Central Complex Research Articles

The Neuronal Circuit of the Dorsal Circadian Clock Neurons in Drosophila melanogaster.

Drosophila’s dorsal clock neurons (DNs) consist of four clusters (DN1as, DN1ps, DN2s, and DN3s) that largely differ in size. While the DN1as and the DN2s encompass only two neurons, the DN1ps consist of ∼15 neurons, and the DN3s comprise ∼40 neurons per brain hemisphere. In comparison to the well-characterized lateral clock neurons (LNs), the neuroanatomy and function of the DNs are still not clear. Over the past decade, numerous studies have addressed their role in the fly’s circadian system, leading to several sometimes divergent results. Nonetheless, these studies agreed that the DNs are important to fine-tune activity under light and temperature cycles and play essential roles in linking the output from the LNs to downstream neurons that control sleep and metabolism. Here, we used the Flybow system, specific split-GAL4 lines, trans-Tango, and the recently published fly connectome (called hemibrain) to describe the morphology of the DNs in greater detail, including their synaptic connections to other clock and non-clock neurons. We show that some DN groups are largely heterogenous. While certain DNs are strongly connected with the LNs, others are mainly output neurons that signal to circuits downstream of the clock. Among the latter are mushroom body neurons, central complex neurons, tubercle bulb neurons, neurosecretory cells in the pars intercerebralis, and other still unidentified partners. This heterogeneity of the DNs may explain some of the conflicting results previously found about their functionality. Most importantly, we identify two putative novel communication centers of the clock network: one fiber bundle in the superior lateral protocerebrum running toward the anterior optic tubercle and one fiber hub in the posterior lateral protocerebrum. Both are invaded by several DNs and LNs and might play an instrumental role in the clock network.

Dopamine Modulation of Drosophila Ellipsoid Body Neurons, a Nod to the Mammalian Basal Ganglia.

The central complex (CX) is a neural structure located on the midline of the insect brain that has been widely studied in the last few years. Its role in navigation and goal-oriented behaviors resembles those played by the basal ganglia in mammals. However, the neural mechanisms and the neurotransmitters involved in these processes remain unclear. Here, we exploited an in vivo bioluminescence Ca2+ imaging technique to record the activity in targeted neurons of the ellipsoid body (EB). We used different drugs to evoke excitatory Ca2+-responses, depending on the putative neurotransmitter released by their presynaptic inputs, while concomitant dopamine administration was employed to modulate those excitations. By using a genetic approach to knockdown the dopamine 1-like receptors, we showed that different dopamine modulatory effects are likely due to specific receptors expressed by the targeted population of neurons. Altogether, these results provide new data concerning how dopamine modulates and shapes the response of the ellipsoid body neurons. Moreover, they provide important insights regarding the similitude with mammals as far as the role played by dopamine in increasing and stabilizing the response of goal-related information.

Carotenoid Single-Molecular Singlet Fission and the Photoprotection of a Bacteriochlorophyll b-Type Core Light-Harvesting Antenna.

Carotenoid (Car) in photosynthesis plays the major roles of accessary light harvesting and photoprotection, and the underlying structure-function relationship attracts continuing research interests. We have attempted to explore the dynamics of Car triplet excitation (3Car*) in the bacteriochlorophyll b (BChl b)-type light harvesting reaction center complex (LH1-RC) of photosynthetic bacterium Halorhodospira halochloris. We show that the LH1 antenna binds a single Car that was identified as a lycopene derivative. Although the Car is hardly visible in the LH1-RC stationary absorption, it shows up conspicuously in the triplet excitation profile with distinct vibronic features. This and the ultrafast formation of 3Car* on direct photoexcitation of Car unequivocally manifest the unimolecular singlet fission reaction of the Car. Moreover, the Car with even one molecule per complex is found to be rather effective in quenching 3BChl b*. The implications of different 3Car* formation mechanisms are discussed, and the self-photoprotection role of BChl b are proposed for this extremophilic species.

