Polar Physiology

Freeze tolerant

animals that endure ice formation in extracellular body fluid compartments

freeze avoiding

species possess physiological mechanisms that promote extensive supercooling of body fluids throughout winter

are collembola freeze tolerant or freeze avoiding

freeze avoidant

• high capacity for supercooling

• relatively impermeable cuticula

• uses cryoprotective dehydration

cryoprotective dehydration

dehydrate water content within body

• involves water vapour pressure (WVP) between ice in the soil and the supercooled hemolymph which drives a net outflux of water vapour

• the difference in WVP is so large it results in water loss of organism

• continuing until pressure of body fluid equals that of the surrounding ice

• this response eliminates internal body ice formation as little water content

thermal hysterisis

difference between the melting points and the freezing temperature

• what temperature are ice crystals going to grow wtihin fluid

hysteresis freezing point

temperature of ice growth

ice binding proteins and effect assosciated with them

changes curvature of ice crystals which lowers melting point

• adsorb to the surfaces of ice cyrstals and prevent water molecules from joining the ice lattice at the ice binding protein adsorbtion location

• ice that ice that grows on the crystal surface between the adsorbed IBPs develops a high curvature that lowers the temperature at which the ice crystals grow (Gibbs Thomson effect)

• the depression creates a gap between the melting point and the nonequilibrium freezing point within which ice growth is arrested

metabolic adaptation to cold and example

higher metabolic rate due to cold

• collembola

metabolic rate changes and reason for changes in collembola

high in winter - low in summer (positive correlation)

shows higher metabolic rate than temperate species

antarctic midge reproductive behaviour

1. adult emergence is a synchronous event occurring in early summer and mate in swarms

2. larvae of midges are non-selective feeders on decaying plant matter and terrestrial algae

3. 4 instars and can overwinter in any instar

4. 2 years development as larvae

5. egg covered in anti-freeze jelly to stop desiccation

6. larvae are freeze tolerant and endure ice formation in extracellular body fluid compartments

gene ontogeny

starts with molecular function

• what are gene products produced by gene

• molecular level activities performed by gene products (catalysis or transport)

• molecular functions generally correspond to activities that can be perfomred by individual gene products

then cellular component

• what functions are being performed

• the locations relative to cellular structures in which a gene product performs a function

then biological process

• the larger processes by multiple molecular activitites

• ex. dna repair or signal transduction

purpose of male accessory glands for antarctic midge

male accessory gland

• steroid hormone secretions

• mating plug

• trigger for ovipositing in females

impact of larval dehydration stress on female antarctic midge fertility

• reduced egg output

• reduced amounts of meterials invested in the progeny at birth

• increase in breakdown of tissues

• increase of carbohydrate motabolism

• accessory gland reduced

polar bear reproduction traits and requirements for success

• K selected

• females mature and breed at 4-5 years

• litter size = 1-3 cubs, 2 most common

• minimum reproductive interval with a successful litter = 3yrs

• females enter dens between sep and dec

  • a successful rearing period =

    • thermal protection

    • time for cub maturation

    • lack of natural or human disturbance

    • security from predation

gas chromatography

process to separate sample components

• uses a gaseous phase via temperature ramping

• sample is vaporised and injected into column then adsorbed onto surface before transported by inert gas such as argon

Quantitative fatty acid signature analysis

• see how much fatty acid is in the tissue

• estimates diet composistion of individuals by comparing predator to prey

  • based on knowledge taht ceratin fatty acids are integrated with minor and predictable modification from teh prey to the predators fat storage tissues

polar bear diets for baffin bay, gulf of bootia, and lancaster sound

gulf of boothia

• high proportion of ringed seal, bearded seal

lancaster sound

• bearded seal

baffin bay

• harp seal

• bearded seal but most common adult females

purpose of thyroid hormones in arctic animals

controls:

• thermoregulation

• metabolism

• reproduction

impact of raising cubs on adult females bodies

• females with cubs of years = 26kg lighter

• females with yearlings = 14 kg lighter

• females 29 kg heavier in sep compared to april

• body condition index lower in females with cubs of years then solitary females

• body condition index same in females with yearlings and solitary

radioimmunoassay technique (RIA)

• sensitive in-vitro technique

• measures teh concentration of antigens through the use of antibodies directed against these antigens

• performed by using antibody-antigen binding and radioactive antigen

• basic principle =

  • competitive binding reaction

  • the analyte competes with radio-labelled antigen for binding to the fixed amount of antibody or the binding sites of the receptor

seasonal variation in plasma thyroid hormones in relation to body condition and fasting state

• TT3 adn FT3 plasma concentrations were affected by season

• TT3 affected by breeding status

• TT3 and FT3 higher in solitary females in spring

• TT3 and FT3 in females measured during autumn were comparable in all females regardless of status

• TT4 adn FT4 were comparable in solitary, breeding, and season

• TT4 adn FT4 concentration significantly affected by season adn decreased from spring to autumn for all females

main polar bear diseases

brucella

morbillivirus

influenza A virus

toxoplasma gondii

causes for rise of polar bear diseases

warming temperatures

changing precipitation regimes

arctic warming 2x as fast as the rest of the planet

immunoglobulins

key role in bodys immune system

they are antibody proteins produced by specific immune cells

found in all jawed vertebrates that diverged from jawless fish

IgM (macro-immunoglobulin) antibodies - what is it, structure, production

what is it?

