The phosphoenolpyruvate-dependent glucose phosphotransferase system (PTSGlc) is the major uptake system responsible for transporting glucose, and is involved in glucose translocation and phosphorylation in Corynebacterium glutamicum. For the longest time, the PTSGlc was considered as the only uptake system for glucose. However, some PTS-independent glucose uptake systems (non-PTSGlc) were discovered in recent years, such as the coupling system of inositol permeases and glucokinases (IPGS) and the coupling system of β-glucoside-PTS permease and glucokinases (GPGS). The products (e.g. lysine, phenylalanine and leucine) will be increased because of the increasing intracellular level of phosphoenolpyruvate (PEP), while some by-products (e.g. lactic acid, alanine and acetic acid) will be reduced when this system become the main uptake pathway for glucose. In this review, we survey the uptake systems for glucose in C. glutamicum and their composition. Furthermore, we summarize the latest research of the regulatory mechanisms among these glucose uptake systems. Detailed strategies to manipulate glucose uptake system are addressed based on this knowledge.

Genome editing is a genetic engineering technique that uses site-directed cleavage activity of specific artificial nucleases and endogenous DNA damage repair activity to generate insertions, deletions or substitutions in the targeted genomic loci. As the accuracy and efficiency of genome editing is improving and the operation is simple, the application of genome editing is expanding. This article provides an overview of the three major genome editing technologies and genome editing types, and the regulatory frameworks for genome-edited products were summarized in the United States, the European Union, and other countries. At the same time, based on the Chinese safety management principles and systems for genetically modified organisms (GMOs), the authors proposed a regulatory framework for genome-edited products. Genome-edited products should first be classified according to whether containing exogenous genetic components such as Cas9 editing enzymes or not. They should be regulated as traditional genetically modified organisms if they do. Otherwise, the regulation of genome-edited products depends on targeted modifications.
基因组编辑技术是指利用特异性核酸酶的定点剪切活性与细胞内源DNA 损伤修复活性，在基因组水平上对目的核酸序列或单个核苷酸进行定点修饰的基因工程技术，该技术可以对生物体基因组进行精确敲除、插入、单碱基突变或置换等编辑。目前，基因组编辑技术具有精确性、高效性及易操作性，应用范围日益扩大。文中简要概述了3 种主要的基因组编辑技术工具及基因组编辑类型，介绍了美国、欧盟等国家和地区对基因组编辑产品的监管体制。同时，基于我国对转基因产品的安全管理原则与体系，初步提出了基因组编辑产品的安全管理思路。根据中间材料或产品中是否含有外源编辑酶蛋白基因成分对基因组编辑产品进行分类管理，含有外源编辑酶的材料应按现有转基因安全管理办法进行管理；中间材料或产品中不含有Cas9 等编辑酶的材料应根据被编辑位点的特征进行具体分类管理。.

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Suppressor tRNAs bear anticodon mutations that allow them to decode premature stop codons in metabolic marker gene mRNAs, that can be used as in vivo reporters of functional tRNA biogenesis. Here, we review key components of a suppressor tRNA system specific to Schizosaccharomyces pombe and its adaptations for use to study specific steps in tRNA biogenesis. Eukaryotic tRNA biogenesis begins with transcription initiation by RNA polymerase (pol) III. The nascent pre-tRNAs must undergo folding, 5\' and 3\' processing to remove the leader and trailer, nuclear export, and splicing if applicable, while multiple complex chemical modifications occur throughout the process. We review evidence that precursor-tRNA processing begins with transcription termination at the oligo(T) terminator element, which forms a 3\' oligo(U) tract on the nascent RNA, a sequence-specific binding site for the RNA chaperone, La protein. The processing pathway bifurcates depending on a poorly understood property of pol III termination that determines the 3\' oligo(U) length and therefore the affinity for La. We thus review the pol III termination process and the factors involved including advances using gene-specific random mutagenesis by dNTP analogs that identify key residues important for transcription termination in certain pol III subunits. The review ends with a \'technical approaches\' section that includes a parts lists of suppressor-tRNA alleles, strains and plasmids, and graphic examples of its diverse uses.

