Whitefly (<i>Bemisia tabaci</i>) is globally considered as a polyphagous agricultural pest that causes severe direct and indirect damage to many crops by feeding and transmitting viruses to plants[1].
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Vitellogenin plays a vital role in oocytes and embryo development in insects and Vitellogenin gene is responsible for the reduction of oxidative stress in honeybees. We cloned this gene into yeast to test if it reduces oxidative stress in eukaryotes [2]. The recombinant yeast <i>Pichia pastoris</i> has been described in [3]. Oxidative stress in eukaryotes is casually linked to the production of carbonyl derivatives. By measuring carbonyl derivatives concentration, oxidative stress can be quantified [4]. By using RNAi to create yeast without the Vitellogenin gene and comparing oxidative stress with the wild type cells, can show whether Vitellogenin is suitable to reduce oxidative stress in human cells.
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RNAi in insects: dsRNA is cleaved by a RNase III, often called Dicer, into 21-25 nt-long short interfering RNA duplexes (siRNA). These siRNAs are incorporated into the RNA-induced silencing complex (RISC). After discarding the passenger strand, the RISC complex binds to the target mRNA, cutting it and thereby hindering translation [5].
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The protein Vitellogenin has previously been expressed in the methyl-trophic yeast <i>Pichia pastoris</i> which has shown to impact cellular production of essential amino acids and long-chain polyunsaturated fatty acids. This effect is consistent with the putative role of Vitellogenin in the health of metazoans, a group which includes wasps (<i>Encarsia formosa</i>) and Silverleaf whitefly (<i>Bemisia tabaci</i>). Targeting Vitellogenin for increased production in certain wasps, or decreased production in Silverleaf whitefly, could both be future routes to controlling the whitefly as a pest.
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In this project we attempted to characterize kinetics of antisense-based down-regulation of recombinant Vitellogenin expression in <i>Pichia pastoris</i>. A genetic construct that complies with the BioBrick standard and enables both Vitellogenin expression and inducible Vitellogenin down-regulation by action of anti-sense RNA was assembled.
[[File:T--UCL--vitG.png|600px|none|]]
[[File:T--UCL--vitG.png|600px|none|]]
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Vitellogenin construct contains pAOX1 promoter (which is sensitive to methanol). Vitellogenin-GFP fusion is produced under pGAP promoter. In the presence of methanol pAOX1 promoter is activated, enabling synthesis of anti-sense mRNA, which binds to the mRNA of the Vitellogenin-GFP fusion and silencing the production of Vitellogenin.
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The experiment investigates the kinetics of anti-sense mRNA and may help Syngenta design the final gene construct in the bio-control of white fly.
Revision as of 13:57, 23 October 2016
pGAP-Vitellogenin-GFP device
Assembly Compatibility:
10
COMPATIBLE WITH RFC[10]
12
INCOMPATIBLE WITH RFC[12]
Illegal NheI site found at 1905 Illegal NheI site found at 2139 Illegal NheI site found at 4457
21
INCOMPATIBLE WITH RFC[21]
Illegal BglII site found at 1 Illegal BglII site found at 3274 Illegal BglII site found at 3900 Illegal BglII site found at 3936 Illegal BamHI site found at 1281 Illegal XhoI site found at 577
23
COMPATIBLE WITH RFC[23]
25
COMPATIBLE WITH RFC[25]
1000
INCOMPATIBLE WITH RFC[1000]
Illegal BsaI site found at 806 Illegal BsaI site found at 3681 Illegal BsaI site found at 3811 Illegal SapI site found at 244 Illegal SapI site found at 3868 Illegal SapI.rc site found at 5732
Design Notes
References
[1] Upadhyay S, Singh H, Dixit S, Mendu V, Verma P. Molecular characterization of vitellogenin and vetellogenin receptor of Bemisia tabaci. PLOS ONE(2016): 10.1371
[2] Seehuus S, Norberg K, Gimsa U, Krekling T, Amdam G. Reproductive protein protects functionally sterile honey bee workers from oxidative stress. PNAS (2006): 103, 962-967
[3] Ding J, Lim E, Li H, Kumar J, Lee S, Lam T. Expression of Recombinant Vitellogenin in the yeast Pichia pastoris. Biotechnology and Bioengineering (2004): 85
[4] Nystrom T. Role of oxidative carbonylation in protein quality control and senescence. The EMBO Journal (2005): 24
[5] Huvenne H, Smagghe G. Mechanisms of dsRNA uptake in insects and potential of RNAi for pest control: a Review. Journal of Insect Physiology (2010): 56, 227-235
