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Transgenic Species and Genetic Manipulation

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					             Transgenic Species and Genetic Manipulation:
 Transgenic species are organisms which have had genetic material from a different
  species experimentally transferred into their chromosomes. The transferred gene
  instructs the transgenic organism to produce the desired trait or product, which may be
  passed on to future generations.
 In creating transgenic species, scientists choose the trait they want to express and, using
  the recombinant DNA technology explained below, isolate the DNA segment and
  transfer the genes for that trait into the reproducing cells or splice the gene into the
  DNA of another organism.
 The Process of Creating Transgenic Species: (This entire process can be seen in the
  flow diagram “Diagram 1: The Process of Cloning using Recombinant DNA used to
  produce Transgenic Species”
     o Scientists choose the trait they want to express and isolate the DNA segment for
         that trait.
     o Chemicals called “restriction enzymes” act as the scissors to cut the DNA.
         Thousands of varieties of restriction enzymes exist, each recognizing only a
         single nucleotide sequence. Once it finds that sequence in a strand of DNA, it
         attacks it and splits the base pairs apart, leaving single helix strands (“sticky
         ends”) at the end of two double helixes.
     o In this specific case, as well as cutting the DNA segment, a plasmid (small rings
         of DNA found in bacteria) are also cut using the restriction enzymes to produce
         sticky ends.
     o At this stage, scientists are free to add any genetic sequences they wish into the
         broken chain, usually to give resistance to a particular antibiotic. (This is done so
         that afterwards, by culturing the bacteria in a medium which contains the
         antibiotic – only those bacteria that have been successfully transformed will
         survive.)
     o After this process, the chain is repaired (as a longer ring of DNA called a
         “recombinant plasmid”) with another enzyme called “ligase”.
     o Then, the recombinant plasmid is transferred to a host cell, where the cell’s
         normal cell division techniques will produce clones of the new DNA sequence.

 Diagram 1: The Process of Cloning using Recombinant DNA used to produce Transgenic
                                       Species
           (From: “Excel HSC: Biology” [2003 Edition] by Diane Alford and
                                   Jennifer Hill)

1. Genetically Modified Foods:
    The “Flavr Savr” Tomato: The Flavr Savr Tomato was created by Calgene Inc
       for the purpose of creating a tasty vine ripened tomato that was not destroyed in the
       process of transportation. The reason why Flavr Savr stays ripe and can stand harsh
       transportation for at least 10 days after picking (without refrigeration) is through
       gene manipulation of polygalacturonase (PG), which occurs naturally in all
       tomatoes. The scientists at Calgene manipulated the genes of the Flavr Savr and
       suppressed polygalacturonase, which breaks down pectin (found in the cell walls)
       and prevents the tomato from going mushy.
    Roundup-Ready Soybeans: In 1995, Monsanto, a large American biotechnology
       company, created the Roundup-Ready Soybeans. These soybeans have been
       genetically modified so that they are not affected by Roundup (also owned by
       Monsanto), which means that farmers can spray the whole field of soybeans with
       Roundup and not worry that it will also kill the crops. Roundup is made out of a
       chemical, called glyphosate, which is environmentally friendly as it breaks down
       easily in water and soil. The theory behind the new Roundup resistant soybeans is
       the scientists at Monsanto have modified the DNA in the soybean by inserting
       DNA from soil bacteria, which makes the effects of the glyphosate in the herbicide
       useless.
    Hi-Bred Soybeans: In the early 1990s, one of the world's largest seed
       companies, Pioneer Hi-Bred, developed a more nutritious type of soybean by
       adding a gene taken from Brazil nuts. The gene coded for a protein rich in
       methionine, a nutrient that is in short supply in ordinary soybeans. However, the
         project had to be dropped when it was discovered that the novel soybean would
         trigger a major attack in people with Brazil nut allergies. Critics often cite this
         case as an example of one of the major risks of genetically modified food
         products, particularly as research published a few years previously suggested that
         this protein was not an allergen.
As can be seen from the three case studies above, it is obvious why there is so much
controversy over genetically modified foods. It is agreed that some genetically modified
foods are better than their natural counterparts, however, such as in the case of the Hi-Bred
soybeans, such foods may cause severe allergies or reactions in humans that would not
normally be expected in the natural foods. As well, with genetically modified crops, many
people are concerned over the possibility of cross-pollination from a genetically modified
crop to a non-engineered crop and the effects it could have on the natural products. It is
difficult to ensure that this does not occur and spread genes which may, for example, be
resistant to pesticides (such as in the case of Roundup-Ready Soybeans) or cause allergic
reactions, to their natural equivalent.

