Degradation potential and pathways of methylcyclohexane by bacteria derived from Antarctic surface water.

Cycloalkanes pose a tremendous environmental risk due to their high concentration in petroleum hydrocarbons and hazardous effects to organisms. Numerous studies have documented the biodegradation of acyclic alkanes and aromatic hydrocarbons. However, insufficient attention has been paid to studies on the microbial degradation of cycloalkanes, which might be closely linked to psychrophilic microbes derived from low-temperature habitats. Here we show that endemic methylcyclohexane (MCH, an abundant cycloalkane species in oil) consumers proliferated in seawater samples derived from the Antarctic surface water (AASW). The MCH-consuming bacterial communities derived from AASW exhibited a distinct species composition compared with their counterparts derived from other cold-water habitats. We also probed Colwellia and Roseovarius as the key active players in cycloalkane degradation by dilution-to-extinction-based incubation with MCH as sole source of carbon and energy. Furthermore, we propose two nearly complete MCH degradation pathways, lactone formation and aromatization, concurrently in the high-quality metagenome-assembled genomes of key MCH consumer Roseovarius. Overall, we revealed that these Antarctic microbes might have strong interactions that enhance the decomposition of more refractory hydrocarbons through complementary degradation pathways.

Structural and Functional Diversity of Peptide Toxins from Tarantula Haplopelma hainanum (Ornithoctonus hainana) Venom Revealed by Transcriptomic, Peptidomic, and Patch Clamp Approaches.

Spider venom is a complex mixture of bioactive peptides to subdue their prey. Early estimates suggested that over 400 venom peptides are produced per species. In order to investigate the mechanisms responsible for this impressive diversity, transcriptomics based on second generation high throughput sequencing was combined with peptidomic assays to characterize the venom of the tarantula Haplopelma hainanum. The genes expressed in the venom glands were identified, and the bioactivity of their protein products was analyzed using the patch clamp technique. A total of 1,136 potential toxin precursors were identified that clustered into 90 toxin groups, of which 72 were novel. The toxin peptides clustered into 20 cysteine scaffolds that included between 4 and 12 cysteines, and 14 of these groups were newly identified in this spider. Highly abundant toxin peptide transcripts were present and resulted from hypermutation and/or fragment insertion/deletion. In combination with variable post-translational modifications, this genetic variability explained how a limited set of genes can generate hundreds of toxin peptides in venom glands. Furthermore, the intraspecies venom variability illustrated the dynamic nature of spider venom and revealed how complex components work together to generate diverse bioactivities that facilitate adaptation to changing environments, types of prey, and milking regimes in captivity.

[Effects of twirling-rotating reinforcing and reducing technique for left ventricular morphology, concentration of ET-1 and expression of type I, III collagen mRNA in spontaneous hypertensive rats].

