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Combination of co-electrolysis of CO2 and steam using solid oxide electrolysis cells (SOECs) and methane production (methanation) offers an attractive process for CO2 conversion to hydrocarbon fuels. Ni-based (Ni/YSZ is a typical example) SOECs could be used as catalytic reactor for CH4 production because Ni has been found to be an active catalyst for methanation. Therefore, Ni/YSZ SOECs could be used as catalytic reactor for methanation. Based on this concept, in this study we have prepared a Ni/YSZ material that can be used in the catalytic reactor. The performance of the prepared Ni/YSZ was evaluated as a catalyst for CO2 methanation. Ni/YSZ catalysts with a Ni loading of 55wt% calcined at 800-1100 ºC gave a high CO2 conversion of up to 86% and a high methane selectivity of >99% at 250-350 ºC of reaction temperature under ambient pressure.

We developed a NaBr-assisted photoelectrochemical and photochemical integrated process for the complete isomerization of dimethyl maleate to dimethyl fumarate under solar-simulated light irradiation. This process also produced bulky fumarate ester derivatives at high yields (85–100%). A plausible mechanism of the bromine-initiated radical chain reaction was suggested by the results of the experimental data and density function theory calculations. The photoelectrochemical oxidation of NaBr generated the oxidized bromine species, which were then photolyzed to produce the bromine radical initiators induced by the photochemical process. This resulted in the high faradaic efficiency (98%) in the photoelectrochemical step and internal quantum yield (>100%) in the photoisomerization step. This newly developed process is an innovative and environmentally friendly strategy that goes beyond the conventional thermochemical process to achieve the precise synthesis of fumarate derivatives under mild conditions.

Microinjection of spermatozoa or spermatids into oocytes is a major choice for infertility treatment. However, the use of premeiotic spermatocytes has never been considered because of its technical problems. Here, we show that the efficiency of spermatocyte injection in mice can be improved greatly by reducing the size of the recipient oocytes. Live imaging showed that the underlying mechanism involves reduced premature separation of the spermatocyte's meiotic chromosomes, which produced much greater (19% vs. 1%) birth rates in smaller oocytes. Application of this technique to spermatocyte arrest caused by STX2 deficiency, an azoospermia factor also found in humans, resulted in the production of live offspring. Thus, the microinjection of primary spermatocytes into oocytes may be a potential treatment for overcoming a form of nonobstructive azoospermia caused by meiotic failure.

We have revealed for the first time that BiVO4 photoanodes can be used even in strong acid media by mixing organic solvents into the electrolyte and depositing multilayers with a WO3 bottom layer. ...

Photocatalytic water splitting is attracting considerable interest because it enables abundant solar energy to be converted into hydrogen for use as a zero-emission fuel or chemical feedstock. Herein, we present a universal approach for inserting hydrophilic non-conjugated building blocks into the main-chain of conjugated polymers to produce a series of discontinuously conjugated polymer (DCP) photocatalysts. Water can effectively be brought into the interior of DCPs through these hydrophilic non-conjugated building blocks, resulting in effective water/polymer interfaces inside the bulk DCPs in both thin-film and solution. P-10HEG with 10 mol% ethylene glycol-based hydrophilic building blocks achieved a record high apparent quantum yield of 17.82% under 460 nm monochromatic light irradiation in solution and an excellent hydrogen evolution rate of 16.8 mmol m− 2 h− 1 in thin-film. Molecular dynamics simulation shows a trend similar to that in experiments, which confirms that main-chain engineering increases the possibility of a water-DCP interaction. Unlike the previous strategy of maintaining a long conjugation length, our approach results in DCP photocatalysts with an interrupted conjugation length that remains efficient photocatalysis.

