transformation

View more Science videos

For more information on transformation, visit Britannica.com.

The addition of deoxyribonucleic acid (DNA) to living cells, thereby changing their genetic composition and properties. The recipient bacteria are usually closely related to the donor strain. The process may occur in natural conditions, for example, in a host animal infected with two parasitic strains, and indeed it might play a part in the rapid evolution of pathogenic bacteria. There are several species of bacteria in which transformation has been achieved in the laboratory.

That bacterial transformation is true genetic transmission on a small scale, rather than controlled mutation, is demonstrated by the following characteristics: (1) A specific trait is introduced, coming always from donors bearing the trait. (2) The trait is transferred by determinant, genelike material far less complex than whole cells or nuclei, and this material, DNA, is known to be present in gene-carrying chromosomes. (3) The trait is inherited by the progeny of the changed bacteria. (4) The progeny produce, when they grow, increased amounts of DNA carrying the specific property. (5) The traits are transferred as units exactly in the patterns in which they appear or in which they are induced by mutation. (6) The DNA transmits the full potentialities of the donor strain, whether these are in an expressed or in a latent state. (7) The traits are often attributable to the presence of a specific gene-determined enzyme protein. (8) Certain groups of determinants may occur “linked” within DNA molecules, just as genes may be linked, and if so, heat denaturation, radiation, or enzyme action will inactivate or separate them just to the extent that they can damage or break apart the DNA molecules. (9) Linked determinants, while transforming a new cell, may become exchanged (recombined) between themselves and their unmarked or unselective alternate forms in such a way that they bring about genetic variation, and in a pattern indicating the existence of larger organized genetic units. See also Bacterial genetics; Gene.

Through the application of a number of procedures prior to adding the DNA, transformation was extended first to many different bacterial species and then to eukaryotic cells. Today almost any cell type can be transformed. In some cases, tissues can be injected directly with naked DNA and transformed. However, unlike with bacteria, the naked DNA adds almost anywhere in the genome rather than recombining with its indigenous homolog. However, with special highly selective procedures, homologous recombination can be obtained. By treating embryonic stem cells and adding them to embryos that then go to term, specific and nonspecific transgenic animals can be obtained (for example, mice). See also Genetic engineering.

When the source of the DNA is some entity capable of independent replication, such as a virus or plasmid, the phenomenon is called transfection. If foreign DNA is then inserted into these entities, the result is recombinant DNA that can lead to transduction. See also Molecular biology; Transduction (bacteria).

noun

The process or result of changing from one appearance, state, or phase to another: change, changeover, conversion, metamorphosis, mutation, shift, transfiguration, translation, transmogrification, transmutation, transubstantiation. See change/persist.

Definition: complete change
Antonyms: preservation, sameness, stagnation

Transformation is one of three basic mechanisms for genetic exchange in bacteria. Transformation may be either a natural process—that is, one that has evolved in certain bacteria—or it may be an artificial process whereby the recipient cells are forced to take up DNA by a physical, chemical, or enzymatic treatment. In both cases, exogenous DNA (DNA that is outside the host cell), is taken into a recipient cell where it is incorporated into the recipient genome, changing the genetic makeup of the bacterium.

Natural Transformation

Natural transformation is a physiological process that is genetically encoded in a wide range of bacteria. Most bacteria must shift their physiology in order to transform DNA; that is, they must become "competent" for taking up exogenous DNA. There appear to be two basic mechanisms by which bacteria can become competent for transformation. In some bacteria, including Streptococcus pneumoniae and Bacillus subtilis, competence is externally regulated. These bacteria produce and secrete a small protein called competence factor that accumulates in the growth medium.

When the bacterial culture reaches a sufficient density, the concentration of competence factor reaches a level high enough to bind receptors on the outside of the cell. This event causes an internal signal to turn on the expression of the genes needed for transformation. Thus, competence development is controlled by cell density. There are a number of other bacterial functions that are similarly regulated, and these processes are collectively called quorum sensing mechanisms. In other bacteria, including Haemophilus influenzae and Pseudomonas stutzeri, competence development is internally regulated. When there is a shift in the growth dynamics of the bacterium, an internal signal triggers competence development.

