Synthesis of the allo-analogue of trehalose

Selective benzoylation of HO-2 and HO-2′ of 4,6-O-benzylidene-α-D-glucopyranosyl 4,6-O-benzylidene-α-D-glucopyranoside with N-benzoylimidazole led to the exclusive formation of 2-O-benzoyl-4,6-O-benzylidene-α-D-glucopyranosyl 2-O-benzoyl-4,6-O-benzylidene-α-D-glucopyranoside. Oxidation of either the dibenzoate or the corresponding ditosylate with methyl sulphoxide-phosphorus pentaoxide gave the 3,3′-diulose, and subsequent reduction with borohydride gave the 3,3′diepimers having the allo-allo configuration. De-esterification and hydrolysis of the benzylidene substituents gave α-D-allopyranosyl α-D-allopyranoside.     

Feeding Motor Patterns in Anurans: Insights from Biomechanical Modeling

During feeding in anurans, the mouth opens while the tongue,which is attached to the mandible at the front of the mouth,rotates forward. Due to the relative simplicity of its anatomyand the complexity of its motion, tongue protraction in frogspresents an ideal system for exploring the neural control ofmultijoint movements. In this study, we used a forward dynamic,rigid body model with four segments and two muscles to investigateopen loop control of tongue protraction in the Australian white-lippedtree frog, Litoria caerulea. Model parameters include the massdistribution, initial position and initial angular velocityof each segment and the anatomy and physiology of each muscle.Model variables include the level of muscle activation at eachtime step and impulsive torques to open and close the mouth.The model gives X,Y coordinates of each segment and joint anglesat each time step as output. The model was tested using scaled,normalized EMG signals and impulsive joint torques to predictthe paths of the lower jaw tip and tongue tip. Predicted pathswere compared to experimentally observed paths using Pearsonproduct-moment correlation coefficients. Simulations demonstratethat the genioglossus muscles likely play a minor role, if any,in determining the trajectory of the tongue in most anurans.Most of the force for tongue protraction comes from angularmomentum transferred to the tongue by the opening jaws. In anurans,tongue protraction is dynamically stable and will occur as longas the musculoskeletal elements are in the correct initial position.     

Circamensal Rhythms in Physical Performance

The eumenorrheic menstrual cycle represents a clear inherent biological rhythm that might interact with both physical performance, and/or the physiological response to performance. The predominant hormonal fluctuations throughout the cycle are in the ovarian steroids oestrogen and progesterone. Progesterone has both a thermogenic and ventilatory effect leading to a potential increase in minute ventilation and body temperature during exercise. Oestrogen has been linked to fluctuations in blood flow and heart rate via a vasodilatory mechanism, plus potential variation in muscle strength. If these hormones do indeed influence physical performance, or the physiological response to performance, female athletes might choose to manipulate the cycle through an endogenous hormonal mechanism. Furthermore, researchers utilizing a female population must control for these fluctuations in their research design.     

Bases and spaces: resources on the web for accessing the draft human genome - II - After publication of the draft

The volume of human genome sequence and the variety of web-based tools to access it continue to grow at an impressive rate, but a working knowledge of certain key resources can be sufficient to get the most from your genome. This article provides an update to Genome Biology 2000, 1(4):reviews2001.1-2001.5.