Modeling the Role of the Cell Cycle in Regulating Proteus mirabilis Swarm-Colony Development

We present models and computational results which indicate that the spatial and temporal regularity seen in Proteus mirabilis swarm-colony development is largely an expression of a sharp age of dedifferentiation in the cell cycle from motile swarmer cells to immotile dividing cells (also called swimmer or vegetative cells.) This contrasts strongly with reaction-diffusion models of Proteus behavior that ignore or average out the age structure of the cell population and instead use only density-dependent mechanisms. We argue the necessity of retaining the explicit age structure, and suggest experiments that may help determine the underlying mechanisms empirically. Consequently, we advocate Proteus as a model organism for a multiscale understanding of how and to what extent the life cycle of individual cells affects the macroscopic behavior of a biological system

Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars III. Iron, Magnesium, and Silicon

We use thermochemical equilibrium calculations to model iron, magnesium, and silicon chemistry in the atmospheres of giant planets, brown dwarfs, extrasolar giant planets (EGPs), and low-mass stars. The behavior of individual Fe-, Mg-, and Si-bearing gases and condensates is determined as a function of temperature, pressure, and metallicity. Our results are thus independent of any particular model atmosphere. The condensation of Fe metal strongly affects iron chemistry by efficiently removing Fe-bearing species from the gas phase. Monatomic Fe is the most abundant Fe-bearing gas throughout the atmospheres of EGPs and L dwarfs and in the deep atmospheres of giant planets and T dwarfs. Mg- and Si-bearing gases are effectively removed from the atmosphere by forsterite (Mg2SiO4) and enstatite (MgSiO3) cloud formation. Monatomic Mg is the dominant magnesium gas throughout the atmospheres of EGPs and L dwarfs and in the deep atmospheres of giant planets and T dwarfs. Silicon monoxide (SiO) is the most abundant Si-bearing gas in the deep atmospheres of brown dwarfs and EGPs, whereas SiH4 is dominant in the deep atmosphere of Jupiter and other gas giant planets. Several other Fe-, Mg-, and Si-bearing gases become increasingly important with decreasing effective temperature. In principle, a number of Fe, Mg, and Si gases are potential tracers of weather or diagnostic of temperature in substellar atmospheres.Comment: 42 pages, 15 figures, submitted to the Astrophysical Journa

A Cross-Match of 2MASS and SDSS. II. Peculiar L Dwarfs, Unresolved Binaries, and the Space Density of T Dwarf Secondaries

We present the completion of a program to cross-correlate the SDSS Data Release 1 and 2MASS Point Source Catalog in search for extremely red L and T dwarfs. The program was initiated by Metchev and collaborators, who presented the findings on all newly identified T dwarfs in SDSS DR1, and estimated the space density of isolated T0--T8 dwarfs in the solar neighbourhood. In the current work we present most of the L dwarf discoveries. Our red-sensitive (z-J > 2.75 mag) cross-match proves to be efficient in detecting peculiarly red L dwarfs, adding two new ones, including one of the reddest known L dwarfs. Our search also nets a new peculiarly blue L7 dwarf and, surprisingly, two M8 dwarfs. We further broaden our analysis to detect unresolved binary L or T dwarfs through spectral template fitting to all L and T dwarfs presented here and in the earlier work by Metchev and collaborators. We identify nine probable binaries, six of which are new and eight harbour likely T dwarf secondaries. We combine this result with current knowledge of the mass ratio distribution and frequency of substellar companions to estimate an overall space density of 0.005--0.05 pc^{-3} for individual T0--T8 dwarfs.Comment: Accepted by Ap

The Organizational Effects of Oxytocin on the Central Expression of Estrogen Receptor Alpha and Oxytocin in Adulthood

