Difference between revisions of "Team:NYMU-Taipei/Project-Experiment"

 
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<img src="https://static.igem.org/mediawiki/2016/f/f7/T--NYMU-Taipei--photo-media-analysis-%E5%88%86%E9%A0%81_project_%E5%8A%A0%E5%AD%97%E7%89%88_experiment.jpg" width="100%" height="100%" />
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<h1>Experimentd</h1></div>
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<div class="satisfysp">
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<h1>Experiment</h1></div>
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<h2 style="margin-top:30px; margin-bottom:10px;">Selection markers</h2><hr>
<hr />
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 +
<p style="font-size:16px;">Firstly we tested for effective fungal selection marker <i>hph</i> and <i>ble</i> (Corresponding  antibiotics: hygromycin and phleomycin)
 +
</p>
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<p style="font-size:16px;"> The concentration for hygromycin selection ranges from 200-1000 µg/ml<sup>[1]</sup> and phleomycin-ranges from 10-50 µg/ml <sup>[2]</sup> for fungi.
 +
 
 +
We chose this series of antibiotic concentration:
 +
</p>
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<p style="font-size:16px;">    Hygromycin (μg/mL): 0, 50, 100, 150, 200
 +
</p>
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<p style="font-size:16px;"> Phleomycin (μg/mL): 0, 25, 50
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</p>
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<p style="font-size:16px;">
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<i>M. anisopliae</i> were incubated in each of the antibiotics test plates and incubated at 25°C.
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</p>
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<div style="border:1px solid:black">
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<img src="https://static.igem.org/mediawiki/parts/1/11/Hyg.jpeg" width="40%">
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<p style="font-size:16px;">Fig.1 Hygromycin test plates (1-5: 0, 50, 100, 150, 200 ug/mL)
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</p>
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</p>
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<div style="border:1px solid:black">
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<img src="https://static.igem.org/mediawiki/parts/6/63/Phe_done.png" width="40%">
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<p style="font-size:16px;">Fig.2 Phleomycin test plates (1-3: 0, 25, 50 ug/mL)
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</p>
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<p style="font-size:16px;">As the images shown above, the growing situation of wild type strain <i>M. anisopliae</i> on hygromycin or phleomycin plates are nearly the same comparing to the control. It indicated that our chassis fungi <i>Metarhizium anisopliae</i> ARSEF549 is not sensitive to hygromycin and phleomycin, that means hygromycin and phleomycin can not select transformants during transformation.
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</p>
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</div>  
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<h2 style="margin-top:30px; margin-bottom:10px;">Insect hemolymph bioassays</h2><hr>
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<p style="font-size:16px;">
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    We extracted insect hemolymph from three different species: oriental fruit flies, cherry cockroaches and silkworms.
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</p>
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<img src="https://static.igem.org/mediawiki/parts/b/b9/Fly.jpeg" height="250" width="250">
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<p style="font-size:16px;">Fig.3 Oriental fruit flies
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<img src="https://static.igem.org/mediawiki/parts/e/ef/Cockroach.jpeg" height="250" width="250">
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<p style="font-size:16px;">Fig.4 Extracting cherry cockroach's hemolymph
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<img src="https://static.igem.org/mediawiki/parts/f/f7/Silkworm.jpeg" height="250" width="250">
  
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<p style="font-size:16px;">Fig.5 Silkworms
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</p>
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</div>
  
<h2 style="margin-top:20px; margin-bottom:10px;">What’s the Problem?</h2><hr /><br />
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<div style="clear:both;"></div>
  
<b>Chemical insecticides:</b>
 
  
<p>Although chemical insecticides have improved the lives of countless human beings by controlling the population of both agricultural and urban pests, since the second half of last century, the numbers of insecticide resistant pests have been rising at an alarming rate [1]. Some would argue that as researchers and chemical pesticide companies develop new insecticides, the resistance couldn’t possibly catch up. In reality, the amount of insecticides applied is actually proportional to the increase in resistance in the target pest population [2, 3]. This means if no action was taken to change the status quo, the ongoing population control of insect pest will become even more of a struggle.</p>
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<p style="font-size:16px;">
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After 24 hours(in cherry cockroach and silkworm's hemolymph) and 30 hours(in oriental fruit fly's hemolymph) cultivation, the fungal cells were observed using the bright field microscopy(Magnification: 1000X).
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</p>
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<div id="DIV2">
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<img src="https://static.igem.org/mediawiki/parts/e/e8/Fly_done.png" height="250" width="250">
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<p style="font-size:16px;">Fig.6 <i>M. anisopliae</i> in oriental fruit fly's hemolymph for 30 hours
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</p>
 
