Lysophosphatidylethanolamine Also known by the abbreviation LPE; also known as phosphatidyl ethanolamine. It is one of the lipids (phospholipids) naturally found in soybean oil. In plants, it functions as a signaling molecule (e.g., speeding the ripening process). See

also LIPIDS, SOYBEAN OIL, SIGNALING MOLECULE.

Lysosome A membrane-surrounded organelle in the cytoplasm of eucaryotic cells which contains many hydrolytic enzymes. The lysosome internalizes and digests foreign proteins as well as cellular debris. The protein fragments (epitopes) are “presented” to T cells by the major histocompatibility complex (MHC) proteins on the surface of the eucaryotic cell. See also ANTIGEN, MAJOR HIS-

TOCOMPATIBILITY COMPLEX (MHC), T CELLS.

Lysozyme An enzyme, naturally produced by some animals, which possesses antibacterial (bacteria-killing) properties. Discovered in 1922 by Alexander Fleming, in his nasal mucus, Mr. Fleming named it from the

Greek lyso — due to its ability to lyse (cut) bacteria — and zyme — due to its being an enzyme.

Lysozyme lyses certain kinds of bacteria, by dissolving the polysaccharide components of the bacteria’s cell wall. When that cell wall is weakened, the bacteria cell bursts because osmotic pressure (inside that bacteria cell) is greater than the weakened cell wall can contain. Tears and egg whites both contain significant amounts of lysozyme, as agents to prevent bacterial infections (e.g., against bacteria entering the body via eye openings; against bacteria entering the chicken embryo through the eggshell). See

also ENZYME, LYSIS, CELL, CYTOLYSIS, POLYSACCHARIDES, BACTERIA.

Lytic Infection A viral infection in which the final act of the infection is to lyse (i.e., burst, or destroy) the cell. This releases the new (progeny) viruses so they can go on to infect

other cells. See also LYSE, LYSIS.

L

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M

MAA Marketing Authorization Application

It is the European Union (EU) equivalent to a U.S. NDA (New Drug Application). An MAA is an application to the EU’s Committee for Proprietary Medicinal Products (CPMP) seeking approval of a new drug that has undergone Phase 2 and Phase 3 clinical trials. See also NDA (TO FDA), CANDA, FOOD

AND DRUG ADMINISTRATION (FDA), MAA, NDA (TO

KOSEISHO), CPMP, PHASE I CLINICAL TESTING,

PHASE II CLINICAL TESTS, PHASE III CLINICAL

TESTS.

MAB See MARKER ASSISTED BREEDING.

MAb See MONOCLONAL ANTIBODIES (MAb).

Macromolecules L a r g e m o l e c u l e s w i t h molecular weights ranging from a few thousand to hundreds of millions. See also

MOLECULAR WEIGHT.

Macrophage A phagocytic cell that is the counterpart of the monocyte. A monocyte that has left the bloodstream and has moved into the tissues. Macrophages have basically the same functions as monocytes, but they carry these out in the tissues. In summary, they engulf and kill microorganisms, present antigen to the lymphocytes, kill certain tumor cells, and their secretions regulate inflammation.

Macrophages utilize nitric oxide (which they synthesize) to kill the microorganisms they engulf (via oxidation), and the nitric oxide also helps to regulate the immune system. In the spleen, macrophages engulf and destroy old red blood cells. When they reside in the bone marrow, they store iron and then transfer it to red blood cells. In the lungs and GI tract, they are scavengers and keep tissues clean. They also serve as a reservoir for the AIDS virus.

0-8493-XXXX-X/01/$0.00+$1.50 © 2001 by CRC Press LLC

They (and other phagocytic cells) are largely responsible for the localization and degradation of foreign materials at inflammatory sites. Macrophages display chemotaxis (i.e., the sensing of, and movement toward or away from a specific chemical). For example, consumption (in food/feed) of mannanoligosaccharides by mammals causes macrophages (within that mammal’s bloodstream) to depart from the bloodstream and move toward the gastrointestinal tract (tissues) where those macrophages eliminate some pathogens (i.e., those growing/reproducing in the gastrointestinal tract). See also

CELL CELLULAR IMMUNE RESPONSE, CHEMOTAXIS,
MONOCYTES, PHAGOCYTE, ADHESION MOLECULE,
LYSOSOME, NITRIC OXIDE, NITRIC OXIDE SYN-	M
THASE, MANNANOLIGOSACCHARIDES (MOS),
PATHOGEN, LEUKOTRIENES.

Macrophage Colony Stimulating Factor (M-CSF) A colony stimulating factor (CSF) that stimulates production of macrophages in the body. See also COLONY STIM-

ULATING FACTORS (CSFs), MACROPHAGE.

MACS Acronym for Magnetic Cell Sorting.

See also MAGNETIC PARTICLES.

