A single plasmid based CRISPR interference in Synechocystis 6803 - A proof of concept.

We developed a simple method to apply CRISPR interference by modifying an existing plasmid pCRISPathBrick containing the native S. pyogenes CRISPR assembly for Synechocystis PCC6803 and named it pCRPB1010. The technique presented here using deadCas9 is easier to implement for gene silencing in Synechocystis PCC6803 than other existing techniques as it circumvents the genome integration and segregation steps thereby significantly shortens the construction of the mutant strains.

Evaluation of trace metal levels in surface water and sediments of the Hungarian upper section of the Danube River and its tributaries.

The objective of this study was to assess the concentration levels of trace metals (Zn, Hg, Cd, Cr, Ni, Pb and Cu) in surface water and bottom sediments of the Hungarian upper section of the Danube River and its main tributaries. A total of 935 samples (water and sediments) were collected from 10 different sampling sites in the period of 2001-2012 and analyzed for the trace metals. Moreover, the dissolved arsenic content was determined in a number of 467 water samples in the period of 2004-2012.

Coregulated genes link sulfide:quinone oxidoreductase and arsenic metabolism in Synechocystis sp. strain PCC6803.

Although the biogeochemistry of the two environmentally hazardous compounds arsenic and sulfide has been extensively investigated, the biological interference of these two toxic but potentially energy-rich compounds has only been hypothesized and indirectly proven. Here we provide direct evidence for the first time that in the photosynthetic model organism Synechocystis sp. strain PCC6803 the two metabolic pathways are linked by coregulated genes that are involved in arsenic transport, sulfide oxidation, and probably in sulfide-based alternative photosynthesis.

Occurrence and distribution of polycyclic aromatic hydrocarbons in surface water and sediments of the Danube River and its tributaries, Hungary.

Polycyclic aromatic hydrocarbons (PAHs) were identified and quantified in surface water and sediments from 9 sites in the Hungarian upper section of the Danube River and its tributaries in autumn 2012. The total PAH concentrations (sum of the concentrations of 17 individual PAH compounds) in water samples ranged from 67 to 96 ng L(-1), which were predominated by two- and three-ring PAHs. The total PAH concentrations in sediments ranged from 35.

Trace metal and metalloid levels in surface water of Marcal River before and after the Ajka red mud spill, Hungary.

The aim of this study was to compare and assess the dissolved concentrations of trace elements (As, Zn, Hg, Cd, Cr, Ni, Pb and Cu) in surface water of Marcal River before and after the red mud spill that occurred in Ajka, western Hungary, in October 2010. The caustic sludge flooded the surrounding settlements and polluted the nearby Torna Creek, which flows through the Marcal and Raba rivers into the Danube. A total of 92 surface water samples were collected from the Marcal River in the period of 2007-2012 and analysed for dissolved trace metal(loid)s by atomic absorption spectroscopy method.

Occurrence and distribution of polycyclic aromatic hydrocarbons in surface water of the Raba River, Hungary.

The objective of this study was to investigate the concentration level and distribution of polycyclic aromatic hydrocarbons (PAHs) in surface water of the Raba River; the largest Danube tributary in Hungary. A total of 54 water samples were collected in the period of 2008-2011 and analysed for PAHs by gas chromatography-mass spectrometry (GC/MS) method. The total PAH concentrations (sum of the concentrations of 17 individual PAH compounds) ranged from 41 to 437 ng/L with the mean value of 111 ±  69.

Polycyclic aromatic hydrocarbons in surface water and bed sediments of the Hungarian upper section of the Danube River.

This study was performed to elucidate the distribution, concentration trend and possible source of polycyclic aromatic hydrocarbons (PAHs) in surface water and bed sediments of the Hungarian upper section of the Danube River and the Moson Danube branch. A total of 217 samples (water and sediments) were collected from four different sampling sites in the period of 2001-2010 and analysed for the 16 priority US Environmental Protection Agency PAHs. Concentrations of total 16 PAHs (∑PAHs) in water samples ranged from 25 to 1,208 ng/L, which were predominated by two- and three-ring PAHs.