OBJECTIVE: To explore the effect differences between twirling-rotating reinforcing and reducing technique of acupuncture on cardiac damage in spontaneous hypertensive rats (SHR). METHODS: Sixty male 11-week-old SHR were randomly divided into four groups: a model control group (group A), a twirling-rotating reinforcing technique group (group B), a twirling-rotating reducing technique group (group C) and a needle retaining group (group D), 15 rats in each one. In addition, twelve male 11-week-old Wistar rats were used as a blank control group (group E). Acupuncture was not used in group A and group E, only with grasp, capture and binding stimulation that was also adapted in the rest groups. Rats in the group B were treated with acupuncture at "Taichong" (LR 3) by twirling-rotating reinforcing technique for 1 min and then the needles were retained for 9 min; rats in the group C were treated with acupuncture at "Taichong" (LR 3) by twirling-rotating reducing technique for 1 min and then the needles were retained for 9 min; rats in the group D were treated with acupuncture at "Taichong" (LR 3) but without any technique and then needles were retained for 10 min. Before and after acupuncture, blood pressure monitor was used to measure the rats' systolic pressure and diastolic pressure every 6 days. Twenty-eight days after the treatment, HE and Masson staining were adopted to observe the status of left ventricular hypertrophy and myocardial fibrosis. ELISA method was applied to test the content of endothelin-1 (ET-1). PCR semiquantitative method was used to analyze Type I and III collagen mRNA in the left ventricular. RESULTS: (1) Blood pressure: after the treatment, the systolic pressure and diastolic pressure were both increased in the group A and the group B (P < 0.05); while the two pressures were both lowered in the group C and the group D (P < 0.05), which was more obvious in the group C (P < 0.05). (2) According to HE and Masson staining, except for the group E, the myocardial hypertrophy and fibrosis could be found in the rest groups, in which the group C was the modest, followed by the group D, while the group A and the group B were more severe. (3) Concentration of ET-1: there were differences of concentration of ET-1 among 5 groups (P < 0.05), and the concentration value from high to low was the group A, B, C, D and E. (4) Type I collagen mRNA: the difference of level of Type I collagen mRNA between group C and D was not statistically significant (P > 0.05); compared with the group A and B, the level was lower in the group C; the level was the lowest in the group E. Type III collagen mRNA: the difference between the group A and B was not statistically significant (P > 0.05); compared with the group A, B and D, the level was lower in the group C. CONCLUSION: The twirling-rotating reducing could reduce the systolic pressure and diastolic pressure in SHR, effectively prohibit the production of ET-1 and expression of Type I and III collagen mRNA, and it has more obvious inhibiting effect on Type III collagen mRNA. There is biological effect difference between twirling-rotating reinforcing and reducing technique.

Selenium suppresses lipopolysaccharide-induced fibrosis in peritoneal mesothelial cells through inhibition of epithelial-to-mesenchymal transition.

Peritoneal fibrosis resulting from long-term clinical peritoneal dialysis has been the main reason of dropout from peritoneal dialysis. Peritonitis as a common complication of peritoneal dialysis treatment may lead to the occurrences of peritoneal fibrosis. We cultured peritoneal mesothelial cells with lipopolysaccharides (LPS) in order to stimulate the environment of peritonitis and investigate whether lipopolysaccharides could induce epithelial-to-mesenchymal transition (EMT). Oxidative stress could stimulate fibrogenesis while selenium has antioxidant properties. So, this study also explored whether selenium supplementation affects lipopolysaccharide-induced EMT and fibrosis. We found that lipopolysaccharides could activate EMT changes such as the loss of E-cadherin and the increase of α-smooth muscle actin (α-SMA), collagen I, vimentin, and fibronectin (FN), while selenium inhibits EMT by modulating reactive oxygen species (ROS) generation and ROS/MMP-9 signaling pathways in peritoneal mesothelial cells. Moreover, it was revealed that selenium decreased the EMT events of peritoneal mesothelial cells via inhibition of PI3k/AKT pathways. In conclusion, these findings enable a better understanding of the mechanism of peritoneal fibrosis and explore a new idea for the prevention and treatment.

Physiological and biochemical analysis to reveal the molecular basis for black widow spiderling toxicity.

The early research found that the spiderlings of black widow spider (Latrodectus tredecimguttatus) exhibited obvious toxicity to animals. The present work performed a systematical analysis of the aqueous extract of newborn black widow spiderlings. The extract was shown to contain 69.42% of proteins varying in molecular weights and isoelectric points. Abdominal injection of the extract into mice and cockroaches caused obvious poisoning symptoms as well as death, with LD50 being 5.30 mg/kg in mice and 16.74 µg/g in Periplaneta americana. Electrophysiological experiments indicated that the extract at a concentration of 10 µg/mL could completely block the neuromuscular transmission in isolated mouse nerve-hemidiaphragm preparations within 21 ± 1.5 min, and 100 µg/mL extract could inhibit a certain percentage of voltage-activated Na⁺, K⁺, and Ca²âº channel currents in rat dorsal root ganglion neurons. These results demonstrate that the spiderlings are rich in neurotoxic components, which play important roles in the spiderling toxicity.