|
Microbial Cooperation
Microorganisms engage in a wide variety of social interactions, including cooperation. A cooperative behavior is one that benefits an individual (the recipient) other than the one performing the behavior (the actor).West SA, Griffin AS, Gardner A. 2007. Social semantics: altruism, cooperation, mutualism, strong reciprocity and group selection. Eur. Soc. for Evol. Biol. 20:415–432. This article outlines the various forms of cooperative interactions ( mutualism and altruism) seen in microbial systems, as well as the benefits that might have driven the evolution of these complex behaviors. Introduction Microorganisms, or microbes, span all three domains of life – bacteria, archaea, and many unicellular eukaryotes including some fungi and protists. Typically defined as unicellular life forms that can only be observed with a microscope, microorganisms were the first cellular life forms, and were critical for creating the conditions for the evolution of more complex multicellul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microorganisms
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in older texts. The informal synonym ''microbe'' () comes from μικρός, mikrós, "small" and βίος, bíos, "life". is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from sixth century BC India. The scientific study of microorganisms began with their observation under the microscope in the 1670s by Anton van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s, Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera, diphtheria, and anthrax. Because ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelating Agents
Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity, as in the case of zinc and its use as a maintenance therapy to prevent the absorption of copper in people with Wilson's disease. Chelation is useful in applications such as providing nutritional supplements, in chelation therapy to remove toxic metals from the body, as contrast agents in MRI scanning, in manufacturing using homogeneous catalysts, in chemical water treatment to assist in the removal of metals, and in fertilizers. Chelate effect The chelate effect is the greater affinity of chelating ligands for a metal ion than that of similar nonchelating (monodentate) ligands for the same met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Collapse
Ecological collapse refers to a situation where an ecosystem suffers a drastic, possibly permanent, reduction in carrying capacity for all organisms, often resulting in mass extinction. Usually, an ecological collapse is precipitated by a disastrous event occurring on a short time scale. Ecological collapse can be considered as a consequence of ecosystem collapse on the biotic elements that depended on the original ecosystem. Ecosystems have the ability to rebound from a disruptive agent. The difference between collapse or a gentle rebound is determined by two factors—the toxicity of the introduced element and the resiliency of the original ecosystem. Through natural selection the planet's species have continuously adapted to change through variation in their biological composition and distribution. Mathematically it can be demonstrated that greater numbers of different biological factors tend to dampen fluctuations in each of the individual factors. Scientists can predict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacterial Growth
250px, Growth is shown as ''L'' = log(numbers) where numbers is the number of colony forming units per ml, versus ''T'' (time.) Bacterial growth is proliferation of bacterium into two daughter cells, in a process called binary fission. Providing no event occurs, the resulting daughter cells are genetically identical to the original cell. Hence, bacterial growth occurs. Both daughter cells from the division do not necessarily survive. However, if the surviving number exceeds unity on average, the bacterial population undergoes exponential growth. The measurement of an exponential bacterial growth curve in batch culture was traditionally a part of the training of all microbiologists; the basic means requires bacterial enumeration (cell counting) by direct and individual (microscopic, flow cytometry), direct and bulk (biomass), indirect and individual (colony counting), or indirect and bulk (most probable number, turbidity, nutrient uptake) methods. Models reconcile theory with th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wild Type
The wild type (WT) is the phenotype of the typical form of a species as it occurs in nature. Originally, the wild type was conceptualized as a product of the standard "normal" allele at a locus, in contrast to that produced by a non-standard, "mutant" allele. "Mutant" alleles can vary to a great extent, and even become the wild type if a genetic shift occurs within the population. Continued advancements in genetic mapping technologies have created a better understanding of how mutations occur and interact with other genes to alter phenotype. It is now appreciated that most or all gene loci exist in a variety of allelic forms, which vary in frequency throughout the geographic range of a species, and that a uniform wild type does not exist. In general, however, the most prevalent allele – i.e., the one with the highest gene frequency – is the one deemed wild type. The concept of wild type is useful in some experimental organisms such as fruit flies ''Drosophila melanogaster'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escherichia Coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly found in the lower intestine of warm-blooded organisms. Most ''E. coli'' strains are harmless, but some serotypes ( EPEC, ETEC etc.) can cause serious food poisoning in their hosts, and are occasionally responsible for food contamination incidents that prompt product recalls. Most strains do not cause disease in humans and are part of the normal microbiota of the gut; such strains are harmless or even beneficial to humans (although these strains tend to be less studied than the pathogenic ones). For example, some strains of ''E. coli'' benefit their hosts by producing vitamin K2 or by preventing the colonization of the intestine by pathogenic bacteria. These mutually beneficial relationships between ''E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Game Theory
