Physiological responses and transcriptomic analysis of StCPD gene overexpression in potato under salt stresses.

Introduction: The potato (Solanum tuberosum L.), one of the most vital food crops worldwide, is sensitive to salinity. Brassinosteroids (BRs) are crucial in tolerance to various abiotic stresses. The constitutive photomorphogenesis and dwarf (CPD) gene encodes C-3 oxidase, which is a rate-limiting enzyme that controls the synthesis of BRs. Methods: In this study, we used StCPD gene overexpression (T) and un-transgenic (NT) plants obtained from our former research to illustrate adaptive resistance to salt stress at levels of phenotype; cell ultrastructure, physiology, and biochemistry; hormone; and transcription. Results: Results showed the accumulation of 2,4-epibrassionolide (EBL) in T potatoes. We found that under high salt situations, the changed Na+/K+ transporter gene expression was linked with the prevalent ionic responses in T plants, which led to lower concentrations of K+ and higher concentrations of Na+ in leaves. Furthermore, RNA-sequencing (RNA-seq) data elucidated that gene expressions in NT and T plants were significantly changed with 200-mM NaCl treatment for 24 h and 48 h, compared with the 0-h treatment. Functional enrichment analysis suggested that most of the differentially expressed genes (DEGs) were related to the regulation of BR-related gene expression, pigment metabolism process, light and action, and plant hormone signal transduction. Discussion: These findings suggested that StCPD gene overexpression can alleviate the damage caused by salt stress and enhance the salt resistance of potato plantlets. Our study provides an essential reference for further research on BR regulation of plant molecular mechanisms in potatoes with stress tolerance.

The impact of task complexity and translating self-efficacy belief on students' translation performance: Evidence from process and product data.

Previous studies that explored the impact of task-related variables on translation performance focused on task complexity but reported inconsistent findings. This study shows that, to understand the effect of task complexity on translation process and its end product, performance in translation tasks of various complexity levels needs to be compared in a specific setting, in which more factors are considered besides task complexity-especially students' translating self-efficacy belief (TSEB). Data obtained from screen recording, subjective rating, semi-structured interview, and quality evaluation were triangulated to measure how task complexity influenced the translation performance of Chinese students with high and low TSEB. We found that the complex task led to significantly longer task duration, greater self-reported cognitive effort, lower accuracy, and poorer fluency than the simple one among students, irrespective of their TSEB level. Besides, the high-TSEB group outperformed the low-TSEB group in translation accuracy and fluency in both tasks. However, the interaction effect of task complexity and TSEB was not significant, due possibly to weak problem awareness among students. Our study has implications for effectively designing task complexity, getting the benefits of TSEB, and improving research on translation performance.

Comprehensive Analysis of StSRO Gene Family and Its Expression in Response to Different Abiotic Stresses in Potato.

As a highly conserved family of plant-specific proteins, SIMILAR-TO-RCD-ONE (SROs) play an essential role in plant growth, development and response to abiotic stresses. In this study, six StSRO genes were identified by searching the PARP, RST and WWE domains based on the genome-wide data of potato database DM v6.1, and they were named StSRO1-6 according to their locations on chromosomes. StSRO genes were comprehensively analyzed using bioinformatics methods. The results showed that six StSRO genes were irregularly distributed on five chromosomes. Phylogenetic analysis showed that 30 SRO genes of four species were distributed in three groups, while StSRO genes were distributed in groups II and III. The promoter sequence of StSRO genes contained many cis-acting elements related to hormones and stress responses. In addition, the expression level of StSRO genes in different tissues of doubled monoploid (DM) potato, as well as under salt, drought stresses and hormone treatments, was analyzed by RNA-seq data from the online database and quantitative real-time polymerase chain reaction (qRT-PCR) analysis. Furthermore, the expression level of StSRO genes was analyzed by transcriptome analysis under mild, moderate and severe salt stress. It was concluded that StSRO genes could respond to different abiotic conditions, but their expression level was significantly different. This study lays a foundation for further studies on the biological functions of the StSRO gene family.

