base properties of the complex have been studied by means of UV/Vis absorption spectrophotometric and spectrofluorimetric titrations in a Britton–Robinson/DMF (v/v, 4:1) buffer solution. The complex was found to act as pH‐induced off‐on‐off/on‐off‐on‐off‐type emission switch, when excited at 530/470 nm, with a protonation/deprotonation reaction taking place near the physiological pH range. The performance of the complex‐sensitized TiO2 nanocrystalline solar cell with 0.05 M I2 and 0.5 M LiI in 50 % acetonitrile and 50 % propylene carbonate (PC) as the electrolyte solution and a platinum film as the counter electrode has also been studied, and was compared to that of the cis‐[Ru(H2dcbpy)2(NCS)2] (N3)‐sensitized solar cell under the same experimental conditions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Construction and Photoluminescence of Monophase Hybrid Materials Derived from a Urea‐Based Bis‐Silylated Bipyridine
Authors: Li Huanrong , Lin Nana , Wang Yige , Feng Yu , Gan Quanying , Zhang Hongjie , Dong Qinglin , Chen Yuhuan
Published: December 2008

A urea‐based bis‐silylated bipyridine ligand derived from 4,4′‐diamino‐2,2′‐bipyridine has been prepared. Organic–inorganic hybrid materials with a high loading of lanthanide 2,2‐bipyridine moieties were obtained by using the silylated bipyridine as the only siloxane network precursor in the presence of lanthanide ions (or lanthanide complexes). The in‐situ formation of lanthanide complexes from lanthanide ions and the silylated bipyridine during the sol–gel processing was confirmed by the luminescence behavior of the obtained hybrid materials and that of the corresponding pure lanthanide complex [Ln(bpy)2Cl3·2H2O]. Tris(2‐thenoyltrifluoroacetonato)europium(III) dihydrate complexes were coupled to the hybrid materials via adduct formation with the nitrogen atoms from bis‐silylated bipyridine, and the coordinated water molecules were expelled from the first coordination sphere of the lanthanide(III) ion as revealed by the much longer lifetime of the hybrid material compared with that of the pure tris(2‐thenoyltrifluoroacetonato)europium(III). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Oligonucleotide Duplexes with Tethered Photoreactive Ruthenium(II) Complexes: Influence of the Ligands and Their Linker on the Photoinduced Electron Transfer and Crosslinking Processes of the Two Strands
Authors: Deroo Stéphanie , Le Gac Stéphane , Ghosh Sumana , Villien Mathilde , Gerbaux Pascal , Defrancq Eric , Moucheron Cécile , Dumy Pascal , Kirsch‐De Mesmaeker Andrée
Published: December 2008

The photoreactivity of new RuII‐oligonucleotide conjugates is investigated in the presence of their complementary strands. The goal is to determine the origins of different effects of parameters that control the photocrosslinking process of the two strands. Therefore, two RuII compounds, either [Ru(tap)3]2+or [Ru(tap)2phen]2+ (tap = 1,4,5,8‐tetraazaphenanthrene, phen = 1,10‐phenanthroline) with different oxidation powers, were tethered with different linkers to either the 5′‐ or 3′‐phosphate end of the probe strand before hybridization with the complementary strand. These systems were studied by time‐resolved emission spectroscopy, UV/Vis absorption experiments, PAGE and MS (ESI) analyses. The best yields of photocrosslinking (45 %) obtained with [Ru(tap)3]2+ tethered to the 3′‐position are due to (i) a higher oxidation power of the complex and (ii) its attachment at the 3′‐position. Indeed, this tethering favours the interaction of the Ru compound with the duplex and, therefore, inhibits its photodechelation. This work allows better design of sequence‐specific DNA photodamaging agents prior to biological applications.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Reactions of 2,2‐Diphenyl‐1‐picrylhydrazyl (DPPH) with Two Syringylic Phenols or One Aroxide Derivative
Authors: Hristea Elena N. , Covaci‐Cîmpeanu Irina C. , Ioniţaǎ Gabriela , Ioniţaǎ Petre , Draghici Constantin , Caǎproiu Miron T. , Hillebrand Mihaela , Constantinescu Titus , Balaban Alexandru T.
Published: December 2008

