ProtozoansProtozoans

Protozoan Groups

Ciliates

Sarcodines

Apicomplexans

Flagellates

Colonial Flagellates

Volvox colony

Protozoan Taxonomy

• Morphological taxonomy– Phylum sarcomastigophora

• Subphylum mastigophora– Flagellates

» Phytoflagellates

» Zooflagellates

• Subphylum sarcodinia– Amoebas– Foramiferans– Radiolarians

– Phylum Ciliophora• Ciliates

– Phylum Apicomplexa• parasitic protozoa• Spore forming protozoans

• Molecular taxonomy– Indicate that

morphological relationships are tenuous

– Divergence between phyla of protozoa as great as between kingdoms (i.e. animalia, fungi and plantae)

– Revisions are continuously occurring

Basis of Taxonomy

• Morphological traits– Flagella– Cilia– Pseudopodia– Shells (tests)

• Reproductive modes– Sexual– Asexual– Spore formation

• Distinct reproductive cell forms

– Cyst formation

• Characteristic organelles– Apical complex– Kinetoplast– Presence/Absence of

mitochondria

• Trophism– Heterotrophic– Autotrophic

Flagella & Cilia

Fig. 5.5, pg 89

Pseudopodial Movement

Amoeba

• Amoeboid movement– Pseudopodial extension

• Phagocytosis– Engulfment of large particles

Contractile Vacuoles

• Osmotic regulation

– Remove excess metabolic H2O, and HCO3

– Remove H2O that enters by osmosis

– Refer to fig 5.7

Feeding

Fig 5.6, page 90

Examples of Binary Fission – Asexual Reproduction

Fig 5.8, page 91

Radiolarian Undergoing Binary Fission

Sexual Reproduction

• Conjugation– Meiotic nuclear division

– Transfer of portion of genome between partners

• Sporogomy– Formation of sporozoites

– Formation of gametocytes from sporozoites

– Fusion of gametocytes to form new generation of sporozoite

– Gametocytes and sporozoites are present in separate hosts

Cell Specialization in the Colonial Volvacae

Fig 5.11, page 93

Reproduction in Ciliates – Sexual and AsexualConjugation Fission

Fig 5.18, pg 98 Fig 5.9, page 91

Conjugation

Conjugation

Conjugation

Cyst Formation

Fig 5.1, page 85

Taxonomy of Kingdom Protozoan

Phylogenic Distinctions

Kingdom ProtistaProtozoans

Kingdom Animalia

• Derived from an early ancestral eukaryote• Retortamonada

– Lack both mitochondria and Golgi bodies.– Include Giardia lambia – intestinal parasite, produces

violent, but not fatal symptoms.• Produces cyst that are passed by the host, host is

infected by contaminated drinking water.• Axostylata

– Have a stiffening rod, the axostyle, composed of microtubules that extend along the longitudinal axis.

– Members of the Order Trichomonadida contain hydrogenosomes, that function in the same method as mitochondria .

• Tichomonas vaginalis – sexually transmitted parasitic, causes urinary tract infections.

Phyla Retortamonada and Axostylata

Phyla Retortamonada and Axostylata

Giardia lambiaTichomonas vaginalis

Phylum Chlorophyta

• Plant-like Protozoan's• Autotrophic, and contain

one or more chloroplast (organelles that contain the pigment chlorophyll used for photosynthesis)

• Single celled algae such as Chlamydomonas

• Colonial organisms such as Gonium and Volvox

Phylum Euglenozoa

• A phytoflagellate– Autotrophic– Opportunistic

heterotroph– Contain a light sensitive

organelle known as the Stigma.

– Kinetoplast, large disk of DNA contained in the mitochondria

– Major cause of parasitic infections throughout the world.

• Genus Trypanosoma • Genus Leishmania

Trypanosomiasis

• African sleeping sickness – Eastern hemisphere– Trypanosoma brucei

– Vector – Tsetse Fly - Glossina spp

Immages from links at http://www.biosci.ohio-state.edu/~parasite

Trypanosomiasis

• Chaga’s disease – Western hemisphere– Trypanosoma cruzi

– Vector – assassin bug – Rhodnius spp, Panstrongylus spp and Triatoma spp

Life Cycle of Trypanosoma

Trypanosoma

• Early diagnosis – treatment very successful– Suramine or Pentamidine depending on subspecies of

trypanosome

• Late phase treatments– Low success rate

– Serious side effects (including lethality) of drugs

– Melarsoprol – often causes sever allergic reaction which causes neural damage

– Eflornithine – only effective against gambiense subspecies and is no longer produced

– These drugs contain arsenic

Leishmania

• Leishmania donovani “referred to as Dum-Dum Fever or kala-azar”

• Spread by sand flies; phlebotomus spp.

• Common in Africa and India, and rare in the Mediterranean and Latin America.

• Causes fever, malaise, progressive wasting, anemia, lesions, enlargement of the liver and spleen, facial scarring and death.

Leishmaniasis

• Treatments – Antimony containing compounds– meglumine antimonate – sodium stibogluconate

Life Cycle of Leishmania

Phylum Apicomplexa• Parasitic• Reproduce both sexually and asexually• Set of organelles called the Apical Complex

– Present in the sporozoite for invading the host cells• Cilia, flagella or pseudopodia – but these are lacking in most

species.• Form spores• Two main Classes

– Gregarinea – intestinal parasites, normally complete life cycle within one host.

– Coccidea – vertebrate parasites include;• Cryptosporidium• Toxoplasma• Plasmodium – malaria

– 500 million cases annually– 1-2 million deaths annually

Apical Organelles of the Apicomplexans

Fig 5.13, page 95

Life Cycle of Plasmodium falciparum

Fig 5.14, page 96

Phylum Ciliophora

• Large, diverse phyla• Typically found in marine or freshwater environments• Range in size from 10um to 3mm long and all have cilia during their

life cycle• Multinucleate

– Macronucleus – controls metabolism, synthesis of organic molecules and development of the organism

– Micronucleus – function in sexual reproduction and give rise to the macronucleus after sexual reproduction.

• Holozoic, feeds on organisms via a cytostome• Defensive and predatory adaptations

– Trichocysts – defensive– Toxocysts – toxic to paralyze prey

• Pellicle – protective coating that can range from a single cell in thickness to a thick armored covering

Phylum Ciliophora– Parmecium sp

Fig 5.17, page 98

Some other Ciliates

Fig 5.15, pg 97

Phylum Dinoflagellata

• Ecologically important– Primary producers in marine environments –

photosynthetic varieties• Commonly have two flagella• Either photosynthetic or herbivores• Some species are bioluminescent• Zooxanthellae gen. live in mutualistic relationships with

other protozoans, sea anemones, coral and clams (ex. with stony coral which produces coral reefs)

• Some species are responsible for red tides– Release toxins that paralyze or kill fish – Protozoans then feed on fish – Can affect humans be affecting the respiratory and

nervous systems, as well as causing sores to develop.

Dinoflagellates

Amebas

• Fresh and salt water environments, and soil moisture• Planktonic or substratum• Holozoic• Some parasitic species

– Entamoeba histolytica

– Brain infections

• Protective tests (or shells) form to protect the organisms– Formaninferans – include sand into the test

• Radiolarians – Marine, planktonic with siliceous skeletons

– Among the oldest known species of protozoans

– Common throughout the geologic or fossil record

Examples of Amebas