Zoothamnium Snowy
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| Научная классификация | |
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| Разновидность: | З. Белый
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| Биномиальное название | |
| Zoothamnium Snowy | |
Zoothamnium niveum -это вид ресничного простейшего , который образует колонии в форме перья в морской прибрежной среде. Ресинкости образуют симбиоз с окисляющими серной хемосинтетическими бактериями вида « Candidatus thiobios Zoothamnicoli», которые живут на поверхности колоний и дают им необычный белый цвет.
Характеристики
[ редактировать ]Явно белые колонии в форме перья состоит из отдельных колоколообразных клеток, известных как зооиды . Стаи отдельных клеток растут из одного центрального стебля. Колонии могут достигать длины до 15 мм, сформированных из сотен отдельных зооидов, каждый с длиной всего 120 мкм. Целая колония может сразиться в кучу в форме мяча через сокращение минемэмов в их стеблях. [ 2 ] [ 3 ]
Белый цвет производится хемолитоаутотрофными бактериями, окисляющимися серой, которые покрывают всю поверхность колонии Z. niveum . [ 4 ] У большинства других видов Zoothamnium бактерии, как известно, покрывают только стебли. Бактерии содержат элементарную серу , которая выглядит белой. Z. Niveum кажется бесцветным, когда бактерии отсутствуют. [ 3 ]
Как и в других ресничках, сократительная вакуоль поддерживает осмотический баланс для клетки и позволяет ей пережить концентрации соли как в морской, так и в солоноватой воде. Вакуоль расположена в Z. niveum непосредственно под губой перистома . [ 2 ]
Polymorphism
[edit]Most ciliates live as single-celled organisms in aquatic environments, and the single cell carries out all functions of life, such as nutrition, metabolism, and reproduction. Colonies of Z. niveum are composed of numerous individual cells that form a feather-like colonial unit, with several different cell types. Old branches of the colony illustrate the polymorphism of the zooids when viewed under the microscope. Three different forms of the individual ciliate cells are present, which are distinct in both form and function. The large macrozooids can transform into swarmers and leave the colony. They settle on suitable surfaces and develop into new colonies. The microzooids are small cells specialized for feeding, which the colony does by consumption of their symbiotic bacteria and other organic particles. At the terminal ends of the colony are specialized zooids that can elongate and facilitate the asexual reproduction of the colony.[2]
The bacteria on different parts of a host have different shapes despite belonging to the same species (polymorphism). Those on the stalks are shaped like rods, but those in the region of the ciliated oral apparatus of the microzooids are shaped like small spheres (coccoid). Intermediate forms are also found in between.[4]
Distribution and habitat
[edit]The sessile colonies of Z. niveum were first described from the shallow waters of the Red Sea.[5] They were later also found in the Florida Keys in the Gulf of Mexico, and at the Belize Barrier Reef in the Caribbean Sea.[3]
The colonies settle in environments that contain sulfide. Hydrogen sulfide, sulfide, and related sulfur-containing compounds like thiosulfate are produced during the decomposition and remineralization of organic material. For example, plant material like the torn-off leaves of Posidonia oceanica in seagrass meadows of the Mediterranean accumulate in depressions of rocky ledges and decompose. In mangrove forests of the Caribbean, organic material can form peat and release sulfide.[6] Hydrogen sulfide can also originate from geological phenomena such as at underwater hydrothermal vents, e.g. off the Canary Islands.
Ecological conditions
[edit]Extreme ecological conditions prevail at these sources of sulfide close to which colonies of Z. niveum settle. Because there is little water current under mangrove roots and at seagrass deposits under rock ledges, these decomposition hot-spots are extremely poor in oxygen and rich in sulfide. In mangrove forests off the coast of Belize, they have been found around small holes in the mangrove peat which form when the mangrove rootlets decompose.[6] These openings have been called sulfide "microvent[s]",[7] because they resemble in miniature the hydrothermal vents of the deep sea, the so-called black smokers, although the temperatures in shallow waters are much lower (28 °C in the Caribbean, 21 °C-25 °C in the Mediterranean (summer)), compared to the gradient between >300 °C and 2 °C in the deep sea because of volcanic activity. The Zoothamnium colonies do not settle directly over the decomposing material, but nearby e.g. on overhanging rocks, leaves of seagrass or seaweed, or mangrove roots.[3]
Symbiosis
[edit]The symbiotic benefits provided by the colonies of Z. niveum for its attached ectosymbiotic bacteria Candidatus Thiobios zoothamnicoli (a member of the Gammaproteobacteria[4]), which are vertically transmitted to its host,[8] are its active alternation between oxygen-rich and sulfide-rich conditions. This alternation can occur through the regular contraction and extension of the colonies and through the water currents set up by the beating of the cilia in the region of the oral opening of the ciliates.[9]
The rapid contraction and slow re-extension of the colonies causes a flow of both sulfide-rich water for the feeding of the bacteria and normal oxygenated seawater for the respiration of Z. niveum. Through the beating of its cilia at the oral apparatus of Zoothamnium is the mixing regulated. When there is a low supply of sulfur compounds, the bacteria use the sulfur that is stored inside their cells. They eventually appear pale and transparent after four hours because the stored sulfur has been consumed. However, if the sulfide concentration is too high, it can be toxic to the Zoothamnium colonies and kill the ciliates despite the bacteria.[9]
Bacteria close to the oral end of the microzooids have a coccoid form, a larger volume, and a higher division rate than the rod-shaped bacteria on the stalks, despite both belonging to the same species. This is because the mixing of water by the beating of the oral cilia result in a more optimal concentration of both oxygen and sulfide in the water there.[9] The bacteria at the oral region can thus be used as a food source and are swirled into the mouth (cytostome) of the ciliate and digested.
