Limits...
Utilizing the effective xanthophyll cycle for blooming of Ochromonas smithii and O. itoi (Chrysophyceae) on the snow surface.

Tanabe Y, Shitara T, Kashino Y, Hara Y, Kudoh S - PLoS ONE (2011)

Bottom Line: It is considered to be effective utilizing the xanthophyll cycle and holding sunscreen pigments as protective system for snow algae blooming in the vulnerable environment such as low temperature and nutrients, and strong light, however the study on the photoprotection of chrysophytes snow algae has not been shown.To dissolve how the chrysophytes snow algae can grow and bloom under such an extreme environment, we studied with the object of light which is one point of significance to this problem.This experimental study using unialgal cultures revealed that both O. smithii and O. itoi utilize only the efficient violaxanthin cycle for photoprotection as a dissipation system of surplus energy under prolonged high-light stress, although they possess chlorophyll c with diadinoxanthin.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Polar Research, Tachikawa, Japan. ukko@nipr.ac.jp

ABSTRACT
Snow algae inhabit unique environments such as alpine and high latitudes, and can grow and bloom with visualizing on snow or glacier during spring-summer. The chrysophytes Ochromonas smithii and Ochromonas itoi are dominant in yellow-colored snow patches in mountainous heavy snow areas from late May to early June. It is considered to be effective utilizing the xanthophyll cycle and holding sunscreen pigments as protective system for snow algae blooming in the vulnerable environment such as low temperature and nutrients, and strong light, however the study on the photoprotection of chrysophytes snow algae has not been shown. To dissolve how the chrysophytes snow algae can grow and bloom under such an extreme environment, we studied with the object of light which is one point of significance to this problem. We collected the yellow snows and measured photosynthetically active radiation at Mt. Gassan in May 2008 when the bloom occurred, then tried to establish unialgal cultures of O. smithii and O. itoi, and examined their photosynthetic properties by a PAM chlorophyll fluorometer and analyzed the pigment compositions before and after illumination with high-light intensities to investigate the working xanthophyll cycle. This experimental study using unialgal cultures revealed that both O. smithii and O. itoi utilize only the efficient violaxanthin cycle for photoprotection as a dissipation system of surplus energy under prolonged high-light stress, although they possess chlorophyll c with diadinoxanthin.

Show MeSH
Changes in xanthophyll cycle pigments in Ochromonas itoi and Ochromonas smithii after 6-h high-light (HL) incubation.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3044130&req=5

pone-0014690-g004: Changes in xanthophyll cycle pigments in Ochromonas itoi and Ochromonas smithii after 6-h high-light (HL) incubation.

Mentions: After 6-h HL irradiation, all four pigments increased in O. itoi (Vx: 15.7 (±0.288)–18.9 (±0.108); Ax: 0.293 (±0.0158)–1.12 (±0.00711); Zx: 0.212 (±0.00387)–0.504 (±0.00327); Ddx: 0.650 (±0.0255)–1.06 (±0.0234); Fig. 4). Decrease in Ddx and Vx from 0.378 (±0.0234) mol/100 mol Chl.a to 0.353 (±0.000462) mol/100 mol and from 14.1 (±0.108) mol/100 mol to 13.4 (±0.105) mol/100 mol, respectively, and increase in Ax and Zx from 0.322 (±0.0174) mol/100 mol to 1.26 (±0.0240) mol/100 mol and 0.427 (±0.00341) mol/100 mol to 0.971 (±0.00258) mol/100 mol, respectively, were observed in O. smithii. Although the pool size of Vx cycle pigments (Vx+Ax+Zx) increased in both species, Dtx was not detected. The values are means of three independent measurements, and error estimates in parenthesis are standard deviations. This increase of the Vx cycle pool size supports to the photosynthesis data in which showed the detected NPQ and the decrease of light use efficiency at lower PAR after 6-h HL irradiation. In LL illumination after 6-h HL, Vx, Ax, and Zx in O. itoi began to decrease after 5 min, and Ax and Zx then continued to decrease until 30 min (Fig. 5A). Ddx also decreased at 5 min; however, Dtx was never detected (Fig. 5B). Then, Vx and Ddx did not almost change during 1-h HL after 6-h HL followed by 1-h LL, but Ax and Zx gradually increased for 1 h (Fig. 6). These results showed that the deepoxidation reactions from Vx to Ax and Zx and the epoxidation reactions from Ax and Zx to Vx occur under HL and LL, respectively. Although the two snow algae were thought to utilize both Ddx and Vx cycles as xanthophyll cycles at first, the pigments analysis after HL and the time-course irradiation experiment confirmed that only the Vx cycle operates in both snow algae, even though they possess Ddx. The molar ratios of Ddx/Chl.a shown in Table 1 clearly indicate that the amount of Ddx is too low to be functional in photoprotection.


