DOCSLIB.ORG

The Science of Animal Cloning

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Science of Animal Cloning CLONING HUMAN BEINGS The Science of Animal Cloning Commissioned Paper by Janet Rossant, Ph.D. Samuel Lunenfield Research Institute-Mount Sinai Hospital CONTENTS What Is Cloning? B-3 The Scientific Question: Does Differentiation Involve Irreversible Changes in Genetic Content? B-4 The Stability of the Differentiated State: Our Understanding Today B-6 Nuclear Transfer in Mammals: The Early Experiments B-7 Reprogramming in the Oocyte Environment B-8 Nuclear Transfer in Mammals: The Current State of Play B-9 And Then Came Dolly B-10 Why Pursue Animal Cloning Research? B-12 1. Making Clones for Research Purposes B-12 2. Propagating Desirable Stocks B-13 3. Improved Generation and Propagation of Transgenic Livestock B-13 4. Generating Targeted Gene Alterations B-14 How Can We Use Information from Nuclear Transfer Experiments for Human Benefit? B-17 Ethical Concerns B-17 References B-18 B-1 WHAT IS CLONING? The word “clone” is used in many different contexts in biological research, but in simple terms it means a set of genetically identical individuals. Scientists talk about cloning DNA—the process of making and propagating a set of identical copies of a particular piece of genetic material, or about cloning cells—taking a single cell in culture and allowing it to multiply into a cell line. These techniques are some of the basic tools of the trade of modern biomedical research and are not currently a source of much public concern. But when we talk about cloning whole animals, especially mammals, the public rightly wants to know what is going on and why. Genetically identical copies of whole organisms—clones—are commonplace in the plant breeding world. Many valuable horticultural or agricultural strains are maintained solely by vegetative propagation from an original plant, and never by sexual reproduction. This reflects the ease with which it is possible to regenerate a complete plant from a small cutting. The ability to propagate a valuable animal strain in the same way would revolutionize the agricultural business. However, in the animal kingdom, development is much less flexible than in plants. Many simpler invertebrate species have the ability to regenerate a whole organism from a small piece, although this is not necessarily their usual mode of reproduction. Vertebrates have lost this ability entirely, although regeneration of missing limbs, organs, or tissues can occur to varying degrees. Although an adult vertebrate cannot make another adult, natural cloning does occur, in a limited way, with the formation of identical twins. These arise in humans and other mammals by chance separation of a single embryo into halves at an early stage of development. The resulting offspring will be genetically identical, deriving from one zygote—the result of the fusion of one egg and one sperm. A clone of two is not very remarkable, but it is a clone nonetheless. Experimental separation of cells from the early embryos of several mammalian species has shown that it is possible in some cases to get larger clones from one egg (Figure 1). In mice, only separated two-cell blastomeres are capable of generating entire mice (Rossant 1976), but in some domestic species, like sheep, it is possible to get separated eight-cell blastomeres to develop into viable offspring (Willadsen 1981). At best, efficiency of this technique is never 100 percent, so the number of clones is small. However, the experiments are scientifically important, because they demonstrate that the cells of the early embryo are totipotent; that is, they retain the full potential to form an entire animal. As development proceeds, cells begin to differentiate into specialized cell types and can no longer revert back to the beginning of development (Figure 1). If this stability of the differentiated state could be reverted in some way, then producing animals from later differentiated cells or even adult cells would become feasible. Nuclear transfer experiments, first performed in amphibians in the 1960s, demonstrated how this could be done. B-3 Figure 1: Preimplantation development in mammals THE SCIENTIFIC QUESTION: DOES DIFFERENTIATION INVOLVE IRREVERSIBLE CHANGES IN GENETIC CONTENT? The information for all the proteins produced in all the specialized cell types of the body is encoded in the DNA of the zygote and must be passed on intact into the next generation via the germ cells that form the eggs and sperm. However, there is no absolute requirement that the somatic cells—those cells not destined to give rise to the germ cells—retain the full genetic content in an unmodified form. A differentiated cell like a neuron must keep a set of neural-specific genes active and silence those genes specifically required to make muscle, liver, and other tissues. How does it do this? Is it an active process, in which genes are still present but repressed in some way, or is the DNA for the inactive genes lost or irreversibly inactivated in some way? In the early 1960s our understanding of the mechanisms of gene regulation was still rudimentary and this general question