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Biomolecular condensates have emerged as an important subcellular organizing principle 1 . Replication of many viruses, including human respiratory syncytial virus (RSV), occurs in virus-induced compartments called inclusion bodies (IBs) or viroplasm 2,3 . IBs of negative-strand RNA viruses were recently shown to be biomolecular condensates that form through phase separation 4,5 . Here we report that the steroidal alkaloid cyclopamine and its chemical analogue A3E inhibit RSV replication by disorganizing and hardening IB condensates. The actions of cyclopamine and A3E were blocked by a point mutation in the RSV transcription factor M2-1. IB disorganization occurred within minutes, which suggests that these molecules directly act on the liquid properties of the IBs. A3E and cyclopamine inhibit RSV in the lungs of infected mice and are condensate-targeting drug-like small molecules that have in vivo activity. Our data show that condensate-hardening drugs may enable the pharmacological modulation of not only many previously undruggable targets in viral replication but also transcription factors at cancer-driving super-enhancers 6 .RSV is a major cause of respiratory illness in young children, the older people and individuals who are immunocompromised worldwide 7,8 . Currently, multiple targets are pursued for the development of a safe and effective therapy to treat RSV infections 9 .In infected cells, RSV induces the formation of cytoplasmic IBs, in which nucleoprotein (N), phosphoprotein (P), polymerase L, the transcription factor M2-1 and viral genomic RNA are concentrated. We recently demonstrated that IBs are 'viral factories' in which viral RNA synthesis occurs 3 . The morphology of IBs suggests that they are condensates formed by liquid-liquid phase separation (LLPS). A recent study showed that N and P were sufficient to drive the formation of pseudo-IB condensates through LLPS in vitro, both in cells and in biochemical assays 10 . However, these N-P pseudo-IB condensates are not functional, as they do not shelter RNA synthesis and do not reflect the complexity of IBs in virus-infected cells, which have multiple compartments. Strikingly similar in size and phase organization to the nucleolus condensate 11 , RSV IBs are multiphasic and contain a sub-compartment called the IB-associated granule (IBAG), which is composed of newly synthesized viral mRNA and M2-1 3,12 . Condensates have emerged as an important subcellular organizing principle 1 . An important question in anti-viral drug developmentand medicinal chemistry more generally-is whether these condensates are druggable. In principle, a drug that dissolved or hardened would prevent viral replication. Neither mechanism has yet been reported. Chemical analogues without hedgehog antagonismWe previously identified the hedgehog (HH) pathway antagonist cyclopamine (CPM) as a potent inhibitor of RSV replication 13 . Inhibition of Sonic hedgehog (SHH) signalling is an unwanted feature of CPM as an RSV inhibitor. On the basis of the binding model of the Smoothe...

To elucidate the phytohormonal basis of the feedback regulation of leaf senescence induced by potassium (K) deficiency in cotton (Gossypium hirsutum L.), two cultivars contrasting in sensitivity to K deficiency were self- and reciprocally grafted hypocotyl-to-hypocotyl, using standard grafting (one scion grafted onto one rootstock), Y grafting (two scions grafted onto one rootstock), and inverted Y grafting (one scion grafted onto two rootstocks) at the seedling stage. K deficiency (0.03mM for standard and Y grafting, and 0.01mM for inverted Y grafting) increased the root abscisic acid (ABA) concentration by 1.6- to 3.1-fold and xylem ABA delivery rates by 1.8- to 4.6-fold. The K deficiency also decreased the delivery rates of xylem cytokinins [CKs; including the zeatin riboside (ZR) and isopentenyl adenosine (iPA) type] by 29–65% and leaf CK concentration by 16–57%. The leaf ABA concentration and xylem ABA deliveries were consistently greater in CCRI41 (more sensitive to K deficiency) than in SCRC22 (less sensitive to K deficiency) scions under K deficiency, and ZR- and iPA-type levels were consistently lower in the former than in the latter, irrespective of rootstock cultivar or grafting type, indicating that cotton shoot influences the levels of ABA and CKs in leaves and xylem sap. Because the scions had little influence on phytohormone levels in the roots (rootstocks) of all three types of grafts and rootstock xylem sap (collected below the graft union) of Y and inverted Y grafts, it appears that the site for basipetal feedback signal(s) involved in the regulation of xylem phytohormones is the hypocotyl of cotton seedlings. Also, the target of this feedback signal(s) is more likely to be the changes in xylem phytohormones within tissues of the hypocotyl rather than the export of phytohormones from the roots.

The fluorescence recovery after photobleaching technique (FRAP) was used to measure the diffusion coefficients (D) of fluorescein isothiocyanate (FITC)-dextrans in diluted, semidiluted, and concentrated hyaluronic acid solutions. The decrease of the diffusion coefficients as the hyaluronic acid concentration increases was consistent with the universal scaling equation D/Do = exp(-oc'). The diffusion experiments were carried out to obtain structural information on the transient network structure in hyaluronic acid solutions. On the basis of scaling laws, the concentration dependence of the average mesh size £ was determined as £ ~c-0•68*0•07. Additionally, the average £-values were estimated. The concentration dependence of £ and the absolute vlaues for £ were compared with structural information obtained from rheological experiments performed on hyaluronic acid solutions. Even though accurate results were found for the concentration dependence of £, there was a semiquantitative relation between the £-values estimated from the diffusion experiments and the rheological experiments.

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