New Scientist + squid Flashcards
Conversation with squid hubby
nidamental glands
- helps cover eg with jelly coat as it’s laid
Excessory nidamenfal gland - adds additional layer to the outside with bacteria embedded into the jelly
Bacteria in channels in gland - all living separately - prevent contamination of fungal spores on egg
AIN system upstream of Lux system, this turns on then part of the things it turns on is needed to turn on Lux.
If you knock out the AIN system number of v. Fisheri cells that have to be present to turn on luc must be much higher so system turns on much slower
Kent nelson
Gut in his lab discovered quorum sensing
Another grad student in Kenya lab made his whole career on studying quorum sensing (Pete Greenberg)
How was quorum sensing discovered?
When cultures growing they were dim then all of a sudden very bright
Always got bright at same cell concentration
Something the bacteria they were making themselves?
Got rid of bacteria from medium but kept autoinducers and then added bacteria that hadn’t yet been induced. Autounducer still in there so not down to number of bacteria - quorum sensing due to autoinducer produced (homo define lactose)
V
I ding that so interesting I really like genetics
Autoinducer application to pathogens
People studying pathogens discovered toxins were being produced in a same way as autoinducer produced then built up then all of a sudden bam
Read literature on squid and wondered if same mechanism
They found they could turn toxin production on earlier and then found the genes
Evolution
Evolution will take machinery developed to do one task and instead of developing a whole machine it will change it and later it to do another task
Bacteria many homo setup lactome systems are evolutionarily similar - clearly come from the same ancestry
Made it easier to discover once u knew there would be a gene sequence that looked something like this
V. Harveyi
also involved on regulating bioluminescence
Bonnie basler
LuxS - involved in making a toxic product to the cell, when it builds up in t. Environment it is a waste product so cell reacts to presence of waste
Debate: could be natural system of getting rid of toxin OR quorum sensing
Non specific quorum sensing system
- luxS system counted total bacteria - idea of community activity rather than turning on just when one single released one specific thing
Gram positive bacteria
Short peptides instead of hook serine lactomes
Gram positive bacteria
Another system not v. Harvey I
Why is the gene that regulates luciegrase production not permanently on ? Why does it have to be turned on but autoinducer etc?
Accessory genes
Efficient - only transcribe and make proteins under conditions when u need the proteins
Constitutive genes - not regulated genes always on
Inductive genes - only when t he re is a specific reason for them to turn o do they turn on
When v.Fischeri are out in sea winning around they aren’t making light. When they get into the light organ then it’s useful to provide light. Used quorum sensing system to determine difference between swimming around by themselves when they don’t want to make light and now when they are in the light organ and it makes sense to make light.
Can mimic in culture by putting all in jar. Cant maintain in lab conditions because in jar don’t have tissues to be continually roobdibdinh food and removing waste products so eventually accumulation of waste
Why would they have evolved a light producing mechanisms when originally they were all separate ?
What happened back in time- how could they anticipate and prepare this light productions Hagen
You can’t make enough light unless together
But u have to be able to make light to get together like that and stay in the light organ
Theory -
Bioluminescence may have some other metabolic purpose. Uses oxygen. May be a way t he cell gets rid of excess oxygen. Light is a product. Can mutate luciferase enzyme so doesn’t make light but still goes through catalytic process so Indy car yes there IS another purpose of the lux system
No reason to make visible light until something to be able to see it
Until animal evolved with visual systems no reason for bacteria to be making light. Oxygen metabolic system luxR making small light waste product. Luciferase mutated btw just makes heat as a byproduct.
Once visual system evolves and purpose for byproduct of light whole purpose then becomes to make light
X
Don’t say ‘or whatever’
Squid that DOESN’t have luminescence
Rossia Atlantic squid
No light organ
No luck system
Identical to Hawaiian squid
Because bobtail squid are shallow water speeches so muddy camouflage whereas rossia is 100m below so completely dark so no need to worry about camouflage.
Not worth effort for energy of luck system so evolved out Lux system
How does luciferase produce light?
Need to get protein into unstable state so let go to stable state producing light as it does say
Unstable state to get here you oxidise two organic compounds (flavin mononucleotide and aldehyde substrate)
Luciferin - general term for all luciferase substrates
FUNGI BIOLUMINESCENCE
Luciferase, oxygen to oxidise for work , luciferin (general term)
One oxygen oxidise flavin, the other the aldehyde. During oxidation of flavin the flavin is bound to luciferase. Flavin goes into excited state. (Sequential either flavin or aldehyde substrate binds first)
Need both substrates to make light .
If u don’t have the aldehyde the luciferase excited th egos in but production of light still can’t happen. (One of the Ways to make a Livi erase for an experiment that doesn’t produce light)
Firefly luminescence requires ATP to energise the system
Because it requires ATP people have used this as an essay for the amount of ATP in a cell extract
Add extract to luciferin, luciferase and measure amount of light produced (light quantity = amount of ATP)
ATP photometer
What kind of situation might you need to know what ATP conc.
Defects in mitochondria
Metabolic disease - can assay amount of ATP made over period of time can see if they are making full level of ATP etc
Works as a diagnostic for ATP amount ?
