In mouse model generation, obtaining positive cell clones that stably integrate and express a transgene is a crucial step. Among selection methods, neomycin resistance (NeoR) and puromycin resistance (PuroR) are the most commonly used. The core principle involves co-transfecting the gene of interest with a resistance gene into host cells (e.g., embryonic stem cells). The cells are then cultured in medium containing the corresponding antibiotic. The sustained antibiotic pressure eliminates cells that have not stably integrated and functionally expressed the resistance gene, ultimately enriching stably transfected positive clones.

Mitochondria, the cellular powerhouses, harbor their own genome (mtDNA). Point mutations in mtDNA are directly linked to hundreds of genetic disorders like Leigh syndrome and Leber's hereditary optic neuropathy (LHON), with point mutations accounting for approximately 95% of pathogenic variants. In the drug discovery pipeline, accurate genetic disease models that can faithfully replicate the human disease mutation threshold (typically >60% heteroplasmy) and multisystem phenotypes are core infrastructure for preclinical research.

April 24, 2026, is the World Day for Laboratory Animals. This commemorative day was established in 1979 by the British Union for the Abolition of Vivisection (BUAV)? and received recognition from the United Nations? in 2009. Its aim is to raise societal awareness regarding the protection of laboratory animals, advocating for the implementation of humanitarian principles in scientific research. The week in which it falls is therefore designated as "Laboratory Animal Week."

Every year on April 17th, we observe World Hemophilia Day, focusing on this rare inherited bleeding disorder, often referred to as the "glass man" disease. In people with hemophilia, the synthesis or function of key clotting factors is impaired, interrupting the coagulation cascade at a critical node in the intrinsic pathway. This prevents the completion of the final "thrombin burst," leading to failure of the physiological hemostatic mechanism. Consequently, even minor trauma can trigger uncontrolled bleeding. Today, let's delve deeper into the pathogenesis of hemophilia and the mouse models used in related research.

In the construction of genetically engineered mouse models, the plasmid is the most critical delivery vector. It is not only the delivery tool for introducing editing machinery into cells but also the key determinant of editing efficiency and stability. This article, starting from the practical needs of mouse model construction, systematically deconstructs the design logic and essential elements of plasmids.