We next investigated the relation between FGM and the saccade landing position. We measured the deviation from the median saccade landing position for every stimulus position (Figure 2B) on every trial and selected the 25% of the trials where the saccadic endpoint deviated most to the left but still landed in the 2.5° target window (blue arrows in Figure 7B) and the 25% of the trials where the saccade deviated

most to the right (red arrows). BAY 73-4506 cost In the remaining 50% of trials the saccadic endpoint was relatively close to the center (green arrows). Figures 7C and 7D shows the spatiotemporal profile of V1 FGM in the trials with deviating saccades. If the saccade deviated to the left, FGM was higher on the left side of the figure and if the saccade deviated to the right FGM was strong on the right side of the figure (paired t tests, p < 0.05). In the trials where the saccade ended close to the center, FGM was more

HCS assay homogeneous (Figure 7E) and stronger (p < 0.05, see Supplemental Information). Accordingly, the strength of FGM in area V1 predicted saccadic accuracy (Figure S6). We observed similar effects in V4 where an increase of FGM on the left predicted that the saccade would deviate to the left, and an increase in FGM on the right predicted a deviation of the saccade to the right (Figure S6). These results suggest that the profile of FGM is read out for the accurate planning of saccades toward the center of the figure. The relative timing of the neuronal activity evoked by the line elements, the FGM and the attention effects provides insight into the chain of events underlying figure-ground segregation. To measure the timing of visually Thiamine-diphosphate kinase driven activity, we fitted a curve to the average visual responses and took the time point where it reached 33% of its maximum as an estimate of latency (Roelfsema et al., 2007) (colored traces in Figure 8A, see Supplemental Information). The latency of the visual

response in V1 was 40 ms and the latency in V4 was 52 ms, and a bootstrap analysis indicated that this latency difference was significant (p < 0.01). To measure the latency of FGM in the two areas, we fitted the same type of curve to the difference between the responses evoked by the figure and background (Figure 8A). The edge modulation in V1 had a latency of 60 ms and was followed by FGM in V4 at latency of 67 ms. These latencies were both later than the visual response in V4 (p < 0.05), and the difference between them was marginally significant (p = 0.06). Finally, the V1 center modulation occurred with a latency of 95 ms, significantly later than V1 edge-FGM and V4 FGM (both Ps < 0.05). An analysis of latency across individual recording sites confirmed these effects. Activity in area V1 started with the visual response, which was followed by edge-FGM (Figure 8B, p < 10−6, paired t test), which was, in turn, followed by center-FGM (Figure 8C, p < 10−4, paired t test).

, 2008). In contrast, no genetic variation was apparent in the Trichomonas sequences obtained from isolates causing morbidity in mortality in passerines in the UK ( Robinson et al., 2010). Of particular interest is the finding of the T. vaginalis-like organism in the owl. Gerhold et al. (2008) found these sequences associated with white-winged doves in Arizona, Texas and California.

Although similar white-winged doves are not found high throughput screening in Brazil, picazuro Pigeon (Patagioenas picazuro) are common. It would be useful to survey and sequence positive trichomonad isolates from picazuro pigeons to determine if they contain similar sequence identity to the T. vaginalis-like isolate from this study. One sequence, from a green-winged saltator with inflammatory and necrotic lesions in the liver, was 100% identical to a Simplicomonas sp. sequence that caused hepatitis-associated mortality in a backyard chicken in Georgia (USA) ( Lollis et al., 2011). Given that the saltators were confiscated during attempts to smuggle birds into other states or countries, the illegal trade market may explain the appearance of the Simplicomonas sp. in the United States. Further surveillance and molecular genotyping of illegally and legally traded birds is needed to determine the transmission risk of novel

protozoal infections in native wild birds and domestic poultry. To our knowledge, this is the first report of a Simplicomonas sp. causing disease in a free ranging bird. Small molecule library mouse This study was supported by

