Acute cold exposure is a significant stressor activating heat production by shivering after the prolonged exposure cellular oxidative stress increases. Chronic exposure to cold lasting at least 2 weeks leads to the development of cold acclimatization. The main thermogenic role is taken over by non-shivering thermogenesis taking place in brown adipose tissue, which significantly increases its weight due to cold. Cardiac hypertrophy, hypertension and impaired renal function are frequently observed pathologies of acclimatization at 4-5 řC. Our laboratory recently introduced a model of mild chronic cold acclimatization at 8 řC, during which no damage to the heart or kidneys occurs and has proven cardioprotective effect on reducing infarct size. Hence, the influence of this cold acclimatization model on the other cellular and molecular processes needs to be investigated. The cardioprotective effect of cold acclimatization includes changes in β-AR signaling, activation of anti-apoptotic pathways or augmentation of the antioxidant system. The aim of this thesis was to investigate the effect of cold acclimation and subsequent reacclimation on proteins regulating Ca2+ levels in the rat heart (SERCA2 and phospholamban) and on the stimulation of regulatory proteins β-arrestin 1/2 and protein kinase PDPK1. The...

Recently, the cold resistance becomes a common topic in scientific articles. If we focus on order Heteroptera, we can find a lot of studies dealing with the cold resistance or with the supercooling point (SCP) and also with the factors that influence them. According to the general rule, the acclimation at low temperatures increases the cold resistance. Therefore, the main goal of this thesis is to find out, whether the acclimation also increases the cold resistance of the water cricket Velia caprai Tamanini, 1947 (Veliidae), with the intention to measure SCP of the water crickets depending on the acclimation temperature and the length of exposure. Due to the high mortality (the 284 individuals remained alive of total 1300) and due to the technical difficulties in measuring of SCP (measured only 36 individuals) it was necessary to modify the original goal of the thesis. The new goal was to test the influence of acclimation (during one month vs. one week) and the influence of different temperatures (0°C, 5°C, 10°C) on SCP of V. caprai. The individuals used for this measurement were collected during the year 2010 and in March 2011. The results of this thesis did not confirm the hypothesis that the acclimation at low temperatures increases the cold resistance. The individuals who were acclimated at a higher temperature have the values of SCP demonstrably lower than the individuals who were acclimated at low temperatures. The individuals who overwinter for the first time have arguably higher cold resistance than the individuals who overwinter for the second time. Probable cause of these results is the fact that the water cricket V. caprai does not start with diapause in the fall but it overwinters in quiescence.

We assessed influence of three acclimation regimes and influence of recovery after cold shock (exposure to 0°C for a period of time corresponding to Lt25) on the relative mRNA levels of selected stress proteins using qRT-PCR method. Larvae acclimated at 25°C showed relatively weak upregulation responses to cold shock. Much stronger responses were observed in the larvae that were cold-acclimated at 15°C or 15°C ? 6°C prior to cold shock. Two different general trends were distinguished in the response to cold acclimation and cold shock: (a) proteins from families SP70 and SP90 and splice variants c and d of the transcription factor HSF were upregulated in response to cold acclimation and the levels of their mRNA transcripts further increased after cold shock (for instance, the abundance of hsp70Aa mRNA increased up to 300-fold after cold shock (acclimation variant 15°C ? 6°C)); (b) four members of the small Hsp family (22, 23, 26 and 27 kDa) and splice variants a and b of the transcription factor HSF were down-regulated during cold acclimation (for instance, 10-fold in the case of hsp22) and the levels of their mRNA transcripts were either unchanged or increased only moderately after the cold shock. A third group of proteins, namely Hsc70, Hsp40 showed no or relatively small changes.

Diploma thesis’s aim was to determine Rubisco activity and its content in sunny and shaded needles of Norway spruce (Picea abies [L.] Karst.) and confirm or refuse acclimation on Rubisco enzyme level. Samples were taken on the Experimental ecology station Czech Academy of Sciences at Bílý Kříž (Beskydy Mountains) where needles were cultivated in two cultivation spheres with different concetrations CO2. One cultivation sphere contains atmosphere with ambient (A) concentration CO2 (350 mol CO2 mol-1) and the other contains atmosphere with elevated (E) concentration CO2 (700 mol CO2 mol-1). Rubisco activities were determinated spectrophotometric, Rubisco content was determined by SDS-PAGE method. Samples were taken in the modele of June and in the end of September. Elevated concetration CO2 did not have significant influence on Rubisco activity. Whereas different exposition had significant influence on Rubisco activity in June, when was found lower Rubisco activity in shaded needles than in sunny needles. In September were not find significant differences in Rubisco activity beetwen sunny and shaded needles. We did not find statistically significant differences in Rubisco content between A and E needles in June. Incontrary, we found about 34 % lower Rubisco content in E needles than in A needles, which confirms acclimation on Rubisco enzyme level. In September Rubisco content was several time higher than in June, which evidences the long term building photosynthetic apparatus in coniferous trees.

