Polar Bear Pathogen Changes

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Questions and Answers

At what age do female polar bears typically start breeding?

2 to 3 years

8 to 9 years

4 to 5 years (correct)

6 to 7 years

Which factor is NOT crucial for a successful denning period for polar bears?

Time for cub maturation

Adequate thermal protection

Balance between cub sizes (correct)

Security from predation

What is the average litter size for polar bears?

Two cubs (correct)

Three cubs

One cub

Four cubs

Which type of seal had the highest consumption frequency in Baffin Bay by polar bears?

Harp seal Signup and view all the answers

What roles do thyroid hormones (THs) play in Arctic animals?

Controlling thermoregulation, metabolism, and reproduction Signup and view all the answers

Which of the following best describes the flora of the Taiga region?

Cold-tolerant evergreen conifers with needle-like leaves Signup and view all the answers

What is the primary difference between freeze-tolerant and freeze-avoiding animals?

Freeze-avoiding animals promote extensive supercooling of their body fluids. Signup and view all the answers

What is a characteristic of Collembola species?

They primarily possess impermeable cuticula and are freeze-avoiders. Signup and view all the answers

Which process describes the net outflux of water vapor due to vapor pressure differences in cryoprotective dehydration?

Outflux of water vapor from the organism Signup and view all the answers

What is thermal hysteresis in the context of ice formation?

The variation between freezing and melting temperatures. Signup and view all the answers

How do ice-binding proteins function to prevent ice formation?

By adsorbing to ice crystal surfaces and hindering water molecule bonding. Signup and view all the answers

The ecotone between the tundra and the forest is commonly referred to as what?

The tree line Signup and view all the answers

Which of the following animals is NOT typically found in the Arctic tundra zone?

Bats Signup and view all the answers

What is the primary cause of increasing pathogen seroprevalence in polar bears?

Warming temperatures Signup and view all the answers

What characteristic is true of Francisella tularensis?

It is a zoonotic gram-negative intracellular bacterium. Signup and view all the answers

In which stage of development is IgM first detected in humans?

During embryonic development in the foetal liver Signup and view all the answers

What is the primary function of IgM antibodies?

As the first response to foreign bodies Signup and view all the answers

Which of the following is NOT a potential effect of climate change on pathogens?

Reduced persistence Signup and view all the answers

Which statement about IgG antibodies is correct?

IgG is formed by plasma B cells fighting infections. Signup and view all the answers

Which ecological area does NOT have natural foci of tularaemia?

Desert ecosystems Signup and view all the answers

What primarily contributes to the ability of Francisella tularensis to persist in the environment?

Survival in cold, moist environments Signup and view all the answers

What percentage of nutritional needs do brown bears obtain from plant matter?

75% Signup and view all the answers

During hibernation, what physiological change occurs in Scandinavian brown bears?

Depressed metabolism Signup and view all the answers

What is the primary function of sex hormone-binding globulin isoform 1 (SHBG)?

Androgen transport Signup and view all the answers

What is metabolomics primarily focused on?

Quantification of metabolites Signup and view all the answers

How long can a fertilized bear egg float freely in the female's uterus before implantation?

Five months Signup and view all the answers

What significant change happens to plasma proteins during hibernation in bears?

Increased innate antimicrobial proteins Signup and view all the answers

What type of proteins are down-regulated during bear hibernation?

Complex multiprotein cascades Signup and view all the answers

What is the general weight range of the brown bear?

100-350 kg Signup and view all the answers

What is the primary function of serum albumin?

Regulating the colloidal osmotic pressure of blood Signup and view all the answers

Which metabolite is critical for energy production by transporting long-chain fatty acids?

Carnitines Signup and view all the answers

Which compound is primarily composed of biological membranes and pulmonary surfactant?

Phosphatidylcholine Signup and view all the answers

What role does carbonic anhydrase 2 play in the body?

Facilitating osteoclast differentiation and bone resorption Signup and view all the answers

Which of the following proteins increases in abundance during hibernation in bears?

Haptoglobin-2 Signup and view all the answers

What function does CAMP primarily perform?

Antibacterial activity Signup and view all the answers

Which of these statements about lysozymes is true?

They enhance the activity of immunity agents. Signup and view all the answers

Which role does sphingomyelin play in cellular functions?

Function in protein sorting and cell membranes Signup and view all the answers

Study Notes

Polar Bear Pathogen Seroprevalence

Warming temperatures, changing precipitation regimes, and Arctic warming twice as fast as the rest of the planet are contributing factors to changes in pathogen prevalence in polar bears.
These changes in the environment can potentially lead to increased pathogen persistence, prevalence, emergence, and transmission.

