Transcript Mutualism: Bathymodioline mussel and

Mutualisms within
Hydrothermal Vents
Erica Stephens
Jessica Hanks
Background Definitions
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Mutualism: an interaction between two species when both benefit and
increase their fitness. Some benefits would be easy transportation for one
organism, and provide chemicals for food supply for another organism.
Symbiosis: the living together of two dissimilar organisms.
Endosymbiotic: symbiosis in which one symbiont lives within the body of
the other.
TEM: transmission electron microscope, uses electrons instead of light.
Intracellular: within cells.
Chemoautotrophic: gets energy from inorganic chemical compounds.
Methanotrophic: use methane to grow and use as their energy source.
Inorganic: not characterized by vital processes
Questions Addressing?
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What are hydrothermal vents and where are they located?
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What chemicals are released in the vents?
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What types of organisms possess mutualistic relationships in hydrothermal
vents?
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How does the bacteria on the organism help them?
What are Hydrothermal Vents?
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Geysers on the seafloor located in the deep ocean.
Are between 1500-4000 meters.
Community includes mussels, crabs, snails, and lobsters.
Formation: the gigantic plates that form the Earth's crust are moving apart
and form cracks in the ocean floor. Seawater goes into these openings and
heats up by the molten rock that lies beneath the Earth's crust. As the water is
heated, it rises and seeks a path back out into the ocean through an opening in
the seafloor, which causes the different types of smokers.
Temperature: 400 degrees Celsius (doesn’t boil because of the pressure.)
Pressure: 300 atmospheres of pressure
Contain primary producers who get energy only from inorganic sources
(chemicals).
Continuously gushes out super-hot, mineral rich water.
http://www.ocean.udel.edu/deepsea/level-2/geology/vents.html
Hydrothermal Vent
http://universe-review.ca/I11-02-hydrothermal.jpg
Types of Chimneys
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Black Smokers: superheated
water caused by volcano, release
sulfur-bearing minerals and iron,
which gives the black smoke it’s
color.
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http://www.csa.com/discoveryguides/vent/review.pdf
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White smokers: have lower
temperatures than the black
smokers, contains calcium and
silicon. They do not contain metals.
http://www.waterencyclopedia.com/ima
ges/wsci_02_img0247.jpg
Mutualism: Bathymodioline mussel
and chemoautotrophic and/or
methanotrophic
A new bathymodioline mussel symbiosis at the Juan de
Fuca hydrothermal vents: McKiness et.al
 This paper explained the new species of mussels found at the Juan de Fuca
hydrothermal vents.
 Juan de Fuca region was once joined with the East
Pacific Rise about 30 MYA
 This was a habitat to dense populations of
Bathymodioline mussels.
 A research cruise on the Endeaver segment of the Ridge
in 1999 yielded the first recorded specimens.
Juan De Fuca Ridge was
linked to East Pacific
Rise approximately
30MYA.
http://www.google.com/imgres?imgurl=http://geomaps.wr.usgs.go
v/socal/geology/geologic_history/images/figure1_03.jpg&imgrefurl
=http://geomaps.wr.usgs.gov/socal/geology/geologic_history/san
_andreas_history.html&h=770&w=572&sz=98&tbnid=cNku9m1aXnv7M::&tbnh=142&tbnw=105&prev=/images%3Fq%3Dea
st%2Bpacific%2Brise&hl=en&usg=__w6ZPomQ1JUzYci18DQjQ
nSeEZMY=&ei=9sTvSffhLJLWlQfRr5k2&sa=X&oi=image_result&
resnum=6&ct=image
 Mytilid mussels hosting bacterial endosymbionts
within their gills are conspicuous members of
communities and in the vents located in the Pacific,
Atlantic, and Indian oceans.
 Bathymodioline mussels are the most common
invertebrates that host chemoautotrophic or
methanotrophic bacteria.
Types of Oxidizing Bacteria
 Chemoautotroph
 synthesize all necessary
organic compounds from
carbon dioxide
 only use inorganic energy
sources (chemicals)
 Evolutionary scientists
believe that the first
organisms to inhabit Earth
were chemoautotrophs that
produced oxygen as a byproduct and later evolved
into both aerobic, animallike organisms and
photosynthetic, plant-like
organisms
 Methanotroph
 able to grow using methane
as their only source of carbon
and energy
 They can grow aerobically or
anaerobically and require
single-carbon compounds to
survive
 Under aerobic conditions,
they combine oxygen and
methane to form
formaldehyde, which is then
incorporated into organic
compounds.
