BGY3100 Biology of Microorganism Protists Lecture Notes 2023/2024 PDF

BGY3100 BIOLOGY OF MICROORGANISM Semester 1 2023/2024 (PROTISTS) PART 1 Speaker DR. EDWARD ENTALAI BESI Department of Biology, Faculty of Science, UPM, Malaysia Member of IUCN Sp...

BGY3100 BIOLOGY OF MICROORGANISM Semester 1 2023/2024 (PROTISTS) PART 1 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  PROTISTS o A diverse collection of organisms – plants, fungi and animals like - 60,000; and 200,000 protist species, and many have yet to be identified o Live in almost any environment that contains liquid water - need a moist environment to survive Clockwise from top left: red algae (Chondrus crispus); brown algae (Giant Kelp); ciliate o Primarily microscopic and unicellular OR (Frontonia); golden algae (Dinobryon); Foraminifera (Radiolaria); parasitic flagellate unicellular-colonial and which form (Giardia muris); pathogenic amoeba (Acanthamoeba); amoebozoan slime mold no tissues - all of life’s various functions (Fuligo septica) must be performed within a single cell (Source: https://en.wikipedia.org/wiki/Protist)  MULTICELLULAR PROTISTS Slime molds may form multicellular structures (Image courtesy of Kate Latham) Brown Algae - Seaweed o Some are macroscopic and relatively simple multicellular o Their morphology and physiology are the same as the cells of multicellular plants and animals – BUT lack highly differentiated tissues o Cells range in size from less than a micrometer to thousands of square meters (Brown algae - giant kelp)  PROTISTS MORPHOLOGY o Protist cell membrane is called the plasmalemma and is identical to that of multicellular organisms o In some protists, the cytoplasm is divided into an outer gelatinous region called the ectoplasm and an inner fluid region, the Protist Structure. A transmission electron micrograph of the photosynthetic protist endoplasm Chlamydomonas reinhardtii. (Image courtesy of Biophoto Associates/Science Source and The McGraw-Hill Companies, Inc.)  PROTISTS MORPHOLOGY o Most aerobic chemoorganotrophic protists have mitochondria, whereas photosynthetic forms have chloroplasts o Mitochondria and chloroplasts surrounded by their own plasma membranes and contain their own DNA - it is similar to the circular DNA Protist Structure. A transmission electron of bacteria micrograph of the photosynthetic protist Chlamydomonas reinhardtii. (Image courtesy of Biophoto Associates/Science Source and The McGraw-Hill Companies, Inc.)  PROTISTS MORPHOLOGY o Pyrenoid is a dense proteinaceous micro-compartment associated with the synthesis and storage of starch - found within chloroplasts o One or more vacuoles are usually present in the cytoplasm of protozoa Contractile vacuoles - osmoregulatory organelles - maintain osmotic balance by continuous water expulsion Secretory vacuoles (vesicles) Phagocytic vacuoles are conspicuous in Protist Structure. A transmission electron protists that ingest food by phagocytosis micrograph of the photosynthetic protist (holozoic protists) - sites of food digestion Chlamydomonas reinhardtii. (Image courtesy Biophoto Associates/Science Source and The McGraw-Hill Companies, Inc.) o Nucleus, which houses their genetic material - surrounded by a nuclear envelope o Locomotion (in non-sessile forms) is by pseudopodia, or by flagella or cilia which show the typical 9+2 microtubular arrangement o Specialized cellular machinery called organelles that execute defined functions within the cell ❑ Contain plastids Photosynthetic protists (e.g. various types of algae) Serve as the site of photosynthesis Some are similar to those of plants Some differ in the color, the repertoire of photosynthetic pigments and even the number of membranes that enclose the organelle (e.g. diatoms and dinoflagellates, which constitute phytoplankton in the ocean) ❑ Most have mitochondria Organelle which generates energy for cells to use But some live in anoxic conditions, or environments lacking in oxygen, use an organelle called the hydrogenosome (which is a greatly modified version of mitochondria) (e.g. the sexually transmitted parasite Trichomonas vaginalis)  Chlorophyll (green algae) PROTISTS Photosynthetic autotroph Fucoxanthin (brown algae) NUTRITION Perform photosynthesis, non- motile protists, resemble plants Phycoerythrin (red algae) Using pigments to harness solar energy and convert it into simple carbohydrates - most Phagotrophs algae (Use their cell body to surround and swallow up food, often other cells) Osmotrophs (Absorb nutrients from the surrounding environment) Nutrition Heterotroph (Seek outside sources of food in Saprotrophs the form of organic