|
Acrasin
Each species of slime mold has its own specific chemical messenger, which are collectively referred to as acrasins. These chemicals signal that many individual cells aggregate to form a single large cell or plasmodium. One of the earliest acrasins to be identified was cAMP, found in the species ''Dictyostelium discoideum'' by Brian Shaffer, which exhibits a complex swirling-pulsating spiral pattern when forming a pseudoplasmodium. The term acrasin was descriptively named after Acrasia from Edmund Spenser's Faerie Queene, who seduced men against their will and then transformed them into beasts. Acrasia is itself a play on the Greek akrasia that describes loss of free will. Extraction Brian Shaffer was the first to purify acrasin, now known to be cyclic AMP, in 1954, using methanol. Glorin, the acrasin of ''P. violaceum'', can be purified by inhibiting the acrasin-degrading enzyme acrasinase with alcohol, extracting with alcohol and separating with column chromatography. Notes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slime Mold
Slime mold or slime mould is an informal name given to several kinds of unrelated eukaryotic organisms with a life cycle that includes a free-living single-celled stage and the formation of spores. Spores are often produced in macroscopic multicellular or multinucleate fruiting bodies which may be formed through aggregation or fusion. Slime molds were formerly classified as fungi but are no longer considered part of that kingdom (biology), kingdom. Although not forming a single Clade, monophyletic clade, they are grouped within the paraphyly, paraphyletic group Protists, Protista. More than 900 species of slime mold occur globally. Their common name refers to part of some of these organisms' life cycles where they can appear as gelatinous "slime". This is mostly seen with the Myxogastria, which are the only Macroscopic scale, macroscopic slime molds. Most slime molds are smaller than a few centimetres, but some species may reach sizes up to several square metres and masses up ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclic Adenosine Monophosphate
Cyclic adenosine monophosphate (cAMP, cyclic AMP, or 3',5'-cyclic adenosine monophosphate) is a second messenger important in many biological processes. cAMP is a derivative of adenosine triphosphate (ATP) and used for intracellular signal transduction in many different organisms, conveying the cAMP-dependent pathway. History Earl Sutherland of Vanderbilt University won a Nobel Prize in Physiology or Medicine in 1971 "for his discoveries concerning the mechanisms of the action of hormones", especially epinephrine, via second messengers (such as cyclic adenosine monophosphate, cyclic AMP). Synthesis Cyclic AMP is synthesized from ATP by adenylate cyclase located on the inner side of the plasma membrane and anchored at various locations in the interior of the cell. Adenylate cyclase is ''activated'' by a range of signaling molecules through the activation of adenylate cyclase stimulatory G ( Gs)-protein-coupled receptors. Adenylate cyclase is ''inhibited'' by agonists of adenyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmodium (life Cycle)
A plasmodium is a living structure of cytoplasm that contains many nuclei, rather than being divided into individual cells each with a single nucleus. Plasmodia are best known from slime molds, but are also found in parasitic Myxosporea, and some algae such as the Chlorarachniophyta. Structure A plasmodium is an amoeboid, multinucleate, and naked mass of cytoplasm that contains many diploid nuclei. The resulting structure, a coenocyte, is created by many nuclear divisions without the process of cytokinesis, which in other organisms pulls newlydivided cells apart. In some cases, the resulting structure is a syncytium, created by the fusion of cells after division. Under suitable conditions, plasmodia differentiates and forms fruiting bodies bearing spores at their tips. Taxonomic distribution The term plasmodium, introduced by Leon Cienkowski, usually refers to the feeding stage of slime molds; these are macroscopic mycetozoans. The multinucleate developmental stages of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dictyostelium Discoideum
''Dictyostelium discoideum'' is a species of soil-dwelling amoeba belonging to the phylum Amoebozoa, infraphylum Mycetozoa. Commonly referred to as slime mold, ''D. discoideum'' is a eukaryote that transitions from a collection of unicellular amoebae into a multicellular slug and then into a fruiting body within its lifetime. Its unique asexual lifecycle consists of four stages: vegetative, aggregation, migration, and culmination. The lifecycle of ''D. discoideum'' is relatively short, which allows for timely viewing of all stages. The cells involved in the lifecycle undergo movement, chemical signaling, and development, which are applicable to human cancer research. The simplicity of its lifecycle makes ''D. discoideum'' a valuable model organism to study genetic, cellular, and biochemical processes in other organisms. Natural habitat and diet In the wild, ''D. discoideum'' can be found in soil and moist leaf litter. Its primary diet consists of bacteria, such as ''Escherichia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edmund Spenser
