61 research outputs found
Double Anus in an \u3ci\u3eIxodes scapularis\u3c/i\u3e Nymph, a Medically Important Tick Vector
Background: Ixodes scapularis ticks are medically important arthropod vectors that transmit several pathogens to humans. The observations of morphological abnormalities, including nanism, missing leg, extra leg, and gynandromorphism, have been reported in these ticks. In this study, we report the presence of two anuses in a laboratory-reared I. scapularis nymph.
Results: Larval ticks were allowed to feed on mice and to molt to nymphs. Two anuses were observed in one of the freshly molted nymphs. Stereo and scanning electron microscopy confirmed the presence of two anuses in one nymph within a single anal groove.
Conclusions: This report confirms the rare occurrence of double anus in I. scapularis
Cell Surface-Binding Sites for Progesterone Mediate Calcium Uptake in Human Sperm
Recent studies (e.g. Blackmore, P. F., Beebe, S. J., Danforth, D. R., and Alexander, N.) (1990) J. Biol. Chem. 265, 1376-1380) have shown that in human sperm, progesterone produces a rapid increase in intracellular free calcium ([Ca2+]i) and an induction of the acrosome reaction (e.g. Osman, R. A., Andria, M. L., Jones, A. D., and Meizel, S. (1989) Biochem. Biophys. Res. Commun. 160, 828-833). In this study, the location of progesterone receptors on the cell surface of human sperm was identified using progesterone immobilized on bovine serum albumin (BSA) (progesterone 3-(O-carboxymethyl)oxime:BSA) as well as progesterone and its 3-O-carboxymethyloxime derivative. Using fluorescence microscopy, BSA-fluorescein isothiocyanate was shown to be excluded from intact sperm, thus validating the use of progesterone 3-(O-carboxymethyl)oxime:BSA to identify cell surface-binding sites for progesterone. The immobilized progesterone and the 3-O-carboxymethyloxime derivative rapidly increased [Ca2+]i and were full agonists, although they were approximately 1.5 orders of magnitude less potent than progesterone. They also displayed an identical time course to increase [Ca2+]i as free progesterone, and the entire increase in [Ca2+]i was due to the influx of Ca2+. This progesterone-mediated response displayed different steroid receptor characteristics since the very potent inhibitors of genomic progesterone responses, RU38486 and ZK98.299, were very ineffective at inhibiting the progesterone-mediated increase in [Ca2+]i. Also the synthetic progestins megestrol, medroxyprogesterone acetate, norgestrel, norethynodrel, norethindrone, R5020, and cyproterone acetate did not mimic the effects of progesterone to increase [Ca2+]i. It is proposed that a distinct nongenomic cell surface receptor for progesterone exists in human sperm
Sodium content as a predictor of the advanced evolution of globular cluster stars
The asymptotic giant branch (AGB) phase is the final stage of nuclear burning
for low-mass stars. Although Milky Way globular clusters are now known to
harbour (at least) two generations of stars they still provide relatively
homogeneous samples of stars that are used to constrain stellar evolution
theory. It is predicted by stellar models that the majority of cluster stars
with masses around the current turn-off mass (that is, the mass of the stars
that are currently leaving the main sequence phase) will evolve through the AGB
phase. Here we report that all of the second-generation stars in the globular
cluster NGC 6752 -- 70 per cent of the cluster population -- fail to reach the
AGB phase. Through spectroscopic abundance measurements, we found that every
AGB star in our sample has a low sodium abundance, indicating that they are
exclusively first-generation stars. This implies that many clusters cannot
reliably be used for star counts to test stellar evolution timescales if the
AGB population is included. We have no clear explanation for this observation.Comment: Published in Nature (online 29 May 2013, hard copy 13 June), 12
pages, 3 figures + supplementary information sectio
Countering the Modern Metabolic Disease Rampage With Ancestral Endocannabinoid System Alignment
