Examining the functionality of peripheral vision: From fundamental understandings to applied sport science

In sports, it is important not only to locate gaze on the right location to utilize the high acuity of foveal vision, but also to attend to other objects in the environment without looking directly at them, accordingly, using peripheral vision. Peripheral vision becomes especially important if, for example, the processing of information from more than one location (e.g. players) is decisive in making accurate decisions. Since such decisions generally must be made under high spatio-temporal demands, costly eye-movements might be advantageously avoided by using peripheral vision for information pick-up from multiple cues. In a series of studies, we aimed to translate the demands found in sports and to investigate the functionality of peripheral vision in a well-controlled experimental paradigm, the multiple object tracking (MOT) task. MOT was implemented in a dual task, along with an additional event-detection task. The present article first presents an overview of sport-specific studies focusing on the functionality of peripheral vision and following, summarizes a series of three published MOT studies. These studies show that peripheral vision is used for simultaneous target monitoring and target-change detection and that visual and attentional demands affect gaze anchoring and change-detection rates. Results also reveal a dysfunctionality of saccades, and further suggest an event- and distance-optimized gaze-anchoring position. In the final portion of this article, we derive specific applications for future sports-specific research. Specifically, we suggest to: (a) use dual-task situations in sport-specific settings, such as monitoring multiple players in soccer and playing a pass at specific moments, (b) investigate the costs of saccades in sports situations with high spatio-temporal demands, as in martial arts, and finally, (c) manipulate attentional and visual demands. For each of these avenues of research, we sketch sports-specific experiments currently being conducted in our research group

Competition of Pyridoxal 5'-Phosphate with Ribulose 1,5-Bisphosphate and Effector Sugar Phosphates at the Reaction Centers of the Spinach Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase

The Stimulation of the carboxylase reaction by effectors of ribulose 1,5-bisphosphate carboxyl­ ase/oxygenase displays higher sensitivity towards pyridoxal 5'-phosphate inhibition than the catalytical process itself. Pyridoxal 5'-phosphate binding to the enzyme is not affected by the modulators 6-phospho-gluconate and fructose 1,6-bisphosphate at low concentrations at which these agents stimulate the carboxylation rate. At higher concentrations these sugar phosphates protect the enzyme against pyridoxal 5'-phos-phate inhibition in a similar fashion like the substrate ribulose 1,5-bisphosphate. Such protection experiments in combination with spectrophotometrical studies of pyridoxal 5'-phosphate binding demonstrate two binding states of ribulose 1,5-bisphosphate at the reaction centers of the enzyme with different requirements for Mg2+. 6-Phosphogluconate functions as protector only in the presence of Mg2+. Our results imply a competition between pyridoxal 5'-phosphate and substrate or effector sugar phosphates at the reaction centers of the spinach carboxylase. It is proposed that the pyridoxal 5'-phosphate inhibition of the stimulatory activity of these effectors originates from a modification of the regulatory sites of the enzyme caused by pyridoxal 5'-phosphate binding to the catalytical sites

Biosynthetic rivalry of o-aminophenol-carboxylic acids initiates production of hemi-actinomycins in Streptomyces antibioticus

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Actinomycins consist of two pentapeptide lactone rings attached to 2-amino-4,6-dimethyl-3-oxo-phenoxazine-1,9-dicarboxylic acid (actinocin). The actinocin moiety is formed through oxidative condensation of two 3-hydroxy-4-methylanthranilic acid (4-MHA) pentapeptide lactones (actinomycin halves) as the last step of actinomycin biosynthesis. We found that feeding of 4-MHA or its putative biogenetic precursor 3-hydroxyanthranilic acid (3-HA) to Streptomyces antibioticus induced formation of different new compounds at the expense of actinomycins. These contain only one pentapeptide lactone ring attached to the β-side of their phenoxazinone ring systems and are formed through premature condensation of the externally added abundant 4-MHA or 3-HA with actinomycin halves. They were termed hemi-actinomycins and C-demethyl-hemi-actinomycins, respectively, which differ from each other in the presence or absence of one or both methyl groups in their phenoxazinone moieties. 3-HA also induces synthesis of various C-demethylactinomycins formed through condensation of actinomycin halves in which 3-HA had been incorporated by the 4-MHA incorporating enzyme in lieu of 4-MHA. 3-HA was not converted to 4-MHA as revealed by its inability to stimulate synthesis of actinomycin or hemi-actinomycin synthesis and thus remained a substrate analogue of 4-MHA rather than its precursor. In contrast to S. antibioticus, actinomycin-producing streptomycetes such as Streptomyces chrysomallus or Streptomyces parvulus do not form hemi-structured actinomycins when fed with 3-HA or 4-MHA. They do not possess the enzyme phenoxazinone synthase (PHS) which in S. antibioticus is present and most probably catalyses premature condensation of abundant 4-MHA or 3-HA with actinomycin halves. Testing hemi-acinomycin IV for drug activity revealed that it intercalates into DNA and inhibits relaxation and supertwisting of DNA by topoisomerase I and DNA-gyrase like actinomycin IV (D). Moreover, it has inhibitory activity on growth of Bacillus subtilis.DFG, EXC 314, Unifying Concepts in Catalysi