The reactions between excess 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and either 4‐hydroxy‐3,5‐dimethoxybenzaldehyde (syringaldehyde, 1) or methyl 4‐hydroxy‐3,5‐dimethoxybenzoate (methyl syringate, 2) afford different products from those obtained with the corresponding aroxide (3) of 1. In the former case (with the free phenols) the aryloxy (syringyl) group substitutes the 4‐nitro group of DPPH, yielding dinitro products 7 and 8 (new stable free radicals) and 9 and 10 (corresponding hydrazines), whereas in the latter case (with the sodium aroxide 3) the aryloxy (syringyl) group substitutes one of the phenyl groups of DPPH in the para position, forming trinitro products 14 (new stable free radical) and 15 (corresponding hydrazine). Accompanying products were isolated by TLC and identified by their 1H NMR, 13C NMR, UV/Vis, and EPR spectra. The reaction mechanisms involving hydrazyl and aroxyl free radicals are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Is the Elimination of Lithium Alkoxide Easier from a Vinyllithium or from an Alkyllithium? A DFT Study of the Aromatization of 3‐Vinylidene‐2,3‐dihydrobenzofurans to Benzofurans
Authors: Fressigné Catherine , Girard Anne‐Lise , Durandetti Muriel , Maddaluno Jacques
Published: December 2008

A possible mechanism for the last step of a cascade transformation in which lithiated propargyl ether 2 is converted into 3‐vinylbenzofuran 7 is described. Starting from the lithiated E olefin 3A, our DFT computations show that the final departure of lithium alkoxide is not easy unless an excess of nBuLi, the importance of which has been noted experimentally, prompts a second deprotonation. This theoretical evidence was further supported by a complementary experiment involving dihydrobenzofuran 10. The deprotonation of this latter compound by nBuLi elicits a spontaneous syn elimination, probably through monolithiated intermediates 10Li and 6, regioisomers of 3A. The activation barriers calculated for these various transformations indicate that the elimination of lithium methoxide from β‐lithiated acetals requires around 10 times more energy when the precursor is a vinyllithium rather than an alkyllithium. A route passing through a sigmatropic rearrangement was also considered. This triggers the elimination of a molecule of methanol, which acts as a shuttle to transfer a proton from the heterocycle to the vinyl position. However, with the set of reaction coordinates considered, this mechanism passes through high‐lying activation barriers unless the conformation of the exocyclic double bond in 3 is Z (isomer 3B).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
An Efficient Molybdenum(VI)‐Catalyzed Direct Substitution of Allylic Alcohols with Nitrogen, Oxygen, and Carbon Nucleophiles
Authors: Yang Hongwei , Fang Ling , Zhang Ming , Zhu Chengjian
Published: December 2008

Direct nucleophilic substitution of allylic alcohols with various nitrogen, oxygen, and carbon nucleophiles catalyzed by MoO2(acac)2 was realized. The corresponding products were obtained in moderate‐to‐excellent yields. Studies of the reaction mechanism showed that a carbenium intermediate was formed in the transition state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis of Symmetric Dinitro‐Functionalised Tröger's Base Analogues
Authors: Bhuiyan M. Delower H. , Mahon Andrew B. , Jensen Paul , Clegg Jack K. , Try Andrew C.
Published: December 2008

The synthesis of six new examples of 2,8‐dinitro‐substituted Tröger's base analogues are reported, together with the first examples of 1,7‐, 3,9‐ and 4,10‐dinitro Tröger's base analogues and the first example of a tetranitro Tröger's base compound. Several of these dinitro compounds lack substituents at the 2‐ and 8‐positions and therefore provide further examples of Tröger's base analogues derived from anilines lacking a para substituent. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis of Substituted 5‐(Pyrrolidin‐2‐yl)tetrazoles and Their Application in the Asymmetric Biginelli Reaction
Authors: Wu Yong‐Yong , Chai Zhuo , Liu Xin‐Yuan , Zhao Gang , Wang Shao‐Wu
Published: December 2008

A series of chiral substituted 5‐(pyrrolidin‐2‐yl)tetrazoles have been synthesized and evaluated as organocatalysts for the asymmetric Biginelli reaction. The relationship between catalytic activity and the different catalyst structures is briefly discussed. By using the optimized catalyst C10 (10 mol‐%), a series of 3,4‐dihydropyrimidin‐2(1H)‐one (DHPM) derivatives have been obtained in 63–88 % yields and 68–81 % ee values within 24 h at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Metalated Nitriles: Internal 1,3‐Asymmetric Induction
Authors: Fleming Fraser F. , Liu Wang
Published: December 2008

