Biotechnology

Autonomous Replicating Segment See
A R S
ELEMENT
.
Autonomous Replicating Sequence See
ARS
ELEMENT
.
Autoradiography A technique to detect radio-
actively labeled molecules by creating an
image on photographic film. The slab of gel
or other material in which the molecules are
held (suspended) is placed on top of a piece
of photographic film. The two are then
securely fastened together such that move-
ment is eliminated and the film is exposed
for a period of time. The exposed (to the
radiation) film is subsequently developed and
the radioactive area is seen as a dark (black)
area. Among other uses, autoradiography has
been used to track the spread of (radioac-
tively labeled) viruses in a living plant. After
treatment (the radioactive labeling process),
the whole plant (in a slab) is placed on top
of a piece of photographic film. When the
film is subsequently developed, the picture
seen is of a plant, with darker areas indicating
regions of greater virus concentration. See
also
LABEL
 (
RADIOACTIVE
),
VIRUS
.
Autosomes All chromosomes except the sex
chromosomes. A diploid cell has two copies
of each autosome.
Autotroph An organism that can live on very
simple carbon and nitrogen sources, such
as carbon dioxide and ammonia. See also
HETEROTROPH
.
Auxins From the Greek auxein, to increase,
this term refers to a family of chemical com-
pounds that regulate plant growth (e.g., stim-
ulate cell enlargement, cell division, initate
roots/growth, flowering, etc.). See also 
CELL
.
Auxotroph Auxotrophic mutant. A mutant
defective in the synthesis of a given biomole-
cule. The biomolecule must be supplied to the
© 2002 by CRC Press LLC

A
organism if normal growth is to be achieved.
See also 
MUTATION
,
GENE
,
GENE DELIVERY
 (
GENE
THERAPY
),
ESSENTIAL FATTY ACIDS
.
Avidin A protein naturally present in egg
white, oilseed protein (e.g., soybean meal),
and grain (e.g., corn/maize), it is 70 kilodal-
tons in mass (weight) and has a high affinity
for biotin (i.e., it “sticks” tightly to the biotin
molecule). Since grain-eating insects require
biotin (a B-complex vitamin) to live, adding
extra avidin to grain (e.g., by inserting a gene
to cause overproduction of avidin in the grain
kernels) may be a way to protect grain from
insects (e.g., weevils in stored corn/maize).
See also 
PROTEIN
,
SOY PROTEIN
,
CORN
,
KILODAL-
TON
 (
KD
),
BIOTIN
,
WEEVILS
,
VITAMIN
.
Avidity (of an antibody) The “tightness of fit”
between a given antibody’s combining site
and the antigenic determinant with which it
combines. The firmness of the combination
of antigen with antibody. See also 
ANTIGENIC
DETERMINANT
,
ANTIBODY
,
ANTIGEN
,
COMBINING
SITE
,
POLYCLONAL RESPONSE
,
CATALYTIC
ANTIBODY
.
Azadirachtin The pharmacophore (active
ingredient) in secretions of the tropical neem
tree, which resists insect depradations. See
also
PHARMACOPHORE
,
NEEM TREE
.
Azurophil-Derived Bactericidal Factor
(ADBF) Potent antimicrobial protein pro-
duced by neutrophils (a type of white blood
cell). See also 
LEUKOCYTES
.
© 2002 by CRC Press LLC

0-8493-XXXX-X/01/$0.00+$1.50
© 2001 by CRC Press LLC
B
B
␤ Sitostanol See
BETA SITOSTANOL
 (
β
SITOSTANOL
).
␤-conglycinin See
BETA
-
CONGLYCININ
.
B Cells B lymphocytes. See also 
LYMPHOCYTE
,
B LYMPHOCYTES
,
BLAST CELL
.
B Lymphocytes A class of white blood cells
originating in the bone marrow and found in
blood, spleen, and lymph nodes, they are the
precursors of (blood) plasma cells (B cells)
that secrete antibodies (IgG) directed against
invading antigens (e.g., of pathogenic bacte-
ria). Via a complex “gene splicing” process,
the B cells of the human body are able to
produce more than one billion different IgG
antibodies (i.e., able to bind onto and neu-
tralize a billion different antigens). See also
ANTIGEN
,
ANTIBODY
,
BLAST CELL
,
LYMPHOCYTE
,
PATHOGEN
,
BACTERIA
,
GENE SPLICING
,
IMMUNO-
GLOBULIN
,
ALLELIC EXCLUSION
.
