Scaling Laws Behind Penetrative Turbulence:History and Perspectives

An unstably stratified flow entering into a stably stratified flow is referred to as penetrative convection,which is crucial to many physical processes and has been thought of as a key factor for extreme weather conditions.Past theoretical,numerical,and experimental studies on penetrative convection are reviewed,along with field studies providing insights into turbulence modeling.The physical factors that initiate penetrative convection,including internal heat sources,nonlinear constitutive relationships,centrifugal forces and other complicated factors are summarized.Cutting-edge methods for understanding transport mechanisms and statistical properties of penetrative turbulence are also documented,e.g.,the variational approach and quasilinear approach,which derive scaling laws embedded in penetrative turbulence.Exploring these scaling laws in penetrative convection can improve our understanding of large-scale geophysical and astrophysical motions.To better the model of penetrative turbulence towards a practical situation,new directions,e.g.,penetrative convection in spheres,and radiation-forced convection,are proposed.

植物质体基因工程调控元件研究进展

随着植物合成生物学的发展,质体逐渐成为许多具有商业价值的次生代谢产物和治疗性蛋白异源生产的理想平台。与核基因工程相比,质体基因工程在外源基因高效表达和生物安全性等方面具有其独特优势。然而,外源基因在质体系统中的组成型表达或对植物生长不利,因此需进一步挖掘、设计调控元件实现对外源基因的精准调控。本文概述了质体基因工程调控元件的研究进展,内容包括操纵子设计与优化思路、多基因共表达调控策略及新型表达调控元件的挖掘等,为植物合成生物学的发展提供参考。

Dendrobium species regulate energy homeostasis in neurodegenerative diseases: a review

Brain energy homeostasis is a vital physiological function in maintaining a balanced internal metabolic environment.The impairment of energy homeostasis is recognized as a key pathophysiological basis for brain metabolic disorders and related neurodegenerative diseases.Dendrobium species(‘Shihu’in Chinese)such as D.officinale,D.huoshanense,D.nobile,D.chrysanthum,D.loddigesii,D.moniliforme,D.gratiosissimum,D.candidum and D.caulis are widely used as traditional Chinese medicines/nutraceuticals to control and treat neurodegenerative disorders.These dietary herbs and their derived compounds possess a variety of biological properties,such as suppression of oxidative stress and neuroinflammation,regulation of energy homeostasis mainly through improving brain mitochondria function,insulin signaling and lipid metabolism.Furthermore,they reduce neurotoxicity,alleviate brain injury and neuropathy,and prevent neurodegenerative conditions including stroke,Alzheimer’s disease,Parkinson’s disease,and Huntington’s disease in humans and/or rodents.Moreover,the nutraceuticals from Dendrobium species promote gut health and aid digestion,which appear to be associated with beneficial effects on brain energy homeostasis.Based on the above-mentioned health benefits associated with Dendrobium species,this work reviews their nutraceutical role in neurodegenerative disorders and further suggests the need to elucidate mechanisms of the underlying molecular actions.

In vivo evaluation of guide-free Cas9-induced safety risks in a pig model

The CRISPR/Cas9 system has shown great potential for treating human genetic diseases through gene therapy.However,there are concerns about the safety of this system,specifically related to the use of guide-free Cas9.Previous studies have shown that guidefree Cas9 can induce genomic instability in vitro.However,the in vivo safety risks associated with guide-free Cas9 have not been evaluated,which is necessary for the development of gene therapy in clinical settings.In this study,we used doxycycline-inducible Cas9-expressing pigs to evaluate the safety risks of guide-free Cas9 in vivo.Our findings demonstrated that expression of guide-free Cas9 could induce genomic damages and transcriptome changes in vivo.The severity of the genomic damages and transcriptome changes were correlate with the expression levels of Cas9 protein.Moreover,prolonged expression of Cas9 in pigs led to abnormal phenotypes,including a significant decrease in body weight,which may be attributable to genomic damage-induced nutritional absorption and metabolic dysfunction.Furthermore,we observed an increase in whole-genome and tumor driver gene mutations in pigs with long-term Cas9 expression,raising the risk of tumor occurrence.Our in vivo evaluation of guide-free Cas9 in pigs highlights the necessity of considering and monitoring the detrimental effects of Cas9 alone as genome editing via the CRISPR/Cas9 system is implemented in clinical gene therapy.This research emphasizes the importance of further study and implementation of safety measures to ensure the successful and safe application of the CRiSPR/Cas9 system in clinical practice.

