GENETIC CODE,

the signaling molecules known as isoflavones, which attract Rhizobium japonicum bacteria. For the alfalfa plant, that is accomplished by the plant synthesizing luteolin molecules, which attract Sinorhizobium meliloti bacteria.

•Certain genes (called nod) within the relevant Rhizobium bacteria are expressed (resulting in the synthesis of specific chemical compounds).

•When the plant roots detect those chemical compounds, certain genes within those roots are expressed (resulting in the formation of nodules on those roots).

•The relevant Rhizobium bacteria move in and inhabit those plant root nodules, where the bacteria then “fix” nitrogen from the atmosphere; which converts that nitrogen into a chemical form (i.e., nitrates) that is available for use by

plants (as fertilizer/plant food). See also

RHIZOBIUM (bacteria), CHEMOTAXIS, SOY-

BEAN PLANT, ISOFLAVONES, GENISTEIN

(Gen), TRANSCRIPTION FACTORS, GENE,

GENE EXPRESSION, SIGNALING MOLECULE,

NITROGEN FIXATION, SYMBIOTIC, HEMAG-

GLUTININ (HA).

Non-Starch Polysaccharides Term — abbreviated NSP — that refers to polysaccharide molecules (in plant seeds) other than starch. These include arabinoxylans, pectins, beta glucans, and alpha galactosides (e.g., raffinose, stachyose, verbascose). See also

POLYSACCHARIDES, STACHYOSE.

Nonessential Amino Acids Amino acids of proteins that can be made (biochemically synthesized within the body) by humans and certain other vertebrate animals from simple chemical precursors (in contrast to the essential amino acids). These amino acids are thus not required in the diet (of humans and those other vertebrates). See also ESSENTIAL AMINO

ACIDS, AMINO ACID, PROTEIN.

Nonheme-Iron Proteins Proteins containing iron but no porphyrin groups (within which iron atoms are held) in their structure. See also HEME.

Nonpolar Group A hydrophobic (“water hating”) group on a molecule; usually hydrocarbon (composed of hydrogen and carbon atoms) in nature. These groups are more at

home in a nonpolar (oil-like) environment.

See also POLAR GROUP, AMPHIPATHIC MOLE-

CULES, AMPHOTERIC COMPOUND.

Nonsense Codon A triplet of nucleotides that does not code for an amino acid. Any one of three triplets (U-A-G, U-A-A, U-G-A) that cause termination of protein synthesis. U-A-G is known as amber and U-A-A is known as ochre. See also

CODON, TERMINATION CODON (SEQUENCE).

Nonsense Mutation A mutation that converts a codon that specifies an amino acid into one that does not specify any amino acid. A change in the nucleotide sequence of a codon that may result in the termination of a polypeptide chain. See also NONSENSE CODON,

GENETIC CODE, CODON.

Nontranscribed Spacer A region between transcription units in a tandem gene cluster.

See also TRANSCRIPTION, MESSENGER RNA

(mRNA), GENETIC CODE, GENE SPLICING, GENE.

North American Plant Protection Organization (NAPPO) One of the international SPS standard-setting organizations that develops plant health standards, guidelines, and recommendations (e.g., to prevent trans-

fer of a disease from one country to another). N Subsidiary to the International Plant Protec-

tion Convention (IPPC), it covers the countries of North America. Its secretariat is located in Nepean, Canada. See also INTER-

NATIONAL PLANT PROTECTION CONVENTION

(IPPC), EUROPEAN PLANT PROTECTION ORGANIZA-

TION (EPPO), SPS.

Northern Blotting A research test/methodology used to transfer RNA fragments from an agarose gel (e.g., following gel electrophoresis) to a filter paper without changing the relative positions of the RNA fragments (e.g., re electrophoresis separation grid). See

also RIBONUCLEIC ACID (RNA), GEL ELECTRO-

PHORESIS, AGAROSE, CHROMATOGRAPHY, FIELD

INVERSION GEL ELECTROPHORESIS.

Northern Corn Rootworm L a t i n n a m e

Diabrotica barberi. See also CORN ROOTWORM.

NOS Terminator A t e r m i n a t i o n c o d o n (sequence of DNA) frequently utilized in genetic engineering of plants to “terminate” expression of the inserted gene (i.e., to halt synthesis of desired protein in the plant, after the desired protein synthesis has occurred).

© 2002 by CRC Press LLC

The NOS terminator was originally extracted from the bacteria species Agrobacterium tumefaciens. See also TERMINATION CODON (terminator sequence), SEQUENCE (OF

A DNA MOLECULE), DEOXYRIBONUCLEIC ACID

(DNA), GENETIC ENGINEERING, EXPRESS, GENE,

PROTEIN, SYNTHESIZING (OF PROTEIN MOLECULE),

AGROBACTERIUM TUMEFACIENS, BACTERIA, CONTROL SEQUENCES.

NPTII See NPTII GENE.

