Revision as of 20:51, 19 October 2016

Orally Active Insecticidal Peptide (OAIP)

Orally Active Insecticidal Peptide (OAIP)

Introduction:

Figure 1. Orally Active Insecticidal Peptide

      By ligating the IPTG induced promoter T7 (BBa_ I712074), strong ribosome binding site (BBa_B0034), OAIP, linker, and the 6xHistag (BBa_ K1223006), we are able to express OAIP, the toxin by IPTG induction.
      This year we create a revolutionary system that integrates biological pesticides, automatic detector, sprinkler, and IoT. We made a database that contains most of the spider toxins and selected the target toxins by programming. Orally Active Insecticidal Peptide is coded for the venom of a spider, Selenotypus plumipes. It is under the control of the strong T7 promoter. A 6xHistag is added for further protein purification.

Figure 2. Omega-hexatoxin-Hv1a structure

Mechanism of OAIP:

      Orally Active Insecticidal Peptide has a structure called ICK(inhibitor cysteine knot).^[1] This kind of structure contains three disulfide bonds. With this structure OAIP can resist the high temperature, acid base solution and the digest juice of insect gut. OAIP can bind on the voltage-gated sodium channel in the insect’s nervous system, making it paralyze and die eventually.

Features of OAIP:

1. Non-toxic: rally Active Insecticidal Peptide is non-toxic to mammals and bees. Since the structure of the target ion channel is different, Orally Active Insecticidal Peptide does not harm mammals and bees. So it is safe to use it as a biological pesticide.

2. Biodegradable: The toxin is a peptide, so it must degrade over time. After degradation, the toxin will become nutrition inside the soil.

3. Species-specific: According to reference, Orally Active Insecticidal Peptide has specificity to Lepidopteran (moths), Coleopteran (beetles) and Isopteran (termite). So another insect such as bees will not be killed.

4. Eco-friendly: Compare with a chemical pesticide, Orally Active Insecticidal Peptide will not remain in soil and water so that it will not pollute the environment and won’t harm the ecosystem.

      Together, using OAIP is totally an environmentally friendly way for solving harmful insect problems by using this ion channel inhibitor as a biological pesticide.

Target insect:

Figure 3.

Experiment

1. Cloning :
After assembling the DNA sequences from the basic parts, we recombined each T7 Promoter+B0034+toxin +linker+6xHistag gene to pSB1C3 backbones and conducted a PCR experiment to check the size of each part. The DNA sequence length of these parts is around 250-500 bp. In this PCR experiment, the toxin product's size should be near at 450-700 bp.

Figure 4.P_T7 + RBS + OAIP+linker+6X His-Tag
The DNA sequence length of P_T7 + RBS + OAIP+linker+6X His-Tag is around 200-300 b.p. In this PCR experiment, the product’s size should be close to 500-600 b.p.

2. Expressing:
E.coli(DE3) express the protein and form the disulfide in the cytoplasm. We sonicated the bacteria and purified the protein by 6xHis-tag behind the toxin using Nickel resin column.

3. Analysis:
We do the Bradford analysis to get the protein concentration.

Figure 5.

4.Modeling:
ccording to reference, the energy of Ultraviolet will break the disulfide bonds and the toxicity is also decreased. To take the parameter into consideration for our automatic system, we modeled the degradation rate of the protein and modified the program in our device. Therefore, Pantide was tested under the ultraviolet light. The protein electrophoresis was shown below.

Figure 6. SDS-PAGE gel and the concentrations of UV radiolytic oxidation test to native Orally active insecticidal peptide (OAIP, 5.3 kDa). The samples are marked on the top of gel.

5. Device:
We designed a device that contains detector, sprinkler, and integrated hardware with users by APP through IoT talk. We use an infrared detector to detect the number of the pest and predict what time to spray the farmland. Furthermore, other detectors like temperature, humidity, lamination, pressure of carbon dioxide and on also install in our device. At the same time, the APP would contact the users that all the information about the farmland and spray biological pesticides automatically. This device can make farmers control the farmland remotely.

Results

Pantide-expressed E. coli Rosetta gami strain and diluted it with the three concentration.We applied the sample onto the leaf disks and put five cutworms into the separate cabinets for feeding assays. The positive control in the experiment was to apply Bacillus thuringiensis, which is the most widely-used bioinsecticide. We preserved all the result of the remained leaves sealing with the glass paper and calculated the ratio of the remained area on the leaves. The collected data were analyzed by t – test. Here are the feeding assay results.

Sequence and Features