Biotechnology
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- Squalene
- Stanol Ester See SITOSTANOL . Stanol Fatty Acid Esters S e e S I T O S T A N O L , FATTY ACID . Starch
- Stearate (stearic acid)
- Stearic Acid See STEARATE . Stearoyl-ACP Desaturase
- Stem Cell Growth Factor (SCF)
- Sterilization See STERILE ( ENVIRONMENT ), STER- ILE ( ORGANISM ). Steroid
- Structural Biology See STRUCTURAL GENE . Structural Gene
- STS Sulfonylurea (Herbicide)-Tolerant Soy- beans
- Substance K See TACHYKININS . Substance P
Spontaneous Assembly See SELF - ASSEMBLY . SPS Acronym for the Sanitary and Phytosani- tary Standards Agreement of the World Trade Organization (WTO), a multinational trading agreement that “sets the rules” gov- erning international trade. Sanitary (i.e., human and animal) and phytosanitary (i.e., plant) standards are important in preventing the transfer of diseases from one nation to another via international trade. SPS stan- dards are designed to protect animal, plant, and human life/health (within WTO member countries) from: • Entry of pests (insects, weeds, etc.) • Entry of disease-carrying organisms (e.g., European Corn Borer) • Entry of disease-causing organisms (e.g., Aspergillus flavus) • Toxins, contaminants, or disease-caus- ing organisms in foods, beverages, or feedstuffs © 2002 by CRC Press LLC S WTO member nations are required to base their SPS standards as much as possible on existing (e.g., Codex Alimentarius, IPPC, and OIE) international sanitary/phytosani- tary standards and practices. See also SANI- TARY AND PHYTOSANITARY ( SPS ) AGREEMENT , SANITARY AND PHYTOSANITARY ( SPS ) AGREE- MENT , INTERNATIONAL PLANT PROTECTION CON- VENTION ( IPPC ), INTERNATIONAL OFFICE OF EPIZOOTICS ( OIE ), CODEX ALIMENTARIUS COMMIS- SION , MAXIMUM RESIDUE LEVEL ( MRL ), WORLD TRADE ORGANIZATION ( WTO ), EUROPEAN CORN BORER ( ECB ), ASPERGILLUS FLAVUS . Squalamine A potent antimicrobial agent (ste- roid, antibiotic) discovered in the tissues of the dogfish shark in 1992. It has been found to be active against a broad spectrum of bac- teria, protozoa, and fungi. Squalamine was chemically synthesized by man in 1993. See also MAGAININS , STEROID , FUNGUS , BACTERIA , BACTERIOCINS , PROTOZOA , ANTIBIOTIC . Squalene A sterol that is produced in some plants. See also STEROLS . SRB (sulfate reducing bacterium) Any organ- ism that metabolically reduces sulfate to H 2 S (hydrogen sulfide). This includes a variety of microorganisms. See also REDUCTION ( IN A CHEMICAL REACTION ), METABOLISM , MICROOR- GANISM , FERROBACTERIA . SSR See SIMPLE SEQUENCE REPEAT ( SSR ) DNA MARKER TECHNIQUE . Stacchyose See STACHYOSE . Stachyose A carbohydrate (oligosaccharide) naturally produced in soybeans (and some other plants). Stachyose is relatively insolu- ble in water, and much less available for digestion by monogastric animals (e.g., swine, poultry) than the other carbohydrate components within soybeans. See also CAR- BOHYDRATES ( SACCHARIDES ), LOW STACHYOSE SOYBEANS , OLIGOSACCHARIDES , SOYBEAN PLANT . “Stacked” Genes Refers to the insertion of two or more (synthetic) genes into the genome of an organism. One example would be of a plant into which a gene from Bacillus thuringiensis (B.t.) and a gene for resistance to a specific herbicide have been inserted. See also GENE , BIOTECHNOLOGY , GENETIC ENGI- NEERING , BACILLUS THURINGIENSIS ( B . t .), B . t . KURSTAKI , GENETICALLY ENGINEERED MICROBIAL PESTICIDES ( GEMP ), EPSP SYNTHASE , PAT GENE , BAR GENE . Staggered Cuts Scissions (cuts) made in duplex DNA when the two strands of DNA that make up the duplex DNA are cleaved at different points near each other by restriction endonucleases. What is produced