bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental progression of Gpd expression from the inactive X chromosome of the virginia opossum
Authors: Samollow Paul B. , Robinson Edwards S. , Ford Allen L. , Vandeberg John L.
Published: May 2005

Metatherian (marsupial) mammals possess a non‐random form of X‐chromosome inactivation in which the paternally‐derived X is always the one inactivated. To examine the progression of X‐linked gene expression during metatherian development, we compared relative levels of the maternally and paternally encoded Gpd gene products in heterozygous female Virginia opossums (Didelphis virginiana) across a moior portion of the developmental period. Panels of tissues obtained from fetuses, newborns, and pouch young were examined via polyacrylamide gel electrophoresis of the G6PD protein. As in adults, G6PD phenotypes in these developmental stages were highly skewed in favor of the maternal allele product, but in some tissues there was a marked increase in paternal allele expression with advancing developmental age. However, even by 42 days of post‐partum development, expression of the paternal Gpd allele had not attained the adult, tissue‐specific activity pattern. Our findings indicate remarkable developmental changes in the activity of the paternal allele in several tissues/organs continuing well into mid pouch‐life stages and beyond. Specifically we found that 1) a substantially repressed paternal Gpdgene is present in the cells of female stage 29 fetuses and later developmental stages, 2) the activity state of the paternal Gpd gene is not fixed during early embryonic development in this species, 3) maior changes in paternal Gpd expression occur in advanced developmental stages and comprise a maturation of the gene expression pattern during ontogeny, and 4) alterations of paternal Gpd allele activity during development occur in a tissue‐specific manner. © 1995 Wiley‐Liss, Inc.
Cell mixing during early epiboly in the zebrafish embryo
Authors: Wilson Ellen T. , Cretekos Chris J. , Helde Kathryn Ann
Published: May 2005

Descendants of early blastomeres in the zebrafish come to populate distinctive regions of the fate map. We present a model suggesting that the distribution of cells in the early gastrula (the fate map stage) results from the passive response of cells to reproducible forces that change the overall shape of the blastoderm just prior to gastrulation. We suggest that one of the morphogenetic changes that accompanies epiboly, the upward doming of the yolk cell into the overlying blastoderm, could be responsible for cell mixing. In support of the model, we show that the timing, extent, and directions of cell mixing in the embryo accurately reflect the expectations of the model. Finally, we show that one portion of the gastrula, a marginal region that later gives rise to many of the mesendodermal derivatives, experiences little cell mixing during the doming process. As a result, this region in the gastrula is populated by the descendants of the subset of the early blastomeres that were originally at the margin. The finding that cytoplasm initially at the edge of the 1‐celled blastodisc is transmitted specifically to mesendodermal precursors at the fate map stage raises the possibility that maternal determinants may contribute to initiation of embryonic patterning in the zebrafish embryo. © 1995 Wiley‐Liss, Inc.
Allocation of epiblast cells to germ layer derivatives during mouse gastrulation as studied with a retroviral vector
Authors: Carey Frederick J. , Linney Elwood A. , Pedersen Roger A.
Published: May 2005

The embryonic ectoderm, or epiblast, is the source of the three primary germ layers that form during gastrulation in the mouse embryo. Previous studies have investigated the fate of epiblast cells in early gastrulation stages using clonal analysis of cell lineage and in late gastrulation stages using transplantation of labeled grafts. In this study, we studied the fate of late gastrulation stage epiblast using a clonal analysis based on a retroviral vector encoding theEscherichia coli lacZgene. We found that by reducing the volume of viral suspension injected into each embryo, it was possible to achieve single infectious events. Our analysis of 20 embryos singly infected at the late streak stage and 21 at the head fold stage revealed clonal descendants in only a single germ layer in each embryo. These results indicate that allocation of epiblast progenitors to a single germ layer fate has occurred by late gastrulation in mouse embryos. © 1995 Wiley‐Liss, Inc.
Cloning, sequencing, and expressional analysis of the chick homologue of follistatin
Authors: Connolly D. J. , Patel K. , Seleiro E. A. P. , Wilkinson D. G. , Cooke J.
Published: May 2005

Follistatin, a secreted glycoprotein, has been shown to act as a potent neural inducer during early amphibian development. The function of this protein during embryogenesis in higher vertebrates is unclear, and to further our understanding of its role we have cloned, sequenced, and performed an in‐depth expressional analysis of the chick homologue of follistatin. In addition we also describe the expression pattern of activin βA and activin β B, proteins that have previously been shown to be able to interact with follistatin. In this study we show that the expression of follistatin and the activins do not always overlap. Follistatin was first detected in Hensen's node and subsequently in the region described by Spratt [1952] as the neuralising area. In older embryos it was also expressed in a highly dynamic manner in the hind‐brain as well as in the somites. We also present evidence that follistatin may have a later role in the resegmentation of the somites. We were unable to detect the expression of activin βA during early embryogenesis, whereas activin βB was first expressed in the extending primitive streak and subsequently in the neural folds. The results from this study are consistent with a role for follistatin in neural induction but suggest it has additional functions unrelated to its inhibitory actions on activins. © 1995 Wiley‐Liss, Inc.
Ventral mesodermal patterning in Xenopus embryos: Expression patterns and activities of BMP‐2 and BMP‐4
Authors: Hemmati‐Brivanlou Ali , Thomsen Gerald H.
Published: May 2005

