Chlorophyta

Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophytes.[6] The name is used in two very different senses, so care is needed to determine the use by a particular author. In older classification systems, it refers to a highly paraphyletic group of all the green algae within the green plants (Viridiplantae) and thus includes about 7,000 species[7][8] of mostly aquatic photosynthetic eukaryotic organisms. In newer classifications, it refers to the sister of the streptophytes/charophytes. The clade Streptophyta consists of the Charophyta in which the Embryophyta emerged.[9][10] In this sense the Chlorophyta includes only about 4,300 species.[4] Like the land plants (bryophytes and tracheophytes), green algae contain chlorophyll a and chlorophyll b and store food as starch[7] in their plastids.

With the exception of Palmophyllophyceae, Trebouxiophyceae, Ulvophyceae and Chlorophyceae, which show various degrees of multicellularity, all the Chlorophyta lineages are unicellular.[11] Some members of the group form symbiotic relationships with protozoa, sponges, and cnidarians. Others form symbiotic relationships with fungi to form lichens, but the majority of species are free-living. Some conduct sexual reproduction, which is oogamous or isogamous. All members of the clade have motile flagellated swimming cells.[12] While most species live in freshwater habitats and a large number in marine habitats, other species are adapted to a wide range of land environments. For example, Chlamydomonas nivalis, which causes Watermelon snow, lives on summer alpine snowfields. Others, such as Trentepohlia species, live attached to rocks or woody parts of trees. Monostroma kuroshiense, an edible green alga cultivated worldwide and most expensive among green algae, belongs to this group.

Chlorophyta
EB1911 Algae - Fig. 2.-Chlorophyceae
Chlorophytes (A–F, H–L and O)
Scientific classification
Domain: Eukaryota
(unranked): Diaphoretickes
(unranked): Archaeplastida
Clade: Chloroplastida
Phylum: Chlorophyta
Reichenbach, 1828, emend. Pascher, 1914, emend. Lewis & McCourt, 2004[1][2][3]
Classes[4]
Synonyms
  • Chlorophycophyta Papenfuss 1946
  • Chlorophycota
  • Chlorophytina
  • Chlorophyllophyceae
  • Isokontae
  • Stephanokontae[5]
Taiwan 2009 East Coast ShihTiPing Giant Stone Steps Algae FRD 6581
Green algae on coastal rocks at Shihtiping in Taiwan

Ecology

Species of Chlorophyta (treated as what is now considered one of the two main clades of Viridiplantae) are common inhabitants of marine, freshwater and terrestrial environments.[13][14] Several species have adapted to specialised and extreme environments, such as deserts, arctic environments, hypersaline habitats, marine deep waters, deep-sea hydrothermal vents and habitats that experiences extreme changes in temperature, light and salinity. [15][16][17][18] Some groups, such as the Trentepohliales are exclusively found on land.[19] Several species of Chlorophyta live in symbiosis with a diverse range of eukaryotes, including fungi (to form lichens), ciliates, forams, cnidarians and molluscs. [14] Some species of Chlorophyta are heterotrophic, either free-living or parasitic.[20][21] Two common species of the heterotrophic green alga Prototheca are pathogenic and can cause the disease protothecosis in humans and animals.[22]

Classifications

Haeckel Siphoneae
"Siphoneae" from Ernst Haeckel's Kunstformen der Natur, 1904

Characteristics used for the classification of Chlorophyta are: type of zoid, mitosis (karyokynesis), cytokinesis, organization level, life cycle, type of gametes, cell wall polysaccharides[23] and more recently genetic data.

Phylogeny

A newer proposed classification follows Leliaert et al. 2011[17] and modified with Silar 2016,[24] Leliaert 2016[25] and Lopes dos Santos et al. 2017[26] for the green algae clades and Novíkov & Barabaš-Krasni 2015[27] for the land plants clade. Sánchez-Baracaldo et al. is followed for the basal clades.[28][29][30]

Plantae/

Mesostigmatophyceae

Spirotaenia

Chlorokybophyceae

Chlorophyta/
Palmophyllophyceae

Prasinococcales ("prasinophyte clade VI")

Palmophyllales

(Prasinophyceae s.s.)

