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Raphidophyte
The raphidophytes, formally known as Raphidophycidae or Raphidophyceae (formerly referred to as Chloromonadophyceae and Chloromonadineae), are a small group of eukaryotic algae that includes both marine and freshwater species. All raphidophytes are unicellular, with large cells (50 to 100 μm), but no cell walls. Raphidophytes possess a pair of flagella, organised such that both originate from the same invagination (or gullet). One flagellum points forwards, and is covered in hair-like mastigonemes, while the other points backwards across the cell surface, lying within a ventral groove. Raphidophytes contain numerous ellipsoid chloroplasts, which contain chlorophylls a, c1 and c2. They also make use of accessory pigments including β-carotene and diadinoxanthin. Unlike other heterokontophytes, raphidophytes do not possess the photoreceptive organelle (or eyespot) typical of this group. In terms of ecology, raphidophytes occur as photosynthetic autotrophs across a range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Gonyostomum Semen
''Gonyostomum semen'' is a species of freshwater algae in the genus ''Gonyostomum'', with worldwide distribution. They cause nuisance algal blooms and are known to cause allergic reactions to people swimming in lakes. Distribution This freshwater microalgal species is globally distributed. It usually occurs in small, acidic lakes with high concentrations of dissolved organic carbon, which result in sharp gradients of light intensity due to rapid attenuation of light with depth. During the last decades, ''G. semen'' has spread in northern Europe to many non-humic lakes with higher pH. There is evidence that brownification of lakes in these areas, decreasing pH and higher water temperature initiated the spreading of this species. Physiology The drop-shaped, vegetative cells of ''G. semen'' are up to 100 μm long, but can vary quite a bit in form and size, as they are only surrounded by a cell membrane instead of a cell wall. These microalgae are, therefore, highly fragil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |