FACTOID # 2: Puerto Rico has roughly the same gross state product as Montana, Wyoming and North Dakota combined.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
RELATED ARTICLES
People who viewed "Senescence" also viewed:
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Senescence

In biology, senescence is the combination of processes of deterioration which follow the period of development of an organism. For the science of the care of the elderly, see gerontology; for experimental gerontology, see life extension. The word senescence is derived from the Latin word senex, meaning "old man" or "old age." Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, knowledge), also referred to as the biological sciences, is the study of living organisms utilizing the scientific method. ... Gerontology is the study of aging. ... Life extension refers to an increase in maximum or average lifespan, especially in humans, by slowing down or reversing the processes of aging. ...

Contents

Cellular senescence

Cellular senescence(upper) Primary mouse embryonic fibroblast cells (MEFs) before senescence. Spindle-shaped. (lower) MEFs became senescent after passages. Cells grow larger, flatten shape and expressed senescence-associated β-galactosidase (SABG, blue areas), a marker of cellular senescence.
Cellular senescence
(upper) Primary mouse embryonic fibroblast cells (MEFs) before senescence. Spindle-shaped. (lower) MEFs became senescent after passages. Cells grow larger, flatten shape and expressed senescence-associated β-galactosidase (SABG, blue areas), a marker of cellular senescence.

Cellular senescence is the phenomenon where normal diploid differentiated cells lose the ability to divide. This phenomenon is also known as "replicative senescence", the "Hayflick phenomenon", or the Hayflick limit in honour of Dr. Leonard Hayflick who was the first to publish it in 1965. In response to DNA damage (including shortened telomeres) cells either senesce or self-destruct (apoptosis, programmed cell death) if the damage cannot be repaired. In this 'cellular suicide', the death of one, or more, cells may benefit the organism as a whole. For example, in plants the death of the water-conducting xylem cells (tracheids and vessel elements) allows the cells to function more efficiently and so deliver water to the upper parts of a plant. Image File history File links Size of this preview: 391 × 600 pixelsFull resolution (600 × 920 pixel, file size: 130 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 391 × 600 pixelsFull resolution (600 × 920 pixel, file size: 130 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Lactase (or β-galactosidase) is the enzyme involved in the hydrolysis of lactose to galactose and glucose. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... The Hayflick limit was discovered by Leonard Hayflick in 1965. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... A telomere is a region of highly repetitive DNA at the end of a chromosome that functions as a disposable buffer. ... A section of mouse liver showing an apoptotic cell indicated by an arrow Apoptosis (pronounced apo tō sis) is a process of suicide by a cell in a multicellular organism. ... Programmed cell death (PCD) is the deliberate suicide of an unwanted cell in a multicellular organism. ... In vascular plants, xylem is one of the two types of transport tissue in plants, phloem being the other one. ... Tracheids are elongated cells in the xylem of vascular plants, serving in the transport of water. ... A vessel element is an important part of the wood (Xylem) of hardwood plants and is found in all Angiosperms. ...


Aging of the whole organism

Organismal senescence is the aging of whole organisms. The term aging has become so commonly equated with senescence that the terms will be used interchangeably in this article.


Aging is generally characterized by the declining ability to respond to stress, increasing homeostatic imbalance and increased risk of aging-associated diseases. Because of this, death is the ultimate consequence of aging. Differences in maximum life span between species correspond to different "rates of aging". For example, inherited differences in the rate of aging make a mouse elderly at 3 years and a human elderly at 90 years. These genetic differences affect a variety of physiological processes, including the efficiency of DNA repair, antioxidant enzymes, and rates of free radical production. Ageing or aging is the process of getting older. ... Homeostasis is the property of either an open system or a closed system,[1] especially a living organism, to regulate its internal environment to maintain a stable, constant condition. ... An aging-associated disease is a disease that is seen with increasing frequency with increasing senescence. ... This article or section does not adequately cite its references or sources. ... Maximum life span is a measure of the maximum number of years a member of a group has been observed to survive. ... Biological inheritance is the process by which an offspring cell or organism acquires or becomes predisposed to characteristics of its parent cell or organism. ... This article is about the animal. ... This article is about modern humans. ... DNA damage resulting in multiple broken chromosomes DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. ... Space-filling model of the antioxidant metabolite glutathione. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ...

Supercentenarian Ann Pouder (8 April 1807 – 10 July 1917) photographed on her 110th birthday. A heavily lined face is common in human senescence.
Supercentenarian Ann Pouder (8 April 180710 July 1917) photographed on her 110th birthday. A heavily lined face is common in human senescence.

Senescence of the organism gives rise to the Gompertz-Makeham law of mortality, which says that mortality rate rises rapidly with age. Originally uploaded by User:Infrogmation as Image:AnnPouderSupercentenarian. ... Originally uploaded by User:Infrogmation as Image:AnnPouderSupercentenarian. ... A supercentenarian (sometimes hyphenated as super-centenarian) is someone who has reached the age of 110 years or more, something achieved by only one in a thousand centenarians (based on European data). ... Ann Pouder (8 April 1807 – 10 July 1917) was one of the earliest known supercentenarians. ... April 8 is the 98th day of the year (99th in leap years) in the Gregorian calendar. ... Year 1807 (MDCCCVII) was a common year starting on Thursday (link will display the full calendar). ... is the 191st day of the year (192nd in leap years) in the Gregorian calendar. ... 1917 (MCMXVII) was a common year starting on Monday of the Gregorian calendar (see link for calendar) or a common year starting on Tuesday of the 13-day slower Julian calendar (see: 1917 Julian calendar). ... The Gompertz-Makeham law states that death rate is a sum of age-independent component (Makeham term) and age-dependent component (Gompertz function), which increases exponentially with age. ... Crude death rate by country Mortality rate is a measure of the number of deaths (in general, or due to a specific cause) in some population, scaled to the size of that population, per unit time. ...


