5BY543 Microbiology: General Structures and Properties of Eukaryotes PDF

5BY543 MICROBIOLOGY General Structures and Properties of Eukaryotes Dr. Isaac Thom Shawa [email protected] derby.ac.uk University Of Derby/5BY543/_Shawa Lecture outline R...

5BY543 MICROBIOLOGY General Structures and Properties of Eukaryotes Dr. Isaac Thom Shawa [email protected] derby.ac.uk University Of Derby/5BY543/_Shawa Lecture outline Recap Bacteriology lessons. Introduction to Eukaryotes. General Mycology Parasitism derby.ac.uk University Of Derby/5BY543/_Shawa What did you learn in bacteriology? History of microbiology. Why study microbiology? General structure and function of Bacteria (prokaryotes). Detection methods: Microscopy Gram staining Culture and sensitivity Molecular techniques Today’s lesson (Eukaryotes). derby.ac.uk University Of Derby/5BY543/_Shawa Recap – Case Study An Eighteen year old male Professional swimmer presents to his GP with a 2 day history of rhinitis (runny nose) and increased irritability, afebrile, and persistent pain, oedema, and tenderness of the soft tissues of the ear (right-ear tugging), with a purulent discharge. His Mum denies that he has had any nausea, vomiting, or diarrhoea; but reported an occasional facial nerve palsy. The Clinician suspects an Acute Otitis media. As a Biomedical Scientist, how would you handle this case by applying the laboratory diagnostic techniques? derby.ac.uk University Of Derby/5BY543/_Shawa Recap – Case Study Diagnosis – Acute Otitis Media Aetiological agents: P. aeruginosa Haemophilus influenzae Streptococcus pneumoniae Moraxella catarrhalis Streptococcus pyogenes Differential diagnosis: Otitis media with effusion (OME) Chronic otitis media External otitis (otitis externa) Herpes infection derby.ac.uk University Of Derby/5BY543/_Shawa  derby.ac.uk University Of Derby/5BY543/_Shawa  derby.ac.uk University Of Derby/5BY543/_Shawa  derby.ac.uk University Of Derby/5BY543/_Shawa Eukaryotic cell structure Similarities with a prokaryotic cell: Plasma membrane Cytoplasm Ribosomes Differences: A membrane-bound nucleus. Numerous membrane-bound organelles Complex rod-shaped chromosomes composed of DNA derby.ac.uk University Of Derby/5BY543/_Shawa The Nucleus and its structures Eukaryotic cells have a true nucleus, which means the cell’s DNA is surrounded by a membrane. The DNA directs the synthesis of ribosomes. The nuclear envelope is a double-membrane structure. Membranes of the envelope are phospholipid bilayers. Envelope is punctuated with pores that control the passage of ions, molecules, and RNA between the nucleoplasm and cytoplasm. The nucleoplasm contains the chromatin and the nucleolus. Chromosomes – are made up of DNA. In prokaryotes, DNA is organized into a single circular chromosome. In eukaryotes, chromosomes are linear structures. derby.ac.uk University Of Derby/5BY543/_Shawa Other Membrane-Bound Organelles Mitochondria have their own ribosomes and DNA. Often called the “energy factories” of a cell. responsible for making adenosine triphosphate (ATP). Endoplasmic reticulum modifies proteins and synthesizes lipids. Golgi apparatus is where the sorting, tagging, packaging, and distribution of lipids and proteins takes place. Peroxisomes are small, round organelles enclosed by single membranes. they carry out oxidation reactions that break down fatty acids and amino acids. they detoxify many poisons that may enter the body. Vesicles and vacuoles are membrane-bound sacs that function in storage and transport. derby.ac.uk University Of Derby/5BY543/_Shawa Mycology derby.ac.uk University Of Derby/5BY543/_Shawa Mycology Mycology – Scientific discipline dealing with fungi Myco – Fungus Mycoses – Diseases caused by fungi Medical mycology – Study of mycoses and their aetiologic agents. Mycologists – Scientists who study fungi. derby.ac.uk University Of Derby/5BY543/_Shawa Morphology Two morphological forms 1. Hypha: This is the basic element of filamentous fungi with a branched, tubular structure, 2–10 um in width. 