Talk:PAMGO work in progress: Difference between revisions

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The process by which an organism effects a change in the function of a '''host protein via a direct''' '''interaction'''. The host is defined as the larger of the organisms involved in a symbiotic interaction.
The process by which an organism effects a change in the function of a '''host protein via a direct''' '''interaction'''. The host is defined as the larger of the organisms involved in a symbiotic interaction.
===Trudy_Candace_Michelle===
The process by which an organism effects a change in the function of a host protein via a direct interaction. The host is defined as the larger of the organisms involved in a symbiotic interaction.
response to [org] defenses (MAKE AS MORE NARROW SYNONYMS OF THIS TERM: “evasion of [org] defenses,” “suppression of [org] defenses,” “tolerance of [org] defenses
          evasion or tolerance of [org] defenses (merge to the parent term “response to [org] defenses”
response to [org] oxidative burst  (child of “response to [org] defenses”)
response to [org] phytoalexins (child of “response to [org] defenses”)
response to [org] nitric oxide (child of “response to [org] defenses”)
evasion by virus of host defenses (obsolete this term)
                        evasion of host defense response (GO:0030682) (merge to parent “response to [org] defenses”)
                        evasion of host immune response (GO:0020012) (child of “response to [org] defenses”)
suppression of [org] defenses (merge to parent term “response to [org] defenses”
child terms include suppression of host processes (merged into terms up above)
We do not need to add terms about “passive” and “active” evasion, etc.; on the other hand, having the words “constitutive” and “induced” in the definition is fine and desirable.


== Modification/modulation of host defenses ==
== Modification/modulation of host defenses ==

Revision as of 11:57, 22 January 2007

Some issues I'm encountering whilst working through the file. Please put your thoughts on the matter underneath each issue. Also see the PAMGO terms to be defined page for a list of PAMGO terms which need definitions.


The first draft of the ontology changes can be found in this SourceForge item:

https://sourceforge.net/tracker/index.php?func=detail&aid=1546635&group_id=36855&atid=440764

It would be great if we could discuss any points on the wiki here, since it allows you to organise things much better than SourceForge.


If you want to leave a comment, click on the "edit" tag for that section, and add your comment at the bottom, starting it with your name as a subheader (put three equals signs in front of and after your name, i.e.

===The Invisible Hulk===

). This will automatically create a link at the top of the page, making it easy to navigate to.

If the point you want to talk about isn't already in the list here, just click the + sign at the top of the page; that creates a new comment section.


Thanks!

The 'other organism' string

See PAMGO The Other Organism String

Hypersensitive response

See PAMGO Hypersensitive Response

Modification of host protein function

At the moment, modification of host protein function is a child of 'modification ... via secreted substance'. This seems OK to me, but are there any ways in which host protein function can be modified directly or via some other method?


Candace_Michelle_Trudy@PAG

In the literature, most of the macromolecules involved in the modification of host protein function are secreted so it is safe to conclude for now that host protein functions are modified mainly via secreted proteins and as such would be a child of 'modification ... via secreted substance" without creating a sibling term "modification ... via non-secreted substance".


However, we modified the definition....find below:

The process by which an organism effects a change in the function of a host protein via a direct interaction. The host is defined as the larger of the organisms involved in a symbiotic interaction.

Trudy_Candace_Michelle

The process by which an organism effects a change in the function of a host protein via a direct interaction. The host is defined as the larger of the organisms involved in a symbiotic interaction.


response to [org] defenses (MAKE AS MORE NARROW SYNONYMS OF THIS TERM: “evasion of [org] defenses,” “suppression of [org] defenses,” “tolerance of [org] defenses

         evasion or tolerance of [org] defenses (merge to the parent term “response to [org] defenses”

response to [org] oxidative burst (child of “response to [org] defenses”) response to [org] phytoalexins (child of “response to [org] defenses”) response to [org] nitric oxide (child of “response to [org] defenses”) evasion by virus of host defenses (obsolete this term)

                       evasion of host defense response (GO:0030682) (merge to parent “response to [org] defenses”)
                       evasion of host immune response (GO:0020012) (child of “response to [org] defenses”)

suppression of [org] defenses (merge to parent term “response to [org] defenses” child terms include suppression of host processes (merged into terms up above)

We do not need to add terms about “passive” and “active” evasion, etc.; on the other hand, having the words “constitutive” and “induced” in the definition is fine and desirable.



