Hot off the presses! Oct 12 curr biol

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Latest Articles Include:

• Depth charges
  - curr biol 20(19):R827-R828 (2010)
  Mediawatch: Concerns are growing about the extent of long-term ecological damage in the Gulf of Mexico after the oil spill. Richard F. Harris reports.
• New insights into climate carbon
  - curr biol 20(19):R828-R829 (2010)
  A new study on rainforest carbon emissions is one new tool in climate change research. Nigel Williams reports.
• Beefing up biodiversity issues
  - curr biol 20(19):R830 (2010)
  The UN believes governments need to strengthen species protection plans. Nigel Williams reports.
• Extreme insects
  - curr biol 20(19):R831-R832 (2010)
  A new book celebrates the extraordinary diversity of one of the planet's most diverse groups. Nigel Williams reports.
• Diversity worries
  - curr biol 20(19):R832-R833 (2010)
  New Zealand is tackling major biodiversity issues. Nigel Williams reports.
• Decline of la dolce vita
  - curr biol 20(19):R833 (2010)
  
• Peter J. Hollenbeck
  - curr biol 20(19):R834-R835 (2010)
  
• Lysenko rising
  - curr biol 20(19):R835-R837 (2010)
  
• Grasses
  - curr biol 20(19):R837-R839 (2010)
  
• Dogs showing separation-related behaviour exhibit a 'pessimistic' cognitive bias
  - curr biol 20(19):R839-R840 (2010)
  Up to five million pet dogs in the UK (50% of the population) may, at some stage of their lives, perform undesirable separation-related behaviour (SRB) when left home alone [1], including vocalising, destruction and toileting [2]. Some owners perceive their dog to be 'fine' or even 'happy' when performing SRB [3], a few seek professional help [1], and others relinquish the dog [4]. Given the magnitude of the issue and the varied perceptions and behaviour of owners, the underlying emotional (affective) states of dogs showing SRB, and hence their welfare, requires elucidation. Whilst most dogs are believed to be anxious when showing SRB [1] and [2], it is uncertain whether their background affective state (mood) when they are not separated is also negative [1]. Here we use a new 'cognitive bias' measure of animal affect to show that dogs which exhibit high levels of SRB in a separation test also appear to have a more negative underlying mood.
• Sex Determination: A Worm Does It by Elimination
  - curr biol 20(19):R841-R843 (2010)
  Parasitic nematode worms of the genus Strongyloides have an alternation of many asexual, all-female generations with a sexual generation composed of males and females. Males of S. papillosus have now been shown to be produced by elimination of chromosomal material that constitutes the X chromosome in its close relatives.
• Plant Development: Early Events in Lateral Root Initiation
  - curr biol 20(19):R843-R845 (2010)
  How are the lateral root founder cells specified in the pericycle to initiate lateral root development? An Aux/IAA28 signaling module activates transcription factor GATA23 to control founder cell identity.
• Intracellular Transport: ER and Mitochondria Meet and Greet along Designated Tracks
  - curr biol 20(19):R845-R847 (2010)
  A recent study shows that contacts between the endoplasmic reticulum and mitochondria occur preferentially on acetylated microtubules, providing physiological support for the microtubule track selectivity of molecular motors.
• Insect Vision: A Few Tricks to Regulate Flight Altitude
  - curr biol 20(19):R847-R849 (2010)
  A recent study sheds new light on the visual cues used by Drosophila to regulate flight altitude. The striking similarity with previously identified steering mechanisms provides a coherent basis for novel models of vision-based flight control in insects and robots.
• Cyanotoxins: A Poison that Frees Phosphate
  - curr biol 20(19):R850-R852 (2010)
  Autotrophic organisms obtain phosphorus from the environment by secreting alkaline phosphatases that act on esters, resulting in inorganic phosphate that is then taken up. New work shows that the cyanobacterium Aphanizomenon ovalisporum obtains inorganic phosphate by secreting the cyanotoxin cylindrospermopsin, which induces alkaline phosphatase in other phytoplankton species.
