Unconventionally fast transport through sliding dynamics of rodlike particles in macromolecular networks.

Transport of rodlike particles in confinement environments of macromolecular networks plays crucial roles in many important biological processes and technological applications. The relevant understanding has been limited to thin rods with diameter much smaller than network mesh size, although the opposite case, of which the dynamical behaviors and underlying physical mechanisms remain unclear, is ubiquitous. Here, we solve this issue by combining experiments, simulations and theory. We find a nonmonotonic dependence of translational diffusion on rod length, characterized by length commensuration-governed unconventionally fast dynamics which is in striking contrast to the monotonic dependence for thin rods. Our results clarify that such a fast diffusion of thick rods with length of integral multiple of mesh size follows sliding dynamics and demonstrate it to be anomalous yet Brownian. Moreover, good agreement between theoretical analysis and simulations corroborates that the sliding dynamics is an intermediate regime between hopping and Brownian dynamics, and provides a mechanistic interpretation based on the rod-length dependent entropic free energy barrier. The findings yield a principle, that is, length commensuration, for optimal design of rodlike particles with highly efficient transport in confined environments of macromolecular networks, and might enrich the physics of the diffusion dynamics in heterogeneous media.

LhGST is an anthocyanin-related glutathione S-transferase gene in Asiatic hybrid lilies (Lilium spp.).

KEY MESSAGE: LhGST, an anthocyanin-related GST gene, was identified from Asiatic hybrid lilies. Expression and functional analyses demonstrated that LhGST might be involved in anthocyanin sequestration in lily tepals. Anthocyanins are responsible for the pink, red and purple pigmentation of flowers in Asiatic hybrid lilies, synthesized at the cytoplasmic surface of the endoplasmic reticulum (ER) and then transported to the vacuole. To date, the mechanism involved in the intracellular transport of anthocyanins in lilies has not been well elucidated. Here, full-length glutathione S-transferase gene (LhGST) was identified from lilies. Expression analysis revealed that LhGST was positively correlated with anthocyanin accumulation. Phylogenetic tree analysis showed that LhGST clustered with other anthocyanin-related GSTs in the same phi clade. Moreover, functional complementation of an Arabidopsis tt19 mutant demonstrated that LhGST might be involved in anthocyanin accumulation in lily tepals. Additionally, according to phenotype analysis, LhGST was found to be correlated with the transport of anthocyanin in lilies by virus-induced gene silencing (VIGS) assay. In addition, cis-element analysis of the LhGST promoter showed the presence of ABA-, auxin-, MeJA-, gibberellin-, light-, and stress-responsive elements and an MYB recognition site (MRS, CCGTTG). Yeast one-hybrid and dual-luciferase report assays revealed that the promoter of LhGST was activated by LhMYB12-lat, which is a key R2R3-MYB transcription factor that regulates anthocyanin biosynthesis in lilies. In conclusion, our results revealed that LhGST plays a key role in anthocyanin transport and accumulation in the tepals of lilies.

RGB-D Object SLAM Using Quadrics for Indoor Environments.

Indoor service robots need to build an object-centric semantic map to understand and execute human instructions. Conventional visual simultaneous localization and mapping (SLAM) systems build a map using geometric features such as points, lines, and planes as landmarks. However, they lack a semantic understanding of the environment. This paper proposes an object-level semantic SLAM algorithm based on RGB-D data, which uses a quadric surface as an object model to compactly represent the object's position, orientation, and shape. This paper proposes and derives two types of RGB-D camera-quadric observation models: a complete model and a partial model. The complete model combines object detection and point cloud data to estimate a complete ellipsoid in a single RGB-D frame. The partial model is activated when the depth data is severely missing because of illuminations or occlusions, which uses bounding boxes from object detection to constrain objects. Compared with the state-of-the-art quadric SLAM algorithms that use a monocular observation model, the RGB-D observation model reduces the requirements of the observation number and viewing angle changes, which helps improve the accuracy and robustness. This paper introduces a nonparametric pose graph to solve data associations in the back end, and innovatively applies it to the quadric surface model. We thoroughly evaluated the algorithm on two public datasets and an author-collected mobile robot dataset in a home-like environment. We obtained obvious improvements on the localization accuracy and mapping effects compared with two state-of-the-art object SLAM algorithms.

Mechanism of exogenous cytokinins inducing bulbil formation in Lilium lancifolium in vitro.

KEY MESSAGE: The cytokinin pathway promotes the initiation of bulbil formation, and iPA may an important type of cytokinin during bulbil formation in Lilium lancifolium. Bulbils are important vegetative reproductive organs in triploid Lilium lancifolium. We previously showed that cytokinins are involved in bulbil formation, but how cytokinins participate in bulbil formation is not clear. In this study, bulbil formation was divided into three stages on the basis of anatomical and histological observations: the bulbil initiation stage, bulbil primordium-formation stage and bulbil structure-formation stage. The results indicated that iPA was the most critical cytokinin during the bulbil initiation. qRT-PCR revealed that increased iPA content during bulbil initiation was mainly due to increased expression of cytokinin synthesis genes (IPT1/5) and cytokinin activation genes (LOG1/3/5/7) and significantly decreased expression of the cytokinin degradation gene CKX4. Exogenous 6-BA and lovastatin affected the cytokinin pathway and promoted or inhibited bulbil initiation by increasing or decreasing the content of endogenous iPA, respectively. In summary, we demonstrate that cytokinins positively regulate bulbil formation and provide preliminary insight into the regulatory mechanisms by which the cytokinin pathway promotes bulbil initiation.

Point-Plane SLAM Using Supposed Planes for Indoor Environments.

Simultaneous localization and mapping (SLAM) is a fundamental problem for various applications. For indoor environments, planes are predominant features that are less affected by measurement noise. In this paper, we propose a novel point-plane SLAM system using RGB-D cameras. First, we extract feature points from RGB images and planes from depth images. Then plane correspondences in the global map can be found using their contours. Considering the limited size of real planes, we exploit constraints of plane edges. In general, a plane edge is an intersecting line of two perpendicular planes. Therefore, instead of line-based constraints, we calculate and generate supposed perpendicular planes from edge lines, resulting in more plane observations and constraints to reduce estimation errors. To exploit the orthogonal structure in indoor environments, we also add structural (parallel or perpendicular) constraints of planes. Finally, we construct a factor graph using all of these features. The cost functions are minimized to estimate camera poses and global map. We test our proposed system on public RGB-D benchmarks, demonstrating its robust and accurate pose estimation results, compared with other state-of-the-art SLAM systems.