1,721,024 research outputs found
TELL ME WHO YOUR FRIENDS ARE AND I'LL TELL WHAT GENE YOU ARE
No full textMetabolic control analysis has several interesting implications for (plant) biotechnologists, the main one being that the parallel activation of enzyme activities is the best strategy to modulate metabolic fluxes. We explored publicly available expression data from microarray measurements (Affimetrix) of Arabidopsis thaliana to highlight the parallel activation of transcripts. We analysed mainly genes coding for enzymes or signal transduction players and shall provide one example each (Menges et al. (2008) New Phytologist 179: 643–662 and Beekwilder et al. (2008) PLoS ONE. 3:e2068).
I demonstrate that correlation analysis can be a powerful tool for gene function discovery, at least in several specific cases. The method’s limitations and the reasons for failing in providing predictions for many other genes are discussed. Apart from trivial causes (mRNA does not equal protein and protein does not equal activity), the limited spatial resolution of the collected samples and the limited temporal resolution of the statistical analysis are presumably the main reasons for the low success rate. This leaves, however ample room for improvement.
Finally, a plea for a different perspective of control in metabolic pathways is put forward (Morandini P. (2009) Rethinking Metabolic Control, Plant Science, 176:441-45)
Biotechnology for agriculture and regulation: friends or foes?
No full textThe conditions for a friendly regulation to foster agricultural biotechnology are discussed in the contest of a water scarce agriculture and mainly focussed on horticultural crops. An instructive example for the potential of Ag-biotechnology to Kuwaity agriculture is discussed (a pest resistant celery)
Tell me who your friends are and I'll tell what gene you are: coregulation analysis on microarray data from Arabidopsis
No full textLa regolazione dei flussi metabolici non può essere discussa senza considerare la termodinamica delle reazioni enzimatiche implicate. Reazioni vicino all'equilibrio richiederanno enzimi con grandi Vmax, mentre reazioni lontane dall'equilibrio richiederanno Vmax poco superiori al flusso nella via. Questo significa che gli aumenti di flusso saranno mediati spesso da aumenti/attivazioni parallele di enzimi. Ne consegue che la coregolazione dei trascritti può essere un utile strumento per analizzare la funzione dei geni coinvlti nel metabolismo. Saranno discussi alcuni esempi paradigmatici e la validità generale dell'approccio
Control limits for accumulation of plant metabolites : brute force is no substitute for understanding
No full textWhich factors limit metabolite accumulation in plant cells? Are theories on flux control effective at explaining the results? Many biotechnologists cling to the idea that every pathway has a rate limiting enzyme, and target such enzymes first in order to modulate fluxes. This often translates into large effects on metabolite concentration, but disappointing small increases in flux. Rate limiting enzymes do exist, but are rare and quite opposite to what predicted by biochemistry. In many cases however, flux control is shared among many enzymes.
Flux control and concentration control can (and must) be distinguished and quantified for effective manipulation. Flux control for several ‘building blocks’ of metabolism is placed on the demand side and therefore increasing demand can be very successful, while tampering with supply, particularly desensitizing supply enzymes, is usually not very effective, if not dangerous, because supply regulatory mechanisms function to control metabolite homeostasis. Some important, but usually unnoticed, metabolic constraint, shape the responses of metabolic systems to manipulation: mass conservation, cellular resource allocation and, most prominently, energy supply, particularly in heterotrophic tissues.
The theoretical basis for this view shall be explored with recent examples gathered from the manipulation of several metabolites (vitamins, carotenoids, aminoacids, sugars, fatty acids, polyhydroxyalkanoates, fructans and sugar alcohols). Some guiding principles are suggested for an even more successful engineering of plant metabolism
Piante transgeniche per uso mangimistico: quantità importate e rapporto rischi/benefici
No full textVengono presentati i dati di importazione delle principali commodities agricole (soia e mais) di cui esistano varietà transgeniche in commercio e i paesi da cui queste importazioni provengono, con i relativi tassi di adozione dei transgeni. Sono discussi i rischi e benefici della loro adozione o non adozione
Inactivation of allergens and toxins
No full textPlants are replete with thousands of proteins and small molecules, many of which are species-specific, poisonous or dangerous. With time humans have learned to avoid dangerous plants or inactivate many toxic compounds in food plants, but there is still room for improvement. The capacity, offered by genetic engineering, of turning off (inactivate) single genes in crop plants has opened up the possibility of altering the plant content in a far more precise manner than previously available. There are several tools to inactivate genes (classical mutagenesis, antisense RNA, RNA interference, post-transcriptional gene silencing, insertion of transposons and other genetic elements) each one with a mixture of advantages and disadvantages (speed, costs, selectivity, stability, reversibility, regulatory regime). There are different level at which to intervene (genes coding for toxins, allergens, enzymes, transporters or regulators), each one suited for a specific problem, and there are different problems to address. We will describe interventions to ameliorate food crops in terms of their content in allergens and toxins, especially in their edible parts, providing some paradigmatic examples. It will be stressed that reducing the content of natural toxins is often a threshold issue (“the dose makes the poison”) and a trade-off process: the least the content of natural toxins, the higher the susceptibility of a plant to pests and therefore the stronger the need to protect plants in field conditions. This has interesting consequences on the domestication process and the development of new pesticides to counter plant pests
Public researchers’ experiences with GMO regulations
No full textBuilding on the preceding presentations, Dr. Morandini underlined that genetic
modification in plants is a tool with the same goal as conventional breeding: to develop better varieties for farmers, the environment and consumers. As many other
tools, genetic modification is neither inherently risky nor safe. GM crops approved to
date are as safe as, or safer than, conventional crops and have demonstrated
environmental and other benefits.
