bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship of quantitative X-ray diffraction measurements of geologic materials to cesium sorption
Authors: Payne Timothy E. , Bertram W. K. , Itakura T. , Raven M. D.
Published: September 2005

The amounts of clay minerals in geologic samples from the Australian arid zone were measured using the SIROQUANT program, which quantifies mineral abundances from X-ray diffraction patterns using the Rietveld method. The sorption of trace cesium on the same samples was investigated in batch experiments. The statistical relationships between the Cs distribution coefficients (Kdvalues) and the smectite, illite and kaolinite contents were assessed. Other characterisation data such as the BET surface area and total clay content were included in the statistical analysis. The correlation of the illite content with the Kdfor trace Cs was stronger than any other correlation that was tested. This can be attributed to the presence of frayed edge sites on illite which are highly selective for the adsorption of trace Cs. Sorption experiments were also carried out with higher Cs concentrations, which were expected to saturate the selective Cs sorption sites on illite. Under these conditions, there was no significant correlation between the illite content and the cesium Kd. However, the Kdwas related to the smectite content of the materials. There was no correlation between the kaolinite content and the Kdfor Cs sorption under any of the experimental conditions. The sorption of Cs on the samples was influenced by the BET surface areas, but normalisation of the Kddata by surface area did not fully explain the sorption results. Only the quantitative XRD data were able to explain the shapes of Cs sorption isotherms. The isotherm was distinctly different for an illite-rich sample and did not conform to the Freundlich isotherm exhibited by other samples. This study demonstrates that quantitative XRD measurements are valuable in predicting Cs sorption properties of complex geologic samples, particularly sorption data obtained with trace Cs levels where bulk measurements such as the BET surface area are less useful.
Technetium behaviour in Boom Clay – a laboratory and field study
Authors: Baston G. M. N. , De Cannière P. , Ilett D. J. , Cowper M. M. , Pilkington N. J. , Tweed Cherry J. , Wang L. , Williams S. J.
Published: September 2005

This paper describes a study of technetium solubility and migration under chemical conditions representative of those prevailing in a Boom Clay environment. Laboratory andin situmeasurements yielded similar aqueous concentrations of technetium, of about 1×10−8mol dm−3, close to the concentrations measured for hydrated technetium(IV) oxide TcO2·1.6H2O in the solubility studies. From fitting the curves of the Tc concentrations as function of time, distribution coefficient (Kd) values were estimated to lie between 0.8 cm3g−1and 1.8 cm3g−1. Exposure of the system at 80 °C and to γ-radiation dose rates of several hundred Gy h−1resulted in only minor differences in behaviour.
Input contribution and vertical migration of plutonium, americium and cesium in lake sediments (Belham Tarn, Cumbria, UK)
Authors: Michel H. , Barci-Funel G. , Barci V. , Ardisson G.
Published: September 2005

The record of the global atmospheric fallout could be found in the lake sediments. A mass balance for fallout radionuclides in Blelham Tarn and its catchment is established. The sediment activity contribution is coming from direct atmospheric fallout and from indirect atmospheric fallout via the catchment. The catchement activity is conveyed to the sediment by the rivers and the direct streaming. A comparison of the fallout and the sediment inventory allows the activity estimation of these different contributions and to understand the mobility of these elements on the catchment and in the sediments. The study of activity profile in sediment core allows to characterise the different radioactive events occurred in the past. For the lake Blelham, the results show two cesium activity peaks and only one peak for transuranic activities. The deepest peaks correspond to the atmospheric nuclear test fallout in the sixties (1963) and the second peak to the Chernobyl accident (1986). The activity ratio 239-240Pu/ 137Cs allows estimating the ratio between cesium activities in sediments coming from these two events. Plutonium and cesium diffusion coefficients are calculated with a simple analytical model.
Diffusion of 22Na+, 85Sr2+, 134Cs+ and 57Co2+ in bentonite clay compacted to different densities: experiments and modeling
Authors: Molera M. , Eriksen T.
Published: September 2005

The diffusion of radionuclides in water-saturated porous media, such as compacted bentonite, is traditionally modeled assuming diffusion in the pore water and immobilization by adsorption on the clay surface. In reality there are several sorption mechanisms acting in the clay-water system. We have therefore carried out a careful diffusion study of the cations Na+, Sr2+, Cs+, which are predominantly sorbed by electrostatic interaction, and Co2+, for which the dominant sorption mechanism at pH > 7 is inner-sphere complexation and/or surface precipitation. The study has been performed at different densities of clay compaction (1.8, 1.6, 1.2, 0.8, 0.4 g cm−3) using a through diffusion technique. In each experiment, the apparent diffusivity and transport Kd were obtained by computer simulation of the experimentally measured cumulative flux through a plug of compacted bentonite and the concentration profile within the bentonite. Batch sorption experiments with Na+, Sr2+, Cs+ and Co2+ were also carried out. Measured batch Kd values were compared to diffusion-derived Kd values using the computer code ANADIFF. The obtained diffusivities of Cs+ and Sr2+ decreased as the density of bentonite increased. The diffusivity of Cs+ decreased from 1.5×10−7 to 1.1×10−8 cm2/s as the clay dry bulk density increased from 0.4 to 1.8 g/cm3 and the diffusivity for Sr2+ varied from 4.3×10−7 to 9.0×10−8 cm2/s. The diffusivities of Co2+ also decreased from 3.0×10−9 to 1.0×10−10 cm2/s in the same range of clay density. An interpretation of the diffusion data is proposed based on differences in porosity and tortuosity of the bentonite compacted to different densities, and on differences in binding energy, hydration energy, and hydrolysis constants for the cations studied.
Precipitation of technetium by subsurface sulfate-reducing bacteria
Authors: Abdelouas A. , Fattahi Massoud , Grambow Bernd , Vichot L. , Gautier E.
Published: September 2005

