(CH3) are added to a molecule of salicylic acid. During 1997, Ilya Raskin showed that methyl salicylate emitted by one tobacco plant (e.g., under ‘attack’ by insects, fungi, bacteria, or viruses) could cause other nearby tobacco plants to “turn on” their selfdefense mechanism (systemic acquired resistance). See also SALICYLIC ACID (SA), BAC-

TERIA, SYSTEMIC ACQUIRED RESISTANCE (SAR),

FUNGUS.

Methylated Refers to a DNA molecule that is saturated with methyl groups (i.e., methyl submolecule groups, -CH3, have attached themselves to the DNA molecule at all possible locations). Generally, when a DNA molecule is methylated, the genes comprising that DNA molecule are “turned off” (inactivated). See also DNA METHYLATION,

DEOXYRIBONUCLEIC ACID (DNA), TRANSCRIPTION,

MESSENGER RNA (mRNA), GENE, GENETIC CODE,

p53 GENE, TUMOR-SUPPRESSOR GENES.

MHC See MAJOR HISTOCOMPATIBILITY COMPLEX

(MHC).

Micelle The spherical structure formed by the

Massociation of a number of amphiphilic molecules dissolved in water. Structurally, the outer surface of the micelle (sphere) is covered with the polar domains (head groups) which are directed toward (stick into) the water while the interior of the micelle contains the nonpolar domains (tails), which self-associate to create an “oil droplet” microenvironment. Micelles may be used to solubilize nonwater (oil) soluble or sparingly water soluble molecules in water. They may be formed by ionic or nonionic surfactants.

See also AMPHIPHILIC MOLECULES, SUPERCRITI-

CAL CARBON DIOXIDE, CRITICAL MICELLE CON- C E N T R A T I O N , R E V E R S E M I C E L L E ( R M ) ,

SURFACTANT, FATS, SELF-ASSEMBLY.

Micro Sensors See BIOCHIP, MICROARRAY (TEST-

ING), BIOSENSOR.

Micro Total Analysis Systems A b b r ev i a t e d

mTAS. See also GENE EXPRESSION ANALYSIS,

BIOCHIP, GENOSENSORS, NANOTECHNOLOGY, BIO-

SENSORS (ELECTRONIC), BIOSENSORS (CHEMICAL).

Micro-electromechanical Systems See MEMS

(NANOTECHNOLOGY).

Microaerophile An organism that grows best in the presence of a small amount of oxygen.

See also ORGANISM, MICROORGANISM, FACULTA-

TIVE ANAEROBE.

Microarray (testing) Refers to a piece of glass, plastic, or silicon onto which has been placed a large number of biosensors. These microarrays (sometimes called “biochips” or “DNA chips”) can then be utilized to test a single biological sample for a variety of attributes or effects. For example, by placing protein-detection molecules (e.g., ligands, which change color or cause electronic signal upon contact with specific protein molecules) onto a microarray, a scientist can perform gene expression analysis (i.e., evaluation of the protein expression and expression levels of genes in a biological sample).

Another application would be to place (cellular) receptors, nucleic acids/probes, adhesion molecules, messenger RNA (specific to which gene is “turned on” in a given disease state), cDNA (complementary to mRNA coded for by each gene that is “turned on”), or cells (indicating which cellular pathway is “turned on,” etc.) onto a microarray, to utilize that microarray to screen for proteins or other chemical compounds that act against a disease (i.e., therapeutic target); as indicated by (the relevant component from biological sample) adhesion or hybridization to the specific spot on the microarray where a specific (target molecule) was earlier placed/attached. “Quantum dots” could potentially be used on microarrays in place of cellular receptors in the future. See also DNA CHIP, BIOCHIP, GENE,

CODING SEQUENCE, GENE EXPRESSION, GENE

EXPRESSION ANALYSIS, GENOSENSORS, NANO-

TECHNOLOGY, GENOMICS, FUNCTIONAL GENOM-

ICS, BIOSENSORS (ELECTRONIC), BIOSENSORS

(CHEMICAL), HIGH-THROUGHPUT SCREENING

(HTS), TARGET-LIGAND INTERACTION SCREENING,

RECEPTORS, BIORECEPTORS, COMBINATORIAL

CHEMISTRY, TARGET (OF A THERAPEUTIC AGENT),

TARGET (OF A HERBICIDE OR INSECTICIDE), ADHE-

SION MOLECULE, MICROFLUIDICS, BIOELECTRON-

ICS, ASSAY, BIOASSAY, MESSENGER RNA (mRNA),

CHARACTERIZATION ASSAY, PROBE, HYBRIDIZA-

TION (MOLECULAR BIOLOGY), BIOINFORMATICS,

HYBRIDIZATION SURFACES, PATHWAY, DEOXY-

RIBONUCLEIC ACID (DNA), QUANTUM DOT, PRO-

TEOME CHIP.

