1. the Phenomenon of 'Like Begets Like' Is Due to (A) Genetics (B) Heredity
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Nature Medicine Essay
COMMENTARY LASKER BASIC MEDICAL RESEARCH AWARD Of maize and men, or peas and people: case histories to justify plants and other model systems David Baulcombe One of the byproducts of molecular biology cork is altogether filled with air, and that air is has been support for the ‘model system’ con- perfectly enclosed in little boxes or cells distinct cept. All living organisms are based on the same from one another.”)2 (Fig. 1). Two hundred fifty genetic code, they have similar subcellular years later, Beijerinck discovered a contagium structures and they use homologous metabolic vivum fluidum in extracts of diseased tobacco pathways. So, mechanisms can be investigated plants that he later referred to as a virus3. using organisms other than those in which In contemporary science, a green alga— the knowledge will be exploited for practical Chlamydomonas reinhardtii—is a useful model benefit. Model systems are particularly use- in the analysis of kidney disease4. However, ful in the early discovery phase of a scientific in this article, I refer to the contribution of endeavor, and recent progress in biomedical plant biology to a family of mechanisms that I science has fully vindicated their use. Jacques refer to as RNA silencing. This topic has been Monod, for example, famously justified his reviewed comprehensively elsewhere5,6, so here work on a bacterial model system by stating I focus on personal experience and my view of that “what is true for Escherichia coli is also future potential from this work. true for elephants.” My fellow laureates, Victor Ambros and Gary Ruvkun, can defend the use The early history of RNA silencing in of the worm Caenorhabditis elegans as a good plants model system and so I will focus on plants. -
Introduction and Historical Perspective
Chapter 1 Introduction and Historical Perspective “ Nothing in biology makes sense except in the light of evolution. ” modified by the developmental history of the organism, Theodosius Dobzhansky its physiology – from cellular to systems levels – and by the social and physical environment. Finally, behaviors are shaped through evolutionary forces of natural selection OVERVIEW that optimize survival and reproduction ( Figure 1.1 ). Truly, the study of behavior provides us with a window through Behavioral genetics aims to understand the genetic which we can view much of biology. mechanisms that enable the nervous system to direct Understanding behaviors requires a multidisciplinary appropriate interactions between organisms and their perspective, with regulation of gene expression at its core. social and physical environments. Early scientific The emerging field of behavioral genetics is still taking explorations of animal behavior defined the fields shape and its boundaries are still being defined. Behavioral of experimental psychology and classical ethology. genetics has evolved through the merger of experimental Behavioral genetics has emerged as an interdisciplin- psychology and classical ethology with evolutionary biol- ary science at the interface of experimental psychology, ogy and genetics, and also incorporates aspects of neuro- classical ethology, genetics, and neuroscience. This science ( Figure 1.2 ). To gain a perspective on the current chapter provides a brief overview of the emergence of definition of this field, it is helpful -
A Short History of DNA Technology 1865 - Gregor Mendel the Father of Genetics
A Short History of DNA Technology 1865 - Gregor Mendel The Father of Genetics The Augustinian monastery in old Brno, Moravia 1865 - Gregor Mendel • Law of Segregation • Law of Independent Assortment • Law of Dominance 1865 1915 - T.H. Morgan Genetics of Drosophila • Short generation time • Easy to maintain • Only 4 pairs of chromosomes 1865 1915 - T.H. Morgan •Genes located on chromosomes •Sex-linked inheritance wild type mutant •Gene linkage 0 •Recombination long aristae short aristae •Genetic mapping gray black body 48.5 body (cross-over maps) 57.5 red eyes cinnabar eyes 67.0 normal wings vestigial wings 104.5 red eyes brown eyes 1865 1928 - Frederick Griffith “Rough” colonies “Smooth” colonies Transformation of Streptococcus pneumoniae