User:Jj.campp/sandbox

Critiquing Microbial ecology

Although many facts have been supported by appropriate references throughout the article, there were some statements that did not have any citation. For example, claims such as "Some theories go as far as saying the shift in the balance of gases might have triggered a global ice-age known as the Snowball Earth" are vague because they make no mention of where the indicated "theories" come from. I have appended a [citation needed] annotation at the end of this sentence to garner attention.

Although many of the statements made on the article are relevant, the organization of content is not conducive to learning. The information is staggered and little transitive flow is apparent. There is potential for a lot of redundant overlap to occur between the contents of each heading. This could be addressed by making them more specific or having subheadings that clearly differentiate and expand on relevant subtopics.

Some statements do not appear to be completely neutral - using "a pressing concern for researchers". Furthermore, informal language is used in some cases.

Although many of the references come from peer-reviewed journals, there are some instances of reputedly poor citations. For example, references to some sub-par press releases. Also some of the citations do not work, such as the link to "healio.com" - an unreliable citation, nevertheless.

Fortunately, there do not seem to be viewpoints that are over-represented/under-represented. However, there is a general lack of information on specific roles that microbial ecology is involved in.

Cyanobiont

My final edits and drafts on this topic will be posted in User:V.Fungi/sandbox.

Rough Outline

Function of Symbiotic cyanobacteria (Physical Interactions)

• Nitrogen fixation
• Photosynthesis

Symbioses (Organisms involved in the interaction)

• Sponges
• Ascadians
• Dinoflagellates
• Lichens
• Diatom
• Ect. (depends on how many we want to include)

Relationship

• Free living → symbiosis/mutualism
• Loss of autonomy

Biont Maintenance

• Horizontal transmission: when biont is obtained via environment→ RARE
• Vertical Transmission: when biont is obtained via replication, from mother to daughter cells→ more common
• If eukaryotes replicate asexually, bionts are more likely to transfer vertically
• If eukaryotes replicate sexually, favors horizontal transmission of bionts

Introduction (JO)

Cyanobionts are cyanobacteria that live in symbiosis with a wide range of organisms encompassing terrestrial or aquatic plant, algal, and fungal species . In order for a cyanobacterium to successfully form a sybiotic relationship, it must be able to exchange signals with the host, overcome defense mounted by the host, be capable of hormogonia formation, chemotaxis, heterocyst formation, as well as possess adequate elasticity to reside in host tissue . The most well-known plant-associated cyanobionts belong to the Nostoc genus . With the ability to differentiate into several cell types that have various functions, Nostoc’s morphological plasticity, flexibility and adaptability to any environmental condition, are partially responsible for its high capacity to form symbiotic relationships with other organisms . However, several cyanobionts involved with fungi and marine organisms also belong to the Richelia, Calothrix, Synechocystis, Aphanocapsa, and Anabaena genera, as well as the Ocillatoria spongeliae species . Although there are many documented symbioses between cyanobacteria and marine organisms, little is known about the nature of many of these symbioses. The possibility of discovering many more novel symbiotic relationships is apparent from preliminary microscopic observations .

Currently, cyanobionts have been found to form symbiosis with various organisms in the marine environment such as diatoms, dinoflagellates, sponges, protozoans, Ascidians, Acadians, and Echiuroid worms, of which have significance in maintaining the biogeochemistry of both open ocean and coastal waters . Specifically, symbiosis involving cyanobacteria is mutualistic, in which the cyanobionts are responsible for nutrient provision to the host in exchange for attaining high structural-functional specialization . Most cyanobacteria-host symbioses are found in oligotrophic areas in which there is limited availability of nutrients such as carbon (DOC) and nitrogen, although a few occur in nutrient-rich areas such as mudflats .

Functional role of cyanobionts in symbiosis (JO)

Cyanobionts play a variety of roles in their symbiotic relationships with the host organism. The cyanobiont’s growth is almost always synchronized with the host. They function primarily as nitrogen- and carbon-fixers, however, they can also be involved in [metabolite] exchange, as well as in provision of UV protection to their symbiotic partners since some can produce nitrogen-containing compounds with sunscreen-like properties, such as scytonemin and mycosporin-like amino acids .

By entering into a symbiosis with nitrogen-fixing cyanobacteria, organisms that otherwise cannot inhabit low-nitrogen environments are provided with adequate levels of fixed nitrogen to carry out life functions. Providing nitrogen is a common role of cyanobionts in many symbiotic relationships, most especially in those with photosynthetic hosts. Formation of an anaerobic envelope (heterocyst) to prevent nitrogenase from being irreversibly damaged in the presence of oxygen is an important strategy employed by nitrogen-fixing cyanobacteria to carry out fixation of dinitrogen in the air, via nitrogenase, into biologically-useful nitrogen . To keep up with the large nitrogen demand of both the symbiotic partner and itself, cyanobionts fix nitrogen at a higher rate, as compared to their free-living counterparts, by increasing frequency of heterocyst formation .

Cyanobacteria are also photosynthetically active and can therefore meet carbon requirements independently. In symbioses involving cyanobacteria, at least one of the partners must be photoautotrophic in order to generate sufficient amounts of carbon for the mutualistic system . This role is usually allocated to cyanobionts in symbiotic relationships with non-photosynthetic partners such as marine invertebrates .