Impacts of benzophenone-type UV filters on cladoceran Daphnia carinata

Limnology - The impacts of three commonly used benzophenone-type UV filters including benzophenone (BP), 2-hydroxy-4-methoxy-benzophenone (BP3), and 2-hydroxy-4-methoxy-benzophenone-5-sulfonicacid...     

The effect of thymectomy on the mixed leukocyte reaction and phytohemagglutinin responsiveness in the clawed toadXenopus laevis

In the clawed toadXenopus laevis, thymectomy at 7 days of age abrogates the phytohemagglutinin response of leukocytes and the mixed leukocyte reaction.A project grant from the Medical Research Council to Dr. J.D. Horton is gratefully acknowledged.     

Effects of Cortisol and Dexamethasone on Insulin Signalling Pathways in Skeletal Muscle of the Ovine Fetus during Late Gestation

Before birth, glucocorticoids retard growth, although the extent to which this is mediated by changes in insulin signalling pathways in the skeletal muscle of the fetus is unknown. The current study determined the effects of endogenous and synthetic glucocorticoid exposure on insulin signalling proteins in skeletal muscle of fetal sheep during late gestation. Experimental manipulation of fetal plasma glucocorticoid concentration was achieved by fetal cortisol infusion and maternal dexamethasone treatment. Cortisol infusion significantly increased muscle protein levels of Akt2 and phosphorylated Akt at Ser473, and decreased protein levels of phosphorylated forms of mTOR at Ser2448 and S6K at Thr389. Muscle GLUT4 protein expression was significantly higher in fetuses whose mothers were treated with dexamethasone compared to those treated with saline. There were no significant effects of glucocorticoid exposure on muscle protein abundance of IR-β, IGF-1R, PKCζ, Akt1, calpastatin or muscle glycogen content. The present study demonstrated that components of the insulin signalling pathway in skeletal muscle of the ovine fetus are influenced differentially by naturally occurring and synthetic glucocorticoids. These findings may provide a mechanism by which elevated concentrations of endogenous glucocorticoids retard fetal growth.     

Epidermal restriction confers robustness to organ shapes

The shape of comparable tissues and organs is consistent among individuals of a given species, but how this consistency or robustness is achieved remains an open question. The interaction between morphogenetic factors determines organ formation and subsequent shaping, which is ultimately a mechanical process. Using a computational approach, we show that the epidermal layer is essential for the robustness of organ geometry control. Specifically, proper epidermal restriction allows organ asymmetry maintenance, and the tensile epidermal layer is sufficient to suppress local variability in growth, leading to shape robustness. The model explains the enhanced organ shape variations in epidermal mutant plants. In addition, differences in the patterns of epidermal restriction may underlie the initial establishment of organ asymmetry. Our results show that epidermal restriction can answer the longstanding question of how cellular growth noise is averaged to produce precise organ shapes, and the findings also shed light on organ asymmetry establishment.