bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential enhancement of neural and photoreceptor cell differentiation of cultured pineal cells by FGF‐1, IGF‐1, and EGF
Authors: Araki Masasuke , Suzuki Haruno , Layer Paul 
Published: June 2007

AbstractThere are several common features between the pineal organ and the lateral eye in their developmental and evolutionary aspects. The avian pineal is a photoendocrine organ that originates from the diencephalon roof and represents a transitional type between the photosensory organ of lower vertebrates and the endocrine gland of mammals. Previous cell culture studies have shown that embryonic avian pineal cells retain a wide spectrum of differentiative capacities, although little is known about the mechanisms involved in their fate determination. In the present study, we investigated the effects of various cell growth factors on the differentiation of photoreceptor and neural cell types using pineal cell cultures from quail embryos. The results show that IGF‐1 promotes differentiation of rhodopsin‐immunoreactive cells, but had no effect on neural cell differentiation. Simultaneous administration of EGF and IGF‐1 further enhanced differentiation of rhodopsin‐immunoreactive cells, although the mechanism of the synergistic effect is unknown. FGF‐1 did not stimulate proliferation of neural progenitor cells, but intensively promoted and maintained expression of a neural cell phenotype. FGF‐1 appeared to lead to the conversion from an epithelial (endocrinal) to a neuronal type. It also enhanced phenotypic expression of retinal ganglion cell markers but rather suppressed expression of an amacrine cell marker. These results indicate that growth factors are important regulatory cues for pineal cell differentiation and suggest that they play roles in determining the fate of the pineal organ and the eye. It can be speculated that the differences in environmental cues between the retina and pineal may result in the transition of the pineal primordium from a potentially ocular (retinal) organ to a photoendocrine organ. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
EphA4 misexpression alters tonotopic projections in the auditory brainstem
Authors: Huffman Kelly J. , Cramer Karina S. 
Published: June 2007

AbstractAuditory pathways contain orderly representations of frequency selectivity, which begin at the cochlea and are transmitted to the brainstem via topographically ordered axonal pathways. The mechanisms that establish these tonotopic maps are not known. Eph receptor tyrosine kinases and their ligands, the ephrins, have a demonstrated role in establishing topographic projections elsewhere in the brain, including the visual pathway. Here, we have examined the function of these proteins in the formation of auditory frequency maps. In birds, the first central auditory nucleus, n. magnocellularis (NM), projects tonotopically to n. laminaris (NL) on both sides of the brain. We previously showed that the Eph receptor EphA4 is expressed in a tonotopic gradient in the chick NL, with higher frequency regions showing greater expression than lower frequency regions. Here we misexpressed EphA4 in the developing auditory brainstem from embryonic day 2 (E2) through E10, when NM axons make synaptic contact with NL. We then evaluated topography along the frequency axis using both anterograde and retrograde labeling in both the ipsilateral and contralateral NM‐NL pathways. We found that after misexpression, NM regions project to a significantly broader proportion of NL than in control embryos, and that both the ipsilateral map and the contralateral map show this increased divergence. These results support a role for EphA4 in establishing tonotopic projections in the auditory system, and further suggest a general role for Eph family proteins in establishing topographic maps in the nervous system. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
REREa/Atrophin‐2 interacts with histone deacetylase and Fgf8 signaling to regulate multiple processes of zebrafish development
Authors: Plaster Nikki , Sonntag Carmen , Schilling Thomas F. , Hammerschmidt Matthias 
Published: June 2007

