Palladium(ii)-catalyzed decarboxylative meta-C–H difluoromethylation reactions have been developed. Initial mechanistic studies disclosed that a migratory insertion would be involved in this meta-selective C–H functionalization.
Cloned pigs generated by the somatic cell transfer nuclear (SCNT) technique are highly valuable for agriculture, biomedicine, and life sciences. However, the neonatal mortality rate of cloned pigs is very high. The reasons causing the massive loss of cloned pigs during their neonatal ages are unclear. In the present study, we found that the neonatal death of cloned pigs was associated with aberrant purine metabolism, impaired renal morphology and function, and decreased hepatic Hprt1 expression. The downregulation of Hprt1, a key purine metabolism regulation gene, in the liver was responsible for the elevation of an important purine metabolite, uric acid, in the serum, causing abnormalities in kidney morphology and function and leading to death of neonatal cloned pigs. This study provided insights into the pathophysiological mechanisms underlying the neonatal death of clone pigs, and results will help improve their survival rate.
In this paper, electromagnetic emissions recorded by a borehole TOA installment with three observing channels of CH1 (0.01 -0.1 Hz), CH2 (0.1 -1.0 Hz) and CH3 (1 -9 kHz) before four large earthquakes with magnitudes more than 8.0 have been depicted. These abnormities present different fluctuating processes from one another. For the Wenchuan M S 8.0 earthquake on 12 May 2008, the nearest one among these four events and only 660 km from the TOA station, electromagnetic information appeared at least 5 months ago in two low frequency bands of CH1 and CH2 and it was subjected to an obvious fluctuating process with several developing stages: initial information, intensive anomaly and large amplitude signals. The typical pulse-like emissions in CH2 happened group by group with large various magnitudes, which can be of 10 mV in the climax period. While during this period, compatible wave-like information with little magnitudes also happened in CH1 channel and a few pulses in CH3. Anomalous emissions occurred about 4 months prior to the 25 April 2015 Nepal M S 8.1 event, 1560 km away from the TOA station. The abnormal information in CH2 also appeared group by group but with small various magnitudes, more than 2 mV during their climax. This process is also effective for the Sumatra M S 8.9 earthquake on 26 December 2004, 2500 km from the borehole TOA, only with a different duration of 2 months and less magnitudes of 0.1 mV in CH1 and 1 mV in CH2 in this case. However, there is no obvious fluctuation and only small constant amplitude signals being ~0.15 mV appeared during 2 weeks before the Japan M S 9.0 earthquake on 11 March 2011. It is the farthest one among these four events and beyond 4000 km from the observing station. So, we can make a conclusion that there is a near relationship between the properties of the abnormi-How to cite this paper:ties associated with these four earthquakes, such as amplitudes, duration and signal types, and the distances from TOA station: on one hand, the amplitude and duration decreases as the distance increases; on the other hand, there is an evolution for emission properties from complex various magnitude signals to single equal magnitude ones as the distance changes to be far. However, one common feature of the anomalous information related to these four events is that almost electromagnetic emissions were collected in two low frequency bands of CH2 and CH1 instead of CH3 band, which means ULF band (0.01 -1.0 Hz) is more sensitive than VLF band (1 -9 kHz) at this TOA station.
The technique of cloning has wide applications in animal husbandry and human biomedicine. However, the very low developmental efficiency of cloned embryos limits the application of cloning. Ectopic XIST-expression-induced abnormal X chromosome inactivation (XCI) is a primary cause of the low developmental competence of cloned mouse and pig embryos. Knockout or knockdown of XIST improves cloning efficiency in both pigs and mice. The transcription factor Yin yang 1(YY1) plays a critical role in XCI by triggering the transcription of X-inactive specific transcript (XIST) and facilitating the localization of XIST RNA on the X chromosome. This study aimed to investigate whether RNA interference to suppress the expression of YY1 can inhibit erroneous XIST expression, rescue abnormal XCI, and improve the developmental ability of cloned pig embryos. The results showed that YY1 binds to the 5′ regulatory region of the porcine XIST gene in pig cells. The microinjection of YY1 siRNA into cloned pig embryos reduced the transcript abundance of XIST and upregulated the mRNA level of X-linked genes at the 4-cell and blastocyst stages. The siRNA-mediated knockdown of YY1 altered the transcriptome and enhanced the in vitro and in vivo developmental efficiency of cloned porcine embryos. These results suggested that YY1 participates in regulating XIST expression and XCI in cloned pig embryos and that the suppression of YY1 expression can increase the developmental rate of cloned pig embryos. The present study established a new method for improving the efficiency of pig cloning.
Oocytes matured in vitro are useful for assisted human and farm animal reproduction. However, the quality of in vitro matured oocytes is usually lower than that of in vivo matured oocytes, possibly due to the absence of some important signal regulators in vitro. In this study, untargeted metabolomics was used to detect the changes in the metabolites in the follicular fluid (FF) during in vivo pig oocyte maturation and in the culture medium during in vitro maturation. Our results showed that the total metabolite changing profile of the in vivo FF was different from that of the in vitro maturation medium, but the levels of 23 differentially expressed metabolites (DEMs) changed by following the same trend during both in vivo and in vitro pig oocyte maturation. These 23 metabolites may be important regulators of porcine oocyte maturation. We found that progesterone and androstenedione, two factors in the ovarian steroidogenesis pathway enriched from the DEMs, were upregulated in the FF during in vivo pig oocyte maturation. The levels of these two factors were 31 and 20 fold, respectively, and they were higher in the FF than in the culture medium at the oocyte mature stage. The supplementation of progesterone and androstenedione during in vitro maturation significantly improved the pig oocyte maturation rate and subsequent embryo developmental competence. Our finding suggests that a metabolic abnormality during in vitro pig oocyte maturation affects the quality of the matured oocytes. This study identified some important metabolites that regulate oocyte maturation and their developmental potential, which will be helpful to improve assisted animal and human reproduction.
The quality of in vitro matured oocytes is inferior to that of in vivo matured oocytes, which translates to low developmental capacity of embryos derived from in vitro matured oocytes. The developmental potential of in vitro matured oocytes is usually impaired due to oxidative stress. Stromal cell-derived factor-l (SDF1) can reduce oxidative stress and inhibit apoptosis. The aim of this study was to investigate the effects of SDF1 supplementation during pig oocyte in vitro maturation (IVM) on subsequent embryo development, and to explore the acting mechanisms of SDF1 in pig oocytes. We found that the IVM medium containing 20 ng/mL SDF1 improved the maturation rate of pig oocytes, as well as the cleavage rate and blastocyst rate of embryos generated by somatic cell nuclear transfer, in vitro fertilization, and parthenogenesis. Supplementation of 20 ng/mL SDF1 during IVM decreased the ROS level, increased the mitochondrial membrane potential, and altered the expression of apoptosis-related genes in the pig oocytes. The porcine oocyte transcriptomic data showed that SDF1 addition during IVM altered the expression of genes enriched in the purine metabolism and TNF signaling pathways. SDF1 supplementation during pig oocyte IVM also upregulated the mRNA and protein levels of YY1 and TET1, two critical factors for oocyte development. In conclusion, supplementation of SDF1 during pig oocyte IVM reduces oxidative stress, changes expression of genes involved in regulating apoptosis and oocyte growth, and enhances the ability of in vitro matured pig oocytes to support subsequent embryo development. Our findings provide a theoretical basis and a new method for improving the developmental potential of pig in vitro matured oocytes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.