Perception during double-step saccades

How the visual system achieves perceptual stability across saccadic eye movements is a long-standing question in neuroscience. It has been proposed that an efference copy informs vision about upcoming saccades, and this might lead to shifting spatial coordinates and suppressing image motion. Here we ask whether these two aspects of visual stability are interdependent or may be dissociated under special conditions. We study a memory-guided double-step saccade task, where two saccades are executed in quick succession. Previous studies have led to the hypothesis that in this paradigm the two saccades are planned in parallel, with a single efference copy signal generated at the start of the double-step sequence, i.e. before the first saccade. In line with this hypothesis, we find that visual stability is impaired during the second saccade, which is consistent with (accurate) efference copy information being unavailable during the second saccade. However, we find that saccadic suppression is normal during the second saccade. Thus, the second saccade of a double-step sequence instantiates a dissociation between visual stability and saccadic suppression: stability is impaired even though suppression is strong

Lazo de control optoacoplado para fuente conmutada

ResumenSe presenta un ejemplo de lazo de realimentación optoacoplado para controlar la tensión de una fuente conmutada, conservando eléctricamente aisladas las tensiones primarias y de salida. La elevada ganancia del lazo permite compensar la no linealidad del optoacoplador empleado y compensar la deriva de sus características, debidas a variaciones de temperatura y envejecimiento. La compensación se proyecta y calcula considerando al sistema lineal, en virtud de adoptar una frecuencia de conmutación mayor, en más de un orden de magnitud, que la de la respuesta dinámica pretendida

Fast saccadic eye-movements in humans suggest that numerosity perception is automatic and direct

Fast saccades are rapid automatic oculomotor responses to salient and ecologically important visual stimuli such as animals and faces. Discriminating the number of friends, foe, or prey may also have an evolutionary advantage. In this study, participants were asked to saccade rapidly towards the more numerous of two arrays. Participants could discriminate numerosities with high accuracy and great speed, as fast as 190 ms. Intermediate numerosities were more likely to elicit fast saccades than very low or very high numerosities. Reaction-times for vocal responses (collected in a separate experiment) were slower, did not depend on numerical range, and correlated only with the slow not the fast saccades, pointing to different systems. The short saccadic reaction-times we observe are surprising given that discrimination using numerosity estimation is thought to require a relatively complex neural circuit, with several relays of information through the parietal and prefrontal cortex. Our results suggest that fast numerosity-driven saccades may be generated on a single feed-forward pass of information recruiting a primitive system that cuts through the cortical hierarchy and rapidly transforms the numerosity information into a saccade command

Antibacterial Properties of D-Amino Acid Oxidase: Impact on the Food Industry

Food quality is also related to safety and prevention of spoilage. Biological antimicrobial agents represent suitable alternatives to clinical preservatives in food industry to increase both safety and stability of aliments. Here, we focused on the enzyme D-amino acid oxidase (DAAO) from the yeast Rhodotorula gracilis, a well-studied protein for biotechnological use based on its stability, high activity, and easy recombinant production. DAAO catalyzes the O-2-dependent oxidative deamination of D-enantiomer of amino acids generating alpha -keto acids, ammonia, and hydrogen peroxide. DAAO shows antibacterial activity on both Gram-positive and Gram-negative bacteria in the presence of D-alanine when tested on plates and reduced by half their growth when tested on liquid cultures. Control experiments performed with alternative amino acid-specific flavoenzymes (able or not to generate H2O2 acting on amino acids), a DAAO inactive variant, catalase (H2O2 scavenger), and L-amino acids instead of D-alanine identified H2O2 as the antibacterial agent. DAAO showed a good ability to decrease the bacterial growth on various food stuffs: e.g., 10-fold less colonies were formed on grated cheese incubated for 16 h at 37 degrees C when a tiny amount (0.01 mg corresponding to 1.2 units) of DAAO was added. No exogenous D-amino acids were added since DAAO used the ones naturally occurring or the ones generated during ripening. Notably, simultaneously to H2O2 generation, DAAO also acts as O-2-scavenger thus further hampering food deterioration

Some tardigrades from Central Africa with the description of two new species: Macrobiotus ragonesei and M. priviterae (Eutardigrada Macrobiotidae)

Ten species of tardigrades are reported from Central Africa. Isohypsibius arbiter Binda 1980 is new for Africa; two species, Macrobiotus ragonesei and Macrobiotus priviterae are new to science. Macrobiotus ragonesei has two macroplacoids and microplacoid, and areolated eggs with conical processes sculptured in the basal portion and unsculptured in the terminal portion. Macrobiotus priviterae is similar to M. richtersi Murray 1911, M. peteri Pilato et al. 1989, and M. chieregoi Maucci et al. 1980 but differs from them by having eyes, and in the claw and egg characters; it is also similar to M. vanescens Pilato et al. 1991 and to M. danielae Pilato et al. 2001 but differs from them in claw and egg characters. The egg of Minibiotus africanus Binda & Pilato 1995, unknown so far, is described

