Usuario:Correogsk/Taller

El flujo metabólico o simplemente flujo es la velocidad de recambio de las moléculas a través de una vía metabólica. El flujo se regula a través de las enzimas involucradas en la vía metabólica. Dentro de las células, la regulación del flujo resulta fundamental para que todas las vías metabólicas regulen la actividad de la vía en distintas condiciones.​ El flujo es, por tanto, un tema de gran interés para la modelación de las redes metabólicas, cuando se lleva a cabo un análisis del balance de flujo.

Así pues, el flujo es el movimiento de la materia a través de las redes metabólicas que se hallan conectadas por metabolitos y cofactores, y es por ello una manera de describir la actividad de la red metabólica como un todo utilizando una sola característica.

Descripción del flujo metabólico

It is easiest to describe the flux of metabolites through a pathway by considering the reaction steps individually. The flux of the metabolites through each reaction (J) is the rate of the forward reaction (Vf), less that of the reverse reaction (Vr).

J=Vf-Vr​

At equilibrium, there is no flux. Furthermore, it is observed that throughout a steady state pathway, the flux is usually determined by the rate determining step of the reaction.

Control del flujo metabólico

Control of flux through a metabolic pathway requires that

• The metabolic flux in the flux determining step varies based on the organisms metabolic needs.
• The change in flux that occurs due to the above requirement is communicated to the rest of the metabolic pathway in order to maintain a steady state.​

Redes metabólicas

Cellular metabolism is represented by a large number of metabolic reactions involving the conversion of the carbon source (usually glucose) into the building blocks needed for macromolecular biosynthesis. These reactions form metabolic networks within cells. These networks can then themselves be used to study metabolism within cells.

To allow these networks to interact, a tight connection between them is necessary. This connection is provided by usage of common cofactors such as ATP, ADP, NADH and NADPH. In addition to this, sharing of some metabolites between the different networks further tightens the connections between the different networks.

Control de las redes metabólicas

Existing metabolic networks regulate the movement of chemicals through their enzymatic steps by mostly regulating enzymes that catalyze irreversible reactions, while the movement of chemicals through reversible steps is generally unregulated directly.​ As a result, the movement of products through a metabolic network is governed by simple chemical equilibria, with specific key enzymes that are subject to regulation. This regulation may be indirect, in the case of an enzyme being regulated by some cell signalling mechanism, or it may be direct, as in the case of allosteric regulation, where metabolites from a different portion of a metabolic network bind directly to and affect the catalytic function of other enzymes in order to maintain homeostasis.

Los flujos y el genotipo

Metabolic fluxes are a function of gene expression, translation, post translational protein modifications and protein-metabolite interactions.​

Los flujos y el fenotipo

The function of the central carbon metabolism (metabolism of glucose) has been fine-tuned to exactly meet the needs of the building blocks and Gibbs free energy in conjunction with cell growth. There is therefore tight regulation of the fluxes through the central carbon metabolism.

The flux in a reaction can be defined based on one of three things:

• The activity of the enzyme catalysing the reaction
• The properties of the enzyme
• The metabolite concentration affecting enzyme activity.​

Considering the above, the metabolic fluxes can be described as the ultimate representation of the cellular phenotype when expressed under certain conditions.

La función del flujo metabólico en las células

La regulación del crecimiento de las células de los mamíferos

Research has shown that cells undergoing rapid growth have shown changes in their metabolism.​ These changes are observed with regards to glucose metabolism. The changes in metabolism occur because the rate of metabolism controls various signal transduction pathways that coordinate the activation of transcription factors as well as determining cell-cycle progress.

Growing cells require synthesis of new nucleotides, membranes and protein components.​​ These materials can be obtained from carbon metabolism (e.g. glucose metabolism) or from peripheral metabolism. The enhanced flux observed in abnormally growing cells is brought about by high glucose uptake.

El cáncer

Metabolic flux and more specifically how metabolism is affected due to changes in the various pathways has grown in importance since it was observed that tumour cells exhibit enhanced glucose metabolism compared to normal cells.​ Through studying these changes, it is possible to better understand the mechanisms of cell growth and where possible develop treatments to counter the effects of enhanced metabolism.

La medición de los flujos

There are several ways of measuring fluxes, however all of these are indirect. Due to this, these methods make one key assumption which is that all fluxes into a given intracellular metabolite pool balance all the fluxes out of the pool.​

This assumption means that for a given metabolic network the balances around each metabolite impose a number of constraints on the system.

