TCA cycle and the Fe/S-dependent steps. The review's Figure 4 renders this as a linear chain from glucose to oxaloacetate with no OAA-to-citrate closure, which the draft's own margin note flags. The closure matters: it is what shows that the two Fe/S-dependent steps throttle flux around the whole loop instead of interrupting a line. Aconitase and succinate dehydrogenase are the review's sentinel nodes and are annotated once on QBM-01, referenced here rather than re-declared, so one entity cannot carry different evidence on two maps. The citrate-to-isocitrate ratio is the most direct available in-vivo proxy for Fe/S cluster integrity and is worth measuring in any near-null-field metabolomics experiment. Note that plant mitochondrial fumarase is a class-II enzyme with no Fe/S cluster, unlike the class-I bacterial form it is sometimes confused with. Derived from: Figure 4 of Porterfield & Barker, "Plant Responses to Near-Null Magnetic Fields" — redrawn as a closed cycle, expanded to gene level and bound to Arabidopsis loci structural_context CHEBI:15351 C00024 structural_context CHEBI:16452 C00036 structural_context AT1G53240 1.1.1.37 structural_context AT2G44350 2.3.3.1 structural_context CHEBI:16947 C00158 iron_sulfur_4Fe4S 57Fe 33S AT4G35830 AT4G26970 AT2G05710 4.2.1.3 The review nominates aconitase as the sentinel of Fe/S integrity, and the biochemistry supports it: the exposed cluster iron makes aconitase the first TCA activity to fall under oxidative stress, so it reports cluster damage before anything else does. Precisely because aconitase responds to any oxidative insult, a change under NNMF would NOT by itself implicate a magnetic mechanism. It is a sensitive readout and a poor discriminator; it needs a paired ROS-independent control. structural_context CHEBI:16087 C00311 structural_context AT4G35260 AT2G17130 1.1.1.41 iron_sulfur_4Fe4S radical_pair_donor 57Fe 33S 1H AT2G20860 2.8.1.8 A radical-SAM enzyme generating a 5'-deoxyadenosyl radical from a [4Fe-4S] cluster — genuine organic radical chemistry on an iron-sulfur centre, which is the tightest coupling of the review's two proposed mechanisms found anywhere in primary metabolism. Its product lipoylates pyruvate dehydrogenase and the 2-oxoglutarate dehydrogenase complex, so a defect propagates straight into TCA flux. The radical is generated inside the active site and quenched within one turnover; whether a spin-correlated pair with a long enough lifetime to be field-sensitive ever forms is untested. flavin_semiquinone iron_sulfur_2Fe2S iron_sulfur_4Fe4S iron_sulfur_3Fe4S ros_leak_site 1H 14N 57Fe 33S CHEBI:57692 AT5G66760 AT3G27380 AT5G40650 AT5G09600 AT2G46505 GO:0005749 1.3.5.1 Carries all three cluster types plus a covalent flavin, and sits at the junction the review nominates as the bottleneck — a change here propagates into both TCA flux and respiratory electron flow. structural_context AT2G47510 4.2.1.2 structural_context CHEBI:57945 CHEBI:57540 C00004 C00003 ros_leak_site CHEBI:18421 CHEBI:16240 AT3G10920 Near-null magnetic field exposure alters ROS-associated transcriptomic and metabolomic programmes in Arabidopsis. Reactive oxygen species and mitochondria jointly regulate seed germination, establishing the route from mitochondrial ROS to a developmental outcome. Not a magnetosensitive mechanism itself — it is the amplifier. A field effect too small to measure as a rate change can still register here, because ROS signalling is threshold-like. catalysis catalysis electron_transfer catalysis electron_transfer catalysis electron_transfer indirect_influence electron_transfer electron_transfer electron_transfer electron_transfer indirect_influence cofactor_insertion redox_feedback redox_feedback direct_influence