Tipping points in the dynamics of speciation.

Speciation can be gradual or sudden and involve few or many genetic changes. Inferring the processes generating such patterns is difficult, and may require consideration of emergent and non-linear properties of speciation, such as when small changes at tipping points have large effects on differentiation. Tipping points involve positive feedback and indirect selection stemming from associations between genomic regions, bi-stability due to effects of initial conditions and evolutionary history, and dependence on modularity of system components. These features are associated with sudden 'regime shifts' in other cellular, ecological, and societal systems. Thus, tools used to understand other complex systems could be fruitfully applied in speciation research

Erythrocyte Transketolase Activity, Markers of Cardiac Dysfunction and the Diagnosis of Infantile Beriberi

Infantile beriberi, or clinical thiamin (vitamin B1) deficiency in infants, is a forgotten disease in Asia, where ∼100 years ago it was a major public health problem. Children aged ∼2–3 months present in cardiac failure but usually rapidly improve if given thiamin injections. It remains relatively common in Vientiane, Lao PDR (Laos) probably because of prolonged intra- and post-partum maternal food avoidance behaviours. There has been very little recent research on the best diagnostic techniques. We conducted a case control study of 47 infants with beriberi and age-matched afebrile and febrile controls in Vientiane. The conventional measures of thiamin deficiency, basal and activated erythrocyte transketolase activities (ETK) and activation (α) coefficients, were assayed along with three markers of cardiac dysfunction - plasma brain natriuretic peptide, N-terminal pro-brain natriuretic peptide, and troponin T. Basal ETK was a better biochemical marker of infantile beriberi than the activation coefficient. Raised plasma troponin T may be a useful indicator of infantile beriberi in babies at risk and in the absence of other evident causes

Peptide Fragments of Odin-Sam1: Conformational Analysis and Interaction Studies with EphA2-Sam

Odin is a protein belonging to the ANKS family, and has two tandem Sam domains. The first, Odin-Sam1, binds to the Sam domain of the EphA2 receptor (EphA2-Sam); this interaction could be crucial for the regulation of receptor endocytosis and might have an impact on cancer. Odin-Sam1 associates with EphA2-Sam by adopting a "mid-loop/end-helix" model. In this study three peptide sequences, encompassing the mid-loop interacting portion of Odin-Sam1 and its C-terminal α5 helix, were designed. Their conformational properties were analyzed by CD and NMR. In addition, their abilities to interact with EphA2-Sam were investigated by SPR studies. The peptides adopt a predominantly disordered state in aqueous buffer, but a higher helical content is evident in the presence of the cosolvent trifluoroethanol. Dissociation constants towards EphA2-Sam were in the high micromolar range. The structural findings suggest further routes for the design of potential anti-cancer therapeutics as inhibitors of EphA2-Sam heterotypic interactions