Anabaena variabilis: Difference between revisions

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==Cell structure and metabolism==
==Cell structure and metabolism==
Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.
As described before, the interesting features of ''Anabaena variabilis'' stem from its genes, which code for something that affects the whole organism. The different nitrogenase enzymes that are produced allow the organism to live in different environments, while still carrying out its major processes. The different conditions for each gene are specified below: <br /> <br />
''nif1'': “diazotrophic conditions only in heterocysts” <br />
''nif2'': “strictly anoxic conditions in vegetative and heterocysts” <br />
''vnf'': “diazotrophic conditions lacking molybdate, with or without vanadate”  (7). <br /> <br />
Under the first gene, the organism can grow without having the need of a fixed nitrogen source. The organism is able to fix its own nitrogen from the environment by using the Mo-Fe cofactor (7).
With the second gene the cell can continue to grow even without an oxygen source. The organism will still use the same Mo-Fe cofactor. The third gene that is transcribed to fix nitrogen will occur when the organism is exposed to an environment lacking molybdate, which is part of the Mo-Fe cofactor needed with the genes ''nif1'' and ''nif2''. This allows the organism to grow without the use of a certain cofactor that other cyanobacteria would need. <br /> <br />
Another interesting feature about the ''Anabaena variabilis'' is that it has the gene that codes for the production of the Phenylalanine ammonia lyase (PAL). This enzyme is common is terrestrial plants, but rare in prokaryotic organisms. It is used to catalyze the beginning of the formation of phenylpropanoids (6).


==Ecology==
==Ecology==

Revision as of 15:44, 5 June 2007

A Microbial Biorealm page on the genus Anabaena variabilis

Photo: Lang, Kurpp, and Koller. From the Joint Genome Institution

Classification


Higher order taxa

Bacteria; Cyanobacteria; Nostocales; Nostocaceae; Anabaena

Genus and Species

Anabaena variabilis

NCBI: Taxonomy


Description and significance

Anabaena variabilis is a bacteria strain of blue-green algae that are known as cyanobacteria. Cyanobacteria are able to carry out photosynthesis, fix nitrogen from the environment, and also produce hydrogen. This feature of creating hydrogen with energy from the sun has made it popular in many laboratories in the world. The main role in its sequencing and research is because of the previous data collected regarding its physiology, biochemistry, and genetics can be better understood (4). This particular strain has also been described to have a “complex life cycle” that involved many types of cells that differentiate. The cells described were the “Heterocysts for nitrogen fixation, akinetes (spores) for survival, and hormogonia for motility and establishment of symbiotic associations with plants and fungi” (4).

The organism Anabaena variabilis was isolated at the U.S. Department of Energy Joint Genome Institute (DOE JGI). The DOE JGI listed that it sequenced the genomes of the organisms through the use of “whole-genome shotgun” (5). It described the technique as randomly “shearing” the genome DNA and then re-assembling it by comparing similar sequences and then inferring the original genome. The institute lists the three different size fragments that it can use and gives an example of how the procedure is done (5).

Genome structure

Anabaena variabilis has been sequenced and the data gathered showed that the circular DNA contains 6,365,727 base pairs (2). The information on the site shows that the GC-content of the organism is at 41.4% and that the genome as of now codes for 5043 proteins and 62 RNA strands (3). The cyanobacteria also have three plasmids which are named plasmid A, B, and C (3). The plasmids probably affect the organism’s ability to produce immunity to harmful substances and also provide the codes for certain proteins. Respectively, the plasmids each codes for 344, 31 and 243 proteins within the cyanobacteria (3).


Some interesting characteristics about this organism are some of its genes. It contains two gene clusters, nif1 and nif2, that code for Mo-nitrogenase (7). It also has another gene cluster, vnf, which codes for V-Fe cofactor nitrogenase. Each of the nitrogenase are activated under different conditions allowing the cyanobacteria to function. The Anabaena variabilis is also one of the few prokaryotic organisms that contains the enzyme Phenylalanine ammonia lyase (PAL), which helps deaminate phenylalanine to cinnamate (6).

Cell structure and metabolism

As described before, the interesting features of Anabaena variabilis stem from its genes, which code for something that affects the whole organism. The different nitrogenase enzymes that are produced allow the organism to live in different environments, while still carrying out its major processes. The different conditions for each gene are specified below:

nif1: “diazotrophic conditions only in heterocysts”
nif2: “strictly anoxic conditions in vegetative and heterocysts”
vnf: “diazotrophic conditions lacking molybdate, with or without vanadate” (7).

Under the first gene, the organism can grow without having the need of a fixed nitrogen source. The organism is able to fix its own nitrogen from the environment by using the Mo-Fe cofactor (7). With the second gene the cell can continue to grow even without an oxygen source. The organism will still use the same Mo-Fe cofactor. The third gene that is transcribed to fix nitrogen will occur when the organism is exposed to an environment lacking molybdate, which is part of the Mo-Fe cofactor needed with the genes nif1 and nif2. This allows the organism to grow without the use of a certain cofactor that other cyanobacteria would need.

Another interesting feature about the Anabaena variabilis is that it has the gene that codes for the production of the Phenylalanine ammonia lyase (PAL). This enzyme is common is terrestrial plants, but rare in prokaryotic organisms. It is used to catalyze the beginning of the formation of phenylpropanoids (6).

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by Phuoc Nam Nguyen, student of Rachel Larsen and Kit Pogliano