- •Contents
- •Preface to the first edition
- •Flagella
- •Cell walls and mucilages
- •Plastids
- •Mitochondria and peroxisomes
- •Division of chloroplasts and mitochondria
- •Storage products
- •Contractile vacuoles
- •Nutrition
- •Gene sequencing and algal systematics
- •Classification
- •Algae and the fossil record
- •REFERENCES
- •CYANOPHYCEAE
- •Morphology
- •Cell wall and gliding
- •Pili and twitching
- •Sheaths
- •Protoplasmic structure
- •Gas vacuoles
- •Pigments and photosynthesis
- •Akinetes
- •Heterocysts
- •Nitrogen fixation
- •Asexual reproduction
- •Growth and metabolism
- •Lack of feedback control of enzyme biosynthesis
- •Symbiosis
- •Extracellular associations
- •Ecology of cyanobacteria
- •Freshwater environment
- •Terrestrial environment
- •Adaption to silting and salinity
- •Cyanotoxins
- •Cyanobacteria and the quality of drinking water
- •Utilization of cyanobacteria as food
- •Cyanophages
- •Secretion of antibiotics and siderophores
- •Calcium carbonate deposition and fossil record
- •Chroococcales
- •Classification
- •Oscillatoriales
- •Nostocales
- •REFERENCES
- •REFERENCES
- •REFERENCES
- •RHODOPHYCEAE
- •Cell structure
- •Cell walls
- •Chloroplasts and storage products
- •Pit connections
- •Calcification
- •Secretory cells
- •Iridescence
- •Epiphytes and parasites
- •Defense mechanisms of the red algae
- •Commercial utilization of red algal mucilages
- •Reproductive structures
- •Carpogonium
- •Spermatium
- •Fertilization
- •Meiosporangia and meiospores
- •Asexual spores
- •Spore motility
- •Classification
- •Cyanidiales
- •Porphyridiales
- •Bangiales
- •Acrochaetiales
- •Batrachospermales
- •Nemaliales
- •Corallinales
- •Gelidiales
- •Gracilariales
- •Ceramiales
- •REFERENCES
- •Cell structure
- •Phototaxis and eyespots
- •Asexual reproduction
- •Sexual reproduction
- •Classification
- •Position of flagella in cells
- •Flagellar roots
- •Multilayered structure
- •Occurrence of scales or a wall on the motile cells
- •Cell division
- •Superoxide dismutase
- •Prasinophyceae
- •Charophyceae
- •Classification
- •Klebsormidiales
- •Zygnematales
- •Coleochaetales
- •Charales
- •Ulvophyceae
- •Classification
- •Ulotrichales
- •Ulvales
- •Cladophorales
- •Dasycladales
- •Caulerpales
- •Siphonocladales
- •Chlorophyceae
- •Classification
- •Volvocales
- •Tetrasporales
- •Prasiolales
- •Chlorellales
- •Trebouxiales
- •Sphaeropleales
- •Chlorosarcinales
- •Chaetophorales
- •Oedogoniales
- •REFERENCES
- •REFERENCES
- •EUGLENOPHYCEAE
- •Nucleus and nuclear division
- •Eyespot, paraflagellar swelling, and phototaxis
- •Muciferous bodies and extracellular structures
- •Chloroplasts and storage products
- •Nutrition
- •Classification
- •Heteronematales
- •Eutreptiales
- •Euglenales
- •REFERENCES
- •DINOPHYCEAE
- •Cell structure
- •Theca
- •Scales
- •Flagella
- •Pusule
- •Chloroplasts and pigments
- •Phototaxis and eyespots
- •Nucleus
- •Projectiles
- •Accumulation body
- •Resting spores or cysts or hypnospores and fossil Dinophyceae
- •Toxins
- •Dinoflagellates and oil and coal deposits
- •Bioluminescence
- •Rhythms
- •Heterotrophic dinoflagellates
- •Direct engulfment of prey
- •Peduncle feeding
- •Symbiotic dinoflagellates
- •Classification
- •Prorocentrales
- •Dinophysiales
- •Peridiniales
- •Gymnodiniales
- •REFERENCES
- •REFERENCES
- •Chlorarachniophyta
- •REFERENCES
- •CRYPTOPHYCEAE
- •Cell structure
- •Ecology
- •Symbiotic associations
- •Classification
- •Goniomonadales
- •Cryptomonadales
- •Chroomonadales
- •REFERENCES
- •CHRYSOPHYCEAE
- •Cell structure