material) (Feeds on nonliving organic matter) Major consumers of bacteria Decompose organic material - resemble fungi Parasitism Paramecium bursaria and Paulinella lost chloroplast - captured a green alga (Zoochlorella) and a cyanobacterium Mixotroph (Do not have/lost chloroplasts/mitochondria - Mixotricha paradoxa - lost its mitochondria – uses entered into endosymbiontic endosymbiontic bacteria as mitochondria relationship with other and ectosymbiontic hair-like bacteria bacteria/algae) (Treponema spirochetes) for locomotion  PROTISTS REPRODUCTION Binary fission (A parent cell splits into two identical cells ) Asexual (Generally under favorable environmental conditions) Multiple fission (The parent cell gives rise Reproduction to multiple identical cells) Sexual (Generally under stressful Gametes/spores conditions: (Undergo meiosis) starvation/heat shock/oxidative stress  Plant-like & Animal-like protists Animal-like protists Plant-like protists (Protozoa) (Protophyta: Micro/Macro-algae)  A phylum or subset of the animal o Euglena kingdom o Diatoms  Most members of these groups live o Dinoflagellates by ingesting food, rather than o Green algae synthesizing their own food o Brown algae (heterotrophic and some are o Red algae parasitic) Fungi-like protists  Classified primarily by their means of locomotion: (Saprophytic) ❑ Amoebas ❑ Ciliates o Slime molds ❑ Foraminiferans ❑ Heliozoans & radiolarians o Water molds ❑ Flagellates ❑ Apicomplexans (sporozoans Animal-like protists (heterotrophs) ▪ Amoebas - single-celled animals 3 micrometers to 20 cm in diameter Characterized by the possession of pseudopodia/pseudopodium; ‘false feet’ - used for feeding and for locomotion in some Do not have cell walls Amoebae typically ingest their food by phagocytosis: extending pseudopods to encircle and engulf live prey/particles Some amoebae also feed by pinocytosis, imbibing dissolved nutrients through vesicles formed within the cell membrane Reproduce asexually, but do not show the typical stages of mitosis No meiosis, and do not form spores Some amoebae can infect other organisms pathogenically, causing disease: ❖ Entamoeba histolytica – cause dysentery ❖ Naegleria fowleri (the "brain-eating amoeba") ❖ Acanthamoeba - cause amoebic keratitis and encephalitis in humans ❖ Balamuthia mandrillaris - cause granulomatous amoebic meningoencephalitis Source: https://byjus.com Reproduce asexually - binary fission ❑ Divide longitudinally: begins with the mitosis of the cell nucleus, followed by the division of the cell ❑ Beginning at the front end of the cell, with the duplication of flagellar processes, gullet and stigma ❑ A cleavage forms in the anterior and a V-shaped bifurcation gradually moves toward the posterior, until the two halves are entirely separated ❑ Sexual conjugation are rare, and have not been substantiated ▪ Ciliates – Alveolata, single-celled animals ▪ A group of protozoans characterized by the presence of hair- like organelles called cilia ▪ Used in swimming, crawling, attachment, feeding and sensation ▪ Common - almost anywhere there is water – about 4,500 unique free-living species have been described, and potentially 27,000 - 40,000 species ▪ Size: 10 µm to 4.5 mm long ▪ Ectosymbiotic and endosymbiotic species, as well as some obligate and opportunistic parasites ▪ Reproduce asexually, by various kinds of fission ▪ Other types of fission in some ciliate groups Budding - the emergence of small ciliated offspring, or "swarmers", from the body of a mature parent Strobilation - multiple divisions along the cell body, producing a chain of new organisms Palintomy - multiple fissions, usually within a cyst ▪ Fission may occur spontaneously, as part of the vegetative cell cycle ▪ Alternatively, it may proceed as a result of self-fertilization (autogamy), or it may follow conjugation, a sexual phenomenon in which ciliates of compatible mating types exchange genetic material ▪ Most ciliates have one or more prominent contractile vacuoles to maintain osmotic pressure and ionic balance - in some genera, such as Paramecium, have a distinctive star shape, with each point being a collecting tube ▪ Food vacuoles - formed through phagocytosis ▪ Two different nuclei: ❑ A tiny, diploid micronucleus - the "generative nucleus“, which carries the germline of the cell - passes its genetic material to offspring, but does not express its genes ❑ A large, polyploid macronucleus - the "vegetative nucleus“, which takes care of general cell regulation, expressing the phenotype of the organism ▪ Paramecium o Shape - slipper-like o Free-swimming - abundant in water bodies – from stagnant ponds to the open ocean o Often used as a model organism to study sexual reproduction Paramecium caudatum (Source: micro_photo/iStock/Getty Images and The McGraw-Hill Companies, Inc.) ▪ Other ciliates Ciliophora. (a) Stentor, a large, vase-shaped, freshwater o Vorticella, Blepharisma, protozoan. (b) Two Stylonychia cells conjugating. (c) Structure of Paramecium spp. Stentor, Stylonychia (Source: (a) Eric Grave/Science Source; (b) ©Eric Grave/Science Source and The McGraw-Hill Companies, Inc.)  ▪ Sporozoans o Do not move on their own o Reproduce by forming spores o Usually parasitic o Sporozoans named Plasmodium causes Malaria Life cycle of Plasmodium falciparum, a parasitic protozoan that causes the most severe form of malaria in humans Plasmodium falciparum (Copyright © 2022 The Consortium of Glycobiology Editors, La Jolla, California; published by Cold Spring Harbor Laboratory Press; (Source: https://www.the-scientist.com/news- DOI:10.1101/glycobiology.4e.43) opinion/malaria-parasites-biological-clocks- coordinate-cell-destruction-67536) ▪ Foraminiferans - single-celled organisms o Over 50,000 species are recognized, both living (10,000) and fossil (40,000) o < 1 mm in size, the largest up to 20 cm o Marine relatives of the Amoeba - most live on or near the ocean bottom (benthic), while a smaller number float in the water column at various depths (planktonic), fewer are freshwater or brackish, and some very few (nonaquatic) soil species o Some smaller species reproduce only asexually by budding or multiple fission, larger forms frequently alternate between sexual and asexual phases White Cliffs of Dover. The limestone that forms these cliffs is composed almost entirely of fossil shells of protists, including Foraminifera. (Source: Image courtesy of elena1977/123RF and The McGraw-Hill Companies, Inc.) ▪ Radiolarians o Live in freshwater and marine - most of the marine species are planktonic o Diameter 0.1 - 0.2 mm o Secrete a radially symmetrical, spherical silicious skeleton shell o Have many needle-like pseudopods supported by bundles of microtubules, which aid in the radiolarian's buoyancy o Nucleus and most other organelles are in the endoplasm ▪ Radiolarians Radiolaria. (a) The radiolarian Acanthometra elastica demonstrates the internal skeleton. Endoplasm is within the intracapsular zone; the vacuolated extracapsular zone contains ectoplasm. (b) Radiolarian shells made of silica. (Source: Image courtesy of (b) Eye of Science/Science Source and The McGraw-Hill Companies, Inc.) o Often contain symbiotic algae, especially zooxanthellae, which provide most of the cell's energy o Morphology and physiology and the radiolarian diversity is currently known ▪ Flagellates - unicellular, eukaryotic organisms ▪ Possess flagella as adults - one or more ▪ Flagella are supported by microtubules in a characteristic arrangement, with nine fused pairs surrounding two central singlets - arise from a basal body ▪ Flagella are generally used for propulsion and direct food into a cytostome or mouth, where food is ingested ▪ A primitive group ▪ Many live commensally within the bodies of other organisms ▪ Heterotrophic, but may be either free-living, symbiotic or parasitic ▪ Major consumers in aquatic ecosystems - consuming bacteria and other protists ▪ Reproduction - sexual or asexual (binary fission)  ▪ Trypanosomes o Unicellular, parasitic and flagellated protozoans o Most are harmless organisms that live commensally within their natural hosts (Source: o Responsible for several human diseases https://medlineplus.gov/chagasdise ase.html) e.g. Trypanosoma lewisi - found in the blood of rats e.g. Trypanosoma gambiense - causes African sleeping sickness e.g. Trypanosoma cruzi - causes Chagas disease Chagas diseases (CD) or American trypanosomiasis is a silent yet life- threatening disease caused by a protozoan parasite named Trypanosoma cruzi (Source: https://www.boldsky.com/hea lth/disorders-cure/chagas- disease-causes-symptoms-risk- factors-treatment-and- prevention-132869.html) Trypanosoma lewisi (Source: Image courtesy of S.J. Upton) ▪ Termite Flagellates o Symbionts and parasites o Symbionts are essential for the survival of four of the five families of termites (e.g. Zootermopsis) and also for certain of the woodroaches o Flagellates digest the cellulose (in the cell walls) of the wood ingested by the termites, producing simple sugars - as a nutrient by the termite Trichonympha campanula Trichomitopsis termopsidis (Source: https://www.microscopy-uk.org.uk/mag/artmar03/rhtermite.html. Image courtesy of Richard L. Howey)  QUIZES Extra Marks for Class Participation TO BE CONTINUED