ACIDS, ANTIBODY AFFINITY CHROMATOGRAPHY,

LIGAND (IN CHROMATOGRAPHY).

Aflatoxin The term that is used to refer to a group of related mycotoxins (i.e., metabolites produced by fungi that are toxic to animals and humans) produced by some strains

Aspergillus flavus and Aspergillus parasiticus, common fungi that typically live on decaying vegetation. Corn earworm (Helicoverpa zea) and European corn borer (Ostrinia nubilalis) are vectors (carriers) of Aspergillus flavus. Aflatoxin B1 is the most commonly occurring aflatoxin and one of the most potent carcinogens known to man. When dairy cattle eat aflatoxin-contami- nated feed, their metabolism process converts the aflatoxin (e.g., Aflatoxin B1) into the mycotoxins known as Aflatoxin M1 and Aflatoxin M2, which soon appear in the milk produced. Consumption of aflatoxins by humans can also result in acute liver damage.

See also CARCINOGEN, TOXIN, FUNGUS, MYCOTOXINS, STRESS PROTEINS, LIPOXYGENASE (LOX),

PEROXIDASE, HELICOVERPA ZEA (H. zea), BETA CAROTENE, OH43, BRIGHT GREENISH-YELLOW

FLUORESCENCE (BGYF), CORN, EUROPEAN CORN

BORER (ECB).

AFLP Acronym for Amplified Fragment Length Polymorphism. See also AMPLIFIED

FRAGMENT LENGTH POLYMORPHISM.

Agar A complex mixture of polysaccharides obtained from marine red algae. It is also called agar-agar. Agar is used as an emulsion stabilizer in foods, as a sizing agent in fabrics, and as a solid substrate for the laboratory culture of microorganisms. Agar melts at 100°C (212°F), and when cooled below 44°C (123°F) forms a stiff and transparent gel. Microorganisms are seeded onto and grown (in the laboratory) on the surface of

the gel. See also POLYSACCHARIDES, CULTURE MEDIUM.

Agarose A highly purified form of agar used as a stationary phase (substrate) in some chromatography and electrophoretic methods.

See also CHROMATOGRAPHY, ELECTROPHORESIS,

AGAR.

Aging The process, affecting organisms and most cells, whereby each cell division (mitosis) brings that cell (or organism composed of such cells) closer to its final cell division

	(i.e., death). Notable exceptions to this aging
			A
	process include cancerous cells (e.g., myelo-
	mas) and the single-celled organism; both of
	which are “immortal.” See also TELOMERES,
	MITOSIS, HYBRIDOMA, MYELOMA, CANCER.
	Aglycon A nonsugar component of a glyco-
	side. See also GLYCOSIDE.
	Aglycone The biologically active (molecular)
	form of molecules of isoflavones. See also
	ISOFLAVONES, BIOLOGICAL ACTIVITY.
	Agonists Small protein or organic molecules
	that bind to certain cell proteins (i.e., recep-
	tors) at a site that is adjacent to the cell’s
	“docking” site of protein hormones, neu-
	rotransmitters, etc. (i.e., receptor) to induce
	a conformational change in that cell protein,
	thereby enhancing its activity (i.e., effect
	upon the cell). See also RECEPTORS, ACTIVE
	SITE, CONFORMATION, CELL, HORMONE, ANTAGO-
	NISTS, NEUROTRANSMITTER.
	Agraceutical See NUTRACEUTICAL, PHYTOCHEM-
	ICAL.
	Agrobacterium tumefaciens A	n a t u r a l l y
	occurring bacterium that is capable of insert-
	ing its DNA (genetic information) into
	plants, resulting in a type of injury to the
	plant known as crown gall. In 1980, Marc
	van Montagu showed that Agrobacterium
	tumefaciens could alter the DNA of its host
	plant(s) by inserting its own (“foreign”)
	DNA into the genome of the host plants
	(thereby opening the way for scientists to
	insert virtually any foreign genes into plants
	via use of A. tumefaciens). In 1983, Luis
	Herrera-Estrella created the first man-made
	transgenic plant by inserting an antibiotic-
	resistant gene into a tobacco plant. During
	2000, Weija Zhou and Richard Vierling
	proved that A. tumefaciens	is at least
	10 times more effective (i.e., at “infecting”
	plants to insert DNA) in space (i.e., weight-
	lessness/microgravity) than it is when on the
	surface of the Earth. Among others, Mon-
	santo Company has developed a way to stop
	A. tumefaciens from causing crown gall,
	while maintaining its ability to insert DNA
	into plant cells, and now uses A. tumefaciens
	as a vehicle to insert desired genes into crop
	plants (e.g., the gene causing high production
	of CP4 EPSP synthase, thus conferring resis-
	tance to glyphosate-containing	herbicide).