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<div class="fund">
 
  
<h2 style="margin-top:20px; margin-bottom:10px;">Current Solution</h2><hr /><br />
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<img src="https://static.igem.org/mediawiki/parts/6/65/Coach_done.png" height="250" width="250">
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<p style="font-size:16px;">Fig.7 <i>M. anisopliae</i> in cherry coach's hemolymph for 24 hours
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</p>
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<img src="https://static.igem.org/mediawiki/parts/f/fc/Silkworm_done.png" height="250" width="250">
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<p style="font-size:16px;">Fig.8 <i>M. anisopliae</i> in silkworm's hemolymph for 24 hours
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</p>
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<p style="font-size:16px;"> Appressorium development can be clearly observed after 24h induction within the hemolymph of silkworms.
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</p>
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<div style="clear:both;"></div>
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<h2 style="margin-top:30px; margin-bottom:10px;"><i>Mcl1</i> promoter</h2><hr>
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 +
<p style="font-size:16px;">   
 +
    We designed the primers PMcl1-f(ACGTC//CTGCAG//AATCATGCAGCGCTATGAG, with a PstI site underlined) and PMcl1-r(ATAA//GCGGCCGC//CATGATGGTCTAGGGAACG with a NotI site underlined), according to the <i>PMcl1</i> sequence<sup>[1]</sup>, to amplify the <i>Mcl1</i> promoter region with <i>Mcl1</i> mRNA 5'-untranslated region at the 5' end of the coding region. The whole length is 2772bp.
 +
</p>
 +
 
 +
<p style="font-size:16px;">   
 +
    The gel image below shows that we succeed extracting the <i>Mcl1</i> promoter and its 5'-untranslated region (99bp downstream the promoter) from the genomic DNA of our chassis organism <i>M. anisopliae</i> ARSEF549.
 +
</p>
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<div style="border:1px solid:black">
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<img src="https://static.igem.org/mediawiki/parts/d/de/PMcl1_PCR.png" width="40%">
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<p style="font-size:16px;">Fig.9  Amplify <i>PMcl1</i> from gDNA
 +
</p>
 +
</div>
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 +
<p style="font-size:16px;">    Then we digested the DNA fragment with NotI and PstI in order to insert it into the backbone. However, when we ran gel electrophoresis to check the digestion result, we found that there is still one unknown PstI cut site inside the PMcl1 region.
 +
</p>
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<div style="border:1px solid:black">
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<img src="https://static.igem.org/mediawiki/parts/0/05/PMcl1_digest.jpeg" width="40%">
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<p style="font-size:16px;">Fig.10  The broken PMcl1 fragment
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</p>
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</div>
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<p style="font-size:16px;">  
 +
    We decided to sequence this DNA fragment we extracted and mutate the PstI site, but we didn't have enough time to finish our relative vectors construction.
 +
</p>
  
<p>Biopesticides, including insecticidal plant extract, bacteria, and fungi, are some of the more popular alternatives to chemical pesticides. Currently, the biopesticides that are the most widespread, in terms of usage, are the entomopathogenic-fungi insecticides [4]. Certain species of entomopathogenic fungi are capable of targeting a small range of hosts, making them the ideal solution to many regional insect pests. However, these biological control agents come with highly variable outcomes due to the variation in environmental (e.g. temperature and humidity) and host (e.g. nutrition and immune response) conditions [5].</p>
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<h2 style="margin-top:30px; margin-bottom:10px;">KillerRed expression in <i>M. anisopliae</i></h2><hr>
<p>Many researchers have tried to improve these fungal insecticides through biochemical or genetic means [6, 7]. Though they might have achieved in increasing the potency of or decreased the environment’s effects on a fungus species, they did not take a step further to consider the evaluation the fungal insecticide must follow before commercialization, which includes the assessment of its toxicity towards humans and animals, dispersal, horizontal gene transfer, and effects on the resident microflora [5].</p><br />
+
  