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG). “
“Mixed infections by dipteran larvae and helminthes are quite common in ruminants. Sheep are frequently parasitized simultaneously by gastrointestinal nematodes (GIN) and by Oestrus ovis larvae. These parasite infections stimulate immune mechanisms of defense that can be mediate by antibodies or cells, but the efficiency of this immune response depends on the animal genotype, age, gender, physiological status, prior exposure to the pathogen, capacity to recall the antigen, health and nutritional status, parasite and the infection stage ( Colditz, Rolziracetam 2008). Proinflammatory immune reactions are characteristic of O. ovis infection and involve the recruitment of cells (mast cells, eosinophils, macrophages, T and B lymphocytes) and the secretion of immunoglobulins, suggesting a type Th2 immune response ( Angulo-Valadez et al., 2011) that is similar to the immune response against gastrointestinal parasitism by nematodes ( Anthony et al., 2007 and Rowe et al., 2008). Studies of the relationship between O. ovis and helminth co-infections have revealed that there are antagonist interactions between O. ovis larvae and the Strongyle nematodes, Trichostrongylus colubriformis and Haemonchus contortus ( Yacob et al., 2004 and Terefe et al., 2005).

, 2010). In a manner similar to the infamous prions, misfolded oligomers composed by diverse proteins can act as a template to induce the conversion of natively folded proteins, propagating the abnormalities to other cells, tissues, and organs. In the case of tau pathology, the current study by de Calignon et al., in addition to various recent reports from other groups (Clavaguera et al., 2009, Frost

et al., 2009, Guo and Lee, 2011 and Nonaka et al., 2010), indicates that misfolding and aggregation of tau may start in a restricted area of the brain and from there spread toward other regions through synaptic connections, leading to a progressive amplification of the damage and expansion throughout the brain. Many open questions regarding this prion-like phenomenon of spreading of tau misfolding still need to be addressed, including the following four points. (1) What are the factors and mechanisms responsible for the formation of the first Microbiology inhibitor misfolded tau seeds? In the present study, pathology

was initiated by artificial expression of a human mutant version of the tau gene in a defined brain area. In the study by Clavaguera and colleagues (2009), the seeds were introduced by direct intracerebral injection of brain homogenates containing tau aggregates. It is possible to envision at least three different ways in which the initial seeds may arise. First, seeds may be formed spontaneously in a particular area of the brain, perhaps PI3K inhibitor as a consequence of somatic mutations, transcriptional/translational errors, defects of the proteostasis machinery, or tissue injury (e.g., brain trauma or subclinical stroke), all of which are probably more frequent during aging. Second, the initial seeds may be acquired exogenously through an “infection-like” process of exposure to preformed aggregates. In prion diseases, transmission between individuals can occur through medical practices (e.g., blood transfusion, organ transplants, and use of materials or surgical tools contaminated with prions), consumption of food from animals carrying misfolded prions, or Thalidomide vertical transmission (Will, 2003). Third, misfolded aggregates composed of one protein may interact

and promote the aggregation of another protein by a phenomenon known as cross-seeding. Evidence for this process has been found for several PMDs, using animal models, in vitro systems, and human epidemiological analysis (see Morales et al., 2009 and references therein). It is also possible that non-disease-associated aggregates (so-called functional amyloids) may also induce misfolding of disease-related proteins through cross-seeding (Johan et al., 1998). (2) What are the mechanisms responsible for the transference of tau seeds between cells? Studies with cellular models of tau and α-synuclein suggest that intracellular aggregates gain access to the extracellular space either by secretion or by damage of the host cell (Guo and Lee, 2011 and Nonaka et al.

The overall intensity of EBAX-1::GFP peaked at the 3-fold stage, especially around the nerve

ring region ( Figure 1F, right panel) and dropped after hatching. In the fourth larval stage (L4), EBAX-1::GFP was detected in the nerve ring, the ventral nerve cord, the HSN motor neuron, and some neurons in the tail ( Figure S2A). Mos1 transposase-mediated single copy insertion (MosSCI) of Pebax-1::EBAX-1::GFP showed similar expression dynamics, albeit at a lower expression level (data not shown). EBAX-1::GFP showed a punctate pattern in the cytosol of individual neurons ( Figure S2A). A similar punctate pattern was also BI2536 observed in the soma and axons when EBAX-1::GFP was specifically expressed in mechanosensory neurons and GABAergic motor neurons (data not shown). Likewise, GFP-tagged mouse ZSWIM8 displayed a cytosolic expression pattern in cultured heterologous cells ( Figure S2B). To decipher the roles of ebax-1 in the developing selleck screening library nervous system,