Living Living Heat killed Heat killed S cells mixed S cells R cells S cells with living R cells capsule Living S cells in blood Bacterial sample from dead mouse Strain Injection Results 1865 Beadle & Tatum - 1941 One Gene - One Enzyme Hypothesis Neurospora crassa Ascus Ascospores placed X-rays Fruiting on complete body medium All grow Minimal + amino acids No growth Minimal Minimal + vitamins in mutants Fragments placed on minimal medium Minimal plus: Mutant deficient in enzyme that synthesizes arginine Cys Glu Arg Lys His 1865 Beadle & Tatum - 1941 Gene A Gene B Gene C Minimal Medium + Citruline + Arginine + Ornithine Wild type PrecursorEnz A OrnithineEnz B CitrulineEnz C Arginine Metabolic block Class I Precursor OrnithineEnz B CitrulineEnz C Arginine Mutants Class II Mutants PrecursorEnz A Ornithine -
DNA: the Timeline and Evidence of Discovery
1/19/2017 DNA: The Timeline and Evidence of Discovery Interactive Click and Learn (Ann Brokaw Rocky River High School) Introduction For almost a century, many scientists paved the way to the ultimate discovery of DNA and its double helix structure. Without the work of these pioneering scientists, Watson and Crick may never have made their ground-breaking double helix model, published in 1953. The knowledge of how genetic material is stored and copied in this molecule gave rise to a new way of looking at and manipulating biological processes, called molecular biology. The breakthrough changed the face of biology and our lives forever. Watch The Double Helix short film (approximately 15 minutes) – hyperlinked here. 1 1/19/2017 1865 The Garden Pea 1865 The Garden Pea In 1865, Gregor Mendel established the foundation of genetics by unraveling the basic principles of heredity, though his work would not be recognized as “revolutionary” until after his death. By studying the common garden pea plant, Mendel demonstrated the inheritance of “discrete units” and introduced the idea that the inheritance of these units from generation to generation follows particular patterns. These patterns are now referred to as the “Laws of Mendelian Inheritance.” 2 1/19/2017 1869 The Isolation of “Nuclein” 1869 Isolated Nuclein Friedrich Miescher, a Swiss researcher, noticed an unknown precipitate in his work with white blood cells. Upon isolating the material, he noted that it resisted protein-digesting enzymes. Why is it important that the material was not digested by the enzymes? Further work led him to the discovery that the substance contained carbon, hydrogen, nitrogen and large amounts of phosphorus with no sulfur. -
The Population Problem Inherited Evolutio
2000 Earthlearningidea - http://www.earthlearningidea.com/ top edge of Sorting out the evolution of evolution headlines page Lay out your own timeline of how the theory of evolution developed Cut off the left hand edge of these four Earthlearningidea sheets and stick them together to form a timeline. Then stick it down on a bench or table. The ‘Evolution of evolution’ timeline Cut out the milestone boxes in the evolution of evolutionary theory below into strips. Leave the dates attached for less able pupils, but remove them for the more able. Then invite the pupils to sort out the headlines 1975 and place them in the correct places on the timeline – to show how evolutionary theory Photo: Chris King evolved. Species static This image is in the public The early part of the bible is interpreted to show that domain because species are static and there is no evolution. The date of its copyright has expired. 1650 creation of all species is calculated by Archbishop Ussher as 4004BC. Archbishop Ussher Evolution – but how? This image is in the public Early evolutionary ideas are presented by natural domain because 1740 philosophers, Pierre Maupertuis and Erasmus Darwin. its copyright has - expired. 1796 1950 Pierre Maupertuis The population problem This image is in the public Thomas Malthus publishes his idea that populations domain because increase geometrically (2,4,16) whilst food production its copyright has 1798 only increases arithmetically (2,3,4) so there must be expired. population crashes. Thomas Malthus Inherited evolution Permission is granted to copy, Jean-Baptiste Lamarck develops his evolutionary theory distribute and/or – that evolution occurs because offspring change in modify this document under 1800 response to the environment, and these changes are the terms of the inherited from their parents (later shown to be 1925 GNU Free incorrect). -