We provide a comparative analysis of the expression patterns and ventral mesoderm‐inducing properties of Xenopus BMP‐2 and BMP‐4. Transcripts for BMP‐2 and BMP‐4 are maternally stored in eggs, and zygotic expression of these genes is uniform in the ectoderm and mesoderm in late blastulae. During gastrulation, BMP‐2 is expressed at a low level throughout the ectoderm and marginal zone, but at early neurula stages a patch of dorso‐anterior cells displays enhanced expression. In contrast, BMP‐4 transcripts are restricted to the ventrolateral marginal zone during gastrulation, and in late gastrula and early neurula BMP‐4 is expressed in the epidermis but not the neural plate. At post‐neurula stages, BMP‐2 and BMP‐4 transcripts are associated with a variety of mesodermal structures, including the pharyngeal pouches, heart, blood island, and blastopore. At tailbud stages, BMP‐2 and BMP‐4 are expressed in neural tissues including the neural tube and brain. In mesoderm induction assays, BMP‐2 and BMP‐4 induce Xhox3, an early ventral‐posterior mesoderm marker, and larval βT1 globin, a marker for red blood cells. Induction of red blood cells in response to BMP‐4 was demonstrated by staining with a hemoglobin‐specific reagent. Little is known about factors that induce hematopoietic lineages in vertebrates, and these results provide evidence linking BMP activity and blood differentiation. Globin induction by BMP‐2 and BMP‐4 is blocked by co‐expression of a dominant‐negative activin receptor, suggesting that either endogenous activin signals are required for BMP‐mediated induction, or that the trancated activin receptor interferes with signaling by BMP receptors. In assays on marginal zone explants, we demonstrate that BMP‐4 respecifies dorsal mesoderm to form ventral mesoderm, consistent with its ability to induce blood and to ventralize embryos. BMP‐2, however, does not display such activity. The findings extend and support evidence that BMP‐2 and BMP‐4 function in ventral mesoderm induction and patterning in Xenopus. Our data furthermore high light the multiple functions these factors fulfill during early vertebrate embryogenesis. © 1995 Wiley‐Liss, Inc.
Expression of HGF/SF, HGFI/MSP, and c‐met suggests new functions during early chick development
Authors: Théary Clotilde , Sharpe Melanie J. , Batley Sarah J. , Stern Claudio D. , Gherardi Ermanno
Published: May 2005

We report the cloning of full‐length cDNAs for a plasminogen‐related growth factor, hepatocyte growth factor/scatter factor (HGF/SF), its tyrosine kinase receptor, c‐met, and a close member of the same family, hepatocyte growth factor‐like/macrophage stimulating protein (HGFI/MSP), from the chick. We have used these cDNAs to provide the first report of the expression of this family of growth factors and the c‐met receptor at early stages of vertebrate development. RNAase protection and wholemount in situ hyb ridization were used on chick embryos between formation of the primitive streak and early organogenesis. We find patterns of expression for HGF/SF and its receptor c‐met consistent with their known roles in ep ithelial‐mesenchymal transformation and angiogenesis. In addition, these genes and HGFI/MSP are expressed in discrete locations within developing somites, suggesting a role in paraxial mesodermal development. Very strong and early expression of HGF/SF in the elevating limb buds suggests its involvement in limb outgrowth. HGFI/MSP is expressed in the notochord and then in the prospective floor plate region and could play a role in development of the neural tube. Interestingly, c‐met is often more closely as sociated with HGFI/MSP than with its known ligand, HGF/SF, raising the possibility that c‐met expression may be induced by HGFI/MSP. © 1995 Wiley‐Liss, Inc.
Widespread expression of the eve1 gene in zebrafish embryos affects the anterior‐posterior axis pattern
Authors: Barro Ousmane , Vriz Sophie , Joly Jean‐Stephane , Joly Claire , Condamine Hubert , Boulekbache Habib
Published: May 2005

The zygotic expression of the evel gene is restricted to the ventral and laletul cells of the marginal zone. At later stages, the mRNAs are localized in the most posterior part of the extending tail tip. An evel clone (pcZf14), containing a poly‐A tail, has been isolated. In order to address evel gene function, pcZf14 transcript injections into zebrafish embryos have been performed. The injection into uncleaved eggs of a synthetic evel mRNA (12 pg), which encodes a protein of 28 kd, produces embryos with anterior‐posterior (A‐P) axis defects and the formation of additional axial structures. The first category of 24 h phenotypes (87%) mainly displays a gradual decrease in anterior structures. This is comparable to previous phenotypes observed following Xhox3 messenger injection either in Xenopus or in zebrafish that have been classified according to the index of axis deficiency (zf‐IAD). These phenotypes result in anomalies of the development of the neural keel, from microphthalmia to acephaly. The second category (13%) corresponds to the phenotypes described above together with truncal or caudal supernumerary structures. Additional truncal structures are the most prominent of these duplicated phenotypes, displaying a “zipper” shape of axial structures including neural keels and noto‐chords. Caudal duplication presents no evident axis supernumerary structures. The observation of these phenotypes suggests an important role for the evel gene in mesodermal cell specification and in the development of the posterior region, and more particularly of the most posterior tail tip where endogenous eve1 messengers are found. © 1995 Wiley‐Liss, Inc.
Involvement of Wnt1 and Pax2 in the formation of the midbrain‐hindbrain boundary in the zebrafish gastrula
Authors: Kelly Gregory M. , Moon Randall T.
Published: May 2005