Pyramimonadophyceae ("prasinophyte clade I")

Mamiellophyceae ("prasinophyte clade II")

Nephroselmidophyceae ("prasinophyte clade III")

?Pycnococcaceae ("prasinophyte clade V")

Picocystophyceae ("prasinophyte clade VII C")

Chloropicophyceae ("prasinophyte clade VII A/B")

Tetraphytina

Pedinophyceae

Chlorophytina

Chlorodendrophyceae ("prasinophyte clade IV")

Trebouxiophyceae

Ulvophyceae

Chlorophyceae

Prasinophyta
Streptophyta/

Klebsormidiophyta

Phragmoplastophyta

Charophyta (stoneworts)

?Chaetosphaeridiales

Coleochaetophyta

Zygnematophyta

Mesotaeniaceae

Embryophyte (Land plants)

Charophyta
Green Algae

Leliaert et al. 2012

Simplified phylogeny of the Chlorophyta, according to Leliaert et al. 2012.[14] Note that many algae previously classified in Chlorophyta are placed here in Streptophyta.

Pombert et al. 2005

A possible classification when Chlorophyta refers to one of the two clades of the Viridiplantae is shown below.[31]

Lewis & McCourt 2004

Hoek, Mann and Jahns 1995

Classification of the Chlorophyta, treated as all green algae, according to Hoek, Mann and Jahns 1995.[7]

In a note added in proof, an alternative classification is presented for the algae of the class Chlorophyceae:

Bold and Wynne 1985

Classification of the Chlorophyta and Charophyta according to Bold and Wynne 1985.[33]

Mattox & Stewart 1984

Classification of the Chlorophyta according to Mattox & Stewart 1984:[32]

Fott 1971

Classification of the Chlorophyta according to Fott 1971.[7]:483

  • Suborder Chlorosarcineae
  • Suborder Ulotrichineae
  • Suborder Oedogoniineae
  • Suborder Chaetophorineae

Round 1971

Classification of the Chlorophyta and related algae according to Round 1971.[34]

Smith 1938

Classification of the Chlorophyta according to Smith 1938:

  • Order 5. Schizogoniales
  • Family Schizogoniaceae
  • Order 10. Siphonales
  • Order 11. Siphonocladiales

