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Peer Review: by mkuck23 |
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| ⚫ | The '''Phaeophyceae''' or '''brown algae''' (singular: alga), are a large group of mostly [[Ocean|marine]] multicellular [[algae]], including many [[Seaweed|seaweeds]] located in colder [[Northern Hemisphere]] waters. They play an important role in marine environments, both as food and as habitats. For instance, ''[[Macrocystis]]'', a [[kelp]] of the order [[Laminariales]], may reach 60 m (200 ft) in length and forms prominent underwater [[Kelp forest|kelp forests]]. Kelp forests like these contain a high level of biodiversity.<ref name=":1">{{Cite journal|last=Cock|first=J. Mark|year=2011|title=Brown Algae|url=http://www.sciencedirect.com/science/article/pii/S0960982211005331|journal=Science Direct|volume=21|pages=|via=}}</ref> Another example is ''[[Sargassum]]'', which creates unique floating mats of seaweed in the tropical waters of the [[Sargasso Sea]] that serve as the habitats for many species. Many brown algae, such as members of the order [[Fucales]], commonly grow along rocky seashores. Some members of the class, such as [[kelp]], are used as food for humans. |
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I was going to say you should put more emphazise on the Imoportance and Uses section but it appears below that you haveYou also might want to inlude a diagram for the Life Cycle portion to help users summarize it. .I |
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| ⚫ | Worldwide, over 1500–2000 [[species]] of brown algae are known.<ref name="Hoek">{{cite book|title=Algae: An Introduction to Phycology|last=van den Hoek|first=C.|last2=Mann|first2=D. G.|last3=Jahns|first3=H. M.|publisher=[[Cambridge University Press]]|year=1995|isbn=0-521-31687-1|location=Cambridge|pages=165–218}}</ref> Some species, such as ''[[Ascophyllum nodosum]]'', are important in commercial use because they have become subjects of extensive research in their own right. They have environmental importance too through [[Carbon fixation]].<ref name=":1" /> In the ecosystem, there is sometimes a [[Symbiosis|symbiotic]] relationship between coral and algae. Coral will host algae and use its carbon fixation for it own good. This relationship is not always mutually beneficial, as the coral often loses its pigments and begins bleaching.<ref>{{Cite journal|last=Wooldridge|first=Scott A.|date=2010-07-01|title=Is the coral-algae symbiosis really ‘mutually beneficial’ for the partners?|url=http://onlinelibrary.wiley.com/doi/10.1002/bies.200900182/abstract|journal=BioEssays|language=en|volume=32|issue=7|pages=615–625|doi=10.1002/bies.200900182|issn=1521-1878}}</ref> |
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ouldwalso suggest that you include more on the asexual reproduction to clarify the difference between the two. In the Life Cycle section for someone who hasn't learned about this before it is confusing as to which things refer to sexual vs asexual reproduction. You also could alwyas add more to the symbiotic relationship mentioned in the introduction. |
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| ⚫ | Brown algae belong to the group [[Heterokont|Heterokontophyta]], a large group of [[Eukaryote|eukaryotic]] organisms distinguished most prominently by having [[Chloroplast|chloroplasts]] surrounded by four membranes, suggesting an origin from a [[symbiotic relationship]] between a basal eukaryote and another eukaryotic organism. Most brown algae contain the pigment [[fucoxanthin]], which is responsible for the distinctive greenish-brown color that gives them their name. Brown algae are unique among heterokonts in developing into multicellular forms with [[Cellular differentiation|differentiated]] [[Tissue (biology)|tissues]], but they reproduce by means of [[Flagellum|flagellated]] [[Spore|spores]] and [[Gamete|gametes]] that closely resemble cells of other heterokonts. Genetic studies show their closest relatives to be the [[yellow-green algae]]. |
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| ⚫ | The '''Phaeophyceae''' or '''brown algae''' (singular: alga), are a large group of mostly [[Ocean|marine]] multicellular [[algae]], including many [[Seaweed|seaweeds]] |
