Selective tracking of template DNA strands after induction of mitosis with unreplicated genomes (MUGs) in Drosophila S2 cells

According to the “immortal” DNA strand hypothesis (Cairns Nature 255:197–200, 1975), stem cells would keep their template strands in order to prevent the accumulation of mutations, which could occur during DNA replication. Despite the growing number of studies that attempt to test this hypothesis, the conclusions remain highly controversial. In the base of this controversy lie the current limitations of available methodology to selectively and faithfully track the fate of template DNA strands throughout and upon cell division. Here, we developed a method that allows the unequivocal tracking of single chromatids containing template DNA strands in Drosophila S2 cells in culture. This method consists in the induction of mitosis with unreplicated genomes (MUGs) in which cells are allowed to enter mitosis without prior DNA replication. This is achieved by RNAi-mediated knockdown of Double parked, a conserved protein required for the initiation of DNA replication and post-replication checkpoint response. The advantages of this system when compared with MUGs generated in mammalian cells is the preservation of chromatid morphology, the ease of loss-of-function studies and the possibility of in vivo applications. Altogether, this approach allows for the readily visualization and tracking of template DNA strands by simply monitoring cells stably expressing GFP-fusions with either Histone H2B or the centromeric Histone variant CID/CENP-A by time-lapse fluorescence microscopy. This might be useful for the dissection of the molecular mechanism behind asymmetric DNA strand segregation.     

Regulation by scaffolding proteins of canonical transient receptor potential channels in striated muscle

Recent studies proposed a pivotal role of TRPC channels, in particular TRPC1, in the striated muscle tissue and in the development of calcium mishandling observed in dystrophin-deficient skeletal and cardiac muscle cells (Vandebrouck et al. in J Cell Biol 158:1089–1096, 2002; Williams and Allen in Am J Physiol Heart Circ Physiol 292:H846–H855, 2007; Stiber et al. in Mol Cell Biol 28:2637–2647, 2008). In skeletal muscle, TRPCs are proposed to function in a costameric macromolecular complex (Vandebrouck et al. in FASEB J 21:608–617, 2007; Gervasio et al. in J Cell Sci 121:2246–2255, 2008) in which scaffolding proteins and dystrophin are central components maintaining normal calcium entry (Stiber et al. in Mol Cell Biol 28:2637–2647, 2008; Sabourin et al. in J Biol Chem 284:36248–61, 2009). In this review, we shall summarize the roles played by scaffolding proteins in regulating the calcium entry through TRPC channels of skeletal muscle cells and the implications in muscle physiopathology. Interactions of TRPC1 with caveolin-3, Homer-1 and α-syntrophin will be addressed and these complexes will be compared with signalplex in other systems. The mechanosensitive function of scaffolding proteins will be discussed as well as interactions with TRPV2 channels regarding to calcium mishandling in Duchenne dystrophy.     

Sound-Induced Flash Illusion is Resistant to Feedback Training

A single flash accompanied by two auditory beeps tends to be perceived as two flashes (Shams et al. Nature 408:788, 2000, Cogn Brain Res 14:147–152, 2002). This phenomenon is known as ‘sound-induced flash illusion.’ Previous neuroimaging studies have shown that this illusion is correlated with modulation of activity in early visual cortical areas (Arden et al. Vision Res 43(23):2469–2478, 2003; Bhattacharya et al. NeuroReport 13:1727–1730, 2002; Shams et al. NeuroReport 12(17):3849–3852, 2001, Neurosci Lett 378(2):76–81, 2005; Watkins et al. Neuroimage 31:1247–1256, 2006, Neuroimage 37:572–578, 2007; Mishra et al. J Neurosci 27(15):4120–4131, 2007). We examined how robust the illusion is by testing whether the frequency of the illusion can be reduced by providing feedback. We found that the sound-induced flash illusion was resistant to feedback training, except when the amount of monetary reward was made dependent on accuracy in performance. However, even in the latter case the participants reported that they still perceived illusory two flashes even though they correctly reported single flash. Moreover, the feedback training effect seemed to disappear once the participants were no longer provided with feedback suggesting a short-lived refinement of discrimination between illusory and physical double flashes rather than vanishing of the illusory percept. These findings indicate that the effect of sound on the perceptual representation of visual stimuli is strong and robust to feedback training, and provide further evidence against decision factors accounting for the sound-induced flash illusion.     

