BGY3100 Biology of Microorganism (Protists) Lecture Notes (Part 2) 2024/2025 PDF

BGY3100 BIOLOGY OF MICROORGANISM Semester 1 2024/2025 (PROTISTS) PART 2 Speaker DR. EDWARD ENTALAI BESI Department of Biology, Faculty of Science, UPM, Malaysia Member of IUCN Spe...

BGY3100 BIOLOGY OF MICROORGANISM Semester 1 2024/2025 (PROTISTS) PART 2 Speaker DR. EDWARD ENTALAI BESI Department of Biology, Faculty of Science, UPM, Malaysia Member of IUCN Species Survival Commission (SSC)  Content  General characteristics of protists  Importance of protists in the ecosystem  Diseases and interaction with host Topic Learning Outcomes 1) Lists of general characteristics used to describe protists 2) Discuss the Importance of protists in the ecosystem 3) Explain the diseases and interaction with host Plant-like protists (autotrophs)  Euglena – single-celled, flagellate The class Euglenoidea is a widely studied member (54 genera and at least 800 species) Found in freshwater and salt water Euglena gracilis has been used as a model organism Sufficient sunlight - feed phototrophy, like plants Chloroplast with three membranes Chloroplast pigments: chlorophyll a and chlorophyll b (like green algae) Chloroplast contains pyrenoid - starch energy storage - enabling Euglena to survive in light deprivation Pyrenoid is also used as an identifying feature of the genus (like Lepocinclis and Phacus) Can also take nourishment heterotrophically, like animals - takes in nutrients by osmotrophy - can survive without light - diet of organic matter (e.g. beef extract, Euglena. Cells range from about 35–75 μm in length. peptone, acetate, ethanol (Image courtesy of Biophoto Associates/Science Source and The McGraw-Hill Companies, Inc.) or carbohydrates)  Euglena – single-celled, flagellate Possess a red eyespot or stigma (an organelle composed of carotenoid pigment granules) - filter the sunlight that falls on a light-detecting structure at the base of the flagellum (paraflagellar body), allowing only certain wavelengths of light to reach it Permitting Euglena to move toward certain light (phototaxis) Two flagella rooted in basal bodies - one flagellum is very short, and does not protrude from the cell, while the other is long enough to be seen with light microscopy - used to swim Surface of the flagellum is coated with about 30,000 Euglena. Cells range from about 35–75 μm in length. (Image courtesy of Biophoto Associates/Science extremely fine filaments Source and The McGraw-Hill Companies, Inc.) called mastigonemes  Some species, Euglena mutabilis, both flagella are "non-emergent“ - entirely confined to the interior of the cell's reservoir - cannot be seen in the light microscope Lacks cell wall - has a pellicle made up of a protein layer supported by a substructure of microtubules - arranged in strips spiraling around the cell Euglena mutabilis, from a Sphagnum pool on Loughrigg Fell, close to Lily Tarn, May 2015 (Source: https://microscopesandmonsters.wordpress.com/)  Pellicle strips sliding over one another - gives Euglena its exceptional flexibility and contractility Some are free-living organisms - others live in or on other Euglena (showing pellicle texture) organisms, including humans (symbiotic/parasite) In low moisture conditions/food is ❑ scarce - forms a protective wall around itself and lies dormant as a resting cyst until environmental conditions improve (Image courtesy Charles Krebs 2007)  The importance/significance of Euglena ❑ Carry out nearly 50 percent of photosynthesis ❑ Decomposers and help in recycling nutrients ❑ Control bacterial populations ❑ The lipid content of Euglena (mainly wax esters) is a promising feedstock for production of biodiesel and jet fuel ❑ Powdered Euglena contains minerals, vitamins and docosahexaenoic acid Euglena Powder. Packed with essential nutrients, it is (an omega-3 acid) - as a renowned for its health benefits. These include anti- food ingredient oxidation, anti-virus properties, free radical scavenging, and anti-cancer and anti-bacterial activity. ▪ Diatoms – unicellular - solitary cells or in colonies ▪ A major group of microalgae - a type of plankton called phytoplankton ▪ Found in the oceans, waterways, and soils - grow attached to benthic substrates, floating debris, and macrophytes ▪ Size from 2 to 200 μm with a few larger species ▪ Two distinct shapes: ✓ centric diatoms (radially symmetric) - a few ✓ pennate diatoms (broadly bilaterally symmetric) - most ▪ Shape of ribbons, fans, zigzags, or stars Features of a phytoplankton cell (Source: http://oceandatacenter.ucsc.edu/PhytoGallery/dinos%20vs%20diatoms.html) ▪ Diatoms – unicellular - solitary cells or in colonies Frustule (cell wall) is intricate hard but porous made of silica (hydrated silicon dioxide) Frustule is highly patterned with a variety of pores, ribs, minute spines, marginal ridges and elevations – (Image courtesy of mrleehamber119 species id and The McGraw-Hill Companies, Inc.) Has structural coloration due to photonic nanostructure, prompting them to be described as "jewels of the sea“ and "living opals“ Reproduce - asexual & sexual reproduction Gametic Life Cycle as Illustrated by Diatoms ❑ (a) Diatom asexual reproduction (repeated mitotic divisions). The repeated mitotic divisions eventually causes the mean cell size to decline in a diatom population. (b) Small cell size triggers sexual reproduction, which regenerates maximal cell size.  Movement - mainly passive (as a result of both water currents and wind-induced water turbulence) - lack flagella - dense cell walls cause them to readily sink o But male gametes of centric diatoms have flagella - permitting active movement for seeking female gametes o Have the usual heterokont structure, including the hairs (mastigonemes) Photosynthetic diatoms o Yellowish-brown chloroplast with four membranes – chlorophyll-like red algae o Chloroplast contains chlorophylls a and c o Contain pigments such as beta-carotene (orange), fucoxanthin (brown- green), diatoxanthin (yellow- green), and diadinoxanthin (yellow-green) (Source: https://cronodon.com/NatureTech/diatoms.html)  Palaeontology Analyzing past marine Modern oceanic environments Monitor past and silicon cycle: they present environmental conditions) Industrial Diatomaceous are the source of earth (diatomite) is a collection of diatom shells the vast majority of found in the earth's crust - used for a variety of purposes including for water filtration, biological as a mild abrasive, in cat litter, and as a dynamite stabilizer, biofuel producing solar panels production Human uses Forensic Nanotechnology May be A material for good evidence of nanotechnology drowning (ante- mortem/post- - used for optical mortem drowning) systems, semiconductor as the cause of nanolithography and death even ‘vehicles’ for drug delivery Monitoring water quality ▪ Dinoflagellates – single-celled Usually considered algae - one of the largest groups of marine eukaryotes – but substantially smaller than diatoms Mostly marine plankton, but are common in freshwater and brackish habitats – populations are distributed depending on sea surface temperature, salinity, or depth Many are known to be photosynthetic, but largely are mixotrophic ▪ Dinoflagellates – single-celled Chloroplast with three membranes Contain chlorophyll, similar to red algae contain chlorophylls a and c2, beta-carotene, and a group of xanthophylls Karenia brevis, Karenia mikimotoi and Karlodinium micrum - acquired other pigments through endosymbiosis, including fucoxanthin Karenia mikimotoi. A = Ventral view with apical groove (=arrow); B = Dorsal view, chloroplasts with pyrenoids; C = Ventral view, ellipsoidal nucleus (DIC). (Source: http://nordicmicroalgae.org/. Photo by Mats Kuylenstierna) ▪ Dinoflagellates – Alveolata, single-celled Desmokonts - have distinct flagellar arrangements, particularly characterized by an unequal flagellar arrangement and length. Dinokonts - have a more typical and distinctive flagellar arrangement with a longitudinal flagellum and a transverse flagellum - often associated with the characteristic whirling or spinning motion Desmokonts Dinokonts (Source: https://allen.in/neet/biology/dinoflagellates)  Dinokonts - Alexandrium catenella. Certain species produce saxitoxins. (Image by WHOI, D. Anderson)  (Image by Mats Kuylenstierna) Desmokonts - Prorocentrum micans known for their role in toxic algal blooms (e.g., causing red tides).  