Stereoselective alkylations of acyclic, metalated nitriles are intimately controlled by a remote stereocenter. Probing the optimal steric demand through alkylations with a series of substituted pentanenitriles reveal the fundamental requirements for 1,3‐asymmetric induction. Relaying these requirements into a predictive model suggests that the stereoselectivity arises from a preferential electrophilic attack on the more stable diamond lattice conformation of the metalated nitrile. Using this strategy a series of metalated alkanenitriles selectively intercept a diverse range of electrophiles in alkylations that efficiently install new quaternary centers. The metalated nitrile alkylations provide fundamental insight for remote stereoinduction and a solid foundation for further advances in stereoselective alkylations of flexible nucleophiles having a defined shape.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Multicomponent Access to Functionalized Mesoionic Structures Based on TFAA Activation of Isocyanides: Novel Domino Reactions
Authors: Arévalo María José , Kielland Nicola , Masdeu Carme , Miguel Miriam , Isambert Nicolas , Lavilla Rodolfo
Published: December 2008

The reactions of azines (isoquinolines, pyridine) with TFAA and isocyanides in a new domino process yield mesoionic acid fluorides with an imidazo[1,2‐a]azine core. This multicomponent reaction has a general character, tolerating a wide range of substitution patterns on each component, and displays an unprecedented arrangement of reaction pathways. The protocol allows the incorporation of a fourth synthetic input by the reaction of a suitable nucleophile (alcohols, thiols, amines) with the acid fluoride moiety.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
The Dependence of the Sensitivity and Reliability of Contactless Conductivity Detection on the Wall Thickness of Electrophoretic Fused‐Silica Capillaries
Authors: Tůma Petr , Samcová Eva , Štulík Karel
Published: December 2008

A contactless conductivity detector (C4D) performance has been tested on a simple capillary electrophoretic separation in a standard fused‐silica capillary with an external diameter of 360 μm and in a thin‐walled capillary (an external diameter of 150 μm); the internal diameters of the two capillaries were identical, equal to 75 μm. Potassium and sodium ions have been separated in a morpholinoethanesulfonic acid/histidine background electrolyte (MES/His), over a wide range of its concentrations (0–100 mM). At low MES/His concentrations, the C4D response, obtained from the height of the potassium peak, is by 100 to 200 per cent higher for the thin‐walled capillary and the calibration dependences are linear, in contrast to the thick‐walled capillary. These differences between the two capillaries decrease with increasing MES/His concentration, the C4D response in the thin‐walled capillary is then higher by mere 20 per cent and the calibration dependences are linear in both the capillaries. The highest sensitivities have been obtained at a MES/His concentration of 50 mM, with LOD values for potassium ion of 2.0 and 2.6 μM, in the thin‐ and thick‐walled capillaries, respectively. The signal‐to‐noise ratios and the plate counts are generally similar for the two capillaries. It follows from the results that special thin‐walled capillaries can be advantageous when background electrolytes with very low conductivities must be employed.
Effects of Reduced Glutathione, Surface Active Agents, and Ionic Strength on the Detection of Metallothioneins by Using of Brdicka Reaction
Authors: Krizkova Sona , Fabrik Ivo , Adam Vojtech , Kukacka Jiri , Prusa Richard , Trnkova Libuse , Strnadel Jan , Horak Vratislav , Kizek Rene
Published: December 2008

We investigated the effects of two surface active agents (sodium dodecyl sulfate, SDS, and polyoxyethylene sorbitol, Tween‐20), ionic strength and reduced glutathione (GSH) on MT signals measured by adsorptive transfer stripping differential pulse voltammetry Brdicka reaction. If we compared the GSH and MT signals at the accumulation time of 120 s, the MT signal was more than two hundred times higher than the GSH one. The influence of Tween‐20 was investigated in a broad concentration range (from 10−8 to 10−11 %, v/v). We found that the catalytic Cat2 signal decreased for more than 60% with increasing Tween‐20 content. In the case of using SDS (10−3–10−6 M), the increase of Cat2 peak in the presence of the highest SDS concentration was determined. The height of Cat2 peak enhanced with increasing ionic strength mimicking by NaCl concentration. Based on the enhancement of the Cat2 peak we determined the ionic strength of fibroblasts sample and recalculated the concentration of MT determined there.
A Highly Selective Amperometric Hydrogen Peroxide Sensor Based on Silicomolybdate‐Doped‐Glutaraldehyde‐Cross‐Linked Poly‐L‐Lysine Film Modified Glassy Carbon Electrode
Authors: Wu Yu‐Ching , Thangamuthu R. , Chen Shen‐Ming
Published: December 2008

