shunshine88
Senior Member
Mình đang cần tài liệu về quá trình tạo cây cà chua này 
mong mọi người giúp đỡ nha
mong mọi người giúp đỡ nha
Cây cà chua FLAVR SAVR
- Thread starter shunshine88
- Start date
-Gen được chuyển vào cà chua Flavr-Savr TM là gen có tác động cho trái cà chua chín chậm, giúp trái cà chua có thời gian sử dụng lâu hơn và có nhiều thuận lợi cho nhà sản xuất và người tiêu dùng, giúp giảm đáng kể nhiều thiệt hại sau thu hoạch. Trái cà chua chuyển gen có độ cứng cao hơn quả thông thường do đó nó không bị thối dập trong khi di chuyển, kéo dài được thời gian trên thị trường cũng như thời gian sử dụng mà trái cà chua vẫn đảm bảo chất lượng.
Giống cà chua mới có chứa hàm lượng beta-carotene cao
History of the FLAVR SAVR Tomato
Normal tomatoes grown commercially cannot be allowed to ripen on the vine because they soften during the ripening process. Picking them while they are still hard allows them to be shipped, but it also prevents the development of natural flavors. Therefore, supermarket tomatoes generally have little flavor. Scientists at Calgene, Inc. began research in the 1980’s on the FLAVR SAVR tomato, a tomato that would not soften while ripening and could, therefore, be left on the vine until it ripened naturally. To create the transgenic tomato, a gene from E. coli (a bacterium which occurs naturally in the mammalian gut) called kan(r) and the FLAVR SAVR gene (from a tomato) were inserted into a plasmid (a circular ring of DNA) and plasmids like these were inserted into a group of tomato cells in a growth medium containing an antibiotic (Engel 77). The kan(r) gene, when established in the cell, produced a substance called APH (3’) II that gave the cell resistance to the antibiotic. The antibiotic killed cells that did not receive the plasmid. The purpose of the bacterial gene was, therefore, to identify the cells that were genetically transformed. The FLAVR SAVR gene coded for a strand of RNA that was the reverse of a strand of RNA that naturally occurs in the plant. The original RNA strand in the plant is responsible for the production of the enzyme polygalacturonase. Polygalacturonase breaks down pectin in the cell walls of the tomato during the ripening process and causes the entire tomato to become soft (Engel 77). The complementary strand of RNA from the FLAVR SAVR gene binds to the polygalacturonase RNA and the two strands "cancel each other out," preventing the production of polygalacturonase and the softening of the tomato (Engel 77). (For a brief discussion of the relationships between DNA, RNA, proteins, enzymes, and substrates and a diagram of the function of the FLAVR SAVR gene, see Appendices A and B respectively.)
The finished product, the FLAVR SAVR tomato, could be allowed to fully ripen on the vine and develop a more homegrown flavor. However, the introduction of the FLAVR SAVR tomato into the market in the mid-1990’s created a good deal of controversy and consumer resistance. Much of the hype surrounding genetically altered crops was created by public misperceptions and fears of "mutant veggies" that were encouraged by various organic and environmental groups. However, the safety of new substances introduced into a food product was a real issue that was brought to the attention of the government and the public. However, after extensive safety research by Calgene and dialogue with the FDA, the FDA found Calgene’s tomato to be safe and approved the FLAVR SAVR tomato on May 17, 1994 (Engel 74).
Transgenic Tomatoes: Are They Safe?
The Calgene Company performed extensive safety and environmental impact tests under the scrutiny of the FDA to assure the public that its transgenic tomato was indeed safe to eat. The company tried to address any relevant concerns that might be associated with eating this genetically altered tomato. Some of the concerns that Calgene’s research addressed are discussed below.
So What?
