Invertebrate defense

Question 1

Defense in invertebrates.

Answer 1

Threats, defense and repair mechanisms

Question 3

What are classes of threats and responses?

Answer 3

ecological causes of mortality
Extrinsic:
-accidents
-predation, defense mechanism
diseases, immune system
environmental stressors, tolerate, resist and repair.

Aging
INtrinsic:
- degeneration of systems,cells and molecules, denaturation of nucleaic acids and protiens
- can be influenced by extrisic factors
- can be repaird, to a point

Question 4

avoiding predators

Answer 4

dinural/ vertical migration
camoflage

Question 5

Camoflage in invertebrates?

Answer 5

All strategies involved in concelment.
Crypsis
when colour or behaviour is employed to prevent detection when in plain sight.
- background matching
- contershading, upper body is darker than lower body
- obliterative shading, disguises 3D forms
- disruptive colouring, markings appear as false boundaries
- distractive markings, direct attention to other things

Masquerade
Recognition is prevented by resembling an uninteresting object

Question 6

Avoiding predators

Answer 6

colour matching

Question 7

Dissuading and repelling predators

Answer 7

MOlluscs, uchordata, barnecles and polychaetes

Flash colouration
warning coloration - Aposematism
this contradicts cryptic colouration, wamrs predator than prey item is unprofitable

Allomones- chemicals preduced by animals for protection

Venom and other checmicals - cnidocytes

Accumulating allomones produced by plants or algea for own defense against predators.

Question 8

What is ant fouling?

Answer 8

1. Disrupting biofilm by killing diatoms
2. Inhibiting larval settlement and survical of polychaete larvea and other organisms

Releasing a chemical into the water means that inhibition is not restricted to organims physically touching the sponge.

Question 9

defense against internal invaders?

Answer 9

Immune systems
- recognition of antigens, probably evolved earlier
- adaptive immune system, vertebrates, antibodies, recognise antigen during infection
- Innate immune system, invertebrates, no antibodies

Question 10

What is innate immunity?

Answer 10

Phagocytic systems enhanced by clotting - haemolymph (haemocyte) coagulation system
* stops the spread of ad destroys bacteria
* enhances phagocytocis
* wound formation

phagocytic systems enhanced by clotting
* lectin-agglutinin system - ‘sticky’ protiens, recognises carbohydrates.

clotting is not problematic for invertebrates with open blood systems.

Question 11

When do invertebrates induce an immune response?

Answer 11

Schistosomes - coat themselves with host antigens
Fasciolids - toxic substances

Question 12

Invertebrate responses ot stressors or pollutants

Answer 12

Stress Response / pathway: [induces a chemical response]
Heat shock proteins
Metallothionien
Mixed function oxygenase

Chemical/environmental inducers:
Temperature, pesticides, heavy metals, solvents, industrial and municipal efflluents.
Heavy metals, exhaust and smoke particles
Pesticides, heavy metals, organic solvents and hydrocarbons (oil)

Question 13

Responses to pollutants?

Answer 13

Heat shock protins (hsp)
- help damaged proteins to reattain their native state
- minimise accumalation of non-functioning or toxic protein molecules.

Chaperones - hang around to protect proteins.
Threshold for production species specific control
COncentration reflects pollution
Metallothioniens (MTs)
- proteins that bind to heavy metals, detoxifys metals.

grahps in lec slides

Question 14

Heat and metal pollution?

Answer 14

Exposure to Cd increased MT expression, and sometimes enhanced at incr °T.
* Incr °T
* incr effect of metal AND/OR
* reduces tolerance to metal, OR
* metal interferes with ability to cope with temperature?

Question 15

Response to stressors?

Answer 15

MIxed function oxygenase (MFO)
- oxidises pollutant
- adds o2 atoms
- makes them easy to metabolise
- INducible, Molluscs - hydrocarbon pollution, Herbivourous insects - defense toxins produced by plants.

Question 16

Inernal stressors?
Aging

Answer 16

Senescence
-Aging, decline in function and increase in mortality
Negligible senescence
- no increase in mortality or decrease in fertility, physiological function or diseased resistance, animals can be long lived
Negative senescence
- Decline in mortality with age after reproductive maturity, usually accompanied by an increase in fecundity, animals with indeterminate growth.

Question 17

Why does aging happen?

Answer 17

• Telomere loss theory
• Oxidative stress / free radical theory
• Gene regulation theory

Question 18

What is the telomere loss thoery?

Answer 18

Telomere = cap at the end of a DNA strand that protects the chromosome

Shortening leads to problems with replication - disrupts tissue function and protein / ezyme structure = aging

Telomeres maintained more effectively in long-lived animal - telomerase activity is high.

Question 19

What is oxidative stress/ free radical theory?

Answer 19

Reactive O2 species:
free radicals that contain O2 with an unpaired electron, easily reacts with other molecules in the cell.

A build up may damage DNA, RNA, proteins and may cause cell death, usually increases with age.

Defence, anti-oxidant enzymes and proteasome enzymes.

Question 20

What is the gene regulation theory?

Answer 20

Senescence result of changes in the gene expression related to:
- Mitochondrial metabolism, DNA repair, electron transfer chain processes, programmed cell death ect.

In long lived sea urchins, age-related increase in gene expression related to:
- energy production, components of proteasome pathway, organogenesis, adults tissue repair and regeneration.

Question 21

What is the cell turnover rate?

Answer 21

Influences the rate of replacement of damaged proteins.
- Slows down with age
- high turnover rate [cnidarians, molluscs, annelids, plathelminthes]
- Low turnover rate [insects and nematodes]