No abstract

The impaired healing of Mycobacterium tuberculosis-infected wounds is a clinical challenge, and the mechanisms involved are still not clear. The zebrafish model of Mycobacterium marinum infection has provided surprising insights into the pathogenesis of tuberculosis in humans. Similarly, the major principles and phases of cutaneous wound healing are conserved among adult mammals and adult zebrafish. Here, we injected Mycobacterium marinum into the dorsal muscles of adult zebrafish and observed the development of chronic wound pathology. Deep sequencing showed that gene expression related to muscles was down-regulated, whereas expressions of the IL-1β, TNF-α, dram1 genes and the transcript of mir1-2 gene were up-regulated in infected wounds of zebrafish compared with control zebrafish. Muscles are immune-responsive tissues. Thus, muscles may play a role in the anti-Mycobacterium tuberculosis immunologic process, which leads to apoptosis of the infected muscle cell and formation of the subcutaneous sinus tract.

Abuse of heavy metals and antibiotics results in the dissemination of metal resistance genes (MRGs) and antibiotic resistance genes (ARGs). Ditch wetlands are important sinks for heavy metals and antibiotics. The relationships between bacterial communities and MRG/ARG dissemination under dual stresses of heavy metals and antibiotics remain unclear. The responses of MRGs and ARGs to the co-selective pressure of cadmium (Cd) and doxycycline (DC) in ditch wetlands were investigated after 7-day and 84-day exposures. In ecological ditches, residual rates of Cd and DC varied from 0.4 to –5.73% and 0 to –0.61%, respectively. The greatest total relative abundance of ARGs was observed in the Cd 5 mg L–1 + DC 50 mg L–1 group. A significant level of DC (50 mg L–1) significantly reduced the total relative abundances of MRGs at a concentration of 5 mg L–1 Cd stress. Redundancy analysis indicated that Cd and DC had strong positive effects on most ARGs and MRGs after a 7-day exposure. Meanwhile, the class 1 integron gene (intI1) exhibited strong positive correlations with most ARGs and cadmium resistance genes (czcA) after an 84-day exposure. Network analysis showed that Acinetobacter and Pseudomonas were the potential dominant host genera for ARGs and MRGs, and tetracycline resistance genes (tetA), czcA, and intI1 shared the same potential host bacteria Trichococcus after an 84-day exposure.