Effects of UV-B on Ciliates

Marangoni, Roberto; Marroni, Fabio; Gioffrè, Domenico; Colombetti, Giuliano

doi:10.1016/b978-012312945-1/50017-6

Cited by 5 publications

(16 citation statements)

References 32 publications

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“…The response of ciliates to UVB exposure is variable and species‐specific (Marangoni et al. ; Wickham and Carstens ). For example, results of the single exposure experiment here indicate that Parauronema acutum is tolerant to short‐term UVB exposure and has the ability to reverse UVB damage using PER and dark repair.…”

Section: Discussionmentioning

confidence: 99%

“…Stentor araucanus was able to withstand high levels of UV, possibly due to an algal endosymbiont (Marangoni et al. ), but S . coeruleus temporarily lost motility immediately following UV exposure (Häder and Häder ).…”

Section: Discussionmentioning

confidence: 99%

“…However, better general “status” of a ciliate population, which would likely include its nutritional state, may make it less sensitive UV radiation (Marangoni et al. ). Conversely, results of zooplankton studies that focused on the amount of food suggest it did not influence UV tolerance (Stutzman ).…”

Section: Discussionmentioning

confidence: 99%

“…CPDs mainly harm cells by blocking replication and transcription (Marangoni et al. ). In addition, some cellular repair mechanisms used to correct CPDs also are subject to error and can lead to point mutations (Buma et al.…”

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confidence: 99%

“…Other adverse effects of UVB exposure for aquatic protists include decreased feeding and/or cell division and alterations in cell motility (Marangoni et al. ; Ochs ; Sanders et al. ).…”

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confidence: 99%

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Effects of Temperature and Photorepair Radiation on a Marine Ciliate Exposed to UVB Radiation

Hamsher

Sung

Sanders

2018

J Eukaryotic Microbiology

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The influences of intensity and repeated exposure to ultraviolet-B radiation (UVB), photoreactivating repair radiation (PRR), and temperature on the scuticociliate Parauronema acutum were explored under laboratory conditions. Population growth was negatively affected after exposure to the equivalent of one sunny summer day of ambient UVB, especially in the absence of PRR. Repeated daily exposure to UVB severely compromised ciliate survival. UVB-exposed treatments without PRR recovered slower and reached lower final abundances than treatments receiving PRR. Reducing the daily UVB exposure approximately 25% improved ciliate recovery after exposure. In the single exposure treatments, temperature effects were not consistent, except that growth was slowest for control and treatments at the lowest temperature (15 °C). These data suggest that dark repair and/or photoprotection are present in P. acutum, but photoenzymatic repair was the more effective mechanism in reversing UVB damage. Repeated exposure treatments without PRR had zero or declining growth at all temperatures (15, 20 and 25 °C), as did those with PRR at 15 °C. Significant temperature/dose differences were identified in the repeated exposure treatments; ciliates subjected to the higher UVB intensity with PRR survived only at 25 °C, while ciliate populations under reduced UVB increased at 20 and 25 °C.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

“…Other adverse effects of UVB exposure for aquatic protists include decreased feeding and/or cell division and alterations in cell motility (Marangoni et al. ; Ochs ; Sanders et al. ).…”

mentioning

confidence: 99%

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Effects of Temperature and Photorepair Radiation on a Marine Ciliate Exposed to UVB Radiation

Hamsher

Sung

Sanders

2018

J Eukaryotic Microbiology

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Action Spectra for UVB Impacts on Blepharisma japonicum Motility and Photobehavior

Checcucci

Sgarbossa

Gioffrè

et al. 1999

Photochem & Photobiology

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The ciliate Blepharisma japonicum was exposed to artificial polychromatic and monochromatic UV radiation to evaluate the relative roles of UVB (28&315 nm UV radiation) and UVA (315-400 nm UV radiation) in altering its motility and photobehavior and to determine absolute weighting coefficients for these effects in the UVB range. Under polychromatic UV irradiation B. japonicurn cells showed a severe reduction of cell speed and of the capability to respond to light stimuli. At low doses, however, UV caused a significant increase in the average velocity of a cell population. The UVB exclusion experiments indicated that UVA does not significantly alter motility and photoresponsiveness. The increase and the subsequent decrease in cell velocity was observed also under monochromatic irradiation at 281, 290 and 300 nm, whereas at 310 nm cells swim faster up to the highest photon flux density used. The cell capability of reacting to photic stimuli, conversely, steadily declined with increasing photon flux density at all the tested UVB wavelengths. The action spectra for the alteration of cell velocity and the impairment of photoresponsiveness show that the lower the irradiation wavelength, the more remarkable are the UVB effects and suggest different targets for the increase and the decrease in cell velocity.

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Effects of UV‐B Irradiation on a Marine Microecosystem^¶

Marangoni

Messina

Gioffrè

et al. 2004

Photochem & Photobiology

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Purpose of this work was to study the effect of UV irradiation on a microecosystem consisting of several interacting species. The system chosen was of a hypersaline type, where all the species present live at high salt concentration; it comprises different bacteria; a producer, the photosynthetic green alga Dunaliella salina; and a consumer, the ciliated protozoan Fabrea salina, which form a complete food chain. We were able to establish the initial conditions that give rise to a selfsustaining microecosystem, stable for at least 3 weeks. We then determined the effect of UV irradiation on this microecosystem under laboratory‐controlled conditions, in particular by measuring the critical UV exposure for the two main components of the microecosystem (algae and protozoa) under UV‐B irradiances comparable to those of solar irradiation. In our experiments, we varied irradiance, total dose and spectral composition of the actinic light. The critical doses at irradiances of the order of 56 kJ/m2 (typical average daily irradiance in a sunny summer day in Pisa), measured for each main component of the microecosystem (algae and ciliates), turned out to be around 70 kJ/m2 for ciliates and 50 kJ/m2 for D. salina. By exposing microecosystems to daily UV‐B irradiances of the order of 8 kJ/m2 (typical average daily irradiance in a sunny winter day in Pisa), we found no effect at total doses of the order of the critical doses at high irradiances, showing that the reciprocity law does not hold. We have also measured a preliminary spectral‐sensitive curve of the UV effects, which shows an exponential decay with wavelength.

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Effects of UV-B on Ciliates

Cited by 5 publications

References 32 publications

Effects of Temperature and Photorepair Radiation on a Marine Ciliate Exposed to UVB Radiation

Effects of Temperature and Photorepair Radiation on a Marine Ciliate Exposed to UVB Radiation

Action Spectra for UVB Impacts on Blepharisma japonicum Motility and Photobehavior

Effects of UV‐B Irradiation on a Marine Microecosystem^¶

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Effects of UV-B on Ciliates

Cited by 5 publications

References 32 publications

Effects of Temperature and Photorepair Radiation on a Marine Ciliate Exposed to UVB Radiation

Effects of Temperature and Photorepair Radiation on a Marine Ciliate Exposed to UVB Radiation

Action Spectra for UVB Impacts on Blepharisma japonicum Motility and Photobehavior

Effects of UV‐B Irradiation on a Marine Microecosystem¶

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Effects of UV‐B Irradiation on a Marine Microecosystem^¶