Stimulation of estrogen receptor accumulation by estradiol in primary cultures of salmon hepatocytes

AbstractHepatocytes of Salmo salar in primary culture form confluent monolayers and can be maintained at 11 °C in serum-free medium for 8 days with minimal cell loss. Cultured hepatocytes from immature male salmon contain estrogen receptor both in nuclear and cytosol fractions (2000 and 2400 sites/cell, respectively). A single addition of estradiol results in an increase in the nuclear receptor to a level of 23 000 sites/cell after 24 h. This nuclear receptor concentration is similar to that in liver of estrogen-treated salmon in vivo, and is much higher than has been found for any other egg-laying vertebrate. The cultured salmon hepatocytes thus represent a highly sensitive system for the study of estrogen receptor dynamics and vitellogenesis in vitro

Convection above the Labrador continental slope

The Labrador Sea is one of the few regions of the World Ocean where deep convection takes place. Several moorings across the Labrador continental slope just north of Hamilton Bank show that convection does take place within the Labrador Current. Mixing above the lower Labrador slope is facilitated by the onshore along-isopycnal intrusions of low-potential-vorticity eddies that weaken the stratification, combined with baroclinic instability that sustains slanted mixing while restratifying the water column through horizontal fluxes. Above the shelf break, the Irminger seawater core is displaced onshore while the stratification weakens with the increase in isopycnal slope. The change in stratification is partially due to the onshore shift of the “classical” Labrador Current, baroclinic instability, and possibly slantwise convection

How does Labrador Sea Water enter the deep western boundary current?

Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 968-983, doi:10.1175/2007JPO3807.1.Labrador Sea Water (LSW), a dense water mass formed by convection in the subpolar North Atlantic, is an important constituent of the meridional overturning circulation. Understanding how the water mass enters the deep western boundary current (DWBC), one of the primary pathways by which it exits the subpolar gyre, can shed light on the continuity between climate conditions in the formation region and their downstream signal. Using the trajectories of (profiling) autonomous Lagrangian circulation explorer [(P)ALACE] floats, operating between 1996 and 2002, three processes are evaluated for their role in the entry of Labrador Sea Water in the DWBC: 1) LSW is formed directly in the DWBC, 2) eddies flux LSW laterally from the interior Labrador Sea to the DWBC, and 3) a horizontally divergent mean flow advects LSW from the interior to the DWBC. A comparison of the heat flux associated with each of these three mechanisms suggests that all three contribute to the transformation of the boundary current as it transits the Labrador Sea. The formation of LSW directly in the DWBC and the eddy heat flux between the interior Labrador Sea and the DWBC may play leading roles in setting the interannual variability of the exported water mass.We are also grateful to the NSF for their support of this research

Coralline algal Barium as indicator for 20th century northwestern North Atlantic surface ocean freshwater variability

During the past decades climate and freshwater dynamics in the northwestern North Atlantic have undergone major changes. Large-scale freshening episodes, related to polar freshwater pulses, have had a strong influence on ocean variability in this climatically important region. However, little is known about variability before 1950, mainly due to the lack of long-term high-resolution marine proxy archives. Here we present the first multidecadal-length records of annually resolved Ba/Ca variations from Northwest Atlantic coralline algae. We observe positive relationships between algal Ba/Ca ratios from two Newfoundland sites and salinity observations back to 1950. Both records capture episodical multi-year freshening events during the 20th century. Variability in algal Ba/Ca is sensitive to freshwater-induced changes in upper ocean stratification, which affect the transport of cold, Ba-enriched deep waters onto the shelf (highly stratified equals less Ba/Ca). Algal Ba/Ca ratios therefore may serve as a new resource for reconstructing past surface ocean freshwater changes

Variability in the Deep Western Boundary Current : local versus remote forcing

Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): C12022, doi:10.1029/2012JC008369.Horizontal velocity, temperature and salinity measurements from the Line W array for the period 2004–2008 show large changes in the water mass structure and circulation of the Deep Western Boundary Current (DWBC). Fluctuations in the flow with periods from 10 to 60 days are bottom intensified: signals most likely associated with topographic Rossby waves (TRW). A fraction (∼15%) of the DWBC transport variability is caused by Gulf Stream rings and meanders. These flow anomalies are surface intensified and fluctuate at frequencies lower than the TRW. Interannual variability in the velocity field appears to be related to changes in the hydrographic properties. The dominant mode of variability is characterized by an overall freshening, cooling, a potential vorticity (PV) increase in the deep Labrador Sea Water (dLSW) and a PV decrease in the Overflow Water (OW). The variability in the flow associated with these property changes is not spatially homogeneous. Offshore (water depths larger than 3500 m) changes in the velocity are in phase with PV changes in the OW: a decrease in the OW PV is accompanied by an increase in the southward (negative) transport. Conversely, variations of the inshore flow are in phase with changes in the dLSW PV (increasing PV and decreasing transport). This trend, true for most of the record, reverses after the winter of 2007–2008. A sudden decrease of the dLSW PV is observed, with a corresponding intensification of the flow in the inner DWBC as well as a northward shift in the Gulf Stream axis.Financial support for the Line W program (2004–2008) was provided by the U.S. National Science Foundation (grants OCE-0241354 and OCE-0726720) as well as funding from the WHOI’s Ocean and Climate Change Institute.2013-06-2

The role of salinity in the decadal variability of the North Atlantic meridional overturning circulation

