Showing papers by "Tel Aviv University published in 2006"

Adaptive linear step-up procedures that control the false discovery rate

Abstract: We provide a new two-stage procedure in which the linear step-up procedure is used in stage one to estimate mo, providing a new level q' which is used in the linear step-up procedure in the second stage. We prove that a general form of the two-stage procedure controls the false discovery rate at the desired level q. This framework enables us to study analytically the properties of other procedures that exist in the literature. A simulation study is presented that shows that two-stage adaptive procedures improve in power over the original procedure, mainly because they provide tighter control of the false discovery rate. We further study the performance of the current suggestions, some variations of the procedures, and previous suggestions, in the case where the test statistics are positively dependent, a case for which the original procedure controls the false discovery rate. In the setting studied here the newly proposed two-stage procedure is the only one that controls the false discovery rate. The procedures are illustrated with two examples of biological importance.

The fusiform face area: a cortical region specialized for the perception of faces.

Abstract: Faces are among the most important visual stimuli we perceive, informing us not only about a person’s identity, but also about their mood, sex, age and direction of gaze The ability to extract this information within a fraction of a second of viewing a face is important for normal social interactions and has probably played a critical role in the survival of our primate ancestors Considerable evidence from behavioural, neuropsychological and neurophysiological investigations supports the hypothesis that humans have specialized cognitive and neural mechanisms dedicated to the perception of faces (the face-specificity hypothesis) Here, we review the literature on a region of the human brain that appears to play a key role in face perception, known as the fusiform face area (FFA) Section 1 outlines the theoretical background for much of this work The face-specificity hypothesis falls squarely on one side of a longstanding debate in the fields of cognitive science and cognitive neuroscience concerning the extent to which the mind/brain is composed of: (i) special-purpose (‘domain-specific’) mechanisms, each dedicated to processing a specific kind of information (eg faces, according to the face-specificity hypothesis), versus (ii) general-purpose (‘domain-general’) mechanisms, each capable of operating on any kind of information Face perception has long served both as one of the prime candidates of a domain-specific process and as a key target for attack by proponents of domain-general theories of brain and mind Section 2 briefly reviews the prior literature on face perception from behaviour and neurophysiology This work supports the face-specificity hypothesis and argues against its domain-general alternatives (the individuation hypothesis, the expertise hypothesis and others) Section 3 outlines the more recent evidence on this debate from brain imaging, focusing particularly on the FFA We review the evidence that the FFA is selectively engaged in face perception, by addressing (and rebutting) five of the most widely discussed alternatives to this hypothesis In §4, we consider recent findings that are beginning to provide clues into the computations conducted in the FFA and the nature of the representations the FFA extracts from faces We argue that the FFA is engaged both in detecting faces and in extracting the necessary perceptual information to recognize them, and that the properties of the FFA mirror previously identified behavioural signatures of face-specific processing (eg the face-inversion effect) Section 5 asks how the computations and representations in the FFA differ from those occurring in other nearby regions of cortex that respond strongly to faces and objects The evidence indicates clear functional dissociations between these regions, demonstrating that the FFA shows not only functional specificity but also area specificity We end by speculating in § 6o n some of the broader questions raised by current research on the FFA, including the developmental origins of this region and the question of whether faces are unique versus whether similarly specialized mechanisms also exist for other domains of high-level perception and cognition

Best Practices or Best Guesses? Assessing the Efficacy of Corporate Affirmative Action and Diversity Policies

Abstract: Employers have experimented with three broad approaches to promoting diversity. Some programs are designed to establish organizational responsibility for diversity, others to moderate managerial bias through training and feedback, and others to reduce the social isolation of women and minority workers. These approaches find support in academic theories of how organizations achieve goals, how stereotyping shapes hiring and promotion, and how networks influence careers. This is the first systematic analysis of their efficacy. The analyses rely on federal data on the workforces of 708 private-sector establishments from 1971 to 2002, coupled with survey data on their employment practices. Efforts to moderate managerial bias through diversity training and diversity evaluations are least effective at increasing white women, black women, and black men in management. Efforts to attack social isolation through mentoring and networking show modest effects. Efforts to establish responsibility for diversity lead to the broadest increases in managerial diversity. Moreover, organizations that establish responsibility see better effects from diversity training and evaluations, networking and mentoring. Employers subject to federal affirmative action edicts also see stronger effects from some programs. This work lays the foundation for an institutional theory of the remediation of workplace inequality, focused on organizational structures allocating responsibility for reducing segregation.