<h2 style="margin-top:20px; margin-bottom:10px;">Our Biosafety Solution</h2><hr /><br />
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<p style="font-size:16px;">   We constructed a KillerRed expression cassette with a fungal promoter <i>PgpdA</i> and a fungal terminator <i>TtrpC</i>. This cassette was used to confirm that KillerRed can be expressed in <i>M. anisopliae</i>
<p>
+
</p>
  The lack of biosafety development for genetically engineered fungal insecticides hinders its commercialization and public acceptance. To address this problem, we, 2016 NYMU_Taipei, are designing light-induced kill switch aimed to reduce the dispersal and horizontal gene transfer of genetically engineered fungal insecticides. Using an entomopathogenic fungus that is applied as an insecticide around the world, Metarhizium anisopliae, as our chassis, we constructed a genetically modified M. anisopliae with wildtype lethality and the additional ability to self-terminate after killing its host.<p/>
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<img src="https://static.igem.org/mediawiki/2016/0/02/T-NYMU-Taipei-photo-PMcl1_KR_TtrpC1.jpeg" width="60%">
  
<h5>In-Out-Suicide<h5><br/>
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<p style="font-size:16px;">    *The fluorescence images below indicated that KillerRed protein was successfully expressed in <i>M. anisopliae</i>.
<p>
+
</p>
  Through synchronizing the different stages of the kill switch activation with that of the M. ansiopliae’s infection cycle, our genetically modified M. anisopliae could infect and kill pest insects before self-termination. This allows for researchers to create highly lethal and environment tolerant fungal pesticides with reduced residual specimen in the area of application.
+
<img src="https://static.igem.org/mediawiki/parts/0/0f/PKT_FL.jpeg" width="90%">
  M. anisopliae’s infection cycle starts with conidia adhesion to the cuticle of the host. The fungus will then attempt to penetrate the cuticle by secreting various proteases, chitinases, and lipases. When the mycelium reaches the hemolymph, it will start to produce yeast-like blastospores, which will change gene expression alongside with any fungal cells that is in contact with the hemolymph. This is also when the production phase of our kill switch begins. Utilizing a hemolymph induced promoter from M. anisopliae, Pmcl 1, with fast activation and high production rate, original transcripts of the gene controlled by this promoter could be detected within 20 minutes of cellular contact with insect hemolymph and amounts for 5.6% of all ESTs [8], high amounts of KillerRed protein will be produced fungal cells within the hemolymph.
+
<p style="font-size:16px;">    As we observed, the growth situations of <i>M. anisopliae</i> KR transformants on media will not be affected greatly since irradiation of KillerRed localized in cell cytosol has a weak effect on cell survival in eukaryotic cells<sup>[3]</sup>.  
  KillerRed, BBa_K1184000, are fluorescent proteins that can be activated by yellow-orange light (540-585 nm) to produce highly reactive oxygen species (O2․-). During M. anisopliae’s stay within the hemolymph and other interior organs of the insect, KillerRed molecules will remain inert due to the lack of yellow light. However, when the fungus depletes the nutrients in its host, M. anisopliae will emerge for conidiation. This put fungal cells in direct contact with sunlight, allowing KillerRed to create O2․- and disrupt the metabolism and eventually killing the fungi.  
+
<img src="https://static.igem.org/mediawiki/parts/f/f7/KR-WT.jpeg" width="60%">
  In conclusion, our In-Out-Suicide system allows for more lethal genetically modified fungal pesticides to be developed because it provides them with an post-deployment clean up, lowering their threat to the surrounding environment.
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</p>
 +
<p style="font-size:16px;">
 +
    Surely, one should select some ROS-sensitive intracellular localizations, such as mitochondria, plasma membrane, or chromatin to increase efficiency of KillerRed-mediated oxidative stress.
 +
    The following two ways have been found to be effective for killing the eukaryotic cells using KillerRed: (1) via an apoptotic pathway using KillerRed targeted to mitochondria, and (2) via membrane lipid oxidation using membrane-localized KillerRed<sup>[3]</sup>.  
  
</p><br />
+
</p>
 +
<p style="font-size:16px;">
 +
    Under consideration, we decided to fuse a SV40 NLS to the KillerRed protein(<a href="http://parts.igem.org/Part:BBa_K2040122">BBa_K2040122</a>) so that KillerRed can function in the ROS-sensitive intracellular localizations, the chromatin in nucleus, due to the NLS.
 +
</p>
  
 +
<h2 style="margin-top:30px; margin-bottom:10px;">Reference</h2><hr>
  
 +
<p>1. <a hred="https://www.thermofisher.com/tw/zt/home/life-science/cell-culture/transfection/selection/hygromycin-b.html">Hygromycin B | Thermo Fisher Scientific</a></p>
 +
<p>2. <a hred="http://www.invivogen.com/PDF/Phleomycin_TDS.pdf">Victor Ilyin - Voprosy filosofii i psikhologii - 2015</a></p>
 +
<p>3. <a hred="http://evrogen.com/products/KillerRed/KillerRed_Detailed_description.shtml">Evrogen KillerRed: Detailed description</a></p>
  