• Motor Control: Exploring the Neurochemistry of Subliminal Inhibition
  - curr biol 20(19):R852-R853 (2010)
  A new study links individual differences in unconsciously triggered motor control to variability in GABA neurotransmitter concentration in the supplementary motor area of the human brain.
• Community Ecology: Top-Down Turned Upside-Down
  - curr biol 20(19):R854-R855 (2010)
  Within African savannas, elephants often damage individual trees to the extent that they influence tree density. New research shows that mutualistic ants inhabiting certain species of Acacia protect trees from catastrophic herbivory by elephants. Protection by the ants stabilizes tree cover across savannas in what is otherwise a highly dynamic biome.
• Behavioural Ecology: Social Networking for Dullards
  - curr biol 20(19):R856-R857 (2010)
  A recent paper shows that dull-plumaged male house finches can improve their mating success by moving to a different social network, where their plumage is brighter relative to that of other males.
• Emerging Roles for Natural MicroRNA Sponges
  - curr biol 20(19):R858-R861 (2010)
  Recently, a non-coding RNA expressed from a human pseudogene was reported to regulate the corresponding protein-coding mRNA by acting as a decoy for microRNAs (miRNAs) that bind to common sites in the 3′ untranslated regions (UTRs). It was proposed that competing for miRNAs might be a general activity of pseudogenes. This study raises questions about the potential ability of thousands of non-coding transcripts to interact with miRNAs and influence the expression of miRNA target genes. Three years ago, artificial miRNA decoys termed 'miRNA sponges' were introduced as a means to create loss-of-function phenotypes for miRNA families in cell culture and in virally infected tissue and transgenic animals. Given the efficacy of miRNA sponges expressed from stable chromosomal insertions, it seemed plausible that natural non-coding RNAs might have evolved to sequence-specifically sequester miRNAs. The first such endogenous sponge RNA was discovered in plants and found to ! attenuate a miRNA-mediated response to an environmental stress. More recently, a viral non-coding RNA was observed to sequester and promote the degradation of a cellular miRNA in infected primate cells. In this review we discuss the potential and proven roles for endogenous miRNA sponges and consider some criteria for screening candidate sponge RNAs.
• Genetics, Chromatin Diminution, and Sex Chromosome Evolution in the Parasitic Nematode Genus Strongyloides
  Nemetschke L Eberhardt AG Hertzberg H Streit A - curr biol 20(19):1687-1696 (2010)
  Background When chromatin diminution occurs during a cell division a portion of the chromatin is eliminated, resulting in daughter cells with a smaller amount of genetic material. In the parasitic roundworms Ascaris and Parascaris, chromatin diminution creates a genetic difference between the soma and the germline. However, the function of chromatin diminution remains a mystery, because the vast majority of the eliminated DNA is noncoding. Within the parasitic roundworm genus Strongyloides, S. stercoralis (in man) and S. ratti (in rat) employ XX/XO sex determination, but the situation in S. papillosus (in sheep) is different but controversial. Results We demonstrate genetically that S. papillosus employs sex-specific chromatin diminution to eliminate an internal portion of one of the two homologs of one chromosome pair in males. Contrary to ascarids, the eliminated DNA in S. papillosus contains a large number of genes. We demonstrate that the region undergoing diminution is homologous to the X chromosome of the closely related S. ratti. The flanking regions, which are not diminished, are homologous to the S. ratti autosome number I. Furthermore, we found that the diminished chromosome is not incorporated into sperm, resulting in a male-specific transmission ratio distortion. Conclusions Our data indicate that on the evolutionary path to S. papillosus, the X chromosome fused with an autosome. Chromatin diminution serves to functionally restore an XX/XO sex-determining system. A consequence of the fusion and the process that copes with it is a transmission ratio distortion in males for certain loci.
