Natural Cloning

8 Key excerpts on "Natural Cloning"

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  Gmo Sapiens: The Life-changing Science Of Designer Babies

  The Life-Changing Science of Designer Babies

  • Paul Knoepfler(Author)
  • 2015(Publication Date)
  • World Scientific

    (Publisher)

  The cloning of ESCs, for example, is called “ therapeutic cloning,” while the cloning of actual animals is referred to as “reproductive cloning.” The birth of cloning Asexual cloning in the world of botany and agriculture has been a long-time observation and practice. Plants can create clones of themselves naturally via budding or underground sprouting of new cloned individual copies. For instance, strawberry plants can create identical clones of themselves, called plantlets, on their runner stems. iii Some animals also perform a type of Natural Cloning via a process called parthenogenesis, where a female animal can produce offspring without a male. In parthenogenesis, an egg starts dividing even without having been fertilized and in some cases can form a healthy female offspring without the involvement of sperm. Parthenogenesis is not known to naturally occur in humans, but can be triggered to occur in a laboratory with an artificial stimulus, such as an electric shock to the egg. Parthenogenesis has sometimes been used to make early human embryos and then in turn human ESCs independent of IVF. Otherwise, naturally occurring parthenogenesis is limited to only a few species, including some lizards, insects, and fish, to name just three. Scientists studying cells had also observed that individual cells often essentially clone themselves every time they divide to produce two identical, or nearly identical, cells. However, as it turns out, sometimes cells divide to produce two so-called “daughter cells” that are very different from each other. In some stem cells, this process is called asymmetric division. We all have two kinds of cells: somatic cells (everyday ordinary cells) and reproductive cells (also confusingly known as germ cells). Germ cells can give rise, via fertilization or through parthenogenesis as mentioned above for eggs, to new organisms. Somatic cells normally cannot. iii http://bbc.in/1liVdqv

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  Dolly Mixtures

  The Remaking of Genealogy

  • Sarah Franklin(Author)
  • 2007(Publication Date)
  • Duke University Press Books

    (Publisher)

  Sex It is not enough simply to say that sexual reproduction has become the dominant mode of propagation among organ-isms. One must go further. Cross-fertilisation, either con-tinuous or occasional, is the really successful method of multiplication everywhere. —Edward M. East and Donald F. Jones, Inbreeding and Outbreeding I began to envisage how to advance the project that I had been thrust into, while also satisfying my own desire for original research in developmental biology. Answer: don’t just add dna to one cell embryos. Add it to plates of cultured cells, and then make embryos from the cells that had taken up the dna most effectively. In other words, as the 1980s wore on I began to see that the future of genetic engineering in animals lay through cloning. —Ian Wilmut, Keith Campbell, and Colin Tudge, The Second Creation 1 Clone is a term from botany, derived from the Greek klon , for twig. It refers primarily to regeneration via cultivation and propagation, in which reproduction is asexual and regeneration is of a part from a whole—as in the creation of a new plant from a cutting. Clone is both a noun and a verb, and has many figurative as well as practi-cal usages. In all of these senses, cloning is synonymous with copy-ing , its primary synonym. In this very general sense, it could be said that most reproduction occurs through a version of cloning to the ex-tent that asexual reproduction, mitosis, or fission—creating multiple ‘‘copies’’ of an organism—is the most common, or standard, form of replication in living things—most of which are microorganisms and prokaryotes. A common distinction between reproduction and rep-lication is the association of the former with sexual difference and the latter with more primitive copying abilities. However, a counter-view would hold that microbes and bacteria, which have a famously

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  Genetics and Evolution of Infectious Diseases

  • Michel Tibayrenc(Author)
  • 2017(Publication Date)
  • Elsevier

    (Publisher)

  9 The issue appears to be perceived differently for specialists working on Bacteria, Archaea, Eukaryota, unicellular or pluricellular animals, or plants. In this chapter, we therefore first deal with specific definitions as this subject area is littered with vocabulary that sometimes has ambiguous meanings. We then try to go back in time to the origin of asexual reproduction and recombination and attempt to describe the diversity of ways in which prokaryotes and eukaryotes reproduce asexually and recombine. Following this we describe the various ways that asexual reproduction is incorporated in eukaryotic life cycles. After a brief attempt to quantify the importance of asexuality in living organisms, the genetic consequences of asexuality are reviewed, followed by a section on the evolution and the paradox of sex. What evolutionary advantages are brought by clonality? What disadvantages result from clonality? What is the so-called twofold cost of sex? The last section deals with clonal microevolution. It consists of two parts: the first one treats neutral gene variability in clonal populations (population genetics structure) and the second addresses selective issues, such as the evolution of resistance or virulence in clonal populations. Finally, we conclude with economic and medical issues linked to asexual organisms.