Double knock-in pig models with elements of binary Tet-On and phiC31 integrase systems for controllable and switchable gene expression

Inducible expression systems are indispensable for precise regulation and in-depth analysis of biological process.Binary Tet-On system has been widely employed to regulate transgenic expression by doxycycline.Previous pig models with tetracycline regulatory elements were generated through random integration.This process often resulted in uncertain expression and unpredictable phenotypes,thus hindering their applications.Here,by precise knock-in of binary Tet-On 3G elements into Rosa26 and Hipp11 locus,respectively,a double knock-in reporter pig model was generated.We characterized excellent properties of this system for controllable transgenic expression both in vitro and in vivo.Two att P sites were arranged to flank the td Tomato to switch reporter gene.Single or multiple gene replacement was efficiently and faithfully achieved in fetal fibroblasts and nuclear transfer embryos.To display the flexible application of this system,we generated a pig strain with Dox-inducing h KRASexpression through phiC31 integrase-mediated cassette exchange.After eight months of Dox administration,squamous cell carcinoma developed in the nose,mouth,and scrotum,which indicated this pig strain could serve as an ideal large animal model to study tumorigenesis.Overall,the established pig models with controllable and switchable transgene expression system will provide a facilitating platform for transgenic and biomedical research.

Genetically humanized pigs exclusively expressing human insulin are generated through custom endonuclease-mediated seamless engineering

Dear Editor,Type1diabetes(T1D)isa lifelong(chronic)disease and a major health problem throughout the world.This disease can be treatedby either insulin injection or islet transplantation.Islet transplantation is considered as a better treatment for T1D patients,because islets can produce and release insulin at the appropriate time,resulting in tight blood glucose control.

Generation of gene-target dogs using CRISPR/Cas9 system

Dear Editor,Dogs(Canis familiaris)serve as human companions and are raised to herd livestock,aid hunters,guard homes,perform police and rescue work,and guide the blind.Dogs exhibit close similarities to humans in terms of metabolic,physiological,and anatomical characteristics,and thus are ideal genetic and clinical models to study human diseases(Tsai et al.,2007).Gene target technology is a powerful tool to create new strains of animals with favorable traits.However,thus far,gene-target dogs have not been developed due to their unique species-specific reproductive characteristics,which limits the applications of dogs especially in the field of biomedical research.Recently,clustered regularly interspaced short palindromic repeats(CRISPRs)/CRISPR-associated(Cas)9 system was applied to edit specific genes with a high efficiency(Cong et al.,2013;Mali et al.,2013).Here we attempt to explore the feasibility of producing gene knockout(KO)dogs by using this technology.Beagle dog,the most widely used breed in biomedical research,was used as our animal model.Myostatin(MSTN)was chosen as the first gene of interest.

