Dominantna epistaza između dva lokusa kvantitativnog svojstva učinkovitosti sporulacije kvasca Saccharomyces cerevisiae

Sporulation efficiency in the yeast Saccharomyces cerevisiae is a well-established model for studying quantitative traits. A variety of genes and nucleotides causing different sporulation efficiencies in laboratory, as well as in wild strains, has already been extensively characterised (mainly by reciprocal hemizygosity analysis and nucleotide exchange methods). We applied a different strategy in order to analyze the variation in sporulation efficiency of laboratory yeast strains. Coupling classical quantitative genetic analysis with simulations of phenotypic distributions (a method we call phenotype modelling) enabled us to obtain a detailed picture of the quantitative trait loci (QTLs) relationships underlying the phenotypic variation of this trait. Using this approach, we were able to uncover a dominant epistatic inheritance of loci governing the phenotype. Moreover, a molecular analysis of known causative quantitative trait genes and nucleotides allowed for the detection of novel alleles, potentially responsible for the observed phenotypic variation. Based on the molecular data, we hypothesise that the observed dominant epistatic relationship could be caused by the interaction of multiple quantitative trait nucleotides distributed across a 60-kb QTL region located on chromosome XIV and the RME1 locus on chromosome VII. Furthermore, we propose a model of molecular pathways which possibly underlie the phenotypic variation of this trait.Učinkovitost sporulacije često se koristi za proučavanje kvantitativnih svojstava kvasca Saccharomyces cerevisiae. Velik broj gena i nukleotida koji utječu na učinkovitost sporulacije kvasca u laboratorijskim te divljim sojevima temeljito je okarakteriziran (uglavnom pomoću tehnike recipročne hemizigotnosti i ciljanom izmjenom nukleotida). U ovom smo radu primijenili drukčiju strategiju analize učinkovitosti sporulacije laboratorijskih sojeva kvasca. Povezivanjem klasičnih analiza kvantitativne genetike sa simulacijama fenotipskih distribucija (metoda modeliranja fenotipova) omogućena je detaljna analiza genetičkih odnosa između lokusa kvantitativnog svojstva učinkovitosti sporulacije. Na taj smo način otkrili dominantno epistatski odnos između dva lokusa koji pridonose učinkovitosti sporulacije. Štoviše, molekularna analiza poznatih gena i nukleotida što utječu na sporulaciju omogućila je pronalazak novih alela, koji su vjerojatno odgovorni za fenotipsku varijaciju. Pretpostavljamo da je dominantno epistatski način nasljeđivanja učinkovitosti sporulacije rezultat interakcije regije DNA na kromosomu XIV, duge 60 kb, te lokusa RME1 na kromosomu VII. Nadalje, predlažemo model pomoću kojeg se mogu opisati signalni putevi što reguliraju učinkovitost sporulacije

Preserved erythrocyte membranes produced from slaughterhouse blood as systems for prolonged delivery of active substances

