Improvement in Tol2 transposon for efficient large-cargo capacity transgene applications in cultured cells and zebrafish(Danio rerio)

Most viruses and transposons serve as effective carriers for the introduction of foreign DNA up to 11 kb into vertebrate genomes.However,their activity markedly diminishes with payloads exceeding 11 kb.Expanding the payload capacity of transposons could facilitate more sophisticated cargo designs,improving the regulation of expression and minimizing mutagenic risks associated with molecular therapeutics,metabolic engineering,and transgenic animal production.In this study,we improved the Tol2 transposon by increasing protein expression levels using a translational enhancer(QBI SP163,ST)and enhanced the nuclear targeting ability using the nuclear localization protein H2B(SHT).The modified Tol2 and ST transposon efficiently integrated large DNA cargos into human cell cultures(H1299),comparable to the well-established super PiggyBac system.Furthermore,mRNA from ST and SHT showed a significant increase in transgene delivery efficiency of large DNA payloads(8 kb,14 kb,and 24 kb)into zebrafish(Danio rerio).This study presents a modified Tol2 transposon as an enhanced nonviral vector for the delivery of large DNA payloads in transgenic applications.

Advancing neuroscience through real-time processing of big data:Transition from open-loop to closed-loop paradigms

The brain functions as a closed-loop system that continuously generates behavior in response to the external environment and adjusts actions based on the outcomes.Traditional research methodologies in neuroscience,especially those employed in brain imaging experiments,have mainly adopted an open-loop paradigm(Grosenick et al.,2015).Functional neural circuits are analyzed offline and subsequently tested through manipulation of neuronal activities within specific regions or with genetic markers.By establishing a closed-loop research paradigm,functional ensembles can be detected and tested in real time with temporal sequences.These functional ensembles,rather than brain regions or genetically labeled neural populations,serve as fundamental units of neural networks,offering valuable insights into the dissection of neural circuits.The closed-loop research paradigm also enables the capture of high-dimensional activities of internal brain dynamics and precise elucidation of physiological processes such as learning,decision-making,and sleep.

One-step generation of zebrafish carrying a conditional knockoutknockin visible switch via CRISPR/Cas9-mediated intron targeting

The zebrafish has become a popular vertebrate animal model in biomedical research.However,it is still challenging to make conditional gene knockout(CKO)models in zebrafish due to the low efficiency of homologous recombination(HR).Here we report an efficient non-HR-based method for generating zebrafish carrying a CKO and knockin(KI)switch(zCKOIS)coupled with dual-color fluorescent reporters.Using this strategy,we generated hey2^zCKOIS which served as a hey2 KI reporter with EGFP expression.Upon Cre induction in targeted cells,the hey2^zCKOIS was switched to a non-functional CKO allele hey2^zCKOIS-inv associated with Tag RFP expression,enabling visualization of the CKO alleles.Thus,simplification of the design,and the visibility and combination of both CKO and KI alleles make our z CKOIS strategy an applicable CKO approach for zebrafish.