© 2002 by CRC Press LLC

See also BACTERIA, DEOXYRIBONUCLEIC ACID

A (DNA), INFORMATIONAL MOLECULES, GENOME,

TRANSGENIC (ORGANISM), PROTOPLAST, EPSP SYNTHASE, CP4 EPSPS, “SHOTGUN” METHOD,

BIOLISTIC® GENE GUN, WHISKERS™, GENETIC ENGINEERING, GENE, BIOSEEDS, GLYPHOSATE,

GLYPHOSATE-TRIMESIUM, GLYPHOSATE ISOPRO-

PYLAMINE SALT, NOS TERMINATOR.

AHG Antihemophilic Globulin. Also known as FACTOR VIII or Antihemophilic Factor VIII.

See also FACTOR VIII, GAMMA GLOBULIN.

AIDS See ACQUIRED IMMUNE DEFICIENCY SYN-

DROME (AIDS).

Alanine (ala) A nonessential amino acid of the pyruvic acid family. In its dry, bulk form it appears as a white crystalline solid. See

also ESSENTIAL AMINO ACIDS.

Albumin A protein that the liver synthesizes (manufactures). Most minerals and hormones utilized by the human body are first “attached” to a molecule of albumin before they are transported in the bloodstream to where they are needed in the body. See also

PROTEIN, HORMONE, SUPERCRITICAL CARBON

DIOXIDE.

ALCAR Acronym for Acetyl-L-Carnitine. See

also ACETYL CARNITINE.

Aldose A simple sugar in which the carbonyl carbon atom is at one end of the carbon chain. A class of monosaccharide sugars; the molecule contains an aldehyde group. See

also MONOSACCHARIDES.

Aleurone The layer (“skin”) that covers the endosperm portion of a plant seed. See also

ENDOSPERM.

AlfAFP Acronym for Alfalfa Antifungal Peptide. See also DEFENSINS.

Algae A heterogeneous (widely varying) group of photosynthetic plants, ranging from microscopic single-cell forms to multicellular, very large forms such as seaweed. All of them contain chlorophyll and hence most are green, but some may be different colors due to the presence of other, overshadowing pigments.

Alicin A compound that is produced naturally by the garlic plant when the cells within garlic bulbs are broken open (e.g., during food preparation or consumption). Enzymes present within those garlic cells convert (precursor compound) to alicin. Research indicates that human consumption of alicin confers some

specific health benefits (anti-thrombotic, reduce blood cholesterol levels, reduce/avoid coronary heart disease, enhance the immune system, etc.). See also CELL, PHYTOCHEMICALS,

ENZYME, THROMBOSIS, CORONARY HEART DISEASE

(CHD), CHOLESTEROL.

Alkaline Hydrolysis A chemical method of liberating DNA from a DNA-RNA hybrid.

See also HYDROLYSIS, RIBONUCLEIC ACID (RNA),

DNA-RNA HYBRID, DEOXYRIBONUCLEIC ACID

(DNA).

Alkaloids A class of toxic compounds that are naturally produced by some organisms (e.g., ants, certain plants such as lupines, and certain fungi such as ergot). For example, certain species of ants naturally produce alkaloids, as a self-defense mechanism. Poi- son-dart frogs (Dendrobates azureus) and two species of New Guinea songbirds (Pitohui dichrous and Ifrita kowaldi) can tolerate those ant-produced alkaloids, so they also acquire that self-defense (toxin) by eating those particular ants. Another example is the moth Utetheisa ornatrix, whose larvae (caterpillars) feed on certain plants that contain pyrrolizidine alkaloids. Because those alkaloids are extremely bitter tasting and toxic, spiders that normally prey on them refuse to eat those Utetheisa ornatrix; even after they later become adult moths. If those moths (who consumed those pyrrolizidine alkaloids as larvae) get caught in the spider’s web, the spider will cut it out of the web and release that particular (toxic) moth. Vinca alkaloids, isolated from the specific plants that produce them, have been utilized as can- cer-treating (antitumor) drugs. See also

TOXIN, FUNGUS, TREMORGENIC INDOLE ALKALOIDS, ERGOTAMINE.

Allele From the Greek allelon, mutually each other, the term refers to one of several alternate forms of a gene occupying a given locus on the chromosome, which controls expression (of product) in different ways. See also

EXPRESS, GENE, CHROMOSOMES, LOCUS.

Allelic Exclusion The expression in any particular manner of only one of the alleles in an antibody gene within a B lymphocyte (cell), coding for the expressed antibody. See

also A L L E L E , C O D I N G S E Q U E N C E , G E N E ,

B LYMPHOCYTES , ANTIBODY, IMMUNOGLOBULIN.

