Possible Production of Genome-Edited Animals Using Gene-Engineered Sperm

CRISPR/Cas9 is widely used for genome editing in a variety of organisms, including mammals, fishes, and plants. In mammals, zygotes are considered an appropriate target for gene delivery of CRISPR/Cas9 components [Cas9 endonuclease and a single-guide (sgRNA)] via microinjection or in vitro electroporation. However, these approaches require ex vivo handling of zygotes, which is necessary for egg transfer to recipient females to allow the treated zygotes to develop full-term. These procedures are often laborious, time-consuming, and use numerous mice. In our previous experiments, the plasmid DNA encapsulated by liposomal reagent introduced into the internal portion of a testis can be transferred to the mature sperm present in the epididymal ducts, and is finally transferred to oocytes via fertilization. Although it was not integrated into their genome, this approach would be useful for creating genome-edited animals, since CRISPR/Cas9 can be performed by transient interaction of Cas9 and sgRNA, whereby chromosomal integration of the CRISPR components is not a prerequisite. Here, we will review past achievements concerning in vivo transfection of immature/mature sperm and present experimental proposals for possible genome editing via gene-engineered sperm based on recent findings

Allowed slepton intergenerational mixing in light of light element abundances

We studied allowed region on the intergenerational mixing parameters of sleptons from a viewpoint of big-bang nucleosynthesis in a slepton-neutralino coannihilation scenario. In this scenario, $^7$Li and $^6$Li problems can be solved by considering exotic reactions caused by bound-state effects with a long-lived slepton. Light element abundances are calculated as functions of the relic density and lifetime of the slepton which considerably depend on the intergenerational mixing parameters. Compared with observational light element abundances, we obtain allowed regions on the intergenerational mixing. Ratio of selectron component to stau component, $c_e$, is allowed in $2\times 10^{-11} \lesssim c_e \lesssim 2\times 10^{-9}$ with solving both the $^7$Li and $^6$Li problems. Similarly, the ratio for smuon, $c_{\mu}$, is allowed in $10^{-7} \lesssim c_{\mu} \lesssim 5\times 10^{-5}$ for mass difference between slepton and neutralino, which is smaller than muon mass, and $$ for the mass difference in range between muon mass and 125 MeV. We also discuss collider signatures of the slepton decays. We find characteristic double peaks in momentum distribution of event number of the slepton decays with allowed mixing parameters. Discoveries of the double peaks at future collider experiments should confirm our scenario.Comment: 10 pages, 6 figure

Anisotropic magnetic responses of topological crystalline superconductors

Majorana Kramers pairs emerged on surfaces of time-reversal-invariant topological crystalline superconductors show the Ising anisotropy to an applied magnetic field. We clarify that crystalline symmetry uniquely determines the direction of the Majorana Ising spin for given irreducible representations of pair potential, deriving constraints to topological invariants. Besides, necessary conditions for nontrivial topological invariants protected by the n-fold rotational symmetry are shown.Comment: Special Issue Topological Crystalline Insulators: Current Progress and Prospect