B-DNA A helical form of DNA. B-DNA can
be formed by adding back water to (dehy-
drated) A-DNA. B-DNA is the form of DNA
of which James Watson and Francis Crick
first constructed their model in 1953. It is
found in fibers of very high (92%) relative
humidity and in solutions of low ionic
strength. This corresponds to the form of
DNA that is prevalent in the living cell. See
also
DEOXYRIBONUCLEIC ACID
  (
DNA
),
A
-
DNA
,
ION
,
CELL
.
BAC Acronym for Bacterial Artificial Chro-
mosomes. See also 
BACTERIAL ARTIFICIAL
CHROMOSOMES
 (
BAC
).
Bacillus Rod-shaped bacteria.
Bacillus subtilis (B. subtilis) A (rod-shaped)
aerobic bacterium commonly used as a host
in recombinant DNA experiments. During
the 1990s, research showed that corn (maize)
plant tissues infected with the endophyte
Bacillus subtilis were less likely to become
infected with Fusarium moniliforme fungus.
Other research has indicated the potential for
prior infection of corn (maize) plant tissues
to hinder any subsequent aflatoxin produc-
tion in that plant by Aspergillus flavus fun-
gus. See also 
BACTERIA
,
HOST VECTOR
  (
HV
)
SYSTEM
,
DEOXYRIBONUCLEIC ACID
 (
DNA
),
CORN
,
ENDOPHYTE
,
FUNGUS
,
FUSARIUM MONILIFORME
,
AFLATOXIN
.
Bacillus thuringiensis (B.t.) Discovered by
bacteriologist Ishiwata Shigetane on a dis-
eased silkworm in 1901. Later discovered on
a dead Mediterranean flour moth, and first
named Bacillus thuringiensis, by Ernst Ber-
liner in 1915. Today, B. thuringiensis refers
to a group of rod-shaped soil bacteria found
all over the earth, that produce “cry” proteins
which are indigestible by — yet still “bind”
to — specific insects’ gut (stomach) lining
(epithelium cell) receptors, so those “cry”
proteins are thereby toxic to certain classes
of insects (corn borers, corn rootworms,
mosquitoes, black flies, some types of bee-
tles, etc.), but are harmless to all mammals.
At least 20,000 strains of B. thuringiensis
are known. Genes that code for the produc-
tion of these cry proteins that are toxic to
insects have been inserted by scientists since
1989 into vectors (i.e., viruses, other bacte-
ria, and other microorganisms) in order to
confer insect resistance to certain agricul-
tural plants (e.g., via expression of those B.t.
proteins by one or more tissues of the trans-
genic plant). For example, the B.t. strain
known as B.t. kurstaki, which is fatal when
ingested by the European corn borer was first
(genetically) inserted into a corn plant (via
vector) in 1991. B.t. kurstaki kills borers via
perforation of that insect’s gut by cry (“crys-
tal-like”) proteins that are coded for by the
B.t. kurstaki gene. The vectors as listed
© 2002 by CRC Press LLC

B
above are entities that can take up and carry
the DNA into plant or other cells. Vectors
are DNA-carrying vehicles. See also 
ENDO-
PHYTE
,
CORN
,
GENE
,
PSEUDOMONAS FLUORE-
S C E N S
,
A G R O B A C T E R I U M
T U M E F A C I E N S
,
AUREOFACIN
,
EUROPEAN CORN BORER
  (
ECB
),
COWPEA TRYPSIN INHIBITOR
  (
Cp
TI
),
PROTEIN
,
“
SHOTGUN
”
METHOD
,
CODING SEQUENCE
,
FUSAR-
IUM
,
VECTOR
,
EXPRESS
,
GENETIC ENGINEERING
,
“
EXPLOSION
”
METHOD
,
BIOLISTIC
®
GENE GUN
,
CRY PROTEINS
,
CRY
1
A
  (
b
)
PROTEIN
,
CRY
1
A
  (
c
)
PROTEIN
,
CRY
9
C PROTEIN
,
B
.
t
.
KURSTAKI
,
B
.
t
.
TENE-
BRIONIS
,
B
.
t
.
