Producing transgenic chickens with chicken blastodermal cells (cBCs) is inefficient due to the extremely low germline transmission capacity of cBCs. As chicken primordial germ cells (PGCs) have been reported as an efficient method for producing transgenic chickens, the inefficiency of cBCs could potentially be resolved by inducing them to differentiate into germ cells. However, whether chemical inducers are able to enhance cBCs germline competence in vitro is unknown and the molecular mechanisms of differentiation of chicken pluripotent cells into germ cells are poorly understood. We cultured cBCs with a monolayer morphology in E8 medium, a xeno- and feeder-free medium. We showed that retinoic acid (RA) treatment increased expression of germ cell-specific genes in cBCs. Using western blot, we determined that RA stimulated Smad1/5 phosphorylation. Moreover, Smad1/5 activation regulates the expression of germ cell-specific genes, as co-treatment with a Smad1/5 phosphorylation inhibitor or activator alters expression of these genes. We also demonstrate that Smad1/5 is required for RA-induced differentiation by RNA interference knockdown. Our results demonstrated that E8 medium is able to maintain cBC growth for weeks and RA treatment induced germ cell differentiation of cBCs through the BMP-Smad1/5 signaling pathway.

Increasingly complex epidemics of animal infectious diseases have emerged as a major risk to livestock production and human health. However, current detection methods for animal infectious diseases suffer from shortcomings such as insufficient sensitivity, complicated operation, and reliance on skilled personnel, highlighting the urgent need for novel sensing platforms. CRISPR/Cas systems are adaptive immune systems found in many prokaryotes. Owing to their ability to precisely and reliably target and cleave nucleic acids, the CRISPR/Cas-based nucleic acid detection technology is considered a promising new detection method. When leveraged with a pre-amplification step and established readout methods, CRISPR/Cas-based sensing platforms can achieve a high sensitivity of single-base resolution or attomolar levels on-site. In this review, we first outline the history, working principles, and nucleic acid detection platforms derived from various CRISPR/Cas systems. Next, we evaluate the advantages and limitations of different nucleic acid pre-amplification methods integrated with CRISPR/Cas systems, followed by a discussion of readout methods employed in CRISPR/Cas-based sensing platforms. Additionally, we highlight recent applications of CRISPR/Cas-based sensing platforms in identifying animal infectious diseases. Finally, we address the challenges and prospects of CRISPR/Cas-based sensing platforms for the early and accurate diagnosis of animal infectious diseases.