Hey Mega,
You've clearly done a lot of good reading, kudos! About the only error there was "saline genes", there's no need to worry about those. Tolerance for salinity is an additives trait for most species, a combination of many genetic and physiological factors.
As to the plan. It's an ambitious goal, that much you ought to know from the outset! It will be much harder to achieve than a regular bacterial transformation, and more expensive.
First thing to consider is how to get the DNA you need. Rather than extracting DNA from vibrio, I recommend
(whoops! ).. I recommend synthesising the DNA. To explain why, let's discuss the "language" of dna. You've heard it's a "universal code" right? That's not entirely true. The amino acid code is universal, although each species has a slightly different set of preferences. However, the rest of the 'code', that which instructs processes such as transcription (and the very first steps of translation), is far less universal. Bacteria and plants have evolved very different codes by now.
Also, bacteria have developed a clever way to automate complex pathways: they combine many protein-coding sequences under one promoter-terminator pair. That mightn't work for plants, and so you might have to cut the sequence up into many sub-genes.
That means that if you use wild vibrio DNA, it may not work until you have altered all of the following at least:
- New promoter
- New ribosomal binding site ("kozak consensus" instead of "shine dalgarno")
- Altering some troublesome codons.
And you may also need to subdivide the genes and possibly add a new terminator.
A lot of work. Years in fact, because biology *that* way is hard and prone to error.
Instead, if you design the."perfect" DNA on a pc and order it from a synthesis company, you will require far less time and effort... But lots more money!
As to agrobacterium, get a lab strain. Trying to recreate the traditional strain from scratch will be almost as much work as the above.! Alternatively look up Cambria, a company / organisation that have developed less patent - laden strains of "I can't believe it's not Agrobacterium!" for sort-of open source use.
Depending on which species you use, getting the DNA into the bacterium may be easier to do chemically. It's really worth reading deep into the literature and seeing what methods are easiest to do. For example if you asked how to transform E. Coli you might be told to use calcium chloride.. But if you read, you learn that peg3350+ mgso4 works great. In other words, Epsom salt and laxative or lubricant! Far easier.
For now that's all I can offer, bit busy over here! There's other stuff to consider to do with the pathways, regulation, etc. Hopefully soon I can help more, could even suggest ways to design the DNA for synthesis.
paper with protocol here:
http://faculty.salisbury.edu/~flerickson/protocols/floral%20dip%20transformation.pdf
Not sure how far this has come for use with other plants, but
basically if you want to avoid doing plant tissue culture to isolate
transformed plant cells, you try to transform the single-celled
embryos in the flowers.
Lots of work as others point out. Mainly because you have to
transform, then grow hundreds or thousands of plants, and check each
to see if they were successfully transformed. Lots of single-celled
embryos will die because the gene insertion is lethal, others may
cause mutations that stunt the plant too badly, others will not be
transformed and just create lots of 'noise'.
Other than the flower-dip, you could construct you DNA then shoot it
into plant cells with a 'gene gun'. Then you would have to dissociate
the plant cells, then dilute the solution enough to dispense one cell
into each of a tissue culture medium. Then screen each cell line for
transformation, when you find a positive, attempt to regenerate the
plant.
Hope this helps!
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Nathan McCorkle
Rochester Institute of Technology
College of Science, Biotechnology/Bioinformatics
Am 04.09.2011 um 22:29 schrieb Mega:
> I'd like to 'create' trees that glow for making a bonsai. I could get
> the lux-codon from vibrio fischerii bacteria extracted from seafish.
> It'll surely be possible to get some agrobacterium tumorfaciens.
I dunno which kind of plant you want to use for the bonsai, but remember that Agrobacterium tumefaciens works best in dicot plants (while you can make it also work for monocots in a lab).
Cheers,
Bastian
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you should start learning how to design a microfluidic device that
would do what you want. You basically need to use a CAD program to
design the fluid traces, and potentially you would have a few layers
that interconnected, not unlike electronic circuit design.
