Download Examples of Red Algae

Origin of the Taxa
Examples of Protista
Topic 6 BOT 3015
Bill Outlaw, Instructor
Lecture Outline (a)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Lecture Outline (a)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Chronology (a-1)
BYBP
EVENT
4.5
Earth Formed
(Universe ~13 billion years old; Solar System ~ 10 billion years old.)
4.5-3.8
Earth Inhospitable
(Asteroid impacts/heat would have destroyed any organisms.)
3.5-3.8
Appearance of the First Organisms
(Non-photosynthetic prokaryotes; insignificant atmospheric O2.)
3.5
Appearance of Oxygenic Photoautrophs (debatable)
(Oxygenic photosynthesis resulted in atmospheric O2 increase.)
2
Rise of O2-rich Atmosphere; Evolution of O2-respiring
Organisms
(10-15% O2 only at this time; reached present levels by 0.8 BYBP)
Chronology (a-2)
BYBP
EVENT
4.5
Earth Formed
(Universe ~13 billion years old; Solar System ~ 10 billion years old.)
4.5-3.8
Earth Inhospitable
(Asteroid impacts/heat would have destroyed any organisms.)
3.5-3.8
Appearance of the First Organisms
(Non-photosynthetic prokaryotes; insignificant atmospheric O2.)
3.5
Appearance of Oxygenic Photoautrophs (debatable)
(Oxygenic photosynthesis resulted in atmospheric O2 increase.)
2
Rise of O2-rich Atmosphere; Evolution of O2-respiring
Organisms
(10-15% O2 only at this time; reached present levels by 0.8 BYBP)
Chronology (a-3)
BYBP
EVENT
4.5
Earth Formed
(Universe ~13 billion years old; Solar System ~ 10 billion years old.)
4.5-3.8
Earth Inhospitable
(Asteroid impacts/heat would have destroyed any organisms.)
3.5-3.8
Appearance of the First Organisms
(Non-photosynthetic prokaryotes; insignificant atmospheric O2.)
3.5
Appearance of Oxygenic Photoautrophs (debatable)
(Oxygenic photosynthesis resulted in atmospheric O2 increase.)
2
Rise of O2-rich Atmosphere; Evolution of O2-respiring
Organisms
(10-15% O2 only at this time; reached present levels by 0.8 BYBP)
Chronology (a-4)
BYBP
EVENT
4.5
Earth Formed
(Universe ~13 billion years old; Solar System ~ 10 billion years old.)
4.5-3.8
Earth Inhospitable
(Asteroid impacts/heat would have destroyed any organisms.)
3.5-3.8
Appearance of the First Organisms
(Non-photosynthetic prokaryotes; insignificant atmospheric O2.)
3.5
Appearance of Oxygenic Photoautrophs (debatable)
(Oxygenic photosynthesis resulted in atmospheric O2 increase.)
2
Rise of O2-rich Atmosphere; Evolution of O2-respiring
Organisms
(10-15% O2 only at this time; reached present levels by 0.8 BYBP)
Chronology (a-5)
BYBP
EVENT
4.5
Earth Formed
(Universe ~13 billion years old; Solar System ~ 10 billion years old.)
4.5-3.8
Earth Inhospitable
(Asteroid impacts/heat would have destroyed any organisms.)
3.5-3.8
Appearance of the First Organisms
(Non-photosynthetic prokaryotes; insignificant atmospheric O2.)
3.5
Appearance of Oxygenic Photoautrophs (debatable)
(Oxygenic photosynthesis resulted in atmospheric O2 increase.)
2
Rise of O2-rich Atmosphere; Evolution of O2-respiring
Organisms
(10-15% O2 only at this time; reached present levels by 0.8 BYBP)
Chronology (b-1)
BYBP
EVENT
2.2
Appearance of Eukaryotes
0.9-1.3
Appearance of Sex
0.7-1.5
Appearance of Multicellular Organisms
0.5-1
Appearance of Large Eukaryotes
0.5
0.14
Appearance of Plants
([CO2] ~ 15x present.)
Appearance of Seed Plants
([CO2] ~ present, result of photosynthesis.)
Appearance of Angiosperms
0.003
Appearance of Humans
0.3
Chronology (b-2)
BYBP
EVENT
2.2
Appearance of Eukaryotes
0.9-1.3
Appearance of Sex
0.7-1.5
Appearance of Multicellular Organisms
0.5-1
Appearance of Large Eukaryotes
0.5
0.14
Appearance of Plants
([CO2] ~ 15x present.)
