GLOSSARY

A  B  C  D  E  F  G  H  I  J  K  L  M
N  O  P  Q  R  S  T  U  V  W  X  Y  Z

A

Allelopathy:
The production and release of chemical substances by one species that inhibit the growth of other species of plants (Smith et al, 2000).

Antibiotic:
An antibiotic can be defined in any of the following ways:

1. relating to antibiosis,
2. prejudicial to life,
3. a soluble substance derived from a mold or bacterium that inhibits the growth of other microorganisms, or
4. relating to such an action (Dirckx, 1997).

Antibiotic Enterocolitis:
Enterocolitis caused by oral administration of broad spectrum antibiotics, resulting from overgrowth of antibiotic resistant staphylococci or yeasts and fungi, when the normal fecal gram-negative organisms are suppressed, resulting in diarrhea or pseudomembranous disease (Dirckx, 1997).

Antibiotic resistance:
Indicating microorganisms that continue to multiply although exposed to antibiotic agents (Dirckx, 1997). Though in the broadest of meanings, antibiotic resistance is, simply, a resistance to an antibiotic.

Antibiotic sensitivity:
Microbial susceptibility to antibiotics (Dirckx, 1997).

See also: minimal inhibitory concentration.

Anuria:
Absence of urine formation (Dirckx, 1997).

Asthma:
Originally, a term used to mean "difficult breathing"; now used to denote bronchial asthma (Dirckx, 1997).

See also: atopic asthma, atopy, bronchial asthma, bronchitic asthma, byssinosis, cardiac asthma, catarrhal asthma, cotton-dust asthma, dust asthma, extrinsic asthma, food asthma, hay asthma, intrinsic asthma, miller's asthma, miner's asthma, nervous asthma, reflex asthma, spasmodic asthma, steam-fitter's asthma, stripper's asthma, summer asthma.

Astrocytosis:
A proliferation of astrocytes owing to the destruction of nearby neurons during an episode of hypoxia or hypoglygemia.

Ataxia:
A failure of muscular coordination or irregularity of muscular action.

Atmosphere:
The whole mass of air, or mixture of gases, surrounding the earth (Clark, 1985; Millar, 1994). Includes layers such as the troposhere (0 to ~6-18km from earth), stratosphere (~6-18km to ~50km from earth), mesosphere (~50km to ~80km from earth), and thermosphere (~80km+ from earth). Each layer is divided from the next by a region refered to as a pause, eg. the tropopause divides the troposphere from the stratosphere. See figure of the layers of the atmosphere below.

                  The Layers of the Atmosphere

Atopic asthma:
Bronchial asthma due to atopy (Dirckx, 1997).

Atopy:
A genetically determined state of hypersensitivity to environmental allergens. Type I allergic reaction is associated with the IgE antibody and a group of diseases, principally asthma, hay fever, and atopic dermatitis (Dirckx, 1997).

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B

Bacteriocinogenic plasmids:
Bacterial plasmid's responsible for the elaboration of bacteriocins (Dirckx, 1997).
Synomyns: bacteriocin factors, bacteriocinogens.

Bacteriostatic antibiotics:
Antibiotics which inhibit bacterial growth, but do not actually kill the bacteria. Successful treatment therefore requires the host's immune system to clear the pathogen. Treatment is compromised when the antibiotics are stopped before the pathogen has been completely cleared (Dirckx, 1997).

Bactericidal antibiotics:
Antibiotics which kill bacteria with or without lysis of the target cell (Dirckx, 1997).

Biodiversity:
The existence of a wide variety of species (species diversity) or other taxa of plants, animals and microorganisms in a natural community or habitat, or of communities within a particular environment (ecological diversity) or of genetic variation within a species (genetic diversity) (Martin et al, 2000).

See Eco-Concepts page for more in depth discussion.

Bioengineering:
The use of artificial tissues, organs, or organ components to replace parts of the body that are damaged, lost or malfunctioning (Martin et al, 2000).

