Blotting A technique used for transferring DNA, RNA, or protein from gels to a suitable binding matrix, such as nitrocellulose or nylon paper, while maintaining the same physical separation.
Blue copper protein An electron transfer protein containing a type 1 copper site. Characterized by a strong absorption in the visible region and an EPR (electron paramagnetic resonance spectroscopy) signal with an unusually small hyperfine coupling to the copper nucleus. Both characteristics are attributed to coordination of the copper by a cysteine sulfur.
Bond energy (bond dissociation energy) Atoms in a molecule are held together by covalent bonds, and to break these bonds atoms need bond energy. The source of energy to break the bonds can be in the form of heat, electricity, or mechanical means. Bond energy is the quantity of energy that must be absorbed to break a particular kind of chemical bond. It is equal to the quantity of energy the bond releases when it forms. It can also be defined as the amount of energy necessary to break one mole of bonds of a given kind (in gas phase).
Bone imaging The construction of bone tissue images from the radiation emitted by radionuclides that have been absorbed by the bone. Radionuclides such as 18F, 85Sr, and 99mTc are introduced as complexes with specific llgands (very often phosphonate ligands) and are absorbed in the bones by metabolic activity.
Book lungs The respiratory pouches or organs of gas exchange in spiders (arachnids), consisting of closely packed blood-filled plates, sheets, or folds for maximum surface aeration and contained in an internal chamber on the underside of the abdomen. They look like the pages of a book.
Bordet, Jules (1870-1961) Belgian Bacteriologist, Immunologist Jules Bordet was born in Soignies, Belgium, on June 13, 1870. He was educated in Brussels and graduated with a doctor of medicine in 1892. Two years later he went to Paris and began work at the Pasteur Institute, where he worked on the destruction of bacteria and explored red blood cells in blood serum, contributing to the founding of serology, the study of immune reactions in bodily fluids. In 1901 he returned to Belgium to found the Pasteur Institute of Brabant, Brussels, where he served until 1940. He was director of the Belgian Institute and professor of bacteriology at the University of Brussels (1907-35).
His work in immunology included finding two components of blood serum responsible for bacteriolysis (rupturing of bacterial cell walls) and the process of hemolysis (rupturing of foreign red blood cells in blood serum). Working with his colleague Octave Gengou, Bordet developed several serological tests for diseases such as typhoid fever, tuberculosis, and syphilis. The bacteria responsible for whooping cough, Bordetella pertussis, was named for him after he and Gengou discovered it in 1906. In 1919, he received the Nobel Prize in physiology and medicine for his immunological discoveries.
He was the author of Traite de l’immunite dans les maladies infectieuses (Treatise on immunity in infectious diseases) and numerous medical publications.
Bordet was a permanent member of the administrative council of Brussels University, president of the First International Congress of Microbiology (Paris, 1930), and member of numerous scientific societies. He died on April 6, 1961.
Bottleneck effect A dramatic reduction in genetic diversity of a population or species when the population number is severely depleted by natural disaster, by disease, or by changed environmental conditions. This limits genetic diversity, since the few survivors are the resulting genetic pool from which all future generations are based.
Bovet, Daniels (1907-1992) Swiss Physiologist Daniel Bovet was born in Neuchatel, Switzerland, on March 23, 1907, to Pierre Bovet, professor of pedagogy at the University of Geneva, and Amy Babut. He graduated from the University of Geneva in 1927 and then worked on a doctorate in zoology and comparative anatomy, which he received in 1929.
During the years 1929 until 1947 he worked at the Pasteur Institute in Paris, starting as an assistant and later as chief of the institute’s Laboratory of Therapeutic Chemistry. Here he discovered the first synthetic antihistamine, pyrilamine (meplyramine). In 1947 he went to Rome to organize a laboratory of therapeutic chemistry and became an Italian citizen. He became the laboratory’s chief at the Istituto Superiore di Sanita, Rome. Seeking a substitute for curare, a muscle relaxant, for anesthesia, he discovered gallamine (trade name Flaxedil), a neuromuscular blocking agent used today as a muscle relaxant in the administration of anesthesia.
