Teman-teman, Ini info lanjutan tentang jagung dan ikan transgenic Dear Friends. further news on transgenic fish and bt corn. ---------- > > Date: Sunday, December 05, 1999 8:35 PM > > about: > 1. New study on Bt: Bt-toxin from transgenic maize seeps into soil > 2. Risks fom transgenic fish > > > > > 1. Insecticide from GM corn seeps into soil - study > > Wednesday, Dec 1 > > LONDON, Reuters [WS] via NewsEdge Corporation : American scientists said on > Wednesday they had uncovered what could be either a potential hazard, or > benefit, of genetically modified corn. > > Dr Guenther Stotzky and researchers at New York University have shown that > BT corn, the seed variety which is resistant to corn borer pests, releases > an insecticide through its roots into the soil. > > The toxin remains in the soil as it is not easily broken down. It retains > its insecticide properties which could help to control pests or promote > insects resistant to the pesticide -- the scientists aren't sure which. > > ``Further investigations will be necessary to shed light on what might > happen underground,'' Stotzky and his colleagues said in a report in the > science journal Nature. > > Their work is the first to show that the toxin from the > genetically-engineered BT corn can seep into the soil. > > ....... > THE TIMES THURSDAY DECEMBER 2 1999 _______ > > GM crop toxin is leaking into the soil > > BV NICK NUTTALL ENVIRONMENT CORRESPONDENT > > SOME genetically modified crops are leaking powerful tox- ins from their > roots into the soil, scientists have found. > > Researchers described the findings as "surprising and un- expected", > raising fresh fears about the environmental im- pact of such crops. > > Companies have modified plants to produce poisons or toxins to combat the > pests that eat their stems and leaves. But the discovery that the same > plants are also leaking toxins into the soil has not, until now, been > considered an issue. > > It will raise fears among some scientists, regulators and environmental > groups that beneficial soil organisms might be killed and that in- sects > living in the soil might be- come resistant to the poisons. > > The findings, published to- day in Nature, have been re- leased by a team > at the Univer- sity of New York that has been studying the roots of GM > maize. > > Several crops, from maize, to corn and potatoes, have been genetically > modified to kill insect pests using a gene derived from a bacterium called > Bacillus thuringiensis (BT). In the United States 15 million acres of corn > modified with the BT gene were planted in 1998 or just under 20 per > > cent of the total crop. GM maize has also been planted in Europe although > the acreage is far smaller. > > Concerns about the impact of such crops on the environ- ment were triggered > earlier in the year when it was found that monarch butterflies had died > after feeding on milk- weed dusted with pollen from GM corn. > > Other research found that lacewings that had fed on corn borers reared on > BT corn had also died, raising concerns that such crops are harming more > than just pests. > > Professor Guenther Stozky, of New York University's labo- ratory of > microbial ecology, who has led the research, said yesterday that the > monarch re- search showed that the toxin was released from the pollen. > > "Now we have found it is also continuously released from the roots into the > soil. The fact that the toxin is re- leased from the roots was unex- > pected," he said. > > Professor Stozky said that the BT toxin was a large pro- tein molecule > which they had considered too large to cross the root membrane. > > During the research, the team grew GM seedlings in the laboratory for 25 > days. Each plant produced on aver- > > age 105 microgrammes of pro- tein and this was tested against larvae of the > tobacco hornworm. Up to 95 per cent of the larvae died after five days with > 50 per cent killed at a dose of just 5.2 micro- grammes of protein. > > Because the roots are con- stantly leaking the toxin, there is also the > risk that pests in the soil might rapidly become im- mune to the poison > triggering new, resistant, strains. > > > Here are some comments by Dr. Charles Benbrook, former Director of the > Board on Agriculture of the US Academy of Science: > > Nature Article re Bt Exudates in Soil > > The December 2, 1999 Nature contains a brief communication entitled > "Insecticidal toxin in root exudates from Bt corn," by Saxena, Flores and > Stotsky, researchers at New York University (full copy in PDF available > from Nature at > <http://www.nature.com/server-java/Propub/nature/402480A0.pdf>. (We will > also post it on Ag BioTech InfoNet under "Environmental Impacts, "Soil > Systems," along with