Infectious Serologies and Autoantibodies in Hepatitis C and Autoimmune Disease-Associated Mixed Cryoglobulinemia

Mixed cryoglobulinemia (MC) syndrome is an immune complex-mediated vasculitis characterized by the clinical triad of purpura, weakness, and arthralgias, the morbidity of which is mainly related to kidney and peripheral nervous system dysfunction as well as to the development of a secondary lymphoma (Ferri et al. Autoimmun Rev 7:114?C120, 2007, Lidar et al. Ann N Y Acad Sci 1173:649?C657, 2009, Trejo et al. Semin Arthritis Rheum 33:19?C28, 2003). MC is associated with infectious and systemic disorders, principally autoimmune and lymphoproliferative diseases. Since the 1990s, a striking association (>90%) between MC and hepatitis C virus (HCV) infection has been established (Ferri and Bombardieri 2004; Pascual et al. J Infect Dis 162:569?C570, 1990). However, information regarding the etiopathogenesis of HCV-negative MC is scant (Mascia et al. Dig Liver Dis 39:61?C64, 2007). We hereby present our findings, as well as previously published data, regarding the presence of antibodies against infectious agents and autoantibodies in patients with MC in an attempt to establish novel associations which may shed light on the etiopathogenesis of this disease.     

Parametric control of collision rates and capture rates in geometrically enhanced differential immunocapture (GEDI) microfluidic devices for rare cell capture

The enrichment and isolation of rare cells from complex samples, such as circulating tumor cells (CTCs) from whole blood, is an important engineering problem with widespread clinical applications. One approach uses a microfluidic obstacle array with an antibody surface functionalization to both guide cells into contact with the capture surface and to facilitate adhesion; geometrically enhanced differential immunocapture is a design strategy in which the array is designed to promote target cell–obstacle contact and minimize other interactions (Gleghorn et al. 2010; Kirby et al. 2012). We present a simulation that uses capture experiments in a simple Hele-Shaw geometry (Santana et al. 2012) to inform a target-cell-specific capture model that can predict capture probability in immunocapture microdevices of any arbitrary complex geometry. We show that capture performance is strongly dependent on the array geometry, and that it is possible to select an obstacle array geometry that maximizes capture efficiency (by creating combinations of frequent target cell–obstacle collisions and shear stress low enough to support capture), while simultaneously enhancing purity by minimizing non-specific adhesion of both smaller contaminant cells (with infrequent cell–obstacle collisions) and larger contaminant cells (by focusing those collisions into regions of high shear stress).     

AMIGO2 mRNA expression in hippocampal CA2 and CA3a

AMIGO2, or amphoterin-induced gene and ORF (open reading frame) 2, belongs to the leucine-rich repeats and immunoglobulin superfamilies. The protein is a downstream target of calcium-dependent survival signals and, therefore, promotes neuronal survival. Here, we describe the mRNA distribution pattern of AMIGO2 throughout the mouse brain with special emphasis on the hippocampus. In the Ammon’s horn, a detailed comparison between the subregional mRNA expression patterns of AMIGO2 and Pcp4 (Purkinje cell protein 4)—a known molecular marker of hippocampal CA2 (Cornu Ammonis 2)—revealed a prominent AMIGO2 mRNA expression level in both the CA2 and the CA3a (Cornu Ammonis 3a) subregion of the dorsal and ventral hippocampus. Since this CA2/CA3a region is particularly resistant to neuronal injury and neurotoxicity [Stanfield and Cowan (Brain Res 309(2):299–307 1984); Sloviter (J Comp Neurol 280(2):183–196 1989); Leranth and Ribak (Exp Brain Res 85(1):129–136 1991); Young and Dragunow (Exp Neurol 133(2):125–137 1995); Ochiishi et al. (Neurosci 93(3):955–967 1999)], we suggest that the expression pattern of AMIGO2 indeed fits with its involvement in neuroprotection.     

The microvascular anatomy of the talus: a plastination study on the influence of total ankle replacement

Purpose

The purpose of our study was to systematize the arterial supply of the talus and characterize the vessel damage occurring in the talus after total ankle replacement. Previous studies exist using vascular injection to visualize the topic [Giebel et al. (Surg Radiol Anat 19:231–235, 1997); Mulfinger and Trueta (J Bone Joint Surg Br 52:160–167, 1970); Peterson et al. (Acta Orthop Scand 46:1026–1034, 1975); Peterson and Goldie (Acta Orthop Scand 45:260–270, 1974)]. The vascularization of the talus has previously been described by various authors [Aquino et al. (J Foot Surg 25:188–193, 1986); Haliburton et al. (J Bone Joint Surg Am 40:1115–1120, 1958); Mulfinger and Trueta (1970); Peterson et al. (1975); Wildenauer (Z Orthop Ihre Grenzgeb 113:730, 1975)]. The plastination method provides excellent intraosseous view of the arterial system and offers a helpful method to demonstrate the influence of the Scandinavian Total Ankle Replacement (STAR) on the blood vessels.

