Search

Increasingly, national space agencies are expanding their goals to include Mars exploration with sample return. To better protect Earth and its biosphere from potential extraterrestrial sources of contamination, as set forth in the Outer Space Treaty of 1967, international efforts to develop planetary protection measures strive to understand the danger of cross-contamination processes in Mars sample return missions. We aim to better understand the impact of the martian surface on microbial dormancy and survivability. Radiation resistance of microbes is a key parameter in considering survivability of microbes over geologic times on the frigid, arid surface of Mars that is bombarded by solar and galactic cosmic radiation. We tested the influence of desiccation and freezing on the ionizing radiation survival of six model microorganisms: vegetative cells of two bacteria (Deinococcus radiodurans, Escherichia coli) and a strain of budding yeast (Saccharomyces cerevisiae) and vegetative cells and endospores of three Bacillus bacteria (B. subtilis, B. megaterium, B. thuringiensis). Desiccation and freezing greatly increased radiation survival of vegetative polyploid microorganisms when applied separately, and when combined, desiccation and freezing increased radiation survival even more so. Thus, the radiation survival threshold of polyploid D. radiodurans cells can be extended from the already high value of 25 kGy in liquid culture to an astonishing 140 kGy when the cells are both desiccated and frozen. However, such synergistic radioprotective effects of desiccation and freezing were not observed in monogenomic or digenomic Bacillus cells and endospores, which are generally sterilized by 12 kGy. This difference is associated with a critical requirement for survivability under radiation, that is, repair of genome damage caused by radiation. Deinococcus radiodurans and S. cerevisiae accumulate similarly high levels of the Mn antioxidants that are required for extreme radiation resistance, as do endospores, though they greatly exceed spores in radioresistance because they contain multiple identical genome copies, which in D. radiodurans are joined by persistent Holliday junctions. We estimate ionizing radiation survival limits of polyploid DNA-based life-forms to be hundreds of millions of years of background radiation while buried in the martian subsurface. Our findings imply that forward contamination of Mars will essentially be permanent, and backward contamination is a possibility if life ever existed on Mars.

16S rRNA phylogenetic tree of the Deinococcus genus. The multiple alignment of 16S rRNA sequences was constructed using MUSCLE program [58] with default parameters. The maximum-likelihood phylogenetic tree was reconstructed using the PHYML program [18], with GTR substitution matrix, empirical base frequencies, and gamma-distributed site rates; support values were computed using the aBayes method. Truepera radiovictrix was chosen as an outgroup. D. ficus KS 0460 is marked in red, D. ficus DSM 19119 in green, completely sequenced genomes (according to GenBank) in purple. (PDF 416Â kb)

Despite concerted functional genomic efforts to understand the complex phenotype of ionizing radiation (IR) resistance, a genome sequence cannot predict whether a cell is IR-resistant or not. Instead, we report that absorption-display electron paramagnetic resonance (EPR) spectroscopy of nonirradiated cells is highly diagnostic of IR survival and repair efficiency of DNA double-strand breaks (DSBs) caused by exposure to gamma radiation across archaea, bacteria, and eukaryotes, including fungi and human cells. IR-resistant cells, which are efficient at DSB repair, contain a high cellular content of manganous ions (Mn2+) in high-symmetry (H) antioxidant complexes with small metabolites (e.g., orthophosphate, peptides), which exhibit narrow EPR signals (small zero-field splitting). In contrast, Mn2+ ions in IR-sensitive cells, which are inefficient at DSB repair, exist largely as low-symmetry (L) complexes with substantially broadened spectra seen with enzymes and strongly chelating ligands. The fraction of cellular Mn2+ present as H-complexes (H-Mn2+), as measured by EPR of live, nonirradiated Mn-replete cells, is now the strongest known gauge of biological IR resistance between and within organisms representing all three domains of life: Antioxidant H-Mn2+ complexes, not antioxidant enzymes (e.g., Mn superoxide dismutase), govern IR survival. As the pool of intracellular metabolites needed to form H-Mn2+ complexes depends on the nutritional status of the cell, we conclude that IR resistance is predominantly a metabolic phenomenon. In a cross-kingdom analysis, the vast differences in taxonomic classification, genome size, and radioresistance between cell types studied here support that IR resistance is not controlled by the repertoire of DNA repair and antioxidant enzymes.

