bluuebunny/crossref_metadata_2025 huggingface dataset:
Three dimensional nanoporous density graded materials formed by optical exposures through conformable phase masks
Authors: Jeon Seokwoo , Nam Yun-Suk , Shir Daniel Jay-Lee , Rogers John A. , Hamza Alex
Published: December 2006

Control of spectral bandwidth, illumination angle, and degree of collimation of light passing through a conformable phase mask provides an experimentally simple route to nanostructured materials with well defined depth gradients in density (i.e., porosity). In this approach, the illumination conditions define spatial variations in visibility of the distributions of intensity. Exposure of photopolymers to these intensity distributions generates, after developing, solid structures with geometries that compare well with expectation based on modeling of the optics. A range of structures is demonstrated, some of which have potential applications ranging from targets for laser fusion to vehicles for controlled release of chemicals.
Molecular tracer diffusion in thin azobenzene polymer layers
Authors: Mechau N. , Saphiannikova M. , Neher D.
Published: December 2006

Translational diffusion of fluorescent tracer molecules in azobenzene polymer layers is studied at different temperatures and under illumination using the method of fluorescence recovery after photobleaching. Diffusion is clearly observed in the dark above the glass transition temperature, while homogeneous illumination at 488nm and 100mW∕cm2 does not cause any detectable diffusion of the dye molecules within azobenzene layers. This implies that the viscosity of azobenzene layers remains nearly unchanged under illumination with visible light in the absence of internal or external forces.
Toward the understanding of DNA fluorescence: The singlet excimer of cytosine
Authors: Olaso-González Gloria , Roca-Sanjuán Daniel , Serrano-Andrés Luis , Merchán Manuela
Published: December 2006

By using the multiconfigurational second-order perturbation method CASPT2, including corrections for the basis set superposition error, the lowest-singlet excited state of the face-to-face π-stacked cytosine homodimer is revealed to be bound by about half an eV, being the source of an emissive feature consistent with the observed redshifted fluorescence.
Exciton splitting and carrier transport across the amorphous-silicon/polymer solar cell interface
Authors: Gowrishankar Vignesh , Scully Shawn R. , McGehee Michael D. , Wang Qi , Branz Howard M.
Published: December 2006

The authors study exciton splitting at the interface of bilayer hybrid solar cells to better understand the physics controlling organic-inorganic device performance. Hydrogenated amorphous silicon (a-Si:H)∕poly(3-hexylthiophene) (P3HT) and a-Si:H∕poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylenevinylene) (MEH-PPV) solar cells show photoresponse dominated by exciton production in the polymer. The a-Si:H∕P3HT devices are nearly as efficient as titania/P3HT cells. However, the a-Si:H∕MEH-PPV system has much lower photocurrent than a-Si:H∕P3HT, likely due to inefficient hole transfer back to the MEH-PPV after energy transfer from MEH-PPV to a-Si:H.
Room-temperature nondispersive hole transport in a discotic liquid crystal
Authors: Kastler Marcel , Laquai Frédéric , Müllen Klaus , Wegner Gerhard
Published: December 2006

The authors report on room-temperature nondispersive hole transport in films of a discotic liquid crystalline hexa-peri-hexabenzocoronene derivative studied by the time-of-flight technique. Hole mobilities in the order of 10−3cm2∕V−1s−1 have been determined and results of field- and temperature-dependent measurements could be well explained within the concept of charge transport by hopping in a one-dimensional manifold of transport sites formed by the columns of the discotic liquid crystal.
Electrically controlled negative refraction in a nematic liquid crystal
Authors: Pishnyak Oleg P. , Lavrentovich Oleg D.
Published: December 2006

The authors demonstrate electrically controlled negative refraction at the interface between an isotropic material and a uniaxial nematic liquid crystal, in which the optic axis is designed to make a large angle with the interface. Depending on the applied voltage, the refracted beam is either on the opposite side of the interface normal as compared to the incident beam (positive refraction) or on the same side (negative refraction).
Low Luminosity Galaxies
Authors: Davies J. I. , Sabatini S. , Roberts S.
Published: December 2006

Low luminosity (dwarf) galaxies play a crucial role in our current theories of galaxy and large scale structure formation. In the hierarchical picture they are the building blocks from which other structures form. These theories in their basic form overpredict the numbers of small dark matter halos (dwarf galaxies?) unless some form of star formation supression is invoked. In this paper we describe observations of dwarf galaxies in a range of different environments. We find that there are far too few dwarf galaxies in low density environments to be compatible with the theories. These observations are not consistent with an environment-independent mechanism suppressing dwarf galaxy formation. It is also not clear how these mechanisms can supress star formation if dwarf galaxies have large mass-to-light ratios (≈100). Either the whole idea of hierarchical galaxy formation has to be rejected or other environmentally dependent physical processes have to be invoked. We suggest that small, gas-rich dI galaxies have their evolution rapidly advanced as they move into the dense cluster environment.
Local Group Velocity from the PSCz and BTP Surveys
Authors: D'Mellow Kenton J. , Saunders Will ,   PSCz/BTP Teams
Published: December 2006

We present a brief overview and preliminary measure of the Local Group velocity, using the PSCz survey together with its recently completed extension into the Galactic plane, the Behind The Plane (BTP) survey. The addition of the BTP has increased the total sky coverage from 84% to 93%, drastically reducing the systematic uncertainty in the direction of the local gravitational pull caused by incomplete sky coverage. We present methods that self-consistently determine the acceleration in the presence of redshift distortions. Preliminary results suggest that the dipole converges within the survey limiting depth. There is a large, but only marginally significant, component to the dipole arising at 180–200 h–1 Mpc.
The Canis Major Dwarf Galaxy
Authors: Lewis Geraint F. , Ibata Rodrigo A. , Irwin Michael J. , Martin Nicolas F. , Bellazzini Michele , Conn Blair
Published: December 2006