• A Novel Aux/IAA28 Signaling Cascade Activates GATA23-Dependent Specification of Lateral Root Founder Cell Identity
  De Rybel B Vassileva V Parizot B Demeulenaere M Grunewald W Audenaert D Van Campenhout J Overvoorde P Jansen L Vanneste S Möller B Wilson M Holman T Van Isterdael G Brunoud G Vuylsteke M Vernoux T De Veylder L Inzé D Weijers D Bennett MJ Beeckman T - curr biol 20(19):1697-1706 (2010)
  Background Lateral roots are formed at regular intervals along the main root by recurrent specification of founder cells. To date, the mechanism by which branching of the root system is controlled and founder cells become specified remains unknown. Results Our study reports the identification of the auxin regulatory components and their target gene, GATA23, which control lateral root founder cell specification. Initially, a meta-analysis of lateral root-related transcriptomic data identified the GATA23 transcription factor. GATA23 is expressed specifically in xylem pole pericycle cells before the first asymmetric division and is correlated with oscillating auxin signaling maxima in the basal meristem. Also, functional studies revealed that GATA23 controls lateral root founder cell identity. Finally, we show that an Aux/IAA28-dependent auxin signaling mechanism in the basal meristem controls GATA23 expression. Conclusions We have identified the first molecular components that control lateral root founder cell identity in the Arabidopsis root. These include an IAA28-dependent auxin signaling module in the basal meristem region that regulates GATA23 expression and thereby lateral root founder cell specification and root branching patterns.
• Mek1 Kinase Governs Outcomes of Meiotic Recombination and the Checkpoint Response
  Wu HY Ho HC Burgess SM - curr biol 20(19):1707-1716 (2010)
  Background Homologous recombination promotes proper segregation of chromosomes during meiosis. Programmed double-strand breaks (DSBs) initiate recombination and are repaired preferentially using the homolog rather than the sister chromatid template. In yeast, activation of Mek1 kinase upholds this bias. Mek1 is also a proposed effector kinase in the recombination checkpoint that responds to aberrant DNA and/or axis structures. Elucidating a role for Mek1 in this checkpoint has been difficult, because a mek1 null mutation causes rapid repair of DSBs using a sister chromatid, thus bypassing formation of checkpoint-activating lesions. Here we analyzed a MEK1 gain-of-function allele to test if it would enhance interhomolog bias and/or the checkpoint response. Results When Mek1 activation was artificially maintained through glutathione S-transferase-mediated dimerization, there was an enhanced skew toward interhomolog recombination and reduction of intersister events, including multichromatid joint molecules. Increased interhomolog events were specifically repaired as noncrossovers rather than as crossovers. Ectopic Mek1 dimerization was also sufficient to impose interhomolog bias in the absence of recombination checkpoint functions, thereby uncoupling these two processes. Finally, the stringency of the checkpoint response was enhanced in mutants with weak recombination defects by blocking prophase exit in a subset of cells in which arrest is not absolute. Conclusions We propose that Mek1 plays dual roles during meiotic prophase I by phosphorylating targets directly involved in the recombination checkpoint, as well as targets involved in sister chromatid recombination. We discuss how regulation of pachytene exit by Mek1 or similar kinases could influence checkpoint stringency, which may differ among species and between sexes.