Appearance of Seed Plants
([CO2] ~ present, result of photosynthesis.)
Appearance of Angiosperms
0.003
Appearance of Humans
0.3
Chronology (b-3)
BYBP
EVENT
2.2
Appearance of Eukaryotes
0.9-1.3
Appearance of Sex
0.7-1.5
Appearance of Multicellular Organisms
0.5-1
Appearance of Large Eukaryotes
0.5
0.14
Appearance of Plants
([CO2] ~ 15x present.)
Appearance of Seed Plants
([CO2] ~ present, result of photosynthesis.)
Appearance of Angiosperms
0.003
Appearance of Humans
0.3
Chronology (b-4)
BYBP
EVENT
2.2
Appearance of Eukaryotes
0.9-1.3
Appearance of Sex
0.7-1.5
Appearance of Multicellular Organisms
0.5-1
Appearance of Large Eukaryotes
0.5
0.14
Appearance of Plants
([CO2] ~ 15x present.)
Appearance of Seed Plants
([CO2] ~ present, result of photosynthesis.)
Appearance of Angiosperms
0.003
Appearance of Humans
0.3
Chronology (b-5)
BYBP
EVENT
2.2
Appearance of Eukaryotes
0.9-1.3
Appearance of Sex
0.7-1.5
Appearance of Multicellular Organisms
0.5-1
Appearance of Large Eukaryotes
0.5
0.14
Appearance of Plants
([CO2] ~ 15x present.)
Appearance of Seed Plants
([CO2] ~ present, result of photosynthesis.)
Appearance of Angiosperms
0.003
Appearance of Humans
0.3
Chronology (b-6)
BYBP
EVENT
2.2
Appearance of Eukaryotes
0.9-1.3
Appearance of Sex
0.7-1.5
Appearance of Multicellular Organisms
0.5-1
Appearance of Large Eukaryotes
0.5
0.14
Appearance of Plants
([CO2] ~ 15x present.)
Appearance of Seed Plants
([CO2] ~ present, result of photosynthesis.)
Appearance of Angiosperms
0.003
Appearance of Humans
0.3
Chronology (b-7)
BYBP
EVENT
2.2
Appearance of Eukaryotes
0.9-1.3
Appearance of Sex
0.7-1.5
Appearance of Multicellular Organisms
0.5-1
Appearance of Large Eukaryotes
0.5
0.14
Appearance of Plants
([CO2] ~ 15x present.)
Appearance of Seed Plants
([CO2] ~ present, result of photosynthesis.)
Appearance of Angiosperms
0.003
Appearance of Humans
0.3
Chronology (b-8)
BYBP
EVENT
2.2
Appearance of Eukaryotes
0.9-1.3
Appearance of Sex
0.7-1.5
Appearance of Multicellular Organisms
0.5-1
Appearance of Large Eukaryotes
0.5
0.14
Appearance of Plants
([CO2] ~ 15x present.)
Appearance of Seed Plants
([CO2] ~ present, result of photosynthesis.)
Appearance of Angiosperms
0.003
Appearance of Humans
0.3
Schopf and His Fossils
Microfossils (~3.5 BYBP, Australia)
Lecture Outline (b)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Origin of the Major Groups (a)
Bacteria, Archaea, Eukarya
1. An unknown protobiont
evolved two lineages—one
leading to Bacteria and a second
leading to the progenitor of
Archaea and Eukarya. Or, . . .
Credit: Andrew White, Staffordshire University, UK
Origin of the Major Groups (b-1)
Bacteria, Archaea, Eukarya
?
Bacterium
2. Bacteria and Archaea arose
(either independently or from a
single unknown ancestor). A
single Bacterial cell fused with a
single Archaeal cell, creating the
proto-eukaryal cell.
Archaeaon
Whole-cell Fusion
Proto-eukaryal cell
idea from Lynn Margulis
Origin of the Major Groups (b-2)
Bacteria, Archaea, Eukarya
Bacterium
Archaeaon
Whole-cell Fusion
**Membrane lipids
**Many/most cytosolic
metabolic pathways (e.g.
glycolysis)
**Transcription/DNA
compaction
**Translation machinery
**ATPases (except
organellar)
**Many enzymes
Origin of the Major Groups (c)
Bacteria, Archaea, Eukarya
Summary
Both explanations are essentially based on inferences from
present-day organisms. Both explanations have strong
advocates.