The secreted signalling molecule encoded by the wntl gene and the paired box‐containing pax2 gene are thought to play an integral role in patterning the zebrafish rostral nervous system. Using a double‐label analysis, we compare the expression patterns of wnt1 RNA and pax2 protein during zebrafish embryogenesis to determine whether they were expressed in identical or overlapping patterns in individual embryos. During gastrulation, wntl RNA was detected in a pattern similar but not identical to the pax2 protein. Later, wntl and pax2 co‐localize to the midbrain‐hindbrain boundary. Exogenous retinoic acid, a teratogen that is known to affect the formation of the midbrain‐hindbrain boundary, has a profound affect on both wntl and pax2 expression at gastrulation. Furthermore, when pax2 is overexpressed in zebrafish embryos, the wntl pattern of expression expands ventrally in the prospective rostral neuroepithelium. Despite the widespread and random distribution of exogenous pax2 RNA, it alone is unable to induce wntl expression in other ec‐topic sites. These results are consistent with the coordinate expression of wntl and pax2 being in a pathway responsible for establishing the midbrain‐hindbrain boundary and support the earlier interpretation that pax2 may regulate wntl expression [Krauss et al., 1992], although only in a subset of embryonic cells. These data suggest that a predisposition for the regionalization of the central nervous system exists at gastrulation. © 1995 Wiley‐Liss, Inc.
Involvement of differential gene expression and mRNA stability in the developmental regulation of the hsp 30 gene family in heat‐shocked Xenopus laevis embryos
Authors: Ohan Nicholas W. , Heikkila John J.
Published: May 2005

Four complete hsp 30 genes have been isolated from Xenopus laevis: hsp 30A, hsp 30B (a pseudogene), hsp 30C, and hsp 30D. The hsp 30A and hsp 30C genes are first heat inducible at the early tailbud stage, as determined by RNase protection and RT‐PCR assays. In this study, we determined by RT‐PCR that the hsp 30D gene was first heat inducible (33oC for 1 h) at the mid‐tailbud stage, approximately 1 day later in development than hsp 30A and hsp 30C. Furthermore, using Northern blot analysis, we detected the presence of very low levels of hsp 30 mRNA at the heat‐shocked late blastula stage. The relative levels of these pre‐tailbud (PTB) hsp 30 mRNAs increased at the gastrula and neurula stage followed by a dramatic enhancement in heat shocked tail‐bud and tadpole stage embryos (50‐ to 100‐ fold relative to late blastula). Interestingly, treatment of blastula or gastrula embryos at high temperatures (37oC for 1 h) or with the protein synthesis inhibitor, cycloheximide, followed by heat shock, led to enhanced accumulation of the pre‐tailbud (PTB) hsp 30 mRNAs. hsp 70, hsp 87, and actin messages were not stabilized at high temperatures or by cycloheximide treatment. Finally, hsp 30D mRNA was not detected by RT‐PCR analysis of cycloheximidetreated, heat‐shocked blastula stage embryos, confirming that it is not a member of the PTB hsp 30 mRNAs. This study indicates that differential gene expression and mRNA stability are involved in the regulation of hsp 30 gene expression during early Xenopus laevis development. © 1995 Wiley‐Liss, Inc.
Transmission‐ratio distortion of X chromosomes among male offspring of females with skewed X‐inactivation
Authors: Naumova A. K. , Olien L. , Bird L. M. , Slamka C. , Fonseca M. , Verner A. E. , Wang M. , Leppert M. , Morgan K. , Sapienza C.
Published: May 2005

We have begun a search for heritable variation in X‐chromosome inactivation pattern in normal females to determine whether there is a genetic effect on the imprinting of X‐chromosome inactivation in humans. We have performed a quantitative analysis of X‐chromosome inactivation in lymphocytes from mothers in normal, three‐generation families. Eight mothers and 12 grandmothers exhibited evidence of highly skewed patterns of X‐chromosome inactivation. We observed that the male offspring of females with skewed X‐inactivation patterns were three times more likely to inherit alleles at loci that were located on the inactive X chromosome (Xi) than the active X chromosome (Xa). The region of the X chromosome for which this phenomenon was observed extends from XP11 to ‐Xq22. We have also examined X‐chromosome inactivation patterns in 21 unaffected mothers of male bilateral sporadic retinoblastoma patients. Six of these mothers had skewed patterns of X‐chromosome inactivation. In contrast to the tendency for male offspring of skewed mothers from nondisease families to inherit alleles from the inactive X chromosome, five of the six affected males inherited the androgen receptor alleles from the active X chromosome of their mother. © 1995 Wiley‐Liss, Inc.
Expression of X‐linked genes in androgenetic, gynogenetic, and normal mouse preimplantation embryos
Authors: Latham Keith E. , Rambhatla Lakshmi
Published: May 2005