was extremely important. Elegant experiments in Xenopus laevis by John Gurdon, following earlier experiments in Rana temporaria by Briggs and King (1952), provided strong evidence that the genetic content of differentiated somatic cells is essentially unchanged from that of the early embryo. Nuclei from donor differentiated cells were injected into recipient eggs from which the nucleus, containing the DNA, had been inactivated (Figure 2). If the donor nucleus could direct normal development of the recipient egg, this would strongly suggest that differentiation cannot involve permanent B-4 changes in the genetic material. The first series of experiments used intestinal epithelial cells from swimming tadpoles (Gurdon 1962), and adult frogs were produced, albeit at a very low efficiency. The intestinal cells used were highly specialized brush-border gut cells, but were not derived from the final adult frog and so might not be terminally differentiated. Gurdon and colleagues (1975) performed another carefully controlled series of experiments in which they used nuclei from adult skin cells for transfer. Over 99 percent of the cultured cells expressed keratin, a differentiated marker of skin cells, and 4 percent of the nuclei transferred eventually gave rise to fully developed tadpoles. These experiments provided the strongest evidence to date that the nuclei of terminal differentiated cells could be reactivated by the cytoplasm of the egg and redirect normal development. Figure 2: Nuclear transfer in amphibians However, no viable adult frog was ever produced from an adult differentiated nucleus and there was a strong decline in the rate of recovery of feeding tadpoles with progressive age of nuclei transferred. This left open the theoretical possibility that complete reactivation of the adult B-5 nucleus was prevented by some kind of irreversible change in the genetic material, and that there was, indeed, a progressive decline in nuclear potential with age. However, careful analysis at the time suggested that the major reason for developmental failure of transplant embryos was chromosomal abnormalities acquired as a consequence of the process of nuclear transplantation itself. The cell cycle of adult cells is much slower than the rapid pace of cell division in the early frog embryo. Expecting a transplanted nucleus to reprogram its gene expression, replicate its DNA, and enter normal embryonic cell cycles within an hour of nuclear transfer is unrealistic. The remarkable thing is that some nuclei manage to do so, rather than that so many do not. The general conclusion from the amphibian nuclear transfer experiments of Gurdon and others was that the differentiated state did not involve major irreversible changes in the DNA. This conclusion was reached in the 1960s and early 1970s and has not been challenged in the intervening years (Gurdon 1974). THE STABILITY OF THE DIFFERENTIATED STATE: OUR UNDERSTANDING TODAY As our understanding of the regulation of gene expression has grown, we have learned that most patterns of differentiated gene expression are maintained by active control mechanisms (Blau 1992), in which combinations of regulatory proteins bind to control sequences adjacent to genes and turn them on or off. The particular differentiated state of a cell depends on its particular combination of regulatory proteins. This is not the only mechanism of gene control. There are some cases in which actual rearrangements and deletions of DNA occur, as in the expression of the immunoglobulin and T-cell receptor genes in lymphocytes. Heritable modification of the DNA by methylation can also affect gene expression. However, the overwhelming evidence suggests that given the right environment, it should be possible to activate or inactivate almost any gene in a cell. This environment need not be the cytoplasm of the egg. Cell fusion experiments, in which different cell types are fused into one multinucleate cell called a heterokaryon, have demonstrated that extensive reprogramming of differentiated nuclei can occur. For example, when muscle cells are fused with non-muscle cells of various sorts, muscle-specific genes are activated in the non-muscle cells (Blau et al. 1985). Similarly, globin genes can be activated in many cell types after fusion with erythroid cells (Baron and Maniati 1986). These and other kinds of experiments have led to the isolation of specific protein factors that regulate cell differentiation, such as the myogenic factors that regulate the formation of the muscle cell lineages (Weintraub 1993). All of this information has shown that the stability of the differentiated state is not absolute and, therefore, it should be theoretically possible to reprogram adult cells to reinitiate earlier programs of differentiation. Nuclear transfer experiments pointed the way and molecular biology is continuing to define the components of the regulation of cellular differentiation. NUCLEAR TRANSFER IN MAMMALS: THE EARLY EXPERIMENTS B-6 Following success in nuclear transfer experiments in frogs, there were some attempts in the 1970s to repeat the experiments in mice, the mammal of choice for experimental manipulation.
