Annual water temperature courses in two contrasting lakes at James Ross Island, Antarctica (Short Communication)

In this Short Communication, long-term temperature courses of two contrasting Antarctic lakes are presented. The lakes differed in their different location, size, and origin. Big Lachman Lake is a typical coastal shallow lake located on a terrace at an altitude of about 9 m. Dulánek Lake is a small-area, shallow kettle lake located in the lateral moraine composed of the back-arc alkaline volcanic rocks of the James Ross Island Volcanic Group at the height of about 220 m a.s.l. The data presented in this study support an idea that the water courses differed between the two lakes due to altitude and local microclimate. Similarly, significant differences in annual and summer-season courses of water temperature were apparent when several consecutive seasons were compared. Such differences have consequences for water invertebrates and autotrophic organisms because of episodic drying out of some lakes and/or formation of long-term lasting ice

Responses of primary photosynthetic processes to repetitive rehydration differ in two representatives of Svalbard moss flora

Global warming in polar regions brings a risk of more frequent and long-lasting dry periods due to warmer and windier climate during polar summers. Mosses are well adapted to desiccation-rehydration events and they have evolved remarkable constitutive and inducible mechanisms of desiccation tolerance. In our study, Sanionia uncinata and Racomitrium lanuginosum were collected in Svalbard and used for laboratory-based repetitive 32-h-lasting rehydration cycles with continuous monitoring of restoration of their primary photosynthetic processes measured by chlorophyll fluorescence parameters. Immediately after the addition of water to dry thalli, potential quantum yield of PSII (FV/FM) was about 50% of its maximum reached after 32 h of rehydration. In a course of time of rehydration, both species showed an increase in FV/FM and effective quantum yield (FPSII) following a S-curve relationship. Non-photochemical quenching did not show clear trend with the rehydration time, It differed between the two species and showed both decrease and increase with the time of rehydration. Relative chlorophyll fluorescence decrease (RFd), which is considered a vitality indicator, increase with the time of rehydration showing similar trends in the first and the third cycle of rehydration. The results indicate that both Sanionia uncinata and Racomitrium lanuginosum are resistant to desiccation since FV/FM and FPSII recovered fully after 32 h of rehydration and there we only minor differences in the two parameters between the first and third rehydration cycle

Photoinhibition of photosynthesis in Antarctic lichen Usnea antarctica. I. Light intensity- and light duration-dependent changes in functioning of photosystem II

