2024-03-29T07:54:04Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/344442019-08-06T09:49:16Zcom_10261_50com_10261_8col_10261_303
2011-04-08T09:42:01Z
urn:hdl:10261/34444
A rapid Method for the Quantitative Isolation of Green Algae from lichens
Ascaso, Carmen
Parmelia conspersa (Ach)
Lasallia pustulata (L)
Lichens
Green algae
Trebouxia
1 page. Short Communication.
This report describes a rapid and quantitative method for the isolation of green algae
from lichen thalli. Several qualitative techniques have been described (see Richardson,
1971, for a review), but until now a quantitative method for blue-green algae only has
been published (Millbank and Kershaw, 1969).
Two grams of washed thalli of Parmelia conspersa (Ach.) or Lasallia pustulata (L.),
were minced with scissors and then ground up in a mortar with distilled water. The
macérate was further homogenized with six strokes in a teflon-glass Elvehjem-Potter
homogenizer and then filtered through three layers of gauze of standard mesh size. The
volume of the fíltrate was adjusted to 100 mi with distilled water and centrifuged five
times at 100 g for 10 s. The pellets were mixed and re-processed as above. The supernatants
were mixed and algal cells were pelleted by centrifugation at 500 g for 10 min.
The algae were resuspended in 0-25 M sucrose in a final volume of 2 mi and the algal
suspensión was layered over 3 mi of a CsCl solution of a density of l-550gcm~3
(refractive Índex at 25 °C r¡z& = 1-3856). After centrifugation at 4500 rev min'1 in the
swinging-bucket rotor of a clinical centrifuge for 10 min, algal cells banded at the
interphase and were recovered, washed and resuspended in 0-25 M sucrose.
Algal symbionts of two lichen species (P. conspersa and L. pustulata) were quantitatively
isolated and puriñed by the method described above. No appreciable contamination
by fungal hyphae was observed on microscopic examination and the recovery of puré
algae was about 50 mg of wet weight per gram of thallus. Caesium chloride can be
replaced by potassium iodide which is cheaper and so is preferable, particularly for
larger-scale isolations than the one described here. An 80 per cent (w/v) solution of
KI has approximately the same density as the CsCl solution used above.
The yield of algae was sufficient to allow chemical analysis of phycobiont freshly
isolated from lichens. Furthermore, only a small fraction (about 10 per cent) of the
algal cells were altered in their appearance under the microscope. The two lichen species
studied in this paper have Trebouxia as phycobiont (Ascaso and Galvan, 1976), but
the method described here might be used successfully on other lichen species with
different algal components. In this case some modification in the density of CsCl or
KI solutions may be required.
2011-04-08T09:42:01Z
2011-04-08T09:42:01Z
1980
artículo
Annals of Botany 45: 483 (1980)
0305-7364
http://hdl.handle.net/10261/34444
eng
closedAccess
Elsevier