Morphological and physiological changes of ramie (Boehmeria nivea L. Gaud) in response to drought stress and GA3 treatment

Ramie (Boehmeria nivea L. Gaud) fibers extracted from the stem bast is one of the most important natural fibers. Ramie growth is severely hindered by drought stress but is promoted by gibberellins (GAs). In order to investigate ramie morphological and physiological responses to drought stress and GA₃ treatment, four groups of potted ramie (severe drought stress (DS), severe drought stress and spraying with GA₃ (DS + GA₃), normal watering and spraying with GA₃ (control + GA₃), and normal watering as a control) were tested. The result showed that, comparing with the ramie growing under well watering condition, a decrease in chlorophyll a (Chl a) and carotenoid and an increase in proline and soluble sugar contents were commonly observed in drought-stressed and GA₃-treated ramie. Different responses of the stem morphological traits, fiber yield, and seven physiological characteristics (relative water content, the activities of POD, SOD, and CAT enzymes, the contents of Chl b, endogenous GAs and MDA) were observed between drought-stressed and GA₃-treated plants. When the ramie suffering drought stress was sprayed with GA₃ (in (DS + GA₃) group), the responses of some physiological traits (POD, SOD, CAT, MDA, and endogenous GAs) and morphological traits (stem shape and fiber yield) to drought stress disappeared completely or partially, and the plant presented similar characteristics of well-watered ramie in these traits. These results suggested that the application of exogenous GA₃ can improve the drought tolerance of ramie.     

Heterologous expression of a halophilic archaeon manganese superoxide dismutase enhances salt tolerance in transgenic rice

In order to investigate new gene resource for enhancing rice tolerance to salt stress, manganese superoxide dismutase gene from halophilic archaeon (Natrinema altunense sp.) (NaMnSOD) was isolated and introduced into Oryza sativa L. cv. Nipponbare by Agrobacterium-mediated transformation. The transformants (L1 and L2) showed some NaMnSOD expression and increased total SOD and CAT activity, which contributed to higher efficiency of ROS elimination under salt stress. The levels of superoxide anion radicals (O ₂ ^·? ) and hydrogen peroxide (H₂O₂) were significantly decreased. In addition, they exhibited higher levels of photosynthesis, whereas lower relative ion leakage and MDA content compared to wild-type plants. Therefore, transgenic seedlings were phenotypically healthier, and heterologous expression of NaMnSOD could improve rice salt tolerance.     

MicroRNA-409-3p inhibits migration and invasion of bladder cancer cells via targeting c-Met

There is increasing evidence suggesting that dysregulation of certain microRNAs (miRNAs) may contribute to tumor progression and metastasis. Previous studies have shown that miR-409-3p is dysregulated in some malignancies, but its role in bladder cancer is still unknown. Here, we find that miR-409-3p is down-regulated in human bladder cancer tissues and cell lines. Enforced expression of miR-409-3p in bladder cancer cells significantly reduced their migration and invasion without affecting cell viability. Bioinformatics analysis identified the pro-metastatic gene c-Met as a potential miR-409-3p target. Further studies indicated that miR-409-3p suppressed the expression of c-Met by binding to its 3′-untranslated region. Silencing of c-Met by small interfering RNAs phenocopied the effects of miR-409-3p overexpression, whereas restoration of c-Met in bladder cancer cells bladder cancer cells overexpressing miR-409-3p, partially reversed the suppressive effects of miR-409-3p. We further showed that MMP2 and MMP9 may be downstream effector proteins of miR-409-3p. These findings indicate that miR-409-3p could be a potential tumor suppressor in bladder cancer.     

A method to determine whether a musculoskeletal model can resist arbitrary external loadings within a prescribed range

Computational models of the musculoskeletal system are prone to design errors. It is possible to create a model that cannot satisfy equilibrium conditions for a set of external loading conditions. A model is ‘loadable’ if there exists a set of muscle forces that can resist an arbitrary applied force within a prescribed range. In this study, a novel mathematical method is introduced to determine whether models are loadable. In addition, an idealised musculoskeletal model is presented in order to develop the theory behind the mathematical method. The method uses the simplex algorithm to determine feasibility of the linear programming problem and can determine loadability for an arbitrary, continuous range of external forces. The method was applied to a three-dimensional model of the shoulder and correctly determined loadability for a range of externally applied forces.     