Background: Previous studies have demonstrated that neonatal manipulation of oxytocin (OT) has effects on the expression of estrogen receptor alpha (ER alpha) and the central production of oxytocin observed in juveniles ( at weaning, 21 days of age). The goal of this study was to determine whether the effects of neonatal manipulation of OT last into adulthood, and if the effects differ from those observed during the early postnatal period. On the first day of life, prairie voles ( Microtus ochrogaster) received one of three doses of OT (High, 3 mu g; Med, 0.3 mu g; Low, 0.03 mu g), an OT antagonist, or isotonic saline. Another group was handled, but not injected. Then as adults, brains were collected, sectioned, and stained for ERa or OT using immunocytochemistry. Results: In females, treatment with OT increased the expression of ERa immunoreactivity in the ventral lateral septum (0.03 mu g) and the ventromedial nucleus of the hypothalamus and central amygdala ( 0.3 g). In males, OT antagonist increased ERa expression in the bed nucleus of the stria terminalis. There was no apparent effect of OT on the number of cells producing OT in the paraventricular nucleus of the hypothalamus. Conclusion: The current results suggest that neonatal manipulation of OT has long-term organizational effects on the expression of ERa in both males and females. The lack of effect on OT neurons in the paraventricular nucleus suggests that some developmental effects of OT previously observed in weanlings do not persist into adulthood. Developmental effects of OT on ERa patterns were sexually dimorphic, dose-dependent, and site-specific

The organizational effects of oxytocin on the central expression of estrogen receptor α and oxytocin in adulthood

Background: Previous studies have demonstrated that neonatal manipulation of oxytocin (OT) has effects on the expression of estrogen receptor alpha (ER alpha) and the central production of oxytocin observed in juveniles ( at weaning, 21 days of age). The goal of this study was to determine whether the effects of neonatal manipulation of OT last into adulthood, and if the effects differ from those observed during the early postnatal period. On the first day of life, prairie voles ( Microtus ochrogaster) received one of three doses of OT (High, 3 mu g; Med, 0.3 mu g; Low, 0.03 mu g), an OT antagonist, or isotonic saline. Another group was handled, but not injected. Then as adults, brains were collected, sectioned, and stained for ERa or OT using immunocytochemistry. Results: In females, treatment with OT increased the expression of ERa immunoreactivity in the ventral lateral septum (0.03 mu g) and the ventromedial nucleus of the hypothalamus and central amygdala ( 0.3 g). In males, OT antagonist increased ERa expression in the bed nucleus of the stria terminalis. There was no apparent effect of OT on the number of cells producing OT in the paraventricular nucleus of the hypothalamus. Conclusion: The current results suggest that neonatal manipulation of OT has long-term organizational effects on the expression of ERa in both males and females. The lack of effect on OT neurons in the paraventricular nucleus suggests that some developmental effects of OT previously observed in weanlings do not persist into adulthood. Developmental effects of OT on ERa patterns were sexually dimorphic, dose-dependent, and site-specific

Stinger utilization and predation in the scorpion \u3ci\u3eParuroctonus boreus\u3c/i\u3e

The utilization of the stinger and the predatory technique of the scorpion, Paruroctonus boreus, was studied under laboratory conditions. During the study, 83 feedings were observed. Age of the scorpions and the percentage of prey stung by them were used to classify the scorpions into groups. The scorpions aged 13–61 days always stung prey. After 62 days the scorpions began to selectively utilize the stinger. Utilization declined until it reached 30 percent in the adult stage. The stinger is apparently necessary for prey capture only in the early life stages

Estrogen Receptors in the Medial Amygdala Inhibit the Expression of Male Prosocial Behavior