is a single- stranded structure (in which the single strands are a number of nucleotide bases long) with a double-stranded core section. This core sec- tion is much longer than the single-stranded region. See also DEOXYRIBONUCLEIC ACID ( DNA ), RESTRICTION ENDONUCLEASES , STICKY ENDS . Stanol Ester See SITOSTANOL . Stanol Fatty Acid Esters S e e S I T O S T A N O L , FATTY ACID . Starch A polymer of glucose molecules (i.e., a polysaccharide) used by plants to store energy. Plants produce starch in two differ- ent molecular forms, amylopectin and amy- lose. For example, the starch content in traditional corn (maize) kernels averages 72–76% amylopectin and 24–28% amylose. Starch is broken down by enzymes (amy- lases) to yield glucose, which can be used as an energy source. The analogous polymer used by mammalian systems is called gly- cogen or, in old usage, “animal starch.” See also GLUCOSE ( GL c ), ENZYME , AMYLASE , CORN , AMYLOSE , AMYLOPECTIN . Startpoint Refers to the position on a DNA molecule corresponding to the first base incorporated into mRNA. See also DEOXY- RIBONUCLEIC ACID ( DNA ), MESSENGER RNA ( m RNA ), EXON , RIBONUCLEIC ACID ( RNA ). Stearate (stearic acid) A saturated fatty acid, containing 18 carbon atoms in its molecular “backbone,” that is essentially neutral in effect on coronary heart disease in humans (i.e., doesn’t appreciably increase low-den- sity lipoproteins in the bloodstream). Because of the heart disease neutrality, stearate-con- taining oils (e.g., high-stearate soybean oil) are an acceptable cooking oil choice, with the resistance to oxidation/breakdown of a saturated fatty acid, but no bloodstream-cho- lesterol increasing effect. In the mid-1990s, the American Cocoa Research Institute/Chocolate Manufacturers Association filed a petition with the U.S. Food and Drug Administration (FDA) to © 2002 by CRC Press LLC S differentiate stearate (on food product labels) from the other saturated long-chain fatty acids used as food ingredients. In order to make milk, dairy cows require more stearic acid than a conventional diges- tive system alone could provide from the cow’s (mainly carbohydrate) diet. Therefore, cows utilize microorganisms living in their rumen (a special sort of pre-stomach) to con- vert carbohydrate (grass) to stearic acid. Thus, high-performance dairy cows might benefit from a diet that contains high-stear- ate soybeans, if their milk output is limited by dietary stearate availability. See also FATTY ACID , LOW - DENSITY LIPOPROTEINS ( LDLP ), SATURATED FATTY ACIDS , FOOD AND DRUG ADMINISTRATION ( FDA ), HIGH - STEARATE SOY- BEANS , FATS , ENOYL - ACYL PROTEIN REDUCTASE , HIGH - STEARATE CANOLA . Stearic Acid See STEARATE . Stearoyl-ACP Desaturase A “ f a m i l y ” o f enzymes that is naturally produced in oilseed plants. They play the central role in deter- mining the ratio of saturated to unsaturated fatty acids (in the vegetable oils produced from such plants). See also FATS , FATTY ACID , ENZYME , GENETIC ENGINEERING , GENETIC CODE , LAURATE , HIGH - STEARATE SOYBEANS , HIGH - STEARATE CANOLA . Stem Cell Growth Factor (SCF) A growth factor (glycoprotein hormone) that acts upon stem cells in a wide variety of ways to increase growth, proliferation, and maturity (into red blood cells or white blood cells). See also STEM CELLS , GROWTH FACTOR , HOR- MONE , GLYCOPROTEIN , DIFFERENTIATION , TOTI- POTENT STEM CELLS , COLONY STIMULATING FACTORS ( CSF s ). Stem Cell One The single stem cell in the bone marrow of a fetus from which every immune system cell in the adult is subse- quently derived. The primordial stem cell is stimulated to develop into the mature immune system’s differentiated, specialized