spore

1. A small, usually single-celled reproductive body that is highly resistant to desiccation and heat and is capable of growing into a new organism, produced especially by certain bacteria, fungi, algae, and nonflowering plants.
2. A dormant nonreproductive body formed by certain bacteria in response to adverse environmental conditions.

To produce spores.

[Greek sporā, seed.]

The resting state of some bacteria; thick-walled and highly resistant to heat. Under suitable conditions they germinate to produce bacteria. Spore-forming bacteria are a health hazard because they can survive pasteurization and sterilization.

noun

A propagative part of a plant: seed, tuber. See start/end.

1. a reproductive unit of some genera of fungi and protozoa. 2. a form assumed by some bacteria that is resistant to heat, drying, and chemicals. Diseases caused by spore-forming bacteria include anthrax, botulism, gas gangrene, and tetanus.

For more information on spore, visit Britannica.com.

A spore is a hard casing that contains the genetic material of those bacteria and other microorganisms that are able to form the structure. This physically and chemically resilient package protects the genetic material during periods when the environmental conditions are so harsh that the growing form of the microbe would be killed.

The effect of temperature on bacterial and spore survival provides a good example of the resilience of bacterial spores. Temperatures of 80 to 90° Celsius (176–194°F) typically kill bacteria that are growing and dividing within minutes. These high temperatures cause structural components of the bacteria to dissolve, and strands of genetic material to separate from one another. A group of bacteria known as thermophilic bacteria can survive these temperatures, but temperatures of 120°C (248°F) kill even thermophiles. In contrast, spores can survive exposure to 120°C for several hours.

Spores of bacteria that subsequently could be revived into the growing form have been recovered from materials that are over a century old. Thus, spores offer an extraordinary form of protection to bacteria. Anthrax spores that could germinate into living bacteria were recovered on Gruinard Island, an island off the coast of Scotland that was used for biological weapons testing by the British government during World War II.

Spores are noteworthy in terms of security because of the threat they pose in the hands of terrorists. Bacillus anthracis, the bacterium that causes anthrax, is a spore former. The spores are very light and tiny. As a result, they can be readily dispersed through the air and can be easily inhaled into the lungs. The resulting lung infection, which is called inhalation anthrax, is almost always fatal without prompt medical treatment. Anthrax spores were used as a mechanism of bioterrorism to target United States citizens by deliberate dispersal in the mail system in late 2001.

Another prominent example of a bacterial spore former of concern is Clostridium botulinum. The bacterium and the spore are widespread in nature; for example, they are a common inhabitant of the soil. This bacterium can also survive in canned foods for extended time periods, even when the food has been heated or is acidic. When the food is eaten, the dormant bacteria begin to grow again and produce a variety of potent toxins that disrupt the nervous system, causing serious illness.

The contamination of foods by terrorists is a significant security concern, especially in the United States. Because the spores are hardy and can be transported virtually undetected, they could be taken to food plants or supermarkets, where the food could be contaminated. The spores would survive to cause illness.

Other microorganisms of human concern that form spores include protozoa (e.g., Microsporidia) and fungi (e.g., Actinomycetes).

Formation of bacterial spores. The multistep process of forming a spore is known as sporulation. The process begins when a bacterium senses that the environmental conditions are becoming life threatening. Bacteria are equipped with a whole battery of sensing proteins and other compounds that monitor environmental conditions of temperature, pH of the surrounding fluid, water content, and availability of food, as some examples. After monitoring the environment for a period of time, the deteriorating conditions trigger the microbe to begin the change from a growing and dividing cell to a dormant spore.

The genetic material of the bacterium is duplicated. Then, the membrane coat that surrounds the inside of the bacterium pinches inward until the ends of the inward growing membrane meet. This isolates one of the copies of the genetic material from the remainder of the bacterium. This smaller cell is called a daughter cell. The remainder of the bacterium is called the mother cell.

In the next stage of spore formation, the membrane that surrounds the mother cell surrounds the daughter cell. This creates a daughter cell that is surrounded by two layers of membrane. Between these two membranes a think layer of a rigid material forms. This layer is called peptidoglycan. Peptidoglycan is normally present in the bacterial cell wall, but not in nearly the same amount. The thick peptidoglycan makes the double membrane layer very tough and hard to break apart. Finally, this tough membrane is coated on the outer surface by proteins. The proteins are also resistant to breakage.

The remnants of the mother cell dissolve away leaving the spore. The spore is essentially in hibernation. There is very little chemical activity. Nevertheless, the spore is able to monitor the external environment and, when conditions are sensed as being more favorable, the conversion from the spore form to the growing organism begins.

