Selenium and its effects on growth, yield and tuber quality in potato

Selenium (Se) has been demonstrated to be an essential trace element for maintenance of animal and human health. Although it has not been confirmed to be an essential micronutrient in higher plants, there is increasing evidence that Se functions as an antioxidant in plants. Selenium has been shown to exert a beneficial effect on crop growth and promotes stress tolerance at low concentrations. However, the specific physiological mechanisms that underlie the positive effects of Se in plants have not been clearly elucidated. The aims of this study were to determine the Se concentration in potato (Solanum tuberosum L.) and the effects of Se on the accumulation of carbohydrates, growth and yield in potato plants. An additional aim was to study the impact of Se on the total glycoalkaloid concentration in immature potato tubers. The distribution of Se in different biochemical Se fractions and the effect of storage on the Se concentration were studied in Se-enriched tubers. Furthermore, the effect of Se on raw darkening and translocation of Se from seed tubers to the next tuber generation was investigated. Due to the established anti-ageing properties of Se, it was of interest to study if Se affects physiological age and growth vigour of seed tubers. The Se concentrations in the upper leaves, roots, stolons and tubers of potato increased with increasing Se supplementation. The highest Se concentration was reached in young upper leaves, roots and stolons, indicating that added selenate was efficiently utilized and taken up at an early stage. During the growing period the Se concentration declined in the aerial parts, roots and stolons of potato plants whereas an intensive accumulation took place in immature and mature tubers. Selenium increased carbohydrate accumulation in the young upper leaves and in stolons, roots and tubers at maturity. This could not be explained by increased production of photoassimilates as net photosynthesis did not differ among Se treatments. The Se treated plants produced higher tuber yields than control plants, and at the highest Se concentration (0.3 mg kg-1) lower numbers of larger tubers were harvested. Increased yield of Se treated plants suggested that Se may enhance the allocation of photoassimilates for tuber growth, acting as a strong sink for both Se and for carbohydrates. Similarly as for other plant species, the positive impact of Se on the yield of potato plants could be related to its antioxidative effect in delaying senescence. The highest Se supplementation (0.9 mg kg-1) slightly decreased the glycoalkaloid concentration of immature tubers. However, at this level the Se concentration in tubers was about 20 µg g-1 DW. A 100 g consumption of potato would provide about 500 mg of Se, which exceeds the upper safe intake level of 400 µg per day for human dietary. The low Se applications (0.0035 and 0.1 mg kg-1) diminished and retarded the degree of raw darkening in tubers stored for one and eight months, which can be attributed to the antioxidative properties of Se. The storage for 1 to 12 months did not affect the Se concentrations of tubers. In the Se enriched tubers Se was allocated to the organic Se fraction, indicating that it was incorporated into organic compounds in tubers. Elevated Se concentration in the next-generation tubers produced by the Se enriched seed tubers indicated that Se could be translocated from the seed tubers to the progeny. In the seed tubers stored for 8 months, at high levels, Se had some positive effects on the growth vigour of sprouts, but Se had no consistent effect on the growth vigour of seed tubers of optimal physiological age. These results indicate that Se is a beneficial trace element in potato plants that exerts a positive effect on yield formation and improves the processing and storage quality of table potato tubers. These positive effects of Se are, however, dependent on the Se concentration and the age of the potato plant and tuber.

