Global amphibian declines Flashcards
how many species of amphibians
5,700
since 1980 how many amphibian species have experienced rapid decline
1/3rd
nearly 2,000 species
–> that have gone completely extinct
–>gone extinct in the wild but have captive breeding programs at zoos
–> have potentially gone extinct
massive extinctions being called
the most spectacular loss of vertebrate biodiversity in recorded history
name a disease which is causing an amphibian scourge
Batrachochytrium dendrobatidis
Bd is a
chytrid fungus
- aquatic and motile
- causes severe disease in amphibians
over the past 30 years
lots of research has poured into research regarding the amphibian scourge
in 1997 some of that research paid off
with the very important discovery of the chytrid fungus, Bd
Chytrid fungi are
heterotrophs
heterotrophs
sequester carbon from other life sources, not the sun–> saphorhphytes and parasites
Bd life cycle
1) bd starts as a tiny zoospore that swims in open water
2) when it find suitable host, it burrow deep into the skin and develops into a thallus
3) thallus matures into a sporangium- egg-sac
4) the sporangium grow until they burst open and new zoospores are released
5) these zoospores swim around and find new hosts, or re-infect the same host and cause chronic disease
Bd life cycle take
4-5 days
Bd causes a chronic skin disease called
chytridiomycosis- colonised keratinised skin layer
hyperplasia and hyperkeratosis causes
disrupted electorylye balance
chyridiomycosis leads to
cardiac arrest and death due to disrupted electolye dance
amphibian ski is
tremendously improtnant
amphibians use their skin to
drink- rarely drink through mouths- especially when underwater
chytrdiomycosis
chronic infection causes skin to thicken and scar- dehydrating the amphibian leading to their death
Bd infected populations can
crash within just a few short months- before anyone knowns the population has become infected
chytrdiomycosis is not
easy to diagnose due to no hallmark symptoms
two main methods for diagnosing Bd infection are quantitative …
qPCR and histology
qPCR requires
an amphibian wiped down with a swab and that swab being sent away to a diagnostic lab
–> CANNOT BE DONE ONSITE
downside to qPCR
- cannot be done onsite
- need trained staff
- expensive equipment (>£10,000)
- expensive reagents
£40 per test
- by the time you have the result, frog has been set free- cannot reat
alternative to qPCR
histological examinaiiton
histological examination
microscopic examination of skin
downside of histological examination
requires extensive knowledge of infected and uninfected skin morphologies and requires you take an actual skin sample from the frog
- usually have to take from dead amphibian
its providing
extremely difficult to monitor BD infections in real time
which monoclonal antibody has been chosen to act as an immunotherapy for Bd
mAb 5CO4
benefits of mAb5CO4
- grows quickly
- produces lots of antibody
- very robust
- does not require supplementation to grow well
next it became important to know where the antigen(glycoprotein/ carbohydrate) to mAb 5C4 was located.. inside? outside? Zoospores? Sporangium? how did they do this
using immunofluorescence- found to be on outside of spores
name a better way to diagnose Bd- to help tracking and prevention of disease
lateral flow assay
what must a test be to track Bd
- it must be inexpensive and widely used
- rapid
- immediate results
- easy to use
how to LFA work
a small amount of liquid is placed on the sample pad and capillary action pulls the fluid across the membrane where it encounters:
- a test line- this only appears if you are infected
- a control line: always appears- ensures test ran completion
which antibodies are used in LFA
labeled and immobilised 5C4 Ab
if the antigen is present in the sample (e.g. the frog has the disease)
then the antigens bind to the labeled (gold) 5C4Ab and then binds to the immobilised 5C4 Ab antibody (test line)
if the antigen is not present the labeled 5C4 Ab will bind to
the control line label antigens
OID can be used to study
antibody-antigen interactions and to determine whether proteins share antigenic determinants
IF and EM-gold can be used to
visualise the extracellular and intracellular location of antigens or antibodies in the cell
western blotting can be used to
identify individual antigens in a mixture of proteins
Lateral flow assays are
semi-quantitiaitev point of care tests