Francisella tularensis

Francisella tularensis is a zoonotic gram-negative intracellular bacterium commonly found in the Northern hemisphere.
Transmission can occur through direct contact with infected host fluids, vector bites, and ingestion of contaminated food or water.
Francisella tularensis survives for weeks in cold, moist environments, including water, soil, hay, straw, and decaying animal carcasses.
Francisella tularensis has natural foci in Europe that are situated in three large ecological areas: Boreal forest taiga, temperate broadleaf and mixed forest, and temperate grassland and shrubland.

Immune System Cell Biology

The serum, or blood plasma, is an amber-colored, protein-rich liquid containing immunoglobulins, antibody proteins produced by specific immune cells.
Immunoglobulins are found in all jawed vertebrates (gnathostomes), which diverged in evolution from jawless fish (agnathans) approximately 550 million years ago.

IgM (macro-immunoglobulin) Antibodies

IgM antibodies are the first response immunoglobulin on exposure to foreign bodies, offering short-term protection until other antibodies can be produced.
In mammals, B cells (lymphocytes) develop in an ordered manner, starting in the fetal liver during embryonic development (detected at 20 weeks in humans), followed by the bone marrow and peripheral lymphoid tissue in adults.
IgM antibodies are produced by plasma blasts residing in the spleen.

IgG (immunoglobulin G) antibodies

IgG is a monomer with two antigen-binding sites.
IgG is formed by plasma B cells that fight infections from bacteria and viruses.

Artic Tundra Zone

The Arctic tundra zone is characterized by terrestrial animals such as the Arctic fox, hare, ptarmigan, and reindeer, as well as numerous migratory birds.
Decomposed biomass in the tundra zone is stored as methane (CH4) and carbon dioxide (CO2), which acts as a carbon sink.
The ecotone (ecological boundary region) between the tundra and the forest is known as the tree line.

Taiga (Boreal Forest)

The taiga is predominantly composed of cold-tolerant evergreen conifers with needle-like leaves, such as pine, fir, and spruce.
The growing season in the taiga is 130 days.
Fauna found in the taiga includes woodpeckers, hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks, shrews, and bats.

Two Main Strategies for Cold Tolerance in Terrestrial Polar Invertebrates

Freeze-tolerant: These animals tolerate ice formation in extracellular body fluid compartments.
Freeze-avoiding: These species employ physiological mechanisms to supercool body fluids throughout the winter.

Collembola

Collembola species living on the ground surface or in vegetation (epigeic species) have a relatively impermeable cuticle and are typically freeze-avoiders with a high capacity for supercooling.
Species inhabiting deeper soil layers have less cuticular resistance to desiccation and employ a different strategy called cryoprotective dehydration to avoid freezing.

Cryoprotective Dehydration

Cryoprotective dehydration involves water vapor pressure (WVP) between ice in the soil and the supercooled hemolymph, driving a net outflux of water vapor.
The difference in WVP is significant, causing water loss in the organism.
This continues until the pressure of body fluids equals that of the surrounding ice, eliminating internal ice formation.

Thermal Hysteresis (TH)

Thermal hysteresis is the separation between the melting and freezing temperatures.
The temperature at which ice growth begins is known as the hysteresis freezing point.
Thermal hysteresis is believed to result from an adsorption of antifreeze proteins to the crystal surface, similar to how rock salt is used on roads to lower the freezing point.

Ice Binding Proteins (IBPs)

Ice Binding Proteins (IBPs) adsorb to the surfaces of ice crystals, preventing water molecules from joining the ice lattice at the location where the IBP is adsorbed.

Ecophysiology of Polar Bears (Ursus maritimus)

Polar bears evolved from brown bears approximately 500,000 years ago.
Polar bears are K-selected, having a low reproductive rate.
Females mature and breed at 4-5 years, typically giving birth to a litter of one to three cubs, with two cubs being the most common.
Cubs stay with their mother for two years.
The minimum reproductive interval for adult females with a successful litter is 3 years.
Females enter dens between September and December, requiring adequate thermal protection, time for cub maturation, lack of disturbance, and security from predation.
There are regional differences in polar bear diet composition. Polar bears in the Gulf of Boothia consume more ringed seals than those in Baffin Bay and Lancaster Sound. Bearded seal consumption is higher in the Gulf of Boothia and Lancaster Sound. Baffin Bay bears have the highest consumption of harp seals. Beluga whales are the third highest dietary contribution in all three subpopulations.
In general, sex and age class do not significantly affect polar bear diet composition; however, in Baffin Bay, bearded seal consumption is significantly higher in adult females than in adult males and younger age classes, but this is only due to a small number of individuals (3 out of 10).