To study the interaction between Tc and subsurface bacteria, we conducted batch experiments with soil and groundwater or sterilized deionized water. The system water/soil was amended with lactate and phosphate for bacterial growth. Nitrate and sulfate were added to stimulate the growth of indigenous denitrifying and sulfate-reducing bacteria. During denitrification Tc-concentration did not change with time. In the presence of sulfate-reducing bacteria, Tc-concentrations decreased in reacted waters which could be attributed to Tc(VII) reduction and precipitation of TcO2and/or TcS2. Coprecipitation with newly formed iron sulfide is expected to contribute to Tc removal. Additional experiments with U and Tc showed that these elements were simultaneously reduced by sulfate-reducing bacteria. This work shows that 1) subsurface mixed cultures of denitrifying bacteria do not remove Tc from solution, this is different from uranium and 2) sulfate-reducing bacteria reduce and remove Tc from aqueous solutions and thus in situ bioremediation of subsurface waters and soils may be possible with such ubiquitous bacteria.
Bio-sorption of neptunium(V) by Pseudomonas fluorescens
Authors: Songkasiri W. , Reed D. T. , Rittmann B. E.
Published: September 2005

The bio-sorption of neptunyl (NpO2
+) by Pseudomonas fluorescens was investigated. The overall goals of this research are to identify key interactions between neptunium and soil bacteria and to model these effects under subsurface-related conditions. Neptunyl, which is generally thought to be non-sorptive, was significantly sorbed under all conditions studied. At initial neptunyl concentrations of 4.75 µM and pH = 7, as much as 85% of the neptunium was sorbed under aerobic conditions. Kinetic studies show that neptunyl was sorbed rapidly within the first 15 minutes. The extent of sorption also increased with pH. In all cases, the sorbed neptunium was shown to be NpO2
+ by X-ray absorption near edged spectroscopy (XANES) analysis, confirming that there was no reduction to Np(IV) under the conditions of our experiment. The sorption data were modeled using Langmuir and Freundlich isotherms. A comparison of the two approaches showed a significantly better fit for the Freundlich isotherm, and the Freundlich parameter values suggest interactions between sorbed NpO2
+ molecules. These data show that bio-sorption, even for neptunyl, has a significant role in defining the speciation of neptunium and, hence, its overall mobility in the subsurface.
Solubility and hydrolysis of Zr oxides: a review and supplemental data
Authors: Curti E. , Degueldre C.
Published: September 2005

Thermodynamic data for Zr(IV) have been reviewed in the context of a recent update of the Nagra/PSI thermochemical database, which is primarily used in safety assessment calculations for radioactive waste repositories in Switzerland. In spite of the important role of Zr in nuclear reactor technology and as fission product in radioactive waste, the thermodynamic properties of this element in aqueous solutions are poorly constrained and published data are frequently contradictory. Specifically, hydrolysis constants, which are critical to any geochemical calculation of Zr speciation in aqueous solutions, may vary by several orders of magnitude.

Published solubility and hydrolysis data for Zr oxides were reviewed and evaluated. Recent solubility measurements on crystalline ZrO2, obtained in our laboratory, were integrated in this analysis. These new data are the only ZrO2 solubility measurements obtained in a pH region relevant for environmental aqueous systems, where equilibrium concentrations decrease to nanomolar levels.

All solubility data of (hydrous) Zr oxides can be reproduced satisfactorily by a single set of hydrolysis constants, provided that only data measured from undersaturation are considered. This set includes the species Zr4+, ZrOH3+, Zr(OH)4
0 and Zr(OH)5
−. However, present experimental data are still not sufficient to establish a fully reliable database.
Nagra/PSI Chemical Thermodynamic Data Base 01/01
Authors: Hummel W. , Berner U. , Curti E. , Pearson F. J. , Thoenen T.
Published: September 2005

The Nagra/PSI Chemical Thermodynamic Data Base has been updated to support performance assessments of the planned Swiss repositories for radioactive waste. The update from version 05/92 to 01/01 involved major revisions for most of the actinides and fission products. Altogether, more than 70% of the database contents have been revised. Data for U, Np, Pu, Am and Tc recommended by the NEA TDB project were considered in the update. Thermodynamic data for Th, Sn, Eu, Pd, Al, and solubility and metal complexation of sulphides and silicates were extensively reviewed. Data for Zr, Ni and Se were examined less rigorously as these elements are currently being reviewed in phase II of the NEA TDB project. Our experiences from this two year team effort can be summarised as follows. Detailed in-house reviews and critical appraisal of NEA recommendations greatly improved the chemical consistency and quality of the selected data. On the other hand, we could discern major gaps in the data, especially missing carbonate complexes. In some systems,e.g. Th(IV)-H2O and U(IV)-H2O, experimental data could not be described by a unique set of thermodynamic constants. There, a pragmatic approach based on solubility data was chosen for application to performance assessment. The electronic version of our database and information concerning its full documentation is available on our PSI web site (http://www.psi.ch/les).
Epidermal growth factor receptor downregulation in cultured bovine cumulus cells: reconstitution of calcium signaling and stimulated membrane permeabilization
Authors: Zhao Zhong , Garbett Damien , Hill Julia L , Gross David J
Published: September 2005

