Name: rhizaria: pseudopods, tests, and skeletons
Uploaded: 2025-06-12T06:30:33.000Z
Duration: 1 min 27 s
Channel: JoVE

Rhizaria, iplik benzeri psödopodia'ya sahip çeşitli bir protist grubunu temsil eder. Üç ana alt grup vardır - Chlorarachniophyta, Foraminifera ve Radiolaria. Chlorarachniophyta, hem tatlı su hem de deniz ortamlarında bulunan fototrofik protistlerdir. Sekonder endosimbiyoz sırasında edinilen alg endosimbiyontları nedeniyle dört zarlı kloroplastları vardır. Foraminiferler, kalsiyum karbonat ve organik materyalden oluşan, test adı verilen kabuk benzeri yapılar inşa eden kesinlikle deniz protistleridir. Çoğu foraminiferan, okyanus tabanındaki çürüyen organik maddeler, bakteriler veya diğer küçük protistlerle beslenmek için testlerinden dışarıya doğru uzanır. Bazı foraminiferler planktoniktir ve besinler için endosimbiyotik alglere ev sahipliği yapar. Radyolaryalılar deniz planktonik kemoorganotroflarıdır. Silika içeren testlere sahiptirler. Radiolarians, okyanusun üst 100 m'sinde yaşar ve burada lipit damlacıkları, büyük sitoplazmik vakuoller ve iğne benzeri psödopodia tarafından asılı kalırlar. Bakteri ve organik maddelerle beslenirler. Buna karşılık, diğer bazı türler alglerle simbiyotik, ancak endosimbiyotik olmayan ilişkiler kurar.