The threat from spores. The threat from spores, particularly anthrax spores, lies in their small size and powdery texture once they have been dried. As shown in the anthrax attacks in the United States in 2001, anthrax spores can be delivered to someone in a letter. The spores escape detection using methods like an x-ray. When the letter is opened, the spores can be dispersed in the air and breathed in.

Studies in animal models have shown that even the inhalation of a few spores is enough to cause an infection. The lung is an ideal environment for the anthrax bacterium. Food is available and the atmosphere is warm and moist. When the spores germinate into growing bacteria, the resulting infection can feel similar to the flu at first. Thus, a victim may not seek treatment, believing that the illness will pass in a few days. By the time the true nature of the infection is discovered, the infection can be so advanced as to be fatal.

Anthrax spores could also potentially be dispersed from an airplane or a balloon. Indeed, the terrorists responsible for the September 11, 2001 attacks on the World Trade Center and the Pentagon had explored the use of crop dusting aircraft. Models developed by the U.S. government have predicted that a few hundred pounds of anthrax spores released upwind of Washington, D.C. could cause at least several hundred thousand deaths within a few days.

The growing of the amounts of bacteria necessary to prepare large amounts of powdered spores and the preparation of the spores is not an easy task. Nonetheless, many microbiologists are capable of the task, and the construction of a facility that is large enough to house the needed equipment is not overly difficult. In the past century, nations including the U.S. and Russia had active anthrax weaponization programs. Prior to Operation Iraqi Freedom, Iraq was suspected of having an anthrax weapons development program.

Protection from spores. The threat posed by the use of spores in the mail is difficult to counter. Researchers are working to develop sensors that detect the spores, based on the reaction of antibodies with target proteins on the surface of the spores. However, such detection requires physical contact with the spores. Methods that do not require the opening of letters, such as irradiation, are being tested and refined in the field and in the laboratory.

Another tact is the use of compounds that can destroy the spore. For example, in 2002, researchers discovered that an enzyme called PlyG lysin will chemically crack apart the spore coat. The spore contents are released and disintegrate. Until such sophisticated detection and protection methods are perfected, the treatment of a site contaminated with spores will continue to include the use of bleach.

Further Reading

Books

Fischetti, Vincent, Richard P. Novick, Joseph J. Ferretti, and Danile A. Portnoy. Gram-Positive Pathogens. Washington: American Society for Microbiology Press, 2000.

Storz, Gisela, and Regine Hengge-Aronis. Bacterial Stress Responses. Washington: American Society for Microbiology Press, 2000.

Caipo, M.L., S. Duffy, L. Zhao, et al."Bacillus megaterium Spore Germination is Influenced by Inoculum Size." Journal of Applied Microbiology. no. 92 (2002): 879–84.

Electronic

American Society for Microbiology. "Microbial Spore Formation." Microbe.org. 1999. <http://www.microbe.org/microbes/spores.asp>(10 January 2003).

A reproductive cell or group of cells, produced by some plants, that is capable of developing into an adult plant without combining with another reproductive cell. Plants also produce sperm cells. The spores of nonflowering plants are analogous to the seeds of flowering plants. (See asexual reproduction; compare sexual reproduction.) Fungi and algae typically reproduce by means of spores that are carried by the wind or some other agency to a new location for growth.

1. a refractile, oval or spherical body formed within bacteria, especially Bacillus and Clostridium spp., usually under adverse conditions such as nutritional deprivation, and which is regarded as a fully infectious, resting stage during the life cycle of the cell. Spores are inactive metabolically, highly resistant to environmental changes and may survive, for example in soil, for many years. Bacterial spores come in various shapes and are given illustrative names such as drumstick, terminal and subterminal.
2. the reproductive element, produced sexually or asexually, of organisms, such as protozoa, fungi or algae.

• s. former — a bacteria or other small life form that forms spores.

The microscopic body by which ferns, mosses, lichens, fungi, and algae reproduce. Spores are smaller than even the tiniest seeds.

For other uses, see Spore (disambiguation).

For the game, see Spore (2008 video game).

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (July 2007)

Spores produced in a sporic life cycle.

In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoans.^[1] A chief difference between spores and seeds as dispersal units is that spores have very little stored food resources compared with seeds.

Spores are usually haploid and unicellular and are produced by meiosis in the sporangium by the sporophyte. Once conditions are favorable, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes.

Two gametes fuse to create a new sporophyte. This cycle is known as alternation of generations, but a better term is "biological life cycle", as there may be more than one phase and so it cannot be a direct alternation. Haploid spores produced by mitosis (known as mitospores) are used by many fungi for asexual reproduction.

Many ferns, especially those adapted to dry conditions, produce diploid spores. This form of asexual reproduction is called apogamy. It is a form of apomixis.

Spores are the units of asexual reproduction, because a single spore develops into a new organism. By contrast, gametes are the units of sexual reproduction, as two gametes need to fuse to create a new organism.