He and his wife Filomena Nitti published two important books, Structure chimique et activite phar-macodynamique des medicaments du systeme nerveux vegetatif (The chemical structure and pharmacody-namic activity of drugs of the vegetative nervous system) in 1948 and, with G. B. Marini-Bettolo, Curare and Curare-like Agents (1959). In 1957 he was awarded the Nobel Prize for physiology or medicine for his discovery relating to synthetic compounds for the blocking of the effects of certain substances occurring in the body, especially in its blood vessels and skeletal muscles.
Bovet published more than 300 papers and received numerous awards. He served as the head of the psychobiology and psychopharmacology laboratory of the National Research Council (Rome) from 1969 until 1971, when he became professor of psychobiolo-gy at the University of Rome (1971-82). He died on April 8, 1992, in Rome.
Bowman’s capsule A cup-shaped receptacle in the kidney that contains the glomerulus, a semipermeable twisted mass of tiny tubes through which the blood passes and is the primary filtering device of the nephron, a tiny structure that produces urine during the process of removing wastes. Each kidney is made up of about 1 million nephrons. Blood is transported into the Bowman’s capsule from the afferent arteriole that branches off of the interlobular artery. The blood is filtered out within the capsule, through the glomeru-lus, and then passes out by way of the efferent arteri-ole. The filtered water and aqueous wastes are passed out of the Bowman’s capsule into the proximal convoluted tubule, where it passes through the loop of Heinle and into the distal convoluted tubule. Eventually the urine passes and filters through the tiny ducts of the calyces, the smallest part of the kidney collecting system, where it begins to be collected and passes down into the pelvis of the kidney before it makes its way to the ureter and to the bladder for elimination.
Brachyptery A condition where wings are disproportionately small in relation to the body.
Brain imaging In addition to magnetic resonance imaging, which is based on the absorption by the brain of electromagnetic radiation, brain images can be acquired by scintillation counting (scintigraphy) of radiation emitted from radioactive nuclei that have crossed the blood-brain barrier. The introduction of radionu-clides into brain tissue is accomplished with the use of specific 99mTc(V) complexes with lipophilic ligands.
Brain stem (brainstem) The oldest and inferior portion of the brain that consists of the midbrain, pons, reticular formation, thalamus, and medulla oblongata,and forms a cap on the anterior end of the spinal cord. The brain stem is the base of the brain and connects the brain’s cerebrum to the spinal cord. It shares several features in common with the brain of reptiles and controls automatic and motor basic functions such as heart rate and respiration and also is the main channel for sensory and motor signals.
Artwork combining profiles of brain and head anatomy. The brain is seen sliced in half to show internal anatomy. The brain’s major area, the cerebrum, includes the folded outer layer (cerebral cortex) that produces memory, language, and conscious movement. The central space is a brain ventricle. The brain stem, at the base of the brain, controls subconscious functions like breathing. It extends downwards and connects to the spinal cord in the neck. The cerebellum (round area, at left of the brainstem) controls balance as well as muscle coordination. The head and neck blood vessels branch from the major chest vessels at bottom.
Bridging ligand A bridging ligand binds to two or more central atoms, usually metals, thereby linking them together to produce polynuclear coordination entities. Bridging is indicated by the Greek letter p appearing before the ligand name and separated by a hyphen. For an example, see femo-cofactor.
Bronchiole A series of small tubes or airway passages that branch from the larger tertiary bronchi within each lung. At the end of the bronchiole are the alveoli, thousands of small saclike structures that make up the bulk of the lung and where used blood gets reoxygenated before routing back through the heart. See also lung.
Br0nsted acid A molecular entity capable of donating a hydron to a base (i.e., a "hydron donor") or the corresponding chemical species. See also acid.
Br0nsted base A molecular entity capable of accepting a hydron from an acid (i.e., a "hydron acceptor") or the corresponding chemical species.
Brownian movement The rapid but random motion of particles colliding with molecules of a gas or liquid in which they are suspended.
Bryophytes The mosses (Bryophyta), liverworts (Hepatophyta), and hornworts (Anthocerophyta); a group of small, rootless, thalloid (single cell, colony, filament of cells, or a large branching multicellular structure) or leafy nonvascular plants with life cycles dominated by the gametophyte phase. These plants inhabit the land but lack many of the terrestrial adaptations of vascular plants, such as specialized vascular or transporting tissues (e.g., xylem and phloem).
Terrestrial bryophytes are important for soil fixation and humus buildup. In pioneer vegetation, they provide a suitable habitat for seedlings of early pioneering plants. Bryophytes are also early colonizers after fire and contribute to nutrient cycles.