we first examined the morphology of HSN motor neurons that control the egg-laying behavior, because ebax-1 mutants exhibit modest egg-laying defects that can be rescued by neuronal expression of EBAX-1 ( Figure 2B). We found that 30% of the ebax-1(ju699) mutants showed HSN axon guidance defects at 20°C ( Figures 2C and 2D). A moderate temperature rise to 25°C increased the guidance errors in wild-type and mutant animals, whereas overexpression of EBAX-1 in the wild-type background significantly improved HSN guidance accuracy ( Figure 2E). These observations suggest that the accuracy of HSN axon guidance is temperature dependent and sensitive to the level of EBAX-1. A similar temperature dependency of axon guidance defects was also observed in AVM neurons of ebax-1 mutants ( Figure S2E). Through extensive analyses of genetic interactions, we identified

a specific role Calpain for ebax-1 in the ventral axon guidance of both HSN motor neurons and AVM and PVM mechanosensory neurons (the latter two also called touch neurons). Ventral guidance of HSN and AVM/PVM axons is in response to a combination of attractive Netrin/DCC (UNC-6/UNC-40) and repellent Slit/Robo (SLT-1/SAX-3) signals ( Figure 2F) ( Desai et al., 1988, Hao et al., 2001 and Zallen et al., 1998). Mutations disrupting either pathway partially disrupt ventral guidance, whereas simultaneous loss of both pathways causes fully penetrant ventral guidance defects ( Figures 2D, 2H, and 2I; Figures S2C and S2D). In AVM neurons, ebax-1 mutants alone did not show any guidance defects at 20°C but significantly enhanced guidance defects in unc-6(ev400) or unc-40(e1430) mutants ( Figures 2H and S2C). In contrast, ebax-1 mutations did not enhance AVM axon guidance defects in the slt-1 or sax-3 mutant backgrounds ( Figures 2H and S2C). In PVM and HSN, ebax-1 showed synergistic effects with both slt-1/sax-3 and unc-6/unc-40 pathways ( Figures 2D and 2I; Figure S2D).

, due to the cost of a survey with more than

10 questions. This survey did however provide some insight into why our respondents began a barefoot running program. A recent survey study investigating the demographics of barefoot runners found the primary motivating factors for those who added barefoot or minimalist shod running to their training was prevention of future injury and performance enhancement. 9 Rothschild found fear of possible injury was the most prevalent perceived barrier in transitioning to BKM120 purchase barefoot or minimalist shod running. However, consistent with our data, they also found that most of the respondents reported no adverse reactions or subsequent injuries after instituting barefoot or minimal running. 9 Similarly, a large number of runners in our study initially tried barefoot

running due to the promise of improved efficiency (60%) or an attempt to get past injury (53%). The runners in our survey ran barefoot on a variety of surfaces including streets, sidewalks, grass, and trails. It has been argued that the decrease in proprioception in cushioned running shoes modifies the body’s natural mechanism for attenuating impact forces, therefore increasing their magnitude.7 The body attempts to attenuate impact forces as failure to do so can result in micro trauma to soft tissue and bone.10 One way the body attempts to mitigate these forces is through adjusting leg stiffness. The body will adjust leg stiffness by altering muscular activity and PFT�� chemical structure joint angles across a variety of surfaces in order to minimize below stress and curtail injuries. Therefore, runners can experience similar impact forces on either hard or soft surfaces with no differences in impact loading whether they are barefoot or shod by appropriately adjusting their leg spring.7 and 11 Efficiency and performance enhancement with barefoot running is a controversial topic. It has been shown that heart rate, maximal oxygen consumption (VO2max), and relative perceived exertion are significantly

higher in the shod runner.12 This study also showed at 70% of VO2max pace, barefoot running is more economical than is running shod, both over ground and on a treadmill. Squadrone and Gallozzi8 found maximum oxygen uptake values to be 1.3% lower when running barefoot than when running in shoes. However, it was also shown that barefoot runners have higher step rates and higher metabolic rates than shod.8 Therefore, it is not clear if barefoot running is more economical metabolically than shod running. A majority of runners in this survey (55%) reported no or slight performance benefit secondary to barefoot running, and over 39% of the runners found moderate to significant improvements in their race times. However, only 6% of respondents claimed to have gotten slower after starting barefoot training. Barefoot running changes biomechanics by encouraging a shorter stride and increased step rate.