ISRAELENSIS
,
B
.
t
.
TOLWORTHI
,
ION
CHANNELS
.
Back Mutation Reverse the effect of a muta-
tion that had inactivated a gene, thus restor-
ing wild phenotype. See also 
PHENOTYPE
,
MUTATION
.
Bacteria From the Greek bakterion, stick,
since the first bacteria viewed by man (via
crude microscopes) appeared to be stick-
shaped. Any of a large group of microscopic
organisms having round, rod-like, spiral, or
filamentous unicellular or noncellular bodies
that are often aggregated into colonies, are
enclosed by a cell wall or membrane (pro-
caryotes), and lack fully differentiated
nuclei. Bacteria may exist as free-living
organisms in soil, water, and organic matter,
or as parasites in the live bodies of plants
and animals. See also 
BACTERIOLOGY
.
Bacterial Artificial Chromosomes (BAC)
Pieces of DNA (e.g., plant DNA) that have
been cloned (made) inside living bacteria
(e.g., by plant researchers who need to
“manufacture” some pieces of plant DNA).
They can be utilized as vectors (for genetic
engineering), to carry (inserted) genes into
certain organisms. Some potential uses of
BACs include: the “manufacture” of probes
(i.e., sequences of DNA utilized to “find”
complementary sequences within large
pieces of DNA) via hybridization; the “man-
ufacture” of “DNA sequence markers” for
use in marker assisted selection (e.g., to
guide choices made by commercial crop
breeders, so they can more quickly select
plants bearing gene(s) for a particular trait)
to develop future improved crop varieties
faster than was previously possible. See also
BACTERIA
,
CLONE
 (
A MOLECULE
),
SYNTHESIZING
(
OF DNA MOLECULES
),
CHROMOSOMES
,
YEAST
ARTIFICIAL CHROMOSOMES
  (
YAC
),
HUMAN ARTI-
FICIAL CHROMOSOMES
  (
HAC
),
PROBE
,
MARKER
ASSISTED SELECTION
,
COMPLEMENTARY DNA
(
c
-
DNA
),
HYBRIDIZATION
  (
MOLECULAR GENET-
ICS
),
DEOXYRIBONUCLEIC ACID
 (
DNA
),
SEQUENCE
(
O F
A
D N A
M O L E C U L E
),
M A R K E R
  (
D N A
SEQUENCE
),
GENE
,
TRAIT
,
GENETIC ENGINEERING
,
VECTOR
.
Bacterial Expressed Sequence Tags These are
ESTs (expressed sequence tags) based on
sequenced/mapped bacterial genes instead
of the genes of (“traditional” EST)
C. elegans nematode. They are utilized to
“label” a given gene (i.e., in terms of that
gene’s function/protein). See also 
BEST
,
EXPRESSED SEQUENCE TAGS
  (
EST
),
BACTERIA
,
SEQUENCING
  (
OF DNA MOLECULES
),
SEQUENCE
(
OF A DNA MOLECULE
),
MAPPING
,
CAENORHABDITIS
ELEGANS
 (
C
.
ELEGANS
).
Bactericide See
MICROBICIDE
,
BIOCIDE
,
ANTIBIOTIC
.
Bacteriocide See
BACTERICIDE
.
Bacteriocins Proteins produced by many types
of bacteria that are toxic (primarily) to other
closely related strains of the particular bac-
teria that produce those proteins. Bacterio-
cins hold promise (e.g., after genetic
engineering of the DNA responsible for their
production) for future possible use as food
preservatives (i.e., acting against bacteria
species that cause food spoilage). For exam-
ple: the bacteriocin known as curvaticin 13,
which is produced by Lactobacillus curvatus
bacteria, inhibits the food-poisoning bacteria
Listeria monocytogenes; the bacteriocin
known as sakacin K, which is produced by
Lactobacillus sakei bacteria, inhibits the
food-poisoning bacteria Listeria monocytoge-
nes. However, the effectiveness of both cur-
vaticin 13 and sakacin K are lessened by the
presence of salt (e.g., in processed meat prod-
ucts), so salt resistance would be a desired
property that may some day be engineered
into those bacteriocins. See also 
PROTEIN
,
BAC-
TERIA
,
BACTERIOLOGY
,
BIFIDUS
,
STRAIN
,
TOXIN
,
GENETIC ENGINEERING
,
DEOXYRIBONUCLEIC ACID
(
DNA
),
CODING SEQUENCE
,
COLICINS
,
LISTERIA
MONOCYTOGENES
,
EXTREMOPHILIC BACTERIA
.
