Cytosolic ferritin and lipid-associated ferritin are metabolically different in guinea-pig livers.

1. Using a human hepatoma (Hep G2) cell line that continually synthesizes 3 beta-hydroxy-5-cholenoic acid, lithocholic acid, chenodeoxycholic acid and cholic acid we have determined the metabolism and biological effects of 26-hydroxycholesterol and 7 alpha-hydroxycholesterol. 2. Addition of 26-hydroxycholesterol to the medium (6 microM) downregulated cholesterol and chenodeoxycholic acid synthesis. 3. The predominant metabolite of 26-hydroxycholesterol was 3 beta-hydroxy-5-cholenoic acid. 4. Cholesterol synthesis was not affected by the addition of 7 alpha-hydroxycholesterol (6 and 12 microM). The predominant metabolite of 7 alpha-hydroxycholesterol was chenodeoxycholic acid. 5. In Hep G2 cells 7 alpha-hydroxylation of 26-hydroxycholesterol is not well expressed.     

FeS2‐Imbedded Mixed Conducting Matrix as a Solid Battery Cathode

A new concept of pairing an active material and a mixed conductor is explored as a solid‐state battery electrode. By imbedding nano‐FeS₂ domains into an amorphous LiTiS₂ matrix, a hybrid power‐energy system is achieved while additionally improving upon many common solid electrode design flaws. High‐resolution transmission electron microscopy is used to probe the active material/mixed conductor interface over the course of cycling. Arguably the most beneficial development is enhancement of charge transfer, manifesting in a significantly increased exchange current as captured in a Tafel analysis. By developing a solution to active material isolation and creating a more homogenous electrode design, cycling at a high rate of C/2 for 500 cycles is obtained. Additionally, the electrode can recover full capacity simply by reducing system rate. Capacity recovery implicates a lack of active material isolation, a common problem in solid‐state batteries.     

An Exotic Tree Alters Decomposition and Nutrient Cycling in A Hawaiian Montane Forest

We evaluated the effects of the exotic tree Fraxinus uhdei on decomposition dynamics and nutrient turnover in a montane Hawaiian rainforest. We used reciprocal transplants of litterbags between forests dominated by Fraxinus and by the native Metrosideros polymorpha to distinguish between endogenous (litter quality) and exogenous (for example, microclimate, nutrient availability, microbial and invertebrate communities) effects of Fraxinus on mass loss and nutrient dynamics of decomposing litter. Fraxinus produced greater quantities of litter that was thinner, had higher N and P concentrations, and lower concentrations of lignin and soluble polyphenols. Microbes decomposing Fraxinus litter produced fewer enzymes involved in N and P acquisition and more of those involved in cellulose degradation. Differences in litter quality and microbial activity resulted in a strong effect of litter type on rates of mass loss, whereby Fraxinus litter decomposed and released nutrients at nearly twice the rate of Metrosideros litter (k=0.82 versus 0.48), regardless of site of decomposition. Although site of decomposition had no effect on rates of litter mass loss, Fraxinus litter decomposed under a Fraxinus canopy mineralized approximately 20% less P after one year than Fraxinus litter decomposed under a Metrosideros canopy. Furthermore, Fraxinus litter decomposed under a Fraxinus canopy immobilized greater amounts of N and P in the early stages of decay, suggesting that the large amounts of N and P in Fraxinus litterfall have raised nutrient availability to decomposers in the forest floor. Greater immobilization of N and P under a Fraxinus canopy may act as a governor on rates of nutrient cycling, limiting the degree to which Fraxinus invasion accelerates N and P cycling in this system.     

The Caenorhabditis elegans nonmuscle myosin genes nmy-1 and nmy-2 function as redundant components of the let-502/Rho-binding kinase and mel-11/myosin phosphatase pathway during embryonic morphogenesis

Rho-binding kinase and the myosin phosphatase targeting subunit regulate nonmuscle contractile events in higher eukaryotes. Genetic evidence indicates that the C. elegans homologs regulate embryonic morphogenesis by controlling the actin-mediated epidermal cell shape changes that transform the spherical embryo into a long, thin worm. LET-502/Rho-binding kinase triggers elongation while MEL-11/myosin phosphatase targeting subunit inhibits this contractile event. We describe mutations in the nonmuscle myosin heavy chain gene nmy-1 that were isolated as suppressors of the mel-11 hypercontraction phenotype. However, a nmy-1 null allele displays elongation defects less severe than mutations in let-502 or in the single nonmuscle myosin light chain gene mlc-4. This results because nmy-1 is partially redundant with another nonmuscle myosin heavy chain, nmy-2, which was previously known only for its role in anterior/posterior polarity and cytokinesis in the early embryo. At the onset of elongation, NMY-1 forms filamentous-like structures similar to actin, and LET-502 is interspersed with these structures, where it may trigger contraction. MEL-11, which inhibits elongation, is initially cytoplasmic. In response to LET-502 activity, MEL-11 becomes sequestered away from the contractile apparatus, to the plasma membrane, when elongation commences. Upon completion of morphogenesis, MEL-11 again appears in the cytoplasm where it may halt actin/myosin contraction.     

Seasonal Differences in Extinction and Colonization Drive Occupancy Dynamics of an Imperilled Amphibian

A detailed understanding of the population dynamics of many amphibian species is lacking despite concerns about declining amphibian biodiversity and abundance. This paper explores temporal patterns of occupancy and underlying extinction and colonization dynamics in a regionally imperiled amphibian species, the Northern leopard frog (Lithobates pipiens) in Alberta. Our study contributes to elucidating regional occupancy dynamics at northern latitudes, where climate extremes likely have a profound effect on seasonal occupancy. The primary advantage of our study is its wide geographic scale (60,000 km²) and the use of repeat visual surveys each spring and summer from 2009–2013. We find that occupancy varied more dramatically between seasons than years, with low spring and higher summer occupancy. Between spring and summer, colonization was high and extinction low; inversely, colonization was low and extinction high over the winter. The dynamics of extinction and colonization are complex, making conservation management challenging. Our results reveal that Northern leopard frog occupancy was constant over the last five years and thus there is no evidence of decline or recovery within our study area. Changes to equilibrium occupancy are most sensitive to increasing colonization in the spring or declining extinction in the summer. Therefore, conservation and management efforts should target actions that are likely to increase spring colonization; this could be achieved through translocations or improving the quality or access to breeding habitat. Because summer occupancy is already high, it may be difficult to improve further. Nevertheless, summer extinction could be reduced by predator control, increasing water quality or hydroperiod of wetlands, or increasing the quality or quantity of summer habitat.     

Functional CD169 on Macrophages Mediates Interaction with Dendritic Cells for CD8+ T Cell Cross-Priming

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Small Intestine Microbiota Regulate Host Digestive and Absorptive Adaptive Responses to Dietary Lipids

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