Characterization of non-imaging semiconductor X-ray solar monitors

The first observations of solar X-rays date back to late 1940 s. In order to observe solar X-rays the instruments have to be lifted above the Earth s atmosphere, since all high energy radiation from the space is almost totally attenuated by it. This is a good thing for all living creatures, but bad for X-ray astronomers. Detectors observing X-ray emission from space must be placed on-board satellites, which makes this particular discipline of astronomy technologically and operationally demanding, as well as very expensive. In this thesis, I have focused on detectors dedicated to observing solar X-rays in the energy range 1-20 keV. The purpose of these detectors was to measure solar X-rays simultaneously with another X-ray spectrometer measuring fluorescence X-ray emission from the Moon surface. The X-ray fluorescence emission is induced by the primary solar X-rays. If the elemental abundances on the Moon were to be determined with fluorescence analysis methods, the shape and intensity of the simultaneous solar X-ray spectrum must be known. The aim of this thesis is to describe the characterization and operation of our X-ray instruments on-board two Moon missions, SMART-1 and Chandrayaan-1. Also the independent solar science performance of these two almost similar X-ray spectrometers is described. These detectors have the following two features in common. Firstly, the primary detection element is made of a single crystal silicon diode. Secondly, the field of view is circular and very large. The data obtained from these detectors are spectra with a 16 second time resolution. Before launching an instrument into space, its performance must be characterized by ground calibrations. The basic operation of these detectors and their ground calibrations are described in detail. Two C-flares are analyzed as examples for introducing the spectral fitting process. The first flare analysis shows the fit of a single spectrum of the C1-flare obtained during the peak phase. The other analysis example shows how to derive the time evolution of fluxes, emission measures (EM) and temperatures through the whole single C4 flare with the time resolution of 16 s. The preparatory data analysis procedures are also introduced in detail. These are required in spectral fittings of the data. A new solar monitor design equipped with a concentrator optics and a moderate size of field of view is also introduced.

Kolmas tehtävä ja neljäs valtiomahti. Uusi yliopistolaki ja yliopiston rooli yhteiskunnassa julkisen keskustelun kohteena 2008-2009.

Tässä pro gradu -tutkielmassa tarkastellaan yliopiston yhteiskunnallista vuorovaikutusta koskevaa julkista keskustelua. Aineisto koostuu viiden levikiltään Suomen suurimpien joukkoon kuuluvan sanomalehden yliopiston yhteiskunnallista vuorovaikutusta käsittelevistä pääkirjoituksista ajalta 1.1.2008–31.12.2009. Pääkirjoituksia on aineistossa yhteensä 110. Tutkielman tarkoituksena on täydentää politiikan tutkimuksen alalla laiminlyötyä koulutuspolitiikan tutkimusta paneutuen yliopiston yhteiskunnallista roolia koskeviin merkityksiin, jotka nousivat aktiiviseen julkiseen keskusteluun yliopistolain uudistuksen myötä. Tutkimuskysymyksenä on, minkälaisia representaatioita yliopiston roolista yhteiskunnassa suomalaiset sanomalehdet välittivät pääkirjoituksissaan uuden yliopistolain säätämistä edeltäneessä uutisoinnissaan? Tutkielmassa eritellään pääkirjoituksista löytyviä yliopiston yhteiskunnallista roolia koskevia merkitysjärjestelmiä eli diskursseja käyttäen menetelmänä Teun van Dijkin diskurssianalyysia. Yliopiston roolia koskevia representaatioita tarkastellaan Jürgen Habermasin tiedon intressien teoriaan peilaten. Muita keskeisiä teoreetikkoja ovat Gerard Delanty, Henry Etzkowitz, Helga Nowotny, Jean-Francois Lyotard, Andy Green ja Marek Kwiek. Yliopiston kolmannen tehtävän korostumista pohjustetaan historiallisella kuvauksella modernin yliopiston synnystä ja yliopistoinstituution kehityksestä Euroopassa ja tarkemmin Suomessa. Työssä käydään myös läpi tutkimusta, joka pureutuu kansallisvaltion ja yliopistoinstituution historiallisen siteen purkautumiseen ja yliopiston toiminnan legitimiteetin uudelleenmäärittelyyn. Lisäksi nostetaan esiin näkemyksiä tiedon tuotannon monopolin irtautumisesta yliopistolta yhä suuremmalle joukolle toimijoita. Analyysia taustoitetaan myös uuden yliopistolain ja sen taustalla olleen ylikansallisen koulutuspolitiikan konsensuksen kautta. Pääkirjoituksissa esiintyneitä yliopiston yhteiskunnallisen roolin saamia merkityksiä tarkastellaan ensin lehtikohtaisesti, minkä jälkeen pääkirjoitusten sisältämistä representaatioista muodostetaan diskursseja. Aineistosta muodostui viisi diskurssia: globaalin selviämistaistelun diskurssi, lokaalin identiteetin diskurssi, maineenrakennuksen diskurssi, panos-tuotos-diskurssi ja myyttisen humboldtilaisuuden diskurssi. Yliopisto representoitiin alueellisen identiteetinrakennuksen ja integraation välineenä ja sellaiseksi alueen integraation välineeksi, jolle valtio on prosessin laidalla oleva tukiverkko. Alueen integraation välineeksi representoitu yliopisto esitettiin samalla globaalille huipulle tähtäämisen myötä legitimoituvaksi instituutioksi. Yliopisto representoitiin siis glokaalin huipulle nousun välineenä. Pääkirjoituksissa epäpolitisoitiin yliopiston ja alueen välinen yhteys sekä yliopiston ja elinkeinoelämän välinen yhteys. Globaalin selviämistaistelun ja myyttisen humboldtilaisuuden välinen merkityskamppailu kulki läpi aineiston. Yliopisto representoitiin teknisen tiedon intressin mukaisesti välineeksi globaalin kilpailukyvyn nostamiseksi. Toisaalta yliopisto esitettiin myös myyttisen humboldtilaiseksi puhdasta tutkimusta tekeväksi ympäröivästä yhteiskunnasta eristäytyneeksi instituutioksi. Aineistossa ei representoitu yliopistoa emansipatorista tiedon intressiä toteuttavana instituutiona vaihtoehtona teknisen tiedon intressin mukaisille representaatioille. Myöskään kommunikatiivisen tiedon intressin mukainen yliopisto ei tullut aineistossa esiin. Aineistossa annettiin vastoin tutkimuskirjallisuuden näkemyksiä yliopistolle legitiimin tiedon monopolin haltijan rooli. Pääkirjoituksissa representoitiin valtiovallan, yksityisen sektorin ja tiedeyhteisön yliopistoa koskevia intressejä. Kansalaisyhteiskunnan ja yliopiston välistä vuorovaikutusta aineisto ei nostanut esiin. Keskeisimmäksi jatkotutkimuksen aiheeksi identifioitiin tämän myötä yliopiston ja kansalaisyhteiskunnan toimijoiden välisen vuorovaikutuksen tarkastelu.