Understanding chronic ionizing radiation (CIR) effects is crucial for predicting impacts of occupational exposures and radionuclide releases. Extrapolation of acute-radiation responses to CIR is unreliable. We investigated how cells resist/mitigate CIR by: (1) exposing bacteria (four Escherichia coli strains and Deinococcus radiodurans) and fungi (6 different species) to chronic g-radiation (0-180 Gy/h); (2) developing a mechanistically-motivated mathematical model to analyze these data. The most resistant organisms (D. radiodurans, E. coli CB1000, Trichosporon mucoides) proliferated at ≥67 Gy/h. Cell concentration strongly modulated the radioresistance of some bacteria. For example, the growth-inhibitory dose rate for D. radiodurans increased from 67 to >126 Gy/h, when the inoculum increased from 103 to ~108 cells/ml. Therefore, some radioresistant microbial cells cooperate to withstand CIR. Our model, based on the hypothesis that proliferation under CIR depends on ROS detoxification rate, provided an explanation for these data: At dose rates below a critical threshold, ROS concentrations remain low enough to allow proliferation. Above the threshold, cells cannot detoxify ROS quickly enough and proliferation is inhibited. We suggest that at high cell concentrations the threshold increases due to enhancement of extra-cellular ROS detoxification. These novel findings have potential implications for predicting/mitigating CIR impact on human cells., Journal of International Society of Antioxidants in Nutrition & Health, Vol 3, No 3 (2016)

Temeljna raziskava magistrskega dela je bila zagon vodenja projektov rasti in razvoja v srednje velikih podjetjih, izvedena na primeru podjetja Kovinoplastika Benda d.o.o. Najprej smo v teoretičnem delu predstavili pomen strategij in projektov v srednje velikih podjetjih ter delovanje projektnega managementa v teh podjetjih. V nadaljevanju smo podrobneje predstavili vrste projektov rasti in razvoja, programe projektov ter multiprojektno poslovanje v podjetjih. Ugotovili smo, da so za srednje velika podjetja projekti rasti in razvoja izjemnega pomena za zagotavljanje nadaljnje rasti in razvoja. V tem delu smo predstavili tudi proces zagona projektov ter dali poudarek predvsem na pretvorbo strategij v projekte in njihovo nadaljnjo izvedbo. V poglavju strateški razvoj podjetij smo opisali, kako poteka strateško načrtovanje v podjetjih, kakšne vrste strategij poznamo in kakšen pomen ima strateški management pri zagonu projektov rasti in razvoja v srednje velikih podjetjih. V nadaljevanju smo predstavili še povezavo projektov s strategijami, vrste ciljev in vhodne strategije projektov. Spoznali smo, da je v podjetjih ključna povezava strategij s projekti, saj lahko le iz jasno zastavljenih strategij nato izvedemo ustrezne projekte, ki bodo podjetju tudi v prihodnosti zagotavljali nadaljnjo rast in razvoj. Zadnje poglavje predstavlja empirični del magistrskega dela, kjer smo analizirali procese zagona projektov rasti in razvoja v podjetju Kovinoplastika Benda d.o.o. Najprej smo na kratko predstavili samo podjetje, nato pa predstavili aktualne projekte, ter podali predloge za zagotavljanje strateškega razvoja podjetja in predlog za reorganizacijo modela vodenja projektov v analiziranem podjetju. Spoznali smo, da podjetje trenutno nima izdelanega modela vodenja projektov in smo zato podali predloge, ki bi to problematiko v podjetju predvidoma izboljšali. Magistrsko delo smo zaključili s predlogi nadaljnjih projektov, ki bodo podjetju tudi v prihodnosti zagotavljali nadaljnjo rast in razvoj, poleg tega pa podali ugotovitve raziskave zastavljenega problema v podjetju. Fundamental research of master's thesis was the growth and development of start-up projects in medium-sized enterprises implemented in the case of Kovinoplastika Benda d.o.o. Firstly in the theoretical part, we presented the importance of strategies and projects for medium-sized businesses and how the project management works in these enterprises. Further, we presented the types of start-up projects, programs and multiple projects of enterprises. We had known that for medium-sized enterprises, the start-up projects are very important for the further development and growth of enterprises. In this work, we also presented the project start-up and conversion between strategies and projects, and their subsequent implementation. In chapter of strategic enterprise development, we had described how the strategic planning in enterprises works what kind of strategies we knows and the importance of strategic management in start-up projects in medium-sized enterprises. Further we presented link between projects and strategies, types of objectives and entry strategy projects. We have learned that a link between strategies and projects is crucial for the enterprises, because only from a clear set of strategies we can carried out relevant projects, which will ensure continued growth and development for the enterprises. The last chapter presents the empirical part of the master's work, where we analyzed the survey of start-up projects of the company Kovinoplastika Benda d.o.o. Firstly we spent a few words about the company and then presented current projects and presented proposals for ensuring the strategic development of the company and the proposal to reorganize the model of project management in the analyzed company. We have learned that the company currently doesn't have a model of project management, so we made our suggestions which would improve the problem in the company. This master's thesis is concluded with suggestions of further projects, which will ensure further growth and development for the company, and we also presented the findings of the research objective problem in the company.