PRRI supports biosafety regulations that allow authorities to make informed and
balanced decisions in order to maximize the benefits of biotechnology and minimize
risks. Biosafety regulations must therefore be transparent, science based,
proportionate and predictable. A PRRI survey shows that public researchers in many
EU countries experience that the current regulatory situation often unduly hinders
research. This is particularly felt in field research. Field trials are an essential stage in
the development of new varieties. Problems are experienced with the EU regulatory
system, the way in which the EU system is transposed into national regulations and
the way in which EU and national rules are executed in practice. Examples of
problems are: Regulations that stay too long in draft form; provisions that are
inconsistent with the EU system; restrictions or bans that lack scientific basis; fees
that are prohibitive for public research; undifferentiated information requirements;
requirements to publish locations of field trials that result in destruction of research;
no mechanism for exemptions on EU level; conflicting interpretations and policies
between different bodies; requests for additional data that have no basis in risk
assessment; ignoring the advice of the scientific bodies such as EFSA; decisions not
taken within the legal time frames; disproportionate or unworkable conditions in
permits; mandatory insurance, ineffective government action against destruction of
field trials. The consequences of these challenges is that research is becoming
increasingly expensive due to costs for additional requests for data and for security
measures, important research does not get beyond the greenhouse stage, and
important research and safety data are often lost because of the destruction of field
trials. Consequently, as was illustrated by a number of examples, much needed public
research is increasingly and unnecessarily delayed, ended, moved abroad or not
started at all.
PRRI offers the following recommendations:
- EU Member States should adhere to the rules they themselves created, e.g.
decisions within the time frames, and based on scientifically sound risk
assessment. Scientifically sound means looking at the whole of the scientific
data available, not only at hand picked cases.
- Additional data should only be requested if they are pertinent to the risk
assessment.
- Remove unqualified bans from regulations.
- Permit conditions should be proportionate to risk.
- Environmental benefits should be taken into account.
- Establish differentiated procedures.
- React effectively to destruction of field trials
- When amending the EU regulatory system: Re-introduce mechanisms for
simplified procedures and introduce a mechanism for exemption of categories of GMOs that are not likely to have adverse impacts, such as certain pest resistant crops
Domestication of new species
No full textDomestication is the process through which a wild plant becomes a crop. The process is the result of the selection, either deliberate or as a byproduct of agricultural practices, of characteristics favorable to human beings. The sum of such characteristics is usually described as the ‘domestication syndrome’ because the types of traits selected are often shared among many different species. The most commonly selected traits are loss of seed dispersal, reduced seed dormancy, changes in growth habit, flowering time, and gigantism, all of which have an impact on morphology, reproductive strategies and, most importantly, production (yield and harvest index). Depending on the plant and its use, other traits could be selected, such as reduction or loss of toxic compounds, winter hardiness, nutritional quality, etc. Most domestication took place in ancient times, but there are a few examples of recent and accelerated domestication, for instance sugar beet. It is now possible to achieve the domestication of new species, based on the deliberate induction and combination of traits, using a set of approaches: classical plant breeding via hybridization and selection (including wide area crosses, hybrid seeds and plant cell culture), coupled with molecular tools such as Marker Assisted Selection, transgenesis, and site directed mutagenesis. Examples of interesting traits as well as candidate crops are discussed. Thus, we have the means to repeat the achievements of the early domestication wave and do even better, but this requires drastic changes in international and national regulations impacting on plant biotechnology and novel breeding techniques
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