A Catalog of GAL4 Drivers for Labeling and Manipulating Circadian Clock Neurons in Drosophila melanogaster

Daily rhythms of physiology, metabolism, and behavior are orchestrated by a central circadian clock. In mice, this clock is coordinated by the suprachiasmatic nucleus, which consists of 20,000 neurons, making it challenging to characterize individual neurons. In Drosophila, the clock is controlled by only 150 clock neurons that distribute across the fly's brain. Here, we describe a comprehensive set of genetic drivers to facilitate individual characterization of Drosophila clock neurons. We screened GAL4 lines that were obtained from Drosophila stock centers and identified 63 lines that exhibit expression in subsets of central clock neurons. Furthermore, we generated split-GAL4 lines that exhibit specific expression in subsets of clock neurons such as the 2 DN2 neurons and the 6 LPN neurons. Together with existing driver lines, these newly identified ones are versatile tools that will facilitate a better understanding of the Drosophila central circadian clock

Overexpression of β1-chain-containing laminins in capillary basement membranes of human breast cancer and its metastases

Manabu Fujita, Natalya M Khazenzon, Shikha Bose, Kiyotoshi Sekiguchi, Takako Sasaki, William G Carter, Alexander V Ljubimov, Keith L Black and Julia Y Ljubimova, "Overexpression of β1-chain-containing laminins in capillary basement membranes of human breast cancer and its metastases", Breast Cancer Research, 7, R411-R421, BioMed Central, 200

The CCHamide1 Neuropeptide Expressed in the Anterior Dorsal Neuron 1 Conveys a Circadian Signal to the Ventral Lateral Neurons in Drosophila melanogaster

The fruit fly Drosophila melanogaster possesses approximately 150 brain clock neurons that control circadian behavioral rhythms. Even though individual clock neurons have self-sustaining oscillators, they interact and synchronize with each other through a network. However, little is known regarding the factors responsible for these network interactions. In this study, we investigated the role of CCHamide1 (CCHa1), a neuropeptide expressed in the anterior dorsal neuron 1 (DN1a), in intercellular communication of the clock neurons. We observed that CCHa1 connects the DN1a clock neurons to the ventral lateral clock neurons (LNv) via the CCHa1 receptor, which is a homolog of the gastrin-releasing peptide receptor playing a role in circadian intercellular communications in mammals. CCHa1 knockout or knockdown flies have a generally low activity level with a special reduction of morning activity. In addition, they exhibit advanced morning activity under light-dark cycles and delayed activity under constant dark conditions, which correlates with an advance/delay of PAR domain Protein 1 (PDP1) oscillations in the small-LNv (s-LNv) neurons that control morning activity. The terminals of the s-LNv neurons show rather high levels of Pigment-dispersing factor (PDF) in the evening, when PDF is low in control flies, suggesting that the knockdown of CCHa1 leads to increased PDF release; PDF signals the other clock neurons and evidently increases the amplitude of their PDP1 cycling. A previous study showed that high-amplitude PDP1 cycling increases the siesta of the flies, and indeed, CCHa1 knockout or knockdown flies exhibit a longer siesta than control flies. The DN1a neurons are known to be receptive to PDF signaling from the s-LNv neurons; thus, our results suggest that the DN1a and s-LNv clock neurons are reciprocally coupled via the neuropeptides CCHa1 and PDF, and this interaction fine-tunes the timing of activity and sleep

Super-hard X-Ray Emission from eta Carinae Observed with Suzaku

We present the Suzaku results of eta Carinae in the 5--50 keV range conducted twice around the apastron in 2005 August for 50 ks and in 2006 February for 20 ks. The X-ray Imaging Spectrometer (XIS) produced hard (5--12 keV) band spectra, resolving K shell lines from highly ionized Fe and Ni. The Hard X-ray Detector yielded a significant detection in the super-hard (15--50 keV) band, which is uncontaminated by near-by sources. We constrained the temperature of the optically-thin thermal plasma emission dominant in the hard band as 3--4 keV using the K-shell line features with the XIS. We found significant excess emission above the thermal emission in the super-hard band with the PIN, confirming the previous INTEGRAL ISGRI report. The entire 5--50 keV spectra were fitted by a combination of a thermal plasma model plus a flat power-law or a very hot thermal bremsstrahlung model for the excess emission. No significant change of the excess emission was found at different epochs within the systematic and statistical uncertainties and no flare-like flux amplification was seen in the hard band, indicating that the excess emission is a steady phenomenon. We argue that the super-hard emission is attributable to the inverse Compton of stellar UV photons by non-thermal electrons or to the thermal bremsstrahlung of very hot plasma, and not to the bremsstrahlung by non-thermal electrons colliding with cold ambient matter.Comment: Accepted for publication in PASJ (10 pages, 7 Postscript figures