I am working on making microfluidic prototyping easier, but there
aren't designs for the actual fludic systems open/popular online yet.
Shearing bacterial DNA and transforming it into plant cells would be
pretty easy, but you'd need to do it hundreds of thousands of times...
and you'd need to watch the cells grow too to detect if something was
working. That said, sheared DNA will generally only integrate into the
genome if there are some matching sequences on the termini, to get
homologous recombination going. Adding those to your sheared DNA is
also possible... but then the bioluminescent system is probably
relatively new compared to the rest of the organism's metabolism, so
the metabolic pathways to create light might not be found in a sheared
genomic fragment... this would be a problem if intermediary molecules
weren't found in the plant. Getting the DNA to express in a plant is
another problem, which I think Cathal went through pretty well....
Sure plants could mutate the DNA and it could eventually start
working, but that would take meiosis, not mitosis, and meiosis in
plants involves pollen and eggs, which are found in flowers, whole
plants are not in the realm of parallelized microfluidics.
>
>
> "[It's a waste of energy for the] plant" - Well I don't care.
> evolution shall take care of that, because it always does.
>
>
> Well, then I'm going to have a look at fluorescence first.
>
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-cory
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No quorum sensing. It's just the luciferase expressed from pBBR1,
which is a vector compatible with most Gram negative bacteria. Medium
copy number.
> Let's assume I just put this plasmide in an e.coli. Will it just
> become luminiscent?
> Or do you have to grow it on a substrate containing luciferin?
You will need to add luciferin.
-cory
Further, LuxCDE handle reduction of tetradecanoic acid (AKA Myristic
acid) to tetradecanal; the fatty acid precursor is pretty common and
occurs abundantly in species such as nutmeg:
https://en.wikipedia.org/wiki/Myristic_acid
The challenge is to ensure that LuxCDE colocate in a subcellular
fraction where they will encounter lots of tetradecanoic acid, and that
your LuxAB and FMNH2 likewise colocate with the "prepared" tetradecanal.
Perhaps the best route is to get your operon into the bacteria already
present in the plant cell; the chloroplasts. You can either tag each
protein with a chloroplast localisation peptide, which instructs the
plant cell to direct the finished proteins to the chloroplast upon
ribosomal synthesis, or you can transfect the chloroplast itself with
the transgenes.
Plastid transfection can be accomplished at some useful efficiency using
PEG3350 (Miralax):
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-313X.1993.00729.x/abstract
(Locked behind paywall)
Here's a sample protocol using PEG 4000 (Miralax should work), mannitol
and Calcium Chloride:
"All constructs were used to transfect Arabidopsis protoplasts, isolated
from 3 - 5 weeks old Arabidopsis leaves grown under long day conditions
(23°C, 16/8 hr light/dark), essentially as described [40]. Cell density
was adjusted to 2 × 106/ml. 100 μl protoplasts were transfected with 20
μg plasmid DNA in 40% polyethylene glycol 4000, 0.8 M mannitol, 1 mM CaCl2."
From: http://www.biomedcentral.com/1471-2148/10/379
Would it be easy? Hell. No. Tobacco is really easy to engineer compared
to other plants, so you won't know until you try whether the PEG/CaCl
method will work at all in your target species.. and by then, you might
have wasted money on ordering DNA that will work in the target species.
OTOH, in the USA you guys can always get an airgun and modify it into a
crappy biolistics gun to shoot DNA-coated particles at your plants.
There are protocols for coating particles with DNA out there.
It'll be expensive and difficult and it's *not* for beginners, but it's
certainly possible IMHO.
On 05/11/11 03:31, Somebody wrote off-list:
>> This is not true. the LuxCDABE cassette encodes a pathway that produces light independent
> of luciferin. LuxCDE reduce fatty acids to aldehydes, which are oxidized by LuxAB making
> light. LuxAB genes are active alone in making light with the addition of long chain
> aldehydes, such as decanal. See Genbank AF170104
>
> The similar cassette from Photorhabdus luminescens works better than the more common
> cassette from Aliivibrio fischeri, in that it is active at 37C, while the fischeri cassette
> will not function above about 30C.
