The S phase checkpoint promotes the Smc5/6 complex dependent SUMOylation of Pol2, the catalytic subunit of DNA polymerase ε

Replication fork stalling and accumulation of single-stranded DNA trigger the S phase checkpoint, a signalling cascade that, in budding yeast, leads to the activation of the Rad53 kinase. Rad53 is essential in maintaining cell viability, but its targets of regulation are still partially unknown. Here we show that Rad53 drives the hyper-SUMOylation of Pol2, the catalytic subunit of DNA polymerase ε, principally following replication forks stalling induced by nucleotide depletion. Pol2 is the main target of SUMOylation within the replisome and its modification requires the SUMO-ligase Mms21, a subunit of the Smc5/6 complex. Moreover, the Smc5/6 complex co-purifies with Pol ε, independently of other replisome components. Finally, we map Pol2 SUMOylation to a single site within the N-terminal catalytic domain and identify a SUMO-interacting motif at the C-terminus of Pol2. These data suggest that the S phase checkpoint regulate Pol ε during replication stress through Pol2 SUMOylation and SUMO-binding abilit

Methylated H3K4, a Transcription-Associated Histone Modification, Is Involved in the DNA Damage Response Pathway

Eukaryotic genomes are associated with a number of proteins such as histones that constitute chromatin. Post-translational histone modifications are associated with regulatory aspects executed by chromatin and all transactions on genomic DNA are dependent on them. Thus, it will be relevant to understand how histone modifications affect genome functions. Here we show that the mono ubiquitylation of histone H2B and the tri-methylation of histone H3 on lysine 4 (H3K4me3), both known for their involvement in transcription, are also important for a proper response of budding yeast cells to DNA damaging agents and the passage through S-phase. Cells that cannot methylate H3K4 display a defect in double-strand break (DSB) repair by non-homologous end joining. Furthermore, if such cells incur DNA damage or encounter a stress during replication, they very rapidly lose viability, underscoring the functional importance of the modification. Remarkably, the Set1p methyltransferase as well as the H3K4me3 mark become detectable on a newly created DSB. This recruitment of Set1p to the DSB is dependent on the presence of the RSC complex, arguing for a contribution in the ensuing DNA damage repair process. Taken together, our results demonstrate that Set1p and its substrate H3K4me3, which has been reported to be important for the transcription of active genes, also plays an important role in genome stability of yeast cells. Given the high degree of conservation for the methyltransferase and the histone mark in a broad variety of organisms, these results could have similar implications for genome stability mechanisms in vertebrate and mammalian cells

Forest management and hunting in areas adjacent to national parks: the example of the Magura National Park

The aim of the study was to evaluate arguments for hunting and its impact on forest management and conservation in national parks as well as areas directly adjacent to them. The issue was examined using the example of the Magura National Park (MNP) for which data on the number of deer and predatory mammals included in the statistical yearbooks for 2013–2014 were available. The quality and size of the food sources provided by this type of forest habitat were evaluated using data obtained from the literature. We also included data on the dietary habits of wolves and lynxes as well as their impact on the number of large ungulates in our analysis. The maximum carrying capacity of forest stands in the Magura National Park was determined to be 789 deer units (dear unit = 1 red deer or 0,3 elk or 5 roe deer), whereas in fact in 2014, the abundance of ungulates reached a total of 1230 deer units. Our analysis evaluating the impact of wolf and lynx populations on ungulates in the area showed that these predators can kill up to 212 deer per year (140 individuals by wolves and 72 by lynxes). The growth in deer population, however, varies from 25,8% to 27,7%, which in the MNP amounts to 258–277 new born individuals per year, meaning that the wolf and lynx populations in the MNP are not able to prevent the number of deer from growing. The current population of ungulates (1230 deer units ) having reached a density of 6,6 deer units/km2 exceeds the capacity of the MNP and thus poses a real threat to maintaining both, the nature of the park and the adjacent stands. This article shows that the natural maintenance of balance in the predator-prey relationship is unlikely under these conditions and failure to allow for anthropogenic interference to regulate the number of ungulates in protected areas may result in an increase in the density of their population. Potential destruction of other valuable assets such as forest habitats may consequently follow

Impact of forest cover and the soil type on the quality of male roe deer in the Kielce region

