Protistiary - Mitochondria

MITOCHONDRIA
There are a relatively small number of shapes of mitochondrial cristae. Categories of mitochondria may also be by a number of other features, such as associations with other organelles or inclusions that can be distinctive. The shapes of the cristae are determined largely by comparing the 'short' and 'long' profiles of a crista (a spherical or bleb-like crista will look more or less circular in any profile, tubes will be a mixture of short and long profiles, flat cristae are parallel sided - the various profiles in flat and cross-section are shown alongside. The shape of the cristae has been used as the basis of various subsets of protists - such as the discicristates, the tubulocristates, and the platycristates. Although some care is needed in interpreting cristal form, the groupings are broadly consistent with other phylogenetic markers, although - because of the small number of forms - are not very discriminatory. click here to activate a key to various forms of cristae
Mitochondria of the pedinellid Actinomonas pusilla. The cristae are tubular - there are only circular and some longer profiles. The cristae of all stramenopiles are cylindrical. There is some material within the cristae, and this is unusual. Tubulocristate - stramenopile. Images by Jacob Larsen, copyright Jacob Larsen.
The mitochondria of Chrysolepidomonas dendrolepidota have bleb like cristae, as do the mitochondria of most stramenopiles. In this case, some of the mitochondria are closely associated with one of the microtubular roots that arise from the flagellar apparatus. Tubulocristate - stramenopile. Adapted from Peters, M. C. and Andersen, R. A. 1993. The flagellar apparatus of Chrysolepidomonas dendrolepidota (Chrysophyceae), a single-celled monad covered with organic scales. J. Phycol., 29: 476-485.
The mitochondria in Poterioochromonas malhamensis, like those of all stramenopiles, have tubular cristae. The bleb shape is determined because all profiles are more or less round - none flat and none elongate. Some mitochondria are closely associated with one of the microtubular roots arising from the basal bodies. Tubulocristate - stramenopile. Adapted from Schnepf, E., Deichgräber, G., Röderer, G. and Herth, W. 1977. The flagellar root apparatus, the microtubular system and associated organelles in the chrysophycean flagellate, Poterioochromonas malhamensis Peterfi (syn. Porteriochromonas stipitata Scherffel and Ochromonas malhamensis Pringsheim). Protoplasma, 92: 87-107.
A mitochondrion from Actinophrys sol, one of the actinophryid heliozoa. Although not initially very like most stramenopiles, the affinities of these organisms was first suggested through similarities with the pedinellid flagellates, and this has subsequently been confirmed through comparative sequence studies. Tubulocristate - stramenopile. Image and copyright by D. J. Patterson
Mitochondria of the endobiotic Proteromonas lacertae. Cristae are tubular. Tubulocristate - ciliate. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss. Image by Guy Brugerolle.
The mitochondria of Paramecium putrinum - the cristae have two profiles, circular and elongate revealing that they have a long tubular make up. There is similarity with the cristae of some stramenopiles (see Proteromonas). Image taken and copyright by D J Patterson.
Hydrogenosomes of Metopus contortus . The term 'hydrogenosome' is used for organelles in evolutionarily distant groups (trichomonads and ciliates), so despite metabolic overlap, hydrogenosomes are a good example of convergent evolution (though check out the comments in the reference below). The similarity with mitochondria is considerably greater in these ciliates than in trichomonads. The occurrence of these organelles in various ciliates from anoxic habitats is evidence of the capacity of mitochondria to relinquish some of their 'irreducible complexity' (sorry, ID rather invites comments like this). These images show the two membranes that separate the contents of the organelle from the cytoplasm as well as residual cristae. Adapted from Biagnini, G. A., Finlay, B. J., and Lloyd, D. 1997. Evolution of the hydrogenosome. FEMS Microbiology letters, 155: 133-140.
The mitochondria (m) of the amoeba, Sappinia diploidea. The profiles are mostly tubular, but occasional profiles show that the cristae can branch. Ramicristate - euamoebae. b = bacteria. Adapted from Page, F. C. 1974. A light- and electron-microscopical study of Sappinia diploidea, a sexual amoeba. Protistologica, 10:207-216.
Mitochondria of the cryptomonad Cryptomonas, showing that the structure radiates and is fenestrated. The gaps are where ejectisomes used to be located. . The cristae are flat. Platycristate - cryptomonads. Adapted from Santore, U. J. and Greenwood, A. D. 1977. The mitochondrial complex of Cryptophyceae. Arch. Microbiol. 112: 207-218.
Mitochondria of the crypotomonad Hemiselmis rufescens. The cristae are flat. Platycristate - cryptomonads. Adapted from Santore, U. J. and Greenwood, A. D. 1977. The mitochondrial complex of Cryptophyceae. Arch. Microbiol. 112: 207-218.
