Heteroplasmy of mouse mtDNA is genetically unstable and results in altered behavior and cognition.

Maternal inheritance of mtDNA is the rule in most animals, but the reasons for this pattern remain unclear. To investigate the consequence of overriding uniparental inheritance, we generated mice containing an admixture (heteroplasmy) of NZB and 129S6 mtDNAs in the presence of a congenic C57BL/6J nuclear background. Analysis of the segregation of the two mtDNAs across subsequent maternal generations revealed that proportion of NZB mtDNA was preferentially reduced. Ultimately, this segregation process produced NZB-129 heteroplasmic mice and their NZB or 129 mtDNA homoplasmic counterparts. Phenotypic comparison of these three mtDNA lines demonstrated that the NZB-129 heteroplasmic mice, but neither homoplasmic counterpart, had reduced activity, food intake, respiratory exchange ratio; accentuated stress response; and cognitive impairment. Therefore, admixture of two normal but different mouse mtDNAs can be genetically unstable and can produce adverse physiological effects, factors that may explain the advantage of uniparental inheritance of mtDNA.

mtDNA lineage analysis of mouse L-cell lines reveals the accumulation of multiple mtDNA mutants and intermolecular recombination.

The role of mitochondrial DNA (mtDNA) mutations and mtDNA recombination in cancer cell proliferation and developmental biology remains controversial. While analyzing the mtDNAs of several mouse L cell lines, we discovered that every cell line harbored multiple mtDNA mutants. These included four missense mutations, two frameshift mutations, and one tRNA homopolymer expansion. The LA9 cell lines lacked wild-type mtDNAs but harbored a heteroplasmic mixture of mtDNAs, each with a different combination of these variants. We isolated each of the mtDNAs in a separate cybrid cell line. This permitted determination of the linkage phase of each mtDNA and its physiological characteristics. All of the polypeptide mutations inhibited their oxidative phosphorylation (OXPHOS) complexes. However, they also increased mitochondrial reactive oxygen species (ROS) production, and the level of ROS production was proportional to the cellular proliferation rate. By comparing the mtDNA haplotypes of the different cell lines, we were able to reconstruct the mtDNA mutational history of the L-L929 cell line. This revealed that every heteroplasmic L-cell line harbored a mtDNA that had been generated by intracellular mtDNA homologous recombination. Therefore, deleterious mtDNA mutations that increase ROS production can provide a proliferative advantage to cancer or stem cells, and optimal combinations of mutant loci can be generated through recombination.

Progressive increase in mtDNA 3243A>G heteroplasmy causes abrupt transcriptional reprogramming.

Variation in the intracellular percentage of normal and mutant mitochondrial DNAs (mtDNA) (heteroplasmy) can be associated with phenotypic heterogeneity in mtDNA diseases. Individuals that inherit the common disease-causing mtDNA tRNA(Leu(UUR)) 3243A>G mutation and harbor ∼10-30% 3243G mutant mtDNAs manifest diabetes and occasionally autism; individuals with ∼50-90% mutant mtDNAs manifest encephalomyopathies; and individuals with ∼90-100% mutant mtDNAs face perinatal lethality. To determine the basis of these abrupt phenotypic changes, we generated somatic cell cybrids harboring increasing levels of the 3243G mutant and analyzed the associated cellular phenotypes and nuclear DNA (nDNA) and mtDNA transcriptional profiles by RNA sequencing. Small increases in mutant mtDNAs caused relatively modest defects in oxidative capacity but resulted in sharp transitions in cellular phenotype and gene expression. Cybrids harboring 20-30% 3243G mtDNAs had reduced mtDNA mRNA levels, rounded mitochondria, and small cell size. Cybrids with 50-90% 3243G mtDNAs manifest induction of glycolytic genes, mitochondrial elongation, increased mtDNA mRNA levels, and alterations in expression of signal transduction, epigenomic regulatory, and neurodegenerative disease-associated genes. Finally, cybrids with 100% 3243G experienced reduced mtDNA transcripts, rounded mitochondria, and concomitant changes in nuclear gene expression. Thus, striking phase changes occurred in nDNA and mtDNA gene expression in response to the modest changes of the mtDNA 3243G mutant levels. Hence, a major factor in the phenotypic variation in heteroplasmic mtDNA mutations is the limited number of states that the nucleus can acquire in response to progressive changes in mitochondrial retrograde signaling.