In the quest for efficient use of solar energy to produce high-value-added chemicals, we first achieved the photoelectrochemical (PEC) diketonization of naphthalene, using a BiVO

The present study was conducted to determine exact location where the acrosome reaction of fertilizing spermatozoa begins in the oviduct of the Chinese hamster. Unlike spermatozoa of other rodent species, Chinese hamster spermatozoa did not spontaneously undergo the acrosome reaction in fertilization-supporting media. In naturally mated females, spermatozoa in the uterus had intact acrosomes, whereas those in the lower oviductal isthmus had visibly thin acrosomal caps. The acrosomal cap was lost when spermatozoa passed through the cumulus oophorus. Thus, Chinese hamster spermatozoa begin the acrosome reaction in the lower isthmus and complete it in the cumulus oophorus. The mucosal epithelium of the oviductal isthmus released many "transparent" vesicles into the lumen, was very fragile and readily sloughed off by rough handling or rapid flushing with medium. Globular materials that oozed out of the dissected oviduct were most likely mucosa cells destroyed by rough handling. Although the oviducts of Chinese hamsters may be exceptionally delicate, this observation nevertheless warns us to cautiously handle the oviducts of any species when studying oviduct secretions that could be involved in inducing capacitation and the acrosome reaction of spermatozoa within the female genital tract.

While the large volume of mammalian oocytes is necessary for embryo development, it can lead to error-prone chromosomal segregation during meiosis. Conversely, we hypothesized that smaller oocytes would have a great unidentified potential to stabilize unstable meiosis and improve the development of the resultant embryos. Here, we show that reducing ooplasmic volume can rescue highly error-prone fertilization using primary spermatocytes by preventing segregation errors of chromosomes during biparental meiosis. High-resolution live-imaging analysis revealed that erroneous chromosome segregation occurred in most (90%) spermatocyte-injected oocytes of normal size, but could be ameliorated to 40% in halved oocytes. The birth rate improved remarkably from 1% to 19% (P < 0.0001). Importantly, this technique enabled the production of offspring from azoospermic mice with spermatocyte arrest caused by STX2 deficiency, an azoospermia factor also found in humans. Thus, contrary to popular opinion, oocytes inherently have a strong potential for precise meiotic divisions, which can be evoked by reduction of the ooplasmic volume. Their potential might help rescue cases of untreatable human azoospermia with spermatocyte arrest.

Non-bias production of a bleach aqueous solution was successfully demonstrated using a solar-driven photoelectrochemical cell consisting of a metal-oxide-semiconductor photoanode and Pt-based cathode. Both hypochlorous acid (HClO) and hypobromous acid (HBrO) were generated via two-electron oxidation of chloride (Cl−) and bromide (Br−) at the photoanode. The faradaic efficiency for HBrO production gradually improved with increasing Br− concentration in the electrolyte solution. Although a certain amount of HBrO was produced from a 1 mM NaBr aqueous solution, the co-existence of Cl− drastically enhanced the amount of HBrO produced from the dilute Br− solution. The use of a gas diffusion electrode (GDE) composed of a Pt/carbon catalyst layer for efficient 4-electron O2 reduction enabled us to achieve the anodic photocurrent derived from the oxidation of Cl− and Br− under AM-1.5 simulated solar light irradiation. Moreover, we successfully accomplished convenient and simple production of aqueous bleach from artificial sea water via irradiating the photoanode with simulated solar light without applying external bias.

Photoelectrochemical (PEC) oxidation of the divalent manganese ion to the permanganate ion was achieved by using porous WO3 thin film photoanodes in sulfuric acid electrolytes under simulated sunlight. In this reaction system, the subsequent reaction of the evolved MnO4− (Mn7+) with residual Mn2+ caused deterioration of photoanodes by Mn solid deposit formation. However, we realized stable PEC reaction by diffusion control of the evolved Mn7+ in the pores of the photoanodes. We also confirmed that the PEC reaction for the evolution of Mn7+ proceeded intrinsically very efficiently, and the faradaic efficiency reached 94.8% in an electrolyte containing 1.0 mM Mn2+ and 1.0 M H2SO4 at a low bias potential voltage of 1.3 VRHE. To use the photoelectrochemically evolved Mn7+ in sulfuric acid solutions effectively, a biphasic reaction involving the oxidation of ethylbenzene was carried out. The ethylbenzene added to the anode cell was converted to acetophenone without any byproducts, and this conversion occurred concurrently with the PEC reaction that produced Mn7+. At the cathode, evolution of hydrogen occurred with 95–99% faradaic efficiency. Thus, we have successfully demonstrated dual benefits of this reaction system: the production of high-value-added organic reagents mediated by the PEC-derived Mn7+ and the production of solar hydrogen.

