Flashcards in Lectures 16-21 Deck (70):
Miletones in Biotechnology
1914 - Strain selection, Koki
1929 - Fleming
1942 - Tatum and beadle one gene one enzyme
1953 - Roger's parasexual analysis
1955 - Backus and staffer mutagenesis
1967 - Pirt and righelato continuous culture
1984 - Ball, Parasexual breeding
1987 - Recombinant DNA
2000 - "Omics"
Genetic analysis of fungi
One gene- one enzyme hypothesis ( Neurospora crassa)
Dissection of yeast life cycle - Schizosaccaromyces pombe
Why are fungi good for classical genetics
Ease of growth
Short life cycles
Many have a sexual stage
Asexual spores that can be used or stored in bulk
Simple nutrients requirements
Can be correlated with genetic studies
Heterothallic life cycle
Conidium, Hyphae, Mycelium, Colony
MatA or Mata
Sexes that reside in different individuals.
Heterothallic fungi require two compatible partners to produce sexual spores.
Within a single organism it has the resources to reproduce sexually. Both male and female systems on same thallus. Different cells of a single mycelium
Biotechnologically, fungi are..
Form hyphal network
Show polarised growth
Most ascomycetes and certain basidiomycetes
and zygomycete mucor spp..
Fungi for industrial use must be able:
Spores easily inoculated into large fermenters
Grow rapidly and form product in large culture
Produce desired product in short period of time
Grown inexpensive nutrient
Not be pathogen
Amenable to genetic manipulation
Solid state fermentation
Submerged liquid fermentation
Amono acids, peptides, ergot alkaloids, lovastatin, citric acid, itaconic and fumaric acid
Loads of peptidases
Fungi : Endoglcucanases, cellobiohydrases, b- glucosidades
Lignin- protects cellulose. Can be used- bio pulping and bleaching without use of chemicals
Which a cell engulfs another cell so that the host cell and the internalised cell form an interaction
Drives evolution of organelles
Champion of endosymbiosis theory
Evidence to support mitochondria and chloroplast bacterial endosymbiotic ancestry
Doolittle and grey
Mitochondria and plastis contain genomes
Sequened genomes shows genes encoded by discrete bacterial ancestry.
Plastid genes most like cyanobacterias genes
mitochondrial genes like alpha proteabacterial genes
What did margulis get wrong?
Bacteria to protist
Spirochete proposed as progenitor of cilia
Thermoplasma Archie proposed as progenitor of major cell body
No organelle genomes define ancestry of cilia
No significant portion of nuclae endcoded genes of spirochete/thermoplasma
No cilia or cytoplasmic protein sets of spirohchete/thermoplasma ancestry
How does endosymbiosis occur
Englulfment leading to incubation
Prokaryotic became integrated cellular structure
Membrane folds called Cristal evolved
Site of ATP generation
Not all mitochondrial derived organelle look like this.
Many proteins in mitochondria are encoded in the nucleus
Membrane- enclosed hydrogen producing organelle. Has genome
Generatres ATP by anaerobic.
Can make iron sulphur clusters
These are derived from same endosymbiosis as mitochondrial progenitor
Found all over. If they have this, they don't have mitochondria.
Mitochondira to hydrogensomes
Nucleus is in control. Same primary endosymbiosis different functional outcomes
Function differences between mitochondria and plastid
Mitochondria - Anaeobic and aerobic ATP. Iron- sulfur cluster biogenesis. Generatre heat
Plastid - Photosynthesis, uses CO2,. Fatty acid biosynthesis.
Iron- sulfur cluster biogenesis
Cyanoacterial endosymbiosis occurred prior to diversification of algae and plants
Why other plastids?
Secondary endosymbiosis. Occurred multiple times. 3/4 membranes. Tertiary endosymbiosis also known.
Plastid secondary endosymbiosis of malaria.
Marlia pathogens plasmodium contain a secondary acquired plastid organelle.
Plastid (apicoplast) does not perform photosynthesis.
Surrounded by 4 membranes
Most encoded by nucleus
Fatty acid biosynthesis
Good source for drugs attacking malaria
Naked or enveloped
Capsid - 60-95% protein
Nucleic acid core
coat + core = nucleo capsid
RNA OR DNA, ss or ds
Shapes: Rods, threads, gemini, icosohedrons
Bacteriophages and mycophages
Diseases caused by virus
Foot and Mouth virus (apthovirus)
Blue Tongue virus ( Orbivirus)
Tobacco mosaic virus ( ssRNA, plants
Lack enveloped nucleus
Lack a true wall
cause plant and animal disease
Myxomycota- Slime moulds
Acellular ( clubroot), (physarum)
Oomycota - Water moulds
Pythium - Damping off diseases
Plasmopara - Downy mildews
Albugo - White rusts
Phytophthora - Late blight
Everything not plants animal or fungi. Artificial grouping ( Paraphyletic)
Important parasites of humans
Mitochondria contain kinetoplast ( Ciricular DNA inside mitochondria, many copeies of this gene) Vectore - Borne parasites.
Typanosomes are included in this
Infect vertebrate and arthropods and leech vectors
Parasite : Trypanosoma Cruzi
Vector : Triatomine bugs
Acute forms- brief
Chronic - Long term]
Trypanosoma Cruzi cruzi (South America) Identical to ones infecting bats, but different epidermiology ( Vectors, hosts, pathologies)
Life cycle of Chagas disease
Trypomastigote found in blood stream of infected vertebrates
Amastigore is the intracellular dividing form in cytoplasm of vertebrate cells
Epimastigore found in insect vector.
Infects many mammals ( Natural reservoir)
Bites near eyes ( chagoma)
Entry of Chagas Disease
Feeding wound, blood, muscle, nerves, macrophages.