The paper deals with the differences in sensitivity of Antarctic lichen to photoinhibition. Thalli of Usnea antarctica were collected at the James Ross Island, Antarctica (57 deg 52 57 W, 63 deg 48 02 S) and transferred in dry state to the Czech Republic. After rewetting in a laboratory, they were exposed to 2 high light treatments: short-term (30 min), and long-term (6 h). In short-term treatment, the sample were exposed to 1000 and 2000 micromol m-2 s-1 of photosynthetically active radiation (PAR). In long-term experiment, PAR of 300, 600, and 1000 micromol m-2 s-1 were used. Photosynthetic efficiency of U.antarctica thalli was monitored by chlorophyll fluorescence parameters, potential (FV/FM) and actual (Phi PSII) quantum yield of photochemical processes in photosystem II in particular. In short-term treatments, the F0, FV and FM signals, as well as the values of FV/FM, and Phi PSII showed light-induced decrease, however substantial recovery after consequent 30 min. in dark. Longer exposition (60 min) to high light led to more pronounced decrease in chlorophyll fluorescence than after 30 min treatment, however dark recovery was faster in the thalli treated before for longer time (60 min). Long-term treatment by high light caused gradual decrease in FV/FM and Phi PSII with the time of exposition. The extent of the decrease was found light dose-dependent. The time course was biphasic for FV/FM but not for Phi PSII. The study showed that wet thalli of Usnea antarctica had high capacity of photoprotective mechanisms to cope well either with short- or long-term high light stress.Článek se zabývá rozdíly v citlivosti antarktických lišejníků na fotoinhibici. Stélky Usnea Antarktidy byly odebrány na Ostrově Jamese Rosse v Antarktidě (57 stupňů 52 57 W, 63 stupňů 48 02 S) a přeneseny v suchém stavu do ČR. Po ovlhčení v laboratoři byly vystaveny krátkodobé (30 min) a dlouhodobé (6 h) fotoinhibici. V krátkodobém experimentu byly vzorky se vystaveny 1000 a 2000 micromol m-2 s-1 fotosynteticky aktivního záření (PAR). Při dlouhodobém experimentu, PAR 300, 600, a 1000 micromol m-2 s-1 byly použity. Fotosyntetická účinnost U.antarctica stélek byla sledována podle parametrů fluorescence chlorofylu, potenciální (FV / FM) a efektivní (Phi PSII) kvantový výtěžek fotochemických procesů v fotosystému II.The paper deals with the differences in sensitivity of Antarctic lichen to photoinhibition. Thalli of Usnea antarctica were collected at the James Ross Island, Antarctica (57 deg 52 57 W, 63 deg 48 02 S) and transferred in dry state to the Czech Republic. After rewetting in a laboratory, they were exposed to 2 high light treatments: short-term (30 min), and long-term (6 h). In short-term treatment, the sample were exposed to 1000 and 2000 micromol m-2 s-1 of photosynthetically active radiation (PAR). In long-term experiment, PAR of 300, 600, and 1000 micromol m-2 s-1 were used. Photosynthetic efficiency of U.antarctica thalli was monitored by chlorophyll fluorescence parameters, potential (FV/FM) and actual (Phi PSII) quantum yield of photochemical processes in photosystem II in particular. In short-term treatments, the F0, FV and FM signals, as well as the values of FV/FM, and Phi PSII showed light-induced decrease, however substantial recovery after consequent 30 min. in dark. Longer exposition (60 min) to high light led to more pronounced decrease in chlorophyll fluorescence than after 30 min treatment, however dark recovery was faster in the thalli treated before for longer time (60 min). Long-term treatment by high light caused gradual decrease in FV/FM and Phi PSII with the time of exposition. The extent of the decrease was found light dose-dependent. The time course was biphasic for FV/FM but not for Phi PSII. The study showed that wet thalli of Usnea antarctica had high capacity of photoprotective mechanisms to cope well either with short- or long-term high light stress. The paper deals with the differences in sensitivity of Antarctic lichen to photoinhibition

Photoinhibition of photosynthesis in Antarctic lichen Usnea antarctica. II. Analysis of non-photochemical quenching mechanisms activated by low to medium light doses

The paper focus sensitivity of an Antarctic lichen Usnea antarctica to photoinhibition studied under controlled laboratory conditions. Main emphasis was given to the analysis of quenching mechanisms, i.e. deexcitation pathways of absorbed light energy exploited in non-photochemical processes. Thalli of U. antarctica were collected at the James Ross Island, Antarctica (57°52´57´´ W, 63°48´02´´ S) and transferred in dry state to the Czech Republic. After rewetting in a laboratory, they were exposed to medium light intensities (300, 600 and 1000 mmol m-2 s-1 of photosynthetically active radiation) for 6 h. Before and during photoinhibitory treatments, chlorophyll fluorescence parameters, photoinhibitory (qI), state 1-2 transition (qT), and energy-dependent quenching (qE) in particular were measured to evaluate dose- and time-dependent changes in these parameters. The results showed that among the components forming non-photochemical quenching (qN), qI contributes to the largest extent to qN, while qE and qT contribute less. This finding differs from our earlier studies made in a short term-, and high light-treated U. antarctica that found qE together with qI is the most important part of non-photochemical quenching. Possible explanation is that photoinhibition in PS II in U. ant-arctica, when induced by low to medium light, activates qE to only limited extend and for a relatively short time (tens of minutes). With prolonged high light treatment lasting several hours, qE tends to be reduced to the values close to zero and qI then forms a major part of qN