© 2002 by CRC Press LLC

Allelopathy Refers to the secretion of certain chemicals (e.g., terpenoid compounds) by a plant, in order to hinder the growth or reproduction of other plants growing near it.

Allergies (airborne) See MAST CELLS. Allergies (foodborne) A n I g E - m e d i a t e d

(aggressive) immune system response to antigen(s) present on protein molecules in the particular food to which (a given) person is allergic. The antibodies (IgE) bind to those antigens and trigger a humoral immune response that can cause vomiting, diarrhea, skin reactions, wheezing, and respiratory distress. In severe cases, the immune response can cause death. In some rare instances, the allergic reaction is mediated by sensitized T cells. In some rare instances, the onset of a food allergy incident is induced by exercise (before or after eating that particular food).

The U.S. Food and Drug Administration (FDA) requires testing in advance to determine if a genetically engineered foodstuff has the potential to cause allergic reactions in humans, before that genetically engineered foodstuff (e.g., a modified crop plant) is approved by the FDA. In general, known food allergens (e.g., peanuts, Brazil nuts, wheat, etc.) are protein molecules that are resistant to rapid digestion (because those protein molecules are too tightly “folded together” for digestive enzymes to access their chemical bonds to break down). One potential way to genetically engineer currently allergenic crops (e.g., wheat) to make them less allergenic, is to insert gene(s) for extra production of thioredoxin. Found in all living organisms, thioredoxin is a protein that targets and breaks down the chemical bonds holding together a tightly foldedtogether protein molecule (thereby making those protein molecules easier to digest). Future crops engineered to contain more thioredoxin than the traditional average level may be nonallergenic. See also PROTEIN, PRO-

TEIN FOLDING, ANTIBODY, ANTIGEN, FOOD AND DRUG ADMINISTRATION (FDA), GENETIC ENGINEERING, IMMUNOGLOBULIN, HUMORAL IMMUNITY,

MAST CELLS, LEUKOTRIENES, DIGESTION (WITHIN

ORGANISMS), ORGANISM.

Allicin See ALICIN.

	Allogeneic With a different set of genes (but
		A
	same species). For example, an organ trans-
	plant from one nonrelated human to another
	is allogeneic. An organ transplant from a
	baboon to a human would be xenogeneic.
	See also GENE, SPECIES, XENOGENEIC ORGANS.
	Allosteric Enzymes R eg u l a t o r y e n z y m e s
	whose catalytic activity is modulated by the
	noncovalent binding of a specific metabolite
	(effector) at a site (regulatory site) other than
	the catalytic site (on the enzyme). Effector
	binding causes a three-dimensional confor-
	mation change in the enzyme and is the root
	of the modulation. The term allosteric is used
	to differentiate this form of regulation from
	the type that may result from the competition
	between substrate and inhibitors at the cata-
	lytic site. See also ENZYME, STERIC HINDRANCE,
	EFFECTOR, CONFORMATION, ACTIVE SITE.
	Allosteric Site The site on an (allosteric)
	enzyme molecule where, via noncovalent
	binding to the site, a given effector can
	increase or decrease that enzyme’s catalytic
	activity. Such an effector is called an allos-
	teric effector because it binds at a site on the
	enzyme molecule that is other (allo) than the
	enzyme’s catalytic site. See also ALLOSTERIC
	ENZYMES, ACTIVATOR, CATALYTIC SITE, EFFEC-
	TOR, CONFORMATION, ENZYME, METABOLITE,
	CATALYST.
	Allotypic Monoclonal Antibodies Monoclonal
	antibodies that are isoantigenic. See also
	MONOCLONAL ANTIBODIES (MAb), ANTIGEN.
	Allozyme See ALLOSTERIC ENZYMES.
	Aloe vera L . A plant whose sap (juice) con-
	tains certain carbohydrates that naturally
	assist healing of human skin (wounds).
	Those carbohydrates “activate” macroph-
	ages, which cause those macrophages to pro-
	duce cytokines (that regulate human immune
	system and inflammatory responses which
	promote healing). See also PHYTOCHEMICALS,
	CARBOHYDRATES (SACCHARIDES), MACROPHAGE,
	CYTOKINES.
	Alpha Amylase Inhibitor-1 A protein natu-
	rally produced in the seeds of the plant
	known as the common bean Phaseolus vul-
	garis that inhibits the amylase enzyme in the
	gut of the pest insect known as the pea weevil.
	Because the amylase enzyme (in its gut) is
	inhibited (prevented from helping digestion)

© 2002 by CRC Press LLC

P O L Y S A C C H A R I D E S ,

by the Alpha Amylase Inhibitor-1, the seeds

Aof the P. vulgaris plant are protected from depradation by the pea weevil. See also PRO-

TEIN, ENZYME, AMYLASE, WEEVILS.

