Monitoring Microbial Populations and Antibiotic Resistance Gene Enrichment Associated with Arctic Waste Stabilization Ponds.

Wastewater management in the Canadian Arctic is challenging due to climate extremes, small population sizes, and lack of conventional infrastructure for wastewater treatment. Although many northern communities use waste stabilization ponds (WSPs) as their primary form of wastewater treatment, few studies have explored WSP microbial communities and assessed effluent impacts on receiving waters from a microbiological perspective. Here, we used 16S rRNA gene and metagenome sequencing to characterize WSP and receiving water microbial communities for two time points bracketing the spring WSP thaw in Baker Lake (Nunavut) and compared these results to other Nunavut WSPs in Cambridge Bay and Kugluktuk. Most amplicon sequence variants (ASVs) recovered from these WSP samples belonged to the phylum Proteobacteria, with considerable variation between the three locations and only six ASVs shared among the WSPs at >0.2% relative abundance. Wastewater indicator ASVs for the Baker Lake WSP were identified, and few indicator ASVs were detected in samples originating from other upstream or downstream sites. The metagenomic data revealed a strong enrichment of antibiotic resistance genes for WSP samples relative to downstream and reference samples, especially for genes associated with macrolide resistance. Together, our results provide a baseline characterization for WSP microbial communities, demonstrate how indicator ASVs can be used to monitor attenuation and dilution of effluent microorganisms, and reveal that WSPs can serve as hot spots for antibiotic resistance genes.IMPORTANCE Given that the microbial communities of Arctic waste stabilization ponds (WSPs) are poorly studied to date, our characterization of multiple WSP systems and time points provides important baseline data that will assist with ongoing monitoring of effluent impacts on downstream aquatic ecosystems in the Arctic. This research also identifies indicator amplicon sequence variants (ASVs) of WSPs that will be helpful for future monitoring for WSP effluent attenuation and demonstrates that WSP microbial communities are enriched in antibiotic resistance genes. Given operational and infrastructure changes anticipated for wastewater treatment systems in the Arctic, baseline data such as these are essential for further development of safe and effective wastewater treatment systems.

The GRHL2/ZEB Feedback Loop-A Key Axis in the Regulation of EMT in Breast Cancer.

More than 90% of cancer-related deaths are caused by metastasis. Epithelial-to-Mesenchymal Transition (EMT) causes tumor cell dissemination while the reverse process, Mesenchymal-to-Epithelial Transition (MET) allows cancer cells to grow and establish a potentially deadly metastatic lesion. Recent evidence indicates that in addition to E and M, cells can adopt a stable hybrid Epithelial/Mesenchymal (E/M) state where they can move collectively leading to clusters of Circulating Tumor Cells-the "bad actors" of metastasis. EMT is postulated to occur in all four major histological breast cancer subtypes. Here, we identify a set of genes strongly correlated with CDH1 in 877 cancer cell lines, and differentially expressed genes in cell lines overexpressing ZEB1, SNAIL, and TWIST. GRHL2 and ESRP1 appear in both these sets and also correlate with CDH1 at the protein level in 40 breast cancer specimens. Next, we find that GRHL2 and CD24 expression coincide with an epithelial character in human mammary epithelial cells. Further, we show that high GRHL2 expression is highly correlated with worse relapse-free survival in all four subtypes of breast cancer. Finally, we integrate CD24, GRHL2, and ESRP1 into a mathematical model of EMT regulation to validate the role of these players in EMT. Our data analysis and modeling results highlight the relationships among multiple crucial EMT/MET drivers including ZEB1, GRHL2, CD24, and ESRP1, particularly in basal-like breast cancers, which are most similar to triple-negative breast cancer (TNBC) and are considered the most dangerous subtype. J. Cell. Biochem. 118: 2559-2570, 2017. © 2017 Wiley Periodicals, Inc.