protist Çeşitliliği-iii

Diversity of Protists III

Rhizaria, ipliksi sitoplazmik uzant&#305;lar olan yalanc&#305; ayaklar&#305; (pseudopodlar) ile karakterize edilen &#231;e&#351;itli tek h&#252;creli protist grubudur. Bu yap&#305;lar hem hareket hem de beslenmede rol oynar ve Rhizaria'ya amipsi bir g&#246;r&#252;n&#252;m kazand&#305;r&#305;r. Amipsi morfolojileri, bir zamanlar taksonomik kar&#305;&#351;&#305;kl&#305;klara neden olmu&#351;sa da, molek&#252;ler filogenetik &#231;al&#305;&#351;malar&#305;, evrimsel konumlar&#305;n&#305; netle&#351;tirmi&#351; ve farkl&#305; soy hatlar&#305;na ra&#287;men yalanc&#305; ayak kullan&#305;m&#305;n&#305;n ortak oldu&#287;unu vurgulam&#305;&#351;t&#305;r.
Bu klad, farkl&#305; ekolojik ni&#351;lere uyum sa&#287;lam&#305;&#351; ve &#231;e&#351;itli metabolik stratejiler sergileyen Chlorarachniophyta, Radiolaria ve Foraminifera gibi &#231;ok &#231;e&#351;itli soy hatlar&#305;n&#305; i&#231;erir.
Chlorarachniophyta
Chlorarachniophyta, denizel ve tatl&#305; su ortamlar&#305;nda bulunan, fotosentetik tek h&#252;creli protistlerdir. Bu grup, fotosentetik olmayan bir &#246;karyotik canl&#305;n&#305;n, fotosentetik bir alg &#246;karyotunu yutmas&#305;yla ger&#231;ekle&#351;en ikincil endosimbiyozun tipik bir &#246;rne&#287;idir. Genellikle iki zara sahip olan birincil plastitlerin aksine, chlorarachniophyta kloroplastlar&#305; d&#246;rt zarla &#231;evrilidir ve yutulan alge ait kal&#305;nt&#305; bir &#231;ekirdek olan n&#252;kleomorfu korur. Bu n&#252;kleomorf, plastit entegrasyonunda nadir g&#246;r&#252;len ara bir durumu temsil eder ve endosimbiyotik olay&#305;n genomik ve yap&#305;sal kan&#305;tlar&#305;n&#305; korur.
Chlorarachniophyta'n&#305;n genetik yap&#305;s&#305; ola&#287;an&#252;st&#252; derecede karma&#351;&#305;kt&#305;r. En az be&#351; genom ta&#351;&#305;rlar: (1) konak h&#252;cre &#231;ekirdek genomu, (2) konak mitokondriyal genomu, (3) n&#252;kleomorf genomu, (4) alg mitokondriyal genomu ve (5) plastit genomu. Evrimsel s&#252;re&#231; boyunca, endosimbiyonttan bir&#231;ok gen konak &#231;ekirde&#287;ine aktar&#305;lm&#305;&#351;t&#305;r; bu da n&#252;kleomorf ve kloroplast i&#231;inde genom daralmas&#305;na yol a&#231;m&#305;&#351;t&#305;r. Bu genomik entegrasyon, i&#351;levsel fazlal&#305;klar&#305;n ortadan kald&#305;r&#305;ld&#305;&#287;&#305; veya yeniden atand&#305;&#287;&#305; evrimsel sadele&#351;meyi yans&#305;t&#305;r.
Foraminifera
Foraminiferler, genellikle kalsiyum karbonattan olu&#351;an karma&#351;&#305;k d&#305;&#351; iskeletler (testler) in&#351;a eden denizel amipsi protistlerdir. Bu testler canl&#305; h&#252;crenin bir par&#231;as&#305; de&#287;ildir; yap&#305;sal koruma sa&#287;lar ve yalanc&#305; ayaklarla beslenmeyi destekler. Bentik foraminiferler okyanus taban&#305;nda ya&#351;ar, organik partik&#252;l maddeyle beslenir ve alglerle besin al&#305;&#351;veri&#351;ine dayal&#305; simbiyotik ili&#351;kiler kurarlar. Planktonik t&#252;rler ise fotosentetik endosimbiyontlara ev sahipli&#287;i yapar ve g&#252;ne&#351; &#305;&#351;&#305;&#287;&#305;n&#305;n eri&#351;ilebilir oldu&#287;u &#252;st okyanus katmanlar&#305;nda ya&#351;ar.
Foraminifer testlerinin fosille&#351;me potansiyeli, onlar&#305; biyostratigrafi ve petrol jeolojisi a&#231;&#305;s&#305;ndan vazge&#231;ilmez k&#305;lar. Jeolojik katmanlar aras&#305;ndaki da&#287;&#305;l&#305;mlar&#305;, tortul katmanlar&#305;n g&#246;reli ya&#351;&#305;n&#305; tahmin etmeye ve petrol rezervlerinin varl&#305;&#287;&#305;n&#305; de&#287;erlendirmeye yard&#305;mc&#305; olur.
Radiolaria
Radyolaryenler esas olarak y&#252;zey sular&#305;nda ya&#351;ayan planktonik deniz protistleridir. Simetrik, silisyum bazl&#305; iskeletleri olduk&#231;a s&#252;sl&#252;d&#252;r ve &#246;l&#252;mden sonra bozulmadan kal&#305;r, deniz taban&#305;nda silisli tortulara katk&#305;da bulunur. Radyolaryenler, organik art&#305;klar ve bakterilerle beslenir ve zaman zaman alglerle simbiyotik ili&#351;kiler kurarlar. Foraminiferlerin aksine, radyolaryenler endosimbiyoz yapmazlar. Y&#252;zebilirlikleri, lipid i&#231;eren yap&#305;lar, kofullar ve yer&#231;ekimine kar&#351;&#305; koyan sert yalanc&#305; ayaklar sayesinde sa&#287;lan&#305;r.

Protist Çeşitliliği-III

Rhizaria, ipliksi sitoplazmik uzant&#305;lar olan yalanc&#305; ayaklar&#305; (pseudopodlar) ile karakterize edilen &#231;e&#351;itli tek h&#252;creli ...