We have revealed for the first time that BiVO

To improve the oxidative stability of biodiesel fuel (BDF), the polyunsaturated fatty acid methyl esters (poly-FAME) presented in commercial palm oil-derived biodiesel fuel (palm-BDF) were selectively hydrogenated to monounsaturated fatty acid methyl esters (mono-FAME) under a mild condition (80 °C, 0.5 MPa) using activated carbon (AC)-supported Pd catalysts with a Pd loading of 1 wt.%. The partially hydrotreated palm-BDF (denoted as H-FAME) which has low poly-FAME components is a new type of BDF with enhanced quality for use in high blends. In this study, we reported that the chemical states and particle sizes of Pd in the prepared Pd/AC catalysts were significantly influenced by the Pd precursors, Pd(NO3)2 and Pd(NH3)4Cl2, and thus varied their hydrogenation activity and product selectivity. The 1%Pd/AC (nit) catalyst, prepared using Pd(NO3)2, presented high performance for selective hydrogenation of poly-FAME into mono-FAME with high oxidation stability, owning to its large Pd particles (8.4 nm). Conversely, the 1%Pd/AC (amc) catalyst, prepared using Pd(NH3)4Cl2, contained small Pd particles (2.7 nm) with a little Cl residues, which could be completely removed by washing with an aqueous solution of 0.1 M NH4OH. The small Pd particles gave increased selectivity toward unwanted-FAME components, particularly the saturated fatty acid methyl esters during the hydrogenation of poly-FAME. This selectivity is unprofitable for improving the biodiesel quality.

The photo-electrochemical C-H bond activation of cyclohexane to produce cyclohexanol and cyclohexanone (KA oil) with high partial oxidation selectivity (99 %) and high current utilization ratio (76 %) was achieved in air at room temperature at atmospheric pressure. The production rate of KA oil was accelerated by applying a bias. The incident photon to current efficiencies at 365 and 420 nm were 57 % and 24 %, respectively.

Electrooxidative copolymerization of 3,4-ethylenedioxithiophene (EDOT) and benzene from a mixture of the monomers with concentrations of 5 mM EDOT and 5 M benzene produced copolymer films on an anode surface. The formation of copolymer films and characterization of their electrochemical properties was confirmed using Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible absorption (UV–vis) spectroscopy, energy dispersive X-ray (EDX) spectroscopy, cyclic voltammetry (CV), and solid-state carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy measurements. Furthermore, the copolymerization ratio could be controlled by selection of the oxidation potential applied for copolymerization.

In order to protect sperm chromosomes against degradation when they are being stored for relatively high temperatures, we investigated the optimal pH of the freeze-drying solution, EGTA/Tris-HCl buffered solution alkalinized by NaOH (Na-ETBS) or KOH (K-ETBS). Mouse spermatozoa suspended in Na-ETBS or K-ETBS were freeze-dried at pH 5.0–8.4 and stored at 4 °C or 50 °C for 3 days. Some freeze-dried samples were stored at 25 °C for 3 days or 1 month. After storage, samples injected into oocytes using intracytoplasmic sperm injection were assessed for chromosome damage in resulting zygotes. Irrespective of freeze-drying solutions and storage temperatures, almost all the zygotes (97–100%) produced using the spermatozoa freeze-dried at pH 5.0 had structural chromosome aberrations of sperm origin. When freeze-drying was conducted at pH 8.0–8.4 using Na-ETBS, the incidence of chromosome damage decreased to 14–17% in 4 °C storage and 24–26% in 50 °C storage. When freeze-dried in K-ETBS, the lowest level of chromosome damage occurred at pH levels of 7.7–8.4 at 4 °C storage (13–15%) and at pH 7.7–8.0 at 50 °C storage (16–23%). Spermatozoa freeze-dried in Na-ETBS at pH 8.2 and K-ETBS at pH 7.7 showed no significant increase in chromosome damage during 25 °C storage from 3 days to 1 month (11%–20% in Na-ETBS; 13%–18% in K-ETBS). Thus, use of the solutions optimized for short-term storage at high temperature (50 °C, 3 days) permits prolonged storage (1 month) of freeze-dried spermatozoa at room temperature.