Goings on in Mendel's Garden
40 Evolutionary Anthropology CROTCHETS & QUIDDITIES Goings on in Mendel’s Garden KENNETH WEISS The honorable monk probably didn’t cheat. But he led us astray in other ways. Gregor Mendel gave us the tools by discussed. But this may have inadver- which to do modern genetics, and we tently led us astray, in ways for which have a century of progress to show for we are paying a price today. The arti- it. We properly credit Mendel and his ficial nature of his experiments lured peas for showing us the particulate us into confusing the inheritance of nature of inheritance, but his work traits with the inheritance of genes. both enabled and disabled evolution- And this in turn has led to an unwar- ary thinking for several decades after ranted phenogenetic (see Note 1) de- its rediscovery. Since the factors he terminism that impairs our under- studied didn’t change over genera- standing of biology. tions, Mendel’s discoveries solved the problem that perplexed Darwin, that BLENDING IN blending inheritance would swamp variation and prevent evolution from Mendel wasn’t trying to explain evo- happening. Yet, for the same reason, lution. He knew of traits that varied Mendel’s work impeded evolutionary continuously in his experimental pea thought because evolution requires species, Pisum sativum, and appeared Figure 1. Mendel. change, and discrete variation was to blend in darwinian fashion from also incompatible with darwinian one generation to the next. But he gradualism. Eventually things were wanted to breed agriculturally valu- worked out, we got our unified theory able strains, so he avoided such traits used pea strains that differed only by (the neodarwinian Synthesis), and it and instead selected strains of pea the single traits he reported for each rested on Mendel’s discoveries. -
Genome As a Multipurpose Structure Built by Evolution Michel Morange
1 Genome as a multipurpose structure built by evolution Michel Morange, Centre Cavaillès, République des savoirs USR 3608, Ecole normale supérieure, 29 rue d’Ulm, 75230 Paris Cedex05, France Email: [email protected] Abstract The publication in 2012 of the results of the ENCODE program generated an acrimonious debate about the role of junk DNA. This debate is a symptom of the difficulties of dovetailing functional and evolutionary descriptions of genomes. My argument is that extant genomes are the result of a progressive evolutionary construction. To the basic function – to give rise to RNA and proteins – have been successively added other functions – regulation by microRNA and epigenetic marks, for instance. This process of complexification was not a regular one, but the result of a complex evolutionary history, different for the different genomes. Better knowledge of the evolutionary history of genomes would help to understand these structures and their functions. Historians and philosophers of biology have amply discussed the difficulty, even the impossibility, of providing a precise definition of a gene (Beurton et al. 2000). The genome no longer appears as a collection of similar genes, but as a multitasking structure formed of different types of genetic elements (Gingeras 2006). Participants in these debates nonetheless often agree on one issue, that the genome is (and has to be) something well defined: a collection of genes, a 2 reservoir of junk DNA, or a structure filled with regulatory sequences. My point of view will be different: the genome is what evolution has progressively made of it. This vision has three important consequences. -
INTRODUCTION to GENETICS Table of Contents Heredity, Historical