Although the main benefit of the FLAVR SAVR tomato is improved flavor for the consumer, the possibilities genetically engineered crops are nearly limitless. Plants can be created that resist spoilage, insect or fungal attacks, or less than ideal weather conditions (as in the case of the antifreeze strawberries) or even create chemicals that can be extracted from the plant tissues and used as pharmaceuticals. Also, the need for clearing new farmland and using pesticides could be reduced if the use of genetically engineered crops became more widespread. However, not all people see genetic alteration of plants from this perspective. One ironic example of resistance to genetically engineered crops came from the Environmental Protection Agency. In a bizarre bureaucratic move, the EPA has designated certain insect resistant crop plants as "pesticides, " thus requiring that they be regulated like chemical pesticides are although there is a tremendous difference between a plant that can make itself not tasty or toxic to insects and man-made chemical pesticides (Nettleton 20). This arbitrary distinction is costing small biotechnology companies thousands of dollars in regulatory costs (Nettleton 20). Groundless bureaucratic decisions such as this reflect the lack of understanding that the government as well as the general public has about biotechnology. The success of the FLAVR SAVR tomato under rigorous testing by Calgene under the watchful eye of the FDA demonstrates that genetically engineered crops have the potential to be safe for human consumption and for the environment. Transgenic plants ought to be tested for safety and regulated by the FDA, but considering the possibilities that the genetic engineering of crops offers and that a demonstrably safe genetically engineered crop (the FLAVR SAVR tomato) has been developed, the public and the government should set aside their concerns, educate themselves on this issue, and give genetic engineering a chance.
Appendix A
DNA is a double stranded molecule that directs the synthesis of proteins in living organisms. The protein synthesis that occurs in a cell ultimately determines the unique characteristics of that organism. The strands of DNA are composed of thousands of nucleic acids stringed together in particular sequences. A particular sequence of nucleic acids on the DNA molecule codes for the particular sequence of amino acids in a particular protein. When a cell needs a particular protein, the part of the DNA strand that codes for that particular protein "unzips" and allows nucleic acid "pieces" floating in the nucleus of the cell to bond to the exposed nucleic acids in the DNA strand. When the entire new strand of nucleic acids is formed, the new strand, called mRNA, is removed, and the DNA strands "rezip." The mRNA strand will then float through the cell to special protein synthesizing structures called ribosomes and act as a template for production of the protein. As the mRNA passes through the ribosome, it will interact with molecules bearing specific amino acids called tRNA. As each specific tRNA binds to the mRNA, the amino acids will form a string, and the tRNA molecules will be released into the cell. When this string of amino acids is completed, it is called a protein. Some proteins provide structure in living things (such as the protein in muscle tissue), while others can promote certain chemical reactions in cells (such as the breakdown of pectin in tomato cell walls).
The above information was taken from Biology, Neil Campbell, et. al., New York: Addison Wesley, 1999, p.316.
Works Cited
Campbell, Neil et. al. (1999). Biology. New York: Addison Wesley
Engel, Karl-Heinz et al., editors. (1995). Genetically Modified Foods: Safety Aspects,
Washington, DC: American Chemical Society.
Nettleton, Joyce. (1999, January). Wedging Science into Public Policy, Food Technology,
p. 20.
Wilson, Edward O. (1999). The Diversity of Life. New York: W. W. Norton & Company.
Giống cà chua mới có chứa hàm lượng beta-carotene cao
History of the FLAVR SAVR Tomato
Normal tomatoes grown commercially cannot be allowed to ripen on the vine because they soften during the ripening process. Picking them while they are still hard allows them to be shipped, but it also prevents the development of natural flavors. Therefore, supermarket tomatoes generally have little flavor. Scientists at Calgene, Inc. began research in the 1980’s on the FLAVR SAVR tomato, a tomato that would not soften while ripening and could, therefore, be left on the vine until it ripened naturally. To create the transgenic tomato, a gene from E. coli (a bacterium which occurs naturally in the mammalian gut) called kan(r) and the FLAVR SAVR gene (from a tomato) were inserted into a plasmid (a circular ring of DNA) and plasmids like these were inserted into a group of tomato cells in a growth medium containing an antibiotic (Engel 77). The kan(r) gene, when established in the cell, produced a substance called APH (3’) II that gave the cell resistance to the antibiotic. The antibiotic killed cells that did not receive the plasmid. The purpose of the bacterial gene was, therefore, to identify the cells that were genetically transformed. The FLAVR SAVR gene coded for a strand of RNA that was the reverse of a strand of RNA that naturally occurs in the plant. The original RNA strand in the plant is responsible for the production of the enzyme polygalacturonase. Polygalacturonase breaks down pectin in the cell walls of the tomato during the ripening process and causes the entire tomato to become soft (Engel 77). The complementary strand of RNA from the FLAVR SAVR gene binds to the polygalacturonase RNA and the two strands "cancel each other out," preventing the production of polygalacturonase and the softening of the tomato (Engel 77). (For a brief discussion of the relationships between DNA, RNA, proteins, enzymes, and substrates and a diagram of the function of the FLAVR SAVR gene, see Appendices A and B respectively.)