Diagram showing the extensive form of the mitochondrion (M) of the cryptomonad Hemiselmis rufescens. N and Nu = nucleus and nucleolus, Ly = lysosome, Cp = cytoplasm, Nm = nucleomorph, P = pyrenoid, F = flagellar bases, G = 'gullet', Go = dictyosome, S = polysaccharide storage material, L = lipid stores. Adapted from Santore, U. J. and Greenwood, A. D. 1977. The mitochondrial complex of Cryptophyceae. Arch. Microbiol. 112: 207-218.
Small part of the extensive mitochondrial system of the euglenid Cyclidiopsis acus. Discicristate - Euglenozoa. Adapted from Mignot, J-P. 1966. Structure et ultrastructure de quelques euglénomonadines. Protistologica, 2: 51-117. Image by J-P. Mignot.
Mitochondria of the euglenid, Euglena spirogyra. The cristae are flattened and discoidal. Discicristate - euglenozoa. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss.. Image by Gordon Leedale.
Flat cristae in a kinetoplastid flagellate. The slightly swollen periphery of the cristae is common in discoidal cristae. The cristae are stacked in a regular array. Discicristate - Euglenozoa. Source of image unknown.
The tightly compacted mass of DNA that makes up the kinetoplast in a kinetoplastid flagellate. Source of image unknown.
An unraveled section of the DNA mass that makes up the kinetoplast in a kinetoplastid flagellate. The DNA is mostly in the form of loops. Source of image unknown.
Mitochondria of the kinetoplastid flagellate, Cryptobia vaginalis. The cristae are flattened. Discicristate - euglenozoa. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss. Image by Keith Vickerman.
Mitochondria of the heterolobosean flagellate, Percolomonas cosmopolitus. The cristae are flattened and discoidal (arrow). Note the slightly expanded rim of the cristae in cross-section - a common characteristic in discoidal cristae. Image and copyright by D. J. Patterson.
Mitochondria of the chonaoflagellate Stephanoeca diplocostata. The cristae are flattened. Platycristate - opisthokonts. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss. Image by Barry Leadbeater.
The ramifying mitochondria of Stepahnopogon apogon as they extend along folds on the ventral surface of the cell. The fixation protocol has left the mitochondrial matrix very dense. The cristae are flattened, and have swollen margins, very similar to those of kinetoplastid flagellates. This is one reason why this small group of flagellates is believed to be related to the Euglenozoa. Image and copyright by D J Patterson.
The ramifying mitochondria of Stepahnopogon apogon as they extend along folds on the ventral surface of the cell. The fixation protocol has left the mitochondrial looking very empty, and some of the profiles are indicated by the asterisks. This is one reason why this small group of flagellates is believed to be related to the Euglenozoa. Image and copyright by D J Patterson.
Hydrogenosomes of Tritrichomonas foetus. The term 'hydrogenosome' is used for organelles in evolutionarily distant groups (trichomonads and ciliates), so despite metabolic overlap, hydrogenosomes are a good example of convergent evolution. The similarity with mitochondria is considerably less in trichomonads than in ciliates. This is therefore one of the amitochondrial lineages that seem to have a residual mitochondrion-derived organelle or other indications that they once had mitochondria. This image shows numerous hydrogenosomes associated with cytoskeletal elements (Ax) in the cell. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss. Iamge by Guy Brugerolle.
Hydrogenosomes of Tritrichomonas foetus. The term 'hydrogenosome' is used for organelles in evolutionarily distant groups (trichomonads and ciliates), so despite metabolic overlap, hydrogenosomes are a good example of convergent evolution. The similarity with mitochondria is considerably less in trichomonads than in ciliates. This is therefore one of the amitochondrial lineages that seem to have a residual mitochondrion-derived organelle or other indications that they once had mitochondria. These images show the two membranes that separate the contents of the organelle from the cytoplasm. Adapted from Benchimol, M. and de Souza, W. 1983. Fine structure and cytochemistry of the hydrogenosome of Tritrichomonas foetus. Journal of Protozoology, 30: 422-425.
Crypton inclusions of Entamoeba histolytica. This is one of the amitochondriate protists. The organelle has no cristae, but - as the title of the article suggests - several pieces of evidence (since extended) indicate that the crypton organelle is derived from mitochondria. Although Entamoeba was never a contender for 'primitive eukaryote' this was the first one in which mitochondrial derived organelles were found and started the hunt for similar organelles in the other amitochondriate protists. Most, if not all, amitochondrial lineages have a residual mitochondrion-derived organelle or other indications that they once had mitochondria. The diplomonads are the most recalcitrant in revealing this evidence. Adapted from. Ghosh, S., Field, J., Rogers, R., Hickman, M. and Samuelson, J. 2000. The Entamoeba histolytica mitochondrion-derived organelle (Crypton) contains double-stranded DNA and appears to be bound by a double membrane. Infection and Immunity, 68: 4319-4322. (pdf)
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MITOCHONDRIA