Recent observational evidence suggests that the Sagittarius dwarf galaxy represents the only major ongoing accretion event in the Galactic halo, accounting for the majority of stellar debris identified there. This paper summarises the recent discovery of another potential Milky Way accretion event, the Canis Major dwarf galaxy. This dwarf satellite galaxy is found to lie just below the Galactic plane and appears to be on an equatorial orbit. Unlike Sagittarius, which is contributing to the Galactic halo, the location and eventual demise of Canis Major suggests that it represents a building block of the thick disk.
The Future of Astronomy and Physical Cosmology
Authors: Peebles P. James E.
Published: December 2006

Astronomy and cosmology have a substantial observational and theoretical basis, but our standard model still depends on some working assumptions. I comment on the nature of the issues behind these assumptions, the guidance we might find from past resolutions of such issues, and the models we might consider for the future of research in this subject.
Organophosphorus Compounds. II. Preparation of Phosphonic Acid Esters using the Dicyclohexylcarbodiimide Reagent
Authors: Maynard JA , Swan JM
Published: December 2006

Mono- and diesters of phosphonic acids are
conveniently prepared by reaction of a phosphonic acid with appropriate
quantities of NN'-dicyclohexylcarbodiimide and an alcohol or phenol in pyridine
solution.
The photolysis of dialkyl sulphides, disulphides, and trisulphides
Authors: Milligan B , Rivett DE , Savige WE
Published: December 2006

Several dialkyl mono-, di-, and
trisulphides have been irradiated in the absence of solvents with ultraviolet
light (2537 Ǻ), with direct sunlight, and with y-rays; the irradiation
products were identified and estimated by gas chromatography. Trisulphides
rapidly gave a mixture of di-, tri-, and tetrasulphides by a disproportionation
reaction initiated by S-S fission. Monosulphides and symmetrical disulphides
were much more stable, although both gave products via C-S fission. The former
yielded the corresponding disulphide and hydrocarbon, while the latter gave
mainly the corresponding tri- and tetrasulphides with traces of mono- sulphides
and hydrocarbons.

Study of these results and those concerned
with disulphide interchange and the dismutation of trisulphides leads to the
conclusion that, if both types of fission are possible in the irradiation of a
simple dialkyl polysulphide, then S-S fission occurs at the expense of C-S
fission.
Synthesis and crystal structure of 7,7a,8,9,11,11a-Hexahydro-7,7,10-trimethyl-1,10-epoxy-10H-benz[de]anthracen-6-ol
Authors: Cannon JR , McDonald IA , Sierakowski AF , White AH , Willis AC
Published: December 2006

3-Methyl-3-(4?-methylpent-3?-enyl)-3H-naphtho[2,1-b]pyran-9-ol
and -8- ol were prepared by condensation of citral with naphthalene-2,7-diol
and -2,6-diol respectively. The 8-hydroxy compound sublimed unchanged but on
heating the 9-hydroxy isomer cyclization occurred yielding
7,7a,8,9,11,11a-hexahydro-7,7,10-trimethyl-1,10-epoxy-10H- benz[de]anthracen-6-ol.
Crystals of the cyclization product were found to be monoclinic [C2/c, a =
21.934(5), b = 8.713(2), c = 19.849(4) Ǻ; β = 127.78(2)�; Z = 81. The
crystal structure was determined at 295 K from diffractometer data [1350
reflections with I > 2σ(I)] and refined to a residual of 0.052.
Correlations between retention volume and molecular size parameters in gel permeation chromatography of small molecules
Authors: Shanks RA
Published: December 2006

Gel permeation columns of
Bio Beads S-X8 have been used to provide separation of oligomers and other
small organic molecules. Results show successful separations up to molecular
weight c. 600. The retention times of compounds have been correlated with the largest
molecular dimension of the molecules and also with molar volumes.
Chemical Examination of Local Plants. XIV. Triterpenoids From the Leaves of Egyptian Callistemon lanceolatus
Authors: El-Garby  Younes M
Published: December 2006

The light petroleum extract
of the leaves of Callistemon lanceolatus yielded
ursolic and oleanolic acid together with uvaol, while the ether extract
afforded 2α-hydroxyursolic acid and a new triterpenetriol
identified as 2α-hydroxyuvaol. The methanol extract contained glucose and
sucrose and a mixture of saponins, acid hydrolysis of which yielded
2α-hydroxyursolic acid and 2α-hydroxyuvaol as aglycones.
Photoelectron spectroscopic studies of the higher alcohols
Authors: Peel JB , Willett GD
Published: December 2006

The He I photoelectron
spectra of some of the higher alcohols have been measured. These include the
propyl, butyl and two pentyl alcohols. The time-averaged spectra are presented
in an intensity-corrected form, and with the assistance of SPINDO calculations
a reasonable assignment of the ionization potentials is given. The relatively
noise-free spectra are of sufficient quality to discern overlapping bands and
the measured band intensities correlate well with the density of states
resulting from the SPINDO calculations.
Binuclear metal(II) complexes of 1,3-diphenyltriazene : The crystal and molecular structures of the nickel(II), palladium(II) and copper(II) derivatives
Authors: Corbett M , Hoskins BF , McLeod NJ , O'Day BP
Published: December 2006