2. Mycelium This is the web or mat-like structure of hyphae. Crosswalls may form compartments (± cells). Substrate mycelia (specialized for nutrition) penetrate into the nutrient substrate. Aerial mycelia (for asexual propagation) develop above the nutrient medium. derby.ac.uk University Of Derby/5BY543/_Shawa  derby.ac.uk University Of Derby/5BY543/_Shawa  derby.ac.uk University Of Derby/5BY543/_Shawa Mycelium A mycelium is a network of fungal threads or hyphae. Mycelia often grow underground but can also thrive in other places such as rotting tree trunks. A single spore can develop into a mycelium. The fruiting bodies of fungi, such as mushrooms, can sprout from a mycelium. derby.ac.uk University Of Derby/5BY543/_Shawa Characteristics of Fungi Eukaryotic, non-vascular, non-motile and heterotrophic organisms. Unicellular or filamentous. They reproduce by means of spores; have no embryonic stage. Fungi lack chlorophyll and hence cannot perform photosynthesis. Fungi store their food in the form of starch. Biosynthesis of chitin occurs in fungi. They have very small nuclei. The mode of reproduction is sexual or asexual. Fungi produce a chemical called pheromone which leads to sexual reproduction in fungi. Some fungi are parasitic and can infect the host. Examples include mushrooms, moulds and yeast. derby.ac.uk University Of Derby/5BY543/_Shawa  derby.ac.uk University Of Derby/5BY543/_Shawa Yeast Unicellular fungi. Dimorphism: some fungal species can Round to oval and 3 – develop either the yeast or the mycelium form 10µm in diameter. depending on the environmental conditions, a Yeast cells chained property called dimorphism. together and resembling Dimorphic pathogenic fungi true hyphae are called take the form of yeast cells in the parasitic stage and pseudohyphae. appear as mycelia in the saprophytic stage. derby.ac.uk University Of Derby/5BY543/_Shawa Reproduction Release spores (called zoospores ) that are produced either sexually or asexually. On sac like structure. Sporangium found on the tip of every hyphae. Dispersed widely by wind or water, spores germinate a moist place. derby.ac.uk University Of Derby/5BY543/_Shawa Reproduction derby.ac.uk University Of Derby/5BY543/_Shawa Classification of Fungi A. Geographic grouping Classification by geographic distribution. Certain fungal diseases are considered endemic to particular areas. Histoplasmosis Central Mississippi Valley Ohio Valley fever Coccidioidomycosis San Joaquin Valley fever derby.ac.uk University Of Derby/5BY543/_Shawa Classification of Fungi B. Epidemiologic grouping Concerned with how fungal disease is transmitted. Few are contagious - i.e. ringworm of the scalp. Some are inhaled, others must be directly introduced into deeper tissue – by a puncture from a thorn. Most mycoses are dependent on the susceptibility of the individual host. derby.ac.uk University Of Derby/5BY543/_Shawa Classification of Fungi C. Taxonomy grouping Scientific grouping according to morphologic and cultural characteristics; varies somewhat, depending on author. Fungi are usually classified in four divisions: Chytridiomycota (chytrids) Zygomycota (bread moulds) Ascomycota (yeasts and sac fungi) Basidiomycota (club fungi). derby.ac.uk University Of Derby/5BY543/_Shawa  derby.ac.uk University Of Derby/5BY543/_Shawa Classification of Fungi Based on Mode of nutrition On the basis of nutrition, kingdom fungi can be classified into 3 groups. 1. Saprophytic The fungi obtain their nutrition by feeding on dead organic substances e.g. Rhizopus, Penicillium and Aspergillus. 2. Parasitic The fungi obtain their nutrition by living on other living organisms e.g. Taphrina and Puccinia. 3. Symbiotic These fungi live by having an interdependent relationship with other species in which both are mutually benefited. E.g. Lichens and mycorrhiza. Lichens are the symbiotic association between algae and fungi. Here both algae and fungi are mutually benefited as fungi provide shelter for algae and in reverse algae synthesis carbohydrates for fungi. Mycorrhiza is the symbiotic association present between fungi and plants. Fungi improve nutrient uptake by plants, whereas, plants provides organic molecules like sugar to the fungus. derby.ac.uk University Of Derby/5BY543/_Shawa Classification of Fungi Based on Spore Formation 1.Zygomycetes These are formed by the fusion of two different cells. The sexual spores are known as zygospores, while the asexual spores are known as sporangiospores. The hyphae are without the septa. Example – Mucor. derby.ac.uk University Of Derby/5BY543/_Shawa Classification of