Chapter 15
PROTISTA
Domain Eukaria
•This chapter represents a variety of
mostly aquatic autotrophic organisms
•Protists range from single cells to
complex, multicellular organisms
•a mixture of several evolutionary lineages
Learning objectives
•Know the three major evolutionary lineages and
what is included in each lineage
•Chromalveolates (Alveolates, Stramenopiles)
•Excavates (Euglena)
•Plantae (Red algae, Green algae, Charophytes)
•Ecosystem services provided by each group
•Human impacts of each group
Required life cycle: Ulva (demonstrates sporic life
cycle (aka alternation of generations)
Volume 20, Issue 12, Pages 670-676
Keeting et al. 2005 Trends in Ecology & Evolution
THE EUKARYOTIC TREE OF LIFE
Chlorophyll a and b,
you are here
Chlorophyll a and c
GAMETE TYPES
a. Isogametes: gametes identical,
differing only in mating type,
usually a single gene
b. Anisogametes: Gametes are
flagellated and two different
sizes. The smaller is
traditionally referred to as the
male
c. Oogametes: One gamete is
large and non-motile (egg).
The other is small and motile
(sperm)
ECOLOGY OF ALGAE
Ecology
Single celled or few celled algae (Plankton)
• Primary producers on the food chain
• Plankton algae produce 50-70% of the O2 in the
atmosphere.
Nurseries for fisheries
Coral reefs
• Interactions between sponges, red algae and
other organisms form coral reefs.
• Some corals harbor green or yellow-green algae
as endosymbionts
Kelp Forests
Mangrove Swamps harbor and protect small fish and
protect the shores from erosion and storms
Algal blooms
Caused by temperature, salinity and nutrients
A source of drugs
and toxins
Red Tides:
Blooms of
dinoflagellates, diatoms
1. Common along the gulf coast of Florida and the coast of
central California
2. Fluorescent
3. Produce a neurotoxin which kills millions of fish
4. Shellfish are immune to the toxin but people eating the
shellfish can die
5. Tends to occur when warm weather follows a storm
with runoff
The dinoflagellate Karenia brevis
Karenia brevis packs a powerful punch for a tiny organism
The culprit behind Florida’s notorious red tides
Produces a dozen toxins
When coupled with on
onshore breeze, the
organism’s airborn toxins
(brevetoxins) constrict
bronchioles and send
asthmatics and other
people with breathing
difficulties scrambling for
treatment
The dinoflagellate Karenia brevis
Strangely, the organism also produces a toxin antidote called
brevenal, discovered in 2004 at the Center for Marine Sciences at the
University of North Carolina.
This compound binds to a novel receptor in the lung and relaxes
bronchi
It is being evaluated as a
possible treatment for
Cystic Fibrosis and
Ciguatera (see notes)
The ocean has long been
suggested as a potential
source of new drugs – this
is one unexpected
possibility
The dinoflagellate Karenia brevis
Karenia brevis was responsible for the death of Florida’s marine mammals.
150 Manatee died in 1996. 30 died in 2007. There are only 3000 left.
The Manatee drown. The toxin paralyzes them so they cannot surface to get
air. To save them, they must be supported in a sling so that they can breath
and it takes months to recover.
The University of North
Carolina has received a
special “compassionate
use” permit to evaluate
the safety and
effectiveness of brevenal
as an antidote to red tide
poisoning in Manatee
Other algae blooms initiated by phosphate
pollution and/or unusually warm water
1. Blooms get very large.
2. When large blooms begin to decay,
oxygen is removed from the water by
respiring bacteria and organisms die.
Consequences of oxygen poor water
NASA photo of dead
zone off New Orleans
NASA photo of dead
zone off Florida
US DEAD ZONES
Algae may be developed as a fuel
source
Department of Energy announced an investment of $44 million in efforts to commercialize algaebased fuels, and last summer even ExxonMobil Corp. jumped onto the band-pontoon, announcing
a partnership with scientist Craig Venter’s Synthetic Genomics Inc. to develop algae as a fuel
source. Maximum production is currently possible only with supplementary CO2 and fertilizer
which puts this process in the red with respect to energy production.
