Overexpression of RPOTmp Being Targeted to Either Mitochondria or Chloroplasts in Arabidopsis Leads to Overall Transcriptome Changes and Faster Growth.

The transcription of Arabidopsis organellar genes is performed by three nuclear-encoded RNA polymerases: RPOTm, RPOTmp, and RPOTp. The RPOTmp protein possesses ambiguous transit peptides, allowing participation in gene expression control in both mitochondria and chloroplasts, although its function in plastids is still under discussion. Here, we show that the overexpression of RPOTmp in Arabidopsis, targeted either to mitochondria or chloroplasts, disturbs the dormant seed state, and it causes the following effects: earlier germination, decreased ABA sensitivity, faster seedling growth, and earlier flowering. The germination of RPOTmp overexpressors is less sensitive to NaCl, while rpotmp knockout is highly vulnerable to salt stress. We found that mitochondrial dysfunction in the rpotmp mutant induces an unknown retrograde response pathway that bypasses AOX and ANAC017. Here, we show that RPOTmp transcribes the accD, clpP, and rpoB genes in plastids and up to 22 genes in mitochondria.

The level of free circulating mitochondrial DNA in blood as predictor of death in case of acute coronary syndrome.

BACKGROUND: The efficacy of treating acute myocardial ischemic damages depends, to a large extent, on the development of technologies for predicting their course and outcome. The aim of this paper was to explore whether it would be possible to consider the content of free circulating mitochondrial DNA as a danger-associated molecular pattern for assessing the probability of death from myocardial infarction. METHODS: We have analyzed the clinical outcomes based on discharge summaries and autopsy reports obtained in the course of the PROTOCOL observational trial. This study was approved by the Irkutsk Scientific Center of Surgery and Traumatology ethics committee (protocol No. 3, 10.08.2015). To examine whether the assessment of the level of free circulating mtDNA in acute coronary syndrome can help predicting clinical outcomes, all patients were divided into two groups: group 1, involving those who survived during 30 days after hospitalization, and group 2, involving those who died during this time. A quantitative analysis of the free circulating mtDNA was conducted using the PCR method in situ. RESULTS: The analysis showed that in patients who survived the level of freely circulating mtDNA (36.0 copies/ml) was 164 times lower than in those who died (5900 copies/ml, p = 0.049). It should be mentioned that according to the logistic regression analysis, the probability of death of patients with the increased level of blood plasma mtDNA (more than 4000 copies/ml) is 50%. CONCLUSIONS: Thus, the PROTOCOL observational trial proved that the increase in the content of free circulating mtDNA in blood is a predictor of lethal outcome in patients with acute coronary syndrome. Trial registration The observational studies (those in which the assignment of the medical intervention is not at the discretion of the investigator) do not require registration.

RPOTmp, an Arabidopsis RNA polymerase with dual targeting, plays an important role in mitochondria, but not in chloroplasts.

In a number of dicotyledonous plants, including Arabidopsis, the transcription of organellar genes is performed by three nuclear-encoded RNA polymerases, RPOTm, RPOTmp, and RPOTp. RPOTmp is a protein with a dual targeting, which is presumably involved in the control of gene expression in both mitochondria and chloroplasts. A previous study of the Arabidopsis insertion rpotmp mutant showed that it has retarded growth and development, altered leaf morphology, changed expression of mitochondrial and probably some chloroplast genes, and decreased activities of the mitochondrial respiratory complexes. To date, there is no clear evidence as to which of these disorders are associated with a lack of RPOTmp in each of the two organelles. The aim of this study was to elucidate the role that this RNA polymerase specifically plays in mitochondria and chloroplasts. Two sets of Arabidopsis transgenic lines with complementation of RPOTmp function in either mitochondria or chloroplasts were obtained. It was found that the recovery of RPOTmp RNA polymerase activity in chloroplasts, although restoring the transcription from the RPOTmp-specific PC promoter, did not lead to compensation of the mutant growth defects. In contrast, the rpotmp plants expressing RPOTmp with mitochondrial targeting restored the level of mitochondrial transcripts and exhibit a phenotype resembling that of the wild-type plants. We conclude that despite its localization in two cell compartments, Arabidopsis RPOTmp plays an important role in mitochondria, but not in chloroplasts.

Genetic and morphological evidence for introgression between three species of willows.

BACKGROUND: Hybridization and introgression are said to occur relatively frequently in plants, and in particular among different species of willows. However, data on the actual frequency of natural hybridization and introgression is rare. Here, we report the first fine-scale genetic analysis of a contact zone shared between the three basket willow species, Salix dasyclados, S. schwerinii and S. viminalis in the vicinity of the Lake Baikal in Southern Siberia. Individuals were sampled in fourteen populations and classified as pure species or hybrids based on a set of morphological characters. They were then genotyped at 384 nuclear SNP and four chloroplast SSR loci. The STRUCTURE and NewHybrids softwares were used to estimate the frequency and direction of hybridization using genotypic data at the nuclear SNP loci. RESULTS: As many as 19 % of the genotyped individuals were classified as introgressed individuals and these were mainly encountered in the centre of the contact zone. All introgressed individuals were backcrosses to S. viminalis or S. schwerinii and no F1 or F2 hybrids were found. The rest of the genotyped individuals were classified as pure species and formed two clusters, one with S. schwerinii individuals and the other with S. viminalis and S. dasyclados individuals. The two clusters were significantly genetically differentiated, with F ST = 0.333 (0.282-0.382, p < 0.001). In contrast, for the chloroplast haplotypes, no genetic differentiation was observed as they were completely shared between the species. Based on morphological classification only 5 % of the individuals were classified as introgressed individuals, which was much less than what was detected using genotypic data. CONCLUSIONS: We have discovered a new willow hybrid zone with relatively high frequency of introgressed individuals. The low frequency of F1 hybrids indicates that ongoing hybridization is limited, which could be because of the presence of reproductive barriers or simply because the conditions are not favorable for hybridization. We further conclude that in order to get a complete picture of the species composition of a hybrid zone it is necessary to use a combination of morphological characters and genetic data from both nuclear and chloroplast markers.