References

  1. ^ Reichenbach HG (1828). Conspectus Regni Vegetabilis. p. 23.
  2. ^ Pascher A (1914). "Über Flagellaten und Algen". Berichte der Deutschen Botanischen Gesellschaft. 32: 136–160.
  3. ^ Adl SM, Simpson AG, Farmer MA, Andersen RA, Anderson OR, Barta JR, et al. (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". The Journal of Eukaryotic Microbiology. 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x. PMID 16248873.
  4. ^ a b Guiry MD, Guiry GM (2011). "AlgaeBase : Chlorophyta". World-wide electronic publication, National University of Ireland, Galway. Retrieved 2011-07-26.
  5. ^ Papenfuss GF (1955). "The Classification of the Algae". A century of progress in the natural sciences, 1853-1953. California Academy of Sciences.
  6. ^ Rockwell NC, Martin SS, Li FW, Mathews S, Lagarias JC (May 2017). "The phycocyanobilin chromophore of streptophyte algal phytochromes is synthesized by HY2". The New Phytologist. 214 (3): 1145–1157. doi:10.1111/nph.14422. PMC 5388591. PMID 28106912.
  7. ^ a b c d van den Hoek C, Mann DG, Jahns HM (1995). Algae An Introduction to Phycology. Cambridge: Cambridge University Press. ISBN 978-0-521-30419-1.
  8. ^ "Major Algae Phyla - Table - MSN Encarta". Archived from the original on 2009-10-31.
  9. ^ Lewis LA, McCourt RM (October 2004). "Green algae and the origin of land plants". American Journal of Botany. 91 (10): 1535–56. doi:10.3732/ajb.91.10.1535. PMID 21652308.
  10. ^ Becker B, Marin B (May 2009). "Streptophyte algae and the origin of embryophytes". Annals of Botany. 103 (7): 999–1004. doi:10.1093/aob/mcp044. PMC 2707909. PMID 19273476.
  11. ^ Green Algae and the Origins of Multicellularity in the Plant Kingdom
  12. ^ Kapraun DF (April 2007). "Nuclear DNA content estimates in green algal lineages: chlorophyta and streptophyta". Annals of Botany. 99 (4): 677–701. doi:10.1093/aob/mcl294. PMC 2802934. PMID 17272304.
  13. ^ Graham LE, Graham JM, Wilcox LW (2009) Algae. 2nd Edition. Benjamin Cummings (Pearson), San Francisco, CA
  14. ^ a b c Leliaert F, Smith DR, Moreau H, Herron MD, Verbruggen H, Delwiche CF, De Clerck O (2012). "Phylogeny and molecular evolution of the green algae" (PDF). Critical Reviews in Plant Sciences. 31: 1–46. doi:10.1080/07352689.2011.615705.
  15. ^ Lewis LA, Lewis PO (December 2005). "Unearthing the molecular phylodiversity of desert soil green algae (Chlorophyta)". Systematic Biology. 54 (6): 936–47. doi:10.1080/10635150500354852. PMID 16338765.
  16. ^ De Wever A, Leliaert F, Verleyen E, Vanormelingen P, Van der Gucht K, Hodgson DA, Sabbe K, Vyverman W (October 2009). "Hidden levels of phylodiversity in Antarctic green algae: further evidence for the existence of glacial refugia". Proceedings. Biological Sciences. 276 (1673): 3591–9. doi:10.1098/rspb.2009.0994. PMC 2817313. PMID 19625320.
  17. ^ a b Leliaert F, Verbruggen H, Zechman FW (September 2011). "Into the deep: new discoveries at the base of the green plant phylogeny". BioEssays. 33 (9): 683–92. doi:10.1002/bies.201100035. PMID 21744372.
  18. ^ Foflonker, Fatima; Ananyev, Gennady; Qiu, Huan; Morrison, Andrenette; Palenik, Brian; Dismukes, G. Charles; Bhattacharya, Debashish (June 2016). "The unexpected extremophile: Tolerance to fluctuating salinity in the green alga Picochlorum". Algal Research. 16: 465–472. doi:10.1016/j.algal.2016.04.003.
  19. ^ López-Bautista JM, Rindi F, Guiry MD (July 2006). "Molecular systematics of the subaerial green algal order Trentepohliales: an assessment based on morphological and molecular data". International Journal of Systematic and Evolutionary Microbiology. 56 (Pt 7): 1709–15. doi:10.1099/ijs.0.63990-0. PMID 16825655.
  20. ^ Joubert JJ, Rijkenberg FH (1971). "Parasitic green algae". Annu. Rev. Phytopathol. 9: 45–64. doi:10.1146/annurev.py.09.090171.000401.
  21. ^ Nedelcu AM (December 2001). "Complex patterns of plastid 16S rRNA gene evolution in nonphotosynthetic green algae". Journal of Molecular Evolution. 53 (6): 670–9. Bibcode:2001JMolE..53..670N. doi:10.1007/s002390010254. PMID 11677627.
  22. ^ Tartar A, Boucias DG, Adams BJ, Becnel JJ (January 2002). "Phylogenetic analysis identifies the invertebrate pathogen Helicosporidium sp. as a green alga (Chlorophyta)". International Journal of Systematic and Evolutionary Microbiology. 52 (Pt 1): 273–9. doi:10.1099/00207713-52-1-273. PMID 11837312.
  23. ^ Lobban CS, Wynne MJ (1981). "The Biology of Seaweeds". Botanical Monograph Series 17. University of California Press: 88.
  24. ^ Silar, Philippe (2016), "Protistes Eucaryotes: Origine, Evolution et Biologie des Microbes Eucaryotes", HAL Archives-ouvertes: 1–462
  25. ^ Leliaert F, Tronholm A, Lemieux C, Turmel M, DePriest MS, Bhattacharya D, Karol KG, Fredericq S, Zechman FW, Lopez-Bautista JM (May 2016). "Chloroplast phylogenomic analyses reveal the deepest-branching lineage of the Chlorophyta, Palmophyllophyceae class. nov". Scientific Reports. 6 (1): 25367. Bibcode:2016NatSR...625367L. doi:10.1038/srep25367. PMC 4860620. PMID 27157793.
  26. ^ Lopes Dos Santos A, Pollina T, Gourvil P, Corre E, Marie D, Garrido JL, Rodríguez F, Noël MH, Vaulot D, Eikrem W (October 2017). "Chloropicophyceae, a new class of picophytoplanktonic prasinophytes". Scientific Reports. 7 (1): 14019. Bibcode:2017NatSR...714019L. doi:10.1038/s41598-017-12412-5. PMC 5656628. PMID 29070840.
  27. ^ Novikoff A, Barabasz-Krasny B (2015). Modern plant systematics. Liga-Pres. p. 685. doi:10.13140/RG.2.1.4745.6164. ISBN 978-966-397-276-3.
  28. ^ Sánchez-Baracaldo P, Raven JA, Pisani D, Knoll AH (September 2017). "Early photosynthetic eukaryotes inhabited low-salinity habitats". Proceedings of the National Academy of Sciences of the United States of America. 114 (37): E7737–E7745. doi:10.1073/pnas.1620089114. PMC 5603991. PMID 28808007.
  29. ^ Gitzendanner MA, Soltis PS, Wong GK, Ruhfel BR, Soltis DE (March 2018). "Plastid phylogenomic analysis of green plants: A billion years of evolutionary history". American Journal of Botany. 105 (3): 291–301. doi:10.1002/ajb2.1048. PMID 29603143.
  30. ^ Rockwell NC, Martin SS, Li FW, Mathews S, Lagarias JC (May 2017). "The phycocyanobilin chromophore of streptophyte algal phytochromes is synthesized by HY2". The New Phytologist. 214 (3): 1145–1157. doi:10.1111/nph.14422. PMC 5388591. PMID 28106912.
  31. ^ Pombert JF, Otis C, Lemieux C, Turmel M (September 2005). "The chloroplast genome sequence of the green alga Pseudendoclonium akinetum (Ulvophyceae) reveals unusual structural features and new insights into the branching order of chlorophyte lineages". Molecular Biology and Evolution. 22 (9): 1903–18. doi:10.1093/molbev/msi182. PMID 15930151.
  32. ^ a b c d e Mattox KR, Stewart KD, et al. (The Systematics Association) (1984). "Classification of the green algae: a concept based on comparative cytology.". In Irvine DE, John DM (eds.). The systematics of Green Algae. 27. London: Academic Press. pp. 29–72.
  33. ^ Bold HC, Wynne MJ (1985). Introduction to the algae : structure and reproduction (2nd ed.). Englewood Cliffs, N.J.: Prentice-Hall. ISBN 978-0-13-477746-7.
  34. ^ Round FE (1971). "The taxonomy of the Chlorophyta, 2". Brit. Phycol. J. 6 (2): 235–264. doi:10.1080/00071617100650261.