How proteins produce cellular membrane curvature

Abstract: Biological membranes exhibit various function-related shapes, and the mechanism by which these shapes are created is largely unclear. Here, we classify possible curvature-generating mechanisms that are provided by lipids that constitute the membrane bilayer and by proteins that interact with, or are embedded in, the membrane. We describe membrane elastic properties in order to formulate the structural and energetic requirements of proteins and lipids that would enable them to work together to generate the membrane shapes seen during intracellular trafficking.

Autophagic and tumour suppressor activity of a novel Beclin1-binding protein UVRAG

Abstract: Autophagy, the degradation of cytoplasmic components, is an evolutionarily conserved homeostatic process involved in environmental adaptation, lifespan determination and tumour development. The tumor suppressor Beclin1 is part of the PI(3) kinase class III (PI(3)KC3) lipid-kinase complex that induces autophagy. The autophagic activity of the Beclin1-PI(3)KC3 complex, however, is suppressed by Bcl-2. Here, we report the identification of a novel coiled-coil UV irradiation resistance-associated gene (UVRAG) as a positive regulator of the Beclin1-PI(3)KC3 complex. UVRAG, a tumour suppressor candidate that is monoallelically mutated at high frequency in human colon cancers, associates with the Beclin1-Bcl-2-PI(3)KC3 multiprotein complex, where UVRAG and Beclin1 interdependently induce autophagy. UVRAG-mediated activation of the Beclin1-PI(3)KC3 complex promotes autophagy and also suppresses the proliferation and tumorigenicity of human colon cancer cells. These results identify UVRAG as an essential component of the Beclin1-PI(3)KC3 lipid kinase complex that is an important signalling checkpoint for autophagy and tumour-cell growth.

Construal Levels and Self-Control

Abstract: The authors propose that self-control involves making decisions and behaving in a manner consistent with high-level versus low-level construals of a situation. Activation of high-level construals (which capture global, superordinate, primary features of an event) should lead to greater self-control than activation of low-level construals (which capture local, subordinate, secondary features). In 6 experiments using 3 different techniques, the authors manipulated construal levels and assessed their effects on self-control and underlying psychological processes. High-level construals led to decreased preferences for immediate over delayed outcomes, greater physical endurance, stronger intentions to exert self-control, and less positive evaluations of temptations that undermine self-control. These results support a construal-level analysis of self-control.