The crystal and molecular structures have been determined, by single-crystal X-ray methods, for
each of the isomorphous set of divalent binuclear metal derivatives of 1,3-diphenyltriazene,
abbreviated as dptH, [M(dpt)2]2 where M = Ni, Pd, and Cu. The crystals are composed of discrete
molecular units, of composition M2(dpt)4, which have a syn-syn structure analogous to that of
copper(II) acetate monohydrate with pairs of closely separated metal atoms held together by the
terminal nitrogen atoms of four ligand groups in such a way that the environment of each metal
atom is almost square-planar. The interatomic distances between the pairs of metal atoms, 2.395(3),
2563(1), and 2.441(2) Ǻ for the Ni, Pd, and Cu compounds, are strongly suggestive of metal-metal
bonding. The two N4-planes are almost parallel but the two sets of coordinating nitrogen atoms
are twisted markedly from the eclipsed configuration, the average angle of rotation being about
15°. Crystals of each complex are triclinic with space group P 1. The unit cell parameters in the order
of a, b, c, α, β, and γ are 10.335(3), 15.84(1), 13.546(3)& 100.48(5), 94.47(2), 102.57(3)° for
Ni2(dpt)4; 10.486(1), 15.791(2), 13.751(1)Ǻ, 99.48(1), 93.61(1), 104.37(1)° for Pd2(dpt)4;
10.373(3), 15.916(5), 13.612(3) Ǻ, 99.51(2), 94.85(3), 102.33(2)° for Cu2(dpt)4. The structure of
the nickel complex was solved by the Patterson-Fourier method and the atomic parameters found
for this structure were used as the basis of the structure determinations of the isomorphous copper
and palladium compounds. All three structures were refined by a block-diagonal least-squares
method using 3300 (photographic data) 4065 (counter) and 2753 (counter) independent non-zero
terms for the nickel(II), palladium(II) and copper(II) compounds respectively, converging with
R values 0.13 (isotropic), 0.056 (anisotropic) and 0.069 (isotropic) respectively.
Solvent-dependent circular dichroism of trans-disubstituted Bis(R-propane-1,2-diamine)cobalt(III) complexes
Authors: Hawkins CJ , Lawrance GA , Peachey RM
Published: December 2006

The circular dichroism
spectra of trans-disubstituted bis(R-propane- 1,2-diamine)cobalt(III) complexes
are reported for an extended series of solvents. The observed variations in the
spectra of the dichloro and dibromo complexes are analysed in terms of stereoselective
solvation at the diamine N-H protons, and also the ion association between the
complexes and their counter-ions. The solvation of these dihalo complexes,
which was studied by p.m.r., showed a preference for
hydrogen-bond formation with the equatorial N-H protons, rendering the donor
nitrogens asymmetric and thus introducing a new source of dissymmetry close to
the metal ion chromophore. This affected a decrease in the positive rotational
strength of the 1A1g → 1Eg (D4h)
transition, and a positive contribution to the rotational strength of the 1A1g
→ 1A2g (D4h) component. Ion association
of the dihalo complexes was evaluated by a comparison of the circular dichroism
of the tetraphenylborate and halide salts. ��� The tendency for ion association was much
greater for the tripositive diammine complex. However, stereospecific solvation
was of little importance and the circular dichroism spectra did not show any
marked solvent dependence for the tetraphenylborate salt.
Reactions of organic compounds in adsorbed monolayers. I. Ozonation of 3,7-dimethyloctyl acetate
Authors: Beckwith ALJ , Bodkin CL , Duong T
Published: December 2006

Oxidation with ozone of
3,7-dimethyloctyl acetate (7) adsorbed on silica gel, alumina or barium
sulphate proceeds in good yield and affords mainly the 7-hydroxy compound (8)
and the 7-nor-ketone (9). Minor products include the 3-alcohol (10) and the
3,7-diol (11). The reaction involves interaction of gaseous ozone with the
adsorbed organic substrate. The relative yields of the various products are
related to the substrate loading. The results show that the very high
regioselectivity exhibited by the reaction when conducted under suitable
experimental conditions may be attributed to the mutual steric effect of one
molecule upon the other in the adsorbed monolayer.
Trimethyl(3-Oxido-1-Oxoinden-2-Yl)Ammonium, a New 1,4-Dipolar Ylide
Authors: Horn E , Jones GP , Prager RH , Snow MR , Ward AD
Published: December 2006

Reaction of isobenzofuran-1(3H)-one ( phthalide ) and its derivatives with dimethylformamide dimethyl acetal in the presence of base gives small amounts (c. 10%)1 of the ylid trimethyl (3-oxido-1-oxoinden-2- yl )ammonium (3). The same compound is formed in higher yield from the corresponding 3-dimethylaminomethyleneisobenzofuran-1(3H)-one. Support for this structure comes from chemical degradation and its mode of synthesis, but relies mainly on X-ray crystallography. The title compound crystallizes as clear prisms in the monoclinic space group P21/n with a 15.992(2), b 9.329(4), c 7.112(3)Ǻ, β 90.15(3)° and Z 4. The structural final refinement of a full-matrix least-squares calculation converged with R 0.044 and Rw 0.045.
Synthetic Studies on Wedeligenin: Preparation of 3-Hydroxy-Substituted Decalincarbonitriles as a Model for 'A Ring' Annulation
Authors: Macleod JK , Molinski TF
Published: December 2006