AbstractThe transcriptional regulator RERE/Atrophin‐2 (RERE) is required for the normal patterning of the early vertebrate embryo, including the central nervous system, pharyngeal arches, and limbs. Consistent with a role as a transcriptional corepressor, RERE binds histone deacetylase 1 and 2 (HDAC1/2), and orphan nuclear receptors such as Tlx. Here, we identify the zebrafishbabyface(bab) as a mutant inrereaand show that it interacts genetically withfibroblast growth factor 8(fgf8). We suggest that this finding is largely due to its interactions with HDAC, because genetic or pharmacological disruptions of HDAC phenocopy many features of thebabmutant. Furthermore, removing the functions of either REREa or HDAC synergizes with loss of Fgf8 function to disrupt posterior mesoderm formation during somitogenesis, midbrain–hindbrain boundary maintenance, and pharyngeal cartilage development. Together, these results reveal novel in vivo roles for REREa in HDAC‐mediated regulation of Fgf signaling. We present a model for RERE‐dependent patterning in which tissue‐specific transcriptional repression, by means of an REREa‐HDAC complex, modulates growth factor signaling during embryogenesis. Developmental Dynamics 236:1891–1904, 2007. © 2007 Wiley‐Liss, Inc.
Transgenic analysis of the anterior eye‐specific enhancers of the zebrafish gelsolin‐like 1 (gsnl1) gene
Authors: Yoshikawa Shunichi , Norcom Evan , Nakamura Hisashi , Yee Richard W. , Zhao Xinping C. 
Published: June 2007

AbstractThe anterior segment of the eye includes such structures as the cornea, lens, iris, and ciliary body and is essential for many visual and physiological functions of the eye. The zebrafish gelsolin‐like 1 (gsnl1) gene encodes an actin regulatory protein and is expressed in the anterior segment of the eye. We report the transgenic analyses of the gsnl1 promoter and enhancer that are required for expression in the anterior segment of the eye. A 6.4‐kb genomic fragment upstream from the translation initiation site (ATG) was capable of driving green fluorescent protein (GFP) expression in transient transgenic embryos and stable transgenic adult fish, which mimics the endogenous gsnl1 expression. The GFP expression was localized in the corneal epithelium (CE) and the annular ligament (AL) at the iridocorneal angle. A unique enhancer for each of these two tissues was identified at 3.7‐kb upstream from the ATG. The 60‐bp AL and 25‐bp CE enhancers were separated by 100‐bp and functioned independently from each other. Deletion analysis indicated that the proximal promoter was located 1.6‐kb upstream from the ATG. Stable GFP transgenic lines were established for future studies of genetic regulation in the anterior segment of the fish eye. Developmental Dynamics 236:1929–1938, 2007. © 2007 Wiley‐Liss, Inc.
Expression of Frizzled5, Frizzled7, and Frizzled10 during early mouse development and interactions with canonical Wnt signaling
Authors: Kemp Caroline R. , Willems Erik , Wawrzak Danuta , Hendrickx Marijke , Agbor Agbor Terence , Leyns Luc 
Published: June 2007

AbstractWnt signaling has been shown to be important in the patterning of the gastrulating mouse embryo, especially in axis formation. To this date, there is no clear indication that the Wnt receptors, Frizzleds (Fzds), are involved in such early specification. Moreover, at the gastrulation stage, the only Fzd with a known characterized expression pattern is Fzd8, which is expressed in the anterior visceral endoderm (aVE) (Lu et al. [2004] Gene Expr Patterns 4:569–572). Following a real time RT‐PCR study to evaluate Fzd expression in the gastrulating embryo, we used whole‐mount in situ hybridization to reveal new expression domains for Fzd5, Fzd7, and Fzd10. Fzd5 is expressed in the aVE and Fzd7 expression is restricted to the epiblast of the gastrulating embryo. The expression pattern of Fzd10 in the primitive streak of the gastrula suggests it has a role in mesoderm induction. We also show that the purified, secreted forms of the extracellular cysteine‐rich domains (CRDs) of FZD5, Fzd7, and Fzd8 can antagonize Wnt3a‐induced β‐Catenin accumulation in L‐cells, whereas in mouse embryonic stem cells, these CRDs can inhibit spontaneous mesoderm formation and promote neural differentiation. Our data demonstrate that Fzd5, Fzd7, and Fzd10 are expressed in distinct domains of the gastrulating embryo, and that the CRDs of FZD5, Fzd7, and Fzd8 can regulate Wnts, indicating that Fzds interpret Wnt signals during embryonic mesoderm and neural induction. Developmental Dynamics 236:2011–2019, 2007. © 2007 Wiley‐Liss, Inc.
Lymphatic development in mouse small intestine
Authors: Kim Kyung Eun , Sung Hoon‐Ki , Koh Gou Young 
Published: June 2007

