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Institute
Ground and space-based geomagnetic data were used in the investigation of the longitudinal, seasonal and lunar phase dependence of the equatorial counter electrojet (CEJ) occurrence in the Peruvian, Brazilian, African, Indian and Philippine sectors during geomagnetically quiet days from the solar cycle 24 (2008 to 2018). We found that CEJ events occur more frequently during the morning (MCEJ) than in the afternoon (ACEJ). The highest MCEJ and ACEJ occurrence rates were observed for the Brazilian sector. Distinct seasonal dependence was found for each longitudinal sector under investigation. The lunar phase dependence was determined for the first time for the Philippine sector (longitude 125 degrees E), and it was shown to be less pronounced than in the Peruvian, Brazilian and African sectors. We demonstrate that differences in CEJ rates derived from ground-based and satellite data can arise from the longitudinal separation between low-latitude and equatorial stations that are used to determine the signal and its consequent time delay in their sunrise/sunset times at ionospheric heights.
Methylmercury (MeHg), an abundant environmental pollutant, has long been known to adversely affect neurodevelopment in both animals and humans. Several reports from epidemiological studies, as well as experimental data indicate sex-specific susceptibility to this neurotoxicant; however, the molecular bases of this process are still not clear. In the present study, we used Caenorhabditis elegans (C. elegans), to investigate sex differences in response to MeHg toxicity during development. Worms at different developmental stage (L1, L4, and adult) were treated with MeHg for 1h. Lethality assays revealed that male worms exhibited significantly higher resistance to MeHg than hermaphrodites, when at L4 stage or adults. However, the number of worms with degenerated neurons was unaffected by MeHg, both in males and hermaphrodites. Lower susceptibility of males was not related to changes in mercury (Hg) accumulation, which was analogous for both wild-type (wt) and male-rich him-8 strain. Total glutathione (GSH) levels decreased upon MeHg in him-8, but not in wt. Moreover, the sex-dependent response of the cytoplasmic thioredoxin system was observedmales exhibited significantly higher expression of thioredoxin TRX-1, and thioredoxin reductase TRXR-1 expression was downregulated upon MeHg treatment only in hermaphrodites. These outcomes indicate that the redox status is an important contributor to sex-specific sensitivity to MeHg in C. elegans.