Load more

Recommended publications
  • Welfare Issues with Genetic Engineering and Cloning of Farm Animals
    WellBeing International WBI Studies Repository 2006 Welfare Issues with Genetic Engineering and Cloning of Farm Animals The Humane Society of the United States Follow this and additional works at: https://www.wellbeingintlstudiesrepository.org/ hsus_reps_impacts_on_animals Part of the Animal Studies Commons, Bioethics and Medical Ethics Commons, and the Other Genetics and Genomics Commons Recommended Citation The Humane Society of the United States, "Welfare Issues with Genetic Engineering and Cloning of Farm Animals" (2006). IMPACTS ON FARM ANIMALS. 21. https://www.wellbeingintlstudiesrepository.org/hsus_reps_impacts_on_animals/21 This material is brought to you for free and open access by WellBeing International. It has been accepted for inclusion by an authorized administrator of the WBI Studies Repository. For more information, please contact [email protected]. Farm Animal Welfare • The HSUS 2100 L St., N.W. • Washington, DC 20037 • HSUS.org 202-452-1100 • F: 301-258-3081 • FarmAnimalWelfare.org An HSUS Report: Welfare Issues with Genetic Engineering and Cloning of Farm Animals Abstract Developments in biotechnology have raised new concerns about animal welfare, as farm animals now have their genomes modified (genetically engineered) or copied (cloned) to propagate certain traits useful to agribusiness, such as meat yield or feed conversion. These animals suffer from unusually high rates of birth defects, disabili- ties, and premature death. Genetically engineering farm animals for greater bone strength or reduced pain reception, for example, may result in improved well-being, yet the broad use of this technology often causes increased suffering. The limited success of gene insertion techniques can result in genes failing to reach target cells and finishing in cells of unintended organs, and abnormally developed embryos may die in utero, be infertile, or born with development defects, attributable in part to insertional problems.
    [Show full text]
  • Cloning: Adult Vs. Embryonic Cells and Techniques Employed
    University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Supervised Undergraduate Student Research Chancellor’s Honors Program Projects and Creative Work Spring 5-2001 Cloning: Adult vs. Embryonic Cells and Techniques Employed Rebecca Ruth Frazor University of Tennessee-Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_chanhonoproj Recommended Citation Frazor, Rebecca Ruth, "Cloning: Adult vs. Embryonic Cells and Techniques Employed" (2001). Chancellor’s Honors Program Projects. https://trace.tennessee.edu/utk_chanhonoproj/459 This is brought to you for free and open access by the Supervised Undergraduate Student Research and Creative Work at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Chancellor’s Honors Program Projects by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. UNIVERSITY HONORS PROGRAM SENIOR PROJECT - APPROVAL Name: Getec eCA f?- f(CAZOr College: AQn eMi:hA rv Department: A1 (met I SCi!A1w -J Faculty Mentor: F. N-S ChV\C ¥: PROJECT TITLE: C10l/1\(}q : Adult \[) ' fmmrVVl l0 C l, (( ~ ~rd the. ~ Qr\L\A<; Icchn \ quc ~ Emplo\( f d I have reviewed this completed senior honors thesis with this student and certify that it is a project commens rate with rs level undergraduate research in this field. Signed: ;. ./-1 Faculty Mentor Date: _-+-'""-+----L-___ Comments (Optional): Cloning: Adult vs. Embryonic Cells and Various Techniques Employed Rebecca R. Frazor Mentor: F. Neal Schrick Senior Honors Project May 2001 Abstract The cloning of amphibians and mainly mammals is discussed focusing on somatic cell usage. Significant progress has been made in recent years and this is outlined with an emphasis on techniques and their differences.