Modification/modulation of host defenses

Host defenses consist of the induced defenses - the defense response mounted by the host - and the preexisting defenses, such as the cell wall and other defensive structures. We've got modification of host structure and modulation of host defense response, but nothing to encapsulate both - logically it seems like a term we should have since elsewhere we have structures like this:

  • evasion or tolerance of host defenses
    • evasion or tolerance of host defense response

Currently, we've got the term 'response to host defenses ; GO:0044413' (was 'avoidance of host defenses' but we renamed it), which is defined thus:

Any process, either constitutive or induced, by which an organism evades, suppresses or tolerates the effects of its host organism's defense(s). Host defenses may be induced by the presence of the organism or may be preformed (e.g. physical barriers). The host is defined as the larger of the organisms involved in a symbiotic interaction.

I am no longer sure that this term is correctly named, as there are situations where the symbiont induces host defenses, but the def of 'response to host defenses' only covers the "negative" aspects of the response. Perhaps 'response to host defenses' should be used as a term to encapsulate modification/modulation of host defenses?

As yet I don't have any suggestion for a new name for 'response to host defenses', unfortunately!

Symbiont defenses

I am just contemplating adding terms for the following:

  • modulation by organism of symbiont defense response
    • modulation by organism of symbiont inflammatory response
    • modulation by organism of symbiont innate immunity

The first one is OK, but I'm not sure about the second and third. Are there/might there be symbioses out there where the smaller partner is a multicellular organism with inflammatory responses and innate immunity which the host species regulates in some way? Most of the symbioses between larger organisms seem to be more behavioural...

Innate immunity

At the moment our terms refer to 'innate immunity', whereas in the main GO, they talk about 'innate immune response'. Is it OK to change the terms to that string instead, e.g. modulation of host innate immune response

Trudy

I see no reason why we cannot use “innate immune response” in place of innate immunity.

Web definitions of immune response: a physiological response in humans and higher animals to defend the body against the introduction of foreign material.

Web definitions of immunity: unsusceptibility-the state of not being susceptible or a condition in which an organism can resist disease.

The word "immunity" connotes the state and "immune responses" refer to the reactions triggered by the foreign body to get the host into a state of immunity so it really depends on the context in which the phrase is being used.

I think whichever one is chosen, the other should be made a synonym or better still be included in the definition as in “innate immune response (sensu Viridiplantae)” in the main GO which is copied below:

innate immune response (sensu Viridiplantae) GO:0002226 Definition:The process of the innate immunity as in, but not restricted to, green plants and algae (Viridiplantae, ncbi_taxonomy_id:33090). Innate immune responses are defense responses mediated by germline encoded components that, in plants, directly recognize components of potential pathogens.

Any other thoughts???

Acquisition of nutrients from host

...is defined as

"The production of structures and/or molecules in an organism that are required for the acquisition and/or utilization of nutrients obtained from its host. The host is defined as the larger of the organisms involved in a symbiotic interaction."

How are we going to differentiate "formation by organism of specialized structure for nutrient acquisition from host" from this term? Is the def for "acquisition of nutrients from host" too detailed?

Michelle

Well, it seems an example of two things that fall under the parent term would be haustoria formation and hemolysin. The haustoria is a structure for gaining nutrients, while hemolysin is a molecule produced by the pathogen which causes nutrients to be dumped into the environment which the pathogen then slurps up - no specialized structures needed. So I think the "formation by organism of specialized...." term is correctly a more specific child of the parent. There could also be "cytolysis of host cells for the purpose of nutrient acquisition" as another child. I don't think we necessarily need such a term, and concurrent annotations should be able to handle it, but I am just trying to illustrate what I mean.

Trudy

Acquisition of nutrients from host

I see this term as the process of acquiring nutrients which is different from the formation of the structures through which the symbionts acquire the nutrients but then the latter is incorporated in the definition of the term thus fusing two separate processes into one.


The primary role of most of these structures, the haustorium, syncytium, arbuscules etc is to acquire nutrients from the hosts so I see why in an earlier term development effort, even though the term name is specified as the acquisition of nutrients from host, the definition was made to include the formation of the structures.

