Activation of Sperm EGFR by Light Irradiation is Mediated by Reactive Oxygen Species

To acquire fertilization competence, spermatozoa must undergo several biochemical and motility changes in the female reproductive tract, collectively called capacitation. Actin polymerization and the development of hyperactivated motility (HAM) are part of the capacitation process. In a recent study, we showed that irradiation of human sperm with visible light stimulates HAM through a mechanism involving reactive‐oxygen‐species (ROS), Ca²⁺ influx, protein kinases A (PKA), and sarcoma protein kinase (Src). Here, we showed that this effect of light on HAM is mediated by ROS‐dependent activation of the epidermal growth factor receptor (EGFR). Interestingly, ROS‐mediated HAM even when the EGFR was activated by EGF, the physiological ligand of EGFR. Light irradiation stimulated ROS‐dependent actin polymerization, and this effect was abrogated by PBP10, a peptide which activates the actin‐severing protein, gelsolin, and causes actin‐depolymerization in human sperm. Light‐stimulated tyrosine phosphorylation of Src‐dependent gelsolin, resulting in enhanced HAM. Thus, light irradiation stimulates HAM through a mechanism involving Src‐mediated actin polymerization. Light‐stimulated HAM and in vitro‐fertilization (IVF) rate in mouse sperm, and these effects were mediated by ROS and EGFR. In conclusion, we show here that irradiation of sperm with visible light, enhances their fertilization capacity via a mechanism requiring ROS, EGFR and HAM.     

Range Minima Queries with Respect to a Random Permutation,and Approximate Range Counting

In approximate halfspace range counting, one is given a set P of n points in ℝ ^d , and an ε>0, and the goal is to preprocess P into a data structure which can answer efficiently queries of the form: Given a halfspace h, compute an estimate N such that (1−ε)|P∩h|≤N≤(1+ε)|P∩h|.     

Generator Coalgebras are not Necessarily Quasi-coFrobenius

We study the problem of whether a coalgebra that generates its category of left (right) comodules is left (right) quasi-coFrobenius or not. We prove it does not hold in general, by giving a method of constructing counterexamples. This gives a negative answer to a question stated in Nastasescu et al. (Algebr Represent Theory 11(2):179–190, 2008). We also prove it is true for monomial pointed coalgebras and we characterize the quivers Q such that \mathbbkQ\mathbb{k}Q admits a monomial subcoalgebra that is left (right) quasi-coFrobenius.     

Observation of B(s)0-->K+ K- and measurements of branching fractions of charmless two-body decays of B0 and B(s)0 mesons in pp collisions at square root of s = 1.96 TeV

We search for decays of the type B(s)0-->h+ h'- (where h,h' = K or pi) in 180 pb(-1) of pp collisions collected at the Tevatron by the upgraded Collider Detector at Fermilab. We report the first observation of the new mode B(s)0-->K+ K- with a yield of 236+/-32 events, corresponding to (fs/fd) x B(B(s)0-->K+ K-)/B(B0-->K+ pi-) = 0.46+/-0.08stat+/-0.07syst, where fs/fd is the ratio of production fractions of B(s)0 and B0. We find results in agreement with world averages for the B0 modes, and set the following new limits at 90% C.L.: B(B(s)0-->K- pi+) < 5.6 x 10(-6) and B(B(s)0-->pi+ pi-) < 1.7 x 10(-6).