Navigation Links
Giant deep-sea tubeworm's meal ticket comes in as a skin infection

Giant tubeworms found near hydrothermal ventsmore than a mile below the ocean surface donot bother to eat: lacking mouth and stomach,they stand rooted to one spot. Fornourishment, they rely completely onsymbiotic bacteria that live within theirbodies to metabolize the sulphurous volcanicsoup in which they both thrive.

But the microscopic larvae of these giantsare born bacteria-free, with a completedigestive system. Juveniles swim, hunt, andeat before permanently settling down andtaking up with their microbial partners. Nowthe idea that the larvae acquire theirsymbionts by eating them has beenoverturned. By collecting the giant worms'tiny spawn from traps laid on the oceanfloor, oceanographers have shown that thesulfur-eating bacteria infect the larvaethrough their skin.

Andrea Nussbaumer and Monika Bright of theUniversity of Vienna, and Charles Fisher,professor of biology at Penn State, reporttheir findings this week in the Britishjournal Nature.

Previous groups had shown that, after a larvaquits swimming and attaches itself to thebottom of the ocean near a volcanic vent, itsmouth disappears and its stomach shrinksaway, even as it grows a specialized organcalled the trophosome that houses thesymbiotic bacteria it collects. "It is anabsolutely obligate symbiosis for the worm,"Fisher explains. "If the larvae do not getthe right symbiont, they die."

The prevailing hypothesis was that theappropriate bacteria were gathered into thestomach during feeding, somehow escapeddigestion, and by remaining in the stomachcaused it to undergo metamorphosis into thetrophosome.

But those conclusions were based on a verysmall set of observations, due to the extremedifficulty of obtaining the tubeworm's larvaland juvenile stages. The only way to collectthese delicate organisms is directly from theocean floor, at 2500 meters depth, in thedeep sea vehicle Alvin. Bright invented"tubeworm artificial settlement cubes," or"baby traps" as the team calls t hem, tocollect young, just-settled larvae andjuveniles. They left the traps at the bottomnear an active hydrothermal vent and returnedthe next season to collect them, bring themback to land-based laboratories, and analyzethem carefully using molecular techniques andfluorescence- and electron microscopy.

By a painstaking reconstruction of electronmicrographs of thin slices of larvae andjuvenile worms, the team showed that thesymbionts do not enter through the mouth, butthrough the skin, in a process akin toinfection by pathogenic bacteria. Thesebacterial partners then crawl inward, throughvarious larval tissues, not to the stomachbut to an adjacent, "mesodermal" tissue. Upontheir arrival, the bacteria appear to inducethe immature mesodermal tissue todifferentiate and form the trophosome, wherethey proliferate and provide sustenance tothe growing worm indefinitely. In return thebacteria get a safe habitat and a reliablesource of food.

"The symbiont, and only the symbiont, iscapable of invading the skin of the tubewormlarvae. It migrates through several layers oftissue towards the interior of the host, andinto the future trophosome," Brightexplains. "Once the trophosome isestablished, infection ceases, and no furtherinfection appears to be possible at laterstages."

The researchers found that after thetrophosome is established, further infectionappears to be prevented, in part by a wave ofprogrammed cell death in tissues wherestraggling bacteria remain.

"Biologists are realizing that symbiosis isnot an oddity in nature, but rather thenorm," Fisher says. "Most -- if not all --animals and plants exist in symbiosis withsome forms of microbes. We currentlyunderstand the early stages of symbiontacquisition for only a very few of themultitudes of symbioses. Since symbiosis isso widespread, understanding the mechanismsof symbiont acquisition is a first orderquestion for modern biologists."

"In this tubeworm," Bright adds, "thesymbiont ac quisition process resembles theinfection processes of pathogenic bacteria.""It may be," Fisher says, "that understandingthe early stages of symbiotic interactionswill help us to understand the early stagesof host-pathogen interactions, andvice-versa."


'"/>

Source:Penn State


Related biology news :

1. A giant among minnows: Giant danio can keep growing
2. Giant insects might reign if only there was more oxygen in the air
3. Climatologists discover deep-sea secret
4. Sinkers provide missing piece in deep-sea puzzle
5. Some like it hot: Worms at deep-sea vents favor a fiery 45-55°C
6. Drug discovery team to explore newly discovered deep-sea reefs
7. Extraordinary life found around deep-sea gas seeps
8. Ocean seep mollusks may share evolutionary history with other deep-sea creatures
9. Long-lived deep-sea fishes imperiled by technology, overfishing
10. Study warns deep-sea mining may pose serious threat to fragile marine ecosystems
11. Growth in the sea comes down to a struggle for iron
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:11/14/2018)... ... ... In recognition of World Diabetes Day, Diopsys is lending its voice to ... reaching out to help educate patients and the healthcare community about the clinical and ... people with the disease. , The American Diabetes Association (ADA) released new research ...
(Date:11/13/2018)... ... November 13, 2018 , ... Fluence Bioengineering today ... applications. VYPR 2 is well suited for sole-source and supplemental lighting applications addressing ... , “As an all-purpose light which can be adapted to virtually any ...
(Date:11/13/2018)... , ... November 12, 2018 , ... ... interactive educational virtual events and webinars, will be hosting its 9th Annual ... featuring new technologies and treatments available, and updates in regulatory processes to ensure ...
Breaking Biology News(10 mins):
(Date:11/13/2018)... ... November 13, 2018 , ... , Park Systems, world leader in ... the increasingly growing demand for AFM technology in China, Park Systems has decided to ... an office in Beijing equipped with Park AFM. , The Grand Opening of the ...
(Date:11/9/2018)... ... November 08, 2018 , ... IC ... a machine-learning powered approach to increasing recovery rates by creating a comprehensive contact ... Collections (AIC) product developed by NLP Logix, a Jacksonville, Florida-based AI solutions company, ...
(Date:11/6/2018)... ... November 06, 2018 , ... Crucial Data Solutions announces the ... management. TrialKit ™, an eClinical platform, has incorporated Apple’s biometric technologies for ... sign in to the app via facial recognition or fingerprint recognition. , ...
(Date:11/5/2018)... , ... November 05, 2018 , ... ... access to 2Blades’ Transcription Activator Like (TAL) effector code technology for applications in ... uses of the technology in plants. Since its discovery in 2009, the efficacy of ...
Breaking Biology Technology: