suitability of resultant soybean raw materials for manufacture of human foods in some countries.

Prevention of the reactions that create the “beany” flavor can be accomplished via heat denaturation (of lipoxygenases present in the soybeans) or via creation of soybeans that do not contain any lipoxygenase enzymes (known as “LOX null” soybeans). Lipoxygenase enzymes also catalyze a reaction in which certain volatile chemicals are produced that inhibit growth of any Aspergillus flavus fungus. See also ENZYME, SOYBEAN

PLANT, LOX NULL SOYBEANS, LOX-1, LOX-2,

LOX- 3.

Lipoxygenase Null See LOX NULL SOYBEANS,

LIPOXYGENASE (LOX).

Listeria monocytogenes Refers to the “family” (numerous strains) of Listeria monocytogenes bacteria, that can grow in many different foodstuffs (e.g., meats) under specific conditions, and can cause food poisoning (Listeriosis) in humans who subsequently consume those foodstuffs. When consumed by humans, certain strains/serotypes of Listeria monocytogenes can cause fever, severe headaches, stiffness, nausea, diarrhea, and possibly miscarriages in pregnant women. As of January 19, 2001, all meat processed in the U.S. is required to be tested for the presence of Listeria monocytogenes. See

also BACTERIA, STRAIN, SEROTYPES, ENTERO-

TOXIN, BACTERIOCINS, CADHERINS.

Living Modified Organism (LMO) See GMO. LMO (Living modified organism) See GMO.

Loci The plural of locus. See also LOCUS. Locus The position of a gene on a chromo-

some. See also GENE, CHROMOSOMES.

Loop A single-stranded region at the end of a hairpin in RNA (or single-stranded DNA). It corresponds to the sequence between inverted repeats in duplex DNA. See also

RIBONUCLEIC ACID (RNA), DEOXYRIBONUCLEIC

ACID (DNA), SEQUENCE (OF A DNA MOLECULE).

LOSBM Low-oligosaccharide soybean meal.

See also LOW-STACHYOSE SOYBEANS, SOYBEAN

PLANT.

Low-Density Lipoproteins (LDLP) So-called “bad” cholesterol (i.e., LDL cholesterol), which carries cholesterol molecules from the digestive system (e.g., intestine) to body

cells and can sometimes clog arteries over time (a disease called atherosclerosis, or coronary heart disease). Since cholesterol does not dissolve in water (which constitutes most of the volume of blood), the body makes LDL cholesterol (derived from the digestion of fatty foods) into little “packages” surrounded by a hydrophilic (“water loving”) protein. That protein “wrapper” is known as apolipoprotein B-100, or apo B-100, and it enables LDL cholesterol to be transported in the bloodstream because the apolipoprotein B-100 is attracted to water molecules in the blood. Part of the apolipoprotein B-100 molecule also will bind to special LDLP receptor molecules in the liver, which then clears those (bound) cholesterol packages out of the body as part of regular liver functions.

See also HIGH-DENSITY LIPOPROTEINS (HDLPs),
HYDROPHILIC, RECEPTORS, PROTEIN, SITOSTANOL,
ISOFLAVONES, WATER SOLUBLE FIBER, CHOLES-
TEROL, CORONARY HEART DISEASE (CHD), APO-
LIPOPROTEINS, VERY LOW-DENSITY LIPOPROTEINS		L
(VLDL).
Low-Linolenic Oil Soybeans Soybeans from
soybean (Glycine max) plant varieties which
have been bred specifically to produce soy-
beans bearing oil that contains less than 4%
linolenic acid, instead of the typical 8% lino-
lenic acid content of soybean oil produced
from traditional varieties of soybeans. Low-
linolenic soybean oil would tend to have
greater flavor stability (especially at elevated
temperatures utilized in frying foods) than
soybean oil from traditional varieties of soy-
beans. See also SOYBEAN PLANT, SOYBEAN OIL,
FATTY ACID, LINOLENIC ACID, POLYUNSATURATED
FATTY ACIDS (PUFA).
Low-lipoxygenase Soybeans See	L O X -N U L L
SOYBEANS.

Low-Phytate Corn Developed in the U.S. during the 1990s, these are corn (maize) hybrids possessing the Lpa1 gene, the Lpa2 gene, or the HAP (highly available phosphorous) gene (which was discovered by Victor Raboy). That gene causes corn (maize) hybrids possessing it to produce much less phytate than the 0.15% typically present in traditional varieties of corn (maize).