Cumulus cell–oocyte complexes (COCs), culturedin vitro, are competent for maturation and fertilization. Inclusion of epidermal growth factor (EGF) in the COC culture medium enhancesin vitromaturation and subsequent embryonic development. It has been shown that isolated COCs exposed to EGF respond with a prolonged and pulsatile release of Ca2+into the extra-cellular medium and that cumulus cells (CCs) of complexes exhibit both a slow rise in intracellular [Ca2+] ([Ca2+]i) and plasma membrane permeabilization in response to EGF. These unusual signaling responses were examined in isolated, cultured bovine CCs. Few individual CCs showed [Ca2+]iincreases; the lack of response was found to be due to decrease of expression of endogenous EGF receptors after dissociation. CCs transfected with a human EGF receptor–GFP fusion protein showed robust, prolonged, EGF-stimulated [Ca2+]ielevations characteristic of CC responses in intact COCs. Many CCs that responded to EGF stimulation with a [Ca2+]irise also released entrapped fura-2 dye at the peak of the [Ca2+]iresponse, suggesting that CC permeabilization and death follows activation of the EGF receptor. The [Ca2+]ielevation due to EGF stimulation and subsequent membrane permeabilization was shown to be mediated by the inositol triphosphate signaling pathway.
Hydrogen peroxide and superoxide anion modulate pregnant human myometrial contractility
Authors: Warren Averil Y , Matharoo-Ball Balwir , Shaw Robert W , Khan Raheela N
Published: September 2005

Reactive oxygen species (ROS) have the propensity to cause macromolecular damage with consequent modification of cellular function. We investigated the effects of two particular oxidants, superoxide (O2−) anions and hydrogen peroxide (H2O2), on oxytocin-induced myometrial contractility using biopsies from women undergoing Caesarean section at term gestation. Isometric tension recordings were performed and concentration–response curves derived after addition of test agents. A maximal reduction in myometrial contractility to 27.2 ± 4.5% of control was observed followed application of H2O2. The enzyme scavenger catalase (CAT) reduced the inhibitory effect of H2O2but had little effect at 10-fold lower concentrations. Addition of dialysed xanthine oxidase ± hypoxanthine significantly inhibited contractility to 23.8.0 ± 4.2% compared with control. Pre-incubation with superoxide dismutase and CAT diminished this effect. The non-specific potassium channel blocker, tetraethylammonium chloride (1 mM), had no effect on myometrial contractility. We conclude that human myometrium is susceptible to the effects of ROS, which may be produced by reperfusion–ischaemic episodes during labour. Our findings could, in part, explain the weak or prolonged depression of contractions characteristic of myometrial dysfunction culminating in difficult labours.
Gene-nutrient interactions during fetal development
Authors: Maloney Christopher A , Rees William D
Published: September 2005

Eukaryotic cells have evolved a complex series of nutrient sensors that protect them from damage caused by acute deficiencies and also mediate adaptive responses to prolonged excess or deficiency of particular nutrients. In adults gene expression is regulated by nutrients interacting with pathways involving mammalian target of rapamycin (mTOR), CCAAT/ enhancer-binding proteins (C/EBPs) and peroxisome proliferator activator proteins (PPARs). These systems are also present in key cells of the developing oocyte, embryo and fetus. In this review we will consider the role of interactions between genes and nutrients during reproduction with a particular emphasis on their possible involvement in the prenatal programming of glucose metabolism in the adult.
Murine CD200+CK7+ trophoblasts in a poly (I:C)-induced embryo resorption model
Authors: Lin Yi , Zeng Yaoying , Di Jingfang , Zeng Shan
Published: September 2005

Cytokeratin 7 (CK7) is currently regarded as the best marker for trophoblast cells, while CD200 (OX-2), known as ‘tolerance signal’, plays an important role in normal pregnancy. In this study, the status of CD200 expression was investigated in BALB/c × C57BL/6 and BALB/c × BALB/c mating combinations designed as allogeneic and syngeneic murine models of induced embryo resorption, in which the resorption rate was boosted by an i.p. injection of poly (I:C), a synthetic double-stranded RNA. The percentage of CD200+cells in the CK7+cell population (CD200+CK7+percentage) and the absolute number of these cells were determined with flow cytometry, using trophoblast cells collected at day 8.5 and day 13.5 of gestation. The potential effect of poly (I:C) on CD200 expression was also evaluated by detecting the CD200+CK7+percentage in trophoblast cells incubated in the presence or absence of poly (I:C),in vitro. The distribution pattern of CD200+cells at the feto–maternal interface was evaluated by immunocytochemical examination. When 104cells were analyzed at day 8.5 of gestation in each case, no significant difference was observed between the poly (I:C)-treated group and the control PBS group either in the CD200+CK7+percentage or in the absolute number of these cells. Similar results were observed both in BALB/c × C57BL/6 mice and in BALB/c × BALB/c mice. However, the CD200+CK7+percentage was significantly decreased in the poly (I:C)-treated group when evaluated at day 13.5 of gestation. Accordingly, a dramatically elevated rate of embryo resorption was observed at this time point of pregnancy after the administration of poly (I:C). In addition, the CD200+CK7+percentage was significantly lower in trophoblast cells incubated with poly (I:C) at a certain concentration,in vitro, while histocytochemical examination showed the CD200+cells mainly scattered in placental tissue adjacent to the interface of the placenta and uterus. This indicates that sufficient expression of the CD200 molecule on CK7+cells at the feto–maternal interface may be necessary for the maintenance of embryos during pregnancy in this rodent model, while poly (I:C) administration may increase embryo resorption, at least partially via direct inhibition of CD200 expression on CK7+cells.
Distinct roles for the mammalian A-type cyclins during oogenesis
Authors: Persson Jenny Liao , Zhang Qi , Wang Xiang Yuan , Ravnik Stuart E , Muhlrad Samantha , Wolgemuth Debra J
Published: September 2005

