Name: amoebozoa: movement and life cycles
Uploaded: 2025-06-05T06:27:20.000Z
Duration: 1 min 27 s
Channel: JoVE

Amoebozoa protistleri, lob şeklindeki psödopodia ile karakterizedir. Gymnamoebas, entamoebas ve plazmodial ve hücresel balçık kalıplarını içerir. Amoeba türleri gibi gymnamoebalar, su ve toprak ortamlarında yaşayan serbest yaşayan protistlerdir. Buna karşılık, entamoebalar parazittir ve esas olarak omurgalıların ve omurgasızların ağız boşluğunda veya bağırsak sisteminde yaşarlar. İnsan patojeni Entamoeba histolytica dikkate değer bir örnektir. Balçık küfleri, dağılmak için sporlar içeren meyve veren cisimler üreten hareketli mantar benzeri protistlerdir. Physarum gibi plazmodyal balçık küfleri tipik olarak vejetatif aşamalarında birden fazla diploid çekirdek içeren bir plazmodyum olarak bilinen tek bir kütle olarak bulunur. Bir plazmodyum hareketlidir ve haploid sporlar içeren sporangia üretir. Uygun koşullar altında, bu sporlar, bir diploid plazmodyumu yeniden oluşturmak için birleşen kamçılı sürü hücrelerine dönüşür. Buna karşılık, Dictyostelium gibi hücresel balçık küfleri, vejetatif durumlarında bireysel haploid hücreler olarak bulunur. Açlıktan ölürlerse bir araya toplanırlar, hareketli kütleler oluştururlar ve meyve veren cisimlere dönüşürler.