    [Show full text]
  • Direct Cloning and Refactoring of a Silent Lipopeptide Biosynthetic Gene Cluster Yields the Antibiotic Taromycin A
    Direct cloning and refactoring of a silent lipopeptide biosynthetic gene cluster yields the antibiotic taromycin A Kazuya Yamanakaa,b, Kirk A. Reynoldsa,c, Roland D. Kerstena, Katherine S. Ryana,d, David J. Gonzaleze, Victor Nizete,f, Pieter C. Dorresteina,c,f, and Bradley S. Moorea,f,1 aScripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093; bYokohama Research Center, JNC Corporation, Yokohama 236-8605, Japan; cDepartment of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093; dDepartment of Chemistry, University of British Columbia, Vancouver, BC, Canada V62 1Z4; and Departments of ePediatrics and fSkaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093 Edited by Jerrold Meinwald, Cornell University, Ithaca, NY, and approved December 23, 2013 (received for review October 23, 2013) Recent developments in next-generation sequencing technologies genes (9, 10). Synthetic biology approaches also can be used to have brought recognition of microbial genomes as a rich resource refactor orphan gene clusters by optimizing promoters, tran- for novel natural product discovery. However, owing to the scar- scriptional regulation, ribosome-binding sites, and even codon city of efficient procedures to connect genes to molecules, only use (11). Examples of successful regulatory gene manipulation to a small fraction of secondary metabolomes have been investigated elicit the production of new natural products from silent bio- to date. Transformation-associated recombination (TAR) cloning synthetic gene clusters in WT strains have been reported in takes advantage of the natural in vivo homologous recombination bacteria and fungi (12, 13); however, this approach requires the of Saccharomyces cerevisiae to directly capture large genomic loci.
    [Show full text]
  • Dolly the Sheep – the First Cloned Adult Animal
    DOLLY THE SHEEP – THE FIRST CLONED ADULT ANIMAL NEW TECHNOLOGY FOR IMPROVING LIVESTOCK From Squidonius via Wikimedia Commons In 1996, University of Edinburgh scientists celebrated the birth of Dolly the Sheep, the first mammal to be cloned using SCNT cloning is the only technology adult somatic cells. The Edinburgh team’s success followed available that enables generation of 99.8% its improvements to the single cell nuclear transfer (SCNT) genetically identical offspring from selected technique used in the cloning process. individuals of adult animals (including sterilized animals). As such, it is being Dolly became a scientific icon recognised worldwide and exploited as an efficient multiplication tool SCNT technology has spread around the world and has been to support specific breeding strategies of used to clone multiple farm animals. farm animals with exceptionally high genetic The cloning of livestock enables growing large quantities of value. the most productive, disease resistant animals, thus providing more food and other animal products. Sir Ian Wilmut (Inaugural Director of MRC Centre for Regeneration and Professor at CMVM, UoE) and colleagues worked on methods to create genetically improved livestock by manipulation of stem cells using nuclear transfer. Their research optimised interactions between the donor nucleus and the recipient cytoplasm at the time of fusion and during the first cell cycle. Nuclear donor cells were held in mitosis before being released and used as they were expected to be passing through G1 phase. CLONING IN COMMERCE, CONSERVATION OF AGRICULTURE AND PRESERVATION ANIMAL BREEDS OF LIVESTOCK DIVERSITY Cloning has been used to conserve several animal breeds in the recent past.
    [Show full text]
  • How They Cloned a Sheep
    How They Cloned A Sheep How They Cloned A Sheep This text is provided courtesy of the American Museum of Natural History. How they cloned a sheep 1. Scientists took udder cells from Dolly's DNA mother. They let the cells multiply and then they stopped the process when they had divided enough. 2. They took an egg cell from a different sheep and removed the nucleus. 3. They put one udder cell next to the egg cell without a nucleus and joined them using electricity. The egg cell now contained all the udder cell's DNA. 4.The egg cell divided until it developed into an embryo. An embryo is the early stage of an animal before it has been born or hatched. This embryo was placed inside a third sheep. Five months later, this sheep gave birth to Dolly. ReadWorks.org · © 2015 ReadWorks®, Inc. All rights reserved. How They Cloned A Sheep - Comprehension Questions Answer Key 1. What did scientists remove from the egg cell of a sheep? A. the nucleus B. the embryo C. DNA D. udder cells 2. This passage describes the sequence of events involved in cloning a sheep. What happened after the scientists took udder cells and an egg cell from different sheep? A. The egg cell was joined to an udder cell using electricity. B. The embryo was placed inside another sheep. C. Scientists took udder cells from Dolly's DNA mother. D. The egg cell divided until it formed an embryo. 3. As part of the process of cloning a sheep, scientists placed the embryo inside a sheep, which eventually gave birth to Dolly.