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| ⚫ | Worldwide, over 1500–2000 [[species]] of brown algae are known.<ref name="Hoek">{{cite book|title=Algae: An Introduction to Phycology|last=van den Hoek|first=C.|last2=Mann|first2=D. G.|last3=Jahns|first3=H. M.|publisher=[[Cambridge University Press]]|year=1995|isbn=0-521-31687-1|location=Cambridge|pages=165–218}}</ref> Some species, such as ''[[Ascophyllum nodosum]]'', are |
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| ⚫ | Brown algae belong to |
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== Life Cycle == |
== Life Cycle == |
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[[File:Laminaria Life Cycle.png|thumb|The life cycle of a representative species Laminaria. Most Brown Algae follow this form of sexual reproduction.]] |
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Most brown algae, with the exception of the [[Fucales]], perform [[sexual reproduction]] through [[sporic meiosis]].<ref name=":0">{{Cite book|url=https://books.google.com/books/about/Introduction_to_the_algae.html?id=qYTwAAAAMAAJ|title=Introduction to the algae: structure and reproduction|last=Bold|first=Harold Charles|last2=Wynne|first2=Michael James|date=1985-01-01|publisher=Prentice-Hall|language=en}}</ref> Between generations, the algae |
Most brown algae, with the exception of the [[Fucales]], perform [[sexual reproduction]] through [[sporic meiosis]].<ref name=":0">{{Cite book|url=https://books.google.com/books/about/Introduction_to_the_algae.html?id=qYTwAAAAMAAJ|title=Introduction to the algae: structure and reproduction|last=Bold|first=Harold Charles|last2=Wynne|first2=Michael James|date=1985-01-01|publisher=Prentice-Hall|language=en}}</ref> Between generations, the algae go through separate [[sporophyte]] ([[diploid]]) and [[gametophyte]] ([[haploid]]) phases. The sporophyte stage is often the more visible of the two, though some species of brown algae have similar diploid and haploid phases. Free floating forms of brown algae often do not undergo [[sexual reproduction]] until they attach themselves to substrate. The haploid generation consists of male and female [[gametophyte|gametophytes]].<ref>{{Cite book|url=https://books.google.com/books?hl=en&lr=&id=Yjv1woP0QtYC&oi=fnd&pg=PA267&dq=sex+chromosomes+in+brown+algae&ots=RqPDMveVUi&sig=IumxOHMJSUdOrfwH9NdEHSIh6ao#v=onepage&q&f=false|title=Plant Reproductive Ecology : Patterns and Strategies: Patterns and Strategies|last=Windsor|first=Jon and Lesley Lovett-Doust Professor of Biology the University of|date=1988-07-07|publisher=Oxford University Press, USA|isbn=9780198021926|language=en}}</ref> The fertilization of egg cells varies between species of brown algae, and may be [[Isogamy|isogamous]], [[Oogamy|oogamous]], or [[Anisogamy|anisogamous]]. Fertilization may take place in the water with eggs and motile sperm, or within the [[oogonium]] itself. |
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Certain species of brown algae can also perform [[asexual reproduction]] through the production of motile diploid [[Zoospore|zoospores]].<ref name=":0" /> These zoospores form in plurilocular [[sporangium]], and can mature into the sporophyte phase immediately.<ref>{{Cite journal|date=2017-02-12|title=Zoid|url=https://en.wikipedia.org/enwiki/w/index.php?title=Zoid&oldid=765004344|journal=Wikipedia|language=en}}</ref> |
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| ⚫ | In a representative species ''[[Laminaria]]'', there is a conspicuous [[diploid]] generation and smaller haploid generations. Meiosis takes place within several [[sporangium]] along the algae's blade, forming haploid male |
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[[File:Fucus conceptacle XS3.jpg|thumb|A closeup of a Fucus' conceptacle, showing the gametes coming together to form a fertilized zygote.]] |
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| ⚫ | In a representative species ''[[Laminaria]]'', there is a conspicuous [[diploid]] generation and smaller haploid generations. Meiosis takes place within several unilocular [[sporangium]] along the algae's blade, each one forming either haploid male or female [[Zoospore|zoospores]]. The spores are then released from the sporangia and grow to form male and female gametophytes. The female gametophyte produces an egg in the oogonium, and the male gametophyte releases motile sperm that fertilize the egg. The fertilized zygote then grows into the mature diploid sporophyte. |