, 1998 and Soliman

et al., 2010). The ERK phosphorylation level was significantly higher in the cortex of vehicle-treated Fmr1 KO animals compared to vehicle-treated WT littermates (KO/vehicle: 122.9% ± 9.3% of WT/vehicle; p = 0.010; Figures 3D and 3H). Chronic treatment with CTEP specifically reduced the elevated ERK activity in Fmr1 KO cortex (KO/CTEP: 89.5% ± 6.5% of WT/vehicle; KO/CTEP versus KO/vehicle; p = 0.0012) with no effect on ERK activity in WT cortex. Chronic CTEP treatment also triggered a modest increase of the total ERK expression level in Fmr1 KO mice compared to vehicle-treated KO animals (KO/CTEP: 109.0% ± 6.5%; KO/vehicle: 95.1% ± 6.0%; p = 0.013; Figure 3E). The mTOR phosphorylation level was nonsignificantly increased in vehicle-treated R428 cost Fmr1 KO animals compared to vehicle-treated WT littermates

(KO/vehicle: 109.1% ± 5.0% of WT/vehicle; p = 0.13; Figure 3F). Chronic CTEP treatment significantly reduced the mTOR phosphorylation level specifically in Fmr1 KO mice and not in WT animals (KO/CTEP: 92.0% ± 4.6% of WT/vehicle; KO/CTEP versus KO/vehicle; p = 0.006). mTOR expression levels were similar in WT and KO animals and were unchanged by treatment INCB024360 manufacturer ( Figure 3G). The postadolescent macroorchidism observed in FXS patients is reflected in elevated testis weight in Fmr1 KO mice ( The Dutch-Belgian Fragile X Consortium, 1994). Testis weight was monitored starting with drug-naive 5-week-old mice throughout 17 weeks of chronic treatment with CTEP and vehicle. Fmr1 KO mice presented significantly increased testis weight compared to WT animals at all adult ages (effect size: +32.8 mg, p < 0.001; Figure 3J; see Table S2 available online), which was partially corrected upon chronic treatment (effect size: −13.5 mg, p < 0.001). No significant differences in plasma levels of testosterone ( Figure 3K) and progesterone ( Figure 3L) were observed between genotypes and treatment groups. Chronic treatment was well tolerated by the animals independent of the genotype. There was a minimal Dipeptidyl peptidase reduction in body weight gain (Figure S1A) and a modest decrease in body

temperature of 0.5°C on average (Figure S1B) in animals receiving chronic CTEP treatment compared to vehicle in both genotypes. Chronic drug treatment for 4 weeks had no effect on the rotarod performance (Figure S1C). A small but significantly reduced grip strength in vehicle-treated Fmr1 KO compared to WT mice and in CTEP-treated mice of both genotypes compared to vehicle-treated WT mice was observed ( Figure S1D). A modified version of the Irwin battery of simple neurological and observational measures ( Irwin, 1968) did not reveal any noticeable alteration in the general fitness of the animals resulting from the mutation or the treatment ( Table S1). This study assessed the therapeutic potential of chronic pharmacological mGlu5 inhibition in a mouse model of FXS, with treatment starting in young adulthood.

, 2007). These baseline hemodynamic signatures have a significant impact on the interpretation of activated functional networks associated with different sensory, attentive, or cognitive states (Greicius Akt inhibitor et al., 2009; Honey et al., 2009; Biswal et al., 2010; Deco et al., 2011; Smith et al., 2009). The link between resting-state metrics and anatomical connectivity has largely been supported by modeling of areal correlations with known interareal connection

patterns (Fox et al., 2005, 2006; Honey et al., 2007; Vincent et al., 2007; Luczak et al., 2009; Schölvinck et al., 2010; Deco and Jirsa, 2012); however, this relationship has not been examined directly with studies of anatomical connectivity (Matsui et al., 2011). The neuronal basis of the resting state is also uncertain. Although hemodynamics-based

networks have been associated with widespread low-frequency correlations in local field potentials (Arieli et al., Roxadustat supplier 1996; Cohen and Kohn, 2011, Kenet et al., 2003), there is little evidence that resting-state connectivity is related to underlying neuronal connectivity. Moreover, as resting-state studies have focused on broad cortico-cortical networks, little attention has been paid to resting-state connectivity patterns at finer local cortical scales. In this study, we seek to establish the relationship between anatomical connectivity, functional neuronal connectivity, and local resting-state connectivity patterns revealed by fMRI. Our testbed for this study is the connectivity pattern of digit-tip representations not in the somatosensory cortex (areas 3b and 1) of squirrel monkeys, an area central to manual

