Photobiology of the Gonyaulax circadian system. I. Different phase response curves for red and blue light

Roenneberg, Till; Deng, Tzu-Shing

doi:10.1007/s004250050154

Cited by 50 publications

(44 citation statements)

References 30 publications

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“…In the seaward part of the present transect, where turbulence is not as strong as in the direct vicinity of the dyke, pelagic microalgae, especially diatoms, tend to sink to the bottom (Kiørboe, 1993), and can undergo cycles of suspension and settling through the water column. Such vertical transport has also been documented for dino-, crypto-and chrysophytes (Roenneberg & Deng, 1997;Olli & Seppa¨la¨, 2001). During the ebb phase of the tidal cycle, water enriched in suspended sediment and organisms flows out at generally higher flow velocities than during the flood phase (Stanev et al, 2003), leaving only a part of the bentho-pelagic microalgae on the deeper areas of the investigated transect (section I).…”

supporting

confidence: 56%

Microphytobenthic dynamics in a Wadden Sea intertidal flat – Part II: Seasonal and spatial variability of non-diatom community components in relation to abiotic parameters

Scholz

Liebezeit

2012

European Journal of Phycology

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The microphytobenthos colonizing the intertidal flats forms an important component of the Wadden Sea. Ten sampling points along a 1-km transect were studied in a fringe area of the Soltho¨rn tidal flat, southern North Sea, in order to determine seasonal differences in the microphytobenthos. An accompanying paper deals with the major component of the flora, the diatoms; here we, focus on the minor taxonomic groups. From May 2008 to May 2009 surface sediments were collected during low tide. Variation of environmental factors as well as microphytobenthic density (abundance and chlorophyll a) were monitored. The area investigated was a mixed-sediment mudflat, with a gradient from coarse to fine. Highest biomass was obtained in summer 2008 with 215.9 AE 12.6 mg chlorophyll a m -2 . In late autumn the chlorophyll a concentration decreased continuously at all investigated stations. Lowest values were detected in December 2008. Species abundances varied considerably both along the transect and seasonally, depending on species-specific requirements as well as hydrodynamic conditions (tidal currents). Higher densities of benthic pro-and eukaryotic microalgae were observed in sites characterized by fine sediments. Apart from the diatoms, the most abundant microphytobenthic group was the cyanophytes. Coccoid cyanophytes, mainly Merismopedia sp., were most abundant during summer, with cell numbers up to 5.72 Â 10 6 cells cm À2, while diatoms dominated in winter, spring and autumn. Filamentous cyanophytes, particularly Microcoleus chthonoplastes, were most abundant during autumn, while coccoid chlorophytes (spring: Chlorococcum submarinum, Crucigenia tetrapedia, Tetraselmis suecica), euglenophytes (summer: Euglena obtusa), dinophytes (autumn: Amphidinium operculatum, A. herdmanii) and cryptophytes (autumn: Hillea marina, Hemiselmis virescens) contributed to the microphytobenthos during warmer seasons. The statistical analysis confirmed that the composition of the microphytobenthos was related to sediment features and to characteristics of particular seasons.

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confidence: 56%

Microphytobenthic dynamics in a Wadden Sea intertidal flat – Part II: Seasonal and spatial variability of non-diatom community components in relation to abiotic parameters

Scholz

Liebezeit

2012

European Journal of Phycology

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“…6B). However, when the two light pulse types are given during the remaining part of the subjective night, blue pulses greatly advance the rhythm while red pulses still lead to considerable delays (79). One of the two receptors is mainly blue sensitive, strongly advancing the system in the subjective night; the other is both red and blue sensitive, mostly delaying the rhythm throughout the subjective day.…”

Section: Light and The Circadian System In A Unicellular Algamentioning

confidence: 99%

“…The freshwater algae Chlarnydomonas (70) and the marine alga Gonyaulax (79) appear to utilize this spectral information to regulate their circadian clocks, but there is little evidence for this in the vertebrates. We do know that the circadian systems of the mouse (107) and the hamster (122) are sensitive to both green light and near-UV irradiation, but we do not know how the signals from these different spectral channels are utilized by the mammalian circadian system.…”

Section: Light and The Circadian System Of Mammalsmentioning

confidence: 99%

Twilight Times: Light and the Circadian System

Roenneberg

Foster

1997

Photochem & Photobiology

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311

203

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Whose twilights were more clear, than our mid-day.John Donne (1571-1631) Of the progress of the soul THE CIRCADIAN CLOCKThe spatial and temporal features of the environment have provided the abiotic selection pressures that have shaped the evolution of life on earth. We are accustomed to accept that the spatial world offers specialized niches. However, we rarely consider that the temporal structure of our planet offers similar opportunities. Most organisms have evolved specializations that allow them to exploit their environment in terms of both space and time, and this demands that individuals have an endogenous representation of these environmental features. We know surprisingly little about the endogenous representation of space, but in recent years an understanding of how organisms build a representation of their temporal world has begun to emerge.Organisms do not merely respond to their environment, they also have the capacity to adjust physiology and behavior in anticipation of changing environmental conditions. In a competitive world, "being prepared" offers a great selective advantage. It takes considerable time to bring about the complex realignments of physiological systems that permit an optimal expression of different behavioral states (e.g. activity and rest or exploitation of temporally restricted resources). By fine-tuning physiology in advance of the changing conditions, an organism can be ready to exploit the changed conditions to its best advantage.At the heart of the biological machinery that "creates" a day within us is a biological or Circadian clock. In mammals, for example, this resides within a small paired nucleus in the brain located above the crossing of the optic nerves, the suprachiasmatic nuclei or SCN.? The neuronal activity of this nucleus continues to oscillate with a 24 h rhythmicity

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“…The blue-sensitive light input pathway in Gonyaulax is active only during the subjective night and is, thus, under clock control Roenneberg and Deng 1997;Roenneberg and Taylor 1994). The other light input pathway responds both to red and blue light, possibly sharing pigments with the photosynthesis machinery.…”

Section: Feedbacks Over Feedbacksmentioning

confidence: 99%