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Highlights d The excitation/inhibition (E/I) ratio is dynamic across the 24h day d Fluctuations in the E/I ratio depend on sleep/wake history d E/I ratio changes are circuit specific, not uniform across all synapses

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Methylation of cytosine to 5-methylcytosine (5mC) is a prevalent DNA modification found in many organisms. Sequential oxidation of 5mC by TET dioxygenases results in a cascade of additional epigenetic marks and promotes DNA demethylation in mammals1,2. However, the enzymatic activity and the function of TET homologs in diverse eukaryotes remains largely unexplored. In our study of TET homologs in the green alga Chlamydomonas reinhardtii, we have found a 5mC-modifying enzyme (CMD1) that catalyzes conjugation of a glyceryl moiety to the methyl group of 5mC through a carbon-carbon bond, resulting in two novel stereoisomeric nucleobase products. The catalytic activity of CMD1 requires Fe(II) and the integrity of its binding motif His-x-Asp (HxD), which is conserved in Fe-dependent dioxygenases3. However, unlike all previous described TET enzymes which utilize 2-oxoglutarate (2-OG) as a co-substrate4, CMD1 utilizes L-ascorbic acid (vitamin C, VC) as an essential co-substrate. VC donates the glyceryl moiety to 5mC with concurrent formation of glyoxylic acid and CO2. The VC-derived DNA modification is present in the genome of C. reinhardtii and its level decreases significantly in a CMD1 mutant strain. The fitness of CMD1 mutant cells during high light exposure is reduced. LHCSR3, a critical gene for protection of C. reinhardtii from photooxidative damage in high light, is hypermethylated and downregulated compared to wild-type cells, causing a lowered capacity for photoprotective non-photochemical quenching (NPQ). Our study thus reveals a new eukaryotic DNA base modification, which is catalyzed by a divergent TET homolog and unexpectedly derived from VC, and its role as a potential epigenetic mark that may counteract DNA methylation in the regulation of photosynthesis.

Fluorocarbons are lipophobic and non-polar molecules that exhibit remarkable bio-compatibility, with applications in liquid ventilation and synthetic blood. The unique properties of these compounds have also enabled mass spectrometry imaging of tissues where the fluorocarbons act as a Teflon-like coating for nanostructured surfaces to assist in desorption/ionization. Here we report fluorinated gold nanoparticles (f-AuNPs) designed to facilitate nanostructure imaging mass spectrometry. Irradiation of f-AuNPs results in the release of the fluorocarbon ligands providing a driving force for analyte desorption. The f-AuNPs allow for the mass spectrometry analysis of both lipophilic and polar (central carbon) metabolites. An important property of AuNPs is that they also act as contrast agents for X-ray microtomography and electron microscopy, a feature we have exploited by infusing f-AuNPs into tissue via fluorocarbon liquids to facilitate multi-modal (molecular and anatomical) imaging.

A panel of metabolites has been identified to facilitate the prediction of tumor response to NCRT in LARC, which is promising for the generation of personalized treatment strategies for LARC patients.

Background Radiotherapy is a conventional and effective local treatment for breast cancer. However, residual or recurrent tumors appears frequently because of radioresistance. Novel predictive marker and the potential therapeutic targets of breast cancer radioresistance needs to be investigated. Methods In this study, we screened all 10 asparagine-linked glycosylation (ALG) members in breast cancer patients’ samples by RT-PCR. Cell viability after irradiation (IR) was determined by CCK-8 assay and flow cytometry. The radiosensitivity of cell lines with different ALG3 expression was determined with the colony formation assay by fitting the multi-target single hit model to the surviving fractions. Cancer stem-like traits were assessed by RT-PCR, Western blot, and flow cytometry. The mechanisms of ALG3 influencing radiosensitivity was detected by Western blot and immunoprecipitation. And the effect of ALG3 on tumor growth after IR was verified in an orthotopic xenograft tumor models. The association of ALG3 with prognosis of breast cancer patients was confirmed by immunohistochemistry. Results ALG3 was the most significantly overexpressing gene among ALG family in radioresistant breast cancer tissue. Overexpression of ALG3 predicted poor clinicopathological characteristics and overall survival (OS), and early local recurrence-free survival (LRFS) in breast cancer patients. Upregulating ALG3 enhanced radioresistance and cancer stemness in vitro and in vivo. Conversely, silencing ALG3 increased the radiosensitivity and repressed cancer stemness in vitro, and more importantly inhibition of ALG3 effectively increased the radiosensitivity of breast cancer cells in vivo. Mechanistically, our results further revealed ALG3 promoted radioresistance and cancer stemness by inducing glycosylation of TGF-β receptor II (TGFBR2). Importantly, both attenuation of glycosylation using tunicamycin and inhibition of TGFBR2 using LY2109761 differentially abrogated the stimulatory effect of ALG3 overexpression on cancer stemness and radioresistance. Finally, our findings showed that radiation played an important role in preventing early recurrence in breast cancer patients with low ALG3 levels, but it had limited efficacy in ALG3-overexpressing breast cancer patients. Conclusion Our results suggest that ALG3 may serve as a potential radiosensitive marker, and an effective target to decrease radioresistance by regulating glycosylation of TGFBR2 in breast cancer. For patients with low ALG3 levels, radiation remains an effective mainstay therapy to prevent early recurrence in breast cancer.