bis2c: lecture 29: triploblasts: protostomes: ecdysozoans i
TRANSCRIPT
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Lecture 29:
Triploblasts: Protostomes:
Ecdysozoans I
BIS 002C Biodiversity & the Tree of Life
Spring 2016
Prof. Jonathan Eisen1
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Where we are going and where we have been…
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•Previous lecture: •28: Triploblasts: Protostomes:
Lophotrochozonas
•Current Lecture: •29: Triploblasts: Protostomes:
Ecdysozoans I
•Next Lecture: •30: Triploblasts: Protostomes:
Ecdysozoans II
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity Topics
• Major Groups
• Diversity within Groups
• Key Features of Groups !Body Plans, Forms and Symmetry !Reproduction and Life Cycles !Mobility !Feeding
• Examples
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoa
• Key Features of Ecdysozoa !Molting
• Major Groups
• Key Features of Key Groups
• Focus on !Nematodes !Tardigrades
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
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Diploblasts
Triploblasts
Monoblasts
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
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Triploblasts
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoans
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoan Feature #1: Cuticle and Molting
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoan Feature #1: Cuticle and Molting
• Ecdysozoans have a cuticle, secreted by the epidermis.
• For animal to grow, cuticle must be shed, or molted, and replaced with a larger one (a process known as ecdysis).
• Molting evolved ~500 mya, apparently only once. All ecdysozoans have a single common ancestor.
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoan Feature #1: Cuticle and Molting
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoan Feature #1: Cuticle and Molting
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• In some wormlike ecdysozoans, the cuticle is thin and flexible.
• A thin cuticle allows gas and water exchange but restricts animal to moist habitats.
• In arthropods, the cuticle is an exoskeleton, thickened by proteins and chitin, a waterproof polysaccharide.
• The exoskeleton restricts movement and gas exchange; new mechanisms for these functions evolved.
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Ecdysozoan Feature #1: Cuticle and Molting
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
A Few Summaries for Your Enjoyment …
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoans
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Ecdysozoans
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Wormlike Marine Ecdysozoans
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Priapulids Kinorhynch Loriciferan
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Wormlike Marine Ecdysozoans
• Priapulids: !Unsegmented, three-part body plan !Burrow in soft sediments !Capture prey with a toothed, muscular pharynx that is
everted through the mouth
• Kinorhynchs: !Microscopic !Body has 13 segments, with separate cuticular plates that
are molted !Feed by ingesting sediments through their retractable
proboscis
• Loriciferans: !Minute !Not discovered until 1983 !Body is covered by six plates (lorica = “corset”)
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoans
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Horsehair Worm Larvae Are Parasitic
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Horsehair Worms
• Horsehair worms: very thin; up to a meter in length; most are freshwater.
• Larvae are internal parasites of insects and crayfish.
• Adult has no mouth and a reduced gut. Some may feed only as larvae; others continue to grow and molt, and may be absorbing nutrients from the environment.
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Horsehair Worms
• Horsehair worms: very thin; up to a meter in length; most are freshwater.
• Larvae are internal parasites of insects and crayfish.
• Adult has no mouth and a reduced gut. Some may feed only as larvae; others continue to grow and molt, and may be absorbing nutrients from the environment.
• WHATEVER YOU DO - DO NOT - DO NOT GOOGLE “HORSEHAIR WORM VIDEO”
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Not Just for Your Enjoyment …
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoans
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoans
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Clicker
Which of the following would make the most sense to add to the UC Davis Department of Nematology and Entomology?
A: Plants
B: Vertebrates
C: Echinoderms D. Annelids
E. Cnidarians28
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Clicker
Which of the following would make the most sense to add to the UC Davis Department of Nematology and Entomology?
A: Plants
B: Vertebrates
C: Echinoderms D. Annelids
E. Cnidarians29
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Ecdysozoans
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Nematodes (roundworms)
!32Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Name from Greek: nematos (thread) eidos (form)
Nematodes (roundworms)
!33Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Thick, multilayered cuticle
Nematodes (roundworms)
!34Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Pharynx, a muscular organ at the anterior end, moves materials through the gut.
Nematodes (roundworms)
!35Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Gas and nutrient exchange occurs through the cuticle and the gut wall, which is only one cell thick.
Nematodes (roundworms)
!36Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Mouthparts modified for specialized tasks
Nematodes (roundworms)
!37Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Brain
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Extremely abundant and universally distributed.
• >25,000 species described.
• Includes scavengers, parasites, predators
• Many are microscopic; the largest is 9 meters long—a parasite in placentas of female sperm whales.
• Reduced musculature and digestive system (pseudocoelom)
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Nematode Features
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Caenorhabitis elegans is used as a model organism in genetics and developmental biology research.
• It is easy to cultivate, matures in three days, and has a fixed number of body cells.