• In Vitro Reconstitution of the Functional Interplay between MCAK and EB3 at Microtubule Plus Ends
  Montenegro Gouveia S Leslie K Kapitein LC Buey RM Grigoriev I Wagenbach M Smal I Meijering E Hoogenraad CC Wordeman L Steinmetz MO Akhmanova A - curr biol 20(19):1717-1722 (2010)
  The kinesin-13 family member mitotic centromere-associated kinesin (MCAK) is a potent microtubule depolymerase [[1], [2], [3] and [4]]. Paradoxically, in cells it accumulates at the growing, rather than the shortening, microtubule plus ends. This plus-end tracking behavior requires the interaction between MCAK and members of the end-binding protein (EB) family [[5], [6], [7] and [8]], but the effect of EBs on the microtubule-destabilizing activity of MCAK and the functional significance of MCAK accumulation at the growing microtubule tips have so far remained elusive. Here, we dissect the functional interplay between MCAK and EB3 by reconstituting EB3-dependent MCAK activity on dynamic microtubules in vitro. Whereas MCAK alone efficiently blocks microtubule assembly, the addition of EB3 restores robust microtubule growth, an effect that is not dependent on the binding of MCAK to EB3. At the same time, EB3 targets MCAK to growing microtubule ends by increasing its assoc! iation rate with microtubule tips, a process that requires direct interaction between the two proteins. This EB3-dependent microtubule plus-end accumulation does not affect the velocity of microtubule growth or shortening but enhances the capacity of MCAK to induce catastrophes. The combination of MCAK and EB3 thus promotes rapid switching between microtubule growth and shortening, which can be important for remodeling of the microtubule cytoskeleton.
• Cholinergic Enhancement Augments Magnitude and Specificity of Visual Perceptual Learning in Healthy Humans
  Rokem A Silver MA - curr biol 20(19):1723-1728 (2010)
  Learning through experience underlies the ability to adapt to novel tasks and unfamiliar environments. However, learning must be regulated so that relevant aspects of the environment are selectively encoded. Acetylcholine (ACh) has been suggested to regulate learning by enhancing the responses of sensory cortical neurons to behaviorally relevant stimuli [1]. In this study, we increased synaptic levels of ACh in the brains of healthy human subjects with the cholinesterase inhibitor donepezil (trade name: Aricept) and measured the effects of this cholinergic enhancement on visual perceptual learning. Each subject completed two 5 day courses of training on a motion direction discrimination task [2], once while ingesting 5 mg of donepezil before every training session and once while placebo was administered. We found that cholinergic enhancement augmented perceptual learning for stimuli having the same direction of motion and visual field location used during training. In ! addition, perceptual learning with donepezil was more selective to the trained direction of motion and visual field location. These results, combined with previous studies demonstrating an increase in neuronal selectivity following cholinergic enhancement [[3], [4] and [5]], suggest a possible mechanism by which ACh augments neural plasticity by directing activity to populations of neurons that encode behaviorally relevant stimulus features.
• Determination of Onset of Sexual Maturation and Mating Behavior by Melanocortin Receptor 4 Polymorphisms
  Lampert KP Schmidt C Fischer P Volff JN Hoffmann C Muck J Lohse MJ Ryan MJ Schartl M - curr biol 20(19):1729-1734 (2010)
  Polymorphisms in reproductive strategies are among the most extreme and complex in nature. A prominent example is male body size and the correlated reproductive strategies in some species of platyfish and swordtails of the genus Xiphophorus. This polymorphism is controlled by a single Mendelian locus (P) that determines the onset of sexual maturity of males. Because males cease growth after reaching puberty, this results in a marked size polymorphism. The different male size classes show pronounced behavioral differences (e.g., courtship versus sneak mating), and females prefer large over small males. We show that sequence polymorphisms of the melanocortin receptor 4 gene (mc4r) comprise both functional and non-signal-transducing versions and that variation in copy number of mc4r genes on the Y chromosome underlies the P locus polymorphism. Nonfunctional Y-linked mc4r copies in larger males act as dominant-negative mutations and delay the onset of puberty. Copy number ! variation, as a regulating mechanism, endows this system with extreme genetic flexibility that generates extreme variation in phenotype. Because Mc4r is critically involved in regulation of body weight and appetite, a novel link between the physiological system controlling energy balance and the regulation of reproduction becomes apparent.
