Eye-hand coordination during a double-step task: evidence for a common stochastic accumulator

Many studies of reaching and pointing have shown significant spatial and temporal correlations between eye and hand movements. Nevertheless, it remains unclear whether these correlations are incidental, arising from common inputs (independent model); whether these correlations represent an interaction between otherwise independent eye and hand systems (interactive model); or whether these correlations arise from a single dedicated eye-hand system (common command model). Subjects were instructed to redirect gaze and pointing movements in a double-step task in an attempt to decouple eye-hand movements and causally distinguish between the three architectures. We used a drift-diffusion framework in the context of a race model, which has been previously used to explain redirect behavior for eye and hand movements separately, to predict the pattern of eye-hand decoupling. We found that the common command architecture could best explain the observed frequency of different eye and hand response patterns to the target step. A common stochastic accumulator for eye-hand coordination also predicts comparable variances, despite significant difference in the means of the eye and hand reaction time (RT) distributions, which we tested. Consistent with this prediction, we observed that the variances of the eye and hand RTs were similar, despite much larger hand RTs (similar to 90 ms). Moreover, changes in mean eye RTs, which also increased eye RT variance, produced a similar increase in mean and variance of the associated hand RT. Taken together, these data suggest that a dedicated circuit underlies coordinated eye-hand planning.

Ferromagnetism and the effect of free charge carriers on electric polarization in the double perovskite Y2NiMnO6

The double perovskite Y2NiMnO6 displays ferromagnetic transition at T-c approximate to 81 K. The ferromagnetic order at low temperature is confirmed by the saturation value of magnetization (Ms) and also validated by the refined ordered magnetic moment values extracted from neutron powder diffraction data at 10 K. This way, the dominant Mn4+ and Ni2+ cationic ordering is confirmed. The cation-ordered P2(1)/n nuclear structure is revealed by neutron powder diffraction studies at 300 and 10 K. Analysis of the frequency-dependent dielectric constant and equivalent circuit analysis of impedance data take into account the bulk contribution to the total dielectric constant. This reveals an anomaly which coincides with the ferromagnetic transition temperature (T-c). Pyrocurrent measurements register a current flow with onset near T-c and a peak at 57 K that shifts with temperature ramp rate. The extrinsic nature of the observed pyrocurrent is established by employing a special protocol measurement. It is realized that the origin is due to reorientation of electric dipoles created by the free charge carriers and not by spontaneous electric polarization at variance with recently reported magnetism-driven ferroelectricity in this material.

Microhomology-mediated end joining is the principal mediator of double-strand break repair during mitochondrial DNA lesions

Mitochondrial DNA (mtDNA) deletions are associated with various mitochondrial disorders. The deletions identified in humans are flanked by short, directly repeated mitochondrial DNA sequences; however, the mechanism of such DNA rearrangements has yet to be elucidated. In contrast to nuclear DNA (nDNA), mtDNA is more exposed to oxidative damage, which may result in double-strand breaks (DSBs). Although DSB repair in nDNA is well studied, repair mechanisms in mitochondria are not characterized. In the present study, we investigate the mechanisms of DSB repair in mitochondria using in vitro and ex vivo assays. Whereas classical NHEJ (C-NHEJ) is undetectable, microhomology-mediated alternative NHEJ efficiently repairs DSBs in mitochondria. Of interest, robust microhomology-mediated end joining (MMEJ) was observed with DNA substrates bearing 5-, 8-, 10-, 13-, 16-, 19-, and 22-nt microhomology. Furthermore, MMEJ efficiency was enhanced with an increase in the length of homology. Western blotting, immunoprecipitation, and protein inhibition assays suggest the involvement of CtIP, FEN1, MRE11, and PARP1 in mitochondrial MMEJ. Knock-down studies, in conjunction with other experiments, demonstrated that DNA ligase III, but not ligase IV or ligase I, is primarily responsible for the final sealing of DSBs during mitochondrial MMEJ. These observations highlight the central role of MMEJ in maintenance of mammalian mitochondrial genome integrity and is likely relevant for deletions observed in many human mitochondrial disorders.

Facile synthesis of Graphene Oxide/Double-stranded DNA composite liquid crystals and Hydrogels

Investigation of the interactions between graphene oxide (GO) and biomolecules is very crucial for the development of biomedical applications based on GO. This study reports the first observation of the spontaneous formation of self-assembled liquid crystals and three-dimensional hydrogels of graphene oxide with double-stranded DNA by simple mixing in an aqueous buffer media without unwinding double-stranded DNA to single-stranded DNA. The GO/dsDNA hydrogels have shown controlled porosity by changing the concentration of the components. The strong binding between dsDNA and graphene is proved by Raman spectroscopy.