A: topic 16 and 17 Flashcards Preview

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Flashcards in A: topic 16 and 17 Deck (10)
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1

16: fungi in general

Uni- or multicellular

Can't move

Need organic materal to feed on: feeding on living tissues or dead matter

Secretes digestive enzymes (extracellular)

(2/3 of all species) symbiotic lifestyle – mutualists or parasites

***(fungi (ammonification, sharing nutrients with other plants, biological wethering), crop plants (nutrient uptake, protection, common mycorrhizal network), herbivores(intestines), predators (intestines ex)

The concentration of poisonous chemical compounds such as heavy metals will increase as you reach higher to the top of the trophic level pyramid.(predators) )

2

16:
a) What can you say about the secondary metabolite production of fungi?

b) their function?

a) They prod (a huge amount of) secondary metabolites – often when the nutrients are limited for the fungi, the secondary metabolites will support/stabilize the primary metabolism

Alternative origin to secondary metabolites: horizontal gene transfer from bacteria

unrelated: Terricolous fungi accumulate heavy metals and poisonous chemical compounds

b) Support acquisition and defence of nutrient sources

Protect against UV radiation

During sexual reproduction They can help attract the hyphae of the opposite sex, then plays role in cell differentiation

3

16: Types of health hazards caused by fungi (5)

Radioactive materials in fungi can accumilate radioactive isotopes: became popular to study after the chernobyl disaster, ex they can replace them with K+

Allergy

Mycetism – muschroom poisening: ingestion

Mycotoxicosis: poisening caused by toxic compounds in microfungi

Mycosis: infection by pathogenic microfungi

4

16: What is Mycosis? in:
a) fish
b) amphibians
c) reptiles
d) birds
e) humans (4)

A fungal infection

In fish:
- Saprolegnia: caused by Saprolegnia spp., skin cotton like, often covered by algae, quarantine as a treatment.
- Fin rot: disease caused by the same reason as saprolegnia

In amphibians
- Amphibian chytrid fungus and phylum chytridiamycota, chytrids: lethal skin infections
- Huge skin areas affected which makes it impossible for gas exchange through the skin to occur--> dies

In reptiles
- Too cold and high air humidity --> not what reptiles likes, but fungi loves --> skin and mucous membranes effected

In birds
- Respiratory system very easily infected including the airsacs --> aspergillosis (infection

In humans
- Fungal infection can happen in case of immune deficiency, ex HIV
- Infection of skin and mucous membranes
- Subcutaneous infections via injuries
- Infection of internal organs
- All of these are often difficult to cure! Prevention is important

5

16: What is Mycotoxicosis? Give examples of microfungi causing these.

--> Poisening caused by toxic secondary metabolites

Never induce immune response: symptoms often occur when major organ damage is developed

EXAMPLES

Microfungi prod aflatoxins
- Liver: hepatitis, liver cirrhosis(not functioning properly) and cancer

Rubratoxins
- Damage in liver and kidneys, also affect CNS

Microfungi prod ochratoxins
- Damage to the liver: immunosuppressives, too much consumption of coffee beans and rye bread

Fumonisins
- Carcinogenic species: erosion of myelin sheath of axons
- Produced by fusarium spp.

Trichothecenes
- Inhibit protein synthesis
- Produced by fusarium spp.
- Patchy color on plants is a clear sign of fungi infection: cereals and grass spp.

Zearalenon
- Produced by fusarium spp.
- Interferes with sexual maturation


6

16: what is Mycetism?

It is mushroom poisoning

Ingestion of toxic substances present in macrofungal sporocarps

Many fungal species poisonous to humans often have no adverse effect in animals: not eaten by animals

7

17: Mycetism: mushroom poisening in humans; general information

Never eat raw fungi!!

Macrofungal poisoning with a long latency period

Macrofungal poisoning with a short latency period

8

17: Macrofungal poisoning with a long latency period
a) example
b) Symptoms
c) Effects
d) treatment

a)
Ex phalloides syndrome ex. death cap – mycorrhizal with oak

b)
half a day to one day: vomiting diahrrea, 2 days later: acute symptoms, ex liver enlargement, haemorrhages in stomach and intestines

Cyclic (=stable) poisonous compounds --> body cannot eliminate

c)
Can inactivate the RNA polymerase II enzyme --> terminate the protein synthesis within 48 hours (transcription),

Phallotoxins and virotoxins: inhibit cell division and destroy cell membranes

d)
Removal of toxins from the intestinal tract and the blood immediately!!

Livertransplant may be needed, and changing all of the blood

These are very deadly!

9

17: Macrofungal poisoning with a short latency period
a) example
b) mechanism of action and effects
c) Symptoms

Not a very serious posening

a)
Hallocinogenic fungi ex muscarinic syndrome – fiber caps species

b)
Strutural analog of acetylcholine --> can bind to its receptors and activate them

Parasympathetic nervous system uses acetylcholine --> parasympathetic predominance

c)
Persiptation, salivation, lacrimation

10

17: Other macrofungal poisonings
a) example
b) Symptoms and cause
c) treatment

a)
Ex Paxillus syndrome - Paxillus involutus
Yellowish brownish colour – when touched turns dark brown

b)
cause:
- Vomit if eaten raw
- Won't vomit if cooked, but some are very sensitive to it and can cause serious sepsis which causes injury to tissues and organs

symptoms: Pain in kidneys, blood in urine,

c)
Transfusion of blood, symptomatic treatment; only affect the symptoms not he cause