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Dauer Larvae
Dauer (German "", English "the endurance", "persistence"; "unlimited time" ) describes an alternative developmental stage of nematode worms, particularly rhabditids including ''Caenorhabditis elegans'', whereby the larva goes into a type of stasis and can survive harsh conditions. Since the entrance of the dauer stage is dependent on environmental cues, it represents a classic and well studied example of polyphenism. The dauer state is given other names in the various types of nematodes such as ‘diapause’ or ‘hypobiosis’, but since the ''C. elegans'' nematode has become the most studied nematode, the term ‘dauer stage’ or 'dauer larvae' is becoming universally recognised when referring to this state in other free-living nematodes. The dauer stage is also considered to be equivalent to the infective stage of parasitic nematode larvae. As Émile Maupas first proposed in 1899 and 1900, all nematodes have five stages separated by four moults. Under environmental condition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Language
German (, ) is a West Germanic language in the Indo-European language family, mainly spoken in Western Europe, Western and Central Europe. It is the majority and Official language, official (or co-official) language in Germany, Austria, Switzerland, and Liechtenstein. It is also an official language of Luxembourg, German-speaking Community of Belgium, Belgium and the Italian autonomous province of South Tyrol, as well as a recognized national language in Namibia. There are also notable German-speaking communities in other parts of Europe, including: Poland (Upper Silesia), the Czech Republic (North Bohemia), Denmark (South Jutland County, North Schleswig), Slovakia (Krahule), Germans of Romania, Romania, Hungary (Sopron), and France (European Collectivity of Alsace, Alsace). Overseas, sizeable communities of German-speakers are found in the Americas. German is one of the global language system, major languages of the world, with nearly 80 million native speakers and over 130 mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forkhead
FOX (forkhead box) proteins are a family of transcription factors that play important roles in regulating the expression of genes involved in cell growth, proliferation, differentiation, and longevity. Many FOX proteins are important to embryonic development. FOX proteins also have pioneering transcription activity by being able to bind condensed chromatin during cell differentiation processes. There are 50 different FOX genes encoding FOX proteins in humans that are further divided into 19 subdivisions based on conserved sequence similarity. The defining feature of FOX proteins is the forkhead box, a sequence of 80 to 100 amino acids forming a motif that binds to DNA. This forkhead motif is also known as the winged helix, due to the butterfly-like appearance of the loops in the protein structure of the domain. FOX proteins are a subgroup of the helix-turn-helix class of proteins. Biological roles FOX genes are key elements in many developmental and biological processes, inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuticle
A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structure, function, and chemical composition. Human anatomy In human anatomy, "cuticle" can refer to several structures, but it is used in general parlance, and even by medical professionals, to refer to the thickened layer of skin surrounding fingernails and toenails (the eponychium), and to refer to the superficial layer of overlapping cells covering the hair shaft ( cuticula pili), consisting of dead cells, that locks the hair into its follicle. It can also be used as a synonym for the epidermis, the outer layer of skin. Cuticle of invertebrates In zoology, the invertebrate cuticle or cuticula is a multi-layered structure outside the epidermis of many invertebrates, notably arthropods and roundworms, in which it forms an exoskeleton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alae (anatomy)
The alae is a protruding ridge that forms longitudinally on many nematodes. In the ''Caenorhabditis elegans'' nematode they are present in the L1, dauer (an alternative long living larvae stage where the nematode is dormant) and adult stages. The alae are most pronounced during the dauer larval stage and not present in the L2, and L3 ''C. elegans'' stages. The term ‘alae’ is the plural of ala (wing), describing either one of the pair of ridges that forms on a nematode or an individual crease found on an individual ridge. The term ‘ala’ is rarely used in describing the alae and scientific journals use the term ‘alae’ both singularly and in the plural. Structure The alae is formed by the hypodermal seam cells where a fibrous ribbon of a zona pellucida (ZP) domain protein is produced. In ''C. elegans'' many of these proteins are termed CUT-1. The CUT refers to cuticulins which are the various proteins that are not solubilised by both reducing agents and detergents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proceedings Of The National Academy Of Sciences Of The United States Of America
''Proceedings of the National Academy of Sciences of the United States of America'' (often abbreviated ''PNAS'' or ''PNAS USA'') is a peer-reviewed multidisciplinary scientific journal. It is the official journal of the National Academy of Sciences, published since 1915, and publishes original research, scientific reviews, commentaries, and letters. According to ''Journal Citation Reports'', the journal has a 2022 impact factor of 9.4. ''PNAS'' is the second most cited scientific journal, with more than 1.9 million cumulative citations from 2008 to 2018. In the past, ''PNAS'' has been described variously as "prestigious", "sedate", "renowned" and "high impact". ''PNAS'' is a delayed open-access journal, with an embargo period of six months that can be bypassed for an author fee ( hybrid open access). Since September 2017, open access articles are published under a Creative Commons license. Since January 2019, ''PNAS'' has been online-only, although print issues are available ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life Extension