AbstractLymphatic vessels in the small intestine serve as essential conduits for the absorption and transport of lipids from the intestine to the thoracic duct. Although the morphology and function of the intestinal lymphatic vasculature are well known, little is known about the embryonic development of these vessels. In this study, we examined development of lymphatic and blood vasculatures in the intestinal tube during mouse embryonic development by immunostaining with recently discovered molecular markers for lymphatic endothelial cells: LYVE‐1, VEGFR3, Prox‐1, and podoplanin. Immature lymphatics became detectable in mesentery, but not in intestinal tube, around E13.5–E14.5, while organized lymphatic vessel plexuses and capillaries were observed in intestinal tube and villi around E17.5. These lymphatic plexuses and capillaries in the intestinal tube appeared to be formed through an active branching process associated with activation of VEGFR3 and involvement of LYVE‐1+ macrophages. Our data also reveal that the lymphatic vessels in the intestinal tube, unlike the blood vessels, have not originated from the mesoderm of intestine. All lymphatic vessels in the intestinal tube originated by extension of mesenteric lymphatic vessels through an active branching process. Although the formation of lymphatic vessels follows the formation of blood vessels in the intestine, a mature lymphatic vasculature is formed before birth. Together, our study reveals the temporal and spatial windows of intestinal lymphatic development during embryonic development in mouse. Developmental Dynamics 236: 2020–2025, 2007. © 2007 Wiley‐Liss, Inc.
Prochondrogenic signals induce a competence for Runx2 to activate hypertrophic chondrocyte gene expression
Authors: Kempf Hervé , Ionescu Andreia , Udager Aaron M. , Lassar Andrew B. 
Published: June 2007

AbstractWhereas Runx2 is necessary for bone formation and cartilage hypertrophy, it is unclear why Runx2 induces markers of chondrocyte hypertrophy only in chondrocytes. We document that chondrocytes either contain a cofactor, which can be induced in somitic cells by prochondrogenic signals, that is necessary for Runx2 to induce chondrocyte hypertrophy or, alternatively, lack a repressor of this maturation program. Sequential Shh and bone morphogenetic protein (BMP) signals or forced expression of either Nkx3.2 or Sox9 (plus BMP signals) induces chondrogenesis in presomitic mesoderm and simultaneously induces a competence for Runx2 to activate the chondrocyte maturation program. The ability of either sequential Shh and BMP signals or retrovirus‐encoded Nkx3.2 or Sox9 to induce this competence correlates with their ability to activate chondrogenesis in various embryonic tissues. Consistent with these findings in embryonic tissues, we have found that cotransfected Runx2 and Smad1 are able to induce the expression of a reporter construct driven by the collagen X regulatory sequences in chondrocytes but not in fibroblasts. In contrast, both Runx2 and Smad1 are competent to activate reporters driven by either reiterated Runx or Smad binding sites, respectively, in both cell types. As Sox9 and Nkx3.2 have previously been shown to block chondrocyte maturation in vivo, our findings suggest that these transcription factors can, in addition, either induce the expression or activity of a factor in chondrocytes that is required for Runx2 to activate the chondrocyte maturation program, or alternatively that these transcription factors block the expression or activity of a repressor of this maturation program. Developmental Dynamics 236:1954–1962, 2007. © 2007 Wiley‐Liss, Inc.
Culture of Ciona intestinalis in closed systems
Authors: Joly Jean‐Stéphane , Kano Shungo , Matsuoka Terumi , Auger Helene , Hirayama Kazuko , Satoh Nori , Awazu Satoko , Legendre Laurent , Sasakura Yasunori 
Published: June 2007

