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2992. Dual role of superoxide radicals in the chilling-induced photoinhibition in maize seedlings

Creator:
Ke, D., Sun, G., and Jiang, Y.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, net photosynthetic rate, photosystem 2, reactive oxygen species, SOD, violaxanthin, xanthophyll cycle, Zea, and zeaxanthin
Language:
Multiple languages
Description:
Maize (Zea mays) seedlings were exposed for 6 h to strong irradiance (1 000 μmol m-1 s-1 of PPFD) at 5, 12, 17, or 25 °C, followed by an exposure to the darkness for 6 h at 22 °C. Leaf chlorophyll fluorescence, net photosynthetic rate (PN), and the amount of superoxide radicals (O2-⋅) in relation to chilling-induced photoinhibition were investigated. During the photophase, a good correlation (r=-0.879) was observed between ΦPS2 (relative quantum efficiency of PS2 electron transport) and the amount of O2-⋅. Treatment with exogenous O2-⋅ reduced the PN and ΦPS2 as the chilling stress did, that was inhibited by specific scavenger of O2-⋅. Hence chilling-induced photoinhibition might be due to the production of O2-⋅. In contrast, in the dark period, PN and ΦPS2 of the seedlings treated with the exogenous O2-⋅ were enhanced, but they were inhibited by the specific scavenger of O2-⋅, showing the photoprotective role of O2-⋅ in the recovery phase. Furthermore, in terms of the effect of exogenous O2-⋅ on the xanthophyll cycle, the O2-⋅ production suggested a promotion effect for the de-epoxidation of violaxanthin during the photophase, the epoxidation of zeaxanthin at the dark stage, and the increase of the xanthophyll pool both in the photophase and dark phase, resulting in an enhancement of the ability of non-photochemical quenching to avoid or alleviate the damage to photosynthetic apparatus. and D. Ke, G. Sun, Y. Jiang.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2993. Dual role of thyroid hormones in rat soleus muscle MyHC isoform expression

Creator:
Vadászová-Soukup, A. and Tomáš Soukup
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie, hormony štítné žlázy, potkan, physiology, thyroid hormones, Rattus norvegicus, soleus muscle, myosin heavy chains, SDS-PAGE, RT-PCR, 14, and 612
Language:
English
Description:
We have analyzed the influence of altered thyroid hormone levels on changes of MyHC protein isoforms and their mRNA transcripts in the soleus muscle of 2-, 4- and 7-month-old euthyroid (EU), hypothyroid (HY) and hyperthyroid (TH) female inbred Lewis strain rats (methimazole and T3 treatment started 3 to 4 weeks after birth). We have found that the content of the dominant MyHC 1 isoform gradually increased in the EU rats and that this increase was more progressive in the HY rats at all three stages. On the other hand, in the TH rats the content of MyHC 1 isoform was the highest in the 2-month-old rats and it decreased with an increasing length of T3 treatment. The content of the minor 2a MyHC isoform followed the opposite pattern. In contrast to the protein isoforms, the MyHC mRNA transcripts remained at similar levels. Nevertheless, in general, the MyHC 1 mRNA level was decreased and MyHC 2a transcript increased in the TH rats, while the opposite changes occurred in the HY rats. Our results thus suggest that in the rat soleus muscle, both increased and decreased levels of thyroid hormones speed up the formation of an adult slow phenotype which is demonstrated by the precocious appearance of the slow MyHC 1 isoform, but opposite to the hypothyroid status, a longer T3 application promotes the expression of the faster MyHC 2a isoform., A. Vadászová-Soukup, T. Soukup., and Obsahuje bibliografii a bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2994. Duchovní hudba - Hudba slovanské vzájemnosti - Hudba po roce 1989

Creator:
Jarmila Gabrielová and Jana Vozková
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Česká společnost pro hudební vědu, muzikologie, musicology, hudební konference, conferences on music, hudební společnosti, music societies, 78.01, 78:005.745, 78:061.2, and (046)
Language:
Czech
Description:
Zpráva o výroční konferenci České společnosti pro hudební vědu, uskutečněné v Praze 29. - 30. listopadu 2013., Jarmila Gabrielová, Jana Vozková., Rubrika: Konference, and Cizojazyčné resumé není.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2995. Důkaz konvekce jako dominantního jevu tání kostek ledu

Creator:
Vochozka, Vladimír and Wegenkittlová, Pavla
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
konvekce, pokusy, convection, experiments, 6, and 53
Language:
Czech and English
Description:
Školní pokus dokazující proudění kapalin s kostkami ledu je možné dohledat v mnoha učebnicích. Pomůcky a průběh experimentu se různě liší. Cílem je dokázat proudění v kapalině v závislosti na rozdílné hustotě způsobené odlišnou teplotou. Pomocí termokamery je možné pozorovat rozložení teploty povrchu nádoby před vložením kostek ledu, v průběhu tání kostek a na konci tání. V textu příspěvku je naznačen možný postup řešení a analýza výsledků., A school experiment proving the flow of liquids, with the help of ice cubes, can be found in many textbooks. The tools and course of the experiment differ in different ways. The aim is to prove that the flow in a liquid depends on its variable density caused by different temperatures. Using a thermal imaging camera, it is possible to observe the temperature distribution of a vessel’s surface before inserting ice cubes, during melting and at the end of melting. In this article we suggest a possible solution and give an analysis of the results., Vladimír Vochozka, Pavla Wegenkittlová., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2996. Důkaz molekulární kondenzace?