There are two A-type cyclins in higher vertebrates, cyclin A1 and A2. Targeted mutagenesis has shown that cyclin A2 is essential for early embryonic development while cyclin A1 is required only for male meiosis. The embryonic lethality of cyclin A2 knockout mice has obviated understanding its role in other aspects of mammalian development, including the germ line. We reported previously that cyclin A2 expression in the male germ line is consistent with a role in both mitotic and meiotic cell cycles. Usingin situhybridization and immunohistochemistry, we now observe high levels of cyclin A2 in granulosa cells and less-abundant but readily detectable expression in ovarian and ovulated oocytes. A decrease in cyclin A2 protein was observed in oocytes from embryonic stages to post-natal and adult ovaries. Interestingly, cyclin A2 protein was nuclear in oocytes from embryonic day 13.5 to 15.5, changing to largely cytoplasmic in oocytes from embryonic day 16.5 to post-natal and adults. Readily detectable expression of the cyclin-dependent kinases Cdk1 and Cdk2, two common partners for the A-type cyclins, was observed in granulosa cells and oocytes at all stages of folliculogenesis. Cdk1 was predominantly cytoplasmic, whereas Cdk2 was both cytoplasmic and nuclear in oocytes. No cyclin A1 expression, at either the mRNA level or the protein level was detected in either embryonic or adult ovaries, consistent with the full fertility observed in female cyclin A1-deficient mice. These results suggest that in the female germ line, cyclin A2 but not cyclin A1 has distinct roles in both mitosis and meiosis.
Non-esterified fatty acids in follicular fluid of dairy cows and their effect on developmental capacity of bovine oocytes in vitro
Authors: Leroy J L M R , Vanholder T , Mateusen B , Christophe A , Opsomer G , de Kruif A , Genicot G , Van Soom A
Published: September 2005

In this study concentration and composition of non-esterified fatty acids (NEFA) in follicular fluid (FF) of high-yielding dairy cows were determined during the period of negative energy balance (NEB) early post partum. NEFA were then added duringin vitromaturation at concentrations measured previously in FF to evaluate their effect on the oocyte’s developmental competence. At 16 and 44 days post partum, FF of the dominant follicle and blood were collected from nine high-yielding dairy cows. Samples were analysed for NEFA concentration and composition. NEFA concentrations in FF (0.2–0.6 mmol/l) during NEB remained ± 40% lower compared with serum (0.4–1.2 mmol/l). The NEFA composition differed significantly between serum and FF with oleic acid (OA), palmitic acid (PA) and stearic acid (SA) being the predominant fatty acids in FF. Based on these results, 5115 oocytes were matured for 24 h in serum-free media with or without (negative control) the addition of 0.200 mmol/l OA, 0.133 mmol/l PA or 0.067 mmol/l SA dissolved in ethanol or ethanol alone (positive control). Matured oocytes were fertilized and cultured for 7 days in SOF medium. Addition of PA or SA during oocyte maturation had negative effects on maturation, fertilization and cleavage rate and blastocyst yield. More (late) apoptotic cumulus cells were observed in cumulus–oocyte complexes matured in the presence of SA or PA. Ethanol or OA had no effect. Thesein vitroresults suggest that NEB may hamper fertility of high-yielding dairy cows through increased NEFA concentrations in FF affecting oocyte quality.
Strontium-induced rat egg activation
Authors: Tomashov-Matar R , Tchetchik D , Eldar A , Kaplan-Kraicer R , Oron Y , Shalgi R
Published: September 2005

Parthenogenetic agents that evoke cytosolic calcium concentration ([Ca2+]i) oscillations similar to those evoked by sperm, mimic fertilization more faithfully than agents that trigger a single [Ca2+]itransient. Strontium chloride (SrCl2) binds to and activates the Ca2+-binding site on the inositol 1,4,5-trisphosphate receptor and evokes [Ca2+]ioscillations. Although SrCl2has been reported to activate mouse eggs, little is known regarding the pattern of the [Ca2+]ioscillations it evokes in rat eggs and their effect on the early events of egg activation: cortical granule exocytosis (CGE) and completion of meiosis (CM). In the current study we investigated the effect of various concentrations of SrCl2(2, 4 or 6 mM) on [Ca2+]i, by monitoring [Ca2+]ioscillations in fura-2-loaded rat eggs. Treatment with 2 mM SrCl2was optimal for inducing the first [Ca2+]itransient, which was similar in duration to that triggered by sperm. However, the frequency and duration of the subsequent [Ca2+]ioscillations were lower and longer in SrCl2-activated than in sperm-activated eggs. The degree of CGE was identical in eggs activated by either sperm or SrCl2, as assessed by semi-quantitative immunohistochemistry combined with confocal microscopy. Evoking 1, 2 or 10 [Ca2+]ioscillations (8, 15 or 60 min in SrCl2respectively) had no effect on the intensity of fluorescent CGE reporter dyes, while 60-min exposure to SrCl2caused a delay in CM. Our results demonstrate that SrCl2is an effective parthenogenetic agent that mimics rat egg activation by sperm, as judged by the generation of [Ca2+]ioscillations, CGE and CM.
Activation of Akt (protein kinase B) stimulates metaphase I to metaphase II transition in bovine oocytes
Authors: Tomek Wolfgang , Smiljakovic Tatjana
Published: September 2005

