Project description:As much as 400 Tg of carbon from airborne semivolatile aromatic hydrocarbons is deposited to the oceans every year, the largest identified source of anthropogenic organic carbon to the ocean. Microbial degradation is a key sink of these pollutants in surface waters, but has received little attention in polar environments. We have challenged Antarctic microbial communities from the sea-surface microlayer (SML) and the subsurface layer (SSL) with polycyclic aromatic hydrocarbons (PAHs) at environmentally relevant concentrations. PAH degradation rates and the microbial responses at both taxonomical and functional levels were assessed. Evidence for faster removal rates was observed in the SML, with rates 2.6-fold higher than in the SSL. In the SML, the highest removal rates were observed for the more hydrophobic and particle-bound PAHs. After 24 h of PAHs exposure, particle-associated bacteria in the SML showed the highest number of significant changes in their composition. These included significant enrichments of several hydrocarbonoclastic bacteria, especially the fast-growing genera Pseudoalteromonas, which increased their relative abundances by eightfold. Simultaneous metatranscriptomic analysis showed that the free-living fraction of SML was the most active fraction, especially for members of the order Alteromonadales, which includes Pseudoalteromonas. Their key role in PAHs biodegradation in polar environments should be elucidated in further studies. This study highlights the relevant role of bacterial populations inhabiting the sea-surface microlayer, especially the particle-associated habitat, as relevant bioreactors for the removal of aromatic hydrocarbons in the oceans.
Project description:Pregnancy-associated hypertensive (PAH) mice were maintained by mating females carrying the human angiotensinogen (hAGT) gene with males expressing the human renin (hRN) gene, as previously described (Takimoto E., et al., Science, 1996). Angiotensin II (AngII) has critical roles in regulation of blood pressure. In late pregnancy of PAH mice, increased AngII causes acute and severe hypertension with proteinuria. Furthermore, PAH mice show cardiac hypertrophy, fibrosis and apoptosis. It is known that AngII downregulates mRNA of alpha 1a-adrenergic receptor (Adra1a) in neonatal rat cardiac myocytes (Li H.T., et al., Circ. Res., 1997). Interestingly, we found that Adra1a knock out PAH (PAH/aKO) mice display more severe phenotype of cardiac hypertrophy in comparison to PAH mice. In this study, to understand the molecular basis of cardiac hypertrophy via regulation of Adra1a expression with AngII in PAH mice, we performed a comprehensive analysis of gene expression changes in cardiac remodeling of PAH and PAH/aKO mice using the next-generation RNA sequencing (RNA-seq).
Project description:PAH was induced by 60mg/kg MCT and an aorto-caval shunt. At different timepoints of PAH progression (day 14, 21 and 28 after MCT-injection), the left lung with PAH was hemodynamically unloading by unilateral orthotopic transplatation into a syngeneic, healthy recipient. All day 14 and 7/10 day 21 transplanted lungs showed reversal of PAH after LTx. All day 28 and 3/10 day 21 transplanted lungs showed PAH progression after LTx. Lung tissue of Reversible and Irreversible PAH and normal controls, acquired at LTx, was compared using RNA-seq.
Project description:As an essential micronutrient that is scarce in surface ocean waters, zinc (Zn) has the potential to limit oceanic photosynthetic productivity and influence the global carbon cycle. Here we observed Zn co-limitation with iron (Fe) in the natural phytoplankton community of Terra Nova Bay, Antarctica, induced by the drawdown of seawater CO2 and dZn during a bloom. Incubations amended with Zn resulted in significantly higher chlorophyll a content and greater macronutrient and dissolved inorganic carbon drawdown compared to Fe addition alone. Multiple Zn and Fe response proteins were observed in experimental and water column samples demonstrating co-stress in various algal taxa. Together these results demonstrate that Zn limitation can occur in productive Antarctic coastal ecosystems. Thus, Zn may be an important factor limiting the total productivity potential of marine phytoplankton.