Abstract
Previous studies have indicated that phyto- chrome regulates Ca2+ fluxes across the plasma membrane of plant cells. In this study we investigated whether phytochrome can also regulate such fluxes across mitochondrial membranes, using the Ca2+-sensitive dye murexide to monitor the uptake and release of Ca2* by mitochondria. The results showed that Ca+ fluxes in these organelles could be photoreversibly altered, red light dimin- ishing the net uptake rate and far-red light restoring this rate to its dark control level. Treatment of the mitochondria with ruthenium red blocked their Ca2+ uptake. In the presence of this inhibitor, red light induced a net efflux of Ca2+ from the mitochondria, and subsequent far-red light reduced this efflux to nearly zero, the dark control level. Light-induced rate changes in Ca2+ flux, both with and without the inhibitor, persisted for several minutes in the dark and remained photoreversible through several irradiations for as long as 30 min. The purity of the mitochondrial preparation was judged to be about 80% by electron microscopic morphometry; most of the phytochrome present was localized on the mitochon- dria in the preparation by using immunocytochemical methods. Taken together with previous findings, the results suggest that red light activation of phytochrome would initiate an increase in the cytosolic Ca2+ concentration. The results are integrated with the fact that calmodulin is a component of plant cell cytoplasms to con- struct a model postulating that phytochrome directs photomorpho- genesis in part through its regulation of Ca+ and calmodulin-con- trolled enzyme activities. Phytochrome is a photomorphogenic pigment in plants that has two relatively stable spectral forms: a red-absorbing form (Pr) with an absorbance maximum near 667 nm and a far-red-absorb- ing form (Pfr) with an absorbance maximum near 730 nm. The two forms are interconvertible by light, and their photoconver- sions can control a large number of developmental processes in plants. Recent data have indicated that phytochrome can regulate Ca2+ fluxes across the plasma membrane of cells in several dif-
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 11
Claim · model-written summary
Red light diminished mitochondrial net calcium uptake.
- Taxon
- oats
Avena sativat0 - Treatment
- red lighte0
- Outcome
- net uptake ratee0
- Direction
- dimin- ishinge0
- Comparator
- dark control levele0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“red light dimin- ishing the net uptake rate and far-red light restoring this rate to its dark control level”
Claim · model-written summary
Far-red light restored mitochondrial calcium uptake to the dark control level.
- Taxon
- oatsAvena sativat0
- Treatment
- far-red lighte0
- Outcome
- this ratee0
- Direction
- restoringe0
- Comparator
- dark control levele0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“far-red light restoring this rate to its dark control level”
Claim · model-written summary
Ruthenium red blocked mitochondrial calcium uptake.
- Taxon
- oatsAvena sativat0
- Treatment
- ruthenium rede0
- Outcome
- Ca2+ uptakee0
- Direction
- blockede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“Treatment of the mitochondria with ruthenium red blocked their Ca2+ uptake”
Claim · model-written summary
With ruthenium red present, red light induced net calcium efflux from mitochondria.
- Taxon
- oatsAvena sativat0
- Treatment
- red lighte0
- Outcome
- net efflux of Ca2+ from the mitochondriae0
- Direction
- inducede0
- Qualifier
- presence of this inhibitore0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“In the presence of this inhibitor, red light induced a net efflux of Ca2+ from the mitochondria”
Claim · model-written summary
Subsequent far-red light reduced mitochondrial calcium efflux nearly to zero.
- Taxon
- oatsAvena sativat0
- Treatment
- far-red lighte0
- Outcome
- this effluxe0
- Direction
- reducede0
- Qualifier
- nearly zeroe0
- Comparator
- dark control levele0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“subsequent far-red light reduced this efflux to nearly zero, the dark control level”
Claim · model-written summary
Light-induced calcium-flux changes persisted in darkness for several minutes.
- Taxon
- oatsAvena sativat0
- Outcome
- rate changes in Ca2+ fluxe0
- Qualifier
- several minutes in the darke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“Light-induced rate changes in Ca2+ flux, both with and without the inhibitor, persisted for several minutes in the dark”
Claim · model-written summary
The mitochondrial calcium-flux response remained photoreversible over repeated irradiations for up to 30 minutes.
- Taxon
- oatsAvena sativat0
- Outcome
- photoreversiblee0
- Value
- 30 mine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“remained photoreversible through several irradiations for as long as 30 min”
Claim · model-written summary
Electron microscopy estimated mitochondrial preparation purity at about 80%.
- Taxon
- oatsAvena sativat0
- Outcome
- purity of the mitochondrial preparatione0
- Value
- about 80%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“The purity of the mitochondrial preparation was judged to be about 80% by electron microscopic morphometry”
Claim · model-written summary
Most phytochrome in the preparation was localized on mitochondria.
- Taxon
- oatsAvena sativat0
- Gene
- phytochromee0
- Outcome
- localized on the mitochon- driae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“most of the phytochrome present was localized on the mitochon- dria in the preparation by using immunocytochemical methods”
Claim · model-written summary
The authors suggest red-light activation of phytochrome increases cytosolic calcium concentration.
- Taxon
- oatsAvena sativat0
- Gene
- phytochromee0
- Outcome
- cytosolic Ca2+ concentratione0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“red light activation of phytochrome would initiate an increase in the cytosolic Ca2+ concentration”
Claim · model-written summary
The authors propose phytochrome regulates photomorphogenesis partly through calcium and calmodulin-controlled enzyme activities.
- Taxon
- oatsAvena sativat0
- Gene
- phytochromee0
- Outcome
- photomorpho- genesise0
- Qualifier
- regulation of Ca+ and calmodulin-con- trolled enzyme activitiese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“oats”
e0“phytochrome directs photomorpho- genesis in part through its regulation of Ca+ and calmodulin-con- trolled enzyme activities”
The same questions in other papers
light · nutrient: content · Avena sativa (oats)Positive and negative results
1 paper in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- positive
1 paper more in this group
See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.