In somatic cells, the serine/threonine kinase Akt (or protein kinase B) was shown to contribute to processes linked to cellular growth, cell survival and cell cycle regulation. In contrast to these findings, the function of Akt during the meiosis of mammalian oocytes remains to be investigated. We analysed the phosphorylation pattern and the activity of Akt during meiotic maturation (transition from prophase I to metaphase II) of bovine oocytes. The oocytes were maturedin vitro(IVM) for 0, 10 and 24 h to reach the germinal vesicle (GV), metaphase I (M I) and metaphase II (M II) stages respectively. The abundance and phosphorylation pattern of Akt was revealed by Western blotting using total Akt or phosphoso-Akt-specific antibodies. The activity of this particular kinase was determined by anin vitrokinase assay. Furthermore, functional properties were analysed by cultivating oocytes in the presence of the Akt inhibitor SH6. The results showed that the overall abundance of Akt did not change significantly during IVM. On the other hand, Akt became phosphorylated at Thr 308 and Ser 473, reaching its maximum at the M I phase. In the GV and M II stages, only low basal phosphorylation levels were observed on both sides. This phosphorylation profile corresponded strictly to the activity of the kinase. The cultivation of oocytes in the presence of the phosphatidylinositol analogue SH6 for 24 h showed that, with higher concentrations, up to 65% of the oocytes were arrested in the M I stage. This result indicated that Akt is involved in the M I/M II transition during the meiotic maturation of bovine oocytes. The physiological aspects of the Akt function will be discussed.
The proteasomal inhibitor MG132 increases the efficiency of mouse embryo production after cloning by electrofusion
Authors: Yu Yuansong , Yong Jun , Li Xiangyun , Qing Tingting , Qin Han , Xiong Xiaoran , You Jiefang , Ding Mingxiao , Deng Hongkui
Published: September 2005

In this study, we cloned mice from ES cells by a post-electrofusion MG132 treatment and improved development of cloned embryos with a sequential cultivation protocol. When 5 μM MG132, a proteasome inhibitor, were used to treat the reconstructed embryos, the capacity ofin vitrodevelopment, implantation and full-term development were significantly improved. Blastocyst formation rates of the reconstructed embryos from X4 ES cells (F1 strain derived from C57BL/6 × 129sv) and J1 ES cells obtained with or without MG132 treatment were 66.9% and 26.6%, and 66.1% and 34.5% respectively (P< 0.05). A total of 146 two-cell embryos cloned from X4 ES cells with MG132 treatment were transferred to recipients, and five cloned pups (3.4%) were born, of which four survived. When the same numbers of two-cell embryos cloned from X4 ES cells without MG132 treatment were transferred, however, no live-born mice were obtained. When embryos cloned from J1 ES cells without MG132 treatment were cultured in KSOM medium for 54 h followed by culture in CZB medium containing 5.6 mM glucose for 42 h, the blastocyst rate was significantly higher than when they were cultured in KSOM continuously for 96 h (34.5% vs 17.1%). However, sequential cultivation did not improve the development of embryos cloned with MG132 treatment and that of parthenotes. In conclusion, MG132 treatment increased the developmental potential of reconstructed mouse embryos, and sequential cultivation improved development of the embryos cloned by electrofusion without MG132 treatment.
Somatic cell nuclear transfer in horses: effect of oocyte morphology, embryo reconstruction method and donor cell type
Authors: Lagutina Irina , Lazzari Giovanna , Duchi Roberto , Colleoni Silvia , Ponderato Nunzia , Turini Paola , Crotti Gabriella , Galli Cesare
Published: September 2005

The objective of the present work was to investigate and clarify the factors affecting the efficiency of somatic cell nuclear transfer (NT) in the horse, including embryo reconstruction, in vitro culture to the blastocyst stage, embryo transfer, pregnancy monitoring and production of offspring. Matured oocytes, with zona pellucida or after zona removal, were fused to cumulus cells, granulosa cells, and fetal and adult fibroblasts, and fused couplets were cultured in vitro. Blastocyst development to Day 8 varied significantly among donor cells (from 1.3% to 16%, P < 0.05). In total, 137 nuclear transfer-embryos were transferred nonsurgically to 58 recipient mares. Pregnancy rate after transfer of NT-embryos derived from adult fibroblasts from three donor animals was 24.3% (9/37 mares transferred corresponding to 9/101 blastocysts transferred), while only 1/18 (5.6%) of NT-blastocysts derived from one fetal cell line gave rise to a pregnancy (corresponding to 1/33 blastocysts transferred). Overall, seven pregnancies were confirmed at 35 days, and two went to term delivering two live foals. One foal died 40 h after birth of acute septicemia while the other foal was healthy and is currently 2 months old. These results indicate that (a) the zona-free method allows high fusion rate and optimal use of equine oocytes, (b) different donor cell cultures have different abilities to support blastocyst development, (c) blastocyst formation rate does not correlate with pregnancy fate and (d) healthy offspring can be obtained by somatic cell nuclear transfer in the horse.
A mouse sperm decapacitation factor receptor is phosphatidylethanolamine-binding protein 1
Authors: Gibbons Rachel , Adeoya-Osiguwa Susan A , Fraser Lynn R
Published: September 2005

