Repressive gene regulation synchronizes development with cellular metabolism

Metabolic conditions affect the developmental tempo of animals. Developmental gene regulatory networks (GRNs) must therefore synchronize their dynamics with a variable timescale. We find that layered repression of genes couples GRN output with variable metabolism. When repressors of transcription or mRNA and protein stability are lost, fewer errors in Drosophila development occur when metabolism is lowered. We demonstrate the universality of this phenomenon by eliminating the entire microRNA family of repressors and find that development to maturity can be largely rescued when metabolism is reduced. Using a mathematical model that replicates GRN dynamics, we find that lowering metabolism suppresses the emergence of developmental errors by curtailing the influence of auxiliary repressors on GRN output. We experimentally show that gene expression dynamics are less affected by loss of repressors when metabolism is reduced. Thus, layered repression provides robustness through error suppression and may provide an evolutionary route to a shorter reproductive cycle

Statistical analysis of excitation functions for elastic and inelastic scattering of α\alpha-particles on Mg and Si nuclei

The excitation functions for inelastic $\alpha$-scattering leading to the low lying excited states in $^{24}$Mg and $^{28}$Si were measured at $\Theta_{LAB}$ = 170°, 175° and 179° in the LAB energy range 22.75–28.40 MeV. Statistical analysis of these excitation functions and those previously measured for elastic scattering was performed. The direct interaction contribution $\mathit{y}_{D}$ to the reaction studied was obtained from probability distributions of cross sections and from correlation coefficients. Cross correlation coefficients between different reaction channels were calculated

Repressive gene regulation synchronizes development with cellular metabolism

Metabolic conditions affect the developmental tempo of animals. Developmental gene regulatory networks (GRNs) must therefore synchronize their dynamics with a variable timescale. We find that layered repression of genes couples GRN output with variable metabolism. When repressors of transcription or mRNA and protein stability are lost, fewer errors in Drosophila development occur when metabolism is lowered. We demonstrate the universality of this phenomenon by eliminating the entire microRNA family of repressors and find that development to maturity can be largely rescued when metabolism is reduced. Using a mathematical model that replicates GRN dynamics, we find that lowering metabolism suppresses the emergence of developmental errors by curtailing the influence of auxiliary repressors on GRN output. We experimentally show that gene expression dynamics are less affected by loss of repressors when metabolism is reduced. Thus, layered repression provides robustness through error suppression and may provide an evolutionary route to a shorter reproductive cycle

dTip60 HAT Activity Controls Synaptic Bouton Expansion at the Drosophila Neuromuscular Junction

Background: Histone acetylation of chromatin plays a key role in promoting the dynamic transcriptional responses in neurons that influence the neuroplasticity linked to cognitive ability, yet the specific histone acetyltransferases (HATs) that create such epigenetic marks remain to be elucidated. Methods and Findings: Here we use the Drosophila neuromuscular junction (NMJ) as a well-characterized synapse model to identify HATs that control synaptic remodeling and structure. We show that the HAT dTip60 is concentrated both pre and post-synaptically within the NMJ. Presynaptic targeted reduction of dTip60 HAT activity causes a significant increase in synaptic bouton number that specifically affects type Is boutons. The excess boutons show a suppression of the active zone synaptic function marker bruchpilot, suggesting defects in neurotransmission function. Analysis of microtubule organization within these excess boutons using immunohistochemical staining to the microtubule associated protein futsch reveals a significant increase in the rearrangement of microtubule loop architecture that is required for bouton division. Moreover, a-tubulin acetylation levels of microtubules specifically extending into the terminal synaptic boutons are reduced in response to dTip60 HAT reduction. Conclusions: Our results are the first to demonstrate a causative role for the HAT dTip60 in the control of synaptic plasticity that is achieved, at least in part, via regulation of the synaptic microtubule cytoskeleton. These findings have implication

Badanie defektów magnetycznych związków NB₂VSBO₁₀ i NB₆VSB₃O₂₅

Introduction and aim: Two new compounds from the Nb-V-Sb-O system will be scrutinized as possible catalysts, because many compounds from this system has showed promising catalytic properties. Since there is often a direct link between the number of defects and catalytic activity of a compound, these two materials will be investigated by magnetic methods to detect existing defects and to determine their structure and properties. Material and methods:NB2VSBO10and NB6VSB3O25 are relatively new compounds synthesized in Department of Inorganic and Analytical Chemistry, West Pomeranian University of Technology, Szczecin. Two magnetic methods have been used - dc magnetisation and electron paramagnetic resonance (EPR) spectroscopy. Results: Although the nominal valences of metal ions in both compounds suggested non-magnetic properties, very complex magnetic response was registered in both magnetisation and EPR measurements. Non-homogeneous distribution of magnetic ions makes possible formation of different types of spin clusters and strongly interacting magnetic subsystems. Conclusion: NB6VSB3O25 seems to be more promising catalyst than NB2VSBO10 as there are more magnetic defects in this compound.Wstęp i cel: Dwa nowe związki z układu Nb-V-Sb-O będą rozważane jako potencjalne katalizatory, gdyż wiele związków z tego układu wykazuje obiecujące właściwości katalityczne. Ponieważ często pomiędzy ilością defektów a aktywnością katalityczną istnieje zależność proporcjonalna, dwa te związki będą badane metodami magnetycznymi aby wykryć istniejące w nich defekty oraz określić ich strukturę i właściwości. Materiały i metody: NB2VSBO10 and Nb6VSb3O25zostały zsyntezowane stosunkowo niedawno w Katedrze Chemii Nieorganicznej i Analitycznej Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie. Zastosowano dwie metody badania właściwości magnetycznych - stałoprądową magnetyzację i spektroskopii elektronowego rezonansu paramagnetycznego (EPR). Wyniki: Chociaż nominalna wartościowość jonów metali w obu związkach sugeruje brak magnetycznych właściwości, zarejestrowano bardzo złożoną odpowiedź magnetyczną w pomiarach magnetyzacji i EPR. Niejednorodny rozkład jonów magnetycznych powoduje tworzenie się różnego rodzaju klasterów spinowych i silnie oddziaływujących podukładów magnetycznych. Wnioski: NB6VSB3O25wydaje się być bardziej obiecującym katalizatorem niż NB2VSBO10, ponieważ w tym związku jest dużo więcej defektów magnetycznych

Chaotic vibration of an autoparametrical system with the spherical pendulum

In the paper, the dynamics of a three degree of freedom vibratory system with a spherical pendulum in the neighbourhood of internal and external resonance is considered. It has been assumed that the spherical pendulum is suspended to the main body which is then suspended to the element characterized by some elasticity and damping. The system is excited harmonically in the vertical direction. The equation of motion has been solved numerically. The influence of initial conditions on the behaviour of the spherical pendulum is investigated. In this type of the system, one mode of vibration may excite or damp another one, and for different kinds of periodic vibrations there may also appear chaotic vibrations. For characterization of an irregular chaotic response, time histories, bifurcation diagrams, power spectral densities, Poincar´e maps and the maximum Lyapunov exponents have been calculated