protist Çeşitliliği-iv

Diversity of Protists IV

Amoebozoa, karada ve suda ya&#351;ayan, lob &#351;eklinde yalanc&#305; ayaklar (pseudopodia) arac&#305;l&#305;&#287;&#305;yla hareket eden ve beslenen &#231;e&#351;itli protistleri kapsayan bir gruptur. Bu &#246;zellik, onlar&#305; ipliksi yalanc&#305; ayaklara sahip olan Rhizaria'dan ay&#305;r&#305;r. Amoebozoa i&#231;indeki ba&#351;l&#305;ca s&#305;n&#305;fland&#305;rmalar aras&#305;nda gymnamoebalar, entamoebalar ile plazmodiyal ve h&#252;cresel s&#252;m&#252;k k&#252;fleri yer al&#305;r. Filogenetik kan&#305;tlar, Amoebozoa'n&#305;n, nihayetinde mantarlar&#305; ve hayvanlar&#305; olu&#351;turan bir soy hatt&#305;ndan ayr&#305;ld&#305;&#287;&#305;n&#305; g&#246;stermektedir.
Gymnamoebalar ve Entamoebalar
Gymnamoebalar, sucul ve toprak ortamlar&#305;nda serbest ya&#351;ayan protistlerdir. Hareketleri, sitoplazmik ak&#305;&#351;&#305; i&#231;eren amipsi hareket olarak bilinen bir s&#252;re&#231;le, yalanc&#305; ayaklar arac&#305;l&#305;&#287;&#305;yla ger&#231;ekle&#351;ir. Bu mekanizmada, sitoplazma h&#252;crenin &#246;n ucunda daha az kas&#305;lm&#305;&#351; ve daha ak&#305;&#351;kan bir b&#246;lgede ilerleyerek en az diren&#231;li yolu takip eder. Bu ak&#305;&#351;, sitoplazmik zar&#305;n hemen alt&#305;ndaki mikrofilamentler taraf&#305;ndan desteklenir. Gymnamoebalar, &#231;ap&#305; 15 mikrometreden 750 mikrometreyi a&#351;an boyutlara kadar de&#287;i&#351;ebilir; bu son boyut &#231;&#305;plak g&#246;zle g&#246;r&#252;lebilir.
Serbest ya&#351;ayan gymnamoebalar&#305;n aksine, entamoebalar omurgal&#305; ve omurgas&#305;zlar&#305;n a&#287;&#305;z bo&#351;lu&#287;unda ya da ba&#287;&#305;rsak kanal&#305;nda ya&#351;ayan parazitik protistlerdir. &#214;zellikle Entamoeba histolytica, insan patojeni olarak i&#351;lev g&#246;ren anaerobik bir t&#252;rd&#252;r ve amipli dizanteriye neden olur. Bu durum, ba&#287;&#305;rsak kanal&#305;n&#305;n &#252;lserle&#351;mesine ve kanl&#305; ishale yol a&#231;ar. Bu parazit, d&#305;&#351;k&#305; ile kirlenmi&#351; su, g&#305;da ve yemek gere&#231;leri arac&#305;l&#305;&#287;&#305;yla yay&#305;lan kistler yoluyla bula&#351;&#305;r.
S&#252;m&#252;k K&#252;fleri
S&#252;m&#252;k k&#252;fleri, ya&#351;am d&#246;ng&#252;lerinin benzerli&#287;i ve spor i&#231;eren meyve g&#246;vdeleri &#252;retmeleri nedeniyle tarihsel olarak mantarlarla s&#305;n&#305;fland&#305;r&#305;lm&#305;&#351;t&#305;r. Ancak, mantarlardan farkl&#305; olarak s&#252;m&#252;k k&#252;fleri hareket yetene&#287;ine sahiptir ve kat&#305; y&#252;zeyler &#252;zerinde h&#305;zla hareket edebilir. Bu organizmalar, plazmodiyal (asell&#252;ler) s&#252;m&#252;k k&#252;fleri ve h&#252;cresel s&#252;m&#252;k k&#252;fleri olmak &#252;zere iki ana gruba ayr&#305;l&#305;r.
Plazmodiyal s&#252;m&#252;k k&#252;fleri, vejetatif evrelerinde &#231;ok say&#305;da diploid &#231;ekirdek i&#231;eren amorf bir protoplazma k&#252;tlesi olan plazmodiyum formunda bulunur (bu, s&#305;tma hastal&#305;&#287;&#305;na neden olan Plasmodium cinsiyle kar&#305;&#351;t&#305;r&#305;lmamal&#305;d&#305;r). Plazmodiyal s&#252;m&#252;k k&#252;fleri aktif olarak amipsi hareketle hareket ederler. Uygun &#231;evresel ko&#351;ullarda, haploid sporlar i&#231;eren yap&#305;lar olan sporangiumlar&#305; olu&#351;tururlar. Bu sporlar &#231;imlenerek kam&#231;&#305;l&#305; s&#252;r&#252; h&#252;crelerine d&#246;n&#252;&#351;&#252;r; bu h&#252;creler birle&#351;erek diploid bir plazmodiyumu yeniden olu&#351;turur.Physarum iyi bilinen ve &#231;al&#305;&#351;&#305;lm&#305;&#351; bir cinstir.
H&#252;cresel s&#252;m&#252;k k&#252;fleri ise, vejetatif evrelerinde bireysel haploid h&#252;creler olarak kal&#305;r ve yaln&#305;zca belirli &#231;evresel ko&#351;ullarda diploid yap&#305;lar olu&#351;tururlar. &#304;yi &#231;al&#305;&#351;&#305;lm&#305;&#351; bir t&#252;r olan Dictyostelium discoideum, k&#252;mele&#351;me, g&#246;&#231; ve meyve g&#246;vdesi olu&#351;umu ile karakterize edilen e&#351;eysiz bir ya&#351;am d&#246;ng&#252;s&#252;ne sahiptir. A&#231;l&#305;k durumunda, bireysel Dictyostelium h&#252;creleri, h&#252;crelerin f&#252;zyona u&#287;ramadan bireyselliklerini kaybettikleri bir yapay plazmodiyum olu&#351;turmak &#252;zere k&#252;mele&#351;ir. Bu k&#252;mele&#351;me s&#252;reci, kom&#351;u h&#252;creleri &#231;eken bir sinyal molek&#252;l&#252; olan siklik adenozin monofosfat (cAMP) salg&#305;s&#305; ile ba&#351;lat&#305;l&#305;r. S&#252;m&#252;kl&#252; b&#246;cek benzeri bu h&#252;cre kitlesi, hareket kabiliyeti g&#246;sterir; ard&#305;ndan sabit hale ge&#231;erek dikey duruma gelir ve bu noktada meyve g&#246;vdesi olu&#351;umu ba&#351;lar.
Meyve g&#246;vdesi, bir sap ve bir ba&#351; b&#246;l&#252;m&#252;nden olu&#351;ur. Sap h&#252;creleri, yap&#305;sal destek sa&#287;layan sel&#252;loz sentezlerken, ba&#351; h&#252;creleri sporlara d&#246;n&#252;&#351;&#252;r. Bu sporlar yay&#305;ld&#305;ktan sonra &#231;imlenerek yeni amipsi h&#252;crelere d&#246;n&#252;&#351;&#252;r ve ya&#351;am d&#246;ng&#252;s&#252; b&#246;ylece devam eder. E&#351;eysiz &#252;remenin yan&#305; s&#305;ra, Dictyostelium e&#351;eyli &#252;reme de ger&#231;ekle&#351;tirebilir; bu s&#252;re&#231;te iki amip birle&#351;erek dev bir amip olu&#351;turur. Bu yap&#305;, kal&#305;n sel&#252;loz duvarl&#305; bir makrosist haline gelir ve uzun s&#252;re uyku halinde kalabilir. Sonunda, makrosist i&#231;inde mayoz ger&#231;ekle&#351;ir; olu&#351;an haploid &#231;ekirdekler yeni amiplere dahil olarak e&#351;eysiz d&#246;ng&#252;y&#252; yeniden ba&#351;lat&#305;r.

