Surveying the agents of galaxy evolution in the tidally stripped, low metallicity small Magellanic cloud (SAGE-SMC), III: young stellar objects

The Spitzer Space Telescope Legacy Program SAGE-SMC allows global studies of resolved stellar populations in the SMC in a different environment than our Galaxy. Using the SAGE-SMC IRAC (3.6-8.0 mu m) and MIPS (24 and 70 mu m) catalogs and images combined with near-infrared (JHK(s)) and optical (UBVI) data, we identified a population of similar to 1000 intermediate-to high-mass young stellar objects (YSOs) in the SMC (three times more than previously known). Our method of identifying YSO candidates builds on the method developed for the Large Magellanic Cloud by Whitney et al. with improvements based on what we learned from our subsequent studies and techniques described in the literature. We perform (1) color-magnitude cuts based on five color-magnitude diagrams (CMDs), (2) visual inspection of multi-wavelength images, and (3) spectral energy distribution (SED) fitting with YSO models. For each YSO candidate, we use its photometry to calculate a measure of our confidence that the source is not a non-YSO contaminant, but rather a true YSO, based on the source's location in the color-magnitude space with respect to non-YSOs. We use this CMD score and the SED fitting results to define two classes of sources: high-reliability YSO candidates and possible YSO candidates. We found that, due to polycyclic aromatic hydrocarbon emission, about half of our sources have [3.6]-[4.5] and [4.5]-[5.8] colors not predicted by previous YSO models. The YSO candidates are spatially correlated with gas tracers

Morphology of powerful suction organs from blepharicerid larvae living in raging torrents

BackgroundSuction organs provide powerful yet dynamic attachments for many aquatic animals, including octopus, squid, remora, and clingfish. While the functional morphology of suction organs from some cephalopods and fishes has been investigated in detail, there are only few studies on such attachment devices in insects. Here we characterise the morphology and ultrastructure of the suction attachment organs of net-winged midge larvae (genus Liponeura; Diptera: Blephariceridae) – aquatic insects that live on rocks in rapid alpine waterways where flow speeds can reach 3 m s− 1 – using scanning electron microscopy, confocal laser scanning microscopy, and X-ray computed micro-tomography (micro-CT). Furthermore, we study the function of these organs in vivo using interference reflection microscopy.ResultsWe identified structural adaptations important for the function of the suction attachment organs in L. cinerascens and L. cordata. First, a dense array of spine-like microtrichia covering each suction disc comes into contact with the substrate upon attachment, analogous to hairy structures on suction organs from octopus, clingfish, and remora fish. These spine-like microtrichia may contribute to the seal and provide increased shear force resistance in high-drag environments. Second, specialised rim microtrichia at the suction disc periphery were found to form a continuous ring in close contact and may serve as a seal on a variety of surfaces. Third, a V-shaped cut on the suction disc (“V-notch“) is actively opened via two cuticular apodemes inserting on its flanks. The apodemes are attached to dedicated V-notch opening muscles, thereby providing a unique detachment mechanism. The complex cuticular design of the suction organs, along with specialised muscles that attach to them, allows blepharicerid larvae to generate powerful attachments which can withstand strong hydrodynamic forces and quickly detach for locomotion.ConclusionThe suction organs from Liponeura are underwater attachment devices specialised for resisting extremely fast flows. Structural adaptations from these suction organs could translate into future bioinspired attachment systems that perform well on a wide range of surfaces

Nutrient intakes and nutritional biomarkers in pregnant adolescents: a systematic review of studies in developed countries

Background: Babies born to adolescent mothers have been shown to have poorer outcomes compared to those born to adults. Nutritional status may have an important role to play in improving the health of pregnant adolescents; however there is a lack of evidence regarding the adequacy of adolescent diets during pregnancy. This systematic review aims to examine what is known about the nutritional status of adolescent pregnant women. Methods: A systematic search of the literature identified 21 studies which met the inclusion criteria for the review. Primary research papers using any methods were included where they were published in English between January 1995 and May 2015 and included measurements of nutrient intakes or biological markers of nutritional status in pregnant women aged 11-19 years. Individual study data was first summarised narratively before study means were pooled to give an estimate of nutritional status in the population. Results: The results show that individual studies reported intakes of energy, fibre and a number of key micronutrients which were below recommended levels. Biological markers of iron and selenium status also showed cause for concern. Pooled analysis of individual means as a percentage of UK Dietary Reference Intakes showed intakes of vitamin D (34.8 % CI 0-83.1) to be significantly below recommendations (p=0.05). Serum selenium levels were also found to be low (61.8 μg/L, CI 39-84). Conclusions: This review has identified a number of areas where the nutritional status of pregnant adolescents is sub-optimal, which may have implications for the health of adolescent mothers and their babies. It was not however possible to examine the impact of supplement use or socio-demographic characteristics which limits the interpretation these results. Further work is needed to establish the characteristics of those most at risk within this population, how this differs from adult pregnant women and the role of supplementation in achieving adequate nutrition

Cysteine oxidation triggers amyloid fibril formation of the tumor suppressor p16INK4A

The tumor suppressor p16INK4A induces cell cycle arrest and senescence in response to oncogenic transformation and is therefore frequently lost in cancer. p16INK4A is also known to accumulate under conditions of oxidative stress. Thus, we hypothesized it could potentially be regulated by reversible oxidation of cysteines (redox signaling). Here we report that oxidation of the single cysteine in p16INK4A in human cells occurs under relatively mild oxidizing conditions and leads to disulfide-dependent dimerization. p16INK4A is an all α-helical protein, but we find that upon cysteine-dependent dimerization, p16INK4A undergoes a dramatic structural rearrangement and forms aggregates that have the typical features of amyloid fibrils, including binding of diagnostic dyes, presence of cross-β sheet structure, and typical dimensions found in electron microscopy. p16INK4A amyloid formation abolishes its function as a Cyclin Dependent Kinase 4/6 inhibitor. Collectively, these observations mechanistically link the cellular redox state to the inactivation of p16INK4A through the formation of amyloid fibrils

Gecko Adhesion as a Model System for Integrative Biology, Interdisciplinary Science, and Bioinspired Engineering

Geckos possess a superlative climbing adaptation in the form of hierarchical arrays of adhesive nanostructures on the underside of their toes. These structures permit rapid, robust, and reliable adhesion to nearly any substrate during full-speed locomotion. We review the fundamental principles and properties of this system, describe its ecological and evolutionary aspects, and offer our assessment of the field alongside suggestions for future research in this direction