- •Flagella and eyespot
- •Internal organelles
- •Extracellular deposits
- •Statospores
- •Nutrition
- •Ecology
- •Classification
- •Chromulinales
- •Parmales
- •Chrysomeridales
- •REFERENCES
- •SYNUROPHYCEAE
- •Classification
- •REFERENCES
- •EUSTIGMATOPHYCEAE
- •REFERENCES
- •PINGUIOPHYCEAE
- •REFERENCES
- •DICTYOCHOPHYCEAE
- •Classification
- •Rhizochromulinales
- •Pedinellales
- •Dictyocales
- •REFERENCES
- •PELAGOPHYCEAE
- •REFERENCES
- •BOLIDOPHYCEAE
- •REFERENCE
- •BACILLARIOPHYCEAE
- •Cell structure
- •Cell wall
- •Cell division and the formation of the new wall
- •Extracellular mucilage, biolfouling, and gliding
- •Motility
- •Plastids and storage products
- •Resting spores and resting cells
- •Auxospores
- •Rhythmic phenomena
- •Physiology
- •Chemical defense against predation
- •Ecology
- •Marine environment
- •Freshwater environment
- •Fossil diatoms
- •Classification
- •Biddulphiales
- •Bacillariales
- •REFERENCES
- •RAPHIDOPHYCEAE
- •REFERENCES
- •XANTHOPHYCEAE
- •Cell structure
- •Cell wall
- •Chloroplasts and food reserves
- •Asexual reproduction
- •Sexual reproduction
- •Mischococcales
- •Tribonematales
- •Botrydiales
- •Vaucheriales
- •REFERENCES
- •PHAEOTHAMNIOPHYCEAE
- •REFERENCES
- •PHAEOPHYCEAE
- •Cell structure
- •Cell walls
- •Flagella and eyespot
- •Chloroplasts and photosynthesis
- •Phlorotannins and physodes
- •Life history
- •Classification
- •Dictyotales
- •Sphacelariales
- •Cutleriales
- •Desmarestiales
- •Ectocarpales
- •Laminariales
- •Fucales
- •REFERENCES
- •PRYMNESIOPHYCEAE
- •Cell structure
- •Flagella
- •Haptonema
- •Chloroplasts
- •Other cytoplasmic structures
- •Scales and coccoliths
- •Toxins
- •Classification
- •Prymnesiales
- •Pavlovales
- •REFERENCES
- •Toxic algae
- •Toxic algae and the end-Permian extinction
- •Cooling of the Earth, cloud condensation nuclei, and DMSP
- •Chemical defense mechanisms of algae
- •The Antarctic and Southern Ocean
- •The grand experiment
- •Antarctic lakes as a model for life on the planet Mars or Jupiter’s moon Europa
- •Ultraviolet radiation, the ozone hole, and sunscreens produced by algae
- •Hydrogen fuel cells and hydrogen gas production by algae
- •REFERENCES
- •Glossary
- •Index
CHLOROPHYTA |
143 |
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tive geotaxis by swimming against gravity. Such |
general line of evolution occurring in the same |
|
a feature would be selected for in evolution |
direction. Usually gametes are specialized cells |
|
because when the algal cell (which is heavier than |
and not vegetative cells, although in the one- |
|
water) is confronted with darkness, it must move |
celled Volvocales the latter can occur. If the |
|
up to the surface in order to obtain light for |
species is isogamous or anisogamous, the gametes |
|
growth and reproduction. In Chlamydomonas, neg- |
are usually not formed in specialized cells |
|
ative geotaxis is an energy-dependent response |
although in the oogamous species, gametes are |
|
that requires a horizontal swimming path of at |
normally formed in specialized gametangia (e.g., |
|
least 200 m because the normal geotactic orien- |
Coleochaete, Fig. 5.25). Whereas most Chlorophyta |
|
tation maneuvers require long gradual turns. The |
form motile flagellated gametes (zoogametes), in |
|
rate of geotaxis is steady but slow relative to the |
the Zygnematales aplanogametes or amoeboid |
|
average swimming speed (Bean, 1977). |
gametes are formed. |
|
|
In some of the Chlorophyta, gametogenesis is |
|
Asexual reproduction |
induced by environmental changes, whereas in |
