Relationships between lead-induced learning and memory impairments and gut microbiota disturbance in mice / 中华劳动卫生职业病杂志

Objective: To explore the effect of lead exposure on the neurobehavior and gut microbiota community structure in mice. Methods: In August 2019, 64 C57BL/6 mice were randomly divided into 4 groups: control group (0 ppm) , low lead exposure group (20 mg/l) , medium lead exposure group (100 mg/l) and high lead exposure group (500 mg/l) . During the experiment, they were free to eat and drink. The drinking water of the lead exposure group was mixed with lead acetate, and sodium acetate was added in the control group. After 10 weeks of exposure, the Morris water maze was used to test the learning and memory ability of each group of mice, and then they were sacrificed for sampling. ICP-MS was used to detect lead content in whole blood and brain tissue. ELISA was used to determine the level of IL-1β in mouse serum. 16S rRNA sequencing was used to detect the structural diversity of the intestinal flora in feces, and then the correlation between the flora and behavior indicators was analyzed. Results: In the Morris water maze experiment, compared with the control group, there was no significant difference in the body weight and swimming speed of the mice in the lead exposure groups. The escape latency of the mice in the 100 mg/l and 500 mg/l dose groups was prolonged, and the number of platform crossings decreased (P<0.05) ; meanwhile, the staying time of the mice in the 500 mg/l Pb-treated group in the target quadrant was lower than that of the control group, and the difference was statistically significant (P<0.05) . Compared with the control group, the blood lead content of the mice in each lead exposure group was significantly increased, and the brain lead content of mice in the 500 mg/l dose group was significantly elevated (P<0.05) . The serum IL-1β levels of mice in each lead exposure group were higher than those of the control group (P<0.05) . At the phylum level, the relative abundance of the Proteobacteria phylum in all of Pb-treated groups was significantly increased (P<0.05) ; at the genus level, Allobaculum, Desulfovibrio, Lachnospiraceae_NK4A136_group, Turicibacter and Ureaplasma were significantly increased (P<0.05) . Among them. The relative abundance of Desuffaoibrio, Turici bacter, and Ureaplasma was negatively correlated with the residence time of mice in the quadrant of the platform (r=-0.32, -0.29, -0.44, P<0.05) . Conclusion: Lead exposure induced learning and memory impairments in mice, which may be related to the disturbance of the gut microbiota.

Isolation, identification and lead adsorption study of lead-resistant Lactobacillus casei strains from feces of healthy newborns / 南方医科大学学报

<p><b>OBJECTIVE</b>To isolate and identify lead-resistant Lactobacillus casei strains with lead adsorption ability from the stool of healthy newborns as a new source of bacteria for developing lead-eliminating food products.</p><p><b>METHODS</b>MRS was used to isolate lead-resistant bacteria from the feces of 30 healthy and full-term neonates. A phylogenetic tree was constructed based on the morphological characteristics and 16S rRNA sequences of the isolated bacteria. Physiological and biochemical characterizations of the bacteria were performed according to the Berger's Systematic Bacteriology Handbook, followed by antimicrobial susceptibility test and acid-tolerant bile salt test. The adsorption capacity of Pbof the bacteria was determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES).</p><p><b>RESULTS</b>Three strains of Lactobacillus casei were isolated, which were resistant to penicillin and ceftriaxone and could tolerate the exposure to 500 mg/L Pb. Acid-tolerant bile salt test showed that the bacteria were resistant to culture in the presence of artificial gastric juice (pH 2.0) for 3 h, and their survival rate reached 62.5% following exposure to 0.3% bile salt for 8 h. The bacteria showed a Pbadsorption rate of 90.4% at a low Pbconcentration (1 mg/L) and of 86.27% at a high Pbconcentration (50 mg/L).</p><p><b>CONCLUSION</b>Three Lactobacillus casei strains lead adsorption ability were isolated from the feces of newborns. These bacterial strains provide a new solution to alleviate lead poisoning by probiotic dietary.</p>

Dextran sedimentation for study of neutrophil polarization / 南方医科大学学报

<p><b>OBJECTIVE</b>To determine the optimal method for separating neutrophils for studying neutrophil polarization.</p><p><b>METHODS</b>Human neutrophil was separated from healthy human peripheral blood by Percoll density gradient centrifugation and Dextran sedimentation. The cell polarization, purity and activity of the neutrophils were determined, and F-actin polymerization and [Ca2+]i were analyzed.</p><p><b>RESULTS</b>No significant difference was found in cell polarization, purity and activity of the human neutrophils separated by Dextran sedimentation and Percoll density gradient centrifugation (P>0.05), but F-actin polymerization was inhibited in PMNs separated by Dextran sedimentation, and the peak value of [Ca2+]i was decreased by 25% in PMNs separated by Dextran sedimentation compared to the cells separated by Percoll density gradient centrifugation.</p><p><b>CONCLUSIONS</b>Both Percoll density gradient centrifugation and Dextran sedimentation can be used for isolating human neutrophils to study cell polarization, but the former method allows better isolation. Dextran sedimentation can be considered when a large number of neutrophils need to be separated.</p>