    [Show full text]
  • Human Cloning: Fact Or Fiction
    LRN: 05D1721 745. 6239 - i/3 Human Cloning: Fact or Fiction An Interactive Qualifying Project Report submitted to the Faculty of the Worcester Polytechnic Institute in partial fulfillment of the requirements for a Bachelor's Degree by Krisha S. Murthy Christopher Tereshko Daniel J. Caloia Amy Borges Date: May 3, 2005 Professor Thomas A. Shannon, Major Advisor 1 Abstract Human Cloning: Fact or Fiction is an evaluation of the portrayal of cloning in the media. Cloning technology has not only made a huge impact in the scientific community, but it has also affected the general community. Cloning is often misrepresented in literature and films, however, giving the public only a partial picture of the different aspects of cloning, such as religion, ethics, and government. Informing them of the facts of cloning technology will form better educated opinions. 2 Section 1 - Introduction In 1997, Dolly was created and cloning became a household word. Before this event, cloning was just a possibility, a fictional thread to weave together tales of science fiction. Once Dolly was born, however, there could be serious talk of cloning and these stories that once seemed like fiction could be considered reality. However, can stories like this really be considered reality? In most fictional books and movies, cloning starts as an amazing scientific breakthrough. However, one or more characters take advantage of the technology and attempt to create, for instance, the perfect army, or a Hitler for the current generation. It could even be as innocent as creating clones to help do a particular tedious task, but even then they get out of hand.
    [Show full text]
  • Cloning of Gene Coding Glyceraldehyde-3-Phosphate Dehydrogenase Using Puc18 Vector
    Available online a t www.pelagiaresearchlibrary.com Pelagia Research Library European Journal of Experimental Biology, 2015, 5(3):52-57 ISSN: 2248 –9215 CODEN (USA): EJEBAU Cloning of gene coding glyceraldehyde-3-phosphate dehydrogenase using puc18 vector Manoj Kumar Dooda, Akhilesh Kushwaha *, Aquib Hasan and Manish Kushwaha Institute of Transgene Life Sciences, Lucknow (U.P), India _____________________________________________________________________________________________ ABSTRACT The term recombinant DNA technology, DNA cloning, molecular cloning, or gene cloning all refers to the same process. Gene cloning is a set of experimental methods in molecular biology and useful in many areas of research and for biomedical applications. It is the production of exact copies (clones) of a particular gene or DNA sequence using genetic engineering techniques. cDNA is synthesized by using template RNA isolated from blood sample (human). GAPDH (Glyceraldehyde 3-phosphate dehydrogenase) is one of the most commonly used housekeeping genes used in comparisons of gene expression data. Amplify the gene (GAPDH) using primer forward and reverse with the sequence of 5’-TGATGACATCAAGAAGGTGGTGAA-3’ and 5’-TCCTTGGAGGCCATGTGGGCCAT- 3’.pUC18 high copy cloning vector for replication in E. coli, suitable for “blue-white screening” technique and cleaved with the help of SmaI restriction enzyme. Modern cloning vectors include selectable markers (most frequently antibiotic resistant marker) that allow only cells in which the vector but necessarily the insert has been transfected to grow. Additionally the cloning vectors may contain color selection markers which provide blue/white screening (i.e. alpha complementation) on X- Gal and IPTG containing medium. Keywords: RNA isolation; TRIzol method; Gene cloning; Blue/white screening; Agarose gel electrophoresis.