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Nematode Example: C. elegans
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Clicker
From an evolutionary point of view, which of the following is the best candidate for a model organism to compare with humans
A. C. elegans (Nematode)
B. Fruit fly (Arthropod)
C. Giant squid (Cephalopod) D. Earthworm (Annelid)
E. All are equally good
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Clicker
From an evolutionary point of view, which of the following is the best candidate for a model organism to compare with humans
A. C. elegans (Nematode)
B. Fruit fly (Arthropod)
C. Giant squid (Cephalopod) D. Earthworm (Annelid)
E. All are equally good
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Animal Diversity
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Triploblasts
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• Whatever you do DO NOT - I REPEAT DO NOT- GOOGLE - GIANT NEMATODE SLITHERING DEAD SPIDER
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Root-Knot Nematodes
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• Meloidogynes nematodes infect root systems of plants • The nematodes cause galls where juvenile worms develop
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• WARNING THE NEXT FEW SLIDES COULD GROSS PEOPLE OUT
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Nematode Example: Filarial Diseases
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• Caused by several different parasitic nematodes and transmitted by mosquitoes • Infect lymph nodes, which can then get blocked. This leads to edema (swelling) and other problems.
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Nematode Example: Filarial Diseases
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• Caused by several different parasitic nematodes and transmitted by mosquitoes • Infect lymph nodes, which can then get blocked. This leads to edema (swelling) and other problems.
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Nematode Example: Filarial Diseases
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• Caused by several different parasitic nematodes and transmitted by mosquitoes • Infect lymph nodes, which can then get blocked. This leads to edema (swelling) and other problems.
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Nematode Example: Filarial Diseases
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• Caused by several different parasitic nematodes and transmitted by mosquitoes • Infect lymph nodes, which can then get blocked. This leads to edema (swelling) and other problems.
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Nematode Example: Filarial Diseases
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HOW CAN WE TREAT THESE DISEASES?
Opisthokonts
!49Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Opisthokonts
Fung
i
Ani
mal
s
Cho
anof
lage
llate
s
Shared derived traits of clade?
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Anti fungal drugs
50http://www.slideshare.net/drjankiborkar/antifungals-14155209
!51
Fila
ster
ea
Icht
hyos
pore
a
Mic
rosp
orid
i
Chy
trids
Zygo
spor
e
Arb
uscu
lar
Sac
fung
i
Clu
b fu
ngi
Dik
It’s Always More Complicated III
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
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Fila
ster
ea
Icht
hyos
pore
a
Mic
rosp
orid
i
Chy
trids
Zygo
spor
e
Arb
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lar
Sac
fung
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Clu
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Dik
Humans & Nematodes Much Closer than Humans and Fungi
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
HumansNematodes
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http://www.worldbank.org/en/news/video/2014/06/30/treating-river-blindness-and-other-neglected-tropical-diseases
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
2015 Nobel Prize in Medicine
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
But …
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Wolbachia
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http://www.theatlantic.com/science/archive/2015/10/ivermectin-nobel-drugs-elephantiasis-filariasis-nematodes-wolbachia/409306/
Ed Yong
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016 57
The avermectins that Campbell and Ōmura discovered, and especially their most potent member ivermectin, can control the symptoms of these diseases by killing the larval nematodes. But they aren’t cures, because they don’t damage the astonishingly sturdy adults. And since these worms can live for a decade, and can release thousands of new larvae every day, their hosts must resign themselves to years of regular treatments.http://www.theatlantic.com/science/archive/2015/10/ivermectin-nobel-drugs-elephantiasis-filariasis-nematodes-wolbachia/409306/
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Filarial Nematodes Permanently House Wolbachia
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016 59
And unfortunately, this means that killing the worms would make everything much worse, because they’d release all their Wolbachia in their death throes. “You get exploding nodules, and scrotal inflammation,” he told me. “You don’t want that. You want to kill the worms slowly, and it’s hard to think how you’d do that with an anti-nematode drug.”
Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
What Would You Use to Kill Wolbachia?
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Ecdysozoa
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Tardigrades
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Tardigrades (aka water bears)
• Fleshy, unjointed legs
• Use a fluid-filled body cavity as a hydrostatic skeleton
• Extremely small
• No circulatory or gas exchange systems
• Live in marine sands and on water films on plants
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016 64
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
• When water films dry up, tardigrades lose water and shrink to form a dormant state that can last at least a decade.
• Tardigrades have been found at densities as high as 2 million / m^2 of moss.
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Tardigrades
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Velvet worm
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Onychophorans (velvet worms)
• Live in leaf litter in the humid tropics
• Thin, flexible cuticle
• Use fluid-filled body cavity as a hydrostatic skeleton
• May look similar to arthropod ancestors
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Slides by Jonathan Eisen for BIS2C at UC Davis Spring 2016
Figure 32.19 A Trilobite Fossil
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