Six new 3-hydroxydecalincarbonitriles were synthesized by employing an annulation strategy involving intramolecular alkylation of 5-bromoalkyl substituted malononitriles or acetonitriles. 2-Allyl-2-methylcyclohexanone was condensed with malononitrile to give the dialkylcyclohexylidenepropanedinitrile (14). Alternatively, Horner-Emmons- Wittig condensation of the same ketone with diethyl cyanomethylphosphonate gave the corresponding acetonitrile (28). Reduction of the dinitrile with sodium borohydride to give a mixture of cis and trans cyclohexyl malononitriles followed by epoxidation of the allyl substituent, gave a separable mixture of four epoxides, two of which, (17) and (19), were site-selectively ring-opened to the bromohydrins. Each bromohydrin was quantitatively converted into its respective O- trimethylsilyl bromohydrin ether and cyclized to afford the respective decalindicarbonitriles (6) and (7). The substituted acetonitrile (28) was reduced to a 5 : 2 mixture of the corresponding cyclohexylacetonitriles with magnesium in methanol and the products were carried through to their respective O- trimethylsilyl bromohydrin ethers and cyclized to afford decalincarbonitriles (8)-(11). The structure and stereochemistry of the new decalins were assigned by 1H and 13C n.m.r. spectroscopy.
Potential Antimalarials. XII. 4-Chloro-3-(substituted amino)methyl-5-[7-bromo (and 7-trifluoromethyl)-1,5-naphthyridin-4-ylamino]biphenyl-2-ols and 4-Chloro-3-(substituted amino)methyl-5-(7-trifluoromethyl-quinazolin-4-ylamino)biphenyl-2-ols
Authors: Barlin GB , Jiravinyu C
Published: December 2006

The mono- Mannich bases 3-(t- butylamino )methyl-4?-chloro-, 3-(4- benzylpiperidin-1-yl)methyl-4′-chloro-, 3-(4-benzylpiperazin-1- yl )methyl-4′-chloro-, 4′-chloro-3-diethylaminomethyl-, 4′-chloro-3-(pyrrolidin-1-yl)methyl-, 4′-chloro-3-(piperidin-1-yl)methyl- and 4′-chloro-3-(3- and 4- methylpiperidin-1-yl)methyl-5-[7-bromo (and 7- trifluoromethyl )-1,5-naphthyridin-4-ylamino]- biphenyl-2-ol, and the corresponding substituted 5-(7-trifluoromethylquinazolin-4-ylamino)bi- phenyl-2-ols, have been prepared by condensation of the 5-amino-3-(N- substituted aminomethyl )-4′-chlorobiphenyl-2-ols and the appropriate 4-chloro heterocycle. The antimalarial activity of these products against the chloroquine-sensitive isolate (FCQ-27) of Plasmodium falciparum revealed that the 1,5-naphthyridines reported here were less active than the corresponding di-Mannich bases, e.g. (6), derived from 4-[7- bromo (and 7-trifluoromethyl)-1?,5′-naphthyridin-4′-ylamino]phenol, a feature not shared by the corresponding quinazolines.
The Synthesis of Some Ethers and Mixed Ether Esters of Glycerol
Authors: Joll CA , Mortimer BC , Redgrave TG , Stick RV
Published: December 2006

The syntheses of various monoethers of glycerol, the derived diesters and two triethers are reported. As well, one of the chiral ether diesters of glycerol has been prepared in both optically active forms.
The Synthesis of Some Carbohydrate-Derived Precursors to Tylonolide, the Aglycon of the Antibiotic Tylosin
Authors: Hughes AB , Stick RV , Tilbrook DMG
Published: December 2006

Treatment of methyl 2,3-anhydro-4,6-O-benzylidene-α-D-alloside with the anion derived from trimethyl(prop-1-ynyl)silane, allylmagnesium chloride or isobutenylmagnesium chloride introduces a three- or four- carbon substituent at C2 of the sugar. In each case, a hydroboration-oxidation sequence helps convert the centre of unsaturation in the new substituent into a carboxylic acid residue. Subsequent manipulations allow the introduction ofanother carbon at C6 of the sugar to give a highly functionalized precursor to the C1-C9 fragment of tylonolide, the aglycon of the antibiotic tylosin. Attempts at the introduction of an axial methyl group at C4 of the extended sugar also described.
Dicopper(II) Complexes of Spiro Macrobicycles With Aza and Thia Aza Donor Sets
Authors: Bernhardt PV , Comba P , Gahan LR , Lawrance GA
Published: December 2006

Reaction of the dicopper (II) complex of the binucleating ligand 5,5- bis (4-amino-2-azabutyl)-3,7-diazanonane-1,9-diamine with nitroethane and formaldehyde in water gives the respective macrobicyclic and macromonocyclic binucleating ligands 7,21-dimethyl-7,21-dinitro-2,5,9,12,16,19,23,26-octaazaspiro[13.13] heptacosane and 6,6-bis(4- amino-2-azabutyl)-13-methyl-13-nitro-1,4,8,11-tetraazacyclotetradecane , both as their dicopper (II) complexes. Similarly, condensation of the dicopper (II) complex of 5,5-bis(4-amino- 2-thiabutyl)-3,7-dithianonane-1,9-diamine with nitroethane and formaldehyde results in the binucleating macrobicycle 7,21-dimethyl- 7,21-dinitro-2,12,16,26-tetrathia-5,9,19,23-tetraazaspiro[13.13]-heptacosane. Physical properties of all complexes are reported and comparisons with mononuclear relatives are made. Structural parameters derived from electron paramagnetic resonance spectra are discussed.
The Synthesis of Some Esters of Glycerol With Special Attention to the Problem of Acyl Migration
Authors: Cockman SJ , Joll CA , Mortimer BC , Redgrave TG , Stick RV
Published: December 2006

Various triglycerides have been prepared by the acylation of either cis-1,3-O-benzylideneglycerol or 2,3-O-isopropylideneglycerol, followed by removal of the protecting group and acylation of the resultant diol. Alternatively, acylation of dihydroxyacetone, reduction of the intermediate ketone with sodium cyanoborohydride (pH 4) and acylation of the resultant alcohol also provide triglycerides in good yields. In some of these esters of glycerol, 13C n.m.r . spectroscopy (125.7 MHz) was used to monitor potential acyl migration. Finally, 2-halopyridinium salts were investigated as an alternative to the normal dicyclohexylcarbodiimide/dimethylaminopyridine couple for glycerol esterification.
The Chlorination of Some 4-Chloro-2,6-dimethylphenols. Some Addition Reactions of Substituted 4,6-Dichloro-2,6-dimethylcyclohexa-2,4-dienones
Authors: Gordon JLM , Hartshorn MP , Martyn RJ , Robinson WT , Wright GJ
Published: December 2006