Broad spectrum antibiotic:
An antibiotic having a wide range of activity against both Gram-positive and Gram-negative organisms (Dirckx, 1997).

Bronchial asthma:
A condition of the lungs in which there is widespread narrowing of airways, varying over short periods of time either spontaneously or as a result of treatment, due in varying degrees to contraction (spasm) of smooth muscle, edema of the mucosa, and mucus in the lumen of the bronchi and bronchioles; these changes are caused by the local release of spasmogens and vasoactive substances (e.g., histamine, or certain leukotrienes or prostaglandins) in the course of an allergic process (Dirckx, 1997).

Bronchitic asthma:
Asthma precipitated by bronchitis (Dirckx, 1997).
Synonym: catarrhal asthma.

Byssinosis:
Obstructive airway disease in people who work with unprocessed cotton, flax, or hemp; caused by reaction to material in the dust and thought to include endotoxin from bacterial contamination. Sometimes called "monday morning asthma" since patients improve when away from work on the weekend.
Synonyms: cotton-dust asthma, cotton-mill fever, mill fever (Dirckx, 1997).

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Carbon cycle:
The process by which carbon is recycled in the ecosystem.

See Eco-Concepts page for more in depth discussion.

Cardiac asthma:
An asthmatic attack, the broncho constriction being secondary to the pulmonary congestion and edema of left ventricular failure (Dirckx, 1997).

Carrying capacity:
The maximum biomass which an area can support for an indefinite period of time (Clark, 1985).

See Eco-Concepts page for more in depth discussion.

Catarrhal asthma:
Asthma precipitated by bronchitis (Dirckx, 1997).
Synonym: bronchitic asthma.

Chemical Cycles:
Chemical cycles are those processes by which various chemicals are recycled in the ecosystem.

See Eco-Concepts page for a more in depth discussion, including figures of the major cycles.

Cholera:
Cholera can be defined in two ways:

1. Formerly, a nonspecific term for a variety of gastrointestinal disturbances.
2. An acute epidemic infectious disease caused by the bacterium Vibrio cholerae, now occurring primarily in Asia. A soluble toxin elaborated in the intestinal tract by the bacterium activates the adenylate cylase of the mucosa, causing active secretion of an isotomic fluid resulting in profuse watery diarrhea, extreme loss of fluid and electrolytes, and dehydration and collapse, but no gross morphologic change in the intestinal mucosa (Dirckx, 1997).

This disease spreads through contaminated drinking water and food (EHP, 1999).
Synonym: Asiatic cholera.

Chorea:
Any of various disorders of the nervous system that are characterized by a continuous sequence of rapid, jerky movements that appear choreographed but are involuntary.

Chromosome aberration/mutation:
Any deviation from the normal number or morphology of chromosomes; also the phenotypic consequences thereof (Dirckx, 1997).

Climate:
The characteristic pattern of weather elements in an area over a period of time (usually average of 30 years). The weather elements include, among others, temperature, rainfall, humidity, solar, insolation, and wind. Climate is controlled by the following factors: latitude (incoming solar radiation), distribution of land and water masses, altitude and topography, location of area in relation to ocean currents (Martin et al, 2000).

Climate change:
A deviation from the average climate.

See Eco-Concepts page for more in depth discussion.

Coliform bacteria:
Common name for Escherichia coli that is used as an indicator of fecal contamination of water, measured in terms of coliform count. Occasionally used to refer to all lactose-fermenting enteric bacteria (Dirckx, 1997).

Commons resource:
Also known as a common property resource, this is a resource jointly owned and used by society at large, to which any member has free access (Clark, 1985).

See Eco-Concepts page for a more in depth discussion, including figures of the major cycles.

Conjugative plasmid:
A plasmid that can effect its own intercellular transfer by means of conjugation; this transfer is accomplished by a bacterium being rendered a donor, usually with specialized pili.
Synonyms: infectious plasmid, transmissible plasmid (Dirckx, 1997).