© 2002 by CRC Press LLC

M I C R O -

MICRON.

Microbe A microscopic organism; applied particularly to bacteria. The word “microbe” was coined by Monsieur Sedillot, a colleague of Louis Pasteur. See also BACTERIA,

GENETICALLY ENGINEERED MICROBIAL PESTICIDES

(GEMP), PHYTOALEXINS.

Microbial Physiology The cell structure, growth factors, metabolism, and genetics of microorganisms. See also MICROORGANISM,

CELL, METABOLISM, GENETICS, MICROBIOLOGY.

Microbial Source Tracking (MST) The process of systematically determining the original source (in a specific environment) of a microbe (e.g., the one that has caused a given disease outbreak). Some of the technologies utilized in MST include genetic fingerprinting, polymerase chain reaction (PCR), serotyping, etc. See also MICROBE, PATHOGEN,

POLYMERASE CHAIN REACTION (PCR) TECHNIQUE,

SEROTYPES.

Microbicide Any chemical that will kill microorganisms. Used synonymously with the terms biocide and bactericide. See also

MICROORGANISM, BIOCIDE.

Microbiology The science dealing with the structure, classification, physiology, and distribution of microorganisms, and with their technical and medical significance. The term microorganism is applied to the simple unicellular and structurally similar representatives of the plant and animal kingdoms. With few exceptions, the unicellular organisms are invisible to the naked eye and generally have dimensions of between a fraction of a micron and 200 microns. See also

Microchannel Fluidic Devices S e e

FLUIDICS.

Microfilaments Very thin filaments found in the cytoplasm of cells. See also CELL, CYTO-

PLASM, MICROTUBULES.

Microfluidic Chips See BIOCHIP, MICROFLUID-

ICS, NANOTECHNOLOGY.

Microfluidics Refers to the science and properties of fluids when flowing through very small passages (e.g., micron or nanometer dimensions) and/or in very small amounts (e.g., femtogram quantities). For example, to move fluid (samples), microfluidic chips utilize either capillary action or else they “pump” fluid (through microchannels in those chips) electrokinetically (i.e., cause the

flow to occur by applying a controlled electrical field, so liquid is attracted to electrical charge, and thereby flows). Such “pumping” could also be utilized to deliver certain medicines in very small, precisely timed and metered doses (e.g., if the microfluidic chip is embedded into diseased tissue within the body). Another potential application of such “pumping” could be to perform multiple chemical analyses (e.g., of body fluids within diseased tissues), in which case such microfluidic chips are known as “lab-on-a- chip”/laboratory-on-a-chip analytical

devices. See also BIOCHIP, NANOTECHNOLOGY,

MICROARRAY (TESTING), NANOSCIENCE, MICRON.

Microgram 10–6 gram, or 2.527 × 10–8 ounce

(avoirdupoir).

Micromachining Refers to the technology and tools or methods utilized to create the very small parts, grooves (in chips/arrays), etc. in NEMS (nanoelectromechanical systems), biochips, microarrays, and other devices of the field of nanotechnology. See also NANO-

TECHNOLOGY, NANOELECTROMECHANICAL SYS-

TEMS (NEMS), BIOCHIP, MICROARRAY (TESTING). M

Micron Also called micrometer. A unit of length convenient for describing cellular dimensions; the Greek letter µ is used as its symbol. A micron is equal to 10–3 mm (mil- l i m e t e r ) o r 1 0 4 Å ( A n g s t r o m s ) o r 0.00003937 inch. See also MICROBIOLOGY,

CELL, MICROFLUIDICS.

Microorganism Any organism of microscopic size (i.e., requires a microscope to be seen by man). First viewed by Antoni van Leeuenhoek in 1676. Some microorganisms are pathogenic (disease-causing) and some

are not. See also MICROBIOLOGY, BACTERIA,

PATHOGENIC, NEMATODES, CAPSULE.

Microparticles Refers to the metal particles (R gene gun). See also BIOLISTIC R GENE GUN,

VECTORS, MICRON, GENE.

Microphage See POLYMORPHONUCLEAR LEUKO-

CYTES.

Micropropagation A technique used by man to replicate (mass-produce) a given (e.g., valuable) plant by making genetic clones (“copies”) of that original plant. See also

CLONE (AN ORGANISM), GENETICS.