Genetic manipulation of the unicellular green alga Chlamydomonas reinhardtii is straightforward. Nuclear genes can be interrupted by insertional mutagenesis or targeted by RNA interference whereas random or site-directed mutagenesis allows the introduction of mutations in the mitochondrial genome. This, combined with a screen that easily allows discriminating respiratory-deficient mutants, makes Chlamydomonas a model system of choice to study mitochondria biology in photosynthetic organisms. Since the first description of Chlamydomonas respiratory-deficient mutants in 1977 by random mutagenesis, many other mutants affected in mitochondrial components have been characterized. These respiratory-deficient mutants increased our knowledge on function and assembly of the respiratory enzyme complexes. More recently some of these mutants allowed the study of mitochondrial gene expression processes poorly understood in Chlamydomonas. In this review, we update the data concerning the respiratory components with a special focus on the assembly factors identified on other organisms. In addition, we make an inventory of different mitochondrial respiratory mutants that are inactivated either on mitochondrial or nuclear genes.

As an efficient and promising protein engineering strategy, directed evolution includes the construction of mutant libraries and screening of desirable mutants. A rapid and high-throughput screening method has played a critical role in the successful application of directed evolution strategy. We reviewed several high-throughput screening tools which have great potential to be applied in directed evolution. The development of powerful high-throughput screening tools will make great contributions to the advancement of protein engineering.

Nine consecutive isogenic Aspergillus fumigatus isolates cultured from a patient with aspergilloma were investigated for azole resistance. The first cultured isolate showed a wild-type phenotype, but four azole-resistant phenotypes were observed in the subsequent eight isolates. Four mutations were found in the cyp51A gene of these isolates, leading to the substitutions A9T, G54E, P216L, and F219I. Only G54 substitutions were previously proved to be associated with azole resistance. Using a Cyp51A homology model and recombination experiments in which the mutations were introduced into a susceptible isolate, we show that the substitutions at codons P216 and F219 were both associated with resistance to itraconazole and posaconazole. A9T was also present in the wild-type isolate and thus considered a Cyp51A polymorphism. Isolates harboring F219I evolved further into a pan-azole-resistant phenotype, indicating an additional acquisition of a non-Cyp51A-mediated resistance mechanism. Review of the literature showed that in patients who develop azole resistance during therapy, multiple resistance mechanisms commonly emerge. Furthermore, the median time between the last cultured wild-type isolate and the first azole-resistant isolate was 4 months (range, 3 weeks to 23 months), indicating a rapid induction of resistance.

Nicotinic acetylcholine receptors (nAChRs) are members of the Cys-loop family of neurotransmitter-gated ion channels, a family that also includes receptors for gamma-aminobutyric acid, glycine and 5-hydroxytryptamine. In humans, nAChRs have been implicated in several neurological and psychiatric disorders and are major targets for pharmaceutical drug discovery. In addition, nAChRs are important targets for neuroactive pesticides in insects and in other invertebrates. Historically, nAChRs have been one of the most intensively studied families of neurotransmitter receptors. They were the first neurotransmitter receptors to be biochemically purified and the first to be characterized by molecular cloning and heterologous expression. Although much has been learnt from studies of native nAChRs, the expression of recombinant nAChRs has provided dramatic advances in the characterization of these important receptors. This review will provide a brief history of the characterization of nAChRs by heterologous expression. It will focus, in particular, upon studies of recombinant nAChRs, work that has been conducted by many hundreds of scientists during a period of almost 30 years since the molecular cloning of nAChR subunits in the early 1980s.

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The restriction site mutation (RSM) assay has been employed in our laboratory, as a mutation detection system, since its first description in 1990. In principle the technique is capable of detecting mutations in ubiquitous restriction enzyme sites and is, therefore, readily applicable to any sequenced gene and/or organism. The RSM assay has been applied in our laboratory in various species, detecting rare mutations induced in mouse, rat, Xenopus, flatfish and human cells and tissues. This paper reviews the data accumulated by the RSM methodology in our hands and charts the developmental processes which have steadily improved the technique such that it is now applicable as a sensitive genotypic mutation detection system. This paper also includes PCR primer sequences and restriction enzymes employed in mutational analyses performed in the various species studied. We detail a variety of problems associated with the assay and the steps taken to solve them. The specific hurdles which have been overcome include the lack of quantitative data, the question of the contribution of DNA adducts to the induced mutation profile and the presence of false positives. Finally, the methods which have been developed to increase the sensitivity of the assay are also detailed. This paper describes our recommended RSM methodology, as it is routinely employed in our laboratory, which enables the analyses of mutations induced by chemical exposures and spontaneous endogenous processes. Our aim in presenting the developmental data on the RSM assay is to provide other researchers with sufficient information about the RSM methodology to facilitate its application in mutation analysis in other genes and organisms.