 
</div>
 
</div>

Latest revision as of 02:00, 20 October 2016

Selection markers


Firstly we tested for effective fungal selection marker hph and ble (Corresponding antibiotics: hygromycin and phleomycin)

The concentration for hygromycin selection ranges from 200-1000 µg/ml[1] and phleomycin-ranges from 10-50 µg/ml [2] for fungi. We chose this series of antibiotic concentration:

Hygromycin (μg/mL): 0, 50, 100, 150, 200

Phleomycin (μg/mL): 0, 25, 50

M. anisopliae were incubated in each of the antibiotics test plates and incubated at 25°C.

Fig.1 Hygromycin test plates (1-5: 0, 50, 100, 150, 200 ug/mL)

Fig.2 Phleomycin test plates (1-3: 0, 25, 50 ug/mL)

As the images shown above, the growing situation of wild type strain M. anisopliae on hygromycin or phleomycin plates are nearly the same comparing to the control. It indicated that our chassis fungi Metarhizium anisopliae ARSEF549 is not sensitive to hygromycin and phleomycin, that means hygromycin and phleomycin can not select transformants during transformation.

Insect hemolymph bioassays


We extracted insect hemolymph from three different species: oriental fruit flies, cherry cockroaches and silkworms.

Fig.3 Oriental fruit flies

Fig.4 Extracting cherry cockroach's hemolymph

Fig.5 Silkworms

After 24 hours(in cherry cockroach and silkworm's hemolymph) and 30 hours(in oriental fruit fly's hemolymph) cultivation, the fungal cells were observed using the bright field microscopy(Magnification: 1000X).

Fig.6 M. anisopliae in oriental fruit fly's hemolymph for 30 hours

Fig.7 M. anisopliae in cherry coach's hemolymph for 24 hours

Fig.8 M. anisopliae in silkworm's hemolymph for 24 hours

Appressorium development can be clearly observed after 24h induction within the hemolymph of silkworms.

Mcl1 promoter


We designed the primers PMcl1-f(ACGTC//CTGCAG//AATCATGCAGCGCTATGAG, with a PstI site underlined) and PMcl1-r(ATAA//GCGGCCGC//CATGATGGTCTAGGGAACG with a NotI site underlined), according to the PMcl1 sequence[1], to amplify the Mcl1 promoter region with Mcl1 mRNA 5'-untranslated region at the 5' end of the coding region. The whole length is 2772bp.

The gel image below shows that we succeed extracting the Mcl1 promoter and its 5'-untranslated region (99bp downstream the promoter) from the genomic DNA of our chassis organism M. anisopliae ARSEF549.

Fig.9 Amplify PMcl1 from gDNA

Then we digested the DNA fragment with NotI and PstI in order to insert it into the backbone. However, when we ran gel electrophoresis to check the digestion result, we found that there is still one unknown PstI cut site inside the PMcl1 region.

Fig.10 The broken PMcl1 fragment

We decided to sequence this DNA fragment we extracted and mutate the PstI site, but we didn't have enough time to finish our relative vectors construction.

KillerRed expression in M. anisopliae


We constructed a KillerRed expression cassette with a fungal promoter PgpdA and a fungal terminator TtrpC. This cassette was used to confirm that KillerRed can be expressed in M. anisopliae

*The fluorescence images below indicated that KillerRed protein was successfully expressed in M. anisopliae.

As we observed, the growth situations of M. anisopliae KR transformants on media will not be affected greatly since irradiation of KillerRed localized in cell cytosol has a weak effect on cell survival in eukaryotic cells[3].

Surely, one should select some ROS-sensitive intracellular localizations, such as mitochondria, plasma membrane, or chromatin to increase efficiency of KillerRed-mediated oxidative stress. The following two ways have been found to be effective for killing the eukaryotic cells using KillerRed: (1) via an apoptotic pathway using KillerRed targeted to mitochondria, and (2) via membrane lipid oxidation using membrane-localized KillerRed[3].

Under consideration, we decided to fuse a SV40 NLS to the KillerRed protein(BBa_K2040122) so that KillerRed can function in the ROS-sensitive intracellular localizations, the chromatin in nucleus, due to the NLS.

Reference


1. Hygromycin B | Thermo Fisher Scientific

2. Victor Ilyin - Voprosy filosofii i psikhologii - 2015

3. Evrogen KillerRed: Detailed description