Microsatellite DNA Pieces of the same small segment (i.e., a DNA sequence) which are

© 2002 by CRC Press LLC

(N A N O -

Minimum Tillage

TIME, BIOLOGICAL ACTIVITY.

FACTOR,

BIOMIMETIC MATERIALS,

of its extraneous (unneeded) portions (peptides) have been removed. In 1995, Brian Cunningham and James A. Wells reduced the 28-residue (peptide) protein (hormone) Atrial Natriuretic Factor to 15-residues (peptides) size without reducing its potency (biological activity). Minimized proteins that retain their potency hold the potential for medicines possessing a greater serum lifetime (when injected into a patient’s body), and as “models” for the creation of organic- chemical-synthesized mimetic drugs possessing the same therapeutic effect as the native protein did. See also PROTEIN, PEPTIDE,

ACTIVE SITE, ENZYME, CATALYTIC SITE, DOMAIN

(OF A PROTEIN), HORMONE, ATRIAL NATRIURETIC SERUM LIFE-

“repeated” (appear repeatedly in sequence within the DNA molecule) adjacent to a specific gene within the DNA molecule. Thus, these “microsatellites” are linked to that spe-

cific gene. See also DEOXYRIBONUCLEIC ACID

(DNA), LINKAGE, SEQUENCE (OF A DNA MOLE-

CULE), SATELLITE DNA, GENE, LINKAGE GROUP.

Microsystems Technology See M S T

TECHNOLOGY).

Microtubules Tiny hollow filaments (i.e., string-like structures) within eucaryotic cells, that are made of tubulin (α and β proteins). Some microtubules give the cell its shape (e.g., act as structural components of cell). Other microtubules are the “tow ropes” utilized to move proteins within cells via vesicular transport (vesicles are small hollow structures that contain those protein molecules).

Microtubules also “tow” apart the paired chromosomes within cells undergoing meiosis. Within neurons (cells of the mammal nervous system), microtubules transport messenger RNAs (mRNA) from the nucleus

M(where they are manufactured) to the ribosomes in the dendrites (long extensions of the neuron cell), where the mRNAs are “translated” into protein molecules (i.e, pro-

teins are manufactured by ribosome). See

also CELL, MEIOSIS, MESSENGER RNA (mRNA),

DENDRITES, PROTEIN, VESICULAR TRANSPORT (OF

A PROTEIN), EUCARYOTE.

Mid-Oleic Sunflowers Refers to sunflower (crop) plant varieties which have been bred so their seeds contain 50–75% oleic acid within the oil in those seeds; vs. historical average of 20% oleic acid in the oil of traditional sunflower (crop) plant varieties. See

also FATTY ACID, OLEIC ACID, HIGH-OLEIC OIL

SOYBEANS.

Mid-Oleic Vegetable Oils Refers to any vegetable oils (other than sunflower oil) that contain 50–70% oleic acid. The range of oleic acid content is slightly different for mid-oleic sunflower oil definition. See also

MID-OLEIC SUNFLOWERS, FATTY ACID, OLEIC

ACID.

Mimetics See BIOMIMETIC MATERIALS.

Minimized Domains See MINIMIZED PROTEINS.

Minimized Proteins The domain/active site of a (former) native protein after all or most

See LOW-TILLAGE CROP PRO-

DUCTION, NO-TILLAGE CROP PRODUCTION.

“Miniprotein Domains” S e e M I N I M I Z E D

PROTEINS.

“Miniproteins” See MINIMIZED PROTEINS.

Mitochondria Granular or rod-shaped bodies (organelles) in a cell’s cytoplasm, that contain the zyme systems required in the citric acid cycle, electron transport, beta oxidation of fatty acids, and synthesis of ATP via oxidative phosphorylation. See also ZYME SYS-

TEMS, CELL, MITOCHONDRIAL DNA, CARNITINE,

ADENOSINE TRIPHOSPHATE, FATTY ACIDS, FATS,

PHOSPHOLIPIDS, CYTOCHROME, CYTOPLASM,

CITRIC ACID CYCLE, ATP, Ac-CoA.

Mitochondrial DNA The DNA within an organism’s (e.g., human) cells that is located inside the mitchondria (organelles); not inside the cell nucleus. Mitochondrial DNA is only passed down from mother to offspring; not from father to offspring, as nuclear DNA is. See also DEOXYRIBONUCLEIC

ACID (DNA), CELL, MITOCHONDRIA, NUCLEUS,

CYTOPLASMIC DNA.

