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Liu J, Wang J, Lee S, Wen R (2018) Copper-caused oxidative stress triggers the activation of antioxidant enzymes via ZmMPK3 in maize leaves. PLoS ONE 13(9): e0203612. https:// doi.org/10.1371/journal.pone.0203612.
I got this source from the online database Ebscohost. The authors are affiliated with a university so this would denote that they are experts in the field. The documentation stating this is:
“1 School of Life Science, Shanxi Datong University, Datong, PR China, 2 School of Life Sciences, Jiangsu Normal University, Xuzhou, PR China, 3 Maize Research Institute, Shanxi Academy of Agricultural Sciences, Xinzhou, PR China”
There are in-text citations, the numbers in parenthesis are the citations:
“In all eukaryotes, the mitogen-activated protein kinase (MAPK) cascade is a universal mod- ule of signal transduction, serving at the center of intracellular signal transduction. Diverse sig- nal pathways use MAPKs to regulate a variety of cellular functions in response to different extracellular stimuli [14–16]. There is abundant evidence that plant MAPKs can be activated by a variety of metals and play an important role in response to the metals such as AtMPK3 and AtMPK6 in arabidopsis [13], four distinct MAPKs in alfalfa, OsMPK3 and OsMPK6 in rice [17–19], and ZmMPK5 in maize [20]. A MAPK, named ZmMPK3 of group A in maize, shares high identity with the above MAPKs.”
The article does have a bibliography:
References
- Huffman DL, O’Halloran TV. Function, structure, and mechanism of intracellular copper trafficking pro- teins. Annu Rev Biochem. 2001; 70: 677–701. https://doi.org/10.1146/annurev.biochem.70.1.677PMID: 11395420
- Luo ZB, He J, Polle A, Rennenberg H. Heavy metal accumulation and signal transduction in herbaceous and woody plants: Paving the way for enhancing phytoremediation efficiency. Biotechnology Advances. 2016; 34: 1131–1148. https://doi.org/10.1016/j.biotechadv.2016.07.003 PMID: 27422434
- Hall JL. Cellular mechanisms for heavy metal detoxification and tolerance. J Exp Bot. 2002; 53: 1–11. PMID: 11741035
- Alaoui-Sosse ́ B, Genet P, Vinit-Dunand F, Toussaint ML, Epron D, Badot PM. Effect of copper on growth in cucumber plants (Cucumis sativus) and its relationships with carbohydrate accumulation and changes in ion contents. Plant Sci. 2004; 166: 1213–1218.
- Atha DH, Wang H, Petersen EJ, Cleveland D, Holbrook RD, Jaruga P, http://www.ncbi.nlm.nih.gov/ pubmed?term=Dizdaroglu%20M%5BAuthor%5D&cauthor=true&cauthor_uid=22201446etal. Copper oxide nanoparticle mediated DNA damage in terrestrial plant models. Environ Sci Technol. 2012; 46:
These 3 attributes denote that it is academic material, the academic material has been accepted before it was published which means it is peer-reviewed academic material.
“Editor: Ricardo Aroca, Estacion Experimental del Zaidin, SPAIN
Received: March 6, 2018
Accepted: August 23, 2018
Published: September 17, 2018”
There is a methods and results section in the article which means this is academic peer-reviewed research material.
Materials and methods
Plant materials and design
Maize (Zea mays L. cv. Nongda 108) seeds were incubated and grown hydroponically in the square plastic pot (30 cm × 20 cm) filled with 1 L Hoagland solution (0.156 μM Cu2+) in a light chamberunder a light intensity of 200 μmol m-2 s-1 and a 14 h: 10 h (28 ̊C: 22 ̊C) day: night regimes. There are 30 seedlings in each pot. The solution was changed every 2 d.
When the second leaves were fully expanded, the seedlings were exposed to a series of the concentration of Cu2+ solution (0, 10, 50 and 100 μM) respectively, for 24 h at 25 oC under a continuous light intensity of 200 μmol m-2 s-1. Two replicates were prepared for each concen- tration. There are 30 plants in each trait. To test H2O2 level, the roots of the maize seedlings were immersed into 1 mgmL-1 solution of 3,3-diaminobenzidine (DAB) (pH 3.8) for 8 h under light at 25 oC, and then were exposed to 100 μM CuCl2 for 0, 2, 4, 8, 12 and 24 h, respec- tively. To further investigate the effects of antioxidant dimethylthiourea (DMTU, 5 mM) and MAPK inhibitor (PD98059, 100 μM), the seedlings were pretreated with them separately for 8 h and then exposed to 100 μM CuCl2 for 24 h under the same conditions as described above. After Cu2+ treatments, the second leave from each seedling was sampled for analysis.
Results
H2O2 production in the leaves of maize exposed to Cu2+
The reaction of DAB with H2O2 can produce the deep brown polymerization product. DAB stain, a histochemical method for H2O2 detection, was employed to test H2O2 accumulation in leaves of maize plants exposed to Cu2+ stress. It was observed that brown polymerization prod- ucts were barely seen in the base of leave in the control plants, which indicated that the level of H2O2 was low (Fig 1A). Visible H2O2 accumulation was observed in leaves of maize plants exposed to Cu2+ for 2 h, which was obviously seen at 4 h. Cu2+ led to H2O2 production in a time-dependent manner (Fig 1A). H2O2 content in leaves of maize plants were examined using the methods of spectrophotometry.