Because phytate is not digestible in humans and other monogastric animals

© 2002 by CRC Press LLC

(swine, poultry, etc.), substituting lowphytate corn in place of traditional corn varieties in those animals’ diets helps lessen adverse environmental impact of animal feeding (e.g., phosphorous emissions in excess of annual cropland requirements). Swine fed a diet in which traditional corn (maize) varieties have been replaced by lowphytate corn (maize) produce up to 30% less phosphorous in their manure, thereby lessening the phosphorous impact of those swine on the environment. Humans consuming a diet based heavily on corn/maize (e.g., tortillas) absorb 50% more iron when traditional corn varieties are replaced by lowphytate corn varieties. That is because the phytate (inositol hexaphosphate) molecule “binds”/chelates iron (and some other metals) within the digestive system and prevents their absorption into the body. See also CORN,

PHYTATE, HIGH-PHYTASE CORN, PHYTASE,

VALUE-ENHANCED GRAINS, HIGHLY-AVAILABLE

LPHOSPHOROUS (HAP) GENE, CHELATION, CHELATING AGENT, IRON DEFICIENCY ANEMIA (IDA).

Low-Phytate Soybeans Developed in the U.S. during the 1990s, these are soybean varieties possessing less than 0.30% (of total soybean weight) phytate, vs. the typical 0.45% phytate content of soybeans from traditional soybean varieties.

Because phytate is not digestible in humans and other monogastric animals (swine poultry, etc.), substituting lowphytate soybeans in place of traditional soybean varieties in those animals’ diets helps to lessen adverse environmental impact of animal feeding (e.g., manure phosphorous emissions in excess of cropland requirements). Swine fed a diet in which traditional soybean varieties have been replaced by lowphytate soybeans produce up to 20% less phosphorous in their manure, thereby lessening the phosphorous impact of those swine on the environment. Due to the fact that the amino acids lysine, methionine, cysteine, arginine, and threonine all become more “bioavailable” (i.e., available for the animal to build its body tissue, or otherwise utilize) in a low-phytate diet, low-phytate diets also help reduce exess nitrogen emissions. See

also SOYBEAN PLANT, PHYTATE, LOW-PHYTATE

CORN, HIGH-PHYTASE CORN/SOYBEANS, LYSINE,

CYSTEINE, METHIONINE, ARGININE, THREONINE,

DEAMINATION.

Low-Stachyose Soybeans T h o s e s o y b e a n varieties that contain lower than 1% levels of the relatively indigestible stachyose carbohydrate (and thus higher levels of easily digestible other nutrients) than traditional varieties of soybeans (which typically contain 1.4–4.1% stachyose in traditional soybean varieties). Compared to traditional varieties of soybeans, low-stachyose soybeans have approximately 10% more metabolizable (i.e., useable by animals) energy content and a 3% increase in amino acid digestibility. Low-stachyose soybeans are particularly useful for feeding of monogastric animals (swine, poultry, etc.), since their single stomach cannot digest stachyose. Thus, stachyose tends to “ferment” (promote excess bacterial growth) in their intestines, causing them to feel prematurely full. See

also STACHYOSE, CARBOHYDRATES (SACCHARIDES), VALUE-ENHANCED GRAINS, SOYBEAN PLANT, HIGH-SUCROSE SOYBEANS, DIGESTION

(WITHIN ORGANISMS), METABOLISM.

Low-Tillage Crop Production A methodology of crop production in which the farmer utilizes a minimum of mechanical cultivation (i.e., only two to four passes over the field with tillage equipment instead of the conventional five passes per year utilized for traditional crop production). This reduced mechanical tillage leaves more carbon in the (less disturbed) soil, leaves more earthworms (Eisenia foetida) per cubic foot or per cubic meter living in the topsoil, and reduces soil compaction (i.e., the reduction in interstitial spaces between individual soil particles); thereby increasing the fertility of “low till” farm fields.

The plant residue remaining on the field’s surface helps control weeds and reduce soil erosion; it also provides sites for insects to shelter and reproduce, leading to a need for increased pest insect control via methods such as inserting a Bacillus thuringiensis

(B.t.) gene into certain crop plants. But if a farmer needs to apply synthetic chemical pesticides, the plant residue remaining on the field’s surface helps cause breakdown (into substances such as carbon dioxide and

© 2002 by CRC Press LLC

water) of those pesticides. That is because that plant residue helps to retain moisture in the field-surface environment, thereby enhancing growth of the types of microorganisms that help break down pesticides. See

also NO-TILLAGE CROP PRODUCTION, GLOMALIN,

EARTHWORMS, MICROORGANISMS, INTEGRATED

PEST MANAGEMENT (IPM), CORN, SOYBEAN

PLANT, BACILLUS THURINGIENSIS (B.t.), GENE,

GENETIC ENGINEERING, EUROPEAN CORN BORER

(ECB), HELICOVERPA ZEA (H. ZEA), CORN ROOT-

WORM, COLD HARDENING.