NPTII Gene A marker gene that codes for (i.e., “causes manufacture of”) the enzyme neomycin phosphotransferase II, which can inactivate the antibiotic kanamycin. The NPTII gene is commonly utilized as a “marker gene” for genetically engineered plants. Neomycin phosphotransferase confers kanamycin resistance to cells expressing it (i.e., cells that contain the NPTII gene in addition to the other gene(s) inserted along with it), so those (engineered) cells will live in a laboratory vessel containing kanamycin.

See also GENE, MARKER (GENETIC MARKER),

CODING SEQUENCE, ENZYME, CELL, GENETIC ENGINEERING.

NSP See NON-STARCH POLYSACCHARIDES.

NNT An acronym for Nuclear Transfer. See also

NUCLEAR TRANSFER.

Nuclear DNA The DNA contained within the nucleus of a cell. See also DEOXYRIBONUCLEIC

ACID (DNA), CELL, GENOME, NUCLEUS, NUCLEAR

TRANSFER.

Nuclear Envelope See MEMBRANE (of a cell). Nuclear Matrix Proteins Protein molecules

present in cancerous cells, but not in normal (nonmutated) cells. See also PROTEIN, CELL,

MUTATION, MUTANT, MYRISTOYLATION, NEO-

PLASTIC GROWTH, “PARP”.

Nuclear Receptors Receptors in a cell’s outer membrane that serve to convey a “signal” from outside the cell all the way into the cell’s nucleus. See also RECEPTORS, SIGNALING,

SIGNAL TRANSDUCTION, NUCLEUS, G-PROTEINS ,

ENDOCYTOSIS, VAGINOSIS, CD4 PROTEIN, PROTEIN,

CELL, GENE, EXPRESS, GENE EXPRESSION, TRANSCRIPTION, TRANSCRIPTION FACTORS, POLYUNSATURATED FATTY ACIDS (PUFA), MEMBRANES (of a cell), PLASMA MEMBRANE.

Nuclear Transfer A method of cloning a living organism, in which that organism’s entire genetic information is conveyed via transfer

© 2002 by CRC Press LLC

of an (adult) cell nucleus into an unfertilized egg (from another animal of the same species) whose nucleus had previously been removed. This was the method utilized to produce “Dolly,” the first cloned sheep, in 1996. It is possible to also delete or substitute genes (e.g., brought in from another species) as part of the nuclear transfer process, so nuclear transfer can be utilized to produce transgenic organisms or “knock out” organisms. See also

CLONE (AN ORGANISM), CELL, NUCLEUS, GENOME,

NUCLEAR DNA, DEOXYRIBONUCLEIC ACID (DNA),

GENE, SPECIES, TRANSGENIC (organism), KNOCK

OUT (GENE), GENETIC ENGINEERING.

Nuclease An enzyme capable of hydrolyzing the internucleotide linkages of a nucleic acid (e.g., DNA or RNA). Nucleases present in cells tend to degrade (i.e., hydrolyze, cleave) artificially inserted DNA strands, making genetic targeting more difficult. See also

GENETIC TARGETING, HYDROLYSIS, DEOXYRIBO-

NUCLEIC ACID (DNA), RIBONUCLEIC ACID (RNA),

ANTISENSE (DNA SEQUENCE).

Nucleic Acid Probes See DNA PROBE, NUCLEIC

ACIDS, POLYMERASE CHAIN REACTION (PCR),

RAPID MICROBIAL DETECTION (RMD).

Nucleic Acids A nucleotide polymer. A large, chain-like molecule containing phosphate groups, sugar groups, and purine and pyrimidine bases; two types are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). The bases involved are adenine, guanine, cytosine, and thymine (uracil in RNA). Nucleic acids are either the specific (genetic) informational molecule (DNA), or act as agent (RNA) in causing that information to be expressed (e.g., as a protein). See also

NUCLEOTIDE, POLYMER, INFORMATIONAL MOLECULES, GENE, GENETIC CODE, DEOXYRIBONUCLEIC

ACID (DNA), RIBONUCLEIC ACID (RNA), EXPRESS,

EXTENSION (IN NUCLEIC ACIDS).

Nucleoid The compact body that contains the genome in a bacterium. See also GENOME.

Nucleolus A round, granular structure situated in the nucleus of eucaryotic cells. It is involved in rRNA (ribosomal RNA) synthesis and ribosome formation. See also RIBO-

SOMES, NUCLEUS.

Nucleophilic Group An electron-rich group with a strong tendency to donate electrons

to an electron-deficient nucleus. See also

POLAR GROUP, NONPOLAR GROUP.

Nucleoproteins Complexes made up of nucleic acid and protein. These two substances are apparently not linked by strong chemical bonds, but are held together by salt linkages and other weak bonds. Most viruses consist entirely of nucleoproteins, although some viruses also contain fatty substances. Nucleoproteins also occur in animal and plant cells and in bacteria. See also PROTEIN, VIRUS.

