Three-Dimensional Structure of the Magnetic Field in the Disk of the Milky Way

We present Rotation Measures (RM) of the diffuse Galactic synchrotron emission from the Canadian Galactic Plane Survey (CGPS) and compare them to RMs of extragalactic sources in order to study the large-scale reversal in the Galactic magnetic field (GMF). Using Stokes Q, U and I measurements of the Galactic disk collected with the Synthesis Telescope at the Dominion Radio Astrophysical Observatory, we calculate RMs over an extended region of the sky, focusing on the low longitude range of the CGPS (l=52deg to l=72deg). We note the similarity in the structures traced by the compact sources and the extended emission and highlight the presence of a gradient in the RM map across an approximately diagonal line, which we identify with the well-known field reversal of the Sagittarius-Carina arm. We suggest that the orientation of this reversal is a geometric effect resulting from our location within a GMF structure arising from current sheets that are not perpendicular to the Galactic plane, as is required for a strictly radial field reversal, but that have at least some component parallel to the disk. Examples of models that fit this description are the three-dimensional dynamo-based model of Gressel et al. (2013) and a Galactic scale Parker spiral (Akasofu & Hakamada 1982), although the latter may be problematic in terms of Galactic dynamics. We emphasize the importance of constructing three-dimensional models of the GMF to account for structures like the diagonal RM gradient observed in this dataset.Comment: Published in Astronomy and Astrophysics, Accepted 23 April, 201

Effects of herbicides on Selenastrum capricornutum and Daphnia magna

The toxicity of five herbicides, Propanil, Machete, Rilof-H, Saturn, and Ronestar, commonly used in Iranian rice fields, were investigated in acute toxicity bioassays on two organisms belonging to different in aquatic food chain. Compared with Daphnia magna, green algae Selenastrum capricornutum, showed more sensitivly to the herbicides. Machete and Saturn were the most toxic herbicides for algae. Three other herbicides, having more effect on the toxicity rate were Ronestar, Rilof-H, and Propanil. The toxic herbicides for Daphnia magna were Rilof-H and Saturn, and the others showed less toxicity. Comparing the amount of 6 to 23 mg/1 field concentrations of the herbicides with 0.01 to 12.46 mg/1 MAV-values for Selenastrum capticomutum and 0.446 to 9.5 mg/1, MAC-values for Daphnia magna in laboratory experiments revealed that the herbicides would certainly kill all useful organisms in aquatic food chain such as algae and zooplanktons in rice fields, and would damage other neighboring ecosystems in rivers, reservoirs, lagoon and the Caspian Sea which are connected with the fields. Ministry of Agriculture should be asked to introduce other less toxic herbicides

Ecotoxicological studies on Daphnia magna

In this study we used Daphnia magna as an index organism for ecotoxicological studies. In order to determine the filtration and ingestion rates in Daphnia magna, we used algea Chlorella volgaris (10 mg/1). Prior to the tests, the acute toxicity of the herbicides Machete and Saturn and the pesticides Diazinon and Malathion, in order to calculate their EC50, were determined. The concentrations which caused the same mortality rate in 24 hours as the EC50 concentrations of these chemical did, were 18.49 mg/1 for Machete, 4.46mg/1 for Saturn, 0.31 gr/1 for Diazinon and 1.5 grit for Malathion. In order to study the toxic effect of Machete, Saturn, Diazinon and Malathion on the filtration and ingestion rates, Daphnia magna was exposed to Ec50, 3/4 Ec50 ,1/2 Ec50 and 1/4 Ec50 concentrations. The rates were reduced after the organism had been exposed to these toxic chemicals for 5 hours. The effective concentrations at which feeding rate were reduced by 50%, compared to the controls, were for herbicides activity and pesticides action. These values in regard to filtration and ingestion rates were 2.8 and 3.3 mg/1 for Machete, 1.45 and 1.6 mg/1 for Saturn, 0.16 and 0.075 mg/1 for Diazinon and 0.6 and 0.7 mg/1 for Malathion respectively

Effects of diazinon, malathion, machete and saturn on mortality of fingerling of Rutilus frisii kutum

The toxicity of the pesticides, malathion and diazinon, and the herbicides, Machete and Saturn, on mortality of fingerling of Rutilus frisii kutum were examined. Lc10 values for diazinon, Malathion, Machete and Saturn were 0.14 - 0.24, 0.10 - 0.35, 0.14 - 0.55, and 1.45 - 2.50 mg/L respectively. The result showed that diazinon, malathion and machete have a highly toxic effect on fingerling of R. frisii kutum and the herbicide, saturn, in comparison with other poisons was less toxic

USP51 deubiquitylates H2AK13,15ub and regulates DNA damage response

Dynamic regulation of RNF168-mediated ubiquitylation of histone H2A Lys13,15 (H2AK13,15ub) at DNA double-strand breaks (DSBs) is crucial for preventing aberrant DNA repair and maintaining genome stability. However, it remains unclear which deubiquitylating enzyme (DUB) removes H2AK13,15ub. Here we show that USP51, a previously uncharacterized DUB, deubiquitylates H2AK13,15ub and regulates DNA damage response. USP51 depletion results in increased spontaneous DNA damage foci and elevated levels of H2AK15ub and impairs DNA damage response. USP51 overexpression suppresses the formation of ionizing radiation-induced 53BP1 and BRCA1 but not RNF168 foci, suggesting that USP51 functions downstream from RNF168 in DNA damage response. In vitro, USP51 binds to H2A–H2B directly and deubiquitylates H2AK13,15ub. In cells, USP51 is recruited to chromatin after DNA damage and regulates the dynamic assembly/disassembly of 53BP1 and BRCA1 foci. These results show that USP51 is the DUB for H2AK13,15ub and regulates DNA damage response