several different types of immune system cells), and is a hematopoietic growth factor.

See also HEMATOPOIETIC GROWTH FACTORS

(HGF), GROWTH FACTOR, GLYCOPROTEIN, PLEIO-

TROPIC, MACROPHAGE, CYTOKINES.

Interleukin-7 (IL-7) A cytokine (glycoprotein) synthesized in the bone marrow that stimulates early (fetal) proliferation and differentiation of B cells and T cells. May be useful in regenerating lymphoid cells in patients whose immune systems have been devastated by cancer chemotherapy. See also

CYTOKINES, GLYCOPROTEIN, STEM CELL ONE,

T CELLS , CANCER.

Interleukin-8 (IL-8) A basic polypeptide (glycoprotein) with heparin-binding activity. Endogenous endothelial IL-8 appears to regulate transvenular traffic during acute inflammatory responses. See also

TIDE (PROTEIN), GLYCOPROTEIN,

ENDOTHELIAL CELLS, ENDOTHELIUM,

PHONUCLEAR LEUKOCYTES (PMN),

IMMUNE RESPONSE.

Interleukin-9 (IL-9) A cytokine (glycoprotein) that is released at sites in the body where inflammation has occurred. See also

CYTOKINES, GLYCOPROTEIN, CELLULAR IMMUNE

RESPONSE.

Interleukin-12 (IL-12) A cytokine (glycoprotein) produced by the body, which serves to activate the immune system against certain tumors and pathogens. See also CYTOKINES,

GLYCOPROTEIN, TUMOR, TUMOR-ASSOCIATED

ANTIGENS, MAJOR HISTOCOMPATIBILITY COMPLEX

(MHC), T CELL RECEPTORS, CYTOTOXIC T CELLS,

PATHOGEN.

Intermediary Metabolism T h e c h e m i c a l reactions that take place in the cell that transform the complex molecules derived from food into the small molecules needed for the growth and maintenance of the cell. See also

METABOLISM, CELL, DIGESTION (WITHIN ORGAN-

ISMS), METABOLIC PATHWAY.

International Food Biotechnology Council (IFBC) An organization that was established in 1988 by the Industrial Biotechnology Association (IBA) and the International Life Sciences Institute (ILSI), in order to “produce a (recommended) set of guidelines that could be used to assess the safety of genetically altered foods." See also GNE,

of the 1979 IPPC text. See also SPS, EUROPEAN

PLANT PROTECTION ORGANIZATION (EPPO),

INTERNATIONAL OFFICE OF EPIZOOTICS (OIE),

WORLD TRADE ORGANIZATION (WTO), NORTH

AMERICAN PLANT PROTECTION ORGANIZATION

(UPOV).

Internaulin See CADHERINS.

Introgression The incorporation of exotic (i.e., wild type) genes into elite germplasm (i.e., domesticated breeding lines), or of transgenes (i.e., genes from transgenic organisms) into a wild type’s genome. See

also TRANSGENIC, OUTCROSSING, WILD TYPE,

GENOME, GENE, TRANSLOCATION.

Intron A (intervening sequence) segment of deoxyribonucleic acid (DNA) that is transcribed, but is removed from within the transcript by splicing together the sequences (exons) on either side of it (in the molecule). It is generally considered a nonfunctioning portion of the molecule. See also TRANSCRIP-

TION, DEOXYRIBONUCLEIC ACID (DNA), EXON.

Inulin A fructose oligosaccharide (FOS) that is naturally produced in more than 30,000 plants. Like many other FOS, consumption of inulin by humans results in several health benefits (helps prevent coronary heart disease, promote growth of bifidobacteria in the intestines, reduce likelihood of developing diabetes, promote absorption of calcium from foods, etc.). During 2000, the European Union’s government regulatory agencies agreed to classify inulin as a water-soluble fiber (because humans cannot digest inulin).

See also FRUCTOSE OLIGOSACCHARIDES, WATER

SOLUBLE FIBER, BIFIDOBACTERIA, CORONARY

HEART DISEASE (CHD), DIABETES.

© 2002 by CRC Press LLC

Invasin A transmembrane (through the membrane of the cell) protein that enables bacterial cells to invade normal (body) cells. See

also CD4 PROTEIN, RECEPTORS, CELL, T CELL

RECEPTORS, ENDOCYTOSIS, PLASMA MEMBRANE.

Inverted Micelle See REVERSE MICELLE (RM),

MICELLE.

Investigational New Drug See IND.

Invitro See IN VITRO .

Invivo See IN VIVO.

IOGTR See INTERIM OFFICE OF THE GENE TECH-

NOLOGY REGULATOR (IOGTR).

Ion From the Greek ion, something that goes. An ion is an atom or molecule possessing a positive or a negative electrical charge. Ions are produced by the dissociation (coming apart) of a (electrolyte) molecule resulting from an electrolyte dissolving in a solution. One example is the dissociation of common table salt (sodium chloride) in water, which results in positively charged sodium ions (called cations) and negatively charged chloride ions (called anions). Ions play critically important roles in many biological processes such as nerve activity. See also CHELATION,

CHELATING AGENT, ION CHANNELS, CITRIC ACID,

CITRATE SYNTHASE (CSb) GENE.

