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

Protisty Amoebozoa charakteryzują się pseudopodiami w kształcie płata. Obejmuje gymnamoeby, entameby oraz plazmodialne i komórkowe śluzowce. Gymnamoeby, takie jak gatunki Amoeba, są wolno żyjącymi protistami, które zamieszkują środowiska wodne i glebowe. Natomiast entameby są pasożytnicze i zasiedlają głównie jamę ustną lub przewód pokarmowy kręgowców i bezkręgowców. Godnym uwagi przykładem jest ludzki patogen Entamoeba histolytica. Śluzowce to ruchliwe protisty podobne do grzybów, które wytwarzają owocniki zawierające zarodniki do rozprzestrzeniania się. Śluzowce plazmodialne, takie jak Physarum, zazwyczaj występują jako pojedyncza masa znana jako plasmodium w fazie wegetatywnej, która zawiera wiele diploidalnych jąder. Plasmodium jest ruchliwe i wytwarza sporangia zawierające haploidalne zarodniki. W sprzyjających warunkach zarodniki te przekształcają się w wiciowe komórki roju, które łączą się, aby zregenerować diploidalne zarodźc. W przeciwieństwie do tego, śluzowce komórkowe, takie jak Dictyostelium istnieją jako pojedyncze komórki haploidalne w stanie wegetatywnym. Jeśli zostaną zagłodzone, gromadzą się razem, tworzą ruchliwe masy i przekształcają się w owocniki.

różnorodność protistów – iv

Diversity of Protists IV

Amoebozoa stanowi&#261; zr&#243;&#380;nicowan&#261; grup&#281; protist&#243;w l&#261;dowych i wodnych, kt&#243;re wykorzystuj&#261; p&#322;atowate pseudopodia do poruszania si&#281; i pobierania pokarmu. Ta cecha odr&#243;&#380;nia je od Rhizaria, kt&#243;re posiadaj&#261; nitkowate pseudopodia. G&#322;&#243;wne klasyfikacje w obr&#281;bie Amoebozoa obejmuj&#261; gymnamoebia, entamoeby oraz &#347;luzowce plazmodialne i kom&#243;rkowe. Dowody filogenetyczne wskazuj&#261;, &#380;e Amoebozoa wyewoluowa&#322;y z linii rozwojowej, kt&#243;ra ostatecznie da&#322;a pocz&#261;tek grzybom i zwierz&#281;tom.
Gymnamoebia i Entamoeby
Gymnamoebia to wolno &#380;yj&#261;ce protisty zasiedlaj&#261;ce &#347;rodowiska wodne i glebowe. Poruszaj&#261; si&#281; za pomoc&#261; pseudopodi&#243;w w procesie zwanym ruchem ameboidalnym, kt&#243;ry polega na pr&#261;dach cytoplazmatycznych. W tym mechanizmie cytoplazma przemieszcza si&#281; w mniej skurczonym i bardziej p&#322;ynnym regionie znajduj&#261;cym si&#281; na czo&#322;owym brzegu kom&#243;rki, pod&#261;&#380;aj&#261;c &#347;cie&#380;k&#261; najmniejszego oporu. Proces ten wspierany jest przez mikrofilamenty zlokalizowane bezpo&#347;rednio pod b&#322;on&#261; cytoplazmatyczn&#261;. Gymnamoebia wykazuj&#261; znaczn&#261; zmienno&#347;&#263; rozmiar&#243;w &#8211; od zaledwie 15 mikrometr&#243;w &#347;rednicy do ponad 750 mikrometr&#243;w, co czyni najwi&#281;ksze z nich widocznymi go&#322;ym okiem.
W przeciwie&#324;stwie do wolno &#380;yj&#261;cych gymnamoeb, entamoeby to paso&#380;ytnicze protisty zasiedlaj&#261;ce g&#322;&#243;wnie jam&#281; ustn&#261; lub przew&#243;d pokarmowy kr&#281;gowc&#243;w i bezkr&#281;gowc&#243;w. Szczeg&#243;lnie istotna jest Entamoeba histolytica &#8211; gatunek beztlenowy, kt&#243;ry dzia&#322;a jako patogen cz&#322;owieka, wywo&#322;uj&#261;c czerwonk&#281; amebow&#261;. Schorzenie to prowadzi do owrzodzenia jelit i skutkuje krwaw&#261; biegunk&#261;. Transmisja tego paso&#380;yta zachodzi poprzez cysty, kt&#243;re rozprzestrzeniaj&#261; si&#281; wskutek fekalnego ska&#380;enia wody, &#380;ywno&#347;ci oraz naczy&#324; do jedzenia.
&#346;luzowce
&#346;luzowce by&#322;y historycznie klasyfikowane jako grzyby ze wzgl&#281;du na podobie&#324;stwa w cyklach &#380;yciowych oraz zdolno&#347;&#263; do tworzenia cia&#322; owocnikowych zawieraj&#261;cych zarodniki s&#322;u&#380;&#261;ce do rozprzestrzeniania si&#281;. Jednak w przeciwie&#324;stwie do grzyb&#243;w, &#347;luzowce wykazuj&#261; zdolno&#347;&#263; ruchu, co umo&#380;liwia im szybkie przemieszczanie si&#281; po sta&#322;ych powierzchniach. Organizmy te dziel&#261; si&#281; na dwie g&#322;&#243;wne grupy: &#347;luzowce plazmodialne (znane r&#243;wnie&#380; jako bezkom&#243;rkowe) oraz &#347;luzowce kom&#243;rkowe.
&#346;luzowce plazmodialne w fazie wegetatywnej wyst&#281;puj&#261; jako bezkszta&#322;tna masa protoplazmy zwana plazmodium (NIE to samo co patogenny rodzaj Plasmodium wywo&#322;uj&#261;cy malari&#281;), zawieraj&#261;ca liczne j&#261;dra diploidalne. Plazmodium &#347;luzowc&#243;w jest aktywnie ruchliwe i przemieszcza si&#281; na drodze ruchu ameboidalnego. W sprzyjaj&#261;cych warunkach tworzy ono sporangia &#8211; struktury zawieraj&#261;ce haploidalne zarodniki. Zarodniki te kie&#322;kuj&#261; i rozwijaj&#261; si&#281; w wiciowate kom&#243;rki rojowe, kt&#243;re nast&#281;pnie ulegaj&#261; fuzji w celu odtworzenia diploidalnego plazmodium. Do dobrze znanych i badanych rodzaj&#243;w nale&#380;y Physarum.
&#346;luzowce kom&#243;rkowe, z kolei, w stanie wegetatywnym pozostaj&#261; pojedynczymi kom&#243;rkami haploidalnymi i dopiero w okre&#347;lonych warunkach &#347;rodowiskowych tworz&#261; struktury diploidalne. Dobrze poznany gatunek Dictyostelium discoideum przechodzi bezp&#322;ciowy cykl &#380;yciowy, kt&#243;ry obejmuje agregacj&#281;, migracj&#281; oraz tworzenie cia&#322;a owocnikowego. W odpowiedzi na g&#322;&#243;d, pojedyncze kom&#243;rki Dictyostelium agreguj&#261;, tworz&#261;c pseudoplazmodium, w kt&#243;rym kom&#243;rki trac&#261; swoj&#261; indywidualno&#347;&#263; bez zachodzenia fuzji. Proces agregacji inicjowany jest przez wydzielanie cyklicznego adenozyno-3&#8242;,5&#8242;-monofosforanu (cAMP) &#8211; cz&#261;steczki sygna&#322;owej przyci&#261;gaj&#261;cej s&#261;siednie kom&#243;rki. Powsta&#322;a masa kom&#243;rkowa, zwana &#347;limakiem, wykazuje zdolno&#347;&#263; ruchu przed zatrzymaniem i pionowym ustawieniem, po czym rozpoczyna si&#281; formowanie cia&#322;a owocnikowego.
Cia&#322;o owocnikowe sk&#322;ada si&#281; z trzonu i g&#322;&#243;wki. Kom&#243;rki trzonu syntetyzuj&#261; celuloz&#281;, zapewniaj&#261;c&#261; wsparcie strukturalne, natomiast kom&#243;rki g&#322;&#243;wki r&#243;&#380;nicuj&#261; si&#281; w zarodniki. Po rozproszeniu zarodniki kie&#322;kuj&#261; i przekszta&#322;caj&#261; si&#281; w nowe kom&#243;rki ameboidalne, kontynuuj&#261;c w ten spos&#243;b cykl &#380;yciowy. Opr&#243;cz rozmna&#380;ania bezp&#322;ciowego, Dictyostelium mo&#380;e r&#243;wnie&#380; przechodzi&#263; rozmna&#380;anie p&#322;ciowe, podczas kt&#243;rego dwie ameby ulegaj&#261; fuzji, tworz&#261;c jedn&#261; olbrzymi&#261; ameb&#281;. Struktura ta rozwija grub&#261; celulozow&#261; &#347;cian&#281;, tworz&#261;c makrocyst&#281;, kt&#243;ra mo&#380;e pozostawa&#263; w stanie u&#347;pienia przez d&#322;ugi czas. Ostatecznie w makrocyscie zachodzi mejoza, w wyniku kt&#243;rej powstaj&#261; j&#261;dra haploidalne integruj&#261;ce si&#281; w nowe ameby, rozpoczynaj&#261;c na nowo cykl bezp&#322;ciowy.

