Spike Parameters Research Articles

Gamma rays from dark matter spikes in EAGLE simulations

Intermediate Mass Black Holes (IMBHs) with a mass range between 100 M⊙ and 106 M⊙ are expected to be surrounded by high dark matter densities, so-called dark matter spikes.The high density of self-annihilating Weakly Interacting Massive Particles (WIMPs) in these spikes leads to copious gamma-ray production. Sufficiently nearby IMBHs could therefore appear as unidentified gamma-ray sources.However, the number of IMBHs and their distribution within our own Milky Way is currently unknown. In this work, we provide a mock catalogue of IMBHs and their dark matter spikes obtained from the EAGLE simulations, in which black holes with a mass of 105 M⊙/h are seeded into the centre of halos greater than 1010 M⊙/h to model black hole feedback influencing the formation of galaxies.The catalogue contains the coordinates and dark matter spike parameters for about 2500 IMBHs present in about 150 Milky Way-like galaxies. We expect about 15+9 -6 IMBHs within our own galaxy, mainly distributed in the Galactic Centre and the Galactic Plane. In the most optimistic scenario, we find that current and future gamma-ray observatories, such as Fermi-LAT, H.E.S.S. and CTAO, would be sensitive enough to probe the cross section of dark matter self-annihilation around IMBHs down to many orders of magnitude below the thermal relic cross section for dark matter particles with masses from GeV to TeV.We have made the IMBH mock catalogue and the source code for our analysis publicly available, providing the resources to study dark matter self-annihilation around IMBHs with current and upcoming gamma-ray observatories.

Cerebellar nuclei cells produce distinct pathogenic spike signatures in mouse models of ataxia, dystonia, and tremor.

The cerebellum contributes to a diverse array of motor conditions, including ataxia, dystonia, and tremor. The neural substrates that encode this diversity are unclear. Here, we tested whether the neural spike activity of cerebellar output neurons is distinct between movement disorders with different impairments, generalizable across movement disorders with similar impairments, and capable of causing distinct movement impairments. Using in vivo awake recordings as input data, we trained a supervised classifier model to differentiate the spike parameters between mouse models for ataxia, dystonia, and tremor. The classifier model correctly assigned mouse phenotypes based on single-neuron signatures. Spike signatures were shared across etiologically distinct but phenotypically similar disease models. Mimicking these pathophysiological spike signatures with optogenetics induced the predicted motor impairments in otherwise healthy mice. These data show that distinct spike signatures promote the behavioral presentation of cerebellar diseases.

A Novel Method for Wheat Spike Phenotyping Based on Instance Segmentation and Classification

The phenotypic analysis of wheat spikes plays an important role in wheat growth management, plant breeding, and yield estimation. However, the dense and tight arrangement of spikelets and grains on the spikes makes the phenotyping more challenging. This study proposed a rapid and accurate image-based method for in-field wheat spike phenotyping consisting of three steps: wheat spikelet segmentation, grain number classification, and total grain number counting. Wheat samples ranging from the early filling period to the mature period were involved in the study, including three varieties: Zhengmai 618, Yannong 19, and Sumai 8. In the first step, the in-field collected images of wheat spikes were optimized by perspective transformation, augmentation, and size reduction. The YOLOv8-seg instance segmentation model was used to segment spikelets from wheat spike images. In the second step, the number of grains in each spikelet was classified by a machine learning model like the Support Vector Machine (SVM) model, utilizing 52 image features extracted for each spikelet, involving shape, color, and texture features as the input. Finally, the total number of grains on each wheat spike was counted by adding the number of grains in the corresponding spikelets. The results showed that the YOLOv8-seg model achieved excellent segmentation performance, with an average precision (AP) @[0.50:0.95] and accuracy (A) of 0.858 and 100%. Meanwhile, the SVM model had good classification performance for the number of grains in spikelets, and the accuracy, precision, recall, and F1 score reached 0.855, 0.860, 0.865, and 0.863, respectively. Mean absolute error (MAE) and mean absolute percentage error (MAPE) were as low as 1.04 and 5% when counting the total number of grains in the frontal view wheat spike images. The proposed method meets the practical application requirements of obtaining trait parameters of wheat spikes and contributes to intelligent and non-destructive spike phenotyping.

