Anabaena azollae: Difference between revisions
| Line 17: | Line 17: | ||
==Genome structure== | ==Genome structure== | ||
The complete genome of Anabaena is 7.2 million base pairs long. The sequenced strain, known as Anabaena sp. strain PCC 7120, was sequence in a collaborative effort between Japanese researchers led by Takakazu Kaneko, of the Kazusa DNA Research Institute in Chiba, Japan, and C. Peter Wolk, of the Michigan State University in East Lansing. Anabaena has a single circular chromosome of 6.4 million base pairs and six smaller circular plasmids. Researchers have identified 5,368 genes in the chromosome, 45 % of which are functional. More than 60 genes involved in various processes of heterocyst formation and nitrogen fixation were assigned to the chromosome. The genomes of many other strains of Anabaena have been sequenced (NCBI Taxonomy Browser), however only several strains of Anabaena Azollae have been sequenced (strains 0708 and PCC 7120). Sequencing of the Anabaena genome has the potential to aid researchers in the study of the genetics and physiology of cellular differentiation and nitrogen fixation (as exhibited in the heterocycsts of Anabaena). Information on the genome of Anabaena Azollae 0708 can be found on KEGG GENOME. | |||
Genes that cause cellular differentiation has been the focus of much research to date. Out of the 5,368 possible genes, only two genes that control the initiation of heterocyst formation and the frequency of cell differentiation have been identified. The hetR gene codes for a protein required for heterocyst differentiation and is only transcribed in differentiating cells. The patS gene has been found to regulate the frequency at which cells develop into heterocysts. | |||
==Cell structure, metabolism & life cycle== | ==Cell structure, metabolism & life cycle== | ||
Revision as of 06:59, 28 October 2011
A Microbial Biorealm page on the genus Anabaena azollae
Classification
Higher Order Taxa:
Bacteria; Cyanobacteria, Nostocales, Nostocaceae, Anabaena,
Species:
Azollae
Description and significance
Anabaena Azollae is a small filamentous phototrophic cyanobacteria generally seen as a multicellular organism with two distinct, interdependent cell types. The first is a small, circular, photoautotrophic “vegetative” cell that performs oxygenic photosynthesis and is typically blue green in color. The second is a heterocyst; a larger, paler, more homogenous cell produced by Anabaena to fix atmospheric nitrogen. A. Azollae, although it can exist on it’s own, is usually found within ovoid cavities inside the leaves of the water fern Azolla. Azolla (also known as mosquito fern, duckweed fern, or fairy moss) is a genus of common waterfern whose small leaves accumulate on the surface of bodies of water creating mats. A. Azollae and Azolla have formed a symbiotic relationship in which the cyanobacterium receives carbon and nitrogen sources from the plant in exchange for fixed nitrogen. This relationship has proven to be useful to humans in the production of food; specifically in the fertilization of rice paddies. Azolla is used as an organic biofertilizer to increase the nitrogen levels in the rice paddies. A. Azollae is a model organism commonly used in labs for the study of gene differentiation in the formation of heterocysts.
Genome structure
The complete genome of Anabaena is 7.2 million base pairs long. The sequenced strain, known as Anabaena sp. strain PCC 7120, was sequence in a collaborative effort between Japanese researchers led by Takakazu Kaneko, of the Kazusa DNA Research Institute in Chiba, Japan, and C. Peter Wolk, of the Michigan State University in East Lansing. Anabaena has a single circular chromosome of 6.4 million base pairs and six smaller circular plasmids. Researchers have identified 5,368 genes in the chromosome, 45 % of which are functional. More than 60 genes involved in various processes of heterocyst formation and nitrogen fixation were assigned to the chromosome. The genomes of many other strains of Anabaena have been sequenced (NCBI Taxonomy Browser), however only several strains of Anabaena Azollae have been sequenced (strains 0708 and PCC 7120). Sequencing of the Anabaena genome has the potential to aid researchers in the study of the genetics and physiology of cellular differentiation and nitrogen fixation (as exhibited in the heterocycsts of Anabaena). Information on the genome of Anabaena Azollae 0708 can be found on KEGG GENOME.
Genes that cause cellular differentiation has been the focus of much research to date. Out of the 5,368 possible genes, only two genes that control the initiation of heterocyst formation and the frequency of cell differentiation have been identified. The hetR gene codes for a protein required for heterocyst differentiation and is only transcribed in differentiating cells. The patS gene has been found to regulate the frequency at which cells develop into heterocysts.
Cell structure, metabolism & life cycle
Provide a physical and biochemical description of the organism. What kind of organism is it, what does it look like, how is it built, what are its metabolic properties, how can it be identified, what is it's life cycle, &c. In other words, describe the organism from its perspective.
Ecology (including pathogenesis)
Describe its habitat, symbiosis, and contributions to environment. If it is a pathogen, how does this organism cause disease? Human, animal, plant hosts? Describe virulence factors and patient symptoms.
Interesting feature
Describe in detail one particularly interesting aspect of your organism or it's affect on humans or the environment.