Structural basis for the assembly and quinone transport mechanisms of the dimeric photosynthetic RC\u2013LH1 supercomplex

The reaction center (RC) and light-harvesting complex 1 (LH1) form a RC–LH1 core supercomplex that is vital for the primary reactions of photosynthesis in purple phototrophic bacteria. Some species possess the dimeric RC–LH1 complex with a transmembrane polypeptide PufX, representing the largest photosynthetic complex in anoxygenic phototrophs. However, the details of the architecture and assembly mechanism of the RC–LH1 dimer are unclear. Here we report seven cryo-electron microscopy (cryo-EM) structures of RC–LH1 supercomplexes from Rhodobacter sphaeroides. Our structures reveal that two PufX polypeptides are positioned in the center of the S-shaped RC–LH1 dimer, interlocking association between the components and mediating RC–LH1 dimerization. Moreover, we identify another transmembrane peptide, designated PufY, which is located between the RC and LH1 subunits near the LH1 opening. PufY binds a quinone molecule and prevents LH1 subunits from completely encircling the RC, creating a channel for quinone/quinol exchange. Genetic mutagenesis, cryo-EM structures, and computational simulations provide a mechanistic understanding of the assembly and electron transport pathways of the RC–LH1 dimer and elucidate the roles of individual components in ensuring the structural and functional integrity of the photosynthetic supercomplex.

Asymmetric structure of the native Rhodobacter sphaeroides dimeric LH1\u2013RC complex

Rhodobacter sphaeroides is a model organism in bacterial photosynthesis, and its light-harvesting-reaction center (LH1–RC) complex contains both dimeric and monomeric forms. Here we present cryo-EM structures of the native LH1–RC dimer and an LH1–RC monomer lacking protein-U (ΔU). The native dimer reveals several asymmetric features including the arrangement of its two monomeric components, the structural integrity of protein-U, the overall organization of LH1, and rigidities of the proteins and pigments. PufX plays a critical role in connecting the two monomers in a dimer, with one PufX interacting at its N-terminus with another PufX and an LH1 β-polypeptide in the other monomer. One protein-U was only partially resolved in the dimeric structure, signaling different degrees of disorder in the two monomers. The ΔU LH1–RC monomer was half-moon-shaped and contained 11 α- and 10 β-polypeptides, indicating a critical role for protein-U in controlling the number of αβ-subunits required for dimer assembly and stabilization. These features are discussed in relation to membrane topology and an assembly model proposed for the native dimeric complex.

Compaction history based on porosity, pressure and temperature relation in Central Luconia province, offshore Sarawak

This study investigates the role of porosity in relation to temperature and pressure within Miocene-Pliocene sediments in Central Luconia province. The main objective is to understand the effect on porosity loss within Miocene-Pliocene sediments as part of the compaction of the sediments through time. The methodology involves seismic interpretation of 2D seismic lines and analysis of four wells over the central complex in Central Luconia province. Thick sedimentation was found within the clastic sediments of Cycle VI, indicating major clastic influx from the deltas and onshore of Sarawak during Pliocene. These clastic sediments had become a major source of weight in the offshore basin, inducing compaction within the older formations. Porosity distributions based on the wells showed that Cycle VI had the highest porosity in LH1 well with 33.77% porosity, while porosity within Cycle IV & V limestone showed an average porosity of 22% in all wells. Porosities within Cycle III and Cycle II were observed to be average of 16%. The porosity within the reservoir rock was reduced as the depth increased. This porosity reduction was relatively due to the compaction of the sediments, linked with the changes of pressure and temperature indicated by several evidences found in each well. Overpressure zone affects irregularity of porosity reduction with depth, whereas high temperature promotes diagenetic reaction that causes sudden porosity loss. Nevertheless, a sudden increase in porosity was also observed at the top of Cycle IV & V limestone due to a major drop in the sea level during the Early Late Miocene, which had encouraged the karstification process, inducing secondary porosity. This study has proved that compaction within Miocene-Pliocene sediments is not only related to the loss in porosity, but it involves changes in pressure and temperature regime of sediments and is highly dependent on the natural changes of sea level.

CHD4 is recruited by GATA4 and NKX2-5 to repress noncardiac gene programs in the developing heart.