There are a relatively small number of shapes of mitochondrial cristae. Categories of mitochondria may also be by a number of other features, such as associations with other organelles or inclusions that can be distinctive.

The shapes of the cristae are determined largely by comparing the 'short' and 'long' profiles of a crista (a spherical or bleb-like crista will look more or less circular in any profile, tubes will be a mixture of short and long profiles, flat cristae are parallel sided - the various profiles in flat and cross-section are shown alongside.

The shape of the cristae has been used as the basis of various subsets of protists - such as the discicristates, the tubulocristates, and the platycristates. Although some care is needed in interpreting cristal form, the groupings are broadly consistent with other phylogenetic markers, although - because of the small number of forms - are not very discriminatory.

click here to activate a key to various forms of cristae

Mitochondria of the pedinellid Actinomonas pusilla. The cristae are tubular - there are only circular and some longer profiles. The cristae of all stramenopiles are cylindrical. There is some material within the cristae, and this is unusual. Tubulocristate - stramenopile. Images by Jacob Larsen, copyright Jacob Larsen.

The mitochondria of Chrysolepidomonas dendrolepidota have bleb like cristae, as do the mitochondria of most stramenopiles. In this case, some of the mitochondria are closely associated with one of the microtubular roots that arise from the flagellar apparatus. Tubulocristate - stramenopile. Adapted from Peters, M. C. and Andersen, R. A. 1993. The flagellar apparatus of Chrysolepidomonas dendrolepidota (Chrysophyceae), a single-celled monad covered with organic scales. J. Phycol., 29: 476-485.

The mitochondria in Poterioochromonas malhamensis, like those of all stramenopiles, have tubular cristae. The bleb shape is determined because all profiles are more or less round - none flat and none elongate. Some mitochondria are closely associated with one of the microtubular roots arising from the basal bodies. Tubulocristate - stramenopile. Adapted from Schnepf, E., Deichgräber, G., Röderer, G. and Herth, W. 1977. The flagellar root apparatus, the microtubular system and associated organelles in the chrysophycean flagellate, Poterioochromonas malhamensis Peterfi (syn. Porteriochromonas stipitata Scherffel and Ochromonas malhamensis Pringsheim). Protoplasma, 92: 87-107.