When primitive vertebrates evolved from ancestral members of the animal kingdom and acquired complex locomotive and neurological toolsets, a constant supply of energy became necessary for their continued survival. To help fulfill this need, the endocannabinoid (eCB) system transformed drastically with the addition of the cannabinoid-1 receptor (CB1R) to its gene repertoire. This established an eCB/CB1R signaling mechanism responsible for governing the whole organism's energy balance, with its activation triggering a shift toward energy intake and storage in the brain and the peripheral organs (i.e., liver and adipose). Although this function was of primal importance for humans during their pre-historic existence as hunter-gatherers, it became expendable following the successive lifestyle shifts of the Agricultural and Industrial Revolutions. Modernization of the world has further increased food availability and decreased energy expenditure, thus shifting the eCB/CB1R system into a state of hyperactive deregulated signaling that contributes to the 21st century metabolic disease pandemic. Studies from the literature supporting this perspective come from a variety of disciplines, including biochemistry, human medicine, evolutionary/comparative biology, anthropology, and developmental biology. Consideration of both biological and cultural evolution justifies the design of improved pharmacological treatments for obesity and Type 2 diabetes (T2D) that focus on peripheral CB1R antagonism. Blockade of peripheral CB1Rs, which universally promote energy conservation across the vertebrate lineage, represents an evolutionary medicine strategy for clinical management of present-day metabolic disorders
3,4-Methylenedioxymethamphetamine Activates Nuclear Factor- κB, Increases Intracellular Calcium, and Modulates Gene Transcription in Rat Heart Cells
3,4-Methylenedioxymethamphetamine (MDMA) is an illicit psychoactive drug that has gained immense popularity among teenagers and young adults. The cardiovascular toxicological consequences of abusing this compound have not been fully characterized. The present study utilized a transient transfection/dual luciferase genetic reporter assay, fluorescence confocal microscopy, and gene expression macroarray technology to determine nuclear factor-κB (NF-κB) activity, intracellular calcium balance, mitochondrial depolarization, and gene transcription profiles, respectively, in cultured rat striated cardiac myocytes (H9c2) exposed to MDMA. At concentrations of 1×10−3 M and 1×10−2 M, MDMA significantly enhanced NF-κB reporter activity compared with 0 M (medium only) control. This response was mitigated by cotransfection with IκB for 1×10−3 M but not 1×10−2 M MDMA. MDMA significantly increased intracellular calcium at concentrations of 1×10−3 M and 1×10−2 M and caused mitochondrial depolarization at 1×10−2 M. MDMA increased the transcription of genes that are considered to be biomarkers in cardiovascular disease and genes that respond to toxic indults. Selected gene activation was verified via temperature-gradient RT-PCR conducted with annealing temperatures ranging from 50°C to 65°C. Collectively, these results suggest that MDMA may be toxic to the heart through its ability to activate the myocardial NF-κB response, disrupt cytosolic calcium and mitochondrial homeostasis, and alter gene transcription
Cyanogen in NGC 1851 red giant branch and asymptotic giant branch stars: Quadrimodal distributions
The Galactic globular cluster NGC 1851 has raised much interest since Hubble Space Telescope photometry revealed that it hosts a double subgiant branch. Here we report on our homogeneous study into the cyanogen (CN) band strengths in the red giant branc
An approach for solving the boundary free edge difficulties in SPH modelling: application to a viscous accretion disc in close binaries
In this work, we propose a SPH interpolating Kernel reformulation suitable
also to treat free edge boundaries in the computational domain. Application to
both inviscid and viscous stationary low compressibility accretion disc models
in Close Binaries (CB) are shown. The investigation carried out in this paper
is a consequence of the fact that a low compressibility modelling is crucial to
check numerical reliability.
Results show that physical viscosity supports a well-bound accretion disc
formation, despite the low gas compressibility, when a Gaussian-derived Kernel
(from the Error Function) is assumed, in extended particle range - whose Half
Width at Half Maximum (HWHM) is fixed to a constant value - without any
spatial restrictions on its radial interaction (hereinafter GASPHER). At the
same time, GASPHER ensures adequate particle interpolations at the boundary
free edges. Both SPH and adaptive SPH (hereinafter ASPH) methods lack accuracy
if there are not constraints on the boundary conditions, in particular at the
edge of the particle envelope: Free Edge (FE) conditions. In SPH, an
inefficient particle interpolation involves a few neighbour particles; instead,
in the second case, non-physical effects involve both the boundary layer
particles themselves and the radial transport.
Either in a regime where FE conditions involve the computational domain, or
in a viscous fluid dynamics, or both, a GASPHER scheme can be rightly adopted
in such troublesome physical regimes. Despite the applied low compressibiity
condition, viscous GASPHER model shows clear spiral pattern profiles
demonstrating the better quality of results compared to SPH viscous ones.