Celecoxib for the Prevention of Colorectal Adenomatous Polyps

Abstract: Background Overexpression of cyclooxygenase 2 (COX-2) has been associated with colorectal adenomatous polyps and cancer, prompting researchers to propose its inhibition as a chemopreventive intervention. Methods The Prevention of Colorectal Sporadic Adenomatous Polyps trial was a randomized, placebo-controlled, double-blind study of the COX-2 inhibitor celecoxib given daily in a single 400-mg dose. At 107 centers in 32 countries, we randomly assigned 1561 subjects who had had adenomas removed before enrollment to receive celecoxib (933 subjects) or placebo (628 subjects) daily, after stratification according to the use or nonuse of low-dose aspirin. The primary outcome was detection of adenomas at either year 1 or year 3 by colonoscopy and was compared among the groups with the use of the Mantel–Cox test. Results Colonoscopies were performed at year 1 on 88.7 percent of the subjects who had undergone randomization and at year 3 on 79.2 percent. Of the 557 subjects in the placebo group and the 840 subjects in the celecoxib group who were included in the efficacy analysis, 264 and 270, respectively, were found to have at least one adenoma at year 1, at year 3, or both. The cumulative rate of adenomas detected through year 3 was 33.6 percent in the celecoxib group and 49.3 percent in the placebo group (relative risk, 0.64; 95 percent confidence interval, 0.56 to 0.75; P<0.001). The cumulative rate of advanced adenomas detected through year 3 was 5.3 percent in the celecoxib group and 10.4 percent in the placebo group (relative risk, 0.49; 95 percent confidence interval, 0.33 to 0.73; P<0.001). Adjudicated serious cardiovascular events occurred in 2.5 percent of subjects in the celecoxib group and 1.9 percent of those in the placebo group (relative risk, 1.30; 95 percent confidence interval, 0.65 to 2.62). Conclusions The use of 400 mg of celecoxib once daily significantly reduced the occurrence of colorectal adenomas within three years after polypectomy. (ClinicalTrials.gov number, NCT00141193.)

Inhibition of amyloid fibril formation by polyphenols: structural similarity and aromatic interactions as a common inhibition mechanism.

Abstract: The formation of well-ordered fibrillar protein deposits is common to a large group of amyloid-associated disorders. This group consists of several major human diseases such as Alzheimer's disease, Parkinson's disease, prion diseases, and type II diabetes. Currently, there is no approved therapeutic agent directed towards the formation of fibrillar assemblies, which have been recently shown to have a key role in the cytotoxic nature of amyloidogenic proteins. One important approach in the development of therapeutic agents is the use of small molecules that specifically and efficiently inhibit the aggregation process. Several small polyphenol molecules have been demonstrated to remarkably inhibit the formation of fibrillar assemblies in vitro and their associated cytotoxicity. Yet, the inhibition mechanism was mostly attributed to the antioxidative properties of these polyphenol compounds. Based on several observations demonstrating that polyphenols are capable of inhibiting amyloid fibril formation in vitro, regardless of oxidative conditions, and in view of their structural similarities we suggest an additional mechanism of action. This mechanism is assuming structural constraints and specific aromatic interactions, which direct polyphenol inhibitors to the amyloidogenic core. This proposed mechanism is highly relevant for future de novo inhibitors' design as therapeutic agents for the treatment of amyloid-associated diseases.

Structure and function of photosystems i and ii

Abstract: Oxygenic photosynthesis, the principal converter of sunlight into chemical energy on earth, is catalyzed by four multi-subunit membrane-protein complexes: photosystem I (PSI), photosystem II (PSII), the cytochrome b6f complex, and F-ATPase PSI generates the most negative redox potential in nature and largely determines the global amount of enthalpy in living systems PSII generates an oxidant whose redox potential is high enough to enable it to oxidize H2O, a substrate so abundant that it assures a practically unlimited electron source for life on earth During the last century, the sophisticated techniques of spectroscopy, molecular genetics, and biochemistry were used to reveal the structure and function of the two photosystems The new structures of PSI and PSII from cyanobacteria, algae, and plants has shed light not only on the architecture and mechanism of action of these intricate membrane complexes, but also on the evolutionary forces that shaped oxygenic photosynthesis

International multicenter pilot study of the first comprehensive self-completed nonmotor symptoms questionnaire for Parkinson's disease : The NMSQuest study