A quantitative RT‐PCR approach has been used to examine the expression of a number of X‐linked genes during preimplan‐tation development of normal mouse embryos and in androgenetic and gynogenetic mouse embryos. The data reveal moderately reduced expression of the Prps1, Hprt, and Pdha1 mRNAs in androge‐netic eight‐cell and morula stage embryos, but not in androgenetic blastocysts. Pgk1 mRNA abundance was severely reduced in androgenones at the eight‐cell and morula stages and remained reduced, but to a lesser degree, in androgenetic blastocysts. These data indicate that paternally inherited X chromosomes are at least partially repressed in androgenones, as they are in normal XX embryos, and that the degree of this repression is chromosome position‐dependent or gene‐dependent. Gynogenetic embryos expressed elevated amounts of some mRNAs at the morula and blas‐tocyst stages, indicative of a delay in dosage compensation that may be chromosome position‐dependent. The Xist RNA was expressed at a greater abundance in androgenones than in gynogenones at the eight‐cell and morula stages, consistent with previous studies. Xist expression was observed in both and rogenones and gynogenones at the blas‐tocyst stage. We conclude that the developmental arrest in early androgenones may be, in part, due to reduced expression of essential X‐linked genes, particularly those near the X inactivation center, where as the developmental defects of gyno‐genones and parthenogenones, by contrast, may be partially due to overexpression of X‐linked genes in extraembryonic tissues, possibly those far‐thest away from the X inactivation center. © 1995 Wiley‐Liss, Inc.
Identification of genes showing altered expression in preimplantation and early postimplantation parthenogenetic embryos
Authors: Mann Mellissa , Latham Keith E. , Varmuza Sue
Published: May 2005

Uniparental embryos have been instrumental in studying imprinting because contributions from the parental genomes can be determined unambiguously. In this study, we set out to identify imprinted genes showing differential expression between parthenogenetic and fertilized embryos during preimplantation and early postimplantation stages of development. We identified three genes‐apolipoprotein E, pyruvate kinase‐3, and protein phosphatase 1 gamma‐that represent excellent candidates for imprinted genes, based on the results of the differential screen, their function in differentiation and the cell cycle, and their location within imprinted chromosomal regions. In addition, two novel genes expressed in trophoblast were identified, 1661 and RA81. These genes, together with four known imprinted genes, H19, Igf2r, Igf2, and Snrpn, showed evidence of expression from both parental alleles in early stage embryos, indicating a role for postfertilization processes in regulating imprinted gene function. © 1995 Wiley‐Liss, Inc.
Expression of SGP‐1 mRNA in preimplantation mouse embryos
Authors: Cao Qiu Ping , Crain William R.
Published: May 2005

In a search for genes expressed in preimplantation mouse embryos that are important for the earliest steps in differentiation, we identified an abundant mRNA that codes for a sulfated glycoprotein, SGP‐1. The amount of this RNA rises ˜ 100‐fold during preimplantation development to a level approximately equal to that of β‐actin mRNA in blastocysts, although the level of these transcripts per cell remains fairly constant during these stages at ˜ 2,000–4,000 copies. An antisense RNA that is complementary to approximately the last one‐third of the message and contains an open reading frame of 455 nt was found in blastocysts at a 2–3‐fold higher level than the mRNA. In situ hybridization with sense and antisense riboprobes showed that both strands are distributed throughout the embryo. The abundance of the SGP‐1 mRNA indicates that the encoded protein may play an important role in the development of embryos, and the excess of antisense RNA raises the possibility of an unusual mechanism of regulating its expression. © 1995 Wiley‐Liss, Inc.
A Xenopus laevis gene encoding EF‐1αS, the somatic form of elongation factor 1α: Sequence, structure, and identification of regulatory elements required for embryonic transcription
Authors: Johnson Andrew D. , Krieg Paul A.
Published: May 2005

Transcription of the Xenopus laevis EF‐1αS gene commences at the mid‐blastula stage of embryonic development and then continues constitutively in all somatic tissues. The EF‐1αS promoter is extremely active in the early Xenopus embryo where EF‐1αS transcripts account for as much as 40% of all new polyadenylated transcripts. We have isolated the Xenopus EF‐1αS gene and used microinjection techniques to identify promoter elements responsible for embryonic transcription. These in vivo expression studies have identified an enhancer fragment, located approximately 4.4 kb upstream of the transcription start site, that is required for maximum expression from the EF‐1αS promoter. The enhancer fragment contains both an octamer and a G/C box sequence, but mutation studies indicate that the octamer plays no significant role in regulation of EF‐1αS expression in the embryo. The presence of a G/C element in the enhancer and of multiple G/C boxes in the proximal promoter region suggests that the G/C box binding protein, Spl, plays a major role in the developmental regulation of EF‐1αS promoter activity. © 1995 Wiley‐Liss, Inc.
Spatial expression of the hsr‐omega (93D) gene in different tissues of drosophila melanogaster and identification of promoter elements controlling its developmental expression
Authors: Mutsuddi Mousumi , Lakhotia S. C.
Published: May 2005

Developmental expression of the heat shock inducible non‐protein coding hsromega gene in several larval and adult tissues of Drosophila melanogaster was examined by in situ hybridization to transcripts in intact organs and by X‐gal staining in the germline transformants carrying the lacZ reporter gene under the control of hsromega promoter. This gene is expressed in a specific spatial pattern in all the larval and adult tissue types examined; however, its transcripts were specifically absent in certain gonadal cell types like the male as well as female gonial cells and in follicle cells and oocytes in ovary. All polytenised tissues like the prothoracic and salivary glands, certain regions of larval gut and the Malpighian tubules showed a greater abundance of hsr‐omega transcripts with a strong hybridization in nuclei. Our results with promoter deletion variant germline transformants suggest that a region between –346bp to –844bp upstream contains major regulatory element/s for developmental expression of this gene in most of the larval and adult tissues examined; however, this region is not sufficient for its normal expression in male and female reproductive systems. An analysis of the base sequence of the hsr‐omega promoter (upto –844bp) reveals putative ecdysone receptor element half‐sites and two GAGA factor binding sites which may be involved in its developmental expression and its ready inducibility. The widespread expression in most tissue types and the known lethality associated with its homozygous deletion, suggest that the variety of non‐protein coding transcripts of the hsromega gene have vital “house‐keeping” functions.
Identification of members of the HSP30 small heat shock protein family and characterization of their developmental regulation in heat‐shocked xenopus laevis embryos
Authors: Tam Ying , Heikkila John J.
Published: May 2005