Temeljna raziskava diplomskega seminarja je bila motivacija v podjetju. Najprej smo v teoretičnem delu predstavili kaj pomeni pojem motivacija ter kako jo razumejo in opisujejo različni avtorji. V tem delu smo tudi spoznali različne vrste motivov, ki smo jih razdelili na primarne in sekundarne ter jih bolje spoznali. V poglavju motivacijske teorije smo se podrobneje spoznali z različnimi motivacijskimi teorijami. Ugotovili smo, da se te delijo na vsebinske in procesne motivacijske teorije. Vsebinske proučujejo predvsem človeške potrebe ter motive, ki povzročajo določene oblike vedenja, procesne pa temeljijo na načinu, kako se neka sprememba v vedenju posameznika pojavi in kako pravzaprav pride do te oblike vedenja. V poglavju motivacijskih dejavnikov, smo opisali kako ti vplivajo na motivacijo zaposlenih v podjetju. Spoznali smo več različnih vrst motivacijskih dejavnikov, nekatere tudi podrobneje predstavili in hkrati spoznali, da se delijo na materialne in nematerialne. Nadaljnje smo predstavili tudi motivacijsko strukturo, njeno sestavo in pomen za podjetja. V zadnjem teoretičnem poglavju smo opisali probleme motiviranosti v podjetjih, ter z vidika različnih avtorjev (tudi s primeri dobre prakse) predlagali rešitve in izboljšave problema. Zadnje poglavje pa predstavlja empirični del tega dela diplomskega seminarja, kjer smo analizirali raziskavo o problemu motiviranosti v podjetju Kovinoplastika Benda d.o.o. Najprej smo predstavili podjetje, nato pa analizirali spoznane ugotovite iz vprašalnika, ki smo ga zastavili zaposlenim v obravnavanem podjetju. Spoznali smo, da ima podjetje izgrajen sistem motiviranja, ki pa ga bo moralo na nekaterih področjih malo izboljšati, saj si bo s tem zagotovilo še večje zadovoljstvo s strani zaposlenih. Delo diplomskega seminarja se zaključi z analiziranjem vprašanj, ki so se navezovala na zastavljene hipoteze, s sprejetjem oziroma zavrženjem le teh. Fundamental research of diploma seminar was motivation in the company. Firstly in the theoretical part, we presented what does the concept of motivation means and how is understand and described by the various authors. In this work we had also known different kinds of motives, and divided them into primary and secondary, and presented it more closely. In chapter of motivational theories we detail presented various motivational theories. We established that these theories are divided into content and process motivation theories. Content theories especially considering human needs and motives that cause certain forms of behavior, process theories are based on the way, how some change in the behavior of individuals appears and how actually do come to this type of behavior. In chapter of motivational factors, we examined how these factors affect the motivation of employees in a company. We had known several different types of motivational factors, some of them presented in details and at the same time realized that are divided into tangible and intangible. Further, we presented the motivational structure, its composition and the importance for businesses. In the last theoretical chapter, we described the theoretical motivation problems in companies and in a view of various authors (also with examples of good practice), suggested solutions and improvements of this problem. The final chapter presents the empirical part of this diploma seminar, where we described research on the problem of motivation in the company Kovinoplastika Benda d.o.o. Firstly we presented the company, and then analyzed to determine perceived from the questionnaire that we asked the employees of this company. We have learned that the company has built a system of motivation, but it will have to improve some areas as it will this provide even greater satisfaction by the employees. This diploma seminar is concluded by analyzing the issues that were related to the hypotheses, with the adoption or rejection thereof.