cells by interleukin-7. See also STEM CELLS , TOTIPOTENT STEM CELLS , INTERLEUKIN- 7 ( IL- 7 ), EMBRYONIC STEM CELLS , DIFFERENTIATION . Stem Cells Certain cells — present in the bod- ies of mammals even prior to birth, although also present in adult mammals — that can grow/differentiate into different cells/tissues of the (adult organism) body. For example, bone marrow (stem) cells, some of which eventually mature into red blood cells or white blood cells. The stem cells that remain in the bone marrow maintain their own num- bers by self-renewal divisions, yielding more cells to start the maturation process. This maturation process is stimulated and con- trolled by stem cell growth factor (SCF), granulocyte colony stimulating factor (G-CSF), and by granulocyte-macrophage colony stimulating factor (GM-CSF). During 2000, research by Richard Childs showed that stem cells (i.e., collected from a sibling’s bloodsteam) transplanted into a patient suffering from kidney cancer could induce generation of a “new” immune sys- tem which could help stop/reverse the kid- ney cancer. See also CELL , MULTIPOTENT ADULT STEM CELLS , ECTODERMAL ADULT STEM CELLS , ENDODERMAL ADULT STEM CELLS , MESODERMAL ADULT STEM CELLS , HEMATOPOIETIC STEM CELLS , RED BLOOD CELLS , WHITE BLOOD CELLS , BASO- PHILS , STEM CELL ONE , STEM CELL GROWTH FACTOR ( SCF ), TOTIPOTENT STEM CELLS , TOTIPOTENCY , EMBRYONIC STEM CELLS , DIFFERENTIATION , IMMUNE RESPONSE , CANCER . Stereoisomers Molecules that have the same structural formula but different spatial arrangements of dissimilar groups (of atoms) bonded to a common atom (in the molecule). Many of the physical and chem- ical properties of stereoisomers are the same, but there are differences in the crystal struc- tures, in the direction in which they rotate polarized light (which has been passed through a solution of the stereoisomer), and in their use in an enzyme-catalyzed (biolog- ical) reaction. See also RACEMATE , POLARIME- TER , DEXTROROTARY ( D ) ISOMER , EPIMERS , ISOMER , LEVOROTARY ( L ) ISOMER , ISOMERASE , DIASTEREOISOMERS . Steric Hindrance Refers to the compression that a group (chemical entity) suffers by being too close to its nonbonded neighbors. If an enzyme and a substrate try to come together in order to react, but the substrate has on it a bulky group that disallows close contact between the two (because the group bumps into the enzyme), then the reaction will not occur because of steric hindrance. © 2002 by CRC Press LLC S Seen another way, two chemical groups bump into each other and cannot get by each other because they are held in place by the bonds binding them to other atoms. Hin- drance of movement or activity occurs because chemical groups bump into each other and cannot occupy the same space. See also REPRESSION ( OF AN ENZYME ), INHIBITION , COREPRESSOR . Sterile (environment) One that is free of any living organisms or spores. For example, a hypodermic needle that has been sterilized (e.g., by heating it) and is free of living microorganisms is said to be sterile. Sterile (organism) One that is unable to repro- duce. For example, a bull that has been cas- trated is rendered sterile. See also TRIPLOID , BARNASE . Sterilization See STERILE ( ENVIRONMENT ), STER- ILE ( ORGANISM ). Steroid A chemical compound composed of a series of four carbon rings joined together to form a (molecular) structural unit called cyclo- pentanoperhydrophenanthrene. Any of a group of naturally occurring, fat-soluble substances essential to life, usually classed as lipids. Steroids of importance to the body are the sterols, which are bile acids (produced by the liver, characterized by the presence of a carboxyl group in the