This diploma thesis examines influence of content of leaf nitrogen and non-structural carbohydrates on Rubisco activity and its content under impact of ambient (A = 385 µmolCO2 mol-1) and elevated (E = 700 µmolCO2 mol-1) concentrations of carbon dioxide in needles of Norway spruce (Picea abies L.). The Rubisco activity was determined spectrophotometrically, the Rubisco content by using SDS-PAGE, the content of non-structural carbohydrates by using the anthron method and total leaf nitrogen was determined by using the Kjeldahl method. The Rubisco activity in needles of Norway spruce did not show acclimation on elevated concentration of carbon dioxide, but the activity was elevated concentration of carbon dioxide stimulated during the growing season. The acclimation was proved by Rubisco content, its content was significantly lower in needles cultivated under elevated carbon dioxide. Content of total leaf nitrogen was statistically significantly lower in needles of Norway spruce cultivated under elevated carbon dioxide then in needles cultivated under ambient concentration of carbon dioxide. On the contrary, the content of non-structural carbohydrates was significantly higher in needles cultivated under elevated concentration of carbon dioxide then in variant A. Seasonal changes of Rubisco content depended on content of non-structural carbohydrates, the Rubisco content decreased with increasing content of non-structural carbohydrates. No dependence was detected between seasonal changes of the total leaf content and the Rubisco content.

Plants are exposed to the stress of the environment throughout their entire live. They therefore had to develop sophisticated mechanisms to avoid or tolerate stress. In some plants, repeated exposure to stress increases tolerance, which is known as stress memory. The aim of this study is to assess stress memory in terms of oxidative stress level. Content of malondialdehyde (MDA), reactive oxygen species (ROS) and the electrolyte leakage were chosen as markers of oxidative stress. Fresh weight, plant height and water content were also evaluated. The level of oxidative stress was assessed in several genotypes of Solanum tuberosum subspecies, Andigena and Tuberosum. In vitro culture did not work well for the evaluation of stress memory, ex vitro partially did. The content of MDA in 66B was significantly lower than in cv. Lada (Tuberosum) in root (in vitro) and shoot (ex vitro) in control groups as well as during water shortage. Treatment of acclimation-inducing cold before the stress-inducing cold had a variable effect on growth and electrolyte leakage according to the culture conditions. In vitro, the effect on electrolyte leakage in roots of cv. Lada was positive, in leaves of 66B (Andigena) it was negative. In ex vitro, a positive effect was found on electrolyte leakage in 66B leaves, but at the...

The constitutively obsereved up-regulation of Hsp70 expression often led to premature conclusions about its critical role as a repair mechanism of cold injury that is, besides, expressed by protein misfolding/denaturation. In this study, we analyze the cold tolerance and the expression of 24 different mRNA transcripts of Hsp complex and other genes, that are associated with the repair of injury caused by cold. We use two strains of D. melanogaster: the wild type and the mutant type Hsp70- null, that lacks all 6 copies of the gene hsp70. We found out, that the larvae of two strains do not differ in their patterns of target genes expression during long term acclimation nor during recovery from chronic cold exposure and acute cold shock, therefore there is no transcriptional compensation of any other Hsp gene for the missing hsp70 in Hsp70- strain. The cold tolerance of Hsp70- strain larvae was impaired only, when they were exposed to strong acute cold shock by temperatures below -8°C. No difference in cold tolerance was observed, when the larvae were exposed to chronic cold exposure in 0°C or to mild acute cold shock by temperatures up to -4°C. Based on our results we assess, that the cold injury caused by strong acute cold schock is of another nature than caused by mild cold conditions and only in the first case Hsp70 expression is critical for the repair of cold injury in Drosophila melanogaster larvae.

The effect of elevated CO2 concentration (EC CO2) on photosynthesis has been observed on many hierarchical levels. There was a significant increase in the rate of photosynthesis of examined trees observed in previous studies thus I hypothesised these changes are accompanied by changes of chloroplast ultrastructure and photosystem content and function and the main aim of this study is to evaluate these adjustments. In this study 13 - 14 years old seedlings of Norway spruce (Picea abies L. Karst.) grown in glass domes with adjustable windows - one with ambient CO2 concentration as a control, the other one with simulated EC CO2 (700 ppm) - during the vegetative season were examined. Pigment content, fluorescence and reflectance indexes, activity of photosystem 1 (PS1) and 2 (PS 2) of isolated chloroplasts, size of cross-sectional area of chloroplast and proportion of stromal to granal thylakoids under EC CO2 treatment were investigated. Although there was a significant increase in the maximum rate of photosynthetic assimilation of trees from EC CO2 (observed by other researchers of our team), decreased chlorophyll and carotenoid content as well as the activity of both photosystems were observed, which is usually atributed to photosynthetic acclimation. As the rate of decrease of photosystem 1 and photosystem 2...