AbstractA virtual image showing ascidian Ciona intestinalis larvae swimming to "corals" located at the bottom of the picture. On top right is a tailbud embryo still in the chorion before hatching. Swimming larvae are carrying constructs driving the expression of green fluorescent proteins in epidermis. Larvae become juveniles through metamorphosis (lower right). Juveniles and adult neural complex pictures derive from a transgenic line with Ror‐b regulatory sequences, which drives yellow fluorescent protein expression at the top of endostyles in juveniles and at the margins of the so‐called ciliated funnels in neural complexes. The corals were reconstructed from details of two adult neural gland complexes artificially merged. Our ascidian facilities in closed‐systems contribute to the maintenance of such transgenic lines. See Joly et al., Developmental Dynamics 236:1832–1840.
Phosphane and Phosphite Unsymmetrically Disubstituted Diiron Complexes Related to the Fe‐Only Hydrogenase Active Site
Authors: Li Ping , Wang Mei , He Chengjiang , Liu Xiaoyang , Jin Kun , Sun Licheng 
Published: June 2007

AbstractA series of unsymmetrically disubstituted diiron complexes [(μ‐pdt){Fe(CO)2L1}{Fe(CO)2L2}] [pdt = 1,3‐propanedithiolato; L1 = PMe3, L2 = PMe2Ph, 4; PPh3, 5; PCy3, 6; P(OEt)3, 7; L1 = PMe2Ph, L2 = PPh3, 8; P(OEt)3, 9; L1 = P(OEt)3, L2 = PPh3, 10; PCy3, 11] and [(μ‐edt){Fe(CO)2PMe3}{Fe(CO)2PPh3}] (edt = 1,2‐ethanedithiolato, 12) were prepared by means of stepwise CO displacements of [(μ‐pdt)Fe2(CO)6] and [(μ‐edt)Fe2(CO)6] by different tertiary phosphane and phosphite ligands. The interconversion of the irondithiacyclohexane ring and the rotation of the [Fe(CO)2PR3] subunit were studied using by variable‐temperature 31P{1H} NMR spectroscopy of 4, 6 and 12 in solution. The molecular structures of 4–6, 8–10 and 12 show that complexes 4–6, 8, 9 and 12 possess an apical/basal coordination mode and complex 10 has an apical/apical conformation. The X‐ray analyses indicate that the PMe2Ph ligand in the apical position of the starting complex [(μ‐pdt){Fe(CO)3}{FeCO2(PMe2Ph)}] rotates to the basal position on conversion to the products 8 and 9. Cyclic voltammograms of 4–11 were studied both under argon and CO. The influences of the phosphane and phosphite ligands on the redox properties of the unsymmetrically disubstituted diiron complexes are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Localization and Delocalization of Spin Density in Mixed‐Valence (VIV/VV) [(V2O3)2(PhPO3)4⊂F]–n (n = 1, 2): Theoretical and Experimental Studies
Authors: Thong Nguyen Huu , Jabor Jabor K. , Stößer Reinhard , Meisel Manfred , Ziemer Burkhard 
Published: June 2007

AbstractBased on XRD and optimized structures of the cage compound [(V2O3)2(PhPO3)4⊂F]–n in singlet (n = 1) and doublet (n = 2) states DFT calculations were carried out to determine the energies and spin density distribution for the symmetries D2d, C2v, and Cs. It turned out, that the cage with Cs symmetry not only represents the energetically more stable doublet system (with respect to D2d and C2v‐symmetries) but also corresponds to the real compound under study. The SOMO of the S = 1/2 cage represents an antibonding state and the volume of the cage in this state is larger than that in the S = 0 state. The calculated ESR hyperfine coupling constants are in acceptable agreement with those determined by ESR. Experimentally the localization/delocalization of spin density was determined via ESR as a function of temperature and adsorption of the cage on Al2O3, respectively. A proposal is given for the localization/delocalization of spin density based on thermally driven changes of the cage symmetry in combination with the hopping of the unpaired electron inside the cage.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
C–H···NiII Interaction‐Driven Homochiral M and P Helices of Neutral (R,R)‐ and (S,S)‐Bis(pyrrol‐2‐ylmethyleneamino)cyclohexane NiII Complexes
Authors: Shan Xu‐Feng , Wu Li‐Zhu , Liu Xian‐Yu , Zhang Li‐Ping , Tung Chen‐Ho 
Published: June 2007