In my opinion, which was further supported from discussions with Brett, Marcus and Tsa-Tsieng, we should have “Formation of specialized nutrient absorption structures and macromolecules” housed under two parents as detailed below:


Modification of host morphology and physiology

        Formation of specialized nutrient absorption structures and macromolecules
                   Formation of arbuscules for nutrient absorption/acquisition from host
                   Formation of haustoria for nutrient absorption/acquisition from host
                   Formation of haustoria for nutrient absorption/acquisition from host sensu Viridiplantae
                   Formation of syncytium for nutrient absorption/acquisition from host
                   Formation of symbiosome for nutrient absorption/acquisition from host
                   Formation of siderophore for nutrient absorption/acquisition from host


Acquisition of nutrients

       Formation of specialized nutrient absorption structures and macromolecules
                  Formation of arbuscules for nutrient absorption/acquisition from host
                  Formation of haustoria for nutrient absorption/acquisition from host (sensu oomycetes and 
                  Formation of haustoria sensu for nutrient absorption/acquisition from host (sensu Viridiplantae)
                  Formation of syncytium for nutrient absorption/acquisition from host
                  Formation of symbiosome for nutrient absorption/acquisition from host
                  Formation of siderophore for nutrient absorption/acquisition from host







Definitions: Formation of specialized nutrient absorption structures and macromolecules

Defn: The production of structures and/or molecules in an organism that are required for the acquisition and/or utilization of nutrients obtained from its host. The host is defined as the larger of the organisms involved in a symbiotic interaction (note: are siderophores produced in the host)

Acquisition of nutrients from host Defn:The process of acquisition and/or utilization of nutrients by symbionts from its host. The host is defined as the larger of the organisms involved in a symbiotic interaction

Formation of arbuscules:

Source: Wikipedia

            Harrison M.J. Annu. Rev Microb:

Defn:The formation of highly branched structures in the parenchyma of plant cells by symbionts for acquisition of nutrients from the host.

Formation of haustoria: Defn:The formation of specialized feeding structures in host characterized by invaginations inside the plasma membrane of the host cell resulting in the formation of an extrahaustorial membrane, the region between this and the fungal membrane referred to as the extrahaustorial matrix.


Formation of haustoria (sensu Viridiplantae): The formation of globular shaped organs developed in parasitic plants for acquiring nutrients from the host; as in, but not restricted to, parasitic plants (Viridiplantae, ncbi_taxonomy_id:33090).


Formation of syncytium: Source: Niblack et al . Annu Rev Phytopath 2006:44:283-303

Defn: The formation of a system of highly modified host cells from which the symbiont (cyst nematode) feeds within the host (plant root).

Formation of symbiosome:

Source:Taken from component term symbiosome in main GO ontology and modified to a process term

The formation of a double-enveloped cell compartment, composed of an endosymbiont with its plasmalemma (as inner envelope) and a non-endosymbiotic outer envelope (the perisymbiontic membrane).


Formation of siderophore

Source: Wikipedia Defn: The formation of iron chelating compounds, many of which are nonribosomal petides secreted by the symbiont to dissolve Fe3+ ions as soluble Fe3+ complexes.



Note: 1.Syncytium formation is already in the main ontology: GO:0006949

Definition:The formation of a syncytium, a mass of cytoplasm containing several nuclei enclosed within a single plasma membrane. Syncytia are normally derived from single cells that fuse or fail to complete cell division.


2.Note that there are other kinds of syncytium formation but these have been accommodated under different terms in the main ontology namely:

            GO:0006949 : syncytium formation ( 2 )
                   GO:0000768 : syncytium formation by plasma membrane fusion ( 1 )
            GO:0006949 : syncytium formation  ( 2 )
                  GO:0000769 : syncytium formation by mitosis without cell division ( 0 )


3. The process of haustoria formation in fungi and oomycetes is different from that in parasitic plants thus a sensu designation was incorporated.

4. Where passage of nutrients is from symbionts to host, the term acquisition of nutrients from symbionts (which is already in the ontology) can be used but the definition of that term should also be changed to infer acquiring and utilizing nutrients only.

      • Could work on the definitions a bit more but thought to throw the general idea out there

Entry of organism into host cell by promotion of host phagocytosis

def: "The invasion by an organism of a cell of its host organism by utilizing the host phagocytosis mechanism."

Just to check - does this term mean that the organism upregulates host phagocytosis?


Michelle

Yes, at least that was my understanding.

Recognition of other organism during symbiotic interaction

This is defined as "The specific processes that allow an organism to detect the presence of a second organism via physical or chemical signals, where the two organisms are in a symbiotic interaction.".

Could this be a standard detection term? The std def for detection terms is:

The series of events in which a [...] stimulus is received by a cell and converted into a molecular signal.

or is recognition more of an organismal-level process?