    [Show full text]
  • Review on Applications of Genetic Engineering and Cloning in Farm Animals
    Journal of Dairy & Veterinary Sciences ISSN: 2573-2196 Review Article Dairy and Vet Sci J Volume 4 Issue 1 - October 2017 Copyright © All rights are reserved by Ayalew Negash DOI: 10.19080/JDVS.2017.04.555629 Review on Applications of Genetic Engineering And Cloning in Farm animals Eyachew Ayana1, Gizachew Fentahun2, Ayalew Negash3*, Fentahun Mitku1, Mebrie Zemene3 and Fikre Zeru4 1Candidate of Veterinary medicine, University of Gondar, Ethiopia 2Candidate of Veterinary medicine, Samara University, Ethiopia 3Lecturer at University of Gondar, University of Gondar, Ethiopia 4Samara University, Ethiopia Submission: July 10, 2017; Published: October 02, 2017 *Corresponding author: Ayalew Negash, Lecturer at University of Gondar, College of Veterinary Medicine and science, University of Gondar, P.O. 196, Gondar, Ethiopia, Email: Abstract Genetic engineering involves producing transgenic animal’s models by using different techniques such as exogenous pronuclear DNA highly applicable and crucial technology which involves increasing animal production and productivity, increases animal disease resistance andmicroinjection biomedical in application. zygotes, injection Cloning ofinvolves genetically the production modified embryonicof animals thatstem are cells genetically into blastocysts identical and to theretrovirus donor nucleus.mediated The gene most transfer. commonly It is applied and recent technique is somatic cell nuclear transfer in which the nucleus from body cell is transferred to an egg cell to create an embryo that is virtually identical to the donor nucleus. There are different applications of cloning which includes: rapid multiplication of desired livestock, and post-natal viabilities. Beside to this Food safety, animal welfare, public and social acceptance and religious institutions are the most common animal conservation and research model.
    [Show full text]
  • Cloning and Genetic Engineering of Farm Animals
    INVESTOR BRIEFING NO. 6 SEPTEMBER 2012 Cloning and Genetic Engineering of Farm Animals ABSTRACT Cloning and the genetic modification of farm animals are becoming more common in intensive farming systems in many countries. These procedures can have adverse impacts on the welfare of animals involved and their descendents. Cloning is primarily used to produce identical copies of high yielding and fast growing breeds of animals. The practice is already established in the US, Brazil, Argentina and Japan. Within Europe, however, there has been widespread opposition – on both animal welfare and ethical grounds – to the cloning of animals for food production and to the sale of meat and dairy products from cloned animals and their descendents. The genetic engineering of farm animals is used in China, the US and Australia to enhance growth rates, increase disease resistance and alter meat and milk composition. The European Commission (EC) is currently considering how to regulate the production and use of GM animals. Introduction The cloning of farm animals for food production is already under way in a number of countries including the US, Brazil, Argentina and Japan. In the EU, however, cloning has become a controversial issue, with the European Commission (EC) being firmly opposed to the cloning of animals for food production and to the sale of meat and dairy products from clones and their descendants. Interestingly, the opposition of the EC and animal welfare organisations is based on animal welfare and ethical grounds rather than on food safety concerns. While the science currently indicates that food from clones and their descendants does not raise food safety issues, it may be too early to be confident about this.
    [Show full text]
  • Genetically Modified Organisms: Activity 1 Page 1 of 3
    Genetically Modified Organisms: Activity 1 Page 1 of 3 Activity 1: Coming Attractions Based on video content 15 minutes (10 minutes before and 5 minutes after the video) Setup Before watching the video, answer a few quick questions about genetically modified organisms. Don’t think too long about the questions—just write down your first response. You might already know the answers to some of them; otherwise, just take an educated guess. During the video, listen for the topics addressed by the questions. After the video, review the questions and the answers as a group. Materials • Transparency of the Coming Attractions Questions (master copy provided) • Transparency of the Coming Attractions Answers (master copy provided) Rediscovering Biology - 323 - Appendix Genetically Modified Organisms: Activity 1 (Master Copy) Page 2 of 3 Coming Attractions Questions 1. What two U.S. crops are the most heavily genetically modified? 2. What fraction of U.S. corn is genetically engineered? 3. What percent of U.S. processed food contains some genetically modified corn or soybean product? 4. All known food allergies are caused by one type of molecule. Is it proteins, sugars, or fats? 5. What is the substance called “bt” used for? a. Bonus: What does “bt” stand for? b. Bonus: When was “bt” first registered with the USDA? 6. What does “totipotent” mean? 7. What nutrient is produced by “golden rice”? 8. According to the World Health Organization, how many children go blind each year from vitamin A deficiency? 9. What is the normal function of “anti-thrombin”? 10. For what was “Dolly the sheep” famous? 11.
