Lectures 16-21 Flashcards Preview

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Flashcards in Lectures 16-21 Deck (70):
1

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"
CRISPR

2

Genetic analysis of fungi

One gene- one enzyme hypothesis ( Neurospora crassa)
Dissection of yeast life cycle - Schizosaccaromyces pombe
Lactam antibiotics

3

Why are fungi good for classical genetics

Ease of growth
Short life cycles
Most haploid
Many have a sexual stage
Asexual spores that can be used or stored in bulk
Simple nutrients requirements
Can be correlated with genetic studies

4

Neurospora crassa

Heterothallic life cycle
Conidium, Hyphae, Mycelium, Colony
MatA or Mata
perithecium
Ascus, Ascospores

5

Heterothallic

Sexes that reside in different individuals.
Heterothallic fungi require two compatible partners to produce sexual spores.

6

Homothallic

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

7

Biotechnologically, fungi are..

Versatile metabolically
Form hyphal network
Show polarised growth
Most ascomycetes and certain basidiomycetes
and zygomycete mucor spp..

8

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

9

fuNGI Player

Aspergillus niger
aspergillus oryzae
Penicillin chyrsogenum
cephalosporin acremonium
rhizopus spp
mucor spp

10

Solid state fermentation

Koji process

11

Submerged liquid fermentation

Chemostat
Substrate costs

12

Fungal products

Amono acids, peptides, ergot alkaloids, lovastatin, citric acid, itaconic and fumaric acid
Loads of peptidases

13

Cellulolytic ungi

Fungi : Endoglcucanases, cellobiohydrases, b- glucosidades
Trichoderma reesei
penicillium pinophilum
acremonium spp

14

Biofuels

Lignin- protects cellulose. Can be used- bio pulping and bleaching without use of chemicals

15

Endosymbiosis

Which a cell engulfs another cell so that the host cell and the internalised cell form an interaction
Drives evolution of organelles

16

Lynn Margulis

Champion of endosymbiosis theory

17

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

18

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

19

How does endosymbiosis occur

Englulfment leading to incubation
Prokaryotic became integrated cellular structure
Double membrane
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

20

Hydrogensomes

Muller

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

21

Chloroplasts

Nucleus is in control. Same primary endosymbiosis different functional outcomes

22

Function differences between mitochondria and plastid

Mitochondria - Anaeobic and aerobic ATP. Iron- sulfur cluster biogenesis. Generatre heat

Plastid - Photosynthesis, uses CO2,. Fatty acid biosynthesis.
Isoprenois biosynthesis.
Iron- sulfur cluster biogenesis

Cyanoacterial endosymbiosis occurred prior to diversification of algae and plants

23

Why other plastids?

Secondary endosymbiosis. Occurred multiple times. 3/4 membranes. Tertiary endosymbiosis also known.

24

Plastid secondary endosymbiosis of malaria.

Marlia pathogens plasmodium contain a secondary acquired plastid organelle.

Plastid (apicoplast) does not perform photosynthesis.
Surrounded by 4 membranes
Small genome
Most encoded by nucleus

25

Apicoplastid

Fatty acid biosynthesis
Heme biosynthesis
Isoprenois biosynthesis
Good source for drugs attacking malaria

26

Viroids

ssRNA's
Plant disease

27

Viruses

Retrograde evolution
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

28

Diseases caused by virus

Foot and Mouth virus (apthovirus)
Blue Tongue virus ( Orbivirus)
Avian flu
Swine flu
Tobacco mosaic virus ( ssRNA, plants

29

Mycoplasmas

0.1 uM
Smalle genome
Lack enveloped nucleus
Lack a true wall
spirals
cause plant and animal disease
Peach yellows
Mycoplasma pneumonia

30

Myxomycota- Slime moulds

Wall-less
Cellular (Dictyostelium)
Acellular ( clubroot), (physarum)

31

Oomycota - Water moulds

Pythium - Damping off diseases
Plasmopara - Downy mildews
Albugo - White rusts
Phytophthora - Late blight
Saprolegnoia

32

Protists

Everything not plants animal or fungi. Artificial grouping ( Paraphyletic)

33

Excavates

Important parasites of humans

34

Kinetoplastids

Mitochondria contain kinetoplast ( Ciricular DNA inside mitochondria, many copeies of this gene) Vectore - Borne parasites.
Typanosomes are included in this

35

Trypanosome

Infect vertebrate and arthropods and leech vectors

36

Chagas disease

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)

37

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)

38

Entry of Chagas Disease

Feeding wound, blood, muscle, nerves, macrophages.
Attack, Cardiac muscle, smooth muscle, autonomic nerves, macrophages.

