Biotic Stresses The stress (e.g., to crop plants) caused by insects, bacteria, viruses, fungi, nematodes, or other living things that attack

plants. See also NEMATODES, FUNGUS, VIRUS,

BACTERIA.

Biotin A B-complex vitamin, also known as vitamin H, which is essential (required) for life of many grain-eating insects as well as for many of the metabolic pathways (series of chemical reactions) involved in milk production by cattle. All of the predominant cellulolytic bacteria (i.e., those that breakdown cellulose molecules) within the rumen (first stomach) of cattle require biotin for them to be able to grow. Biotin (within certain molecules) acts as a coenzyme in carboxylation reactions, thereby playing a critical role in gluconeogenesis, fatty acid synthesis (manufacture), and protein synthesis reactions occurring within all animals. Biotin enzymes are inhibited (blocked) by the protein avidin. Since insects must have biotin to live, avidin might be a useful ingredient to add to grain in order to protect it from insects such as weevils during storage.

See also VITAMIN, METABOLISM, INTERMEDIARY

METABOLISM, PATHWAY, BACTERIA, CELLULOSE,

LYSIS, ENZYME, COENZYME, WEEVILS, GLUCONEO-

GENESIS, FATTY ACID, PROTEIN, AVIDIN.

Biotransformation (of a biosynthesized

product) See POSTTRANSLATIONAL MODIFICA-

TION OF PROTEIN.

Biotransformation (of an introduced compound) Biological portion of definition of persistence. See also PERSISTENCE.

bla Gene A gene that confers resistance to β-lactam (beta-lactam) antibiotics (e.g., ampicillin). See also GENE, BETA-LACTAM

ANTIBIOTICS, MARKER (GENETIC MARKER).

Black-layered (corn) An indicator of a corn plant’s maturity. It refers to a distinctive dark line that forms in each corn kernel at maturity. See also CORN.

Black-lined (corn) See BLACK-LAYERED (CORN).

Blast Cell A large, rapidly dividing cell that develops from a B cell (B lymphocyte) in response to an antigenic stimulus. The blast cell then becomes an antibody-producing plasma cell. See also ANTIGEN, ANTIBODY,

B LYMPHOCYTES , LYMPHOCYTE.

Blood Serum See SERUM.

Blood-Brain Barrier (BBB) The specialized layer of endothelial cells that line all blood vessels in the brain. The BBB prevents most organisms (e.g., bacteria) and toxins from entering the brain via the bloodstream while allowing the passage of oxygen and needed nutrients (iron, glucose, tryptophan, etc.). For example, receptors that line BBB cell surfaces (on the bloodstream side of the BBB) “latch onto” transferrin molecules (which contain iron molecules) as those transferrin molecules pass by in the bloodstream. These transferrin receptors first bind to the (passing) transferrin molecules, transport them through the BBB via a process called vaginosis, then release them (in order to supply needed iron to the brain cells). Factors such as aging, trauma, stroke, multiple sclerosis, and some infections will cause an increase in the permeability of the

BBB. See also ENDOTHELIAL CELLS, TOXIN,

TRANSFERRIN, TRANSFERRIN RECEPTOR, CHELAT-

ING AGENT, GLUCOSE, RECEPTORS, VAGINOSIS,

HEME, BACTERIA, TRYPTOPHAN (trp), SEROTONIN.

Blunt-End DNA A segment of DNA that has both strands terminating at the same basepair location, that is, fully base-paired DNA. No sticky ends. See also STICKY ENDS.

Blunt-End Ligation A method of joining blunt-ended DNA fragments using the enzyme T4 ligase, which can join fully basepaired, double-stranded DNA. See also

LIGASE, DEOXYRIBONUCLEIC ACID (DNA), BASE

PAIR (bp), BLUNT-END DNA.

BLUP See BEST LINEAR UNBIASED PREDICTION

(BLUP).