A mitochondrion from Actinophrys sol, one of the actinophryid heliozoa. Although not initially very like most stramenopiles, the affinities of these organisms was first suggested through similarities with the pedinellid flagellates, and this has subsequently been confirmed through comparative sequence studies. Tubulocristate - stramenopile. Image and copyright by D. J. Patterson

Mitochondria of the endobiotic Proteromonas lacertae. Cristae are tubular. Tubulocristate - ciliate. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss. Image by Guy Brugerolle.

The mitochondria of Paramecium putrinum - the cristae have two profiles, circular and elongate revealing that they have a long tubular make up. There is similarity with the cristae of some stramenopiles (see Proteromonas). Image taken and copyright by D J Patterson.

Hydrogenosomes of Metopus contortus . The term 'hydrogenosome' is used for organelles in evolutionarily distant groups (trichomonads and ciliates), so despite metabolic overlap, hydrogenosomes are a good example of convergent evolution (though check out the comments in the reference below). The similarity with mitochondria is considerably greater in these ciliates than in trichomonads. The occurrence of these organelles in various ciliates from anoxic habitats is evidence of the capacity of mitochondria to relinquish some of their 'irreducible complexity' (sorry, ID rather invites comments like this). These images show the two membranes that separate the contents of the organelle from the cytoplasm as well as residual cristae. Adapted from Biagnini, G. A., Finlay, B. J., and Lloyd, D. 1997. Evolution of the hydrogenosome. FEMS Microbiology letters, 155: 133-140.

The mitochondria (m) of the amoeba, Sappinia diploidea. The profiles are mostly tubular, but occasional profiles show that the cristae can branch. Ramicristate - euamoebae. b = bacteria. Adapted from Page, F. C. 1974. A light- and electron-microscopical study of Sappinia diploidea, a sexual amoeba. Protistologica, 10:207-216.

Mitochondria of the cryptomonad Cryptomonas, showing that the structure radiates and is fenestrated. The gaps are where ejectisomes used to be located. . The cristae are flat. Platycristate - cryptomonads. Adapted from Santore, U. J. and Greenwood, A. D. 1977. The mitochondrial complex of Cryptophyceae. Arch. Microbiol. 112: 207-218.

Mitochondria of the crypotomonad Hemiselmis rufescens. The cristae are flat. Platycristate - cryptomonads. Adapted from Santore, U. J. and Greenwood, A. D. 1977. The mitochondrial complex of Cryptophyceae. Arch. Microbiol. 112: 207-218.

Diagram showing the extensive form of the mitochondrion (M) of the cryptomonad Hemiselmis rufescens. N and Nu = nucleus and nucleolus, Ly = lysosome, Cp = cytoplasm, Nm = nucleomorph, P = pyrenoid, F = flagellar bases, G = 'gullet', Go = dictyosome, S = polysaccharide storage material, L = lipid stores. Adapted from Santore, U. J. and Greenwood, A. D. 1977. The mitochondrial complex of Cryptophyceae. Arch. Microbiol. 112: 207-218.

Small part of the extensive mitochondrial system of the euglenid Cyclidiopsis acus. Discicristate - Euglenozoa. Adapted from Mignot, J-P. 1966. Structure et ultrastructure de quelques euglénomonadines. Protistologica, 2: 51-117. Image by J-P. Mignot.

Mitochondria of the euglenid, Euglena spirogyra. The cristae are flattened and discoidal. Discicristate - euglenozoa. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss.. Image by Gordon Leedale.

Flat cristae in a kinetoplastid flagellate. The slightly swollen periphery of the cristae is common in discoidal cristae. The cristae are stacked in a regular array. Discicristate - Euglenozoa. Source of image unknown.

