Mesenchymal stem cellsCells from the immature embryonic connective tissue. A number of cell types come from mesenchymal stem cells, including chondrocytes, which produce…
Mesenchymal stem cells (MSCs)Cells from the immature embryonic connective tissue. A number of cell types come from mesenchymal stem cells, including chondrocytes, which produce…
MeshIn wire screen, the number of openings per lineal inch.
Mesic habitatA habitat type characterized by the presence of a moderate amount of moisture or water. Compare: hydric; opposite: xeric.
MESOMesocyclone- A storm-scale region of rotation, typically around 2-6 miles in diameter and often found in the right rear flank of a supercell (or often on…
MesoclimateThe climate of a small area of the earth's surface which may differ from the general climate of the district.
Mesocyclone(abbrev. MESO)- A storm-scale region of rotation, typically around 2-6 miles in diameter and often found in the right rear flank of a supercell (or often…
MesodermThe middle germ layer that forms in the early animal embryo and gives rise to parts such as bone and connective tissue.
MesohighA relatively small area of high atmospheric pressure that forms beneath a thunderstorm. It is usually associated with an MCS or its remnants.
Mesolow(or Sub-synoptic Low) - A mesoscale low-pressure center. Severe weather potential often increases in the area near and just ahead of a mesolow.
MesonA kind of matter made from an even number of quark-antiquark constituents. The basic structure of most mesons is one quark and one antiquark.
MesonetA regional network of observing stations (usually surface stations) designed to diagnose mesoscale weather features and their associated processes.
MesopauseThe top of the mesosphere, corresponding to the level of minimum temperature in the atmosphere found at 70 to 80 km.
mesophileA micro-organism able to grow in the temperature range 20-50 °C; optimal growth often occurs at about 37 °C. See: psychrophile, thermophile.
MesophilicAn optimum temperature for bacterial growth in an enclosed digester (25° to 40°C).
mesophyllLeaf parenchyma tissue found between epidermal layers.
MesoscaleSize scale referring to weather systems smaller than synoptic-scale systems but larger than storm-scale systems.
Mesoscale Convective Complex(abbrev. MCC)- MCC - Mesoscale Convective Complex. A large Mesoscale Convective System (MCS), generally round or oval-shaped, which normally reaches peak…
Mesoscale Convective System(MCS): A complex of thunderstorms which becomes organized on a scale larger than the individual thunderstorms, and normally persists for several hours or…
Mesoscale DiscussionWhen conditions actually begin to shape up for severe weather, SPC (Storm Prediction Center) often issues a Mesoscale Discussion (MCD) statement anywhere…
Mesoscale High WindsThese high winds usually follow the passage of organized convective systems and are associated with wake depressions or strong mesohighs.
MesosphereThe atmospheric shell between about 20 km and about 70 to 80 km, extending from the top of the stratosphere (the stratopause) to the upper temperature…
MesotrophicA lake classification describing middle-aged bodies of water between oligotrophic (young) and eutrophic (old) classifications.
MesozoicAn era of geologic time between the Paleozoic and the Cenozoic, spanning the time between 251 and 65 million years ago.
Messenger RNA (mRNA)The class of RNA molecules that copies the genetic information from DNA, in the nucleus, and carries it to ribosomes, in the cytoplasm, where it is…
METAn approximate unit of heat produced by a resting person, equal to about 18.5 Btu per square foot per hour.
metabolic cellA cell that is not dividing. See: metabolism
metabolism(meh-TA-boh-lih-zum) The total of all chemical changes that take place in a cell or an organism.
metabolite(meh-TA-boh-lite) A substance made or used when the body breaks down food, drugs or chemicals, or its own tissue (for example, fat or muscle tissue).
metabolomicsThe large-scale study of the full complement of secondary metabolites produced by a given species in all its tissues and growth stages.
metacentric chromosomeA chromosome in which the centromere is located in the middle and, consequently, the chromosome arms are of about equal length.
Metachromatic leukodystrophyA heritable metabolic disorder, usually of infancy, characterized by myelin loss and other abnormalities of the white matter of the nervous system…
metadataMetadata is information about a particular data set which may describe, for example, how, when, and by whom it was received, created, accessed, and/or…
metadata system (MDS)The components of the ARM data system that collect and report data stream metadata. Formerly known as the Site Ops Log.
metal affinity chromatographyA chromatographic technique, in which a compound interacting with a specific metal ion can be captured by immobilizing the relevant ion on the column's…
Metal Halide LampA high-intensity discharge lamp type that uses mercury and several halide additives as light-producing elements.