Nucleoside A hybrid molecule consisting of a purine (adenine, guanine) or pyrimidine (thymine, uracil, or cytosine) base covalently linked to a five-membered sugar ring (ribose in the case of RNA and deoxyribose in the case of DNA). See also NUCLEOTIDE.

Nucleoside Diphosphate Sugar A coenzymelike carrier of a sugar molecule functioning in the enzymatic synthesis of polysaccharides and sugar derivatives. See also

POLYSACCHARIDES.

Nucleosome Spherical particles composed of a special class of basic proteins (histone) in combination with DNA (146 bp of DNA are wrapped 1.75 times around a “core” of histone proteins). The particles are approximately 12.5 nm in diameter and are connected to each other by DNA filaments. Under an electron microscope they appear somewhat like a string of pearls. See also CHROMATIN,

HISTONES, PROTEIN, DEOXYRIBONUCLEIC ACID

(DNA), BASE PAIR (bp), NANOMETERS (nm).

Nucleotide An ester of a nucleoside and phosphoric acid. Nucleotides are nucleosides that have a phosphate group attached to one or more of the hydroxyl groups of the sugar (ribose or deoxyribose). In short, a nucleotide is a hybrid molecule consisting of a purine or pyrimidine base covalently linked to a fivemembered sugar ring which is covalently linked to a phosphate group. While (polymerized) nucleotides are the structural units of a nucleic acid, free nucleotides that are not an integral part of nucleic acids are also found in tissues and play important roles in the cell, e.g., ATP and cyclic AMP. See also ATP,

CYCLIC AMP, BASE (NUCLEOTIDE), NUCLEOSIDE,

NUCLEIC ACIDS, MESSENGER RNA (mRNA), RIBONU-

CLEIC ACID (RNA), DEOXYRIBONUCLEIC ACID

(DNA), TRANSVERSION.

Nucleus The usually spherical body with each living cell that contains its hereditary biological material (DNA, genes, chromosomes, etc.) and controls the cell’s life functions (e.g., metabolism, growth, and reproduction). The nucleus is a highly differentiated, relatively large organelle lying in the cytoplasm of the cell. The nucleus is surrounded by a (nuclear) membrane which is quite similar to the plasma (cell) membrane, except the nuclear membrane contains holes or pores. It is characterized by its high content of chromatin, which contains most of the cell’s DNA. That chromatin is normally (when cell is not in process of dividing) distributed throughout the nucleus in a diffuse manner. See also GENOME, CELL,

GENE, GENETIC CODE, RNA, HEREDITY, DEOXY-

RIBONUCLEIC ACID (DNA), CHROMOSOMES, MEIO-

S I S , N U C L E A R T R A N S F E R, M E T A B O L I S M ,

CHROMATIDS, CHROMATIN, PLASMA MEMBRANE,

ORGANELLES, NUCLEAR RECEPTORS.

Nutraceuticals Coined in 1989 by Stephen DeFelice, this term is used to refer to either a food or portion of food (a vitamin, essential amino acid, etc.) that possesses medical or

health benefits (to the organism that con- N sumes that nutraceutical). For example,

saponins (present in beans, spinach, tomatoes, potatoes, alfalfa, clover, etc.) possess some cancer-prevention properties. Also sometimes called pharmafoods, functional foods, or designer foods, these are food products that have been designed to contain specific concentrations and/or proportions of certain nutrients (vitamins, amino acids, etc.) that are critical for good health. See also

ESSENTIAL AMINO ACIDS, AMINO ACID, VITAMIN,

FOOD GOOD MANUFACTURING PRACTICE (FGMP),

SAPONINS, ESSENTIAL NUTRIENTS, PHYTOCHEMI-

CALS, ANTIOXIDANTS, ISOFLAVONES, GENISTEIN

(Gen), RESVERATROL, PHYTOSTEROLS, BETA CAR-

OTENE, LYCOPENE, CAROTENOIDS, LUTEIN,

ANTHOCYANINS, VITAMIN E, XANTHOPHYLLS, STE-

ROLS, SITOSTEROLS, SITOSTANOLS, ELLAGIC ACID,

ALICIN, PROANTHOCYANIDINS, POLYPHENOLS,

ZEAXANTHIN, PHYTO-MANUFACTURING.

Nutriceuticals See NUTRACEUTICALS.

Nutricines See NUTRACEUTICALS.

Nutrient Enhanced™ A phrase that is now a trademark of Garst Seed Company; it refers

© 2002 by CRC Press LLC

to plants that have been modified to possess	HIGH-OIL CORN, PROTEIN, GENETIC ENGINEERING,
novel traits that make those plants more eco-	HIGH-LYSINE CORN, HIGH-METHIONINE CORN,
nomically valuable for nutritional uses (e.g.,	PLANT’S NOVEL TRAIT (PNT), HIGH-PHYTASE
higher-than-normal protein content in certain	CORN AND SOYBEANS.
feedgrains). See also VALUE-ENHANCED GRAINS,	Nutrigenomics See PHARMACOGENOMICS.

N

© 2002 by CRC Press LLC