Decontamination of genetically modified mice strains by embryo transfer for obtaining SPF colonies in a Brazilian animal facility / Descontaminação de linhagens de camundongos geneticamente modificadas por transferência embrionária para obtenção de colônias SPF em um biotério brasileiro (São Paulo, SP)

The introduction of new strains of mice in specific pathogen-free (SPF) animal facilities should be performed carefully to avoid breaking sanitary barriers. To meet this need, animals should be rederived to reduce infection risk and thus avoid research interference caused by loss of animal health status and welfare. The objective of this study was to implement mice embryo transfer in the laboratory mouse facility of the Department of Immunology at the Institute of Biomedical Sciences/University of São Paulo, Brazil. Embryo transfers were performed to rederive genetically modified mouse strains with undefined sanitary status, received from different research and educational institutions. Fertilized eggs at two-cell stage were obtained by natural means and transferred into the oviducts of SPF pseudo-pregnant female mice. All surgical procedures were performed under aseptic conditions. A total of 625 embryos were transferred into the recipients. 148 pups were born, of which 140 were reared. Viruses, bacteria and intestinal protozoa were eliminated using this technique. The improvement in the microbiological status of mice allowed their expansion in our SPF facility. With these results, we can stimulate the use of embryo transfer technique between rodent facilities in Brazil and thus encourage the distribution of better models to our scientific community.(AU)

A introdução de novas linhagens de camundongos em biotérios livres de patógenos específicos (SPF) deve ser realizada com critérios para evitar a quebra das barreiras sanitárias. Dessa forma, os animais devem ser rederivados para reduzir os riscos de infecção e evitar as interferências provocadas pela perda do status sanitário e do bem-estar dos animais. O objetivo deste estudo foi implementar a transferência de embriões murinos no Biotério do Departamento de Imunologia do Instituto de Ciências Biomédicas da Universidade de São Paulo, Brasil. As transferências embrionárias foram realizadas para rederivar linhagens de camundongos geneticamente modificadas com status sanitário não conhecido, recebidas de diferentes instituições de pesquisa e de ensino. Os embriões em duas células foram obtidos pelos métodos naturais e transferidos para os ovidutos de fêmeas de camundongos SPF pseudoprenhas. Todos os procedimentos cirúrgicos foram realizados sob condições assépticas. Um total de 625 embriões foram transferidos para as receptoras. Foram obtidos 148 filhotes nascidos vivos, destes 140 foram desmamados. Por meio desta técnica, foram eliminados vírus, bactérias e protozoários intestinais. A melhora no status microbiológico dos camundongos permitiu a expansão destes em nossa colônia SPF. Com esses resultados, podemos promover o uso da técnica de transferência de embriões entre os biotérios brasileiros e assim incentivar a distribuição de modelos mais adequados para a nossa comunidade científica.(AU)

The crystal structure of Ac-AChBP in complex with α-conotoxin LvIA reveals the mechanism of its selectivity towards different nAChR subtypes

The α3* nAChRs, which are considered to be promising drug targets for problems such as pain, addiction, cardiovascular function, cognitive disorders etc., are found throughout the central and peripheral nervous system. The α-conotoxin (α-CTx) LvIA has been identified as the most selective inhibitor of α3β2 nAChRs known to date, and it can distinguish the α3β2 nAChR subtype from the α6/α3β2β3 and α3β4 nAChR subtypes. However, the mechanism of its selectivity towards α3β2, α6/α3β2β3, and α3β4 nAChRs remains elusive. Here we report the co-crystal structure of LvIA in complex with Aplysia californica acetylcholine binding protein (Ac-AChBP) at a resolution of 3.4 Å. Based on the structure of this complex, together with homology modeling based on other nAChR subtypes and binding affinity assays, we conclude that Asp-11 of LvIA plays an important role in the selectivity of LvIA towards α3β2 and α3/α6β2β3 nAChRs by making a salt bridge with Lys-155 of the rat α3 subunit. Asn-9 lies within a hydrophobic pocket that is formed by Met-36, Thr-59, and Phe-119 of the rat β2 subunit in the α3β2 nAChR model, revealing the reason for its more potent selectivity towards the α3β2 nAChR subtype. These results provide molecular insights that can be used to design ligands that selectively target α3β2 nAChRs, with significant implications for the design of new therapeutic α-CTxs.