Perception and Action in Sports. On the Functionality of Foveal and Peripheral Vision

An optimal coupling between perception and action is crucial for successful performance in sports. In basketball, for example, a stable fixation onto the basket helps to gain precise visual information of the target to successfully throw a basketball into the basket. In basketball-defense situations, however, opposing players cutting to the basket can be detected by using peripheral vision as less precise information are sufficient to mark this player. Those examples elucidate that to solve a given task foveal and peripheral vision can be used to acquire the necessary information. Following this reasoning, the current state of our framework will be presented that allows one to predict the functionality of one or the other or both depending on the current situation and task demands. In more detail, for tasks that require high motor precision like in far-aiming tasks, empirical evidence suggests that stable foveal fixations facilitate inhibitory processes of alternative action parameterization over movement planning and control. However, more complex situations (i.e., with more than one relevant information source), require peripheral vision to process relevant information by positioning gaze at a functional location which might actually be in free space between the relevant information sources. Based on these elaborations, we will discuss complementarities, the role of visual attention as well as practical implications

Characteristic Features of the Regulatory Functions of the ᴅ-Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase from Spinach

Catalysis and regulation of CO2 fixation differ in a characteristic manner in their response to anionic modifiers and the polarity of the reaction medium. Monovalent inorganic anions inhibit catalysis and CO2-activation of the ᴅ-ribulose 1,5-bisphosphate carboxylase/oxygenase from spinach, whereas the activity and binding of NADPH and effector sugar phosphates are affected only at appreciably higher concentrations. In contrast such modulators with a dianion structure stimulate CO2 fixation by an increase of the affinity of the enzyme for the activator CO2 and stabilization of the reactive carbamate. Structure-activity studies revealed a broad specificity of the enzyme for these regulatory effects. Essentially amino groups are involved in these processes. Certain organic solvents, as methanol or acetone, stimulate CO2 fixation by a similar modification of the CO2 activation centers, as induced by dianionic effectors. These results infer that such effects are due to a decrease of the polarity at the regulatory centers of the enzyme and a concomitant change of the pK of the active lysine responsible for the binding of the activator CO2. A correlation of effector binding and activity demonstrates that already low, non-saturating concentrations of such modifiers induce high activation levels of the carboxylase and prevent the dissociation of the activated ternary complex. It is discussed that the central problem concerning the catalytical competence of ᴅ-ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the presence of active site directed dianionic effectors can be solved kinetically

