Colloidal toxic trace metals in urban riverine and estuarine waters of Yantai City, southern coast of North Yellow Sea

The environmental characteristics of colloidal toxic trace metals Cd, Cu and Pb in riverine and estuarine waters collected from two urban rivers of Yantai City in eastern China, the Guangdang and Xin'an Rivers, were investigated using a modified centrifugal ultrafiltration (CUF) method in conjunction with acid extraction and inductively coupled plasma mass spectrometry. The target metals in dissolved pool were divided into four CUF fractions, i.e. <1 kDa, 1-3 kDa, 3-10 kDa and 10 kDa-0.2 mu m, and the results showed that colloidal Cd, Cu and Pb were dominated by 1-10 kDa (1-3 and 3-10 kDa), 1-3 kDa and 10 kDa-0.2 lm fractions, respectively. The coagulation/flocculation of low-molecular-weight (1-10 kDa) colloidal Cd and Cu in the estuaries was obvious and strong, while the enrichment of dissolved Pb in the 10 kDa-0.2 lm fraction may be mainly related to its biogeochemical interactions with Fe-oxides, which is easy to occur in macromolecular colloids. In addition, the actual molecular weight cutoffs (MWCOs) of the three used CUF units with nominal MWCOs of 1, 3 and 10 kDa were determined to be 4.9, 8.5 and 33.9 kDa, respectively, indicating that membrane calibration is essential for explaining the actual fraction of dissolved trace metals and verifying the integrity of ultrafiltration membrane. Overall, the results in this study provide a further understanding of the heterogeneity in biogeochemical features, migration and fate of toxic trace metals in aquatic ecosystems, especially that of the river-sea mixing zone. (C) 2019 Elsevier B.V. All rights reserved

Some nonlocal elliptic problem involving positive parameter

We consider the following superlinear Kirchhoff type nonlocal problem: \cases \displaystyle -\bigg(a+b\int_\Omega |\nabla u|^2dx\bigg)\Delta u =\lambda f(x,u) & \text{in } \Omega,\ a> 0, \ b> 0, \ \lambda > 0, \\ u=0 &\text{on } \partial\Omega. \endcases Here, $f(x,u)$ does not satisfy the usual superlinear condition, that is, for some $\theta > 0,$ $$0\leq F(x,u)\triangleq \int_0^u f(x,s)ds \leq \frac1{2+\theta}f(x,u)u, \quad \text{for all } (x,u)\in \Omega \times \mathbb{R}^+$$ or the following variant $$0\leq F(x,u)\triangleq \int_0^u f(x,s)ds \leq \frac1{4+\theta}f(x,u)u, \quad \text{for all } (x,u)\in \Omega \times \mathbb{R}^+$$ which is quiet important and natural. But this superlinear condition is very restrictive eliminating many nonlinearities. The aim of this paper is to discuss how to use the mountain pass theorem to show the existence of non-trivial solution to the present problem when we lose the above superlinear condition. To achieve the result, we first consider the existence of a solution for almost every positive parameter $\lambda$ by varying the parameter $\lambda$. Then, it is considered the continuation of the solutions

Progress in Research on the Mechanisms Underlying Chloroplast-Involved Heat Tolerance in Plants

Global warming is a serious challenge plant production has to face. Heat stress not only affects plant growth and development but also reduces crop yield and quality. Studying the response mechanisms of plants to heat stress will help humans use these mechanisms to improve the heat tolerance of plants, thereby reducing the harm of global warming to plant production. Research on plant heat tolerance has gradually become a hotspot in plant molecular biology research in recent years. In view of the special role of chloroplasts in the response to heat stress in plants, this review is focusing on three perspectives related to chloroplasts and their function in the response of heat stress in plants: the role of chloroplasts in sensing high temperatures, the transmission of heat signals, and the improvement of heat tolerance in plants. We also present our views on the future direction of research on chloroplast related heat tolerance in plants

A chloroplast homologous recombinant empty vector of Dunaliella salina and its application

本发明涉及基因工程技术，具体涉及一种D。salina叶绿体同源重组空载体及其应用。 该载体包括启动子和终止子。 该重组空载体含有SEQ ID NO : 1所示碱基序列的上游同源臂和SEQ ID NO : 2所示碱基序列的下游同源臂。 插入SEQ ID NO : 1所示的核苷酸序列，其与至少一个外源基因形成多顺反子结构。 采用本发明的盐藻叶绿体稳定表达系统，可以在叶绿体中稳定表达多种外源基因

Overexpressing 7-Hydroxymethyl Chlorophyll a Reductase Alleviates Non-Programmed Cell Death during Dark-Induced Senescence in Intact Arabidopsis Plants