Contents 1 Definition 2 Classification 2.1 By spore-producing structure 2.2 By function 2.3 By origin during life cycle 2.4 By motility 3 Anatomy 3.1 Trilete spores 4 Dispersal 5 See also 6 References 7 Gallery

Definition

The term spore derives from the ancient Greek word σπορα ("spora"), meaning a seed.

In common parlance, the difference between a "spore" and a "gamete" (both together called gonites) is that a spore will germinate and develop into a sporeling, while a gamete needs to combine with another gamete before developing further. However, the terms are somewhat interchangeable when referring to gametes.

A chief difference between spores and seeds as dispersal units is that spores have little food storage compared with seeds, and thus require more favorable conditions in order to successfully germinate. (This is not without its exceptions, however: many orchid seeds, although multicellular, are microscopic and lack endosperm, and spores of some fungi in the Glomeromycota commonly exceed 300 µm in diameter.)^[2] Seeds, therefore, are more resistant to harsh conditions and require less energy to start mitosis. Spores are produced in large numbers to increase the chance of a spore surviving in a number of notable examples.

Classification

Spores can be classified in several ways such as:

By spore-producing structure

Asci of Morchella elata, containing ascospores.

In plants, microspores, and in some cases megaspores, are formed from all four products of meiosis.

In contrast, in many seed plants and heterosporous ferns, only a single product of meiosis will become a megaspore (macrospore), with the rest degenerating.

In fungi and fungus-like organisms, spores are often classified by the structure in which meiosis and spore production occurs. Since fungi are often classified according to their spore-producing structures, these spores are often characteristic of a particular taxon of the fungi.

• Sporangiospores: spores produced by a sporangium in many fungi such as zygomycetes.
• Zygospores: spores produced by a zygosporangium, characteristic of zygomycetes.
• Ascospores: spores produced by an ascus, characteristic of ascomycetes.
• Basidiospores: spores produced by a basidium, characteristic of basidiomycetes.
• Aeciospores: spores produced by a aecium in some fungi such as rusts or smuts.
• Urediospores: spores produced by a uredinium in some fungi such as rusts or smuts.
• Teliospores: spores produced by a telium in some fungi such as rusts or smuts.
• Oospores: spores produced by a oogonium, characteristic of oomycetes.
• Carpospores: spores produced by a carposporophyte, characteristic of red algae.
• Tetraspores: spores produced by a tetrasporophyte, characteristic of red algae.

By function

• Chlamydospores: thick-walled resting spores of fungi produced to survive unfavorable conditions.
• Parasitic fungal spores may be classified into internal spores, which germinate within the host, and external spores, also called environmental spores, released by the host to infest other hosts.^[3]

By origin during life cycle

• Meiospores: spores produced by meiosis; they are thus haploid, and give rise to a haploid daughter cell(s) or a haploid individual. Examples are the precursor cells of gametophytes of seed plants found in flowers (angiosperms) or cones (gymnosperms).
  • Microspores: meiospores that give rise to a male gametophyte, (pollen in seed plants).
  • Megaspores (or macrospores): meiospores that give rise to a female gametophyte, (an ovule in seed plants).
• Mitospores (or conidia, conidiospores): spores produced by mitosis; they are characteristic of Ascomycetes. Fungi in which only mitospores are found are called “mitosporic fungi” or “anamorphic fungi”, and are previously classified under the taxon Deuteromycota (See Teleomorph, anamorph and holomorph).

By motility

Spores can be differentiated by whether they can move or not.

• Zoospores: mobile spores that move by means of one or more flagella, and can be found in some algae and fungi.
• Aplanospores: immobile spores that may nevertheless potentially grow flagella.
• Autospores: immobile spores that cannot develop flagella.
• Ballistospores: spores that are actively discharged from the body of the fungal fruiting body. Most basidiospores are also ballistospores, and another notable example is spores of Pilobolus.
• Statismospores: spores that are not actively discharged from the fungal fruiting body. Examples are puffballs.

Anatomy

Under high magnification, spores can be categorized as either monolete spores or trilete spores. In monolete spores, there is a single line on the spore indicating the axis on which the mother spore was split into four along a vertical axis. In trilete spores, all four spores share a common origin and are in contact with each other, so when they separate, each spore shows three lines radiating from a center pole.

Vascular plant spores are always haploid. Vascular plants are either homosporous (or isosporous) or heterosporous. Plants that are homosporous produce spores of the same size and type. Heterosporous plants, such as spikemosses, quillworts, and some aquatic ferns produce spores of two different sizes: the larger spore in effect functioning as a "female" spore and the smaller functioning as a "male".

Trilete spores

Main article: Evolutionary history of plants

This section requires expansion.