• 1st response immunoglobulin on exposure to foreign bodies

• provides short-term protection whilst the body makes other antibodies

structure

• pentameric in mammals

• hexameric in amphibians

• tetrameric in bony fish

production

• foetal liver during embryonic development

• bone marrow

• peripheal lymphoid tissue in adults

• plasma blasts in spleen

IgG (immunoglobulin G antibodies)

monomer with two antigen binding sites

formed by plasma B cells fighting infections from bacteria and viruses

most immunoglobulins in blood are IgG

IgG is only immunoglobulin that crosses placenta

acquired immunity - learns

seroprevalence

how many antibodies in blood which shows how many antibodies they have faced

proportion of individuals within a population affected by a disease at a specific time point based on positive testing for serum antibodies

enzyme linked immunosorbent assay (ELISA)

an immunological assay commonly used to measure antibodies, antigens, proteins, and glycoproteins in biological samples

direct ELISAs use a conjugated primary antibody while indirect iELISA include an additional amplification step

seroprevalence for males vs female polar bears to pathogens

males = 1.82x more likely to be positive for trichinella

females = 4.95x more likely to be positive for B. bronchiseptica

increased with age

bears more exposed to humans

• 2.24x more likely for trichinella

• 1.97x more less likely for F. tularensis

effect of climate change on seroprevelance of pathogens for polar bears

summer temp

• higher seroprevalence of trichinella and B. bronchiseptica

winter temp

• increase in trichinella

precipitation

• wetter summers within dryer years increased teh likelihood of polar bears seropositive for T. gondii

ursus arctos arctos reproductive traits

breeding may to july

polygamous

fertilized eff floats freely in females uterus for up to 5months before implantation at beginning of hibernation

between jan-mar cubs are born in winter den

what are the metabolic reactions to hibernation

74% drop in metabolic rate

6c drop in body temperature

24% drop in cardiac output

25% drop in oxygen consumption

increased affinity of haemoglobin to oxygen

metabolome

total number of metabolites present within an organism, cell, or tissue

metabolite

substance formed in or necessary for metabolism

metabolomics

emerging field that quantifies numersou metabolites systematically

proteome

number of proteins present in an organism, cell, or tissue

proteomics

study of the structure and function of proteins, including the way they work and interact with each other inside cells

differences in proteome for hibernating bears

protein concentration higher in winter

innate antimicrobial proteins protecting health were increased

down regulating complex multiprotein cascades and up regulating a small number of generalist and principal effector proteins

very few intracellular proteins released from bone and muscle tissues

sex hormone binding globulin isoform 1

functions as an androgen transport protein, can be involved in receptor mediator processes

each dimer binds one molecult of steroid

specific for 5 alpha dihydrotestosterone, testosterone, and 17-beta-estradiol

regulates teh plasma metabolic clearance rate of steroid hormones by controlling their plasma

cathelicidin antimicrobrial peptide

binds to bacterial lipopolysacharides

has antibacterial activity

carbonic anhydrase 2

essentail for bone resorption adn osteoclast differentiation

serum albumin

most common - general purpose transporter proteins

good binding capacity for water, Ca2+, Na+, K+, fatty acids, hormones, bilirubin, drugs

main function is the regulation of the colloidal osmotic presssure of blood

major zinc transporter in plasma, typically binds about 80% of all plasma zinc

carnitines

ammonium compound

play critical roles in energy production

essential cofactor that helps transport long chanin fatty acids into the mitochondria so that they can be oxidized to produce energy in the form of ATP

gives water to bear

phosphatidylcholines

major components of biological membranes and pulmonary surfactant

essential component of the very low density lipoprotein complex that facilitates the transport of tricylglyverols out of the liver

sphinogomyelins

sphingolipid

involvement in the regulation of endocytosis - into cell

receptor mediated ligans uptake

ion channel and G-protwin coupled receptor function

in protein sorting

component of myelin sheath and cell membranes

proteome and metabolome changes in hibernating bears

albumin increased 1.18x (causes higher viscosity in blood)

4 antimicrobial proteins increased = haptoglobin-2, lysozymes, N-acetylmuramoyl-L-alanine amidase, IGA1 (immunoglobulin A1)

lipids upregulated or downregulated depending on type

transporter proteins increased - free fatty acids, cholesterol, triglycerids, and phopholipids

protein that increases the most in hibernating bears

sex steroid hormone

carrier proteins for steroid hormones

glucocorticoids

• corticosterone binding globulin

• albumin

progesterone

• corticosterone binding globulin

• albumin

active sex steroids

• sex steroid hormone binding globulin

• albumin

the rest

• albumin

hibernations effect on steroid hormones

cholesterol levels increased

progesterone levels increases

sex hormone increased - 22x

17a-hydroxyprogesterone increased in males

free testosterone increased in males

hibernations effect on cardiac output

heart rates drops