SMAD3 directly regulates cell cycle genes to maintain arrest in granulosa cells of mouse primordial follicles

Primordial follicles, consisting of granulosa cell (GC)-enveloped oocytes are maintained in a state of developmental arrest until activated to grow. The mechanism that operates to maintain this arrested state in GCs is currently unknown. Here, we show the TGFβ-activated transcription factor SMAD3 is expressed in primordial GC nuclei alongside the cell cycle proteins, cyclin D2 (CCND2) and P27. Using neonatal C57/Bl6 mouse ovaries densely populated with primordial follicles, CCND2 protein co-localised and was detected in complex with P27 by immunofluorescence and co-immunoprecipitation, respectively. In the same tissue, SMAD3 co-precipitated with DNA sequences upstream of Ccnd2 and Myc transcription start sites implicating both as direct SMAD3 targets. In older ovaries follicle growth was associated with nuclear exclusion of SMAD3 and reduced P27 and CCND2 in GCs, alongside elevated Myc expression. Brief (2 H) exposure of neonatal ovaries to TGFβ1 (10 ng/ml) in vitro led to immediate dissociation of SMAD3 from the Ccnd2 and Myc promoters. This coincided with elevated Myc and phospho-S6, an indicator of mTOR signalling, followed by a small increase in mean primordial GC number after 48 H. These findings highlight a concentration-dependent role for TGFβ signalling in the maintenance and activation of primordial follicles, through SMAD-dependent and independent signalling pathways, respectively

Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays

Average charged multiplicities have been measured separately in $b$, $c$ and light quark ($u,d,s$) events from $Z^0$ decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of $b$ and light quark events, and reconstructed charmed mesons were used to select $c$ quark events. We measured the charged multiplicities: $\bar{n}_{uds} = 20.21 \pm 0.10 (\rm{stat.})\pm 0.22(\rm{syst.})$, $\bar{n}_{c} = 21.28 \pm 0.46(\rm{stat.}) ^{+0.41}_{-0.36}(\rm{syst.})$ $\bar{n}_{b} = 23.14 \pm 0.10(\rm{stat.}) ^{+0.38}_{-0.37}(\rm{syst.})$, from which we derived the differences between the total average charged multiplicities of $c$ or $b$ quark events and light quark events: $\Delta \bar{n}_c = 1.07 \pm 0.47(\rm{stat.})^{+0.36}_{-0.30}(\rm{syst.})$ and $\Delta \bar{n}_b = 2.93 \pm 0.14(\rm{stat.})^{+0.30}_{-0.29}(\rm{syst.})$. We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers

Stress Responsiveness Varies over the Ultradian Glucocorticoid Cycle in a Brain-Region-Specific Manner

Glucocorticoid hormones are released in rapid hourly hormone bursts by the adrenal gland. These ultradian oscillations are fundamental to hypothalamic-pituitary-adrenal activity and transcriptional regulation of glucocorticoid responsive genes. The physiological relevance of glucocorticoid pulsatility is however unknown. Using a novel automated infusion system, we artificially created different patterns (modulating pulse amplitude) of corticosterone (cort). Identical amounts of cort either in constant or in hourly pulses were infused into adrenalectomized rats. At the end of the infusion period, either during rising or falling concentrations of a cort pulse, animals were exposed to 99 dB noise stress (10 min). Pulsatile cort infusion led to a differential stress response, dependent on the phase of the pulse during which the stress was applied. Although constant administration of cort resulted in a blunted ACTH response to the stressor, a brisker response occurred during the rising phase of plasma cort than during the falling phase. This phase-dependent effect was also seen in the behavioral response to the stressor, which was again greater during the rising phase of each cort pulse. Within the brain itself, we found differential C-fos activation responses to noise stress in the pituitary, paraventricular nucleus, amygdala, and hippocampus. This effect was both glucocorticoid pulse amplitude and phase dependent, suggesting that different stress circuits are differentially responsive to the pattern of glucocorticoid exposure. Our data suggest that the oscillatory changes in plasma glucocorticoid levels are critical for the maintenance of normal physiological reactivity to a stressor and in addition modulate emotionality and exploratory behavior. (Endocrinology 151: 5369-5379, 2010)Stress hormones and brain functio

Currently cohabiting: relationship attitudes, expectations and outcomes

This study uses prospective data from the British Household Panel Survey to analyse individuals’ relationship expectations and subsequent outcomes between 1998 and 2005. How do relationship expectations differ by age, sex, previous relationship history and parenthood? How do attitudes towards cohabitation differ by age, sex, previous relationship history and parenthood? Prospective data are particularly well suited to answering these questions as the relationship expectations are collected whilst the subjective state exists, allowing systematic empirical investigation of social change

Everyday encounters with context-aware computing in a campus environment

Abstract. As ubiquitous computing technologies mature, they must move out of laboratory settings and into the everyday world. In the process, they will increasingly be used by heterogeneous groups, made up of individuals with different attitudes and social roles. We have been studying an example of this in a campus setting. Our field work highlights the complex relationships between technology use and institutional arrangements – the roles, relationships, and responsibilities that characterize social settings. In heterogeneous groups, concerns such as location, infrastructure, access, and mobility can take on quite different forms, with very different implications for technology design and use.