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The pretreatments for the measurement of dissolved inorganic carbon (DIC) isotopes in field water samples were developed from traditional BaCl2 precipitation methods to directly continuous flow (GasBench-IRMS) methods. Further research needs be conducted to distinguish the difference between the traditional BaCl2 precipitation methods and the continuous flow (GasBench-IRMS) method in order to select the best pretreatment for DIC. This study compared the results obtained by three pretreatment methods: BaCl2 precipitation, medical sterile high-density polyethylene bottles and acidification of the sample in GasBench headspace vials in field work. Drip water and underground water samples were collected from Panlong cave in Guilin. The results show that because of CO2 escape from the water sample, by using the BaCl2 precipitation the value of the carbon isotope was more positive than other sample-pretreatment methods. The maximum deviation of the carbon isotope value from the underground river is 0.26. The maximum deviation of the carbon isotope value from the cave drip water is 0.33. The temperature and atmospheric pressure are similar in the field and the laboratory, therefore it did not cause solubility change of CO2 and HCO-3 in water samples. The DIC results of the medical sterile high-density polyethylene bottles and GasBench headspace vials are the same. The GasBench headspace vials pretreatment method can effectively avoid the solubility change of CO2 and HCO-3 caused by environmental changes, which leads to the CO2 escape from the water sample or dissolved into the water sample from the atmosphere of CO2. This change may cause carbon isotopic fractionation in DIC of water samples. Using GasBench headspace vials, which directly produce and collect CO2 gas in the field is the recommended DIC pretreatment method.

Abstract Background Neuropathic pain is detrimental to human health; however, its pathogenesis still remains largely unknown. Overexpression of pain-associated genes and increased nociceptive somato-sensitivity are well observed in neuropathic pain. The importance of epigenetic mechanisms in regulating the expression of pro- or anti-nociceptive genes has been revealed by studies recently, and we hypothesize that the transcriptional coactivator and the histone acetyltransferase E1A binding protein p300 (p300), as a part of the epigenetic mechanisms of gene regulation, may be involved in the pathogenesis of neuropathic pain induced by chronic constriction injury (CCI). To test this hypothesis, two different approaches were used in this study: (I) down-regulating p300 with specific small hairpin RNA (shRNA) and (II) chemical inhibition of p300 acetyltransferase activity by a small molecule inhibitor, C646. Results Using the CCI rat model, we found that the p300 expression was increased in the lumbar spinal cord on day 14 after CCI. The treatment with intrathecal p300 shRNA reversed CCI-induced mechanical allodynia and thermal hyperalgesia, and suppressed the expression of cyclooxygenase-2 (COX-2), a neuropathic pain-associated factor. Furthermore, C646, an inhibitor of p300 acetyltransferase, also attenuated mechanical allodynia and thermal hyperalgesia, accompanied by a suppressed COX-2 expression, in the spinal cord. Conclusions The results suggest that, through its acetyltransferase activity in the spinal cord after CCI, p300 epigenetically plays an important role in neuropathic pain. Inhibiting p300, using interfering RNA or C646, may be a promising approach to the development of new neuropathic pain therapies.

JMJD6, a jumonji C (Jmj C) domain-containing protein demethylase and hydroxylase, has been implicated in an array of biological processes. It has been shown that JMJD6 interacts with and hydroxylates multiple serine/arginine-rich (SR) proteins and SR related proteins, including U2AF65, all of which are known to function in alternative splicing regulation. However, whether JMJD6 is widely involved in alternative splicing and the molecular mechanism underlying JMJD6-regulated alternative splicing have remained incompletely understood. Here, by using RASL-Seq, we investigated the functional impact of RNA-dependent interaction between JMJD6 and U2AF65, revealing that JMJD6 and U2AF65 co-regulated a large number of alternative splicing events. We further demonstrated the JMJD6 function in alternative splicing in jmjd6 knockout mice. Mechanistically, we showed that the enzymatic activity of JMJD6 was required for a subset of JMJD6-regulated splicing, and JMJD6-mediated lysine hydroxylation of U2AF65 could account for, at least partially, their co-regulated alternative splicing events, suggesting both JMJD6 enzymatic activity-dependent and independent control of alternative splicing. These findings reveal an intimate link between JMJD6 and U2AF65 in alternative splicing regulation, which has important implications in development and disease processes.

Aim: Senescence of alveolar type II (AT2) cells is an important driver of pulmonary fibrosis. This study aimed to investigate whether and how dysregulation of hydrogen sulfide (H2S) production affected AT2 cell senescence, and then explored the effect of H2S on the communication between AT2 and fibroblasts. Methods: ICR mice were intratracheally administered with bleomycin (3 mg/kg). Sodium hydrosulfide (NaHS, 28 μmol/kg/d) was intraperitoneally injected for 2 weeks. The H2S‐generating enzyme cystathionine‐β‐synthase (CBS) knockout heterozygous (CBS+/−) mice were used as a low H2S production model. Results: Analysis of microarray datasets revealed downregulation of H2S‐generating enzymes in lung tissues of patients with pulmonary fibrosis. Decreased H2S production was correlated with higher levels of cell senescence markers p53 and p21 in bleomycin‐induced lung fibrosis. CBS+/− mice exhibited increased levels of p53 and p21. The numbers of AT2 cells positive for p53 and p21 were increased in CBS+/− mice as compared to control mice. H2S donor NaHS attenuated bleomycin‐induced AT2 cell senescence both in vivo and in vitro. H2S donor suppressed bleomycin‐induced senescence‐associated secretory phenotype (SASP) of AT2 cells via inhibiting p53/p21 pathway, consequently suppressing proliferation and myofibroblast transdifferentiation of fibroblasts. Mechanically, H2S suppressed p53 expression by enhancing the mouse double‐minute 2 homologue (MDM2)‐mediated ubiquitination and degradation of p53. Conclusion: H2S inactivated p53‐p21 pathway, consequently suppressing AT2 cell senescence as well as cell communication between senescent AT2 cells and fibroblasts. Aberrant H2S synthesis may contribute to the development of pulmonary fibrosis through promoting the activation loop involving senescent AT2 cells and activated fibroblasts. [ABSTRACT FROM AUTHOR]