molecule’s side chain), and the hormones of the sex glands and the adrenal cortex. In addition, the plant king- dom possesses a wide variety of steroid gly- cosides. See also GLYCOSIDE , LIPIDS , HORMONE , CHOLESTEROL , STEROLS , SAPONINS . Sterols Solid alcohols consisting of ring-struc- tured molecules (i.e., a ‘ring’ made of atoms). Evidence suggests that human con- sumption of certain phytosterols (i.e., sterols produced in plant seeds) can help to prevent certain types of cancers, and can help lower levels of total blood serum cholesterol and low-density lipoproteins (LDLP); thereby reducing risk of coronary heart disease (CHD). Evidence indicates that those phy- tosterols interfere with absorption of choles- terol by the intestines, and they decrease the body’s recovery and reuse of cholesterol- containing bile salts, which causes more cholesterol to be excreted from the body. During 2000, researcher Joseph Judd fed phytosterols extracted from soybeans (Gly- cine max L.) to human volunteers who were already consuming a “low fat” diet. Their total blood serum cholesterol and low-den- sity lipoprotein (LDLP) levels decreased by more than 10%, in a short time. During 2001, the U.S. FDA approved a (label) health claim that associates the consumption of plant ste- rols with reduced blood cholesterol content, and with reduced coronary heart disease (CHD). Some of the sterols known to impart health benefits when consumed by humans include β-sitosterol (beta-sitosterol) and squalene. See also PHYTOSTEROLS , STEROID , CHOLESTEROL , BILE , SITOSTANOL , SOYBEAN PLANT , CAMPESTEROL , STIGMASTEROL , BETA - SITOSTEROL , CORONARY HEART DISEASE ( CHD ), LOW - DENSITY LIPOPROTEINS ( LDLP ), FOOD AND DRUG ADMINIS- TRATION ( FDA ). Sticky Ends Complementary single strands of DNA (deoxyribonucleic acid) that protrude from opposite ends of a DNA duplex or from ends of different DNA duplex molecules. They can be generated by staggered cuts in DNA. They are called “sticky” because the exposed single strands can bind (stick) to complementary single strands on another DNA molecule. A hybrid piece of DNA is hence produced (by that binding). See also STAGGERED CUTS , HYBRIDIZATION ( MOLECULAR GENETICS ), DUPLEX , ANNEAL , DEOXYRIBONUCLEIC ACID ( DNA ), BLUNT - END LIGATION , RESTRICTION ENDONUCLEASES . Stigmasterol A phytosterol produced within the seeds of the soybean plant (Glycine max L.), among others. Evidence indicates that human consumption of stigmasterol helps reduce levels of total serum cholesterol and low-density lipoproteins (LDLP); thereby lowering risk of coronary heart disease (CHD). Evidence indicates that certain phy- tosterols (including stigmasterol) interfere with absorption of cholesterol by the intes- tines, and decrease the body’s recovery and reuse of cholesterol-containing bile salts; which causes more cholesterol to be excreted from the body. See also PHYTOSTEROLS , PHYTO- CHEMICALS , STEROLS , SOYBEAN PLANT , CHOLES- T E R O L , C A M P E S T E R O L , B E T A - S I T O S T E R O L , CORONARY HEART DISEASE ( CHD ). © 2002 by CRC Press LLC S Stomatal Pores See GPA 1 , ABSCISIC ACID . Strain A group or organisms of the same spe- cies that possess(es) distinctive genetic char- acteristics that set it apart from others within the same species, but whose differences are not “severe” enough for it to be considered a different breed or variety (of that species). The basic taxonomic unit of microbiology. Can also be used to designate a population of cells derived from a single cell. See also SPECIES , CELL , CLONE ( AN ORGANISM ). Streptococcus Refers to bacteria of the genus Streptococcus. See also BACTERIA , GENUS , STREPTOCOCCUS MUTANS . Streptococcus