Szalicilsav által szabályozott védekező mechanizmusok vizsgálata gabonafélékben = Investigation of protective mechanisms controlled by salicylic acid in cereals

A pályázat célja az volt, hogy megvizsgáljuk az exogén szalicilsav (SA) hatását különböző abiotikus stresszek során, valamint hogy megvizsgáljuk hogyan alakul az endogén SA szint stresszkörülmények között gabonafélékben. Hidegstressz során nem volt különbség a kontroll és a SA kezelt növények membránlipidjeinek zsírsavösszetételében, míg a SA előkezelés megemelte a putreszcin és a spermidin szintjét, és ez is hozzájárul valószínűleg a SA védőhatásához. Szárazság stressz ellen a SA nemcsak, hogy nem nyújtott védelmet, hanem fokozta annak károsító hatását. Nehézfémstressznél (Cd) a SA kezelés hatására gyökérben jobban csökkent a fitokelatin szintáz enzim aktivitása, míg levélben megnőtt. Szárazság stressz során kukorica (Norma hibrid) mind a kötött, mind a szabad endogén SA szint lecsökkent gyökérben, míg levélben drasztikus stressz hatására megnőtt. NaCl kezelésnél a levélben a szabad SA szint kismértékben megnőtt, gyökérben nem változott, a kötött mind levélben, mind gyökérben lecsökkent. Cd stressz során gyökérben mind a szabad mind a kötött SA tartalom megnőtt. Az abszcizinsav kezelés normál hőmérsékleten nem befolyásolta az SA szintet, míg egy nap 5°C-os alacsony hőmérsékleti stressz során a szabad SA szint megnőtt, a kötött pedig lecsökkent, mind levélben, mind gyökérben. Ezek alapján megállapíthatjuk, hogy a szalicilsav szerepet játszik abiotikus stresszek során. | The aim of the project was to examine the effect of exogenous salicylic acid (SA) during various types of abiotic stress, and to determine how the endogenous SA level changed under stress conditions in cereals. During cold stress no difference was observed in the fatty acid composition of membrane lipids between control and SA-treated plants, while preliminary treatment with SA caused a rise in the levels of putrescine and spermidine, probably contributing to the protective effect of SA. Rather than providing protection against drought stress, SA made the damage more severe. In the case of heavy metal (Cd) pollution the phytochelatin synthase enzyme activity was further reduced by SA in the roots, but increased in the leaves. During drought stress there was a reduction in the level of both bound and free endogenous SA in the roots of maize (hybrid Norma), while it increased in response to drastic stress in the leaves. Treatment with NaCl caused a slight increase in the free SA level in the leaves, while no change was observed in the roots; the bound SA level declined in both leaves and roots. During Cd stress there was an increase in both free and bound SA content in the roots. At normal temperature abscisic acid treatment had no effect on the SA level, but after one day of low temperature stress (5°C) there was an increase in free SA and a drop in bound SA in both leaves and roots. It is thus clear that salicylic acid plays a role in the response to abiotic stress factors

Alacsony hőmérsékleti stressztolerancia és antioxidáns aktivitás közti kapcsolat vizsgálata gabonaféléknél = Investigation of the connection between tolerance to low temperature stress and antioxidant activity in cereals

A kutatási munka célja a gabonafélék stressztűrő képességének kialakításában szerepet játszó szabályozási folyamatok jobb megismerése volt, különös tekintettel a reaktív oxigénformák mennyiségének szabályozását végző antioxidáns rendszerekre. Több gazdasági növény, elsősorban kukorica és búza esetében jellemeztük az antioxidáns enzimrendszerek hozzájárulását abiotikus stresszfaktorok elleni védelemben. Kimutattuk, hogy a különböző gabonafajok eltérő stratégiákat dolgoztak ki a reaktív oxigénformák mennyiségének szabályozásához. Igazoltuk a fény szerepét a búza maximális fagyállóságának kialakulásában. Ehhez kapcsolódóan bemutattuk a ciklikus elektrontranszportlánc, egyes antioxidánsok, a szalicilsav-metabolizmus, valamint a membránlipidek alakulását eltérő fényviszonyok melletti alacsony hőmérsékleti edzés során. Eredményeink azt mutatják, hogy a szalicilsavfüggő jelátviteli utak szerepének tanulmányozásakor nemcsak magára a szalicilsavra, hanem egyes prekurzorainak a változásaira is figyelemmel kell lenni. Mindemellett bizonyítottuk, hogy intakt levelekben az egy elektronátmenetet megengedő fényfelvillanás általi gerjesztés egy összetett termolumineszcencia sávot eredményez, melynek magasabb hőmérsékleti (40 °C körüli) komponense egy AG-sáv. Jellemeztük az AG termolumineszcencia sávot, és bemutattuk alkalmazását gazdasági növények stressztűrő képességének vizsgálatában. | The research aimed to obtain a better insight into the regulatory processes involved in the development of stress tolerance in cereals, with special regard to antioxidant systems that regulate the quantity of reactive oxygen species (ROS). The contribution of antioxidant enzyme systems to defence against abiotic stress factors was investigated in several crops, particularly maize and wheat. Different cereal species were found to have elaborated diverse strategies for the regulation of ROS quantities. Light was proved to play a role in the achievement of maximum frost resistance in wheat. In this connection, changes occurring in the cyclic electron transport chain, in various antioxidants, in the salicylic acid metabolism and in membrane lipids during low temperature hardening were investigated under varying light conditions. It was found that when studying the role of salicylic acid-dependent signal transduction pathways it is important to consider not only salicylic acid itself, but also changes in its precursors. In addition it was demonstrated that in intact leaves a single turnover flash resulted in a complex thermoluminescence band, the high temperature (~ 40°C) component of which is an AG band. The latter was analysed, and its application in determining the stress tolerance of crops was discussed