Once competence is induced, three additional steps are required for natural transformation. After induction of competence, double-stranded DNA is bound to specific receptors on the surface of the competent cells. These receptors are lacking in noncompetent cells. The double-stranded DNA is nicked and one strand is degraded while the other strand enters the cell. This process is called DNA uptake. Finally, the recombination enzymes of the recipient cell will bind the single-strand DNA that has entered it, align it with its homologous DNA on the recipient chromosome, and recombine the new DNA into the chromosome, incorporating any genetic differences that exist on the entering DNA.

Artificial Transformation

While a wide variety of bacteria can transform naturally, many species cannot take up DNA from an outside source. In some cases DNA can be forced into these cells by chemical, physical, or enzymatic treatment. This is especially important in genetic engineering, as artificial transformation is essential for the introduction of genetically altered sequences into recipient cells. One of the two most common methods is a chemical process where cells are heat-shocked, then treated with the DNA and a high concentration of calcium ions. The calcium ions precipitate the DNA on the surface of the cell, where the DNA is forced into the recipient.

More recently a new method, called electroporation, has been used to introduce DNA by artificial transformation. In this process a suspension of recipient bacteria and transforming DNA is placed in a container with metal sides. A high-voltage electrical current is passed through the sample, temporarily creating small pores, or channels, in the membranes of the bacteria. The DNA enters the cells and the pores close. Thus, exogenous (outside) DNA is introduced into the recipient.

Because exogenous DNA is not enclosed within cell walls, it is susceptible to enzymes that degrade DNA, called DNases. A hallmark of transformation is that it is sensitive to DNase, while the other two processes of genetic exchange, transduction and conjugation, are DNase resistant. Transduction is DNase resistant because the DNA is protected inside a viral protein coat. Conjugation is DNase resistant because fusion occurs between donor and recipient cells, meaning the DNA is never exposed to the outside environment or to enzymes.

Discovery of Transformation

The first report of transformation was an example of natural transformation. Dr. Frederick Griffith was a public health microbiologist studying bacterial pneumonia during the 1920s. He discovered that when he first isolated bacteria from the lungs of animals with pneumonia, the bacterial colonies that grew on the agar plates were of reasonable size and had a glistening, mucoid appearance. When he transferred these colonies repeatedly from one agar plate to another, however, mutant colonies would appear that were much smaller and were chalky in appearance. He designated the original strains as "smooth" strains, and the mutants as "rough" strains. When Griffith injected mice with smooth strains they contracted pneumonia, and smooth strains of the bacterium could be reisolated from the infected mice. However, when he infected the mice with rough strains they did not develop the disease. The smooth strains were capable of causing disease, or were "virulent," while the rough strains did not cause disease, or were "aviruluent."

Griffith questioned whether the ability to cause disease was a direct result of whatever product was making the bacterial colonies smooth, or whether rough strains of the bacterium were less capable of establishing disease for some other reason. To investigate this idea, he prepared cultures of both bacterial types. He pasteurized (killed) each of these cultures by heating them for an hour and then injected the heat-treated extracts into mice. His hypothesis was that if the bacteria had to be living to cause disease, heat-treating that killed the bacteria would prevent disease. If, on the other hand, the smooth material was itself a toxin, heating would not destroy it, meaning heated extracts of smooth strains would continue to cause disease. When Griffith injected heated extracts of both smooth and rough strains into mice, neither caused disease. This suggested to him that only living smooth cells could cause disease.

In his next experiment he coinjected unheated, live rough bacteria with heat-treated, dead smooth bacteria into mice. All of the mice developed disease, and when bacteria were isolated from the lungs of the diseased mice, all the isolates were smooth. This led Griffith to propose that there was some "transforming principle" in the heated smooth extract that converted the rough strains back to smooth ones capable of causing diseases. Griffith was not able to determine the nature of this transforming principle, but his experiments suggested that some "inheritable" material present in the heated extract could genetically convert strains from one colony type to another.

Approximately ten years later, another research team, that of Oswald Avery, Colin Munro MacLeod, and Maclyn McCarty, followed up on Griffith's experiments by enzymatically and biochemically characterizing the heated transforming extracts that Griffith had produced. Their studies indicated that the transforming principle was deoxyribonucleic acid (DNA), providing the first definitive evidence that DNA was the inheritable material.

