LECTURE 16EUKARYOTIC MICROBIALDIVERSITYFig. 12.1. Phylogeny of the Eucarya. Note thedistribution ofAlgae, Fungi and ProtozoaPhycology is the study of algae.Algae have chlorophyll a and use oxygenicphotosynthesis.ALGAEAlgae encompass many diverse groups:I. Green algae (Chlorophyta)II. Euglenoids (Euglenophyta)III. Golden-Brown + Diatoms (Stramenophiles)IV. Brown Algae (Phaeophyta)V. Red Algae (Rhodophyta)VI. Dinoflagellates (Pyrrophyta)Fig. 12.03Fig. 12.3. Notethat algae are notmonophyletic andare mixed in withthe “Protozoa”,there may havebeen severaljumps ofchloroplasts(cyanos) intoeucs….Classification based on many propertiesincluding:• chlorophyll molecules• flagella• reproductive structures• life histories• and othersI. Green Algae - Chlorophyta• have chlorophylls a and b• wide variety of forms• both sexual and asexual reproduction• closely related to land plantsComplex life cycle - sexual and asexualReproduction in ChlamydomonasII. Euglenoids (“photosynthetic protozoa”) • have chlorophyll a and bIII. Golden-Brown and Diatoms - Chrysophyta• diatoms have a 2-piece cell wall of silicacalled a frustuleDiversity of DiatomsVI.Dinoflagellates - PyrrhophytaFig. 12.6• alveolate algae – related to Ciliates (Protozoa)• some are bioluminescent• may cause red tides• some are symbionts in other marine organisms,especially corals – called zooxanthellae.PROTOZOAProtozoology is the study of protozoa.Not a monophyletic group – defined as amotile, eukaryotic unicellular cell.Fig. 12.07Fig. 12.7Protozoa arehighlighted inred….not amonophyleticgroup.Most are chemoheterotrophic.!ingest solid nutrients via phagocytosis!ingest soluble nutrients and smallsolids via pinocytosisAlso can take up small nutrients viadiffusionSee Figure 3.50……Some can encyst – form resting stage or cyst.1) help protist survive harsh periods2) allow for transfer of parasites between hostsFeeding or vegetative stage is called atrophozoite.Figure 12.9.Polymorphiclifecycle of aprotozoan,Naegleria.A. Ameboid stage inanimal tissue orsoil.B. Flagellated stage inwaterC. Cyst under dryingconditions…..Protists move via:1) pseudopodia (“false feet”) – cytoplasmicextensions2) flagella3) ciliaReproduction in protists is via:1) binary fission. Fig. 12.10. Variations on asexualreproduction in protozoa2) sexual reproduction - e.g. conjugationcommon among Paramecium. Manydisease causing protists have a sexualcycle…Many groups, we’ll concentrate on 3:I. SarcomastigophoraII. ApicomplexaIII. CiliatesI. Phylum Sarcomastigophora• flagella – subphylum Mastigophora• pseudopodia – subphylum SarcodinaMastigophora contains important groups:!GiardiaFig. 24.22. Giardia lamblia trophozoites in human intestines.!Trichomonas!trypanosomesTable 24.13Sarcodina – amoeboid protists! some have test = “shell” – providesprotection! Foraminiferans = marine amoebaewith ornate tests! Many are symbioticII. Apicomplexa• have a spore-forming stage in their life cycleat some point• generally lack locomotory organelles• all are parasites – includes some of mostimportant parasites:!Plasmodium –malaria!Toxoplasma!CryptosporidiumIII. Ciliates ( Phylum Ciliophora)-Major predators of bacteria in natural systems-Have 2 nuclei-Transverse binary fission (figure 12.10)Fig. 1.8……• move with ciliaFungus = eukaryotic, spore-bearing organismswith absorptive nutrition, no chlorophyll, andthat reproduce both sexually and asexually.Mycology = the science of studying fungiThe FungiFig. 12.11. Sequencebased phylogeny of thefungi…….Some general fungal terms:Mycelium = many hyphaeChitin = the glycoprotein that makesup a fungal cell wall (polymer of N-acetylglucosamine)Where else do you find chitin??Saprophytes = nutrients come from dead material(decomposers, chemoheterotrophs)Many fungi are mutualists with plants (mycorrhizae)and cyanobacteria or algae (lichens)…Mold = filamentous - long, branched filaments orhyphae. Together, hyphae form a mycelium.• coenocytic = continuous, no cross walls• septate = cross walls, with poresFigure 12.13. Yeast = unicellular fungusDimorphic fungi - alternate between yeast formand mold forms - the YM shiftCommon in pathogenic fungi, butwith opposite patterns in animal vs.plant hosts• Animals - yeast in host, mold inenvironment• Plants - mold in host, yeast inenvironmentFungal reproductionAsexual or sexualAsexual1. Divide into 2 equal cells- binary fission2. Budding Fig. 12.14. Asexual reproduction(budding) in a yeast….3. Form asexual spores (conidia)4. Fig. 12.15 . Asexual reproductionin a filamentous fungusFungal reproductionSexual- the union of compatible nuclei• haploid gametes• gamete-producing bodies• hyphaeMajor Fungal Divisions(based on DNA sequencing)I. ZygomycotaII. AscomycotaIII. BasidomycotaIV. ChytridomycotaI. Zygomycota• examples - bread mold, arbuscularmycorrhizae• hyphae are coenocytic (no or few cross walls)• sexual reproduction produces zygosporesFig. 12.16. B. Rhizopus stolonifer, black bread moldEndoMycorrhizaeEndomycorrhizae areZygomycetes and areassociated with over 70%of land plants - alsocalled arbuscularmycorrhizae<--- arbuscule inside plant root cellII. Ascomycota• example - food molds,mildews, cup fungi, morels,some ectomycorrhizae,many types of yeast….• characteristic reproductive structure -ascusVery common in soils many forms havenever been grown in the lab several largenew groups (at the class and sub-phylum level) offungi discovered (Science 301: 1359-1361 (2003)).• mycelia are septatePhylogenetic tree of all fungi(based on LSU rDNA)Green branches are groups found in tundrasoils.A = Ascomycetes Clade I = mostly summer Clade II = mostly winter and spring Clade III = spring and summerB = Basidiomycetes(Schadt et al. Science 301: 1359-1361)SummercladeWinter &snow-meltcladeIII. Basidiomycota• examples are shelf fungi and mushrooms• form a basidiumFig. 12.12. Some sexual fruiting bodies of Basidiomycestes.B. A shelf fungus growing on wood. C. Amanita muscariaan ectomycorrhizal fungus…….Figure 12.17. The structure of a typical BasidiomyceteNote button stage, underground hyphal network,gills and basidia on the gills….Sexual life cycle of a Basidiomycete…..EctoMycorrhizae"Ectomycorrhizae are mostly Basidiomycetes - many of the largemushrooms in forests are the sexual stage ofectomycorrhizal fungi….V. Chytridomycota - the chytrids• asexual