Asymmetric Hydrogenation of 1-aryl substituted-3,4-Dihydroisoquinolines with Iridium Catalysts Bearing Different Phosphorus-Based Ligands

Starting from the chiral 5,6,7,8-tetrahydroquinolin-8-ol core, a series of amino-phosphorusbased ligands was realized. The so-obtained amino-phosphine ligand (L1), amino-phosphinite (L2) and amino-phosphite (L3) were evaluated in iridium complexes together with the heterobiaryl diphosphines tetraMe-BITIOP (L4), Diophep (L5) and L6 and L7 ligands, characterized by mixed chirality. Their catalytic performance in the asymmetric hydrogenation (AH) of the model substrate 6,7-dimethoxy-1-phenyl-3,4-dihydroisoquinoline 1a led us to identify Ir-L4 and Ir-L5 catalysts as the most eective. The application of these catalytic systems to a library of dierently substituted 1-aryl-3,4-dihydroisoquinolines aorded the corresponding products with variable enantioselective levels. The 4-nitrophenyl derivative 3b was obtained in a complete conversion and with an excellent 94% e.e. using Ir-L4, and a good 76% e.e. was achieved in the reduction of 2-nitrophenyl derivative 6a using Ir-L5

Diagnosing congenital Cytomegalovirus infection: Don't get rid of dried blood spots

Background: Congenital Cytomegalovirus (cCMV) is a serious global public health issue that can cause irreversible fetal and neonatal congenital defects in symptomatic or asymptomatic newborns at birth. In absence of universal cCMV screening, the retrospective diagnosis of cCMV infection in children is only possible by examining Dried Blood Spot (DBS) samples routinely collected at birth and stored for different time spans depending on the newborn screening regulations in force in different countries. In this article, we summarize the arguments in favor of long-term DBS sample storage for detecting cCMV infection. Main text: CMV infection is the most common cause of congenital infection resulting in severe defects and anomalies that can be apparent at birth or develop in early childhood. Sensorineural hearing loss is the most frequent consequence of cCMV infection and may have a late onset and progress in the first years of life. The virological diagnosis of cCMV is essential for clinical research and public health practices. In fact, in order to assess the natural history of CMV infection and distinguish between congenital or acquired infection, children should be diagnosed early by analyzing biological samples collected in the first weeks of life (3 weeks by using viral culture and 2 weeks by molecular assays), which, unfortunately, are not always available for asymptomatic or mildly symptomatic children. It now seems possible to overcome this problem since the CMV-DNA present in the blood of congenitally infected newborns can be easily retrieved from the DBS samples on the Guthrie cards routinely collected and stored within 3 days from birth in the neonatal screening program for genetic and congenital diseases. Early collection and long-term storage are inexpensive methods for long-term bio-banking and are the key points of DBS testing for the detection of cCMV. Conclusion: DBS sampling is a reliable and inexpensive method for long-term bio-banking, which enables to diagnose known infectious diseases - including cCMV - as well as diseases not jet recognized, therefore their storage sites and long-term storage conditions and durations should be the subject of political decision-making

Non-spatial skills differ in the front and rear peri-personal space

In measuring behavioural and pupillary responses to auditory oddball stimuli delivered in the front and rear peri-personal space, we find that pupils dilate in response to rare stimuli, both target and distracters. Dilation in response to targets is stronger than the response to distracters, implying a task relevance effect on pupil responses. Crucially, pupil dilation in response to targets is also selectively modulated by the location of sound sources: stronger in the front than in the rear peri-personal space, in spite of matching behavioural performance. This supports the concept that even non-spatial skills, such as the ability to alert in response to behaviourally relevant events, are differentially engaged across subregions of the peri-personal space

Crystal structure of human monoamine oxidase B, a drug target enzyme monotopically inserted into the mitochondrial outer membrane

AbstractMonoamine oxidase B (MAO B) is an outer mitochondrial membrane protein that oxidizes arylalkylamine neurotransmitters and has been a valuable drug target for many neurological disorders. The 1.7 Å resolution structure of human MAO B shows the enzyme is dimeric with a C-terminal transmembrane helix protruding from each monomer and anchoring the protein to the membrane. This helix departs perpendicularly from the base of the structure in a different way with respect to other monotopic membrane proteins. Several apolar loops exposed on the protein surface are located in proximity of the C-terminal helix, providing additional membrane-binding interactions. One of these loops (residues 99–112) also functions in opening and closing the MAO B active site cavity, which suggests that the membrane may have a role in controlling substrate binding