  2. Definitions

  Asexual reproduction is a process of genetic propagation of genomes, following which the genomes that descend from this process are strictly identical to the parental genome, in terms of quantity and quality, at the exception of uncorrected errors during the duplication process (i.e., mutations).1 Besides cell division (e.g., mitosis in unicellular eukaryotes), many other processes correspond to clonal propagation as agametic (animals) or vegetative (plants) reproduction, ameiotic thelytokous parthenogenesis, endomitotic automictic parthenogenesis with pair formation of sister chromatids occurring before meiosis, automictic parthenogenesis with fusion of two polar bodies, deuterokous parthenogenesis, gynogenesis, apomixy, or agamospermy (reviewed in Ref. 1 ).

  Sexual reproduction is not initially a propagation mode even if it is now 100% correlated with the multiplication of many organisms (e.g., mammals). It is a recombinational repair tool,

  3 ,10 ,11

  hence the use of sexual recombination (SR) in the rest of this chapter as a synonym for meiotic sex. Recombination in the wide sense is present in the three domains of life (Archaea, Bacteria, and Eukaryota), although through very different means,3 while SR is a eukaryotic hallmark.

  3 ,10 ,12

  Recombination can take three forms in Bacteria and Archaea: conjugation, transformation, and transduction.

  3 ,13 ,14

  Conjugation concerns plasmid exchange through a specialized structure called pilus. It is unidirectional in Bacteria (donor and recipient) and is apparently bidirectional in certain Euryarchaeota.14 Transformation is the absorption of soluble naked DNA present in the microenvironment by a recipient cell, and its further inclusion (recombination), if compatible, in the chromosome. When divergence between the two sequences is less than 25%, a homologous recombination can occur (without chromosome size increase). Illegitimate integration of more divergent DNA can increase the size of the recipient chromosome. Homology-based recombination also increases recipient chromosome size. Natural transformation can be found in any eubacteria lineage, but has only been reported in 1% of recognized eubacteria species (see Ref. 15 for review) and was never observed in Archaea except in laboratory conditions, by chemical or physical induction.14 Transduction is a horizontal gene transfer mediated by viruses. It is widespread in Eubacteria,16 while in Archaea, it has been reported in methanogens (Euryarchaeota) only.14 Calling transduction, transformation, and conjugation sex is unsound and true sex, with meiosis and syngamy, is only found in eukaryotes and never in prokaryotes.3

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  Biotechs Dictionary of Biotechnology

  • Arora, Dinesh(Authors)
  • 2021(Publication Date)
  • Biotech

    (Publisher)

  clone (gr. klon, a twig or slip) 1. a group of cells or organisms that are genetically identical as a result of asexual reproduction, breeding of completely inbred organisms, or forming genetically identical organisms by nuclear transplantation. 2. group of plants genetically identical, in which all are derived from one selected individual by vegetative propagation, without the sexual process. 3. a population of cells that all carry a cloning vehicle with the same insert DNA molecule. 4. verb: To clone. To insert a DNA segment into a vector or host chromosome. See cloning . 5. a genetic replica of another organism obtained through a This ebook is exclusively for this university only. Cannot be resold/distributed. non-sexual (no fertilisation) reproduction process. Cloning by nucleus transfer involves the transfer of a donor cell (from (cultured) cells of embryonic, foetal or adult origin) into the recipient cytoplasm of an enucleated oocyte or zygote, and the subsequent development of embryos and animals. (Based on: FAO, 1999). 6. bacterial or cell colony that is formed though division of a single cell. All the cells in this colony are absolutely identical in genetic terms. 7. an exact genetic replica of a specific gene or an entire organism. 8. a collection of genetically identical copies of a cell, gene or organism reproduced asexually from a common ancestor. The clone is genetically identical to the parent. cloned strain or line a strain or line descended directly from a clone. cloning 1. the formation of clones or exact genetic replicas. 2. the mitotic division of a progenitor cell to give rise to a population of identical daughter cells or clones. 3. incorporation of a DNA molecule into a chromosomal site or a cloning This ebook is exclusively for this university only. Cannot be resold/distributed. vector. 4. animal cloning: the creation of a whole animal by mitotic divisions from a single diploid somatic cell, typically by the process of nuclear transfer.