A Grain Number Counting Method Based on Image Characteristic Parameters of Wheat Spikes

In order to measure wheat yield and wheat spike phenotypes, the grain number of wheat spikes is counted manually at present, but acquiring the grain number of wheat spikes is laborious and time-consuming. Counting the grain number of wheat spikes with an image processing method is promising, yet the application of this method is flawed due to its low accuracy. In this work, images of wheat spikes were collected and processed with technical procedures, including image cropping, image graying, histogram equalization, image binarization, eroding operation, removing small objects, filling image holes, revolving vertical spikes, cutting off stems, and removing stems. Wheat stems in binary images were eliminated by the sum pixels method, and the morphological characteristic parameters of the image areas of wheat spikes and lengths of wheat spike axes were calculated. Mathematical models relating the image areas of wheat spikes and lengths of the wheat spike axes to the grain number were established, and the mathematical models were verified. The results showed that the characteristic parameters of the image areas of wheat spikes and the lengths of the wheat spike axes for the spike images were linear relative to the grain number, and the maximum determination coefficients R2 were 0.9336 and 0.9012, respectively. The maximum determination coefficients R2 for the practical and predicted grain numbers were 0.9552 and 0.9369, respectively, and the minimum average absolute error was 2.3, while the average relative error for the mathematical models was 5.65%. The mathematical models relating the image areas of wheat spikes and the lengths of the wheat spike axes to the grain number were practical and accurate, and the mathematical model comparing the image area of wheat spikes and the grain number was superior to that comparing the length of the wheat spike axis and the grain number. The grain number of wheat spikes could be acquired accurately and quickly by the image processing method extracting the characteristic parameters of wheat spikes.

Analysis of the Effects of the Vrn-1 and Ppd-1 Alleles on Adaptive and Agronomic Traits in Common Wheat (Triticum aestivum L.).

Wheat heading time is primarily governed by two loci: VRN-1 (response to vernalization) and PPD-1 (response to photoperiod). Five sets of near-isogenic lines (NILs) were studied with the aim of investigating the effect of the aforementioned genes on wheat vegetative period duration and 14 yield-related traits. Every NIL was sown in the hydroponic greenhouse of the Institute of Cytology and Genetics, SB RAS. To assess their allelic composition at the VRN-1 and PPD-1 loci, molecular markers were used. It was shown that HT in plants with the Vrn-A1vrn-B1vrn-D1 genotype was reduced by 29 and 21 days (p < 0.001) in comparison to HT in plants with the vrn-A1Vrn-B1vrn-D1 and the vrn-A1vrn-B1Vrn-D1 genotypes, respectively. In our study, we noticed a decrease in spike length as well as spikelet number per spike parameter for some NIL carriers of the Vrn-A1a allele in comparison to carriers of the Vrn-B1 allele. PCA revealed three first principal components (PC), together explaining more than 70% of the data variance. Among the studied genetic traits, the Vrn-A1a and Ppd-D1a alleles showed significant correlations with PCs. Regarding genetic components, significant correlations were calculated between PC3 and Ppd-B1a (-0.26, p < 0.05) and Vrn-B1 (0.57, p < 0.05) alleles. Thus, the presence of the Vrn-A1a allele affects heading time, while Ppd-D1a is associated with plant height reduction.

Characterisation of the observed diurnal cycle of precipitation over the Maritime Continent

AbstractThis study investigates the temporal and spatial complexities of the mean diurnal cycle (DC) of precipitation over the Maritime Continent during the wet season using the Integrated Multi‐satellite Retrievals for GPM (IMERG) data product and highlights systematic inaccuracies of amplitude and phase representation using the first diurnal harmonic (FDH). The first‐order nature of the DC of precipitation is already well documented, typically featuring heavy precipitation over near‐coastal land areas in the late afternoon and evening followed by maximum precipitation overnight over the surrounding seas, with offshore propagation evident in places. The DC is often described concisely in terms of an amplitude and phase based on the FDH parameters, however the omission of higher‐order components of variability results in the FDH parameters being poor indicators of the magnitude and peak time of diurnal variability in many locations. This study improves the accuracy of the amplitude and phase parameters by characterising the DC using two novel waveforms—a skew‐permitting waveform and a spike‐permitting waveform—which are constructed to characterise single‐peak cycles with rapid transitions more accurately. Key characterisation improvements include correction of a phase lag (averaging approximately 1 h) over near‐coastal land areas and capture of the short‐lasting but extreme peak in precipitation rate over Java which increases the amplitude by the order of 20%. The new skew parameter shows that locations close to coastlines experience rapid intensification and gradual weakening of diurnal precipitation, while there is a tendency toward gradual intensification and rapid weakening far inland and offshore. The new spike parameter shows that near‐coastal land experiences a brief and precisely timed peak in precipitation, whereas diurnal activity over inland locations is longer‐lasting and less precisely timed, and waters surrounding Java experience a precisely timed suppression of precipitation. Other potential applications of the novel waveforms used in this study are discussed.

