| GMOs and Scientific Aspects |
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| Written by HH | |
| Wednesday, 05 May 2010 | |
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Some people claim that GMOs are similar to the hybrid species obtained thanks to plant breeding, that the former are no more dangerous than the latter. What is your opinion on this? “GMOs go right through the genetic barrier between species, genes are randomly introduced in animals or plants; or rather, fragments of artificially synthesized genes, often inspired by viruses or bacteria. In fact, an infinite number of combinations is now possible. We no dot master the effects of the introduced modification and we have no hindsight on the secondary modifications that can occur in the metabolism. Whereas hybridizations occur between compatible varieties: between maize varieties, or between canola varieties. They occur naturally, even if in the last few years, they were produced by man on purpose, they are part of the history of agriculture as it has been practiced for the last 11,000 years.” What are precisely your arguments to demonstrate that the development of second generation GMOs rests on the success of the ones commercialized currently? “Both the necessary financial resources and what the manufacturers say about it. The first generation GMOs need to become profitable so that investing can continue (see the CRIIGEN’s Index Cards on second generation GMOs).”
The GMOs that are useful in medicine are produced in sealed environments: from yeasts used in fermentors, from bacteria, and often from plants grown in greenhouses in pharmaceutical factories. They are not disseminated everywhere round the world over 40 million hectares like agricultural GMOs. Their purpose is more obvious: for example with recombinant insulin. Finally the products made from these GMOs are evaluated just like other medicines, this could certainly be improved, but they are prescribed under medical control and therefore with a certain traceability. On the contrary, agricultural GMOs and pesticide plants are not systematically tested on mammals, nor are they tested as pesticides. They are therefore more dangerous”.
Your are worried that the GMO seed manufacturers might eventually possess “the agro-business weapon”, what do you mean?
“Genetic engineering consists in deciphering the genomes, with a view to know the genetic inheritance of species, todetermine the function of each of the genes discovered, and possibly to use these findings to modify the species in order to get them to produce something specific. For this new technology to be ‘profitable’, the possibility of genetic modification was associated to the patenting of genes and therefore to the patenting of plants and animals. Therefore introducing a GMO in the United-States means first and foremost being able to patent an agricultural variety. If, like Monsanto or Syngenta, you try to patent most rice, maize, soy varietals, registered in the seed catalogue, because you manufacture GMOs, you become the ruler of the quoted prices on the cereal exchange, the chief of global food who will decide who grows what on the globe. Especially if the varietals in question have a lab-induced sterility (such as the ‘Terminator’)”.
What are, according to you, the main advantages of Second Generation GMOs? Are there only quality aspects? “Second generation GMOs are not the majority, in this respect. Even present trials still include 2/3 of first generation GMOs in pre-commercialization. It will take at least another ten years for them to be commercialized, and they are in no way an excuse or an alibi to accept or refuse the present GMOs. They will need to have their own added value and will probably remain a minority. Unsuccessful attempts are conducted to try and modify food quality and production, mostly in animals. We will see on an individual basis, when they exist; however, they are completely irrelevant in the present debate.”
“The genetic constructions can be considered like patentable inventions, but not the genes which are rather of the discovery type. Once the genetic constructions are integrated in live organisms, the organisms and their reproduction should not be protected by patents, since the vast majority of the genetic inheritance of modified live beings does not belong to individuals or groups.”
“If we import GMOs without any identification mixed with non-GMOs and if we grow GMOs in poor isolation conditions, it poses a problem, like today. These conditions were negotiated in the 1980’s, according to the principles of the WTO Agreements. However it is quite logical to organize a GMO distribution channel, if these new products offer an added value. The viability of the project for separating the GMO and the non-GMO production and distribution channels has started. Contaminations are inevitable at present, just like contaminations with pesticides. And since a new type of pollution has been invented, its background noise can be, however, reduced to a minimum. This is the meaning of the future worldwide regulations on GMO labelling."
“The identification and the location of the genes of interest on a genetic map makes it possible to trace the presence of a transgene through generations of plants for example, its transmission, the stability of its location, and therefore its potential regulation by the surrounding DNA… Furthermore, the identification and isolation by cloning of a new gene gives new ideas for transgenes”.
“It depends on the number of copies of a gene in a gene family. For example for the cytochrome P450 genes that I am studying, there are about 80 of them in mammals and even more in plants! The double or triple knockout is barely tackled in research… Of course more transformations will be necessary to achieve it!