Accommodation in phakic and pseudophakic eyes measured with subjective and objective methods

PURPOSE To measure accommodation subjectively and objectively and assess anterior segment changes during accommodation in phakic eyes and pseudophakic eyes. SETTING Department of Ophthalmology, Medical Health and Science Centre, University of Debrecen, Debrecen, Hungary. DESIGN Case series. METHODS Subjective and objective accommodation measurements and pupillometry were performed in phakic and pseudophakic patients. Refraction and pupil diameter were recorded with different accommodation stimuli. Corneal higher-order aberrations (HOAs) and anterior chamber depths (ACDs) were detected with a rotating Scheimpflug camera. RESULTS The mean age of the 44 patients in the phakic group was 36.34 years ± 16.6 (SD) and of the 27 patients in the pseudophakic group, 69.3 ± 9.98 years. The mean subjective accommodation was 4.49 ± 3.48 diopters (D) in phakic eyes and showed significant correlation with age, spherical aberration, changes in pupil diameter, and ACD. The mean subjective accommodation was 0.50 ± 0.28 D in pseudophakic eyes. In phakic eyes, the mean objective accommodation was 0.46 ± 1.02 D, 1.06 ± 1.33 D, and 2.2 ± 1.9 D with 2.0 D, 3.0 D, and 5.0 D, respectively, of stimulus. In pseudophakic eyes, measurable objective accommodation was recorded. In phakic eyes, the correlations were significant between these values and age, changes in ACD, pupil size, and corneal spherical aberration. In pseudophakic eyes, the only correlation was with the spherical equivalent value. CONCLUSIONS The magnitude of accommodation was greater with subjective measures than objective measures. In pseudophakic eyes, senile miosis and HOAs can be regarded as underlying factors in subjective accommodation; however, objective accommodation is not clinically significant. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned

Scanning-slit topography in patients with keratoconus

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Intraoperative and postoperative corneal thickness change after collagen crosslinking therapy.

PURPOSE To assess intraoperative and postoperative changes in corneal thickness subsequent to riboflavin-UVA (collagen crosslinking [CXL]) treatment. METHODS Forty-one eyes of 41 patients (mean age 27.97 ± 6.97 years) were treated with CXL technique. During treatment, isotonic riboflavin was instilled and corneal thickness measurements were obtained at the cornea apex, the thinnest point, and the pupil center at 15 and 30 minutes, then 3 days, 1 week, and 1, 3, 6, and 12 months after surgery using Pentacam HR and an ultrasound pachymeter. RESULTS A decrease in corneal thickness was detected 15 minutes intraoperatively with a value of 108.95 ± 48.6 µm, and 112.35 ± 47.3 µm at 30 minutes (p<0.001). Three days after the operation, no deviation was found from the initial values (p = 0.17). No further changes were detected during the follow-up period. CONCLUSIONS Isotonic riboflavin solution used during CXL treatment resulted in a significant decrease in corneal thickness, but its effect had disappeared by postoperative day 3

Examination of ocular biomechanics with a new Scheimpflug technology after corneal refractive surgery

PURPOSE To analyze the early results of a new device measuring ocular biomechanics after corneal refractive surgery. PATIENTS AND METHODS Thirty nine refractive surgery patients were enrolled in the study (age: 32.6±9.9 years). Laser in situ keratomileusis (LASIK) was performed on 52 eyes of 26 patients and photorefractive keratectomy (PRK) was done on 26 eyes of 13 patients. Ten device-specific biomechanical parameters, intraocular pressure (IOP) and pachymetry were measured preoperatively and at day 1, week 1 and month 1 after the surgeries with a new technology based on Scheimpflug imaging (CorVis ST, Oculus). RESULTS In case of LASIK, the day after the procedure, radius values showed significant differences compared to preoperative data. One month after surgery, radius values, velocity of the second applanation and pachymetry showed significant differences compared to preoperative data. In case of PRK, the day after the procedure, significant differences in IOP, maximum amplitude at the apex, A1 time, A2 velocity and highest concavity time were measured. After 1 month of PRK, there were no differences in the parameters compared to preoperative data except pachymetry. CONCLUSIONS We observed that some specific biomechanical parameters changed measured with CorVis ST after LASIK and PRK, in the early postoperative time. However, most of these parameters remain unchanged after one month of LASIK and PRK compared to preoperative data