The finished product, the FLAVR SAVR tomato, could be allowed to fully ripen on the vine and develop a more homegrown flavor. However, the introduction of the FLAVR SAVR tomato into the market in the mid-1990’s created a good deal of controversy and consumer resistance. Much of the hype surrounding genetically altered crops was created by public misperceptions and fears of "mutant veggies" that were encouraged by various organic and environmental groups. However, the safety of new substances introduced into a food product was a real issue that was brought to the attention of the government and the public. However, after extensive safety research by Calgene and dialogue with the FDA, the FDA found Calgene’s tomato to be safe and approved the FLAVR SAVR tomato on May 17, 1994 (Engel 74).
Transgenic Tomatoes: Are They Safe?
The Calgene Company performed extensive safety and environmental impact tests under the scrutiny of the FDA to assure the public that its transgenic tomato was indeed safe to eat. The company tried to address any relevant concerns that might be associated with eating this genetically altered tomato. Some of the concerns that Calgene’s research addressed are discussed below.
[*]All New Substances in the FLAVR SAVRä Tomato have been Tested and Demonstrated to be Safe
[*]Transgenic Tomatoes have Comparable Nutritional Values to Normal Tomatoes Changing the genome of a particular crop plant could theoretically alter the amounts of various nutrients that the plant would pack into parts one would eat. However, in the case of the FLAVR SAVR tomato, no significant alteration of nutrient quality was detected (Engel 78). The amounts of major tomato vitamins (Vitamins A and C), minerals (calcium, magnesium, phosphorus, and sodium), and protein were not shown to be significantly different from the amounts of these substances in normal tomatoes (see Table One).
Table 1: Comparison of Ranges of Nutrients Between Transgenic and Normal Tomatoes (per 100 g Fruit)
Nutrient
Normal Range
Transgenics
Controls
Protein
Vitamin A
Thiamin
Riboflavin
Vitamin B6
Vitamin C
Niacin
Calcium
Phosphorus
Sodium
0.85 g
192-1667 IU
16-80 m g
20-78 m g
50-150 m g
8.4-59 mg
0.3-0.85 mg
4.0-21 mg
7.7-53 mg
1.2-32.7 mg
0.75-1.14 g
330-1660 IU
38-72 m g
24-36 m g
86-150 m g
15.3-29.2 mg
0.43-0.70 mg
9-13 mg
25-37 mg
2-5 mg
0.53-1.05 g
420-2200 IU
39-64 m g
24-36 m g
10-140 m g
12.3-29.2 mg
0.43-0.76 mg
10-12 mg
29-38mg
2-3 mg
Note: For Table 1, the "Normal Range" represents values that the researchers looked up in standard references. The "Controls" column represents actual amounts of nutrients found in non-transgenic (traditional) varieties grown by the researchers alongside the transgenic varieties.
Also, it was shown that levels of the naturally occurring toxins tomatine and solanine were not any higher in the transgenic tomatoes than they were in the natural varieties (see Table Two).