• Artificial Night Lighting Affects Dawn Song, Extra-Pair Siring Success, and Lay Date in Songbirds
  Kempenaers B Borgström P Loës P Schlicht E Valcu M - curr biol 20(19):1735-1739 (2010)
  Associated with a continued global increase in urbanization [1], anthropogenic light pollution is an important problem [2]. However, our understanding of the ecological consequences of light pollution is limited [[2], [3] and [4]]. We investigated effects of artificial night lighting on dawn song in five common forest-breeding songbirds. In four species, males near street lights started singing significantly earlier at dawn than males elsewhere in the forest, and this effect was stronger in naturally earlier-singing species. We compared reproductive behavior of blue tits breeding in edge territories with and without street lights to that of blue tits breeding in central territories over a 7 year period. Under the influence of street lights, females started egg laying on average 1.5 days earlier. Males occupying edge territories with street lights were twice as successful in obtaining extra-pair mates than their close neighbors or than males occupying central forest ter! ritories. Artificial night lighting affected both age classes but had a stronger effect on yearling males. Our findings indicate that light pollution has substantial effects on the timing of reproductive behavior and on individual mating patterns. It may have important evolutionary consequences by changing the information embedded in previously reliable quality-indicator traits [[5] and [6]].
• Individual-Level Bet Hedging in the Bacterium Sinorhizobium meliloti
  Ratcliff WC Denison RF - curr biol 20(19):1740-1744 (2010)
  The expression of phenotypic variability can enhance geometric mean fitness and act as a bet-hedging strategy in unpredictable environments [1]. Metazoan bet hedging usually involves phenotypic diversification among an individual's offspring [[2], [3], [4], [5] and [6]], such as differences in seed dormancy. Virtually all known microbial bet-hedging strategies, in contrast, rely on low-probability stochastic switching of a heritable phenotype by individual cells in a clonal group [[7], [8], [9] and [10]]. This is less effective at generating within-group diversity when group size is small. Here we describe a novel microbial bet-hedging behavior that resembles individual-level metazoan bet hedging. Sinorhizobium meliloti stores carbon and energy in poly-3-hydroxybutyrate (PHB) as a contingency against carbon scarcity [11]. We show that, when starved, dividing S. meliloti bet hedge by forming two daughter cells with different phenotypes. These have high and low PHB level! s and are suited to long- and short-term starvation, respectively. The low-PHB cells have greater competitiveness for resources, whereas the high-PHB cells can survive for over a year without food, perhaps until a legume host is next available.
• The Involvement of the Left Motor Cortex in Learning of a Novel Action Word Lexicon
  Liuzzi G Freundlieb N Ridder V Hoppe J Heise K Zimerman M Dobel C Enriquez-Geppert S Gerloff C Zwitserlood P Hummel FC - curr biol 20(19):1745-1751 (2010)
  Current theoretical positions assume that action-related word meanings are established by functional connections between perisylvian language areas and the motor cortex (MC) [[1], [2], [3] and [4]] according to Hebb's associative learning principle [5]. To test this assumption, we probed the functional relevance of the left MC for learning of a novel action word vocabulary by disturbing neural plasticity in the MC with transcranial direct current stimulation (tDCS) [[6], [7], [8] and [9]]. In combination with tDCS, subjects learned a novel vocabulary of 76 concrete, body-related actions by means of an associative learning paradigm. Compared with a control condition with "sham" stimulation, cathodal tDCS reduced success rates in vocabulary acquisition, as shown by tests of novel action word translation into the native language. The analysis of learning behavior revealed a specific effect of cathodal tDCS on the ability to associatively couple actions with novel word! s. In contrast, we did not find these effects in control experiments, when tDCS was applied to the prefrontal cortex or when subjects learned object-related words. The present study lends direct evidence to the proposition that the left MC is causally involved in the acquisition of novel action-related words.