Abstract: Nonmotor symptoms (NMS) of Parkinson's disease (PD) are not well recognized in clinical practice, either in primary or in secondary care, and are frequently missed during routine consultations. There is no single instrument (questionnaire or scale) that enables a comprehensive assessment of the range of NMS in PD both for the identification of problems and for the measurement of outcome. Against this background, a multidisciplinary group of experts, including patient group representatives, has developed an NMS screening questionnaire comprising 30 items. This instrument does not provide an overall score of disability and is not a graded or rating instrument. Instead, it is a screening tool designed to draw attention to the presence of NMS and initiate further investigation. In this article, we present the results from an international pilot study assessing feasibility, validity, and acceptability of a nonmotor questionnaire (NMSQuest). Data from 123 PD patients and 96 controls were analyzed. NMS were highly significantly more prevalent in PD compared to controls (PD NMS, median = 9.0, mean = 9.5 vs. control NMS, median = 5.5, mean = 4.0; Mann-Whitney, Kruskal-Wallis, and t test, P < 0.0001), with PD patients reporting at least 10 different NMS on average per patient. In PD, NMS were highly significantly more prevalent across all disease stages and the number of symptoms correlated significantly with advancing disease and duration of disease. Furthermore, frequently, problems such as diplopia, dribbling, apathy, blues, taste and smell problems were never previously disclosed to the health professionals.

Construal Levels and Self-Control

Abstract: The authors propose that self-control involves making decisions and behaving in a manner consistent with high-level versus low-level construals of a situation. Activation of high-level construals (which capture global, superordinate, primary features of an event) should lead to greater self-control than activation of low-level construals (which capture local, subordinate, secondary features). In 6 experiments using 3 different techniques, the authors manipulated construal levels and assessed their effects on self-control and underlying psychological processes. High-level construals led to decreased preferences for immediate over delayed outcomes, greater physical endurance, stronger intentions to exert selfcontrol, and less positive evaluations of temptations that undermine self-control. These results support a construal-level analysis of self-control.

Burnout and risk of cardiovascular disease : Evidence, possible causal paths, and promising research directions

Abstract: Burnout is characterized by emotional exhaustion, physical fatigue, and cognitive weariness, resulting from prolonged exposure to work-related stress. The authors review the accumulated evidence suggesting that burnout and the related concept of vital exhaustion are associated with increased risk of cardiovascular disease and cardiovascular-related events. The authors present evidence supporting several potential mechanisms linking burnout with ill health, including the metabolic syndrome, dysregulation of the hypothalamic-pituitary-adrenal axis along with sympathetic nervous system activation, sleep disturbances, systemic inflammation, impaired immunity functions, blood coagulation and fibrinolysis, and poor health behaviors. The association of burnout and vital exhaustion with these disease mediators suggests that their impact on health may be more extensive than currently indicated.

Behavioral treatment of bedtime problems and night wakings in infants and young children.

Abstract: This paper reviews the evidence regarding the effi cacy of be- havioral treatments for bedtime problems and night wakings in young children. It is based on a review of 52 treatment studies by a task force appointed by the American Academy of Sleep Medicine to develop prac- tice parameters on behavioral treatments for the clinical management of bedtime problems and night wakings in young children. The fi ndings in- dicate that behavioral therapies produce reliable and durable changes. Across all studies, 94% report that behavioral interventions were effi ca- cious, with over 80% of children treated demonstrating clinically signifi - cant improvement that was maintained for 3 to 6 months. In particular, empirical evidence from controlled group studies utilizing Sackett criteria for evidence-based treatment provides strong support for unmodifi ed ex- tinction and preventive parent education. In addition, support is provided for graduated extinction, bedtime fading/positive routines, and scheduled awakenings. Additional research is needed to examine delivery methods of treatment, longer-term effi cacy, and the role of pharmacological agents. Furthermore, pediatric sleep researchers are strongly encouraged to de- velop standardized diagnostic criteria and more objective measures, and to come to a consensus on critical outcome variables.