Stearoyl-CoA Desaturase-1 (SCD1) Augments Saturated Fatty Acid-Induced Lipid Accumulation and Inhibits Apoptosis in Cardiac Myocytes

Mismatch between the uptake and utilization of long-chain fatty acids in the myocardium leads to abnormally high intracellular fatty acid concentration, which ultimately induces myocardial dysfunction. Stearoyl-Coenzyme A desaturase-1 (SCD1) is a rate-limiting enzyme that converts saturated fatty acids (SFAs) to monounsaturated fatty acids. Previous studies have shown that SCD1-deficinent mice are protected from insulin resistance and diet-induced obesity; however, the role of SCD1 in the heart remains to be determined. We examined the expression of SCD1 in obese rat hearts induced by a sucrose-rich diet for 3 months. We also examined the effect of SCD1 on myocardial energy metabolism and apoptotic cell death in neonatal rat cardiac myocytes in the presence of SFAs. Here we showed that the expression of SCD1 increases 3.6-fold without measurable change in the expression of lipogenic genes in the heart of rats fed a high-sucrose diet. Forced SCD1 expression augmented palmitic acid-induced lipid accumulation, but attenuated excess fatty acid oxidation and restored reduced glucose oxidation. Of importance, SCD1 substantially inhibited SFA-induced caspase 3 activation, ceramide synthesis, diacylglycerol synthesis, apoptotic cell death, and mitochondrial reactive oxygen species (ROS) generation. Experiments using SCD1 siRNA confirmed these observations. Furthermore, we showed that exposure of cardiac myocytes to glucose and insulin induced SCD1 expression. Our results indicate that SCD1 is highly regulated by a metabolic syndrome component in the heart, and such induction of SCD1 serves to alleviate SFA-induced adverse fatty acid catabolism, and eventually to prevent SFAs-induced apoptosis

Electric conductance of metal nanowires at mechanically controllable break junctions under electrochemical potential control

We have developed the mechanically controllable break junction setup with an electrochemical cell (EC–MCBJ) to measure the electric conductance of metal nanowires under electrochemical potential control. The electric conductance of Au nanowires was investigated in 0.1 M Na_{2}SO_{4} solution using EC–MCBJ. The conductance of the Au nanowires was quantized in units of G_{0} (=2e^{2}/h), showing clear features in the conductance histogram. The atomic contact with a specific conductance value was kept for >5 s, indicating the relatively high stability of the present EC–MCBJ system

The lateral posterior clock neurons of Drosophila melanogaster express three neuropeptides and have multiple connections within the circadian clock network and beyond

Drosophila’s lateral posterior neurons (LPNs) belong to a small group of circadian clock neurons that is so far not characterized in detail. Thanks to a new highly specific split‐Gal4 line, here we describe LPNs’ morphology in fine detail, their synaptic connections, daily bimodal expression of neuropeptides, and propose a putative role of this cluster in controlling daily activity and sleep patterns. We found that the three LPNs are heterogeneous. Two of the neurons with similar morphology arborize in the superior medial and lateral protocerebrum and most likely promote sleep. One unique, possibly wakefulness‐promoting, neuron with wider arborizations extends from the superior lateral protocerebrum toward the anterior optic tubercle. Both LPN types exhibit manifold connections with the other circadian clock neurons, especially with those that control the flies’ morning and evening activity (M‐ and E‐neurons, respectively). In addition, they form synaptic connections with neurons of the mushroom bodies, the fan‐shaped body, and with many additional still unidentified neurons. We found that both LPN types rhythmically express three neuropeptides, Allostatin A, Allostatin C, and Diuretic Hormone 31 with maxima in the morning and the evening. The three LPN neuropeptides may, furthermore, signal to the insect hormonal center in the pars intercerebralis and contribute to rhythmic modulation of metabolism, feeding, and reproduction. We discuss our findings in the light of anatomical details gained by the recently published hemibrain of a single female fly on the electron microscopic level and of previous functional studies concerning the LPN