Mouse mtDNA mutant model of Leber hereditary optic neuropathy.

An animal model of Leber hereditary optic neuropathy (LHON) was produced by introducing the human optic atrophy mtDNA ND6 P25L mutation into the mouse. Mice with this mutation exhibited reduction in retinal function by elecroretinogram (ERG), age-related decline in central smaller caliber optic nerve fibers with sparing of larger peripheral fibers, neuronal accumulation of abnormal mitochondria, axonal swelling, and demyelination. Mitochondrial analysis revealed partial complex I and respiration defects and increased reactive oxygen species (ROS) production, whereas synaptosome analysis revealed decreased complex I activity and increased ROS but no diminution of ATP production. Thus, LHON pathophysiology may result from oxidative stress.

ERRγ Promotes Angiogenesis, Mitochondrial Biogenesis, and Oxidative Remodeling in PGC1α/ß-Deficient Muscle.

PGC1α is a pleiotropic co-factor that affects angiogenesis, mitochondrial biogenesis, and oxidative muscle remodeling via its association with multiple transcription factors, including the master oxidative nuclear receptor ERRγ. To decipher their epistatic relationship, we explored ERRγ gain of function in muscle-specific PGC1α/ß double-knockout (PKO) mice. ERRγ-driven transcriptional reprogramming largely rescues muscle damage and improves muscle function in PKO mice, inducing mitochondrial biogenesis, antioxidant defense, angiogenesis, and a glycolytic-to-oxidative fiber-type transformation independent of PGC1α/ß. Furthermore, in combination with voluntary exercise, ERRγ gain of function largely restores mitochondrial energetic deficits in PKO muscle, resulting in a 5-fold increase in running performance. Thus, while PGC1s can interact with multiple transcription factors, these findings implicate ERRs as the major molecular target through which PGC1α/ß regulates both innate and adaptive energy metabolism.

PPARδ Promotes Running Endurance by Preserving Glucose.

Management of energy stores is critical during endurance exercise; a shift in substrate utilization from glucose toward fat is a hallmark of trained muscle. Here we show that this key metabolic adaptation is both dependent on muscle PPARδ and stimulated by PPARδ ligand. Furthermore, we find that muscle PPARδ expression positively correlates with endurance performance in BXD mouse reference populations. In addition to stimulating fatty acid metabolism in sedentary mice, PPARδ activation potently suppresses glucose catabolism and does so without affecting either muscle fiber type or mitochondrial content. By preserving systemic glucose levels, PPARδ acts to delay the onset of hypoglycemia and extends running time by ∼100 min in treated mice. Collectively, these results identify a bifurcated PPARδ program that underlies glucose sparing and highlight the potential of PPARδ-targeted exercise mimetics in the treatment of metabolic disease, dystrophies, and, unavoidably, the enhancement of athletic performance.

ERRγ Is Required for the Metabolic Maturation of Therapeutically Functional Glucose-Responsive ß Cells.

Pancreatic ß cells undergo postnatal maturation to achieve maximal glucose-responsive insulin secretion, an energy intensive process. We identify estrogen-related receptor γ (ERRγ) expression as a hallmark of adult, but not neonatal ß cells. Postnatal induction of ERRγ drives a transcriptional network activating mitochondrial oxidative phosphorylation, the electron transport chain, and ATP production needed to drive glucose-responsive insulin secretion. Mice deficient in ß cell-specific ERRγ expression are glucose intolerant and fail to secrete insulin in response to a glucose challenge. Notably, forced expression of ERRγ in iPSC-derived ß-like cells enables glucose-responsive secretion of human insulin in vitro, obviating in vivo maturation to achieve functionality. Moreover, these cells rapidly rescue diabetes when transplanted into ß cell-deficient mice. These results identify a key role for ERRγ in ß cell metabolic maturation, and offer a reproducible, quantifiable, and scalable approach for in vitro generation of functional human ß cell therapeutics.