Capacitation is a pivotal event for mammalian spermatozoa, involving the loss of surface proteins known as decapacitation factors (DF) and consequent acquisition of fertilizing ability. Earlier studies showed that a mouse sperm DF binds to a receptor, DF-R, whose attachment to the sperm plasma membrane appears to involve a glycosylphosphatidylinositol (GPI) anchor. In the present study, purification and subsequent sequencing of DF-R has identified this ~23 kDa protein as phosphatidyletha-nolamine-binding protein 1 (PEBP 1). To obtain functional evidence that supports sequence homology data, purified recombinant PEBP 1 and PEBP 2 were evaluated for biological activity. While PEBP 1 was able to remove DF activity in solution at concentrations above ~1 nmol/l, PEBP 2 was ineffective, even at 600 nmol/l; this confirmed that DF-R is PEBP 1. Anti-PEBP 1 antiserum recognized recombinant PEBP 1 and a ~23 kDa protein in both mouse and human sperm lysates. Immunolocalization studies revealed that DF-R/PEBP 1 is located on the acrosomal cap, the post-acrosomal region and the flagellum of both mouse and human spermatozoa, with epitope accessibility being capacitation state-dependent and reversible. Treatment of cells with a phospholipase able to cleave GPI anchors essentially abolished immunostaining, thus confirming the extracellular location of DF-R/PEBP 1. We suggest that DF-R/PEBP 1 plays its fundamental role in capacitation by causing alterations in the sperm plasma membrane in both head and flagellum, with functional consequences for membrane-associated proteins. Obtaining more detail about DF ↔ DF-R interactions could lead to useful applications in both fertility treatments and new contraceptive approaches.
Metabolic markers of developmental competence for in vitro-matured mouse oocytes
Authors: Preis Kimberly A , Seidel George , Gardner David K
Published: September 2005

In vitromaturation of oocytes has enormous potential in assisted reproductive technology, but its use has been limited due to insufficient knowledge of oocyte physiology during this dynamic period and lack of an adequate maturation system. The aim of this study was to characterize the metabolic profiles of three groups of oocytes throughout maturation: cumulus–oocyte complexes (COCs), denuded oocytes, and denuded oocytes co-cultured with cumulus cells. Mouse oocytes were collected from 28-day-old unstimulated females and matured in a defined medium. Oocytes were matured individually and transferred into fresh 0.5 μl drops of medium at 4 h intervals until 16 h. Ultramicrofluorimetry was used to quantitate carbohydrate consumption from and metabolite release into the medium. Glucose consumption and lactate production of COCs increased (P< 0.001) over the maturation interval (0–16 h). Glucose consumption by COCs that subsequently fertilized was higher between 8–12 h of maturation than by COCs that did not fertilize (38 versus 29 pmol/COC per h, respectively;P< 0.01). Lactate production by COCs that subsequently fertilized was higher between 8–16 h of maturation, than by oocytes that did not fertilize (8–12 h, 66 versus 46 pmol/COC per h,P< 0.01; 12–16 h, 56 versus 40 pmol/COC per h, respectively;P< 0.05). These data indicate that the final hours of maturation may hold a unique marker of oocyte competence, as during this time fertilizable COCs take up more glucose and produce more lactate than those not subsequently fertilized.
Effect of E(sev) and Su(Raf) Hsp83 Mutants and Trans-heterozygotes on Bristle Trait Means and Variation in Drosophila melanogaster
Authors: Milton Claire C , Batterham Philip , McKenzie John A , Hoffmann Ary A
Published: September 2005

The Hsp90 protein encoded by the Hsp83 gene is required for the development of many traits in Drosophila. Hsp83 is also thought to play a role in the expression of phenotypic and genetic variability for subsequent selection and evolutionary change. Here we examine the impact of different E(sev) and Su(Raf) Hsp83 mutants on means and phenotypic variances of invariant and variable bristle traits. One of the mutants influenced the normally invariant thoracic bristle number, while none affected invariant scutellar bristle number. E(sev) alleles consistently influenced variable bristle traits while there were fewer effects of the Su(Raf) alleles. For the variable traits, none of the Hsp83 alleles had any effect on phenotypic variance, environmental variance, or developmental stability of the bristle traits. When alleles were combined in trans-heterozygotes, there were both cumulative and complementary effects on thoracic and variable bristle trait numbers, depending on the allelic combination. Overall, the results suggest that Hsp83 mutants do not have detectable effects on the phenotypic or environmental variance of bristle traits and that complementation of E(sev) and Su(Raf) Hsp83 mutants can extend to thoracic bristles as well as previously reported effects on viability. Some allelic combinations lead to more severe effects on variable bristle trait means than do single Hsp83 mutations.
Extensive Chromosomal Repatterning and the Evolution of Sterility Barriers in Hybrid Sunflower Species
Authors: Lai Zhao , Nakazato Takuya , Salmaso Marzia , Burke John M , Tang Shunxue , Knapp Steven J , Rieseberg Loren H
Published: September 2005