• A Catalytic Role for Mod5 in the Formation of the Tea1 Cell Polarity Landmark
  Bicho CC Kelly DA Snaith HA Goryachev AB Sawin KE - curr biol 20(19):1752-1757 (2010)
  Many systems regulating cell polarity involve stable landmarks defined by internal cues [[1], [2], [3], [4] and [5]]. In the rod-shaped fission yeast Schizosaccharomyces pombe, microtubules regulate polarized vegetative growth via a landmark involving the protein Tea1 [[6], [7], [8] and [9]]. Tea1 is delivered to cell tips as packets of molecules associated with growing microtubule ends [10] and anchored at the plasma membrane via a mechanism involving interaction with the membrane protein Mod5 [[11] and [12]]. Tea1 and Mod5 are highly concentrated in clusters at cell tips in a mutually dependent manner, but how the Tea1-Mod5 interaction contributes mechanistically to generating a stable landmark is not understood. Here, we use live-cell imaging, FRAP, and computational modeling to dissect dynamics of the Tea1-Mod5 interaction. Surprisingly, we find that Tea1 and Mod5 exhibit distinctly different turnover rates at cell tips. Our data and modeling suggest that rather th! an acting simply as a Tea1 receptor or as a molecular "glue" to retain Tea1, Mod5 functions catalytically to stimulate incorporation of Tea1 into a stable tip-associated cluster network. The model also suggests an emergent self-focusing property of the Tea1-Mod5 cluster network, which can increase the fidelity of polarized growth.
• Shapes of Krill Swarms and Fish Schools Emerge as Aggregation Members Avoid Predators and Access Oxygen
  Brierley AS Cox MJ - curr biol 20(19):1758-1762 (2010)
  Many types of animals exhibit aggregative behavior: birds flock, bees swarm, fish shoal, and ungulates herd [1]. Terrestrial and aerial aggregations can be observed directly, and photographic techniques have provided insights into the behaviors of animals in these environments [2] and data against which behavioral theory can be tested [3]. Underwater, however, limited visibility can hamper direct observation, and understanding of shoaling remains incomplete. We used multibeam sonar to observe three-dimensional structure of Antarctic krill shoals acoustically [4]. Shoal size and packing density varied greatly, but surface area:volume ratios (roughnesses) were distributed narrowly about 3.3 m−1 [5]. Shoals of clupeid fish (e.g., sardine, anchovy) from geographically and oceanographically diverse locations have very similar roughnesses [[6], [7] and [8]]. This common emergent shape property suggests common driving forces across diverse ecosystems. Group behavior can be ! complex [9], but a simple tradeoff—that we model—in which individual fish and krill juggle only their access to oxygen-replete water and exposure to predation can explain the observed shoal shape. Decreasing oxygen availability in a warming world ocean [10] may impact shoal structure: because structure affects catchability by predators and fishers [[11], [12] and [13]], understanding the response will be necessary for ecological and commercial reasons.
• Human Muscle Spindles Act as Forward Sensory Models
  Dimitriou M Edin BB - curr biol 20(19):1763-1767 (2010)
  Modern theories of motor control incorporate forward models that combine sensory information and motor commands to predict future sensory states [[1] and [2]]. Such models circumvent unavoidable neural delays associated with on-line feedback control [3]. Here we show that signals in human muscle spindle afferents during unconstrained wrist and finger movements predict future kinematic states of their parent muscle. Specifically, we show that the discharges of type Ia afferents are best correlated with the velocity of length changes in their parent muscles approximately 100–160 ms in the future and that their discharges vary depending on motor sequences in a way that cannot be explained by the state of their parent muscle alone. We therefore conclude that muscle spindles can act as "forward sensory models" [4]: they are affected both by the current state of their parent muscle and by efferent (fusimotor) control, and their discharges represent future kinematic sta! tes. If this conjecture is correct, then sensorimotor learning implies learning how to control not only the skeletal muscles but also the fusimotor system.