Bacteriology The science and study of bacteria,
a specialized branch of microbiology. The
bacteria constitute a useful and essential
© 2002 by CRC Press LLC

B
group in the biological community.
Although some bacteria prey on higher
forms of life, relatively few are pathogens
(disease-causing organisms). Life on earth
depends on the activity of bacteria to min-
eralize organic compounds and to capture
the free nitrogen molecules in the air for use
by plants. Also, bacteria are important indus-
trially for the conversion of raw materials
into products such as organic chemicals,
antibiotics, cheeses, etc. Genetically engi-
neered bacteria are starting to be used to
produce high value-added pharmaceuticals
and specialty chemicals. See also 
ESCHERI-
CHIA COLIFORM
 (
E
.
COLI
).
Bacteriophage Discovered in 1917 by Felix
d’Herelle (fr. bacteria eaters), a bacterio-
phage is a virus that attaches to, injects its
DNA into, and multiplies inside bacteria,
which causes bacteria to die. Often abbrevi-
ated as simply phage, another name for
virus. As an example, bacteriophage lambda
is commonly used as a vector in rDNA
experiments in Escherichia coli and attaches
to a specific receptor, which in the bacteria
also normally functions in sugar transport
across the cell wall. Viruses come in many
shapes and sizes. See also 
ESCHERICHIA
COLIFORM
  (
E
.
COLI
),
RECEPTORS
,
VIRUS
,
TRANS-
DUCTION
  (
GENE
),
TRANSDUCTION
  (
SIGNAL
),
TRANSFECTION
,
LAMBDA PHAGE
.
Bacterium See
BACTERIA
.
Baculovirus A class of virus that infects lepi-
dopteran insects (e.g., cotton bollworm or
gypsy moth larva). Baculoviruses can be
modified via genetic engineering to insert
new genes into the larva, causing those larva
to then produce proteins desired by man (e.g.,
pharmaceuticals). Baculoviruses are poten-
tially very useful for pharmaceutical produc-
tion, because the protein molecules produced
are glycosylated (i.e., have relevant oligosac-
charides attached to them), and baculoviruses
cannot infect vertebrate animals. Such phar-
maceuticals are thus not even a theoretical
risk to humans. See also 
VIRUS
,
GENETIC ENGI-
NEERING
,
GENE
,
PROTEIN
,
GLYCOSYLATION
,
BAC-
ULOVIRUS EXPRESSION VECTORS
 (
BEV
s
).
Baculovirus Expression Vectors (BEVs)
Vectors (used by researchers to carry new
genes into cells) in which the agent is a
baculovirus (a virus that infects certain types
of insects only). These could conceivably be
used to make a genetically engineered insec-
ticide that is specific to a targeted insect
(wouldn’t harm anything but that insect). For
example, a BEV might be used to cause a
cotton bollworm adult protein to be
expressed when the bollworm is a juvenile,
thus killing the bollworm before it has a
chance to damage a cotton crop. See also
BACULOVIRUS
,
VIRUS
,
VECTOR
,
GENE
,
PROTEIN
,
CELL
,
GENETIC ENGINEERING
.
Bakanae See
FUSARIUM MONILIFORME
.
BAR Gene A dominant gene from the Strep-
tomyces hygroscopicus bacterium, which
codes for (causes production of) the enzyme
phosphinothricin acetyl transferase (PAT).
When the BAR gene is inserted into a plant’s
genome (its DNA), it imparts resistance to
glufosinate-ammonium based herbicides.
Because the glufosinate-ammonium herbi-
cides act via inhibition of glutamine syn-
thetase (an enzyme that catalyzes the
synthesis of glutamine), this inhibition (of
enzyme) kills plants (e.g., weeds). That is
because glutamine is crucial for plants to
synthesize critically needed amino acids.
