Pig cloning by somatic cell nuclear transfer (SCNT) frequently undergoes incomplete epigenetic remodeling during the maternal-to-zygotic transition, which leads to a significant embryonic loss before implantation. Here, we generated the first genome-wide landscapes of histone methylation in pig SCNT embryos. Excessive H3K9me3 and H3K27me3, but not H3K4me3, were observed in the genomic regions with unfaithful embryonic genome activation and donor-cell-specific gene silencing. A combination of H3K9 demethylase KDM4A and GSK126, an inhibitor of H3K27me3 writer, were able to remove these epigenetic barriers and restore the global transcriptome in SCNT embryos. More importantly, thymine DNA glycosylase (TDG) was defined as a pig-specific epigenetic regulator for nuclear reprogramming, which was not reactivated by H3K9me3 and H3K27me3 removal. Both combined treatment and transient TDG overexpression promoted DNA demethylation and enhanced the blastocyst-forming rates of SCNT embryos, thus offering valuable methods to increase the cloning efficiency of genome-edited pigs for agricultural and biomedical purposes.

Because of the special geological conditions on the Loess Plateau, Landslide erosion is not only the main goal of prevention and control of geological disasters, but also an important erosion mode of soil and water loss in the basin. Thus, landslide susceptibility assessment before only considering landslide frequency is not far enough for a decision-maker. The study aims to consider both frequency and scale of landslides for a better landslide susceptibility evaluation. Taking the Yangou small watershed as an example, this study used a VR model, RIRA method, and the GIS method to comprehensively consider frequency and scale to analyze landslide susceptibility of the small watershed. Based on the detailed analysis of the existing literature, slope, elevation, NDVI, land-use, lithology, amount distant to road, amount distant to river, profile curvature, and rainfall as landslide are selected as the conditioning factors (CFs) of the landslide, to draw the sensitivity map. The map of landslide susceptibility was classified into five zones: very low, low, medium, high, and very high, and the cover areas occupy 6.90, 12.81, 12.83, 9.42, and 5.87 km², respectively. A total of 60% of the landslide occurred in the zones of high and very high susceptibility, accounting for 87% of the total volume in the study area. The very high susceptibility is the area with a larger relief and along the river and road. The findings will help decision makers to formulate scientific comprehensive policies that take into account disaster prevention and soil conservation measures in specific regions.

Loess collapse-type lateral pressure may have a landslide-promoting effect in loess slope areas. A study on the variability of loess collapse-type lateral pressure in the Heifangtai area and its sliding mechanism has been analysed. Collapse tests and numerical simulations were conducted according to local safety field theory. The results indicate that the Heifangtai loess is self-weighted collapsible loess. As the depth or moisture content increases, the lateral pressure gradually increases, and correspondingly the deformation becomes greater. In a saturated state, the maximum lateral pressure reaches 123 kPa, and the lateral pressure coefficient increases up to 1.4 times. As the water content increases from 4% to 20%, the total slope displacement is predominantly horizontal, increasing from 12 to 140 mm, the lateral pressure coefficient gradually increases and the increase range gradually expands; the failure area becomes gradually wider until the slope toe is penetrated. Collapse action leads to tensile stresses in the upper part of the slope, making it prone to collapse-type crack formation, resulting in dominant channels of surface water infiltration and forming landslide scarps. Furthermore, collapse action also enables the formation of compressive stresses in the lower part of the slope, resulting in outward extrusion of deep soil, increased sliding force and landslide formation.