Studies using estrogen receptor alpha(ER) knock-out mice indicate that ER alpha masculinizes male behavior. Recent studies of ER alpha and male prosocial behavior have shown an inverse relationship between ER alpha expression in regions of the brain that regulate social behavior, including the medial amygdala (MeA), and the expression of male prosocial behavior. These studies have lead to the hypothesis that low levels of ER alpha are necessary to permit the expression of high levels of male prosocial behavior. To test this, viral vectors were used to enhance ER alpha in male prairie voles (Microtus ochrogaster), which display high levels of prosocial behavior and low levels of MeA ER alpha. Adult male prairie voles were transfected with ER alpha in the MeA (MeA-ER alpha) or the caudate-putamen (ER alpha control) or luciferase (MeAsitespecific control), and 3 weeks later tested for spontaneous alloparental behavior and partner preference. Enhancing ER alpha in the MeA altered/reduced male prosocial behavior. Only one-third of MeA-ER alpha males, compared with all control males, were alloparental. Me-A-ER alpha males also displayed a significant preference for a novel female. This is a critical finding because the manipulations of neuropeptides, oxytocin and vasopressin, can inhibit the formation of a partner preference, but do not lead to the formation of a preference for a novel female. The results support the hypothesis that low levels of ER alpha are necessary for high levels of male prosocial behavior, and provide the first direct evidence that site-specific ER alpha expression plays a critical role in the expression of male prosocial behavior

Avaliação da aterosclerose subclínica e de níveis plasmáticos de LDL minimamente modificada em pacientes com espondilite anquilosante e sua correlação com a atividade da doença

AbstractIntroductionAccelerated atherosclerosis has been shown in some autoimmune diseases, mainly in Systemic Lupus Erythematosus and Rheumatoid Arthritis. Although high preva- lence of corticosteroids use may be a confounding factor due to their detrimental effects on several risk factors, systemic inflammation per se is supposed to play an important role in atherogenesis in these patients.MethodsWe have evaluated sub-clinical atherosclerosis and plasma levels of circulating electronegative LDL, which represents the fraction of LDL that is minimally modified, in patients with ankylosing spondylitis (AS). Fourteen patients who fulfilled the modified New York criteria for AS were compared with 13 paired controls. Carotid intimal-media thick- ness (IMT) was assessed by ultrasonography bilaterally in common carotid artery, internal carotid artery and in the bifurcation. Groups were homogeneous regarding cardiovascular risk factors. Only a single patient in AS group was in use of corticosteroid.ResultsThe presence of active inflammation was demonstrated by elevated BASDAI and higher CRP levels and in patients versus controls (12.36 vs. 3.45mg/dl, P = 0.002). No dif- ference was found in carotid IMT between both groups, in any site of artery. Averaged IMT (6 measurements, at 3 pre-specified sites bilaterally) was 0.72 ± 0.28 in AS group and 0.70 ± 0.45mm in controls (P = 0.91). Minimally modified LDL did not differ significantly either between patients and controls (14.03 ± 17.40 vs. 13.21 ± 10.21; P = 0.88).ConclusionsPatients with AS did not show increased carotid IMT in comparison to con- trols. In the same way, circulating plasma levels of LDL (-), did not differ significantly in both groups

Estrogen Receptor-Alpha in the Bed Nucleus of the Stria Terminalis Regulates Social Affiliation in Male Prairie Voles (Microtus Ochrogaster)

Estrogen receptor alpha (ER alpha) typically masculinizes male behavior, while low levels of ER alpha in the medial amygdala (MeA) and the bed nucleus of the stria terminalis (BST) are associated with high levels of male prosocial behavior. In the males of the highly social prairie vole (Microtus ochrogaster), increasing ER alpha in the MeA inhibited the expression of spontaneous alloparental behavior and produced a preference for novel females. To test for the effects of increased ER alpha in the BST, a viral vector was used to enhance ER alpha expression in the BST of adult male prairie voles. Following treatment, adult males were tested for alloparental behavior with 1-3-day- old pups, and for heterosexual social preference and affiliation. Treatment did not affect alloparental behavior as 73% of ER alpha-BST males and 62.5% of control males were alloparental. Increasing ER alpha in the BST affected heterosexual affiliation, with ER alpha-BST males spending significantly less total time in side-by-side contact with females relative to time spent with control males. ER alpha-BST males did not show a preference for either the familiar or novel female. These findings differed significantly from those reported in ER alpha-MeA enhanced males, where ER alpha inhibited alloparental behavior and produced a preference for a novel female. The findings from this study suggest two things: first, that increased ER alpha in the BST decreases social affiliation and second, that altering ER alpha in different regions of the social neural circuit differentially impacts the expression of social behavior