Tetrapyrroles such as chlorophyll and heme are indispensable for life because they are involved in energy fixation and consumption, i.e. photosynthesis and oxidative phosphorylation. In eukaryotes, the tetrapyrrole biosynthetic pathway is shaped by past endosymbioses. We investigated the origins and predicted locations of the enzymes of the heme pathway in the chlorarachniophyte Bigelowiella natans, the cryptophyte Guillardia theta, the "green" dinoflagellate Lepidodinium chlorophorum, and three dinoflagellates with diatom endosymbionts ("dinotoms"): Durinskia baltica, Glenodinium foliaceum and Kryptoperidinium foliaceum. Bigelowiella natans appears to contain two separate heme pathways analogous to those found in Euglena gracilis; one is predicted to be mitochondrial-cytosolic, while the second is predicted to be plastid-located. In the remaining algae, only plastid-type tetrapyrrole synthesis is present, with a single remnant of the mitochondrial-cytosolic pathway, a ferrochelatase of G. theta putatively located in the mitochondrion. The green dinoflagellate contains a single pathway composed of mostly rhodophyte-origin enzymes, and the dinotoms hold two heme pathways of apparently plastidal origin. We suggest that heme pathway enzymes in B. natans and L. chlorophorum share a predominantly rhodophytic origin. This implies the ancient presence of a rhodophyte-derived plastid in the chlorarachniophyte alga, analogous to the green dinoflagellate, or an exceptionally massive horizontal gene transfer.

• MeSH
• Biological Evolution * MeSH
• Biosynthetic Pathways * genetics   MeSH
• Cryptophyta classification   genetics   metabolism   MeSH
• Dinoflagellida classification   genetics   metabolism   MeSH
• Phylogeny MeSH
• Heme metabolism   MeSH
• Porphobilinogen Synthase genetics   metabolism   MeSH
• Diatoms classification   genetics   metabolism   MeSH
• Gene Expression Profiling MeSH
• Tetrapyrroles metabolism   MeSH
• Publication type
• Journal Article MeSH

Algae frequently get a bad press. Pond slime is a problem in garden pools, algal blooms can produce toxins that incapacitate or kill animals and humans and even the term seaweed is pejorative - a weed being a plant growing in what humans consider to be the wrong place. Positive aspects of algae are generally less newsworthy - they are the basis of marine food webs, supporting fisheries and charismatic marine megafauna from albatrosses to whales, as well as consuming carbon dioxide and producing oxygen. Here we consider what algae are, their diversity in terms of evolutionary origin, size, shape and life cycles, and their role in the natural environment and in human affairs.

• MeSH
• Apicomplexa genetics   physiology   MeSH
• Biodiversity * MeSH
• Chlorophyta classification   genetics   physiology   MeSH
• Cryptophyta genetics   physiology   MeSH
• Dinoflagellida genetics   physiology   MeSH
• Eukaryota classification   genetics   physiology   MeSH
• Glaucophyta classification   genetics   physiology   MeSH
• Haptophyta genetics   physiology   MeSH
• Stramenopiles genetics   physiology   MeSH
• Charophyceae genetics   physiology   MeSH
• Rhizaria genetics   physiology   MeSH
• Rhodophyta classification   genetics   physiology   MeSH
• Reproduction physiology   MeSH
• Cyanobacteria classification   genetics   physiology   MeSH
• Symbiosis physiology   MeSH
• Publication type
• Journal Article MeSH