Cotton-dust asthma:
Obstructive airway disease in people who work with unprocessed cotton, flax, or hemp; caused by reaction to material in the dust and thought to include endotoxin from bacterial contamination. Sometimes called "monday morning asthma" since patients improve when away from work on the weekend (Dirckx, 1997).
Synonym: byssinosis.

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D

Dementia:
An organic mental disorder characterized by loss of memory,impairment of judgement and abstract thinking and changes in personality.

Dengue fever (or Dengue):
A disease of tropical and subtropical regions that occurs epidemically, is caused by dengue virus, a member of the family Flaviviridae.

There are 4 antigenic types, and they are transmitted by a mosquito of the genus Aedes (usually A. aegypti, but frequently A. albopictus).

Four grades of severity are recognized: grade I, fever and constitutional symptoms; grade II, grade I plus spontaneous bleeding (of skin, gums, or gastrointestinal tract); grade III, grade II plus agitation and circulatory failure; grade IV, profound shock (Dirckx, 1997).

Disease:
Disease can be defined in three ways:

1. An interruption, cessation, or disorder of body functions, systems, or organs.
   Synonym: illness, morbus, sickness.
2. A morbid entity characterized usually by at least two of these criteria: recognized etiologic agent(s), identifiable group of signs and symptoms, or consistent anatomical alterations.
   See also: syndrome.
3. Literally, dis-ease, the opposite of ease, when something is wrong with a bodily function (Dirckx, 1997).

Dust asthma:
Asthma aggravated by inhalation of dust, especially seen as occupational disease resulting from cotton dust (Dirckx, 1997).

Dysesthesia:
An impairment or distortion of any sense, especially that of touch; an abnormal sensation in which normal stimuli may produce an unpleasant sensation, such as itching or burning.

Dystonia:
Any abnormality of muscle tone or tension.

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E

Ecological footprint:
A measure of consumption each human places on the environment they live within. The ecological footprint of each modern city dweller has been figured at 12 acres - about three city block squares (Callenbach, 1998).

See Eco-Concepts page for more in depth discussion.

Ecology:
The study of the interrelationships between organisms and their natural environment, both living and nonliving (Martin et al, 2000).

Ecosystem:
A biological community and the physical environment associated with it. Nutrients pass between the different organisms in an ecosystem in definite pathways up through the food chain. Organisms in the food chain are classified on the basis of their position in an ecosystem into various trophic levels. Nutrients and energy move around ecosystem in loops or cycles (Martin et al, 2000).

Ecosystem Health:
A systematic approach to the preventative, diagnostic, and prognostic aspects of ecosystem management, and to the understanding of relationships between ecosystem health and human health. It seeks to understand and optimize the intrinsic capacity of an ecosystem for self-renewal while meeting reasonable human goals. It encompasses the role of societal values, attitudes and goals in shaping our conception of health at human and ecosystem scales.

Energy spectrum:
Also known as the electromagnetic spectrum, it is the range of wavelengths of energy radiated by electromactetic waves. The spectrum ranges from gamma rays (the shortest wavelength) to radiowaves (the longest wavelength), and includes radar, infra-red, X, and ultra-violet rays as well as visible light (Clark, 1985).

The Energy or Electromagnetic Spectrum

See also: ultraviolet radiation.

Enterocolitis:
Inflammation of the mucous membrane of a greater or lesser extent of both small and large intestines.
Synonym: coloenteritis (Dirckx, 1997).

Enterotoxin:
A cytotoxin specific for the cells of the intestinal mucosa.
Synonym: intestinotoxin (Dirckx, 1997).

Environment:
The physical, chemical, and biological condition of the region in which an organism lives (Martin et al, 2000).

Enterobacteriaceae:
A family of aerobic, facultatively anaerobic, nonsporeforming bacteria (order Eubacteriales) containing Gram-negative rods(Dirckx, 1997).