In the present study we have characterized the synthesis of members of the HSP30 family during Xenopus laevis development using a polyclonal antipeptide antibody derived from the carboxyl end of HSP30C. Two‐dimensional PAGE/immunoblot analysis was unable to detect any heat‐inducible small HSPs in cleavage, blastula, gastrula, or neurula stage embryos. However, heat‐inducible accumulation of a single protein was first detectable in early tailbud embryos with an additional 5 HSPs at the late tailbud stage and a total of 13 small HSPs at the early tadpole stage. In the Xenopus A6 kidney epithelial cell line, a total of eight heat‐inducible small HSPs were detected by this antibody. Comparison of the pattern of protein synthesis in embryos and somatic cells revealed a number of common and unique heat inducible proteins in Xenopus embryos and cultured kidney epithelial cells. To specifically identify the protein product of the HSP30C gene, we made a chimeric gene construct with the Xenopus HSP30C coding sequence under the control of a constitutive promoter. This construct was microinjected into fertilized eggs and resulted in the premature and constitutive synthesis of the HSP30C protein in gastrula stage embryos. Through a series of mixing experiments, we were able to specifically identify the protein encoded by the HSP30C gene in embryos and somatic cells and to conclude that HSP30C synthesis was first heat‐inducible at the early tailbud stage of development. The differential pattern of heat‐inducible accumulation of members of the HSP30 family during Xenopus development suggests that these proteins may have distinct functions at specific embryonic stages during a stress response.
Book Review: Emulsifiers in Food Technology. By R. J. Whitehurst
Authors: Filip Vladimír , Pokorný Jan
Published: May 2005

No abstracts.
Inner‐Phase Reaction Dynamics: The Influence of Hemicarcerand Polarizability and Shape on the Potential Energy Surface of an Inner‐Phase Reaction
Authors: Sánchez Carrera Sigifredo , Kerdelhué Jean‐Luc , Langenwalter Kevin J. , Brown Neil , Warmuth Ralf
Published: May 2005

The thermal decomposition of six phenyldiazirine (2) hemicarceplexes and the spectroscopic properties of these hemicarceplexes, as well as those of one spiro[cyclobutabenzene‐1(2H),3′‐diazirine] (1) and one p‐tolyldiazirine (3) hemicarceplex, have been investigated in order to determine the effect of a hemicarcerand on the potential energy surface of an inner‐phase reaction. These hemicarceplexes have pentyl or phenethyl feet groups, three tetramethylene linkers and differ in the nature of one linker group X as follows: 1: X = (CH2)5; 2: X = (CH2)n (n = 2, 3, 4), (S,S)‐CH2CH[OC(CH3)O]CHCH2 ­and ortho‐CH2C6H4CH2; 3: X = (CH2)4. The effect of the linker group X on the structure of the phenyldiazirine hemicarceplexes was analyzed by MM2 force field calculations and leads to a change in the bending of the inner phase, which increases in the order (S,S)‐CH2CH[OC(CH3)O]CHCH2 > (CH2)4 > (CH2)3 > (CH2)2 > ortho‐CH2C6H4CH2 and to a shortening of the center‐to‐center distance between the two cavitands of the host, which decreases in the order (S,S)‐CH2CH[OC(CH3)O]CHCH2 < (CH2)4 < (CH2)3 < (CH2)2 < ortho‐CH2C6H4CH2. All hemicarceplexes show large red shifts of the diazirine n‐π*‐transition in their UV/Vis absorption spectra. From the red shifts and from plots of the n‐π*‐excitation energy of the free diazirines against the solvent polarizability P, the inner‐phase polarizability was estimated. P ranges from 0.39 to 0.58 and is larger than the polarizabilities of common organic solvents. A comparison of the activation parameters ΔH‡, TΔS‡, and ΔG‡ for the diazirine decomposition in the inner phase with those in the bulk phase shows that the hemicarcerand stabilizes the inner‐phase transition states enthalpically by ΔΔH‡ = 1.9–2.8 kcal/mol and destabilizes the transition states entropically by ΔTΔS‡ = 0.2 to 3.0 kcal/mol. The enthalpic stabilization is explained with dispersion interactions between the stretched C–N bonds in the transition state and the highly electron‐rich aryl units of the hemicarcerand. This is consistent with the high polarizability of the inner phase. The entropic destabilization of the inner‐phase transition states is explained with a greater loss of vibrational degrees of freedoms as the transition state is reached in the inner phase as compared to the more mobile bulk solvent cage. Furthermore, the entropic destabilization decreases with an increased bending of the inner phase. This is explained with an induced‐fit model. An increased hemicarcerand bending leads to an improved fit between the inner phase and the bend transition states, which reduces the loss of vibrational degrees of freedom as the transition states are reached. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of Spirocyclopropanated Analogues of Iprodione
Authors: Brackmann Farina , Es‐Sayed Mazen , de Meijere Armin
Published: May 2005