>
> Neither of these cassettes will likely function at all in plants without a LOT of work.
Which is fine in my opinion; we Irish had a storied history of shooting
one another, and the lack of guns in the public domain mean our police
force is likewise unarmed. It's a nice compromise.
However, this does lead to my focusing on chemical or biological methods
of gene transfection, which is probably good really: given the choice
between a chemical and instrumental route, the former is usually easier
for a toe-dipping beginner to invest in and try out. The latter is often
more reproducible provided everyone's using the same equipment, but
that's not true of a "Make your own Gene Gun!" situation. You'd need the
"OpenPCR of Gene Guns". And patents would probably get in the way of
something awesome along those lines.
and its like the holy-grail for electroporation. Techniques and
reviews of systems, and it even talks about building your own (the
advantages and disadvantages mainly).
"The exponentially decaying wave generator gave high rates of both
uptake and expression; however,
the pulse field strength working range was very narrow. Regardless of
which wave generator is used, it is clear that the
experimental protocol must be optimized for each cell type
that is being examined. The optimization often involves the
use of different electroporation chambers. The cuvette-style
electroporation chamber (13) increases the ease and simplicity
in the handling of cells during electroporation and has evolved
as an industry standard"
from:
http://www.plantphysiol.org/content/99/2/365.full.pdf
Exponential decay is what capacitors do, and I know we've got some
Electrical Engineers active on this list... I'm no electrical expert,
but I think I remember reading that the capacitance changed the time
of decay, so really configurable electroporators basically just have
lots of different sized capacitors.
With some thought and dedication, I think we could build an Open Electroporator.
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I'm not sure that electroporation works well for plants, but I'd totally get behind an open electroporator anyway. For bacterial protocols it'd be amazing.
I'd see this working as a computer plug-in device like OpenPCR, such that the computer can display practical protocol instructions while the user pulses the cells. So, you'd get instructions like an automatic defibrillator; "Cool cells to 4C. Press Forward to continue." -> "Charging. Prepare recovery medium to add post-pulse. Press forward to pulse." -> "Cells pulsed. Add 200uL recovery medium." -> "Incubate cells"... etc. etc.
Because the equipment would be pretty standardised you could easily share protocols. That's not quite so possible with the sorts of crappy equipment people actually use in academic labs in my experience; appart from a few secret-inner-workings devices, the devices I've seen lack standardisation, so it can be hard to mimic someone else's protocol, and ultimately you can't know whether your device generates similar waveforms without splurging money on a waveform analyser. Also, the interfaces tend to be universally awful; the one we used to use in my prior workplace was all dials and click-counters, like a babbage difference engine with several kilovolts of power behind it.
Still, I'll carry on at chemical techniques; the more species you can transform easily with household or pharmacy-bought chemicals, the lower the barrier to entry for n00bs. I was delighted to find PEG3350-as-Laxative for that reason; PEG is essential to transforming Yeast, Plants and E.coli easily.
http://www.wiziq.com/tutorial/41707-Micropropagation-through-Plant-tissue-culture-Detailed-methodolog
http://csm.jmu.edu/biology/renfromh/pop/pctc/tcstart.htm
http://www.wiziq.com/tutorials/plant-tissue-culture
http://aggie-horticulture.tamu.edu/syllabi/689plantbreeding/Assigned%20Articles/Tissue%20Culture%20Applications/Crop%20improvement%20through%20tissue%20culture.pdf
this one is a really good FAQ from Harvard:
http://molbio.mgh.harvard.edu/sheenweb/faq.html
and others from tamu.edu:
http://tinyurl.com/83mqzc7
Both are pretty useless to me: neither are useful and neither is
perennial. Also, neither is a tree. :)
The two standard methods, protoplast chemical
transfection/electroporation and biolistics, seem to cover most species,
but neither seems to cover the lot.