Electric spike emergence and synchronization during wet etching of overlapping low energy light ion microbeam-irradiated polymers

Electric spike emission was observed for the first time for thin polymer foils irradiated with low energy light ion microbeams at overlapping fluences, when placing them in between two vessels filled with etchant and distilled water, respectively, and applying a low sinusoidal transverse voltage. The various shapes of recorded spike types are described and examined. From their emergence that occurs after different derived etching times, and the inter-correlation of different spike parameters, we draw the first conclusions about their formation mechanism, behavior, and usefulness for technical applications.

Enhancing the Study of Quantal Exocytotic Events: Combining Diamond Multi-Electrode Arrays with Amperometric PEak Analysis (APE) an Automated Analysis Code.

MicroGraphited-Diamond-Multi Electrode Arrays (μG-D-MEAs) can be successfully used to reveal, in real time, quantal exocytotic events occurring from many individual neurosecretory cells and/or from many neurons within a network. As μG-D-MEAs arrays are patterned with up to 16 sensing microelectrodes, each of them recording large amounts of data revealing the exocytotic activity, the aim of this work was to support an adequate analysis code to speed up the signal detection. The cutting-edge technology of microGraphited-Diamond-Multi Electrode Arrays (μG-D-MEAs) has been implemented with an automated analysis code (APE, Amperometric Peak Analysis) developed using Matlab R2022a software to provide easy and accurate detection of amperometric spike parameters, including the analysis of the pre-spike foot that sometimes precedes the complete fusion pore dilatation. Data have been acquired from cultured PC12 cells, either collecting events during spontaneous exocytosis or after L-DOPA incubation. Validation of the APE code was performed by comparing the acquired spike parameters with those obtained using Quanta Analysis (Igor macro) by Mosharov et al.

EFFECT OF UV RADIATION ON WHEAT PRODUCTIVITY UNDER WATER DEFICIT IRRIGATION

Water Scarcity and increasing ultraviolet radiation, especially UV-B and C bands, are direct affects of both negative climate change phenomenon and environmental pollution. Both functioned individually or synergically resulting stress in plants. Deficit irrigation and biophysical applications can be implemented to optimize the use of available water resources and increase productivity per unit area to achieve self-sufficiency of strategic crops. Pretreatedsoft wheat seeds cv. Gmeza 11 by three UV- bands UV-BS (A, B and C) with approximately dose (2.9×103mJ cm-2 ± 50), were grown till maturity on pot experiment under the winter spring of 2022/2023 season. Their response was evaluated in terms of biomass components, harvest and seed indexes, and some spike parameters, under three water deficit WD percentage 100, 85, 70% (W1,W2 and W3) of ETC, using split plot design. Moreover, some financial, technical and economic indicators for the efficiency of irrigation water were computed. Results affirmed that, all parameters had a stimulatory significant effect (P ≤ 0.05) with current studied treatments. They affected positively following UV-C, B, and A, as well as, 70, 85 and 100%. This effect may be caused individually or as a result of the interaction between them. Meanwhile, the irrigation water productivity IWP has an opposite proportion with WD, and direct proportion with UV- BS. Thehighest values of parameters were recorded with fully irrigation, 100% &amp; UV-A treatment, except for IWP and irrigation water return IWR. In contrast, the lowest values were recorded at 70% &amp;UV-C treatment, except for IWP. The results concluded that, the deficit percentage might not be increased more than 15% and UV wavelength might not be less than315nm. While the profit rate reached 61.04% at UV-A&amp;W1 treatment. The economic indicators, e.g., IWR and crop requirement, have a negative correlation with both UV-BS and WD.

