RESUMEN
Surface subsidence pits formed by mining disturbance are highly susceptible to slope instability under rainfall erosion, inducing underground debris flow disasters. To prevent and control underground debris flow disasters in a subsidence area, a test model of subsidence pit slope was established in accordance with the principle of similar simulation, and the erosion-resistant performance of moraine-cured slopes with different soil-slurry ratios and the law of runoff and sand production were investigated through the simulation of artificial rainfall and a simulation test of grouting. Results show that the initial rainfall production time increases exponentially with increasing soil-slurry ratio, while sediment production intensity decreases linearly with increasing rainfall duration. The evolution of soil erosion can be divided into five stages: impact infiltration, water-filled softening, stripping cutting, migration crossing, and steady flow equilibrium. Compared with in situ moraine, moraine particles after grouting between the generation of large amounts of Si-O-Si and Si-OH hydration products become loose and porous soil medium is transformed into a dense cemented structure. The soil-slurry ratio is 5:1, the sand-fixing effect increases by 28.8 times, the resistance of permeability increases by 11.3 times, and the grouting curing effect is remarkable. This study can provide technical support for the prevention and control of geological disasters in subsidence pits.
RESUMEN
The rat is an important animal model in biomedical research, but practical limitations to genetic manipulation have restricted the application of genetic analysis. Here we report the derivation of rat androgenetic haploid embryonic stem cells (RahESCs) as a tool to facilitate such studies. Our approach is based on removal of the maternal pronucleus from zygotes to generate androgenetic embryos followed by derivation of ESCs. The resulting RahESCs have 21 chromosomes, express pluripotency markers, differentiate into three germ layer cells, and contribute to the germline. Homozygous mutations can be introduced by both large-scale gene trapping and precise gene targeting via homologous recombination or the CRISPR-Cas system. RahESCs can also produce fertile rats after intracytoplasmic injection into oocytes and are therefore able to transmit genetic modifications to offspring. Overall, RahESCs represent a practical tool for functional genetic studies and production of transgenic lines in rat.
Asunto(s)
Células Madre Embrionarias/metabolismo , Pruebas Genéticas , Haploidia , Animales , Secuencia de Bases , Biomarcadores/metabolismo , Sistemas CRISPR-Cas/genética , Diferenciación Celular/genética , Elementos Transponibles de ADN/genética , Embrión de Mamíferos/metabolismo , Células Madre Embrionarias/citología , Regulación de la Expresión Génica , Marcación de Gen , Genoma , Recombinación Homóloga/genética , Homocigoto , Masculino , Ratones , Datos de Secuencia Molecular , Mutación/genética , Células Madre Pluripotentes/citología , Células Madre Pluripotentes/metabolismo , Ratas , Inyecciones de Esperma IntracitoplasmáticasRESUMEN
The rat is an important animal model for human disease research. Using inhibitors of glycogen synthase kinase 3 and MAPK signaling pathways, rat embryonic stem cells and rat induced pluripotent stem cells (riPSCs) have been derived. However, unlike rat embryonic stem cells, germ line competent riPSCs have only been derived from Wistar rats at low efficiency. Here, we found that an optimized induction medium containing knock-out serum replacement and vitamin C improved the rate and efficiency of riPSCs generation from Dark Agouti rat fibroblasts and Sertoli cells. riPSCs maintained an undifferentiated status for >30 passages and could differentiate into various cells types including germ cells when injected into rat blastocysts. Moreover, transgenic riPSCs could be generated through the PiggyBac transposon, which could be used to generate transgenic rats through germ line transmission. riPSCs can be used as a novel tool in genetic and genomic studies of the rat.