Inhibitory effects of wood extracts on the spoilage flora of marinated poultry meat

Polyphenolic compounds occurring naturally in knotwood of plants are known to have antimicrobial effects. The knots (i.e. the branch bases inside tree stems) and outer branches in pine trees contain a remarkably high concentration of phenolic stilbenes, while lignans are the major phenolic constituents of spruce knots. Large amount of these phenolic compounds can be extracted from wood knots at pulp and paper mills where their presence is undesirable. In Finland, marinating of broiler meat is done not only to increase or add value to the meat, but also to enhance the safety and shelf-life. These products are usually packed under a modified atmosphere for further protection against spoilage microorganisms. However, studies have revealed that addition of marinades to poultry products do not have an inhibitory effect on either some psychrotrophic anaerobic bacteria, such as Brochothrix thermosphacta or lactic acid bacteria associated with spoilage. Also, the activity of pathogenic Campylobacter jejuni is not affected by marinating. The objective of this study was to investigate the inhibitory and lethal activities of extracts from spruce (Picea spp.) and pine (Pinus spp.) knotwood and outer branches that are dissolved in ethanol against the spoilage microorganisms in modified atmosphere packaged marinated broiler products. Modified atmosphere packaged broiler products were separately inoculated with ‘normal’ marinades, marinades with 70% ethanol, marinades with a mixture of spruce and pine extracts dissolved in 70% ethanol or mixture of spruce and pine extracts in powder form. The bacterial colony forming units per gram obtained from each of the samples were analysed on de Man Rogosa and Sharpe agar at days 1, 6, 12 and 15. The results showed that there were significant differences in bacterial colony forming units per gram (P <0.05) between packages with ‘normal’ marinades and packages with extracts added to their marinades on the 12th and 15th day. It can be concluded that the addition of extracts from spruce and pine knotwood to marinades significantly retarded growth of spoilage microorganisms during the 15 day test period. However further research is warranted to characterise and establish the safety and suitability of the compound(s) in spruce and pine knotwood extracts that are responsible for inhibitory or lethal activity against the microbes that may be present in marinated poultry meat.