The photo-assisted electrochemical oxidation of benzylic alcohol derivatives was achieved with excellent yields up to 97% at low applied potential under visible light irradiation (>420 nm) using a BiVO₄/WO₃ photoelectrode in aprotic organic media. The faradaic efficiencies for oxidation of 1-phenylethyl alcohol was very high (>99%) in 0.1 M Bu₄NBF₄/MeCN. The applied potentials for the oxidation of benzylic alcohols (approximately +0.7 V vs. SHE) were considerably lower than those of the Pt electrodes (approximately +1.9 V vs. SHE). The turnover number of moles of oxidation product per moles of BiVO₄ was approximately 1200.

The fundamental advantages and potential benefits of flow microreactor technology include extremely large surface-to-volume ratios, precise control over temperature and residence time, extremely fast molecular diffusion, and increased safety during reactive processes. These advantages and benefits can be applied to a wide range of electrosynthetic techniques, and so the integration of flow microreactors with electrosynthesis has received significant research interest from both academia and industry. This review presents an up-to-date overview of electrosynthetic processes in continuous-flow microreactors. In addition, the advantages of continuous-flow electrochemistry are discussed, along with a thorough comparison of microreactor-based processes and conventional batch reaction systems.

The purpose of this study was to evaluate the effects of 3rd-generation (3G) cellular phone radiofrequency–electromagnetic wave (RF-EMW) exposure on fertilization and embryogenesis in mice. Oocytes and spermatozoa were exposed to 3G cellular phone RF-EMWs, 1.95 GHz wideband code division multiple access, at a specific absorption rate of 2 mW/g for 60 min, or to sham exposure. After RF-EMW exposure, in vitro fertilization and intracytoplasmic sperm injection were performed. Rates of fertilization, embryogenesis (8-cell embryo, blastocyst), and chromosome aberration were compared between the combined spermatozoa and oocyte groups: both exposed, both non-exposed, one exposed, and the other non-exposed. Rates of fertilization, embryogenesis, and blastocyst formation did not change significantly across the four groups. Considering that the degree of exposure in the present study was ≥100 times greater than daily exposure of human spermatozoa and even greater than daily exposure of oocytes, the present results indicate safety of RF-EMW exposure in humans. Bioelectromagnetics. 38:466–473, 2017. © 2017 Wiley Periodicals, Inc.

A new approach for the synthesis and molecular weight control of poly(3-hexylthiophene) (P3HT) using electrochemical polymerization in a flow microreactor is described. This synthetic system enabled electrochemical synthesis of soluble P3HT without its deposition using a flow microreactor. Careful selection of the reaction conditions enabled the control of molecular weight and distribution of the synthesized P3HT.

A new approach for the green synthesis of α-amino acids using electrochemical carboxylation of imines in a flow microreactor is described. This method has the major advantage of not requiring sensitive, expensive, or toxic reagents. In addition, the reaction could be conducted using single flow-through operations, without the need for sacrificial anodes and under very mild and green conditions. Our microreactor system enabled the electrochemical synthesis of N-phenylphenylglycine derivatives in good to moderate yields.