Bibliography

Curtis, Helen, and N. Susan Barnes. Invitation to Biology, 5th ed. New York: WorthPublishers, 1994.

Ingraham, John, and Catherine Ingraham. Introduction to Microbiology, 2nd ed. PacificGrove, CA: Brooks/Cole Publishing, 1999.

Madigan, Michael T., John Martinko, and Jack Parker. Brock Biology of Microorganisms, 10th ed. Upper Saddle River, NJ: Prentice Hall, 2000.

Streips, Uldis N., and Ronald E. Yasbin. Modern Microbial Genetics, 2nd ed. Hoboken, NJ: John Wiley & Sons, 2002.

—Gregory Stewart

The changing of data into another form. For example, absolute distance may be plotted as time-distance in a cartogram.

Transformation is the process by which a cell or an organism incorporates foreign DNA. Transformation usually occurs between a plasmid and a bacterium. The transformed cell or organism then produces the protein encoded by the foreign DNA. In order to determine whether cells have been transformed, the foreign DNA usually contains a marker, such as the gene for penicillin resistance. Only cells with the resistance gene will be able to grow in a culture medium containing penicillin.

Wilfred R. Bion conceived of transformations as the changes that the analysand's sense impressions of emotional experience undergo to become a progressive series of mental realizations. They are akin to the transformations that food undergoes in the digestive system to become protoplasm. The concept also belongs to the mathematical concepts that Bion employed to bring more rigor to psychoanalytic understanding. In this way, he was attempting to make psychoanalysis more scientific. This period in his work overlaps with the next period in his work, developing psychoanalysis as an "intuitionistic science."

Briefly put, Bion envisions psychoanalytic transformations as the psychoanalyst's attempt to help the analysand transform that part of an emotional experience of which he is unconscious into an emotional experience of which he is conscious. Transforming here would be changing the form but not the fundamental nature or invariant aspect of the emotional experience. In this way the analyst helps the analysand achieve private or personal knowledge about his emotional life. Bion states his theory in a rigorous mathematical notation in which his symbols have the following meanings: O = the symptom or analytic object; T = transformation; t = the representation of the transformation; K = knowledge link; β = beta elements, sense impressions of emotional experience; α = alpha elements, elements suitable for further mental processing; p = patient; a = analyst. Bion states, "I shall regard only those aspects of the patient's behavior which are significant as representing his view of O; I shall understand what he says or does as if it were an artist's painting. In the session the facts of his behavior are like facts of a painting and from them I must find the nature of his representations (or, in terms of my notation, the nature of that which I denote by the sign T(patient)β). From the analytic treatment as a whole I hope to discover from the invariants in this material what O is, what he does to transform O (that is to say, the nature of T(patient)α) and, consequently, the nature of T(patient). This last point is the set of transformations in the group of transformations, to which his particular transformation (T(patient)) is to be assigned. As I am concerned with the nature (or . . . meaning) of these phenomena, my problem is to determine the relationship between the unknowns: T(patient), T(patient)α, and T(patient)β. Only in the last of these have I any facts on which to work. . . . I shall make three assumptions: (i) that the patient is talking about something (O); (ii) that something, O, has impressed him and that he has transformed the impression by the process represented by Tpα and (iii) that his representation tpβ is comprehensible" (Bion, 1965).

Bion considers the emotional experience of the analysand and of the analyst to be O (the symptom or analytic object) but each has his distinct experience of O: Op (patient), and Oa (analyst). The analyst must, with his alpha function, deduce the transformation O →Tpα →Tpβ, which is then translated by the analyst as O →Taα →Taβ.

Bion considers there to be four kinds of transformations in clinical practice: (a) "rigid-motion transformations," which involve little alteration and which correspond directly to past events that may now be relived in the (classical) transference; (b) "projective transformations," which correspond to Melanie Klein's concept of projective identification; (c) "transformations in hallucinosis," which occur only in psychosis, and (d) "transformation in O," by which Bion seems to mean a transformation both from the ineffable nature of the analytic object, the analysand's symptom, and through K (the knowledge link), to yet another state, that of Absolute Truth or Ultimate Reality, the Godhead.

