GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (2)
Document type
Years
Year
  • 1
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Photoconversion of the red-absorbing form of phytochrome (Pr) to the far-red-absorbing form of phytochrome (Pfr) and vice versa has been measured spectrophotometrically at 10°C in immobilized and soluble phytochrome (118 kdalton), prepared from 5-day-old etiolated oat seedlings (Avena saliva L. cv. Sol II). The photostationary equilibrium φ= PfrPtot (with Ptot= total amount of phytochrome Pr+ Pfr) for red light depends on whether it is established by repetitive pulses (≥ 5 s) or by repetitive flashes (≥ 4 ms). In the wavelength region around 660 nm, a lower φ is reached with flashes as compared to that with pulses. This difference becomes negligible if the wavelength is shortened to the 600 nm region, and it also disappears if the fluence of each individual flash is reduced. In contrast, in long-wavelength red light and short-wavelength far-red light, a higher φ is reached with flashes than with pulses.We relate the differences in φ for flash and pulse irradiation to photochromic systems between Pr and photoreversible intermediates in the phototransformation pathway Pr→ Pfr. Thus, light absorption by phytochrome intermediates can be limiting for the quantitative relationship between light signal and Pfr formed.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A method is described to determine germination by blue-light excited red fluorescence in the positively photoblastic spores of Dryopteris paleacea Sw. This fluorescence is due to chlorophyll as evidenced from 1) a fluorescence-emission spectrum in vivo, where a bright fluorescence around 675 nm is obtained only in red light (R)-irradiated spores and 2) in vitro measurements with acetone extracts prepared from homogenized spores. Significant amounts of chlorophyll can be found only in R-treated spores; this chlorophyll exhibits an emission band around 668 nm, when irradiated with 430 nm light at 21°C.Compared to other criteria for germination, such as swelling of the cell, coat splitting, greening, and rhizoid formation, which require longer periods after induction for their expression, chlorophyll fluorescence can be used to quantify germination after two days. This result is confirmed by fluence-response curves for R-induced spore germination; the same relationship between applied R and germination is obtained by the evaluation with the epifluorescence method 2 days after the light treatment as compared with the evaluation with bright-field microscopy 5 days after the inducing R.Using this technique we show for the first time that Ca2+ contributes to the signaltransduction chain in phytochrome-mediated chlorophyll synthesis in spores of Dryopteris paleacea.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...