Epidemiology:
The study of the various factorsinfluencing the occurrence, distribution, prevention and control of disease, injury and other health-related events in a defined human population.

European Commission:
The executive body of the European Union which has the right to initiate legislation.

European Union:
An organization of 15 European countries, whose mission is:"to organize relations between Member states and between their peoples in a coherent manner on the basis of solidarity".

Eutrophication:
Physical, chemical, and biological changes that take place after a latke, an estuary, or a slow-flowing stream receives inputs of plant nutrients - mostly nitrates and phosphates - from natural erosion and runoff from the surrounding land basin (Millar, 1994).

Evolution:
The gradual process by which the present diversity of life arose from the earliest and most primitive organisms (Martin et al, 2000).

See Eco-Concepts page for more in depth discussion.

Extrinsic asthma:
Bronchial asthma resulting from an allergic reaction to foreign substances, such as inhaled particles, vapors, or gases, or ingested foods, beverages, or drugs (Dirckx, 1997).

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F

F plasmid:
The prototype conjugative plasmid associated with conjugation in the K-12 strain of Escherichia coli.
Synonyms: F agent, F factor, F genote, F-genote, fertility agent, fertility factor, sex factor (Dirckx, 1997).

Fimbriae:
Any fringelike structure.
Synonym: pilus (Dirckx, 1997).

Food asthma:
Asthma caused by allergic reaction to a dietary item (Dirckx, 1997).

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G

Genotype:
The sum of hereditary, or genetic, information carried by an individual (Smith et al, 2000).

See also: phenotype.

Global warming:
The greenhouse effect acts to warm the plant and increase average global temperatures. This is seen as a major environmental hazard as average temperatures rise, leading to a possible change in weather patterns and agricultural output. This also may lead to melting of the polar ice-cap and a corresponding rise in sea level (Martin et al, 2000).

See also: climate change.

Greenhouse effect:
An effect occurring in the atmosphere because of the presence of certain gases that absorb infrared radiation. Light and ultraviolet radiation from the sun are able to penetrate the atmosphere and warm the earth surface. This energy is re-radiated as infrared radiation, which because of its longer wavelength, is absorbed by such substances as carbon dioxide. The overall effect is that the average temperature of the earth and its atmosphere is increasing. The effect is similar to that occurring in a greenhouse, where light and long-wavelength ultraviolet radiation can pass through the glass into the greenhouse but the infrared radiation is absorbed by the glass and part of its is re-radiated into the greenhouse. The greenhouse effect results in climate change (Martin et al, 2000).

See Eco-Concepts page for more in depth discussion.

Ground level ozone:
Also known as troposheric ozone, ground level ozone occurs near the earth's surface in the troposphere (See atmosphere). In the troposphere, ozone is a natural constituent of the air we breathe, however at critical increased concentrations, it becomes a harmful pollutant. In natural (unpolluted) conditions, ozone is formed in the troposphere when UV radiation that reaches the Earth’s surface converts nitrogen dioxide to nitric oxide and an oxygen radical. The oxygen radical may subsequently react with diatomic oxygen to form ozone. Ozone is then broken down when it reacts with nitric oxide, forming diatomic oxygen and nitrogen dioxide.

Activities which increase the atmospheric concentrations of nitrogen oxides consequently affect an increase in ozone, thus upsetting the balance in the natural nitrogen-ozone cycle. Natural sources of ground level increases in ozone include lightening and volcanic activity. Anthropogenic influences which result in increased ozone concentrations embody any activities that increase the levels of nitrogen oxides in the air. The most important example is the burning of fossil fuels for industrial, energy and transportation purposes. In addition to increases in nitrogen oxides, volatile organic compounds also serve to elevate the ozone concentrations in the atmosphere by reacting more quickly with nitric oxide. Some notable sources of volatile organic compounds include automobile exhausts, chemical manufacturing and petroleum refining.