Reactions of 4,6-dichlorocyclohexa-2,4dienone (4c) with chlorine in acetic acid and with chlorine in acetic acid containing sodium acetate are described, as are the corresponding reactions for a mixture of the 4,5,6-trichloro-(4b) and 3,4,6-trichloro-cyclohexa-2,4-dienone (5b). X-Ray crystal structures are reported for compounds (3b), (7), (9b), (11) and (13).
Expression of endothelial and inducible nitric oxide synthases is modulated in the endometrium of cyclic and early pregnant mares
Authors: Welter H. , Bollwein H. , Weber F. , Rohr S. , Einspanier R.
Published: December 2006

The expression of the endothelial and inducible nitric oxide synthases (eNOS and iNOS, respectively) was examined in the endometrium of cyclic and pregnant mares by real-time polymerase chain reaction and immunohistology. The concentration of eNOS mRNA varied throughout the oestrous cycle, with significantly higher transcripts on Day 5 of the oestrous cycle (P < 0.05), whereas iNOS transcription did not change significantly over time (P > 0.05). In early pregnant mares both eNOS and iNOS mRNA increased between Days 12 and 15 (P < 0.05). In cyclic mares, eNOS protein was detected immunocytochemically in endometrial epithelia, the basement membrane, the endothelial layer and smooth muscle cells of the vasculature. Using immunocytochemical methods, iNOS protein was undetectable in the endometrium of cyclic mares but could be demonstrated in pregnant mares. Endometrial epithelia of pregnant mares were immunopositive for both proteins with a more intense labelling for iNOS. Thus, the present study describes for the first time the modulation and spatial distribution of eNOS and iNOS expression during the oestrous cycle and early pregnancy, suggesting that ovarian steroids are differently involved in the regulation of each NOS. Localisation of eNOS protein in endometrial epithelia and various vascular components indicates that this isoform may be involved in the regulation of endometrial cyclicity. The presence and increase of both forms of NOS during early gestation suggest a role for them in the control of endometrial vascular bed and glandular activity to provide a suitable microenvironment for successful pregnancy.
Genetics and imaging to assess oocyte and preimplantation embryo health
Authors: Warner C. M. , Newmark J. A. , Comiskey M. , De Fazio S. R. , O'Malley D. M. , Rajadhyaksha M. , Townsend D. J. , McKnight S. , Roysam B. , Dwyer P. J. , DiMarzio C. A.
Published: December 2006

Two major criteria are currently used in human assisted reproductive technologies (ART) to evaluate oocyte and preimplantation embryo health: (1) rate of preimplantation embryonic development; and (2) overall morphology. A major gene that regulates the rate of preimplantation development is the preimplantation embryo development (Ped) gene, discovered in our laboratory. In mice, presence of the Ped gene product, Qa-2 protein, results in a fast rate of preimplantation embryonic development, compared with a slow rate of preimplantation embryonic development for embryos that are lacking Qa-2 protein. Moreover, mice that express Qa-2 protein have an overall reproductive advantage that extends beyond the preimplantation period, including higher survival to birth, higher birthweight, and higher survival to weaning. Data are presented that suggest that Qa-2 increases the rate of development of early embryos by acting as a cell-signalling molecule and that phosphatidylinositol-3′ kinase is involved in the cell-signalling pathway. The most likely human homologue of Qa-2 has recently been identified as human leukocyte antigen (HLA)-G. Data are presented which show that HLA-G, like Qa-2, is located in lipid rafts, implying that HLA-G also acts as a signalling molecule. In order to better evaluate the second criterion used in ART (i.e. overall morphology), a unique and innovative imaging microscope has been constructed, the Keck 3-D fusion microscope (Keck 3DFM). The Keck 3DFM combines five different microscopic modes into a single platform, allowing multi-modal imaging of the specimen. One of the modes, the quadrature tomographic microscope (QTM), creates digital images of non-stained transparent cells by measuring changes in the index of refraction. Quadrature tomographic microscope images of oocytes and preimplantation mouse embryos are presented for the first time. The digital information from the QTM images should allow the number of cells in a preimplantation embryo to be counted non-invasively. The Keck 3DFM is also being used to assess mitochondrial distribution in mouse oocytes and embryos by using the k-means clustering algorithm. Both the number of cells in preimplantation embryos and mitochondrial distribution are related to oocyte and embryo health. New imaging data obtained from the Keck 3DFM, combined with genetic and biochemical approaches, have the promise of being able to distinguish healthy from unhealthy oocytes and embryos in a non-invasive manner. The goal is to apply the information from our mouse model system to the clinic in order to identify one and only one healthy embryo for transfer back to the mother undergoing an ART procedure. This approach has the potential to increase the success rate of ART and to decrease the high, and undesirable, multiple birth rate presently associated with ART.
Sperm-mediated gene transfer
Authors: Lavitrano Marialuisa , Busnelli Marco , Cerrito Maria Grazia , Giovannoni Roberto , Manzini Stefano , Vargiolu Alessia
Published: December 2006