Fig. 1 Bathymodiolus sp. JdF.
Transmission electron
micrograph of a transverse
section of a gill filament.
Bacterial symbionts are
localized at the apical surface
of gill cells (referred to as
bacteriocytes as in other
bathymodioline symbioses)
along with micelle-like
bodies. Due to the poor
condition of the fixed gill
tissue, the exact location of
the symbionts with respect to
the host cell membrane is
unclear. B bacteriocyte, Bl
blood space, S symbiont.
Scale bar 1 lm
http://www.springerlink.com/content/m4606t1kt8314548/fulltext.pdf
 Stable isotope analysis was performed on the mussels
to look for δC13 and δN15.
 It was found that for Carbon13=-26.6% and for
Nitrogen15=+5.19% in comparison to other
Bathymodiodine mussels.
Example of Stable Isotope Analysis
δX- amount of that isotope found compared to the
standard
Standard for Carbon 13: 1.11
Standard for Nitrogen 15: 0.37
δX= [(Rsample)/(Rstandard)-1] X 10³
δX= [(1.08)/(1.11)-1] X 10³
δX=-26.6
Table 1 Stable carbon and nitrogen isotope ratios for bathymodioline mussel
symbioses
Habitat/species
Symbiont
type(s)
d13C (%)
d15N (%)
Location
Bathymodiolus sp.
JdFb
C
-26.6
+5.19
Pacific Ocean
B. thermophilusc, d
C
-30.5 to -37.1
-8.1 to +9.6
Pacific Ocean
B. breviore
C
-30.8 to -35.8
NA
Pacific Ocean
B. aff. breviof
C
-20.0 to -30.8
-2.7 to -7.5
Indian Ocean
B. azoricusg
C, M
-21.3 to -32.6
-10.5 to +0.75
Atlantic Ocean
B. Puteoserpentish
C, M
-32.5 to -37.3
-17.2
Atlantic Ocean
*C chemoautotroph, M methanotroph, NA not available
http://www.springerlink.com/content/m4606t1kt8314548/fulltext.pdf
 On the basis of the 16s rRNA gene sequences, the two
different symbiont types group in separate clades on a
phylogenetic tree according to their metabolism.
 In terms of nutrition:
 Evidence for translocation via host digestion of the
symbionts.
 Evidence in terms of TEM observation of symbionts in
“lysosomal bodies” in the gill epithelials.
 The cytochrome c oxidase subunit I (COI) gene was
used for the host phylogeny (cytochrome c is in the
Electron Transport Chain)
 A ~1,500 bp portion of the 16S rRNA gene was used for
the bacterial symbiont phylogeny.
Fig. 3 Single most parsimonious tree showing phylogenetic relationship
of the Bathymodiolus sp. JdF symbiont with symbiotic and free-living γProteobacteria (based on 1,456 bp of 16S rRNA). Bootstrap values >50%
indicated on tree. Genbank accession numbers are noted on the tree.
Scale bar equals number of changes .
 The Juan de Fuca COI sequence is distinct from the
other mussel COI sequences concluding that this is
probably a new species.
Evolutionary Relationships
 Using COI sequence analyses, it suggests that Bathymodiolus sp. JDF is
distinct from other species of bathymodioline mussels.
 The rarity of this species in the northeast Pacific vents may represent
an initial colonization or an occasional settlement from a population
that is not well adapted to these particular hydrothermal vent
conditions, with potential sources of mussels on the JDFRidge.
 This data supports the presence of chemoautotrophic bacterial
symbionts in a new species of mussel recently discovered on the
Endeaver segment.
Transovarial inheritance of endosymbiotic bacteria in clams
inhabiting deep-sea hydrothermal vents and cold seeps: Cary et. al
 Vesicomyid clams have specialized gill tissue that habitat
endosymbiotic bacteria
 Mechanisms of symbiotic inheritance are likely to be dispersal
strategies.