Photoelectrochemical dimethoxylation of furan with methanol using a BiVO4/WO3 photoanode and Br+/Br- as a mediator was demonstrated with low applied potential. The faradaic efficiency for the dimethoxylation with a Et4NBF4 co-supporting electrolyte at +0.1 V vs. SHE was almost quantitative up to 99%.

The photo-electrochemical oxidation of cyclohexene to 2-cyclohexene-1-one was successfully performed with excellent Faraday efficiency (>99%) via indirect oxidation with a PINO/NHPI mediator and O2 on a BiVO4/WO3 photoanode under low applied bias.

In order to develop an efficient and greener method for organic chemical hydride production in the energy carrier system, the electrocatalytic hydrogenation of toluene to methylcyclohexane was carried out using a proton exchange membrane (PEM) reactor, which generally applied a polymer electrolyte fuel cell and industrial electrolysis technologies. The electrochemical conversion proceeded in high current efficiencies (>90%) under sufficiently mild conditions with various metal-supported catalysts such as Pt/C, Rh/C, Ru/C, and PtRu/C. For example, methylcyclohexane was obtained in 94% current efficiency by the electrochemical hydrogenation of toluene with PtRu/C. Although the current efficiency of the hydrogenation with Pt/C, Rh/C, and Ru/C apparently decreased under high current density conditions due to the side reaction (hydrogen evolution), the hydrogenation with PtRu/C catalysts proceeded in excellent efficiencies even under high current density conditions.

The electrocatalytic hydrogenation of o-xylene in a proton-exchange membrane (PEM) reactor with various cathode catalysts was carried out as a study of a model reaction for hydrogen storage. o-Xylene introduced in a PEM reactor underwent electrocatalytic hydrogenation to provide cis-1,2-dimethylcyclohexane as the main stereoisomer with moderate to good current efficiencies. The reaction proceeded in accordance with the Langmuir–Hinshelwood mechanism.

The use of highly concentrated pyrrole solution enabled simultaneous effective monomer transport into the porous electrode and uniform polarization inside the porous electrode even at an ambient temperature. As a result, the uniform polymer deposition could be successfully carried out on the porous electrode entirely even its inside.

The photo-electrochemical C-H bond activation of cyclohexane to produce cyclohexanol and cyclohexanone (KA oil) with high partial oxidation selectivity (99 %) and high current utilization ratio (76 %) was achieved in air at room temperature at atmospheric pressure. The production rate of KA oil was accelerated by applying a bias. The incident photon to current efficiencies at 365 and 420 nm were 57 % and 24 %, respectively.

The electrochemical properties of novel reaction media, ionic liquid (IL)/supercritical CO 2 (scCO 2 ) systems, were evaluated and the electrochemical carboxylation of various organohalides in these systems was demonstrated. Voltammetric studies revealed that the CO 2 solubility in an IL such as N , N -diethyl- N -methyl- N -(2-methoxyethyl) ammonium bis(trifluoromethanesulfonyl) imide ([DEME][TFSI]) increased in the presence of scCO 2 . The IL/scCO 2 systems were found to be effective for the electrochemical carboxylation of various organohalides.

We have successfully demonstrated an efficient anodic aromatic C,C cross-coupling reaction using parallel laminar flow mode in a two-inlet flow microreactor. The model reaction proceeded effectively even in single flow-through operations and the desired cross-coupling product was obtained in much higher current yields compared to the reaction in a conventional batch type cell.

We have successfully demonstrated effective generation of an electrogenerated base (EGB) such as the 2-pyrrolidone anion and its rapid use for the following alkylation reaction in a flow microreactor system without the need for severe reaction conditions. The key feature of the method is effective and selective preparation of monoalkylated products.

We demonstrated in situ preparation of unstable trichloromethyl anion and its reaction with benzaldehyde in an electrochemical flow microreactor at ambient temperature. The trichloromethyl anion was prepared by the reaction of chloroform with an electrogenerated base. The generated unstable anion was rapidly used for following reaction with benzaldehyde before decomposition, and 2,2,2-trichloro-1-phenylethanol was obtained in a reasonable yield.