Since 1989, a new method for the production of transgenic animals has been available, namely sperm-mediated gene transfer (SMGT), based on the intrinsic ability of sperm cells to bind and internalise exogenous DNA molecules and to transfer them into the oocyte at fertilisation. We first described the SMGT procedure in a small animal model, with high efficiency reported in the mouse. In addition, we successfully adapted and optimised the technique for use in large animals; it was, in fact, highly efficient in the generation of human decay accelerating factor transgenic pig lines, as well as multigene transgenic pigs in which three different reporter genes, namely enhanced green fluorescent protein, enhanced blue fluorescent protein and red fluorescent protein, were introduced. The major benefits of the SMGT technique were found to be its high efficiency, low cost and ease of use compared with other methods. Furthermore, SMGT does not require embryo handling or expensive equipment. Sperm-mediated gene transfer could also be used to generate multigene transgenic pigs that would be of benefit as large animal models for medical research, for agricultural and pharmaceutical applications and, in particular, for xenotransplantation, which requires extensive genetic manipulation of donor pigs to make them suitable for grafting to humans.
Control of pest mammals for biodiversity protection in Australia. I. Patterns of control and monitoring
Authors: Reddiex Ben , Forsyth David M. , McDonald-Madden Eve , Einoder Luke D. , Griffioen Peter A. , Chick Ryan R. , Robley Alan J.
Published: December 2006

Foxes, wild dogs, feral cats, rabbits, feral pigs and feral goats are believed to have deleterious impacts on native biodiversity in Australia. However, although considerable resources have been expended controlling these six species, little is known about national patterns and costs of control and monitoring. We therefore conducted a survey of pest-control operations undertaken by conservation-focused organisations in Australia. A total of 1306 control operations were reported, with most conducted during 1998–2003: there was little information prior to 1990. Foxes and rabbits were the most, and feral cats the least, frequently controlled pest species. The total area on which control was undertaken in 2003, the year for which most information was available, ranged from ~0.4 × 104 km2 for feral cats to ~10.7 × 104 km2 for foxes. A wide range of techniques and intensities were used to control each of the six species. The estimated cost of labour expended on control in 2003 ranged from $0.4 × 106 for feral cats to $5.3 × 106 for foxes. Monitoring of the pest or biodiversity occurred in 50–56% of control actions in which foxes, wild dogs and feral cats were targeted, but only 22–26% of control actions in which rabbits, feral pigs and feral goats were targeted. Our results are discussed in relation to previous studies of pest animal control and monitoring in Australia.
Mechanism of tRNA-dependent editing in translational quality control
Authors: Ling Jiqiang , Roy Hervé , Ibba Michael
Published: December 2006

Protein synthesis requires the pairing of amino acids with tRNAs catalyzed by the aminoacyl-tRNA synthetases. The synthetases are highly specific, but errors in amino acid selection are occasionally made, opening the door to inaccurate translation of the genetic code. The fidelity of protein synthesis is maintained by the editing activities of synthetases, which remove noncognate amino acids from tRNAs before they are delivered to the ribosome. Although editing has been described in numerous synthetases, the reaction mechanism is unknown. To define the mechanism of editing, phenylalanyl-tRNA synthetase was used to investigate different models for hydrolysis of the noncognate product Tyr-tRNA
Phe
. Deprotonation of a water molecule by the highly conserved residue βHis-265, as proposed for threonyl-tRNA synthetase, was excluded because replacement of this and neighboring residues had little effect on editing activity. Model building suggested that, instead of directly catalyzing hydrolysis, the role of the editing site is to discriminate and properly position noncognate substrate for nucleophilic attack by water. In agreement with this model, replacement of certain editing site residues abolished substrate specificity but only reduced the catalytic efficiency of hydrolysis 2- to 10-fold. In contrast, substitution of the 3′-OH group of tRNA
Phe
severely impaired editing and revealed an essential function for this group in hydrolysis. The phenylalanyl-tRNA synthetase editing mechanism is also applicable to threonyl-tRNA synthetase and provides a paradigm for synthetase editing.
IL-33, the IL-1-like cytokine ligand for ST2 receptor, is a chromatin-associated nuclear factorin vivo
Authors: Carriere Virginie , Roussel Lucie , Ortega Nathalie , Lacorre Delphine-Armelle , Americh Laure , Aguilar Luc , Bouche Gérard , Girard Jean-Philippe
Published: December 2006

Recent studies indicate that IL-1α functions intracellularly in pathways independent of its cell surface receptors by translocating to the nucleus and regulating transcription. Similarly, the chromatin-associated protein HMGB1 acts as both a nuclear factor and a secreted proinflammatory cytokine. Here, we show that IL-33, an IL-1-like cytokine that signals via the IL-1 receptor-related protein ST2 and induces T helper type 2-associated cytokines, is an endothelium-derived, chromatin-associated nuclear factor with transcriptional repressor properties. We found that IL-33 is identical to NF-HEV, a nuclear factor preferentially expressed in high endothelial venules (HEV), that we previously characterized. Accordingly,in situhybridization demonstrated that endothelial cells constitute a major source of IL-33 mRNA in chronically inflamed tissues from patients with rheumatoid arthritis and Crohn's disease. Immunostaining with three distinct antisera, directed against the N-terminal part and IL-1-like C-terminal domain, revealed that IL-33 is a heterochromatin-associated nuclear factor in HEV endothelial cellsin vivo. Association of IL-33 with heterochromatin was also observed in human and mouse cells under living conditions. In addition, colocalization of IL-33 with mitotic chromatin was noted. Nuclear localization, heterochromatin-association, and targeting to mitotic chromosomes were all found to be mediated by an evolutionarily conserved homeodomain-like helix–turn–helix motif within the IL-33 N-terminal part. Finally, IL-33 was found to possess transcriptional repressor properties, associated with the homeodomain-like helix–turn–helix motif. Together, these data suggest that, similarly to IL1α and HMGB1, IL-33 is a dual function protein that may function as both a proinflammatory cytokine and an intracellular nuclear factor with transcriptional regulatory properties.
The zinc-finger antiviral protein recruits the RNA processing exosome to degrade the target mRNA
Authors: Guo Xuemin , Ma Jing , Sun Jing , Gao Guangxia
Published: December 2006

