|
Home / Greens / Siphonous
/Acetabularia
|
||||
|
|
|
|
||
|
|
|
|
|
|
|
|
||||
|
|
|
|
|
|
|
|
|
|
|
|
|
Click
on images for larger format |
||||
Name derivation: |
||||
|
"Vinegar Cup" but more generously called
"Mermaid's Wineglass"
|
||||
Classification: |
||||
Acetabularia J.V.Lamouroux 1812;
13 of 39 species descriptions are currently accepted taxonomically
(Guiry and Guiry 2013).
Order Dasycladales; Family Polyphysaceae
|
||||
Morphology: |
||||
|
Rhizoid at the base of a long stalk,
at the top of the stalk radial branches fan out forming a cap. It is very
large with a complex morphology for a single cell, and is a coenocyte that contains
thousands of nuclei. The stalk tends to calcify, i.e.
form an outer layer of marl as a result of the rise in pH related to
photosynthesis.
|
||||
Similar genera: |
||||
|
|
||||
Circadian Rhythm: |
||||
Periodicity of 24 – 25 hours,
considered circadian, has been observed several times in the unicellular
Acetabularia. For example, electrical
polarity from one end to the other along the cell varies from ~ 10 – 15 mV
with a 24 h cycle in continuous light (> 14 quanta). Cytoplasmic streaming recorded with
cinematic photomicrography was also cyclic in continuous light. Both the polarity and the streaming, as
well as morphogenesis and growth, gradually ceased in continuous darkness
(Borghi et al. 1983).
Chloroplast movement, measured
with time-lapse cinematography, was first observed in Acetabularia by Koop et al. (1978) with a periodicity of 27 h
under constant light The nucleus also
moved the same direction as the chloroplasts . Later experiments in continuous light (14
– 21 quanta) demonstrated a periodicity of 23.8 – 26.8 h in which the nucleus
was not essential in establishing the circadian rhythm in Acetabularia mediterranea (Woolum 1991).
Chloroplast movement is
associated with actin microtubules (microfilaments) in the cytoplasm as well
as pulses of trancellular action potential.
Blue light activates movement nearly the same as white light, while
red light has minimal effect (Dazy et al. 1989).
|
||||
Chloroplast
activity inside sea slug:
|
||||
Elysia timida feeds on Acetabularia acetabulum and retains chloroplasts that remain functional, providing photosynthates to the slug even when the alga is seasonally unavailable, a distinct advantage of the slug competitors (Marin and Ros 1992). |
||||
Habitat: |
||||
|
Subtropical
oceans |
||||
References: |
||||
|
Dazy, A-C, S. Puiseux-Dao and H.
Borghi 1989). The effects of blue and red light on
Acetabularia mediterranea after long exposure to darkness. Bioloy of the Cell 67:227-234. Guiry, M.D. and G.M. Guiry 2013.
AlgaeBase. World-wide electronic
publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 30
October 2013. Koop, H.U., r. Schmid,
H.H. Hennert and B. Milthaler
1978. Chloroplast
migration: A new circadian rhythm in
Acetabularia. Protoplasma 97:301-310. Lamouroux, J.V.F. 1812.
Extrait d'un mémoire sur la
classification des Polypiers coralligènes non entièrement pierreux. Nouveaux
Bulletin des Sciences,
par la Société Philomathique de Paris 3: 181-188. Marin, A. and J.D. Ros 1992.
Dynamics of a peculiar plant-herbivore relationship: the photosynthetic ascoglossan Elysia timida and the chlorophycean Acetabularia acetabulum. Marine Biology 112:677-682. Woolum, J.C.
1991. A re-examination of the
role of the nucleus in generating the circadian rhythm in Acetabularia. J. Biol. rhythms 6:129-136. |
||||