• Defensive Plant-Ants Stabilize Megaherbivore-Driven Landscape Change in an African Savanna
  Goheen JR Palmer TM - curr biol 20(19):1768-1772 (2010)
  Tree cover in savanna ecosystems is usually regarded as unstable, varying with rainfall, fire, and herbivory [[1], [2], [3] and [4]]. In sub-Saharan Africa, elephants (Loxodonta africana) suppress tree cover, thereby maintaining landscape heterogeneity by promoting tree-grass coexistence. In the absence of elephants, tree encroachment may convert savannas into closed-canopy woodlands [[5] and [6]]; when elephants increase in abundance, intensified browsing pressure can transform savannas into open grasslands [[5], [6], [7] and [8]]. We show that symbiotic ants stabilize tree cover across landscapes in Kenya by protecting a dominant tree from elephants. In feeding trials, elephants avoided plants with ants and did not distinguish between a myrmecophyte (the whistling-thorn tree [Acacia drepanolobium]) from which ants had been removed and a highly palatable, nonmyrmecophytic congener. In field experiments, elephants inflicted severe damage on whistling-thorn trees from w! hich ants had been removed. Across two properties on which elephants increased between 2003 and 2008, cover of whistling-thorn did not change significantly inside versus outside large-scale elephant exclusion fences; over the same period of time, cover of nonmyrmecophytes differed profoundly inside versus outside exclusion fences. These results highlight the powerful role that symbioses and plant defense play in driving tree growth and survival in savannas, ecosystems of global economic and ecological importance. PaperFlick To view the video inline, enable JavaScript on your browser. However, you can download and view the video by clicking on the icon below Download this Video (23393 K)
• Coupling of Apoptosis and L/R Patterning Controls Stepwise Organ Looping
  Suzanne M Petzoldt AG Spéder P Coutelis JB Steller H Noselli S - curr biol 20(19):1773-1778 (2010)
  Handed asymmetry in organ shape and positioning is a common feature among bilateria, yet little is known about the morphogenetic mechanisms underlying left-right (LR) organogenesis. We utilize the directional 360° clockwise rotation of genitalia in Drosophila to study LR-dependent organ looping. Using time-lapse imaging, we show that rotation of genitalia by 360° results from an additive process involving two ring-shaped domains, each undergoing 180° rotation. Our results show that the direction of rotation for each ring is autonomous and strictly depends on the LR determinant myosin ID (MyoID). Specific inactivation of MyoID in one domain causes rings to rotate in opposite directions and thereby cancels out the overall movement. We further reveal a specific pattern of apoptosis at the ring boundaries and show that local cell death is required for the movement of each domain, acting as a brake-releaser. These data indicate that organ looping can proceed through an i! ncremental mechanism coupling LR determination and apoptosis. Furthermore, they suggest a model for the stepwise evolution of genitalia posture in Diptera, through the emergence and duplication of a 180° LR module.
• Individual Differences in Subconscious Motor Control Predicted by GABA Concentration in SMA
  Boy F Evans CJ Edden RA Singh KD Husain M Sumner P - curr biol 20(19):1779-1785 (2010)
  Subliminal visual stimuli affect motor planning [1], but the size of such effects differs greatly between individuals [[2] and [3]]. Here, we investigated whether such variation may be related to neurochemical differences between people. Cortical responsiveness is expected to be lower under the influence of more of the main inhibitory neurotransmitter, GABA [4]. Thus, we hypothesized that, if an individual has more GABA in the supplementary motor area (SMA)—a region previously associated with automatic motor control [5]—this would result in smaller subliminal effects. We measured the reversed masked prime—or negative compatibility—effect, and found that it correlated strongly with GABA concentration, measured with magnetic resonance spectroscopy. This occurred specifically in the SMA region, and not in other regions from which spectroscopy measurements were taken. We replicated these results in an independent cohort: more GABA in the SMA region is reliably asso! ciated with smaller effect size. These findings suggest that, across individuals, the responsiveness of subconscious motor mechanisms is related to GABA concentration in the SMA.