Education

JoVE Core

Microbiology

Mikrobiyoloji

Unit

Birim

Microbial Diversity

Mikrobiyal Çeşitlilik

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

rhizaria: pseudopods, tests, and skeletons

Rhizaria are unicellular protists with threadlike pseudopodia, which are thin cytoplasmic extensions used for movement and feeding. Their amoeboid shape once caused taxonomic confusion, but molecular phylogenetics has since shown where they fit on the evolutionary tree. This group includes Chlorarachniophyta, Radiolaria, and Foraminifera, and each lineage has adapted to a different ecological niche and metabolic strategy.

Chlorarachniophyta are unicellular phototrophic protists found in marine and freshwater environments. They are a clear example of secondary endosymbiosis, where a non-photosynthetic eukaryotic host engulfed a photosynthetic algal eukaryote. Their chloroplasts have four membranes, unlike the two membranes seen in primary plastids, and they also keep a nucleomorph, which is the vestigial nucleus of the engulfed alga.

Chlorarachniophytes also have unusually complex genetics. At least five genomes are present: the host nuclear genome, the host mitochondrial genome, the nucleomorph genome, the algal mitochondrial genome, and the plastid genome. Over time, many genes moved from the endosymbiont to the host nucleus. This left the nucleomorph and chloroplast reduced and shows how cells can streamline after endosymbiosis.

Foraminifera are marine amoeboid protists that build tests, which are protective shells often made of calcium carbonate. The test is not part of the living cell, but it supports the cell and helps with feeding through pseudopodia. Benthic foraminiferans live on the ocean floor and feed on particulate organic matter, and some also form nutrient-exchange symbioses with algae.

Other foraminiferans are planktonic and live in the upper ocean where sunlight is available. These species can host phototrophic endosymbionts. Their tests fossilize well, which makes foraminifera useful in biostratigraphy and petroleum geology. Scientists use their fossils to compare the relative age of sediment layers and to help judge where oil deposits may be found.

Radiolaria are mostly planktonic marine protists found in surface waters. They have ornate, symmetrical skeletons made of silica, and these structures remain after death to form siliceous ooze on the seafloor. Radiolarians feed on organic detritus and bacteria, and some live with algae in symbiosis. Unlike foraminifera, they do not use endosymbiosis. Their buoyancy comes from lipid inclusions, vacuoles, and stiff pseudopodia that help keep them from sinking.

Rhizaria: Pseudopods, Tests, and Skeletons

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diversity of protists iii

Rhizaria are unicellular protists with threadlike pseudopodia, which are thin cytoplasmic extensions used for movement and feeding. Their amoeboid shape once caused taxonomic confusion, but molecular phylogenetics has since shown where they fit on the evolutionary tree. This group includes Chlorarachniophyta, Radiolaria, and Foraminifera, and each lineage has adapted to a different ecological niche and metabolic strategy. Chlorarachniophyta are unicellular phototrophic protists found in marine...

diversity of protists iv

Amoebozoa: Movement and Life Cycles

Amoebozoa are a diverse group of terrestrial and aquatic protists. They move and feed with lobe-shaped pseudopodia. This feature sets them apart from Rhizaria, which have threadlike pseudopodia. The group includes gymnamoebas, entamoebas, and the plasmodial and cellular slime molds. Phylogenetic evidence also shows that Amoebozoa split from a lineage that later gave rise to fungi and animals. Gymnamoebas are free-living protists that live in water and soil. They move by amoeboid movement,...

key terms and concepts

Explore Rhizaria in high school biology, including pseudopodia, chlorarachniophytes, foraminifera, and radiolarians with their unique structures and roles.

Rhizaria: Pseudopods, Tests, and Skeletons | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Rhizaria: Pseudopods, Tests, and Skeletons

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