Induce male sterility by CRISPR/Cas9-mediated mitochondrial genome editing in tobacco.

Genome editing has become more and more popular in animal and plant systems following the emergence of CRISPR/Cas9 technology. However, target sequence modification by CRISPR/Cas9 has not been reported in the plant mitochondrial genome, mtDNA. In plants, a type of male sterility known as cytoplasmic male sterility (CMS) has been associated with certain mitochondrial genes, but few genes have been confirmed by direct mitochondrial gene-targeted modifications. Here, the CMS-associated gene (mtatp9) in tobacco was cleaved using mitoCRISPR/Cas9 with a mitochondrial localization signal. The male-sterile mutant, with aborted stamens, exhibited only 70% of the mtDNA copy number of the wild type and exhibited an altered percentage of heteroplasmic mtatp9 alleles; otherwise, the seed setting rate of the mutant flowers was zero. Transcriptomic analyses showed that glycolysis, tricarboxylic acid cycle metabolism and the oxidative phosphorylation pathway, which are all related to aerobic respiration, were inhibited in stamens of the male-sterile gene-edited mutant. In addition, overexpression of the synonymous mutations dsmtatp9 could restore fertility to the male-sterile mutant. Our results strongly suggest that mutation of mtatp9 causes CMS and that mitoCRISPR/Cas9 can be used to modify the mitochondrial genome of plants.

Prognostic significance and clinicopathological features of hypoxic inducible factor-2alpha expression in hepatocellular carcinoma.

OBJECTIVES: To assess the association between hypoxic inducible factor-2alpha (HIF-2α) and hepatocellular carcinoma (HCC) by meta-analysis. METHODS: This study was carried out at Anhui Province Hospital, Hefei, Anhui, China in February 2014. We searched various databases for studies published in English or Chinese up to February 28, 2014. The hazard ratio for overall survival and analyzed odds ratio were combined to evaluate the clinicopathological features of HIF-2α expression in HCC. RESULTS: A total of 7 eligible studies comprising 1066 patients with HCC were identified after our full assessment according to inclusion criteria. All of the patients came from China. The results indicated that the association between HIF-2α expression and prognostic values in HCC was inconspicuous, while the expression of HIF-2α was significantly associated with capsule infiltration, vein invasion, and histological grade. CONCLUSION: Expression of HIF-2α was associated with invasion and metastasis in HCC, but did not have a distinct significance in prognosis, according to the limited evidence. However, high quality, large sample size, and controlled trials are required.