A reassessment of Geminella (Chlorophyta) based upon photosynthetic pigments, DNA sequence analysis and electron microscopy
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Maris R. Durako (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
- Advisor
- J. Craig Bailey
Abstract: A cultured microalgal strain (UTEX 2540) originally identified as Heterotrichella
gracillas Reisigl (Xanthophyceae) was re-examined using various techniques. Morphological
evidence, particularly the absence of dimorphic cells (one blunt, the other tapered to an acute
point), indicate that strain UTEX 2540 has been misidentified. Heterotrichella gracillas is
considered to be a member of the chlorophyll a and c-containing class Xanthophyceae
(Chromista). However, HPLC analyses of photosynthetic pigments indicated the presence of
chlorophylls a and b, ß-carotene, lutein and violaxanthin while ultrastructural data revealed the
presence of starch stored inside the plastid. These data, as well as small subunit (18S rRNA)
gene sequence analysis, indicate that this alga belongs in the Chlorophyta, not the
Xanthophyceae (Chromista). Further DNA sequence analyses suggest that UTEX 2540 is most
closely related to Geminella terricola Petersen and certain Microspora species that are currently
classified in the Ulotrichales. However, unlike other Geminella species, UTEX 2540 exists as
single cells or forms poorly organized (2-8 celled) ephemeral pseudofilaments. A conspicuous
extracellular mucilaginous sheath characterizes other Geminella species but this feature is
lacking in UTEX 2540. Furthermore, our analyses convincingly demonstrate that Geminella and
at least some isolates of Microspora do not belong in the Ulotrichales. These results suggest that
(1) the generic concept for Geminella must be broadened to include unicellular species that lack
an apparent mucilaginous envelope, (2) Geminella does not belong in the Ulotrichales, and,
instead, (3) its closest relatives among other green algae are almost certainly found within the
Trebouxiophyceae.
A reassessment of Geminella (Chlorophyta) based upon photosynthetic pigments, DNA sequence analysis and electron microscopy
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
- Language: English
- Date: 2009
- Keywords
- Green algae, Spirogyra
- Subjects
- Green algae
- Spirogyra