BOD See BIOLOGICAL OXYGEN DEMAND (BOD).

Boletic Acid See FUMARIC ACID (C4H4O4).

Bollworms See HELIOTHIS VIRESCENS (H. VIRE-

SCENS), HELICOVERPA ZEA (H. ZEA), PECTINOPHORA

, . . .

BBone Morphogenetic Proteins (BMP) A fam-KURSTAKIGOSSYPIELLA B t

ily of proteinaceous growth factors (nine identified as of 1994) for bone tissue formation (e.g., at the site where a bone has been broken). BMPs stimulate a “recruitment” of bone-forming cells (to the site of bone injury) which first form cartilage, then mineralize that cartilage to form bone. See also

GROWTH FACTOR, PERIODONTIUM, PROTEIN.

Bovine Somatotropin (BST) A l s o c a l l e d bovine growth hormone. A protein hormone, produced in a cow’s pituitary gland, that increases the efficiency of the cow in converting its feed into milk. Increases milk production, and promotes cell growth in healing tissues of all ages of cattle. Promotes body growth of young cattle. See also PROTEIN,

GROWTH HORMONE (GH), HORMONE, SOMATOME-

DINS, SPECIES SPECIFIC.

Bowman-Birk Trypsin Inhibitor See TRYPSIN

INHIBITORS.

bp Common abbreviation for base pair. See

also BASE PAIR (bp).

Brassica A fast-growing category of the mustard plant family, which also produces sul- fur-based gases (a natural defense against certain fungi, nematodes, and insect pests). For example, Australian CSIRO scientists discovered in 1994 that sulfur-based isothiocyanates emitted by Brassica actively combat Wheat Take-All Disease (a fungal disease that attacks the roots of the wheat

plant). See also ARABIDOPSIS THALIANA,

WHEAT, WHEAT TAKE-ALL DISEASE, CANOLA,

ALLELOPATHY, FUNGUS, NEMATODES.

Brassica campestre See BRASSICA. Brassica campestris See CANOLA, BRASSICA. Brassica napus See CANOLA, BRASSICA.

BRCA Genes Oncogenes that, when mutated, can cause development of breast cancer or ovarian cancer. All humans possess BRCA genes of one sort or another (the acronym BRCA stands for breast cancer). However, the two specific BRCA genes most likely to lead to breast cancer (BRCA 1 and BRCA 2) are present in only two percent of women who are of Northern European ancestry, most Caucasian women in the U.S., and

© 2002 by CRC Press LLC

Askenazi Jews whose ancesters are from Central and Eastern Europe. Those women possessing the BRCA 1 gene in their genome (DNA) have a 20–40% chance of developing ovarian cancer (and a 50–85% chance of developing breast cancer) in their lifetime. Those women possessing the BRCA 2 gene in their genome (DNA) have a 15–20% chance of developing ovarian cancer (and a 55–85% chance of developing breast cancer) in their lifetimes. See also GENE, MUTATION,

CANCER, ONCOGENES, HER2 GENE.

BRCA 1 Gene See BRCA GENES.

BRCA 2 Gene See BRCA GENES.

Breeder’s Rights See PLANT BREEDER’S RIGHTS.

Bright Greenish-Yellow Fluorescence (BGYF) An indication of the presence of fungus (e.g., in a sample of grain), when light of an appropriate wavelength is shone on sample. For example, when the fungus Aspergillus flavus infects cottonseed during boll development on the cotton plant, the resultant seed (when harvested) shows BGYF on its lint and linters. That fungus gains entry into the bolls typically via holes made by the pink bollworm (Pectinophora gossypiella).

See also MYCOTOXINS, AFLATOXIN, FUNGUS,

PECTINOPHORA GOSSYPIELLA, FLUORESCENCE.

Broad Spectrum See GRAM STAIN.

Bromoxynil An active ingredient in some herbicides, it kills certain types of plants (weeds). See also NITRILASE.