Ion Channels Refers to specialized proteins that act as “pores” (through the plasma membrane of a cell) through which certain ions (atoms or molecules bearing an electrical charge) are allowed to pass. The selectivity of ion channels can be altered when specific molecules (e.g., in the blood or digestive fluids) come in contact with the plasma membrane (i.e., G-protein receptors coupled to the ion channel). For example, the group of pharmaceuticals known as CALCIUM CHANNEL BLOCKERS (verapamil, amlopidine, diltiazem, nifedipine, etc.) act to “block” or hinder the movement of calcium ions through calcium ion channels: “pores” which had previously allowed calcium ions to enter relevant cells (i.e., in blood vessel walls) easily.

Another example is the mode of action of the “cry” (crystal-like) proteins that are naturally present within Bacillus thuringiensis

(B.t.) bacteria. When eaten by certain insects (possessing alkaline digestive fluids in their stomach or gut), cry proteins are hydrolyzed

(i.e., chemically “cut”) into fragments. One of those fragments — 60 Kd in size — attaches to specific receptors located on the surface (membrane) of certain cells which line the inside (epithelium) of the insect’s mid-gut. That attachment to those receptors triggers ion channels in the (epithelium) cell’s membrane to suddenly allow cations (atoms or molecules with positive electrical charge) to quickly flow out of the cell (which leads to death of all gut cells that the cry protein piece attached to). See also CELL,

PLASMA MEMBRANE, ION, CALCIUM CHANNEL-

BLOCKERS, MEMBRANE TRANSPORT, PROTEIN, CRY

PROTEINS, G-PROTEINS, BACILLUS THURINGIENSIS

(B.t.), BACTERIA, PROTOXIN, HYDROLYZE, KILO-

DALTON (Kd), RECEPTORS, EPITHELIUM.

Ion-Exchange Chromatography Separation of ionic compounds (which include nucleic acids and proteins) in a chromatographic column containing a polymeric resin (i.e., the stationary phase) having fixed charge groups. The process works in that the charges of the column (stationary phase) interact with the opposite charges of the material dissolved in the solution that is flowing through the column (mobile phase). The charge interaction between the column material and, i.e., the protein has the effect of slowing down the rate of movement of the protein through the column. The other molecules, meanwhile, which do not interact with the column, flow right on through. This constitutes the separation process. See also

CHROMATOGRAPHY.

IP-6 Inositol hexaphosphate. See also PHYTATE.

IPM See INTEGRATED PEST MANAGEMENT (IPM).

IPPC See INTERNATIONAL PLANT PROTECTION

developing countries. IDA also makes people more susceptible to diphtheria. See also

GOLDEN RICE, PHYTATE, LOW-PHYTATE CORN,

LOW-PHYTATE SOYBEANS, ORGANISM.

R H I Z O B I U M ( b a c t e r i a ) , P H Y T O P H T H E R A

MEGASPERMA F. SP. GLYCINEA, PHYTOPHTHERA

ROOT ROT, SIGNALING, SIGNALING MOLECULES,

HIGH-ISOFLAVONE SOYBEANS, ANTIOXIDANTS,

OXIDATIVE STRESS.

Isoflavonoids See ISOFLAVONES.

Isoleucine (ile) A monocarboxylic amino acid occurring within most dietary proteins. See

also AMINO ACID, PROTEIN, ALS GENE.

Isomer One of the two or more chemical substances having the same elementary percentage composition (i.e., same atoms) and molecular weight, but differing in structure and therefore in properties. There are many ways in which such structural differences (between the two or more isomeric mole-

Icules) occur. One example is n-butane [CH3 (CH2)2CH3] and isobutane [CH3CH(CH3)2].

See also STEREOISOMERS.

Isomerase An enzyme-catalyzing transformation of a compound into its positional isomer. See also ISOMER.

Isoprene The five-carbon hydrocarbon molecule 2-methyl-1,3 butadiene. It is a recurring

structural unit of the terpenoid molecules, which are either linear or cyclic. There exists a very large number of terpenes and many are major components of essential plant oils. See also GTPases.

Isotope Refers to one of the several “varieties” of atoms that exist, of the same element, that differ from each other in the number of neutrons in the atom’s nucleus. For example, the element chlorine exists primarily in two forms (isotopes) in nature, with 18 neutrons (76% of the time) and with 20 neutrons (24% of the time). The chemical properties of isotopes of a given element are virtually identical. See also ATOMIC WEIGHT.

Isozymes (isoenzymes) Multiple forms of an enzyme that differ from each other in their substrate (substance acted upon) affinity, in their maximum activity, or in their regulatory properties. See also ENZYME, SUBSTRATE

(CHEMICAL), RIBOZYMES.

ISPM Acronym for International Standards for Pest Management. See also INTERNATIONAL

PLANT PROTECTION CONVENTION (IPPC).