Generation of rat blood vasculature and hematopoietic cells in rat-mouse chimeras by blastocyst complementation

Interspecies chimera through blastocyst complementation could be an alternative approach to create human organs in animals by using human pluripotent stem cells.A mismatch of the major histocompatibility complex of vascular endothelial cells between the human and host animal will cause graft rejection in the transplanted organs.Therefore,to achieve a transplantable organ in animals without rejection,creation of vascular endothelial cells derived from humans within the organ is necessary.In this study,to explore whether donor xeno-pluripotent stem cells can compensate for blood vasculature in host animals,we generated rat-mouse chimeras by injection of rat embryonic stem cells(rESCs)into mouse blastocysts with deficiency of Flk-1 protein,which is associated with endothelial and hematopoietic cell development.We found that rESCs could differentiate into vascular endothelial and hematopoietic cells in the rat-mouse chimeras.The whole yolk sac(YS)of Flk-1^EGFP/ECFP rat-mouse chimera was full of rat blood vasculature.Rat genes related to vascular endothelial cells,arteries,and veins,blood vessels formation process,as well as hematopoietic cells,were highly expressed in the YS.Our results suggested that rat vascular endothelial cells could undergo proliferation,migration,and self-assembly to form blood vasculature and that hematopoietic cells could differentiate into B cells,T cells,and myeloid cells in rat-mouse chimeras,which was able to rescue early embryonic lethality caused by Flk-1 deficiency in mouse.

Production of transgenic pigs over-expressing theantiviral gene Mx1

The myxovirus resistance gene (Mx1) has a broad spectrum of antiviral activities. It is therefore an interestingcandidate gene to improve disease resistance in farm animals. In this study, we report the use of somatic cellnuclear transfer (SCNT) to produce transgenic pigs over-expressing the Mx1 gene. These transgenic pigs expressapproximately 15–25 times more Mx1 mRNA than non-transgenic pigs, and the protein level of Mx1 was alsomarkedly enhanced. We challenged fibroblast cells isolated from the ear skin of transgenic and control pigs withinfluenza A virus and classical swine fever virus (CFSV). Indirect immunofluorescence assay (IFA) revealed a profounddecrease of influenza A proliferation in Mx1 transgenic cells. Growth kinetics showed an approximately 10-foldreduction of viral copies in the transgenic cells compared to non-transgenic controls. Additionally, we found thatthe Mx1 transgenic cells were more resistant to CSFV infection in comparison to non-transgenic cells. These resultsdemonstrate that the Mx1 transgene can protect against viral infection in cells of transgenic pigs and indicate thatthe Mx1 transgene can be harnessed to develop disease-resistant pigs.

Amelioration of ethanol-induced oxidative stress and alcoholic liver disease by in vivo RNAi targeting Cyp2e1

Alcoholic liver disease(ALD)results from continuous and heavy alcohol consumption.The current treatment strategy for ALD is based on alcohol withdrawal coupled with antioxidant drug intervention,which is a long process with poor efficacy and low patient compliance.Alcohol-induced CYP2E1 upregulation has been demonstrated as a key regulator of ALD,but CYP2E1 knockdown in humans was impractical,and pharmacological inhibition of CYP2E1 by a clinically relevant approach for treating ALD was not shown.In this study,we developed a RNAi therapeutics delivered by lipid nanoparticle,and treated mice fed on Lieber-DeCarli ethanol liquid diet weekly for up to 12 weeks.This RNAi-based inhibition of Cyp2e1 expression reduced reactive oxygen species and oxidative stress in mouse livers,and contributed to improved ALD symptoms in mice.The liver fat accumulation,hepatocyte inflammation,and fibrosis were reduced in ALD models.Therefore,this study suggested the feasibility of RNAi targeting to CYP2E1 as a potential therapeutic tool to the development of ALD.

Generation of pigs with humanized type Ⅱ collagen by precise human COL2A1 gene knock-in

Osteoarthritis(OA)is the most common chronic disease,characterized by progressive cartilage breakdown,subchondral bone sclerosis,and aberrant bone outgrowth(Yucesoy et al.,2015;Hussain et al.,2016).OA is one of the leading causes of cartilage damage.Patients with severe cartilage damage require transplantation of articular cartilage to improve their quality of life.Type Ⅱ collagen is a major component of articular cartilage and intervertebral discs and plays an important role in the structure and strength of connective tissues that support muscles and joints(Byers,1994).