У овој докторској дисертацији развијен је процес за изоловање говеђих и свињских еритроцитних мембрана („духова”) из отпадне кланичне крви. Поред тога, развијени су и детаљно in vitro окарактерисани системи за продужено ослобађање активних супстанци на бази добијених еритроцитних мембрана. У циљу пројектовања процеса којим би се добиле говеђе и свињске еритроцитне мембране које су структурно очуване, а пореклом из отпадне кланичне крви, дефинисане су специфичне осмотске карактеристике ових еритроцита. Показано је да су свињски еритроци осмотски осетљивији и да еритроцити ниједне од испитиваних врста нису осмотски хомогени. Ова хетерогеност је детектована између еритроцита различитих узорака исте врсте, али и еритроцита једног узорка. Као оптимални пуфер за извођење хемолизе говеђих и свињских еритроцита одређен је 35 mМ натријум фосфатни/NaCl пуфер чијом применом се у процесу градуалне хипотоничне хемолизе, при протоку пуфера од 300 ml/h, током 30 min, ослобађа >90% хемоглобина из велике запремине (100 ml) обе врсте еритроцита. Биохемијска анализа добијених мембрана еритроцита је показала да се садржај протеина и холестерола није битно разликовао у односу на мембране интактних еритроцита. Такође, пречник еритроцитних мембрана обе врсте био је за само 10% мањи од интактних еритроцита, а расподела величине униформна. Ови резултати су показали да духови кланичних еритроцита обе врсте животиња имају способност да „имитирају" хемијско и структурно анизотропно окружење ћелијских мембрана in vivo, што је од значаја за дифузију и партициони коефицијет активних супстанци при њиховој инкапсулацији. У следећој фази истраживања испитана је могућности примене процеса градуалне хипотоничне хемолизе за инкапсулацију модел супстанце, синтетског глукокортикоида и најшире коришћеног антиинфламаторног лека, дексаметазон-натријум-фосфата (DexP)...In this doctoral dissertation, а process for production of empty erythrocyte membranes („ghosts“) originating from bovine and porcine wasted slaughterhouse blood was developed. In addition, with an aim of designing prolonged drug delivery vehicles, ghost-based drug delivery systems were formulated and in vitro characterized. In order to design the process by which hemoglobin would be released from erythrocytes, leaving preserved cell membranes, the first step was to define specific osmotic properties of bovine and porcine erythrocytes derived from slaughterhouse blood. The results showed that porcine erythrocytes were more osmotically susceptible compared to bovine ones, but neither of the two examined types of erythrocytes was homogeneous regarding their osmotic properties. This heterogeneity was detected among erythrocytes from different samples of one species, as well as among erythrocytes in one sample. The hypotonic sodiumphosphate/ NaCl buffer of 35 mM concentration circulating with a flow rate of 300 ml/h during 30 min was optimal for conducting gradual hypotonic hemolysis. Under these conditions the process of gradual hemolysis resulted with a high hemolysis extent (>90%). Biochemical analysis revealed that protein and cholesterol content of isolated ghosts were nearly the same as in intact erythrocytes. Compared to starting erythrocytes, average diameter of the ghosts from both type of erythrocytes decreased for only 10%. These results indicate that isolated membranes have possibility to mimic the chemical and structural anisotropic environment of in vivo cell membranes, and this fact is of significance for drug diffusion and partition coefficients during encapsulation procedure. In the next step, the gradual hypotonic hemolysis was evaluated as an encapsulation procedure for a model drug into the ghosts which were obtained in the previous experimental stage. A synthetic glucocorticoid, widely used antiinflammatory drug, dexamethasone sodium phosphate (DexP), was selected as a model compound. The processing parameters of DexP encapsulation into the ghosts-temperature, initial drug concentration, and cross-linker addition- were optimized..

Tržišna moć korporacija i konkurencija u grani

U savremenim uslovima poslovanja koje karakteriše proces globalizacije tržišna moć korporacija sve više dobija na značaju. Tržišna moć je sposobnost korporacije ili više njih da u dužem roku na nekom tržištu profitabilno odrede cenu iznad graničnih troškova, odnosno konkurentne cene. Tako definisana tržišna moć utiče na konkurentske uslove poslovanja i zavisi od niza faktora među kojima se izdvaja relevantno tržište kao mesto gde se ova moć ispoljava. Pored dimenzija relevantnog tržišta, koje u sebi sadrži proizvodnu i geografsku komponentu, na veličinu tržišne moći a posledično i na uslove konkurencije u grani utiču i drugi faktori među kojima izdvajamo: ulazne barije, životni ciklus grane i horizontalna i vertikalna povezivanja korporacija. Tržišna moć i stepen ograničenosti tržišta se može izmeriti korišćenjem niza pokazatelja koncentracije i nejednakosti od kojih se pojedini često primenjuju u antimonopolskoj regulativi razvijenih zemlja (npr. Racio koncentracije i Herfindal-Hiršmanov indeks). Pokazatelji koncentracije i nejednakosti predstavljaju kvalitetnu osnovu za primenu odgovarajućih mera poboljšanja uslova konkurencije. Proizilazi da su referentne vrednosti ovih pokazatelja dobar instrument za analizu uslova konkurencije i primenu mera za njeno poboljšanje.In contemporary business environment, characterized by globalization, the market power of corporations is increasingly gaining in importance. Market power is the ability of a corporation or more of them to profitably set the price above marginal cost, i.e. competitive pricing, in a market in the long run. Thus defined market power affects the competitive business conditions and depends on many factors, among them the relevant market as a place where this power is manifested. Besides the size of the relevant market, which encompasses production and geographical component, the size of market power and consequently the conditions of competition in the industry are influenced by other factors, among which we highlight: barriers to entry, industry evolution, and horizontal and vertical integration of corporations. Market power and the degree of market limitation can be measured using a variety of indicators of concentration and inequality of which some are often used in anti-monopoly regulation of developed countries (e.g. concentration ratio and the Herfindahl-Hirschman Index). Indicators of concentration and inequality provide an adequate basis for the implementation of appropriate measures for improving the conditions of competition. It follows that the reference values of these indicators are a good instrument for analysing the conditions of competition and implementing measures for its improvement

