Why Five Fingers? Evolutionary Constraints on Digit Numbers

Evolutionary changes in the number of digits and other limb elements appear to be severely constrained, probably as a result of a low level of modularity during limb development. Reduced limb structures typically develop through a process of construction followed by destruction and amniotes have evolved many digit-like structures rather than actual extra digits. In amniotes, limb development occurs during the crucial phylotypic stage, when many inductive interactions are occurring throughout the body. As a result, changes in limb development usually engender changes in other body parts. Thus, mutations that change the number of limb bones are expected to have many pleiotropic effects, which severely reduces the chance of such mutations being successful. In amphibians with aquatic larvae, limb development occurs after the phylotypic stage and limb development is decoupled from the interactivity of the phylotypic stage. The constraint of pleiotropic effects is, therefore, expected to be weaker. This expectation agrees with the larger variability in the number of hand and foot structures in amphibians, with frogs even occasionally possessing six toes. These facts once again emphasize the importance of pleiotropic effects as constraints to evolutionary change, including their role in the conservation of body plans

Predictive model for functional consequences of oral cavity tumour

The prediction of functional consequences after treatment of large oral cavity tumours is mainly based on the size and location of the tumour. However, patient specific factors play an important role in the functional outcome, making the current predictions unreliable and subjective. An objective prediction is necessary for better patient oriented care, where the choice between surgery or chemo- and radiotherapy could be made according to more reliable measures. In this project, work is being performed to create a tool to obtain this objective prediction. The aim is to develop a virtual biomechanical patient-specific model of the oral cavity for virtual surgery. By adjusting the model, so as to mimic the performed surgery, an accurate preoperative assessment of the postoperative functional consequences can be made for each individual patient

Predicting 3D lip shapes using facial surface EMG

Aim The aim of this study is to prove that facial surface electromyography (sEMG) conveys sufficient information to predict 3D lip shapes. High sEMG predictive accuracy implies we could train a neural control model for activation of biomechanical models by simultaneously recording sEMG signals and their associated motions. Materials and methods With a stereo camera set-up, we recorded 3D lip shapes and simultaneously performed sEMG measurements of the facial muscles, applying principal component analysis (PCA) and a modified general regression neural network (GRNN) to link the sEMG measurements to 3D lip shapes. To test reproducibility, we conducted our experiment on five volunteers, evaluating several sEMG features and window lengths in unipolar and bipolar configurations in search of the optimal settings for facial sEMG. Conclusions The errors of the two methods were comparable. We managed to predict 3D lip shapes with a mean accuracy of 2.76 mm when using the PCA method and 2.78 mm when using modified GRNN. Whereas performance improved with shorter window lengths, feature type and configuration had little influence

Development and Evolutionary Constraints in Animals

We review the evolutionary importance of developmental mechanisms in constraining evolutionary changes in animals—in other words, developmental constraints. We focus on hard constraints that can act on macroevolutionary timescales. In particular, we discuss the causes and evolutionary consequences of the ancient metazoan constraint that differentiated cells cannot divide and constraints against changes of phylotypic stages in vertebrates and other higher taxa. We conclude that in all cases these constraints are caused by complex and highly controlled global interactivity of development, the disturbance of which has grave consequences. Mutations that affect such global interactivity almost unavoidably have many deleterious pleiotropic effects, which will be strongly selected against and will lead to long-term evolutionary stasis. The discussed developmental constraints have pervasive consequences for evolution and critically restrict regeneration capacity and body plan evolution

The spliceosome as target for anticancer treatment

The spliceosome is a ribonucleoprotein complex involved in RNA splicing, that is, the removal of non-coding introns from precursor messenger RNA. (Alternative) Splicing events may play an essential role in tumourigenesis. The recent discovery that the spliceosome is a target for novel compounds with anticancer activity opens up new therapeutic avenues