Biotechnology

Herbicide Resistance See
HERBICIDE
-
TOLERANT
CROP
.
Herbicide-Resistant Crop See
HERBICIDE
-
TOL-
ERANT CROP
.
Herbicide-Tolerant Crop Crop plants, culti-
vated by man, that have been altered to be
able to survive application(s) of one or more
herbicides by the incorporation of certain
gene(s), via either genetic engineering, natu-
ral mutation, or mutation breeding (i.e., soak-
ing seeds in mutation-causing chemicals, or
bombardment of seeds with ionizing radia-
tion, to cause random genetic mutations, fol-
lowed by selection of the particular mutation
in which herbicide-tolerance occurs).
Because it has been utilized for decades,
most relevant national laws consider mutation
breeding to be one of the so-called “traditional
plant breeding” techniques. For example,
European laws that require special labeling of
food products containing genetically engi-
neered (via rDNA) crops do not require such
special labeling for food products that contain
crops created via mutation breeding. Several
crops (soybean, canola, cotton, etc.) are made
tolerant to glyphosate- or sulfosate-containing
© 2002 by CRC Press LLC

H
herbicides by the insertion (via genetic engi-
neering techniques) of the aroA transgene
(cassette) for CP4 EPSPS. Corn (maize) is
made tolerant to glyphosate-containing herbi-
cides by insertion (via genetic engineering
techniques) of the mEPSPS or GA21 trans-
gene (cassette). Some soybean varieties are
made tolerant to sulfonylurea-based herbi-
cides by adding (via traditional breeding
methods) the ALS gene (which confers the
sulfonylurea-tolerance trait). Corn (maize)
and rice (Oryza sativa) are made tolerant to
imidazolinone-containing herbicides by add-
ing (via traditional breeding techniques) the
imidazolinone-tolerance trait. That trait is
imparted by the T-Gene, IT-Gene, or the IR-
Gene. See also 
GENE
,
GENETIC ENGINEERING
,
CAS-
SETTE
,
TRANSGENIC
,
DEOXYRIBONUCLEIC ACID
(
DNA
),
r
DNA
,
EPSP SYNTHASE
,
GLYPHOSATE OXI-
DASE
,
PAT GENE
,
BAR GENE
,
GENETICS
,
GLYPHO-
SATE
,
GA
21
,
SULFOSATE
,
ALS GENE
,
EPSP SYNTHASE
,
CP
4
EPSPS
,
CHLOROPLAST TRANSIT PEPTIDE
  (
CTP
),
ACURON
™
GENE
,
TRANSGENE
,
TRAIT
,
CANOLA
,
SOYBEAN PLANT
,
CORN
,
MUTATION BREEDING
,
TRA-
DITIONAL BREEDING METHODS
.
Heredity Transfer of genetic information from
parent cells to progeny. See also 
INFORMA-
TIONAL MOLECULES
,
GENE
,
GENETIC CODE
,
GENOME
,
GENETICS
,
GENOTYPE
,
DEOXYRIBO-
NUCLEIC ACID
  (
DNA
),
HERITABILITY
,
QUANTITA-
TIVE TRAIT LOCI
 (
QTL
).
Heritability The fraction of variation (of an
individual’s given trait) that is due to genet-
ics. For example, if a pig’s trait (e.g., weight
at birth) is 30% heritable, that means that
30% of the (birthweight) difference between
that individual pig and its (statistically rep-
resentative) group of contemporaries (pigs)
is due to genetics. The other 70% would be
due to factors such as nutrition of the mother
during pregnancy, etc. See also 
HEREDITY
,
TRAIT
,
GENETICS
,
INFORMATIONAL MOLECULES
,
GENE
,
GENETIC CODE
,
GENOME
,
GENOTYPE
,
DEOXYRIBONUCLEIC ACID
  (
DNA
),
QUANTITATIVE
TRAIT LOCI
 (
QTL
).
Hetero- A chemical nomenclature prefix
meaning “different.” For example, a hetero-
cyclic compound is one with a (ring) structure
made up of more than one kind of atom. A
heterokaryon refers to a cell containing nuclei
of different species. See also 
HETEROCYCLIC
,
HETERODUPLEX
,
HETEROGENEOUS
  (
CATALYSIS
),
HETEROGENEOUS
  (
CHEMICAL REACTION
),
HETERO-
GENEOUS
  (
MIXTURE
),
HETEROKARYON
,
HETEROLO-
GOUS PROTEINS
,
HETEROLOGOUS DNA
,
HETEROLOGY
,
HETEROSIS
,
HETEROTROPH
,
HETEROZYGOTE
.
