Genome analysis of Tepidibacter sp. SWIR-1, an anaerobic endospore-forming bacterium isolated from a deep-sea hydrothermal vent.

Tepidibacter sp. SWIR-1, a putative new species isolated from deep-sea hydrothermal vent field on the Southwest Indian Ridge (SWIR), is an anaerobic, mesophilic and endospore-forming bacterium belonging to the family Peptostreptococcaceae. In this study, we present the complete genome sequence of strain SWIR-1, consists of a single circular chromosome comprising 4,122,966 nucleotides with 29.25% G + C content and a circular plasmid comprising 38,843 nucleotides with 29.46% G + C content. In total, 3861 protein coding genes, 104 tRNA genes and 46 rRNA genes were obtained. SWIR-1 genome contains numerous genes related to sporulation and germination. Compared with the other three Tepidibacter species, SWIR-1 contained more spore germination receptor proteins. In addition, SWIR-1 contained more genes involved in chemotaxis and two-component systems than other Tepidibacter species. These results indicated that SWIR-1 has developed versatile adaptability to the Southwest Indian Ridge hydrothermal vent environment. The genome of strain SWIR-1 will be helpful for further understanding adaptive strategies used by bacteria dwelling in the deep-sea hydrothermal vent environments of different oceans.

Metagenomic analysis reveals wide distribution of phototrophic bacteria in hydrothermal vents on the ultraslow-spreading Southwest Indian Ridge.

Deep-sea hydrothermal vents are known as chemosynthetic ecosystems. However, high temperature vents emit light that hypothetically can drive photosynthesis in this habitat. Metagenomic studies have sporadically reported the occurrence of phototrophic populations such as cyanobacteria in hydrothermal vents. To determine how geographically and taxonomically widespread phototrophs are in deep-sea hydrothermal vents, we collected samples from three niches in a hydrothermal vent on the Southwest Indian Ridge and carried out an integrated metagenomic analysis. We determined the typical community structures of microorganisms found in active venting fields and identified populations of known potential chlorophototrophs and retinalophototrophs. Complete chlorophyll biosynthetic pathways were identified in all samples. By contrast, proteorhodopsins were only found in active beehive smoker diffusers. Taxonomic groups possessing potential phototrophy dependent on semiconductors present in hydrothermal vents were also found in these samples. This systematic comparative metagenomic study reveals the widespread distribution of phototrophic bacteria in hydrothermal vent fields. Our results support the hypothesis that the ocean is a seed bank of diverse microorganisms. Geothermal vent light may provide energy and confer a competitive advantage on phototrophs to proliferate in hydrothermal vent ecosystems. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-021-00121-y.

Heart rate-corrected QT interval: A novel diagnostic biomarker for diabetic peripheral neuropathy.

AIMS/INTRODUCTION: To explore the relationship between heart rate-corrected QT (QTc) interval and diabetic peripheral neuropathy (DPN), and whether QTc interval has diagnostic utility for DPN beyond nerve conduction velocity. MATERIALS AND METHODS: A total of 965 patients with diabetes, including 473 patients with DPN and 492 patients without DPN, underwent standard 12-lead electrocardiography and detailed assessments of peripheral neuropathy. RESULTS: Patients with DPN had longer QTc intervals than those without. Among participants, from the first to fourth quartile of QTc interval, the proportion of patients with DPN appreciably increased and the nerve conduction velocity obviously decreased (P for trend <0.001). The univariate and multivariate analyses showed that prolonged QTc interval was closely associated with increased risk of DPN (univariable odds ratio 1.112, 95% confidence interval 1.097-1.127, P < 0.001; multivariable odds ratio 1.118, 95% confidence interval 1.099-1.137, P < 0.001). Receiver operating characteristic analysis for the diagnosis of DPN showed a greater area under the curve for QTc interval of 0.894 than the median nerve motor conduction velocity of 0.691, median nerve sensory conduction velocity of 0.664 and peroneal nerve motor conduction velocity of 0.692. The optimal cut-off point of QTc interval for DPN was 428.5 ms with sensitivity of 0.715 and specificity of 0.920 (P < 0.001). The combination of QTc interval and nerve conduction testing increased the area under the curve for the diagnosis of DPN (from 0.736 to 0.916; P < 0.001). CONCLUSIONS: QTc interval with 428.5 ms has more reliable diagnostic utility for DPN than nerve conduction velocity, and prolonged QTc interval is closely associated with an increased risk of DPN.