Bubonic plague A bacterial disease marked by chills, fever, and inflammatory swelling of lymphatic glands found in rodents and humans. It is caused by Pasteurel-la pestis and transmitted by the oriental rat flea. The famous Black Death that devastated the population of Europe and Asia in the 1300s was a form of bubonic plague.
Budding An asexual means of propagation in which a group of self-supportive outgrowths (buds) from the parent form and detach to live independently, or else remain attached to eventually form extensive colonies. The propagation of yeast is a good example of budding.
Also a type of grafting that consists of inserting a single bud into a stock.
Buffer A molecule or chemical used to control the pH of a solution. It consists of acid and base forms and minimizes changes in pH when extraneous acids or bases are added to the solution. It prevents large changes in pH by either combining with H+ or by releasing H+ into solution.
Bulk flow (pressure flow) Movement of water due to a difference in pressure between two locations. The movement of solutes in plant phloem tissue is an example.
C3 plant The majority of photosynthetic plants that produce, as the initial steps of CO2 incorporation, a three-carbon compound, phosphoglyceric acid (PGA), as the first stable intermediate (calvin cycle). The PGA molecules are further phosphorylated (by ATP) and are reduced by nadph to form phosphoglyceralde-hyde (PGAL), which then serves as the starting material for the synthesis of glucose and fructose, which, when combined, make sucrose that travels through the plant. Velvetleaf (Abutilon theophrasti) is an example of a C3 plant.
C4 plant A small number of plants that incorporate CO2 using a carboxylase for the CO2 capture, producing a four-carbon compound (carboxylic acid) as a stable intermediary in the first step of photosynthesis. C4 plants (e.g., corn) supply CO2 for the calvin cycle.
Cage An aggregate of molecules, generally in the condensed phase, that surround the fragments formed by thermal or photochemical dissociation of a species.
Calcitonin Calcitonin is a hormone produced by the thyroid gland that acts primarily on bone. It inhibits bone removal by osteoclasts and promotes bone formation by osteoblasts; lowers blood calcium levels.
Calmodulin A Ca2+ binding protein involved in muscular contraction.
Calorie An energy measurement unit; the amount of energy required to raise the temperature of 1 g of water by 1°C. A kilocalorie (1,000 calories) is used in food science to describe the energy content of food products.
Calpain A calcium-activated neutral protease.
Calvin cycle The second major stage in photosynthesis after light reactions—discovered by chemist Melvin Calvin (1911-97)—whereby carbon molecules from CO2 are fixed into sugar (glucose) and mediated by the enzyme rubisco (ribulose-1-5-biphosphate carboxylase). It occurs in the stroma of chloroplasts. The Calvin cycle is also known as the dark reaction, as opposed to the first-stage light reactions.
CAM (crassulacean acid metabolism) A metabolic adaptation of certain plants, particularly xerophytes (desert loving, e.g., succulents), in arid areas that allows them to take up CO2 at night, not during the day, store it as organic acid (malic), and release CO2 by decarboxylation of the acids for fixing into sugar. This reduces transpirational water loss during photosynthesis. The calvin cycle occurs during the day.
Cambrian explosion A period about 530 million years ago (Cambrian age) when a large explosion of species, both in number and diversity, appeared on Earth. It lasted about 10 million years, and it is the first recorded evidence through the fossil record of larger and more complex life forms appearing.
Canadian shield A geographic area of Canada centered around Hudson Bay and composed of 2- to 3-billion-year-old igneous and metamorphic shield rock. It covers much of northern Canada.
Cancer Diseases in which abnormal cells divide and grow unchecked and can spread from the original site to other parts of the body; often fatal.
Capillary The smallest blood vessels in the circulatory system. Capillaries have thin walls that facilitate the transfer of oxygen and glucose into a cell and the removal of waste products such as carbon dioxide back out into the blood stream, to be carried away and taken out of the body via the lungs. They act as the bridge between the arteries, which carry blood away from the heart, and the veins, which carry blood back to the heart..
Capsid The outer protein coat or shell of a virus surrounding its genetic material. Also capsid bugs (capsi-dae), which number over 6,000 species and live on plants, sucking juice and damaging cultivated plants.