In order to protect sperm chromosomes against degradation when they are being stored for relatively high temperatures, we investigated the optimal pH of the freeze-drying solution, EGTA/Tris-HCl buffered solution alkalinized by NaOH (Na-ETBS) or KOH (K-ETBS). Mouse spermatozoa suspended in Na-ETBS or K-ETBS were freeze-dried at pH 5.0-8.4 and stored at 4 °C or 50 °C for 3 days. Some freeze-dried samples were stored at 25 °C for 3 days or 1 month. After storage, samples injected into oocytes using intracytoplasmic sperm injection were assessed for chromosome damage in resulting zygotes. Irrespective of freeze-drying solutions and storage temperatures, almost all the zygotes (97-100%) produced using the spermatozoa freeze-dried at pH 5.0 had structural chromosome aberrations of sperm origin. When freeze-drying was conducted at pH 8.0-8.4 using Na-ETBS, the incidence of chromosome damage decreased to 14-17% in 4 °C storage and 24-26% in 50 °C storage. When freeze-dried in K-ETBS, the lowest level of chromosome damage occurred at pH levels of 7.7-8.4 at 4 °C storage (13-15%) and at pH 7.7-8.0 at 50 °C storage (16-23%). Spermatozoa freeze-dried in Na-ETBS at pH 8.2 and K-ETBS at pH 7.7 showed no significant increase in chromosome damage during 25 °C storage from 3 days to 1 month (11%-20% in Na-ETBS; 13%-18% in K-ETBS). Thus, use of the solutions optimized for short-term storage at high temperature (50 °C, 3 days) permits prolonged storage (1 month) of freeze-dried spermatozoa at room temperature.

We have successfully developed a novel cathodic cross-coupling reaction of aryl halides with arenes. Utilization of the cathodic single electron transfer (SET) mechanism for activation of aryl halides enables the cross-coupling reaction to proceed without the need for any transition metal catalysts or single electron donors in a mild condition. The SET from a cathode to an aryl halide initiates a radical chain by giving an anion radical of the aryl halide. The following propagation cycle also consists entirely of anion radical intermediates.

Ca2+ ionophore A23187 is known to induce the acrosome reaction of mammalian spermatozoa, but it also quickly immobilizes them. Although mouse spermatozoa were immobilized by this ionophore, they initiated vigorous motility (hyperactivation) soon after this reagent was washed away by centrifugation. About half of live spermatozoa were acrosome-reacted at the end of 10 min of ionophore treatment; fertilization of cumulus-intact oocytes began as soon as spermatozoa recovered their motility and before the increase in protein tyrosine phosphorylation, which started 30-45 min after washing out the ionophore. When spermatozoa were treated with A23187, more than 95% of oocytes were fertilized in the constant presence of the protein kinase A inhibitor, H89. Ionophore-treated spermatozoa also fertilized 80% of oocytes, even in the absence of HCO3-, a component essential for cAMP synthesis under normal in vitro conditions. Under these conditions, fertilized oocytes developed into normal offspring. These data indicate that mouse spermatozoa treated with ionophore are able to fertilize without activation of the cAMP/PKA signaling pathway. Furthermore, they suggest that the cAMP/PKA pathway is upstream of an intracellular Ca2+ increase required for the acrosome reaction and hyperactivation of spermatozoa under normal in vitro conditions. Fil: Tateno, Hiroyuki. Asahikawa Medical University. Department of Biological Sciences; Japón Fil: Krapf, Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; Argentina Fil: Hino,Toshiaki. Asahikawa Medical University. Department of Biological Sciences; Japón Fil: Sánchez Cárdenas, Claudia. Universidad Nacional Autonoma de Mexico. Instituto de Biotecnologia; México Fil: Darszon, Alberto. Universidad Nacional Autonoma de Mexico. Instituto de Biotecnologia; México Fil: Yanagimachi, Ryuzo. University of Hawaii Medical School. Institute for Biogenesis Research; Estados Unidos Fil: Visconti, Pablo E.. University Of Massachussets; Estados Unidos