Chromatin relaxation in response to DNA double-strand breaks is modulated by a novel ATM- and KAP-1 dependent pathway

Abstract: The cellular DNA-damage response is a signaling network that is vigorously activated by cytotoxic DNA lesions, such as double-strand breaks (DSBs)1. The DSB response is mobilized by the nuclear protein kinase ATM, which modulates this process by phosphorylating key players in these pathways2. A long-standing question in this field is whether DSB formation affects chromatin condensation. Here, we show that DSB formation is followed by ATM-dependent chromatin relaxation. ATM's effector in this pathway is the protein KRAB-associated protein (KAP-1, also known as TIF1β, KRIP-1 or TRIM28), previously known as a corepressor of gene transcription3,4. In response to DSB induction, KAP-1 is phosphorylated in an ATM-dependent manner on Ser 824. KAP-1 is phosphorylated exclusively at the damage sites, from which phosphorylated KAP-1 spreads rapidly throughout the chromatin. Ablation of the phosphorylation site of KAP-1 leads to loss of DSB-induced chromatin decondensation and renders the cells hypersensitive to DSB-inducing agents. Knocking down KAP-1, or mimicking a constitutive phosphorylation of this protein, leads to constitutive chromatin relaxation. These results suggest that chromatin relaxation is a fundamental pathway in the DNA-damage response and identify its primary mediators.

The two young star disks in the central parsec of the galaxy: properties, dynamics and formation

Abstract: We report the definite spectroscopic identification of 40 OB supergiants, giants and main sequence stars in the central parsec of the Galaxy. Detection of their absorption lines have become possible with the high spatial and spectral resolution and sensitivity of the adaptive optics integral Held spectrometer SPIFFI/SINFONI on the ESO VLT. Several of these OB stars appear to be helium and nitrogen rich. Almost all of the 80 massive stars now known in the central parsec (central arcsecond excluded) reside in one of two somewhat thick (|/R 0.14) rotating disks. These stellar disks have fairly sharp inner edges (R 1'') and surface density profiles that scale as R−2. We do not detect any OB stars outside the central 0.5 pc. The majority of the stars in the clockwise system appear to be on almost circular orbits, whereas most of those in the 'counter-clockwise' disk appear to be on eccentric orbits. Based on its stellar surface density distribution and dynamics we propose that IRS 13E is an extremely dense cluster (ρcore 3 × 108M⊙ pc−3), which has formed in the counter-clockwise disk. The stellar contents of both systems are remarkably similar, indicating a common age of 6±2 Myr. The K-band luminosity function of the massive stars suggests a top-heavy mass function and limits the total stellar mass contained in both disks to 1.5 × 104 M⊙. Our data strongly favor in situ star formation from dense gas accretion disks for the two stellar disks. This conclusion is very clear for the clockwise disk and highly plausible for the counter-clockwise system.

Dual‐tasking effects on gait variability: The role of aging, falls, and executive function

Abstract: The objectives of the present study were to test the hypothesis that the dual-tasking effect on gait variability is larger in healthy older adults than it is in healthy young adults; that this effect is larger in idiopathic elderly fallers than it is in healthy older adults; and that the dual-tasking effects on gait variability are correlated with executive function (EF). Young adults and older adults who were classified as fallers and nonfallers were studied. Gait speed, swing time, and swing time variability, a marker of fall risk, were measured during usual walking and during three different dual-tasking conditions. EF and memory were evaluated. When performing dual tasks, all three groups significantly decreased their gait speed. Dual tasking did not affect swing time variability in the young adults and in the nonfallers. Conversely, dual tasking markedly increased swing time variability in the fallers. While memory was similar in fallers and nonfallers, EF was different. The faller-specific response to dual tasking was significantly correlated with tests of EF. These findings demonstrate that dual tasking does not affect the gait variability of elderly nonfallers or young adults. In contrast, dual tasking destabilizes the gait of idiopathic elderly fallers, an effect that appears to be mediated in part by a decline in EF.