I was just wondering as it would be nice to have a structure that mimics the main ontology, i.e.

response to other organism

  • detection of other organism

Induction terms

At the moment, under positive regulation, we have various 'induction' and 'activation' terms. What specifically should these terms mean? Are they induction as in kicking off an inactive process, or are the induction meaning general positive regulation, i.e. activating an inactive process and perpetuating or upregulating an existing process? The terms in question are:

  • GO:0052103 activation by organism of induced systemic resistance in host
  • GO:0052104 activation by organism of systemic acquired resistance in host
  • GO:0052030 induction by organism of host apoptotic programmed cell death
  • GO:0052065 induction by organism of host calcium ion flux
  • GO:0044416 induction by organism of host defense response
  • GO:0052105 induction by organism of host defensive cell wall thickening
  • GO:0052063 induction by organism of host nitric oxide production
  • GO:0012504 induction by organism of host non-apoptotic programmed cell death
  • GO:0052062 induction by organism of host phytoalexin production
  • GO:0052044 induction by organism of host programmed cell death
  • GO:0052064 induction by organism of host reactive oxidative species production
  • GO:0052101 induction by organism of host resistance gene-dependent defense response
  • GO:0052033 pathogen-associated molecular pattern dependent induction by organism of host innate immunity

Michelle

I seem to recall that for the induction terms we meant "kicking off an inactive process" and for upregulating we used "enhancement" however, I am not sure that we put in "enhancement" terms everywhere we needed them. We may need to create analagous enhancement terms for many of the induction terms.

Protein secretion systems

We've got the terms for modification of morphology and physiology using substances secreted by various types of secretion systems. Are these systems only found in symbionts, or might there be symbioses where the host organism had type II / III / IV (i.e. a bacterium was the host)? Also, we've got the term names as follows:

  • GO:0052049 interaction with host via protein secreted by type III secretion system
  • GO:0052050 interaction with host via substance secreted by type IV secretion system
  • GO:0052051 interaction with host via protein secreted by type II secretion system

Should these all be "... *protein* secreted by type ..."? Do other substances ever get secreted by these systems?

T4SS secretes protein and DNA (Donghui Li)

Three distinct secretion pathyways have been studied in plant pathogens.

The Type II secretion systems (T2SS) exports enzymes that are involved in degrading the plant cell wall, including pectinases, endo-glucanases and cellulases.

T3SS is the most widely studied secretion system in plant pathogens. Pathogens use T3SS to inject effectors (proteins) into the host cell. There is a great diversity of effectors; they have diverse enzymatic activities. Bacterial effectors have a prominent role in promoting the virulence in plants.

The T4SS has a critical role in the pathogenesis of Argobacterium and its capacity to form galls on plants. The T4SS mediates the trafficking of bacterial proteins and DNA into the plant cell. The bacterial DNA is integrated into the host genome to produce hormones that modify the phsyiology of plants.

Many pathogens rely on multiple secretion systems. For example, several strains of Xanthomonas have T2SS, T3SS and T4SS.

Based on the above discussion, it is clear that the use of 'substance' instead of 'protein' for T4SS is appropriate: T4SS secretes both protein and DNA, while T2SS and T3SS only secrete proteins.

Ref: Abramovitch et al (2006) Nature Reviews Molecular Cell Biology, 7:601-611.


Trudy

I would like to suggest the use of macromolecules instead of substance. Substance is too general a word. To support my stance on this, the definition of macromolecules and its usage in the context of the T4SS which Donghui rightly said secretes proteins and DNA can be found below:

Source: Wikipedia Macromolecule is defined as: A macromolecule is a large molecule with a large molecular mass, but generally the use of the term is restricted to polymers and molecules which structurally include polymers. Many examples come from biology and in particular biochemistry. In case of "biomacromolecules" or biopolymers, there are proteins, carbohydrates, nucleic acids (such as DNA), and lipids (fat).

In the literature nucleic acids and proteins are jointly referred to as macromolecules. For eg. Christie et al: 2005. Annu. Rev. Microbiol.2005. 59:451-485

           PMID:16153176

“In the T4SS , VirB11 is a member of a large family of ATPases associated with systems dedicated to secretion of macromolecules” (proteins and DNA).

Protein secretion systems (again)

Def of "modification by organism of host morphology or physiology via secreted substance":

The process by which an organism effects a change in the structure or function of its host organism, mediated by a substance secreted by one of the organisms.