LOX Null Soybeans Refers to soybeans that do not contain any of the three lipoxygenase enzymes (thus, they result in a “null” test reading). See also LIPOXYGENASE (LOX), LOX- 1,

LOX-2, LOX- 3, SOYBEAN PLANT, ENZYME.

LOX-1 One of the isozymes (enzyme molecule variations) of the lipoxygenase (LOX) enzyme “family.” See also LIPOXYGENASE

(LOX), ISOZYMES (ISOENZYMES).

LOX-2 One of the isozymes (enzyme molecule variations) of the lipoxygenase (LOX) enzyme “family.” See also LIPOXYGENASE

(LOX), ISOZYMES (ISOENZYMES).

LOX-3 One of the isozymes (enzyme molecule variations) of the lipoxygenase (LOX) enzyme “family.” See also LIPOXYGENASE

(LOX), ISOZYMES (ISOENZYMES).

LPAAT Protein A protein consisting of lysophosphatidic acid acyl transferase (enzyme), which (when present in a plant) causes production of triglycerides (in the seeds) possessing saturated fatty acids in the “middle position” of the triglycerides’ molecular (glycerol) “backbone.” For example, canola (rapeseed) plants genetically engineered to contain LPAAT protein are able to produce high levels of saturated fatty acids (including laurate) in their oil. See also PROTEIN, LAU-

RATE, ENZYME, TRIGLYCERIDES, SATURATED

F A T T Y A C I D S , M O N O U N S A T U R A T E D F A T S ,

CANOLA, GENETIC ENGINEERING.

LPE See LYSOPHOSPHATIDYLETHANOLAMINE.

LPS See ENDOTOXIN.

Luciferase Refers to a group of enzymes that can catalyze a chemical reaction that results in the production of light (i.e., bioluminescense) within certain living oganisms. For example, the common firefly is able to emit light from its tail (photophores) via

luciferase-catalyzed bioluminescence. The ocean jellyfish known as the sea pansy (Renilla reniformis) is able to emit light via similar use of a slightly different luciferase molecule. See also B I O L U M I N E S C E N C E ,

ENZYME, CATALYST, ORGANISM, NITRIC OXIDE.

Luciferin See BIOLUMINESCENCE.

Lumen The interior (opening through which blood flows); e.g., within a blood vessel. See

also ENDOTHELIUM.

	Luminesce See BIOLUMINESCENCE.
	Luminescence See BIOLUMINESCENCE.
	Luminescent Assays Refers to assays (i.e.,
	tests/test techniques) which detect or mea-
	sure the presence of a specific substance
	(e.g., bacteria ATP on surfaces in a slaugh-
	terhouse) and the efficacy (i.e., effective-
	ness) of a specific substance via the enzyme
	(e.g., luciferase)-catalyzed production of
	light. For example, one (rapid) luminescent
	assay utilizes two chemical reagents which
	first break down bacteria cell membranes,
		L
	then cause ATP from those broken-open
	cells to luminesce. Subsequent measurement
	of that light is the assay’s proof (e.g., that
	bacteria had been present on the tested sur-
	face in a slaughterhouse). See also ASSAY,
	BIOLUMINESCENCE, ENZYME, BACTERIA, PLASMA
	MEMBRANE, ADENOSINE TRIPHOSPHATE (ATP).
	Lupus An autoimmune disease of the body, in
	which anti-DNA antibodies bind to DNA.
	The resulting complexes (of DNA and anti-
	bodies) travel to the kidneys via the blood-
	stream, and become lodged in the kidneys,
	where they cause inflammatory reactions
	(that can lead to kidney failure). Sometimes
	joints, blood vessels, bone marrow, and the
	liver are also damaged by this disease. See
	also ANTIBODY, DEOXYRIBONUCLEIC ACID (DNA),
	AUTOIMMUNE DISEASE, SUPERANTIGENS.
	Lupus Erythematosus See LUPUS.
	Lutein A carotenoid (i.e., “light harvesting”
	compound utilized in photosynthesis) that is
	naturally produced in carrots, summer squash,
	broccoli, dark lettuce, and green peas. Lutein
	is a phytochemical/nutraceutical conducive
	to good eye health, and regular consumption
	of large amounts of lutein has been shown
	to reduce the risk of the disease age-related
	macular degeneration, a leading cause of
	blindness in elderly people. Research

© 2002 by CRC Press LLC

CAROTENOIDS,

indicates that consumption of lutein by humans also reduces risk of prostate cancer and breast cancer. See also PHYTOCHEMICALS,

NUTRACEUTICALS, PHOTOSYNTHE-

SIS.