Life extension is the concept of extending the human lifespan, either modestly through improvements in medicine or dramatically by increasing the maximum lifespan beyond its generally-settled biological limit of around 125 years. Several researchers in the area, along with "life extensionists", " immortalists", or " longevists" (those who wish to achieve longer lives themselves), postulate that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement (such as with artificial organs or xenotransplantations) will eventually enable humans to have indefinite lifespans through complete rejuvenation to a healthy youthful condition (agerasia). The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists. The sale of purported anti-aging products such as supplements and hormone replacement is a lucrative global industry. For example, the industry that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germline
In biology and genetics, the germline is the population of a multicellular organism's cells that develop into germ cells. In other words, they are the cells that form gametes ( eggs and sperm), which can come together to form a zygote. They differentiate in the gonads from primordial germ cells into gametogonia, which develop into gametocytes, which develop into the final gametes. This process is known as gametogenesis. Germ cells pass on genetic material through the process of sexual reproduction. This includes fertilization, recombination and meiosis. These processes help to increase genetic diversity in offspring. Certain organisms reproduce asexually via processes such as apomixis, parthenogenesis, autogamy, and cloning. Apomixis and Parthenogenesis both refer to the development of an embryo without fertilization. The former typically occurs in plants seeds, while the latter tends to be seen in nematodes, as well as certain species of reptiles, birds, and fish. Autogamy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cynthia Kenyon
Cynthia Jane Kenyon (born February 21, 1954) is an American molecular biologist and biogerontologist known for her genetic dissection of aging in a widely used model organism, the roundworm ''Caenorhabditis elegans''. She is the vice president of aging research at Calico Research Labs, and emeritus professor of biochemistry and biophysics at the University of California, San Francisco (UCSF). Career Cynthia Kenyon graduated valedictorian in chemistry and biochemistry from the University of Georgia in 1976. She received her Ph.D. in 1981 from MIT where, in Graham Walker's laboratory, she looked for genes on the basis of their activity profiles, discovering that DNA-damaging agents activate a battery of DNA repair genes in E. coli. She then did postdoctoral studies with Nobel laureate Sydney Brenner at the MRC Laboratory of Molecular Biology in Cambridge, England, studying the development of ''C. elegans.'' Since 1986 she has been at the UCSF, where she was the Herbert Boyer Disti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DAF-9
The Daf-9 gene encodes a cytochrome p450 enzyme catalysis the generation of dafachronic acid (a steroid hormone) in the worm ''Caenorhabditis elegans'', with the CYP Symbol CYP22A1 (Cytochrome P450, family 22, member A1). After generation, dafachronic acid will binding it's nuclear receptor Daf-12 and has been implicated by Cynthia Kenyon and colleagues related to the formation of Dauer larva Dauer ( German "", English "the endurance", "persistence"; "unlimited time" ) describes an alternative developmental stage of nematode worms, particularly rhabditids including ''Caenorhabditis elegans'', whereby the larva goes into a type of stas .... References {{Dauer larva Caenorhabditis elegans genes 22 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytochrome P450
Cytochromes P450 (P450s or CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that mostly, but not exclusively, function as monooxygenases. However, they are not omnipresent; for example, they have not been found in ''Escherichia coli''. In mammals, these enzymes oxidize steroids, fatty acids, xenobiotics, and participate in many biosyntheses. By hydroxylation, CYP450 enzymes convert xenobiotics into hydrophilic derivatives, which are more readily excreted. P450s are, in general, the terminal oxidase enzymes in electron transfer chains, broadly categorized as P450-containing systems. The term "P450" is derived from the spectrophotometry, spectrophotometric peak at the wavelength of the absorption spectroscopy, absorption maximum of the enzyme (450 nanometre, nm) when it is in the redox, reduced state and complexed with carbon monoxide. Most P450s require a protein partner to deliver one or more electrons to reduc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dafachronic Acid
Dafachronic acids are steroid hormones activate the nuclear receptor Daf-12/NR1J1 in ''Caenorhabditis elegans'' and related organisms, include Δ4-dafachronic acid and Δ7-dafachronic acid. Both are generated by Daf-9 The Daf-9 gene encodes a cytochrome p450 enzyme catalysis the generation of dafachronic acid (a steroid hormone) in the worm ''Caenorhabditis elegans'', with the CYP Symbol CYP22A1 (Cytochrome P450, family 22, member A1). After generation, dafachr .../CYP22A1 from respective precursors. References {{Reflist Steroid hormones ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hormone
A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physiology and behavior. Hormones are required for the normal development of animals, plants and fungi. Due to the broad definition of a hormone (as a signaling molecule that exerts its effects far from its site of production), numerous kinds of molecules can be classified as hormones. Among the substances that can be considered hormones, are eicosanoids (e.g. prostaglandins and thromboxanes), steroids (e.g. Estrogen, oestrogen and brassinosteroid), amino acid derivatives (e.g. epinephrine and auxin), protein or peptides (e.g. insulin and CLE peptides), and gases (e.g. ethylene and nitric oxide). Hormones are used to communicate between organ (anatomy), organs and Tissue (biology), tissues. In vertebrates, hormones are responsible for regulating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