Zinc-finger antiviral protein (ZAP) is a host antiviral factor that specifically inhibits the replication of Moloney murine leukemia virus (MLV) and Sindbis virus (SIN) by preventing accumulation of the viral mRNA in the cytoplasm. In previous studies, we demonstrated that ZAP directly binds to its specific target mRNAs. In this article, we provide evidence indicating that ZAP recruits the RNA processing exosome to degrade the target RNA. ZAP comigrated with the exosome in sucrose or glycerol velocity gradient centrifugation. Immunoprecipitation of ZAP coprecipitated the exosome components.
In vitro
pull-down assays indicated that ZAP directly interacted with the exosome component hRrp46p and that the binding region of ZAP was mapped to amino acids 224–254. Depletion of the exosome component hRrp41p or hRrp46p with small interfering RNA significantly reduced ZAP's destabilizing activity. These findings suggest that ZAP is a
trans
-acting factor that modulates mRNA stability.
Isolation and functional characterization of murine prostate stem cells
Authors: Lawson Devon A. , Xin Li , Lukacs Rita U. , Cheng Donghui , Witte Owen N.
Published: December 2006

The ability to isolate prostate stem cells is essential to explore their role in prostate development and disease.
In vitro
prostate colony- and sphere-forming assays were used to quantitatively measure murine prostate stem/progenitor cell enrichment and self-renewal. Cell surface markers were screened for their ability to positively or negatively enrich for cells with enhanced growth potential in these assays. Immunohistochemical and FACS analyses demonstrate that specific cell surface markers can be used to discriminate prostate stromal (CD34
+
), luminal epithelial (CD24
+
CD49f
−
), basal epithelial (CD24
+
CD49f
+
), hematopoietic (CD45
+
, Ter119
+
), and endothelial (CD31
+
) lineages. Sorting for cells with a CD45
−
CD31
−
Ter119
−
Sca-1
+
CD49f
+
antigenic profile results in a 60-fold enrichment for colony- and sphere-forming cells. These cells can self-renew and expand to form spheres for many generations and can differentiate to produce prostatic tubule structures containing both basal and luminal cells
in vivo
. These cells also localize to the basal cell layer within the region of the gland that is proximal to the urethra, which has been identified as the prostate stem cell niche. Prostate stem cells can be isolated to a purity of up to 1 in 35 by using this antigenic profile. The remarkable similarity in cell surface profile between prostate and mammary gland stem cells suggests these markers may be conserved among epithelial stem cell populations.
Identification and characterization of COPIa- and COPIb-type vesicle classes associated with plant and algal Golgi
Authors: Donohoe Bryon S. , Kang Byung-Ho , Staehelin L. Andrew
Published: December 2006

Coat protein I (COPI) vesicles arise from Golgi cisternae and mediate the recycling of proteins from the Golgi back to the endoplasmic reticulum (ER) and the transport of Golgi resident proteins between cisternae.
In vitro
studies have produced evidence for two distinct types of COPI vesicles, but the
in vivo
sites of operation of these vesicles remain to be established. We have used a combination of electron tomography and immunolabeling techniques to examine Golgi stacks and associated vesicles in the cells of the scale-producing alga
Scherffelia dubia
and
Arabidopsis
preserved by high-pressure freezing/freeze-substitution methods. Five structurally distinct types of vesicles were distinguished. In
Arabidopsis
, COPI and COPII vesicle coat proteins as well as vesicle cargo molecules (mannosidase I and sialyltransferase–yellow fluorescent protein) were identified by immunogold labeling. In both organisms, the COPI-type vesicles were further characterized by a combination of six structural criteria: coat architecture, coat thickness, membrane structure, cargo staining, cisternal origin, and spatial distribution. Using this multiparameter structural approach, we can distinguish two types of COPI vesicles, COPIa and COPIb. COPIa vesicles bud exclusively from cis cisternae and occupy the space between cis cisternae and ER export sites, whereas the COPIb vesicles bud exclusively from medial- and trans-Golgi cisternae and are confined to the space around these latter cisternae. We conclude that COPIa vesicle-mediated recycling to the ER occurs only from cis cisternae, that retrograde transport of Golgi resident proteins by COPIb vesicles is limited to medial and trans cisternae, and that diffusion of periGolgi vesicles is restricted.
Nasal Cytotoxic and Carcinogenic Activities of Systemically Distributed Organic Chemicals
Authors: Jeffrey Alan M. , Iatropoulos Michael J. , Williams Gary M.
Published: December 2006

Toxicity and carcinogenicity in the mucosa of the nasal passages in rodents has been produced by a variety of organic chemicals which are systemically distributed. In this review, 14 such chemicals or classes were identified that produced rodent nasal cytotoxicity, but not carcinogenicity, and 11 were identified that produced nasal carcinogenicity. Most chemicals that affect the nasal mucosa were either concentrated in that tissue or readily activated there, or both. All chemicals with effects in the nasal mucosa that were DNA-reactive, were also carcinogenic, if adequately tested. None of the rodent nasal cytotoxins has been identified as a human systemic nasal toxin. This may reflect the lesser biotransformation activity of human nasal mucosa compared to rodent and the much lower levels of human exposures. None of the rodent carcinogens lacking DNA reactivity has been identified as a nasal carcinogen or other cancer hazard to humans. Some DNA-reactive rodent carcinogens that affect the nasal mucosa, as well as other tissues, have been associated with cancer at various sites in humans, but not the nasal cavity. Thus, findings in only the rodent nasal mucosa do not necessarily predict either a toxic or carcinogenic hazard to that tissue in humans.
Toxicity Profiles in Mice Treated with Hepatotumorigenic and Non-Hepatotumorigenic Triazole Conazole Fungicides: Propiconazole, Triadimefon, and Myclobutanil
Authors: Allen James W. , Wolf Douglas C. , George Michael H. , Hester Susan D. , Sun Guobin , Thai Sheau-Fung , Delker Don A. , Moore Tanya , Jones Carlton , Nelson Gail , Roop Barbara C. , Leavitt Sharon , Winkfield Ernest , Ward William O. , Nesnow Stephen
Published: December 2006

