Oceanic oxygen deficient zones (ODZs) influence global biogeochemical cycles in a variety of ways, most notably by acting as a sink for fixed nitrogen (Codispoti et al. 2001). Optimum multiparameter analysis of data from two cruises in the Eastern Tropical North Pacific (ETNP) was implemented to develop a water mass analysis for the large ODZ in this region. This analysis reveals that the most pronounced oxygen deficient conditions are within the 13 C water (13CW) mass, which is distributed via subsurface mesoscale features such as eddies branching from the California Undercurrent. Nitrite accumulates within these eddies and slightly below the core of the 13CW. This water mass analysis also reveals that the 13CW and deeper Northern Equatorial Pacific Intermediate Water (NEPIW) act as the two Pacific Equatorial source waters to the California Current System. The Equatorial Subsurface Water and Subtropical Subsurface Water are synonymous with the 13CW and this study refers to this water mass as the 13CW based on its history. Since the 13CW has been found to dominate the most pronounced oxygen deficient conditions within the Eastern Tropical South Pacific ODZ and the Peru-Chile Undercurrent, the 13CW and the NEPIW define boundaries for oxygen minimum conditions across the entire eastern Pacific Ocean.

Transient elevations of cytosolic Ca 2؉ are a common mechanism of cellular signaling. In striated muscle, the sarco(endo)plasmic reticulum Ca 2؉ ATPase (SERCA) plays an important role in terminating Ca 2؉ transients by returning cytosolic Ca 2؉ to intracellular stores. Stored Ca 2؉ can then be released again for subsequent signaling. We down-regulated SERCA2 gene expression in cultured cardiac myocytes by means of endogenous transcription of small interfering RNA encoded by an exogenous cDNA template. The cDNA template was delivered by adenovirus vector. Reduction of SERCA expression in all myocytes in culture was documented by immunochemistry, real-time RT-PCR, and determination of ATP-dependent Ca 2؉ transport. The reduction of SERCA2 expression was associated with the up-regulation of transient receptor potential (TRP) channel proteins (TRPC4 and TRPC5) and Na ؉ ͞Ca 2؉ exchanger, indicating that intracellular store deficiency was compensated for by Ca 2؉ fluxes through the plasma membrane. In fact, SERCA silencing was followed by increased transcription of Na ؉ ͞ Ca 2؉ exchanger, TRPC4, TRPC5, and related transcriptional factors, such as stimulating protein 1, myocyte enhancer factor 2, and nuclear factor of activated cells 4, through activation of calcineurin. This finding demonstrates that the observed compensation occurs through transcriptional crosstalk and the remodeling of Ca 2؉ signaling pathways. The wide significance of this regulatory mechanism is related to its general involvement in Ca 2؉ signaling dynamics and in cardiac development and hypertrophy.Na ϩ ͞Ca 2ϩ exchanger ͉ transient receptor potential channel ͉ calcineurin ͉ small interfering RNA N umerous cellular functions, including motility, secretion, and gene activation, are triggered by a rise of cytosolic Ca 2ϩ after electrical or chemical excitation of the plasma membrane (1, 2). Trigger Ca 2ϩ derives from intracellular stores and͞or extracellular fluids and reaches the cytosol by diffusion through gated channels as permitted by large concentration gradients. When membrane excitation ceases, Ca 2ϩ is returned to intracellular stores by the sarco(endo)plasmic reticulum Ca 2ϩ ATPase (SERCA) or to extracellular fluid by the plasma membrane Ca 2ϩ ATPase and the Na ϩ ͞Ca 2ϩ exchanger (NCX).In cardiac muscle, intracellular Ca 2ϩ stores and the Ca 2ϩ ATPase (SERCA2 isoform) of sarcoplasmic reticulum play a prominent role in contractile activation and relaxation (3-5). In fact, SERCA overexpression in transgenic animals (6, 7) and in cultured myocytes (8-11) improves the signaling of Ca 2ϩ spikes under limiting conditions. On the other hand, SERCA2 genetargeting does not allow development of homozygous mice with SERCA2-null mutations, whereas heterozygous mutants manifest altered Ca 2ϩ homeostasis in cardiac muscle (12, 13). We report here that SERCA2 gene expression can be strongly reduced in cultured cardiac myocytes by endogenous production of small interfering RNA (siRNA) encoded by an exogenous cDNA template. Adenovirus vectors ensure homoge...

Live cell imaging of mammalian RNA polymerase II (Pol II) has previously relied on random insertions of exogenous, mutant Pol II coupled with the degradation of endogenous Pol II using a toxin, α-amanitin. Therefore, it has been unclear whether over-expression of labeled Pol II under an exogenous promoter may have played a role in reported Pol II dynamics in vivo. Here we label the endogenous Pol II in mouse embryonic fibroblast (MEF) cells using the CRISPR/Cas9 gene editing system. Using single-molecule based super-resolution imaging in the living cells, we captured endogenous Pol II clusters. Consistent with previous studies, we observed that Pol II clusters were short-lived (cluster lifetime ~8 s) in living cells. Moreover, dynamic responses to serum-stimulation, and drug-mediated transcription inhibition were all in agreement with previous observations in the exogenous Pol II MEF cell line. Our findings suggest that previous exogenously tagged Pol II faithfully recapitulated the endogenous polymerase clustering dynamics in living cells, and our approach may in principle be used to directly label transcription factors for live cell imaging.

While the impact of air pollution on human health is well studied, mechanistic impacts of air pollution on wild systems, including those providing essential ecosystem services, are largely unknown, but directly impact our health and well-being. India is the world’s largest fruit producer, second most populous country, and contains 9 of the world’s 10 most polluted cities. Here, we sampled Giant Asian honey bees, Apis dorsata, at locations with varying air pollution levels in Bangalore, India. We observed significant correlations between increased respirable suspended particulate matter (RSPM) deposition and changes in bee survival, flower visitation, heart rate, hemocyte levels, and expression of genes related to lipid metabolism, stress, and immunity. Lab-reared Drosophila melanogaster exposed to these same sites also exhibited similar molecular and physiological differences. Our study offers a quantitative analysis on the current impacts of air pollution on insects, and indicates the urgency for more nonhuman studies to accurately assess the effects of pollution on our natural world.

Abstract. Emissions of ice-nucleating particles (INPs) from sea spray can impact climate and precipitation by changing cloud formation, precipitation, and albedo. However, the relationship between seawater biogeochemistry and the ice nucleation activity of sea spray aerosols remains unclarified. Here, we demonstrate a link between the biological productivity in seawater and the ice nucleation activity of sea spray aerosol under conditions relevant to cirrus and mixed-phase cloud formation. We show for the first time that aerosol particles generated from both subsurface and microlayer seawater from the highly productive eastern tropical North Pacific Ocean are effective INPs in the deposition and immersion freezing modes. Seawater particles of composition similar to subsurface waters of highly productive regions may therefore be an unrealized source of effective INPs. In contrast, the subsurface water from the less productive Florida Straits produced less effective immersion mode INPs and ineffective depositional mode INPs. These results indicate that the regional biogeochemistry of seawater can strongly affect the ice nucleation activity of sea spray aerosol.