New species may arise via hybridization and without a change in ploidy. This process, termed homoploid hybrid speciation, is theoretically difficult because it requires the development of reproductive barriers in sympatry or parapatry. Theory suggests that isolation may arise through rapid karyotypic evolution and/or ecological divergence of hybrid neospecies. Here, we investigate the role of karyotypic change in homoploid hybrid speciation by generating detailed genetic linkage maps for three hybrid sunflower species, Helianthus anomalus, H. deserticola, and H. paradoxus, and comparing these maps to those previously generated for the parental species, H. annuus and H. petiolaris. We also conduct a quantitative trait locus (QTL) analysis of pollen fertility in a BC2 population between the parental species and assess levels of pollen and seed fertility in all cross-combinations of the hybrid and parental species. The three hybrid species are massively divergent from their parental species in karyotype; gene order differences were observed for between 9 and 11 linkage groups (of 17 total), depending on the comparison. About one-third of the karyoypic differences arose through the sorting of chromosomal rearrangements that differentiate the parental species, but the remainder appear to have arisen de novo (six breakages/six fusions in H. anomalus, four breakages/three fusions in H. deserticola, and five breakages/five fusions in H. paradoxus). QTL analyses indicate that the karyotypic differences contribute to reproductive isolation. Nine of 11 pollen viability QTL occur on rearranged chromosomes and all but one map close to a rearrangement breakpoint. Finally, pollen and seed fertility estimates for F1's between the hybrid and parental species fall below 11%, which is sufficient for evolutionary independence of the hybrid neospecies.
Lamin A/C Expression Is a Marker of Mouse and Human Embryonic Stem Cell Differentiation
Authors: Constantinescu Dan , Gray Heather L. , Sammak Paul J. , Schatten Gerald P. , Csoka Antonei B.
Published: September 2005

Nuclear lamins comprise the nuclear lamina, a scaffold-like structure that lines the inner nuclear membrane. B-type lamins are present in almost all cell types, but A-type lamins are expressed predominantly in differentiated cells, suggesting a role in maintenance of the differentiated state. Previous studies have shown that lamin A/C is not expressed during mouse development before day 9, nor in undifferentiated mouse embryonic carcinoma cells. To further investigate the role of lamins in cell phenotype maintenance and differentiation, we examined lamin expression in undifferentiated mouse and human embryonic stem (ES) cells. Wide-field and confocal immunofluorescence microscopy and semiquantitative reverse transcription–polymerase chain reaction analysis revealed that undifferentiated mouse and human ES cells express lamins B1 and B2 but not lamin A/C. Mouse ES cells display high levels of lamins B1 and B2 localized both at the nuclear periphery and throughout the nucleoplasm, but in human ES cells, B1 and B2 expression is dimmer and localized primarily at the nuclear periphery. Lamin A/C expression is activated during human ES cell differentiation before downregulation of the pluripotency marker Oct-3/4 but not before the downregulation of the pluripotency markers Tra-1-60, Tra-1-81, and SSEA-4. Our results identify the absence of A-type lamin expression as a novel marker for undifferentiated ES cells and further support a role for nuclear lamins in cell maintenance and differentiation.
Magnetic Resonance Imaging and Confocal Microscopy Studies of Magnetically Labeled Endothelial Progenitor Cells Trafficking to Sites of Tumor Angiogenesis
Authors: Arbab Ali S. , Frenkel Victor , Pandit Sunil D. , Anderson Stasia A. , Yocum Gene T. , Bur Monica , Khuu Hanh M. , Read Elizabeth J. , Frank Joseph A.
Published: September 2005

AC133 cells, a subpopulation of CD34+ hematopoietic stem cells, can transform into endothelial cells that may integrate into the neovasculature of tumors or ischemic tissue. Most current imaging modalities do not allow monitoring of early migration and incorporation of endothelial progenitor cells (EPCs) into tumor neovasculature. The goals of this study were to use magnetic resonance imaging (MRI) to track the migration and incorporation of intravenously injected, magnetically labeled EPCs into the blood vessels in a rapidly growing flank tumor model and to determine whether the pattern of EPC incorporation is related to the time of injection or tumor size. Materials and Methods: EPCs labeled with ferumoxide–protamine sulfate (FePro) complexes were injected into mice bearing xenografted glioma, and MRI was obtained at different stages of tumor development and size. Results: Migration and incorporation of labeled EPCs into tumor neovasculature were detected as low signal intensity on MRI at the tumor periphery as early as 3 days after EPC administration in preformed tumors. However, low signal intensities were not observed in tumors implanted at the time of EPC administration until tumor size reached 1 cm at 12 to 14 days. Prussian blue staining showed iron-positive cells at the sites corresponding to low signal intensity on MRI. Confocal microcopy showed incorporation into the neovasculature, and immunohistochemistry clearly demonstrated the transformation of the administered EPCs into endothelial cells. Conclusion: MRI demonstrated the incorporation of FePro-labeled human CD34+/AC133+ EPCs into the neovasculature of implanted flank tumors.
Measurement of defect‐mediated diffusion: The case of silicon self‐diffusion
Authors: Vaidyanathan Ramakrishnan , Jung Michael Y. L. , Braatz Richard D. , Seebauer E. G.
Published: September 2005