Some have light-sensitive organelle (ocelloid or eyespot or stigma) – e.g. Winowia and Erythropsidinium The dinoflagellate Winowia sp. showing the ocelloid with its lens Images by Franz Neidl Light micrograph of a single Erythropsidinium sp. isolates. Double arrowhead = ocelloid (light-sensitive structure analogous to metazoan eyes); arrow = piston Source: Hoppenrath et al. (2009). ▪ Some have a larger nucleus containing a prominent nucleolus ▪ Nucleus (dinokaryon) – in most (but not all) Akashiwo sanguinea (previously Gymnodinium sanguineum), a simple nonthecate dinoflagellate. [Source: Dipper, F.A. (2016)]  ▪ Haplontic life cycle Haploid cells divide mitotically to form independent gametophytes Asexual reproduction through mitosis) ▪ Rapid accumulation of certain dinoflagellates can result in a visible coloration of the water Red tide (a harmful algal bloom) ▪ Exhibit bioluminescence - primarily emitting blue-green light Some parts of the Indian Ocean light up at night - blue-green light ▪ Green algae – unicellular, colonial and multicellular ± 22,000 species - many live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds Chlorophyta (Green Algae). (a) Volvox, which demonstrates colonial growth. (b) Spirogyra; each filament contains ribbonlike, spiral chloroplasts. (c) Acetabularia, the mermaid’s wine goblet. (Source: (a) Micro photo/iStock/Getty Images; (b) Nuridsany et Perennou/Science Source; (c) De Agostini Picture Library/Science Source) Serve as model experimental organisms to understand mechanisms of the ionic and water permeability of membranes, osmoregulation, turgor regulation, salt tolerance and more… ▪ Green algae – unicellular, colonial and multicellular ▪ Chloroplast with two membranes in stacked thylakoids Chlorophyll a and b - giving them a bright green color Accessory pigments beta carotene (orange) and xanthophylls (yellow) in stacked thylakoids ▪ Cell wall usually contains cellulose ▪ Mitochondria with flat cristae (inner membrane) ▪ Paired flagella - to move the cell (Source: https://www.carverstl.org/connections-2021/2021/4/11/the- praiseworthy-green-algae. Image by David Peters) ▪ Green algae – unicellular, colonial and multicellular Reproduction varies from fusion of identical cells (isogamy) to fertilization of a large non-motile cell by a smaller motile one (oogamy) Haplobiontic and diplobiontic life cycles o Haplobiontic species - only the haploid generation - the diploid zygote, undergoes meiosis, giving rise to haploid cells which will become new gametophytes o Diplobiontic species, e.g. Ulva - reproductive cycle: alternation of generations in which two multicellular forms (haploid and diploid) o Sporophyte produces haploid spores by meiosis that germinate to produce a multicellular gametophyte o Zygote divides repeatedly by mitosis and grows into a multicellular diploid sporophyte ▪ Green algae – unicellular, colonial and multicellular Diplobiontic species - Chlamydomonas reinhardtii The Structure and Life Cycle of Chlamydomonas reinhardtii. During asexual reproduction, all structures are haploid; during reproduction, only the zygote is diploid. (Image courtesy of The McGraw-Hill Companies, Inc.) ▪ Brown algae - a large group of multicellular algae 1,500 to 2,000 species Most live in marine environments - play an important role both as food and as a potential habitat Form - from small crusts or cushions to leafy free-floating mats formed by species of Sargassum Contain pigment fucoxanthin - olive green to various shades of brown Chloroplasts surrounded by 4 membranes Largest and fastest growing of seaweeds The simplest are filamentous (Source: Dreamstime.com. Image courtesy of Mayamy249)  Cell wall - consists of several components with alginates and suphated fucan being its main ingredients, up to 40 % each o Two layers: ❑ The inner layer bears the strength, and consists of cellulose ❑ The outer wall layer is mainly algin Free floating forms of brown algae often do not undergo sexual reproduction until they attach themselves to substrate Between generations, the algae go through separate sporophyte (diploid) and gametophyte (haploid; consists of male and female) phases (Source: https://brownalgaearecooltoo.weebly.com/reproduction.html)  Body is termed a thallus - lacks the complex xylem and phloem of vascular plants Holdfast is a rootlike structure present at the base of the alga Stipe is a stalk or stemlike structure present in an alga ▪ May grow as a short structure near the base of the alga (as in Laminaria) ▪ May develop into a large, complex structure running throughout the algal body (as in Sargassum or Macrocystis) ▪ May be relatively flexible and elastic in species like Macrocystis pyrifera ▪ May be more rigid in species like Postelsia palmaeformis ▪ Brown algae The use: o Edible seaweeds o Fix carbon dioxide through photosynthesis o Sargachromanol G, an extract of Sargassum siliquastrum, has anti-inflammatory effects o Alginic acid (alginate) in their cell walls - extracted commercially ❑ Used as an industrial thickening agent in food ❑ Used in lithium-ion batteries - a stable component of a battery anode ❑ Used in aquaculture - enhances the immune system of rainbow trout  ❑ Red algae/Rhodophyta - multicellular o Over 7,000 species o Abundant in marine habitats but are relatively rare in freshwaters, two coastal cave dwelling species o Most are multicellular, macroscopic, marine, and reproduce sexually o The life history is typically an alternation of generations that may have three generations rather than two o Without flagella and centrioles o Store sugars as floridean starch ❑ Red algae (Rhodophyta, Rhodophyceae) - multicellular o Chloroplast with two membranes - chlorophyll like the majority of cyanobacteria Chlorophyll a, α- and β-carotene, lutein and zeazanthin Contain unstacked (stroma) thylakoids o Double cell walls The outer layers contain the polysaccharides agarose and agaropectin The outer layer can be extracted from the cell walls by boiling as agar The internal walls are mostly cellulose o Lack external endoplasmic reticulum o No flagella and centrioles during their entire life cycle ❑ Display alternation of generations – gametophyte generation and sporophyte generations Gametophyte Sporophyte generation generation ❑ Reproduce sexually as well as asexually Asexual reproduction can occur through the production of spores and by vegetative means Vegetative means - fragmentation, cell division (Source: https://www.britannica.com/science/green-algae) Sexual reproduction - lack motile sperm, rely on water currents to transport their gametes to the female organs The spermatia (male) are capable of "gliding" to a carpogonium's trichogyne (female) - fertilization ▪ The use: ▪ Source of antioxidants including polyphenols, and phycobiliproteins and contain proteins, minerals, trace elements, vitamins and essential fatty acids ▪ Eaten raw, in salads, soups, meal and condiments ▪ Thickening agent, textiles, food, anticoagulants, water-binding agent Fungi-like protists (saprophytic) ▪ Slime molds - "fungus-like" (saprophytic) protists > 900 species Cellular (when swarm; remain as distinct cell) Acellular (when swarm; fuse together to form a single cell with many nuclei) forms Can live freely as single cells BUT can aggregate together to form multicellular reproductive structures Smaller than a few centimeters or several square meters - masses up to 20 kilograms Commonly found on rotting logs and compost as decomposer Feed on bacteria, yeasts and fungi Used as model organisms in molecular biology and genetics - may be the key to how multicellular organisms evolved Cell walls made of cellulose  ❑ Life cycles - asexual and sexual reproduction o Reproduce with spores as fungi o Motile during some stages of their life cycle o Begin life as amoeba-like cells (haploid) and feed on bacteria o Fertilization results in a diploid