Spacetime Metrics and Ringdown Waveforms for Galactic Black Holes Surrounded by a Dark Matter Spike

Theoretical models suggest the existence of a dark matter spike surrounding the supermassive black holes at the core of galaxies. The spike density is thought to obey a power law that starts at a few times the black hole horizon radius and extends to a distance, R sp, of the order of a kiloparsec. We use the Tolman–Oppenheimer–Volkoff equations to construct the spacetime metric representing a black hole surrounded by such a dark matter spike. We consider the dark matter to be a perfect fluid, but make no other assumption about its nature. The assumed power-law density provides in principle three parameters with which to work: the power-law exponent γ sp, the external radius R sp, and the spike density at R sp. These in turn determine the total mass of the spike. We focus on Sagittarius A* and M87 for which some theoretical and observational bounds exist on the spike parameters. Using these bounds in conjunction with the metric obtained from the Tolman–Oppenheimer–Volkoff equations, we investigate the possibility of detecting the dark matter spikes surrounding these black holes via the gravitational waves emitted at the ringdown phase of black hole perturbations. Our results suggest that if the spike to black hole mass ratio is roughly constant, greater mass black holes require relatively smaller spike densities to yield potentially observable signals. We find that is unlikely for the spike in M87 to be detected via the ringdown waveform with currently available techniques unless its mass is roughly an order of magnitude larger than existing observational estimates. However, given that the signal increases with black hole mass, dark matter spikes might be observable for more massive galactic black holes in the not too distant future.

Kisspeptin-13 prevented the electrophysiological alterations induced by amyloid-beta pathology in rat: Possible involvement of stromal interaction molecules and pCREB

Alzheimer's disease (AD) is a progressive neurological disease that slowly causing memory impairments with no effective treatment. We have recently reported that kisspeptin-13 (KP-13) ameliorates Aβ toxicity-induced memory deficit in rats. Here, the possible cellular impact of kisspeptin receptor activation in a rat model of the early stage AD was assessed using whole-cell patch-clamp recording from CA1 pyramidal neurons and molecular approaches. Compared to neurons from the control group, cells from the Aβ-treated group displayed spontaneous and evoked hyperexcitability with lower spike frequency adaptation. These cells had also a lower sag ratio in response to hyperpolarizing prepulse current delivered before a depolarizing current injection. Neurons from the Aβ-treated group exhibited short spike onset latency, lower rheobase and short utilization time compared with those in the control group. Furthermore, phase plot analysis of action potential showed that Aβ treatment affected the action potential features. These electrophysiological changes induced by Aβ were associated with increased expression of stromal interaction molecules (STIMs), particularly (STIM2) and decreased pCREB/CREB ratio. Treatment with KP-13 following Aβ injection into the entorhinal cortex, however, prevented the excitatory effect of Aβ on spontaneous and evoked neuronal activity, increased the latency of onset, enhanced the sag ratio, increased the rheobase and utilization time, and prevented the changes induced Aβ on spike parameters. In addition, the KP-13 application after Aβ treatment reduced the expression of STIMs and increased the pCREB/CREB ratio compared to those receiving Aβ treatment alone. In summary, these results provide evidence that activation of kisspeptin receptor may be effective against pathology of Aβ.

Covalent Coupling of Porphyrins with Monolayer Graphene for Low-Voltage Synaptic Transistors.

Synaptic devices emulating biological synapses are a key building component of artificial neural networks. Porphyrins and graphene, as two kinds of emerging electronic materials, have attracted extensive attention in the research of photoelectric devices due to their excellent structural and functional properties. Herein, we present a photonic synaptic transistor based on porphyrin-graphene covalent hybrids utilizing 5,10,15,20-tetrakis (4-aminophenyl)-21H,23H-porphine and monolayer graphene linked through the diazo addition reaction. The photonic synaptic device successfully simulates several essential biological functions, and the synaptic plasticity can be regulated by adjusting the parameters of light spikes and gate voltages of the device. Moreover, learning and memory behaviors under different wavelengths are studied to imitate the learning efficiency of humans in diverse emotional states. It is worth noting that all the synaptic functions can be realized at a low operating voltage of -10 mV, which is much lower than that required by most reported photonic synaptic devices. These results indicate that covalent coupling products of porphyrins with graphene have broad prospects in the construction of synaptic transistors and may arouse new research advances in neuromorphic devices with ultralow operating voltage and low energy consumption.