The nucleosome remodeling and deacetylase (NuRD) complex is one of the central chromatin remodeling complexes that mediates gene repression. NuRD is essential for numerous developmental events, including heart development. Clinical and genetic studies have provided direct evidence for the role of chromodomain helicase DNA-binding protein 4 (CHD4), the catalytic component of NuRD, in congenital heart disease (CHD), including atrial and ventricular septal defects. Furthermore, it has been demonstrated that CHD4 is essential for mammalian cardiomyocyte formation and function. A key unresolved question is how CHD4/NuRD is localized to specific cardiac target genes, as neither CHD4 nor NuRD can directly bind DNA. Here, we coupled a bioinformatics-based approach with mass spectrometry analyses to demonstrate that CHD4 interacts with the core cardiac transcription factors GATA4, NKX2-5, and TBX5 during embryonic heart development. Using transcriptomics and genome-wide occupancy data, we characterized the genomic landscape of GATA4, NKX2-5, and TBX5 repression and defined the direct cardiac gene targets of the GATA4-CHD4, NKX2-5-CHD4, and TBX5-CHD4 complexes. These data were used to identify putative cis-regulatory elements controlled by these complexes. We genetically interrogated two of these silencers in vivo: Acta1 and Myh11 We show that deletion of these silencers leads to inappropriate skeletal and smooth muscle gene misexpression, respectively, in the embryonic heart. These results delineate how CHD4/NuRD is localized to specific cardiac loci and explicates how mutations in the broadly expressed CHD4 protein lead to cardiac-specific disease states.

Isomerization kinetics of bacteriochlorophyll b and bacteriopheophytin b under acidic conditions.

Bacteriochlorophyll (BChl) b has a unique π-conjugation system, in which the bacteriochlorin macrocycle is conjugated with the C8-ethylidene group. This π-system is converted easily to the chlorin macrocycle. However, the effects of the central magnesium in BChl b on this conversion are unclear. In this study, the isomerization kinetics of BChl b and its demetalated pigment, bacteriopheophytin (BPhe) b, was analyzed under weakly acidic conditions. BChl b exhibited faster acid-induced isomerization than BPhe b. These results were attributed to the stabilization of a cationic intermediate, whose C8-ethylidene group is protonated, during the isomerization of BChl b compared to BPhe b because of a difference in the electron densities of the π-conjugation systems between BChl b and BPhe b. High-performance liquid chromatography analyses indicated that BChl b was primarily isomerized to 3-acetyl Chl a, followed by demetalation. The reaction order was due to the slower demetalation kinetics of metallobacteriochlorins than metallochlorins. These results will be helpful for handling unstable BChl b and BPhe b. The reaction properties of BChl b and BPhe b demonstrated here will be helpful for understanding the in vivo formation of BPhe b, which acts as the primary electron acceptor in photosynthetic reaction center complexes in BChl b-containing purple photosynthetic bacteria.

EGFR-mutated advanced lung cancer. Data from a single institution, the Hospital of Leon, in Spain.

10-16% of non-small cell lung cancer (NSCLC) cases have the epidermal growth factor receptor (EGFR) amplified and/or mutated. Studies show that EGFR tyrosine kinase inhibitors (TKIs) significantly prolong progression-free survival (PFS) in patients with advanced NSCLC compared to those treated with platinum-based chemotherapy (CT) doublets. Our aim is to perform a real-world survival analysis of patients treated with TKI as first-line therapy at the Hospital of Leon (CAULE) in Spain. The impact on global survival rates and responses to clinical and histopathological factors were also analyzed. We retrospectively reviewed patients diagnosed with EGFR-mutated NSCLC who received treatment with EGFR-TKI in the Department of Oncology at the University of Leon Health Center complex between March 2011 and June 2018. Data was analyzed with Kaplan-Meier and Cox regression models to show overall survival (OS), progression-free survival (PFS), and the associated variables. 53 patients were included in the study, 50% (n = 27) were treated with gefitinib, 32% (n = 18) with erlotinib and 10% (n = 6) with afatinib. The median OS and PFS were 27.7 months (95% CI: 21-33.8 months) and 18 months (95% CI 14.25-21.89 months), respectively. The variables associated with OS and with PFS were exon19 deletion as a protective factor and presence of extrathoracic metastasis as a risk factor. The most frequent adverse effects were rash, diarrhea, asthenia, and conjunctivitis. Real-world analysis of this data confirms that treatment with TKI is beneficial for patients diagnosed with EGFR-mutated NSCLC. Our OS outcomes were similar to those reported in clinical trials.