INTRODUCTION TO GENETICS Table of Contents Heredity, historical perspectives | The Monk and his peas | Principle of segregation Dihybrid Crosses | Mutations | Genetic Terms | Links Heredity, Historical Perspective | Back to Top For much of human history people were unaware of the scientific details of how babies were conceived and how heredity worked. Clearly they were conceived, and clearly there was some hereditary connection between parents and children, but the mechanisms were not readily apparent. The Greek philosophers had a variety of ideas: Theophrastus proposed that male flowers caused female flowers to ripen; Hippocrates speculated that "seeds" were produced by various body parts and transmitted to offspring at the time of conception, and Aristotle thought that male and female semen mixed at conception. Aeschylus, in 458 BC, proposed the male as the parent, with the female as a "nurse for the young life sown within her". During the 1700s, Dutch microscopist Anton van Leeuwenhoek (1632-1723) discovered "animalcules" in the sperm of humans and other animals. Some scientists speculated they saw a "little man" (homunculus) inside each sperm. These scientists formed a school of thought known as the "spermists". They contended the only contributions of the female to the next generation were the womb in which the homunculus grew, and prenatal influences of the womb. An opposing school of thought, the ovists, believed that the future human was in the egg, and that sperm merely stimulated the growth of the egg. Ovists thought women carried eggs containing boy and girl children, and that the gender of the offspring was determined well before conception. -
Gregor Mendel and ‘‘Myth-Conceptions’’
COMMENTS AND CRITICISM Gregor Mendel and ‘‘Myth-Conceptions’’ JULIE WESTERLUND Texas State University, San Marcos, TX 78666, USA DANIEL FAIRBANKS Brigham Young University, Provo, UT 84602, USA Received 4 November 2003; accepted 11 December 2003 DOI 10.1002/sce.20007 Published online 7 June 2004 in Wiley InterScience (www.interscience.wiley.com). In a recent article, in Science Education, entitled “Scientific Myth-Conceptions” (Allchin, 2003), the author aptly criticized “popular histories of science that romanticize scien- tists, inflate the drama of their discoveries and cast scientists and the process of sci- ence in monumental proportion” (p. 329). The first example cited of such romanticism is Gregor Mendel. However, there is also tendency among some historians, such as Monaghan and Corcos (1990) and Di Trocchio (1991), to disparage Mendel’s contributions with claims that contradict his original writings (Orel, 1996; Orel & Hartl, 1994; Fairbanks & Rytting, 2001). Such is also the case with the depiction of Gregor Mendel in Allchin’s article. Following the lead of Monaghan and Corcos (1990), the article credits Mendel’s principle of independent assortment not to him but to geneticists who worked several years after the rediscovery of his work. It states: “in his classic 18651 paper, Mendel did not explicitly formulate a ‘Second Law,’ the principle of independent assortment,” and “geneticists did not distinguish ‘Mendel’s’ 1st and 2nd laws until several years after the revival of his work when they encountered anomalous ratios in the offspring” (Allchin, 2003, p. 332). These assertions concerning Mendel’s Second Law are easily refuted. Although Monaghan and Corcos (1990) claimed that Mendel did not articulate the principle of independent assortment, other authors, among them Di Trocchio (1991), Orel (1996), and Fairbanks and Rytting (2001), pointed out that Mendel clearly stated the principle of independent Correspondence to: Julie Westerlund; e-mail: [email protected] 1 Although Mendel presented his paper verbally in 1865, it was published in 1866. -
The Hereditary Statistics of Hugo De Vries
Acta Bot. Neerl. 47(4), December 1998, p. 427—463 The Hereditary Statistics of Hugo de Vries Erik Zevenhuizen Institute for Systematics and Population Biology, Faculty of Biology, University of Amsterdam, Kruislaan 318, 1098 SM Amsterdam, The Netherlands CONTENTS Introduction 427 The theory of pangenesis 429 The use of statistics 432 The laws of chance 435 The Veronica-note: the 5/16-law 439 The Veronica-note: the 1.2.1-law 446 The Aster-note 449 Conclusion: in search of the laws of nature 452 Keywords: Hugo de Vries, Mendel’s laws, mutation theory, pangenesis. INTRODUCTION de Vries is remembered the first of three botanists in Today, Hugo chiefly as who, 1900, publicly announced that they had discovered what we now call the laws of Mendel. All three maintainedthat they had foundthe laws on their own and that, at the moment they did their discovery, they had been completely unaware of the fact that the Austrian amateur botanist Gregor Mendel (1822-1884) had published similar conclusions already in 1866. Whereas his contributions to the development of evolutionary thought are De Vries is credited in generally unappreciated or simply unknown, many surveys on the history of genetics for his rediscovery of Mendel’s laws. It is generally accepted that, together with his two fellow-rediscoverers, Carl Correns from Tubingen and Erich von Tschermak-Seysenegg from Vienna, De Vries made these basic rules of genetics scientific widely known to the world. The year 1900 can be considered as the year of birth of modern genetics, and Hugo de Vries as one of the founders of the discipline. -