Some animals, such as some reptiles and fish, age slowly. Some even exhibit "negative senescence", in which mortality falls with age, in disagreement with the Gompertz-Makeham "law".[1]


Theories of aging

The process of senescence is complex, and may derive from a variety of different mechanisms and exist for a variety of different reasons. However, senescence is not universal, and scientific evidence suggests that cellular senescence evolved in certain species as a mechanism to prevent the onset of cancer. In a few simple species, senescence is negligible and cannot be detected. All such species have no "post-mitotic" cells; they reduce the effect of damaging free radicals by cell division and dilution. Such species are not immortal, however, as they will eventually fall prey to trauma or disease. Moreover, average lifespans can vary greatly within and between species. This suggests that both genetic and environmental factors contribute to aging. For other uses, see Species (disambiguation). ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... Mitosis divides genetic information during cell division. ... The free-radical theory of aging (FRTA) is that organisms age because protein, lipid and nucleic acids (DNA, RNA) accumulate free radical damage with the passage of time. ... In medicine, a trauma patient has suffered serious and life-threatening physical injury resulting in secondary complications such as shock, respiratory failure and death. ... This article is about the medical term. ... For other uses, see Species (disambiguation). ... The nature versus nurture debates concern the relative importance of an individuals innate qualities (nature) versus personal experiences (nurture) in determining or causing individual differences in physical and behavioral traits. ...


Traditionally, theories that explain senescence have generally been divided between the programmed and stochastic theories of aging. Programmed theories imply that aging is regulated by biological clocks operating throughout the life span. This regulation would depend on changes in gene expression that affect the systems responsible for maintenance, repair and defense responses. Stochastic theories blame environmental impacts on living organisms that induce cumulative damage at various levels as the cause of aging, examples which range from damage to deoxyribonucleic acid (DNA), damage to tissues and cells by oxygen radicals (widely known as free radicals countered by the even more well known antioxidants), and cross-linking. Gene expression, or simply expression, is the process by which the inheritable information which comprises a gene, such as the DNA sequence, is made manifest as a physical and biologically functional gene product, such as protein or RNA. Several steps in the gene expression process may be modulated, including the... DNA replication Deoxyribonucleic acid (DNA) is a nucleic acid which carries genetic instructions for the biological development of all cellular forms of life and many viruses. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... The free-radical theory of aging (FRTA) is that organisms age because protein, lipid and nucleic acids (DNA, RNA) accumulate free radical damage with the passage of time. ... An antioxidant is a chemical that prevents the oxidation of other chemicals. ... Vulcanization is an example of cross-linking. ...


The above categorisation of theories of aging is obsolete and no serious biogerontologist follows that division anymore. Instead, aging is seen as a progressive failure of homeodynamics (homeostasis) involving genes for the maintenance and repair, stochastic events leading to molecular damage and molecular heterogeneity, and chance events determining the probability of death. Since complex and interacting systems of maintenance and repair comprise the homeodynamic (old term, homeostasis) space of a biological system, aging is considered to be a progressive shrinkage of homeodynamic space mainly due to increased molecular heterogeneity. [citation needed]


Evolutionary theories

Main article: Evolution of ageing

Ageing is believed to have evolved because of the increasingly smaller probability of an organism still being alive at older age, due to predation and accidents, both of which may be random and age-invariant. It is thought that strategies which result in a higher reproductive rate at a young age, but shorter overall lifespan, result in a higher lifetime reproductive success and are therefore favoured by natural selection. Essentially, ageing is therefore the result of investing resources in reproduction, rather than maintenance of the body (the "Disposable Soma" theory), in light of the fact that accidents, predation and disease will eventually kill the organism no matter how much energy is devoted to repair of the body. Various other, or more specific, theories of ageing exist, and are not necessarily mutually exclusive. Enquiry into the evolution of ageing aims to explain why almost all living things weaken and die with age. ... For other uses, see Natural selection (disambiguation). ...


The geneticist J. B. S. Haldane wondered why the dominant mutation which causes Huntington's disease remained in the population, why natural selection had not eliminated it. The onset of this neurological disease is (on average) at age 45 and is invariably fatal within 10-20 years. Haldane assumed, probably reasonably, that in human prehistory, few survived until age 45. Since few were alive at older ages and their contribution to the next generation was therefore small relative to the large cohorts of younger age groups, the force of selection against such late-acting deleterious mutations was correspondingly small. However if a mutation affected younger individuals, selection against it would be strong. Therefore, late-acting deleterious mutations could accumulate in populations over evolutionary time through genetic drift. This principle has been proven correct. And it is these later-acting deleterious mutations which are believed to cause, or perhaps more correctly allow, age-related mortality. John Burdon Sanderson Haldane (November 5, 1892 – December 1, 1964), who normally used J.B.S. as a first name, was a British geneticist and evolutionary biologist. ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ...