The techniques currently used mainly revolve around the use of either Nuclear magnetic resonance (NMR) or gas chromatography-mass spectrometry (GC-MS).

In order to avoid the complexity of data analysis, a simpler method of estimating flux ratios has recently been developed which is based on cofeeding unlabelled and uniformly ¹³C labelled glucose. The metabolic intermediate patterns are then analysed using NMR spectroscopy. This method can also be used to determine the metabolic network topologies.

Véase también

• análisis del balance del flujo
• análisis del control metabólico
• ciclo celular
• metabolismo

Ligas externas

• Cell Press:Metabolic flux and the regulation of mammalian cell growth

[[:Categoría:Metabolismo]]

Correogsk/Taller
Fórmula molecular	?

2-Nonenal (sometimes misspelled as noneal) is an unsaturated aldehyde. The colorless liquid is an important aroma component of aged beer​ and buckwheat.​

Odor characteristics

The odor of this substance is perceived as orris, fat and cucumber.​ Its odor has been associated with human body odor alterations during aging (a.k.a. old person smell).​

Further reading

• Morrison, G. C.; Nazaroff, W. W. (2002). «Ozone interactions with carpet: secondary emissions of aldehydes». Environmental Science & Technology 36 (10): 2185-92. PMID 12038828. doi:10.1021/es0113089. 

[[Category:Fatty aldehydes]] [[Category:Flavors]]

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The Chrysanthemum and the Sword

Correogsk/Taller

The Chrysanthemum and the Sword: Patterns of Japanese Culture is a 1946 study of Japan by American anthropologist Ruth Benedict. It was written at the invitation of the U.S. Office of War Information, in order to understand and predict the behavior of the Japanese in World War II by reference to a series of contradictions in traditional culture. The book was influential in shaping American ideas about Japanese culture during the occupation of Japan, and popularized the distinction between guilt cultures and shame cultures.​

Although it has received harsh criticism, the book has continued to be influential. Two anthropologists wrote in 1992 that there is "a sense in which all of us have been writing footnotes to [Chrysanthemum] since it appeared in 1946".​ The Japanese, Benedict wrote, are

both aggressive and unaggressive, both militaristic and aesthetic, both insolent and polite, rigid and adaptable, submissive and resentful of being pushed around, loyal and treacherous, brave and timid, conservative and hospitable to new ways...​

The book also affected Japanese conceptions of themselves.​ The book was translated into Japanese in 1948 and became a bestseller in the People's Republic of China when relations with Japan soured.​

Research circumstances

Véase también: Empire of Japan

This book which resulted from Benedict's wartime research, like several other OWI wartime studies of Japan and Germany,​ is an instance of "culture at a distance," the study of a culture through its literature, newspaper clippings, films, and recordings, as well as extensive interviews with German-Americans or Japanese-Americans. The techniques were necessitated by anthropologists' inability to visit Nazi Germany or wartime Japan. One later ethnographer pointed out, however, that although "culture at a distance" had the "elaborate aura of a good academic fad, the method was not so different from what any good historian does: to make the most creative use possible of written documents."​ Anthropologists were attempting to understand the cultural patterns that might be driving the aggression of once-friendly nations, and they hoped to find possible weaknesses or means of persuasion that had been missed.

Americans found themselves unable to comprehend matters in Japanese culture. For instance, Americans considered it quite natural that American prisoners of war would want their families to know that they were alive and that they would keep quiet when they were asked for information about troop movements, etc. However, Japanese prisoners of war apparently gave information freely and did not try to contact their families.

Reception in the United States

Between 1946 and 1971, the book sold only 28,000 hardback copies, and a paperback edition was not issued until 1967.​ Benedict played a major role in grasping the place of the Emperor of Japan in Japanese popular culture, and formulating the recommendation to President Franklin D. Roosevelt that permitting continuation of the Emperor's reign had to be part of the eventual surrender offer.^{[cita requerida]}

Later reception and criticism

More than two million copies of the book have been sold in Japan since it first appeared in translation there.​

John W. Bennett and Michio Nagai, two scholars on Japan, pointed out in 1953 that the translated book "has appeared in Japan during a period of intense national self-examination — a period during which Japanese intellectuals and writers have been studying the sources and meaning of Japanese history and character, in one of their perennial attempts to determine the most desirable course of Japanese development."​

