Advances and applications of genetically modified pig models in biomedical and agricultural field.

Compared with rodents, pigs are closer to humans in terms of anatomy, metabolism and physiology, so they are ideal animal models of human diseases and xenotransplantation donors. In addition, as one of the most important livestock in China, pigs are closely related to our lives in terms of breeding improvement, disease prevention and animal welfare. In this review, we mainly summarize the research progress and future application of genetically modified pig models in the fields of xenotransplantation, molecular breeding and human disease models. We wish to take this opportunity to raise the awareness of researchers in related fields on cutting-edge technologies such as gene editing and understand the significance of genetically modified pig models in life science research.

Advances in Innate Immunity to Overcome Immune Rejection during Xenotransplantation.

Transplantation is an effective approach for treating end-stage organ failure. There has been a long-standing interest in xenotransplantation as a means of increasing the number of available organs. In the past decade, there has been tremendous progress in xenotransplantation accelerated by the development of rapid gene-editing tools and immunosuppressive therapy. Recently, the heart and kidney from pigs were transplanted into the recipients, which suggests that xenotransplantation has entered a new era. The genetic discrepancy and molecular incompatibility between pigs and primates results in barriers to xenotransplantation. An increasing body of evidence suggests that innate immune responses play an important role in all aspects of the xenogeneic rejection. Simultaneously, the role of important cellular components like macrophages, natural killer (NK) cells, and neutrophils, suggests that the innate immune response in the xenogeneic rejection should not be underestimated. Here, we summarize the current knowledge about the innate immune system in xenotransplantation and highlight the key issues for future investigations. A better understanding of the innate immune responses in xenotransplantation may help to control the xenograft rejection and design optimal combination therapies.

[Effects of Biochar Application on Soil Microbial Nutrient Limitations and Carbon Use Efficiency in Lou Soil].

Soil microbial metabolism is vital for nutrient cycling and stability of an ecosystem. To elucidate the long-term effects of biochar application on nutrient limitations and carbon use efficiency (CUE) of soil microbial metabolisms, biochars pyrolyzed at 450℃ from trunks and branches of fruit trees under an oxygen-limited condition were mixed with the top Lou soils (0-20 cm) with application amounts of 0, 20, 40, 60, and 80 t·hm-2 in 2012. Corn-wheat rotation was carried out afterwards for seven years. The nutrient limitations of soil microbial metabolisms were analyzed quantitatively through ecoenzymatic stoichiometry in 2019. The results indicated that:① With an increase in the biochar application amount, soil moisture, organic carbon, total nitrogen, C:N, C:P, and N:P significantly increased, whereas there were no clear patterns for the active components of carbon, nitrogen, and phosphorus, microbial biomass carbon, nitrogen, phosphorus and total phosphorus. In contrast, the activities of five extracellular enzymes (ß-1,4-glucosidase, cellobiohydrolase, leucine aminopeptidase, ß-1,4-N-acetylglucosaminidase, and phosphatase) were significantly reduced. ② The soil microorganisms suffered from the phosphorus limitation under all treatments in this study. In the treatments of biochar application, the carbon and phosphorus limitations of microbial metabolisms increased significantly with increasing application amount, whereas the microbial CUE decreased significantly. When the application amount was 20 t·hm-2, the carbon limitation (0.625±0.022) and phosphorus limitation (62.153°±0.892°) were lowest, and the microorganism CUE (0.511±0.007) was highest. ③ Partial least-squares path modeling (PLS-PM) showed that soil carbon, nitrogen, phosphorus, and their stoichiometry had a very direct positive effect on phosphorus limitation (P<0.01), and there was a positive correlation between carbon limitation and phosphorus limitation (R2=0.242, P<0.001); in contrast, the carbon and phosphorus limitations had a very significant negative effect on CUE (P<0.001). It was revealed that the excessive application of biochar had caused a soil element stoichiometry imbalance, which deteriorated the phosphorus limitation of the soil microbial metabolism and further led to carbon limitation and reduction of CUE. When the biochar application amount was 20 t·hm-2, C and P limitations were lowest, and microbial CUE was highest. Therefore, 20 t·hm-2 was optimal for regulating soil microbial metabolism, maintaining ecological functions, and reducing carbon dioxide emission produced by microbial metabolism.