Identification of medicinal plants within the Apocynaceae family using ITS2 and psbA-trnH barcodes / 中国天然药物

To ensure the safety of medications, it is vital to accurately authenticate species of the Apocynaceae family, which is rich in poisonous medicinal plants. We identified Apocynaceae species by using nuclear internal transcribed spacer 2 (ITS2) and psbA-trnH based on experimental data. The identification ability of ITS2 and psbA-trnH was assessed using specific genetic divergence, BLAST1, and neighbor-joining trees. For DNA barcoding, ITS2 and psbA-trnH regions of 122 plant samples of 31 species from 19 genera in the Apocynaceae family were amplified. The PCR amplification for ITS2 and psbA-trnH sequences was 100%. The sequencing success rates for ITS2 and psbA-trnH sequences were 81% and 61%, respectively. Additional data involved 53 sequences of the ITS2 region and 38 sequences of the psbA-trnH region were downloaded from GenBank. Moreover, the analysis showed that the inter-specific divergence of Apocynaceae species was greater than its intra-specific variations. The results indicated that, using the BLAST1 method, ITS2 showed a high identification efficiency of 97% and 100% of the samples at the species and genus levels, respectively, via BLAST1, and psbA-trnH successfully identified 95% and 100% of the samples at the species and genus levels, respectively. The barcode combination of ITS2/psbA-trnH successfully identified 98% and 100% of samples at the species and genus levels, respectively. Subsequently, the neighbor joining tree method also showed that barcode ITS2 and psbA-trnH could distinguish among the species within the Apocynaceae family. ITS2 is a core barcode and psbA-trnH is a supplementary barcode for identifying species in the Apocynaceae family. These results will help to improve DNA barcoding reference databases for herbal drugs and other herbal raw materials.

Molecular Identification of Bupleurum chinense Seeds Based on DNA Barcoding Technology / 中国实验方剂学杂志

Objective:To establish a molecular identification method for Bupleurum chinense seeds based on ribosomal DNA internal transcribed spacer (ITS) sequence, ensuring the species authenticity of the cultivated seeds of B. chinense. Method:A total of 59 seeds samples of B. chinense and its main cultivated species, marketed B. chinense were collected. The effect of different sampling amounts and different water bath conditions on DNA extraction quality of the seeds was investigated, a DNA extraction method for seeds of Bupleurum was established. Their ITS sequences were obtained by polymerase chain reaction (PCR) and bidirectional sequencing. In addition, 34 ITS sequences of main cultivated Bupleurum species, such as B. chinense, B. scorzonerifolium, B. falcatum and B. smithii, were downloaded from GenBank to enrich identification database of B. chinense seeds. The neighbor-joining (NJ) dendrogram were constructed by MEGA-X 10.0.5 software to investigate the the species identification ability of ITS sequences for B. chinense seeds. And DNA barcoding identification of marketed B. chinense seeds was conducted based on BLAST method and NJ dendrogram method. Result:In total, 59 ITS sequences were obtained. ITS sequences of B. chinense could be divided into six haplotypes, including seven variable sites. The NJ dendrogram indicated that all the haplotypes of B. chinense could form independent branches, which could be distinguished from other cultivated species of Bupleurum in the collected samples, and possessed the ability to identify species of B. chinense seeds. Based on ITS sequence barcoding identification, 3 of the 19 marketed B. chinense seeds were B. falcatum with a counterfeit rate of 15.8%. Conclusion:DNA barcoding technology based on ITS sequence can accurately and reliably identify B. chinense seeds and its adulterants, providing reference for the standardization construction of Chinese medicinal materials seeds.