Moreover a successful comparison of results concerning GASPHER 1D inviscid
shock tube with analytical solution is also reported.Comment: 18 pages, 12 figure
An approach to the Riemann problem in the light of a reformulation of the state equation for SPH inviscid ideal flows: a highlight on spiral hydrodynamics in accretion discs
In physically inviscid fluid dynamics, "shock capturing" methods adopt either
an artificial viscosity contribution or an appropriate Riemann solver
algorithm. These techniques are necessary to solve the strictly hyperbolic
Euler equations if flow discontinuities (the Riemann problem) are to be solved.
A necessary dissipation is normally used in such cases. An explicit artificial
viscosity contribution is normally adopted to smooth out spurious heating and
to treat transport phenomena. Such a treatment of inviscid flows is also widely
adopted in the Smooth Particle Hydrodynamics (SPH) finite volume free
Lagrangian scheme. In other cases, the intrinsic dissipation of Godunov-type
methods is implicitly useful. Instead "shock tracking" methods normally use the
Rankine-Hugoniot jump conditions to solve such problems. A simple, effective
solution of the Riemann problem in inviscid ideal gases is here proposed, based
on an empirical reformulation of the equation of state (EoS) in the Euler
equations in fluid dynamics, whose limit for a motionless gas coincides with
the classical EoS of ideal gases. The application of such an effective solution
to the Riemann problem excludes any dependence, in the transport phenomena, on
particle smoothing resolution length in non viscous SPH flows. Results on
1D shock tube tests, as well as examples of application for 2D turbulence and
2D shear flows are here shown. As an astrophysical application, a much better
identification of spiral structures in accretion discs in a close binary (CB),
as a result of this reformulation is also shown here.Comment: 19 pages, 17 figure
Accretion Discs with an Inner Spiral Density Wave
In Montgomery (2009a), we show that accretion discs in binary systems could
retrogradely precess by tidal torques like the Moon and the Sun on a tilted,
spinning, non-spherical Earth. In addition, we show that the state of matter
and the geometrical shape of the celestial object could significantly affect
the precessional value. For example, a Cataclysmic Variable (CV) Dwarf Novae
(DN) non-magnetic system that shows negative superhumps in its light curve can
be described by a retrogradely precessing, differentially rotating, tilted
disc. Because the disc is a fluid and because the gas stream overflows the
tilted disc and particles can migrate into inner disc annuli, coupled to the
disc could be a retrogradely precessing inner ring that is located near the
innermost annuli of the disc. However, numerical simulations by Bisikalo et al.
(2003, 2004) and this work show that an inner spiral density wave can be
generated instead of an inner ring. Therefore, we show that retrograde
precession in non-magnetic, spinning, tilted CV DN systems can equally be
described by a retrogradely precessing and differentially rotating disc with an
attached retrogradely precessing inner spiral density wave so long as the wave
appears at the same radius as the ring and within the plane of the tilted disc.
We find that the theoretical results generated in this work agree well with the
theoretical results presented in Montgomery (2009a) and thus with the numerical
simulations and select CV DN systems in Montgomery (2009b) that may have a main
sequence secondary. Therefore, pressure effects do need to be considered in CV
DN systems that exhibit negative superhumps if the accretion discs are tilted
and have an inner spiral density wave that is in the plane of the disc
A large C+N+O abundance spread in giant stars of the globular cluster NGC 1851
Abundances of C, N, and O are determined in four bright red giants that span
the known abundance range for light (Na and Al) and s-process (Zr and La)
elements in the globular cluster NGC 1851. The abundance sum C+N+O exhibits a
range of 0.6 dex, a factor of 4, in contrast to other clusters in which no
significant C+N+O spread is found. Such an abundance range offers support for
the Cassisi et al. (2008) scenario in which the double subgiant branch
populations are coeval but with different mixtures of C+N+O abundances.
Further, the Na, Al, Zr, and La abundances are correlated with C+N+O, and
therefore, NGC 1851 is the first cluster to provide strong support for the
scenario in which AGB stars are responsible for the globular cluster light
element abundance variations.Comment: Accepted for publication in ApJ Letter
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