Conazoles comprise a class of fungicides used in agriculture and as pharmaceutical products. The fungicidal properties of conazoles are due to their inhibition of ergosterol biosynthesis. Certain conazoles are tumorigenic in rodents; both propiconazole and triadimefon are hepatotoxic and hepatotumorigenic in mice, while myclobutanil is not a mouse liver tumorigen. As a component of a large-scale study aimed at determining the mode(s) of action for tumorigenic conazoles, we report the results from comparative evaluations of liver and body weights, liver histopathology, cell proliferation, cytochrome P450 (CYP) activity, and serum cholesterol, high-density lipoprotein and triglyceride levels after exposure to propiconazole, triadimefon, and myclobutanil. Male CD-1 mice were treated in the feed for 4, 30, or 90 days with triadimefon (0, 100, 500, or 1800 ppm), propiconazole (0, 100, 500, or 2500 ppm) or myclobutanil (0, 100, 500, or 2000 ppm). Alkoxyresorufin O-dealkylation (AROD) assays indicated that all 3 chemicals induced similar patterns of dose-related increases in metabolizing enzyme activity. PROD activities exceeded those of MROD, and EROD with propiconazole inducing the highest activities of PROD. Mice had similar patterns of dose-dependent increases in hepatocyte hypertrophy after exposure to the 3 conazoles. High-dose exposures to propiconazole and myclobutanil, but not triadimefon, were associated with early (4 days) increases in cell proliferation. All the chemicals at high doses reduced serum cholesterol and high-density lipoprotein (HDL) levels at 30 days of treatment, while only triadimefon had this effect at 4 days of treatment and only myclobutanil and propiconazole at 90 days of treatment. Overall, the tumorigenic and nontumorigenic conazoles induced similar effects on mouse liver CYP enzyme activities and pathology. There was no specific pattern of tissue responses that could consistently be used to differentiate the tumorigenic conazoles, propiconazole, and triadimefon, from the nontumorigenic myclobutanil. These findings serve to anchor other transcriptional profiling studies aimed at probing differences in key events and modes of action for tumorigenic and nontumorigenic conazoles.
Acute and Subacute Pulmonary Toxicity of Low Dose of Ultrafine Colloidal Silica Particles in Mice after Intratracheal Instillation
Authors: Kaewamatawong Theerayuth , Shimada Akinori , Okajima Mina , Inoue Hiromi , Morita Takehito , Inoue Kenichiro , Takano Hirohisa
Published: December 2006

To study the acute and subacute lung toxicity of low dose of ultrafine colloidal silica particles (UFCSs), mice were intratracheally instilled with 0, 0.3, 3, 10, 30 or 100 μg of UFCSs. Cellular and biochemical parameters in bronchoalveolar lavage fluid (BALF), histological alteration and the body weight were determined at 3 days after instillation. Exposure to 30 or 100 μg of UFCSs produced moderate to severe pulmonary inflammation and tissue injury. To investigate the time response, mice were instilled with 30 μg of UFCSs and sacrificed at intervals from 1 to 30 days post-exposure. UFCSs induced moderate pulmonary inflammation and injury on BALF indices at acute period; however, these changes gradually regressed until recovery during the experiment. Concomitant histopathological and laminin immunohistochemical findings generally correlated to BALF data. TUNEL analyses in UFCSs-treated animals showed a significant increase of the apoptotic index in lung parenchyma at all observation times. 8-OHdG expression occurred in lung epithelial cells and activated macrophages, which correlated to lung lesions in UFCSs-treated mice. These findings suggest that instillation of a small dose of UFCSs causes transient acute moderate lung inflammation and tissue damage. Oxidative stress and apoptosis may underlie the lung tissue injury induction.
Cardiotrophin-1 defends the liver against ischemia-reperfusion injury and mediates the protective effect of ischemic preconditioning
Authors: Iñiguez Maria , Berasain Carmen , Martinez-Ansó Eduardo , Bustos Matilde , Fortes Puri , Pennica Diane , Avila Matias A. , Prieto Jesús
Published: December 2006

Ischemia-reperfusion (I/R) liver injury occurs when blood flow is restored after prolonged ischemia. A short interruption of blood flow (ischemic preconditioning [IP]) induces tolerance to subsequent prolonged ischemia through ill-defined mechanisms. Cardiotrophin (CT)-1, a cytokine of the interleukin-6 family, exerts hepatoprotective effects and activates key survival pathways like JAK/STAT3. Here we show that administration of CT-1 to rats or mice protects against I/R liver injury and that CT-1–deficient mice are exceedingly sensitive to this type of damage. IP markedly reduced transaminase levels and abrogated caspase-3 and c-Jun–NH2-terminal kinase activation after I/R in normal mice but not in CT-1–null mice. Moreover, the protective effect afforded by IP was reduced by previous administration of neutralizing anti–CT-1 antibody. Prominent STAT3 phosphorylation in liver tissue was observed after IP plus I/R in normal mice but not in CT-1–null mice. Oxidative stress, a process involved in IP-induced hepatoprotection, was found to stimulate CT-1 release from isolated hepatocytes. Interestingly, brief ischemia followed by short reperfusion caused mild serum transaminase elevation and strong STAT3 activation in normal and IL-6–deficient mice, but failed to activate STAT3 and provoked marked hypertransaminasemia in CT-1–null animals. In conclusion, CT-1 is an essential endogenous defense of the liver against I/R and is a key mediator of the protective effect induced by IP.