Game theory is the study of mathematical models of strategic interactions among rational agents. Myerson, Roger B. (1991). ''Game Theory: Analysis of Conflict,'' Harvard University Press, p.&nbs1 Chapter-preview links, ppvii–xi It has applications in all fields of social science, as well as in logic, systems science and computer science. Originally, it addressed two-person zero-sum games, in which each participant's gains or losses are exactly balanced by those of other participants. In the 21st century, game theory applies to a wide range of behavioral relations; it is now an umbrella term for the science of logical decision making in humans, animals, as well as computers. Modern game theory began with the idea of mixed-strategy equilibria in two-person zero-sum game and its proof by John von Neumann. Von Neumann's original proof used the Brouwer fixed-point theorem on continuous mappings into compact convex sets, which became a standard method in game theory and mathem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melvin Dresher
Melvin Dresher (born Dreszer; March 13, 1911 – June 4, 1992) was a Polish-born American mathematician, notable for developing, with Merrill Flood, the game theoretical model of cooperation and conflict known as the Prisoner's dilemma while at RAND in 1950 ( Albert W. Tucker gave the game its prison-sentence interpretation, and thus the name by which it is known today). Dresher came to the United States in 1923. He obtained his B.S. from Lehigh University in 1933 and his Ph.D. from Yale University in 1937; the title of his dissertation was "Multi-Groups: A Generalisation of the Notion of Group." Dresher worked as instructor of mathematics, Michigan State College, 1938–1941; statistician, War Production Board, 1941–1944; mathematical physicist, National Defense Research Committee, 1944–1946; professor of mathematics, Catholic University, 1946–1947; research mathematician, RAND, from 1948. He was the author of several RAND research papers on game theory, and his widely a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merrill Flood
Merrill Meeks Flood (1908 – 1991) was an American mathematician, notable for developing, with Melvin Dresher, the basis of the game theoretical Prisoner's dilemma model of cooperation and conflict while being at RAND in 1950 ( Albert W. Tucker gave the game its prison-sentence interpretation, and thus the name by which it is known today). Biography Flood received an MA in mathematics at the University of Nebraska, and a PhD at Princeton University in 1935 under the supervision of Joseph Wedderburn, for the dissertation ''Division by Non-singular Matric Polynomials''. In the 1930s he started working at Princeton University, and after the War he worked at the Rand Corporation, Columbia University, the University of MichiganHuixian Xu et al. (2001).Merrill M. Flood: 2nd President of TIMS (1955) and 10th President of ORSA, 1961–62". Accessed April 15, 2008 and the University of California. In the 1950s Flood was one of the founding members of TIMS and its second President i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prisoner's Dilemma
The Prisoner's Dilemma is an example of a game analyzed in game theory. It is also a thought experiment that challenges two completely rational agents to a dilemma: cooperate with their partner for mutual reward, or betray their partner ("defect") for individual reward. This dilemma was originally framed by Merrill Flood and Melvin Dresher while working at RAND in 1950. Albert W. Tucker appropriated the game and formalized it by structuring the rewards in terms of prison sentences and named it "prisoner's dilemma". William Poundstone in his 1993 book ''Prisoner's Dilemma'' writes the following version:Two members of a criminal gang are arrested and imprisoned. Each prisoner is in solitary confinement with no means of speaking to or exchanging messages with the other. The police admit they don't have enough evidence to convict the pair on the principal charge. They plan to sentence both to two years in prison on a lesser charge. Simultaneously, the police offer each prison ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tragedy Of The Commons
Tragedy (from the grc-gre, τραγῳδία, ''tragōidia'', ''tragōidia'') is a genre of drama based on human suffering and, mainly, the terrible or sorrowful events that befall a main character. Traditionally, the intention of tragedy is to invoke an accompanying catharsis, or a "pain hatawakens pleasure", for the audience. While many cultures have developed forms that provoke this paradoxical response, the term ''tragedy'' often refers to a specific tradition of drama that has played a unique and important role historically in the self-definition of Western civilization. That tradition has been multiple and discontinuous, yet the term has often been used to invoke a powerful effect of cultural identity and historical continuity—"the Greeks and the Elizabethans, in one cultural form; Hellenes and Christians, in a common activity," as Raymond Williams puts it. From its origins in the theatre of ancient Greece 2500 years ago, from which there survives only a fractio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutant
In biology, and especially in genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. It is a characteristic that would not be observed naturally in a specimen. The term mutant is also applied to a virus with an alteration in its nucleotide sequence whose genome is in the nuclear genome. The natural occurrence of genetic mutations is integral to the process of evolution. The study of mutants is an integral part of biology; by understanding the effect that a mutation in a gene has, it is possible to establish the normal function of that gene. Mutants arise by mutation Mutants arise by mutations occurring in pre-existing genomes as a result of errors of DNA replication or errors of DNA repair. Errors of replication often involve translesion synthesis by a DNA polymerase when it encounters and bypasses a damaged base in the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