Functional analysis of StDWF4 gene in response to salt stress in potato.

The DWARF4 (DWF4) gene encodes a C-22 hydroxylase which is pivotal for brassinosteroids (BRs) biosynthesis. In this research, aimed to understand the molecular mechanism of DWF4 on regulation of potatoes tolerance to salt stress, DWF4 was cloned from potato, named as StDWF4. Its 1476 bp open reading frame encodes a protein of 491 amino acids. The StDWF4-overexpressing (OE) and interference-expressing (RNAi) transgenic potato plants were acquired using Agrobacterium-mediated transformation, respectively. Tissue specific analysis using Quantitative real-time polymerase chain reaction (qRT-PCR) demonstrated that the StDWF4 gene expressed in the leaves, stems and roots of the transgenic and un-transgenic (NT) plants, with specially increased (StDWF4-OE)/reduced (StDWF4-RNAi) expression in the roots. The content of malondialdehyde (MDA) in StDWF4-OE potato plants was lower than that of NT, and proline content was higher than that of NT. MDA and proline content in StDWF4-OE and NT under salt-stress was significantly higher than that of the control and was increased at different sampling times. The content of soluble protein, soluble sugar and the activities of superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) was higher in the StDWF4-OE plantlets at varied salt treatment time than in the NT potatoes. Reduction of H2O2 content in the StDWF4-OE plants was observed. All above plant physiology indicators in the StDWF4-RNAi potatoes showed opposite variation trends. The results proved that the overexpressing of StDWF4 in potato plantlets can enhance the salt resistance by alleviating the negative effects of salt-stress. However, its interference expression in potato plants depresses the salt resistance. The results lay the groundwork for intensive study of BRs regulation in potato growth and development, and will help us to reveal the molecular mechanisms of how the BRs signaling regulate potato salt tolerance.

Expression of the Galanthus nivalis agglutinin (GNA) gene in transgenic potato plants confers resistance to aphids.

Aphids, the largest group of sap-sucking pests, cause significant yield losses in agricultural crops worldwide every year. The massive use of pesticides to combat this pest causes severe damage to the environment, putting in risk the human health. In this study, transgenic potato plants expressing Galanthus nivalis agglutinin (GNA) gene were developed using CaMV 35S and ST-LS1 promoters generating six transgenic lines (35S1-35S3 and ST1-ST3 corresponding to the first and second promoter, respectively). Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the GNA gene was expressed in leaves, stems and roots of transgenic plants under the control of the CaMV 35S promoter, while it was only expressed in leaves and stems under the control of the ST-LS1 promoter. The levels of aphid mortality after 5 days of the inoculation in the assessed transgenic lines ranged from 20 to 53.3%. The range of the aphid population in transgenic plants 15 days after inoculation was between 17.0±1.43 (ST2) and 36.6±0.99 (35S3) aphids per plant, which corresponds to 24.9-53.5% of the aphid population in non-transformed plants. The results of our study suggest that GNA expressed in transgenic potato plants confers a potential tolerance to aphid attack, which appears to be an alternative against the use of pesticides in the future.

Isolation and characterization of StERF transcription factor genes from potato (Solanum tuberosum L.).

Ethylene response factor (ERF) is a major subfamily of the AP2/ERF family and plays significant roles in the regulation of abiotic- and biotic-stress responses. ERF proteins can interact with the GCC-box cis-element and then initiate a transcriptional cascade activating downstream ethylene response and enhancing plant stress tolerance. In this research, we cloned five StERF genes from potato (Solanum tuberosum L.). The expressional analysis of StERF genes revealed that they showed tissue- or organ-specific expression patterns and the expression levels in leaf, stem, root, flower, and tuber were different. The assays of quantitative real-time polymerase chain reaction (qRT-PCR) and the reverse transcription-PCR (RT-PCR) showed that the expression of five StERF genes was regulated by ethephon, methyl jasmonate (MeJA), salt and drought stress. The result from the yeast one-hybrid experiment showed that five StERFs had trans-activation activity and could specifically bind to the GCC-box cis-elements. The StERFs responded to abiotic factors and hormones suggested that they possibly had diverse roles in stress and hormone regulation of potato.