Methods

In a first step, the nutritive foramina were analyzed on 20 macerated cadaver feet. After this, the articular surface was measured with a print using Optosil. The next step was the visualization of the vascularization of the talus using the plastination method. After vascular injection, a STAR was implanted in two specimens and a plastination was done.

Results

The highest amount and density of nutritive foramina were found in the sulcus tali. Using the imprint technique for the examined tali, we found a mean area covered by cartilage of 56.9 % in comparison to the total surface. The deep fin of STAR has the potential to eliminate important blood vessels of the talus.

Conclusion

The plastination methods were useful methods to analyze the arterial supply of the talus. In our study, the STAR showed a dominant influence on the vascularization of the talus. The fin appeared to be too long. A design modification with a short fin could provide the arterial supply, but should be tested biomechanically.     

Print-to-print: a facile multi-object micro-patterning technique

In recent years, micropatterning techniques have gained increasing popularity from a broad range of engineering and biology communities for the promise to establish highly quantitative investigations on miniature biological objects (e.g., cells and bacteria) with spatially defined microenvironments. However, majority of the existing techniques rely on cleanroom-based microfabrication and cannot be easily extended to a regular biological laboratory. In this paper, we present a simple versatile printing-based method, referred to as Print-to-Print (P2P), to form multi-object micropatterns for potential biological applications, along with our recent efforts to deliver out-of-cleanroom microfabrication solutions to the general public (Zhao et al. 2009), (Xing et al. 2011), (Wang et al. 2009), (Pan and Wang 2011), (Zhao et al. 2011). The P2P method employs only a commercially available solid-phase printer and custom-made superhydrophobic films. The entire patterning process does not involve any thermal or chemical treatment. Moreover, the non-contact nature of droplet transferring and printing steps can be highly advantageous for sensitive biological uses. Using the P2P process, a minimal feature resolution of 229?±?17 μm has been successfully demonstrated. In addition, this approach has been applied to form biological micropatterning on various substrates as well as multi-object co-patterns on the commonly used surfaces. Finally, the reusability of superhydrophobic substrates has also been illustrated.     

Traditional and emerging roles for the SLC9 Na+/H+ exchangers

The SLC9 gene family encodes Na⁺/H⁺ exchangers (NHEs). These transmembrane proteins transport ions across lipid bilayers in a diverse array of species from prokaryotes to eukaryotes, including plants, fungi, and animals. They utilize the electrochemical gradient of one ion to transport another ion against its electrochemical gradient. Currently, 13 evolutionarily conserved NHE isoforms are known in mammals [22, 46, 128]. The SLC9 gene family (solute carrier classification of transporters: www.bioparadigms.org) is divided into three subgroups [46]. The SLC9A subgroup encompasses plasmalemmal isoforms NHE1-5 (SLC9A1-5) and the predominantly intracellular isoforms NHE6-9 (SLC9A6-9). The SLC9B subgroup consists of two recently cloned isoforms, NHA1 and NHA2 (SLC9B1 and SLC9B2, respectively). The SLC9C subgroup consist of a sperm specific plasmalemmal NHE (SLC9C1) and a putative NHE, SLC9C2, for which there is currently no functional data [46]. NHEs participate in the regulation of cytosolic and organellar pH as well as cell volume. In the intestine and kidney, NHEs are critical for transepithelial movement of Na⁺ and HCO₃ ^? and thus for whole body volume and acid–base homeostasis [46]. Mutations in the NHE6 or NHE9 genes cause neurological disease in humans and are currently the only NHEs directly linked to human disease. However, it is becoming increasingly apparent that members of this gene family contribute to the pathophysiology of multiple human diseases.     