Fungi Based on Spore Formation 2. Ascomycetes They are also called sac fungi. They can be coprophilous, decomposers, parasitic or Ascomycota saprophytic. The sexual spores are called ascospores. Asexual reproduction occurs by conidiospores. Example – Saccharomyces Saccharomyces. derby.ac.uk University Of Derby/5BY543/_Shawa Classification of Fungi Based on Spore Formation 3. Basidiomycetes Mushrooms are the most commonly found basidiomycetes and mostly live as parasites. Sexual reproduction occurs by basidiospores. Asexual reproduction occurs by conidia, budding or fragmentation. Example- Agaricus. derby.ac.uk University Of Derby/5BY543/_Shawa Classification of Fungi Based on Spore Formation Trichoderma 4. Deuteromycetes Also called imperfect fungi – Moulds. They do not follow the regular reproduction cycle as the other fungi. They do not reproduce sexually. Asexual reproduction occurs by conidia. Example – Trichoderma. Deuteromycetes derby.ac.uk University Of Derby/5BY543/_Shawa Medical Mycology A discipline that deals with the fungi that cause human disease. Mycoses – fungal diseases. Eukaryotic microorganisms: Kingdom of the fungi (Mycota) comprises over 50 000 different species. >200 of the thousands of species as human pathogens. Taxonomy of the fungi is essentially based on their morphology. derby.ac.uk University Of Derby/5BY543/_Shawa Metabolism Heterotrophs dependent on exogenous nutrient substrates as sources of organic carbon. Obligate aerobes. Found in almost all types of environments i.e. thermophilic, psychrophilic, acidophilic, and halophilic. Plant pathogens are extensively studied. derby.ac.uk University Of Derby/5BY543/_Shawa Fungal Infections Superficial mycoses: Superficial mycosis is a disease of the skin and its appendages caused by fungi. It comprises dermatophytosis, candidiasis, and pityriasis versicolor They have the affinity to keratin rich tissues and produce dermal inflammatory response, intense itching, and cosmetically poor appearance. Fungi causes infection of outer surface of hair shafts, skin shafts and nails. They are very rare E.g. Black Piedra Dermatophytosis derby.ac.uk University Of Derby/5BY543/_Shawa Fungal Infections Cutaneous mycoses: Also called dermatomycoses, ringworms, or tineas Most common fungal infections Infection occurs on the epidermal layer of skin and hair roots Three important genera: Epidermophyton Microsporum Trichophyton E.g. Tinea pedis derby.ac.uk University Of Derby/5BY543/_Shawa Fungal Infections Sub-cutaneous mycoses: Cause infection of the subcutaneous layer of skin. Saprophytic species Unable to penetrate the skin, they must be introduced into the subcutaneous tissue by a puncture wound that has been contaminated with soil. Nodules - become ulcer - protrude out of skin - pus containing drainage E.g. chromoblastomycosis mycetom derby.ac.uk University Of Derby/5BY543/_Shawa Fungal Infections Systemic Infection: Inhalation of fungal spores (wind dispersed soil borne spores) Lesion formation in lungs. Bursting of lesion Diffusion in blood Species are dimorphic i.e. exist in 2 forms of parasitic and saptophytic both E.g. Blastomycosis Coccidiodomycosis derby.ac.uk University Of Derby/5BY543/_Shawa 4. Systemic Infection Infection Inhalation of fungal spores (wind dispersed soil borne spores) Lesion formation in lungs bursting of lesion Diffusion in blood Species are dimorphic i.e. exist in 2 forms of parasitic and saptophytic both E.g. Blastomycosis Coccidiodomycosis derby.ac.uk University Of Derby/5BY543/_Shawa Fungal Disease Causative agent Black piedra Piedraia hortae White piedra Trichosporon beigelii Pityriasis versicolor Malassezia furfur Tinea nigra Phaeoannellomyces werneckii Candidosis Candida albicans Trichophyton Dermatophytosis Microsporum Epidermophyton derby.ac.uk University Of Derby/5BY543/_Shawa  derby.ac.uk University Of Derby/5BY543/_Shawa Laboratory diagnosis Specimens: Skin scrapings, nail clippings, hairs. Scrapings from mucous membrane. Scrapings, crusts, aspirated pus, tissue biopsy. Blood, CSF etc in systemic mycoses. Microscopy: KOH mount – KOH dissolves keratin and cellular material but does not affect fungi. Specimen is placed on a slide, a drop of 10-20% KOH is added and covered with a coverslip, left for 20 min in incubator at 37°C to digest