In regions of or near high industrial or automobile activity, the greatest threat of increased ozone levels is the elevated production of photochemical smog, of which ozone is the prime component. The problems associated with smog are particularly contentious since the air-borne pollutants may transcend political borders. Consequently, the primary pollutants responsible for ozone formation may be borne in a region other than the one eventually disturbed. For example, northeasterly winds may sweep pollutants from industrialized U.S. centres into Canadian territory. As a result, ozone concentrations in rural areas of London may be higher than in the nearby urban centre of Detroit. Unfortunately, it is difficult to assert responsibility for the resultant debilitating effects of these pollutants on the original sources (see commons resources).

Ozone exerts negatively affects agriculture, forestry, biodiversity, human health and many other areas of concern to humans.

See also: ozone, ozone layer.

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H

Habitat:
The place in which an organism lives, which is characterized by its physical features or by its dominant plant types (Martin et al, 2000).

Hay asthma:
An asthmatic stage of hay fever (Dirckx, 1997).

Health:

1. The state of the organism when it functions optimally without evidence of disease or abnormality.
2. A group's capacity to cope with all the circumstances of living is at an optimum level.
3. A state characterized by anatomical, physiological, and psychological integrity, ability to perform personally valued family, work, and community roles; ability to deal with physical, biological, psychological and social stress; a feeling of well-being; and freedom from the risk of disease and untimely death (Dirckx, 1997).

From the Old English hal, meaning whole, the term has been variously defined among health specialists. In 1948, the World Health Organization described health as "a state of complete physical, mental, and social well-being and not merely the absence of disease." This definition was, in turn, criticized as unquantifiable. In 1984, WHO advanced a revised statement that any measure of health must take into account "the extent to which an individual or a group is able to realize aspirations and satisfy needs, and to change or cope with the environment." Health in this sense is seen as a "resource for everyday life." Health also involves an ability to perform within society, and to accommodate stresses, whether physical or mental. From an ecological viewpoint, the relative health of a group is evaluated according to whether that group might sustain its existence over time without major disruption to its own way of life or to the environment within which it functions (Dirckx, 1997).

Hemolytic uremic syndrome:
Hemolytic anemia and thrombocytopenia occurring with acute renal failure. In children, characterized by sudden onset of gastrointestinal bleeding, hematuria, oliguria, and microangiopathic hemolytic anemia; in adults, associated with complications of pregnancy following normal delivery, or associated with oral contraceptive use or with infection (Dirckx, 1997).

Hemorrhagic Colitis:
A disease characterised by severe abdominal cramps and bloody diarrhea (Dirckx, 1997, Volk et al, 1996).

Horizontal Transmission:
The transmission of a virus, parasite or other pathogen from one individual or one cell to another within the same generation, as opposed to vertical transmission through the germ line.

Hydrological cycle:
The process by which water, in liquid, solid and gaseous states, is cycled through the ecosystem.

See Eco-Concepts page for more in depth discussion.

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I

Iatrogenic:
Describing any adverse condition that is a reaction to treatment by physicians, especially to infections transmitted during therapy.

Illness:
(Dirckx, 1997).

Immunocytochemistry:
A field of chemisrty that specializes in the study of the chemical activity occurring in association with immunological phenomena.

Infectious plasmid:
See conjugative plasmid.

Intrinsic asthma:
Bronchial asthma in which no extrinsic causes can be identified, and which is assumed to be due to an endogenous process, possibly allergic (Dirckx, 1997).

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J

K

L

Leptospirosis:
Infection with Leptospira interrogans. Infection can result in anicteric leptospirosis, which is an infection with one of the species of the Leptospira group, usually mild, with limited liver and kidney involvement, as opposed to Weil's disease. Infection may also result in the clinical syndrome leptospirosis icterohemorrhagica or icterohemorrhagic fever. This disease results from infection with the variety of Leptospira interrogans serotype known as icterohemorrhagiae, characterized by fever, jaundice, hemorrhagic lesions, azotemia, and central nervous system manifestations (Dirckx, 1997).