Heterocyclic See
HETERO
-.
Heteroduplex A DNA molecule, the two
strands of which come from different indi-
viduals so that there may be some base pairs
or blocks of base pairs that do not match.
Can arise from mutation, recombination, or
by annealing DNA single strands in vitro.
See also 
DEOXYRIBONUCLEIC ACID
 (
DNA
).
Heterogeneous (catalysis) Catalysis occur-
ring at a phase boundary, usually a solid-
fluid interface. See also 
HETERO-
,
HETEROGE-
NEOUS
 (
MIXTURE
),
CATALYST
.
Heterogeneous (chemical reaction) A chem-
ical reaction in which the reactants are of
different phases: for example, gas with liq-
uid, liquid with solid, or a solid catalyst with
liquid or gaseous reactants. See also 
HETERO-
,
HETEROGENEOUS
 (
CATALYSIS
),
CATALYST
.
Heterogeneous (mixture) One that consists of
two or more phases such as liquid-vapor, or
liquid-vapor-solid. See also 
HETERO-
.
Heterokaryon A fused cell containing nuclei
of different species. See also 
NUCLEOID
.
Heterologous DNA Refers to a DNA mole-
cule in which each of the (double) strands is
from different sources (e.g., different spe-
cies). See also 
DEOXYRIBONUCLEIC ACID
 (
DNA
),
HETERO-
,
SPECIES
.
Heterologous Proteins Those proteins pro-
duced by an organism that is not the wild
type source of those proteins. For example,
bacteria have been genetically engineered to
produce human growth hormone and bovine
(i.e., cow) somatotropin. See also 
PROTEIN
,
WILD TYPE
,
GROWTH HORMONE
  (
GH
),
BOVINE
SOMATOTROPIN
 (
BST
),
HOMOLOGOUS PROTEIN
.
Heterology A sequence of amino acids in two
or more proteins that are not identical to each
other. See also 
AMINO ACID
,
PROTEIN
,
HOMOLOGY
.
Heterosis Also known as “hybrid vigor.” See
also
F
1
HYBRIDS
.
Heterotroph An organism that obtains nour-
ishment from the ingestion and breakdown
of organic matter.
© 2002 by CRC Press LLC

H
Heterozygote An individual organism with
different alleles at one or more particular
loci. See also 
ALLELE
.
Hexadecyltrimethylammonium Bromide
(CTAB) A solvent that is widely utilized to
dissolve plant DNA samples (e.g., when a
scientist wants to sequence that sample of
plant DNA). CTAB solvent helps the scien-
tist to separate out contaminants that are
commonly present in samples from plant tis-
sues (polysaccharides, quinones, etc.)
because DNA molecules are much more sol-
uble in CTAB than are the contaminant mol-
ecules. See also 
DEOXYRIBONUCLEIC ACID
 (
DNA
),
POLYSACCHARIDES
,
SEQUENCING
 (
OF DNA MOLE-
CULES
),
SDS
.
Hexose See
GLUCOSE
 (
GL
c
).
HF Cleavage A research process in which
hydrofluoric acid is used to sequentially
remove side-chain protective groups from
peptide chains. Also used to remove the resin
support from peptides that have been pre-
pared via solid-phase peptide synthesis. The
HF cleavage reaction is a temperature-
dependent process. See also 
PROSTHETIC
GROUP
,
SYNTHESIZING
 (
OF PROTEINS
).
High-Amylose Corn Refers to those corn
(maize) hybrids that produce kernels in
which the starch that is contained within
those kernels is at least 50% amylose, versus
the average of 24–28% amylose in tradi-
tional corn starch. See also 
CORN
,
STARCH
,
AMYLOSE
.
High-Density Lipoproteins (HDLPs) So-
called “good” cholesterol, it consists of lipo-
proteins that can help move excess low-den-
sity lipoproteins (“bad” cholesterol, which
can clog arteries) out of the human body by
binding to the low-density lipoproteins (also
known as LDL cholesterol) in the blood and
then attaching to special LDLP receptor mol-
ecules in the liver. The liver then clears those
(bound) low-density lipoproteins out of the
body as a part of regular liver functions.