Peter Medawar formalised this observation in his mutation accumulation theory of ageing[2]. "The force of natural selection weakens with increasing age — even in a theoretically immortal population, provided only that it is exposed to real hazards of mortality. If a genetic disaster... happens late enough in individual life, its consequences may be completely unimportant". The 'real hazards of mortality' are typically predation, disease and accidents. So, even an immortal population, whose fertility does not decline with time, will have fewer individuals alive in older age groups. This is called 'extrinsic mortality.' Young cohorts, not depleted in numbers yet by extrinsic mortality, contribute far more to the next generation than the few remaining older cohorts, so the force of selection against late-acting deleterious mutations, which only affect these few older individuals, is very weak. The mutations may not be selected against, therefore, and may spread over evolutionary time into the population. Sir Peter Brian Medawar (February 28, 1915 – October 2, 1987) was a Brazilian-born English scientist best known for his work on how the immune system rejects or accepts organ transplants. ...


The major testable prediction made by this model is that species which have high extrinsic mortality in nature will age more quickly and have shorter intrinsic lifespans. This is because there is too little time before death occurs by extrinsic causes for the effects of deleterious mutations to be expressed and, therefore, selected against. This is borne out among mammals, the most well studied in terms of life history. There is a correlation among mammals between body size and lifespan, such that larger species live longer than smaller species in controlled/optimum conditions, but there are notable exceptions. For instance, many bats and rodents are similarly sized, yet bats live much, much longer. For instance, the little brown bat, half the size of a mouse, can live 30 years in the wild. A mouse will live 2–3 years even with optimum conditions. The explanation is that bats have fewer predators, and have lower overall metabolic activity, due to lengthier periods of dormancy, so therefore low extrinsic mortality. Thus more individuals survive to later ages so the force of selection against late-acting deleterious mutations is stronger. Fewer late-acting deleterious mutations = slower ageing = longer lifespan. Birds are also warm-blooded and similarly sized to many small mammals, yet live often 5–10 times as long. They clearly have fewer predation pressures compared with ground-dwelling mammals. And seabirds, which generally have the fewest predators of all birds, live longest. Lifespan is the maximum number of years a species can survive, defined by the oldest documented age of an individual member. ... Binomial name Myotis lucifugus (LeConte, 1831) The little brown bat (sometimes called Little Brown Myotis) (Myotis lucifugus) is one of the most common bats of North America, a species of the genus Myotis (mouse-eared bats), found throughout the world. ... This article is about the animal. ... The Sooty Tern is highly aerial and marine and will spend years flying at sea without returning to land. ...


Also, when examining the body-size vs. lifespan relationship, predator mammals tend to have longer lifespans than prey animals in a controlled environment such as a zoo or nature reserve. The explanation for the long lifespans of primates (such as humans, monkeys and apes) relative to body size is that their intelligence and often sociality helps them avoid becoming prey. Being a predator, being smart and working together all reduce extrinsic mortality.


Another evolutionary theory of ageing was proposed by George C. Williams (Williams 1957) and involves antagonistic pleiotropy. A single gene may affect multiple traits. Some traits that increase fitness early in life may also have negative effects later in life. But because many more individuals are alive at young ages than at old ages, even small positive effects early can be strongly selected for, and large negative effects later may be very weakly selected against. Williams suggested the following example: perhaps a gene codes for calcium deposition in bones which promotes juvenile survival and will therefore be favored by natural selection; however this same gene promotes calcium deposition in the arteries, causing negative effects in old age. Therefore negative effects in old age may reflect the result of natural selection for pleiotropic genes which are beneficial early in life. In this case, fitness is relatively high when Fisher's reproductive value is high and relatively low when Fisher's reproductive value is low. George Williams Professor George Christopher Williams (b. ... Pleiotropy occurs when a single gene influences multiple phenotypic traits. ... Pleiotropy occurs when a single gene influences multiple phenotypic traits. ... Fishers reproductive value was defined by R. A. Fisher (1930) as the expected reproduction of an individual from their current age onward, given that they have survived to their current age. ... Fishers reproductive value was defined by R. A. Fisher (1930) as the expected reproduction of an individual from their current age onward, given that they have survived to their current age. ...


Gene regulation

A number of genetic components of aging have been identified using model organisms, ranging from the simple budding yeast Saccharomyces cerevisiae to worms such as Caenorhabditis elegans and fruit flies (Drosophila melanogaster). Study of these organisms has revealed the presence of at least two conserved aging pathways. Typical divisions Ascomycota (sac fungi) Saccharomycotina (true yeasts) Taphrinomycotina Schizosaccharomycetes (fission yeasts) Basidiomycota (club fungi) Urediniomycetes Sporidiales Yeasts are a growth form of eukaryotic microorganisms classified in the kingdom Fungi, with approximately 1,500 species described. ... Binomial name Meyen ex E.C. Hansen Saccharomyces cerevisiae is a species of budding yeast. ... Binomial name Maupas, 1900 Caenorhabditis elegans (IPA: ) is a free-living nematode (roundworm), about 1 mm in length, which lives in temperate soil environments. ... Species Drosophila melanogaster Drosophila subobscura Drosophila is a genus of small flies whose members are often called fruit flies or more appropriately vinegar flies, wine flies, pomace flies, grape flies, and picked fruit-flies. ...