behavior in monkeys and amenable to study with fMRI and electrophysiological and anatomical connectivity techniques. This multimodal approach aims to establish an understanding of local (at the millimeter scale) baseline networks revealed by resting-state connectivity and, furthermore, provide evidence to support a local to global hierarchy of resting states within the brain. Resting-state functional connectivity patterns of digit-tip representations in primary somatosensory cortex (SI) were examined in 11 squirrel monkeys (one case is shown in Figures 1A, 1B, and 1D–1F). Under isoflurane anesthesia, blood oxygen level-dependent (BOLD) maps of digit activation (Figure 1B) and the resting-state acquisitions (static probe touching digit-tip skin; Figures 1D–1F) were recorded using a 9.4T Varian MRI scanner. Seed locations (Figures 1A and 1B, open blue squares) were selected based on fMRI and/or electrophysiological maps of areas 3b and 1 (Figure 1A); using surface vasculature as landmarks (arrowheads), these maps were readily coregistered to the maps acquired by MRI (cf. Chen et al., 2007).

While GFAP, for example, labels type B cells within the VZ-SVZ, GLAST is also present in a limited number of C cell progeny (Pastrana et al., 2009), possibly due to perdurance after

proliferation of the primary progenitors. Similarly, the orphan nuclear receptor Tlx, which was initially thought to be expressed only in nestin-positive type B cells (Shi et al., 2004), is also transcribed at high levels in C cells. Mash1 and EGFR are present in a limited number of B cells, and are now suggested to possibly distinguish a population of “activated” B cells in addition to the GFAP-negative C cells (Doetsch et al., 2002, Pastrana et al., 2009 and Kim et al., 2011). In addition, subsequent studies of markers that were suggested to be exclusive to the progenitor cell compartment, such as nestin, have found that these proteins are more broadly expressed within the brain (Hendrickson selleck chemicals et al., 2011). These results argue that the large number of putative stem and progenitor cell markers are likely to identify overlapping but not identical subsets of adult VZ-SVZ cells, highlighting the need for caution and accompanying functional studies when assigning biological characteristics to the stem cell population (for further discussion of this topic, see Chojnacki et al., 2009). Given that Type B1 cells have many astroglial characteristics,

finding potential markers to distinguish Type B1 cells from other nongerminal astrocytes within the SVZ and in the Proteases inhibitor brain parenchyma would be extremely useful in future studies of this region. Neural stem cells are present transiently at many locations along the developing neuraxis, as this complex tissue generates the many cell types required in the mature CNS (Alvarez-Buylla et al., 2001 and Noctor et al., 2007). At birth, the walls of the lateral ventricles still bear many similarities to the ventricular zone present in the immature neuroepithelium. They are comprised mainly of radial glia, progenitors with cell

bodies close to the ventricles and a long radial process that contacts the pial surface of the brain (Hartfuss et al., 2001 and Merkle et al., 2004). Radial glia, which function as neural stem cells (NSCs) in the embryonic and fetal brain, generate an immense diversity of neurons and glial cells within a short period of already time—days in the mouse and weeks in the human—to assemble the central nervous system (CNS). A select group of radial glia then transform into unique subpopulations of astrocytes that continue to function as primary neural progenitors during juvenile and adult life. Viral targeting of these cells via their radial processes, as well as anatomical studies, have demonstrated that during the next several days of postnatal development, the radial glia located on the walls of the lateral ventricles retract their long RC2-positive distal process, lose RC2 expression, and give rise to the type B1 astrocytes that become the slow-cycling stem cells of the VZ-SVZ (Merkle et al.