Effective gene editing by high-fidelity base editor 2 in mouse zygotes

Targeted point mutagenesis through homologous recombination has been widely used in genetic studies and holds considerable promise for repairing disease-causing mutations in patients. However, problems such as mosaicism and low mutagenesis efficiency continue to pose challenges to clinical application of such approaches. Recently, a base editor (BE) system built on cytidine (C) deaminase and CRISPR/Cas9 technology was developed as an alternative method for targeted point mutagenesis in plant, yeast, and human cells. Base editors convert C in the deamination window to thymidine (T) efficiently, however, it remains unclear whether targeted base editing in mouse embryos is feasible. In this report, we generated a modified high-fidelity version of base editor 2 (HF2-BE2), and investigated its base editing efficacy in mouse embryos. We found that HF2-BE2 could convert C to T efficiently, with up to 100% biallelic mutation efficiency in mouse embryos. Unlike BE3, HF2-BE2 could convert C to T on both the target and non-target strand, expanding the editing scope of base editors. Surprisingly, we found HF2-BE2 could also deaminate C that was proximal to the gRNA-binding region. Taken together, our work demonstrates the feasibility of generating point mutations in mouse by base editing, and underscores the need to carefully optimize base editing systems in order to eliminate proximal-site deamination.

Mesenchymal stem cells reduce the irradiation induced lung injury / 中华放射医学与防护杂志

Objective To evaluate the role of mesenchymal stem cells (MSCs) derived from mouse bone and embryo dorsal aorta(DA) area in the treatment of irradiation induced lung injury of mouse model. Methods The mice were divided into four groups as normal control group, irradiation group,bone MSCs treatment group and DA MSCs treatment group. Immunohistochemical Analysis of lung tissue was observed after 9 months of treatment. Results Fibrosis and alveolar infiltration were scored in each group. The score for fibrosis and alveolar is 0. 17 in normal control group, 2 in irradiation group, 1 in bone MSCs treat group and 1.38 in DA MSCs treat group. Conclusion The extent of irradiation Induced Lung Injury could be reduced thorough the treatment of MSCs derived from mouse bone and embryos dorsal aorta ( DA ) area.

Immunohistochemical identification and quantitative analysis of cytoplasmic Cu/Zn superoxide dismutase in mouse organogenesis

Cytoplasmic Cu/Zn superoxide dismutase (SOD1) is an antioxidant enzyme that converts superoxide to hydrogen peroxide in cells. Its spatial distribution matches that of superoxide production, allowing it to protect cells from oxidative stress. SOD1 deficiencies result in embryonic lethality and a wide range of pathologies in mice, but little is known about normal SOD1 protein expression in developing embryos. In this study, the expression pattern of SOD1 was investigated in post-implantation mouse embryos and extraembryonic tissues, including placenta, using Western blotting and immunohistochemical analyses. SOD1 was detected in embryos and extraembryonic tissues from embryonic day (ED) 8.5 to 18.5. The signal in embryos was observed at the lowest level on ED 9.5-11.5, and the highest level on ED 17.5-18.5, while levels remained constant in the surrounding extraembryonic tissues during all developmental stages examined. Immunohistochemical analysis of SOD1 expression on ED 13.5-18.5 revealed its ubiquitous distribution throughout developing organs. In particular, high levels of SOD1 expression were observed in the ependymal epithelium of the choroid plexus, ganglia, sensory cells of the olfactory and vestibulocochlear epithelia, blood cells and vessels, hepatocytes and hematopoietic cells of the liver, lymph nodes, osteogenic tissues, and skin. Thus, SOD1 is highly expressed at late stages of embryonic development in a cell- and tissue-specific manner, and can function as an important antioxidant enzyme during organogenesis in mouse embryos.

The Influences of Different Composition of Glucose and Pyruvate on In Vitro Development of Mouse Preimplantation Embryos in Medium with Glutamine / 대한산부인과학회잡지

