Abstract
Alfalfa (Medicago sativa) plantlets were exposed to Cd or Hg to study the kinetics of diverse stress indexes. In the so-called beaker-size hydroponic system, plantlets were grown in 30 microM of Cd or Hg for 7 d. Oxidative stress took place and increased over time, a linear response being observed with Cd but not with Hg. To improve the sensitivity of the stress assays used, a micro-assay system, in which seedlings were exposed for 24 h, was developed. Phytotoxicity of metals, quantified as growth inhibition, was observed well before there was any change in the non-protein thiol tissue concentration. When measured with conventional techniques, oxidative stress indexes did not show significant variation. To trace early and small plant responses to Cd and Hg, a microscopic analysis with novel fluorescent dyes, which had not yet been exploited to any significant extent for use in plants, was conducted. These fluorescent probes, which allowed minute cellular responses to 0, 3, 10, and 30 microM of both metals to be visualized in the roots of the alfalfa seedlings, were: (i) 2',7'-dichlorofluorescin diacetate that labels peroxides; (ii) monochlorobimane that stains reduced glutathione/homoglutathione (GSH/hGSH); and (iii) propidium iodide that marks nuclei of dead cells. Oxidative stress and cell death increased after exposure for 6-24 h to Cd and Hg, but labelling of GSH/hGSH decreased acutely. This diminution might be the result of direct interaction of GSH/hGSH with both Cd and Hg, as inferred from an in vitro conjugation assay. Therefore, both Cd and Hg not only compromised severely the cellular redox homeostasis, but also caused cell necrosis. In plants treated with 1 mM L-buthionine sulphoximine, a potent inhibitor of GSH/hGSH synthesis, only the oxidative stress symptoms appeared, indicating that the depletion of the GSH/hGSH pool was not sufficient to promote cell death, and that other phytotoxic mechanisms might be involved.
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Claims 15
Claim · model-written summary
Cd caused oxidative stress that increased linearly over time.
- Taxon
- Medicago sativa
Medicago sativat0 - Treatment
- Cde0
- Outcome
- Oxidative stresse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxidative stress took place and increased over time, a linear response being observed with Cd but not with Hg”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Hg caused oxidative stress that increased over time without a linear response.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Hge0
- Outcome
- Oxidative stresse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxidative stress took place and increased over time, a linear response being observed with Cd but not with Hg”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Metal phytotoxicity appeared as growth inhibition before nonprotein thiol concentration changed.
- Taxon
- Medicago sativaMedicago sativat0
- Outcome
- growth inhibitione0
- Direction
- inhibitione0
- Qualifier
- before there was any change in the non-protein thiol tissue concentratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phytotoxicity of metals, quantified as growth inhibition, was observed well before there was any change in the non-protein thiol tissue concentration”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Conventional techniques showed no significant variation in oxidative stress indexes.
- Taxon
- Medicago sativaMedicago sativat0
- Outcome
- oxidative stress indexese0
- Direction
- did not show significant variatione0
- Comparator
- conventional techniquese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When measured with conventional techniques, oxidative stress indexes did not show significant variation”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Fluorescent probes visualized minute cellular responses to metals in alfalfa roots.
- Taxon
- alfalfaMedicago sativae0
- Organ / stage
- rootse0
- Outcome
- minute cellular responsese0
- Value
- 0, 3, 10, and 30 microMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These fluorescent probes, which allowed minute cellular responses to 0, 3, 10, and 30 microM of both metals to be visualized in the roots of the alfalfa seedlings”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Oxidative stress increased after 6-24 h exposure to Cd.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Cde0
- Outcome
- Oxidative stresse0
- Direction
- increasede0
- Qualifier
- 6-24 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxidative stress and cell death increased after exposure for 6-24 h to Cd and Hg”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Cell death increased after 6-24 h exposure to Cd.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Cde0
- Outcome
- cell deathe0
- Direction
- increasede0
- Qualifier
- 6-24 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxidative stress and cell death increased after exposure for 6-24 h to Cd and Hg”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Oxidative stress increased after 6-24 h exposure to Hg.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Hge0
- Outcome
- Oxidative stresse0
- Direction
- increasede0
- Qualifier
- 6-24 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxidative stress and cell death increased after exposure for 6-24 h to Cd and Hg”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Cell death increased after 6-24 h exposure to Hg.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Hge0
- Outcome
- cell deathe0
- Direction
- increasede0
- Qualifier
- 6-24 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxidative stress and cell death increased after exposure for 6-24 h to Cd and Hg”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
GSH/hGSH labeling decreased acutely after Cd and Hg exposure.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Cd and Hge0
- Outcome
- labelling of GSH/hGSHe0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxidative stress and cell death increased after exposure for 6-24 h to Cd and Hg, but labelling of GSH/hGSH decreased acutely”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
The authors suggest that Cd and Hg directly interact with GSH/hGSH, based on an in vitro conjugation assay.
- Taxon
- Medicago sativaMedicago sativat0
- Compound
- GSH/hGSHe0
- Outcome
- diminutione0
- Qualifier
- in vitro conjugation assaye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This diminution might be the result of direct interaction of GSH/hGSH with both Cd and Hg, as inferred from an in vitro conjugation assay”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Cd and Hg compromised cellular redox homeostasis.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Cde0
- Outcome
- cellular redox homeostasise0
- Direction
- compromised severelye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both Cd and Hg not only compromised severely the cellular redox homeostasis, but also caused cell necrosis”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
Cd and Hg caused cell necrosis.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Hge0
- Outcome
- cell necrosise0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both Cd and Hg not only compromised severely the cellular redox homeostasis, but also caused cell necrosis”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
L-buthionine sulphoximine treatment produced oxidative stress symptoms alone.
- Taxon
- plantsViridiplantaee0
- Treatment
- 1 mM L-buthionine sulphoximinee0
- Outcome
- oxidative stress symptoms appearede0
Not reportedComparatorDirection
Verbatim
e0“In plants treated with 1 mM L-buthionine sulphoximine, a potent inhibitor of GSH/hGSH synthesis, only the oxidative stress symptoms appeared”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
Claim · model-written summary
The authors inferred that GSH/hGSH depletion alone did not suffice for cell death.
- Taxon
- Medicago sativaMedicago sativat0
- Compound
- GSH/hGSHe0
- Outcome
- cell deathe0
- Qualifier
- other phytotoxic mechanisms might be involvede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the depletion of the GSH/hGSH pool was not sufficient to promote cell death, and that other phytotoxic mechanisms might be involved”
t0“Cellular damage induced by cadmium and mercury in Medicago sativa”
The same questions in other papers
cadmium atom · molecular: metabolites · Medicago sativa (alfalfa)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
cadmium atom · physiology: oxidative · Medicago sativa (alfalfa)Positive and negative results
8 papers in the same direction as this paper · 1 in the opposite direction
- negative
- negative
- negative
6 papers more in this group
See all 10 papers →mercury atom · cytology · Medicago sativa (alfalfa)Results agree
1 paper in the same direction as this paper
- negative
mercury atom · physiology: oxidative · Medicago sativa (alfalfa)Results agree
3 papers in the same direction as this paper
- negative
- negative
- negative
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.