Therapeutic HPV DNA vaccines

It is now well established that most cervical cancers are causally associated with HPV infection. This realization has led to efforts to control HPV-associated malignancy through prevention or treatment of HPV infection. Currently, commercially available HPV vaccines are not designed to control established HPV infection and associated premalignant and malignant lesions. To treat and eradicate pre-existing HPV infections and associated lesions which remain prevalent in the U.S. and worldwide, effective therapeutic HPV vaccines are needed. DNA vaccination has emerged as a particularly promising form of therapeutic HPV vaccines due to its safety, stability and ability to induce antigen-specific immunity. This review focuses on improving the potency of therapeutic HPV vaccines through modification of dendritic cells (DCs) by [1] increasing the number of antigen-expressing/antigen-loaded DCs, [2] improving HPV antigen expression, processing and presentation in DCs, and [3] enhancing DC and T cell interaction. Continued improvement in therapeutic HPV DNA vaccines may ultimately lead to an effective DNA vaccine for the treatment of HPV-associated malignancies.     

Perception of relative throw-ability

Bingham et al. (J Exp Psychol Hum Percept Perform 15(3):507–528, 1989) showed that skilled throwers can perceive optimal objects for throwing to a maximum distance. Zhu and Bingham (J Exp Psychol Hum Percept Perform 34(4):929, 2008, 36(4):862–875, 2010) replicated this finding and then showed that felt heaviness is used to perceive this affordance (see also Zhu and Bingham in Evol Hum Behav 32(4):288–293, 2011; Zhu et al. in Exp Brain Res 224(2):221–231, 2013). Throwers pick the best weight for spherical projectiles in each graspable size. Bingham et al. (J Exp Psychol Hum Percept Perform 15(3):507–528, 1989) speculated that relative throw-ability might be perceptible. This would mean that the ordering of distances achieved by maximum effort throws of different objects could be judged. This affordance property is not the same as optimal throw-ability, because it requires all projectiles to be evaluated relative to one another with respect to ordinally scaled distances, not just a discrete optimum. We now used a magnitude estimation task to test this hypothesis, comparing the resultant ordering with that exhibited by distances of throws in previous studies. The findings show that participants were able to perform the perceptual task. However, discrimination among objects of different weight within a size was better than between sizes. The implications of these results for understanding of the information used to perform this task are discussed.     

Supervised Segmentation of Polycystic Kidneys: a New Application for Stereology Data

Stereology is a volume estimation method, typically applied to diagnostic imaging examinations in population studies where planimetry is too time-consuming (Chapman et al. Kidney Int 64:1035–1045, 2003), to obtain quantitative measurements (Nyengaard J Am Soc Nephrol 10:1100–1123, 1999, Michel and Cruz-Orive J Microsc 150:117–136, 1988) of certain structures or organs. However, true segmentation is required in order to perform advanced analysis of the tissues. This paper describes a novel method for segmentation of region(s) of interest using stereology data as prior information. The result is an efficient segmentation method for structures that cannot be easily segmented using other methods.     