MODELS AND TOOLS OF THE AUTOMATED SYSTEM FOR COMPUTER NETWORK TRAFFIC INVESTIGATION USING BERKELEY PACKET FILTER

An approach for automating the monitoring and analysis of incoming network traffic in large-scale computer networks is proposed in the paper. The authors suggest using the Linux Berkeley Packet Filter tool to automate traffic analysis in computer networks. The software structure is developed, which includes two main parts: the service machine and the user machine, it is based on the modular principle, which allows for rapid improvement and modernization of the system. The main algorithms for software functionality are built, namely: the algorithm for processing network packets using the Berkeley Packet Filter tool, and the algorithm of the user-space program for loading the Berkeley Packet Filter program to kernel space and setting up communication with it. A study model of program functioning dynamics based on the Petri net theory has been developed. As a result of the application of models based on the Petri net in the software development process, the system works correctly, all states are accessible, and there are no dead ends. A simulation model of the application of the Berkeley Packet Filter tool for the automation of computer network traffic analysis was designed, and the script was created for testing the developed software system. Implemented Python script generates a flow of network packets with random values in the sender IP address, receiver port number, and protocol. These packets, created by the IP address spoofing methodology, later are sent to the service machine's network interface. The developed computer network traffic monitoring software, that uses the Berkeley Packet Filter tool and is implemented in C, C++, and Python programming languages, provides collecting and processing of computer network traffic data. The output of the analysed results is displayed in a user-friendly form. The development and testing of the created software were carried out on the operating system Arch Linux version 5.10.3, which was previously installed on a virtual machine. The results of traffic testing in computer networks in different modes of normal operation and during DDoS attacks are given. In particular, an example of sidebar output with network traffic statistics over a long period, an example of output with network traffic spike parameters, and an example of a warning message, that the sidebar dashboard will show, are presented.

Cytological and molecular characteristics of delayed spike development in wheat under low temperature in early spring

Low temperature in early spring impairs wheat growth and grain yield. However, little is known about the cytological and molecular mechanisms underlying low temperature regulation of wheat spike development. Microstructure observation and transcriptome sequencing of wheat spikes under low temperature were conducted. Low temperature slowed spike development, reduced the yield-component parameters of wheat spikes at the harvest stage, delayed the formation of lateral spikelets and tissue development, and induced the early differentiation of terminal spikelets. Low temperature increased the content of abscisic acid and caused the upregulation of genes in the abscisic acid signaling pathway, including those encoding PP2Cs, SnRK2s, and bZIP transcription factors. Low temperature also induced the upregulation of 33 cold-responsive genes involved in wheat response to low-temperature stress and regulation of abscisic acid biosynthesis and metabolism of other substances. The wheat spike adapted to cold conditions by changing the expression levels of genes involved in spike morphogenesis, including the transcription-factor genes MADS6, ERF4, ERF78, WOX6, and NAC48. These findings suggest that low temperature in early spring delays wheat spike development by increasing abscisic acid content or affecting the expression of genes involved in morphogenesis.

Plasticity and learning behavior emulated in a ZnO based transparent artificial synapse

Artificial synaptic devices play a vital role in constructing artificial neural networks, fundamental building blocks of neuromorphic computing. In this article, we report a transparent synaptic device that manifests potentiation, depression and forgetting behavior analogous to the biological synapse. This synaptic device possesses paired-pulse facilitation, spike parameters dependent synaptic weight, and voltage-induced transition from short-term memory to long-term memory. This study reveals that the pulse with a higher amplitude, higher pulse width, and lower pulse interval produces more change in synaptic weight. The mechanism behind potentiation and depression in the fabricated device is proposed in terms of oxygen vacancy migration; oxygen vacancies are generated and drift during the application of input pulses, thus forming a conducting filament. This device exhibits excellent short-term plasticity and long-term potentiation depending upon the input conditions, which are inherent properties of neuroplasticity. Forgetting, referred as the spontaneous decay of conductance, is explained by the rupturing of oxygen vacancy filament due to recombination of oxygen vacancies with non-lattice oxygen ions present in indium tin oxide electrodes. This is confirmed by studying the decay in device with metal electrodes.