Protist Çeşitliliği-IV

Amoebozoa, karada ve suda ya&#351;ayan, lob &#351;eklinde yalanc&#305; ayaklar (pseudopodia) arac&#305;l&#305;&#287;&#305;yla hareket eden ve beslenen ...

Education

JoVE Core

Microbiology

Mikrobiyoloji

Unit

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Microbial Diversity

Mikrobiyal Çeşitlilik

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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, which depends on pseudopodia and cytoplasmic streaming. In this process, the cytoplasm flows into a less contracted, more fluid region at the front of the cell. Microfilaments just under the cell membrane support this movement. Gymnamoebas also vary widely in size, from about 15 micrometers across to more than 750 micrometers, which can be seen with the naked eye.

Entamoebas are parasitic protists that usually live in the mouth or intestinal tract of vertebrates and invertebrates. Entamoeba histolytica is an anaerobic species and a human pathogen. It causes amebic dysentery, which can ulcerate the intestinal tract and lead to bloody diarrhea. The parasite spreads through cysts that contaminate water, food, and eating utensils.

Slime molds were once grouped with fungi because both can form fruiting bodies that contain spores. Unlike fungi, however, slime molds can move quickly across solid surfaces. They are divided into plasmodial slime molds, also called acellular slime molds, and cellular slime molds. These two groups have different life cycles, but both use spore formation for dispersal.

Plasmodial slime molds live as a plasmodium in the vegetative stage. A plasmodium is an amorphous mass of protoplasm with many diploid nuclei, and it moves by amoeboid movement. When conditions are favorable, it forms sporangia that contain haploid spores. These spores germinate into flagellated swarm cells, which then fuse to form a new diploid plasmodium. Physarum is a well-known genus in this group.

Cellular slime molds stay as individual haploid cells during the vegetative stage. Under certain environmental conditions, they form diploid structures. Dictyostelium discoideum is the best-studied species in this group. Its asexual life cycle includes aggregation, migration, and fruiting body formation, and it can also undergo sexual reproduction. During starvation, cells release cAMP, or cyclic adenosine monophosphate, which attracts nearby cells and triggers aggregation into a pseudoplasmodium. The cells do not fuse, but they lose their individuality and form a moving slug.

The slug later becomes stationary and stands upright before fruiting body formation begins. The fruiting body has a stalk and a head. Stalk cells make cellulose for support, while head cells become spores. After dispersal, the spores germinate into new amoeboid cells. Dictyostelium can also reproduce sexually when two amoebae fuse to form a giant amoeba. This structure develops a thick cellulose wall and becomes a macrocyst that can stay dormant for a long time. Meiosis then occurs inside the macrocyst, producing haploid nuclei that give rise to new amoebae and restart the asexual cycle.

Amoebozoa: Movement and Life Cycles

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diversity of protists i

Excavata Protists and Their Adaptations

Excavata protists show many different ways of living, from photosynthesis to parasitism. This group includes organisms that can use chemical energy, light, or both. Some also live in low-oxygen, or anaerobic, environments where they survive without normal oxygen-based metabolism. Among the main Excavata groups are diplomonads and parabasalids. These are flagellated protists, meaning they move with whip-like tails, and they lack mitochondria and chloroplasts. They often live in anoxic habitats,...

diversity of protists ii

Alveolates: Ciliates, Dinoflagellates, Apicomplexans

Alveolates are protists with tiny sacs called alveoli beneath the cell membrane. These sacs may help control water balance by limiting how much water moves in and out of the cell. In dinoflagellates, alveoli may also act like armor plates. The three main alveolate groups are ciliates, dinoflagellates, and apicomplexans. Ciliates move with cilia, which are short hair-like structures that can cover the whole cell or appear in rows or tufts. One well-known ciliate is Paramecium, which uses cilia...

diversity of protists iii

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...

diversity of protists iv

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

Learn how Amoebozoa move with pseudopodia and how gymnamoebas, entamoebas, and slime molds grow, spread, and reproduce in different life cycles.

Amoebozoa: Movement and Life Cycles | 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

Amoebozoa: Movement and Life Cycles

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