The purpose of this study was to evaluate the effects of 3rd-generation (3G) cellular phone radiofrequency-electromagnetic wave (RF-EMW) exposure on fertilization and embryogenesis in mice. Oocytes and spermatozoa were exposed to 3G cellular phone RF-EMWs, 1.95 GHz wideband code division multiple access, at a specific absorption rate of 2 mW/g for 60 min, or to sham exposure. After RF-EMW exposure, in vitro fertilization and intracytoplasmic sperm injection were performed. Rates of fertilization, embryogenesis (8-cell embryo, blastocyst), and chromosome aberration were compared between the combined spermatozoa and oocyte groups: both exposed, both non-exposed, one exposed, and the other non-exposed. Rates of fertilization, embryogenesis, and blastocyst formation did not change significantly across the four groups. Considering that the degree of exposure in the present study was ≥100 times greater than daily exposure of human spermatozoa and even greater than daily exposure of oocytes, the present results indicate safety of RF-EMW exposure in humans. Bioelectromagnetics. 38:466-473, 2017. © 2017 Wiley Periodicals, Inc.

Author, PURPOSE: Incorporation of a second polar body (PB2) into one of the blastomeres has been considered as a causal mechanism underlying diploid/triploid mixoploidy in humans. Using a mouse model, we examined whether PB2s can participate in the formation of mixoploidy. METHODS: Uptake of BrdU was examined to determine DNA synthesis in PB2s up to 28h after fertilization. PB2s from embryos at 4-6 (1-cell), 24 (2-cell), 48 (4-cell), and 72h (morula) were fused with MII oocytes to induce premature chromosome condensation. Caspase and TUNEL assays were used to detect apoptotic PB2s at 24, 48, and 72h. PB2s were fused with one of the blastomeres of the 2-cell embryos to produce mixoploid embryos. RESULTS: DNA synthesis in the PB2s continued until 22h after fertilization. At 4-6h, nearly all of the PB2s showed G1-type chromosomes and there was no significant increase in chromosome damage. At 24, 48, and 72h, S-type chromatin predominated. Few PB2s showed apoptotic response until 72h. Regardless of the fusion with the PB2, more than 90% of the embryos developed to 4-cell stage, and over 80% of the resultant 4-cell embryos had daughter blastomeres with a morphologically normal nucleus. Some of the daughter blastomeres displayed triploidy. CONCLUSIONS: The PB2 is viable for at least 72h after fertilization, with slow progression through the cell cycle. Once the PB2 has been incorporated into a blastomere, the cell cycle of the PB2 might be synchronized with that of the host resulting in diploid/triploid mixoploidy.

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Mutagenesis following peer review. The definitive publisher-authenticated version Kusakabe, Hirokazu ; Tateno, Hiroyuki, Mutagenesis, 26(3), 447-453. is available online at: http://mutage.oxfordjournals.org/content/26/3/447., Structural chromosome aberrations and DNA damage generated in freeze-dried mouse spermatozoa were investigated. Freeze-dried sperm samples were preserved at 4, 25 and 50℃ for short duration (1 day to 2 months) and at 25℃ for long duration (2 years). The spermatozoa were injected into mouse oocytes to analyse the chromosomes of the zygotes at the first cleavage metaphase. Chromosome break of the chromosome-type aberrations was the most common type of structural chromosome aberrations observed in all freeze-dried samples. The frequency of chromatid exchanges rapidly increased in freeze-dried spermatozoa preserved at 50℃ for 1-5 days. The frequency of chromatid-type aberrations (break and exchange) gradually increased in freeze-dried spermatozoa preserved at 25℃ for up to 2 months. Alkaline comet assay revealed significant migration of damaged DNA accumulated in freeze-dried spermatozoa preserved at 50℃ for 3 days and 25℃ for 2 years. However, no DNA damage was detected using the same sperm samples by neutral comet assay, which can detect mostly DNA double-strand breaks in cellular DNA. These results suggest that DNA single-strand breaks were accumulated in freeze-dried spermatozoa preserved under ambient or heat conditions, and then chromatid-type aberrations, especially the chromatid exchanges, were formed via post-replication repair system in zygotes.