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  The Genetics Revolution

  History, Fears, and Future of a Life-Altering Science

  • Rose Morgan(Author)
  • 2005(Publication Date)
  • Greenwood

    (Publisher)

  . . . Many years after his death, his son married a lady who had never heard of the family incident. She, however, observed precisely the same peculiarity in her husband; but his nose, from not being par- ticularly prominent, has never as yet suffered from the blows. One of his children, a girl, has inherited the same trick. 3 It seems there may be more in our genes than we often realize. Kinds of Cloning There are several different kinds of cloning which involve three distinct paths: adult-cell (somatic or body cell) cloning, natural and artificial embryo cloning, and stem-cell (therapeutic) cloning. In adult-cell cloning the development of an en- tire animal such as Dolly the sheep is obtained from a single body (somatic) cell, other than an egg or sperm, of another animal. In the first step of somatic cloning the nucleus of an egg (ovum) containing the maternal genes is removed (enucle- ated). Next, DNA from a cell from the individual to be cloned is implanted into l 6 1 T H E G E N E T I C S R E V O L U T I O N the empty egg, creating a cell with a perfect set of genes. The egg is activated in a manner similar to natural fertilization, allowed to develop into an embryo, im- planted into the womb of a female for further development into a fetus, and al- lowed to develop to a full-term baby. In natural embryo cloning an egg and a sperm are joined in vivo (in the body) and allowed to grow and divide in the body. In the laboratory, artificial (deliberate) embryo cloning begins with joining a sperm and an egg in a petri dish (in vitro fertil- ization) to form a fertilized egg called a zygote. After union, there is a natural di- vision of the zygote; normal cell division occurs into two, four, eight cells, etc. If an egg splits, identical twins are the result. In stem-cell (therapeutic) cloning an embryo is deliberately created in order to obtain and use its stem cells.

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  Human Cloning in the Media

  From Science Fiction to Science Practice

  • Joan Haran, Jenny Kitzinger, Maureen McNeil, Kate O'Riordan(Authors)
  • 2007(Publication Date)
  • Routledge

    (Publisher)

  Ian Wilmut and his colleagues make dramatic claims for cloning as a technology. However, cloning captured popular attention long before news of the birth of Dolly the sheep in 1997 and before the announcement of the ‘completion’ of the Human Genome Project in 2000. Nevertheless, in the aftermath of these two announcements there has been a renewed and intensified interest in cloning. This chapter brings the contemporary concern with human cloning under scrutiny both by locating it in a set of genealogies and by analysing the distinctive features of its recent manifestations. (See Appendix I for a timeline that attempts to consolidate these genealogies to provide an overview of key events.) In this chapter, we draw on a range of accounts by scientists and social commentators on the development of the technology of cloning and provide a brief review of some of its key representations in Western popular culture. This sets the context for our analysis of the particular configurations of cloning discourses that have become dominant in the early twenty-first century.

  It is tempting at this point to offer a dictionary definition of cloning as our starting point. For example, the Chambers Dictionary published the following definition for clone:

  n a group of two or more individuals with identical genetic makeup derived, by asexual reproduction, from a single common parent or ancestor, orig applied to plants, but later applied much more widely; any of such individuals; a person or thing closely similar to another, a copy or replica (colloq.). – vt to reproduce as a clone; to produce a clone or clones of … [Gr. klon shoot]

  (1993: 324)

  While this definition indicates some contemporary resonances of the term, it is our contention that, in the early twenty-first century, cloning has accrued a new set of meanings, associations, imagery and iconography that render this definition inadequate. This chapter provides an orientating introduction to the research on specific aspects of recent controversies about cloning that are explored in the rest of this book. It does this by offering both a longitudinal analysis of the diverse strands in the genealogy of cloning and a set of reflections about cloning in the contemporary cultural imaginary. Before moving on, it is worth noting that the practice of using Greek roots in the coinage of terminology can mislead the casual reader as to the antiquity of a term. The word ‘clone’ was not coined until the early twentieth century. In 1903, Herbert J. Webber of the US Department of Agriculture invented the term: ‘to describe a colony or organisms derived asexually from a single progenitor’ (Silver 2001; Webber 1903). Silver points out that Webber’s coinage ‘found quick acceptance among botanists and gained favour among biologists working with cells in culture’ (2001).