The aim of the study was to verify the hypothesis that the quality of male roe deer hunted in the Kielce region depends on the selected characteristics of the place of their earlier habitat (forest cover, soil) and the age of the individuals. As a criteria to verify that hypothesis we chose carcass weight, weight and height of the antlers and skull dimensions. Material consisted of carcasses and antlers of 1349 bucks harvested in 169 hunting districts in the Kielce region (central Poland). We found that the individual quality of male roe deer was diverse. Significant impact was found for the forest cover, diversity of soil types and age of the individuals. Roe deer with the smallest carcass weight, having significantly lighter antlers occurred in areas with the forest cover of over 40% (tab. 1). In turn, in the filed−type circuits, where the forest cover does not exceed 20%, bucks were much heavier and imposed massive antlers (fig. 1). There was also evidence that in areas where the fertile soil dominated (rendzina and chernozems) individual quality of deer was significantly better than in districts where poor fawn and rust soils predominated (fig. 2). The examined environmental factors had the greatest impact on carcass or antlers weight, as well as the dimensions of deer skulls in case of the youngest bucks and their impact decreased with age. Optimum of the individual's development in terms of carcass weight and antler falls at the age of seven. Bucks harvested in the Kielce region, in comparison to the other populations in Poland, were characterized by good individual quality and slightly subsided only to individuals from the Lublin Upland (tab. 2)

Capacity of the forest hunting grounds on the example of the Kluczbork Forest District

The aim of the study was to determine the abundance of winter food of cervids and the capacity of the Game Breeding Centre 'Krystyna' administered by the Kluczbork Forest District (southern Poland). Research was based on the estimation of shoots available for cervids in winter time. Evaluation of annual increment of biomass was calculated on 160 circular plots, on which occurrence of trees and shrubs species was estimated (tab. 1). We assumed that the cervids cause 20% loss of growth of shoots for forest species and 90% for other species. Among the 4296 examined trees or shrubs we identified 15 deciduous and 4 coniferous species (tab. 2). The estimation of the potential food for cervids showed a significant variation depending on the species. Among the conifers, the largest total weight of shoots was observed for spruce and pine, while among the deciduous species, the largest reserves of shoots were noted for hornbeam, birch, beech and mountain ash (fig. 2). The so called secure resources amounts to approximately 8 t/1000 ha, which accounted for 35% of the total stock of shoots up to 2 m above the ground. The most food was offered by spruce and pine (over 2.5 t/1000 ha), and hornbeam, mountain ash, black cherry, birch, beech and alder buckthorn (fig. 4). Based on the calculated mass of the shoots possible to eat by deer without threat of the economic damage, we calculated capacity of the forest hunting grounds using two variants of the winter (short and long), and three variants of share the shoots in the diet. The obtained capacity amounted to on average from 120 to 144 deer/1000 ha during short winter or from 103 to 123 deer during the long winter. These results point to the urgent need to objectify the existing rules for determining allowable density of deer at the local level

TIF1 Activates the Intra-S-Phase Checkpoint Response in the Diploid Micronucleus and Amitotic Polyploid Macronucleus of Tetrahymena

The ribosomal DNA origin binding protein Tif1p regulates the timing of rDNA replication and is required globally for proper S-phase progression and division of the Tetrahymena thermophila macronucleus. Here, we show that Tif1p safeguards chromosomes from DNA damage in the mitotic micronucleus and amitotic macronucleus. TIF1p localization is dynamically regulated as it moves into the micro- and macronucleus during the respective S phases. TIF1 disruption mutants are hypersensitive to hydroxyurea and methylmethanesulfonate, inducers of DNA damage and intra-S-phase checkpoint arrest in all examined eukaryotes. TIF1 mutants incur double-strand breaks in the absence of exogenous genotoxic stress, destabilizing all five micronuclear chromosomes. Wild-type Tetrahymena elicits an intra-S-phase checkpoint response that is induced by hydroxyurea and suppressed by caffeine, an inhibitor of the apical checkpoint kinase ATR/MEC1. In contrast, hydroxyurea-challenged TIF1 mutants fail to arrest in S phase or exhibit caffeine-sensitive Rad51 overexpression, indicating the involvement of TIF1 in checkpoint activation. Although aberrant micro- and macronuclear division occurs in TIF1 mutants and caffeine-treated wild-type cells, TIF1p bears no similarity to ATR or its substrates. We propose that TIF1 and ATR function in the same epistatic pathway to regulate checkpoint responses in the diploid mitotic micronucleus and polyploid amitotic macronucleus