Construction of yeast one-hybrid library and screening of transcription factors regulating LS expression in Ganoderma lucidum / 中国中药杂志

Lanosterol synthase( LS) is a key enzyme involving in the mevalonate pathway( MVA pathway) to produce lanosterol,which is a precursor of ganoderma triterpenoid. And the transcriptional regulation of LS gene directly affects the content of triterpenes in Ganoderma lucidum. In order to study the transcriptional regulation mechanism of LS gene,yeast one-hybrid technique was used to screen the transcription regulators which interact withthe promoter of LS. The bait vector was constructed by LS promoter,then the vector was transformed yeast cells to construct bait yeast strain. One-hybrid c DNA library was constructed via SMART technology. Then the c DNA and p GADT7-Rec vector were co-transformed into the bait yeast strain to screen the upstream regulatory factors of the promoter region of LS by homologous recombination. Total of 23 positive clones were screened. After sequencing,blast was performed against the whole-genome sequence of G. lucidum. As a result,8 regulatory factors were screened out including the transcription initiation TFIIB,the alpha/beta hydrolase super family,ALDH-SF superfamily,60 S ribosomal protein L21,ATP synthase β-subunit,microtubule associated protein Cript,prote asome subunit β-1,and transaldolase. Until now,the regulation effect of these 8 regulatory factors in G.lucidum has not been reported. This study provides candidate proteins for in-depth study on the expression regulation of LS.

Identification of Chinese medicinal materials Stellariae Radix and its adulterants using DNA barcoding / 药学学报

To accurately discriminate Stellariae Radix from its adulterants, four leading candidate DNA barcoding markers were evaluated. Sixty samples including Stellariae Radix and its adulterants have been newly collected and their total genomic DNA was extracted. Four DNA barcoding markers ITS, rbcL, psbA-trnH and matK were amplified and sequenced. Their sequence characteristic analyses, Kimura-2-parameter (K2P) distance calculation and Neighbor-joining (NJ) phylogenetic tree constructions were accomplished using the MEGA 7.0 software. DNA Barcoding gaps of the four DNA barcoding markers were estimated by the distributions of inter- and intra-sequence specific variations. Species identification efficiency was calculated using the BLAST method. The results showed that ITS had the highest (95.2%) while matK demonstrated the lowest (75%) PCR and sequencing efficiency. The length range of the four markers were in the ranger of 211-797 bp, and the G+C content of ITS was highest (54.35%). The identification efficiency of matK and ITS was 92% and 90% respectively. Barcoding gap could be found in ITS sequences. The NJ phylogenetic tree constructed using ITS sequences showed that samples of Stellariae Radix were separately formed into one clade, and samples of adulterants like Stellaria bistyla were clearly belong to different branches from Stellariae Radix, whereas NJ trees constructed using psbA-trnH, rbcL and matK could not differentiate Stellariae Radix from its adulterants. Therefore, ITS regions as DNA barcodes can stably and accurately distinguished Stellariae Radix from its adulterants, and provide a new technique for modern identification of Stellariae Radix.

Identification of water buffalo horn and its adulterants using COI barcode / 药学学报

Bubali cornu (water buffalo horn) has been used as the substitute for Cornu rhinoceri asiatici (rhino horn) in clinical applications, and is the essential ingredient of Angong Niuhuang Wan. In recent years, there are a number of adulterants on the commercial herbal medicine markets. An efficient tool is required for species identification. In this study, 155 Bubali cornu samples have been taken from original animals and collected from commercial herbal medicine markets. 153 COI sequences have been successfully obtained from 155 samples through DNA extraction, PCR amplification, bidirectional sequencing and assembly. 93 COI sequences have been added to the DNA barcoding database of traditional Chinese animal medicine after validation using DNA barcoding GAP and tree-based methods. The species identification of the 62 commercial Bubali cornu medicines has been accomplished on the DNA barcoding system for identifying herbal medicine using the updated animal medicine database (www.tcmbarcode.cn). Except two samples failed to obtain COI sequences, 54.8% of the commercial Bubali cornu medicines were water buffalo horns and 29% were yak horns. Our results showed that yak horn was the major adulterant of Bubali cornu and the DNA barcoding method may accurately discriminate Bubali cornu and their adulterants. Therefore, we recommend that supervision on the herbal medicine markets should be strengthened with this new method to warren the effectiveness of herbal medicines.