Is this supposed to be suitable for referring to either host- or symbiont-secreted substances, or is it supposed to be specific to the organism secreting the substance (i.e. the symbiont in this case)?

MAPK pathways

At the moment, we have regulation of the defense-related MAPK signalling pathways as an is-a of regulation of ethylene-mediated defense response. I vaguely remember discussing that but I just want to check it's correct.

Trudy

Having "regulation of the defense-related MAPK signalling pathways" as a child of "regulation of ethylene-mediated defense response" violates the true path rule. Suggestion as to how these terms ought to be placed in the hierachy can be found below.


Modulation of host morphology and physiology

  Modulation by symbiont of host signal transduction pathway
     Modulation by symbiont of host protein kinases

Modulation of host morphology and physiology

  Modulation by symbiont of host defense responses
     Modulation by symbiont of defense related signalling pathways
        Modulation by symbiont of defense-related protein kinases
            Regulation/Modulation by symbiont of the defense-related MAPK signalling pathways
            Regulation/Modulation by symbiont of ethylene-mediated signalling pathways


All other types of protein kinases besides MAPK induced during the host-microbe intearction can be listed as children of "Modulation by symbiont of defense-related protein kinases".

Avoidance, Evasion and Tolerance, oh my!

I'm trying to work out a systematic way to deal with the terms under 'response to ... defenses', because at the moment, the terms have various names (evasion, evasion and tolerance, suppression, avoidance, response to, etc.) and the defs all seem to differ. This is the current structure (I've used a generic 'org' instead of spelling out all the host / symbiont / other organism terms):

  • response to [org] defenses
    • avoidance of [org] defenses
      • evasion or tolerance of [org] defenses
        • evasion by virus of host defenses
          • child terms include suppression of host processes
        • evasion or tolerance of [org] defense response
          • evasion or tolerance of [org] immune response
            • active evasion terms
            • passive evasion terms
            • evasion or tolerance of [org] oxidative burst / [org] phytoalexins / [org] NO
      • suppression of [org] defenses
    • modulation of [org] defense response

I would like to try to work out what we're actually meaning by "evasion", "tolerance" and so on.


  • "passive evasion" is defined as a process by which an organism deals with a defense response without affecting the other organism
  • "active evasion" is a process by which an organism deals with a defense response and affects the other organism into the bargain. It is not clear
  • "tolerance" isn't used on its own, so I am not sure what it represents
  • "suppression" seems to be very similar, if not identical, to "negative regulation" - i.e. stopping a process, impeding a process, or preventing an inactive process from starting.
  • "avoidance" seems to be the conjunction of "tolerance", "evasion" and "suppression"

Some of the term defs mention "constitutive" and "induced" processes (the avoidance terms), and others talk about "active" and "passive" (evasion or tolerance terms). I am not sure whether "active" and "passive" here means the same as "active evasion" and "passive evasion".


This is how I have been thinking of defenses and the defense response:

  • "defenses" applies to everything that an organism has developed over its lifespan and through evolution to deal with threats.
  • you can separate defenses into two types, structural defenses and defensive processes. I *think* this correlates with constitutive and induced defenses (aka the defense response). I can't think of any constitutive defenses that are a GO process, rather than just a protein sitting there holding the cell wall together.
  • structural defenses can't harm you, so the only thing you're likely to do to them is to attack them
  • the defense response of the other organism is likely to harm you in some way. There are three ways you could deal with this:
  1. build up fortifications to protect yourself against the effects of the other organism's process (e.g. cell wall)
  2. neutralize the effects of the other organism's process (e.g. detoxifying harmful chemicals)
  3. stop the other organism from performing the process

No. 1 is your structural defenses. They are constitutive and passive, and they can't be represented by a GO process term (I believe). No. 2 and 3 are your 'defense response'.

So your response to the defenses of the other organism could be split up thus:

response to [org] defenses
[i] modification of [org] defenses
---[i] physical modification of [org] defensive structures
---[i] modulation of [org] defense response (#3)
[i] response to [org] defense response
---[i] modulation of [org] defense response (#3)
---[i] examples of neutralizing the effects of the other org's defense response (#2)

No. 2 would include the new terms like 'evasion or tolerance of [org] phytoalexins'.

From this perspective, 'suppression of [org] defenses' doesn't make much sense, as you can't suppress a physical structure. I think it would be better to alter this term to be 'suppression of [org] defense response'.

