These single celled algae are from 2 mm to 200 mm long. They live on substrates in shallow warm (>20 °C) euhaline tropical marine waters, usually less than 20 meters deep, and protected from waves.[5] They are very large cells. They are able to attain these sizes without numerous internal cell wells because they build calcium carbonate shells around themselves.
They contain only one nucleus in their vegetative stage, which remains in the bottom of the cell in the holdfast at the substrate. Only when they are ready to produce gametes does the nucleus undergo meiosis and then numerous mitoses into many nuclei which then migrate into the gametangia at the top of the alga.
Because the nucleus is safely hidden in the holdfast, the cells easily regenerate if the top portions are broken off.
These algae are notable for having an intracellular network of 10 nm proteinaceous filaments, possibly for the storage and transport of ribonucleoprotein particles.[6]
Because of all these properties, and the fact that they are easy to manipulate they have been favorite organisms in the study of the role of the nucleus vs the unnucleated cytoplasm in the behavior of cells.
A fossil receptaculitid, considered a member of the Order Dasycladales; Ordovician of Estonia.
Dasyclads mineralize in aragonite or high-magnesium calcite (never both in the same species); some extant examples also contain extracellular secretions of weddellite (calcium oxalate, CaC2O4), secreted in the mucilage layer. [5] Calcification can occur in (i) cell walls, potentially continuing into cell lumina; (ii), vacuoles, before transport to cell walls or mucilage; (iii) within cell lumens; (iv) the mucilage layer, (v) externally to the mucilage layer; typically without biological mediation.[5]
The calcium carbonate typically forms needle-like crystals, sometimes forming layers with different orientations corresponding to later stages of mineralization, but idiosyncratic microstructures characterize specific taxa.[5]
Fossil recordedit
Cyclocrinitids are among their earliest fossil representatives.
^Yang, Jie; Lan, Tian; Zhang, Xi-Guang; Smith, Martin R. (8 March 2023). "Protomelission is an early dasyclad alga and not a Cambrian bryozoan". Nature. 615 (7952): 468–471. doi:10.1038/s41586-023-05775-5. PMID 36890226. S2CID 257425218.
^ abcdefBerger, Sigrid; Kaever, Matthias J. Dasycladales: An illustrated monograph of a fascinating algal order.
^Berger, S; Wittke W; Traub P (1998). "Occurrence of proteinaceous 10-nm filaments throughout the cytoplasm of algae of the order Dasycladales". Experimental Cell Research. 240 (2): 176–186. doi:10.1006/excr.1997.3924. PMID 9596990.
External linksedit
Berger, Sigrid (2006).- Photo-Atlas of living Dasycladales.- ISBN2-916733-01-9, Carnets de Géologie, Brest, Book / Livre 2006/02 (CG2006_BOOK_02), 348 p., 1 fig., 332 micrographs.
Génot, Patrick (2009).- Cenozoic Dasycladales. A photo-atlas of Lutetian species from French Cenozoic basins.- ISBN978-2-916733-03-6, Carnets de Géologie, Brest, Special Publication 2009/01 (CG2009_SP01), 180 p., 2 figs., 29 pls.
This Ulvophyceae-related article is a stub. You can help Wikipedia by expanding it.
dasycladales, order, large, unicellular, green, algae, class, ulvophyceae, contains, families, dasycladaceae, polyphysaceae, temporal, range, cambrian, stage, recent, preꞒ, ordovician, presentscientific, classification, unranked, viridiplantaedivision, chlorop. Dasycladales is an order of large unicellular green algae in the class Ulvophyceae 4 It contains two families the Dasycladaceae and the Polyphysaceae DasycladalesTemporal range Cambrian Stage 3 Recent PreꞒ Ꞓ O S D C P T J K Pg N 1 Ordovician 2 to presentScientific classification unranked ViridiplantaeDivision ChlorophytaClass UlvophyceaeOrder DasycladalesPascher 1931 3 FamiliesDasycladaceae Polyphysaceae TriploporellaceaeThese single celled algae are from 2 mm to 200 mm long They live on substrates in shallow warm gt 20 C euhaline tropical marine waters usually less than 20 meters deep and protected from waves 5 They are very large cells They are able to attain these sizes without numerous internal cell wells because they build calcium carbonate shells around themselves They contain only one nucleus in their vegetative stage which remains in the bottom of the cell in the holdfast at the substrate Only when they are ready to produce gametes does the nucleus undergo meiosis and then numerous mitoses into many nuclei which then migrate into the gametangia at the top of the alga Because the nucleus is safely hidden in the holdfast the cells easily regenerate if the top portions are broken off These algae are notable for having an intracellular network of 10 nm proteinaceous filaments possibly for the storage and transport of ribonucleoprotein particles 6 Because of all these properties and the fact that they are easy to manipulate they have been favorite organisms in the study of the role of the nucleus vs the unnucleated cytoplasm in the behavior of cells A fossil receptaculitid considered a member of the Order Dasycladales Ordovician of Estonia Contents 1 Mineralization 2 Fossil record 3 References 4 External linksMineralization editDasyclads mineralize in aragonite or high magnesium calcite never both in the same species some extant examples also contain extracellular secretions of weddellite calcium oxalate CaC2O4 secreted in the mucilage layer 5 Calcification can occur in i cell walls potentially continuing into cell lumina ii vacuoles before transport to cell walls or mucilage iii within cell lumens iv the mucilage layer v externally to the mucilage layer typically without biological mediation 5 The calcium carbonate typically forms needle like crystals sometimes forming layers with different orientations corresponding to later stages of mineralization but idiosyncratic microstructures characterize specific taxa 5 Fossil record editCyclocrinitids are among their earliest fossil representatives Proposed Cambrian representatives questionable include 5 Cambroporella Amgaella Yakutina Seletonella Mejerella 5 References edit Yang Jie Lan Tian Zhang Xi Guang Smith Martin R 8 March 2023 Protomelission is an early dasyclad alga and not a Cambrian bryozoan Nature 615 7952 468 471 doi 10 1038 s41586 023 05775 5 PMID 36890226 S2CID 257425218 e g Young G A Rudkin D M Dobrzanski E P Robson S P Nowlan G S 2007 Exceptionally preserved Late Ordovician biotas from Manitoba Canada Geology 35 10 883 886 Bibcode 2007Geo 35 883Y doi 10 1130 G23947A 1 Womersley HBS 1984 The marine benthic flora of southern Australia Part I Adelaide Government Printer South Australia Guiry MD GM Guiry 2007 AlgaeBase version 4 2 Taxonomy Browser AlgaeBase National University of Ireland Galway Retrieved 2007 09 22 a b c d e f Berger Sigrid Kaever Matthias J Dasycladales An illustrated monograph of a fascinating algal order Berger S Wittke W Traub P 1998 Occurrence of proteinaceous 10 nm filaments throughout the cytoplasm of algae of the order Dasycladales Experimental Cell Research 240 2 176 186 doi 10 1006 excr 1997 3924 PMID 9596990 External links editBerger Sigrid 2006 Photo Atlas of living Dasycladales ISBN 2 916733 01 9 Carnets de Geologie Brest Book Livre 2006 02 CG2006 BOOK 02 348 p 1 fig 332 micrographs Genot Patrick 2009 Cenozoic Dasycladales A photo atlas of Lutetian species from French Cenozoic basins ISBN 978 2 916733 03 6 Carnets de Geologie Brest Special Publication 2009 01 CG2009 SP01 180 p 2 figs 29 pls nbsp This Ulvophyceae related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Dasycladales amp oldid 1180152671, wikipedia, wiki, book, books, library,