Methyl 1‐(tert‐butoxycarbonylamino)cyclopropanecarboxylate (9) was converted into the spirocyclopropanated five‐membered ring analogue 7a of Iprodione (1) in five steps with an overall yield of 28 %. The spirocyclopropanated five‐membered ring analogue 8a was prepared from tert‐butyl N‐[1‐(hydroxymethyl)cyclopropyl]carbamate (10) in five steps with an overall yield of 19 %. En route to the spirocyclopropanated six‐membered ring analogues of Iprodione (1), the oxalic acid diamides 5b and 6b could be obtained starting from 9 or 10 in 33 or 19 % yield, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Calix[5]‐ and Calix[8]arenes Bridged with Heterocycles
Authors: Konrad Serge , Näther Christian , Lüning Ulrich
Published: May 2005

Calix[5]arene (2) and calix[8]arene (4) reacted with bis(bromo­methyl)‐substituted heterocycles such as pyridine and 1,10‐phenanthroline to give [1+1] condensation products 10 and 16–18 (bridged bimacrocycles) and [2+1] dicalixarenes 11, 13 and 14, all of which were fully characterized. Although the bridging capability of both bridging units 5 and 6 is surprisingly similar, calix[5]arene (2) could only be bridged with the pyridine derivatives 5. With calix[8]arene (4), the 1,10‐phenanthroline bridging reagent 6 gave a cleaner product spectrum than the pyridine reagent 5. The 1,10‐phenanthroline‐bridged calix[8]arene 16 was characterized by X‐ray analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of Bromo‐ and Iodohydrins from Deactivated Alkenes by Use ofN‐Bromo‐ and N‐Iodosaccharin
Authors: Urankar Damijana , Rutar Irena , Modec Barbara , Dolenc Darko
Published: May 2005

N‐Bromo and N‐iodosaccharin react with electron‐deficient alkenes such as α,β‐unsaturated ketones, acids, esters and nitriles in aqueous organic solvents, yielding the corresponding halohydrins in good yields. The reactions take place at room temperature, mostly within short reaction times and with high antistereoselectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Highly Chemoselective Multicomponent Biginelli‐Type Condensations of Cycloalkanones, Urea or Thiourea and Aldehydes
Authors: Zhu Yu‐lin , Huang Shen‐lin , Pan Yuan‐jiang
Published: May 2005

The classical Biginelli reaction is considerably extended by use of cycloalkanones instead of 1,3‐dicarbonyl compounds. Use of TMSCl as a Lewis acid allowed one‐pot chemoselective multicomponent Biginelli reactions between cycloalkanones, urea or thiourea, and aldehydes. Under similar reaction conditions, thiourea exhibited different behavior to urea, and aliphatic aldehydes showed lower reactivity than aromatic aldehydes. A possible mechanism to account for the reaction is proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Total Synthesis of (±)‐Pumiliotoxin C: An Electrochemical Approach
Authors: Girard Nicolas , Hurvois Jean‐Pierre , Moinet Claude , Toupet Loic
Published: May 2005

The total stereoselective synthesis of the decahydroquinoline alkaloid (±)‐pumiliotoxin C (cis‐195A, 1) is described. The compound was prepared in 15 steps from the commercially available 4‐piperidone ethylene ketal 2, in an overall 5 % yield. New C–C bonds in the α position relative to the nitrogen atom were formed by the metalation of aminonitriles 4 and 15, which were themselves prepared electrochemically. The ease of this synthesis shows that the N‐aryl group is an efficient nitrogen‐protecting group that can be removed in the last step through a Birch dearomatization. In addition, the aryl substituent serves as an efficient activator of the nitrogen atom during the elaboration of aminonitriles 4 and 15. The oxygen atom of the keto carbonyl group in octahydroquinolinone 10 was removed by an unprecedented two‐step method involving a Shapiro reaction and a palladium‐catalyzed reduction of the intermediate alkene 13. Finally, the expected stereospecific alkylation–hydride reduction process of the cis‐fused aminonitrile 15 established the trans relationship between the propyl group at C‐2 and the methyl substituent at C‐5. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Absolute Configuration of the Fungal Metabolite Spirolaxine
Authors: Bava Adriana , Clericuzio Marco , Giannini Giuseppe , Malpezzi Luciana , Valdo Meille Stefano , Nasini Gianluca
Published: May 2005

The relative stereochemistry of the four stereocentres of spirolaxine 1, a bioactive 6,5‐spiroacetal phthalide secondary metabolite, was determined through single‐crystal X‐ray analysis. Its absolute configuration was determined by circular dichroism; the experimental spectrum of spirolaxine is in good agreement with that evaluated by means of DeVoe coupled‐oscillator calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Highly Efficient Catalytic Nitration of Phenolic Compounds by Nitric Acid with a Recoverable and Reusable Zr or Hf Oxychloride Complex and KSF
Authors: Shi Min , Cui Shi‐Cong , Yin Wan‐Po
Published: May 2005

Phenolic compounds can be nitrated with 60 % nitric acid (1.2 equiv.) in the presence of catalytic amounts of a Zr or Hf oxychloride complex and montmorillonite KSF to give the corresponding nitrated products in good yields in a heterogeneous catalytic system. The co‐catalyst and montmorillonite can be easily recovered and reused in the next batch of nitration. This is a practical process for the nitration of phenolic compounds in a clean way. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Why Do Peroxomolybdenum Complexes Chemoselectively Oxidize the Sulfur Centers of Unsaturated Sulfides and Sulfoxides? A DFT Analysis
Authors: Sensato Fabrício R. , Custodio Rogério , Longo Elson , Safont Vicent S. , Andrés Juan
Published: May 2005