In many solids, diffusion of foreign atoms takes place primarily through highly mobile intermediate species that periodically exchange with atoms in the crystalline lattice. A method is developed for determining key diffusion parameters via the short‐time decay of an initial step concentration profile. This method takes advantage of the relative ease with which step concentration profiles can be fabricated by thin film deposition, and in the limit of very short times provides particularly simple analytical means for obtaining parameters connected to diffusion length and defect formation. Application of the method to isotopic heterostructures of silicon shows that under the ultrahigh vacuum conditions of the experiment, interstitial atoms mediate self‐diffusion. © 2005 American Institute of Chemical Engineers AIChE J, 2006
Composing chaos: An experimental and numerical study of an open duct mixing flow
Authors: Metcalfe Guy , Rudman M. , Brydon A. , Graham L. J. W. , Hamilton R.
Published: September 2005

By using a programmed sequence of boundary motions to introduce flow reorientation to a steady, laminar axial flow in an open duct, we develop a novel device to investigate and exploit chaotic advection of viscously dominated (low Reynolds number) flows. The design and operation of the Rotated Arc Mixer (RAM) is discussed. Among other things, the RAM can effect good continuous mixing of viscous materials without use of any internal elements; moreover, the RAM has several control parameters to tune the chaotic advection, making it flexible for applications and theoretical developments. Numerical methods to discover the robust parameter regions where chaos covers the entire flow domain, and how these parameters change with fluid properties is also discussed. Poincaré sections, dye advection and residence time calculations are presented for Newtonian and non‐Newtonian fluids. Experiments, including advection field, velocity field and residence‐time measurements, confirm all aspects of the device for Newtonian fluids. © 2005 American Institute of Chemical Engineers AIChE J, 2006
Discrete element simulation for pneumatic conveying of granular material
Authors: Wee Chuan Lim Eldin , Wang Chi‐Hwa , Yu Ai‐Bing
Published: September 2005

The pneumatic transport of granular material is a common operation frequently employed to transport solid particles from one location to another. It is well established in the literature that different flow regimes can arise in such transportation processes depending on the system geometry and operating conditions used. In this study, the pneumatic transports of solid particles in both vertical and horizontal conveying lines were studied numerically using the discrete element method coupled with computational fluid dynamics. The simulation outputs corresponded well with reported experimental observations in terms of the different flow regimes obtained at different operating conditions. In the vertical pneumatic conveying simulations, two different flow patterns corresponding to the experimentally observed dispersed flow and plug flow regimes were obtained at different gas velocities and solid concentrations. Similarly, the homogeneous flow, stratified flow, moving dunes, and slug flow regimes previously reported to occur in horizontal pneumatic conveying were also reproduced computationally in this study. Solid concentration profiles obtained by spatial averaging along the length of the pipe showed a symmetrical but non‐uniform distribution for dispersed flow and an almost flat distribution for plug flow in vertical pneumatic conveying. The profile for stratified flow in horizontal pneumatic conveying showed higher solid concentration near the bottom wall due to the effects of gravitational settling, while that for slug flow was flat. Hysteresis in solid flow rates was observed in vertical pneumatic conveying near the point where transition between the dispersed and plug flow regimes was expected to occur. Solid flow rates were also found to be more sensitive towards the coefficient of friction than the coefficient of restitution of particles and the pipe walls in a sensitivity analysis study of these parameters. © 2005 American Institute of Chemical Engineers AIChE J, 2006
Effect of curvature of coating die edges on the pinning of contact line
Authors: Romero Oldrich Joel , Scriven L. E. , Carvalho Márcio da Silveira
Published: September 2005

Coating die edges are not mathematical corners, they are rounded. Contact lines do not actually pin. The effects of the radius of curvature of the downstream edge of slot dies on contact line location, effective contact angle, and low‐flow limit—air‐fingers penetrating from downstream and breaking apart the coating‐bead—are examined by solving the Navier‐Stokes system for Newtonian flow. The geometry of the die surface is represented by two straight lines and an arc of circle connecting them. The local contact angle is treated as a specified equilibrium value. The system of equations is solved by Galerkin's method and finite element basis functions. The results show how the edge rounding affects the contact line position and stability of the flow, and indicate the minimum radius of curvature necessary to apparently pin the contact line. © 2005 American Institute of Chemical Engineers AIChE J, 2006
Equation of state for the viscosity of Lennard‐Jones fluids
Authors: Woodcock Leslie V.
Published: September 2005

A one‐parameter model constitutive transport equation for the viscosity of the Lennard‐Jones (L‐J) fluid that is accurate for all equilibrium states of liquid and gas is proposed:

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The form of this equation is based upon the soft‐sphere scaling laws for the residual density‐dependent viscosity discovered originally by Ashurst and Hoover and uses their empirical coefficient (CAH). Enskog's density‐independent limit theoretical term (η0) is included to reproduce the viscosity in the limit of zero density accurately. Remaining discrepancies at low temperatures, for both gas and liquid densities, are largely removed when the linear‐density Rainwater‐Friend coefficient is added. The equation is comparable in accuracy to the 24‐parameter empirical equation of state proposed by Rowley and Painter. Comparison with this correlation and previous MD results reveals a discrepancy near the triple point. To test the equation, new MD data for three fluid states are reported. Here, the viscosity is computed from time correlation functions resolved into the single‐particle auto‐ and cross‐correlation terms. It is found that, at high density (ρ* > 0.8), the cross–correlations extend beyond 7σ (molecule diameters) and oscillate in sign. This explains the wide scatter of previous MD viscosities for small L‐J systems. © 2005 American Institute of Chemical Engineers AIChE J, 2006