Curcumin induces apoptosis through mitochondrial pathway and caspases activation in human melanoma cells.

Melanoma is the most malignant skin cancer and is highly resistant to chemotherapy and radiotherapy. Curcumin is a component of turmeric, the yellow spice derived from the rhizome of Curcuma longa. It has been demonstrated to modulate multiple cell signaling pathways, including apoptosis, proliferation, angiogenesis and inflammation. In this study, we studied the signaling pathways involved in melanoma cell death after treatment with curcumin using western blotting. Colorimetric assays (MTT) assessed cell viability. Flow cytometry and DNA laddering evaluated cell apoptosis. Fluorescent microscopy was used to evaluate of Hoechst 33342 staining of nuclei. The result demonstrated that curcumin could induce apoptosis and inhibit proliferation in melanoma cells. Curcumin stimulated the expression of pro-apoptotic Bax, and inhibited the activation of anti-apoptotic Mcl-1 and Bcl-2. During curcumin treatment, caspase-8 and Caspase-3 were cleaved in time and dose-dependent manners. Curcumin treatment also altered the expressions of apoptosis associated proteins NF-κB, p38 and p53. Curcumin induced DNA double strand breaks, which were indicated by phosphorylated H2AX. Our data suggested that curcumin could be used as a novel and effective approach for the treatment of melanoma.

Progression of O6-methylguanine-DNA methyltransferase and temozolomide resistance in cancer research.

Temozolomide (TMZ) is an alkylating agent that is widely used in chemotherapy for cancer. A key mechanism of resistance to TMZ is the overexpression of O(6)-methylguanine-DNA methyltransferase (MGMT). MGMT specifically repairs the DNA O(6)-methylation damage induced by TMZ and irreversibly inactivates TMZ. Regulation of MGMT expression and research regarding the mechanism of TMZ resistance will help rationalize the clinical use of TMZ. In this review, we provide an overview of recent advances in the field, with particular emphasis on MGMT structure, function, expression regulation, and the association between MGMT and resistance to TMZ.

A dual-regulated oncolytic adenovirus expressing interleukin-24 sensitizes melanoma cells to temozolomide via the induction of apoptosis.

Malignant melanoma is one of the most lethal and aggressive human malignancies. Suppressed apoptosis and extraordinary invasiveness are the distinctive features that contribute to malignant melanoma. The alkylating agent temozolomide (TMZ) is one of the most effective single chemotherapeutic agents for patients with malignant melanoma, but resistance develops quickly and with high frequency. We constructed a dual-regulated oncolytic adenovirus expressing interleukin 24 (IL-24) gene (Ki67-ZD55-IL-24) by utilizing the Ki67 promoter to replace the native viral promoter of E1A gene. We investigated whether a combination of Ki67-ZD55-IL-24-mediated gene virotherapy and chemotherapy using TMZ produces increased cytotoxicity against human melanoma cells via the induction of apoptosis. Our data indicate that this novel strategy thus holds promising potentials for further developing an effective approach to treat malignant melanoma.

A conditionally replicating adenovirus carrying interleukin-24 sensitizes melanoma cells to radiotherapy via apoptosis.

Combinatorial therapy is the current trend of the development of novel cancer treatments due to the high heterogenous nature of solid tumors. In this study, we investigated the effects of the combined use of a conditionally replicating adenovirus carrying IL-24 (ZD55-IL-24) and radiotherapy on the proliferation and apoptosis of melanoma A375 cells in vitro and in vivo. Compared with either agent used alone, ZD55-IL-24 combined with radiotherapy significantly inhibited cell proliferation, accompanied with increased apoptosis. Radiotherapy did not affect the expression of IL-24 and E1A of ZD55-IL-24-treated cells, but increased the expression of Bax, promoted the activation of caspase-3, while decreasing Bcl-2 levels. Thus, this synergistic effect of ZD55-IL-24 in combination with radiotherapy provides a novel strategy for the development of melanoma therapies, and is a promising approach for further clinical development.