Attack, Cardiac muscle, smooth muscle, autonomic nerves, macrophages.
Immune Evasion of Chagas disease
Intra- Cellular multiplication
Can grow within macrophages - Can escape phagocytic vacuole.
Pathology of Chagas disease
Acute - First few weeks, mild symptoms. Swelling. Caused by amastigore multiplication and cell rupture - Kids vulnerable.
Chronic - Persists and enters chronic. Toxins released by intracellular amastigotes, cause widespread damage.
Destruction of autonomic nerve elements ( Mega syndrome)
Muscle denervation (Megacardia)
Autoimmune tissue destruction
African Sleeping Sickness
Parasite - Trypanosoma Brucei
Vector - tsetse flies
Distribution of sleeping sickness
Two forms, each with distinct ecology and epidemiology
Type of sleeping sickness
West - Trypanosoma Bruce gambiense
East - Trypanosoma Brucei rhodesiense
Gambiense - Invades central nervous system, chronic
rhodesiense - Widespread organ damage, acute
Invasion of sleeping sickness
Inoculated by tsetse fly.
Immune invasion of sleeping sickness
Parasite presents a series of variant antigenic types by virtue of its surface coat.
Coat made up of variable surface glycoproteins (VSGs)
VSG's pack tightly, prevents immune recognition, protects lytic compounds in host serum.
Change throughout infection
There is undulating waves of parasitaemia. (Waves as VSG changes.
In tsetse flies, only procyclin expressed.
In bloodstream many more ( begins in salivary gland)
Only VSG's in telomeric expression sites expressed. Only 1 active.
Methods of antigenic variation for sleeping sickness
Use of different VSG expression sites - in situ switch
DNA recombination changes VSG present in active expression site - Gene conversion.
Pathology of sleeping sickness
Acute - Fever, headaches. Overcomes hosts defences, causes extensive damage everywhere.
Direct result of invasion, multiplication and circulation of parasites in lymph and blood.
Parasite antigens adsorb red blood cells
Parasites require glucose
W=Swelling of lymph nodes.
Chronic form of sleeping sickness
24 sleep wake cycle.
Inflammation fo brain
Lesions in cerebral cortex
High dosage of drugs, including arsenic
Types of diarrhoea
Osmotic-Enterocyte malfunction, imparted absorption, enhanced secretion, excessive solutes
Inflammatory- Mucosal invasion, leukocytes in stool
Secretory - Toxin associated, lots of water
Solution to diarrhoea
Oral rehydration salts and zinc
Safe drinking water
Fecal - Oral transmission
Trophozoite inhabits intestinal tract but not infectious
Cysts are excreted and are infectious
Diarrhoea, disease of small intestine
Dysentery involves blood and mucus in stool.
Parasite damage in gastroenteritis
Water absorption impaired due to epithelial damage
Crypt cells produce new cells but excrete water and Cl
Water not reabsorbed with NA+
Infects all vertebrates. Humans infected by 6 but only histolytic causes disease - Dysentery.
Entamoeba dispar. vs histolytica
Only drug = Nitroimidazole.
Fecal- oral cycle.
In factious cysts passed through faeces
Trophozoites replicate in large intestine
Cysts can survive days to weeks.
Lyses cells in contact dependent manner - Eats its way into epithelium and beyond.
Process of Histolytica
1) Crawling and feeding
2) Erosion of the mucous layer for contact depending killing
3) ECM breakdown and neutrophil killing
4) Perforation of serous layers leading to peritonitis
5) Access to circulatory system.
Virulence factors of histolytica
1) Adhesision - Gal/GalNAC lectin
2) - Mucous breakdown - Cysteine proteases
3) - Cytotoxicity - pore forming peptides (Amebapore)
Colonises upper portions of small intestine. Asymptomatic infections - 2 nucleus's
Fecal - oral route.
Produces resistant cysts
Enterotest is used to diagnose
Adhesive disk of giardia
Important for adhesion to intestinal epithelium
Made from cytoskeleton and contractile proteins
Unique cytoskeletal element called a micro ribbon
Inhibitors of microfilament attachment function also inhibit attachment
Impression in microvilli
Pathogenesis of giardia
Attachment causes irritation and mucosal injury
Villus blunting, enterocyte apoptosis
Increase crypt cell activity - Hyperplasia with hyper secretion of Cl- and water
Treatment of giarada
Nitroimidazole drugs or metronidazole
Only known human infectious ciliate
Common with pig workers
Fecal oral route.
Typical ciliate with cilia and micro and macro nucleus
diarrhoea or dysentery causing
Rarely invades intestinal epithelium, but similar to entamoeba dysentery
Common, Irritable bowel system
4 subtypes common in humans
Controversy re mode of transmission/ life cycle.
C. Hominis or C. Parvum
Immune suppression, often deadly in AIDS patients.
Extracytoplasmis association of cryptosporidium
Sporozoites do not invite enterocytes(cells on first layer) but attach to epithelial cells
Induce fusion of microvilli - Parasite encapsulated by bhost membrane.
Hidden from immune system
Sexual reproduction of cryptosporidium
Two rounds of asexual reproduction of zygote to generate oocyst
thick walled ones thought to be excreted and thin walled cysts reinfect
Healthy individuals suppress merozoiute ( things that infect others) release.
Can go fecal oral
But waterborne outbreaks. Oocysts resistant to chlorine treatment
Parvum from animal waste.
Cryptosporidum Hominis, Parvum
Entamoeba Histolytica - Amoebozoa
Giadria Intestinalis -Excavata
Dientamobea fragilis - Excavata
Cryptosporidum Hominis, Parvum - Apicomplexan
Balandtidium coli - Ciliate
Blastocystis - Stramenophile