Stimuli-responsive polymer nanocomposites inspired by the sea cucumber dermis

Sea cucumbers, like other echinoderms, have the ability to rapidly and reversibly alter the stiffness of their inner dermis. It has been proposed that the modulus of this tissue is controlled by regulating the interactions among collagen fibrils, which reinforce a low-modulus matrix. We report on a family of polymer nanocomposites, which mimic this architecture and display similar chemoresponsive mechanic adaptability. Materials based on a rubbery host polymer and rigid cellulose nanofibers exhibit a reversible reduction by a factor of 40 of the tensile modulus, for example, from 800 to 20 megapascals (MPa), upon exposure to a chemical regulator that mediates nanofiber interactions. Using a host polymer with a thermal transition in the regime of interest, we demonstrated even larger modulus changes (4200 to 1.6 MPa) upon exposure to emulated physiological conditions.     

Expression and function of junctional adhesion molecule-C in myelinated peripheral nerves

JAM-C is an adhesion molecule that is expressed on cells within the vascular compartment and epithelial cells and, to date, has been largely studied in the context of inflammatory events. Using immunolabeling procedures in conjunction with confocal and electron microscopy, we show here that JAM-C is also expressed in peripheral nerves and that this expression is localized to Schwann cells at junctions between adjoining myelin end loops. Sciatic nerves from JAM-C-deficient [having the JAM-C gene knocked out (KO)] mice exhibited loss of integrity of the myelin sheath and defective nerve conduction as indicated by morphological and electrophysiological studies, respectively. In addition, behavioral tests showed motor abnormalities in the KO animals. JAM-C was also expressed in human sural nerves with an expression profile similar to that seen in mice. These results demonstrate that JAM-C is a component of the autotypic junctional attachments of Schwann cells and plays an important role in maintaining the integrity and function of myelinated peripheral nerves.     

Broadband modulation of light by using an electro-optic polymer

A major challenge to increasing bandwidth in optical telecommunications is to encode electronic signals onto a lightwave carrier by modulating the light up to very fast rates. Polymer electro-optic materials have the necessary properties to function in photonic devices beyond the 40-GHz bandwidth currently available. An appropriate choice of polymers is shown to effectively eliminate the factors contributing to an optical modulator's decay in the high-frequency response. The resulting device modulates light with a bandwidth of 150 to 200 GHz and produces detectable modulation signal at 1.6 THz. These rates are faster than anticipated bandwidth requirements for the foreseeable future.     

Comparative anatomic and morphometric examination of the interosseous muscle,sesamoid ligaments and flexor tendons of the fetlock in South American camelids

This study presents a comparative morphological and morphometrical examination of the interosseous muscle (IOM), digital flexor tendons and associated structures of all four species of South American Camelids (SACs): Lama (Lama glama), alpaca (Vicugna pacos), guanaco (Lama guanicoe) and vicuna (Vicugna vicugna). Our findings show that the lamoid interosseous muscle and digital flexor tendons are very similar between species and differences, which have been reported previously, are possibly due to diverging examiner interpretation. Lumbricalis muscles were mostly found as single muscles in this study. The definition of the terminal and dorsal branches of the interosseous muscle is critically revised. The analysis of morphometric data indicates that the size of the individual has a substantial influence on the cross-sectional area (CSA) of the examined structures. Metacarpal/metatarsal bone width is a main predictor of CSA, while the factor species only shows significance in specific sample points. For lama and alpaca, no differences in CSA in relation to species as factor were found. The IOM shows the largest CSAs of the three examined structures in all species, which implies an important load-bearing function. Considerable individual variation remains unexplained by the mentioned factors. This lowers the prospect of CSA reaching diagnostic importance in SAC fetlock pathology.     

Areal activities and stratification of hydrolytic enzymes involved in the biochemical cycles of carbon, nitrogen, sulphur and phosphorus in podsolized boreal forest soils

A novel approach allowing on-site high throughput enzyme activity measurements by fluorogenic model substrates was applied to study the functioning of enzymes involved in biochemical cycling of nutrients in boreal forest soil ecosystems. The examined enzymes comprised α-glucosidase, β-glucosidase, β-xylosidase, β-cellobiosidase, N-acetyl-glucosamidase, acetate-esterase, butyrate-esterase, phosphomonoesterase, sulphatase and aminopeptidase, whereby spatial and seasonal variation of their activity was investigated over nine seasons in 2 years. The studied sites of boreal podzolized soil of Pinus sylvestris and Picea abies forest were located in central Finland. Activity of all enzymes except sulphatase was highest in the humus layer in all seasons. Maximum sulphatase activity was located below the humus layer in the soil column. Annual activities of acetate-esterase, butyrate-esterase, β-glucosidase and phosphomonosterase calculated to in situ temperature during the year were 480-700, 690-950, 110-190 and 110-200 mol m⁻² year⁻¹, respectively. They were up to 100 fold higher than the other six measured activities. The overall turnover capacity of the enzymes was >1000 mol of ester linked carbon, >700 mols carbon from different carbohydrates, 100-200 mol of ester linked phosphate, 10-40 mol of ester linked sulphate m⁻² year⁻¹. Winter time (November-April) contributed from 7 to 32% to the annual turnover capacity indicating important enzyme activities also during a cold period of the year. Clear-cutting of the tree stand did not adversely affect enzyme activities related to the cycling of carbon, nitrogen, sulphur and phosphorus during the year. The pH optimum for hemicellulose and cellulose hydrolysing enzymes was pH 3-4 and the pH optimum of phosphomonoesterase, sulphatase, aminopeptidase and N-acetyl-glucosamidase was 4-5. This shows that the hydrolytic activities were adapted to the acid pH-values of the soils. The soil hydrolytic potential was many fold higher as compared to the actual amount of litter it received in the P. sylvestris and P. abies forests.     

Solanum scabrum—a potential source of a coloring plant extract

The objective of this study was to examine the potential of Solanum scabrum to provide a colorant for food. We conducted a field trial with eight accessions from four different sources and recorded both morphological variability and fruit yield differences between accessions. Further, anthocyanin and glucoalkaloid concentrations were determined. The accessions could be assigned to two distinct groups: a leafy vegetable type with toxic fruits used in Africa and a berry type with edible fruits known as Garden Huckleberry in North America, but both types had edible leaves with low glucoalkaloid concentrations. The leafy vegetable type set not much fruit. In contrast, the berry type yielded on average 800–900 g berries per plant with remarkable high anthocyanin concentrations of 8.1–13.9 g kg⁻¹ fresh weight, calculated as petunidin 3-p-(coumaryl-runtinoside)-5-glucoside. Thus, S. scabrum can serve as a source for natural anthocyanin pigments. In particular, two accessions with a high fruit yield were promising candidates as a berry crop. One had the best anthocyanin concentration of the examined material and the other one had a low percentage of unripe berries as a further advantage.