Biology subjects

Zhao, J.-P.

Publications and source records attributed to Zhao, J.-P..

3 recordsLinked to original sources

bioRxiv2024

In Vivo Optical Clearing of Mammalian Brain

Established methods for imaging the living mammalian brain have, to date, taken the brains optical properties as fixed; we here demonstrate that it is possible to modify the optical properties of the brain itself to significantly enhance at-depth imaging while preserving native physiology. Using a small amount of any of several biocompatible materials to raise the refractive index of solutions superfusing the brain prior to imaging, we could increase several-fold the signals from the deepest cells normally visible and, under both one-photon and two-photon imaging, visualize cells previously too dim to see. The enhancement was observed for both anatomical and functional fluorescent reporters across a broad range of emission wavelengths. Importantly, visual tuning properties of cortical neurons in awake mice, and electrophysiological properties of neurons assessed ex vivo, were not altered by this procedure.

bioengineering↗

bioRxiv2023

Removal of a genomic duplication by double-nicking CRISPR restores synaptic transmission and behavior in the MyosinVA mutant mouse Flailer.

Copy number variations, and particularly duplications of genomic regions, have been strongly associated with various neurodegenerative conditions including autism spectrum disorder (ASD). These genetic variations have been found to have a significant impact on brain development and function, which can lead to the emergence of neurological and behavioral symptoms. Developing strategies to target these genomic duplications has been challenging, as the presence of endogenous copies of the duplicate genes often complicates the editing strategies. Using the ASD and anxiety mouse model Flailer, that contains a duplication working as a dominant negative for MyoVa, we demonstrate the use of DN-CRISPRs to remove a 700bp genomic duplication in vitro and in vivo. Importantly, DN-CRISPRs have not been used to remove more gene regions <100bp successfully and with high efficiency. We found that editing the flailer gene in primary cortical neurons reverts synaptic transport and transmission defects. Moreover, long-term depression (LTD), disrupted in Flailer animals, is recovered after gene edition. Delivery of DN-CRISPRs in vivo shows that local delivery to the ventral hippocampus can rescues some of the mutant behaviors, while intracerebroventricular delivery, completely recovers Flailer animal phenotype associated to anxiety and ASD. Our results demonstrate the potential of DN-CRISPR to efficiently (>60% editing in vivo) remove large genomic duplications, working as a new gene therapy approach for treating neurodegenerative diseases.

neuroscience↗

bioRxiv2018

Desiccation Does Not Drastically Increase the Accessibility of Foreign DNA to the Nuclear Genomes: Evidence from the Frequency of Endosymbiotic DNA Transfer

Horizontal gene transfer (HGT) is a widely accepted force in the evolution of prokaryotic genomes. However, in eukaryotes, it is still in hot debate. Some bdelloid rotifers that are resistant to extreme desiccation and radiation were reported to have a very high level of HGTs. However, a similar report in another resistant invertebrate, tardigrades, has been mired in controversy. The DNA double-strand breaks (DSBs) induced by prolonged desiccation have been postulated to open the gateway of nuclear genome for foreign DNA integration and thus facilitate the HGT process. If so, the rate of endosymbiotic DNA transfer should also be enhanced. We first surveyed the abundance of nuclear mitochondrial DNAs (NUMTs) and nuclear plastid DNAs (NUPTs) in three groups of eukaryotes that are extremely resistant to desiccation, bdelloid rotifers, A. vaga and A. ricciae, tardigrades, H. dujardini and R. varieornatus, and the resurrection plants, D. hygrometricum and S. tamariscina. Excessive NUMTs or NUPTs have not been detected. Furthermore, we compared nine groups of desiccation-tolerant organisms with their desiccation-sensitive relatives but did not find significant difference in the NUMT/NUPT contents. Desiccation could induce DSBs, but it unlikely dramatically increase the frequency of foreign sequence integration in most eukaryotes. Only in the nuclear genomes enriched in repetitive sequences, the DSBs are predominantly repaired by non-homologous end joining (NHEJ) and desiccation-induced DSBs is possible to enhance the integration of foreign sequences into nuclear genome for some degree.

evolutionary biology↗