zygotes that then grow into plasmodia o Plasmoda grow into an interconnected network of protoplasmic strands o When the food supply reduce, Plasmodial Slime Mold Life Cycle plasmodium transform into rigid o Sporangia will release spores which hatch fruiting bodies into amoebae to begin the life cycle again  Hemitrichia serpula forms fruiting body called a plasmodiocarp. Photo by Roman Providukhin, CC-BY-NC. Fruiting bodies of Diachea leucopodia have a distinct stalk and sporangium. Photo by Sypster, CC BY-NC. Further reading: https://bio.libretexts.org/Bookshelves/Botany/A_Photographic_Atla Plasmodium of Physarum polycephalum exploring some s_for_Botany_(Morrow)/04%3A_Protists/4.01%3A_Slime_Molds decaying wood. Photo by Daniel Folds, CC BY-NC. ▪ Water molds/Oomycetes - "fungus-like" (saprophytic) protists ▪ Cellular and acellular forms ▪ Commonly found in moist soil and surface water ▪ Cell walls made of cellulose ▪ Filamentous and branching ▪ Heterotrophic – saprophytic ▪ Many are pathogens that destroy crops e.g. Phytophthora infestans ▪ Complicated life cycles - motile during some stages of their life cycle - both asexual and sexual reproduction ▪ Sexual reproduction of an oospore is the result of contact between hyphae of male antheridia and female oogonia - these spores can overwinter and are known as resting spores ▪ Asexual reproduction involves the formation of chlamydospores and sporangia, producing motile zoospores QUIZZES Sargasso sea is named after an algae Sargassum which is a: a. Green algae b. Brown algae c. Red algae d. Blue green algae Agar agar is obtained from: a. Green algae b. Red algae c. Brown algae d. Blue green algae In Chlamydomonas, the meiosis occurs in: a. Gamete b. Zygote c. Sporogonium d. Zoospore Pyrenoids are the centre of formation of: a. Enzymes b. Proteins c. Fats d. Starch Blue-green algae are included in: a. Prokaryotes b. Protista c. Fungi d. Bryophytes The __________ is the vegetative body of algae: a. mycelium b. plasmodium c. pseudoplasmodium d. thallus Sexual reproduction of algae is carried by: a. Isogamy b. Anisogamy c. Oogamy d. All the above What are two ways that protists reproduce sexually? a. Budding and binary fission b. Conjugation and alternating generations c. Binary fission and multiple fission d. Budding and multiple fission  Name organism labelled (a)(b)(c): Paramecium Amoeba Euglena Name 3 main groups in Kingdom Protista? ▪ Protozoa – heterotrophic consumers ▪ Algae – autotrophic produces (slime) ▪ Molds – heterotrophic decomposers Why are red and green algae not plants? Although, they possess chlorophyll that helps in photosynthesis and considered as plant-like protists, they are simple organisms that lack complex plant organs such as roots, stems, and leaves What are the characteristics of typical protists? Diverse Live in almost any environment that contains liquid water Need a moist environment to survive Primarily microscopic and unicellular OR unicellular-colonial and which form no tissues Some are macroscopic and relatively simple multicellular – BUT lack highly differentiated tissues Cells range in size from less than a micrometer to thousands of square meters  Complete the diagram and questions below: Haploid reproductive cell Type of cell division: spores _________________________ Type of cell division: meiosis ___________________ 1n mitosis ___________________ Diploid haploid multicellular organism Alternation of multicellular organism sporophyte 2n Generation 1n gametophyte of Protists Type of cell division: Type of cell division: 2n 1n mitosis ___________________ mitosis ___________________ zygote Fertilization gametes __________________________ _______________ diploid cell haploid reproductive cell  REFERENCES 1) Willey, J., Sandman, K. & Wood, D. (2023). Prescott’s Microbiology (12th ed.). McGraw-Hill Education. 2) Hoppenrath, M., Bachvaroff, T.R., Handy, S.M. et al. Molecular phylogeny of ocelloid-bearing dinoflagellates (Warnowiaceae) as inferred from SSU and LSU rDNA sequences. BMC Evol Biol 9, 116 (2009). DOI: 10.1186/1471- 2148-9-116