mutans The strain of Strepto- coccus bacteria that grows on the surface of teeth and can contribute to causing tooth “decay.” See also STRAIN , BACTERIA , STREPTO- COCCUS . Stress Proteins Discovered by Italian biolo- gist Ferruchio Ritossa in the 1960s, these molecules are also called heat-shock pro- teins. Proteins made by many organisms’ (plant, bacteria, and mammal) cells when those cells are stressed by environmental conditions such as certain chemicals, patho- gens, or heat. When corn/maize (Zea mays L.) is stressed during its growing season by high nighttime temperatures, that plant switches from its normal production of (“immune sys- tem” defense) chitinase to production of heat-shock (i.e., stress) proteins, instead. Stress proteins are also produced by tuberculosis and leprosy bacteria after these bacteria have invaded (infected) cells in the human body, in an attempt by those bacteria to mimic the stress proteins that (mammal) cells would normally manufacture to repair damage done to the (mammal) cells. This mimicry makes it more difficult for the immune system to recognize and attack those pathogenic bacteria (and/or repair mis- shaped protein molecules in the body’s cells). Similarly, production of stress pro- teins helps some types of cancer cells to avoid being attacked by the immune system. Because consumption of genistein by humans causes a reduction in the production of stress proteins, genistein may thereby help the human immune system destroy cancerous cells. In 1996, Richard I. Morim- oto discovered that two stress proteins known as HSP 90 and HSP 70 help ensure that certain crucial proteins in cells are folded into the configuration/conformation needed by that cell. See also ANTIGEN , IMMUNE RESPONSE , PATHOGEN , PROTEIN , PROTEIN FOLD- ING , CONFORMATION , CHAPERONES , PROTEIN STRUCTURE , ABSOLUTE CONFIGURATION , PRION , CHITINASE , AFLATOXIN , GENISTEIN , CANCER , LIPOXYGENASE ( LOX ), PHYTOALEXINS . Stromelysin (MMP-3) A collagenase (enzyme) that “clears a path” through living tissue, ahead of tumor cells, thereby enabling a can- cer to spread within the body. See also COLLAGENASE , ENZYME , CANCER , TUMOR . Structural Biology See STRUCTURAL GENE . Structural Gene A gene that codes for any RNA (ribonucleic acid) or protein product other than a regulator molecule. It deter- mines the primary sequences (i.e., the amino acid sequences) of a polypeptide (protein). See also GENE , EXPRESS , POLYPEPTIDE ( PROTEIN ), AMINO ACID , PRIMARY STRUCTURE , RIBONUCLEIC ACID ( RNA ). Structural Genomics Study of, or discovery of, where (gene) sequences are located within the genome, and what (DNA) sub- units comprise those sequences. See also GENE , SEQUENCE ( OF A DNA MOLECULE ), DEOXY- RIBONUCLEIC ACID ( DNA ), SEQUENCING ( OF DNA MOLECULES ), GENOME , GENOMICS , PRIMARY STRUCTURE . STS Sulfonylurea (Herbicide)-Tolerant Soy- beans These are soybeans that have been bred (via insertion of ALS gene by tradi- tional breeding methods) to resist the (weed killing) effects of sulfonylurea-based herbi- cides. The ALS gene was discovered by Scott Sebastian in 1986. See also GENE , GENETIC ENGINEERING , HTC , ALS , ALS GENE , BAR GENE , PAT GENE , EPSP SYNTHASE , GLYPHOSATE OXIDASE , HERBICIDE - TOLERANT CROP . Stx Shiga-like toxins. See also TOXIN , TOXI- GENIC E . COLI , ENTEROHEMORRHAGIC E . COLI , ESCHERICHIA COLIFORM 0157 : H 7 ( E . COLI 0157 : H 7 ). Substance K See TACHYKININS . Substance P A neuropeptide (i.e., peptide pro- duced by cells of the nervous system) which is involved in activation of the immune sys- tem, pain sensation, and (when in excess) © 2002 by CRC Press LLC |
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