Is 'tolerance' supposed to represent the passive / structural defenses?

[this is unfinished at the moment due to temporary loss of mind]

Later thoughts

For concepts where we have both modulation terms and evasion/tolerance terms, I've grouped them together under a 'response to' term, e.g.

response to [org] phytoalexin production
[i] evasion or tolerance of [org]-produced phytoalexins
[i] modulation of [org] phytoaxelin production
---[i] positive regulation of [org] phytoalexin production
------[i] induction of [org] phytoalexin production

I really need to know, for the 'avoidance' and the 'evasion or tolerance' terms, exactly what is being meant. I am wondering if the 'avoidance' terms could themselves be avoided. Hmmmm.

Trudy

Amelia, this is what I ended up with in response to the above issue after discussions with Brett and Marcus

Altering the effectiveness of host defenses

  Reducing effectiveness of host defenses
       Avoidance of host defenses
            Evasion of host defenses
            Suppression of host defenses
       Tolerance of host defenses
       Modification of host defenses
            Modification of defensive structures
                Physical modification of defensive structures
                Biochemical modification of defensive structures
            Modification of defensive compounds and chemicals
                Biochemical modification of defensive structures
  Enhancing effectiveness of host defenses


Definitions and other child terms can be provided later but this will serve as the basic structure. Note that

all is_a relationships

I'm interested in the rationale for building this portion of the ontology with terms that represent collections of processes rather than global processes that are then broken down into part_of subprocesses. Is there a plan to break these terms down into parts at some point? It seems for the nervous system development portion of the ontology we took the converse approach. We considered global processes and broke them down into parts. We are now going back and adding the is_a parents that will eventually have is_a relationships to the more 'primitive' terms in the process ontology.

Terms recommended for obsoletion

Trudy

Since the new terms have not been committed to the GO yet, I am assuming terms that are marked for obsoletion can be eliminated completly... Am I right Amelia?? I created this section to put any such terms I come across as I go through all the new terms in the obo file Amelia posted on Sourceforge for download.


GO:0052435 modulation by organism of defense-related symbiont MAP kinase-mediated signal transduction pathway

Reason: The way I understand this is the host modulating MAP kinase mediated signal transduction pathway in the symbiont. This is not biologically true. In some cases, such as "acquisition of nutrients from host", the reverse occurs. For example, in the mutualistic relationship formed between arbuscular mycorrhizal (AM) fungi and vascular flowering plants, the host receives all its phosphorous from the fungal symbiont whilst the fungus obtains its carbon source from the plant. This is not the case for:

GO:0052080 modulation by organism of defense-related host MAP kinase-mediated signal transduction pathway

and

GO:0052435 modulation by organism of defense-related symbiont MAP kinase-mediated signal transduction pathway

Whilst the former is biologically sound, the latter is not


Similar terms for obsoletion include:

  • GO:0052395 induction by organism of defense-related symbiont nitric oxide production
  • GO:0052401 induction by organism of defense-related symbiont reactive oxygen species production
  • GO:0052398 induction by organism of symbiont phytoalexin production

These are just a few examples but there are a lot more in the draft...instead of listing them, I am sure Amelia can fish them out in the obo file with a keyword or with a script.

Modify definitions of these terms?????

Trudy

symbiosis, encompassing mutualism through parasitism

Definition: An interaction between two organisms living together in more or less intimate association. The term host is usually used for the larger (macro) of the two members of a symbiosis. The smaller (micro) member is called the symbiont organism. Microscopic symbionts are often referred to as endosymbionts. The various forms of symbiosis include parasitism, in which the association is disadvantageous or destructive to one of the organisms; mutualism, in which the association is advantageous, or often necessary to one or both and not harmful to either; and commensalism, in which one member of the association benefits while the other is not affected. However, mutualism, parasitism, and commensalism are often not discrete categories of interactions and should rather be perceived as a continuum of interaction ranging from parasitism to mutualism. In fact, the direction of a symbiotic interaction can change during the lifetime of the symbionts due to developmental changes as well as changes in the biotic/abiotic environment in which the interaction occurs.

I find myself wondering lately about this part of the definition The smaller (micro) member is called the symbiont organism in this definition. If you consider parasitic plants and their hosts, it is possible that the parasitic plant, being the symbiont in this relationship, could be larger or same size as its host.

New Terms

Michelle_Trudy_Candace@PAG

Commensalism, Mutualism: Add as siblings to pathogenesis