Creator:
Cartlidge, Edwin and Cejnarová, Andrea
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fyzika, molekulární kondenzace, physics, and molecular condensation
Language:
Czech
Description:
Výzkumníci ze Spojených států amerických tvrdí, že vytvořili molekulární Boseho-Einsteinův kondenzát, což je stav hmoty, ve kterém velký počet molekul koexistuje ve stejném kvantovém stavu. Elizabeth Donleyová a její kolegové z laboratoře JILA v Boulderu oznámili, že pozorovali koherentní oscilace mezi atomy a molekulami ve vzorku rubidia 85. Tento objev by mohl mít významné důsledky pro molekulární fyziku, chemii a kvantové počítání (E. Donley a kol., Nature 417, 529 (2002)). and Edwin Cartlidge ; přeložila Andrea Cejnarová. Přeloženo z Physicsweb: http:/www.physicsweb.org/
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2997. Durability assessment of soft clay soil stabilized with halloysite nanotubes

Creator:
Tavakolipour, Masoud and Salemi, Niloofar
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
půdy, soils, soil stabilization, Halloysite nanotubes, unconfined compressive strength, wet/dry durability, freeze/thaw durability, 7, and 551
Language:
English
Description:
In this study the compressive strength and durability of soft clay soil stabilized with halloysite nanotubes are investigated. Halloysite nanotubes are novel 1D natural nanomaterials which are widely used in reinforcing polymer, pollution remediation, and as nanoreactors for biocatalyst. The wide use of halloysite nanotubes is due to their high aspect ratio, appropriate mechanical strength, high thermal stability, nature-friendly and cost-effectiveness. However, the use of halloysite nanotubes as a stabilizing agent for improving the durability of soil is not clear. In this research, halloysite nanotubes was used in the amounts of 2%, 5% and 10% by the weight of dried soil. Unconfined compressive strength, wet/dry cycles and freeze/thaw cycles tests were performed to evaluate the strength and durability of stabilized soft clay soil. Experimental results showed that halloysite nanotubes considerably improves the compressive strength and durability of soft clay soil. The optimum amount of halloysite nanotubes for soil stabilizing in terms of compressive strength and durability was 5%. The compressive strength of soft clay increased as much as 129% by applying 5% halloysite nanotubes. Also, the specimen containing 5% halloysite nanotubes showed the least strength loss after wet/dry and freeze/thaw cycles. The soil sample containing 5% halloysite nanotubes lost 20% of its initial compressive strength after 8 cycles of freezing and thawing, while the soil sample without any halloysite content lost 100% of its compressive strength after the same number of freezing and thawing. Based on the obtained results, the use of halloysite nanotubes in order to enhance the strength and durability of soft clay is strongly recommended., Tavakolipour Masoud, Salemi Niloofar., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2998. Duration of irradiation rather than quantity and frequency of high irradiance inhibits photosynthetic processes in the lichen Lasallia pustulata

Creator:
Barták, M., Vráblíková-Cempírková, H., Štepigová, J., Hájek, J., Váczi, P., and Večeřová, K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, non-photochemical quenching, photoinhibition, photochemical quenching, xanthophyll cycle, and zeaxanthin
Language:
Multiple languages
Description:
Lichen thalli were exposed to 4 regimes differing in irradiance and duration of irradiation. Photosynthetic efficiency of thalli was monitored by chlorophyll fluorescence parameters and xanthophyll cycle analysis. Maximal quantum yield of photosystem 2 (FV/FM) decreased gradually with time in long-term treatment. The effect of additional short-term high irradiance (HI) treatment applied each 24 h was not significant. Nevertheless, short-term HI applied repeatedly on thalli kept in the dark led to a significant decrease of FV/FM. Non-photochemical quenching recorded during the long-term treatment corresponded to the content of zeaxanthin (Z). In short-term treatment, however, proportion of Z (and antheraxanthin) to total amount of xanthophyll cycle pigments recovered to the initial values every 24 h after each repeated short-term HI event in thalli kept in dark. Thus duration of irradiation rather than irradiance and frequency of HI events is important for a decrease in primary photosynthetic processes in wet thalli of Lasallia pustulata. Rapidly responding photoprotective mechanisms, such as conversion of xanthophyll cycle pigments, are involved mainly in short-term irradiation events, even at HI. and M. Barták ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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