Table 2: Comparison of Tomatine Levels Between Transgenic and Controls Tomatoes (per 100 g fruit)
Fruit Stage
Transgenics
Controls
Green
0-8.79 mg
0-6.48 mg
Red
0-1.09 mg (A)
A- Only 1 of 38 fruits had detectable tomatine.
0-2.31 mg (B)
B- Only 4 of 60 fruits had detectable tomatine.
[*]The FDA Approved the FLAVR SAVR Tomato for Sale to the Public
So What?
Although the main benefit of the FLAVR SAVR tomato is improved flavor for the consumer, the possibilities genetically engineered crops are nearly limitless. Plants can be created that resist spoilage, insect or fungal attacks, or less than ideal weather conditions (as in the case of the antifreeze strawberries) or even create chemicals that can be extracted from the plant tissues and used as pharmaceuticals. Also, the need for clearing new farmland and using pesticides could be reduced if the use of genetically engineered crops became more widespread. However, not all people see genetic alteration of plants from this perspective. One ironic example of resistance to genetically engineered crops came from the Environmental Protection Agency. In a bizarre bureaucratic move, the EPA has designated certain insect resistant crop plants as "pesticides, " thus requiring that they be regulated like chemical pesticides are although there is a tremendous difference between a plant that can make itself not tasty or toxic to insects and man-made chemical pesticides (Nettleton 20). This arbitrary distinction is costing small biotechnology companies thousands of dollars in regulatory costs (Nettleton 20). Groundless bureaucratic decisions such as this reflect the lack of understanding that the government as well as the general public has about biotechnology. The success of the FLAVR SAVR tomato under rigorous testing by Calgene under the watchful eye of the FDA demonstrates that genetically engineered crops have the potential to be safe for human consumption and for the environment. Transgenic plants ought to be tested for safety and regulated by the FDA, but considering the possibilities that the genetic engineering of crops offers and that a demonstrably safe genetically engineered crop (the FLAVR SAVR tomato) has been developed, the public and the government should set aside their concerns, educate themselves on this issue, and give genetic engineering a chance.
Appendix A
DNA is a double stranded molecule that directs the synthesis of proteins in living organisms. The protein synthesis that occurs in a cell ultimately determines the unique characteristics of that organism. The strands of DNA are composed of thousands of nucleic acids stringed together in particular sequences. A particular sequence of nucleic acids on the DNA molecule codes for the particular sequence of amino acids in a particular protein. When a cell needs a particular protein, the part of the DNA strand that codes for that particular protein "unzips" and allows nucleic acid "pieces" floating in the nucleus of the cell to bond to the exposed nucleic acids in the DNA strand. When the entire new strand of nucleic acids is formed, the new strand, called mRNA, is removed, and the DNA strands "rezip." The mRNA strand will then float through the cell to special protein synthesizing structures called ribosomes and act as a template for production of the protein. As the mRNA passes through the ribosome, it will interact with molecules bearing specific amino acids called tRNA. As each specific tRNA binds to the mRNA, the amino acids will form a string, and the tRNA molecules will be released into the cell. When this string of amino acids is completed, it is called a protein. Some proteins provide structure in living things (such as the protein in muscle tissue), while others can promote certain chemical reactions in cells (such as the breakdown of pectin in tomato cell walls).
The above information was taken from Biology, Neil Campbell, et. al., New York: Addison Wesley, 1999, p.316.
Works Cited
Campbell, Neil et. al. (1999). Biology. New York: Addison Wesley
Engel, Karl-Heinz et al., editors. (1995). Genetically Modified Foods: Safety Aspects,
Washington, DC: American Chemical Society.
Nettleton, Joyce. (1999, January). Wedging Science into Public Policy, Food Technology,
p. 20.
Wilson, Edward O. (1999). The Diversity of Life. New York: W. W. Norton & Company.
Một trong những enzym làm mềm trái cây là polygalacturonase (PG)
[ bạn chịu khó tìm thêm các tài liệu nc ngoài đó, hay lắm]
which act to break down pectin in cell walls to simple sugars
mà hành động để phá vỡ pectin ở thành tế bào để các loại đường đơn giản simultaneously softening and sweetening fruit.
