Students' Perceived Well-Being and Online Preference: Evidence from Two Universities in Vietnam during COVID-19.

University education is still being impacted two years after the COVID-19 outbreak. We performed a rapid survey in February 2022 at two public universities in Vietnam to examine the effects of the pandemic on well-being and the factors that may associate with online class preference among university students as well as to investigate the need for support to improve resilience. A web-based survey included 1589 undergraduate students in total. Both quantitative and qualitative data analysis was carried out. Overall, approximately a quarter of respondents said that they perceived an influence on their health, 42.9% expressed stress, and more than 70% reported worrying about the future. In total, 61.9% of the respondents reported having satisfaction with online classes, while over half of them preferred a program of 50% online classes. Students who live in an urban area, are female, have had pre-COVID-19 campus life experience, have decreased income, and/or experience low online satisfaction and over-information may be in need of more support. The results show implications for universities to consider policies addressing well-being and post-pandemic online education. Providing support to university students to improve their resilience against the impact on their studying, campus life, health, and well-being should be prioritized during and post-pandemic.

One-Step Generation of Multiple Gene-Edited Pigs by Electroporation of the CRISPR/Cas9 System into Zygotes to Reduce Xenoantigen Biosynthesis.

Xenoantigens cause hyperacute rejection and limit the success of interspecific xenografts. Therefore, genes involved in xenoantigen biosynthesis, such as GGTA1, CMAH, and B4GALNT2, are key targets to improve the outcomes of xenotransplantation. In this study, we introduced a CRISPR/Cas9 system simultaneously targeting GGTA1, CMAH, and B4GALNT2 into in vitro-fertilized zygotes using electroporation for the one-step generation of multiple gene-edited pigs without xenoantigens. First, we optimized the combination of guide RNAs (gRNAs) targeting GGTA1 and CMAH with respect to gene editing efficiency in zygotes, and transferred electroporated embryos with the optimized gRNAs and Cas9 into recipient gilts. Next, we optimized the Cas9 protein concentration with respect to the gene editing efficiency when GGTA1, CMAH, and B4GALNT2 were targeted simultaneously, and generated gene-edited pigs using the optimized conditions. We achieved the one-step generation of GGTA1/CMAH double-edited pigs and GGTA1/CMAH/B4GALNT2 triple-edited pigs. Immunohistological analyses demonstrated the downregulation of xenoantigens; however, these multiple gene-edited pigs were genetic mosaics that failed to knock out some xenoantigens. Although mosaicism should be resolved, the electroporation technique could become a primary method for the one-step generation of multiple gene modifications in pigs aimed at improving pig-to-human xenotransplantation.

Generation of CD163-edited pig via electroporation of the CRISPR/Cas9 system into porcine in vitro-fertilized zygotes.

CD163 is a putative fusion receptor for virus of porcine reproductive and respiratory syndrome (PRRS). In this study, we introduced a CRISPR/Cas9 system [guide RNAs (gRNAs) with Cas9 protein] targeting the CD163 gene into in vitro-fertilized porcine zygotes by electroporation to generate CD163-modified pigs. First, we designed four types of gRNAs that targeted distinct sites in exon 7 of the CD163 gene. Cas9 protein with different gRNAs was introduced into in vitro-fertilized zygotes by electroporation. When the electroporated zygotes were allowed to develop to blastocysts in vitro and the genome editing efficiency was evaluated using these blastocysts, three (gRNA1, 2, and 4) of the four gRNAs tested successfully edited the CD163 gene. To generate CD163-knockout pigs, a total of 200 electroporated zygotes using these three gRNAs were transferred into the oviducts of oestrous-synchronized surrogate and the surrogate gave birth to eight piglets. Subsequent sequence analysis revealed that one of the piglets carried no wild-type sequence in CD163 gene. The other seven piglets carried only wild-type sequence. Thus, we successfully generated a CD163-edited pig by electroporation of the CRISPR/Cas9 system into in vitro-fertilized zygotes, although further improvement is required to generate genetically modified pigs with high efficiency.