A quantitative study of the intracellular concentration of graphene/noble metal nanoparticle composites and their cytotoxicity.

Noble-metal nanoparticles (NPs) especially prepared from gold and silver have been combined on the surface of graphene to obtain graphene-based nanocomposites for novel functions in enhanced performance in bio-imaging, cancer detection and therapy. However, little is known about their cellular uptake, especially the intracellular quantity which plays a critical role in determining their functions and safety. Therefore, we prepared covalently conjugated GO/Au and GO/Ag composites by immobilizing Au and Ag nanoparticles on GO sheets pre-functionalized with disulfide bonds, respectively. The cellular uptake of these composites was quantitatively studied by means of an ion beam microscope (IBM) to determine the metal content in human lung cancer cells (A549 cells) and liver hepatocellular carcinoma cells (HepG2 cells). The cell uptake was also studied by inductively coupled plasma mass spectrometry (ICP-MS), which is one of the most sensitive techniques being applied to cell suspensions, for comparison. Toxicity, one of the consequences of cellular uptake of GO based composites, was studied as well. The potential toxicity mechanism was also suggested based on the results of intracellular quantification of the nanomaterials.

Uptake of cerium oxide nanoparticles and their influences on functions of A549 cells.

The cerium oxide nanoparticles (NPs) have been widely used in the fields of fuel additives, cosmetics, commodities, pharmaceuticals and other industries. Exposure of the CeO2 NPs causes a public concern on their potential health risk. In this study, the interactions between two commercial CeO2 NPs and human bronchoalveolar carcinoma-derived A549 cells were investigated to provide a fast and in-depth understanding of the biological influences of the NPs. In the culture medium containing 10% fetal bovine serum, both of the D-CeO2 and PC-CeO2 NPs had an extremely small solubility (< 0.1 ng/mL) and were aggregated from 20 nm and 8 nm (in a dry state) to approximately 190 nm and approximately 60 nm, respectively. Both types of the CeO2 NPs showed slightly negative surface charge due to the adsorption of serum proteins. They had rather weak cytotoxicity even at the highest concentration of 200 microg/mL. Cellular uptake of the CeO2 NPs increased along with the increase of concentration and incubation time. The internalized CeO2 NPs were dispersed in vacuoles and cytoplasm. Uptake of the particles resulted in slight change of the cell cycles, i.e., more cells stayed in the G1 phase, and could suppress the production of reactive oxygen species but brought negligible influence on the mitochondrial membrane potential. However, the cytoskeleton organization and the cell adhesion ability were affected to some extent.

Influence of structure and properties of colloidal biomaterials on cellular uptake and cell functions.

The molecular structure and physicochemical properties of nano- and colloidal materials have a big impact on their intracellular uptake and cell functions. Elucidation of the cellular uptake and cytotoxicity of the colloidal materials has been recognized recently as one of the paramount prerequisites for their biomedical applications. In this review, the influence of important parameters of colloidal biomaterials such as size, shape, chemical and mechanical properties on cellular uptake and its pathways is summarized. The intracellular distribution and transportation of the colloidal particles are then correlated with their physiochemical properties. The impacts on cytotoxicity and cell functions are also discussed. Finally, more attention is suggested to be paid on the basic understanding of cellular uptake and subsequent influence on cells, which is of great significance for the function implementations and safer applications of nano- and colloidal materials.

Pillar[6]arene/paraquat molecular recognition in water: high binding strength, pH-responsiveness, and application in controllable self-assembly, controlled release, and treatment of paraquat poisoning.