đồng thời làm mềm và ngọt trái cây. PG is synthesized de novo
PG được tổng hợp de novo during ripening and was cDNA cloned by protein purification, sequencing
trong quá trình chín và đã được nhân bản cDNA của protein tinh chế, trình tự and oligomer probe synthesis.
và oligomer thăm dò tổng hợp. PG expression in plants was reduced by
PG biểu hiện ở thực vật đã được giảm expressing the PG cDNA backwards in transgenic tomatoes and produce the
thể hiện cDNA PG ngược trong cà chua biến đổi gen và sản xuất Flavr -Savr tomato that is slow to rot so that the tomato can be allowed
Flavr-Savr cà chua mà chậm cà chua thối để có thể được cho phép to ripen on the vine.
để chín trên cây nho. During vine ripening the tomato acquires flavor,
Trong quá trình chín cà chua nho mua lại hương vị, organic acids and various volatiles that are absent from supermarket
xít hữu cơ và chất dễ bay hơi khác nhau được vắng mặt tại siêu thị tomatoes which are presently picked green.
cà chua mà hiện nay đã chọn màu xanh lá cây. [ bạn chịu khó tìm thêm các tài liệu nc ngoài đó, hay lắm]
shunshine88
Senior Member
Bạn có hình ảnh về quá trình này không ?
cảm ơn nhìu
cảm ơn nhìu
shunshine88
Senior Member
Mọi người cho mình hỏi :
Trong cây cà chua Flavr Savr thì gen Flavr Savr được tạo ra như thế nào. Nó được tổng hợp nhân tạo từ trình tự mã hóa cho enzyme Polygalacturonase hay là đoạn gen này bị đảo ngược.
Trong cây cà chua Flavr Savr thì gen Flavr Savr được tạo ra như thế nào. Nó được tổng hợp nhân tạo từ trình tự mã hóa cho enzyme Polygalacturonase hay là đoạn gen này bị đảo ngược.
Để tạo ra cà chua biến đổi gen, một gen từ E. coli (một loại vi khuẩn mà xuất hiện tự nhiên trong ruột động vật có vú) được gọi là kan (r) và SAVR gen FLAVR (từ cà chua một) đã được chèn vào plasmid một (một vòng tròn của DNA) và plasmid như thế này đã được đưa vào một nhóm của cà chua các tế bào trong môi trường tăng trưởng có chứa thuốc kháng sinh (Engel 77). Các kan (r) gen, khi thành lập vào tế bào, sản xuất một chất gọi là APH (3 ') II đã cho rằng các tế bào đề kháng với thuốc kháng sinh. Các kháng sinh giết chết các tế bào không nhận được plasmid. Mục đích của gen vi khuẩn được, do đó, để xác định các tế bào đã được biến đổi di truyền. Các FLAVR SAVR gen mã hoá cho một sợi RNA đó là đảo ngược của một sợi ARN xảy ra tự nhiên trong nhà máy. Các RNA gốc sợi trong nhà máy chịu trách nhiệm sản xuất của các enzyme polygalacturonase. . Polygalacturonase bị hư pectin trong các bức tường tế bào của cà chua trong quá trình chín và làm cho toàn bộ cà chua để trở thành mềm (Engel 77). Các sợi bổ sung của RNA từ gen FLAVR SAVR liên kết với các RNA polygalacturonase và hai sợi cáp "hủy lẫn nhau," ngăn chặn việc sản xuất polygalacturonase và làm mềm của cà chua (Engel 77).(Đối với một cuộc thảo luận ngắn gọn về các mối quan hệ giữa DNA, RNA, protein, các enzym và các chất nền và một sơ đồ chức năng của gen FLAVR SAVshunshine88
Senior Member
Thanks bạn. Ý mình ở đây là làm thế nào để có được gen Flavr Savr. Sau đó gen này cùng với gen Kan(r) sẽ chèn vào plasmid thì như bạ đã nói.
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