, 2013 and Pastoll et al., 2013). If grid patterns are generated in stellate cells, the competitive interactions must therefore be exclusively inhibitory. In favor of this possibility, recent modeling has shown that in networks where each neuron has an inhibitory output of a constant magnitude and a fixed radius, activity will

self-organize into a stable hexagonal grid pattern (Couey et al., 2013, Bonnevie et al., 2013 and Pastoll et al., 2013) (Figure 4). One condition for this to occur is for the network to receive steady excitatory input from an external source. Without such input, the firing of a grid cell would be determined MAPK inhibitor by its external inputs, such as directional signals from the head direction system. Experimental

work supports this prediction. Removal of one of the find more major excitatory inputs (from the hippocampus) leads to disruption of the grid pattern at the same time that directional modulation is increased (Bonnevie et al., 2013). The attractor models receive indirect support from a number of research lines. The strongest indication of an attractor mechanism is perhaps the observation that, within a grid module, the spatial relationship between pairs of grid cells persists across environments and environmental manipulations, despite substantial changes in the sensory input (Fyhn et al., 2007 and Yoon et al., 2013). The fact that cell-cell relationships are better preserved across environments than

responses of single cells speaks in favor of a network organization in which grid-cell activity falls into a low number of internally generated stable states (Yoon et al., 2013). An additional line of support for this idea is the fact that grid cells are organized in modules with similar grid spacing and grid orientation found (Stensola et al., 2012). This is an implicit and necessary assumption of all existing attractor models for grid cells. A modular organization makes it possible to maintain a constant relationship between velocity of movement and displacement in the neural sheet such that the hexagonal organization of the grid network is reflected in the activity of individual neurons. Both sets of observations—internal coherence and modularity—are consistent with the notion that individual grid modules operate as attractor networks, but they do not prove it. It is important to be aware that the current evidence does not directly address the core ideas of the models, the mechanisms for hexagonal pattern formation and speed-dependent network translation. In future work, it will be necessary to test these mechanisms by direct observation, e.g., by monitoring spatial firing patterns in large networks of cells with known connectivity. It will be necessary to more directly address key assumptions, such as the proposed connectivity preference between grid cells with similar firing locations.

For barrel cortex experiments, mice were anesthetized with 100 mg/kg ketamine and 10 mg/kg xylazine i.p. injected, and whiskers were removed under a dissection scope by grasping them at the base with forceps and pulling. After whisker removal, mice were singly housed, and whiskers did not regrow substantially by the time of tamoxifen injection two days later. Approximately 6 hr after TM injection, mice were provided with cardboard tubes (approximately 3.5 cm in

diameter) and nesting material to stimulate whisker exploration. For visual stimulation, the homecages of singly housed mice were placed in individual light-tight cubicles with white walls. Light stimuli were delivered by an Anti-diabetic Compound Library order LED bulb mounted above the cage, which produced light of ∼500 lux at cage level. Drugs were injected with a dim red LED in an otherwise dark room. For the time course experiment, light was delivered at the same time of day (starting at 8 hr after the subjective dawn of the animal’s former light/dark cycle)

to all mice in order to control for possible circadian differences in sensitivity to stimulation, and the timing of drug injections was varied around this fixed time. For auditory stimulation, mice were placed into custom sound isolation cubicles lined with acoustic foam (Auralex Acoustics). Sound stimuli were generated in Audacity (https://audacity.sourceforge.net), produced by a PC sound card (Creative Labs), amplified (Onkyo), and delivered by a speaker (Fostex) mounted directly above the only animal’s cage. Stimuli were delivered at approximately 90 dB. For the novel environment experiments, mice were group housed until at least

Lumacaftor 3 days before the start of the experiment, at which point they were singly housed in standard 20 × 30 cm mouse cages in a normal colony room. Novel environment experiments were performed beginning 1–3 hr after the onset of the animals’ dark cycle, at which point experimental mice were transported to a separate room and placed in a dimly lit (<10 lux) 30 × 60 cm plastic cage with a running wheel, a wooden or plastic “hut,” a plastic tunnel, wooden chips for chewing, and buried food. After 1 hr, mice were removed from the novel environment and injected with either 4-OHT or vehicle before they were returned to the novel environment for another 1 hr, at which point they were returned to the homecage in the animal colony for 1 week before sacrifice. Homecage control mice were similarly injected with 4-OHT 1–3 hr after the onset of the dark cycle under dim white light 1 week prior to sacrifice. For all experiments, mice were subjected to only the minimal handling necessary for genotyping and colony maintenance prior to performing the experiments. Details of cell counting and quantification are available in the Supplemental Experimental Procedures. Statistical analyses were performed in Prism (GraphPad). We thank A. Huberman, A. Mizrahi, and C. Ran for advice; members of the Heller lab for help with preliminary experiments; B.