534 research outputs found
DESCRIPTION OF THE LIFE STAGES OF MACROGLENES PENETRANS (KIRBY) (HYMENOPTERA: CHALCIDOIDEA, PTEROMALIDAE), A PARASITOID OF THE WHEAT MIDGE, SITODIPLOSIS MOSELLANA (GÉHIN) (DIPTERA: CECIDOMYIIDAE)
The life stages of Macroglenes penetrans (Kirby), an egg-larval parasitoid of the wheat midge, Sitodiplosis mosellana (Géhin), are described. The mean length and width, respectively, of 25 parasitoid eggs deposited in host eggs were 0.105 ± 0.008 (SD) mm and 0.041 ± 0.006 mm. Mature oocytes were 0.131 ± 0.008 mm long by 0.038 ± 0.004 mm wide, slightly larger than laid eggs. A frequency distribution of head width (HW) indicated two larval instars during the feeding period. During development, the HW of the first instar remains almost constant at about 0.03 mm whereas body length (BL) increases from about 0.15 to about 0.3 mm. Both HW and BL increase in the second instar from about 0.15 and 0.49 to 0.34 and 1.05 mm, respectively, for mature larvae. The third instar does not feed and is characterized by hook-like "pseudomandibles" and four incurving spines on the terminal segment. The pupa is adectious exarate. Adults are about 2 mm long, shiny bluish-black, and have translucent wings. Males have prominent rust-coloured eyes; eyes of females are less prominent and fuscou
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Establishment of a Developmental Compartment Requires Interactions between Three Synergistic Cis-regulatory Modules
The subdivision of cell populations in compartments is a key event during animal development. In Drosophila, the gene apterous (ap) divides the wing imaginal disc in dorsal vs ventral cell lineages and is required for wing formation. ap function as a dorsal selector gene has been extensively studied. However, the regulation of its expression during wing development is poorly understood. In this study, we analyzed ap transcriptional regulation at the endogenous locus and identified three cis-regulatory modules (CRMs) essential for wing development. Only when the three CRMs are combined, robust ap expression is obtained. In addition, we genetically and molecularly analyzed the trans-factors that regulate these CRMs. Our results propose a three-step mechanism for the cell lineage compartment expression of ap that includes initial activation, positive autoregulation and Trithorax-mediated maintenance through separable CRMsThis study was supported by a grant from the MINECO to CE (No. BFU2012-34353) and grants from the Kantons Basel-Stadt and Basel-Land, and the Swiss National Science Foundation to MA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip
Towards Improved Quantum Simulations and Sensing with Trapped 2D Ion Crystals via Parametric Amplification
Improving coherence is a fundamental challenge in quantum simulation and
sensing experiments with trapped ions. Here we discuss, experimentally
demonstrate, and estimate the potential impacts of two different protocols that
enhance, through motional parametric excitation, the coherent spin-motion
coupling of ions obtained with a spin-dependent force. The experiments are
performed on 2D crystal arrays of approximately one hundred Be ions
confined in a Penning trap. By modulating the trapping potential at close to
twice the center-of-mass mode frequency, we squeeze the motional mode and
enhance the spin-motion coupling while maintaining spin coherence. With a
stroboscopic protocol, we measure dB of motional squeezing below
the ground-state motion, from which theory predicts a dB enhancement in
the sensitivity for measuring small displacements using a recently demonstrated
protocol [Science , 673 (2021)]. With a continuous squeezing
protocol, we measure and accurately calibrate the parametric coupling strength.