Further reading

  • Burrows EM (1991). Seaweeds of the British Isles. 2 (Chlorophyta). London: Natural History Museum. ISBN 978-0-565-00981-6.
  • Lewis LA, McCourt RM (October 2004). "Green algae and the origin of land plants". American Journal of Botany. 91 (10): 1535–56. doi:10.3732/ajb.91.10.1535. PMID 21652308.
  • Pickett-Heaps JD (1975). Green Algae. Structure, Reproduction and Evolution in Selected Genera. Stamford, CT: Sinauer Assoc. p. 606.
Bryopsidales

Bryopsidales is an order of green algae, in the class Ulvophyceae.

Chaetophorales

Chaetophorales is an order of green algae in the class Chlorophyceae.

Chlamydomonadales

Chlamydomonadales, also known as Volvocales, are an order of flagellated or pseudociliated green algae, specifically of the Chlorophyceae. Chlamydomonadales can form planar or spherical colonies. These vary from Gonium (four to 32 cells) up to Volvox (500 cells or more). Each cell has two flagella, and is similar in appearance to Chlamydomonas, with the flagella throughout the colony moving in coordination.Both asexual and sexual reproduction occur. In the former, cells divide until they form new colonies, which are then released. In the smaller forms, typically all cells are involved, but larger forms have anterior vegetative and posterior reproductive cells. Sexual reproduction varies from isogamy (both genders produce flagellated gametes of equal size) to oogamy (one gender produces a much larger, nonmotile gamete).