Studies have shown that humans having
high bloodstream levels of HDLPs will off-
set high levels of LDLPs (e.g., the HDLPs
can still help lower the risk of developing
coronary heart disease). Since cholesterol
does not dissolve in water (which constitutes
most of the volume of blood), the body
makes HDL cholesterol into little “pack-
ages” surrounded by a hydrophilic (“water
loving”) protein. That protein “wrapper” is
known as apolipoprotein A-1, or apo A-1,
and it enables HDL cholesterol to be trans-
ported in the bloodstream because the apo-
lipoprotein A-1 is attracted to water
molecules in the blood. See also 
LOW
-
DENSITY
LIPOPROTEINS
  (
LDLP
),
RECEPTORS
,
APOLIPOPRO-
TEINS
,
WATER SOLUBLE FIBER
,
CHOLESTEROL
,
CORONARY HEART DISEASE
 (
CHD
).
High-Glutenin Wheat See
GLUTEN
.
High-Isoflavone Soybeans Developed in the
U.S. in the 1990s, these are soybean varieties
which contain greater content of isoflavones
than do traditional soybean varieties (i.e.,
isoflavones constitute 0.15–0.3% of a tradi-
tional variety soybean’s dry weight). Con-
sumption of isoflavones helps to reduce the
blood level of low-density lipoproteins (“bad
cholesterol”) in humans. A human diet con-
taining a large amount of isoflavones helps
prevent osteoporosis, causes reduced risk of
certain cancers (breast cancer, prostate can-
cer, endometrial cancer, etc.), and decreases
risk of prostate enlargement. See also 
ISOFLA-
VONES
,
SOYBEAN PLANT
,
CHOLESTEROL
,
CANCER
,
PROSTATE
-
SPECIFIC ANTIGEN
 (
PSA
),
LOW
-
DENSITY
LIPOPROTEINS
 (
LDLP
),
OSTEOPOROSIS
.
High-Lactoferrin Rice Refers to rice plants
(Oryza sativa) which have been genetically
engineered to produce substantial amounts
of lactoferrin in the grain they yield. Lacto-
ferrin is a compound that is naturally pro-
duced in human breast milk. Consumption
of lactoferrin by infants helps to strengthen
their immune system. Consumption of lacto-
ferrin (e.g., from genetically engineered
rice) by older humans helps their immune
systems to resist some infectious diseases.
Lactoferrin “binds” free iron (e.g., in body
fluids), thereby denying that iron to patho-
genic bacteria (which need free iron to
grow/infect). Lactoferrin also promotes
intestinal cell growth in humans. See also
GENETIC ENGINEERING
,
PATHOGEN
,
BACTERIA
,
VALUE
-
ENHANCED GRAINS
,
GROWTH
  (
MICRO-
BIAL
),
CELL
.
High-Laurate Canola Refers to canola (Bras-
sica napus/campesris) varieties genetically
engineered (e.g., via insertion of gene for
© 2002 by CRC Press LLC

H
lauroyl-ACP thioesterase) to produce at least
40% laurate (lauric acid) in their oil (in
seed). See also 
LAURATE
,
CANOLA
,
GENETIC
ENGINEERING
,
FATTY ACID
,
LAUROYL
-
ACP
THIOESTERASE
,
VALUE
-
ENHANCED GRAINS
.
High-Lysine Corn Developed in the U.S. in
the mid-1960s, these were initially corn
(maize) varieties possessing the opague-2
gene. The opague-2 gene causes such corn
to contain 0.30–0.55% lysine (i.e., 50–80%
more than traditional No. 2 yellow corn).
Other genes have subsequently been discov-
ered that, when inserted into the corn/maize
genome (e.g., via genetic engineering tech-
niques), cause production of larger amounts
of lysine than in traditional corn/maize vari-
eties. High-lysine corn is particularly useful
for feeding of swine, since traditional No. 2
yellow corn does not contain enough lysine
for optimal swine growth. See also 
CORN
,
LYSINE
  (
lys
),
GENE
,
OPAGUE
-2
,
GENETIC ENGI-
NEERING
,
GENOME
,
VALUE
-
ENHANCED GRAINS
,
“
IDEAL PROTEIN
”
CONCEPT
,
MAL
  (
MULTIPLE
ALEURONE LAYER
)
GENE
.