Alpha Galactosides Term referring to a family of polysaccharides (produced in plant seeds) composed (at the molecular level) of one sucrose unit linked by a 1,6 molecular bond to several galactose units. Alpha galactosides include raffinose, stachyose, and verbascose . See also

GALACTOSE (GAL), STACHYOSE.

Alpha Helix ( -helix) A highly regular (i.e., repeating) structural feature that occurs in certain large molecules. First discovered in protein molecules by Linus Pauling in the late 1940s. See also A-DNA, PROTEIN, PROTEIN

FOLDING, PROTEIN STRUCTURE.

Alpha Interferon Also written as α-inter- feron, it has been shown to prolong life and reduce tumor size in patients suffering from Kaposi’s sarcoma (a cancer that affects approximately 10% of people with acquired immune deficiency syndrome). It is also effective against hairy-cell leukemia and may work against other cancers. It has recently been approved by the U.S. FDA for use against certain types of sarcoma. Recent research indicates that injections of alpha interferon can limit the liver damage typically caused by hepatitis C, a viral disease.

See also INTERFERONS.

ALS A plant enzyme (also present in some microoganisms) known as acetolactate synthase or acetohydroxy acid synthase. ALS catalyzes (enables to occur) one of the early chemical reaction steps in the synthesis (manufacturing) of branched-chain amino acids (isoleucine, leucine, valine) required by plants to sustain life (i.e., to make needed proteins). Herbicides that deactivate/destroy ALS are effective at killing plants (e.g., weeds). See also ENZYME, GENE, ALS GENE,

MICROORGANISMS, CATALYST, AMINO ACID, ISO-

LEUCINE (ile), LEUCINE (leu), VALINE (val).

ALS Gene Gene that codes for (i.e., causes to be produced in microorganisms or plants’ chloroplasts) the critical-to-plants enzyme acetolactate synthase (ALS). See also GENE,

HTC, MICROORGANISMS, CHLOROPLASTS, ENZYME,

CATALYST, AMINO ACID, ISOLEUCINE (ile), LEUCINE

(leu), VALINE, STS SULFONYLUREA (HERBICIDE)-

TOLERANT SOYBEANS.

Alternative mRNA Splicing See TRANSCRIP-

TOME, CENTRAL DOGMA (NEW).

Alternative Splicing See TRANSCRIPTOME, CEN-

TRAL DOGMA (NEW).

Alu Family A set of dispersed and related genetic sequences, each about 300 base pairs long, in the human genome. At both ends of these 300 bp segments there is an A-G-C-T sequence. Alu 1 is a restriction enzyme that recognizes this sequence and cleaves (cuts) it between the G (guanine) and the C (cytosine). See also GENOME, RESTRICTION

ENDONUCLEASES.

Aluminum Resistance See CITRATE SYNTHASE

(CSb) GENE, GENE, CITRIC ACID.

Aluminum Tolerance See CITRATE SYNTHASE

(CSb) GENE, GENE, CITRIC ACID.

Aluminum Toxicity See CITRATE SYNTHASE

(CSb) GENE, GENE, CITRIC ACID.

Alzheimer’s Disease N a m e d a f t e r A l o i s Alzheimer who, in 1906, first described the Amyloid β Protein (AβP) plaques in the human brain that are caused by this disease. Alzheimer’s disease causes progressive memory loss and dementia in its victims as it kills brain cells (neurons). Some drugs (e.g., tacrine, donepezil, etc.) appear to slow the progression of Alzheimer’s disease (by increasing the availability of acetylcholine in the brain), but there is currently no way to stop the disease. See also AMYLOID β PRO-

TEIN (AβP), AMYLOID β PROTEIN PRECURSOR

(AβPP), NEURON, NEUROTRANSMITTER, ACETYL-

CHOLINE, OXIDATIVE STRESS.

AMD Acronym for Age-related Macular Degeneration. See also LUTEIN.

American Society for Biotechnology (ASB)

A society founded for the purpose of “providing a multiand interdisciplinary forum for those persons from academia, industry, and government who are interested in any and all aspects of biotechnology, and will achieve its aims by cooperation with existing organizations active in the field.” To join, write to ASB, P.O. Box 2820, Sausalito, California, 94966-2820. See also BIOTECHNOLOGY,

INTERNATIONAL SOCIETY FOR THE ADVANCEMENT

OF BIOTECHNOLOGY (ISAB), BIOTECHNOLOGY

INDUSTRY ORGANIZATION (BIO).

© 2002 by CRC Press LLC