Cryptomonas

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Cryptomonas
Systematics
Classification : Creature
Domain : Eukaryotes (eukaryota)
incertae sedis
without rank: Cryptophyceae
without rank: Cryptomonadales
Genre : Cryptomonas
Scientific name
Cryptomonas
Ehrenberg 1831, emend. Hoef-Emden & Melkonian , 2003

Cryptomonas is the eponymous genus of the Cryptophyceae . As with all plastid- containing Cryptophyceae, these are unicellularalgaeequipped with two flagella and only visible with a light microscope . The cells arecolored light, olive to dark brownby the xanthophyll alloxanthin. In addition to the flagellated stages, Cryptomonas species can also form palm cells and cysts . Palmelles are clumps of mucus with flagellated cells embedded in them. It is believed that palmella serve as protection against predatory zooplankton. Cysts are rounded and immobile permanent stages protected by a strong cell wall, which serve to survive under unfavorable environmental conditions.

The genus seems to be the only Cryptophyceae genus to be restricted to freshwater. Cryptomonas species are present in almost all lakes. As weak light specialists, Cryptomonas species often form dense populations in deeper layers near the chemocline or in winter under the ice.

Systematics of Cryptomonas

The generic name was introduced in 1831 by Christian Gottfried Ehrenberg . Since then, well over 100 Cryptomonas species have been described on the basis of features that can be recognized by light microscopy. Since the characteristics that were considered to be genus-specific changed several times, they also included marine Cryptomonas species.

With the introduction of electron microscopic methods, differences in the ultrastructure of the cells were used to narrow the definition of the genus. Since then, the following features have been considered to be genus-specific: polygonal periplastic plates on the inside of the plasma membrane and fibrillar material on the outside, a microtubular flagellum root (rhizostyle) directed backwards without lamella-like appendages, a cell invagination in the form of a bag closed at the back with a slit-shaped opening at the front (Combination of throat and furrow) and a phycoerythrin with an absorption maximum at 566 nm as a light-collecting complex .

Today only those species are counted in the genus, whose membership of Cryptomonas was confirmed in molecular-phylogenetic analyzes. Combined studies of morphology and phylogeny on the basis of clonal cultures found evidence of a life cycle with two different cell shapes. Until then, Proteomonas was considered the only dimorphic Cryptophyceae genus. The morphology of the alternative cell type in the dimorphic Cryptomonas cultures corresponded to the freshwater genus Campylomonas described in 1991 (morphological differences to Cryptomonas : inner periplastic component consisting of a continuous leaf and a long rhizostyle equipped with lamellae). This showed that Campylomonas is not a separate genus, but a stage in the life cycle of Cryptomonas . It could also be proven that the genus Chilomonas , which differed from Campylomonas only by colorless plastids, had developed from photosynthetic Cryptomonas species. The genera Campylomonas and Chilomonas were therefore declared to be synonyms of the genus Cryptomonas . The dimorphism suggests that there could be biological species with sexual reproduction in Cryptomonas .

Cryptomonas species

Since at the time of CG Ehrenberg there were no nomenclature codes ( ICBN , ICZN ) in which rules for the valid description of genera and species were laid down, Ehrenberg did not include a type in the description and illustration of the first four Cryptomonas species or later. Type defined. A lectotyping according to the rules of the ICBN, in which Cryptomonas curvata was identified as a type species, did not take place until 120 years later.

During extensive light microscopic investigations on clonal cultures, Ernst Georg Pringsheim already found that it is practically impossible to reliably differentiate Cryptomonas species from one another due to the lack of clear morphological features . Pringsheim's observations could be confirmed in a later work. There are only a few species that can be clearly identified by their morphological features, most of them are cryptic species . For this reason, Cryptomonas species were newly described or modified in two revisions with the aid of molecular-phylogenetic pedigrees and with DNA sequences as diagnostic features. The species that can be recognized by light microscopy include the campylomorphic cell types of Cryptomonas curvata , C. pyrenoidifera and C. gyropyrenoidosa and the cryptomorphic cell types of C. ovata and C. tetrapyrenoidosa .