The tightly compacted mass of DNA that makes up the kinetoplast in a kinetoplastid flagellate. Source of image unknown.

An unraveled section of the DNA mass that makes up the kinetoplast in a kinetoplastid flagellate. The DNA is mostly in the form of loops. Source of image unknown.

Mitochondria of the kinetoplastid flagellate, Cryptobia vaginalis. The cristae are flattened. Discicristate - euglenozoa. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss. Image by Keith Vickerman.

Mitochondria of the heterolobosean flagellate, Percolomonas cosmopolitus. The cristae are flattened and discoidal (arrow). Note the slightly expanded rim of the cristae in cross-section - a common characteristic in discoidal cristae. Image and copyright by D. J. Patterson.

Mitochondria of the chonaoflagellate Stephanoeca diplocostata. The cristae are flattened. Platycristate - opisthokonts. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss. Image by Barry Leadbeater.

The ramifying mitochondria of Stepahnopogon apogon as they extend along folds on the ventral surface of the cell. The fixation protocol has left the mitochondrial matrix very dense. The cristae are flattened, and have swollen margins, very similar to those of kinetoplastid flagellates. This is one reason why this small group of flagellates is believed to be related to the Euglenozoa. Image and copyright by D J Patterson.

The ramifying mitochondria of Stepahnopogon apogon as they extend along folds on the ventral surface of the cell. The fixation protocol has left the mitochondrial looking very empty, and some of the profiles are indicated by the asterisks. This is one reason why this small group of flagellates is believed to be related to the Euglenozoa. Image and copyright by D J Patterson.

Hydrogenosomes of Tritrichomonas foetus. The term 'hydrogenosome' is used for organelles in evolutionarily distant groups (trichomonads and ciliates), so despite metabolic overlap, hydrogenosomes are a good example of convergent evolution. The similarity with mitochondria is considerably less in trichomonads than in ciliates. This is therefore one of the amitochondrial lineages that seem to have a residual mitochondrion-derived organelle or other indications that they once had mitochondria. This image shows numerous hydrogenosomes associated with cytoskeletal elements (Ax) in the cell. Adapted from Vickerman, K., Brugerolle, G. and Mignot, J-P. Mastigophora in Harrison, F. W., and Corliss, J. O. (Eds). 1999. Microscopic Anatomy of Invertebrates. Wiley Liss. Iamge by Guy Brugerolle.

Hydrogenosomes of Tritrichomonas foetus. The term 'hydrogenosome' is used for organelles in evolutionarily distant groups (trichomonads and ciliates), so despite metabolic overlap, hydrogenosomes are a good example of convergent evolution. The similarity with mitochondria is considerably less in trichomonads than in ciliates. This is therefore one of the amitochondrial lineages that seem to have a residual mitochondrion-derived organelle or other indications that they once had mitochondria. These images show the two membranes that separate the contents of the organelle from the cytoplasm. Adapted from Benchimol, M. and de Souza, W. 1983. Fine structure and cytochemistry of the hydrogenosome of Tritrichomonas foetus. Journal of Protozoology, 30: 422-425.

Crypton inclusions of Entamoeba histolytica. This is one of the amitochondriate protists. The organelle has no cristae, but - as the title of the article suggests - several pieces of evidence (since extended) indicate that the crypton organelle is derived from mitochondria. Although Entamoeba was never a contender for 'primitive eukaryote' this was the first one in which mitochondrial derived organelles were found and started the hunt for similar organelles in the other amitochondriate protists. Most, if not all, amitochondrial lineages have a residual mitochondrion-derived organelle or other indications that they once had mitochondria. The diplomonads are the most recalcitrant in revealing this evidence. Adapted from. Ghosh, S., Field, J., Rogers, R., Hickman, M. and Samuelson, J. 2000. The Entamoeba histolytica mitochondrion-derived organelle (Crypton) contains double-stranded DNA and appears to be bound by a double membrane. Infection and Immunity, 68: 4319-4322. (pdf)

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