NGC 2782: a merger remnant with young stars in its gaseous tidal tail

We have searched for young star-forming regions around the merger remnant NGC 2782. By using Galaxy Evolution Explorer far-ultraviolet and near-ultraviolet imaging and H i data we found seven ultraviolet sources, located at distances greater than 26 kpc from the centre of NGC 2782, and coinciding with its western H i tidal tail. These regions were resolved in several smaller systems when Gemini/Gemini multi-object spectrograph (GMOS) r-band images were used. We compared the observed colours to stellar population synthesis models and found that these objects have ages of similar to 1 to 11 Myr and masses ranging from 103.9 to 104.6 M circle dot. By using Gemini/GMOS spectroscopic data we confirm memberships and derive high metallicities for three of the young regions in the tail (12+log(O/H) = 8.74 +/- 0.20, 8.81 +/- 0.20 and 8.78 +/- 0.20). These metallicities are similar to the value presented by the nuclear region of NGC 2782 and also similar to the value presented for an object located close to the main body of NGC 2782. The high metallicities measured for the star-forming regions in the gaseous tidal tail of NGC 2782 could be explained if they were formed out of highly enriched gas which was once expelled from the centre of the merging galaxies when the system collided. An additional possibility is that the tail has been a nursery of a few generations of young stellar systems which ultimately polluted this medium with metals, further enriching the already pre-enriched gas ejected to the tail when the galaxies collided.

The globular cluster kinematics and galaxy dark matter content of NGC 3923

This paper presents further results from our spectroscopic study of the globular cluster (GC) system of the group elliptical NGC 3923. From observations made with the GMOS instrument on the Gemini South Telescope, an additional 50 GC and ultra-compact dwarf (UCD) candidates have been spectroscopically confirmed as members of the NGC 3923 system. When the recessional velocities of these GCs are combined with the 29 GC velocities reported previously, a total sample of 79 GC/UCD velocities is produced. This sample extends to over 6 arcmin (>6 R-e similar to 30 kpc) from the centre of NGC 3923 and is used to study the dynamics of the GC system and the dark matter content of NGC 3923. It is found that the GC system of NGC 3923 displays no appreciable rotation, and that the projected velocity dispersion is constant with radius within the uncertainties. The velocity dispersion profiles of the integrated light and GC system of NGC 3923 are indistinguishable over the region in which they overlap. We find some evidence that the diffuse light and GCs of NGC 3923 have radially biased orbits within similar to 130 arcsec. The application of axisymmetric orbit-based models to the GC and integrated light velocity dispersion profiles demonstrates that a significant increase in the mass-to-light ratio (from M/L-V = 8 to 26) at large galactocentric radii is required to explain this observation. We therefore confirm the presence of a dark matter halo in NGC 3923. We find that dark matter comprises 17.5(-4.5)(+7.3) per cent of the mass within 1 R-e, 41.2(-10.6)(+18.2) per cent within 2 R-e and 75.6(-16.8)(+15.4) per cent within the radius of our last kinematic tracer at 6.9 R-e. The total dynamical mass within this radius is found to be 1.5(-0.25)(+0.4) x 10(12) M-circle dot. In common with other studies of large ellipticals, we find that our derived dynamical mass profile is consistently higher than that derived by X-ray observations, by a factor of around 2.

Intron 4 polymorphism of the endothelial nitric oxide synthase (eNOS) gene is associated with decreased NO production in a mercury-exposed population

Nitric oxide (NO), produced by endothelial nitric oxide synthase (eNOS), is a potent vasodilator and plays a prominent role in regulating the cardiovascular system. Decreased basal NO release may predispose to cardiovascular diseases. Evidence suggests that the 27 nt repeat polymorphism of the intron 4 in the eNOS gene may regulate eNOS expression. On the other hand, some recent reports strongly suggest an association between methylmercury (MeHg) exposures and altered NO synthesis. In the present study, we investigate the contribution of the 27-pb tandem repeat polymorphism on nitric oxide production, which could enhance susceptibility to cardiovascular disease in the MeHg-exposed study population. Two-hundred-two participants (98 men and 104 women), all chronically exposed to MeHg through fish consumption were examined. Mean blood Hg concentration and nitrite plasma concentration were 50.5 +/- 35.4 mu g/L and 251.4 +/- 106.3 nM, respectively. Mean systolic and diastolic blood pressure were 120.1 +/- 19.4 mm Hg and 72.0 +/- 10.6 mm Hg, respectively. Mean body mass index was 24.5 +/- 4.3 kg/m(2) and the mean heart rate was 69.8 +/- 11.8 bpm. There were no significant differences in age, arterial blood pressure, body mass index or cardiac frequency between genotype groups (all P>0.05). However, we observed different nitrite concentrations in the genotypes groups, with lower nitrite levels for the 4a4a genotype carriers. Age, gender and the presence of intron 4 polymorphism contributed to nitrite reduction as a result of blood Hg concentration. Taken together, our results show that the 27 nt repeat polymorphism of the intron 4 in the eNOS gene increases susceptibility to cardiovascular diseases after MeHg exposure by modulating nitric oxide levels. (C) 2011 Elsevier B.V. All rights reserved.

Synthesis and Antiplasmodial Activity of Betulinic Acid and Ursolic Acid Analogues

More than 40% of the World population is at risk of contracting malaria, which affects primarily poor populations in tropical and subtropical areas. Antimalarial pharmacotherapy has utilised plant-derived products such as quinine and artemisinin as well as their derivatives. However, worldwide use of these antimalarials has caused the spread of resistant parasites, resulting in increased malaria morbidity and mortality. Considering that the literature has demonstrated the antimalarial potential of triterpenes, specially betulinic acid (1) and ursolic acid (2), this study investigated the antimalarial activity against P. falciparum chloroquine-sensitive 3D7 strain of some new derivatives of 1 and 2 with modifications at C-3 and C-28. The antiplasmodial study employed flow cytometry and spectrofluorimetric analyses using YOYO-1, dihydroethidium and Fluo4/AM for staining. Among the six analogues obtained, compounds 1c and 2c showed excellent activity (IC50 = 220 and 175 nM, respectively) while 1a and b demonstrated good activity ( IC50 = 4 and 5 mu M, respectively). After cytotoxicity evaluation against HEK293T cells, 1a was not toxic, while 1c and 2c showed IC50 of 4 mu M and a selectivity index (SI) value of 18 and 23, respectively. Moreover, compound 2c, which presents the best antiplasmodial activity, is involved in the calcium-regulated pathway(s).