Curcumin supplementation in the maturation medium improves the maturation, fertilisation and developmental competence of porcine oocytes.

This study was conducted to determine the effects of supplementing the maturation medium with the antioxidant curcumin on the in vitro maturation (IVM), fertilisation and development of porcine oocytes. Curcumin supplementation was performed at concentrations of 0, 5, 10, 20, and 40 µM. At concentrations of 5-20 µM, curcumin had significant positive effects (P < 0.05) on maturation and fertilisation rates compared to the non-treated group. Of the groups cultured with 5-20 µM curcumin, the number of oocytes with DNA-fragmented nuclei after IVM was significantly lower than in groups matured without curcumin. Moreover, curcumin supplementation at 10 µM also gave a significantly higher rate of blastocyst formation compared with oocytes matured without curcumin. Increasing the curcumin concentration to 40 µM yielded negative effects on fertilisation and embryonic development compared with the groups treated with lower concentrations of curcumin. Supplementation with 10 µM curcumin had beneficial effects on the oocyte maturation rate and DNA fragmentation index compared to the non-treated group both in the presence and absence of hydrogen peroxide. These results indicate that curcumin supplementation at a suitable concentration (10 µM) is potentially useful for porcine oocyte culture systems, in terms of protecting oocytes from various forms of oxidative stress.

Efficient generation of GGTA1-deficient pigs by electroporation of the CRISPR/Cas9 system into in vitro-fertilized zygotes.

BACKGROUND: Xenoantigens are a major source of concern with regard to the success of interspecific xenografts. GGTA1 encodes α1,3-galactosyltransferase, which is essential for the biosynthesis of galactosyl-alpha 1,3-galactose, the major xenoantigen causing hyperacute rejection. GGTA1-modified pigs, therefore, are promising donors for pig-to-human xenotransplantation. In this study, we developed a method for the introduction of the CRISPR/Cas9 system into in vitro-fertilized porcine zygotes via electroporation to generate GGTA1-modified pigs. RESULTS: We designed five guide RNAs (gRNAs) targeting distinct sites in GGTA1. After the introduction of the Cas9 protein with each gRNA via electroporation, the gene editing efficiency in blastocysts developed from zygotes was evaluated. The gRNA with the highest gene editing efficiency was used to generate GGTA1-edited pigs. Six piglets were delivered from two recipient gilts after the transfer of electroporated zygotes with the Cas9/gRNA complex. Deep sequencing analysis revealed that five out of six piglets carried a biallelic mutation in the targeted region of GGTA1, with no off-target events. Furthermore, staining with isolectin B4 confirmed deficient GGTA1 function in GGTA1 biallelic mutant piglets. CONCLUSIONS: We established GGTA1-modified pigs with high efficiency by introducing a CRISPR/Cas9 system into zygotes via electroporation. Multiple gene modifications, including knock-ins of human genes, in porcine zygotes via electroporation may further improve the application of the technique in pig-to-human xenotransplantation.

Evaluation of multiple gene targeting in porcine embryos by the CRISPR/Cas9 system using electroporation.

The CRISPR/Cas9 system now allows for unprecedented possibilities of genome editing. However, there are some limitations, including achieving efficient one-step multiple genome targeting to save costs, time, and ensure high quality. In the present study, we investigated the efficiency of one-step multiple gene modification by electroporation in porcine zygotes using pooled guide RNAs (gRNAs) targeting CMAH, GHR, GGTA1, and PDX1. We first selected the best-performing gRNA from three different designs for each gene based on the effect on embryo development and mutation efficiency. The three gRNAs showed equivalent effects on the rates of blastocyst formation in each targeted gene; however, gRNAs CMAH #2, GHR #3, GGTA1 #3, and PDX1 #3 showed the highest biallelic mutation rate, although the total mutation rate of PDX1 #3 was significantly lower than that of PDX1 #1. Therefore, CMAH #2, GHR #3, GGTA1 #3, and PDX1 #1 were used as a mixture in electroporation to further clarify whether multiple genes can be targeted simultaneously. Individual sequencing of 43 blastocysts at the target sites of each gene showed mutations in one and two target genes in twenty-four (55.8%) and nine (20.9%) blastocysts, respectively. No mutation was detected in any target gene in ten (23.3%) blastocysts and no blastocysts had a mutation in three or more target genes. These results indicate that electroporation could effectively deliver multiple gRNAs and Cas9 protein into porcine zygotes to target multiple genes in a one-step process. However, the technique requires further development to increase the success rate of multiple gene modification.

