So about a week after getting to Arizona, I finally finished a reasonably thorough draft revision to a manuscript I'll call the 2018 seed-harvester ant paper, and sent it over to my hosts, who are coauthors on it, for their review and feedback.
Then, while in the transition phase between that and the next writing project, I had one of those thinking-out-loud conversations that went, "Oh yeah, of course the next writing project I should work on is the next paper that's closest to being ready to submit."
...That would be a leafcutter manuscript rather than the next seed-harvester paper (the "2021 seed-harvester ant paper").
...the only major downside being that switching from seed-harvesters to leafcutter ants is kind of a big intellectual shift, for me, at least. To wit, I spent a bunch of time last week just trying to get my leafcutter ant annotated bibliographies better organized (yes, that's bibliographies, plural), to identify where I need to brush up on the literature, and since then I've been spending a bunch of time trying to find and read any information I can about how fungi might respond to excess nitrogen (protein).
Half of the challenge tends to be just figuring out how to dial in on what my question actually is, to figure out how to search for sufficiently specific information related to my question. "All fungi" is FAR too broad; I really just want to learn about saprotrophs - and soil saprotrophs rather than wood saprotrophs, but often they get studied in the context of "soil microbiota," which will also always include ectomycorrhizal fungi and bacteria, okay, rightly so. But the thing is, the context of other microbes might actually be really important, seeing as most leafcutter ants grow their fungus gardens underground. They do keep their gardens immaculately clean, but there are still bacteria in the mix.
Out of the papers I found, I only finished reading the best of them yesterday and today - a review article from 2014 that basically laid out a great framework for thinking mechanistically about how soil microbial communities could and do respond to C, N, or P limitation (so interesting and cool*), and a fun paper from 2024 that helps to clarify that there are some systematic patterns to fungal fruiting body element content, related to both fungal evolutionary history and ecology. The latter is important for being able to assert that fungi regulate their body element composition homeostatically.
Things I'm still not entirely clear about: in soil microbial communities, when there's an abundance of nitrogen around, it sounds like basically "microbes" (presumably mostly bacteria rather than fungi) produce and excrete "mineralized" nitrogen (ammonium) - a form of nitrogen readily available to plants. This basically means plants will renege on their deal with ectomycorrhizal fungi and just get their nitrogen directly. In contrast, when nitrogen is limited, microbes are said to "immobilize" it, which basically means they hold onto it and put it to use in forms that are not directly accessible to plants. (that would lead plants to barter with fungi for nitrogen in exchange for some sweet photosynthesized sugar).
But: do fungi also mineralize nitrogen? If there's too much nitrogen around and not enough carbon, are fungi more likely to die by way of simply running out of energy (can't get to enough organic carbon), or from some form of nitrogen toxicity, perhaps related to having lower tolerance to high nitrogen and getting outcompeted by microbes with higher nitrogen tolerance?
That's what I still don't really know and can't fully conjecture about.
This line of speculative thinking will probably only contribute to 1-2 sentences in the Discussion section of the leafcutter ant manuscript, but on the other hand, it's fun and interesting to think about.
...And so only eventually have I been able to get back to working on a coauthor's feedback on the 2018 seed-harvester ant manuscript.
I wasn't quite expecting so much of this time to get devoted to the writing step of reading papers and learning things, but here I am.
*Responses differ depending on the limiting element/nutrient (out of C, N, and P), because the extracellular enzymes that these organisms secrete in order to obtain nutrients require nitrogen and energy (but not phosphorus!) to synthesize. Fungi and microbes don't appear to store appreciable amounts of nitrogen, but they DO stockpile phosphorus! If nitrogen is limiting, that will then favor organisms that can burn a bunch of energy to get N (consider N fixation, for instance). If C (energy) is limiting, that will favor more energetically-thrifty organisms. P limitation will favor organisms that can store and transport phosphorus from one place to another (fungal hyphae FTW!).
Then, while in the transition phase between that and the next writing project, I had one of those thinking-out-loud conversations that went, "Oh yeah, of course the next writing project I should work on is the next paper that's closest to being ready to submit."
...That would be a leafcutter manuscript rather than the next seed-harvester paper (the "2021 seed-harvester ant paper").
...the only major downside being that switching from seed-harvesters to leafcutter ants is kind of a big intellectual shift, for me, at least. To wit, I spent a bunch of time last week just trying to get my leafcutter ant annotated bibliographies better organized (yes, that's bibliographies, plural), to identify where I need to brush up on the literature, and since then I've been spending a bunch of time trying to find and read any information I can about how fungi might respond to excess nitrogen (protein).
Half of the challenge tends to be just figuring out how to dial in on what my question actually is, to figure out how to search for sufficiently specific information related to my question. "All fungi" is FAR too broad; I really just want to learn about saprotrophs - and soil saprotrophs rather than wood saprotrophs, but often they get studied in the context of "soil microbiota," which will also always include ectomycorrhizal fungi and bacteria, okay, rightly so. But the thing is, the context of other microbes might actually be really important, seeing as most leafcutter ants grow their fungus gardens underground. They do keep their gardens immaculately clean, but there are still bacteria in the mix.
Out of the papers I found, I only finished reading the best of them yesterday and today - a review article from 2014 that basically laid out a great framework for thinking mechanistically about how soil microbial communities could and do respond to C, N, or P limitation (so interesting and cool*), and a fun paper from 2024 that helps to clarify that there are some systematic patterns to fungal fruiting body element content, related to both fungal evolutionary history and ecology. The latter is important for being able to assert that fungi regulate their body element composition homeostatically.
Things I'm still not entirely clear about: in soil microbial communities, when there's an abundance of nitrogen around, it sounds like basically "microbes" (presumably mostly bacteria rather than fungi) produce and excrete "mineralized" nitrogen (ammonium) - a form of nitrogen readily available to plants. This basically means plants will renege on their deal with ectomycorrhizal fungi and just get their nitrogen directly. In contrast, when nitrogen is limited, microbes are said to "immobilize" it, which basically means they hold onto it and put it to use in forms that are not directly accessible to plants. (that would lead plants to barter with fungi for nitrogen in exchange for some sweet photosynthesized sugar).
But: do fungi also mineralize nitrogen? If there's too much nitrogen around and not enough carbon, are fungi more likely to die by way of simply running out of energy (can't get to enough organic carbon), or from some form of nitrogen toxicity, perhaps related to having lower tolerance to high nitrogen and getting outcompeted by microbes with higher nitrogen tolerance?
That's what I still don't really know and can't fully conjecture about.
This line of speculative thinking will probably only contribute to 1-2 sentences in the Discussion section of the leafcutter ant manuscript, but on the other hand, it's fun and interesting to think about.
...And so only eventually have I been able to get back to working on a coauthor's feedback on the 2018 seed-harvester ant manuscript.
I wasn't quite expecting so much of this time to get devoted to the writing step of reading papers and learning things, but here I am.
*Responses differ depending on the limiting element/nutrient (out of C, N, and P), because the extracellular enzymes that these organisms secrete in order to obtain nutrients require nitrogen and energy (but not phosphorus!) to synthesize. Fungi and microbes don't appear to store appreciable amounts of nitrogen, but they DO stockpile phosphorus! If nitrogen is limiting, that will then favor organisms that can burn a bunch of energy to get N (consider N fixation, for instance). If C (energy) is limiting, that will favor more energetically-thrifty organisms. P limitation will favor organisms that can store and transport phosphorus from one place to another (fungal hyphae FTW!).