Sorption of lead, cadmium and zinc ions from aqueous solutions onto natural and modified zeolite

Sorpcija se koristi za uklanjanje zagađujućih materija iz vode, zahvaljujući efikasnosti i ekonomičnosti, posebno ako se koriste jeftini sorbenti i ukoliko je moguća njihova višestepena regeneracija. Zeoliti zauzimaju značajno mesto među sorbentima za uklanjanje neorganskih jona iz prirodnih i otpadnih voda. Da bi se sorpcioni kapacitet prirodnih zeolita za jone metala povećao i proces sorpcije unapredio, poslednjih godina se proučavaju različiti postupci modifikovanja zeolita. Jedan od efikasnih postupaka modifikacije je nanošenje na površinu zeolita gvožđe(III)-oksihidroksida, koji su takođe aktivni sorbenti i igraju značajnu ulogu u imobilizaciji jona u prirodi. U ovoj doktorskoj disertaciji je proučavana sorpcija jona olova, kadmijuma i cinka iz jednokomponentnih i višekomponentnih rastvora u dejonizovanoj i komunalnoj otpadnoj vodi, na prirodnom zeolitu i zeolitu koji je modifikovan gvožđe(III)-oksihidroksidima. Cilj disertacije je bio objašnjenje razlike u mehanizmima sorpcije i sorpcionim kapacitetima prirodnog i modifikovanog zeolita. Karakterizacija prirodnog i modifikovanog zeolita pokazala je da nije došlo do narušavanja strukture zeolita i da se modifikacija odigrala na površini, obrazovanjem klastera amorfnog gvožđe(III)-oksihidroksida. Adsorpcijom azota na temperaturi tečnog azota utvrđeno je da je modifikacija uzrokovala značajno povećanje specifične površine i zapremine mezopora, kao i zatvaranje mikropora. Specifična površina oba zeolita je određena i na osnovu adsorpcionih izotermi za n-heksan, benzen, hloroform i tetrahidrofuran primenom inverzne gasne hromatografije u uslovima konačne prekrivenosti na temperaturi od 240 °C. Niže vrednosti specifične površine dobijene inverznom gasnom hromatografijom za modifikovani zeolit u odnosu na vrednost dobijenu na osnovu adsorpcije azota ukazuju na prisustvo mezopora manjih dimenzija, manjih nego u slučaju prirodnog zeolita, koje su dostupne molekulima azota, a nisu molekulima n-heksana, benzena, hloroforma i tetrahidrofurana, koji su većih dimenzija u odnosu na N2...Sorption is used to remove pollutants from water, thanks to its efficiency and cost effectiveness, especially if cheap sorbents are used and if there is a possibility for their multistage regeneration. Zeolites occupy an important place among the sorbents for removal of inorganic ions from natural and waste waters. In order to increase the sorption capacity of natural zeolites for metal ions, and to improve the sorption process, various methods for modifying zeolites have been studied in recent years. One of the most effective methods is a modification of the surface of the zeolite with iron(III)–oxyhydroxides, which are also active sorbents and play a important role in the immobilization of ions in nature. This doctoral thesis investigates sorption of lead, cadmium and zinc ions from multicomponent solutions in deionized and municipal waste water, onto natural zeolite and zeolite modified with iron(III)-oxyhydroxides. The goal of the thesis was the explanation of differences in the sorption mechanisms and sorption capacity of natural and modified zeolites. Characterization of natural and modified zeolites showed that no damage to the zeolite structure was done and that the modification occurred on the surface, forming clusters of amorphous iron(III)-oxyhydroxides. Nitrogen adsorption at liquid nitrogen temperature determined that the modification caused a significant increase in specific surface area and volume of mesopores and micropores closing. The specific surface area of natural and modified zeolite was also determined based on the adsorption isotherms of n-hexane, benzene, chloroform and tetrahydrofuran by inverse gas chromatography at finite concentration condition at a temperature of 240 °C. Lower values of specific surface area obtained by inverse gas chromatography for the modified zeolite, compared to the value obtained by nitrogen adsorption, indicate the presence of mesopores with smaller dimensions, smaller than in the case of natural zeolite. These pores are available for nitrogen molecule, and they are not available for the molecules of n-hexane, benzene, chloroform and tetrahydrofuran, which are large in size in comparison to N..