Trilete spores, formed by the dissociation of a spore tetrad, are taken as the earliest evidence of life on land,^[4] dating to the mid-Ordovician (early Llanvirn, ~470 million years ago).^[5]

Dispersal

Spores being ejected by fungi.

In fungi, both asexual and sexual spores or sporangiospores of many fungal species are actively dispersed by forcible ejection from their reproductive structures. This ejection ensures exit of the spores from the reproductive structures as well as travelling through the air over long distances. Many fungi thereby possess specialized mechanical and physiological mechanisms as well as spore-surface structures, such as hydrophobins, for spore ejection. These mechanisms include, for example, forcible discharge of ascospores enabled by the structure of the ascus and accumulation of osmolytes in the fluids of the ascus that lead to explosive discharge of the ascospores into the air.^[6] The forcible discharge of single spores termed ballistospores involves formation of a small drop of water (Buller's drop), which upon contact with the spore leads to its projectile release with an initial acceleration of more than 10,000 g.^[7] Other fungi rely on alternative mechanisms for spore release, such as external mechanical forces, exemplified by puffballs. Attracting insects, such as flies, to fruiting structures, by virtue of their having lively colours and a putrid odour, for dispersal of fungal spores is yet another strategy, most prominently used by the stinkhorns.

In the case of spore-shedding vascular plants such as ferns, wind distribution of very light spores provides great capacity for dispersal. Also, spores are less subject to animal predation than seeds because they contain almost no food reserve; however they are more subject to fungal and bacterial predation. Their chief advantage is that, of all forms of progeny, spores require the least energy and materials to produce.

In the spikemoss Selaginella lepidophylla, dispersal is achieved in part by an unusual type of diaspore, a tumbleweed.^{[citation needed]}

See also

Fungi portal

• Alternation of generations
• Bioaerosol
• Sporophyte
• Endospore
• Fern
• Auxiliary cell

References

1. ^ Spore FAQ - Aerobiology Research Laboratory
2. ^ INVAM
3. ^ [1].
4. ^ Gray, J. (1985). "The Microfossil Record of Early Land Plants: Advances in Understanding of Early Terrestrialization, 1970-1984". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences (1934-1990) 309 (1138): 167–195. doi:10.1098/rstb.1985.0077. http://links.jstor.org/sici?sici=0080-4622(19850402)309%3A1138%3C167%3ATMROEL%3E2.0.CO%3B2-E. Retrieved on 2008-04-26. 
5. ^ Wellman, C.H., Gray, J. (2000). "The microfossil record of early land plants". Philosophical Transactions: Biological Sciences 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. http://www.journals.royalsoc.ac.uk/index/2NWB35JF2C34PJHG.pdf. Retrieved on 2008-02-13. 
6. ^ Trail F. (2007). "Fungal cannons: explosive spore discharge in the Ascomycota". FEMS Microbiology Letterrs 276: 12–8. doi:10.1111/j.1574-6968.2007.00900.x. PMID 17784861. 
7. ^ Pringle A, Patek SN, Fischer M, Stolze J, Money NP. (2005). "The captured launch of a ballistospore". Mycologia 97: 866–71. doi:10.3852/mycologia.97.4.866. PMID 16457355. 

Gallery

Microscopic view of dehisced fern sporangia (no spores are visible)

Microscopic view of Equisetum spores

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Dansk (Danish)
n. - spore
v. intr. - udvikle sporer, så sporer

Nederlands (Dutch)
spoor, spore, reproduceren door middel van sporen

Français (French)
n. - spore
v. intr. - se former, porter, ou libérer des spores

Deutsch (German)
n. - Spore
v. - Sporen bilden, sich durch Sporen fortpflanzen

Ελληνική (Greek)
n. - (βιολ.) σπόριο(ν)
v. - γεμίζω με σπόρια

Italiano (Italian)
spora

Português (Portuguese)
n. - esporo (m)
v. - germinar

Русский (Russian)
спора

Español (Spanish)
n. - espora
v. intr. - producir esporas

Svenska (Swedish)
n. - spor
v. - utveckla sporer

中文（简体）(Chinese (Simplified))
孢子, 胚芽, 种子, 生殖细胞, 长孢子

中文（繁體）(Chinese (Traditional))
n. - 孢子, 胚芽, 種子, 生殖細胞
v. intr. - 長孢子

한국어 (Korean)
n. - (균류, 식물의) 포자, 종자, 원인
v. intr. - 포자가 생기다

日本語 (Japanese)
n. - 胞子, 芽胞

العربيه (Arabic)
‏(الاسم) بويغه - خليه ينمو منها النبات (فعل) بوغ - حمل أو ولد الأبواغ‏

עברית (Hebrew)
n. - ‮נבג‬
v. intr. - ‮יצר נבגים‬

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