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M

Malaria:
A disease caused by the presence of the sporozoan Plasmodium in human or other vertebrate red blood cells, usually transmitted to humans by the bite of an infected female mosquito of the genus Anopheles that previously sucked the blood from a person with malaria. Human infection begins with the exoerythrocytic cycle in liver parenchyma cells, followed by a series of erythrocytic schizogenous cycles repeated at regular intervals; production of gametocytes in other red cells provides future gametes for another mosquito infection; characterized by episodic severe chills and high fever, prostration, occasionally fatal termination (Dirckx, 1997).

Microangiopathic hemolytic anemia:
Hemolysis due to narrowing or obstruction of small blood vessels usually due to inflammation, causing fragmentation and distortion in the shape of red blood cells (Dirckx, 1997).

Microbes:
Bacteria, fungi, protozoa, algae, and viruses (Needham et al, 2000).

Microvilli:
Minute projections of cell membranes that greatly increase the surface area; microvilli form the striated or brush borders of certain cells (Dirckx, 1997).

Miller's asthma:
Asthma caused by flour or grain allergens (Dirckx, 1997).

Miner's asthma:
The dyspnea of anthracosis or other pneumoconioses in miners (Dirckx, 1997).

Minimal Inhibitory Concentration:
The lowest concentration of antibiotic which prevents visible growth of an organismafter 18-24 hours of incubation. (Lorian,V. 1996).

Monoculture:
One crop grown densely over an extensive area. This agricultural practice has required an increase in the use of pesticides, as monoculture provides an ideal opportunity for crop pests. Requires vast amounts of land, resulting in the destruction of many natural habitats. Deforestation has resulted from the clearing of forests for crop production and cattle rearing (Martin et al, 2000).

See also: polyculture.

Morbus:

Myoclonus:
A brief, shocklike contraction of a muscle or group of muscles.

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N

Natural selection:
The process by which new species evolve when influenced by selective pressure (Martin et al, 2000). Natural selection occurs when the natural factors of environmental resistance tend to eliminate those members of a population that are least well adapted to cope and thus, in effect, select those best adapted for survival and reproduction (Nebel et al, 1998).

See Eco-Concepts page for more in depth discussion.

Nervous asthma:
Asthma precipitated by psychic stress (Dirckx, 1997).

Nitrogen cycle:
The process by which nitrogen is recycled in the ecosystem.

See Eco-Concepts page for more in depth discussion.

Nonconjugative plasmid:
A plasmid that cannot effect conjugation and self-transfer to another bacterium (bacterial strain); transfer depends upon mediation of another (and conjugative) plasmid (Dirckx, 1997).

Non-renewable resources:
A resource, assessed to be finite and which, once used, can be replaced only after a considerable span of geological time (Clark, 1985).

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O

Ozone:
Ozone (O3) is the highly-reactive, triatomic from of oxygen. However, unlike diatomic oxygen (also known as oxygen gas, O2), which is odorless and colorless, ozone has a strong scent and is blue in color. Furthermore, diatomic oxygen is significantly more common; the ratio of O2:O3 molecules in the atmosphere is aproximately 2,000,000:3.

Ozone occurs in both the tropospheric and the stratospheric regions of the atmosphere.

See also: ground level ozone

Ozone layer:
Also known as stratospheric ozone, the ozone layer is located approximately 30 to 50km from the surface of the earth in the stratosphere.

See also: atmosphere, ground level ozone

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P

PAHO:
The Pan American Health Organization.

Paresis:
Partial or incomplete paralysis characterized by weakness and reduction in muscular power.

Phenotype:
The external, observable expression of the genotype (Smith et al, 2000).

Phosphorus cycle:
The process by which phosphorus is recycled in the ecosystem.

See Eco-Concepts page for more in depth discussion.