Identification of Bombyx Batryticatus based on DNA barcoding technology / 药学学报

To identify the commercial medicinal materials of Bombyx Batryticatus, two-dimensional DNA barcode was used to construct the "Internet Plus" identification system for Chinese medicine, which should benefit the cross-platform communication of DNA barcode information. Bombyx Batryticatus contained Bombyx mori Linnaeus and Beauveria bassiana (Bals.) Vuillant. Both COI and ITS sequences were obtained via PCR amplification for total genomic DNA extracted from raw materials using the animal genomic DNA kit, while only ITS but no COI sequences was obtained when using the plant genomic DNA kit. The ITS sequences obtained using the animal genomic DNA kit were consistent with those using plant genomic DNA kit. The medicinal materials yielded COI sequences and identified as B. mori. According to analysis of ITS sequences, the main species of the medicinal materials were identified as B. bassiana and few were identified as other fungi. NJ trees analysis based on ITS sequences suggests that it can be easily distinguished from other fungi. Our results showed that total genomic DNA of B. mori and B. bassiana was extracted simultaneously using the animal genomic DNA kit, which could effectively solve the problem in species identification of animal and fungi mixture materials. COI and ITS regions as DNA barcodes can stably and accurately identify Bombyx Batryticatus. The "Internet Plus" two-dimensional DNA barcode system will promote the standardization and normalization of Chinese medicinal materials market.

Computational design and selections for an engineered, thermostable terpene synthase.

Terpenoids include structurally diverse antibiotics, flavorings, and fragrances. Engineering terpene synthases for control over the synthesis of such compounds represents a long sought goal. We report computational design, selections, and assays of a thermostable mutant of tobacco 5-epi-aristolochene synthase (TEAS) for the catalysis of carbocation cyclization reactions at elevated temperatures. Selection for thermostability included proteolytic digestion followed by capture of intact proteins. Unlike the wild-type enzyme, the mutant TEAS retains enzymatic activity at 65°C. The thermostable terpene synthase variant denatures above 80°C, approximately twice the temperature of the wild-type enzyme.

Identification of Notopterygium seeds using DNA barcoding method / 中国中药杂志

In order to guarantee the species correction of Notopterygium seeds, a molecular identification method with ITS2 as DNA barcode has been verified. In this study, 27 samples of Notopterygium seeds were collected from the main producing area of Notopterygium. The morphological characteristics of the Notopterygium seeds were firstly surveyed. Then the DNA extraction, PCR amplification, DNA sequencing and DNA assembly were carried out. The species identification for a Notopterygium seed was implemented through distance method, NJ-tree method and the DNA barcoding system for traditional Chinese medicine (www.tcmbarcode.cn). The results showed that the seeds of N. incisum and N. franchetii had similar morphological characteristics and were difficult to distinguish clearly based on morphological descriptions. With the results of molecular identification, 24 samples were genuine including 13 N. incisum seeds samples and 11 N. franchetii genuine seeds samples. In conclusion, DNA barcode technology can accurately and efficiently identify the species of Notopterygium seeds. Furthermore, this study will provide a new method for germplasm resources identification of medicinal materials and supplies some guidelines for establishing Chinese herbal seeds and seedlings quality standards.

Identification of antler powder components based on DNA barcoding technology / 药学学报

In order to authenticate the components of antler powder in the market, DNA barcoding technology coupled with cloning method were used. Cytochrome c oxidase subunit I (COI) sequences were obtained according to the DNA barcoding standard operation procedure (SOP). For antler powder with possible mixed components, the cloning method was used to get each COI sequence. 65 COI sequences were successfully obtained from commercial antler powders via sequencing PCR products. The results indicates that only 38% of these samples were derived from Cervus nippon Temminck or Cervus elaphus Linnaeus which is recorded in the 2010 edition of "Chinese Pharmacopoeia", while 62% of them were derived from other species. Rangifer tarandus Linnaeus was the most frequent species among the adulterants. Further analysis showed that some samples collected from different regions, companies and prices, contained adulterants. Analysis of 36 COI sequences obtained by the cloning method showed that C. elaphus and C. nippon were main components. In addition, some samples were marked clearly as antler powder on the label, however, C. elaphus or R. tarandus were their main components. In summary, DNA barcoding can accurately and efficiently distinguish the exact content in the commercial antler powder, which provides a new technique to ensure clinical safety and improve quality control of Chinese traditional medicine

