Oxymonad
Encyclopedia
The Oxymonads are a group of flagellated
protozoa found exclusively in the intestines of termite
s and other wood-eating insects. Along with the similar parabasalid
flagellates, they harbor the symbiotic bacteria that are responsible for breaking down cellulose
. Both groups lack mitochondria
, and oxymonads also lack dictyosome
s.
It includes Dinenympha
, Pyrsonympha
, and Oxymonas
.
, associated with four flagella. Their basal bodies give rise to a several long sheets of microtubule
s, which form an organelle called an axostyle
, but different in structure from the axostyles of parabasalids. The cell may use the axostyle to swim, as the sheets slide past one another and cause it to undulate. An associated fiber called the preaxostyle separates the flagella into two pairs. A few oxymonads have multiple nuclei, flagella, and axostyles.
is closely related to the oxymonads. It lacks mitochondria and has four flagella separated by a preaxostyle, but unlike the oxymonads has a feeding groove. This character places the Oxymonads and Trimastix among the excavate
s, and in particular they may belong to the metamonad
s.
Flagellate
Flagellates are organisms with one or more whip-like organelles called flagella. Some cells in animals may be flagellate, for instance the spermatozoa of most phyla. Flowering plants do not produce flagellate cells, but ferns, mosses, green algae, some gymnosperms and other closely related plants...
protozoa found exclusively in the intestines of termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
s and other wood-eating insects. Along with the similar parabasalid
Parabasalid
The parabasalids are group of flagellate protozoa, most of which are symbiotic in animals. These include a variety of forms found in the guts of termites and cockroaches, many of which have symbiotic bacteria that help them digest wood. Some other species are human pathogens.-Characteristics:The...
flagellates, they harbor the symbiotic bacteria that are responsible for breaking down cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
. Both groups lack mitochondria
Mitochondrion
In cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers in diameter...
, and oxymonads also lack dictyosome
Golgi apparatus
The Golgi apparatus is an organelle found in most eukaryotic cells. It was identified in 1898 by the Italian physician Camillo Golgi, after whom the Golgi apparatus is named....
s.
It includes Dinenympha
Dinenympha
Dinenympha is a genus of Excavata.It includes the species Dinenympha exilis....
, Pyrsonympha
Pyrsonympha
Pyrsonympha is a genus of Excavata.It includes the species Pyrsonympha vertens....
, and Oxymonas
Oxymonas
Oxymonas is a genus of Excavata.It includes the species Oxymonas protus....
.
Characteristics
Most Oxymonads are around 50 μm in size and have a single nucleusCell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
, associated with four flagella. Their basal bodies give rise to a several long sheets of microtubule
Microtubule
Microtubules are a component of the cytoskeleton. These rope-like polymers of tubulin can grow as long as 25 micrometers and are highly dynamic. The outer diameter of microtubule is about 25 nm. Microtubules are important for maintaining cell structure, providing platforms for intracellular...
s, which form an organelle called an axostyle
Axostyle
An axostyle is a sheet of microtubules found in certain microbial eukaryotes. It arises from the bases of the flagella, sometimes projecting beyond the end of the cell, and is often flexible or contractile, and so may be involved in movement and provides support for the cell...
, but different in structure from the axostyles of parabasalids. The cell may use the axostyle to swim, as the sheets slide past one another and cause it to undulate. An associated fiber called the preaxostyle separates the flagella into two pairs. A few oxymonads have multiple nuclei, flagella, and axostyles.
Relationship to Trimastix
The free-living flagellate TrimastixTrimastix
Trimastix is an Excavate grouping.One species is Trimastix pyriformis....
is closely related to the oxymonads. It lacks mitochondria and has four flagella separated by a preaxostyle, but unlike the oxymonads has a feeding groove. This character places the Oxymonads and Trimastix among the excavate
Excavate
The excavates are a major kingdom of unicellular eukaryotes, often known as Excavata. The phylogenetic category Excavata, proposed by Cavalier-Smith in 2002, contains a variety of free-living and symbiotic forms, and also includes some important parasites of humans.-Characteristics:Many excavates...
s, and in particular they may belong to the metamonad
Metamonad
The metamonads are a large group of flagellate protozoa. Their composition is not entirely settled, but they include the retortamonads, diplomonads, and possibly the parabasalids and oxymonads as well...
s.