Darwin's Influence on Mendel: Evidence from a New Translation Of
| PERSPECTIVES Darwin’sInfluence on Mendel: Evidence from a New Translation of Mendel’s Paper Daniel J. Fairbanks*,1 and Scott Abbott† *Department of Biology and †Department of Integrated Studies, Utah Valley University, Orem, Utah 84058 ORCID ID: 0000-0001-7422-0549 (D.J.F.) ABSTRACT Gregor Mendel’s classic paper, Versuche über Pflanzen-Hybriden (Experiments on Plant Hybrids), was published in 1866, hence 2016 is its sesquicentennial. Mendel completed his experiments in 1863 and shortly thereafter began compiling the results and writing his paper, which he presented in meetings of the Natural Science Society in Brünn in February and March of 1865. Mendel owned a personal copy of Darwin’s Origin of Species, a German translation published in 1863, and it contains his marginalia. Its publication date indicates that Mendel’s study of Darwin’s book could have had no influence while he was conducting his experiments but its publication date coincided with the period of time when he was preparing his paper, making it possible that Darwin’s writings influenced Mendel’s interpretations and theory. Based on this premise, we prepared a Darwinized English translation of Mendel’s paper by comparing German terms Mendel employed with the same terms in the German translation of Origin of Species in his possession, then using Darwin’s counterpart English words and phrases as much as possible in our translation. We found a substantially higher use of these terms in the final two (10th and 11th) sections of Mendel’s paper, particularly in one key paragraph, where Mendel reflects on evolutionary issues, providing strong evidence of Darwin’sinfluence on Mendel. -
Mendel's Opposition to Evolution and to Darwin
Mendel's Opposition to Evolution and to Darwin B. E. Bishop Although the past decade or so has seen a resurgence of interest in Mendel's role in the origin of genetic theory, only one writer, L. A. Callender (1988), has concluded that Mendel was opposed to evolution. Yet careful scrutiny of Mendel's Pisum pa- per, published in 1866, and of the time and circumstances in which it appeared suggests not only that It Is antievolutlonary In content, but also that it was specif- ically written in contradiction of Darwin's book The Origin of Species, published in 1859, and that Mendel's and Darwin's theories, the two theories which were united in the 1940s to form the modern synthesis, are completely antithetical. Mendel does not mention Darwin in his Pi- [Mendel] in so far as they bore on his anal- sum paper (although he does in his letters ysis of the evolutionary role of hybrids." to Nlgeli, the famous Swiss botanist with Olby's (1979) article, entitled "Mendel whom he initiated a correspondence, and No Mendelian?," led to a number of revi- in his Hieracium paper, published In 1870), sionist views of Mendel's work and his in- but he states unambiguously in his intro- tentions, although no agreement has been duction that his objective is to contribute reached. For instance, some writers, un- to the evolution controversy raging at the like de Beer, Olby, and Callender, overlook time: "It requires a good deal of courage or minimize the evolutionary significance indeed to undertake such a far-reaching of Mendel's paper, while others maintain task; however, this seems to be the one that Mendel had little or no interest in he- correct way of finally reaching the solu- redity, an interpretation that has been op- tion to a question whose significance for posed by Hartl and Orel (1992): "We con- the evolutionary history of organic forms clude that Mendel understood very clearly must not be underestimated" (Mendel what his experiments meant for heredity." 1866).