Public reporting for coronary artery bypass graft surgery: The quest for the optimal scorecard

ObjectiveA number of publicly available rating algorithms are used to assess hospital performance in coronary artery bypass grafting (CABG). However, concerns remain that these algorithms fail to correlate with each other and inadequately capture the case complexity of individual center practices. MethodsComposite star ratings for isolated CABG from the Society of Thoracic Surgeons public reporting database were extracted for 2018-2019. U.S. News & World Report Best Hospitals was used to extract CABG ratings as well as overall cardiology and heart surgery ranking, and the Centers for Medicare & Medicaid Services Hospital Compare was used to extract CABG volume and 30-day mortality. Spearman correlation coefficients were used to assess possible relationships. Expert opinion on risk adjustment and program evaluation was incorporated. ResultsCorrelations between Society of Thoracic Surgeons star rating and U.S. News & World Report overall ranking in cardiology and heart surgery (r = 0.15) and Centers for Medicare & Medicaid Services 30-day mortality (r = −0.27) were poor. Society of Thoracic Surgeons star rating correlated weakly with U.S. News & World Report CABG ratings (r = 0.33) and with Centers for Medicare & Medicaid Services CABG volume (r = 0.32), whereas the latter 2 correlated moderately (r = 0.52) with each other. Of the 75 centers with accredited cardiac surgery training programs, 13 (17%) did not participate in Society of Thoracic Surgeons public reporting. Important gaps were identified in risk assessment, and potential solutions are proposed. ConclusionsCorrelations between current CABG public reporting systems are weak. Further work is needed to refine and standardize CABG rating systems to more adequately capture the scope and complexity of an individual center's clinical practice and to better inform patients.

ANALYSIS OF THE SEISMIC AND IONOSPHERIC EFFECTS OF THE KUDARINSKY EARTHQUAKE ON DECEMBER 9, 2020

According to the data obtained on the equipment of the IEC SB RAS complex monitoring base for hazardous geological processes "Buguldeika" (Shared Research Facilities "Geodynamics and Geochronology" of IEC SB RAS) and Shared Research Facilities "Angara" of ISTP SB RAS an analysis of the characteristics of the Kudarinsky earthquake (09.12.2020) and the behaviour of the ionosphere during this event was carried out. The source parameters of the earthquake were obtained – the seismic moment of the earthquake (M0=3.02·1017 N·m), the moment magnitude (Mw=5.6), the source radius (2.43 km), and the stress drop (1.26 MPa).The analysis of the ionosphere behaviour carried out using GPS/GLONASS receivers did not reveal disturbances caused by the Kudarinsky earthquake, which is most likely due to the relatively small magnitude of this earthquake. An analysis of the observation series related to the Kudarinsky earthquake showed the efficiency of using the Core Facilities Centre equipment and complex monitoring bases for studying seismicity, which is the most dangerous natural process for the Baikal region.

Dopamine 1-like receptor in the brain holds key to zombie cockroach transformation

It's a grizzly scene; a female jewel wasp (Ampulex compressa) wrestles an American cockroach (Periplaneta americana) to the ground. But what follows is a masterclass in neurosurgery. Following a precise sting aimed at the first bundle of nerves in the body, immobilising the cockroach's front legs, the wasp then deals its coup de grâce through the neck, aiming a second sting directly into a region of the brain known as the central complex, transforming the cockroach into a zombie-incubator for her egg. ‘Biochemical analysis of the venom shows the presence of [the neurotransmitter] dopamine’, says Frederic Libersat from Ben Gurion University of the Negev, Israel, adding that the neurotransmitter is entirely responsible for the initial stage of the transformation, when the cockroach begins to groom obsessively. However, it wasn't clear which of the two possible dopamine receptors (D1-like receptor or D2-like receptor) in the cockroach brain could be mediating the neurotransmitter's gruesome effect. So, Stefania Nordio (Ben Gurion University of the Negev) and Libersat set about bamboozling the cockroach's nervous system with drugs to identify which receptors are responsible for the deadly transformation that robs the insects of free will.‘These experiments require some technical skill and lots of practice’, says Libersat, who chose a series of drugs that selectively activate or disable the dopamine receptors in the cockroach's brain, to identify which receptors are targeted by the wasp's mind-bending venom. Injecting a drug that specifically activates the D1-like receptor into the central complex, Nordio and Libersat watched the insects as they ceased ambling around the arena and settled down to grooming, as if they'd been stung. However, the cockroaches that were injected with a drug that activates the D2-like receptor did not behave as if they had been stung and continued wandering around. The D1 receptor is the key receptor that controls the cockroaches’ urge to settle down and groom.The duo then injected cockroaches with a drug that blocks both dopamine receptors and waited a few hours before releasing jewel wasps in with the cockroaches to see if the drugs could prevent the wasps’ venom cocktail from disabling the cockroaches. Sure enough, the cockroaches were protected from the wasps’ stings, continuing to stroll around the arena even after being stung 6 h after the drug was applied. In addition, selectively blocking the D2 receptor with a drug, leaving the D1 receptor responsive, left the cockroaches vulnerable to the wasps’ stings, while the cockroaches treated to prevent the D1 receptor from responding to the toxic venom continued moving around the arena unaffected, providing more evidence that the D1 receptor is essential for initiating the transformation.Finally, the team tested the protective powers of the dopamine receptor blocking drugs to find out whether the dopamine receptors are targeted by wasp venom later in the cockroach's zombie transformation. Treating the cockroaches with a drug before letting the wasps loose, the team kept an eye on the stung insects for 2 days to find out whether they lost the ability to flee. Initially the cockroaches were unable to make a run for it. However, a day after being stung, when most cockroaches can no longer walk independently, the cockroaches that had been pre-treated with the drug had regained their free will and could make a dash for it; the wasp venom was targeting both dopamine receptors to rob the zombies of the ability to walk independently.So, jewel wasp venom specifically targets the D1 receptors in the cockroach brain to trigger the first stage of the zombie transformation, while both receptors rob the cockroach of the ability to walk unaided as the mind-altering venom takes hold.