The Relationship between Embryonic Development and the Efficiency of Target Mutations in Porcine Endogenous Retroviruses (PERVs) Pol Genes in Porcine Embryos.

Porcine endogenous retrovirus (PERV) is a provirus found in the pig genome that may act as an infectious pathogen in humans who receive pig organ xenotransplantation. Inactivation of the PERV pol gene in porcine cells reportedly affects cell growth. Therefore, the mutation of PERV pol gene in porcine embryos using genome editing may affect the embryonic development. The present study was carried out to investigate the relationship between the mutation of the PERV pol gene in porcine embryos and their development. We introduced, either alone or in combination, three different gRNAs (gRNA1, 2, and 3) into porcine zygotes by genome editing using electroporation of the Cas9 protein (GEEP) system. All three gRNAs targeted the PERV pol gene, and we assessed their effects on porcine embryonic development. Our results showed that the blastocyst formation rates of zygotes electroporated with gRNA3-alone and in combination-were significantly lower (p < 0.05) than those of zygotes electroporated with gRNA1. The mutation rates assessed by the PERV pol gene target site sequencing in individual blastocysts and pooled embryos at the 2-to-8-cell stage did not differ among the three gRNAs. However, the frequency of indel mutations in mutant embryos at the 2-to-8-cell stage trended higher in the embryos electroporated with gRNA3 alone and in combination. Embryonic development may be affected by gRNAs that induce high-frequency indel mutations.

Genome mutation after the introduction of the gene editing by electroporation of Cas9 protein (GEEP) system into bovine putative zygotes.

The present study was designed to investigate the effects of voltage strength on embryonic developmental rate and mutation efficiency in bovine putative zygotes during electroporation with the CRISPR/Cas9 system to target the MSTN gene at different time points after insemination. Results showed that there was no significant interaction between electroporation time and voltage strength on the embryonic cleavage and blastocyst formation rates. However, increasing the voltage strength to 20 V/mm to electroporate the zygotes at 10 h after the start of insemination yielded significantly lower blastocyst formation rates (P < 0.05) than those of the 10-V/mm electroporated zygotes. Mutation efficiency was then assessed in individual blastocysts by DNA sequence analysis of the target sites in the MSTN gene. A positive correlation between mutation rate and voltage strength was observed. The mutation efficiency in mutant blastocysts was significantly higher in the zygotes electroporated with 20 V/mm at 10 h after the start of insemination (P < 0.05) than in the zygotes electroporated at 15 h, irrespective of the voltage strength. We also noted that a certain number of blastocysts from zygotes that were electroporated with more than 15 V/mm at 10 h (4.8-16.7%) and 20 V/mm at 15 h (4.8%) were biallelic mutants. Our results suggest that the voltage strength during electroporation as well as electroporation time certainly have effects on the embryonic developmental rate and mutation efficiency in bovine putative zygotes.

The effects of electroporation on viability and quality of in vivo-derived bovine blastocysts.