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Climate Dynamics 33 (2009): 777-793, doi:10.1007/s00382-008-0523-2.An OGCM hindcast is used to investigate the linkages between North Atlantic Ocean salinity and circulation changes during 1963–2003. The focus is on the eastern subpolar region consisting of the Irminger Sea and the eastern North Atlantic where a careful assessment shows that the simulated interannual to decadal salinity changes in the upper 1500 m reproduce well those derived from the available record of hydrographic measurements. In the model, the variability of the Atlantic meridional overturning circulation (MOC) is primarily driven by changes in deep water formation taking place in the Irminger Sea and, to a lesser extent, the Labrador Sea. Both are strongly influenced by the North Atlantic Oscillation (NAO). The modeled interannual to decadal salinity changes in the subpolar basins are mostly controlled by circulation-driven anomalies of freshwater flux convergence, although surface salinity restoring to climatology and other boundary fluxes each account for approximately 25% of the variance. The NAO plays an important role: a positive NAO phase is associated with increased precipitation, reduced northward salt transport by the wind-driven intergyre gyre, and increased southward flows of freshwater across the Greenland-Scotland ridge. Since the NAO largely controlled deep convection in the subpolar gyre, fresher waters are found near the sinking region during convective events. This markedly differs from the active influence on the MOC that salinity exerts at decadal and longer timescales in most coupled models. The intensification of the MOC that follows a positive NAO phase by about 2 years does not lead to an increase in the northward salt transport into the subpolar domain at low frequencies because it is cancelled by the concomitant intensification of the subpolar gyre which shifts the subpolar front eastward and reduces the northward salt transport by the North Atlantic Current waters. This differs again from most coupled models, where the gyre intensification precedes that of the MOC by several years.Support from NSF Grant 82677800 with the Woods Hole Oceanographic Institution, and (to CF) from the Institut universitaire de France and European FP6 project DYNAMITE (contract 003903-GOCE) and (to JD) from the NOAA Office of Hydrologic Development through a scientific appointment administered by UCAR is gratefully acknowledged

High-temperature dynamic hohlraums on the pulsed power driver Z

In the concept of the dynamic hohlraum an imploding z-pinch is optically thick to its own radiation. Radiation may be trapped inside the pinch to give a radiation temperature inside the pinch greater than that outside the pinch. The radiation is typically produced by colliding an outer Z-pinch liner onto an inner liner. The collision generates a strongly radiating shock, and the radiation is trapped by the outer liner. As the implosion continues after the collision the radiation temperature may continue to increase due to ongoing PdV (pressure times change in volume) work done by the implosion. In principal the radiation temperature may increase to the point at which the outer liner burns through, becomes optically thin, and no longer traps the radiation. One application of the dynamic hohlraum is to drive an ICF (inertial confinement fusion) pellet with the trapped radiation field. Members of the dynamic hohlraum team at Sandia National Labs have used the pulsed power driver Z (20 LMA, 100 ns) to create a dynamic hohlraum with temperature linearly ramping from 100 to 180 eV over 5 ns. On this shot zp214 a nested tungsten wire array of 4 and 2 cm diameters with masses of 2 and 1 mg imploded onto a 2.5 mg plastic annulus at 5 mm diameter. The current return can on this shot was slotted. It is likely the radiation temperature may be increased to over 200 CV by stabilizing the pinch with a solid current return can. A current return can with 9 slots imprints 9 filaments onto the imploding pinch. This degrades the optical trapping and the quality of the liner collision. A 1.6 mm diameter capsule situated inside this dynamic hohlraum of zp214 would see 15 kJ of radiation impinging on its surface before the pinch itself collapses to a 1.6 mm diameter. Dynamic hohlraum shots including pellets are scheduled to take place on Z in September of 1998

The oxidative metabolism of estrogens by mammalian liver

The main problem of estrogen metabolism studied has been to determine the nature of the water-soluble products formed from estrone-16-C¹⁴ by rat liver preparations. Comparative studies were carried out in the guinea pig. Three types of water-soluble metabolites were demonstrated, namely, protein-bound derivatives, glucosiduronate conjugates, and unidentified products which were not bound to protein and were not hydrolysed by 2N HC1. The water-soluble metabolites formed on incubating rat or guinea pig liver microsomes with estrone-16-C¹⁴ in the presence of NADPH and oxygen consisted of protein-bound material, some unknown derivatives, but virtually no simple conjugates. Incubation with the rat liver 8000 x g supernatant fraction resulted largely in conversion of the estrogen to the unknown water-soluble end-products, while in contrast, this liver fraction from guinea pig gave rise mainly to glucosiduronates. In the presence of UDPGA, both rat and guinea pig liver microsomes converted estrone-16-C¹⁴ to glucosiduronate conjugates, but this did not occur with the rat liver 8000 x g supernatant fraction. Estradiol-17β-16-C¹⁴and stilbestrol-C¹⁴ behaved similarly to estrone-16-C¹⁴. In the rat, in vivo, the bulk of the urinary water-soluble derivatives of estrone were of unknown nature, while in the guinea pig, glucosiduronate conjugation predominated. The problem was also studied by a different approach. Various compounds having structural features similar to estrone were tested for their ability to inhibit the formation of water-soluble metabolites from this estrogen by rat liver microsomes. It was found that 2-hydroxyestrone, 2-hydroxyestradiol-17β and equilenin were potent inhibitors, while those estrogens which had an oxygen function at C-6 or C-16, as well as the 17β-glucosiduronates and non-phenolic steroids tested were inactive. The synthetic estrogens, stilbestrol and hexestrol, both inhibited the reaction, but their non-estrogenic analogues had no effect. A group of benzoquinones, naphthoquinones and ortho- and para-hydroxylated phenols proved to be powerful inhibitors, whereas anthraquinones and meta-hydroxy-lated phenols showed no activity. In kinetic studies, 2-hydroxyestrone, equilenin, and stilbestrol appeared to act as competitive inhibitors, but menadione gave a mixed type of inhibition.Medicine, Faculty ofBiochemistry and Molecular Biology, Department ofGraduat