The equivalent of trypsin, which I interpret to mean "the enzyme that
makes protoplasts by digesting the cell wall", would be a blend of
cellulase and pectinase I think. That tends to give you nice
protoplasts, but you have to carefully buffer them with sugars or salts
to prevent lysis (cell explosion).
Once you have protoplasts, it's pretty easy to engineer compatible
species with PEG and a salt, but you can't leave them too long in the
PEG or they tend to lyse. So, not as easy as E.coli transfection, but
somewhere on the same scale certainly.
Actually, one of the big barriers to genetic manipulation isn't gene
delivery, but stable gene integration and expression. Plants don't
support episomal DNA so chromosomal integration is a must, and plants
have defences against viral DNA that tend to shut down "new" DNA at
unpredictable intervals after gene delivery. So you could select for
gene X, and get a lovely glowing plant or whatever, only to find that
Gene X is rendered non-operational within a generation and stays that way.
One way to avoid this is to avoid bacterial CpG methylation; special
strains of E.coli can be used to prepare plasmid DNA that don't use Dam
or Dcm, but those strains are unstable and grow awfully slowly because
of the Dam- phenotype. Another way is to use PCR, which will give
beautifully unmethylated DNA.. although that in itself might be
suspicious to a plant, for all I know.
Of course, avoiding Dam Methylation sites when synthesising your DNA
would be a good thing to try also, in addition to optimising the DNA to
"resemble" plant DNA as closely as you can.
--
Sure, a feature some folks have talked about is having something that
could grow into a house or something large... poplar is fast growing
and a target of genetic investigation... maybe pumpkins would also be
interesting (a la Cinderella's giant pumpkin carriage)
--
A gourd-house consisting of vastly enlarged pumpkins; the biotech
poster-boy that never was.
On 08/11/11 13:45, Nathan McCorkle wrote:
> On Tue, Nov 8, 2011 at 8:24 AM, Cathal Garvey <cathal...@gmail.com> wrote:
>> Well, the two standards are Arabidopsis (grows quickly, convenient size,
>> studied intensively) and Tobacco (really easy to engineer).
>
> Sure, a feature some folks have talked about is having something that
> could grow into a house or something large... poplar is fast growing
> and a target of genetic investigation... maybe pumpkins would also be
> interesting (a la Cinderella's giant pumpkin carriage)
--
That said, it's awesome to see that it worked. And that's with (AFAIK
after a quick skim of the paper) with a basically unoptimised operon;
you could seriously improve that bioluminescence with a little work. As
I mentioned previously, there's lots of work out there in improving
light production by de-coupling transcription of LuxAB from the rest,
and you could probably gain another factorial leap in brightness if you
somehow upregulated fatty acid synthesis in the target cells/organelles.
The university of the first author is about an hour away from me... I'll try to get in contact
Sent from my mobile Android device, please excuse any typographical errors.
Any protocols out there for regenerating Volvox from single-cells?
Because apparently volvox can be seen with the naked eye, just about. So
if you transformed Volvox and regenerated to spheroid colonies, you'd
have a little vial of glowing "motes", which would be pretty attractive
to look at. :)
hmm I like this idea
Nuclear transformation of Volvox carted
http://www.pnas.org/content/91/11/5080.full.pdf
Seems they're photosensitive, could cause problems...:
http://phgoods.info/content/11/8/1473.short
I've attached the full article (INFLUENCE OF THE CELL WALL ON
INTRACELLULAR DELIVERY TO ALGAL CELLS BY ELECTROPORATION AND
SONICATION)
Using C reinhardtii:
"
The primary objective of this study was to test the hypothesis that
electroporation primarily transports molecules across cell membranes,
because its mechanism is known to be specific to lipid bilayer
disruption ( [Jaroszeski et al 2000] and [Weaver and Chizmadzhev 1996]
), whereas sonication transports molecules across both cell membranes
and cell walls, because it nonspecifically disrupts cell-surface
barriers. The data from this study generally support this hypothesis.