Parasitoid wasp venom manipulates host innate behavior via subtype-specific dopamine receptor activation.

ABSTRACTThe subjugation strategy employed by the jewel wasp is unique in that it manipulates the behavior of its host, the American cockroach, rather than inducing outright paralysis. Upon envenomation directly into the central complex (CX), a command center in the brain for motor behavior, the stung cockroach initially engages in intense grooming behavior, then falls into a lethargic sleep-like state referred to as hypokinesia. Behavioral changes evoked by the sting are due at least in part to the presence of the neurotransmitter dopamine in the venom. In insects, dopamine receptors are classified as two families, the D1-like and the D2-like receptors. However, specific roles played by dopamine receptor subtypes in venom-induced behavioral manipulation by the jewel wasp remain largely unknown. In the present study, we used a pharmacological approach to investigate roles of D1-like and D2-like receptors in behaviors exhibited by stung cockroaches, focusing on grooming. Specifically, we assessed behavioral outcomes of focal CX injections of dopamine receptor agonists and antagonists. Both specific and non-specific compounds were used. Our results strongly implicate D1-like dopamine receptors in venom-induced grooming. Regarding induction of hypokinesia, our findings demonstrate that dopamine signaling is necessary for induction of long-lasting hypokinesia caused by brain envenomation.

Identification of metal-sensitive structural changes in the Ca2+-binding photocomplex from Thermochromatium tepidum by isotope-edited vibrational spectroscopy.

Calcium ions play a dual role in expanding the spectral diversity and structural stability of photocomplexes from several Ca2+-requiring purple sulfur phototrophic bacteria. Here, metal-sensitive structural changes in the isotopically labeled light-harvesting 1 reaction center (LH1-RC) complexes from the thermophilic purple sulfur bacterium Thermochromatium (Tch.) tepidum were investigated by perfusion-induced attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The ATR-FTIR difference spectra induced by exchanges between native Ca2+ and exogenous Ba2+ exhibited interconvertible structural and/or conformational changes in the metal binding sites at the LH1 C-terminal region. Most of the characteristic Ba2+/Ca2+ difference bands were detected even when only Ca ions were removed from the LH1-RC complexes, strongly indicating the pivotal roles of Ca2+ in maintaining the LH1-RC structure of Tch. tepidum. Upon 15N-, 13C- or 2H-labeling, the LH1-RC complexes exhibited characteristic 15N/14N-, 13C/12C-, or 2H/1H-isotopic shifts for the Ba2+/Ca2+ difference bands. Some of the 15N/14N or 13C/12C bands were also sensitive to further 2H-labelings. Given the band frequencies and their isotopic shifts along with the structural information of the Tch. tepidum LH1-RC complexes, metal-sensitive FTIR bands were tentatively identified to the vibrational modes of the polypeptide main chains and side chains comprising the metal binding sites. Furthermore, important new IR marker bands highly sensitive to the LH1 BChl a conformation in the Ca2+-bound states were revealed based on both ATR-FTIR and near-infrared Raman analyses. The present approach provides valuable insights concerning the dynamic equilibrium between the Ca2+- and Ba2+-bound states statically resolved by x-ray crystallography.

