Team:Shiyan SY China/Project.html
You have to believe in yourself. That’s the secret of success.
—— Charles Chaplin
With increased agriculture activities around the world, it becomes a common practice to use pesticides to manage pest problem. Runoff can carry field pesticide into aquatic environment while wind can carry them to other fields, potentially affecting other species. Over time, repeated application increases pest resistance and facilitate the pest resurgence. Further, especially in China, toxic pesticide residues on green vegetable and fruits become a major public health problem.
In order to provide a solution, we design an engineered bacterium, secreting the OMP enzyme to degrade the common toxic pesticide residues. Its secretion is under the temperature control and can only be activated at specified temperature. To avoid the secondary pollution, a UV-induced suicide gene is inserted into the bacteria: upon exposure to UV or sunshine, the suicide procedure is induced. This purpose of the design is to remove toxic pesticide safely without affecting the environment.
The increasing environmental pollution and changeable climates make the insect pests on crops more serious. According to the statistical data from Chinese Academy of Agricultural Sciences, in recent years, there have been over seventy kinds of insect pests on vegetables and fruits. If these insect pests are not controlled, they will lead to total failures of crops, such as vegetables, fruits and grains. Faced with raging insect pests, the farmers have to constantly spray pesticides, and even use the high-toxic pesticides which are forbidden by our country. Therefore, as a result of the use of pesticides, a majority of vegetables and fruits contain pesticides above the permitted limits, but they still flow into thousands of families through channels such as vegetable markets, supermarkets and roadside stalls.
It is shown according to the statistics from World Health Organization, there are at least 500 000 pesticide poisoning accidents and 115 000 persons who die of pesticide poisoning annually all over the world. Moreover, over 85% of cancer cases and over 80 kinds of diseases are relevant to pesticide residues. In many big cities in China, the exceeding standard rate of pesticide residues on vegetables and fruits reached up to 47%.
At present, the pesticides which are used most widely are phosphorus pesticides and ester pesticides. The phosphorus and ester in these two pesticides can both cause damages to the mechanism of human bodies. 1. Organophosphorus pesticides, are organic composites which contain organophosphorus pesticides and are used to prevent plant diseases and insect pests. These pesticides have multiple varieties, high pesticide effects, wide applications and are easy to be broken down. Additionally, they generally will not accumulate in human bodies and animal bodies, and are highly important composites among pesticides. The organophosphorus pesticides produced currently are mostly insecticides, such as parathion, demeton, malathion, dimethoate, trichlorphon and dichlorvos which are often used. In recent years, organophosphorus pesticides such as bactericide and rodenticide have been synthesized. Organophosphorus pesticides have many varieties and can be divided into high-toxic, medium-toxic and low-toxic according to their degrees of toxicity. Toxicity of each variety can be different. A majority of organophosphorus pesticides belong to high-toxic and medium-toxic varieties while a minority of them are low-toxic. Only a gentle contact of small amount of high-toxic organophosphorus pesticides can cause poisoning while damages can be caused if a large amount of low-toxic organophosphorus pesticides enter human bodies. The amounts of organophosphorus inside different human bodies which can cause poisoning and death range from person to person. The poisoning symptoms which are caused by organophosphorus pesticides’ entering human bodies from digestive tracts are severer than those caused by common concentration of organophosphorus pesticides’ entering human bodies from respiratory tracts or skins while the disease attack rate by the former is also quicker than that by the latter. However, if a person inhales organophosphorus pesticides in large amounts or of high concentration, he or she can be attacked by disease within five minutes and dies quickly. The toxic effects organophosphorus pesticides have on human bodies are mainly to combine with cholinesterase to form phosphorylation cholinesterase. Then the activeness of cholinesterase is suppressed, which leads the enzymes to not being capable to break down acetylcholine. Consequently, the amount of acetylcholine which accumulates inside tissues is beyond limit and causes the cholinergic nerves to be overly stimulated, which leads to muscarinic, nicotinic and central nervous system symptoms.
Related studies prove that the sources of many diseases such as various cancers, leukemia, breast cancer, children of low intelligence and bad memory, meningitis, compounded diseases can be traced back to pesticide residues. People who always touch pesticides have a over 90% chance to suffer Parkinson’s disease. Additionally, contacts with pesticides can cause cardiovascualr and cerebrovascular diseases, diabetes and infertility. If eating fruits and vegetables with residual pesticides, people who are acutely poisoned will suffer symptoms such as headache, dizziness, vomit, stomachache and diarrhea. Apart from that chronic poisoning can lead to various diseases, pesticide residues can cause incurable deadly diseases (cancers) after accumulating in human bodies for about fifteen to twenty years.
Note: F1:…,F2:…, F3:…, F4: ….
Faced with the stress effects human pollution such as pesticides has on environment, nature has evolved many methods to deal with these problems. For example, many natural micro-organisms have the characteristic of degrading organophosphorus pesticides. Currently the micro-organisms which have been found being capable to degrade organophosphorus pesticides include bacteria, fungus, actinomycete and alga. As the research goes further, people find that these degrading bacteria degrade pesticides by secreting a kind of enzyme which can hydrolyze phosphaester bonds-organophosphorus-degradation enzyme. Because each organophosphorus pesticide has similar structure and is only different in substituent groups, one kind of organophosphorus-degradation enzyme can always degrade multiple kinds of organophosphorus pesticides. Organophosphorus-degradation enzyme has been widely acknowledged to be the most potential new method to eliminate pesticide residues currently. At present, many enzymes have been identified to be used to degrade organophosphate pesticides. Among these enzymes, organophosphorus-degradation enzyme (opdA) which comes from Agrobacterium radiobacter P230 of radioactive agrobactium tumefaciens genus has wider substrate and higher enzyme-catalyst efficiency. In recent years, the research on the structure and function of organophosphorus-degradation enzyme has gained relatively big development and comes into the molecule level, which makes it possible to improve the properties of organophosphorus-degradation enzyme through genetic engineering and protein engineering and invent organophosphorus-degradation enzyme products which meet requirements of different application fields.
We connect we the World magazine and publish the Igem monograph . In the magazine we discuss the safety, ethic, advantage and disadvantage of the synthetic biology. We record the process of our team, including the safety of the experiment and the what we learned during the experiment in the CAS. World magazine is established by the Liaoning province Shiyan high school’s international department., facing the entire school and the high school in the province,; therefore, through the magazine, we are able to share and discuss the igem with other students.
This part includes two individual DNA domains. 1. A strong promoter followed with a RNA thermometer sequence, which regulate the transcription of opdA gene and expression of opdA protein out of the host cell via an ompA peptide. This DNA fragment domain could be obtained by double-digested with EcoR I + Spe I. 2. A UV induced promoter (RecA SOS) followed with a suicide gene ccdB, which could lead to the death of host cell if exposed in UV. This DNA fragment domain could be obtained by double-digested with Xho I + Spe I. And the whole part DNA fragment could be obtained by double-digested with Xho I + EcoR I.
| Name | Type | Description | Length |
|---|---|---|---|
| BBa_K1667005 | DNA | OpdA encoding gene with ompA signal peptide | 1776 |
We do a new way spread the knowledge of biology to the public, and we update the dynamic of our team work.