The presence of a cell wall significantly reduced intracellular
delivery of BSA during electroporation, but generally did not reduce
BSA uptake during sonication.
"
>
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Scientists found out Gold nanoparticles make plants glow using a
mechanism I yet have to find on articles ion the web.
Copper has the same chemical property as gold becaus it's in the same
'row' as gold. May that be a viable row? To use copper nanoparticles?
Besides, some plants are already fluorescent; loose chlorophyll
fluoresces orange under UV, although with an intact photosynthetic
cascade the energy is handed off to other molecules before it can
fluoresce. Some plants decouple this handover mechanism at times, and
they'd probably fluoresce when this occurs.
Alternatively, mashing up the leaves a bit would achieve the same
result; try shining a UV light on some good green pesto to see this in
effect. The olive oil and basil leaves render good pesto a bit
fluorescent orange.
This plasmid has the complete lux operon and also a ampicilline
ressistance. But now I got some concerns about the amp-r
Couldn't it be that some pathogen bacteria may take the plasmid from
e.coli and get ressistant?
So if one gets ill he maybe cannot be cured with ampicilline and
related substances. Is that true? Maybe kanamycin would be better, but
I don't find a plasmid with it.
Mega: Totally with you on this one. While antibiotic resistance isn't
likely to be an issue with genetically modified plants or animals
(incompatibility with microbes in that encoding format), with bacteria
you can rest assured that they will share DNA when it is convenient.
For that reason, I generally advocate sterilising your cultures *after*
use, so that their contents (DNA etc.) are already starting to degrade
even before disposal. Taking this further, I'm trying to work on
platforms that don't require antibiotics, or at least platforms that use
medically insignificant, legally available antibiotics.
I'm sure it will be said by others so I'll say it now (although the
actions of others are no excuse for sloppiness on our part): The
greatest source of antibiotic resistance is stupid use of antibiotics by
livestock farmers and factory farms. The second greatest source of
resistance is patients abusing antibiotics.
On 19/12/11 17:33, Mega wrote:
> Hey, my newest project is to make e. coli glow with a plasmide called
> pVIB.
>
> This plasmid has the complete lux operon and also a ampicilline
> ressistance. But now I got some concerns about the amp-r
>
> Couldn't it be that some pathogen bacteria may take the plasmid from
> e.coli and get ressistant?
>
> So if one gets ill he maybe cannot be cured with ampicilline and
> related substances. Is that true? Maybe kanamycin would be better, but
> I don't find a plasmid with it.
--
I agree 100% on that... Well my fear was that using ampecillin was
totally ethically incorrect from my point of view.... But as you said,
farmers are abusing them in huge amounts - so if I sterilize
everything, that shouldn't affect mother nature so much...
Do you know whether farmers use ampicillin?
Kanamycin shall be the best antibiotic for transformation: ressistance
is common in bacteria. So when they conjugate and share ressistance
plasmids - that could happen also in nature quite likely. Ampicillin
on the other hand is used as a broad-range (german word translation,
correct i hope) antibioticum.
As my first project i want to make something very impressive, yet non-
pathogen(!) and (in comparison) easy. pVIB seems to be easy because
that is a readily prepared plasmid.
I 'just' have to use a transformation methode and see the results. Of
course, if in pVIB there was kan-r instead of amp-ressistance, it
would be a lot better (in case they escape into the environment, there
would be no danger to anyone)
so you'd mix up a stock solution of ampicillin (they recommend
50mg/mL)... so in 50mL of distilled, sterile water, add 2.5 g
ampicillin
if you make 250mL of LB agar solution, after its been sterilized and
allowed to cool to less than 55 degrees C, you'd add (250mL*100ug/ml)
25mg ampicillin. Since your stock solution was 50mg/mL, you'd add
0.5mL of this stock solution to the media
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