Influence of Peripheral Perception on Motor Control

In sports, attention must presumably be divided to multiple players in order to monitor their move-ments and to initiate the correct motor response at the right time. First, in a series of three experi-mental studies, this proposed functionality has been investigated to propose ways for sport-specific investigations on peripheral vision. For the experimental studies, we chose the Multiple-Object Tracking (MOT) task, a task with high experimental control in which we could expect that peripheral vision would naturally be used for target monitoring (i.e., without the instruction to locate gaze on a fixation cross). The task requires one to monitor 4 initially highlighted targets moving together with 6 distractors (10 square objects in total). In this task, gaze seems predominantly not be located on individual targets, but rather on the virtual center of mass (“centroid” of the targets). Thus, it can be expected that peripheral vision is used for target monitoring. In Study 1, the validity of the MOT paradigm was tested to make sure that peripheral vision was indeed used for target monitoring as well as to examine the motion sensitivity of peripheral vision. In Study 2, we tested if this motion sensitivity holds true in dual task situations with a concurrent monitoring and detection tasks. In Study 3, we systematically manipulated visual and attentional demands to analyze the influence of these factors on gaze behavior during monitoring and change-detection performance. Considering the results of all three studies, the functionality of peripheral vision allows for the monitoring of mul-tiple moving objects, the (simultaneous) detection of motion changes and the avoidance of sac-cade-related costs (because saccades would interrupt visual information processing). It could fur-ther be shown that capabilities of the visual and the attentional systems affect the gaze anchoring location and peripheral monitoring and detection performance. In a theoretical paper, we link our fundamental results to sports situations, for example, the monitoring of multiple players in soccer and the peripheral detection of a crucial player’s movement, and discuss how a sport-specific func-tionality could be tested in future experiments. In field- and laboratory experiments, we already test-ed this proposed functionality and found, for example in martial arts, that national athletes anchor their gaze on the opponent’s chest to detect attacks from arms and legs. In a beach-volleyball de-fense situations, experts seem to anchor their gaze between the ball and the attacking player (i.e., in free space and not on an actual visual cue). This suggests that peripheral vision is used to monitor both movements. In current studies, we make use of virtual reality applications to examine the functionality of peripheral vision with a higher degree of experimental control but at the same time a high ecological validity. Our final aim is to train expert’s peripheral vision in sport specific settings to improve visual information pick-up outside the fovea

Investigation of the potential of Brevibacillus spp. for the biosynthesis of nonribosomally produced bioactive compounds by combination of genome mining with MALDI-TOF mass spectrometry

The biosynthetic potential of 11 Brevibacillus spp. strains was investigated by combination of genome mining with mass spectrometric analysis using MALDI-TOF mass spectrometry. These endophytic, plant associated Brevibacillus strains were isolated from crop plants, such as coffee and black pepper, in Vietnam. Draft genomes of these strains were available. They were classified (a) by comparison with type strains and a collection of genome-sequenced Brevibacillus spp. deposited in the NCBI data base as well as (b) by construction of a phylogenetic tree from the core sequences of publicly available genomes of Brevibacillus strains. They were identified as Brevibacillus brevis (1 strain); parabrevis (2 strains); porteri (3 strains); and 5 novel Brevibacillus genomospecies. Our work was specifically focused on the detection and characterization of nonribosomal peptides produced by these strains. Structural characterization of these compounds was performed by LIFT-MALDI-TOF/TOF mass spectrometric sequence analysis. The highlights of our work were the demonstration of the tyrocidines, a well-known family of cyclodecapeptides of great structural variability, as the main products of all investigated strains and the identification of a novel class of pentapeptides produced by B. brevis; B. schisleri; and B. porteri which we designate as brevipentins. Our biosynthetic studies demonstrate that knowledge of their biosynthetic capacity can efficiently assist classification of Brevibacillus species.Peer Reviewe

Fusaricidins, Polymyxins and Volatiles Produced by Paenibacillus polymyxa Strains DSM 32871 and M1

Paenibacilli are efficient producers of potent agents against bacterial and fungal pathogens, which are of great interest both for therapeutic applications in medicine as well as in agrobiotechnology. Lipopeptides produced by such organisms play a major role in their potential to inactivate pathogens. In this work we investigated two lipopeptide complexes, the fusaricidins and the polymyxins, produced by Paenibacillus polymyxa strains DSM 32871 and M1 by MALDI-TOF mass spectrometry. The fusaricidins show potent antifungal activities and are distinguished by an unusual variability. For strain DSM 32871 we identified numerous yet unknown variants mass spectrometrically. DSM 32871 produces polymyxins of type E (colistins), while M1 forms polymyxins P. For both strains, novel but not yet completely characterized polymyxin species were detected, which possibly are glycosylated. These compounds may be of interest therapeutically, because polymyxins have gained increasing attention as last-resort antibiotics against multiresistant pathogenic Gram-negative bacteria. In addition, the volatilomes of DSM 32781 and M1 were investigated with a GC–MS approach using different cultivation media. Production of volatile organic compounds (VOCs) was strain and medium dependent. In particular, strain M1 manifested as an efficient VOC-producer that exhibited formation of 25 volatiles in total. A characteristic feature of Paenibacilli is the formation of volatile pyrazine derivatives.Peer Reviewe