The introduction of exogenous molecules into embryos is required for analyses of molecular dynamics and specific gene functions during early embryonic development. Electroporation is an effective method to transport exogenous molecules into cells, but is rarely used in bovine embryos. First, we evaluated the viability of in vivo-derived bovine blastocysts after electroporation with fluorescein (FAM) labeled-oligonucleotides with varying pulse numbers (3, 5, 7, and 10), while keeping the pulse duration at 1 msec and the electric field of 20 V/mm. Next, we examined the effects of zona pellucida status on blastocyst quality after electroporation, by comparing the average diameter of blastocysts before and after electroporation using blastocysts with intact zona pellucida and hatching/hatched blastocysts. Electroporation successfully introduced exogenous molecules into in vivo-derived bovine blastocysts without loss of viability. Moreover, the status of the zona pellucida may be associated with the quality of blastocysts after electroporation.

Relationship among ovarian follicular status, developmental competence of oocytes, and anti-Müllerian hormone levels: A comparative study in Japanese wild boar crossbred gilts and Large White gilts.

The aim of this study was to investigate the ovarian follicular development, developmental competence of oocytes, and plasma anti-Müllerian hormone (AMH) levels of Japanese wild boar crossbred (wild hybrid) gilts, whose litter size is inferior to that of European breeds. Ovary and plasma samples were collected from two different breeds of gilts (wild hybrid and Large White breeds). The ovaries from the wild hybrid gilts had a lower average numbers of secondary follicles and vesicular follicles in ovarian cross-sections and of good quality oocytes collected from ovarian follicles as compared with those from Large White gilts (p < 0.05). The development rate to the blastocyst stage of good quality oocytes after in vitro maturation, fertilization and culture was also lower (p < 0.05) in wild hybrid gilts than in Large White gilts. Plasma AMH levels with >0.16 ng/ml were detected in 8.3% of the examined wild hybrid gilts and 33% of the Large White gilts. These results indicate that the low reproductive performance of wild hybrid breed may result in part from low numbers of vesicular follicles and good quality oocytes, and low developmental competence of oocytes. Moreover, plasma AMH levels may support low number of vesicular follicles in ovaries of wild hybrid gilts.

Genome mutation after introduction of the gene editing by electroporation of Cas9 protein (GEEP) system in matured oocytes and putative zygotes.

The application of CRISPR/Cas9 strategy promises to rapidly increase the production of genetically engineered animals since it yields stably integrated transgenes. In the present study, we investigated the efficiency of target mutations after electroporation with the CRISPR/Cas9 system using sgRNAs to target the MSTN or FGF10 genes in porcine-matured oocytes and putative zygotes. Effects of pulse number (3-7 pulse repetitions) during electroporation on the embryonic development and mutation efficiency were also investigated. Our results showed that the cleavage rate of matured oocytes with electroporation treatment significantly decreased as compared with electroporated putative zygotes (p < 0.05). Moreover, the rates of blastocyst formation from oocytes/zygotes electroporated with more than 5 pulses decreased. Mutation efficiency was then assessed after sequencing the target sites in individual blastocysts derived from oocytes/zygotes electroporated by 3 and 5 pulses. No bi-allelic mutations in all examined blastocysts were observed in this study. There were no differences in the mutation rates (50-60%) between blastocysts derived from matured oocytes electroporated by 3 and 5 pulses, irrespective of targeting gene. In the targeting MSTN gene, however, the mutation rate (12.5%) of blastocysts derived from putative zygotes electroporated by 3 pulses tended to be lower than that (60%) from 5-pulsed electroporated putative zygotes. These data indicate that the type of eggs may influence not only their development after electroporation treatment but also the mutation rate in the resulting blastocysts.

Effects of Tris (hydroxymethyl) aminomethane on the quality of frozen-thawed boar spermatozoa.