MetalimnionMiddle layer of a thermally stratified lake or reservoir with a rapid temperature decrease with depth. See stratification and thermocline.
metalloenzymeAn enzyme which requires the presence of a metal in order to be catalytically active.
MetallothioneinA protective protein that binds heavy metals, such as cadmium and lead.
MetamorphicRock compressed or changed by pressure, heat, or water. A rock formed from a preexisting rock that is altered ("baked") by high temperatures and…
Metamorphic rockA sedimentary or igneous rock that has been changed by pressure, heat, or chemical action.
MetaphaseStage of mitosis or meiosis (following prophase and preceding anaphase ) during which the chromosome s, or at least the kinetochores, lie in the central…
METARAn international code (Aviation Routine Weather Report) used for reporting, recording and transmitting weather observations.
metastasis(meh-TAS-tuh-sis) The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a "metastatic tumor" or a…
MetateA portable stone slab upon which seeds and other grains are milled with a mano using a push-pull, back-and-forth motion. See also Mano
MeteogramA graphical depiction of trends in meteorological variables such as temperature, dew point, wind speed and direction, pressure, etc.
Meteorological elementMeteorological element Any one of the properties or conditions of the atmosphere which together specify the weather at a given place for any particular…
MeteorologistA person who studies meteorology. There are many different paths within the field of meteorology.
MeteorologyThe science dealing with the atmosphere and its phenomena. A distinction can be drawn between meteorology and climatology, the latter being primarily…
MethaneA colorless, odorless, tasteless gas composed of one molecule of Carbon and four of hydrogen, which is highly flammable.
Methane (CH4)A hydrocarbon that is a greenhouse gas with a global warming potential most recently estimated at 23 times that of carbon dioxide (CO2).
Methane (CH<sub>4</sub>)A hydrocarbon that is a greenhouse gas with a global warming potential most recently estimated at 21.
MethanolMethyl alcohol having the chemical formula CH30H. Methanol is usually produced by chemical conversion at high temperatures and pressures. Wood alcohol.
Methanol (CH<sub>3</sub>3OH)A colorless poisonous liquid with essentially no odor and little taste. It is the simplest alcohol with a boiling point of 64.7 degrees Celsius.
methanol (wood alcohol)(CH3OH) An alcohol formed by catalytically combining carbon monoxide with hydrogen in a 1:2 ratio under high temperature and pressure.
MethanotrophicHaving the biological capacity to oxidize methane to CO2 and water by metabolism under aerobic conditions. See aerobic.
Methyl bromide (CH<sub>3</sub>Br)An effective pesticide; used to fumigate soil and many agricultural products. Because it contains bromine, it depletes stratospheric ozone when released…
Methyl tertiary butyl ether (MTBE)An ether manufactured by reacting methanol and isobutylene. MTBE has high octane and low volatility. Used as a fuel oxygenate.
methylationThe addition of a methyl group (-CH3) to a molecule, most commonly in the context of DNA where cytosine and, less often, adenine residues can be modified…
Metric Ton(or tonne) 1000 kilograms. 1 metric ton = 2,204.62 lb = 1.023 short tons.
Metric Ton (Tonne)A unit of mass equal to 1,000 kilograms or 2,204.6 pounds.
micro-arrayA large set of cloned DNA molecules immobilized as a compact and orderly pattern of sub-microlitre spots onto a solid matrix (typically a glass slide).
micro-carrierSmall particles used as a support material for (particularly mammalian) cells, which are too fragile to be pumped and stirred as bacterial cells are in a…
micro-elementA nutritional element required in very small quantities.
micro-encapsulationA process of enclosing a substance in very small sealed capsules from which material is released by heat, solution or other means.
micro-environmentA small-scale environment in which the conditions (temperature, humidity, pH etc.
micro-injectionThe introduction of small amounts of (usually) liquid material (DNA, RNA, enzyme s, cytotoxic agents) into a defined tissue or single cell with a fine…
micro-isolating systemMechanical separation of single cells or protoplasts thus allowing them to proliferate individually.
micro-organismOrganism visible only under magnification.
microalgal cultureCulture in bioreactors of microalgae (including seaweeds).
MicroarraySets of miniaturized chemical reaction areas that may also be used to test DNA fragments, antibodies, or proteins.
microarray technologyA new way of studying how large numbers of genes interact with each other and how a cell's regulatory networks control vast batteries of genes…
MicrobarographA instrument designed to continuously record a barometer's reading of very small changes in atmospheric pressure.