literature

  1. ^ A b D. Klaveness: Ecology of the Cryptomonadida: A First Review. In: CD Sandgren (Ed.): Growth and Reproductive Strategies of Freshwater Phytoplankton. Cambridge University Press, Cambridge 1988, pp. 105-133.
  2. ↑ C. Lichtlé: Effects of nitrogen deficiency and light of high intensity on Cryptomonas rufescens (Cryptophyceae). I. Cell and photosynthetic transformations and encystment. In: Protoplasm. 101, 1979, pp. 283-299.
  3. ↑ C. Lichtlé: Effects of nitrogen deficiency and light of high intensity on Cryptomonas rufescens (Cryptophyceae). II. Excystment. In: Protoplasm. 102, 1980, pp. 11-19.
  4. ^ F. Gervais: Ecology of cryptophytes coexisting near a freshwater chemocline. In: Freshw Biol. 39, 1998, pp. 61-78.
  5. ↑ C. Pedrós-Alió, JM Gasol, R. Guerrero: On the ecology of a Cryptomonas phaseolus population forming a metalimnetic bloom in Lake Cisó, Spain: Annual distribution and loss factors. In: Limnol Oceanogr. 32, 1987, pp. 285-298.
  6. ↑ CG Ehrenberg (ed.): Symbolae physicae seu icones et descriptiones animalium evertebratorum sepositis insectis quae ex itinere per Africanum Borealem et Asiam Occidentalem Friderici Guilelmi Hemprich et Christiani Godofredi Ehrenberg medicinae et chirurgiae doctorum studio novae aut illustratae redierunt. Mittler, Berlin 1831.
  7. ↑ G. Huber-Pestalozzi: The phytoplankton of fresh water. Part 3: Cryptophyceae, Chloromonadophyceae, Dinophyceae. In: H.-J. Elster, W. Ohle (Ed.): The inland waters. Volume XVI, 2nd edition. E. Schweizerbart'sche Verlagbuchhandlung, Stuttgart 1950.
  8. ↑ RW Butcher: An introductory account of the smaller algae of British Coastal waters. Part IV: Cryptophyceae. Fishery Investigations. Ministry of Agriculture, Fisheries & Food, HMSO, London 1967, Ser IV.
  9. ↑ a b B. L. Clay, P. Kugrens, RE Lee: A revised classification of the Cryptophyta. In: Bot J Linnean Soc. 131, 1999, pp. 131-151.
  10. ↑ a b G. Novarino: A companion to the identification of crypto monad flagellates (cryptophyceae = Cryptomonadea). In: Hydrobiologia. 502, 2003, pp. 225-270.
  11. ↑ a b c d e f K. Hoef-Emden, M. Melkonian: Revision of the genus Cryptomonas (Cryptophyceae): a combination of molecular phylogeny and morphology provides insights into a long-hidden dimorphism. In: Protist. 154, 2003, pp. 371-409.
  12. ↑ DRA Hill, R. Wetherbee: Proteomonas sulcata gen. Et sp. nov. (Cryptophyceae), a cryptomonad with two morphologically distinct and alternating forms. In: Phycologia. 25, 1986, pp. 521-543.
  13. ↑ DRA Hill: A revised circumscription of Cryptomonas (Cryptophyceae) based on examination of Australian strains. In: Phycologia. 30, 1991, pp. 170-188.
  14. ↑ The Tree of Life Web Project: Phylogeny of the genus Cryptomonas Ehrenberg
  15. ↑ CG Ehrenberg: On the development and lifespan of infusion animals; along with further contributions to a comparison of their organic systems. In: Abh Königl Akad Wiss Berlin, physics class. 1832, 1831, pp. 1-154.
  16. ↑ CG Ehrenberg: The infusion animals as perfect organisms: A look into the deeper organic life of nature. With an atlas of colored copper plates. Voss, Leipzig 1838.
  17. ↑ EG Pringsheim: On the knowledge of the cryptomonads of fresh water. In: Nova Hedwigia. 16, 1968, pp. 367-401.
  18. ↑ a b K. Hoef-Emden: Revision of the genus Cryptomonas (Cryptophyceae) II: Incongruences between the classical morphospecies concept and molecular phylogeny in smaller pyrenoid-less cells. In: Phycologia. 46, 2007, pp. 402-428.

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