Fireflies
Fireflies make luciferase all the time
Never stop glowing
Two routes
Quorum sensing system is a way of turning gene on or off
Epigenetics is also a way of turning genes on or off
Just two different routes of evolution
Epogjetics good at changing gene expression then this change can be inherited by next generation
Quorums ensng works in minutes, shorter timescale
Where exactly does the LuxI-LuxR quorum sensing system occur? Where in the cell does luciferase occur ?
One study - evidence these were in the cell membrane (cytochromes also use oxygen are located in membrane) the luciferase was membrane was membrane associated
He couldn’t show any evidence it was involved in the membrane - other guy from competing lab - rang up - couldn’t show it - massive silence - yay!
Luciferase not bound to the membrane - free in cytoplasm
Will tropical rainforests continue to soak up carbon dioxide from the atmosphere, slowing the pace of climate change?
How do rising temperatures affect the ability of rainforests to lock up carbon dioxide?
Plants and oceans act as carbon sinks
Ocean acidification
Worlds terrestrial plants absorb 12 giga tonnes (a third of global emission from burning fossil fuels) of carbon dioxide each year (for photosynthesis) - prevents accumulation of carbon dioxide and so moderates global warming.
Grassland, bogs, peats forests all lock away carbon.
Evidence suggests tropical rainforests could be the single largest terrestrials carbon sink. - they absorb as much carbon dioxide as boreal forests and mid latitude temperate forests combined.
These terrestrial land carbon sinks are buffering the build up of carbon dioxide in the air but we could be underestimating the climate impacts when these tropical forests decline - temperature could be two degrees warmer by the end of the century than predictions suggest.
Tropical forest decline:
- surveys of carbon uptake in Congo and Amazon
- calculated mass of carbon in each tree, comparing with figures taken decades before in database of Amazonian trees
- both in tact forests absorbing less carbon than previously
- intact forests absorb 30% less carbon than ten years earlier
= even parts of forests not devastated by logging likely to turn into carbon SOURCES rather than sinks (suggests can’t rely on rainforests to keep soaking up carbon dioxide)
Inquilines
Animals that live in the dwellings of other species without affecting them
Termites use cowardice to side step their hosts anger
Some termites can enjoy the shelter of complex nests that insects build without having to contribute to their construction
Inquiline termites are unable to make their own nests and instead inhabit the nest built by another termite, constrictotermes cyphergaster. Unclear how these two live together in peace since termites are typically aggressive.
Many times when two unrelated colonies are placed together in a single space there is a war with a loss on both sides.
Here when the host termites (constrictotermes) and inquiline termites were placed in the same nest despite attacks from the host the inquiline termites did not retaliate.
- hosts bite and spray inquilines with acrid chemicals but targets never responded and instead fled (even though the inquilines do have snapping jaws to protect themselves). At the most the lodging termites squirt faeces at their host.
By preventing an escalation in conflict they may considerably improve their chances of establishing cohabitation with their host termites. (Cycle of revenge is not necessary)
Doesn’t that just result in all the lodging termites dying though??
How does Rory Gibb from UCL suggest disease risk could be reduced ?
If ecosystems are restored
Small fast-lived animals such as rodents, songbirds and bats tend to become more abundant after people move into an area (eg. After deforestation or land clearing)
These carry more diseases than larger long-lived animals.
Short lived animals might harbour more diseases because they must invest more into reproduction at the expense of energy for their immune system defences making them more vulnerable to pathogens.
Issues with tropical rainforest study?
Possible team studied biases sample of forest as tropical rain forests are extremely biased.
244 survey plots only minuscule fraction of forest.
Decline in carbon uptake found on these plots may not be replicated everywhere else.
So still hope more carbon dioxide in atmosphere will HELP rainforests to continue to soak up carbon dioxide dioxide (more ingredient = more growth : concept of carbon fertilisation)
Why might rainforests that haven’t been effected by logging still be soaking up less carbon dioxide than they were 10 years ago?
X
Study on carbon fertilisation
1990
Full size trees in natural conditions
Added co2 enriched air through pipes hanging above plot
Trees grow faster at first and then slowed down when nitrogen in soil became limiting factor.
Similar studies to carbon fertilisation (FACE)
+ issues
Free air CO2 enrichment = FACE
David Lapola - Brazil
Some plants grow better with additional carbon dioxide, others don’t. Suggests that carbon fertilisation may not always just mean the more carbon dioxide the more they grow - carbon fertilisation may not take up slack for extra carbon dioxide in the air.
Issues with experiment -
- conditions highly artificial
- plastic walls block out wind and restrict access to birds, insects and rodents
- plots only large enough for shorter plants - full size trees in different plots could behave differently
What’s going on in the Adriatic Sea?
Common dolphins - Delphinus Delphi’s have been spotted having last seen in large groups in 1940s
Only a few individuals spotted between 1970s and 2000s
Three adults and a calf spotted recently
Not sure if population is growing. In fact fishing which limits their prey has actually increased. Culling campaigns have decrease.
What is the walking catfish?
Species of freshwater air breathing catfish native to South east Asia which can wiggle or ‘walk’ across dry land to find food or suitable environments.
Pond hopping - Florida