The Coral Probiotic Hypothesis

Abstract: Summary Emerging diseases have been responsible for the death of about 30% of corals worldwide during the last 30 years. Coral biologists have predicted that by 2050 most of the world's coral reefs will be destroyed. This prediction is based on the assumption that corals can not adapt rapidly enough to environmental stress-related conditions and emerging diseases. Our recent studies of the Vibrio shiloi/Oculina patagonica model system of the coral bleaching disease indicate that corals can indeed adapt rapidly to changing envi- ronmental conditions by altering their population of symbiotic bacteria. These studies have led us to propose the Coral Probiotic Hypothesis. This hypoth- esis posits that a dynamic relationship exists between symbiotic microorganisms and environmen- tal conditions which brings about the selection of the most advantageous coral holobiont. Changing their microbial partners would allow the corals to adapt to changing environmental conditions more rapidly (days to weeks) than via mutation and selection (many years). An important outcome of the Probiotic Hypothesis would be development of resistance of the coral holobiont to diseases. The following evi- dence supports this hypothesis: (i) Corals contain a large and diverse bacterial population associated with their mucus and tissues; (ii) the coral-associated bacterial population undergoes a rapid change when environmental conditions are altered; and (iii) although lacking an adaptive immune system (no antibodies), corals can develop resistance to pathogens. The Coral Probiotic Hypothesis may help explain the evolutionary success of corals and mod- erate the predictions of their demise.

Modeling cellular machinery through biological network comparison

Abstract: Molecular networks represent the backbone of molecular activity within the cell. Recent studies have taken a comparative approach toward interpreting these networks, contrasting networks of different species and molecular types, and under varying conditions. In this review, we survey the field of comparative biological network analysis and describe its applications to elucidate cellular machinery and to predict protein function and interaction. We highlight the open problems in the field as well as propose some initial mathematical formulations for addressing them. Many of the methodological and conceptual advances that were important for sequence comparison will likely also be important at the network level, including improved search algorithms, techniques for multiple alignment, evolutionary models for similarity scoring and better integration with public databases.

Lattice-based cryptography

Abstract: We describe some of the recent progress on lattice-based cryptography, starting from the seminal work of Ajtai, and ending with some recent constructions of very efficient cryptographic schemes.

Spatial Distance and Mental Construal of Social Events

Abstract: Construal-level theory proposes that increasing the reported spatial distance of events leads individuals to represent the events by their central, abstract, global features (high-level construal) rather than by their peripheral, concrete, local features (low-level construal). Results of two experiments indicated that participants preferred to identify actions as ends rather than as means to a greater extent when these actions occurred at a spatially distant, as opposed to near, location (Study 1), and that they used more abstract language to recall spatially distant events, compared with near events (Study 2). These findings suggest that spatially distant events are associated with high-level construals, and that spatial distance can be conceptualized as a dimension of psychological distance.

A Comparison of the Construct Validity of Two Burnout Measures in Two Groups of Professionals

Abstract: Arie ShiromTel Aviv UniversitySamuel MelamedTel Aviv University and National Institute of Occupational & EnvironmentalHealthThe authors studied certain aspects of the construct validity of the MaslachBurnout Inventory–General Survey (MBI-GS), the most popular measure ofburnout, and that of the Shirom-Melamed Burnout Measure (SMBM). Theseburnout measures were compared with respect to their psychometric char-acteristics and factorial validity in two groups of professionals, humanservice and other professionals (N 196 and 226, respectively), whocompleted questionnaires at work. As hypothesized, the conrmatory factoranalyses supported a two-factor and a three-factor structure invarianceacross the two groups considered for the SMBM and the MBI-GS, respec-tively, with superior t found for the SMBM.

Linguistic Landscape as Symbolic Construction of the Public Space: The Case of Israel.

Abstract: Linguistic landscape (LL) refers to linguistic objects that mark the public space. This paper compares patterns of LL in a variety of homogeneous and mixed Israeli cities, and in East Jerusalem. The groups studied were Israeli Jews, Palestinian Israelis and non-Israeli Palestinians from East Jerusalem, of whom most are not Israeli citizens. The study focused on the degree of visibility on private and public signs of the three major languages of Israel-Hebrew, Arabic and English. This study reveals essentially different LL patterns in Israel's various communities: Hebrew–English signs prevail in Jewish communities; Arabic Hebrew in Israeli–Palestinian communities; Arabic–English in East Jerusalem. Further analyses also evince significant – and different – discrepancies between public and private signs in the localities investigated. All in all, LL items are not faithfully representative of the linguistic repertoire typical of Israel's ethnolinguistic diversity, but rather of those linguistic resources that...