OBJECTIVE: The purpose of this study was to examine the effects on in vitro development of early preimplantation mouse embryos in DMEM medium with glutamine which was controlled by different composition of glucose and pyruvate. METHODS: Four hundred and nineteen mouse 2-cell embryos were cultured in four different media with different composition of glucose and pyruvate for 96 hours. The DMEM-G contained L-glutamine for energy sources was used for control group. Group I embryos were cultured in the medium that mixed one volume of DMEM-GGP contained L-glutamine, D-glucose and sodium pyruvate for energy sources with three volume of DMEM-G, and group II embryos were cultured in the medium that mixed with same volume of DMEM-G and DMEM-GGP, and group III embryos were cultured in DMEM-GGP. RESULTS: At 24 hours, the development into >or=3-cell was significantly higher (por=8-cell was significantly higher in group I (73.1%) than control (44.2%), group II (59.6%) and III (45.8%), and also group II was significantly higher than control and group III. At 48 hours, the development into >or=morula was significantly higher in group I (90.4%) and II (86.5%) than control (73.0%). However, the development into blastocyst, in group III (15.0%) was significantly lower than control, group I and II. At 72 hours, the development into >or=expanded blastocyst was significantly higher in group I (69.2%) than group III (47.7%), and total blastocyst was significantly higher in group I (80.8%) than control (66.3%) and group III (67.3%). At 96 hours, the development into >or=hatching blastocyst was significantly higher in group I (78.8%) than control (61.5%) and group III (57.9%), and also, total blastocyst was significantly higher in group I (85.6%) than control (69.2%) and group III (72.0%). CONCLUSION: The development of early preimplantation mouse embryos cultured in group I medium that mixed one volume of DMEM-GGP with three volume of DMEM-G was better than other groups during the culture period.

Effect of Ethylene Glycol (EG) and 1,2-Propanediol (PROH) on the Survival and the Development of Mouse and Human Embryosafter Slow Freezing/Rapid Thawing Protocol / 대한불임학회지

OBJECTIVE: The aim of this study were to compare the effects of EG and PROH on cryopreservation of mouse and human embryos, and to find the optimal protocol for embryo freezing. METHODS: Human embryos derived from fertilized eggs showing 3 pronuclei (PN) and mouse embryos were divided into two groups respectively: dehydrated with 1.5 M EG+0.2 M sucrose or 1.5 M PROH+0.2 M sucrose using the slow freezing method. Moreover mouse embryos were controlled the exposure time of cryoprotectant during dehydration or rehydration steps. RESULTS: The survival rates of human embryos were 79.2% (84/106) in EG group and 77.9% (88/113) in PROH group. In mouse embryos, the survival and development rates up to blastocyst were 70.6% (245/347), 44.1% (123/279) in EG group and 62.1% (198/319), 45.1% (123/279) in PROH group, respectively. However, in EG group, partially damaged embryos after thawing were decreased compared to PROH group. In combination group, when the exposure time during dehydration and rehydration were reduced, the survival and embryonic developments were increased slightly, but not significant. CONCLUSION: Cryopreservation of mouse and human embryos at cleavage stage by using EG or PROH exhibited no statistical difference in the survival rate and/or developmental rate to blastocyst. However, the use of EG for cryopreservation of embryos might reduce the exposure time of the cryoprotectant because of a high permeation of EG and result in lessen its toxic effects.

Granulocyte Macrophage-Colony Stimulating Factor Signaling in Development of Mouse Embryos / 대한불임학회지

OBJECTIVE Present study was aimed to verify the effect of granulocyte macrophage-colony stimulating factor (GM-CSF) in the preimplantation development of mouse embryos and the involvement of the mitogen activated protein kiase (MAPK) in the GM-CSF signaling. METHODS: Two-cell embryos were cultured for 96 h in the presence or absence of GM-CSF (0, 0.4, 2, 10 ng/ml) and PD98059, a MEK inhibitor (10 muM). Morphological development, cell number per blastocyst, and apoptotic nuclei, were eamined. MAPK activity of embryonic immunoprecipitate by MAPK (ERK1/2) antibody was measured by in vitro phosphorylation of myelin basic protein. RESULTS: At post hCG 122 h the embryonic development among the experimental groups was significantly different (p=0.018). The rate of blastocyst development and cell number per embryo were the highest in 2 ng/ml GM-CSF treatment group. The percent of apoptotic cells of the GM-CSF-treated embryos was the lowest among the group. in blastocysts, GM-CSF treatment transiently increased MAPK activity. PD098059 attenuated the effect of GM-CSF on the morphological development, increase in cell number per blastocyst, down regulation of apoptosis, and upregulation of MAPK activity, suggesting that activation of MAPK cascade possibly mediated the embryotropic effect of GM-CSF. CONCLUSION: This result suggested that GM-CSF potentiated the development of preimplantation mouse embryos by activation of MAPK.