One of these pathways involves the gene Sir2, a NAD+-dependent histone deacetylase. In yeast, Sir2 is required for genomic silencing at three loci: the yeast mating loci, the telomeres and the ribosomal DNA (rDNA). In some species of yeast replicative aging may be partially caused by homologous recombination between rDNA repeats; excision of rDNA repeats results in the formation of extrachromosomal rDNA circles (ERCs). These ERCs replicate and preferentially segregate to the mother cell during cell division, and are believed to result in cellular senescence by titrating away (competing for) essential nuclear factors. ERCs have not been observed in other species of yeast (which also display replicative senescence), and ERCs are not believed to contribute to aging in higher organisms such as humans. Extrachromosomal circular DNA (eccDNA) has been found in worms, flies and humans. The role of eccDNA in aging, if any, is unknown. Sir2 (whose homology in mammals is SIRT1, SIR2L1 or Sir2α) is a member of a family of closely related enzymes, the sirtuins. ... Nicotinamide adenine dinucleotide (NAD+ or in older notation DPN+) is an important coenzyme found in cells. ... Short and long arms Chromosome. ... A telomere is a region of highly repetitive DNA at the end of a chromosome that functions as a disposable buffer. ... Ribosomal DNA (rDNA) are sequences encoding ribosomal RNA. These sequences regulate amplification and transcription initiation and contain transcribed and nontranscribed spacer segments. ... Chromosomal crossover is the process by which two chromosomes, paired up during Prophase I of meiosis, exchange some distal portion of their DNA. Crossover occurs when two chromosomes, normally two homologous instances of the same chromosome, break and then reconnect but to the different end piece. ... In medicine, titration is the process of gradually adjusting the dose of a medication until the desired effect is achieved. ... A nucleotide is a chemical compound that consists of a heterocyclic base, a sugar, and one or more phosphate groups. ...


Despite the lack of a connection between circular DNA and aging in higher organisms, extra copies of Sir2 are capable of extending the lifespan of both worms and flies. The mechanisms by which Sir2 homologues in higher organisms regulate lifespan is unclear, but the human SIRT1 protein has been demonstrated to deacetylate p53, Ku70, and the forkhead family of transcription factors. SIRT1 can also regulate acetylates such as CBP/p300, and has been shown to deacetylate specific histone residues. Ageing or aging is the process of getting older. ... TP53 bound to a short DNA fragment. ... Forkhead box proteins (FOX proteins) play important roles in regulating the expression of genes involved in cell growth, proliferation, differentiation, and longevity. ... In molecular biology, a transcription factor is a protein that binds DNA at a specific promoter or enhancer region or site, where it regulates transcription. ... It has been suggested that EP300 be merged into this article or section. ... Schematic representation of the assembly of the core histones into the nucleosome. ...


RAS1 and RAS2 also affect aging in yeast and have a human homologue. RAS2 overexpression has been shown to extend lifespan in yeast.


Other genes regulate aging in yeast by increasing the resistance to oxidative stress. Superoxide dismutase, a protein that protects against the effects of mitochondrial free radicals, can extend yeast lifespan in stationary phase when overexpressed. Oxidative stress is a medical term for damage to animal or plant cells (and thereby the organs and tissues composed of those cells) caused by reactive oxygen species, which include (but are not limited to) superoxide, singlet oxygen, peroxynitrite or hydrogen peroxide. ... Structure of the monomeric unit of human superoxide dismutase 2 The enzyme superoxide dismutase (SOD, EC 1. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ...


In higher organisms, aging is likely to be regulated in part through the insulin/IGF-1 pathway. Mutations that affect insulin-like signaling in worms, flies and mice are associated with extended lifespan. In yeast, Sir2 activity is regulated by the nicotinamidase PNC1. PNC1 is transcriptionally upregulated under stressful conditions such as caloric restriction, heat shock, and osmotic shock. By converting nicotinamide to niacin, it removes nicotinamide, which inhibits the activity of Sir2. A nicotinamidase found in humans, known as PBEF, may serve a similar function, and a secreted form of PBEF known as visfatin may help to regulate serum insulin levels. It is not known, however, whether these mechanisms also exist in humans since there are obvious differences in biology between humans and model organisms. The insulin-like growth factors (IGFs) are polypeptides with high sequence similarity to insulin. ... Upregulation is the process by which a cell increases the number of receptors to a given hormone or neurotransmitter to improve its sensitivity to this molecule. ... Caloric restriction or Calorie restriction (CR) is the practice of limiting dietary energy intake to improve health and retard aging. ... Heat shock proteins are a part of the cells internal repair mechanism. ... Osmotic shock is a condition that inhibits cellular activity. ... Nicotinamide, also known as niacinamide, is the amide of niacin (vitamin B3) which has the chemical formula C6H6N2O. Niacinamide is a derivative of vitamin B-3 can be used for the treatment of arthritis by aiding the body in its production of cartilage. ... Niacin, also known as nicotinic acid or vitamin B3, is a water-soluble vitamin whose derivatives such as NADH, NAD, NAD+, and NADP play essential roles in energy metabolism in the living cell and DNA repair. ... Nampt, PBEF, and visfatin refer to an identical protein, as judged by its amino acid sequence, with multiple biological functions. ... Insulin (from Latin insula, island, as it is produced in the Islets of Langerhans in the pancreas) is an anabolic polypeptide hormone that regulates carbohydrate metabolism. ...


Sir2 activity has been shown to increase under calorie restriction. Due to the lack of available glucose in the cells more NAD+ is available and can activate Sir2. Resveratrol, a polyphenol found in the skin of red grapes, was reported to extend the lifespan of yeast, worms, and flies. It has been shown to activate Sir2 activity and therefore mimics the effects of calorie restriction. Resveratrol is a phytoalexin produced naturally by several plants when under attack by bacteria or fungi. ... Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol group per molecule. ... This article is about the fruits of the genus Vitis. ...


Gene expression is imperfectly controlled, and it is possible that random fluctuations in the expression levels of many genes contribute to the aging process (Ryley, J. 2006). Individual cells, which are genetically identical, none-the-less can have substantially different responses to outside stimuli, and markedly different lifespans, indicating the epigenetic factors play an important role in gene expression and aging as well as genetic factors.


This is a list of confirmed longevity genes from model animals. A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. ...