Bion states, "The bearing on psycho-analysis and interpretation of what I have said may seem obscure; it is this: The beginning of a session has the configuration already formulated in the concept of the God-head. From this there evolves a pattern and at the same time the analyst seeks to establish contact with the evolving pattern. This is subject to his Transformation and culminates in his interpretation Ta b. I am aware of the problems I have left without attempting an approach to their solution. . . . In this book I draw attention to a few of the problems which present themselves in analytic material and offer suggestions for clarifying, first observation and then, assessment of what has been observed" (1965).

Transformations (1965) seems to represent Bion's last venture in employing mathematical notation to bring scientific rigor to clinical psychoanalytic phenomena. Transformations in O constitute "a bridge to a new science," the intuitionistic, to which he thereafter bent his efforts. Though mathematical, Transformations was the third in a series of foundational works that was gradually to alter how analysts regarded clinical material and their personal (T(analyst)) relationship to it. Having already defined the mind that had to develop in order to think "the thoughts without a thinker" (beta elements, emotional experiences in themselves), he then undertook to define how these thoughts evolve from sense impressions of emotional experience (beta elements) to alpha elements suitable for further mental processing. From there he defined the steps of "mentally digestive transformation" that these beta, and then alpha, elements must undergo in the analysand and in the analyst in order to qualify for status in a scientific deductive system or fall by the wayside because of invidious K. O is the beginning and the end of the transformational cycle. Bion's epistemological transformation of psychoanalytic metapsychology was then in place.

Bibliography

Bion, Wilfred R. (1965). Transformations: Change from learning to growth. London: Heinemann.

—JAMES S. GROTSTEIN

The vampire traditionally could transform itself into various animals, particularly a bat, a wolf, or a dog. It could also transform into a dust-like cloud or a mist. This attribute was often referred to as shape-shifting, and vampires figures often graded into shape-shifters, a particular kind of demon entity in European mythologies. It was also an attribute often tied to witchcraft. In the novel by Bram Stoker, Dracula's first recorded transformations were observed by Jonathan Harker but occurred in such a manner that neither Harker (nor the reader) realized what was happening. During the course of the novel, Dracula transformed into a wolf (to leave the ship that had wrecked at Whitby) a bat (throughout the novel), and as mist (in order to enter Mina Murray's bedroom). In one of his encounters with the three vampire women in Castle Dracula, Harker noted that they appeared to him first as a swirl of dust in the moonlight. Twenty-five years prior to Dracula, the transformation of the vampire into an animal had also been an integral part of Sheridan Le Fanu 's story Carmilla In that story, Carmilla transformed into a cat on several occasions.

The ability of vampires to transform into animals was part of the folklore of the majority of countries that include a vampire figure. The Japanese, for example, had a well-known tale of a vampire who assumed the form of the wife of Prince Nabeshima and then transformed into a cat to hunt her victims. In various countries in Eastern Europe, the Slavic vampire could transform into a wide variety of animals, and on rare occasions, even some plants and farm implements. The ancient Roman vampire often appeared as a bird, a crow, or screech owl. Their transformation into wolves tied vampires to werewolves, the exact relationship being a matter of scholarly disagreement.

In Dracula Abraham Van Helsing also proposed the idea that vampire transformations were facilitated at certain hours. Dracula could change into various forms during the evening at will. However, during the daylight hours he could change only at noon, or exactly at sunrise and sunset. Most likely, Stoker borrowed this idea from Emily Gerard, who reported that Romanians believed that specific times of the day had special significance. Among these were the "exact hour of noon," a precarious time because an evil spirit, Pripolniza, was active. The idea of special powers tied to certain times of the day was dropped by subsequent writers using the vampire theme.

More recent novels and movies have disagreed on the issue of the vampire's power of transformation. The many remakes of Dracula have been fairly consistent with his ability to transform into an animal, at least a bat. In the 1992 Bram Stoker's Dracula his ability to transform was a major sub-theme of the plot. However, the influential novels by Chelsea Quinn Yarbro and Anne Rice have denied the vampire's ability to transform, as have the more recent novels of P N Elrod and Elaine Bergstrom. Yarbro, even more than Rice, stripped her vampires of most of their supernatural abilities, although they were left with great strength and a long life. The trend initiated by Rice and Yarbro carried over into many books and motion pictures that have stepped back from Dracula and created other vampire characters who exist in a contemporary setting. Thus, transformation has not been an element in the life of the vampires in such recent movies as Vamp (1986), Near Dark (1987), The Lost Boys (1987), and Innocent Blood (1992), or of the television series Forever Knight

