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Topic: Pyrenoid

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	Pyrenoid - Wikipedia, the free encyclopedia
		Complex pyrenoids are highly differentiated areas of chloroplast surrounded by a thick starch sheath.
		The pyrenoid may serve to aid the concentration of dissolved carbon dioxide by preventing diffusion away from the site of fixation while simultaneously reducing the level of oxygen at the site of CO fixation.
		Pyrenoids are not found in higher plants and it is thought that the slower rate of diffusion of carbon dioxide in water compared to air (1:1000) favors their presence in these small submerged organisms.
	en.wikipedia.org /wiki/Pyrenoid (249 words)

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		The fine structure of the pyrenoid in the mature vegetative cell of Tetracystis excentrica Brown and Bold is described.
		Zoospore pyrenoids lack the 2 convoluted thylakoids between the starch plates and the ground substance characteristic of those in the mature vegetative cell.
		Conclusive evidence is presented for the presence of RNA in the cytoplasm and nucleolus, DNA in the nucleus, and protein in the pyrenoid.
	www.botany.utexas.edu /mbrown/papers/26.htm (267 words)

	Pyrenoid - Biocrawler (Site not responding. Last check: 2007-09-30)
		In cell biology, pyrenoids are centers of carbon dioxide fixation.
		This is assumed to aid the concentration of dissolved carbon dioxide by preventing diffusion away from the site of fixation while simultaneously reducing the level of oxygen in the pyrenoid which can inhibit the carbon fixation reaction catalysed by RubisCO.
		Pyrenoids are not found in higher plants and it is thought that the slower rate of diffusion of carbon dioxide in water compared to air (1:1000) necessitates their use by small aquatic organisms.
	www.biocrawler.com /encyclopedia/Pyrenoid (298 words)

	The Intracellular Localization of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase in Chlamydomonas reinhardtii -- ...
		to the pyrenoid or to the chloroplast stroma was estimated for
		Pyrenoids are electron-dense structures that are found in the plastids of most algae.
		To obtain the fraction of Rubisco in the pyrenoid, the average density of immunogold particles in the cytoplasm was subtracted
	www.plantphysiol.org /cgi/content/full/116/4/1585 (3087 words)

	Diel changes in pyrenoid and starch reserves in dinoflagellates Phycologia - Find Articles (Site not responding. Last check: 2007-09-30)
		During the night, pyrenoid regions were absent from both marine and freshwater species; starch granules were absent from the marine forms but remained present in the freshwater forms.
		The results demonstrate that pyrenoids show a diurnal rhythm in occurrence in both freshwater and marine dinoflagellates and that starch reserves are consumed differently in marine and freshwater forms.
		Dinoflagellate pyrenoids exhibit a great variety of shapes and are reported to consist of proteinaceous material; in a few cases, they have a paracrystalline matrix (Kowallik 1969).
	www.findarticles.com /p/articles/mi_qa3850/is_200201/ai_n9039138/pg_9 (768 words)

	Introduction
		Rubisco is located in the pyrenoid in the chloroplast of plants.
		With higher levels of CO, 40% of the Rubisco is associated with the pyrenoid.
		All of the pyrenoid Rubisco should be active in order to account for the amount of CO fixation occurring.
	csmres.jmu.edu /biology/Bio480/Fall05/Monday1/intro.html (431 words)

	lecture3.html
		Electron micrograph of a brown algal cell showing acentric pyrenoid, plastid in "3s" and (difficult to see), the attachment of the plastid ER to the nuclear envelop.
		Pyrenoid in some orders (more simple orders); this is acentric - protrudes from plastid surface; polymerized carbohydrate is stored in a vesicle outside of the plastid, but juxtiposed to pyrenoid.
		This vesicle appears "empty" after EM fixation procedures as the contents are soluble in the fixation solutions utilized (unlike starch in Chlorophyta which is in starch grains that are not solubilized by fixation solutions).
	bio.classes.ucsc.edu /bio170/oldsite/lecture7.html (639 words)

	Constancea 83.11: Diacanthos belenophorus
		As in that genus, Diacanthos also has a pyrenoid crossed by a thylakoid, a bipartite cell wall consisting of an inner electron-dense layer and an outer less electron-dense layer and mother cell wall fragments that remain attached to the autospore walls.
		Usually, the pyrenoid is nearly completely surrounded by two cup-shaped starch grains and is crossed by a thylakoid which passes through between the starch cups (Fig.
		The pyrenoid was crossed by single thylakoids and the cell wall was described as consisting of two layers (Moestrup 1972).
	ucjeps.berkeley.edu /constancea/83/hegewald_schnepf/diacanthos.html (1547 words)

	13th International Congress on Photosynthesis (Site not responding. Last check: 2007-09-30)
		The photosynthetic apparatus of hornworts is unique among land plants due to the presence of a pyrenoid (an electron dense body in each chloroplast).
		Despite their scarcity among land plants, pyrenoids are common in algae and are generally believed to be an integral part of a carbon concentrating mechanism (CCM).
		The involvement of the pyrenoid in CCMs has been clearly demonstrated for Chlamydomonas reinhardtii and several species of pyrenoid-containing hornworts, however, its precise function is unclear.
	abstracts.co.allenpress.com /pweb/pwc2004/document?ID=43649 (281 words)