Japanese social critic and philosopher Tamotsu Aoki said that the translated book "helped invent a new tradition for postwar Japan." It helped to create a growing interest in "ethnic nationalism" in the country, shown in the publication of hundreds of ethnocentric nihonjinron (treatises on 'Japaneseness') published over the next four decades. Although Benedict was criticized for not discriminating among historical developments in the country in her study, "Japanese cultural critics were especially interested in her attempts to portray the whole or total structure ('zentai kōzō') of Japanese Culture," as Helen Hardacre put it.​ C. Douglas Lummis has said the entire "nihonjinron" genre stems ultimately from Benedict's book.​

The book began a discussion among Japanese scholars about "shame culture" vs. "guilt culture," which spread beyond academia, and the two terms are now established as ordinary expressions in the country.​

Soon after the translation was published, Japanese scholars, including Kazuko Tsurumi, Tetsuro Watsuji, and Kunio Yanagita criticized the book as inaccurate and having methodological errors. American scholar C. Douglas Lummis has written that criticisms of Benedict's book that are "now very well known in Japanese scholarly circles" include that it represented the ideology of a class for that of the entire culture, "a state of acute social dislocation for a normal condition, and an extraordinary moment in a nation's history as an unvarying norm of social behavior."​

Japanese ambassador to Pakistan Sadaaki Numata said the book was a "must reading for many students of Japanese studies."​

According to Margaret Mead, the author's former student and a fellow anthropologist, other Japanese who have read it found it on the whole accurate but somewhat "moralistic." Sections of the book were mentioned in Takeo Doi's book, The Anatomy of Dependence, but he is highly critical of her analysis of Japan and the West as respectively shame and guilt cultures.

In a 2002 symposium at The Library of Congress in the United States, Shinji Yamashita, of the department of anthropology at the University of Tokyo, added that there has been so much change since World War II in Japan that Benedict would not recognize the nation she described in 1946.​

Lummis wrote, "After some time I realized that I would never be able to live in a decent relationship with the people of that country unless I could drive this book, and its politely arrogant world view, out of my head."​ Lummis, who went to the Vassar College archives to review Benedict’s notes, wrote that he found some of her more important points were developed from interviews with Robert Hashima, a Japanese-American native of the United States who was taken to Japan as a child, educated there, then returned to the US before World War II began. According to Lummis, who interviewed Hashima, the circumstances helped introduce a certain bias into Benedict's research: "For him, coming to Japan for the first time as a teenager smack in the middle of the militaristic period and having no memory of the country before then, what he was taught in school was not 'an ideology', it was Japan itself." Lummis thinks Benedict relied too much on Hashima and says that he was deeply alienated by his experiences in Japan and that "it seems that he became a kind of touchstone, the authority against which she would test information from other sources."​

Reception of the book in Taiwan and China

The first Chinese translation was made by Taiwanese anthropologist Huang Dao-Ling, and published in Taiwan in April 1974 by Taiwan Kui-Kuang Press. The book became a bestseller in China in 2005, when relations with the Japanese government were strained. In that year alone, 70,000 copies of the book were sold in China.​

See also

• Bushidō
• Honne and tatemae

Further reading

• Kent, Pauline, "Misconceived Configurations of Ruth Benedict," Japan Review 7 (1996): 33-60.
• Kent, Pauline, "Japanese Perceptions of the Chrysanthemum and the Sword," Dialectical anthropology 24.2 (1999): 181.
• Sonya Ryang, "Chrysanthemum’s Strange Life: Ruth Benedict in Postwar Japan," Asian Anthropology 1: 87-116.
• Christopher Shannon, "A World Made Safe for Differences: Ruth Benedict's The Chrysanthemum and the Sword," American Quarterly 47 (1995): 659-680.

External links

• "Ruth Benedict, The Chrysanthemum and the Sword," (Allison Alexy Yale University site)

[[Category:Anthropology books]] [[Category:Books about Japan]] [[Category:1946 books]] [[Category:Houghton Mifflin books]] [[Category:Works about Japan]] Anexo:Términos de la francmasonería

• aumento de salario = pase del grado de aprendiz (primero) al grado de compañerx (segundo)
• logia azul = logia que incluye el trabajo de los tres primeros grados: aprendiz, compañerx y maestrx