Toward genetic transformation of mitochondria in mammalian cells using a recoded drug-resistant selection marker

Due to technical difficulties,the genetic transformation of mitochondria in mammalian cells is still a challenge.In this report,we described our attempts to transform mammalian mitochondria with an engineered mitochondrial genome based on selection using a drug resistance gene.Because the standard drug-resistant neomycin phosphotransferase confers resistance to high concentrations of G418 when targeted to the mitochondria,we generated a recoded neomycin resistance gene that uses the mammalian mitochondrial genetic code to direct the synthesis of this protein in the mitochondria,but not in the nucleus（mitochondrial version）.We also generated a universal version of the recoded neomycin resistance gene that allows synthesis of the drug-resistant proteins both in the mitochondria and nucleus.When we transfected these recoded neomycin resistance genes that were incorporated into the mouse mitochondrial genome clones into mouse tissue culture cells by electroporation,no DNA constructs were delivered into the mitochondria.We found that the universal version of the recoded neomycin resistance gene was expressed in the nucleus and thus conferred drug resistance to G418 selection,while the synthetic mitochondrial version of the gene produced no background drug-resistant cells from nuclear transformation.These recoded synthetic drug-resistant genes could be a useful tool for selecting mitochondrial genetic transformants as a precise technology for mitochondrial transformation is developed.

Heavy Metal Distribution Map in Soil by Using GIS Techniques

A detailed investigation was conducted to understand the contamination characteristics and distributions of heavy metal pollution in terms of contributions of the heavy metal concentrations as mg/kg ofCd, Cr, Cu, Ni, Zn, Pb, Fe and Mn in the urban soil in Eskisehir city center. The amount of these heavy metals were determined from 15 soil sample points collected within urban area and every sample point included 6 separated samples for chemical analyses. The results indicated that concentration values of all metals except Ni and Cr in soils were below the risky limit pollution values which are recommended by Turkey Ministry of Environment and Forestry in some sample points. Spatial distribution maps were created and recoded, in terms of these heavy metals concentrations as contribution to heavy metal pollution in soil, through Geographical Information Systems techniques. As a result, risky areas were modeled in terms of contamination of heavy metal and it is shown that, every different risky area can be interpreted based on buildings in city center quickly and easily.

应用死亡相关情况分类法(ReCoDe)对死产分类的人群队列研究

Objective: To develop and test a new classification system for stillbirths to help improve understanding of the main causes and conditions associated with fetal death. Design: Population based cohort study. Setting: West Midlands region. Subjects: 2625 stillbirths from 1997 to 2003. Main outcome measures: Categories of death according to conventional classification methods and a newly developed system (ReCoDe, relevant condition at death). Results: By the conventional Wigglesworth classification, 66.2%of the stillbirths (1738 of 2625) were unexplained. The median gestational age of the unexplained group was 237 days, significantly higher than the stillbirths in the other categories (210 days; P < 0.001). The proportion of stillbirths that were unexplained was high regardless of whether a postmortem examination had been carried out or not (67%and 65%; P = 0.3). By the ReCoDe classification, the most common condition was fetal growth restriction (43.0%), and only 15.2%of stillbirths remained unexplained. ReCoDe identified 57.7%of the Wigglesworth unexplained stillbirths as growth restricted. The size of the category for intrapartum asphyxia was reduced from 11.7%(Wigglesworth) to 3.4%(ReCoDe). Conclusion: The new ReCoDe classification system reduces the predominance of stillbirths currently categorised as unexplained. Fetal growth restriction is a common antecedent of stillbirth, but its high prevalence is hidden by current classification systems. This finding has profound implications for maternity services, and raises the question whether some hitherto “unexplained”stillbirths may be avoidable.

The Integrative Studies on the Functional A-to-I RNA Editing Events in Human Cancers

Adenosine-to-inosine(A-to-I)RNA editing,constituting nearly 90%of all RNA editing events in humans,has been reported to contribute to the tumorigenesis in diverse cancers.However,the comprehensive map for functional A-to-I RNA editing events in cancers is still insufficient.To fill this gap,we systematically and intensively analyzed multiple tumorigenic mechanisms of A-to-I RNA editing events in samples across 33 cancer types from The Cancer Genome Atlas.For individual candidate among1,500,000 quantified RNA editing events,we performed diverse types of downstream functional annotations.Finally,we identified 24,236 potentially functional A-to-I RNA editing events,including the cases in APOL1,IGFBP3,GRIA2,BLCAP,and miR-589-3p.These events might play crucial roles in the scenarios of tumorigenesis,due to their tumor-related editing frequencies or probable effects on altered expression profiles,protein functions,splicing patterns,and microRNA regulations of tumor genes.Our functional A-to-I RNA editing events(https://ccsm.uth.edu/CAeditome/)will help better understand the cancer pathology from the A-to-I RNA editing aspect.

Synthetic genome with recoding

With the development of DNA synthesis techniques,synthetic biology has enabled redesign and construction of genome on purposes(Luo et al.,2018).The whole-genome recoding of Escherichia coli could be used to enhance incorporation of non-natural amino acids into proteins and to construct safer and multi-virus-resistant strains,which has always been a long-cherished wish in synthetic biology.In recent years,many research teams around the world have been engaged in genetic recoding.The Church group in Harvard University used the MAGE technique to convert 314 TAG stop codons into TAA,generating a first E.coli that is completely recoding for TAG codon(Isaacs et al.,2011).