Leaf senescence, the last stage of leaf development, is a well-regulated and complex process for investigation. For simplification, dark-induced leaf senescence has frequently been used to mimic the natural senescence of leaves because many typical senescence symptoms, such as chlorophyll (Chl) and protein degradation, also occur under darkness. In this study, we compared the phenotypes of leaf senescence that occurred when detached leaves or intact plants were incubated in darkness to induce senescence. We found that the symptoms of non-programmed cell death (non-PCD) with remaining green coloration occurred more heavily in the senescent leaves of whole plants than in the detached leaves. The pheophorbide a (Pheide a) content was also shown to be much higher in senescent leaves when whole plants were incubated in darkness by analyses of leaf Chl and its metabolic intermediates. In addition, more serious non-PCD occurred and more Pheide a accumulated in senescent leaves during dark incubation if the soil used for plant growth contained more water. Under similar conditions, the non-PCD phenotype was alleviated and the accumulation of Pheide a was reduced by overexpressing 7-hydroxymethyl Chl a (HMChl a) reductase (HCAR). Taken together, we conclude that a high soil water content induced non-PCD by decreasing HCAR activity when whole plants were incubated in darkness to induce senescence; thus, the investigation of the fundamental aspects of biochemistry and the regulation of leaf senescence are affected by using dark-induced leaf senescence

Isoramin attenuates retinal cell apoptosis in diabetes retinopathy rats

Objective To investigate the effect of isorhamnetin on the apoptosis of retinal cells in diabetic retinopathy (DR) rats. Methods The rats were divided into control group, DR model group, low and high dose isorhamnetin groups (ISO-L group, ISO-H group, 50, 150 mg/kg isorhamnetin orally, respectively) and positive drug group (150 mg/kg calcium dobesilate orally). The level of serum inflammatory factors was measured by ELISA; HE staining and TUNEL staining were performed to observe the pathological changes and cell apoptosis of retina. Western blot method was performed to detect protein expression of VEGF, Bax, caspase-3 and phosphorylation levels of p38 MAPK, NF-κB p65 in retinal tissue. Results Compared with the control group, the retina of the model group was arranged disorderly, the boundary was unclear, the inner and outer nuclear layers were edema, the number of cells was reduced, and the thickness of the retina became thinner, and the retinal cell apoptosis rate, serum TNF-α, IL-1β, IL-6 levels, VEGF, Bax, caspase-3 protein expression and p38 MAPK, NF-κB p65 phosphorylation were significantly increased (P＜0.05); Compared with the model group, the retinal tissue layers of the ISO-L, ISO-H, and positive drug groups had clearer boundaries, slightly looser structures, and increased retinal thickness, and the retinal cell apoptosis rate, serum TNF-α, IL-1β, IL-6 levels, VEGF, Bax, caspase-3 protein expression, and p38 MAPK, NF-κB p65 phosphorylation levels were significantly reduced (P＜0.05). Conclusions Isorhamnetin may ameliorate retinal injury and cell apoptosis in DR rats by inhibiting the MAPK/NF-κB signaling pathway

The Effect of Projectile Nose Shape on the Critical Velocity of High-Performance Yarn

In this study, ballistic experiments were performed to determine the critical velocity of a Twaron&reg; 2040 high-performance yarn transversely impacted by round projectiles. Four different round projectiles possessing a radius of curvature of 2 &micro;m, 20 &micro;m, 200 &micro;m and 2 mm were used in this study. Load cells were mounted to the grips to measure the load history of the yarn upon impact. A high-speed camera was incorporated into the ballistic experimental setup to capture the failure process of the yarn upon impact. A scanning electron microscope was utilized to perform post-mortem failure analysis on the recovered specimens. The results showed that as the radius of curvature of the projectile increased, the critical velocity also increased. The critical velocities for all cases were bounded between those predicted from the Euler&ndash;Bernoulli beam and Smith models. Upon impact above the upper limit of the critical velocity, the axial loads revealed a demonstrative reduction. The failure surfaces changed from shear to fibrillation as the radius of curvature increased. For those specimens that failed in shear, Hertzian contact model was used to predict the critical velocity

Bait microalga harboring antimicrobial peptide for controlling Vibrio infection in Argopecten irradians aquaculture

Vibrio infection is a longstanding and serious bacterial disease of various shellfish species that has caused high mortality rates for many decades. Antibiotics can effectively prevent and control bacterial diseases. However, the long-term abuse of antibiotics exacerbates the risk of environmental pollution, which also poses a threat to food safety. In this study, transgenic lines of the marine microalga Tetraselmis subcordiformis harboring antimicrobial peptide NZ2114 were attempted to be created as an oral drug-delivery system in shellfish aquaculture. Toward this, codon-optimized nz2114 was respectively assembled into nuclear and chloroplast expression vectors of T. subcordiformis. After particle bombardment, two stable transgenic lines Y1 (with nuclear transformation) and Y2 (with chloroplast transformation) were selected, each expressing a stable transgene inheritance for at least 12 months. In vitro experiments demonstrated the significant inhibition of total protein containing NZ2114 from transgenic lines on two marine Vibrio species and Staphylococcus aureus. To test the efficacy of transgenic baits, pathogen-infected scallops (Argopecten irradians) were fed with transgenic T. subcordiformis via oral delivery. The results showed that the survival rate (after 20 days of infection) of the scallops fed transgenic T. subcordiformis was much higher than that of scallop fed with wild-type algae (95.92% versus 80.41%). In summary, this strategy offers a new, efficient, and low-cost method for controlling Vibrio in scallop aquaculture through oral drug -delivery system, which is a promising step toward the development of safe and environment-friendly antimi-crobial baits