Interaction of warm acclimation, low salinity, and trophic fluoride on plasmatic constituents of the Antarctic fish Notothenia rossii Richardson, 1844.

The adaptive evolution of the Notothenia rossii occurred under the selective pressure of stable and low temperatures. It is an opportunistic feeder of Antarctic krill and the fluoride in the krill carapace is apparently not toxic. We investigated the interactive effect of fluoride, elevated temperatures, and low salinity on the plasmatic constituents of this Antarctic fish. The experiments were conducted at the Brazilian Antarctic Station Comandante Ferraz (EACF), located on King George Island. The Antarctic fish N. rossii was acclimatized to eight thermo-saline-trophic conditions, combining two temperatures (0 and 4 °C), two salinities (35 and 20), and two trophic conditions (with/without fluoride) for an 11-day period. Trophic fluoride was not able to alter the plasmatic levels of glucose, cholesterol, plasmatic protein, Cl⁻, Mg²âº, Ca²âº, and inorganic phosphate, but induced an acute elevation of triglycerides at 0 °C and salinity of 35. At low salinity, hyperglycemia, hypertriglyceridemia, and hypocalcemia were observed. The thermo-saline interaction at 4 °C was able to minimize the effects of fluoride and low salinity on the plasmatic constituents levels.

Bisulfite sequencing and dinucleotide content analysis of 15 imprinted mouse differentially methylated regions (DMRs): paternally methylated DMRs contain less CpGs than maternally methylated DMRs.

Imprinted genes in mammals show monoallelic expression dependent on parental origin and are often associated with differentially methylated regions (DMRs). There are two classes of DMR: primary DMRs acquire gamete-specific methylation in either spermatogenesis or oogenesis and maintain the allelic methylation differences throughout development; secondary DMRs establish differential methylation patterns after fertilization. Targeted disruption of some primary DMRs showed that they dictate the allelic expression of nearby imprinted genes and the establishment of the allelic methylation of secondary DMRs. However, how primary DMRs are recognized by the imprinting machinery is unknown. As a step toward elucidating the sequence features of the primary DMRs, we have determined the extents and boundaries of 15 primary mouse DMRs (including 12 maternally methylated and three paternally methylated DMRs) in 12.5-dpc embryos by bisulfite sequencing. We found that the average size of the DMRs was 3.2 kb and that their average G+C content was 54%. Dinucleotide content analysis of the DMR sequences revealed that, although they are generally CpG rich, the paternally methylated DMRs contain less CpGs than the maternally methylated DMRs. Our findings provide a basis for the further characterization of DMRs.