The classification of the Chlamydomonadales varies. Very often they are taken to include the orders Volvocales and Dunallielales, which contain closely related unicellular flagellates, as suborders.

Chlorellales

The Chlorellales are an order of green algae in the class Trebouxiophyceae.Genera of uncertain placement:

Ankistrodesmopsis

Picochlorum

Chlorococcales

Chlorococcales is an order of green algae in the class Chlorophyceae. Individual specimens are sometimes found in soil, but mostly in fresh and marine waters. The order contains approximately 780 species.Conventionally, many groups of coccoid green algae were lumped in the order Chlorococcales sensu lato by Komárek & Fott (1983), based on Pascher's (1918) idea of establishing orders according to life forms. However, coccoid green algae are currently placed in several orders of Chlorophyceae, Trebouxiophyceae, Ulvophyceae (e.g., Chlorocystis) and Prasinophyceae within the division Chlorophyta, or in the division Charophyta (e.g., Chlorokybales, Desmidiales).

Chlorodendrales

Chlorodendrales are an order of green, flagellated, thecate, unicellular eukaryotes, within the green algae class Chlorodendrophyceae. Prasinophyceae are defined by their cellular scales which are composed of carbohydrates, and Chlorodendrales are unique within this group due to these scales forming a fused thecal wall. Cells of Chlorodendrales are completely covered in scales, which fuse around the cell body producing the theca, but remain individually separated on the flagella, of which there are typically four per cell. Species within Chlorodendrales live in both marine and fresh water habitats, occupying both benthic and planktonic food webs. Additionally, they are photoautotrophs, meaning they produce their own food through the conversion of sunlight into chemical energy.

Cladophorales

Cladophorales are an order of green algae, in the class Ulvophyceae.There is a plausible fossil example in the mid-Ordovician Winneshiek shale

Green algae

The green algae (singular: green alga) are a large, informal grouping of algae consisting of the Chlorophyta and Charophyta/Streptophyta, which are now placed in separate divisions, as well as the potentially more basal Mesostigmatophyceae, Chlorokybophyceae and Spirotaenia.The land plants, or embryophytes, are thought to have emerged from the charophytes. Therefore, cladistically, embryophytes belong to green algae as well. However, because the embryophytes are traditionally classified as neither algae nor green algae, green algae are a paraphyletic group. Since the realization that the embryophytes emerged from within the green algae, some authors are starting to include them. The clade that includes both green algae and embryophytes is monophyletic and is referred to as the clade Viridiplantae and as the kingdom Plantae. The green algae include unicellular and colonial flagellates, most with two flagella per cell, as well as various colonial, coccoid and filamentous forms, and macroscopic, multicellular seaweeds. There are about 8,000 species of green algae. Many species live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds.

A few other organisms rely on green algae to conduct photosynthesis for them. The chloroplasts in euglenids and chlorarachniophytes were acquired from ingested green algae, and in the latter retain a nucleomorph (vestigial nucleus). Green algae are also found symbiotically in the ciliate Paramecium, and in Hydra viridissima and in flatworms. Some species of green algae, particularly of genera Trebouxia of the class Trebouxiophyceae and Trentepohlia (class Ulvophyceae), can be found in symbiotic associations with fungi to form lichens. In general the fungal species that partner in lichens cannot live on their own, while the algal species is often found living in nature without the fungus. Trentepohlia is a filamentous green alga that can live independently on humid soil, rocks or tree bark or form the photosymbiont in lichens of the family Graphidaceae. Also the macroalga Prasiola calophylla (Trebouxiophyceae) is terrestrial, and

Prasiola crispa, which live in the supralittoral zone, is terrestrial and can in the Antarctic form large carpets on humid soil, especially near bird colonies.

Mamiellophyceae

Mamiellophyceae is a class of green algae in the division Chlorophyta.

Prasinophyceae

The Prasinophytes (incl. Tetraphytina) or chlorophyta are a class of unicellular green algae. Prasinophytes mainly include marine planktonic species, as well as some freshwater representatives. The prasinophytes are morphologically diverse, including flagellates with one to eight flagella and non-motile (coccoid) unicells. The cells of many species are covered with organic body scales; others are naked. Well studied genera include Ostreococcus, considered to be the smallest (ca. 0.95 μm) free-living eukaryote, and Micromonas, both of which are found in marine waters worldwide. Prasinophytes have simple cellular structures, containing a single chloroplast and a single mitochondrion. The genomes are relatively small compared to other eukaryotes (about 12 Mbp for Ostreococcus and 21 Mbp for Micromonas).