|
others the presence of two sexually different |
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strains is necessary. In the latter, vegetative cells |
|
There are a number of types of asexual reproduc- |
of one sex secrete a substance that initiates sexual |
|
tion, the simplest being fragmentation of colonies |
differentiation in competent cells of the opposite |
|
into two or more parts, each part becoming a new |
sex. Such a situation is common in the Volvocales |
|
colony. Zoosporogenesis commonly occurs, usually |
(Starr, 1972; Kirk and Kirk, 1986) and is considered |
|
induced by a change in the environment of the alga. |
in more detail later. In Oedogonium (Fig. 5.95), sex |
|
In the Chlorophyta, zoospores are normally pro- |
organs form without the complementary strain, |
|
duced in vegetative cells (e.g., Ulothrix; Fig. 5.31), |
but subsequent fertilization is under a complex |
|
and only in a few cases are they formed in special- |
hormonal control. In other genera, a chemotactic |
|
ized sporangia (e.g., Derbesia; Fig. 5.42). Zoospores |
substance is sometimes produced by the egg that |
|
are usually formed in the younger parts of fila- |
attracts the spermatozoids. This does not gener- |
|
ments, and the number of zoospores is generally a |
ally happen in isogamous species. In isogamous |
|
power of two in uninucleate genera. Aplanospores |
species, sexually different gametes meet at |
|
are non-flagellated and have a wall distinct from the |
random and immediately adhere by means of an |
|
parent cell wall (e.g., Trebouxia; Fig. 5.86(a)–(c)). |
agglutination reaction. The agglutinative flagel- |
|
Aplanospores are considered to be abortive |
lar adhesion between gametes of different sex is |
|
zoospores and have the ability to form a new plant |
designated as the mating-type reaction. Initially |
|
on germination. Autospores are aplanospores that |
after mixing, the gametes of opposite sexes |
|
have the same shape as the parent cell, and are common |
adhere by their flagella tips in clusters of up to 25 |
|
in the Chlorellales (e.g., Chlorella; Fig. 5.83). |
gametes. Soon the anterior ends of complemen- |
|
Autospores are usually formed in a multiple of two |
tary gametes fuse, and the flagella free them- |
|
in the parent cell. Coenobia are colonies with a definite |
selves. The motile zygote then swims for some |
|
number of cells arranged in a specific manner (e.g., |
time before settling and secreting a thick wall. |
|
Volvox; Fig. 5.69). Genera with colonies arranged in |
The mating-type substances (responsible for |
|
coenobia form daughter colonies with a certain |
flagellar agglutination) are localized and function |
|
number of cells. In maturation of the daughter |
at the flagella tips. It is possible to isolate the |
|
coenobia, there is enlargement but no division of |
mating-type substances that still have the ability to |
|
vegetative cells in the coenobia. |
interact with the gametes of the opposite sex. When |
|
|
added to the opposite gamete type, they cause |
|
Sexual reproduction |
isoagglutination (male gametes will clump with |
|
each other when a female mating-type substance is |
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||
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added to the culture). The mating-type substances |
|
Sexual reproduction in the Chlorophyceae may be |
are discussed in more detail for Chlamydomonas, |
|
isogamous, anisogamous, or oogamous, with the |
which has been most intensively studied. |