Podospora Saccharomyces Caenorhabditis Drosophila Mouse
grisea LAG1 daf-2 sod1 Prop-1
LAC1 age-1/daf-23 cat1 p66shc RAS1 daf-18 mth mclk1
RAS2 akt-1/akt-2
PHB1 daf-16
PHB2 daf-12
CDC7 ctl-1
BUD1 old-1
RTG2 spe-26
RPD3 clk-1
HDA1 mev-1
SIR2
SIR4-42
UTH4
YGL023
SGS1
RAD52
FOB1

The major genetic model organisms used in aging research are the filamentous fungus (Podospora anserina), bakers' yeast (Saccharomyces cerevisiae), the soil roundworm (Caenorhabditis elegans), the fruit fly (Drosophila melanogaster), and the mouse (Mus musculus). The daf-2 gene encodes an insulin-like receptor in the worm C. elegans. ... The clk-1 (Clock abnormal protein 1) gene encodes an enzyme (demethoxyubiquinone mono-oxygenase) that is necessary for ubiquinone biosynthesis in the worm C. elegans and other eukaryotes. ... The clk-1 gene encodes an enzyme that is necessary for ubiquinone biosynthesis in the worm C. elegans and other eukaryotes. ... Sir2 (whose homology in mammals is SIRT1, SIR2L1 or Sir2α) is a member of a family of closely related enzymes, the sirtuins. ... Binomial name Meyen ex E.C. Hansen Saccharomyces cerevisiae is a species of budding yeast. ... Binomial name Maupas, 1900 Caenorhabditis elegans (IPA: ) is a free-living nematode (roundworm), about 1 mm in length, which lives in temperate soil environments. ... Binomial name Meigen, 1830[1] Drosophila melanogaster (from the Greek for black-bellied dew-lover) is a two-winged insect that belongs to the Diptera, the order of the flies. ... Binomial name Mus musculus Linnaeus, 1758 Mus musculus is the common house mouse. ...


Cellular senescence

As noted above, senescence is not universal, and senescence is not observed in single-celled organisms that reproduce through the process of cellular mitosis. Moreover, cellular senescence is not observed in many organisms, including sponges, corals, and lobsters. In those species where cellular senescence is observed, cells eventually become post-mitotic when they can no longer replicate themselves through the process of cellular mitosis -- i.e., cells experience replicative senescence. How and why some cells become post-mitotic in some species has been the subject of much research and speculation, but (as noted above) it is widely believed that cellular senescence evolved as a way to prevent the onset and spread of cancer. Somatic cells that have divided many times will have accumulated DNA mutations and would therefore be in danger of becoming cancerous if cell division continued. Mitosis divides genetic information during cell division. ... Classes Calcarea Hexactinellida Demospongiae The sponges or poriferans (from Latin porus pore and ferre to bear) are animals of the phylum Porifera. ... Extant Subclasses and Orders Alcyonaria    Alcyonacea    Helioporacea Zoantharia    Antipatharia    Corallimorpharia    Scleractinia    Zoanthidea [1][2]  See Anthozoa for details For other uses, see Coral (disambiguation). ... Subfamilies and Genera Neophoberinae Acanthacaris Thymopinae Nephropsis Nephropides Thymops Thymopsis Nephropinae Homarus Nephrops Homarinus Metanephrops Eunephrops Thymopides Clawed lobsters comprise a family (Nephropidae, sometimes also Homaridae) of large marine crustaceans. ... Overview of the major events in mitosis In biology, mitosis is the process of chromosome segregation and nuclear division that follows replication of the genetic material in eukaryotic cells. ... Mitosis divides genetic information during cell division. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... The term somatic refers to the body, as distinct from some other entity, such as the mind. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... It has been suggested that mutant be merged into this article or section. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ...


Lately the role of telomeres in cellular senescence has aroused general interest, especially with a view to the possible genetically adverse effects of cloning. The successive shortening of the chromosomal telomeres with each cell cycle is also believed to limit the number of divisions of the cell, thus contributing to aging. There have, on the other hand, also been reports that cloning could alter the shortening of telomeres. Some cells do not age and are therefore described as being "biologically immortal." It is theorized by some that when it is discovered exactly what allows these cells, whether it be the result of telomere lengthening or not, to divide without limit that it will be possible to genetically alter other cells to have the same capability. It is further theorized that it will eventually be possible to genetically engineer all cells in the human body to have this capability by employing gene therapy and thereby stop or reverse ageing, effectively making the entire organism potentially immortal. A telomere is a region of highly repetitive DNA at the end of a chromosome that functions as a disposable buffer. ... For other uses, see clone. ... Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ... The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication. ... Biological immortality can be defined as the absence of a sustained increase in rate of mortality as a function of chronological age. ... Kenyans examining insect-resistant transgenic Bt corn. ... Gene therapy is the insertion of genes into an individuals cells and tissues to treat a disease, and hereditary diseases in which a defective mutant allele is replaced with a functional one. ...


Chemical damage

Elderly Klamath woman by Edward S. Curtis, 1924
Elderly Klamath woman by Edward S. Curtis, 1924

The earliest aging theory was the Rate of Living Hypothesis posited by Raymond Pearl in 1928[3], based on the idea that fast basal metabolic rate corresponds to short maximum life span (much as a rapidly running machine will experience more damage from wear). Image File history File links Download high resolution version (775x1024, 155 KB) Old Klamath woman Edward S. Curtis, 1924 Northwestern University Library, Edward S. Curtiss The North American Indian: the Photographic Images, 2001. ... Image File history File links Download high resolution version (775x1024, 155 KB) Old Klamath woman Edward S. Curtis, 1924 Northwestern University Library, Edward S. Curtiss The North American Indian: the Photographic Images, 2001. ... Raymond Pearl (3 June 1879 - 17 November 1940) was an American biologist, who spent most of his career at Johns Hopkins University in Baltimore. ... Basal metabolic rate (BMR) is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting in humans). ... Maximum life span is a measure of the maximum number of years a member of a group has been observed to survive. ...


