Novel Regulatory Mechanisms Of Inositol Biosynthesis In Saccharomyces Cerevisiae And Mammalian Cells, And Implications For The Mechanism Underlying Vpa-Induced Glucose 6-Phosphate Depletion

Myo-inositol is the precursor of all inositol containing molecules, including inositol phosphates, phosphoinositides and glycosylphosphatidylinositols, which are signaling molecules involved in many critical cellular functions. Perturbation of inositol metabolism has been linked to neurological disorders. Although several widely-used anticonvulsants and mood-stabilizing drugs have been shown to exert inositol depletion effects, the mechanisms of action of the drugs and the role of inositol in these diseases are not understood. Elucidation of the molecular control of inositol synthesis will shed light on the pathologies of inositol related illnesses. In Saccharomyces cerevisiae, deletion of the four glycogen synthase kinase-3 genes, MCK1, MRK1, MDS1, and YGK3, resulted in multiple features of inositol depletion. My studies demonstrated that the MCK1 gene is required for normal inositol homeostasis. mck1∆ and gsk3∆ (mck1∆mrk1∆mds1∆ygk3∆) cells exhibited similar features of inositol depletion. MCK1 ablation led to decreased myo-inositol-3-phosphate synthase (MIPS) activity and a decreased rate of inositol de novo synthesis. This is the first demonstration that Mck1 controls inositol synthesis by regulating MIPS activity. While elegant studies have revealed several inositol-regulating mechanisms in yeast, very little is known about regulation of inositol synthesis in mammals. My studies discovered that IP6K1, an inositol hexakisphosphate kinase that catalyzes the synthesis of inositol pyrophosphate, negatively regulates inositol synthesis in mammalian cells. Interestingly, IP6K1 preferentially bound to the phospholipid phosphatidic acid, and this binding was required for IP6K1 nuclear localization and the transcriptional regulation of Isyna1, which encodes mammalian MIPS. This is the first demonstration of the molecular control of de novo synthesis of inositol in mammalian cells. VPA depletes intracellular glucose 6-phosphate in yeast cells by an unidentified mechanism. My studies discovered that VPA inhibits expression of hexose transporter genes HXT2, HXT4, HXT6, and HXT7. Mig1, a DNA-binding transcription repressor that translocates to the nucleus to repress gene expression under high glucose conditions, is required to inhibit HXT2 and HXT4 expression. Interestingly, VPA triggered Mig1 nuclear localization under non-repressive conditions. Furthermore, ablation of REG1, which regulates Mig1 translocation, reversed VPA-induced inhibition of HXT4 expression. These findings suggest that VPA may inhibit glucose uptake by activating Mig1-mediated repression of hexose transporter genes

Deformable Object Tracking with Gated Fusion

The tracking-by-detection framework receives growing attentions through the integration with the Convolutional Neural Networks (CNNs). Existing tracking-by-detection based methods, however, fail to track objects with severe appearance variations. This is because the traditional convolutional operation is performed on fixed grids, and thus may not be able to find the correct response while the object is changing pose or under varying environmental conditions. In this paper, we propose a deformable convolution layer to enrich the target appearance representations in the tracking-by-detection framework. We aim to capture the target appearance variations via deformable convolution, which adaptively enhances its original features. In addition, we also propose a gated fusion scheme to control how the variations captured by the deformable convolution affect the original appearance. The enriched feature representation through deformable convolution facilitates the discrimination of the CNN classifier on the target object and background. Extensive experiments on the standard benchmarks show that the proposed tracker performs favorably against state-of-the-art methods

Visualizing the Invisible: Occluded Vehicle Segmentation and Recovery

In this paper, we propose a novel iterative multi-task framework to complete the segmentation mask of an occluded vehicle and recover the appearance of its invisible parts. In particular, to improve the quality of the segmentation completion, we present two coupled discriminators and introduce an auxiliary 3D model pool for sampling authentic silhouettes as adversarial samples. In addition, we propose a two-path structure with a shared network to enhance the appearance recovery capability. By iteratively performing the segmentation completion and the appearance recovery, the results will be progressively refined. To evaluate our method, we present a dataset, the Occluded Vehicle dataset, containing synthetic and real-world occluded vehicle images. We conduct comparison experiments on this dataset and demonstrate that our model outperforms the state-of-the-art in tasks of recovering segmentation mask and appearance for occluded vehicles. Moreover, we also demonstrate that our appearance recovery approach can benefit the occluded vehicle tracking in real-world videos

An Instrument for In Situ Measuring the Volume Scattering Function of Water: Design, Calibration and Primary Experiments

The optical volume scattering function (VSF) of seawater is a fundamental property used in the calculation of radiative transfer for applications in the study of the upper-ocean heat balance, the photosynthetic productivity of the ocean, and the chemical transformation of photoreactive compounds. A new instrument to simultaneously measure the VSF in seven directions between 20° to 160°, the attenuation coefficient, and the depth of water is presented. The instrument is self-contained and can be automatically controlled by the depth under water. The self-contained data can be easily downloaded by an ultra-short-wave communication system. A calibration test was performed in the laboratory based on precise estimation of the scattering volume and optical radiometric calibration of the detectors. The measurement error of the VSF measurement instrument has been estimated in the laboratory based on the Mie theory, and the average error is less than 12%. The instrument was used to measure and analyze the variation characteristics of the VSF with angle, depth and water quality in Daya Bay for the first time. From these in situ data, we have found that the phase functions proposed by Fournier-Forand, measured by Petzold in San Diego Harbor and Sokolov in Black Sea do not fit with our measurements in Daya. These discrepancies could manly due to high proportion of suspended calcium carbonate mineral-like particles with high refractive index in Daya Bay

An RBF-based reparameterization method for constrained texture mapping

Texture mapping has long been used in computer graphics to enhance the realism of virtual scenes. However, to match the 3D model feature points with the corresponding pixels in a texture image, surface parameterization must satisfy specific positional constraints. However, despite numerous research efforts, the construction of a mathematically robust, foldover‐free parameterization that is subject to positional constraints continues to be a challenge. In the present paper, this foldover problem is addressed by developing radial basis function (RBF) based reparameterization. Given initial 2D embedding of a 3D surface, the proposed method can reparameterize 2D embedding into a foldover ‐free 2D mesh, satisfying a set of user‐specified constraint points. In addition, this approach is mesh‐free. Therefore, generating smooth texture mapping results is possible without extra smoothing optimization