Interpretations must have reservations. (For example,
whole-cell fusion, a common ancestor, or lateral gene
transfer could account for a trait in Eukarya.)
Lecture Outline (c)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene
transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Phagocytosis
as a means of
horizontal
gene transfer.
In part, as a lead-in to
endosymbiosis . . . .
PNAS 100: 7419
Basic Outline
of (Primary)
Endosymbiosis
using the plastid as
an example
The bulk of evidence (more later)
indicates that all chloroplasts resulted
from a single primary endosymbiotic
event (=monophyletic origin of plastids).
Basis for the Endosymbiosis Mechanism (a)
In virtually all ways:
chloroplasts = mitochondria = bacteria
**size
**ribosomes size & sensitivity antibiotics (implying homologous
function)/translation
**DNA packaging/transcription
** . . . and other features such as bias towards certain lipids in
membranes
**. . . and, as expected, all the above being in agreement with
sequence data (more later)
Basis for the Endosymbiosis Mechanism (b)
In virtually all ways:
chloroplasts = mitochondria = bacteria
. . .but they are not identical:
**DNA-containing organelles are only semiautonomous
For example, a chloroplast may contain ~100 ORF, but
requires ~1000 polypeptides for function. (Some of the
missing genes were transferred to the nucleus and
some—being redundant with those of the host—were
lost.)
** loss of function/features (e.g. cell wall) is the rule
(again, a reason for loss of genes).
Endosymbiosis—The devil is in the details.
The details . . .
**all chloroplasts are not the same. (more later)
**all mitochondria are not the same. For example, the
typical mammalian mitochondrial genome has only
0.017 MB, but those of some plant mitochondria have
up to 2.5 MB.
Secondary
Endosymbiosis
At least three separate secondary endosymbiotic events led to
plastids in different groups of algae. Some odd algae even have
two kinds of chloroplasts—either from tertiary endosymbiosis or
serial acquisition of chloroplasts.
Endosymbiosis—Summary and
BOT 3015 Focus
Green Alga/Plant
Primary
Secondary
Red Alga
Cryptomonad
Heterokont
Expert opinion, but not inclusive of all opinions.
Gene transfer . . . Summary (a)
The historical way to think of gene transfer is vertically:
1. Asexual (e.g., division of a single-celled organism to form two
daughter organisms by mitosis)
2. Sexual (i.e., formation of gametes followed by syngamy)
In this historical way of thinking, gene transfer is linear. One
can thus construct a tree in which there are unambiguous lines
of descent.
--------------------------------------------------------------------------“Life” is not so simple because of horizontal (=lateral) gene
transfer.
Gene transfer . . . Summary (b)
Mechanisms for horizontal gene transfer:
**conjugation, phagocytosis, & endosymbiosis (as shown earlier)
** bacterial transformation (=uptake of naked DNA). Natural
(complex cell machinery required) and artificial (e.g., by
treatment with membrane-permeabilizing agent); more later
** bacterial transduction (gene introduction by virus)
** “Transformation” is used broadly in most genetic engineering
literature to mean a stable change in genetic potential.
In plants, e.g., introduction of a novel gene is usually accomplished
by (a) transfer of a gene via a recombinant plasmid from the crown
gall bacterium, Agrobacterium; (b) biolistics (“gene gun”);
electroporation or chemically induced membrane pores; (d)
microfibers (stabbing cells with gene-coated fibers.)
Gene transfer . . . Summary (c)
How important is gene-by-gene horizontal gene transfer in evolution?
**central force of evolution of many different prokaryotes.
** occurs across domains
** role in eukaryotes less certain, but evidence is accumulating
in some groups, particularly phagocytotic algae. (E.g., in one
study, 21% of nuclear genes for plastid-targeted proteins were
derived by horizontal gene transfer.)
Lecture Outline (d)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Chloroplasts are one kind of plastid
Green Algal and
Plant Chloroplast
PSI & most
ATPase
PS II (LHCII
with chl b—
regions of
membrane
appression)
Calvin Cycle & Starch
Storage
Two limiting
membranes
Chloroplast
Types (a)
Red Algae
(most similar to
Cyanobacteria)
Green Algae & Plant (share
recent common ancestor)
Secondary Endosymbiosis
(Both these particular examples
result from engulfing a Red Alga)
Brown Algae (and
others) (example of
heterokont & meiotic
gametogenesis)
Cryptomonad
(convincing
example of
surviving
nucleomorph)
Organization of PS II light-harvesting pigments
Three types of
antenna complexes
involved in light
harvesting.