Reconstructing Soma-Soma Synapse-like Vesicular Exocytosis with DNA Origami.

Cell–cell communications exhibit distinct physiological functions in immune responses and neurotransmitter signaling. Nevertheless, the ability to reconstruct a soma–soma synapse-like junction for probing intercellular communications remains difficult. In this work, we develop a DNA origami nanostructure-based method for establishing cell conjugation, which consequently facilitates the reconstruction of a soma–soma synapse-like junction. We demonstrate that intercellular communications including small molecule and membrane vesicle exchange between cells are maintained in the artificially designed synapse-like junction. By inserting the carbon fiber nanometric electrodes into the soma–soma synapse-like junction, we accomplish the real-time monitoring of individual vesicular exocytotic events and obtain the information on vesicular exocytosis kinetics via analyzing the parameters of current spikes. This strategy provides a versatile platform to study synaptic communications.

Modeling of the worm cutter in the process of cutting the gears

This work offers a new approach to graphical modeling of worm cutter parameters, based on analyses and synthesis of simple kinematic movements, causing its cutting elements a single move and displacement when placing metal into a hollow between spikes of the gear, which is being cut. It is one of the most difficult cutting and shaping processes, combining four kinematic movements – rotation of the cutters, their axial feed, rotation of the billet and a constructive move – displacement of cutting elements, located on the principle worm helix along the cutter axis. The modeling difficulty is that the cutting surface constantly changes its location and form in relation to the spikes. This surface is formed on the billet as a kind of a transition surface between the untreated surface, the partly treated surface and the partly treated hollow between the spikes of the gear, which is being cut. Its formation is participated by all the spikes, which have performed the cutting during all the time before a certain moment. Continuous change of the transition surface shape and size determines the shape and size of the shavings and the cross-sectional parameters of the spikes slices and the tool blades, and its reproduction is a base for a correct quantitative assessment of the cutting parameters of individual blades and spikes of the cutter. In its turn, complete and authentic information about the cross-sections and the shape and size of metal layers cut during the spike milling is a base for calculating and analysis of the cutting power, the friction force, the thermal processes, fluctuations and vibrations. The algorithm of an instant surface formation between the gear spikes and the shavings 3D geometry on all of the active spikes of the tool are realized in AutoCAD graphic system. Here are given the results of computer modeling of the shavings when using the Archimedean cutter with counter feed. Complete information about geometrical structure of the cut off layers creates the base for a detailed and system modeling of this process abreast the separate warm cutter rails, the spikes and the blades. In combination with intensity of the plastic deformation data, the tension and the temperature received in Deform system for a certain spike milling condition, the parameters of the cut layers data referred in this work, create the condition for thermo prognostication and the cutting elements waste, their power load, strength protective coatings, cutting force and temperature transition processes, optimum technological processes of spike milling projecting and its managing.

8-Nitro-cGMP modulates exocytosis in adrenal chromaffin cells

Nitric oxide (NO)-mediated production of cyclic guanosine 3′,5′-monophosphate (cGMP) is a crucial signaling pathway that controls a wide array of neuronal functions, including exocytotic neurotransmitter release. A novel nitrated derivative of cGMP, 8-nitro-cGMP, not only activates cGMP-dependent protein kinase (PKG), but also has membrane permeability and redox activity to produce superoxide and S-guanylated protein. To date, no studies have addressed the effects of 8-nitro-cGMP on exocytotic kinetics. Here, we aimed to assess the 8-nitro-cGMP-mediated modulation of the depolarization-evoked catecholamine release from bovine chromaffin cells. 8-Nitro-cGMP was produced in bovine chromaffin cells dependent on NO donor. Amperometric analysis revealed that 8-nitro-cGMP modulated the kinetic parameters of secretory spikes from chromaffin cells, particularly decreased the speed of individual spikes, resulting in a reduced amperometric spike height, slope β, and absolute value of slope γ. The modulatory effects were independent of the PKG signal and superoxide production. This is the first study to demonstrate that 8-nitro-cGMP modulates exocytosis and provide insights into a novel regulatory mechanism of exocytosis.