Theory suggests this protocol can be used to improve quantum spin squeezing,
limited in our system by off-resonant light scatter. We illustrate numerically
the trade-offs between strong parametric amplification and motional dephasing
in the form of center-of-mass frequency fluctuations for improving quantum spin
squeezing in our set-up.Comment: 11 pages, 6 figure
Comparison of Spontaneous Emission in Trapped Ion Multiqubit Gates at High Magnetic Fields
Penning traps have been used for performing quantum simulations and sensing
with hundreds of ions and provide a promising route toward scaling up trapped
ion quantum platforms because of the ability to trap and control up to
thousands of ions in 2D and 3D crystals. A leading source of decoherence in
laser-based multiqubit operations on trapped ions is off-resonant spontaneous
emission. While many trapped ion quantum computers or simulators utilize clock
qubits, other systems rely on Zeeman qubits, which require a more complex
calculation of this decoherence. We examine theoretically the impacts of
spontaneous emission on quantum gates performed with trapped ions in a high
magnetic field. We consider two types of gates -- light-shift and
Molmer-Sorensen gates -- and compare the decoherence errors in each. We also
compare different detunings, polarizations, and required intensities of the
laser beams used to drive the gates. We show that both gates can have similar
performance at their optimal operating conditions and examine the experimental
feasibility of various operating points. By examining the magnetic field
dependence of each gate, we demonstrate that when the state fine structure
splitting is large compared to the Zeeman splittings, the theoretical
performance of the Molmer-Sorensen gate is significantly better than that of
the light-shift gate. Additionally, for the light-shift gate, we make an
approximate comparison between the fidelities that can be achieved at high
fields with the fidelities of state-of-the-art two-qubit trapped ion quantum
gates. We show that, with regard to spontaneous emission, the achievable
infidelity of our current configuration is about an order of magnitude larger
than that of the best low-field gates, but we also discuss alternative
configurations with potential error rates that are comparable with
state-of-the-art trapped ion gates.Comment: Main text: 19 pages, 13 figures, Appendix: 7 pages, 1 figure, updated
to improve presentatio
Mechanical Stress Inference for Two Dimensional Cell Arrays
Many morphogenetic processes involve mechanical rearrangement of epithelial
tissues that is driven by precisely regulated cytoskeletal forces and cell
adhesion. The mechanical state of the cell and intercellular adhesion are not
only the targets of regulation, but are themselves likely signals that
coordinate developmental process. Yet, because it is difficult to directly
measure mechanical stress {\it in vivo} on sub-cellular scale, little is
understood about the role of mechanics of development. Here we present an
alternative approach which takes advantage of the recent progress in live
imaging of morphogenetic processes and uses computational analysis of high
resolution images of epithelial tissues to infer relative magnitude of forces
acting within and between cells. We model intracellular stress in terms of bulk
pressure and interfacial tension, allowing these parameters to vary from cell
to cell and from interface to interface. Assuming that epithelial cell layers
are close to mechanical equilibrium, we use the observed geometry of the two
dimensional cell array to infer interfacial tensions and intracellular
pressures. Here we present the mathematical formulation of the proposed
Mechanical Inverse method and apply it to the analysis of epithelial cell
layers observed at the onset of ventral furrow formation in the {\it
Drosophila} embryo and in the process of hair-cell determination in the avian
cochlea. The analysis reveals mechanical anisotropy in the former process and
mechanical heterogeneity, correlated with cell differentiation, in the latter
process. The method opens a way for quantitative and detailed experimental
tests of models of cell and tissue mechanics
The mating-specific Gα interacts with a kinesin-14 and regulates pheromone-induced nuclear migration in budding yeast