2. Some risks that have been suggested in terms of gene technology are:
    Concerns about the long term affect on the transgenic animal itself, for example,
      the transgenic pigs which grow much faster and have leaner meat, but are unable
      to stand due to chronic arthritis.
    The morality of using animals, with the possibility of giving them painful
      inflictions.
    The concern that genetic engineering of transgenic species has the capacity to
      disrupt the rate of gene transfer between organisms and the way genes are
      transferred, which therefore disrupts evolutionary relationships between
      organisms.
    Concerns that genetically engineered organisms released into the environment
      may cause new diseases or encourage resistance to current drugs and pesticides.
    Concerns about the “pollution” of gene pools due to cross-pollination of
      genetically modified crops to normal non-engineered crops.
    Concerns about unknown long term health risks associated with eating
      genetically modified foods or taking genetically modified medicines.

3. Table 1: Reasons For and Against the Development of Transgenic Species:

              For                                               Against
 1. Increases the resistance of    1. Concerns about the long term affect on the transgenic animal
    plants and animals to             itself and the morality of using animals, with the possibility of
    diseases, pests and extreme       giving them painful inflictions.
    environments.                  2. The concern that genetic engineering of transgenic species has
 2. Can be used for medicines,        the capacity to disrupt the rate of gene transfer between
    vaccines and to study             organisms and the way genes are transferred, which therefore
    human diseases.                   disrupts evolutionary relationships between organisms.
 3. Improves the productivity of   3. Concerns that genetically engineered organisms released into
    crops, pastures and animals.      the environment may cause new diseases or encourage
 4. Increases the efficiency of       resistance to current drugs and pesticides.
    food processing.               4. Concerns about the “pollution” of gene pools due to cross-
 5. Improves the quality of food      pollination of genetically modified crops to normal non-
    stuffs.                           engineered crops.
6. Has the ability to develop   5. Concerns about unknown long term health risks associated
   new products in many            with eating genetically modified foods or taking genetically
   industries.                     modified medicines.

                                   Artificial Insemination

  Artificial Insemination is defined as being the introduction of semen to ova
   through other processes than copulation. These processes usually involve the cell
   fusion taking place outside the body of the surrogate organism and then being re-
   introduced back into the uterus and placed for the term of the pregnancy.
  The process of the most common form of artificial insemination, In Vitro
   Fertilisation (IVF), is described as follows: (Please also refer to “Diagram 1:
   Procedure of IVF” for a pictorial explanation of the procedure.)
        1. In preparation for the procedure, the female will undergo hormonal
            therapy, including medication that blocks the secretions of the pituitary
            gland (thereby, optimising the number of oocytes, or unfertilised ova /
            eggs, that can be retrieved) and that stimulate ovarian activity, along with
            blood tests and ultrasound scans of the ovaries to determine the optimal
            time to retrieve the eggs from the ovary.
        2. At the proper time, just before ovulation, a small surgical procedure will
            allow the female's eggs to be visualised by ultrasound and retrieved from
            the ovary by placing a fine, hollow needle through the vaginal wall.
        3. Then, the embryologist will place the sperm with the eggs when they are
            ready for fertilisation. Usually, the eggs will develop into cleaving pre-
            embryos, whose cells divide 2 or 3 times to become pre-implantation
            embryos (also known as, “pre-embryos”), like the ones shown in Step 5 of
            Diagram 1. They are maintained in laboratory dishes, in a rich nutrient
            mixture which acts as a substitute for the environment that would have
            been provided by the fallopian tubes.
        4. Using a special fine catheter, the pre-embryos will then be passed through
            the vagina and into the uterus at the time the pre-embryos would normally
            have reached the uterus, approximately two days after retrieval, as shown
            in Diagram 1 (Step 6).
                              Diagram 1: Procedure of IVF
                                 Artificial Pollination

 Artificial Pollination is defined as being the transmission of pollen onto a stigma
  by processes that do not occur naturally. This process requires fertilisation using
  pollen from a selected plant with desirable traits (eg. colour, perfume) and then
  artificially transferring it to the stigma of another plant.
 Artificial pollination is, in essence, a reasonably simple procedure to perform:
      o Firstly, the pollen from the stamen (shown in Diagram 2) of one of the
          breeding pairs (Plant 1) can be collected using a fine paintbrush.
      o To ensure that self pollination of the other breeding plant (Plant 2) does not
          occur, the “male” stamens are removed from the organism. This process is
          shown below in “Diagram 3: Removing the Stamens from an Angiosperm”.
      o Then, the pollen from Plant 1 is transferred via hand pollination to the
          “female” stigma (shown in Diagram 2) of Plant 2 with the cotton swab or
          artist's brush, or shaken directly over the flowers.
  Diagram 2: Generalised diagram of the Reproductive Organs in an Angiosperm