Ekmeklik Buğdayda (Triticum aestivum L.) Farklı Ekim Sıklıklarının Verim ve Verim Bileşenleri Üzerine Etkisinin Belirlenmesi

Buğday tarımında ekim sıklığı, tane verimi etkileyen önemli agronomik uygulamalardan biridir. Araştırmanın amacı, ekmeklik buğday çeşitlerinde (Alpu01, Atay85, Bezostaja1, Harmankaya99, Sönmez01 ve Sultan95) farklı ekim sıklığı uygulamalarının (350, 500, 650 ve 800 tohum m-2) verim ve verim bileşenleri üzerine etkisinin belirlenmesidir. Denemeler 2012-2013 ve 2013-2014 ürün yıllarında Geçit Kuşağı Tarımsal Araştırma Enstitüsü Müdürlüğü Merkez Sultanönü yerleşkesinde sulu ve kuru (yağmura bağımlı) koşullarda tesadüf bloklarında faktöriyel deseninde 3 tekerrürlü olarak yürütülmüştür. Bu çalışmada her iki koşulda da ekim sıklığı uygulamaları ve çeşitler açısından tane verim, metrekarede başak sayısı, başak uzunluğu, başakta tane sayısı, başakta tane ağırlığı ve hasat indeksi gibi unsurlar incelenmiştir. Sonuç olarak ekim sıklığı uygulamalarından en yüksek tane verimi kuru koşullarda 650 tohum m-2 uygulamasından; sulu koşullarda ise 500 tohum m-2 uygulamasından alınmıştır. Çeşitler değerlendirildiğinde her iki koşulda da tane verim açısından en yüksek değerlere Harmankaya99 çeşidi ulaşırken, bunu Alpu01 çeşidi takip etmiştir. Gerek sulu gerekse kuru koşullarda başak uzunluğu, başakta tane sayısı, başakta tane ağırlığı ve hasat indeksi değerleri artan ekim sıklığı ile ters orantılı olarak azalırken, metrekarede başak sayısı artan ekim sıklığı ile doğru orantılı olarak artış göstermiştir. Araştırmada kuru koşullarda tane verim ile metrekarede başak sayısı ve hasat indeksi arasında pozitif korelasyon bulunurken başak uzunluğu, başakta tane sayısı ve başakta tane ağırlığı arasında negatif korelasyon önemli bulunmuştur. Sulu koşullarda ise tane verim ile başak uzunluğu ve hasat indeksi arasında pozitif korelasyon önemli bulunmuştur.

Phosphatidic acid metabolism regulates neuroendocrine secretion but is not under the direct control of lipins.

Phosphatidic acid (PA) produced by phospholipase D1 has been shown to contribute to secretory vesicle exocytosis in a large number of cell models. Among various hypotheses, PA may contribute to recruit and/or activate at the exocytotic site a set of proteins from the molecular machinery dedicated to secretion, but also directly influence membrane curvature thereby favoring membrane rearrangements required for membrane fusion. The release of informative molecules by regulated exocytosis is a tightly controlled process. It is thus expected that PA produced to trigger membrane fusion should be rapidly metabolized and converted in a lipid that does not present similar characteristics. PA-phosphatases of the lipin family are possible candidates as they convert PA into diacylglycerol. We show here that lipin 1 and lipin 2 are expressed in neuroendocrine cells where they are cytosolic, but also partially associated with the endoplasmic reticulum. Silencing of lipin 1 or 2 did not affect significantly either basal or evoked secretion from PC12 cells, suggesting that it is unlikely that conversion of PA into a secondary lipid by lipins might represent a regulatory step in exocytosis in neurosecretory cells. However, in agreement with a model in which PA-metabolism could contribute to prevent entering into exocytosis of additional secretory vesicles, ectopic expression of lipin1B-GFP in bovine chromaffin cells reduced the number of exocytotic events as revealed by carbon fiber amperometry recording. Furthermore, individual spike parameters reflecting fusion pore dynamics were also modified by lipin1B-GFP, suggesting that a tight control of PA levels represents an important regulatory step of the number and kinetic of exocytotic events.