this commentary). > > This report is not likely to generate the attention received by the > much-debated Losey et al. Nature article on Bt-pollen and Monarchs, > although it certainly should. > > In a nutshell, the new report finds that a common current > Bt-transgenic corn variety exudes Bt toxin through root exudates -- > actually, this finding comes as no great surprise, just as the Losey et al. > finding that Bt corn pollen can kill Monarchs was not a surprise. But the > new report and research documents that the activated Bt toxin is exuded > through roots, binds with soil particles, becomes very stable -- persisting > in the soil for 243 days, and that it remains active (i.e. toxic) to soil > insects for very long periods. Hence, Bt toxin from root exudates will be > augmented by toxin in residues from corn plant residues later in the fall > and winter. > > The implications of the findings reported in the new article are > largely unknown but could be enormous. Bt comes from a common soil > bacterium; to the extent that Bt-transgenic crops significantly enhance the > quantity of a particular toxin in soil, there will be impacts on other soil > microorganisms and soil microbial communities. These impacts will, in turn > effect nutrient cycling and uptake, microbial biocontrol of soil pathogens, > and perhaps the development and triggering of the corn plant's immune > system. As the authors point out, some of the effects are likely to prove > positive and some negative. > > These impacts may be transitory and insignificant; it is likely > they will be major in some soils and systems and not in others; they may > prove short-lived and highly cyclic, or they may build overtime, reaching a > point in some fields where major and sustained shifts occur in soil > microbial communities. They may prove modest compared to the impact of > tillage; they may reinforce some of the adverse impacts of tillage, or > actually prove a bigger problem in no-till systems. > > The second reason that the paper is so important is that the next > major EPA review of a GMO corn is about to get underway, with commercial > introduction planned for crop season 2002, if regulatory approvals are > received in time. The new variety is being developed by Dow AgroSciences > in cooperation with Pioneer and has been engineered to express a Bt toxin > in corn root systems and exudates at levels high enough in order to control > the corn rootworm complex, by far the toughest, nastiest set of insect > pests corn farmers have to manage. > > Resistance management will again be a major concern, and again the > high dose strategy will almost certainly be a cornerstone of the strategy > deployed and the evidence advanced by the company in support of approval. > There has been no public discussion or scientific community appraisal of > what a Bt-toxin "high dose" for corn rootwrom management will be, but rest > assured it will be two or more orders of magnitude higher than the levels > analyzed in the just published Nature piece. > > Proponents of the new Bt-corn technology will correctly point out > that corn rootworms are damaging pests in second year corn fields (i.e. a > field planted to corn two or more years in a row). In most parts of the > corn belt, rotation with soybeans remains an effective cultural practice > that lies at the heart of corn rootworm IPM systems, and has for 30 years. > But the plot has thickened in recent years -- a new strain or subspecies of > the western corn rootworm has adapted around rotation and is causing > economic damage in some first year corn fields in parts of the corn belt. > Its range is expanding every year and insecticide applications for corn > rootwrom control are clearly rising. (For a detailed discussion of this > adaptation and overview/references/links to key University of Illinois > research on this new problem, see Section D, "Evolving Insect Pest > Challenges," page 17 in the January 1999 paper "World Food System > Challenges and Opportunities: GMOs, Biodiversity, and Lessons from > America's Heartland," accessible at <http://www.biotech-info.net/IWFS.pdf>). > > Until recently, most of the soil insecticides used to control corn > rootworms have met everyone's definition of nasty. Highly toxic carbamate > and organophosphate insecticides accounted for the lion's share of acres > treated and pounds applied. Most farmers hate handling these > insecticides; they pose significant risks to birds, fish, pets, and a range > of beneficial organisms. In the last two years, two much safer new > insecticides have come on the market. A synthetic pyrethroid product > marketed by Zeneca called Force (active ingredient, tefluthrin) is getting > rave reviews by farmers and may soon