The Biocontrol Functions of Bacillus velezensis Strain Bv-25 Against Meloidogyne incognita.

Meloidogyne incognita is obligate parasitic nematode with a wide variety of hosts that causes huge economic losses every year. In an effort to identify novel bacterial biocontrols against M. incognita, the nematicidal activity of Bacillus velezensis strain Bv-25 obtained from cucumber rhizosphere soil was measured. Strain Bv-25 could inhibit the egg hatching of M. incognita and had strong nematicidal activity, with the mortality rate of second-stage M. incognita juveniles (J2s) at 100% within 12 h of exposure to Bv-25 fermentation broth. The M. incognita genes ord-1, mpk-1, and flp-18 were suppressed by Bv-25 fumigation treatment after 48 h. Strain Bv-25 could colonize cucumber roots, with 5.94 × 107 colony-forming units/g attached within 24 h, effectively reducing the infection rate with J2s by 98.6%. The bacteria up-regulated the expression levels of cucumber defense response genes pr1, pr3, and lox1 and induced resistance to M. incognita in split-root trials. Potted trials showed that Bv-25 reduced cucumber root knots by 73.8%. The field experiment demonstrated that disease index was reduced by 61.6%, cucumber height increased by 14.4%, and yield increased by 36.5% in Bv-25-treated plants compared with control. To summarize, B. velezensis strain Bv-25 strain has good potential to control root-knot nematodes both when colonizing the plant roots and through its volatile compounds.

[Particle Size Distribution and Human Health Risk Assessment of Heavy Metals in Atmospheric Particles from Beijing and Xinxiang During Summer].

Under a condition of good air quality (AQI:55-90, PM10:37-97 µg·m-3, PM2.5:17-76 µg·m-3), six groups of 54 samples were collected using an Andersen cascade impactor from both the indoor and outdoor stations in Beijing and Xinxiang from June to August in 2016. The samples were digested by microwave digestion, and nine heavy metal elements (Pb, Cr, Ni, Cu, Zn, As, Cd, Mn, and Co) in the atmospheric particles were determined with an inductively coupled plasma source mass spectrometer (ICP-MS). The results showed that the enrichment index (0-3) of most elements were low in both cities except for Cd[15.0 (Beijing) and 8.47 (Xinxiang)]. Cr, Co, Cu, and Mn in the atmospheric particles from Beijing park, Cd, Pb, and Mn in the atmospheric particles from the Beijing office, Cr, Co, Ni, and As in the atmospheric particles from Xinxiang park, and all nine heavy metal elements in the atmospheric particles from roads in both cities were found to be more concentrated in the coarse fractions; however, Pb, Zn, Cd, Ni, and As in the atmospheric particles from Beijing park, Co, Zn, Ni, Cr, As, and Cu in the atmospheric particles from the Beijing office, Pb, Zn, Cd, Cu, and Mn in the atmospheric particles from Xinxiang park, and all nine metal elements in the atmospheric particles from the Beijing office showed the opposite pattern. The result of a human health risk assessment indicated that the carcinogenic risk of the five carcinogenic elements were all less than 10-4, but a lower potential cancer risk would also occur under long term exposure. For the four non-carcinogenic elements (Pb, Zn, Mn, and Cu), the non-carcinogenic health risk values of Pb, Zn, Mn, and Cu in the atmospheric particulates in Beijing were all far less than 1, which means the corresponding non-carcinogenic risk was negligible; and, except for Mn, there was no obvious non-carcinogenic risk from Pb, Zn, and Cu in the atmospheric particles of Xinxiang.

[Protective effects of taurine on myocardial mitochondria and their enzyme activities in rate with severe burn].

OBJECTIVE: To investigate the effects of taurine on myocardial mitochondria and their enzyme activities in rats with severe burn. METHODS: One hundred and twenty healthy adult Wistar rats were subjected to 30% TBSA full-thickness burn. They were randomly divided into burn group (B, with intraperitoneal injection of isotonic saline), treatment group (T, with intraperitoneal injection of taurine, 200 mg/kg),with 60 rats in each group . Ten rats with sham scald were used as control (S group). The myocardial tissue samples in B and T groups were harvested at 1, 3, 6, 12, 24 and 48 postburn hours (PBH) for determination of activity respectively of succinate dehydrogenase (SDH), cytochrome oxidase (CCO), the superoxide dismutase (SOD), Ca2+ -ATPase in mitochondria, and contents of cytochrome c (Cyt c), cytochrome aa3 (Cyt aa3), malondialdehyde (MDA), and Ca2+ in mitochondria and cytoplasm . The myocardial tissue samples of controls were harvested at 1 PBH for determination of above indices. RESULTS: The activity of CCO in B group was decreased at 1 PBH , especially at 6 ,12 PBH. The activity of SDH in B group was decreased to lowest level at 6 PBH, and its value was lower than that of S group at each time point. The activity of CCO or SDH in T group was not obviously decreased, and the activity of CCO at 3, 6, 12 PBH showed significant difference compared with B group (P < 0.05). The contents of Cyt aa3 and Cyt c in B group at 3, 6, 12, 24 PBH were obviously decreased, which were significantly lower than those in T group (P < 0.05). The activity of SOD in B group at 3, 6, 12 PBH was obviously decreased, the activity of Ca2+ -ATPase at 3, 6, 12 and 24 PBH was decreased to different extent, which was significantly lower than those in T group (P < 0.05). The MDA contents in B and T groups were higher than that in S group at 3-48 PBH ,and it was highest in B group (P < 0.05). The Ca2+ content of mitochondria in B group at 1 PBH was increased (13.7 +/- 1.5), and it was (24.8 +/- 2.6), (29.7 +/- 3.1), (16.3 +/- 1.9) and (13.5 +/- 1.7) at 3, 6, 12, 24 PBH respectively,and they were all higher than that of S group (10.7 +/- 1.6, P < 0.05). The Ca2 contents of cytoplasm in group B at 3 - 24 PBH were also higher than that in S group (P < 0.05). The Ca2+ content of mitochondria in T group at 3, 6, 12, 24 PBH was (16.8 +/- 2.8), (18.7 +/- 1.9), (10.5 +/- 1.8) and (13.3 +/- 1.7)respectively, which were lower than that in B group at every time point. CONCLUSION: Taurine have protective effect on mitochondria and their enzyme activities in myocardium in rats with severe burn, and it may be attributable to improving the ability of eradicating oxygen free radicals and alleviating Ca2+ overload in the mitochondria.