While there is likely some validity to this theory, in the form of various types of specific damage detailed below which, all other things being equal may reduce lifespan, in general this theory does not adequately explain the differences in lifespan either within, or between, species. Calorically-restricted animals process as much, or more, calories per gram of body mass, as their ad libitum fed counterparts, yet exhibit substantially longer lifespans. Similarly, metabolic rate is a poor predictor of lifespan for birds, bats and other species which presumably have reduced mortality from predation, and therefore have evolved long lifespans even in the presence of very high metabolic rates.


With respect to specific types of chemical damage caused by metabolism, it is suggested that damage to long-lived biopolymers, such as structural proteins or DNA, caused by ubiquitous chemical agents in the body such as oxygen and sugars, are in part responsible for aging. The damage can include breakage of biopolymer chains, cross-linking of biopolymers, or chemical attachment of unnatural substituents (haptens) to biopolymers. Biopolymers are a class of polymers produced by living organisms. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... This article is about sugar as food and as an important and widely-traded commodity. ... Vulcanization is an example of cross-linking. ... A hapten is a small molecule which can elicit an immune response only when attached to a large carrier such as a protein; the carrier may be one which also does not elicit an immune response by itself. ...


Under normal aerobic conditions, approximately 4% of the oxygen metabolized by mitochondria is converted to superoxide ion which can subsequently be converted to hydrogen peroxide, hydroxyl radical and eventually other reactive species including other peroxides and singlet oxygen, which can in turn generate free radicals capable of damaging structural proteins and DNA. Certain metal ions found in the body, such as copper and iron, may participate in the process. (In Wilson's disease, a hereditary defect which causes the body to retain copper, some of the symptoms resemble accelerated senescence.) These processes are termed oxidative damage and are linked to the benefits of nutritionally derived polyphenol antioxidants [citation needed]. Look up Aerobic in Wiktionary, the free dictionary. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Lewis electron configuration of superoxide. ... R-phrases , , , , S-phrases , , , ,, , , , Flash point Non-flammable Related Compounds Related compounds Water Ozone Hydrazine Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Hydrogen peroxide (H2O2) is a very pale blue liquid which appears colourless in... // Hydroxyl group The term hydroxyl group is used to describe the functional group -OH when it is a substituent in an organic compound. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... A peroxide is a compound containing an oxygen-oxygen single bond. ... Molecular orbital diagram for singlet oxygen. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... This article is about the electrically charged particle. ... For other uses, see Copper (disambiguation). ... For other uses, see Iron (disambiguation). ... Wilsons disease or hepatolenticular degeneration is an autosomal recessive hereditary disease, with an incidence of about 1 in 30,000 in most parts of the world and a male preponderance. ... A genetic disorder is a disease caused by abnormalities in genes or chromosomes. ... Molecular structure of flavone, a common Polyphenol antioxidant Polyphenol antioxidant is a class of multi-phenolic compounds known for their role of down-regulating free radical formation in mammals . ...


Sugars such as glucose and fructose can react with certain amino acids such as lysine and arginine and certain DNA bases such as guanine to produce sugar adducts, in a process called glycation. These adducts can further rearrange to form reactive species which can then cross-link the structural proteins or DNA to similar biopolymers or other biomolecules such as non-structural proteins. People with diabetes, who have elevated blood sugar, develop senescence-associated disorders much earlier than the general population, but can delay such disorders by rigorous control of their blood sugar levels. There is evidence that sugar damage is linked to oxidant damage in a process termed glycoxidation. This article is about sugar as food and as an important and widely-traded commodity. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Fructose (or levulose) is a simple sugar (monosaccharide) found in many foods and is one of the three most important blood sugars along with glucose and galactose. ... Phenylalanine is one of the standard amino acids. ... Lysine is one of the 20 amino acids normally found in proteins. ... Arginine (symbol Arg or R) is an α-amino acid. ... Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA; the others being adenine, cytosine, thymine, and uracil. ... Glycation is the result of a sugar-reducing molecule, such as fructose or glucose, bonding to a protein or lipid molecule without the controlling action of an enzyme. ... This article is about the disease that features high blood sugar. ... In medicine, blood sugar is a term used to refer to levels of glucose in the blood. ... It has been suggested that this article or section be merged with Glycation#Exogenous. ...


Free radicals can damage proteins, lipids or DNA. Glycation mainly damages proteins. Damaged proteins and lipids accumulate in lysosomes as lipofuscin. Chemical damage to structural proteins can lead to loss of function; for example, damage to collagen of blood vessel walls can lead to vessel-wall stiffness and thus hypertension, and vessel wall thickening and reactive tissue formation (atherosclerosis); similar processes in the kidney can lead to renal failure. Damage to enzymes reduces cellular functionality. Lipid peroxidation of the inner mitochondrial membrane reduces the electric potential and the ability to generate energy. It is probably no accident that nearly all of the so-called "accelerated aging diseases" are due to defective DNA repair enzymes. In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Figure 1: Basic lipid structure. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Glycation is the result of a sugar-reducing molecule, such as fructose or glucose, bonding to a protein or lipid molecule without the controlling action of an enzyme. ... Organelles labeled at upper left. ... Lipofuscin is the name given to brown pigment granules composed of lipid-containing residues of lysosomal digestion. ... Tropocollagen triple helix. ... f you all The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... For other forms of hypertension, see Hypertension (disambiguation). ... The kidneys are organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. ... Renal failure is the condition in which the kidneys fail to function properly. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Some common lipids. ... Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... This article does not cite any references or sources. ... The term Progeria narrowly refers to Hutchinson-Gilford Progeria syndrome, but the term is also used more generally to describe any of the so-called accelerated aging diseases. The word progeria is derived from the Greek for prematurely old. Because the accelerated aging diseases display different aspects of aging, but... DNA damage resulting in multiple broken chromosomes DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. ...