High-Methionine Corn Developed in the
U.S. in the mid-1960s, these were initially
corn (maize) varieties possessing the floury-
2 gene. The floury-2 gene causes such corn
to contain slightly higher levels of methion-
ine than traditional No. 2 yellow corn. Other
genes have subsequently been discovered
that, when inserted into corn/maize genome
(e.g., via genetic engineering techniques),
cause production of larger amounts of
methionine than in traditional corn/maize
varieties. High-methionine corn is particu-
larly useful for feeding of poultry, since tra-
ditional No. 2 yellow corn does not contain
enough methionine for optimal poultry
(especially feather) growth. See also
METHIONINE
  (
met
),
CORN
,
FLOURY
-2
,
GENE
,
G E N O M E
,
G E N E T I C E N G I N E E R I N G
,
V A L U E
-
ENHANCED GRAINS
,
OPAGUE
-2
, “
IDEAL PROTEIN
”
CONCEPT
,
MAL
  (
MULTIPLE ALEURONE LAYER
)
GENE
.
High-Oil Corn Conceived in 1896 at the Uni-
versity of Illinois in the U.S., high-oil corn
(HOC) is defined to be corn (maize) possess-
ing a kernel oil content of 5.8% or greater.
Traditional No. 2 yellow corn varieties tend
to contain 4.5% or less oil content. See also
VALUE
-
ENHANCED GRAINS
,
CORN
,
CHEMOMETRICS
.
High-Oleic Oil Soybeans S o y b e a n s   f r o m
plants which have been genetically engi-
neered to produce soybeans bearing oil that
contains more than 70% oleic acid, instead
of the typical 24% oleic acid content of soy-
bean oil produced from traditional varieties
of soybeans. Cosuppression, via inserted
gene for 
∆ 12 desaturase (an enzyme that
normally converts oleic acid to linoleic acid
as part of the oil creation process in tradi-
tional varieties of soybean plants), causes the
higher than traditional amount of oleic acid
in the soybean oil. High-oleic soybean oil
would tend to have greater oxidative stability
(especially at elevated temperatures) than
soybean oil from traditional varieties of soy-
beans. Because of that, nuts that were fried
in high-oleic oil have been shown to possess
a longer shelf life than nuts fried in tradi-
tional oils. A human diet containing a large
amount of oleic acid causes lower blood cho-
lesterol level, and thus lower risk of coronary
heart disease (CHD). See also 
SOYBEAN
PLANT
,
SOYBEAN OIL
,
FATTY ACID
,
OLEIC ACID
,
MONOUNSATURATED FATS
,
GENETIC ENGINEER-
ING
,
DELTA
12
DESATURASE
,
CHOLESTEROL
,
COR-
ONARY HEART DISEASE
  (
CHD
),
PALMITIC ACID
,
COSUPPRESSION
,
ENZYME
,
LINOLEIC ACID
.
High-Phytase Corn and Soybeans Crop plants
that have been genetically engineered to con-
tain in their grain/seed high(er) levels of the
enzyme phytase (which aids digestion and
absorption of phosphate in that grain/seed).
High-phytase grains or oilseeds are particu-
larly useful for the feeding of swine and
poultry, since traditional No. 2 yellow corn
(maize) or traditional soybean varieties do
not contain phytase in amounts needed for
complete digestion/absorption of phosphate
naturally contained in those traditional
soybeans and corn (maize) in the form of
phytate. See also 
PHYTASE
,
ENZYME
,
PHYTATE
,
VALUE
-
ENHANCED GRAINS
,
LOW
-
PHYTATE CORN
,
LOW
-
PHYTATE SOYBEANS
.
High-Stearate Canola Canola varieties which
have been genetically engineered so their
seeds contain a higher percentage of stearate
(also called stearic acid) in the canola oil
than the typical stearate content in canola oil
© 2002 by CRC Press LLC

H
produced from traditional canola varieties.
Cosuppression, via inserted gene for
D
-stearoyl-ACP desaturase (i.e., enzyme that
normally converts stearic acid to to oleic acid
in the oil creation process in traditional vari-
eties of canola), causes the higher than tra-
ditional amount of stearic acid in the canola
oil. See also 
CANOLA
,
STEARATE
,
SATURATED
FATTY ACIDS
 (
SAFA
),
GENE
,
GENETIC ENGINEERING
,
VALUE
-
ENHANCED GRAINS
,
FATTY ACID
,
COSUP-
PRESSION
,
ENZYME
,
OLEIC ACID
,
STEAROYL
-
ACP
DESATURASE
,
CHOLESTEROL
,
CORONARY HEART
DISEASE
 (
CHD
).
High-Stearate Soybeans Soybean plant vari-
eties which have been bred or genetically
engineered so their beans contain at least
12% stearate (also known as stearic acid)
within their soybean oil (i.e., more than four
times the typical 3% stearic acid content in
the soybean oil produced from traditional
soybean varieties). Some high-stearate soy-
beans contain more than 20% stearate.