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In the order [[Fucales]], sexual reproduction is [[oogamous]], and the mature diploid is the only form for each generation. Gametes are formed in specialized [[Conceptacle|conceptacles]] |
In the order [[Fucales]], sexual reproduction is [[oogamous]], and the mature diploid is the only form for each generation. Gametes are formed in specialized [[Conceptacle|conceptacles]] that occur scattered on both surfaces of the receptacle, the outer portion of the blades of the parent plant. Egg cells and motile sperm are released from separate sacs within the conceptacles of the parent algae, combining in the water to complete fertilization. The fertilized zygote settles onto a surface and then differentiates into a leafy [[thallus]] and a finger-like [[holdfast]]. Light regulates differentiation of the zygote into blade and holdfast. |
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== Importance and Uses == |
== Importance and Uses == |
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Brown algae include a number of [[Edible seaweed|edible seaweeds]] |
Brown algae include a number of [[Edible seaweed|edible seaweeds]]. All brown algae contain [[alginic acid]] (alginate) in their cell walls, which is extracted commercially and used as a industrial thickening agent in food and for other uses.<ref>{{Cite web|url=http://www.fao.org/docrep/w6355e/w6355e04.htm|title=Alginic acid|website=www.fao.org|access-date=2017-04-12}}</ref> One of these products is used in a Lithium Ion batteries. Alginic acid is used as a stable component of a battery [[anode]]. This [[polysaccharide]] is a major component of brown algae, and is not found in land plants.<ref>{{Cite journal|last=Kovalenko|first=Igor|last2=Zdyrko|first2=Bogdan|last3=Magasinski|first3=Alexandre|last4=Hertzberg|first4=Benjamin|last5=Milicev|first5=Zoran|last6=Burtovyy|first6=Ruslan|last7=Luzinov|first7=Igor|last8=Yushin|first8=Gleb|date=2011-01-01|title=A Major Constituent of Brown Algae for Use in High-Capacity Li-Ion Batteries|url=http://www.jstor.org/stable/23059304|journal=Science|volume=334|issue=6052|pages=75–79}}</ref> |
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Alginic acid can also be used in [[ |
Alginic acid can also be used in [[aquaculture]]. For example, alginic acid enhances the immune system of rainbow trout. Younger fish are more likely to survive when given a diet with alginic acid.<ref>{{Cite journal|last=Gioacchini|first=Giorgia|last2=Lombardo|first2=Francesco|last3=Avella|first3=Matteo Alessandro|last4=Olivotto|first4=Ike|last5=Carnevali|first5=Oliana|date=2010-04-01|title=Welfare improvement using alginic acid in rainbow trout (Oncorhynchus mykiss) juveniles|url=http://dx.doi.org/10.1080/02757541003627738|journal=Chemistry and Ecology|volume=26|issue=2|pages=111–121|doi=10.1080/02757541003627738|issn=0275-7540}}</ref> |
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Brown algae including [[kelp]] beds also |
Brown algae including [[kelp]] beds also fix a significant portion of the earth's carbon dioxide yearly through photosynthesis.<ref>{{Cite journal|last=Vásquez|first=Julio A.|last2=Zuñiga|first2=Sergio|last3=Tala|first3=Fadia|last4=Piaget|first4=Nicole|last5=Rodríguez|first5=Deni C.|last6=Vega|first6=J. M. Alonso|date=2014-04-01|title=Economic valuation of kelp forests in northern Chile: values of goods and services of the ecosystem|url=https://link.springer.com/article/10.1007/s10811-013-0173-6|journal=Journal of Applied Phycology|language=en|volume=26|issue=2|pages=1081–1088|doi=10.1007/s10811-013-0173-6|issn=0921-8971}}</ref> |
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[[Sargachromanol|Sargachromanol G]], |
[[Sargachromanol|Sargachromanol G]], an extract of [[Sargassum siliquastrum]], has been shown to have anti-inflammatory effects.<ref>{{Cite journal|last=Yoon|first=Weon-Jong|last2=Heo|first2=Soo-Jin|last3=Han|first3=Sang-Chul|last4=Lee|first4=Hye-Ja|last5=Kang|first5=Gyeoung-Jin|last6=Kang|first6=Hee-Kyoung|last7=Hyun|first7=Jin-Won|last8=Koh|first8=Young-Sang|last9=Yoo|first9=Eun-Sook|date=2012-08-01|title=Anti-inflammatory effect of sargachromanol G isolated from Sargassum siliquastrum in RAW 264.7 cells|url=https://link.springer.com/article/10.1007/s12272-012-0812-5|journal=Archives of Pharmacal Research|language=en|volume=35|issue=8|pages=1421–1430|doi=10.1007/s12272-012-0812-5|issn=0253-6269}}</ref> |