Utilizing the effective xanthophyll cycle for blooming of Ochromonas smithii and O. itoi (Chrysophyceae) on the snow surface.

Tanabe Y, Shitara T, Kashino Y, Hara Y, Kudoh S - PLoS ONE (2011)

Changes in xanthophyll cycle pigments in Ochromonas itoi and Ochromonas smithii after 6-h high-light (HL) incubation.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3044130&req=5

pone-0014690-g004: Changes in xanthophyll cycle pigments in Ochromonas itoi and Ochromonas smithii after 6-h high-light (HL) incubation.
Mentions: After 6-h HL irradiation, all four pigments increased in O. itoi (Vx: 15.7 (±0.288)–18.9 (±0.108); Ax: 0.293 (±0.0158)–1.12 (±0.00711); Zx: 0.212 (±0.00387)–0.504 (±0.00327); Ddx: 0.650 (±0.0255)–1.06 (±0.0234); Fig. 4). Decrease in Ddx and Vx from 0.378 (±0.0234) mol/100 mol Chl.a to 0.353 (±0.000462) mol/100 mol and from 14.1 (±0.108) mol/100 mol to 13.4 (±0.105) mol/100 mol, respectively, and increase in Ax and Zx from 0.322 (±0.0174) mol/100 mol to 1.26 (±0.0240) mol/100 mol and 0.427 (±0.00341) mol/100 mol to 0.971 (±0.00258) mol/100 mol, respectively, were observed in O. smithii. Although the pool size of Vx cycle pigments (Vx+Ax+Zx) increased in both species, Dtx was not detected. The values are means of three independent measurements, and error estimates in parenthesis are standard deviations. This increase of the Vx cycle pool size supports to the photosynthesis data in which showed the detected NPQ and the decrease of light use efficiency at lower PAR after 6-h HL irradiation. In LL illumination after 6-h HL, Vx, Ax, and Zx in O. itoi began to decrease after 5 min, and Ax and Zx then continued to decrease until 30 min (Fig. 5A). Ddx also decreased at 5 min; however, Dtx was never detected (Fig. 5B). Then, Vx and Ddx did not almost change during 1-h HL after 6-h HL followed by 1-h LL, but Ax and Zx gradually increased for 1 h (Fig. 6). These results showed that the deepoxidation reactions from Vx to Ax and Zx and the epoxidation reactions from Ax and Zx to Vx occur under HL and LL, respectively. Although the two snow algae were thought to utilize both Ddx and Vx cycles as xanthophyll cycles at first, the pigments analysis after HL and the time-course irradiation experiment confirmed that only the Vx cycle operates in both snow algae, even though they possess Ddx. The molar ratios of Ddx/Chl.a shown in Table 1 clearly indicate that the amount of Ddx is too low to be functional in photoprotection.

Bottom Line: It is considered to be effective utilizing the xanthophyll cycle and holding sunscreen pigments as protective system for snow algae blooming in the vulnerable environment such as low temperature and nutrients, and strong light, however the study on the photoprotection of chrysophytes snow algae has not been shown.To dissolve how the chrysophytes snow algae can grow and bloom under such an extreme environment, we studied with the object of light which is one point of significance to this problem.This experimental study using unialgal cultures revealed that both O. smithii and O. itoi utilize only the efficient violaxanthin cycle for photoprotection as a dissipation system of surplus energy under prolonged high-light stress, although they possess chlorophyll c with diadinoxanthin.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Polar Research, Tachikawa, Japan. ukko@nipr.ac.jp

ABSTRACT
Snow algae inhabit unique environments such as alpine and high latitudes, and can grow and bloom with visualizing on snow or glacier during spring-summer. The chrysophytes Ochromonas smithii and Ochromonas itoi are dominant in yellow-colored snow patches in mountainous heavy snow areas from late May to early June. It is considered to be effective utilizing the xanthophyll cycle and holding sunscreen pigments as protective system for snow algae blooming in the vulnerable environment such as low temperature and nutrients, and strong light, however the study on the photoprotection of chrysophytes snow algae has not been shown. To dissolve how the chrysophytes snow algae can grow and bloom under such an extreme environment, we studied with the object of light which is one point of significance to this problem. We collected the yellow snows and measured photosynthetically active radiation at Mt. Gassan in May 2008 when the bloom occurred, then tried to establish unialgal cultures of O. smithii and O. itoi, and examined their photosynthetic properties by a PAM chlorophyll fluorometer and analyzed the pigment compositions before and after illumination with high-light intensities to investigate the working xanthophyll cycle. This experimental study using unialgal cultures revealed that both O. smithii and O. itoi utilize only the efficient violaxanthin cycle for photoprotection as a dissipation system of surplus energy under prolonged high-light stress, although they possess chlorophyll c with diadinoxanthin.

Show MeSH