    [Show full text]
  • Gene Cloningcloningcloning
    GeneGeneGene CloningCloningCloning 20042004 SeungwookSeungwookKim Kim Chem.Chem. && Bio.Bio. Eng.Eng. Reference z T.A. Brown, Gene Cloning, Chapman and Hall z S.B. Primrose, Molecular Biotechnology, Blackwell 1 Why Gene Cloning is Important? z A century ago, Gregor Mendel : { Basic assumption (each heritable property of an organism) is controlled by a factor (gene). z In 1900, Mandel's law Æ the birth of genetics. z what these genes are and exactly how they work The Early Development of Genetics z In 1903, Sutton, W { Proposed that genes reside on chromosomes 2 z In 1910, Morgan, TH { Experimental backing on that --> development of the techniques for gene mapping (To establish the structure or structural details or location) { By 1922, a comprehensive analysis of the relative positions of over 2000 genes on the four chromosomes of the fruit fly. (Drosophilia melanogaster) z In 1944, Avery, MacLeod and McCarty z In 1952, Hershey and Chase { Experimental results were shown that DNA is the genetic material. { Conventional idea : genes were made of protein z In 1952-1966, Delbruck, Chargaff, Crick and Monod { The structure of DNA was elucidated. { The genetic code was cracked. { The process of transcription and translation were described. 3 The Advent of Gene Cloning z In the late 1960's ; The experimental techniques were not sophisticated. z In 1971 ~ 1973 ; A new experimental techniques were developed. { Recombinant DNA technology or Genetic engineering based on the process of gene cloning { This led to rapid and efficient DNA sequencing techniques that enabled the structures of individual genes to be determined. z In the 1990s ; started with massive genome sequencing projects including the human project.
    [Show full text]
  • Tissue Culture and Cloning of Carnegiea Gigantea, Cactaceae
    Tissue Culture and Cloning of Carnegiea gigantea, Cactaceae Item Type Article Authors Baker, William P.; Hanks, Tyrone Harvard; Marin, Louis Eduardo Publisher University of Arizona (Tucson, AZ) Journal Desert Plants Rights Copyright © Arizona Board of Regents. The University of Arizona. Download date 26/09/2021 08:33:25 Link to Item http://hdl.handle.net/10150/554346 BakerCloning 13 and Tinus 1996; Guibert 1996; O'Dea et al. 1995; Ritchie Tissue Culture and Cloning of 1997). Carnegiea gigantea, Cactaceae Cloning of these plants allows multiple copies to be pro- duced from superior genotypes without the time and expense William P. Baker of traditional methods. Tissue culture and cloning, however, Tyrone Harvard Hanks are not routinely used to cultivate members of the cactus family. According to Havel and Kolar (1983), "one of the Biomedical Sciences reasons can be seen in the morphological structure of cacti Midwestern University making the traditional way of explant isolation and surface 19555 North 59th Avenue sterilization of the plant material difficult." Glendale, Arizona 85308 [email protected] Material and Methods In this study, in vitro clones were produced from phenotypi- cally selected, commercially available saguaro. Eight plants Louis Eduardo Marin measuring 8 -10 cm tall were purchased from a local nurs- Life Science Department ery. Stem portions were excised, dipped in 95% ethanol, and flamed to burn off the needles. The cooled samples were Mesa Community College sterilized by soaking in 10% sodium hypochlorite (10% v/v 1833 West Southern Avenue in dH2O) for 5 minutes. They were rinsed once in distilled Mesa, Arizona 85202 H20, surface sterilized in 95% ethanol, flamed and trans- ferred to a sterile surface.
    [Show full text]