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Latest revision as of 00:31, 20 April 2017
Brown Algae
The Phaeophyceae or brown algae (singular: alga), are a large group of mostly marine multicellular algae, including many seaweeds located in colder Northern Hemisphere waters. They play an important role in marine environments, both as food and as habitats. For instance, Macrocystis, a kelp of the order Laminariales, may reach 60 m (200 ft) in length and forms prominent underwater kelp forests. Kelp forests like these contain a high level of biodiversity.[1] Another example is Sargassum, which creates unique floating mats of seaweed in the tropical waters of the Sargasso Sea that serve as the habitats for many species. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Some members of the class, such as kelp, are used as food for humans.
Worldwide, over 1500–2000 species of brown algae are known.[2] Some species, such as Ascophyllum nodosum, are important in commercial use because they have become subjects of extensive research in their own right. They have environmental importance too through Carbon fixation.[1] In the ecosystem, there is sometimes a symbiotic relationship between coral and algae. Coral will host algae and use its carbon fixation for it own good. This relationship is not always mutually beneficial, as the coral often loses its pigments and begins bleaching.[3]
Brown algae belong to the group Heterokontophyta, a large group of eukaryotic organisms distinguished most prominently by having chloroplasts surrounded by four membranes, suggesting an origin from a symbiotic relationship between a basal eukaryote and another eukaryotic organism. Most brown algae contain the pigment fucoxanthin, which is responsible for the distinctive greenish-brown color that gives them their name. Brown algae are unique among heterokonts in developing into multicellular forms with differentiated tissues, but they reproduce by means of flagellated spores and gametes that closely resemble cells of other heterokonts. Genetic studies show their closest relatives to be the yellow-green algae.
Life Cycle
[edit]
Most brown algae, with the exception of the Fucales, perform sexual reproduction through sporic meiosis.[4] Between generations, the algae go through separate sporophyte (diploid) and gametophyte (haploid) phases. The sporophyte stage is often the more visible of the two, though some species of brown algae have similar diploid and haploid phases. Free floating forms of brown algae often do not undergo sexual reproduction until they attach themselves to substrate. The haploid generation consists of male and female gametophytes.[5] The fertilization of egg cells varies between species of brown algae, and may be isogamous, oogamous, or anisogamous. Fertilization may take place in the water with eggs and motile sperm, or within the oogonium itself.
Certain species of brown algae can also perform asexual reproduction through the production of motile diploid zoospores.[4] These zoospores form in plurilocular sporangium, and can mature into the sporophyte phase immediately.[6]
In a representative species Laminaria, there is a conspicuous diploid generation and smaller haploid generations. Meiosis takes place within several unilocular sporangium along the algae's blade, each one forming either haploid male or female zoospores. The spores are then released from the sporangia and grow to form male and female gametophytes. The female gametophyte produces an egg in the oogonium, and the male gametophyte releases motile sperm that fertilize the egg. The fertilized zygote then grows into the mature diploid sporophyte.
In the order Fucales, sexual reproduction is oogamous, and the mature diploid is the only form for each generation. Gametes are formed in specialized conceptacles that occur scattered on both surfaces of the receptacle, the outer portion of the blades of the parent plant. Egg cells and motile sperm are released from separate sacs within the conceptacles of the parent algae, combining in the water to complete fertilization. The fertilized zygote settles onto a surface and then differentiates into a leafy thallus and a finger-like holdfast. Light regulates differentiation of the zygote into blade and holdfast.
