Transformation mechanism of methylphosphonate to methane by Burkholderia sp: Insight from multi-labeled water isotope probing and transcriptomic.

Methylphosphonate (MPn), has been identified as a likely source of methane in aerobic ocean and may be responsible for the "ocean methane paradox", that is oversaturation of dissolved methane in oxic sea waters. However, the mechanism underlying the cleavage of C-P bonds during microbial degradation is not well understood. Using multi-labeled water isotope probing (MLWIP) and transcriptome analysis, we investigated the phosphate oxygen isotope systematics and mechanisms of microbial-mediated degradation of MPn in this study. In the aerobic culture containing MPn as the only phosphorus source, there was a significant release of inorganic phosphate (149.4 µmol/L) and free methane (268.3 mg/L). The oxygen isotopic composition of inorganic phosphorus (δ18OP) of accumulated released phosphate was 4.50‰, 23.96‰, and 40.88‰, respectively, in the corresponding 18O-labeled waters of -10.3‰, 9.9‰, and 30.6‰, and the slope obtained in plots of δ18OP versus the oxygen isotopic composition of water (δ18OW) was 0.89. Consequently, 89% of the oxygen atoms (Os) in phosphate (PO4) were exchanged with 18O-labeled waters in the medium, while the rest were exchanged with intracellular metabolic water. It has been confirmed that the C-P bond cleavage of MPn occurs in the cell with both ambient and metabolic water participation. Moreover, phn gene clusters play significant roles to cleave the C-P bond of MPn for Burkholderia sp. HQL1813, in which phnJ, phnM and phnI genes are significantly up-regulated during MPn decomposition to methane. In conclusion, the aerobic biotransformation of MPn to free methane by Burkholderia sp. HQL1813 has been elucidated, providing new insights into the mechanism that bio-cleaves C-P bonds to produce methane aerobically in aqueous environments for representative phosphonates.

Novel Prenylated Indole Alkaloids with Neuroprotection on SH-SY5Y Cells against Oxidative Stress Targeting Keap1-Nrf2.

Oxidative stress has been implicated in the etiology of Parkinson's disease (PD). Molecules non-covalently binding to the Keap1-Nrf2 complex could be a promising therapeutic approach for PD. Herein, two novel prenylated indole alkaloids asperpenazine (1), and asperpendoline (2) with a scarce skeleton of pyrimido[1,6-a]indole were discovered from the co-cultivated fungi of Aspergillus ochraceus MCCC 3A00521 and Penicillium sp. HUBU 0120. Compound 2 exhibited potential neuroprotective activity on SH-SY5Y cells against oxidative stress. Molecular mechanism research demonstrated that 2 inhibited Keap1 expression, resulting in the translocation of Nrf2 from the cytoplasm to the nucleus, activating the downstream genes expression of HO-1 and NQO1, leading to the reduction in reactive oxygen species (ROS) and the augment of glutathione. Molecular docking and dynamic simulation analyses manifested that 2 interacted with Keap1 (PDB ID: 1X2R) via forming typical hydrogen and hydrophobic bonds with residues and presented less fluctuation of RMSD and RMSF during a natural physiological condition.

Microplastic accelerate the phosphorus-related metabolism of bacteria to promote the decomposition of methylphosphonate to methane.

Microplastic (MP) contaminants in marine water have become a global public health concern because of their persistence and potentially adverse effects on organisms. MP can affect the growth and metabolism of marine microorganisms and further impact the microbial environmental functions. The molecular impact mechanisms of MP on specific functional microbes with the capability of decomposing methylphosphonate (MPn) to release methane (CH4) in oxygenated water have rarely been reported upon. Herein, we investigated the effects of MP on microbes and concomitant methanogenesis via the microbial degradation of MPn. Furthermore, the specific perturbation was revealed at the molecular level combined with transcriptomics and metabolomics. The results showed that intracellular phosphorus utilization by MPn-degrading strain Burkholderia sp. HQL1813 was enhanced by accelerating the catabolism of MPn. Phosphorus transport-related genes (phnG-M, pstSCAB, phnCDE) were upregulated in the MP exposure groups. Amino acid metabolism, the phosphotransferase system and nucleotide metabolism were also perturbed after MP exposure. Notably, released CH4 increased by 24 %, 29 % and 14 % in the exposure group. In addition, the responses of the strain were dose-independent with increasing MP doses. These findings are beneficial for clarifying the effect of MP on specific functional microbes at the molecular level and their degradation of CH4 by MPn.

[Study on the toxicological effect of chloropropanols on rats].

Toxicological effect of 3-chloro-1,2-propanediol on rats were studied to provide scientific basis for assessing the effect of Chloropropanols on human health. 170 SD rats were divided randomly into 8 groups and the dose of 0, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 mg/kg 3-chloro-1,2-propanediol were given to rats for 90 days by gavages per day, respectively. The weight and food efficiency, hematology and clinical chemistry, NAG, GGT and total protein in urine, sperm number, sperm survive rate and sperm aberration rate, the LDH and LDH-X activity in testis, rate of organ/weight and histopathological analysis were measured. The results showed that different dose of 3-chloro-1,2-propanediol did not has adverse effect on body weight, food efficiency, Hb, red cell, white cell, serum AST, ALT, creatine, ALP, LDH, total protein and albumin, urine GGT and total protein, LDH activity in testis. At the dose of 4.0, 8.0 and 16.0 mg/kg group, the activity of NAG in urine and the rate of kidney/weight was significantly increased compared with negative control groups; the pathological changes in kidney were observed in the same groups, and the sperm number was also significantly decreased. At the dose of 8.0 and 16.0 mg/kg group, sperm survive rate and the X-LDH activity were significantly decreased and pathological changes were also observed in testis and caudal epididymis. It was concluded that the activity of NAG in urine and sperm number is the sensitive biological effective marker. Because urine is a kind of convenient available biological material, NAG activity in urine is a good biological effective marker for assessing effect of Chloropropanols on health. If the NAG activity can be used as sensitive marker for assessment on human health need to be tested further in human study.