Reliability theory

Reliability theory suggests that biological systems start their adult life with a high load of initial damage. Reliability theory is a general theory about systems failure. It allows researchers to predict the age-related failure kinetics for a system of given architecture (reliability structure) and given reliability of its components. Reliability theory predicts that even those systems that are entirely composed of non-aging elements (with a constant failure rate) will nevertheless deteriorate (fail more often) with age, if these systems are redundant in irreplaceable elements. Aging, therefore, is a direct consequence of systems redundancy. Reliability Theory of Aging and Longevity is a scientific approach aimed to gain theoretical insights into mechanisms of biological aging and species survival patterns by applying a general theory of systems failure, known as reliability theory. ... Reliability theory developed apart from the mainstream of probability and statistics, and was used originally as a tool to help nineteenth century maritime insurance and life insurance companies compute profitable rates to charge their customers. ... Failure rate is the frequency with which an engineered system or component fails, expressed for example in failures per hour. ... In engineering, the duplication of critical components of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe, is called redundancy. ...


Reliability theory also predicts the late-life mortality deceleration with subsequent leveling-off, as well as the late-life mortality plateaus, as an inevitable consequence of redundancy exhaustion at extreme old ages. The theory explains why mortality rates increase exponentially with age (the Gompertz law) in many species, by taking into account the initial flaws (defects) in newly formed systems. It also explains why organisms "prefer" to die according to the Gompertz law, while technical devices usually fail according to the Weibull (power) law. Reliability theory allows to specify conditions when organisms die according to the Weibull law: organisms should be relatively free of initial flaws and defects. The theory makes it possible to find a general failure law applicable to all adult and extreme old ages, where the Gompertz and the Weibull laws are just special cases of this more general failure law. The theory explains why relative differences in mortality rates of compared populations (within a given species) vanish with age (compensation law of mortality), and mortality convergence is observed due to the exhaustion of initial differences in redundancy levels. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... In probability theory and statistics, the Weibull distribution (named after Waloddi Weibull) is a continuous probability distribution with the probability density function where and is the shape parameter and is the scale parameter of the distribution. ... In probability theory and statistics, the Weibull distribution (named after Waloddi Weibull) is a continuous probability distribution with the probability density function where and is the shape parameter and is the scale parameter of the distribution. ... Compensation law of mortality (late-life mortality convergence) states that the relative differences in death rates between different populations of the same biological species are decreasing with age, because the higher initial death rates in disadvantaged populations are compensated by lower pace of mortality increase with age. ...


Neuro-endocrine-immunological theories

Senescence may also simply be a result of wear and tear overwhelming repair mechanisms. It is also possible that senescence is a mechanism to control the development and spread of cancer; if cells have built-in limits to how many times they can replicate, they must somehow overcome this before they can spread indefinitely. Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ...


Miscellaneous

Recently, early senescence has been alleged to be a possible unintended outcome of early cloning experiments. Most notably, the issue was raised in the case of Dolly the sheep, following her death from a contagious lung disease. The claim that Dolly's early death involved premature senescence has been vigorously contested (e.g. by Kerry Lynn Macintosh in her book, Illegal Beings: Human Clones and the Law), and Dolly's creator, Dr. Ian Wilmut has expressed the view that her illness and death were probably unrelated to the fact that she was a clone. For other uses, see clone. ... Dolly (July 5, 1996 – February 14, 2003), a ewe, was the first mammal to have been successfully cloned from an adult somatic cell. ... Ian Wilmut (born July 7, 1944) is an English embryologist and is currently one of the leaders of the Queens Medical Research Institute at the University of Edinburgh. ...


A set of rare hereditary (genetic) disorders, each called progeria, has been known for some time. Sufferers exhibit symptoms resembling accelerated aging, including wrinkled skin. The cause of Hutchinson–Gilford progeria syndrome was reported in the journal Nature in May 2003. This report suggests that DNA damage, not oxidative stress, is the cause of this form of accelerated aging. This article is about the general scientific term. ... The term Progeria narrowly refers to Hutchinson-Gilford Progeria syndrome, but the term is also used more generally to describe any of the so-called accelerated aging diseases. The word progeria is derived from the Greek for prematurely old. Because the accelerated aging diseases display different aspects of aging, but... An accelerated aging disease is a genetic disorder in which various tissues, organs or systems of the human body age prematurely. ... The term Progeria narrowly refers to Hutchinson-Gilford Progeria syndrome, but the term is also used more generally to describe any of the so-called accelerated aging diseases. The word progeria is derived from the Greek for prematurely old. Because the accelerated aging diseases display different aspects of aging, but... Nature is a prominent scientific journal, first published on 4 November 1869. ... DNA damage resulting in multiple broken chromosomes DNA repair is a process constantly operating in each cell of a living being; it is essential to survival because it protects the genome from damage. ... Oxidative stress is a medical term for damage to animal or plant cells (and thereby the organs and tissues composed of those cells) caused by reactive oxygen species, which include (but are not limited to) superoxide, singlet oxygen, peroxynitrite or hydrogen peroxide. ...


