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Life cyle and sexuality of the freshwater raphidophyte Gonyostomum semen (Raphidophyceae)

Figueroa, Rosa LU and Rengefors, Karin LU (2006) In Journal of Phycology 42(4). p.859-871
Abstract
Previously unknown aspects in the life cycle of the freshwater flagellate Gonyostomum semen (Ehrenb.) (Raphidophyceae) are described here. This species forms intense blooms in many northern temperate lakes, and has increased in abundance and frequency in northern Europe during the past decades. The proposed life cycle is based on observations of life cycle stages and transitions in cultures. Viable stages of the life cycle were individually isolated and monitored by time-lapse photography. The most common processes undertaken by the isolated cells were: division, fusion followed by division, asexual cyst formation, and sexual cyst formation. Motile cells divided by two different processes. One lasted between 6 and 24 h and formed two cells... (More)
Previously unknown aspects in the life cycle of the freshwater flagellate Gonyostomum semen (Ehrenb.) (Raphidophyceae) are described here. This species forms intense blooms in many northern temperate lakes, and has increased in abundance and frequency in northern Europe during the past decades. The proposed life cycle is based on observations of life cycle stages and transitions in cultures. Viable stages of the life cycle were individually isolated and monitored by time-lapse photography. The most common processes undertaken by the isolated cells were: division, fusion followed by division, asexual cyst formation, and sexual cyst formation. Motile cells divided by two different processes. One lasted between 6 and 24 h and formed two cells with vegetative cell size and with or without the same shape. The second division process lasted between 10 and 20 min and formed two identical cells, half the size of the mother cell. Planozygotes formed by the fusion of hologametes subsequently underwent division into two cells. Asexual cyst-like stages were spherical, devoid of a thick wall and red spot, and germinated in 24-48 h. Heterogamete pairs were isogamous, and formed an angle of 0-90 degrees between each other. Planozygote and sexual cyst formation were identified within strains established from one vegetative cell. The identity of these strains, which was studied by an amplified fragment length polymorphism analysis, was correlated with the viability of the planozygote. Resting cyst germination was described using cysts collected in the field. The size and morphology of these cysts were comparable with those formed sexually in culture. The excystment rate was higher at 24 degrees C than at 19 or 16 degrees C, although the cell liberated during germination (germling) was only viable at 16 degrees C. The placement of G. semen within the Raphidophyceae family was confirmed by sequence analysis of a segment of the 18S ribosomal DNA. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
AFLP, cysts, encystment, Gonyostomum semen life cycle, raphydophyceans, sexuality, SSU
in
Journal of Phycology
volume
42
issue
4
pages
859 - 871
publisher
Wiley-Blackwell
external identifiers
  • wos:000239258900011
  • scopus:33746415764
ISSN
0022-3646
DOI
10.1111/j.1529-8817.2006.00240.x
language
English
LU publication?
yes
id
3276421c-96be-4b50-83e7-5492d27a2bb5 (old id 159781)
date added to LUP
2007-06-28 13:11:51
date last changed
2019-05-28 01:41:00
@article{3276421c-96be-4b50-83e7-5492d27a2bb5,
  abstract     = {Previously unknown aspects in the life cycle of the freshwater flagellate Gonyostomum semen (Ehrenb.) (Raphidophyceae) are described here. This species forms intense blooms in many northern temperate lakes, and has increased in abundance and frequency in northern Europe during the past decades. The proposed life cycle is based on observations of life cycle stages and transitions in cultures. Viable stages of the life cycle were individually isolated and monitored by time-lapse photography. The most common processes undertaken by the isolated cells were: division, fusion followed by division, asexual cyst formation, and sexual cyst formation. Motile cells divided by two different processes. One lasted between 6 and 24 h and formed two cells with vegetative cell size and with or without the same shape. The second division process lasted between 10 and 20 min and formed two identical cells, half the size of the mother cell. Planozygotes formed by the fusion of hologametes subsequently underwent division into two cells. Asexual cyst-like stages were spherical, devoid of a thick wall and red spot, and germinated in 24-48 h. Heterogamete pairs were isogamous, and formed an angle of 0-90 degrees between each other. Planozygote and sexual cyst formation were identified within strains established from one vegetative cell. The identity of these strains, which was studied by an amplified fragment length polymorphism analysis, was correlated with the viability of the planozygote. Resting cyst germination was described using cysts collected in the field. The size and morphology of these cysts were comparable with those formed sexually in culture. The excystment rate was higher at 24 degrees C than at 19 or 16 degrees C, although the cell liberated during germination (germling) was only viable at 16 degrees C. The placement of G. semen within the Raphidophyceae family was confirmed by sequence analysis of a segment of the 18S ribosomal DNA.},
  author       = {Figueroa, Rosa and Rengefors, Karin},
  issn         = {0022-3646},
  keyword      = {AFLP,cysts,encystment,Gonyostomum semen life cycle,raphydophyceans,sexuality,SSU},
  language     = {eng},
  number       = {4},
  pages        = {859--871},
  publisher    = {Wiley-Blackwell},
  series       = {Journal of Phycology},
  title        = {Life cyle and sexuality of the freshwater raphidophyte Gonyostomum semen (Raphidophyceae)},
  url          = {http://dx.doi.org/10.1111/j.1529-8817.2006.00240.x},
  volume       = {42},
  year         = {2006},
}