Tris (hydroxymethyl) aminomethane (Tris) has been used as a pH regulator for buffering the pH of dilution extenders for boar semen, such as the Modena extender. The purpose of the present study was to assess the effects of Tris supplementation at different concentrations (0, 8, 24 and 72 µM) into the freezing extender on the quality and fertilising capacity of frozen-thawed boar spermatozoa. The results showed that the supplementation of 24 µM of Tris gave significantly higher percentages of sperm viability and plasma membrane integrity than those of the control group at any time point of assessment (0 h and 3 h post-thawing) (P < 0.05). However, there were no significant differences in the acrosome integrity parameter among the groups. Higher percentages of sperm motility were observed in the spermatozoa cryopreserved with 24 µM of Tris compared to the control groups when the samples were analysed 0 h after thawing (P < 0.05). However, an increase of the Tris concentration to 72 µM did not enhance the sperm motility parameters. The total numbers of fertilised oocytes and blastocysts obtained with spermatozoa frozen with 24 µM Tris were significantly higher than those of the control group without Tris (P < 0.05). In conclusion, the supplementation of 24 µM Tris into the freezing extender contributes to a better boar sperm quality and fertilising capacity after the process of freezing and thawing.

Effects of concentration of CRISPR/Cas9 components on genetic mosaicism in cytoplasmic microinjected porcine embryos.

Cytoplasmic microinjection (CI) of the CRISPR/Cas9 system enabled the induction of site-specific mutations in porcine zygotes and resulting pigs. However, mosaicism is a serious problem for genetically modified pigs. In the present study, we investigated suitable timing and concentration of CRISPR/Cas9 components for introduction into oocytes/zygotes by CI, to reduce mosaicism in the resulting blastocysts. First, we introduced 20 ng/µl of Cas9 protein and guide RNA (gRNA), targeting the α-1,3-galactosyltransferase (GalT) gene in oocytes before in vitro fertilization (IVF), in zygotes after IVF, or in oocytes/zygotes before and after IVF, twice. CI treatment had no detrimental effects on blastocyst formation rates. The highest value of the rate of mutant blastocysts was observed in zygotes injected after IVF. Next, we injected Cas9 protein and gRNA into zygotes after IVF at a concentration of 20 ng/µl each (20 ng/µl group) or 100 ng/µl each (100 ng/µl group). The ratio of the number of blastocysts that carried mutations to the total number of blastocysts examined in the 100 ng/µl group was significantly higher (P < 0.05) than that in the 20 ng/µl group. Although no blastocysts from the 20 ng/µl group carried a biallelic mutation, 16.7% of blastocysts from the 100 ng/µl group carried a biallelic mutation. In conclusion, increasing the concentration of Cas9 protein and gRNA is effective in generating biallelic mutant blastocysts. To reduce mosaicism, however, further optimization of the timing of CI, and the concentration of CRISPR/Cas9 components, is needed.

Generation of a TP53-modified porcine cancer model by CRISPR/Cas9-mediated gene modification in porcine zygotes via electroporation.

TP53 (which encodes p53) is one of the most frequently mutated genes in cancers. In this study, we generated TP53-mutant pigs by gene editing via electroporation of the Cas9 protein (GEEP), a process that involves introducing the Cas9 protein and single-guide RNA (sgRNA) targeting exon 3 and intron 4 of TP53 into in vitro-fertilized zygotes. Zygotes modified by the sgRNAs were transferred to recipients, two of which gave birth to a total of 11 piglets. Of those 11 piglets, 9 survived. Molecular genetic analysis confirmed that 6 of 9 live piglets carried mutations in TP53, including 2 piglets with no wild-type (WT) sequences and 4 genetically mosaic piglets with WT sequences. One mosaic piglet had 142 and 151 bp deletions caused by a combination of the two sgRNAs. These piglets were continually monitored for 16 months and three of the genome-edited pigs (50%) exhibited various tumor phenotypes that we presumed were caused by TP53 mutations. Two mutant pigs with no WT sequences developed mandibular osteosarcoma and nephroblastoma. The mosaic pig with a deletion between targeting sites of two sgRNAs exhibited malignant fibrous histiocytoma. Tumor phenotypes of TP53 mosaic mutant pigs have not been previously reported. Our results indicated that the mutations caused by gene editing successfully induced tumor phenotypes in both TP53 mosaic- and bi-allelic mutant pigs.