Gradient Design of Vacancies and Their Positive Correlation with Electrochemical Anticorrosion Protection.

The contribution of defects to electrochemistry is a controversial but practically applicable subject. Meanwhile, it is challenging to obtain precisely a certain nonchemometric single phase in mixed-valence compounds. The precise design of nonchemometric single-phase WO3-x (x = 0, 0.1, 0.28, and 1) mixed-valence metal oxides (MVMOs) was achieved by the gradient intrinsic reduction method, and the correlation between oxygen vacancies and electrochemical anticorrosion protection was explored systematically. Then, the decisive role of periodic oxygen vacancies in electrochemical anticorrosion was confirmed. And the origin was the synergistic reaction of oxygen vacancy-upgraded photocathodic protection, vacancy-induced passivation, and mixed-valence reductive protection, which were brought about by the high oxygen vacancy concentration. Integrating the above three aspects, the WO2.72 MVMO showed the best electrochemical anticorrosion performance by increasing the resistance value to 7.67 times that of the epoxy resin coating. The establishment of a positive correlation between oxygen vacancy and corrosion protection in WO3-x (x = 0, 0.1, 0.28, and 1) materials can not only guide the design of MVMOs but also make an important contribution to the rapid precorrosion performance of the materials.

Effect of NANOG overexpression on porcine embryonic development and pluripotent embryonic stem cell formation in vitro.

The efficiency of establishing pig pluripotent embryonic stem cell clones from blastocysts is still low. The transcription factor Nanog plays an important role in maintaining the pluripotency of mouse and human embryonic stem cells. Adequate activation of Nanog has been reported to increase the efficiency of establishing mouse embryonic stem cells from 3.5 day embryos. In mouse, Nanog starts to be strongly expressed as early as the morula stage, whereas in porcine NANOG starts to be strongly expressed by the late blastocyst stage. Therefore, here we investigated both the effect of expressing NANOG on porcine embryos early from the morula stage and the efficiency of porcine pluripotent embryonic stem cell clone formation. Compared with intact porcine embryos, NANOG overexpression induced a lower blastocyst rate, and did not show any advantages for embryo development and pluripotent embryonic stem cell line formation. These results indicated that, although NANOG is important pluripotent factor, NANOG overexpression is unnecessary for the initial formation of porcine pluripotent embryonic stem cell clones in vitro.

Fetal bovine serum promotes the development of in vitro porcine blastocysts by activating the Rho-associated kinase signalling pathway.

Fetal bovine serum (FBS) supplementation has beneficial effects on invitro porcine embryonic development, but the underlying mechanisms are unclear. In the present study we found that the addition of FBS to PZM-3 increased the number of cells in porcine blastocysts and hatching rate invitro primarily by promoting proliferation of the inner cell mass and further differentiation. Moreover, based on the following results, we surmise that FBS benefits blastocyst development by activating Rho-associated kinase (ROCK) signalling: (1) the ROCK signalling inhibitor Y-27632 decreased the blastocyst rate and the number of cells in blastocysts, whereas FBS rescued the developmental failure induced by Y-27632; (2) the mRNA levels of two ROCK isoforms, ROCK1 and ROCK2, were significantly increased in blastocysts derived from medium containing FBS; and (3) FBS increased RhoA/Rho-kinase expression in the nucleus of embryonic cells. These results indicate that FBS promotes the invitro development of porcine embryos by activating ROCK signalling in a chemically defined medium.

[Analysis of SOX2 gene promoter activity in porcine early embryonic development].

SOX2 (sex determining region Y-box2) is one of the critical pluripotent factors that play a crucial role in the first lineage differentiation and maintenance of pluripotency in inner cell mass during early embryonic development. However, there are few researches about the regulation of the SOX2 promoter, especially in Sus scrofa. To analyzed the activity of SOX2 promoter in early porcine embryos, we determined the control system and established the microinjection system for assessing SOX2 promoter activity by analyzing the embryonic development and the expression of enhanced green fluorescence protein (EGFP) after micro-injected different EGFP plasmids at different times after activation of the oocytes. Then, we analyzed the structure of 5000 bp upstream of the SOX2 translation initiation site and found there were four transcription factor binding site clusters. Next, we designed and constructed promoter-containing plasmids to analyze the function of each cluster. To detect the activity of different promoters, we assessed the mCherry expression in protein levels and mRNA levels by analyzing the mCherry fluorescence intensity and qRT-PCR after injecting plasmids into embryos. These results showed that the activity of the shorted promoter, with the region from 2254 bp to 2442 bp upstream of translation initiation site deleted, decreased to 17.8% at 4-cell and 8-cell stages compared with the full-length promoter. This region included two NF-AT transcription factor binding sites, which indicated that the NF-AT binding site is a key region to regulate the activity of the SOX2 promoter. The results provide important data for determination the mechanism of porcine SOX2 regulation.

SINE-Associated LncRNA SAWPA Regulates Porcine Zygotic Genome Activation.

In mice, retrotransposon-associated long noncoding RNAs (lncRNA) play important regulatory roles in pre-implantation development; however, it is largely unknown whether they function in the pre-implantation development in pigs. The current study aims to screen for retrotransposon-associated lncRNA in porcine early embryos and identifies a porcine 8-cell embryo-specific SINE-associated nuclear long noncoding RNA named SAWPA. SAWPA is essential for porcine embryonic development as depletion of SAWPA results in a developmental arrest at the 8-cell stage, accompanied by the inhibition of the JNK-MAPK signaling pathway. Mechanistically, SAWPA works in trans as a transcription factor for JNK through the formation of an RNA-protein complex with HNRNPA1 and MED8 binding the SINE elements upstream of JNK. Therefore, as the first functional SINE-associated long noncoding RNAs in pigs, SAWPA provides novel insights for the mechanism research on retrotransposons in mammalian pre-implantation development.

OCT4 expression transactivated by GATA protein is essential for non-rodent trophectoderm early development.

Oct4 is exclusively expressed in rodent inner cell mass (ICM) but silenced in its trophectoderm (TE). However, for many non-rodent animals, including pig, cattle, rabbit, goat, and human, OCT4 has a remarkable expression in early TE. This study, applying pig as the main research model, proves that OCT4 expression in TE is supported by a unique GATA motif in the OCT4 upstream conserved regulatory region, and GATA4 is responsible for its activation. Moreover, OCT4 acts as a specific regulator of a narrow range of genes (including BCL2A1 and HNRNP2AB1) that are essential for the first wave of rapid proliferation in early TE. This study describes the regulatory mechanism to direct the OCT4 expression and its significance in TE of porcine preimplantation embryo.