Bluetongue disease in Germany (2007–2008): monitoring of entomological aspects

In the summer of 2006, a bluetongue epidemic started in the border area of Belgium, The Netherlands, and Germany, spread within 2 years over large areas of Western and Central Europe, and caused substantial losses in farm ruminants. Especially sheep and cattle were severely affected, leading to a case–fatality ratio of nearly 40% in sheep (Conraths et al., Emerg Inf Dis 15(3):433–435, 2009). The German federal ministry of food, agriculture, and consumer protection (BMELV) established a countrywide monitoring on the occurrence of the vectors of this virus, i.e., midges (family Ceratopogonidae) of the genus Culicoides. The monitoring was done on 91 sites, most of which were localized in the 150-km restriction zone that existed in December 2006. A grid consisting of 45?×?45 km² cells was formed that covered the monitoring area. As a rule, one trap was placed into each grid cell. The monitoring program started at the end of March 2007 and lasted until May 2008. It included the catching of midges by ultraviolet light traps—done each month from days 1 until 8, the selection of midges of the Culicoides obsoletus, Culicoides pulicaris group, and other Culicoides spp., the testing of midges for bluetongue virus (BTV) by polymerase chain reaction (PCR), and the daily registration of weather data at each trap site for the whole monitoring period. The following main results were obtained: (1) Members of the C. obsoletus group were most commonly found in the traps, reaching often 3/4 of the catches. The African and South European vector of BTV—the species Culicoides imicola—was never found. (2) Members of the C. obsoletus group were most frequently found infected with BTV besides a few cases in the C. pulicaris group and other species. (3) Members of the C. obsoletus group were also found in winter. Their numbers were reduced, however, and they were caught mostly close to stables. Therefore, a true midge-free period does not exist during the year in Germany. (4) The amounts of midges caught daily depended on the weather conditions. If it was cold and/or windy, the traps contained only a few specimens. Since the months from January to May 2008 were considerably colder (at all farms) than their correspondents in 2007, the growing of the population of midges started 2–3 months later in 2008 than in 2007. (5) The highest populations of midges occurred in both years (2007 and 2008) during the months September and October. This corresponded significantly to the finding of highest numbers of infected midges and to the number of diseased cattle and sheep during these 2 months. (6) It is noteworthy that in general, the first virus-positive midges of the species C. obsoletus were found about 1 1/2 months later than the first clinical cases had occurred or later than the first PCR-proven virus-positive sentinel animals had been documented. In 2007, the first BTV-positive cattle were detected in May in North Rhine-Westphalia, while the first positive Culicoides specimens were only found in August on the same farm. Evaluating these main results of the entomological monitoring and the fact that many wild ruminants have also been infected with BTV, it becomes evident that bluetongue disease has become endemic in Central Europe, and that only constant effort including vaccination and perhaps also insecticidal protection of cattle and sheep will keep the economical losses at a reasonable level. The following papers (1–10) in this journal will contribute more details obtained from this worldwide unique entomological monitoring: Bartsch et al. 2009; Bauer et al. 2009; Stephan et al. 2009; Clausen et al. 2009; Hörbrand and Geier 2009; Kiehl et al. 2009; Mehlhorn et al. 2009; Kiel et al. 2009; Vorsprach et al. 2009; Balczun et al. 2009.     

Cell directional spread determines accuracy,precision, and length of the neuronal population vector

The neuronal population vector (NPV) for movement direction is the sum of weighted neuronal directional contributions. Based on theoretical considerations, we proposed recently that the sharpness of tuning will impact the directional precision, accuracy, and length of the NPV, such that sharper tuning will yield NPV with higher precision, higher accuracy, and shorter length (Mahan and Georgopoulos in Front Neural Circuits 7:92, 2013). Furthermore, we proposed that controlling the inhibitory drive in a local network could be the mechanism by which the sharpness of directional tuning would be varied, resulting in a continuous specification and control of movement’s directional precision, accuracy, and speed (Mahan and Georgopoulos in Front Neural Circuits 7:92, 2013, Fig. 5). As a first step in testing this idea, here we analyzed data from 899 cells recorded in the motor cortex during performance of a center → out task. There were two major findings. First, directional selectivity varied with cell activity, such that it was higher in cells with lower mean discharge rates. And second, NPVs calculated from subsets of cells with higher directional selectivity (and, correspondingly, lower mean discharge rates) were more accurate (i.e., closer to the movement), precise (i.e., less variable), and shorter (i.e., slower; Schwartz in Science 265:540–542, 1994). These findings confirm our predictions above made from modeling (Mahan and Georgopoulos in Front Neural Circuits 7:92, 2013) and provide a simple mechanism by which desired attributes of the directional motor command can be implemented. We hypothesize that the inhibitory drive in a local network is controlled directly and independently of recurrent collaterals or common excitatory inputs to other cells. This could be achieved by a private excitation/inhibition of key inhibitory interneurons in a way similar to that in operation for Renshaw cells in the spinal cord. The presence of such a private line of inhibitory control remains to be investigated.     

Role of the anterior insula in task-level control and focal attention

In humans, the anterior insula (aI) has been the topic of considerable research and ascribed a vast number of functional properties by way of neuroimaging and lesion studies. Here, we argue that the aI, at least in part, plays a role in domain-general attentional control and highlight studies (Dosenbach et al. 2006; Dosenbach et al. 2007) supporting this view. Additionally, we discuss a study (Ploran et al. 2007) that implicates aI in processes related to the capture of focal attention. Task-level control and focal attention may or may not reflect information processing supported by a single functional area (within the aI). Therefore, we apply a novel technique (Cohen et al. 2008) that utilizes resting state functional connectivity MRI (rs-fcMRI) to determine whether separable regions exist within the aI. rs-fcMRI mapping suggests that the ventral portion of the aI is distinguishable from more dorsal/anterior regions, which are themselves distinct from more posterior parts of the aI. When these regions are applied to functional MRI (fMRI) data, the ventral and dorsal/anterior regions support processes potentially related to both task-level control and focal attention, whereas the more posterior aI regions did not. These findings suggest that there exists some functional heterogeneity within aI that may subserve related but distinct types of higher-order cognitive processing.     