 16S rRNA-directed oligodeoxynucleotide (CG1255R) for the bacteria
was used to detect and localize in host germ tissues.
 These genes were amplified from the ovarial tissue of three species of
clams:
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Calyptogena magnifica
Calyptogena phaseoliformis
Calyptogena pacifica
Transmission of Endosymbiotic Bacteria
1. Horizontally
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spread of symbionts between contemporary hosts
2. Vertically
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transfer from parent to offspring
3. Environmentally
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reinfection of the new host generation from an environmental
shock of microorganisms
 The researchers collected 3 clam species from the deep-
sea research vessel Alvin from 3 Eastern Pacific sites:
 East Pacific Rise
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C. magnifica
 Monterey Canyon
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C. phaseoliformis
 Axial site on the Juan De Fuca Ridge
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C. pacifica
Juan de Fuca Ridge
Monterey Canyon
East Pacific Rise
Fig 2. Restriction analysis of ovarial
amplification products. Agarose gel
showing amplified ovarial and gill
eubacterial 16S rDNA (lanes A) and
the same product cut with the
restriction endonuclease Hae III
(Promega) (lanes B). Two
independent primer sets were used in
the amplifications: a eubacterial set
and a symbiont-specific set for the
vesicomyid clams (Calyptogena spp.).
All amplifications of ovarial rDNA
had restriction fragments identical to
the symbiont amplification products
out of the gills from respective hosts.
Chemoautotrophic symbiosis:
Mariana Gastropods
 Snails in the western Pacific
oceans contains
endosymbiotic bacteria
within specialized gill cells.
 The gills of these snails
contain sulfur.
 Measurements show that the
snails are exposed to vent
water with temperature of 25
degrees Celsius and
concentrations of hydrogen
sulifde.
http://www.biolbull.org/cgi/reprint/174/3/373
Mariana Gastropods Continued…
 They have chemoautotrophic symbiosis.
 The bacterial endosymbionts are responsible for sulfur
oxidation and generating ATP. This was found out by
looking at a frozen tissue sample at room temperature by
TEM
 By using the TEM, is was found that the bacteria was
packed densely within microvilli-fringed cells.
 The presence of bacteria within the gill cells coupled with
the activities of enzymes that were responsible for fixing
carbon dioxide and taking out energy from sulfide.
 The snails rely on their symbionts for detoxifying the
sulfide.
Refer to Mariana Gastropod overhead
Mutualism: Giant Tube Worms
(riftia pachyptila).
 The tube worms are one the most abundant species located in
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the hydrothermal vents.
They can grow up to 2 meters long.
The tube worms have no mouth, gut, anus, or digestive system.
They house chemoautotrophic bacteria.
Tubeworms get their energy by/from:
 Symbiotic bacteria that live their body cavity called the trophosome.
 Take in chemicals from the vents
 Chemicals get in their blood stream to the bacteria
 The bacteria breaks the chemicals down
Tube Worms Cont…
 The process of breaking down the chemicals take place in
the tube worm called the trophosome.
 The trophosome is packed with blood vessels and
chemosynthetic microbes. Scientists believe that the
hemoglobin that fills the tube worm’s cardiovascular
system gives the tube worms its color and is important to
transport sulfur and oxygen.
 The tube worms must be close enough to the vents to pick
up hydrogen sulfide and be within close proximity of cool
seawater, which contains oxygen
Anatomy of a Tube Worm
http://www.chemosynthesis.co.uk/study/studythirdpic.JPG
Future Research
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Find a better way to collect more information about other organisms besides
the ones mentioned.
Try to locate more hydrothermal vents.
• Try to see if there are similarities or differences between vents in similar
geographic locations.
References
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http://universe-review.ca/I11-02-hydrothermal.jpg
http://www.csa.com/discoveryguides/vent/review.pdf
http://www.springerlink.com/content/m4606t1kt8314548/fulltext.pdf
http://www.ocean.udel.edu/deepsea/level-2/geology/vents.html
http://www.waterencyclopedia.com/images/wsci_02_img0247.jpg
http://www.bionewsonline.com/o/p/shana_k_goffredi_2004_3082.htm
http://www.uga.edu/~sisbl/stable.html
http://www.biolbull.org/cgi/reprint/174/3/373