Fishes of the genus Danio exhibit diverse pigment patterns that serve as useful models for understanding the genes and cell behaviors underlying the evolution of adult form. Among these species, zebrafish D. rerio exhibit several dark stripes of melanophores with sparse iridophores that alternate with light interstripes of dense iridophores and xanthophores. By contrast, the closely related species D. nigrofasciatus has an attenuated pattern with fewer melanophores, stripes and interstripes. Here we demonstrate species differences in iridophore development that presage the fully formed patterns. Using genetic and transgenic approaches we identify the secreted peptide Endothelin-3 (Edn3)—a known melanogenic factor of tetrapods—as contributing to reduced iridophore proliferation and fewer stripes and interstripes in D. nigrofasciatus. We further show the locus encoding this factor is expressed at lower levels in D. nigrofasciatus owing to cis-regulatory differences between species. Finally, we show that functions of two paralogous loci encoding Edn3 have been partitioned between skin and non-skin iridophores. Our findings reveal genetic and cellular mechanisms contributing to pattern differences between these species and suggest a model for evolutionary changes in Edn3 requirements for pigment patterning and its diversification across vertebrates.

Our image analysis approach enables insights into gut dynamics in a wide variety of developmental and physiological contexts and can also be extended to analyze other types of cell movements.

ers by interactions of FoxO3 with the chromatin-remodeling factor Brg1 and the TF Olig2, which are involved in control of OPC differentiation (14-16). Hence, central myelination failure is regulated by a noncanonical TLR4/AKT/FoxO3 signaling pathway utilized by bHAf to induce a tolerance-like state that selectively constrains OPC maturation and myelination. ResultsNeonatal hypoxic-ischemic WMI promotes MDa HA depolymerization. To investigate the status of MDa HA in chronic neonatal WMI, we employed our preterm-equivalent rat hypoxia-ischemia (H-I) model, which generates myelination failure and replicates key features of human WMI ( Figure 1A) (17). MDa HA turnover in the ECM after H-I was visualized with a biotinylated HA-binding protein (HABP) and costained with glial fibrillary acidic protein (GFAP) as a marker of WMI. Unlike in age-matched uninpro-myelination signal (13). This tolerance-like action of bHAf was mediated through TLR4 but not via CD44 or TLR2. As in TLR4-mediated IT, bHAf 's influence on myelination was reversible when MDa HA depolymerization was attenuated or bHAf was removed. AKT desensitization was similarly reversible in vivo in neonatal WMI. Moreover, bHAf actions were mediated via a noncanonical TRIF-dependent pathway, also involved in IT, rather than the canonical MyD88 arm of TLR4 signaling. AKT desensitization resulted in maturation-dependent activation of the FoxO3 transcription factor (TF), which selectively constrained preOL maturation in a bHAf-dependent fashion. A role for activated FoxO3 in human myelination failure was supported by selective localization of nuclear FoxO3 to OPCs in human preterm WMI and multiple sclerosis (MS) plaques. bHAf-mediated OPC maturation arrest appears to be regulated at the FoxO3 and myelin basic protein (MBP) promot- (Contralateral). Only the lesion group had a significant reduction in HA recovery. (E) Incubation of MDa HA with the lesion lysate generated HAf below ~650 kDa. Lesion-lysate activity was sensitive to heat inactivation but insensitive to deferoxamine (50 μM). B and C: control n = 2; H-I n = 4 animals for each age group (P4 and P14). D: n = 6 (H-I), n = 5 (control), and n = 4 (hypoxia) animals (P7). E: n = 4 separate experiments on 4 different animals at P4 after H-I at P3; one representative experiment is shown. *P < 0.05 by ANOVA. Mean ± SD. Scale bars: 300 μm (B and C). The Journal of Clinical Investigation R E S E A R C H A R T I C L E2 0 2 7 jci.orgVolume 128 Number 5 May 2018 with MBP-labeled oligodendrocytes (Supplemental Figure 2A). To confirm de novo progressive myelin generation, we undertook ultrastructural studies that identified axons wrapped with multilamellar myelin sheaths ( Figure 2B). In contrast to vehicle-treated slices, which displayed robust myelination of the corpus callosum, slices incubated with MDa HA until 21 days in vitro (DIV21) displayed a pronounced reduction in myelinated axons ( Figure 2C). Myelination failure was not related to decreased OPC survival, since MDa HA treatment did not enhance OPC degeneratio...

Nearly half of cancer patients suffer from cachexia, a metabolic syndrome characterized by progressive atrophy of fat and lean body mass. This state of excess catabolism decreases quality of life, ability to tolerate treatment and eventual survival, yet no effective therapies exist. Although the central nervous system (CNS) orchestrates several manifestations of cachexia, the precise mechanisms of neural dysfunction during cachexia are still being unveiled. Herein, we summarize the cellular and molecular mechanisms of CNS dysfunction during cancer cachexia with a focus on inflammatory, autonomic and neuroendocrine processes and end with a discussion of recently identified CNS mediators of cachexia, including GDF15, LCN2 and INSL3.

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This study presents the first messenger RNA (mRNA) therapy for metastatic ovarian cancer and cachexia‐induced muscle wasting based on lipid nanoparticles that deliver follistatin (FST) mRNA predominantly to cancer clusters following intraperitoneal administration. The secreted FST protein, endogenously synthesized from delivered mRNA, efficiently reduces elevated activin A levels associated with aggressive ovarian cancer and associated cachexia. By altering the cancer cell phenotype, mRNA treatment prevents malignant ascites, delays cancer progression, induces the formation of solid tumors, and preserves muscle mass in cancer‐bearing mice by inhibiting negative regulators of muscle mass. Finally, mRNA therapy provides synergistic effects in combination with cisplatin, increasing the survival of mice and counteracting muscle atrophy induced by chemotherapy and cancer‐associated cachexia. The treated mice develop few nonadherent tumors that are easily resected from the peritoneum. Clinically, this nanomedicine‐based mRNA therapy can facilitate complete cytoreduction, target resistance, improve resilience during aggressive chemotherapy, and improve survival in advanced ovarian cancer.

2 Summary StatementWe present a new image analysis technique using image velocimetry and spectral analysis that returns quantitative measures of gut contraction strength, frequency, and wave speed that can be used to study gut motility and other cellular movements. AbstractNormal gut function requires rhythmic and coordinated movements that are affected by developmental processes, physical and chemical stimuli, and many debilitating diseases. The imaging and characterization of gut motility, especially regarding periodic, propagative contractions driving material transport, are therefore critical goals. Whereas previous image analysis approaches have successfully extracted properties related to temporal frequency of motility modes, robust measures of contraction magnitude remain elusive. We developed a new image analysis method based on image velocimetry and spectral analysis that reveals temporal characteristics such as frequency and wave propagation speed, while also providing quantitative measures of the amplitude of gut motions. We validate this approach using several challenges to larval zebrafish, imaged with differential interference contrast microscopy. Both acetylcholine exposure and feeding increase frequency and amplitude of motility. Larvae lacking enteric nervous system gut innervation show the same average motility frequency, but reduced and less variable amplitude compared to wild-types. Our image analysis approach enables insights into gut dynamics in a wide variety of developmental and physiological contexts and can also be extended to analyze other types of cell movements.