Centrifuge modelling of root–soil interaction of laterally loaded trees under different loading conditions

Understanding the stability of trees under lateral loads arising from natural hazards (e.g. extreme weather and debris flows) is important, as fallen trees can become a potential threat to life and infrastructure. Two 1 : 20 scale three-dimensional printed analogue root system models, with architectures from field-surveyed root architecture data, were used to simulate the push-over behaviour of trees in silty sand under different conditions in the centrifuge. The peak overturning moments obtained were verified against data from field winching tests. Horizontal roots orientated in the loading direction and the central taproot complex contributed most to the overturning resistance. Increasing soil matric suction due to a lowering of the water table, increasing the loading rate and considering the presence of the fine root fraction all resulted in higher moment capacity and rotational stiffness of the root systems. The overturning behaviour was ductile in fully saturated soil and more brittle in partially saturated cases, with more root breakages in the windward horizontal roots and the taproot complex in the latter. These results suggest that it is important to measure the groundwater conditions when conducting winching tests and demonstrate a connection between soil effective stress, total root breakage area and peak moment resistance.

U‐Pb dating of zircon and monazite from the uplifted Variscan crystalline basement of the Ries impact crater

AbstractImpact crater central peaks and peak ring complexes are important exploration targets for future missions to other planetary bodies, because they provide access to material uplifted from lower crustal levels. Material exposed there could also provide chronological constraints on crater formation events. Therefore, it is essential to understand if uplifted peak material preserves the chronological records of igneous and metamorphic protolith crustal rocks, or if such records are reset during impact events. To investigate this issue, we collected shocked gneiss and granite samples from uplifted crystalline basement megablocks in the 24 km diameter Ries impact crater in Germany, which is dated at ~14.8 Ma. Petrographic observations, electron beam imaging, and Raman spectroscopy suggest that these samples record the peak pressures of ~10–15 GPa. In situ U‐Pb dating shows that monazite U‐Pb systematics have not been affected by the Ries impact, as gneisses and granites yielded monazite U‐Pb dates of ~370 and 330 Ma, consistent with known Variscan metamorphic and magmatic events. The U‐Pb systematics of some zircon grains yielded U‐Pb dates of approximately 5–10 Ma, which is younger than the age of the Ries impact event. These young dates correspond to U‐rich metamict domains and may reflect recent Pb loss and/or U‐gain during postimpact hydrothermal alteration or weathering. These observations indicate that dating uplifted crystalline material in impact craters on other bodies might provide useful petrological and chronological constraints on the underlying target rocks rather than directly dating impact events, for which sampling impact melt and impact melt‐bearing lithologies should remain the primary target.

Online learning for orientation estimation during translation in an insect ring attractor network

Insect neural systems are a promising source of inspiration for new navigation algorithms, especially on low size, weight, and power platforms. There have been unprecedented recent neuroscience breakthroughs with Drosophila in behavioral and neural imaging experiments as well as the mapping of detailed connectivity of neural structures. General mechanisms for learning orientation in the central complex (CX) of Drosophila have been investigated previously; however, it is unclear how these underlying mechanisms extend to cases where there is translation through an environment (beyond only rotation), which is critical for navigation in robotic systems. Here, we develop a CX neural connectivity-constrained model that performs sensor fusion, as well as unsupervised learning of visual features for path integration; we demonstrate the viability of this circuit for use in robotic systems in simulated and physical environments. Furthermore, we propose a theoretical understanding of how distributed online unsupervised network weight modification can be leveraged for learning in a trajectory through an environment by minimizing orientation estimation error. Overall, our results may enable a new class of CX-derived low power robotic navigation algorithms and lead to testable predictions to inform future neuroscience experiments.