emerge as the product of choice. From > an environmental perspective, it is far, far less damaging than the OP and > carbamate insecticides it is replacing. > > EPA's review and approval decision on the new Bt-corn for rootwrom > control is going to really put the agency to the test. Without a doubt, > there will remain major unresolved issues regarding resistance management > and soil microbial community and plant health impacts. In addition, there > will be major debates about the actual "benefits" of the technology in > light of the availability of cost-effective alternatives. > > In the meantime and hopefully prior to approval, information is > needed on the exact toxin expressed in roots; the level of expression and > the temporal dynamics of expression, along with levels in plant tissue and > residues; its fate in soil ecosystems under different tillage and planting > systems; the impact of the Bt toxins on various beneficial and pathogenic > soil microorganisms and arthropods/decomposers. This information will be > among that needed in order to determine whether this technology might lead, > on balance, to sustained and significant adverse impacts on soil quality > and plant health. > > As the authors state, what goes on underground in a field planted > to today's Bt-corn varieties is largely a mystery. Enhance the toxin > levels 100- to 1,000-fold and it becomes a mystery of some consequence and > immediacy. > > chuck benbrook > > > > Charles Benbrook CU FQPA site www.ecologic-ipm.com > Benbrook Consulting Services Ag BioTech InfoNet www.biotech-info.net > 5085 Upper Pack River Road IPM site www.pmac.net > Sandpoint, Idaho 83864 > 208-263-5236 (Voice) 208-263-7342 (Fax) > > > > 2. Transgenic fish > > Wednesday December 1, 12:01 AM > > Source: Proceedings of the National Academy of Sciences (vol 96, p 13 853) > (From New Scientist <http://www.newscientist.com>, 4/12/99) > > Today's News > > Could one genetically modified fish invade a species and destroy it? > > By Matt Walker > > A SINGLE genetically modified fish could turn Darwinian evolution upside > down and wipe out local populations of the species if released into the > wild, biologists warn. They add that other organisms could face the same > risk from transgenic relatives. > > William Muir and Richard Howard of Purdue University in West Lafayette, > Indiana, made the discovery while modelling ecological risks associated > with genetically modified organisms (GMOs). They have dubbed their idea the > "Trojan gene" hypothesis. "This resembles the Trojan horse," says Muir. "It > gets into the population looking like something good and it ends up > destroying the population.". > > The researchers studied fish carrying the human growth hormone gene hGH, > which increases growth rate and final size. Biologists in the US and > Britain are experimenting with salmon engineered in a similar way, although > no one has yet begun commercial production. > > Muir and Howard included hGH in embryos of a fish called the Japanese > medaka (Oryzias latipes), a common aquarium fish that is widely used in > research. They found that modified individuals became sexually mature > faster than normal fish and produced more eggs. > > Other experiments using non-modified fish also showed that larger males > attracted four times as many mates as their smaller rivals. This effect is > also known in salmon. Muir predicts that bigger, engineered fish would > enjoy the same advantages. So the hGH gene would quickly spread through a > fish population. > > But Muir and Howard also found that only two-thirds of engineered medaka > survived to reproductive age compared with wild medakas. So the spread of > the growth hormone gene could make populations dwindle and eventually > become extinct. > > To quantify this, the researchers plugged their results into a computer > model to find out what would happen if 60 transgenic individuals joined a > wild population of 60 000 fish. The population became extinct within just > 40 generations. Even a single transgenic animal could have the same effect, > they found, although extinction would take longer. > > "You have the very strange situation where the least fit individual in the > population is getting all the matings--this is the reverse of Darwin's > model," says Muir. "The sexual selection drives the gene into the > population and the reduced viability drives the population to extinction." > The researchers say their results are the first evidence that GMOs could > have catastrophic consequences on their own species. > > > -= Dual T3 Webhosting on Dual Pentium III 450 - www.indoglobal.com =- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Archive: http://www.mail-archive.com/[email protected]/
