Snail2 directly represses cadherin6B during epithelial-to-mesenchymal transitions of the neural crest

The neural crest, a transient population of migratory cells, forms the craniofacial skeleton and peripheral nervous system, among other derivatives in vertebrate embryos. The transcriptional repressor Snail2 is thought to be crucial for the epithelial-to-mesenchymal transition (EMT) that promotes neural crest delamination from the neural tube; however, little is known about its downstream targets. To this end, we depleted avian Snail2 in the premigratory neural crest using morpholino antisense oligonucleotides and examined effects on potential targets by quantitative PCR. Several dorsal neural tube genes were upregulated by alleviating Snail2 repression; moreover, the cell adhesion molecule cadherin6B was derepressed within 30 minutes of blocking Snail2 translation. Examination of the chick cadherin6B genomic sequence reveals that the regulatory region contains three pairs of clustered E boxes, representing putative Snail2 binding sites. Furthermore, in vivo and in vitro biochemical analyses demonstrate that Snail2 directly binds to these sites and regulates cadherin6B transcription. These results are the first to describe a direct target of Snail2 repression in vivo and in the context of the EMT that characterizes neural crest developmen

Infrared spectra of van de Waals complexes of importance in planetary atmospheres

It has been suggested that (CO2)2 and Ar-CO2 are important constituents of the planetary atmospheres of Venus and Mars. Recent results on the laboratory spectroscopy of CO2 containing van der Waals complexes which may be of use in the modeling of the spectra of planetary atmospheres are presented. Sub-Doppler infrared spectra were obtained for (CO2)2, (CO2)3, and rare-gas-CO2 complexes in the vicinity of the CO2 Fermi diad at 2.7 micrometers using a color-center-laser optothermal spectrometer. From the spectroscopic constants the geometries of the complexes have been determined and van der Waals vibrational frequencies have been estimated. The equilibrium configurations are C2h, C3h, and C2v, for (CO2)2, (CO2)3, and the rare-gas-CO2 complexes, respectively. Most of the homogeneous linewidths for the revibrational transitions range from 0.5 to 22 MHz, indicating that predissociation is as much as four orders of magnitude faster than radiative processes for vibrational relaxation in these complexes

Potential solar axion signatures in X-ray observations with the XMM-Newton observatory

The soft X-ray flux produced by solar axions in the Earth's magnetic field is evaluated in the context of ESA's XMM-Newton observatory. Recent calculations of the scattering of axion-conversion X-rays suggest that the sunward magnetosphere could be an observable source of 0.2-10 keV photons. For XMM-Newton, any conversion X-ray intensity will be seasonally modulated by virtue of the changing visibility of the sunward magnetic field region. A simple model of the geomagnetic field is combined with the ephemeris of XMM-Newton to predict the seasonal variation of the conversion X-ray intensity. This model is compared with stacked XMM-Newton blank sky datasets from which point sources have been systematically removed. Remarkably, a seasonally varying X-ray background signal is observed. The EPIC count rates are in the ratio of their X-ray grasps, indicating a non-instrumental, external photon origin, with significances of 11(pn), 4(MOS1) and 5(MOS2) sigma. After examining the constituent observations spatially, temporally and in terms of the cosmic X-ray background, we conclude that this variable signal is consistent with the conversion of solar axions in the Earth's magnetic field. The spectrum is consistent with a solar axion spectrum dominated by bremsstrahlung- and Compton-like processes, i.e. axion-electron coupling dominates over axion-photon coupling and the peak of the axion spectrum is below 1 keV. A value of 2.2e-22 /GeV is derived for the product of the axion-photon and axion-electron coupling constants, for an axion mass in the micro-eV range. Comparisons with limits derived from white dwarf cooling may not be applicable, as these refer to axions in the 0.01 eV range. Preliminary results are given of a search for axion-conversion X-ray lines, in particular the predicted features due to silicon, sulphur and iron in the solar core, and the 14.4 keV transition line from 57Fe.Comment: Accepted for publication in MNRAS. 67 pages total, including 39 figures, 6 table

EvoSuite at the SBST 2016 Tool Competition

EvoSuite is a search-based tool that automatically generates unit tests for Java code. This paper summarizes the results and experiences of EvoSuite's participation at the fourth unit testing competition at SBST 2016, where Evo-Suite achieved the highest overall score

Private API Access and Functional Mocking in Automated Unit Test Generation

Not all object oriented code is easily testable: Dependency objects might be difficult or even impossible to instantiate, and object-oriented encapsulation makes testing potentially simple code difficult if it cannot easily be accessed. When this happens, then developers can resort to mock objects that simulate the complex dependencies, or circumvent object-oriented encapsulation and access private APIs directly through the use of, for example, Java reflection. Can automated unit test generation benefit from these techniques as well? In this paper we investigate this question by extending the EvoSuite unit test generation tool with the ability to directly access private APIs and to create mock objects using the popular Mockito framework. However, care needs to be taken that this does not impact the usefulness of the generated tests: For example, a test accessing a private field could later fail if that field is renamed, even if that renaming is part of a semantics-preserving refactoring. Such a failure would not be revealing a true regression bug, but is a false positive, which wastes the developer's time for investigating and fixing the test. Our experiments on the SF110 and Defects4J benchmarks confirm the anticipated improvements in terms of code coverage and bug finding, but also confirm the existence of false positives. However, by ensuring the test generator only uses mocking and reflection if there is no other way to reach some part of the code, their number remains small

A Memetic Algorithm for whole test suite generation

The generation of unit-level test cases for structural code coverage is a task well-suited to Genetic Algorithms. Method call sequences must be created that construct objects, put them into the right state and then execute uncovered code. However, the generation of primitive values, such as integers and doubles, characters that appear in strings, and arrays of primitive values, are not so straightforward. Often, small local changes are required to drive the value toward the one needed to execute some target structure. However, global searches like Genetic Algorithms tend to make larger changes that are not concentrated on any particular aspect of a test case. In this paper, we extend the Genetic Algorithm behind the EvoSuiTE test generation tool into a Memetic Algorithm, by equipping it with several local search operators. These operators are designed to efficiently optimize primitive values and other aspects of a test suite that allow the search for test cases to function more effectively. We evaluate our operators using a rigorous experimental methodology on over 12,000 Java classes, comprising open source classes of various different kinds, including numerical applications and text processors. Our study shows that increases in branch coverage of up to 53% are possible for an individual class in practice

Unit Test Generation During Software Development: EvoSuite Plugins for Maven, IntelliJ and Jenkins

Different techniques to automatically generate unit tests for object oriented classes have been proposed, but how to integrate these tools into the daily activities of software development is a little investigated question. In this paper, we report on our experience in supporting industrial partners in introducing the EVOSUITE automated JUnit test generation tool in their software development processes. The first step consisted of providing a plugin to the Apache Maven build infrastructure. The move from a research-oriented point-and-click tool to an automated step of the build process has implications on how developers interact with the tool and generated tests, and therefore, we produced a plugin for the popular IntelliJ Integrated Development Environment (IDE). As build automation is a core component of Continuous Integration (CI), we provide a further plugin to the Jenkins CI system, which allows developers to monitor the results of EVOSUITE and integrate generated tests in their source tree. In this paper, we discuss the resulting architecture of the plugins, and the challenges arising when building such plugins. Although the plugins described are targeted for the EVOSUITE tool, they can be adapted and their architecture can be reused for other test generation tools as well