	How Do Algae Concentrate CO2 to Increase the Efficiency of Photosynthetic Carbon Fixation? -- Moroney and Somanchi 119 ...
		the role of the pyrenoid in CO concentration is circumstantial.
		Lacoste-Royal G, Gibbs SP (1987) Immunocytochemical localization of ribulose-1,5-bisphospate carboxylase in the pyrenoid and thylakoid region of the chloroplast of Chlamydomonas reinhardtii.
		Smith EC, Griffiths H (1996) The occurrence of the chloroplast pyrenoid is correlated with the activity of a CO -concentrating mechanism and carbon isotope discrimination in lichens and bryophytes.
	www.plantphysiol.org /cgi/content/full/119/1/9 (4502 words)

	Pyrenoids are centers of carbon dioxide fixation carbon dioxide fixation... (Site not responding. Last check: 2007-09-30)
		Pyrenoids are centers of carbon dioxide fixation carbon dioxide fixation...
		It needs six molecules of carbon dioxide and six molecules of ribulose-1,5-bisphosphate = six cycles of the Calvin cycle Calvin cycle to make one new molecule of glucose glucose.
		Since RubisCO doesn't work very efficiently in the presence of oxygen oxygen, the pyrenoids are presumably used to reduce reduce oxygene influence by increasing locally the amount of carbon dioxide.
	www.biodatabase.de /Pyrenoid (183 words)

	Anthocerophyta
		TEM of the thallus epidermis showing large plastids with interspersed starch that lack a pyrenoid.
		Color light micrograph showing longitudinal section of sporophyte with central columella and spores separated by pseudoelaters that extend from the columella to the epidermis.
		Epidermal cells of a hornwort gametophyte stained with acid fuchsin to highlight the pyrenoid with the large, solitary, starch-laden chloroplasts.
	www.science.siu.edu /landplants/Anthocerophyta/anthocerophyta.html (556 words)

	THE CYTOPLASMIC FINE STRUCTURE OF THE DIATOM, NITZSCHIA PALEA -- Drum 18 (2): 429 -- The Journal of Cell Biology
		The pyrenoid appears to be membrane limited, and
		oil droplets are found adjacent to the pyrenoid.
		The membrane limiting the pyrenoid may be a composite of the
	www.jcb.org /cgi/content/abstract/18/2/429 (246 words)

	Cymbella (Site not responding. Last check: 2007-09-30)
		lanceolata is the exception) with a central pyrenoid located towards the dorsal margin.
		Cymbella has undergone a number of revisions in recent years, with the 'broad' concept, as used by Hustedt (1927-66, 1930) and Krammer and Lange-Bertalot (1986) gradually being replaced by a number of more circumscribed genera.
		Single H-shaped chloroplast with a central pyrenoid located towards the dorsal margin.
	craticula.ncl.ac.uk /EADiatomKey/html/Cymbella.html (460 words)

	THE ISOLATION AND PARTIAL CHARACTERIZATION OF THE PYRENOID PROTEIN OF EREMOSPHAERA VIRIDIS -- Holdsworth 51 (2): 499 -- ...
		THE ISOLATION AND PARTIAL CHARACTERIZATION OF THE PYRENOID PROTEIN OF EREMOSPHAERA VIRIDIS -- Holdsworth 51 (2): 499 -- The Journal of Cell Biology
		Holdsworth's present address is the Department of Biology, George Mason College of the University of Virginia, Fairfax, Virginia 22030.
		The pyrenoids of Eremosphaera viridis, a green alga, were isolated
	www.jcb.org /cgi/content/abstract/51/2/499 (286 words)

	pyrenoid - OneLook Dictionary Search
		Tip: Click on the first link on a line below to go directly to a page where "pyrenoid" is defined.
		pyrenoid : The American Heritage® Dictionary of the English Language [home, info]
		Pyrenoid : Online Plain Text English Dictionary [home, info]
	www.onelook.com /?w=pyrenoid (164 words)

	Gomphonema (Site not responding. Last check: 2007-09-30)
		There is a single H-shaped chloroplast with a central pyrenoid.
		Central area with one absent stria on opposite side to stigma.
		The central area is bordered by one very short stria on each side and there is a single stigma is present on one side, close to the central raphe endings.
	craticula.ncl.ac.uk /EADiatomKey/html/Gomphonema.html (801 words)

	Assessing carbon concentrating mechanism function with a tunable diode laser absorption spectrometer: real-time ...
		The photosynthetic apparatus of hornworts is unique among plants due to the presence of a pyrenoid (an electron dense body in each chloroplast).
		This structure is an aggregation of all the Rubisco (ribulose-1, 5-bisphosphate carboxylase/oxygenase) in the cell, plus a few other enzymes, and is often traversed by thylakoid membranes.
		Despite their scarcity among plants, pyrenoids are common in algae and are believed to be an integral part of a carbon concentrating mechanism (CCM), though many mechanistic details are unclear.
	abstracts.aspb.org /pb2005/public/M28/9149.html (388 words)

	CSIRO PUBLISHING - Science Access (Site not responding. Last check: 2007-09-30)
		Hornworts (Anthocerotae) are the only group of land plants with pyrenoid-containing chloroplasts.
		The hornwort pyrenoid is an aggregation of Rubisco, and is analogous to algal pyrenoids.
		CO2 exchange and ?13C values have demonstrated the presence of a CO2 concentrating mechanism (CCM) in pyrenoid-containing species of the genus Anthoceros.
	www.publish.csiro.au /nid/197/paper/SA0403378.htm (210 words)

	pyrenoid - Dictionnaire Français-Anglais WordReference.com
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		Forum discussions with the word(s) 'pyrenoid' in the title:
	www.wordreference.com /fren/pyrenoid (49 words)

	pyrenoid - English-French Dictionary - WordReference.com
		We found no French translation for 'pyrenoid' in our English to French Dictionary.
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	www.wordreference.com /enfr/pyrenoid (57 words)

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