Cosuppression, via inserted gene for
D
-stearoyl-ACP desaturase (i.e., enzyme that
normally converts stearic acid to oleic acid
in the oil creation process in traditional vari-
eties of soybeans), is the primary way to
cause the higher than traditional amount of
stearic acid in the resultant soybean oil. A
human diet containing stearate instead of
alternative saturated fatty acids, does not
cause an increase in blood cholesterol levels
(whereas human consumption of the other
saturated fatty acids causes bloodstream
cholesterol levels to increase, which
increases risk of coronary heart disease). See
also
STEARATE
,
VALUE
-
ENHANCED GRAINS
,
SOY-
BEAN PLANT
,
SOYBEAN OIL
,
GENE
,
GENETIC ENGI-
NEERING
,
FATTY ACID
,
COSUPPRESSION
,
ENZYME
,
OLEIC ACID
,
CHOLESTEROL
,
SATURATED FATTY
ACIDS
 (
SAFA
),
CORONARY HEART DISEASE
 (
CHD
),
STEAROYL
-
ACP DESATURASE
.
High-Sucrose Soybeans Another name for
low-stachyose soybeans because the soy-
beans replace the (reduced) stachyose with
(additional) sucrose. See also 
LOW
-
STACHYOSE
SOYBEANS
,
STACHYOSE
,
VALUE
-
ENHANCED GRAINS
,
SOYBEAN PLANT
,
SUGAR MOLECULES
.
High-Throughput Identification Determina-
tion of the identification of a given chemical
compound (e.g., within a mixture), the
desired impact (cell apoptosis, etc.), a spe-
cific segment (sequence) of DNA (i.e., a spe-
cific gene), a specific ligand or receptor (e.g.,
“attaching” itself to a given molecule), etc.
within the overall process known as high-
throughput screening. See also 
HIGH
-
THROUGHPUT SCREENING
 (
HTS
),
COMBINATORIAL
CHEMISTRY
,
BIOCHIPS
,
CELL
,
APOPTOSIS
,
GENE
,
DEOXYRIBONUCLEIC ACID
  (
DNA
),
GENE EXPRES-
SION
,
TARGET
-
LIGAND INTERACTION SCREENING
,
R E C E P T O R S
,
C H A R A C T E R I Z A T I O N
A S S A Y
,
SEQUENCE
 (
OF A DNA MOLECULE
),
GENE EXPRES-
SION ANALYSIS
,
CAENORHABDITIS ELEGANS
(
C
.
ELEGANS
),
MOLECULAR BEACON
.
High-Throughput Screening (HTS) A meth-
odology utilized to quickly screen large
numbers of compounds for use as pharma-
ceuticals or agrochemicals (e.g., herbicides).
For example, when screening chemical com-
pounds for potential use as a pharmaceutical,
the goal often is to assess differences
between diseased and treated cells; enabling
identification of a pharmaceutical candidate
that favorably impacts change in protein
level (i.e., gene expression) which character-
izes a diseased state, or some other gene
expression marker (e.g., apoptosis).
When screening compounds for potential
use as herbicide active ingredients, the goal
is to assess differences between normal and
treated weed plant cells; enabling identifica-
tion of a potential herbicide candidate that
imparts desired (fatal) change. Although
whole living cells or whole microscopic ani-
mals such as nematodes could be utilized in
HTS, it is more common to use a proxy (e.g.,
receptors, enzymes, or STATs from applica-
ble cells) whose interaction with candidate
compounds can be inferred to cell (and/or
organism) effects. See also 
COMBINATORIAL
CHEMISTRY
,
BIOCHIP
,
TARGET
-
LIGAND INTERAC-
TION SCREENING
,
CELL
,
ORGANISM
,
CHARACTER-
I Z A T I O N
A S S A Y
,
P R O T E I N
,
G E N E
,
G E N E
EXPRESSION
,
HIGH
-
THROUGHPUT IDENTIFICATION
,
RECEPTORS
,
GENE EXPRESSION ANALYSIS
,
BIOAS-
SAY
,
GENE EXPRESSION MARKERS
,
SIGNAL TRANS-
DUCERS AND ACTIVATORS OF TRANSCRIPTION
(
STAT
s
),
APOPTOSIS
,
IN SILICO SCREENING
,
NEMA-
TODES
,
CAENORHABDITIS ELEGANS
  (
C
.
ELEGANS
),
ENZYME
,
NORTHERN BLOT ANALYSIS
,
MOLECULAR
BEACON
.
© 2002 by CRC Press LLC