DNA barcoding identification between arisaematis rhizoma and its adulterants based on ITS2 sequences / 中国中药杂志

Fifty-eight samples belonging to 7 species of Arisaematis Rhizoma and its adulterants were collected. The ITS2 locus was employed as a DNA barcode and amplified, sequenced and assembled for all of the collected samples. Then, ITS2 sequences have been annotated using HMM-based method. The intra- and inter-specific variations were calculated and NJ tree was constructed using MEGA 6.0 software. The results showed that inter-specific K2P distances were significantly larger than intra-specific distances for all of the three origin species of Arisaematis Rhizoma. Furthermore, three origin species, Arisaema amurense, A. erubescens and A. heterophyllum, can be respectively formed to be a single branch with high bootstrap values. It is concluded that ITS2 can be used to correctly identify Arisaematis Rhizoma from its adulterants and the application of ITS2 in the identification of traditional Chinese medicine has an important prospective.

Integrated DNA barcoding database for identifying Chinese animal medicine / 中国中药杂志

In order to construct an integrated DNA barcoding database for identifying Chinese animal medicine, the authors and their cooperators have completed a lot of researches for identifying Chinese animal medicines using DNA barcoding technology. Sequences from GenBank have been analyzed simultaneously. Three different methods, BLAST, barcoding gap and Tree building, have been used to confirm the reliabilities of barcode records in the database. The integrated DNA barcoding database for identifying Chinese animal medicine has been constructed using three different parts: specimen, sequence and literature information. This database contained about 800 animal medicines and the adulterants and closely related species. Unknown specimens can be identified by pasting their sequence record into the window on the ID page of species identification system for traditional Chinese medicine (www. tcmbarcode. cn). The integrated DNA barcoding database for identifying Chinese animal medicine is significantly important for animal species identification, rare and endangered species conservation and sustainable utilization of animal resources.

Identification of atractylodis macrocephalae rhizoma and atractylodis rhizoma from their adulterants using DNA barcoding / 中国中药杂志

Atractylodis Macrocephalae Rhizoma and Atractylodis Rhizoma were widely used in strengthening spleen under different disease conditions, and were easily and often misused each other. Therefore, DNA barcode was used to distinguish Atractylodis Macrocephalae Rhizoma and Atractylodis Rhizoma from their adulterants to ensure the safe use. The sequence lengths of ITS2 of Atractylodes macrocephala, Atractylodis Rhizoma (A. lancea, A. japonica and A. coreana) were both 229 bp. Among the ITS2 sequences of A. macrocephala, only one G/C transversion was detected at site 98, and the average GC content was 69.42%. No variable site was detected in the ITS2 sequences of A. lancea. The maximum K2P intraspecific genetic distances of both A. japonica and A. coreana were 0.013. The maximum K2P intraspecific genetic distances of A. macrocephala, A. lancea, A. japonica and A. coreana were less than the minimum interspecific genetic distance of adulterants. The ITS2 sequences in each of these polytypic species were separated into pairs of divergent clusters in the NJ tree. DNA barcoding could be used as a fast and accurate identification method to distinguish Atractylodis Macrocephalae Rhizoma, Atractylodis Rhizoma, from their adulterants to ensure its safe use.

Identification of Scolopendra subspinipes mutilans and its adulterants using DNA barcode / 中国中药杂志

In this study, the COI barcode was used to identify the Scolopendra medicinal materials and its adulterants in order to provide a new method for the identification of Scolopendra. Genomic DNA was extracted from the experimental samples. The COI sequences were amplified and sequenced bi-directionally. Sequence alignment and NJ tree construction was carried out by MEGA6.0 software. The results showed that the COI sequences can be obtained from all experimental samples. The average inter-specific K2P distance of Scolopendra was 0.222 and the minimum inter-specific distance was 0.190. All the Scolopendra subspinipes mutilans medicinal samples clustered into a clade in the NJ tree and can be distinguished from its adulterants. In a conclusion, COI can be used to correctly identify Scolopendra medicinal materials, and it will be a potential DNA barcode for identifying other animal medicinal materials.