A novel reassortant H1N2 virus related to the pandemic H1N1 2009 influenza virus isolated from Korean pigs

Since the discovery of the pandemic H1N1 (pH1N1) virus in 2009, a novel reassortant H1N2 virus (A/Swine/Korea/VDS1/2010) containing the pH1N1 segments has been detected in Korean pig populations. The hemagglutinin and neuraminidase genes of this virus are derived from reassortant H1N1- and H1N2-group viruses, respectively, identified in Korean pigs, while other genes originate from contemporary circulating pH1N1 viruses. The antigenic and biological properties of this novel virus, as determined by clinical, pathological, serological, and genetic analyses, are similar to those of pH1N1 viruses, which infect swine easily (Weingartl et al. J Virol 84:2245–2256, 2010; Brookes et al. PLoS one 5:e9068, 2010; Lange et al. J Gen Virol 90:2119–2123, 2009). Determining whether this virus will become established and pose a threat to mammalian populations requires further investigation.     

The background is remapped across saccades

Physiological studies have found that neurons prepare for impending eye movements, showing anticipatory responses to stimuli presented at the location of the post-saccadic receptive fields (RFs) (Wurtz in Vis Res 48:2070–2089, 2008). These studies proposed that visual neurons with shifting RFs prepared for the stimuli they would process after an impending saccade. Additionally, psychophysical studies have shown behavioral consequences of those anticipatory responses, including the transfer of aftereffects (Melcher in Nat Neurosci 10:903–907, 2007) and the remapping of attention (Rolfs et al. in Nat Neurosci 14:252–258, 2011). As the physiological studies proposed, the shifting RF mechanism explains the transfer of aftereffects. Recently, a new mechanism based on activation transfer via a saliency map was proposed, which accounted for the remapping of attention (Cavanagh et al. in Trends Cogn Sci 14:147–153, 2010). We hypothesized that there would be different aspects of the remapping corresponding to these different neural mechanisms. This study found that the information in the background was remapped to a similar extent as the figure, provided that the visual context remained stable. We manipulated the status of the figure and the ground in the saliency map and showed that the manipulation modulated the remapping of the figure and the ground in different ways. These results suggest that the visual system has an ability to remap the background as well as the figure, but lacks the ability to modulate the remapping of the background based on the visual context, and that different neural mechanisms might work together to maintain visual stability across saccades.     

Action strategies used by children to avoid two vertical obstacles in non-confined space

Information used to determine the action strategies necessary to successfully pass through apertures is based on the dimensions of the individual and the mover’s action capabilities (Warren in J Exp Psychol 10:683–703, 1984; Warren and Whang in J Exp Psychol 13:371–383, 1987). Previous research has demonstrated that when children must pass through small spaces, they will produce a shoulder rotation at apertures 1.6 times their shoulder width and smaller (i.e., critical point) and their avoidance strategies are based more on dynamic than geometric measures (Snapp-Childs and Bingham in Exp Brain Res 198:527–533, 2009; Wilmut and Barnett in Exp Brain Res 210:185–194, 2011). The question remains as to whether similar strategies exist when children are given a choice in their obstacle avoidance strategy. The current study aimed to determine the action strategies employed by children when confronted with a non-confined obstacle avoidance task. Specifically, the study intended to identify the aperture width that elicited a change in action (e.g., a shoulder rotation or a change in travel path). Children (N = 12, mean age = 7.1 years, ±0.2) were instructed to walk along a 10-m path toward a visible goal located at the end of the pathway and avoid colliding with the two vertical obstacles placed halfway (5 m) down the path on either side of the midline. The space between the obstacles ranged between 0.6 and 1.8 times the participant’s shoulder width (presented in increments of 0.2). Results revealed that when the aperture was too small for straight passage, children choose to circumvent the obstacles rather than rotate their shoulders the majority of the time. However, unlike young and older adults (Hackney and Cinelli in Gait Posture 37:93–97, 2013a, Exp Brain Res 225:419–429, 2013b), this strategy was not used consistently. Instead, changes in travel path were highly variable both across participants and within trials. This variability suggests that a true critical point cannot be established for children in this non-confined task. Variable actions at the time of crossing were significantly correlated with the medial–lateral center of mass variability during the approach to the obstacles. These results further support the idea that children’s actions may be more affected by dynamic factors than geometric measures.