Gama, A. | Search bioRxiv

bioRxiv2022

Estimating sequence diversity of prion protein gene (PRNP) in Portuguese populations of two cervid species: red deer and fallow deer.

Among the transmissible spongiform encephalopathies (TSEs), chronic wasting disease (CWD) in cervids is now a rising concern in wildlife within Europe, after the detection of the first case in Norway in 2016, in a wild reindeer and until June 2022 a total of 34 cases were described in Norway, Sweden and Finland. The definite diagnosis is postmortem, performed in target areas of the brain and lymph nodes. Samples are first screened using a rapid test and, if positive, confirmed by immunohistochemistry and Western immunoblotting. The study of the genetics of the prion protein gene, PRNP, has been proved to be a valuable tool for determining the relative susceptibility to TSEs. In the present study, the exon 3 of PRNP gene of 143 samples from red deer (Cervus elaphus) and fallow deer (Dama dama) of Portugal was analyzed. Three single nucleotide polymorphisms (SNPs) were found in red deer - codon A136A, codon T98A, codon Q226E - and no sequence variation was detected in fallow deer. The low genetic diversity found in our samples is compatible with previous studies in Europe. The comparison with results from North America, suggests that the free-ranging deer from our study may present susceptibility to CWD, although lack of experimental data and the necessity of extensive survey are necessary to evaluate these populations.

genetics↗

bioRxiv2020

Acute ethanol stress induces sumoylation of conserved chromatin structural proteins in Saccharomyces cerevisiae

Stress is a ubiquitous part of life that disrupts cellular function and, if unresolved, can irreparably damage essential biomolecules and organelles. All organisms can experience stress in the form of unfavorable environmental conditions including exposure to extreme temperatures, hypoxia, reactive oxygen species, alcohol, or shifts in osmolarity. To survive, organisms must sense these changes then react and adapt. One highly conserved adaptive response to stress is through protein sumoylation, which is a post-translational modification by the small ubiquitin-like modifier (SUMO) protein. In this study, we examine the effects of acute ethanol stress on protein sumoylation in the budding yeast Saccharomyces cerevisiae. Although ethanol induces protein sumoylation, the targets and roles of sumoylation are largely unknown. Here, we found that cells exhibit a transient sumoylation response after exposure of cells to [≤] 7.5% volume/volume ethanol. The response peaks at 15 minutes and resolves by 60 minutes, indicating that cells have an adaptive response to low concentrations of ethanol. By contrast, the sumoylation response becomes chronic at 10% ethanol stress with no resolution by 60 minutes. To identify key targets of ethanol-induced sumoylation, we performed mass spectrometry analyses and identified 18 proteins with increased sumoylation after acute ethanol exposure, with 15 identified as known chromatin-associated proteins. Two of these proteins are the chromatin structural proteins Smc5 and Smc6, which are sumoylated by the activity of the SUMO ligase Mms21. Ethanol-induced Smc5/6 sumoylation occurs during G1 and G2M phases of the cell cycle but is abrogated during S phase despite the fact that other proteins are sumoylated during this phase. Acute ethanol exposure leads to formation of Rad52 foci indicating DNA damage similar to that observed with the addition of methyl methanesulfonate (MMS), which is an alkylating agent that damages DNA. Whereas MMS exposure induces the intra-S phase DNA damage checkpoint as observed by Rad53 phosphorylation, ethanol exposure does not induce the intra-S phase checkpoint and prevents Rad53 phosphorylation when added with MMS. From these results, we propose that ethanol induces a structural change in chromatin, possibly through DNA damage, and this causes sumoylation of conserved chromatin-associated proteins, including Smc5 and Smc6.

cell biology↗