Luteinizing Hormone (LH) A reproductive hormone that acts upon the ovaries to stimulate ovulation. It is secreted by the pituitary

gland. See also HORMONE, PITUITARY GLAND,

ENDOCRINE HORMONES, ESTROGEN.

Luteolin See NODULATION.

Lycopene An antioxidant carotenoid (“light harvesting” pigment utilized by plants in the photosynthesis process) that is a naturally occurring phytochemical in tomatoes, watermelon, guava, pink grapefruit (and some other fruits). Consumption of significant amounts of lycopene by humans causes an increase in the concentration of lycopene in the blood plasma. Lycopene is a natural constituent of blood plasma and certain tissues in the human body, but it must be consumed

Lin the diet, because the human body does not synthesize (manufacture) lycopene. Consumption of lycopene by humans has been linked to a reduction in atherosclerosis, coronary heart disease, some cancers (e.g., prostate cancer), and inhibition of oxidation of low-density lipoproteins (LDLP).

Lycopene is also converted (in some instances) into alpha-carotene and/or betacarotene. Because beta-carotene is processed into vitamin A by the human body, consumption of this phytochemical can help prevent human diseases (e.g., in developing countries) that result from deficiency of vitamin A, e.g.: coronary heart disease; certain cancers (cancer of prostate, lung, etc.), childhood blindness, macular degeneration (a leading cause of blindness in older people), and various childhood diseases that can cause death due to a weakened immune sys-

tem. See also PHYTOCHEMICALS, NUTRACEUTICALS, CANCER, ANTIOXIDANTS, CAROTENOIDS,

CORONARY HEART DISEASE (CHD), PLASMA,

ATHEROSCLEROSIS, PROSTATE-SPECIFIC ANTIGEN

(PSA), TOMATO, BETA CAROTENE, VITAMIN,

LUTEIN, PHOTOSYNTHESIS, LOW-DENSITY LIPO-

PROTEINS (LDLP).

Lymphocyte A type of cell found in the blood, spleen, lymph nodes, etc. of higher animals. They are formed very early in fetal life, arising in the liver by the sixth week of human gestation. There exist two subclasses of lymphocytes: B lymphocytes and T lymphocytes. B lymphocytes make antibodies (immunoglobins) of which there are five classes: IgM, IgA, IgG, IgD, and IgE. The antibodies circulate in the bloodstream. T lymphocytes recognize and reject foreign tissue, modulate B cell activity, kill tumor cells, and kill host cells infected with virus. T-lymphocytes are also called T cells. See

also B LYMPHOCYTES, T CELLS, ANTIBODY,

HELPER T CELLS (T4 CELLS), BLAST CELL, CYTO-

TOXIC T CELLS, ANTIGEN.

Lymphokines Peptides and proteins secreted by (immune system response) stimulated T cells. These hormone-like (peptide and protein) molecules direct the movements and activities of other cells in the immune system. Some examples of lymphokines are interleukin-1, interleukin-2, tumor necrosis factor (TNF), gamma interferon, colony stimulating factors, macrophage chemotactic factor, and lymphocyte growth factor. The suffix “-kine” comes from the Greek word kinesis, meaning movement.

Lyochrome See FLAVIN.

Lyophilization The process of removing water from a frozen biomaterial (e.g., a microbial culture or an aqueous protein solution) via application of a vacuum. It is a drying method for long-term preservation of proteins in the solid state, and for long-term storage of live microbial cultures. See also

CULTURE, PROTEIN.

Lyse To rupture a membrane (cell). The act of lysis (rupturing a membrane). See also LYSIS.

Lysine (lys) An essential amino acid that can be obtained from many proteins by hydrolysis (i.e., cutting apart the protein molecule). See

also ESSENTIAL AMINO ACIDS, PROTEIN, OPAGUE- 2,

PHOTORHABDUS LUMINESCENS, HYDROLYSIS.

Lysis The process of cell disintegration; membrane rupturing; breaking up of the cell wall.

See also CYTOLYSIS, CELL, LYSOZYME, MEM-

BRANE TRANSPORT, BIOCIDE.

© 2002 by CRC Press LLC