Carbohydrate A large class of compounds that contain carbon, hydrogen, and oxygen in a general formula of Cn(H2O)n. Classified from simple to complex, they form mono-, di-, tri-, poly-, and heterosaccha-rides. Examples include sugars (monosaccharide, di-and polysaccharides), starches, and cellulose. Carbohydrates are used as an energy source by organisms, and most are formed by green plants and are obtained by animals via food intake.
Carbon dioxide (CO2) A colorless, odorless gas that makes up the fourth most abundant gas in the atmosphere. Used by plants in carbon fixation. Atmospheric CO2 has increased about 25 percent since the early 1800s due to burning fossil fuels and deforestation. Increased amounts of CO2 in the atmosphere enhance the greenhouse effect, blocking heat from escaping into space and contributing to the warming of Earth’s lower atmosphere and affecting the world’s biota. This is a major issue currently being debated by scientists around the world.
Carbon fixation The process by which carbon atoms from CO2 gas are incorporated into sugars. Carbon fixation occurs in the chloroplasts of green plants or any photosynthetic or chemoautotrophic organism.
Carbonic anhydrase A zinc-containing enzyme (carbonate hydrolyase, carbonate dehydratase) that catalyzes the reversible decomposition of carbonic acid to carbon dioxide and water.
Carboniferous period A geological time period (360 to 280 millions of years ago) during the middle-to-late Paleozoic era. It is divided into the Pennsylvani-an period (325 to 280 millions of years ago) and the Mississippian period (360 to 325 millions of years ago).
Carbon monoxide (CO) A colorless, odorless gas that is toxic.
Carbon monoxide dehydrogenases enzymes that catalyze the oxidation of carbon monoxide to carbon dioxide. They contain iron-sulfur clusters and either nickel and zinc, or molybdopterin. Some nickel-containing enzymes are also involved in the synthesis of acetyl coenzyme A from C02 and H2.
Carbonyl group A functional group with an oxygen atom double-bonded to a carbon atom, e.g., aldehydes (joined to at least one hydrogen atom) and ketones (carbonyl group is joined to alkyl groups or aryl groups).
Carboplatin A "second generation" platinum drug effective in cancer chemotherapy, named cis-diammine (cyclobutane-1,1-dicarboxylato)platinum(II). Carboplatin is less toxic than the "first generation" antitumor drug, cisplatin.
Carboxyl group A functional group that consists of a carbon atom joined to an oxygen atom by a double bond and to a hydroxyl group; present in all carboxylic acids.
Carcinogen Any substance that can produce cancer.
Cardiac muscle One of the three muscle types (the others are skeletal and smooth); found in the walls of the heart, each rectangular heart muscle cell has one central nucleuslike smooth muscle, but it is striated like skeletal muscle. These cells are joined by intercalated discs, physical connections between the fibers of the myocardium, that relay each heartbeat through gap junctions (electrical synapses). Each strong and rhythmical contraction of the cardiac muscle is controlled by the autonomic nervous system and is involuntary.
Cardiac output The amount of blood that is pumped each minute from the left ventricle into the aorta or from the right ventricle into the pulmonary trunk.
Cardiotech A species radiolabeled with 99mTc with the formula [Tc(CNR)6]+(R=tert-butyl) known for imaging the heart after a heart attack.
Cardiovascular system The human circulatory system; the heart and all the vessels that transport blood to and from the heart.
Carnivore Any animal that eats the meat of other animals.
Carotenoids A large family of natural phytochemicals, accessory pigments found in plants (in chloroplasts) and animals that are composed of two small six-carbon rings connected by a carbon chain that must be attached to cell membranes. Their variety of colors absorb wavelengths that are not available to chlorophyll and so serve to transfer their captured energy from the sun to help in photosynthesis. Carotenoids color fruits and vegetables and give them their characteristic red, orange, and yellow colors and serve as antioxidants in human nutrition. Over 600 carotenoids are known.
The ribbon snake, a type of carnivorous tree snake in Venezuela, will eat birds and serves as a model for mimicry among caterpillars as well as a Batesian model.
Carpal bones Hand bones. The carpal bones include the navicular, lunate, pisiform, capitate, trapezium, trapezoid, hamate, and the triquetrum. They are arranged in two rows, the proximal (near the body) and the distal (near the fingers).
Carpal tunnel A small passage located below the wrist at the heel of the hand where the median nerve, the major nerve to the hand, as well as tendons that bend the fingers pass through.
Carpel The female reproductive part of the flower, including the ovary, style, and stigma.
