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Neurotrophin-regulated signalling pathways
Neurotrophins are a family of closely related proteins that were identified initially as survival factors for sensory and sympathetic neurons, and have since been shown to control many aspects of survival, development and function of neurons in both the peripheral and the central nervous systems. Each of the four mammalian neurotrophins has been shown to activate one or more of the three members of the tropomyosin-related kinase (Trk) family of receptor tyrosine kinases (TrkA, TrkB and TrkC). In addition, each neurotrophin activates p75 neurotrophin receptor (p75NTR), a member of the tumour necrosis factor receptor superfamily. Through Trk receptors, neurotrophins activate Ras, phosphatidyl inositol-3 (PI3)-kinase, phospholipase C-γ1 and signalling pathways controlled through these proteins, such as the MAP kinases. Activation of p75NTR results in activation of the nuclear factor-κB (NF-κB) and Jun kinase as well as other signalling pathways. Limiting quantities of neurotrophins during development control the number of surviving neurons to ensure a match between neurons and the requirement for a suitable density of target innervation. The neurotrophins also regulate cell fate decisions, axon growth, dendrite growth and pruning and the expression of proteins, such as ion channels, transmitter biosynthetic enzymes and neuropeptide transmitters that are essential for normal neuronal function. Continued presence of the neurotrophins is required in the adult nervous system, where they control synaptic function and plasticity, and sustain neuronal survival, morphology and differentiation. They also have additional, subtler roles outside the nervous system. In recent years, three rare human genetic disorders, which result in deleterious effects on sensory perception, cognition and a variety of behaviours, have been shown to be attributable to mutations in brain-derived neurotrophic factor and two of the Trk receptors.
Journal Article
Transgender Demographics: A Household Probability Sample of US Adults, 2014
Objectives. To estimate the proportion of US adults who identify as transgender and to compare the demographics of the transgender and nontransgender populations. Methods. We conducted a secondary analysis of data from states and territories in the 2014 Behavioral Risk Factor Surveillance System that asked about transgender status. The proportion of adults identified as transgender was calculated from affirmative and negative responses (n = 151 456). We analyzed data with a design-adjusted χ 2 test. We also explored differences between male-to-female and nontransgender females and female-to-male and nontransgender males. Results. Transgender individuals made up 0.53% (95% confidence interval = 0.46, 0.61) of the population and were more likely to be non-White (40.0% vs 27.3%) and below the poverty line (26.0% vs 15.5%); as likely to be married (50.5% vs 47.7%), living in a rural area (28.7% vs 22.6%), and employed (54.3% vs 57.7%); and less likely to attend college (35.6% vs 56.6%) compared with nontransgender individuals. Conclusions. Our findings suggest that the transgender population is a racially diverse population present across US communities. Inequalities in the education and socioeconomic status have negative implications for the health of the transgender population.
Journal Article
Observation of high-order harmonic generation in a bulk crystal
High-order harmonic generation is a nonlinear optical process that enables the creation of light pulses at frequencies much higher than that from a seed laser. The host medium for this interaction is typically a gas. Now, the process has been observed in a bulk crystalline solid with important implications for attosecond science.
Harmonic generation is a general feature of driven nonlinear systems. In particular high-order harmonic generation (HHG) in atomic gases
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is the basis for producing attosecond pulses
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,
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. In molecules and clusters, the existence of multiple ionization and recombination sites makes for richer dynamics allowing imaging of molecular orbitals
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,
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, higher conversion efficiency
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and the possibility of extending the high-energy cutoff
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. In the strong-field limit, HHG in bulk crystals is fundamentally different from that in the atomic case owing to the high density and periodic structure. Here we present the first observation of HHG in a bulk crystalline solid using a long-wavelength few-cycle laser. The harmonics spectra extend well beyond the band edge of the ZnO crystal, show a clear non-perturbative character and exhibit a cutoff that scales linearly with the electric field of the drive laser. Our results have important implications for the understanding of attosecond electron dynamics and other non-equilibrium band-structure-related phenomena in strongly driven bulk solids.
Journal Article
Differing structures of galactoglucomannan in eudicots and non-eudicot angiosperms
The structures of cell wall mannan hemicelluloses have changed during plant evolution. Recently, a new structure called β-galactoglucomannan (β-GGM) was discovered in eudicot plants. This galactoglucomannan has β-(1,2)-Gal-α-(1,6)-Gal disaccharide branches on some mannosyl residues of the strictly alternating Glc-Man backbone. Studies in Arabidopsis revealed β-GGM is related in structure, biosynthesis and function to xyloglucan. However, when and how plants acquired β-GGM remains elusive. Here, we studied mannan structures in many sister groups of eudicots. All glucomannan structures were distinct from β-GGM. In addition, we searched for candidate mannan β-galactosyltransferases (MBGT) in non-eudicot angiosperms. Candidate At MBGT1 orthologues from rice ( Os GT47A-VII) and Amborella ( Atr GT47A-VII) did not show MBGT activity in vivo . However, the At MBGT1 orthologue from rice showed MUR3-like xyloglucan galactosyltransferase activity in complementation analysis using Arabidopsis. Further, reverse genetic analysis revealed that the enzyme ( Os GT47A-VII) contributes to proper root growth in rice. Together, gene duplication and diversification of GT47A-VII in eudicot evolution may have been involved in the acquisition of mannan β-galactosyltransferase activity. Our results indicate that β-GGM is likely to be a eudicot-specific mannan.
Journal Article
Individual Differences in the Amount and Timing of Salivary Melatonin Secretion
The aim of this study was to examine individual differences in a large sample of complete melatonin profiles not suppressed by light and search for possible associations between the amount and timing of melatonin secretion and a multitude of lifestyle variables. The melatonin profiles were derived from saliva samples collected every 30 minutes in dim light from 85 healthy women and 85 healthy men aged 18-45 years. There was a large individual variability in the amount of melatonin secreted with peak values ranging from 2 to 84 pg/ml. The onset of melatonin secretion ranged from 18:13 to 00:26 hours. The use of hormonal birth control, reduced levels of employment, a smaller number of days on a fixed sleep schedule, increased day length and lower weight were associated with an increased amplitude of melatonin secretion. The use of hormonal birth control, contact lenses, a younger age, and lower ratings of mania and paranoia were associated with a longer duration of melatonin secretion. An earlier occurrence of the onset of melatonin secretion was associated with an earlier wake time, more morningness and the absence of a bed partner. Lifestyle and behavioral variables were only able to explain about 15% of the individual variability in the amount of melatonin secretion, which is likely because of a substantial genetic influence on the levels of melatonin secretion.
Journal Article