1. or genetic transformation the intraspecific and interspecific transfer of genetic information by means of 'naked' extracellular DNA in bacteria. In transformation, in contrast to transduction, the DNA not integrated into the recipient's genome cannot function and manifest its genetic information phenotypically.
2. characteristic and inherited changes produced in cells in culture when they have been treated with certain viruses (which may be DNA- or RNA-containing), or with chemical carcinogens, or with X-rays, or when they have been subjected to genetic modification by DNA technology. In animal cells, these changes include certain specific alterations in morphology (especially of the nucleus) and stainability, and the cells usually show a loss of contact inhibition and can give rise to neoplastic growth on injection into animals. The term also refers to corresponding changes occurring in cells in vivo.
3. or blast transformation or lymphocyte transformation the morphological and other changes that occur in both B and T lymphocytes when they are cultured in the presence of an antigen to which they are primed, or that occur nonspecifically in B lymphocytes when they are exposed to a mitogen (e.g. certain lectins). The lymphocytes increase in size and develop a basophilic ribosome-rich cytoplasm, a prominent nucleolus, and a paler-staining nucleus. After about three days these cells resemble blast cells.
4. the alteration produced in certain specific hormone-receptor proteins, present in the extranuclear region of hormone-responsive cells, when the hormone binds to them. This alteration is accompanied by the migration of the hormone — receptor complexes to the nucleus.
5. or nuclear transformation (of an atomic nucleus) the change of one nuclide to another.

Change of form or structure; conversion from one form to another. In oncology, the change that a normal cell undergoes as it becomes malignant. In statistics a functional change to the variable.

• bacterial t. — the process of intercellular transfer of genetic information in which a small portion of the total DNA of a lysed bacterium enters a related bacterium and is incorporated into the DNA genome of the recipient.
• cell t. — the changes in types of proteins expressed and growth characteristics that take place in cells infected by some viruses, including tumor formation by retroviruses.

• Genetics, Heredity, and Evolution - transformation: genetic change induced by incorporation of DNA from one bacterial cell into another
• Religious States and Experiences - transformation: experience in which adherent to religion moves from one state to another, as by conversion, leap of faith, or following a path

Look up transformation in Wiktionary, the free dictionary.

Transformation may refer to:

Contents 1 Mathematics 2 Natural science 3 Computing 4 Fiction 5 Other uses 6 See also

Mathematics

• Transformation (function)
• Transformation (combinatorics)
• Integral transform
• Data transformation (statistics)
• Transformation matrix

Natural science

• Phase transformation, a physical transition from one medium to another
• Chemical transformation
• Metamorphosis, the biological process of changing physical form after birth or hatching
• Malignant transformation, the process of cells becoming cancerous
• Transformation (genetics), genetic alteration of a cell by DNA uptake
• Transformation optics, generalized optical devices

Computing

• Data transformation
• Model transformation
• Program transformation
• XML transformation
• Transformation of text

Fiction

• Transformation (novel), by Carol Berg
• Shapeshifting, a type of transformation common in mythology and folklore
• Henshin, a type of transformation common in anime, manga and tokusatsu
• Transformation, an alternate title for The Marble Faun, a novel by Nathaniel Hawthorne

Other uses

• Maturity Transformation (MT): use/borrow cheap (e.g. short-term) money to invest at a more lucrative rate (typically long-term projects for a firm; or longer-term loans if the transformer is a bank). Cf. carry trade on rates
• Transformation (law), a concept in copyright law
• Transformation (patent law)
• Transformation (Tal Wilkenfeld album)
• Transformation (Alex Skolnick Trio album)
• Transformation (music)
• Transformation, a song by Nona Hendryx
• Transformation (warfare)
• Transformation of culture
• Transformation design, a design process
• Transformation playing card
• Transformation problem, a concept in economics
• Transformational grammar
• Spiritual transformation, a psychological and New-Age concept
• Business Transformation, an idea in strategic management
• Business Network Transformation, a concept used in thinking about markets
• Transformation of precious metals - see Synthesis of precious metals
• Transformational festival

See also

• Transform (disambiguation)
• Transformation Story Archive

This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)