Magainins Discovered within frog skin tissues by Michael Zasloff in 1987, magainins are antimicrobial, amphopathic peptides that lyse (burst) certain cells upon contact by “worming” their hydrophobic portion into the cell’s membrane, which creates a transmembrane (i.e., through the surface) pore (allowing ions to flow into the cell, causing osmotic bursting). Magainins are selective against bacteria, fungi, and protozoa cells. The word magainin comes from the Hebrew word for “shield.” See also AMPHIPHILIC MOL-

ECULES, CELL, PEPTIDE, BACTERIA, FUNGUS, ANTI-

BIOTICS, PLASMA MEMBRANE.

© 2002 by CRC Press LLC

“Magic Bullet” When this term was first coined by Paul Ehrlich in 1905, it initially referred only to antibodies (e.g., because antibodies seek their own target, without damaging other nearby tissues). However, over time, this term has come to be applied to immunotoxins and other immunoconjugates (i.e., toxic or pharmacological molecules which are “attached” to an antibody that “steers/guides” the toxic or pharmacological molecule to the intended “target” in the body such as a tumor). See also ANTIBODY,

IMMUNOCONJUGATE, IMMUNOTOXIN, GENISTEIN,

RICIN, MONOCLONAL ANTIBODIES (MAb), HER2

GENE.

Magnetic Antibodies See MAGNETIC PARTICLES.

Magnetic Beads See MAGNETIC PARTICLES.

Magnetic Cell Sorting See MAGNETIC PARTICLES.

Magnetic Labeling See MAGNETIC PARTICLES.

Magnetic Particles Refers to various tiny pieces of naturally magnetic materials, that are bonded (attached) to antibodies (e.g., monoclonal antibodies that are specific to a particular type of cell). These can then be

Mmixed with a large population of many cell types (crude tissue samples, cells grown in a vat/reactor, etc.), where the magnetic antibodies will attach themselves to only the desired cells, then the desired cells are separated out using a magnetic field (and the magnetic particles/antibodies are subse-

quently removed from those cells). See also

ANTIBODY, MONOCLONAL ANTIBODIES (MAb),

CELL, IMMUNOCONJUGATE, CELL SORTING.

Maize See CORN.

Major Histocompatibility Complex (MHC)

A chromosomal region (approximately 3,000 Kb) which encodes for three classes of transmembrane (cell) proteins. MHC I proteins (located on the surface of nearly all cells) present foreign epitopes (i.e., fragments of antigens that have been ingested; peptides) to cytotoxic T cells (killer T cells). MHC II proteins (located on the surface of immune system cells and phagocytes) present foreign epitopes to helper T cells, and MHC III proteins are components of the complement cascade. Genes in the MHC must be matched (between an organ donor and organ recipient) to prevent rejection of organ transplants. See also COMPLEMENT CASCADE,

GRAFT-VERSUS-HOST DISEASE (GVHD), Kb, MAC-

ROPHAGE, PROTEIN, CELL, T CELL RECEPTORS,

ANTIGEN, T CELLS, CYTOTOXIC T CELLS, EPITOPE,

GENE, TUMOR-ASSOCIATED ANTIGENS, HUMAN

LEUKOCYTE ANTIGENS (HLA).

MAL (Multiple Aleurone Layer) Gene A gene in corn (maize) that (when present in the DNA of a given plant) causes that plant to produce seed that contains higher-than- normal levels of calcium, magnesium, iron, zinc, and manganese. These higher mineral levels are particularly useful for feeding of swine, since traditional No. 2 yellow (dent) corn does not contain enough for optimal pig

growth. See also GENE, DEOXYRIBONUCLEIC ACID (DNA), HIGH-METHIONINE CORN, HIGH-

LYSINE CORN, FLOURY-2, OPAGUE-2.

MALDI-TOF-MS Acronym for Matrix-Asso- ciated Laser Desorption Ionization Time of Flight Mass Spectrometry. A mass spectrometry methodology/technology that can establish, in seconds, the identity, purity, etc. of a sample of proteins, oligonucleotide, or (poly)peptides. Also the identification of gram-positive microorganisms, or characterization of genetic materials (DNA, RNA, etc.) on hybridization surfaces. MALDITOF utilizes measurement of the time for particles (e.g., proteins) to transit a specific distance after being “dislodged” from (‘adhered’) surface by specific amount of energy to precisely determine the molecular weight (of proteins, etc.). See also MASS SPEC-

TROMETER, MICROORGANISM, OLIGONUCLEOTIDE,

GRAM-POSITIVE, RIBONUCLEIC ACID (RNA),

HYBRIDIZATION SURFACES, DEOXYRIBONUCLEIC

ACID (DNA), IN SILICO BIOLOGY, PROTEIN, PEPTIDE.

Male-sterile See BARNASE. Malonyl CoA See FATS.