AbstractReaction of (R,R)‐ and (S,S)‐bis(pyrrol‐2‐ylmethyleneamino)cyclohexane with NiII(OAc)2·4H2O afforded enantiomeric nickel(II) Schiff‐base complexes (R,R)‐1 and (S,S)‐1, respectively. Rare C–H···NiII interactions were found to be responsible for the facile formation of homochiral M and P helices of the neutral, chiral, mononuclear complexes in crystal lattices. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Crystallographic Characterisation of the Heterodimetallic Complex [(Dibenzo‐18‐crown‐6)K(μ‐Cl)3Ru(η6‐p‐cymene)]
Authors: Vock Carsten A. , Scopelliti Rosario , Dyson Paul J. 
Published: June 2007

AbstractThe triple‐chlorido‐bridged heterodimetallic dinuclear complex [(dibenzo‐18‐crown‐6)K(μ‐Cl)3Ru(η6‐p‐cymene)] containing an (η6‐arene)RuII fragment and a Group 1 metal crown ether fragment was synthesized and characterized by spectroscopy and X‐ray crystallography. The solid‐state structure clearly reveals the presence of the triple‐chlorido‐bridged dinuclear complex, whereas NMR investigations in different deuteriated solvents reveal the presence of an essentially 1:1 mixture of 1 and starting materials, indicating the presence of a dynamic equilibrium. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Reactions of Polynuclear Polyhydrido Rare Earth Metal Complexes Containing “(C5Me4SiMe3)LnH2” Units: A New Frontier in Rare Earth Metal Hydride Chemistry
Authors: Hou Zhaomin , Nishiura Masayoshi , Shima Takanori 
Published: June 2007

AbstractThe back cover picture shows the Ln4H8 core structure of the tetranuclear, rare earth metal, octahydride complexes [(C5Me4SiMe3)4Ln4H8(THF)n] (Ln = Sc, Y, Gd, Dy, Ho, Er, Tm, Lu; n = 0, 1, or 2). These hydride clusters exhibit extremely high and unique reactivity towards a variety of unsaturated substrates, which leads to the formation of a new family of polynuclear compounds. Details are discussed in the article by Z. Hou et al. on p. 2535 ff.
Transesterification of the crude Jatropha curcas L. oil catalyzed by micro‐NaOH in supercritical and subcritical methanol
Authors: Tang Zhiyong , Wang Lianyuan , Yang Jichu 
Published: June 2007

AbstractTransesterification of the crude Jatropha curcas L. oil catalyzed by micro‐NaOH in supercritical/subcritical methanol was studied. The effects of various reaction variables such as the catalyst content, reaction temperature, reaction pressure and the molar ratio of methanol to oil on the conversion of crude Jatropha curcas L. oil to biodiesel were investigated. The results showed that even micro‐NaOH could noticeably improve this reaction. When NaOH was added from 0.2 to 0.5 to 0.8 wt‐‰ of triacylglycerols, the transesterification rate increased sharply; when the catalyst content was further increased, the reaction rate was just poorly improved. It was observed that increasing the reaction temperature had a favorable influence on the methyl ester yield. For the molar ratio ranging from 18 to 36, the higher the molar ratio of methanol to oil was charged, the faster the transesterification rate seemed. At the fixed stirring rate of 400 rpm, when the catalyst content, reaction temperature, reaction pressure and the molar ratio of methanol to oil were developed at 0.8 wt‐‰ NaOH, 523 K, 7.0 MPa and 24 : 1, respectively, the methyl ester yield could reach 90.5% within 28 min. Further, the kinetics of this reaction was involved and the results showed that it was a pseudo‐first‐order reaction whose apparent activation energy was 84.1 kJ/mol, and the pre‐exponential factor was 2.21×105.
Cascade Reactions of Me3Si‐Substituted Imidazolidine‐1,3‐Diols with PbO2, Including Oxidation of the Corresponding Diol and Subsequent Elimination of the Trimethylsilyl Fragment
Authors: Tretyakov Eugene , Romanenko Galina , Ikorskii Vladimir , Stass Dmitry , Vasiliev Vladimir , Demina Maria , Mareev Alexander , Medvedeva Alevtina , Gorelik Elena , Ovcharenko Victor 
Published: June 2007