                                        Cloning

 Cloning is defined as being the process to make identical copies (known as
  “clones”) from single cells without fertilisation or the genetical engineering, or the
  manipulation of the DNA sequencing, of the produced clone. Specifically the term
  “cloning” may be used to refer to a number of reproductive technologies:
     o “Animal and Plant cloning” refers to the creation of genetically identical
        organisms asexually without fertilisation. This can happen in two ways:
            DNA is extracted from the organism’s tissue and cloned to create an
               embryo. This embryo is then implanted back into the organism’s
               uterus for the term of gestation.
            Cells are taken from an embryo and clones to make multiple copies of
               the embryo.
     o “Gene cloning” refers to the creation of multiple copies of DNA segments
        using recombinant DNA technology, where the DNA segment is isolated
        and the genes for that trait are transferred into the reproducing cells or
        “spliced” into the DNA of another organism. This process is used in the
        hope that scientists can artificially combine the qualities of different
        organisms; and being able to choose which are the best qualities that
        particular organism could have.
   One of the version of plant and animal “cloning” is briefly explained below:
      o Remove the nucleus of an oocyte (an unfertilised egg) with a
         micromanipulator (a microscope with fine needles and pipettes to
         manipulate the oocyte).
      o Inject the donor nucleus into the oocyte and pulse the egg with a shock of
         electricity to make the nucleus attach itself to the cytoplasm. This pulse of
         electricity will begin to “wake” up the cell and make it more likely to start
         the dividing process.
      o The resulting cloned ovum can then be re-implanted into a surrogate
         mother’s uterus to be fertilised to eventually develop into an embryo.




  1. Table 1: Potential Risks and Benefits for Cloning

                   Benefits                                                Risks
                                                                    High Risk of Failure:
Embryonic stem cells can be grown to produce
 organs or tissues to repair or replace damaged
                                                         Cloning animals through somatic cell nuclear
 ones. Skin for burn victims, brain cells for the
                                                      transfer is simply inefficient and does not produce
       brain damaged, spinal cord cells for
                                                     required results. The success rate ranges from 0.1 –
 paraplegics, hearts, lungs, livers, and kidneys
                                                          3%, which means that for every 1000 tries,
     could be produced. By combining this
                                                        approximately only one to 30 clones are made.
 technology with human cloning technology it
                                                         Some reasons for this high rate of failure are:
 may be possible to produce needed tissue for
                                                      The enucleated egg and the transferred nucleus
suffering people that will be free of rejection by
                                                          may not be compatible
   their immune systems. Conditions such as
                                                      An egg with a newly transferred nucleus may
    Alzheimer's disease, Parkinson's disease,
                                                          not begin to divide or develop properly
    diabetes, heart failure, degenerative joint
                                                      Implantation of the embryo into the surrogate
 disease, and other genetically based problems
                                                          mother might fail
              may be made curable.
                                                      The pregnancy itself might fail
   With cloning, infertile couples could have                 Problems during later development:
children. Despite being quite well-known about
and publicised in the media, infertility programs     Cloned animals that do survive tend to be much
  are not very successful. (One estimate is that       bigger at birth than their natural counterparts.
  current infertility treatments are less than 10    Scientists usually refer to this as “Large Offspring
percent successful.) Human cloning could make            Syndrome” (LOS). Clones with LOS have
 it possible for many more infertile couples to          abnormally large organs which can lead to
    have children than ever before possible.          breathing, blood flow and other problems. Since
                                                    LOS doesn't always occur, scientists cannot reliably
                                                     predict whether it will happen in any given clone.
                                                      Also, some clones without LOS have developed
                                                        kidney or brain malformations and impaired
                                                    immune systems, which can cause problems later in
                                                                              life.
                                                            Abnormal gene expression patterns:

 Lastly, human cloning technology may be able            In a naturally-created embryo, the DNA is
 to reduce the amount of defective genes in our     programmed to express a certain set of genes. Later
society. (Currently, the average person carries 8   on, as the embryonic cells begin to differentiate, the
  defective genes inside them.) These defective       program changes. For every type of differentiated
 genes allow people to become sick when they        cell - skin, blood, bone or nerve, for example - this
 would otherwise remain healthy. With human            program is different. In cloning, the transferred
cloning and its technology it may be possible to    nucleus doesn't have the same program as a natural
 ensure that we no longer suffer because of our     embryo. It is up to the scientist to totally reprogram
                 defective genes.                    the nucleus as complete reprogramming is needed
                                                          for normal or near-normal development.
                                                     Incomplete programming will cause the embryo to
                                                                  develop abnormally or fail.