Author, We investigated whether the small litter size in the 129 inbred mouse strain results from a reduction in oocyte fertilizability. Sensitivity of the zona pellucida to α-chymotrypsin was examined for oocytes collected at 14 h (shortly after ovulation), 17 h, and 20 h after hCG injection. Passage of spermatozoa through the zona pellucida (using an in vitro fertilization (IVF) technique) and the density of cortical granules were examined for oocytes collected at 14 and 17 h after hCG injection. The capability of the oolemma to fuse with the sperm plasma membrane was also evaluated by IVF using zona-free eggs. The zona pellucida became markedly resistant to the enzyme 17 h after hCG injection. IVF rates significantly decreased at this time. In addition, there was a significant reduction in the density of cortical granules. When zona-free oocytes were inseminated, high fertilization rates were obtained at both 17 and 14 h after hCG injection. These results indicate that accelerated modification of the zona pellucida primarily causes a decreased fertilizability of oocytes in 129 mice, resulting in the low reproductive performance of this strain.

This study was performed to investigate whether removal of cholesterol from the plasma membrane and collapse of the acrosome can prevent structural chromosome aberrations of paternal origin in mouse zygotes produced by intracytoplasmic sperm injection (ICSI).Mouse spermatozoa were treated with methyl-beta-cyclodextrin (M beta CD) to remove cholesterol from the plasma membrane and with calcium ionophore A23187 to collapse the acrosome. Chromosomes of zygotes derived from M beta CD- and ionophore-treated spermatozoa were analyzed at the first mitotic metaphase.Both chemical agents effectively induced the acrosome reaction. Incidence of structural chromosome aberrations in ICSI zygotes derived from M beta CD-treated spermatozoa was similar to that in zygotes produced by in vitro fertilization (IVF) with the same spermatozoa, but significantly lower compared to ICSI zygotes derived from acrosome-intact spermatozoa. Chromosome aberration rates in ICSI zygotes derived from ionophore-treated spermatozoa were evidently high compared to IVF zygotes.Induction of the acrosome reaction through cholesterol efflux by M beta CD can prevent chromosome aberrations of paternal origin, while use of ionophore to induce the acrosome reaction exerts detrimental effect on paternal chromosomes in ICSI zygotes.

The original publication is available at www.springerlink.com, Incidence of structural chromosome aberrations in mouse one-cell embryos produced by intracytoplasmic sperm injection (ICSI) with mature epididymal spermatozoa were influenced by sperm incubation medium and time. When spermatozoa were incubated in bicarbonate-buffered TYH for ≤0.5 h, the embryo aberration rates were significantly higher than in vitro fertilization (IVF) embryos. However, after the incubation of spermatozoa in the same medium for ≥2 h, the aberration rates were close to the IVF embryo level. When spermatozoa were incubated in bicarbonate-buffered mCZB, hepes-buffered H-TYH and H-mCZB, and phosphate-buffered PB1, the increased incidences of aberrations were observed at any incubation time. In the case of sperm incubation in H-TYH, H-mCZB and PB1, the aberration rates increased in a time-dependent manner. Chromosome aberrations generated by ICSI were transmissible to offspring. On the other hand, the aberration rate in embryos derived from testicular spermatozoa was independent of the medium type and incubation time. Thus, the incubation media appears to have no effect on sperm chromatin. TYH can effectively induce capacitation and acrosome reaction, while H-TYH, H-mCZB and PB1 never induce these spermatozoal events. It is probable that the cholesterol-rich plasma membrane and intact acrosome injected into the ooplasm affect sperm chromatin remodeling, thus resulting in the generation of chromosome damage in ICSI embryos.