Management of UPS Supplies with GSM Technology

Tato práce je věnována problematice záložních zdrojů a jejich vlastnostem. Je zde popsán návrh UPS zdroje k řízení a monitorování záložní baterie. UPS zdroj je kompletně řízen přes rozhraní ethernet a protokol TCP/IP. Dále je zde zároveň navržena jednotka TCP/IP GSM modulu, která řeší komunikační rozhraní mezi sítěmi typu GSM a Ethernet. UPS a GSM modul jsou navrženy kompletně. V projektu jsou obsaženy všechny potřebné podklady pro konstrukci hardware modulů i jejich softwarové řešení. Moduly jsou navrženy velmi univerzálně, umožňují tak široké možnosti dalšího vývoje.Theme of the Master's thesis is issue of backup power units and its attributes. There is also complete proposal of UPS power unit which can be used to control and monitor backup batteries. Power supply is fully controlled via Ethernet interface using TCI/IP protocol. The other chapter describes complete development of TCI/IP GSM unit which can be used for communication interface between GSM and Ethernet protocol. UPS and GSM modules are developed in details. The Master.s thesis includes all needed information for HW unit development and also for controlling software as well. Universal solution of the modules allows number possibilities of further development.

Interspecific differences in photosynthetic efficiency and spectral reflectance in two Umbilicaria species from Svalbard during controlled desiccation

This study aimed to evaluate the effective photosynthetic quantum yield ( Phi PSII) and the Photochemical Reflectance Index (PRI) for assessment of photosynthetic performance of two Umbilicaria lichens during gradual desiccation of their thalli. U. cylindrica and U. decussata exhibited curvilinear relationship (S-shape curve) of decreasing Phi PSII values with decreasing water potential (WP) of thalli. During initial phase of desiccation (WP from 0 to -10 MPa), no decrease of Phi PSII was apparent, further desiccation (WP from -10 to -20 MPa) led to fast Phi PSII decrease from 0.6 to 0.1 indicating strong inhibition of photosynthetic processes. Critical WP at which photosythetic processes are fully inhibited was found bellow -25 MPa in both lichen species. Photochemical Reflectance Index (PRI) exhibited curvilinear increase with thalli desiccation (decreasing WP). At full thallus hydration, the PRI reached the value of -0.18 in both species. Under strong dehydration (WP from -20 to -30 MPa), however, U. cylindrica showed somewhat lower value (-0.04) than U.decussata (-0.02 MPa). PRI to WP relationship is discussed and compared to existing evidence from higher plants and poikilohydric organisms.Tato publikace je zaměřena na souběžné sledování indexu PRI a efektivního kvantového výtěžku fyotoyntézy během vysychání stélek dvou druhů lišejníků rodu Umbilicaria ze souostroví Špicberky (Svalbard). Byl zjištěno, že PRI s postupujícím vysycháním roste, zatímco u listů vyšších rostlin klesá.This study aimed to evaluate the effective photosynthetic quantum yield (Phi PSII) and the Photochemical Reflectance Index (PRI) for assessment of photosynthetic performance of two Umbilicaria lichens during gradual desiccation of their thalli. U. cylindrica and U. decussata exhibited curvilinear relationship (S-shape curve) of decreasing Phi PSII values with decreasing water potential (WP) of thalli. During initial phase of desiccation (WP from 0 to -10 MPa), no decrease of Phi PSII was apparent, further desiccation (WP from -10 to -20 MPa) led to fast Phi PSII decrease from 0.6 to 0.1 indicating strong inhibition of photosynthetic processes. Critical WP at which photosythetic processes are fully inhibited was found bellow -25 MPa in both lichen species. Photochemical Reflectance Index (PRI) exhibited curvilinear increase with thalli desiccation (decreasing WP). At full thallus hydration, the PRI reached the value of -0.18 in both species. Under strong dehydration (WP from -20 to -30 MPa), however, U. cylindrica showed somewhat lower value (-0.04) than U.decussata (-0.02 MPa). PRI to WP relationship is discussed and compared to existing evidence from higher plants and poikilohydric organisms