Edmund Spenser (; 1552/1553 – 13 January 1599) was an English poet best known for '' The Faerie Queene'', an epic poem and fantastical allegory celebrating the Tudor dynasty and Elizabeth I. He is recognized as one of the premier craftsmen of nascent Modern English verse and is often considered one of the greatest poets in the English language. Life Edmund Spenser was born in East Smithfield, London, around the year 1552; however, there is still some ambiguity as to the exact date of his birth. His parenthood is obscure, but he was probably the son of John Spenser, a journeyman clothmaker. As a young boy, he was educated in London at the Merchant Taylors' School and matriculated as a sizar at Pembroke College, Cambridge. While at Cambridge he became a friend of Gabriel Harvey and later consulted him, despite their differing views on poetry. In 1578, he became for a short time secretary to John Young, Bishop of Rochester. In 1579, he published ''The Shepheardes Calender'' an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Faerie Queene
''The Faerie Queene'' is an English epic poem by Edmund Spenser. Books IIII were first published in 1590, then republished in 1596 together with books IVVI. ''The Faerie Queene'' is notable for its form: at over 36,000 lines and over 4,000 stanzas it is one of the longest poems in the English language; it is also the work in which Spenser invented the verse form known as the Spenserian stanza. On a literal level, the poem follows several knights as a means to examine different virtues, and though the text is primarily an allegorical work, it can be read on several levels of allegory, including as praise (or, later, criticism) of Queen Elizabeth I. In Spenser's "Letter of the Authors", he states that the entire epic poem is "cloudily enwrapped in Allegorical devices", and that the aim of publishing ''The Faerie Queene'' was to "fashion a gentleman or noble person in virtuous and gentle discipline". Spenser presented the first three books of ''The Faerie Queene'' to Elizabeth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Akrasia
Akrasia (; Greek , "lacking command" or "weakness", occasionally transliterated as acrasia or Anglicised as acrasy or acracy) is a lack of self-control, or acting against one's better judgment. The adjectival form is "akratic". Classical approaches The problem goes back at least as far as Plato. In Plato's ''Protagoras'' Socrates asks precisely how it is possible that, ''if'' one judges action A to be the best course of action, one would do anything other than A? In the dialogue ''Protagoras'', Socrates attests that akrasia does not exist, claiming "No one goes willingly toward the bad" (358d). If a person examines a situation and decides to act in the way he determines to be best, he will pursue this action, as the best course is also the good course, i.e. man's natural goal. An all-things-considered assessment of the situation will bring full knowledge of a decision's outcome and worth linked to well-developed principles of the good. A person, according to Socrates, never ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States National Academy Of Sciences
The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the National Academy of Medicine (NAM). As a national academy, new members of the organization are elected annually by current members, based on their distinguished and continuing achievements in original research. Election to the National Academy is one of the highest honors in the scientific field. Members of the National Academy of Sciences serve '' pro bono'' as "advisers to the nation" on science, engineering, and medicine. The group holds a congressional charter under Title 36 of the United States Code. Founded in 1863 as a result of an Act of Congress that was approved by Abraham Lincoln, the NAS is charged with "providing independent, objective advice to the nation on matters related to science and technology. ... to provide sci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smithsonian Magazine
''Smithsonian'' is the official journal published by the Smithsonian Institution in Washington, D.C. The first issue was published in 1970. History The history of ''Smithsonian'' began when Edward K. Thompson, the retired editor of ''Life'' magazine, was asked by the then-Secretary of the Smithsonian, S. Dillon Ripley, to produce a magazine "about things in which the Smithsonian nstitutionis interested, might be interested or ought to be interested." Thompson would later recall that his philosophy for the new magazine was that it "would stir curiosity in already receptive minds. It would deal with history as it is relevant to the present. It would present art, since true art is never dated, in the richest possible reproduction. It would peer into the future via coverage of social progress and of science and technology. Technical matters would be digested and made intelligible by skilled writers who would stimulate readers to reach upward while not turning them off with jargon. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Faerie Queene")
.JPG "Click for more on -> United States National Academy Of Sciences")