The reasons why oxo‐peroxo molybdenum complexes chemoselectively oxidize unsaturated sulfides to the corresponding sulfoxides and these to sulfones without any epoxidation of the electron‐rich double bond were elucidated by transition state theory and density functional calculations at the B3LYP level. For the diperoxo model complex with the structure MoO(η2‐O2)2OPH3 and for allyl methyl sulfide as a model of unsaturated sulfides, the calculations show that the oxygen transfer process from the peroxomolybdenum complex to the sulfur center requires a lower free activation energy (ΔG‡ = 19.0 kcal mol–1) than the attack on the double bond moiety (ΔG‡ = 26.4 kcal mol–1) of the unsaturated sulfide. Subsequent oxidation of allyl methyl sulfoxide at the sulfinyl group to yield the corresponding sulfone also requires a lower activation energy (ΔG‡ = 21.5 kcal mol–1) thanthe corresponding epoxidation process (ΔG‡ = 27.7 kcal mol–1),yielding 2,3‐epoxypropyl methyl sulfoxide. These results unambiguously account for these complexes’ excellent chemoselectivity towards the sulfur groups in unsaturated sulfides and sulfoxides, as has been observed experimentally. On the basis of SCRF calculations, the level of chemoselectivity is predicted to diminish with increasing solvent polarity. Charge decomposition analysis and the orbital interaction model reveal that unsaturated sulfides with reaction sites carrying lone pair and π electrons behave as nucleophiles toward the electrophilic peroxo oxygen group. The origin of the chemoselectivity is ascribed to the fact that the electronic state related to the sulfur lone pair (HOMO) lies 1.2 eV above that associated with the π electrons (HOMO–1). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Estimation of charge trapping in bilayers of coducting polymers composed of polypyrrole and poly(N‐methylpyrrole)
Authors: Maksymiuk Krzysztof
Published: May 2005

Charge trapping effects were studied in bilayers of conducting polymers composed of poly(N‐methylpyrrole) (PMPy) and polypyrrole (PPy), by comparing redox charges of the polymer [Q(ox/red)] obtained by integration of cyclic voltammetric and chronoamperometric curves for single films and bilayers with variable thickness of both components. Charge trapping factors, TF, for PMPy(inner layer)/PPy(outer layer) bilayers were determined using the definition: TF = 1 ‐ Q(ox/red)/Q(ox/red)PPy where Q(ox/red) is redox charge of PPy in the bilayer, Q(ox/red)ppy relates to the charge for a single PPy film of the same thickness as that in the bilayer. Since the formal potential of PMPy is higher than that of PPy, the outer PPy film cannot be entirely reduced due to low conductivity of PMPy at negative potentials. The estimated charge trapping factor is independent of the outer layer thickness, it depends, however on the thickness of the inner film. For the reverse sequence of polymers, PPy/PMPy, charge trapping was not observed. Modification of the outer PPy layer by immobilized poly(4‐styrenesulfonate) anions changes the response of the bilayer due to low permeability of the cation‐exchanging outer polymer to anions. Therefore perchlorate anions compensating charge of PMPy film were found to be entrapped in the polymer matrix under conditions of cyclic voltammetry.
Use of different fluorochromes for monitoring protein elution and transfer
Authors: Szewczyk Boguslaw , Bienkowska‐Szewczyk Krystyna , Kozloff Lloyd M.
Published: May 2005

Protein molecular weight standards labeled with different fluorochromes were tested for their usefulness in following the protein transfer from sodium dodecyl sulfate‐polyacrylamide gels to nitrocellulose and for electro‐elution of proteins from polyacrylamide gels. Dichlorotriazynylaminofluorescein labeled proteins appear to be useful for both purposes as they are stable, their detection sensitivity was high (about 10 ng of protein on nitrocellulose) and the coupling of the fluorochrome did not appreciably change the molecular weight of any protein examined. On the other hand, proteins labeled with tetramethylrhodamine isothiocyanate, or its heterocyclic derivative, were of limited usefulness as standards. Labeled proteins of molecular weight below 20 kDa formed diffuse bands on gels. Therefore, these particular fluorescent protein standards appear to be useful in following the elution from gels, or as references on nitrocellulose, only for proteins larger than 20–25 kDa.
Sodium dodecyl sulfate electrophoresis in the first dimension and isoelectric focusing in the second dimension in a single thin‐layer gel, followed by activity stain for glycosyltransferases
Authors: Mukasa Hidehiko , Tsumori Hideaki , Shimamura Atsunari
Published: May 2005

A method has been developed for the two‐dimensional separation of proteins in a single thin‐layer gel, using sodium dodecyl sulfate‐polyacrylamide gel electrophoresis in the first dimension and isoelectric focusing in the second dimension. After two‐dimensional electrophoresis of concentrated culture supernatants from Streptococcus mutans, the gels were directly stained with Coomassie Brilliant Blue R‐250 for protein and with periodic acid‐Schiff base reagent for glycoprotein. Glycosyl‐transferases were detected by incubating the gels in a sucrose‐containing buffer, either by visual observation of white spots of the product polysaccharides or by periodic acid‐Schiff staining of the products. All the procedures, including the staining steps, were done in a single gellayer covalently bound to a glass plate. The efficient removal of sodium dodecyl sulfate and renaturation of glycosyltransferases in the gel layers rendered this a simplified and rapid method for the relative molecular mass and isoelectric point determinations in the crude preparations.
Heat release rates from samples of polymethlmethacrylate and polystyrene burning in normal air
Authors: Tewarson A.
Published: May 2005