Silicomolybdate‐doped‐glutaraldehyde‐cross‐linked poly‐L‐lysine (PLL‐GA‐SiMo) film modified glassy carbon electrode was prepared by means of electrostatically trapping the silicomolybdate anion in the cationic film. The PLL‐GA‐SiMo film was stable and the charge transport through the film was fast. The modified electrode shows excellent electrocatalytic activity towards hydrogen peroxide reduction with significant reduction of overpotential, however, not responded to potential interferrents such as dopamine, ascorbic acid and uric acid. This unique feature of PLL‐GA‐SiMo modified electrode allowed for the development of a highly selective method for the determination of H2O2 in the presence of interferents.
Electrochemical Synthesis of Polypyrrole in the Presence of Congo Red; Application to Selective Voltammetric Determination of Dopamine in the Presence of Ascorbic Acid
Authors: Shahrokhian Saeed , Zare‐Mehrjardi Hamid Reza
Published: December 2008

The electrosynthesis of polypyrrole (PPy) film has been achieved on glassy carbon electrode (GCE) in aqueous medium of Congo red (CR) by means of cyclic voltammetry (CV). The modified electrode exhibits high electrocatalytic activity toward dopamine (DA) oxidation, with drastic enhancement of the reversibility and peak currents. This modified electrode, due to electrostatic interactions, is capable to mask the response of ascorbic acid (AA) completely and provide an effective method for the detection of minor amounts of dopamine in the presence of high concentrations of AA. The electrochemical response of the film modified electrode is strongly dependent to the switching potential applied in the CV procedure of the electro‐polymerization. The results show that by increasing the switching potential more than 0.75 V, the peak of AA is gradually disappeared. This peak in potential of 0.85 V is reached to capacitive background current. With respect to the destruction of the conjugated structure of ppy and lowering the conductivity of the film at the surface of modified electrode, higher switching potentials cannot be suitable for electropolymerization procedure. The effects of various experimental parameters such as, number of polymerization cycles, switching potential, pH and potential sweep rate on the voltammetric response of dopamine were also investigated. The modified electrode shows a linear response to DA in the range of 0.5 to 100 μM with a detection limit of 0.1 μM. The prepared modified electrode does not show any considerable response toward sulfhydryl compounds, such as, cysteine, penicillamine and glutathione, revealing a good selectivity for voltammetric response to DA. The effective electrocatalytic property, ability for masking the voltammetric responses of the other biological reducing agents together with high reproducibility and stability make the modified electrode suitable for selective and sensitive voltammetric detection of sub‐micromolar amounts of DA in clinical and pharmaceutical preparations.
Selective Detection of Ascorbic Acid Using Octacyanomolybdate‐Doped‐Glutaraldehyde‐Cross‐Linked Poly‐L‐Lysine Film Modified Glassy Carbon Electrode
Authors: Thangamuthu R. , Wu Yu‐Ching , Chen Shen‐Ming
Published: December 2008

The present work describes oxidation of ascorbic acid (AA) at octacyanomolybdate‐doped‐glutaraldehyde‐cross‐linked poly‐L‐lysine (PLL‐GA‐Mo(CN)$\rm{ {_{8}^{4-}}}$ film modified glassy carbon electrode in 0.1 M H2SO4. The modified electrode has been successfully prepared by means of electrostatically trapping Mo(CN)$\rm{ {_{8}^{4-}}}$ mediator in the cationic film of glutaraldehyde‐cross‐linked poly‐L‐lysine. The dependence of peak current of modified electrode in pure supporting indicates that the charge transfer in the film was a mixed process at low scan rates (5 to 200 mV s−1), and kinetically restrained at higher scan rates (200 to 1000 mV s−1). Cyclic voltammetry and rotating disk electrode (RDE) techniques are used to investigate the electrocatalytic oxidation of ascorbic acid and compared with its oxidation at bare and undoped PLL‐GA film coated electrodes. The rate constant of catalytic reaction k obtained from RDE analysis was found to be 9.5×105 cm3 mol−1 s−1. The analytical determination of ascorbic acid has been carried out using RDE technique over the physiological interest of ascorbic acid concentrations with a sensitivity of 75 μA mM−1. Amperometric estimation of AA in stirred solution shows a sensitivity of 15 μA mM−1 over the linear concentration range between 50 and 1200 μM. Interestingly, PLL‐GA‐Mo(CN)$\rm{ {_{8}^{4-}}}$ modified electrode facilitated the oxidation of ascorbic acid but not responded to other electroactive biomolecules such as dopamine, uric acid, NADH, glucose. This unique feature of PLL‐GA‐Mo(CN)$\rm{ {_{8}^{4-}}}$ modified electrode allowed for the development of a highly selective method for the determination of ascorbic acid in the presence of interferents.