The BAR gene is often utilized by genetic
engineers as a marker gene. See also 
GENE
,
GENOME
,
GENETIC ENGINEERING
,
MARKER
(
GENETIC MARKER
),
DOMINANT ALLELE
,
ESSENTIAL
AMINO ACIDS
,
HERBICIDE
-
TOLERANT CROP
,
GTS
,
SOYBEAN PLANT
,
CANOLA
,
CORN
,
GLUTAMINE
,
GLUTAMINE SYNTHETASE
,
PHOSPHINOTHRICIN
,
PHOSPHINOTHRICIN ACETYLTRANSERASE
  (
PAT
),
PAT GENE
.
Barley The domesticated plant Hordeum vul-
gare, whose grain is utilized by man for
various purposes, such as feed barley variet-
ies (for feeding of livestock). Malting barley
varieties (containing beta-amylase in their
seeds) were created via mutation breeding
(i.e., bombardment of the seeds by ionizing
radiation to cause random genetic mutations,
followed by selection of the particular muta-
tion in which maltose is produced by that
barley plant in its seeds). See also 
TRADI-
TIONAL BREEDING METHODS
,
MUTATION
,
MUTA-
TION BREEDING
,
AMYLASE
.
Barnase An enzyme that catalyzes destruction
of nucleic acids (which thus kills the cell that
© 2002 by CRC Press LLC

B
the barnase is in). When the gene that codes
for barnase is inserted via genetic engineer-
ing into a given plant and activated only in
that plant’s pollen (the barnase is produced
only in its pollen cells), that plant’s male
parts become sterile. For crop plants possess-
ing both male and female parts (monoecious
plants), such male sterility facilitates the
development of hybrids, because self-polli-
nation does not occur. See also 
ENZYME
,
NUCLEIC ACIDS
,
CELL
,
GENE
,
GENETIC CODE
,
GENETIC ENGINEERING
,
GENETICS
,
HYBRIDIZATION
(
PLANT GENETICS
),
F
1
HYBRIDS
,
MONOECIOUS
.
Base (general) A substance with a pH in the
range 7–14, which will react with an acid to
form a salt. Mild bases normally taste bitter
and feel slippery to the touch. See also 
ACID
.
Base (nucleotide) A segment of the DNA (and
RNA) molecules. One of the four (repeating)
chemical units that comprise DNA/RNA
that, according to their order and pairing (on
the parallel strands of DNA/RNA mole-
cules), represent the different amino acids
(within the protein molecule that each gene
in the DNA codes for). The four bases com-
prising DNA are adenine (A), cytosine (C),
guanine (G), and thymine (T). See also
DEOXYRIBONUCLEIC ACID
  (
DNA
),
RIBONUCLEIC
ACID
  (
RNA
),
POLYMER
,
CODING SEQUENCE
,
CONTROL SEQUENCES
,
EXPRESSION
,
AMINO ACID
,
PROTEIN
,
GENE
,
ADENINE
,
CYTOSINE
,
GUANINE
,
THYMINE
,
URACIL
,
BASE PAIR
 (
bp
).
Base Excision Sequence Scanning (BESS)
A method that can be utilized to detect a
“point mutation” in DNA (via rapid DNA
sequence scanning). See also 
BASE PAIR
 (
bp
),
NUCLEOTIDE
,
DEOXYRIBONUCLEIC ACID
  (
DNA
),
M U T A T I O N
,
P O I N T
M U T A T I O N
,
E X C I S I O N
,
SEQUENCING
  (
OF DNA MOLECULES
),
SEQUENCE
(
OF A DNA MOLECULE
).
Base Pair (bp) Two nucleotides that are in dif-
ferent nucleic acid chains and whose bases
pair (interact) by hydrogen bonding. In
DNA, the nucleotide bases are adenine
(which pairs with thymine) and guanine
(which pairs with cytosine). See also 
DEOXY-
RIBONUCLEIC ACID
 (
DNA
),
GENETIC CODE
,
INFOR-
MATIONAL MOLECULES
.
Base Substitution Replacement of one base
(within a DNA molecule) by another base.
See also 
BASE
  (
NUCLEOTIDE
),
TRANSITION
,
TRANSVERSION
.
Basic Fibroblast Growth Factor (BFGF)
See
FIBROBLAST GROWTH FACTOR
 (
FGF
).
Basophilic Staining strongly with basic dye.
For example, basophil leukocytes are poly-
morphonuclear leukocytes which stain
strongly with (take up a lot of) basic dyes.
See also 
POLYMORPHONUCLEAR LEUKOCYTES
(
PMN
).