Mammalian Cell Culture Te c h n o l o g y t o artificially cultivate cells, of mammal origin, in a laboratory or production-scale device (i.e., in vitro). Can be either a batch or continuous process device. The first mammalian cell culture was performed by a neurobiologist named R. G. Harrison in 1907, when he added chopped-up spinal cord tissue to clotted (blood) plasma in a humidified growth chamber. The nerve cells from this spinal cord tissue successfully grew, divided, and extended long fibers into the clot. Many

© 2002 by CRC Press LLC

	improvements to cell culture process have	between that DNA sequence (the “marker”)
	been made over the years, including special	and the gene(s) that cause that particular
	growth media (fluids that bathe the cultured	trait. Such markers have been utilized to
	cells with the right amounts of amino acids,	aid/speed up the process of plant (e.g., crop)
	salts, and other minerals). See also CONTIN-	breeding since the mid-1970s, via Marker
	UOUS PERFUSION, DISSOCIATING ENZYMES, HAR-	Assisted Selection. See also DEOXYRIBO-
	VESTING ENZYMES, IN VITRO , PLASMA, CELL,	NUCLEIC ACID (DNA), TRAIT, LINKAGE, LINKAGE
	MEDIUM, AMINO ACID.	GROUP, LINKAGE MAP, GENE, SEQUENCE (OF A
	Mannan Oligosaccharides See MANNANOLIGO-	DNA MOLECULE), MARKER ASSISTED SELECTION.
	SACCHARIDES (MOS).	Marker (genetic marker) A trait that can be
	Mannanoligosaccharides (MOS) A family of	observed to occur or not to occur in an organ-
	oligosaccharides that can be produced by	ism such as, e.g., bacteria or plant(s).
	man in commercial quantities via certain	Genetic markers include such traits as:
	yeast cells. When consumed (e.g., by	expression of luciferase-catalyzed biolumi-
	humans or monogastric livestock such as	nescence in leaf cells (causing leaves to glow
	swine or poultry), mannose sugars in the	when illuminated by certain light sources);
	MOS stimulate the liver to secrete the man-	resistance to specific antibiotics; the nature
	nose-binding protein. Mannose-binding pro-	of the cell wall and capsule characteristics;
	tein enters the digestive system and binds to	requirements for a particular growth factor;
	the (mannosecontaining) capsule (surface	and carbohydrate utilization, to mention a
	membrane) of pathogenic bacteria. That bind-	few. For example, if a culture of dividing
	ing to pathogens triggers the immune sys-	(growing) bacteria that is not resistant to a
	tem’s complement cascade to combat those	particular antibiotic (i.e., lacks the trait of
	pathogenic bacteria. Consumption of man-	antibiotic resistance) is exposed to only the
			M
	nanoligosaccharides by mammals also causes	DNA isolated from bacteria that are resistant
	macrophages to move toward the gastrointes-	to the antibiotic, then a fraction of the cells
	tinal tract (in body’s tissues), where those	exposed will directly incorporate this trait
	macrophages eliminate some pathogens (i.e.,	(some DNA) into their genome, hence
	growing/reproducing in the gastrointestinal	acquiring the trait. The first genetically engi-
	tract). See also OLIGOSACCHARIDES, FRUCTOSE	neered plants bearing a marker gene were
	OLIGOSACCHARIDES, SUGAR MOLECULES, YEAST,	field tested in 1986. See also ALLELE, GENETIC
	COMPLEMENT CASCADE, PATHOGENIC, BACTERIA,	ENGINEERING, POSITIVE AND NEGATIVE SELEC-
	IMMUNE RESPONSE, COMPLEMENT, CAPSULE,	TION (PNS), TRANSFORMATION, TRANSFECTION,
	MACROPHAGE, FOSHU, NUTRACEUTICALS.	NPTII GENE, BIOLUMINESCENCE, MARKER ASSISTED
	Map Distance A number proportional to the	SELECTION, GUS GENE, bla GENE, RECOMBINASE.
	frequency of recombination between two	Marker Assisted Breeding S e e M A R K E R
	genes. One map unit corresponds to a recom-	ASSISTED SELECTION.
	bination frequency of 1%. See also GENETICS,	Marker Assisted Selection The utilization of
	GENETIC CODE, GENETIC MAP, GENE, LINKAGE,	DNA sequence “markers” by commercial
	QUANTITATIVE TRAIT LOCI (QTL).	breeders to select the organisms (crops, live-
	Mapping (of genome) See GENETICS, GENETIC	stock, etc.) that possess gene(s) for a partic-
	CODE, GENETIC MAP, QUANTITATIVE TRAIT LOCI,	ular performance trait (rapid growth, high
	POSITION EFFECT.	yield, etc.) desired, for subsequent breed-
	Marker (DNA marker) A DNA fragment of	ing/propagation. Marker Assisted Selection
	known size used to calibrate an electro-	has been utilized in many plant (e.g., crop)
	phoretic gel. See also ELECTROPHORESIS, TWO-	breeding programs since the mid-1970s. See
	DIMENSIONAL (2D) GEL ELECTROPHORESIS,	also DEOXYRIBONUCLEIC ACID (DNA), SEQUENCE
	DEOXYRIBONUCLEIC ACID (DNA).	(OF A DNA MOLECULE), MARKER (DNA SEQUENCE),
	Marker (DNA sequence) A specific sequence	GENE, TRAIT, GENETIC MAP, LINKAGE, LINKAGE
	of DNA that is virtually always associated	GROUP, MOLECULAR BREEDING, LINKAGE MAP,
	with a specified trait, because of “linkage”	QUANTITATIVE TRAIT LOCI (QTL).
	© 2002 by CRC Press LLC