Polyphenol content and antioxidant activity of sour cherries from Serbia

The aim of this study is to evaluate the content of phenolics: the total phenols (TP), flavonoids (TF), anthocyanins (TA), as well as the total antioxidant capacity (TAC) in three sour cherry cultivars (Prunus cerasus L.) introduced to the southeast Serbia climate conditions. Among the researched sour cherries, ‘Oblacinska’ cultivar contained the highest amounts of all groups of phenolics, followed by ‘Cigancica’ > ‘Marela’. A significant difference were observed in the phenolic content among different cultivars and growing seasons (p<0.05), and the phenolic compounds were significantly higher in the growing season 2009. The examined cultivars possess a high antioxidant capacity, and all phenolics of highy correlation with TAC. The following compounds were identified and quantified using HPLC-DAD: 4 anthocyanins, the most abundant of which was cyaniding-3-glucoside in ‘Marela’ and ‘Oblacinska’, and cyanidin-3-glucosylrutinoside in ‘Cigancica’, and 4 hydroxycinnamic acids, the most abundant of which was neochlorogenic acid in all sour cherry cultivars. The growing and ripening process on the tree of sour cherry cv. Oblacinska was evaluated, also. The results showed significant increases in total phenols during the ripening, the total anthocyanins and total antioxidant capacity and 4 quantified anthocyanins, however the neochlorogenic acid decreased during the ripening. The study indicated that the growing and climate conditions in southeast Serbia are convenient for introducing sour cherry cultivars

Detailed investigation of the superconducting transition of niobium disks exhibiting the paramagnetic Meissner effect

The superconducting transition region in a Nb disk showing the paramagnetic Meissner effect (PME) has been investigated in detail. From the field-cooled magnetization behavior, two well-defined temperatures can be associated with the appearance of the PME: T_1 (< T_c) indicates the characteristic temperature where the paramagnetic moment first appears and a lower temperature T_p (< T_1) defines the temperature where the positive moment no longer increases. During the subsequent warming, the paramagnetic moment begins to decrease at T_p and then vanishes at T_1 with the magnitude of the magnetization change between these two temperatures being nearly the same as that during cooling. This indicates that the nature of the PME is reversible and not associated with flux motion. Furthermore, the appearance of this paramagnetic moment is even observable in fields as large as 0.2 T even though the magnetization does not remain positive to the lowest temperatures. Magnetic hysteresis loops in the temperature range between T_1 and T_p also exhibit a distinct shape that is different from the archetypal shape of a bulk type-II superconductor. These behaviors are discussed in terms of the so-called 'giant vortex state'.Comment: Total 4 printed pages, 4 Figure