In all your questions, you are mixing up research and applications. For research, just one genetically modified individual can be almost enough (or maybe just a few can help understand the new roles of crucial genes), but for applications, obtaining a lineage is another matter, in terms of time and effort… So strictly speaking, mutagenic methods are used with transgenesis, since a mutation is induced. If this creates a genetic instability in the plant’s line of descent, if recombinations are favoured because of the introduced viral sequences, it depends on the sequences and the chromosomal location into which they are introduced. If they were introduced randomly (as is the case with GMOs today), they would have chances of coming up against a fragile chromosomal site, and of recombining with dormant viral sequences that already exist, and of reactivating them, and so on and so forth… Outside of transgenesis, mutagenic methods are also used to create some commercialized plants and obtain some mutations.”
Does the Southern test really correspond to a molecular hybridization? “In order to obtain a Southern blot, a molecular probe is hybridized (and then revealed later) with a genomic fingerprint (the DNA is separated by electrophoresis). Do not confuse this with the hybridization of organisms, or plants…”“In order to obtain a Southern blot, a molecular probe is hybridized (and then revealed later) with a genomic fingerprint (the DNA is separated by electrophoresis). Do not confuse this with the hybridization of organisms, or plants…”
“What is really new, is the extent of this phenomenon and how it is exploited with GMOs. The several millions of hectares cultivated in a few years are multiplying the risks of absurd GMO behaviours. That some gene exchange occurred between unrelated species in rare cases (mostly transposons) over a few billion years has nothing to do with it… On the scale of evolution and transformation of species.”
In genetic engineering, transposons are of interest for their ability to excise, insert and stabilise new mutations. What is meant by this last claim? “A transposon has the ability of coding for an enzyme (either reverse transcriptase, or transposase) capable of “constructing” new stable genes by reintegrating DNA sequences or a genome (coming from endogenous RNAm or other). Therefore they induce mutations, which are not temporary in that case.”
Do regulator sequences of gene expression depend on the kingdom (or the species)? “Yes, that is very often the case. But there are more universal consensus sequences (like the CaMV 35S promoter, precisely).”
Are they included in genetic constructions carried out before the transfer of the gene of interest? “It depends on the GMO generations you are talking about”.
When genetic construction is under way, can you say that there is a genetic recombination between the different united elements (in the sense of the definition: genetic rearranging occurring in vitro between DNA fragments from various origins or between non-contiguous DNA fragments)? “Yes, before and after the insertion, most transgenes in commercialized GMOs are Chimeric (coming from several organisms), or synthetic”.
What is the success rate of transgenesis? “It is very weak, it depends on the species transformed and the methods".
Some talk about extremely powerful promoters and catalysts used to force the transgene to express itself. What are they precisely talking about? They also talk about the horizontal transfer of genes: what are the elements that do this naturally except for viruses and transposons? Is this transfer really limited by the species barriers and the cellular defence mechanisms? Why do transgenes increase the frequency of such transfers? “They are alluding to viral promoters, which play a control sequence role for many transgenes (catalysts is inappropriate in that sense). The transgenes are supposedly increasing the frequency of such horizontal transfers because of the virus sequences which can be hot spots in recombinations, excisions and transpositions… It is a distinctive feature of viruses to be transmitted from individual to individual through horizontal transfer… A theory even says that viruses phylogenetically stem from retrotransposons.”
Can the antisense strategy be assimilated to transgenesis? “Not if you are talking about antisense oligonucleotides. (However, the transgenesis of genes can be included in an antisense direction.)"
Which vectors are used for that type of operation and are there particular consequences for the plants thus transformed? “For example, PEI for oligonucleotides. This is what we use in the laboratory for the transfection of animal cells. The consequences need to be prudently assessed individually.”
Doesn’t the co-evolution concept make it possible to tell whether the creation of new viruses within the framework of transgenic plants might lead to unpredictable situations and it is therefore impossible to claim that situation is the same than with traditional plants? “Yes. With or without the co-evolution concept.”
Are the tests preceding the commercialization of a transgenic plant sufficient to apprehend the instability of the lineage?
“No.”
Is modified starch synonymous with genetically modified starch?
"No, not necessarily. The modification can be chemical and not necessarily genetic.” |
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| Last Updated ( Friday, 14 May 2010 ) |
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