*** phycobilisomes,
cyanobacteria and
red algae
*** LHCII (chl a/b
binding), plants &
green algae
*** fucoxanthin/chl
a/c complex, brown
algae
Reaction Center Complex
A few Chl a, other electrontransfer reagents, 5 proteins;
role is charge separation.
Proximal Chl a-complex
Two types of chl a-binding
proteins (also carotenes);
role is to harvest light and
transfer energy.
Core Complex =
The above two complexes—sufficient for
photosynthesis. Essentially the same in all
photosynthetic eukaryotes.
Organization of PS II light-harvesting pigments
Three types of
antenna complexes
involved in light
harvesting.
*** phycobilisomes,
cyanobacteria and
red algae
*** LHCII (chl a/b
binding), plants &
green algae
*** fucoxanthin/chl
a/c complex, brown
algae
Extrinsic (little proteinaceous knobs on
membrane); no lateral heterogeneity in
thylakoid membranes; associated with linear
pigments (phycocyanin and phycobilins)
Integral complexes that migrate between
photosystems to balance light, thus stacking and
unstacking thylakoids. (Recall, stacked and
unstacked regions have different functions.)
Integral complexes. No lateral heterogeneity
in thylakoid membranes.
Lecture Outline (e)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Plastidic and other 16S rRNA phylogeny
Plants and Green Algae
18S rRNA
phylogeny
Animals and Fungi
Phototrophic & Heterotrophic Heterokonts
Summary of Relationships
***Chloroplasts have a monophyletic origin (All plastidic16S
rRNA sequences more similar to each other than to any extant
cyanobacterium; gene clusters in chloroplasts similar to each
other but different to cyanobacteria; similarity of protein import
machinery)
***Green Algae and plants share a recent common ancestor not
shared by other groups (chloroplast structure, chemistry, 16S &
18S rRNA sequences)
***The eukaryotic portions of heterokonts share a common
history, regardless of whether photosynthetic or not
(morphology, 18S rRNA sequence, much more)
***Fungi and animals share a “recent” common ancestor not
shared by other eukaryotes (18S rRNA and much more)
Diversification of plastids
The large diversity of plastids, assumed to have been achieved since
the seminal endosymbiotic event, obviously raises questions because
no single extant cyanobacterium contains the range of lightabsorbing pigments found in algae.
. . . but the biosynthetic pathways leading to pigments are similar,
and, moreover, the engulfed cyanobacterium might have had the
range of pigments, which have been subsequently lost.
Lecture Outline (f)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Examples of Green Algae: Colonial Forms
These panels depict three species (Gonium, Pandorina, Eudorina)
that comprise a colonial series made up of Chlamydomonas-type
cells. The pinnacle in this dead-end evolutionary series is Volvox,
which is made of thousands of cells.
Examples of Green Algae: Siphonous Form
Acetabularia
Examples of Green Algae: Parenchytamous Forms
Ulva
Chlamydomonas sp.
Chlamydomonas asexual life cycle
Chlamydomonas sexual life cycle
Lecture Outline (g)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Examples of Red Algae: Bonnemaisonia
Examples of Red Algae: coralline alga (calcified walls)
Examples of Red Algae:
Batrachospermum
Lecture Outline (h)
Chronology of life and life processes on Earth
Possible origins of the proto-eukaryal cell
Endosymbiosis and other methods for non-vertical gene transfer
Morphology and function of chloroplasts
16(18)S rRNA sequence analysis
Green Algae
Red Algae
Heterokonts (Brown Algae and Oomycetes)
Heterokont (=different flagella)
“Tinsel-type” flagellum with two
rows of stiff glycoproteinaceous
hairs.
Shorter, smooth flagellum, often
with a basal swelling that is
involved in light sensing.
Image from Graham & Wilcos
Examples of Brown Algae: Durvillea, New Zealand
Examples of Brown
Algae: Laminaria
Examples of
Brown Algae:
Macrocystis
Examples of Brown Algae: Fucus (Rockweed)
Fucus sexual life cycle
Phytophthora infestans
on potato
Phytophthora life cycle
End
End