THE
CHROMALVEOLATES
[Alveolates/Stramenopiles]
Chlorophyll a and c
Volume 20, Issue 12, Pages 670-676
Keeting et al. 2005 Trends in Ecology & Evolution
THE EUKARYOTIC TREE OF LIFE
Chlorophyll a and c
alveolates
PHYLUM
DINOPHYTA
dinoflagellates
Fossil history
ERAS (YEARS SINCE START)
PERIODS
Cenozoic
Quaternary
Holocene (present)
Pleistocene
Tertiary
Pliocene
Miocene
Oligocene
Eocene
Paleocene
(65,000,000)
Mesozoic
(225,000,000)
Paleozoic
(570,000,000)
TIME PERIOD IN
MILLIONS OF YEARS
Last 10,000 years
.01-2
2-6
6-23
23-35
35-54
54-65
Cretaceous-Paleocene discontinuity
Cretaceous
Jurassic
Triassic
65-135
135-197
197-225
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
225-280
280-345
345-405
405-425
425-500
500-570
1200-1400
Precambrian
(Origin of earth, 4.5 billion years)
Most invertebrate
phyla present
570-4500
Diatom fossils
Green algae
photosynthetic
eukaryotes
Photosynthetic prokaryotes
Pigments:
• chlorophylls a and c
• peridinin and other carotenoids
Photosynthetic reserve (storage of photosynthetic
product)=starch
Cell Wall composition: armored plates of cellulose
Move by: flagella (2 tinsel) but some have no flagella
Habitat: Marine, freshwater and can be airborne
PFIESTERIA
A fresh-water dinoflagelate
Pfiesteria piscicida
•A tiny killer that shoots a paralyzing toxin into its
victim, attaches a trumpet-like tongue and sucks
holes in its victim’s flesh
•Pfiesteria produces an airborn neurotoxin
•People exposed to the toxin loose ability to carry out
simple thought processes, (e.g., dialing a phone) and
experience a sense of disorientation
Lives in fresh water and
blooms are caused by
runoff from farms
containing nutrients and
animal wastes
Mergers and acquisitions: malaria and the
great chloroplast heist
The malaria parasite is
descended from algae. It
carries the remnants of a
chloroplast. Closest
living relative is the
dinoflagelate, Chromera,
which is a coral
symbiont
Chromera
Chromalveolates
Stramenopiles
Aka heterokonts
http://en.wikipedia.org/wiki/Heterokont
Volume 20, Issue 12, Pages 670-676
Keeting et al. 2005 Trends in Ecology & Evolution
THE EUKARYOTIC TREE OF LIFE
Chlorophyll a and c
Stramenopiles
(Heterokonts)
• 100,000 known species, most
of them diatoms
• Chloroplasts surrounded by
four membranes. Chloroplasts
were obtained from the
reduction of a symbiotic red
algal eukaryote.
• Oomycetes are related to these
algae, rather than fungi as
previously thought but lack
chloroplasts
Many Straminopile gametes have two kinds of flagella
(heterokonts): One flagellum has tubular hairs on the
flagella (tinsil). This motile reproductive structure is
common to many of this group but some members of the
Straminopiles seem to have lost flagella).
Anterior
Tinsel Flagellum
Whiplash Flagellum
Posterior
Stramenopiles
PHYLUM
BACILLARIOPHYTA
DIATOMS
Volume 20, Issue 12, Pages 670-676
Keeting et al. 2005 Trends in Ecology & Evolution
THE EUKARYOTIC TREE OF LIFE
The various forms of diatoms
Pigments:
• chlorophylls a and c
• fucoxanthin and carotenoids
Photosynthetic reserve (storage of photosynthetic product)=
Chrysolaminarin
Cell Wall composition: cellulose wall or silica shell
Move by: variable
Habitat: Marine, freshwater and can be airborne
Each half is always the
larger part of the
daughter cell, the new
frustule fits within it
→Sexual
reproduction
Diatoms can also
reproduce sexually,
undergoing meiosis
and producing a
flagellated sperm
which fertilizes and
egg nucleus
DiatomAlgal blooms
Domoic acid is a naturally
occurring toxin produced by
microscopic algae, specifically the
diatom Pseudo-nitzschia.
For the first time, scientists have identified all links in the food chain that tie toxic algal
blooms to the deaths of marine mammals. In so doing, they determined the California
sea lions were poisoned with domoic acid, a neuro-toxin generated by various marine
algae that also affect birds, sea otters and even humans. Toxic algae can bloom in many
conditions and affect many levels of the marine food chain. The California sea lions ate
large quantities of anchovies and sardines that had fed on the algae.
Neurological symptoms can last for years.
Diatomaceous earth is formed from diatoms
Diatomaceous earth is harvested and used -
a. As a polishing agent in metal polish, toothpaste
b. For reflective highway signs
c. For clarifying bear or wine (silica shells absorb
materials including foods)
d. For swimming pool filters
e. Much of the fossil oil comes from diatom deposits
and diatoms are a useful indicator of oil deposits
in cores
•Diatomaceous earth
Stramenopiles
PHYLUM
CRYPTOPHYTA
Volume 20, Issue 12, Pages 670-676
Keeting et al. 2005 Trends in Ecology & Evolution
THE EUKARYOTIC TREE OF LIFE
The cryptomonads are single celled, have flagella
and are very tiny (from kryptos = hidden)
They are an important part of the food chain
because they are a good source of fatty acids.
Some are photosynthetic - some are heterotrophs
that eat other plankton.
This group offers the
best evidence that
photosynthetic
organisms can be
engulfed and enslaved.
The chloroplast of the
cryptomonads came
from a red algae and
remnants of the
nucleus of the red
algae can be found
microscopically
END