See also

Look up Senescence in
Wiktionary, the free dictionary.

Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... Old age consists of ages nearing the average lifespan of human beings, and thus the end of the human life cycle. ... The effects of ageing on a human face Elderly woman Ageing or aging is the process of systems deterioration with time. ... One of the key concerns of older adults is experiencing memory loss, especially as it is one of the hallmark symptoms of Alzheimers Disease. ... The human brain goes through several large-scale changes as the individual progresses from embryo through to old age. ... It has been suggested that Longevity genes be merged into this article or section. ... The Aging Research Centre (ARC) is an independent non-profit educational research centre with facilities in Berkeley, California and in Waterloo, Ontario, Canada. ... The American Academy of Anti-Aging Medicine (A4M) is a charitable 501(c)(3) medical society dedicated to the advancement of technology to detect, prevent, and treat aging related disease and to promote research into methods to retard and optimize the human aging process. ... The American Aging Association (AGE) is a non-profit, tax-exempt biogerontology organization of scientists and laypeople dedicated to biomedical aging studies intended to slow the aging process. ... // The American Federation for Aging Research (AFAR) is a private, nonprofit, 501(c)3, organization whose mission is to support biomedical research on aging. ... Gerontology is the study of aging. ... Biological immortality can be defined as the absence of a sustained increase in rate of mortality as a function of chronological age. ... DNA damage resulting in multiple broken chromosomes DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. ... Engineered negligible senescence refers to an engineered prevention or reversal of cellular aging (referred to as senescence in biology). ... Fishers reproductive value was defined by R. A. Fisher (1930) as the expected reproduction of an individual from their current age onward, given that they have survived to their current age. ... Indefinite lifespan is a term used in the life extension movement to refer to the longevity of humans (and other lifeforms) under conditions in which aging can be effectively and completely prevented and treated. ... Life extension refers to an increase in maximum or average lifespan, especially in humans, by slowing down or reversing the processes of aging. ... Following is a list of topics related to life extension: Contents: Top - 0–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0–9 15 Global Challenges A Accelerated aging disease Cockayne... Maximum life span is a measure of the maximum number of years a member of a group has been observed to survive. ... The network theory of aging supports the idea that multiple connected processes contribute to the biology of aging. ... Plant senescence is a heavily studied subject just as it is in the other kingdoms of life. ... The term Progeria narrowly refers to Hutchinson-Gilford Progeria syndrome, but the term is also used more generally to describe any of the so-called accelerated aging diseases. The word progeria is derived from the Greek for prematurely old. Because the accelerated aging diseases display different aspects of aging, but... There are very few or no other articles that link to this one. ... Rejuvenation is the procedure of reversing the aging process, thus regaining youth. ... Reliability Theory of Aging and Longevity is a scientific approach aimed to gain theoretical insights into mechanisms of biological aging and species survival patterns by applying a general theory of systems failure, known as reliability theory. ... The Science of Aging Knowledge Environment (SAGE KE) is an online scientific resource provided by the American Association for the Advancement of Science (AAAS), which also publishes the journal SCIENCE. History and Organization The American Association for the Advancement of Science established a collaboration with Stanford University Libraries and The... Age-associated diseases are diseases that increase in frequency and intensity as the age of an organism increases. ...

References

  1. ^ New Scientist, 10 Aug. 2007, pp. 36-9.[1]
  2. ^ Medawar, Peter B. (1952). An Unsolved Problem of Biology. London: H. K. Lewis. 
  3. ^ Pearl, Raymond (1928). The Rate of Living, Being an Account of Some Experimental Studies on the Biology of Life Duration. New York: Alfred A. Knopf. 
  • MEDAWAR, P. B., 1946 Old age and natural death. Mod. 1:30-56.
  • WILLIAMS, G. C., 1957 Pleiotropy, natural selection and the evolution of senescence. Evolution 11:398-411.
  • GAVRILOV, L. A., GAVRILOVA, N. S., 2001 The reliability theory of aging and longevity. Journal of Theoretical Biology 213(4): 527-545. PMID 11742523
  • F. Yaghmaie, O. Saeed, S.A. Garan, M.A. Voelker, A.M. Gouw, W. Freitag, H. Sternberg and P.S. Timiras "Age-dependent loss of insulin-like growth factor-1 receptor immunoreactive cells in the supraoptic hypothalamus is reduced in calorically restricted mice". International Journal of Developmental Neuroscience, Vol. 24, Issue 7, 2006, pp. 431-436
  • RYLEY, J. Microfluidics device for single cell gene expression analysis in Saccharomyces cerevisiae.

External links

“MIT” redirects here. ...


  Results from FactBites:
 
Senescence Theory (8879 words)
For annual plants, yearly senescence can be explained as a way of increasing the number of progeny surviving to reproductive age and/or a way of increasing the amount of turnover and thus the rate of evolution.
Nevertheless, during senescence in soybeans, biological nutrients and minerals are redistributed to the seeds (Nooden, 1980).
Wittenbach (1983a) concluded that senescence in soybeans is a.
Senescence - Wikipedia, the free encyclopedia (3207 words)
However, senescence is not universal, and scientific evidence suggests that cellular senescence evolved in certain species as a mechanism to prevent the onset of cancer.
Senescence is studied in gerontology which is the branch of science involved with the aging process.
Recently, early senescence has been alleged to be a possible unintended outcome of early cloning experiments, Most notably, the issue was raised in the case of Dolly the sheep, following her death from a contagious lung disease.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m