keratin. Then examined microscopically. derby.ac.uk University Of Derby/5BY543/_Shawa Laboratory diagnosis Fungal growth Cultures are incubated for at least 2-3 weeks and in some cases up to 6 weeks. Cultures are examined macroscopically for colony morphology, and microscopically for fungal morphology. Potato dextrose agar (PDA). Sabouraud dextrose agar (SDA) Czapek-Dox agar Cornmeal agar derby.ac.uk University Of Derby/5BY543/_Shawa Key points Eukaryotic cells are larger than prokaryotic cells and have a “true” nucleus, membrane-bound organelles, and rod-shaped chromosomes. The nucleus houses the cell’s DNA and directs the synthesis of proteins and ribosomes. Mitochondria are responsible for ATP production; the endoplasmic reticulum modifies proteins and synthesizes lipids; and the golgi apparatus is where the sorting of lipids and proteins takes place. Peroxisomes carry out oxidation reactions that break down fatty acids and amino acids and detoxify poisons; vesicles and vacuoles function in storage and transport. Animal cells have a centrosome and lysosomes while plant cells do not. Plant cells have a cell wall, a large central vacuole, chloroplasts, and other specialized plastids, whereas animal cells do not. derby.ac.uk University Of Derby/5BY543/_Shawa Summary of structures of Fungi Almost all the fungi have a filamentous structure except the yeast cells. They can be either single-celled or multicellular organisms. Fungi consist of long thread-like structures known as hyphae. These hyphae together form a mesh-like structure called mycelium. Fungi possess a cell wall which is made up of chitin and polysaccharides. The cell wall comprises a protoplast, which is differentiated into other cell parts such as cell membrane, cytoplasm, cell organelles and nuclei. The nucleus is dense, clear, with chromatin threads. The nucleus is surrounded by a nuclear membrane. derby.ac.uk University Of Derby/5BY543/_Shawa PARASITISM derby.ac.uk University Of Derby/5BY543/_Shawa Parasitism Not mutual – only one benefits at the expense of the other. Intimate contact (feed off host). Usually do not kill host (parasitoids do). Herbivores(?) Parasitic Plants Holoparasites (lack chlorophyll) – Rafflesia (biggest flower). Hemiparasites (photosynthesize) – Mistletoe. Microparasites – reproduce inside host. Bacteria, viruses Macroparasites – release juvenile outside. E.g. trematodes Ectoparasites vs. endoparasites. derby.ac.uk Parasitism Common Possibly more parasites than anything else. 50% of insects parasitic. Potentially 4:1 parasites:free- living forms. Often complex life cycles. E.g. Lancet fluke, other trematodes. Several intermediate hosts derby.ac.uk  derby.ac.uk University Of Derby/5BY543/_Shawa derby.ac.uk Macroparasites Parasites represent a pervasive threat for their hosts. Macroparasites indicates parasitic protozoa and helminths. Have higher genomic complexity Complex life cycles requiring either one or several intermediate hosts. Require vectors E.g. Malaria parasites Transmitted from vertebrate host to vertebrate host Requires a competent mosquitoes Filarial nematodes relying on black flies Schistosomes that have water snails as intermediate hosts derby.ac.uk University Of Derby/5BY543/_Shawa Macroparasites derby.ac.uk University Of Derby/5BY543/_Shawa Self-Directed Study Hookworm Giardia lamblia Toxoplasma gondii derby.ac.uk University Of Derby/5BY543/_Shawa  Prokaryotes Summary Next lesson Eukaryotes X Entomology derby.ac.uk University Of Derby/5BY543/_Shawa Coursework 2 A 22-year-old female "gap-year" student returning from Southeast Asia presents to her GP with sudden onset of fever, severe headache, photophobia, dehydration, myalgia, and weakness. She vomits but also complains of diarrhoea, and stomach cramps from the past 3 days. In view of the travel history the GP suspects an infectious cause. She was assessed for gastroenteritis where a stool specimen was taken. You are working in a microbiology laboratory with unlimited resources; you received the stool specimen from this patient. Discuss the processes of handling the specimens to enable you identify and report a potential pathogenic organism including possible antibiograms. derby.ac.uk University Of Derby/5BY543/_Shawa Thank You Any Question derby.ac.uk University Of Derby/5BY543/_Shawa