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  Life Liberty & the Defense of Dignity

  The Challenge for Bioethics

  • Leon Kass(Author)
  • 2002(Publication Date)
  • Encounter Books

    (Publisher)

  Asexual reproduction, which produces “single-parent” offspring, is indeed a radical departure from the natural human way, confounding all normal understandings of father, mother, sibling, grandparent and the like, and all moral relations tied thereto. It becomes even more of a radical departure when the resulting offspring is a clone derived not from an embryo but from a mature adult to whom it would be an identical twin; and when the process occurs not by natural accident (as in natural twinning) but by deliberate human design and manipulation; and when the child’s (or children’s) genetic constitution is preselected by the parent(s) (or scientists). Accordingly, as we will see, cloning is vulnerable to three kinds of concerns and objections, related to these three points: (1) cloning threatens confusion of identity and individuality, even in small-scale practice; (2) cloning represents a giant step (though not the first one) toward transforming procreation into manufacture, that is, toward the increasing depersonalization of the process of generation and toward the “production” of human children as artifacts, products of human will and design; and (3) cloning—like other forms of eugenic engineering of the next generation—represents a form of despotism of the cloners over the cloned, and thus (even in benevolent cases) a blatant violation of the inner meaning of parent-child relations, of what it means to have a child, of what it means to say “yes” to our own demise and “replacement.”

  Before turning to these specific ethical objections, let me test my claim of the profundity of the natural way by taking up a challenge posed to me by a friend. Why, he wanted to know, was I making such a fuss about “the natural human way”? Why treat our sexual mode of reproduction as anything more than the accident of evolutionary history, which, like all else produced in evolutionary history, is always subject to change? What if the given natural human way of reproduction were asexual (rather than sexual), and we now had to deal with a new technological innovation—artificially induced sexual dimorphism and the fusing of complementary gametes—whose inventors argued cogently that sexual reproduction promised all sorts of advantages, including hybrid vigor and the creation of greatly increased individuality? Would one then be forced to defend natural asexuality because it was natural? Could one claim that it carried deep human meaning?

  This is a most welcome challenge, the response to which broaches the ontological meaning of sexual reproduction and permits us to see exactly what is at stake. For it is, I submit, impossible for there to have been human life—or even higher forms of animal life—in the absence of sexuality and sexual reproduction. We find asexual reproduction only in the lowest forms of life: bacteria, algae, fungi and some lower invertebrates. Sexuality brings with it a new and enriched relationship to the world. Only sexual animals can seek and find complementary others with whom to pursue a goal that transcends their own existence. For a sexual being, the world is no longer an indifferent and largely homogeneous otherness,

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  Handbook of Animal Diversity

  • Richard E. Blackwelder(Author)
  • 2019(Publication Date)
  • CRC Press

    (Publisher)

  Implications of bisexual reproduction in various aspects of biology (genetics, evolution, behavior) are so great and of such importance, that some biologists feel that any other form of reproduction is secondary or less fundamental or less worthy of study, and so they generalize that only sexual reproduction is important. In these fields, however, it is not sexuality itself that is important but outbreeding, the mixing of genetic materials from two unrelated individuals. Few biologists have taken note of Sonneborn’s (1957) estimate that probably half of all animal individuals were the direct result of non-outbreeding reproductive processes. This large number cannot reasonably be labeled as exceptional.

  The word reproduction is often used as if it were a single process, acting in a single organ system. In reality, it is always a complex of processes, often extending throughout the life of the individual. In general, it covers all the processes which lead to production of new individuals; in reproducing individuals this is substantially equivalent to its entire life, because there is little in that life that does not contribute to reproduction. Specifically, reproduction is the origination of new organisms from pre-existing ones. In fission it is direct and immediate, but bisexual reproduction involves operation of gonads and many associated organs. This results in two sets of gametogenesis, delivery of the spermatozoa to the ova, and fusion of the two.

  When the term sexual reproduction is used to cover all reproduction by animals that produce gametes, there are a variety of unnoticed processes whose implications are omitted. These include several kinds of parthenogenesis, self-fertilization, pseudogamy or plasmogony, and autogamy. These are said to be sporadic in occurrence, but in some species in most groups of animals at least one of these reproductive processes is obligate. The species with no known true bisexual reproduction are more numerous than usually recognized. They occur in nearly all phyla of animals but are frequently overlooked.

  Asexual reproduction can be very simple and direct. A bud grows or a fragmentation suddenly produces several individuals. Whether or not one can think of sexual reproduction as simple, it does involve a great many separate proceses and often the entire life of the individual. When it is realized that reproduction in a species very often involved two or three distinct reproductive sequences (as described in a later section), then that reproduction can scarcely be thought of as simple. In many species of animals, reproductive processes are not only several and complex, but because of alternative pathways the reproduction can only be thought of as diverse.

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