Pilus:
Pilus can be defined in two way (Dirckx, 1997):

1. One of the fine, keratinized filamentous epidermal growths arising from the skin of the body of mammals except the palms, soles, and flexor surfaces of the joints; the full length and texture of the hair varies markedly in different body sites.
   Synonyms: crinis, hair.
2. A fine filamentous appendage, somewhat analogous to the flagelium, that occurs on some bacteria. Pili consist only of protein and are shorter, straighter, much more numerous, and may be chemically similar to flagella; specialized pili (F pili, I pili, and other conjugative pili) seem to mediate bacterial conjugation.
   Synonym: fimbria.

Plasmid:
A genetic particle physically separate from the chromosome of the host cell (chiefly bacterial) that can stably function and replicate; not essential to the cell's basic functioning.
Synonyms: extrachromosomal element, extrachromosomal genetic element, paragene (Dirckx, 1997).

Plasmids are transmitted between bacteria by conjugation. This one-way transfer of genetic information is not species-specific, explaining how many different species of bacteria share similar resistance traits (Volk et al, 1996). The extracellular factors that encourage gene transfer are barely understood. There are some pheromones that influence transfer (Davies, 1997), but their role has been ill defined. There has been some work to indicate that antibiotics themselves promote the transfer of resistance genes (Clewell, 1993; Stevens et al, 1993). Plasmids acquire resistance genes from transposons and gene cassettes.

Plasmids can acquire resistance genes from gene cassettes. Gene cassettes encode a specific resistance gene. Integrons are required to provide the receptor site for the gene cassette as well as the enzyme that catalyzes the mobility of the gene (Hall, 1997). Both the gene cassettes and their corresponding integrons are mobile. By incorporating into a broad-host-range plasmid, the resistance traits encoded by gene cassettes are shared among bacterial species (Hall, 1997).

Polyculture:
A system of agriculture, whereby, different crops are planted at the same time in the same space.

See also: monoculture.

Polymerase chain reaction:
An enzymatic method for the repeated copying and amplification of the two strands of DNA of a particular gene sequence.

This reaction exploits the capacity of DNA polymerase to assemble new DNA. The polymerase is added to a mixture of free nucleotides and primers. Primers are specially prepared units containing both RNA and DNA with a free terminus where the polymerase will react. The short sequence of DNA to be amplified is flanked by two primers. Once the reaction begins, the polymerase churns out multiple copies of the target sequence, which can then be recovered for analysis (Dirckx, 1997).

Porins:
Any of a class of proteins that form water-filled channels across cell membranes (Martin et al, 2000).

Prion:
An infectious particle that does not contain DNA or RNA, but consists of only a hydrophobic protein; believed to be the smallest infectious particle.

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Q

R

R plasmids:
See resistance plasmids.

Reflex asthma:
Asthma occurring as a reflex in disease of the viscera, the nose, or other parts (Dirckx, 1997).

Render:
To melt down or to extract by melting. or, to treat so as to convert into industrial fats and oils or fertilizer.

Renewable resources:
A resource that can potentially last as long as the sun is around because it can be renewed fairly rapidly through natural processes.
Examples include forest trees, land grasses, and wild animals (Millar, 1994).

Resistance plasmids:
Plasmid's carrying genes responsible for antibiotic (or antibacterial drug) resistance among bacteria (notably Enterobacteriaceae); they may be conjugative or nonconjugative plasmid's, the former possessing transfer genes (resistance transfer factor) lacking in the latter.
Synonyms: R factors, R plasmids, resistance factors, resistance-transferring episomes (Dirckx, 1997).

Resources:
A source of supply or support, the means of meeting a need or deficiency, especially an economic or social need or deficiency (Clark, 1985).

See Eco-Concepts page for more in depth discussion.

Ruminant:
An animal that chews its cud; having even toed hooves and a four-chambered stomach, such as a cow, buffalo, goat, deer or llama.

Rural area:
Geographical area with a population of less than 2,500 people per unit of area. The number of people used in this definition may vary in different countries (Millar, 1994).