Broth A fluid culture medium (for growing microorganisms). See also MEDIUM, CULTURE

MEDIUM.

Brown Stem Rot (BSR) A plant disease that can be caused by the soilborne fungus

Phialaphora gregata in the soybean plant (Glycine max L. Merrill). Some soybean varieties are genetically resistant to BSR.

See also FUNGUS, SOYBEAN PLANT, GENOTYPE,

GENE, PATHOGENIC.

BSE Bovine spongiform encephalopathy. A neurodegenerative disease of cattle. See also

PRION.

BSP Biosafety protocol. See also CONVENTION

ON BIOLOGICAL DIVERSITY (CBD).

BSR See BROWN STEM ROT (BSR).

BST See BOVINE SOMATOTROPIN (BST).

BtR-4 Gene See TOXICOGENOMICS.

B.t. See BACILLUS THURINGIENSIS (B.t.).

C. elegans See CAENORHABDITIS ELEGANS.

C Value The total amount of DNA in a haploid

genome. See also DEOXYRIBONUCLEIC ACID

(DNA), HAPLOID, GENOME.

C-DNA Also known as copy DNA. A helical form of DNA, it occurs when DNA fibers are maintained in 66% relative humidity in the presence of lithium ions. It has fewer base pairs per turn than B-DNA. See also

B-DNA , DEOXYRIBONUCLEIC ACID (DNA), BASE

PAIR (bp), COMPLEMENTARY DNA (cDNA).

Cadherins A class of (cell surface) adhesion molecules that causes cells (e.g., in the lining of the intestine known as the epithelium) to “stick together” to form a continuous lining; cadherins sometimes function as cellular adhesion receptors. For example, the (food poisoning) pathogenic bacteria Listeria monocytogenes is able to infect humans via its use of the E-cadherin receptor located on the surface of intestinal epithelium cells. That bacteria’s “key” (a bacterial membrane surface protein known as internaulin) is “inserted” into the E-cadherin (“lock”), which opens up the otherwise closed-to-bacteria intestinal epithelium. The L. monocytogenes bacteria then leave the intestine and infect the human body tissues. See also ADHESION

M O L E C U L E , C E L L , R E C E P T O R S , L I S T E R I A

MONOCYTOGENES, EPITHELIUM.

Caenorhabditis elegans (C. elegans) The name of a nematode (microscopic roundworm) that is commonly utilized by scientists in genetics experiments. Because of this, a large base of knowledge about C. elegans genetics has been accumulated by the world’s scientific community. For example, of the nearly 300 “disease-causing genes” in the human genome, more than half of them have an analogous gene within the

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C

C. elegans genome. C. elegans was one of the first animals to have its entire genome sequenced by man. Thus, one of the methodologies utilized by researchers to rapidly screen large numbers of chemical compounds for their potential use as pharmaceuticals is to:

Expose large numbers of C. elegans to the various chemical compounds that the researcher wants to investigate for potential pharmaceutical activity.

Pass those large numbers of previously exposed C. elegans, suspended in liquid such as water, through a small transparent chamber where a focused laser beam is shone upon the roundworm’s side (for its full length, as the roundworm passes by).

Utilize expression-of-fluorescent-protein, autofluorescence, lectin (in the fluid) binding detected via laser reflectance, antibody (in the fluid) binding detected via laser reflectance, etc. as the basis for individual C. elegans to be “sorted” via tiny jets of air that blow into a container those C. elegans that show thus visible sign(s) of having been changed by the particular chemical compound to which they were exposed.

Evaluate in detail (e.g., via conventional gene expression analysis) the specific impact of that particular chemical compound on those C. elegans that had indicated an apparent change, so were sorted into the “likely target” receptacle.

See also NEMATODES, GENETICS, GENE, GENOME,

GENE EXPRESSION, GENE EXPRESSION MARKERS,

EXPRESSED SEQUENCE TAGS (EST), SEQUENCING