39

Immune Evasion of Chagas disease

Intra- Cellular multiplication
Can grow within macrophages - Can escape phagocytic vacuole.

40

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

41

African Sleeping Sickness

Parasite - Trypanosoma Brucei
Vector - tsetse flies

42

Distribution of sleeping sickness

Two forms, each with distinct ecology and epidemiology

43

Type of sleeping sickness

West - Trypanosoma Bruce gambiense
East - Trypanosoma Brucei rhodesiense

Gambiense - Invades central nervous system, chronic
rhodesiense - Widespread organ damage, acute

44

Invasion of sleeping sickness

Inoculated by tsetse fly.
Blood
Lymph
Lymph nodes
Cerebrospinal fluid
Brain

45

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.

46

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.

47

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.

Haematolymphatic phase

48

Chronic form of sleeping sickness

Meningoencephalitic phase
24 sleep wake cycle.
Neurological symptons

CNS invasion
Inflammation fo brain
Lesions in cerebral cortex
Myelin destruction

High dosage of drugs, including arsenic

49

Types of diarrhoea

Osmotic-Enterocyte malfunction, imparted absorption, enhanced secretion, excessive solutes

Inflammatory- Mucosal invasion, leukocytes in stool

Secretory - Toxin associated, lots of water

50

Solution to diarrhoea

Oral rehydration salts and zinc
Vaccination
Safe drinking water
improved hygiene.

51

Fecal - Oral transmission

Trophozoite inhabits intestinal tract but not infectious
Cysts are excreted and are infectious

52

Gastroenteritis

Diarrhoea, disease of small intestine
Dysentery involves blood and mucus in stool.

53

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+

54

Entameoba

Infects all vertebrates. Humans infected by 6 but only histolytic causes disease - Dysentery.

55

Entamoeba dispar. vs histolytica

Morphologically indistinguishable.
Only drug = Nitroimidazole.

56

Entameoba histolytica

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.

57

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.

58

Virulence factors of histolytica

1) Adhesision - Gal/GalNAC lectin
2) - Mucous breakdown - Cysteine proteases
3) - Cytotoxicity - pore forming peptides (Amebapore)

59

Giardia

Colonises upper portions of small intestine. Asymptomatic infections - 2 nucleus's

Fecal - oral route.
Produces resistant cysts

Enterotest is used to diagnose

60

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

61

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

62

Treatment of giarada

Nitroimidazole drugs or metronidazole

63

Balantidium coli

Only known human infectious ciliate
Common with pig workers
Fecal oral route.

Typical ciliate with cilia and micro and macro nucleus
nuclear dimorphism
asymmetric division
diarrhoea or dysentery causing
Rarely invades intestinal epithelium, but similar to entamoeba dysentery


64

Blastocystis homis

Common, Irritable bowel system
4 subtypes common in humans

Controversy re mode of transmission/ life cycle.
Stramenophile

65

Cryptosporidium

Apicomplexan parasite
C. Hominis or C. Parvum
Immune suppression, often deadly in AIDS patients.

66

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

67

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.

68

Transmission cycles

Can go fecal oral

But waterborne outbreaks. Oocysts resistant to chlorine treatment

Parvum from animal waste.

69

Entamoeba Histolytica
Giadria Intestinalis
Dientamobea fragilis
Cryptosporidum Hominis, Parvum
Balandtidium coli
Blastocystis

Entamoeba Histolytica - Amoebozoa
Giadria Intestinalis -Excavata
Dientamobea fragilis - Excavata
Cryptosporidum Hominis, Parvum - Apicomplexan
Balandtidium coli - Ciliate
Blastocystis - Stramenophile

70

Mycoplasma

0.1um, Small genome
Lack enveloped nucleus
Lack true wall - Gram positive
Spirals (spiroplams)
Cause plant and animal disease
Plant pathogens - Peach yellow/ Elm phloem necrosis
Pneumoniae