A conditional GABAergic synaptic vesicle marker for Drosophila

BackgroundThroughout the animal kingdom, GABA is the principal inhibitory neurotransmitter of the nervous system. It is essential for maintaining the homeostatic balance between excitation and inhibition required for the brain to operate normally. Identification of GABAergic neurons and their GABA release sites are thus essential for understanding how the brain regulates the excitability of neurons and the activity of neural circuits responsible for numerous aspects of brain function including information processing, locomotion, learning, memory, and synaptic plasticity, among others. New methodSince the structure and features of GABA synapses are critical to understanding their function within specific neural circuits of interest, here we developed and characterized a conditional marker of GABAergic synaptic vesicles for Drosophila, 9XV5-vGAT. Results9XV5-vGAT is validated for conditionality of expression, specificity for localization to synaptic vesicles, specificity for expression in GABAergic neurons, and functionality. Its utility for GABAergic neurotransmitter phenotyping and identification of GABA release sites was verified for ellipsoid body neurons of the central complex. In combination with previously reported conditional SV markers for acetylcholine and glutamate, 9XV5-vGAT was used to demonstrate fast neurotransmitter phenotyping of subesophageal ganglion neurons. Comparison with existing methodsThis method is an alternative to single cell transcriptomics for neurotransmitter phenotyping and can be applied to any neurons of interest represented by a binary transcription system driver. ConclusionA conditional GABAergic synaptic vesicle marker has been developed and validated for GABA neurotransmitter phenotyping and subcellular localization of GABAergic synaptic vesicles.

Rubredoxin 1 Is Required for Formation of the Functional Photosystem II Core Complex in Arabidopsis thaliana.

Chloroplast thylakoid protein rubredoxin 1 (RBD1) in Chlamydomonas and its cyanobacterial homolog RubA contain a rubredoxin domain. These proteins have been proposed to participate in the assembly of photosystem II (PSII) at early stages. However, the effects of inactivation of RBD1 on PSII assembly in higher plants are largely unclear. Here, we characterized an Arabidopsis rbd1 mutant in detail. A drastic reduction of intact PSII complex but relatively higher levels of assembly intermediates including PSII RC, pre-CP47, and pre-CP43 were found in rbd1. Polysome association and ribosome profiling revealed that ribosome recruitment of psbA mRNA is specifically reduced. Consistently, in vivo protein pulse-chase labeling showed that the rate of D1/pD1 synthesis is significantly reduced in rbd1 compared with WT. Moreover, newly synthesized mature D1 and pD1/D2 can assemble into the PSII reaction center (RC) complex but further formation of larger PSII complexes is nearly totally blocked in rbd1. Our data imply that RBD1 is not only required for the formation of a functional PSII core complex during the early stages of PSII assembly but may also be involved in the translation of D1 in higher plants.

Geophysical Evaluation of Central Nigeria Earth Tremor Activities using High Resolution Airborne Magnetic Data

The aim of this study is to investigate the actual causes of earth tremors in Central Nigeria using geophysical technique. Since 1933 till date (over 88 years), small to moderate magnitude earthquakes have either been observed or instrumentally recorded in Nigeria. However, the specific causes of the intra plate earthquakes in Nigeria is still not well known. In this study therefore, a high-resolution aeromagnetic data analysis was performed to evaluate the various theories proposed as the causes of tremor activity in central Nigeria with a view to ascertaining the actual causes of earthquakes in the West African country that lies on a stable crust. The total magnetic intensity data acquired from the Nigerian Geological Survey Agency (NGSA) in the Central Basement complex of Nigeria, was processed and filtered using the tilt derivative, lineament analysis, and advanced Analytic Signal- Hilbert Solution filter. To define the trends of both major and minor structure, a lineament plot was extracted and plotted. The analysis revealed a dominant NE-SW and NW-SE trending structure that is distributed throughout the study area. The regional North Atlantic Romanche fault system, which extends from the offshore (Niger Delta) into the continental crust, was mapped and is thought to extend from Gwagwalada in the study area's south, through Gwarinpa and Mpape, to Kwoi, and beyond Kafanchan.Findings from our study have indicated that, areas prone to Earth tremors are linked to the Romanche fault by numerous NE-SW and NW-SE faults that act as conduits for seismic energy that causes tremor. Using lineament density analysis, tremor active areas have been interpreted to be highly deformed; thus, seismic energy induced into the environment would result in tremors. This study demonstrates that the regional North Atlantic Romanche fault system is the primary source of seismic energy that causes the earth tremors in central Nigeria.