Viability of Frozen-Thawed Embryos According to Developmental Stage in Mouse Embryo Cryopreservation / 대한산부인과학회잡지

OBJECT: To compare the viability after thawing of cryopreserved embryos according to developmental stage and decide the cryopreservation strategy METHODS: Total 538 mouse embryos(One, 2, 4, 8-cell, blastocyst, each 151, 136, 101, 98, 52, respectively) were cryopreserved and thawed using 1,2-propanediol and glycerol as cryoprotectant with slow cooling and rapid thawing technique, and compared the recovery, cleavage, blastocyst development rate, and calculated the recovery and reexpansion rate in blastocyst cryopreservation. RESULTS: Highest recovery, cleavage and blastocyst development rate were obtained from one cell, 8-cell stage freezing, 90.1%, 89.5% and 76.7%, respectively. In recovery rate, there was no significant difference among developmental stage, but in cleavage rate, there was significant difference between 2 and 8-cell group(p<0.05). In blastocyst development rate, there was significant difference between 2 and 8 cell, 4 and 8-cell group(p<0.05). Recovery and reexpansion rate of frozen-thawed blastocyst was 73.1%, 52.6%, respectively. CONCLUSIONS: Eight-cell embryo may be the best developmental stage for cryopreservation and blastocyst freezing also may be the promising technique.

Effect of Magnesium Ion in the Culture Medium on the Development of Preimplantation Mouse Embryos In Vitro / 대한불임학회지

OBJECTIVE: The present study was undertaken to examine the effects of magnesium ion in the culture medium on the development of mouse fertilized oocytes either before or after pronuclear formation, and to investigate whether the effect of magnesium ion is related with the redistributional change of mitochondria. METHODS: Fertilized oocytes obtained from the oviducts of mice at 15 hr after hCG injection before pronuclear formation (pre-PN) or 21 hr after hCG injection after pronuclear formation (post-PN) were used. The embryos were cultured for 3 days with basic T6 medium-magnesium free and various concentrations of magnesium ion, 0.0, 0.5, 1.0, 2.0, 4.0 or 8.0 mM, respectively. After culture, the developmental stages of embryos and the number of nuclei were evaluated. To observe the effects of magnesium ion on the mitochondrial distribution, fertilized oocytes were collected at 21 hr after hCG injection and cultured for 6 hr with various concentration of magnesium ion. As a control, fertilized oocytes with pronuclei at 27 hr after hCG injection were used. RESULTS: The concentration of magnesium ion to accelerate the in vitro development of mouse fertilized oocytes appeared to be at 2.0 mM for the pre-PN and the post-PN stage embryos. In the mitochondrial redistribution patterns, the embryos cultured in 2.0 mM concentration of magnesium ion showed the highest percentage (22.6%) of distinct perinuclear clustering pattern comparing to other experimental group. CONCLUSION: The effect of magnesium ion may be related to the cytoplasmic redistribution of mitochondria. This relationship seems to connect the developmental competence of preimplantation mouse embryos in vitro. These results can suggest that higher concentration of magnesium ion (2.0 mM) than those of conventional culture medium (0.2~1.2 mM) is more suitable for in vitro culture of preimplantation mouse embryos.

The Effect of Coculture on In Vitro Fertilization of Oocytes and Development of Early Stage Embryos in Mice / 대한산부인과학회잡지

OBJECTIVES: Our objective was to investigate the effect of coculture system on in vitro fertilization and development of mice embryos. METHODS: F1 hybrid mice were superovulated with PMSG/hCG. Recruited oocytes were divided into three subgroups which are control(subgroup a), Vero cell coculture(subgroup b) and human amniocyte coculture subgroup (subgroup c) respectively. For 3 subgroups, we observed fertilization after 24 hours of incubation. In vitro fertilized early 2-cell stage embryos were allocated to Group I and in vivo fertilized early 2-cell stage embryos were allocated to Group II. Also, each group was divided into control (subgroup a), Vero cell coculture(subgroup b) and human amniocyte coculture subgroup(subgroup c) respectively. For 6 subgroups, we observed in vitro development to blastocyst and that to hatching blastocyst after 120 hours of incubation. RESULTS: As to recruited oocytes, the in vitro fatilization rate of subgroup a was significantly higher than that of subgroup b and subgroup c (P<0.05). In Group I, the developmental rates were not significantly different between the three subgroups. But in Group II, the developmental rates to hatching blastocysts of subgroup b and c were significantly higher than that of subgroup a (p<0.05). CONCLUSION: The development of the in vitro fertilized mouse embryos seemed to be independent of physiologic condition which we think coculture system may give to the embryos. The independent developmental capability of the in vitro fertilized embryos might be obtained through a certain intracellular mechanism for which there should be the need of many more investigations to be verified.