Thyroid Hormones (TH)

Thyroid hormones (THs) are essential for Arctic animals, playing significant roles in thermoregulation, metabolism, and reproduction.
A study examined seasonal variations in plasma THs in relation to body condition and fasting state, using the plasma urea to creatinine ratio (UCR) as an indicator.

Ecophysiology of Hibernating Bears

Brown bears (Ursus arctos arctos) are the largest terrestrial carnivores in Central Europe.
They hibernate from November to March, sleeping continually without eating, drinking, urinating, or defecating.
Brown bears are polygamous, breeding between May and July.
Fertilized eggs float freely in the female's uterus for up to five months, implanting only at the beginning of hibernation.
Two to three cubs are born in the winter den between January and March.
During hibernation, metabolism is depressed, body temperature decreases, and a suite of cellular and physiological changes occur, allowing the bear to survive periods of food scarcity.
Humans with sedentary lifestyles are prone to heart disease, type 2 diabetes, and kidney disease.

Metabolome, Metabolite, Metabolomics, Proteome, and Proteomics

Metabolome: The total number of metabolites present within an organism, cell, or tissue.
Metabolite: A substance formed in or necessary for metabolism
Metabolomics: The emerging field that systematically quantifies numerous metabolites.
Proteome: The number of proteins present in an organism, cell, or tissue.
Proteomics: The study of the structure and function of proteins, including their interactions within cells.

Differences in Plasma Proteins (Proteome)

Protein concentration is significantly higher in hibernating brown bears compared to the non-hibernating state.
Innate antimicrobial proteins that protect health are significantly increased in hibernation.
The complex multiprotein cascades are down-regulated, while a small number of generalist and principal effector proteins are up-regulated.
Very few intracellular proteins are released from bone and muscle tissues during hibernation.

Examples of 154 Proteins Identified

SHBG: (sex hormone-binding globulin isoform 1) - Functions as an androgen transport protein, involved in receptor-mediated processes. Each dimer binds one molecule of steroid, specific for 5-alpha-dihydrotestosterone, testosterone, and 17-beta-estradiol. Regulates plasma metabolic clearance rate of steroid hormones by controlling their plasma concentration.
CAMP: (cathelicidin antimicrobial peptide) - Binds to bacterial lipopolysaccharides (LPS), has antibacterial activity.
CA2: (carbonic anhydrase 2) - Essential for bone resorption and osteoclast differentiation.
ALB: (serum albumin) - Has good binding capacity for water, Ca2+, Na+, K+, fatty acids, hormones, bilirubin, and drugs. The main function is to regulate blood's colloidal osmotic pressure. A major zinc transporter in plasma, typically binding about 80% of all plasma zinc.

Targeted Mass Spectrometry Identification and Quantification of Metabolome

Targeted metabolomes of phospholipids, hexose sugars, and amine-containing compounds were studied.
Carnitines (ammonium compound) play a critical role in energy production. They help transport long-chain fatty acids into mitochondria for energy production in the form of adenosine triphosphate (ATP).
Phosphatidylcholines are major components of biological membranes and pulmonary surfactant, also essential for transporting triacylglycerols from the liver.
Sphingomyelins (sphingolipid) are involved in regulating endocytosis, receptor-mediated ligand uptake, ion channel and G-protein coupled receptor function, protein sorting, and are components of myelin sheaths and cell membranes.

Summary of Proteome and Metabolome

Albumin, accounting for 50% of plasma protein, was increased to 1.18-fold in hibernating bears, leading to higher plasma viscosity.
Levels of four protective antimicrobial proteins increased during hibernation:
- Haptoglobin-2 (4.7-fold): Antimicrobial, antioxidant, and recycler of iron. It binds harmful hemoglobin (HB) released from red blood cells (RBCs) and protects the kidneys.
- Lysozymes (2.7-fold): Primarily bacteriolytic; those in tissues and body fluids are associated with the monocyte-macrophage system and enhance the activity of immune agents.

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Description

Explore the impact of climate change on pathogen prevalence in polar bears and the specifics of Francisella tularensis, a zoonotic bacterium. This quiz delves into the environmental factors contributing to pathogen transmission and the ecological areas where this bacterium is found in Europe.