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S

Scale:
Scale can be defined as;

1. A level of representation of reality, the proportion of a representation to the object it represents, or
2. An ordered series of graduated quantities, values, degrees, or
3. relative magnitude (Clark, 1985).

See Eco-Concepts page for more in depth discussion.

Selective pressure:
The extent to which organisms possessing a particular characteristic are either eliminated or favoured by environmental demands. It indicates the degree of intensity of natural selection (Martin et al, 2000). Organisms may respond to selective pressure by adapting (natural selection), migrating or becoming extinct.

See also: evolution, natural selection.

See Eco-Concepts page for more in depth discussion.

Spasmodic asthma:
Asthma due to spasm of the bronchioles (Dirckx, 1997).

Steam-fitter's asthma:
Asthma associated with asbestosis acquired by exposure to asbestos-insulated heating and plumbing components (Dirckx, 1997).

Stratospheric ozone:
See the ozone layer.

Stripper's asthma:
Asthma associated with byssinosis (Dirckx, 1997).

Sulfur cycle:
The process by which sulfur is recycled in the ecosystem.

See Eco-Concepts page for more in depth discussion.

Summer asthma:
Asthma associated with hay fever or allergy to summer vegetation (Dirckx, 1997).

Sustainable society:
Society based on working with nature by recycling and reusing discarded matter, by preventing pollution, by conserving matter and energy resources through reducing unnecessary waster and use, by not degrading renewable resource, by building things that are easy to recycle, reuse and repair, by not allowing population size to exceed the carrying capacity of the environment, and by preserving biodiversity (Millar, 1994).

Sustainable economy:
Economic system in which the number of people and the quantity of goods are maintained at some constant level. This level is ecologically sustainable over time and meets at least the basic needs of all members of the population (Millar, 1994).

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T

Thrombocytopenia:
A condition in which there is an abnormally small number of platelets in the circulating blood.
Synonym: thrombopenia (Dirckx, 1997).

Thrombocytopenic purpura (TPP):
A systemic illness characterized by extensive ecchymoses and hemorrhages from mucous membranes and very low platelet counts; resulting from platelet destruction by macrophages due to an antiplatelet factor; childhood cases are usually brief and rarely present with intracranial hemorrhages, but adult cases are often recurrent and have a higher incidence of grave bleeding, especially intracranial (Dirckx, 1997).

Transport antibiotic:
A substance that makes biomembranes permeable to certain ions (Dirckx, 1997).

Transmissible plasmid:
See conjugative plasmid.

Transposons:
Transposons are discrete genetic units that translocate from one from one bacterial genome to another. Transposons should not be confused with plasmids, since they are incapable of autonomous replication. Transposons have special sequences at their terminals that allow them to integrate into other strands of DNA - transposition (Volk et al, 1996). Plasmids can obtain new resistance genes by transposition (Hall, 1997). Once captured by a plasmid, the transposon can be spread to many different bacteria by conjugation.

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U

Ultraviolet radiation:
UV radiation, which falls between x-rays and visible light on the electromagnetic spectrum, is divided into three types, according to wavelength. These are: UVA (320-400nm), UVB (290-320), and UVC (200-290nm) (Clark, 1985).

See also: energy spectrum.

Ungulate:
Any hoofed mammal.

Urban area:
Geographic area within a population of 2,000 or more people. The number of people used in this definition may vary with some countries setting the minimum number of people anywhere from 10,000 to 50,000 (Millar, 1994).

UV:
See ultraviolet radiation.

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V

Vector:

Vector Shift:

Vero cells:
A cell line developed from African green monkey nephrocytes (Volk et al, 1996).

Vertical Transmission:
The transmission of genetic material from parent cells or organisms to their offspring, utilizing natural hereditary mechanisms such as mitosis, meiosis and fertilization, as contrasted with induction and infection between organisms or cells of the same generation.

W

Western Blot:
A method for identifying proteins in a complex mixture; separated proteins are transferred from a gel medium to a protein-binding nitrocellulose sheet for analysis.

X

Y

Z

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