Polar front associated variation in prokaryotic community structure in Arctic shelf seafloor

Abstract

Spatial variations in composition of marine microbial communities and its causes have largely been disclosed in studies comprising rather large environmental and spatial differences. In the present study, we explored if a moderate but temporally permanent climatic division within a contiguous arctic shelf seafloor was traceable in the diversity patterns of its bacterial and archaeal communities. Soft bottom sediment samples were collected at 10 geographical locations, spanning spatial distances of up to 640 km, transecting the oceanic polar front in the Barents Sea. The northern sampling sites were generally colder, less saline, shallower, and showed higher concentrations of freshly sedimented phytopigments compared to the southern study locations. Sampling sites depicted low variation in relative abundances of taxa at class level, with persistent numerical dominance by lineages of Gamma- and Deltaproteobacteria (57–66% of bacterial sequence reads). The Archaea, which constituted 0.7–1.8% of 16S rRNA gene copy numbers in the sediment, were overwhelmingly (85.8%) affiliated with the Thaumarchaeota. Beta-diversity analyses showed the environmental variations throughout the sampling range to have a stronger impact on the structuring of both the bacterial and archaeal communities than spatial effects. While bacterial communities were significantly influenced by the combined effect of several weakly selective environmental differences, including temperature, archaeal communities appeared to be more uniquely structured by the level of freshly sedimented phytopigments.

HIV-1 TAT protein enhances sensitization to methamphetamine by affecting dopaminergic function

“…However, intra-Acb injections of TAT before or after acquisition of cocaine sensitization have been shown to decrease sensitized locomotor responses (Ferris et al 2010; Harrod et al 2008). Similarly, intra-VTA TAT injections attenuate nicotine sensitization in rats (Zhu et al 2015). However, it is not known whether acute local injections of the TAT protein are comparable to the prolonged TAT expression of TAT-expressing mouse model utilized in our study (Paris et al 2014b).…”

The effects of HIV-1 regulatory TAT protein expression on brain reward function, response to psychostimulants and delay-dependent memory in mice

“…However, our findings do not preclude that other methods may reveal TAT-induced alterations in sensitivity to the rewarding effects of nicotine or the potential for alterations in the response to nicotine during acute TAT protein expression. Recent work demonstrated decreased nicotine-induced locomotor sensitization in HIV-1 transgenic rats (Midde et al, 2011) and after infusions of TAT into the ventral tegmental area in rats (Zhu et al, 2015). These findings suggest that the TAT protein may reduce sensitivity to nicotine.…”

A Unique Benthic Microbial Community Underlying the Phaeocystis antarctica-Dominated Amundsen Sea Polynya, Antarctica: A Proxy for Assessing the Impact of Global Changes

“…In marine surface sediments, microorganisms occur in enormous numbers (approximately 1.7 × 10 28 cells worldwide) (Whitman et al, 1998), are extremely diverse (Huber et al, 2007), and are notably involved in global carbon, nitrogen, and sulfur cycles (Canfield et al, 2005;Orcutt et al, 2011). Because microbial community composition, diversity, and metabolic activity are significantly influenced by environmental change (Bertics and Ziebis, 2009;Nguyen and Landfald, 2015;Sebastián et al, 2018;Kim et al, 2019;Richert et al, 2019), characterization of microbial distribution provides relevant information on spatial and temporal variations in environmental conditions (Fuhrman, 2009;Schauer et al, 2010;Robador et al, 2016). However, little is known about benthic microbial communities in the Southern Ocean (SO), where environmental changes due to global warming are occurring rapidly (Baldi et al, 2010;Ruff et al, 2014;Learman et al, 2016).…”