Różnorodność protistów – IV

Amoebozoa stanowi&#261; zr&#243;&#380;nicowan&#261; grup&#281; protist&#243;w l&#261;dowych i wodnych, kt&#243;re wykorzystuj&#261; p&#322;atowate ...

Education

JoVE Core

Microbiology

Mikrobiologia

Unit

Jednostka

Microbial Diversity

Różnorodność mikrobiologiczna

KEY TERMS AND CONCEPTS

KLUCZOWE TERMINY I POJĘCIA

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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Planctomycetes Cell Structure and Life Cycle

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Verrucomicrobiota Cell Structure and Traits

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Spirochete Shape, Motion, and Disease

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Cyanobacteria and Oxygenic Photosynthesis

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Actinobacteria: Soil Bacteria and Cheese

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Heat-Loving Bacteria and Their Enzymes

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Mycoplasmas and Wall-Less Bacteria

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Magnetotactic and DNA-Resistant Bacteria

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Archaea Cell Structure and Metabolism

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Zygomycota: Spores, Hyphae, and Roles

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Ascomycota: Sac Fungi and Their Spore Cycle

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Basidiomycota: Mushrooms, Spores, and Ecological Roles

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Red Algae Pigments, Shapes, and Uses

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Green Algae: Forms, Habitats, and Roles

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overview of protists

Protist Diversity, Movement, and Survival

Protists are diverse eukaryotic microorganisms with many ways to move, eat, and survive. They do not have the specialized tissues of plants and animals or the chitinous cell walls of fungi. Their early split within Eukarya led to major structural, functional, and ecological diversity. Scientists group protists into supergroups based on genetic analysis and shared structures. These groups include Archaeplastida, Excavata, Amoebozoa, Rhizaria, Alveolata, and Stramenopiles. This classification...

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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