Importance and Uses
[edit]Brown algae include a number of edible seaweeds. All brown algae contain alginic acid (alginate) in their cell walls, which is extracted commercially and used as a industrial thickening agent in food and for other uses.[7] One of these products is used in a Lithium Ion batteries. Alginic acid is used as a stable component of a battery anode. This polysaccharide is a major component of brown algae, and is not found in land plants.[8]
Alginic acid can also be used in aquaculture. For example, alginic acid enhances the immune system of rainbow trout. Younger fish are more likely to survive when given a diet with alginic acid.[9]
Brown algae including kelp beds also fix a significant portion of the earth's carbon dioxide yearly through photosynthesis.[10]
Sargachromanol G, an extract of Sargassum siliquastrum, has been shown to have anti-inflammatory effects.[11]
 | This is a user sandbox of Jmcain58. You can use it for testing or practicing edits. This is not the sandbox where you should draft your assigned article for a dashboard.wikiedu.org course. To find the right sandbox for your assignment, visit your Dashboard course page and follow the Sandbox Draft link for your assigned article in the My Articles section. |
- ^ a b Cock, J. Mark (2011). "Brown Algae". Science Direct. 21.
- ^ van den Hoek, C.; Mann, D. G.; Jahns, H. M. (1995). Algae: An Introduction to Phycology. Cambridge: Cambridge University Press. pp. 165–218. ISBN 0-521-31687-1.
- ^ Wooldridge, Scott A. (2010-07-01). "Is the coral-algae symbiosis really 'mutually beneficial' for the partners?". BioEssays. 32 (7): 615–625. doi:10.1002/bies.200900182. ISSN 1521-1878.
- ^ a b Bold, Harold Charles; Wynne, Michael James (1985-01-01). Introduction to the algae: structure and reproduction. Prentice-Hall.
- ^ Windsor, Jon and Lesley Lovett-Doust Professor of Biology the University of (1988-07-07). Plant Reproductive Ecology : Patterns and Strategies: Patterns and Strategies. Oxford University Press, USA. ISBN 9780198021926.
- ^ "Zoid". Wikipedia. 2017-02-12.
- ^ "Alginic acid". www.fao.org. Retrieved 2017-04-12.
- ^ Kovalenko, Igor; Zdyrko, Bogdan; Magasinski, Alexandre; Hertzberg, Benjamin; Milicev, Zoran; Burtovyy, Ruslan; Luzinov, Igor; Yushin, Gleb (2011-01-01). "A Major Constituent of Brown Algae for Use in High-Capacity Li-Ion Batteries". Science. 334 (6052): 75–79.
- ^ Gioacchini, Giorgia; Lombardo, Francesco; Avella, Matteo Alessandro; Olivotto, Ike; Carnevali, Oliana (2010-04-01). "Welfare improvement using alginic acid in rainbow trout (Oncorhynchus mykiss) juveniles". Chemistry and Ecology. 26 (2): 111–121. doi:10.1080/02757541003627738. ISSN 0275-7540.
- ^ Vásquez, Julio A.; Zuñiga, Sergio; Tala, Fadia; Piaget, Nicole; Rodríguez, Deni C.; Vega, J. M. Alonso (2014-04-01). "Economic valuation of kelp forests in northern Chile: values of goods and services of the ecosystem". Journal of Applied Phycology. 26 (2): 1081–1088. doi:10.1007/s10811-013-0173-6. ISSN 0921-8971.
- ^ Yoon, Weon-Jong; Heo, Soo-Jin; Han, Sang-Chul; Lee, Hye-Ja; Kang, Gyeoung-Jin; Kang, Hee-Kyoung; Hyun, Jin-Won; Koh, Young-Sang; Yoo, Eun-Sook (2012-08-01). "Anti-inflammatory effect of sargachromanol G isolated from Sargassum siliquastrum in RAW 264.7 cells". Archives of Pharmacal Research. 35 (8): 1421–1430. doi:10.1007/s12272-012-0812-5. ISSN 0253-6269.