| Study/system | Key quantitative results | Implication/application | Publication date | URL |
|---|---|---|---|---|
| Qin et al. 2024 — *Nitrososphaera viennensis* EN76 culture physiology and regulation | In *N. viennensis*, **ureC (NVIE_014740)** and adjacent **ut (NVIE_014780)** transcripts changed by ~**10-fold within 24 h** after switching between urea and ammonia; apparent substrate affinities showed **Km(app) ammonia = 0.68 ± 0.16 µM** versus **Km(app) urea = 8.97 ± 1.27 µM**, with ~**10-fold lower specific affinity** for urea; ammonia-grown cells given **10 µM urea** showed no immediate O2 uptake until ammonia depletion, indicating repression of urea use during ammonia growth (pqac-00000000, pqac-00000002, pqac-00000021) | Shows that urease-linked urea oxidation in soil AOA is inducible but typically secondary to ammonia use; useful for modeling nitrogen-source competition in soils and bioreactors and for interpreting ureC expression as a condition-dependent, not constitutive, marker | Jan 2024 | https://doi.org/10.1038/s41564-023-01593-7 |
| Zhao et al. 2023 — soil Nitrososphaeria resource acquisition | Across 12 major soil Nitrososphaeria lineages, **85.7–89.8%** of AOA in surveyed soils were estimated to encode **urease** based on **ureC** relative to **amoA/rpoB** reads (pqac-00000020) | Indicates that urea use is a widespread niche-defining trait in soil archaeal nitrifiers, supporting application of ureC-based analyses in predicting nitrogen acquisition strategies and coexistence patterns in agricultural and natural soils | Aug 2023 | https://doi.org/10.1038/s41396-023-01493-y |
| Arandia-Gorostidi et al. 2024 — dark ocean urea assimilation and nitrification | Regional deep-sea metagenomes estimated **ureC in 39% of cells**; global datasets estimated **10–46%** of deep-sea cells carry ureC (median ~**36%**); on average **25%** of deep-sea cells assimilated urea-derived N, or **60% of detectably active cells**; urea concentrations ranged **21 nM–1.1 µM**; peak nitrification at **150 m** reached **16.1 nmol N L^-1** from ammonium and **11.8 nmol N L^-1** from urea; urea-based nitrification rates were statistically indistinguishable from ammonia-based rates at sampled depths; urea-supported chemoautotrophic C fixation was estimated at **1.4–8.8 mg C m^-2 d^-1**, ~**5–7%** of sinking POC at study sites (pqac-00000013, pqac-00000014, pqac-00000015, pqac-00000016) | Demonstrates that ureC-bearing archaeal and bacterial communities substantially support deep-ocean N cycling and some chemoautotrophic production; relevant to ocean biogeochemical models and to interpreting ureC as an ecologically important marker beyond surface waters | Jan 2024 | https://doi.org/10.1093/ismejo/wrae230 |
| Hollibaugh et al. 2024 preprint / 2023 Southern Ocean study — polar nitrification | Thaumarchaeota-associated **ureC** abundance was variable by water mass, with highest mean **1.2 × 10^6 copies L^-1** in CDW; mean **ureC/rrs ≈ 0.14** overall; ammonia oxidation averaged **10.9 nmol L^-1 d^-1** versus urea oxidation **2.6 nmol L^-1 d^-1** (or **1.5 nmol L^-1 d^-1** excluding high outliers); AO and UO differed significantly among water masses (**p = 0.008**) (pqac-00000017) | Suggests urea contributes a measurable but generally smaller share of nitrification in polar waters; useful for constraining regional nitrogen-cycle budgets and for evaluating when ureC abundance does or does not predict active urea-based nitrification | Feb 2024 preprint / 2023 study | https://doi.org/10.1101/2024.02.20.581251 |


*Table: This table summarizes key 2023–2024 quantitative findings on ureC/urease and urea-based nitrification or assimilation in archaeal nitrifiers across culture, soil, and ocean systems. It highlights the most useful recent statistics for functional interpretation and environmental application.*