Primary-Source Evidence Overview

Nuclear Condensates: Assembly, Composition and Evidence

Primary evidence distinguishes model demixing, selective composition, nucleolar behaviour, PML organization and restricted RNA-processing effects.

Nuclear Condensates_ Comprehensive Review.docx Body-specific evidence Evidence with context limits

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Selected nuclear-condensate evidence

This overview compares defined examples of collective molecular assembly, selective composition, nucleolar material behaviour, PML organization and a restricted RNA-processing phenotype. Their physical mechanisms and functional evidence are evaluated separately. The associated Word document is broader and has not received this appraisal.Evidence and interpretation: Li et al. (2012); Feric et al. (2016); Banani et al. (2016); Sahin et al. (2014); Małszycki et al. (2026); Itoh et al. (2021).

Defined interactions can produce demixing

Li et al. (2012) found concentration- and valency-dependent phase behaviour in purified multivalent interaction mixtures. Such systems show that defined molecular binding can generate collective demixing. They do not establish the mechanism of an endogenous nuclear focus solely because it is enriched or rounded.

Internal material behaviour can differ

Feric et al. (2016) combined Xenopus oocyte nucleolar observations with reconstitution of NPM1-rich and fibrillarin-rich condensed phases in an RNA-containing mixture. The two protein-rich phases coexist with surrounding solution and have different component/material behaviour. They are not a recreation of all three anatomical nucleolar compartments.

Selective composition within phases

Banani et al. (2016) measured client sorting within phase-separated model scaffolds. Recruitment depended on cognate interactions, scaffold composition and valency. Selectivity is therefore compatible with demixing; it does not imply nonspecific partitioning or independently prove phase separation in every endogenous compartment.

Assembly and retention are separate in a PML example

Sahin et al. (2014) distinguished oxidation-associated initial PML mesh assembly from subsequent SUMO/SIM-associated recruitment and retention of partners in cell models. These findings address related but distinct steps of organization; they are not a measurement of liquid coexistence throughout an entire PML body.

A restricted RNA-processing connection

Małszycki et al. (2026) reported impaired splicing and reduced expression of GC-rich genes with short introns after acute loss of SON/SRRM2 in human cells. This supports a particular processing dependence in that system. The direct functions of the removed proteins and loss of speckle architecture remain coupled; the result is not a phase-only perturbation or an equal effect on every transcript.

Scope boundaries

Disease-wide mechanisms, clinical outcomes, therapeutic recommendations and pathogen/viral manipulations are outside this overview. Those inherited topics are not validated by the selected cell/model evidence or by the separate associated document link.

Assay interpretation and evidence assessment

Itoh et al. (2021) found changes in chromatin motion and compaction in human cell models exposed to 1,6-hexanediol. Sensitivity to this perturbation must therefore be interpreted with its chromatin effects in mind. This observation is a specificity caution, not evidence that phase separation never occurs.

Molecular fluorescence recovery, component composition and phase coexistence describe different properties. The distinct component behaviour in Feric et al. (2016) and Banani et al. (2016) illustrates why a recovery curve or a single image should be interpreted alongside the other evidence rather than treated as a universal phase diagnosis.

The checked examples support particular demixing, sorting, material-property, assembly and processing findings. They do not establish one mechanism or one function for every nuclear condensate. Body identity, molecular components and biological context remain essential to the interpretation.Evidence and interpretation: Li et al. (2012); Feric et al. (2016); Banani et al. (2016); Sahin et al. (2014); Małszycki et al. (2026); Itoh et al. (2021).

Evidence context and limits

Li et al: Engineered multivalent SH3 and proline-rich-motif proteins and PTB/RNA reconstitution; valency-dependent phase diagrams; droplet/bulk partitioning; dynamic light scattering, SAXS, photobleaching and cryo-EM; additional HeLa puncta and nephrin/Nck/N-WASP reconstitution context. Descriptive primary observations/modelling at the recorded source depth; no operational procedures reproduced. Sol–gel coupling is the authors’ qualified interpretation, not a directly measured universal percolation threshold or nuclear material state. The page preserves likely and confines claims to reconstituted systems.Evidence and interpretation: Li et al. (2012).

Banani et al: Purified engineered polySUMO/polySIM, polySH3/polyPRM, and PTB/polyUCUCU scaffold pairs with fluorescent low-valency clients; phase diagrams, partition coefficients, binding mutants, valency series, and mass-action modeling. Current page claims stay with these engineered systems. Descriptive primary observations/modelling at the recorded source depth; no operational procedures reproduced. SUMO/SIM mutant/GFP controls are not described as controls for every scaffold pair. Does not show all endogenous bodies demix or assign a phase mechanism solely from enrichment.Evidence and interpretation: Banani et al. (2016).

Feric et al: Amplified extrachromosomal nucleoli in X. laevis oocytes, fluorescent subcompartment markers, actin perturbation to permit fusion; purified NPM1/FIB1/rRNA mixtures; FRAP and embedded 50-nm probe microrheology; ATP depletion in oocyte and mammalian-cell conditions. Descriptive primary observations/modelling at the recorded source depth; no operational procedures reproduced. Two protein-rich phases are not a reconstitution of all three nucleolar compartments or a universal nuclear-body model. Aging and ATP observations are component/condition-specific; no standalone FRAP-to-solid-state inference.Evidence and interpretation: Feric et al. (2016).

Sahin et al: Mouse fibroblast and human-cell PML models, with PML/SUMO interaction comparisons. Cell imaging, biochemical assembly comparisons, partner localization and retention. Initial PML assembly and subsequent SUMO/SIM partner retention are distinct cell-model observations, not a whole-body liquid-coexistence measurement.Evidence and interpretation: Sahin et al. (2014).

Itoh et al: Human cell-line chromatin assessed through fluorescent histone markers. This is not a neuronal FUS study. Single-nucleosome motion measurements and chromatin imaging. Chromatin motion/compaction effects in human cell models; no neuronal FUS inference or mechanism diagnosis of every condensate.Evidence and interpretation: Itoh et al. (2021).

Małszycki et al: Human cells with acute SON/SRRM2 loss; precise engineered line details not independently appraised here. Descriptive expression and RNA-splicing comparisons reported in the primary Abstract. Abstract depth; no timing/quantitative effect size/method controls or isolated architectural causality validated.Evidence and interpretation: Małszycki et al. (2026).

Nucleolar mechanics requires a specimen-specific measurement

Evidence update · 12 October 2026

A 2025 aspiration study found different mechanical responses of the granular and DFC/FC nucleolar regions, with RNA degradation changing the latter. Measurements used transcriptionally active Xenopus nucleoli inside extracted germinal vesicles. Those specimen and RNA dependencies constrain extrapolation to an intact mammalian nucleus or a universal material state. Micropipette aspiration reveals differential RNA-dependent viscoelasticity of nucleolar subcompartments (2025).

Primary sources for this update

Source access: primary abstract and main Results specimen description. The study-specific findings above do not certify associated Word drafts, raw data or every proposed nuclear-body mechanism.

Primary references

  1. Li et al. (2012). Phase transitions in the assembly of multivalent signalling proteins. Nature 483, 336–340. DOI: 10.1038/nature10879.
  2. Banani et al. (2016). Compositional Control of Phase-Separated Cellular Bodies. Cell 166, 651–663. DOI: 10.1016/j.cell.2016.06.010.
  3. Feric et al. (2016). Coexisting liquid phases underlie nucleolar sub-compartments. Cell 165, 1686–1697. DOI: 10.1016/j.cell.2016.04.047.
  4. Sahin et al. (2014). Oxidative stress-induced assembly of PML nuclear bodies controls sumoylation of partner proteins. Journal of Cell Biology 204, 931–945. DOI: 10.1083/jcb.201305148.
  5. Itoh et al. (2021). 1,6-hexanediol rapidly immobilizes and condenses chromatin in living human cells. Life Science Alliance 4, e202001005. DOI: 10.26508/lsa.202001005.
  6. Małszycki et al. (2026). Nuclear speckles enable processing of RNA from GC-rich isochores. Cell 189, 2024–2039.e25. DOI: 10.1016/j.cell.2026.01.011.

Primary source access depth and inference limits are recorded in the appraisal ledger. This appraisal covers the revised HTML text and reference identity; it excludes the associated Word document, exhaustive literature coverage, raw-data reanalysis and detailed procedures.