Puking

FISH ATTACK!
Do you know that fish can stay for a long period on land?
How? Why?
To be able to stay on land, fish need to overcome ammonia toxicity

Why is ammonia toxic?
From the organism level, ammonia toxicity causes hyperventilation, hyperexcitability, coma and subsequently death.
From the cellular level,
1. membrane effect-- ammonia substitute K+ in Na+,K+-ATPase, and NKCC co-transporter affecting ionic balance and substitute for H+ in Na+/H+ exchanger
2. affect intracellular pH
3. increase in intercellular glutamate-- from ammonia-induced astrocyte swelling, increase in activation of NMDA receptor lead to more glutamate production, influx of Ca2+ and Na+ into neurons. To maintain the influx, Na+,K+-ATPase work to pump out Na+ to normal - deplete ATP. Ca2+ lead to destruction of astrocyte.
4. depletion of a-KG.
high NH3 level results in hepatic encephalopathy due to acute liver failure.

The 7 strategies tropical fish use to adapt to ammonia toxicity
1. decrease in proteolysis and/or a.a. catabolism
2. partial catabolism to alanine
3. active excretion of ammonia
4. glutamine synthesis
5. urea synthesis
6. high ammonia tolerance
7. volitilization of ammonia

giant mudskipper- strategies 1, 2, 3
climbing perch- strategy 3
4-eyed sleeper- strategies 1 n 3
african lungfish- strategies 2 n 5
the weatherloach- strategies 1, 2, 4, 6, n 7
swamp eel- strategy 6
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uric acid are water insoluble, thus some animals such as bird excrete nitrogenous waste thru uricolysis to preserve water
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HOT HOT HOT!
Stability - poikilotherm (changes with the environment) and homeotherm (constant b.t.)
Source - ectotherm (environment) and endotherm (generate internal heat)

most mammal n birds are endotherm and homeotherm
most invertebrates, amphibians, fishes n insects are poikilotherm and ectotherm
However, large insects are endotherm and poikilotherm, fishes (polar) are homeotherm and ectotherm

Effects of temperature
- Only protein and lipids are affected by T
- At high T, van der Waals forces and hydrogen bonds are affected
- but hydrophobic interactions are stabilised
- cold T solidify cell membrane
- high T affect membrane fluidity thus affecting membrane permeability

homeoviscous adaptation
1. length of FA chain
2. saturation
3. cholesterol
4. types of phopholipid- PC for warm-acclimated; PE for cold-acclimated

Adaptations to warm-temperature
1. increase heat loss across the respiratory surface, panting, gular fluttering
2. sweating in large animals with low SA/V ratio
- salt in sweat; salt increase boiling point thus can help dissipate out more heat
- in prolong heat environment, NaCl is decrease to minimise ionic and osmotic balance
3. HSP -- help to catalyze newly translated prot and denatured prot
factors influencing induction of HSP
- environmental stress-- T, hypoxia, hyperoxia, oxidant, alcohol, UV
- pathophysiological stressors-- microbial infection; tissues trauma
- normal conditions -- cell cycle; hormonal induction; microbial growth
heat shock response-- increase in level of HSP
- under non-stressful condition, HSF bind to HSP
- stress condition activate release of HSP from HSF
- HSP binds to denatured protein while HSF forms trimer and bind to promoter of HSE
- HSP protein transcripted; polyA+ mRNA exported to cytoplasm n translated into HSP
- Increase in HSP level stop transcriptional activation

IT'S SNOWING!
Strategies to survive cold
1. freeze-tolerance-- freeze extracellular fluid before it gets freeze by the T
2. freeze-avoidance
3. antifreeze macromolecules -- these are prot n glycoprot; non-colligative action

How to compensate for low rates of activities under cold T?
1. make more enzymes eg cytochrome oxidase
2. make different enzymes; isoform
3. generate heat
- shivering for a short period
- metabolic futile cycle
- brown adipose tissue
- leakiness of mito inner memb
4. piloerection-- insulation of fur; longer are better
5. vasomotor response-- less blood transfer near skin
6. countercurrent exchange in some birds

Don't bother about me. The gun is just overloaded!
.................................................................to-be-continued =p
I need to go hibernate now -- no food, no water, low T
- brown tissue
- thermogenin, UCP1 and thermogenesis
- urea cycling and muscles atrophy
- signalling molecule
- changes in metabolic pathway
HERRE I COME>>>>>>>>>>>>>>>>>>>>>>>>>>>>>