Results are presented for mass generation rates of major combustion products (CO2, CO, total hydrocarbons and smoke particulates) and heat release rates from samples of polymethylmethacrylate and polystyrene burning in normal air under varying magnitudes of externally applied radiant heat flux. In the experiments mass generation rates of products and convective heat release rates are measured and, from heat and mass balance, actual and radiative rate of heat release, as well as heat that is not released due to incompleteness of combustion, are calculated. From the data, 99% of the rate of the theoretical heat release for complete combustion can be accounted for. In some cases the experimentally derived heat release rate was less than half that predicted from mass loss rate (assuming complete combustion). This ‘combustion efficiency’ decreased strongly with increasing externally applied radiant flux, and was always much lower for polystrene than for polymethylmethacrylate. At the ‘deal’ condition, defined as a condition where heat losses have been compensated and where the mass burning rate of polystyrene is 1.44 times the rate for polymethylmethacrylate, polystyrene generates 6.60 times more CO, 7.83 times more smoke particulates, and the radiative rate of heat release is 1.75 times more than that of polymethylmethacrylate.
Smoke characteristics of coal‐lined tunnel fires
Authors: Cashdollar Kenneth L. , Singer Joseph M. , Lee Calvin K. , Litton Charles D.
Published: May 2005

Characteristics of smoke particulates generated from a coal fire in a ventilated model tunnel were investigated by laser optical transmission and by electron microscopy. Average particle diameter and mass concentration of the smoke were determined as a function of the temperature and stoichimoetry of the coal tunnel fire. Smoke particle sizes ranged from 0.2 to 0.9 μm, with larger particle sizes associated with higher smoke concentrations. These coal smoke data are relevant to several aspects of underground mine safety including the development and location of smoke detection instruments, the understanding of the fire (toxic fume) hazard, and the development of new fire protection and control techniques.
Genetic admixture and asthma‐related phenotypes in Mexican American and Puerto Rican asthmatics
Authors: Salari Keyan , Choudhry Shweta , Tang Hua , Naqvi Mariam , Lind Denise , Avila Pedro C. , Coyle Natasha E. , Ung Ngim , Nazario Sylvette , Casal Jesus , Torres‐Palacios Alfonso , Clark Suzanne , Phong Angie , Gomez Ivan , Matallana Henry , Pérez‐Stable Eliseo J. , Shriver Mark D. , Kwok Pui‐Yan , Sheppard Dean , Rodriguez‐Cintron William , Risch Neil J. , Burchard Esteban González , Ziv Elad
Published: May 2005

Genetic association studies in admixed populations may be biased if individual ancestry varies within the population and the phenotype of interest is associated with ancestry. However, recently admixed populations also offer potential benefits in association studies since markers informative for ancestry may be in linkage disequilibrium across large distances. In particular, the enhanced LD in admixed populations may be used to identify alleles that underlie a genetically determined difference in a phenotype between two ancestral populations. Asthma is known to have different prevalence and severity among ancestrally distinct populations. We investigated several asthma‐related phenotypes in two ancestrally admixed populations: Mexican Americans and Puerto Ricans. We used ancestry informative markers to estimate the individual ancestry of 181 Mexican American asthmatics and 181 Puerto Rican asthmatics and tested whether individual ancestry is associated with any of these phenotypes independently of known environmental factors. We found an association between higher European ancestry and more severe asthma as measured by both forced expiratory volume at 1 second (r=−0.21, p=0.005) and by a clinical assessment of severity among Mexican Americans (OR: 1.55; 95% CI 1.25 to 1.93). We found no significant associations between ancestry and severity or drug responsiveness among Puerto Ricans. These results suggest that asthma severity may be influenced by genetic factors differentiating Europeans and Native Americans in Mexican Americans, although differing results for Puerto Ricans require further investigation. Genet. Epidemiol. 2005. © 2005 Wiley‐Liss, Inc.
A Functional Polymorphism in the IL - 10 Promoter Influences the Response After Vaccination With HBsAg and Hepatitis A *
Authors: Höhler Thomas , Reuss Esther , Freitag Christine M. , Schneider Peter M.
Published: May 2005

The immune response to hepatitis B surface antigen (HBsAg) is mostly genetically determined. Interleukin 10 (IL-10) is a central immunoregulatory cytokine with important effects on B-cells. We have studied the influence of

IL
-
10

promoter polymorphisms on the immune response to HBsAg and hepatitis A vaccination. We vaccinated 202 twin pairs in an open prospective study with a combined recombinant HBsAg/inactivated hepatitis A vaccine.

IL
-
10

promoter polymorphisms were investigated in all individuals and their influence on anti-HBs, and anti-HAV responsiveness was studied. In the multiple regression analysis accounting for smoking, gender, body mass index and age, the

ACC

haplotype (−

1082

, −

819

and −

592

) had a strong influence on anti-HBs production. Individuals carrying the

ACC

haplotype had anti-HBs titres almost twice as high as individuals without this haplotype. In contrast, anti-HAV production was suppressed by the presence of the −1082A allele in comparison with individuals homozygous for the −1082G allele. The contribution of the shared

IL
-
10

promoter haplotype accounted for 27% of the genetic influence on anti-HBs antibody response.
In conclusion
, genetic variability in the

IL
-
10

promoter is an important modulator of the immune response against hepatitis viral antigens. (Hepatology 2005.)