The complexation between a water-soluble pillar[6]arene (WP6) and paraquat (G1) in water was investigated. They could form a stable 1:1 [2]pseudorotaxane with an extremely high association constant of (1.02 ± 0.10) × 10(8) M(-1) mainly driven by electrostatic interactions, hydrophobic interactions, and π-π stacking interactions. This molecular recognition has not only high binding strength but also pH-responsiveness. The threading and dethreading processes of this [2]pseudorotaxane could be reversibly controlled by changing the solution pH. This novel recognition motif was further used to control the aggregation of a complex between WP6 and an amphiphilic paraquat derivative (G2) in water. The reversible transformations between micelles based on G2 and vesicles based on WP6⊃G2 were realized by adjusting the solution pH due to the pH-responsiveness of WP6. The controlled release of water-soluble dye molecules from the vesicles could be achieved by the collapse of the vesicles into the micelles upon changing the solution pH to acidity. Additionally, the high binding affinity between WP6 and paraquat could be utilized to efficiently reduce the toxicity of paraquat. After the formation of a stable host-guest complex between WP6 and paraquat, less opportunity was available for paraquat to interact with the reducing agents in the cell, which made the generation of its radical cation more difficult, resulting in the efficient reduction of paraquat toxicity.

Influence of surface coating of PLGA particles on the internalization and functions of human endothelial cells.

This study is focused on the uptake of PLGA particles with different coatings and its influences on the functions and toxicity of human endothelial cells. The PLGA particles coated with polyethyleneimine (PEI) or bovine serum albumin (BSA) were prepared via a one-step emulsion method, which had a similar diameter of ∼420 nm in water and ∼170 nm in a dry state but oppositely charged surfaces. Both types of the particles were readily internalized into cells within a short time regardless of their surface chemistry. Uptake of the positively charged particles caused apparently a decrease in cell viability, but did not significantly influence mitochondrial membrane potential and activity of caspase-3. The cell adhesion and migration were significantly affected, especially after uptake of the PLGA-PEI particles. The secretion levels of von Willebrand factor (vWF) and 6-k-PGF(1α) were not significantly influenced regardless of the surface coating.

[Hemostatic effect of hemocoagulase agkistrodon and its mechanism].

This study was aimed to investigate the hemostatic effects of hemocoagulase agkistrodon (HCA) and its mechanism. The procoagulative and hemostatic effects of HCA were evaluated by using rabbit blood coagulatin time and mouse tail bleeding time; the mechanisms of HCA hemostatic effect were analyzed by using rabbit blood clot lysis and fibrinogen lysis. The results showed that HCA shortened the rabbit blood coagulation time and the mouse tail bleeding time significantly. The effects are nearly similar to that of positive control (reptilase). HCA also induced rabbit blood clot lysis and directly hydrolysed the alpha-chain of fibrinogen. It is concluded that HCA exert its hemostatic effects by hydrolysing the alpha-chain of fibrinogen, but it is not able to induce production of XIII factor.

Postnatal growth, neurobehavioral and neurophysiologic changes of prenatal low-dose beta-radiation from tritiated water in mice.

Pregnant adult C57BL/6J mice were randomly assigned to four groups: one sham and three irradiated groups that were exposed to -irradiation from tritiated water (HTO) by a single intraperitoneal injection on Day 12.5 of gestation. The offspring received cumulative doses of 0.036, 0.071, and 0.213 Gy, respectively. The litters were observed for postnatal growth (body weight, brain weight), the development of four physiologic milestones (pinna detachment, eye opening, testes decent, vaginal opening), the acquisition age of several reflexes (cliff avoidance, air righting) and sensory functions (auditory startle, thermal reflex), movement and coordination functions and activity (pivoting, foot splay, continuous corridor activity), learning and memory performance (shock avoidance, conditioning reflex), and the density of CA1-CA4 hippocampal pyramidal neurons. Modest but significant dose-dependent neuronal death and functional impairment were seen in both 0.071 and 0.213 Gy groups. In conclusion, even prenatal low-dose beta-radiation may impair murine central nervous system (CNS) development suggesting the potential importance of minimizing environmental exposure during human pregnancy.