Some authors treat the prasinophytes as a non-evolutionary grouping (paraphyletic) of green algae from different clades. As the Tetraphytina emerged in the Prasinophytes, recently authors include it, rendering it monophyletic, and equivalent to chlorophyta.

Pseudoscourfieldiales

Pseudoscourfieldiales is an order of green algae in the class Pyramimonadophyceae.

Pyramimonadales

Pyramimonadales are an order of green algae in the Chlorophyta.

Scourfieldiales

Scourfieldiales is an order of green algae in the class Pedinophyceae.

Sphaeropleales

Sphaeropleales is an order of green algae that used to be called Chlorococcales. The order includes some of the most common freshwater planktonic algae such as Scenedesmus and Pediastrum. The Spaeropleales includes vegetatively non-motile unicellular or colonial taxa that have biflagellate zoospores with flagella that are directly opposed in direction (the DO arrangement): Sphaeroplea, Atractomorpha, Neochloris, Hydrodictyon, and Pediastrum. All of these taxa have basal body core connections.With an increase in the number of taxa for which sequence data are available, there is evidence of an expanded DO clade that includes additional zoosporic (Bracteacoccus, Schroederia) and some strictly autosporic genera such as Ankistrodesmus, Scenedesmus, Selenastrum, and Monoraphidium. The filamentous Microspora has been allied with the coccoid genus Bracteacoccus based on molecular data.

Monophyly of the DO clade is supported by phylogenetic analysis of multi-gene data.

Streptophyta

Streptophyta, informally the streptophytes (from the Greek strepto, for twisted, i.e., the morphology of the sperm of some members), is a clade of plants. The composition of the clade varies considerably between authors, but the definition employed here includes land plants and all green algae except the Chlorophyta and possibly the more basal Mesostigmatophyceae, Chlorokybophyceae, and Spirotaenia.

Trebouxiophyceae

The Trebouxiophyceae are a class of green algae, in the division Chlorophyta. Their circumscription within the green algae is not well established due to the need for more genetic studies at higher levels within the group.Genera without intervening taxonomy include:

Choricystis

Crucigenia

Koliellopsis

Leptosira

Rhopalosolen

Viridiella

Prototheca

Ulotrichales

Ulotrichales is an order of green algae in the class Ulvophyceae.Genera unplaced to family (incertae sedis):

Trichosarcina

Ulvales

Ulvales is an order of green algae.

Viridiplantae

Viridiplantae (literally "green plants") are a clade of eukaryotic organisms made up of the green algae, which are primarily aquatic, and the land plants (embryophytes), which emerged within them. Green algae traditionally excludes the land plants, rendering them a paraphyletic group. Since the realization that the embryophytes emerged from within the green algae, some authors are starting to include them. They have cells with cellulose in their cell walls, and primary chloroplasts derived from endosymbiosis with cyanobacteria that contain chlorophylls a and b and lack phycobilins. More than 350,000 species of Viridiplantae exist.In some classification systems, the group has been treated as a kingdom, under various names, e.g. Viridiplantae, Chlorobionta, or simply Plantae, the latter expanding the traditional plant kingdom to include the green algae. Adl et al., who produced a classification for all eukaryotes in 2005, introduced the name Chloroplastida for this group, reflecting the group having primary chloroplasts with green chlorophyll. They rejected the name Viridiplantae on the grounds that some of the species are not plants, as understood traditionally. The Viridiplantae are made up of two clades: Chlorophyta and Streptophyta as well as the basal Mesostigmatophyceae and Chlorokybophyceae. Together with Rhodophyta and glaucophytes, Viridiplantae are thought to belong to a larger clade called Archaeplastida or Primoplantae.

A taxonomic evaluation of eukaryotes based on myosin distribution showed the Viridiplantae lost class-I myosins.

Rhodophyta
(red algae)
Glaucocystophyta
(glaucophytes)
Viridiplantae
(green algae,
& land plants)
Extant Life phyla/divisions by domain

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