Salient geometric features for partial shape matching and similarity

Abstract: This article introduces a method for partial matching of surfaces represented by triangular meshes. Our method matches surface regions that are numerically and topologically dissimilar, but approximately similar regions. We introduce novel local surface descriptors which efficiently represent the geometry of local regions of the surface. The descriptors are defined independently of the underlying triangulation, and form a compatible representation that allows matching of surfaces with different triangulations. To cope with the combinatorial complexity of partial matching of large meshes, we introduce the abstraction of salient geometric features and present a method to construct them. A salient geometric feature is a compound high-level feature of nontrivial local shapes. We show that a relatively small number of such salient geometric features characterizes the surface well for various similarity applications. Matching salient geometric features is based on indexing rotation-invariant features and a voting scheme accelerated by geometric hashing. We demonstrate the effectiveness of our method with a number of applications, such as computing self-similarity, alignments, and subparts similarity.

Early evolution of the venom system in lizards and snakes

Abstract: Among extant reptiles only two lineages are known to have evolved venom delivery systems, the advanced snakes and helodermatid lizards (Gila Monster and Beaded Lizard). Evolution of the venom system is thought to underlie the impressive radiation of the advanced snakes (2,500 of 3,000 snake species). In contrast, the lizard venom system is thought to be restricted to just two species and to have evolved independently from the snake venom system. Here we report the presence of venom toxins in two additional lizard lineages (Monitor Lizards and Iguania) and show that all lineages possessing toxin-secreting oral glands form a clade, demonstrating a single early origin of the venom system in lizards and snakes. Construction of gland complementary-DNA libraries and phylogenetic analysis of transcripts revealed that nine toxin types are shared between lizards and snakes. Toxinological analyses of venom components from the Lace Monitor Varanus varius showed potent effects on blood pressure and clotting ability, bioactivities associated with a rapid loss of consciousness and extensive bleeding in prey. The iguanian lizard Pogona barbata retains characteristics of the ancestral venom system, namely serial, lobular non-compound venom-secreting glands on both the upper and lower jaws, whereas the advanced snakes and anguimorph lizards (including Monitor Lizards, Gila Monster and Beaded Lizard) have more derived venom systems characterized by the loss of the mandibular (lower) or maxillary (upper) glands. Demonstration that the snakes, iguanians and anguimorphs form a single clade provides overwhelming support for a single, early origin of the venom system in lizards and snakes. These results provide new insights into the evolution of the venom system in squamate reptiles and open new avenues for biomedical research and drug design using hitherto unexplored venom proteins.

The rapid formation of a large rotating disk galaxy three billion years after the Big Bang.

Abstract: Observations and theoretical simulations have established a framework for galaxy formation and evolution in the young Universe. Galaxies formed as baryonic gas cooled at the centres of collapsing dark-matter haloes; mergers of haloes and galaxies then led to the hierarchical build-up of galaxy mass. It remains unclear, however, over what timescales galaxies were assembled and when and how bulges and disks--the primary components of present-day galaxies--were formed. It is also puzzling that the most massive galaxies were more abundant and were forming stars more rapidly at early epochs than expected from models. Here we report high-angular-resolution observations of a representative luminous star-forming galaxy when the Universe was only 20% of its current age. A large and massive rotating protodisk is channelling gas towards a growing central stellar bulge hosting an accreting massive black hole. The high surface densities of gas, the high rate of star formation and the moderately young stellar ages suggest rapid assembly, fragmentation and conversion to stars of an initially very gas-rich protodisk, with no obvious evidence for a major merger.