Mitogen A substance (growth factor, hormone, etc.) that initiates cell division within the body. For example, most Angiogenic Growth Factors (e.g., fibroblast growth factor) stimulate cell division of the endothelial cells which line blood vessel walls. See also

MITOSIS, GROWTH FACTOR, HORMONE, ANGIO-

GENIC GROWTH FACTORS, ENDOTHELIAL CELLS.

© 2002 by CRC Press LLC

(OF A

FLUORESCENCE,

Mitosis A process of cell duplication, or reproduction, during which one cell gives rise to two identical daughter cells. See also MITO-

GEN, TUBULIN.

Mixed-Function Oxygenases Enzymes catalyzing simultaneous oxidation of two substances by oxygen, one of which is usually NADPH or NADH. See also NADPH, NADH,

OXIDATION, ENZYME.

Model Organism Refers to an organism that is utilized (e.g., in scientific experiments) to conduct tests, etc. in an attempt to infer results applicable to larger, more complex organisms. For example, the use of the microscopic roundworm C. elegans in highthroughput screening to attempt to find pharmaceuticals that will be useful for humans.

See also ORGANISM, DROSOPHILA, CAENORHABDITIS ELEGANS (C. ELEGANS), HIGH-THROUGHPUT SCREENING (HTS), ARABIDOPSIS THALIANA.

Moiety Referring to a part or portion of a molecule, generally complex, having a characteristic chemical or pharmacological property.

See also ANALOGUE, PHARMACOPHORE.

Mold See FUNGUS.

Mole An Avogadro’s number (6.023 × 1023) of whatever units are being considered. One gram molecular weight of an element or a compound (i.e., same number of grams of an element or a compound as that substance’s molecular weight, equal to 6.023 × 1023 molecules). See also MOLECULAR WEIGHT.

Molecular Beacon Term that is used to refer to specific oligonucleotides possessing a “hairpin loop” and bearing a fluorescent dye. A “quencher dye” located on a nearby portion of the hairpin loop prevents fluorescence until the hairpin loop is opened up. Molecular beacons (sometimes called fluorogenic probes) are utilized (e.g., in high-throughput screening or high-throughput identification) to detect the presence of a desired “target” molecule. When the “target” (i.e., a molecule possessing the desired functional group or desired property) is present within a given sample being evaluated, the “hairpin loop” opens up because a portion of it forms a stronger bond to the “target,” than to the rest of the loop thereby allowing the fluorescent dye to emit light. See also OLIGONUCLEOTIDE,

HAIRPIN LOOP, TARGET

THERAPEUTIC AGENT), TARGET (OF A HERBICIDE

OR INSECTICIDE), HIGH-THROUGHPUT IDENTIFICA-

TION, HIGH-THROUGHPUT SCREENING (HTS).

Molecular Biology A term coined by Vannevar Bush during the 1940s that eventually came to mean the study and manipulation of molecules that constitute, or interact with, cells. Molecular biology as a distinct scientific discipline originated largely as a result of a decision to provide “support for the application of new physical and chemical techniques to biology” during the 1930s by Warren Weaver, director of the biology (funding) program at America’s Rockefeller Foundation (a philanthropic organization).

See also MOLECULAR GENETICS, GENETICS,

GENETIC ENGINEERING, BIOLOGICAL ACTIVITY,

BIOPOLYMER, BIOGENESIS, BIOCHEMISTRY, DEOXY-

RIBONUCLEIC ACID (DNA), MITOSIS, MEIOSIS.

Molecular BreedingTM A trademarked term that refers to certain “molecular evolution” technologies developed by Maxygen Company. This term is also sometimes used to refer to the utilization of molecular genetics

and/or marker assisted selection in a breed- M ing program (e.g., within a seed company or

within a university) to select the organisms (e.g., crop varieties) that possess gene(s) for a particular trait (higher yield, disease resis-

tance, etc.). See also MARKER ASSISTED SELECTION, MOLECULAR EVOLUTION, GENE, TRAIT,

MARKER (DNA SEQUENCE), QUANTITATIVE TRAIT

LOCI (QTL).

Molecular Chaperones See CHAPERONES, PRO-

TEIN FOLDING.

Molecular Diversity Sometimes referred to as “irrational drug design,” this refers to the drug design technique of generating large numbers of diverse candidate molecules (e.g., pieces of DNA, RNA, proteins, or other organic moieties) at random (via a variety of methods). These diverse candidate molecules are then tested to see which is best at working against a disease/condition (e.g., fitting a cell receptor, or category of receptors relevant to the disease in question). Molecular candidates that show promise (e.g., via a “pretty good fit” to receptor) are then produced in larger quantities (e.g., via Polymerase Chain Reaction techniques) along with additional molecules that are similar

© 2002 by CRC Press LLC