References
[edit]- ^ Warren, Alan (2009). "Zoothamnium niveum Ehrenberg, 1838". WoRMS. World Register of Marine Species. Retrieved 9 August 2017.
- ^ Jump up to: a b c Bauer-Nebelsick, Monika; Bardele, Christian F.; Ott, Jörg A. (1996). "Redescription of Zoothamnium niveum (Hemprich & Ehrenberg, 1831) Ehrenberg, 1838 (Oligohymenophora, Peritrichida), a ciliate with ectosymbiotic, chemoautotrophic bacteria". European Journal of Protistology. 32 (1): 18–30. doi:10.1016/s0932-4739(96)80036-8.
- ^ Jump up to: a b c d Bright, Monika; Espada-Hinojosa, Salvador; Lagkouvardos, Ilias; Volland, Jean-Marie (2014). "The giant ciliate Zoothamnium niveum and its thiotrophic epibiont Candidatus Thiobios zoothamnicoli: a model system to study interspecies cooperation". Frontiers in Microbiology. 5: 145. doi:10.3389/fmicb.2014.00145. ISSN 1664-302X. PMC 3985026. PMID 24778630.
- ^ Jump up to: a b c Rinke, Christian; Schmitz-Esser, Stephan; Stoecker, Kilian; Nussbaumer, Andrea D.; Molnár, Dávid A.; Vanura, Katrina; Wagner, Michael; Horn, Matthias; Ott, Jörg A. (March 2006). ""Candidatus Thiobios zoothamnicoli," an ectosymbiotic bacterium covering the giant marine ciliate Zoothamnium niveum". Applied and Environmental Microbiology. 72 (3): 2014–2021. doi:10.1128/AEM.72.3.2014-2021.2006. ISSN 0099-2240. PMC 1393213. PMID 16517650.
- ^ Готфрид, Эренберг, Кристиан (1838). «Инфузия Тьерчен как совершенные организмы» (на немецком языке). [Текст Pt.2]. Л. Восс.
{{cite journal}}: CITE Journal требует|journal=( Справка ) CS1 Maint: несколько имен: список авторов ( ссылка ) - ^ Jump up to: а беременный Ott, Jörg A.; Яркая, Моника; Schiemer, Friedrich (1998-09-01). «Экология нового симбиоза между морским перитричским реснихом и химитотрофными бактериями». Морская экология . 19 (3): 229–243. Bibcode : 1998marec..19..229o . doi : 10.1111/j.1439-0485.1998.tb00464.x . ISSN 1439-0485 .
- ^ Вопель, Кей; Чотоподобный, Дэвид; Отт, Йорг; Яркая, Моника; Røy, Hans (2005-01-01). «Индуцированный волной поток H2S поддерживает химитотрофический симбиоз» (PDF) . Лимнология и океанография . 50 (1): 128–133. Bibcode : 2005limoc..50..128V . doi : 10.4319/lo.2005.50.1.0128 . HDL : 10292/1466 . ISSN 1939-5590 .
- ^ Яркий, м.; Espada -inojosa, S.; Волланд, JM; Drexel, J.; Kesting, J.; Колар, я.; Morchner, D.; Nussbaumer, A.; Opt, J.; Scharhauser, F.; Schuster, L.; Замбалос, HC; Nemeschkal, HL (2019). «Тотрофический бактериальный симбионт индуцирует полифенизм в гигантском хозяине килиаты Zoothamnium niveum» . Научные отчеты . 9 (1): 15081. Bibcode : 2019natsr ... 915081b . Doi : 10.1038/s41598-019-51511-3 . PMC 6803713 . PMID 31636334 .
- ^ Jump up to: а беременный в Ринке, Кристиан; Ли, Рэймонд; Кац, Сигрид; Брайт, Моника (2007-09-22). «Влияние сульфида на рост и поведение титотрофического Zoothamnium niveum symbiosis» . Труды Королевского общества B: Биологические науки . 274 (1623): 2259–2269. doi : 10.1098/rspb.2007.0631 . ISSN 0962-8452 . PMC 1950315 . PMID 17660153 .
Литература
[ редактировать ]- Кристиан Ринке, Йорг А. Отт Ун и Моника Брайт: «Процессы питания в химиоаутотрофных Zoothamnium Niveum Symbioses», Симпозиум биологии тропической мелководье, среда обитания, Lunz, österreich, Oktober 2001, S. 19-21