An automatic 2D–3D image matching method for reproducing spatial knee joint positions using single or dual fluoroscopic images

Fluoroscopic image technique, using either a single image or dual images, has been widely applied to measure in vivo human knee joint kinematics. However, few studies have compared the advantages of using single and dual fluoroscopic images. Furthermore, due to the size limitation of the image intensifiers, it is possible that only a portion of the knee joint could be captured by the fluoroscopy during dynamic knee joint motion. In this paper, we presented a systematic evaluation of an automatic 2D–3D image matching method in reproducing spatial knee joint positions using either single or dual fluoroscopic image techniques. The data indicated that for the femur and tibia, their spatial positions could be determined with an accuracy and precision less than 0.2 mm in translation and less than 0.4° in orientation when dual fluoroscopic images were used. Using single fluoroscopic images, the method could produce satisfactory accuracy in joint positions in the imaging plane (in average up to 0.5 mm in translation and 1.3° in rotation), but large variations along the out-plane direction (in average up to 4.0 mm in translation and 2.2° in rotation). The precision of using single fluoroscopic images to determine the actual knee positions was worse than its accuracy obtained. The data also indicated that when using dual fluoroscopic image technique, if the knee joint outlines in one image were incomplete by 80%, the algorithm could still reproduce the joint positions with high precisions.     

Light-Regulated Hypocotyl Elongation Involves Proteasome-Dependent Degradation of the Microtubule Regulatory Protein WDL3 in Arabidopsis

Light significantly inhibits hypocotyl cell elongation, and dark-grown seedlings exhibit elongated, etiolated hypocotyls. Microtubule regulatory proteins function as positive or negative regulators that mediate hypocotyl cell elongation by altering microtubule organization. However, it remains unclear how plants coordinate these regulators to promote hypocotyl growth in darkness and inhibit growth in the light. Here, we demonstrate that WAVE-DAMPENED 2–LIKE3 (WDL3), a microtubule regulatory protein of the WVD2/WDL family from Arabidopsis thaliana, functions in hypocotyl cell elongation and is regulated by a ubiquitin-26S proteasome–dependent pathway in response to light. WDL3 RNA interference Arabidopsis seedlings grown in the light had much longer hypocotyls than controls. Moreover, WDL3 overexpression resulted in overall shortening of hypocotyl cells and stabilization of cortical microtubules in the light. Cortical microtubule reorganization occurred slowly in cells from WDL3 RNA interference transgenic lines but was accelerated in cells from WDL3-overexpressing seedlings subjected to light treatment. More importantly, WDL3 protein was abundant in the light but was degraded through the 26S proteasome pathway in the dark. Overexpression of WDL3 inhibited etiolated hypocotyl growth in regulatory particle non-ATPase subunit-1a mutant (rpn1a-4) plants but not in wild-type seedlings. Therefore, a ubiquitin-26S proteasome–dependent mechanism regulates the levels of WDL3 in response to light to modulate hypocotyl cell elongation.     

An-1 Encodes a Basic Helix-Loop-Helix Protein That Regulates Awn Development,Grain Size,and Grain Number in Rice

Long awns are important for seed dispersal in wild rice (Oryza rufipogon), but are absent in cultivated rice (Oryza sativa). The genetic mechanism involved in loss-of-awn in cultivated rice remains unknown. We report here the molecular cloning of a major quantitative trait locus, An-1, which regulates long awn formation in O. rufipogon. An-1 encodes a basic helix-loop-helix protein, which regulates cell division. The nearly-isogenic line (NIL-An-1) carrying a wild allele An-1 in the genetic background of the awnless indica Guangluai4 produces long awns and longer grains, but significantly fewer grains per panicle compared with Guangluai4. Transgenic studies confirmed that An-1 positively regulates awn elongation, but negatively regulates grain number per panicle. Genetic variations in the An-1 locus were found to be associated with awn loss in cultivated rice. Population genetic analysis of wild and cultivated rice showed a significant reduction in nucleotide diversity of the An-1 locus in rice cultivars, suggesting that the An-1 locus was a major target for artificial selection. Thus, we propose that awn loss was favored and strongly selected by humans, as genetic variations at the An-1 locus that cause awn loss would increase grain numbers and subsequently improve grain yield in cultivated rice.