As a budding yeast cell elongates toward its mating partner, cytoplasmic microtubules connect the nucleus to the cell cortex at the growth tip. The Kar3 kinesin-like motor protein is then thought to stimulate plus-end depolymerization of these microtubules, thus drawing the nucleus closer to the site where cell fusion and karyogamy will occur. Here, we show that pheromone stimulates a microtubule-independent interaction between Kar3 and the mating-specific Gα protein Gpa1 and that Gpa1 affects both microtubule orientation and cortical contact. The membrane localization of Gpa1 was found to polarize early in the mating response, at about the same time that the microtubules begin to attach to the incipient growth site. In the absence of Gpa1, microtubules lose contact with the cortex upon shrinking and Kar3 is improperly localized, suggesting that Gpa1 is a cortical anchor for Kar3. We infer that Gpa1 serves as a positional determinant for Kar3-bound microtubule plus ends during mating. © 2009 by The American Society for Cell Biology
ESPRESSO: The next European exoplanet hunter
The acronym ESPRESSO stems for Echelle SPectrograph for Rocky Exoplanets and
Stable Spectroscopic Observations; this instrument will be the next VLT high
resolution spectrograph. The spectrograph will be installed at the
Combined-Coud\'e Laboratory of the VLT and linked to the four 8.2 m Unit
Telescopes (UT) through four optical Coud\'e trains. ESPRESSO will combine
efficiency and extreme spectroscopic precision. ESPRESSO is foreseen to achieve
a gain of two magnitudes with respect to its predecessor HARPS, and to improve
the instrumental radial-velocity precision to reach the 10 cm/s level. It can
be operated either with a single UT or with up to four UTs, enabling an
additional gain in the latter mode. The incoherent combination of four
telescopes and the extreme precision requirements called for many innovative
design solutions while ensuring the technical heritage of the successful HARPS
experience. ESPRESSO will allow to explore new frontiers in most domains of
astrophysics that require precision and sensitivity. The main scientific
drivers are the search and characterization of rocky exoplanets in the
habitable zone of quiet, nearby G to M-dwarfs and the analysis of the
variability of fundamental physical constants. The project passed the final
design review in May 2013 and entered the manufacturing phase. ESPRESSO will be
installed at the Paranal Observatory in 2016 and its operation is planned to
start by the end of the same year.Comment: 12 pages, figures included, accepted for publication in Astron. Nach
Temporal Progression of Fatty Acids in Preterm and Term Human Milk of Mothers from Switzerland.
We longitudinally compared fatty acids (FA) from human milk (HM) of mothers delivering term and preterm infants. HM was collected for 4 months postpartum at 12 time points for preterm and for 2 months postpartum at 8 time points for term group. Samples were collected from the first feed of the morning, and single breast was fully expressed. FA were analyzed by gas chromatography coupled with flame ionization detector. Oleic, palmitic and linoleic acids were the most abundant FA across lactation and in both groups. Preterm colostrum contained significantly (p < 0.05) higher 8:0, 10:0, 12:0, sum medium chain fatty acids (MCFA), 18:3 n-3 FA compared to term counterparts. Preterm mature milk contained significantly higher 12:0, 14:0, 18:2 n-6, sum saturated fatty acids (SFA), and sum MCFA. We did not observe any significant differences between the preterm and term groups for docosahexaenoic acid, arachidonic acid and eicosapentaenoic acid at any stage of lactation. Overall, preterm milk was higher for SFA with a major contribution from MCFA and higher in 18:2 n-6. These observational differences needs to be studied further for their implications on preterm developmental outcomes and on fortification strategies of either mothers' own milk or donor human milk
Regulation of BMP4/Dpp retrotranslocation and signaling by deglycosylation.
During endoplasmic reticulum-associated degradation (ERAD), the cytoplasmic enzyme N-glycanase 1 (NGLY1) is proposed to remove N-glycans from misfolded N-glycoproteins after their retrotranslocation from the ER to the cytosol. We previously reported that NGLY1 regulates Drosophila BMP signaling in a tissue-specific manner (Galeone et al., 2017). Here, we establish the Drosophila Dpp and its mouse ortholog BMP4 as biologically relevant targets of NGLY1 and find, unexpectedly, that NGLY1-mediated deglycosylation of misfolded BMP4 is required for its retrotranslocation. Accumulation of misfolded BMP4 in the ER results in ER stress and prompts the ER recruitment of NGLY1. The ER-associated NGLY1 then deglycosylates misfolded BMP4 molecules to promote their retrotranslocation and proteasomal degradation, thereby allowing properly-folded BMP4 molecules to proceed through the secretory pathway and activate signaling in other cells. Our study redefines the role of NGLY1 during ERAD and suggests that impaired BMP4 signaling might underlie some of the NGLY1 deficiency patient phenotypes
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