AbstractIt was found that reactions of 2‐Me3Si‐R‐substituted (Si–Csp or Si–C) imidazolidine‐1,3‐diols with PbO2 in MeOH are cascade reactions, which involve the oxidation of imidazolidine‐1,3‐diols into nitronyl nitroxide (NN–R–SiMe3) and further elimination of the Me3Si group to give NN–R–H. The efficiency of a one‐pot approach in the synthesis of nitronyl nitroxides is demonstrated by reference to syntheses of2‐ethynyl‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (2), 2‐(4‐ethynylphenyl)‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (8), (E)‐4,4,5,5‐tetramethyl‐2‐[2‐(pyrrolidin‐1‐yl)vinyl]‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (3a), (E)‐2‐[2‐(diisopropylamino)vinyl]‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (3b), and 4,4,5,5‐tetramethyl‐2‐(1H‐1,2,3‐triazol‐5‐yl)‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (H11). Interaction of 2 with secondary amines formed only trans isomers 3a and 3b. X‐ray investigation of 3a and 3b confirmed that the reaction is regiospecific. Static magnetochemical measurements detected weak exchange interactions between the odd electrons of the paramagnetic centers in the solid nitronyl nitroxide products, including H11 whose crystals consist of helices formed by numerous intermolecular H bonds. The ESR spectra of 3a, 3b, and H11 show substantial delocalization of spin density to the substituent. Modeling reproducibly gave equal hyperfine coupling constants (HFC) for the imidazoline nitrogen atoms of 3b and different HFC for the nitrogen atoms of 3a and H11, indicating that rotation of the two cyclic substituents is hindered. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Development of Ketoside‐Type Analogues of Trehalose by Using α‐Stereoselective O‐Glycosidation of Ketose
Authors: Namme Rie , Mitsugi Takashi , Takahashi Hideyo , Ikegami Shiro 
Published: June 2007

AbstractThe stereoselective synthesis of ketoside‐type analogues of trehalose is described. O‐Glycosidation of hept‐2‐ulopyranose with trimethylsilyl α‐pyranoside promoted by trimethylsilyl trifluoromethanesulfonate afforded α‐ketopyranosyl α‐aldopyranosides exclusively. α‐Ketopyranosyl β‐aldooyranosides and α‐ketopyranosyl α‐ketopyranosides were also synthesized in a similar manner. The benzyl protecting groups of the hydroxy moieties were removed by hydrogenolysis to afford fully deprotected trehalose analogues.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Practical Syntheses of Enantiomerically Pure N‐Acetylbenzhydrylamines
Authors: Castagnolo Daniele , Giorgi Gianluca , Spinosa Raffaella , Corelli Federico , Botta Maurizio 
Published: June 2007

AbstractTwo practical routes for the synthesis of benzhydrylamine derivatives in enantiomerically pure form have been developed. N‐Acetylbenzhydrylamines can be synthesised in few steps and good yields starting from 1‐aryl‐1‐propargylamines. The key steps are represented by the alkene‐alkyne cross metathesis reaction and alkyne–diene methylene‐free tandem‐metathesis reaction; these reactions have been performed under microwave irradiation in a few minutes and high yields. N‐Acetylbenzhydrylamines have been also converted in both enantiomers of the antifungal agent bifonazole, emphasizing the importance of these compounds as scaffolds for the synthesis of biologically active compounds in enatiopure form.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)