外源H2S影响黄瓜幼苗响应高盐胁迫的蛋白质组学分析

为了阐明外源H₂S对高盐胁迫下黄瓜蛋白质表达的影响,以盐敏感型黄瓜栽培种‘春夏秋王’为材料,通过双向电泳（2 DE）技术分离叶片总蛋白质,采用基质辅助激光解析飞行时间串联质谱（MALDI TOF/TOF MS）技术对差异表达蛋白质进行质谱鉴定,并利用NCBI及SwissProt数据库检索进行差异表达蛋白质功能注释和代谢通路分析。结果表明：(1) 共检测到约2 490个蛋白质,其中蛋白质表达差异在1.5倍以上且差异显著(P<0.05)的有45个,其中有24个蛋白质表达上调,21个蛋白质表达下调。(2) 成功鉴定蛋白质26个,这些蛋白质参与了光合作用（26.92%）、蛋白质代谢（23.08%）、能量与碳水化合物代谢（11.54%）、氨基酸生物合成（11.54%）、细胞结构相关蛋白（7.69%）、抗氧化作用（3.85%）、信号转导（3.85%）及未知功能蛋白（11.54%）。(3) GO注释表明差异表达的蛋白质分子功能主要以蛋白质结合与水解酶活性为主,生物学过程涉及应激反应、有机物代谢过程、胁迫响应和细胞分化等,细胞组成集中分布在细胞部分和一些胞内细胞器。KEGG代谢通路分析表明,差异表达蛋白质主要参与了肌动蛋白细胞骨架调控、细胞凋亡、碳代谢和光和调控等代谢途径。研究表明,外源H₂S诱导了高盐胁迫下黄瓜叶片蛋白质的差异表达,为后续探索外源H₂S对黄瓜的抗盐分子机制研究提供了理论依据。     

Plant functional types broadly describe water use strategies in the Caatinga,a seasonally dry tropical forest in northeast Brazil

1. In seasonally dry tropical forests, plant functional type can be classified as deciduous low wood density, deciduous high wood density, or evergreen high wood density species. While deciduousness is often associated with drought‐avoidance and low wood density is often associated with tissue water storage, the degree to which these functional types may correspond to diverging and unique water use strategies has not been extensively tested.
2. We examined (a) tolerance to water stress, measured by predawn and mid‐day leaf water potential; (b) water use efficiency, measured via foliar δ¹³C; and (c) access to soil water, measured via stem water δ¹⁸O.
3. We found that deciduous low wood density species maintain high leaf water potential and low water use efficiency. Deciduous high wood density species have lower leaf water potential and variable water use efficiency. Both groups rely on shallow soil water. Evergreen high wood density species have low leaf water potential, higher water use efficiency, and access alternative water sources. These findings indicate that deciduous low wood density species are drought avoiders, with a specialized strategy for storing root and stem water. Deciduous high wood density species are moderately drought tolerant, and evergreen high wood density species are the most drought tolerant group.
4. Synthesis. Our results broadly support the plant functional type framework as a way to understand water use strategies, but also highlight species‐level differences.

     

Effects of Radio-Collars are not Contingent on Socioecological Conditions in Degus

Species-specific research on free-ranging mammals reveals a diversity of effects of radio-collars on behavior, body condition, and fitness. Although these studies indicate rather limited direct effects, radio-collars may cause effects influenced by socio-ecological conditions. Using a 7-year study on a natural population of group-living degus (Octodon degus), we tested the hypothesis that ecological (food availability, burrow density) and social (group size, group male-to-female ratio) conditions modulate effects of radio-collars on body condition (e.g., body mass, ecto- and endoparasite loads, fecal cortisol metabolites) and direct fitness (litter size, adult survival). We determined the effect of radio-collar use on degus by contrasting the presence or absence of radio-collars, quantifying the effects of the number of days carrying a radio-collar, and the relative mass of radio-collars worn by degus in central Chile between 2009 and 2015. Radio-collar use was not associated with direct effects on litter size, adult survival, or with body mass and fecal cortisol metabolites but was linked to low ecto- and endoparasite loads. These seemingly positive effects may reflect decreased mobility, or a research bias for radio-collaring larger, healthier individuals. There was no evidence that ecological and social conditions modulated radio-collar effects on degu body condition and direct fitness. These findings are consistent with evidence from other mammal studies that reported no appreciable detrimental direct or indirect effects of radio-collars. © 2021 The Wildlife Society.     

A mechanism coordinating root elongation,endodermal differentiation,redox homeostasis and stress response

Root growth relies on both cell division and cell elongation, which occur in the meristem and elongation zones, respectively. SCARECROW (SCR) and SHORT-ROOT (SHR) are GRAS family genes essential for root growth and radial patterning in the Arabidopsis root. Previous studies showed that SCR and SHR promote root growth by suppressing cytokinin response in the meristem, but there is evidence that SCR expressed beyond the meristem is also required for root growth. Here we report a previously unknown role for SCR in promoting cell elongation. Consistent with this, we found that the scr mutant accumulated a higher level of reactive oxygen species (ROS) in the elongation zone, which is probably due to decreased expression of peroxidase gene 3, which consumes hydrogen peroxide in a reaction leading to Casparian strip formation. When the oxidative stress response was blocked in the scr mutant by mutation in ABSCISIC ACID 2 (ABA2) or when the redox status was ameliorated by the upbeat 1 (upb1) mutant, the root became significantly longer, with longer cells and a larger and more mitotically active meristem. Remarkably, however, the stem cell and radial patterning defects in the double mutants still persisted. Since ROS and peroxidases are essential for endodermal differentiation, these results suggest that SCR plays a role in coordinating cell elongation, endodermal differentiation, redox homeostasis and oxidative stress response in the root. We also provide evidence that this role of SCR is independent of SHR, even though they function similarly in other aspects of root growth and development.     

Evaluation of nanoselenium and nanogold activities against murine intestinal schistosomiasis

Nanomedicine is one of the most important methods used to treat human diseases including parasitic diseases. Schistosomiasis is a major parasitic disease that affects human health in tropical regions. Whilst Praziquantel is the main classic antischistosomal drug, new drugs are required due to the poor effect of the drug on the parasite juveniles and immature worms, and the emergence of drug resistant strains of Schistosoma. The present study aimed to examine the curative roles of both gold and selenium nanoparticles on jejunal tissues of mice infected with Schistosoma mansoni. Transmission electron microscopy was used for characterization of nanoparticles. Gold nanoparticles of 1 mg/kg mice body weight and selenium nanoparticles 0.5 mg/kg body weight were inoculated separately into mice infected with S. mansoni. The parasite induced a significant decrease in glutathione levels; however, the levels of nitric oxide and malondialdehyde were significantly increased. Additionally, the parasite introduced deteriorations in histological architecture of the jejunal tissue. Treatment of mice with metal nanoparticles reduced the levels of body weight changes, oxidative stress and histological impairment in the jejunal tissue significantly. Therefore, our results revealed the protective role of both selenium and gold nanoparticles against jejunal injury in mice infected with S. mansoni.     

Facilitation and herbivory during restoration of California coastal sage scrub

Using nurse plants to facilitate native plant recruitment in degraded habitats is a common restoration practice across various arid and semiarid environments. Living trees or shrubs are typically considered nurse plants, whereas dead shrubs left in the landscape from prolonged drought are understudied prospective facilitators for native plant recruitment. The interaction between nurse plants and biotic pressures, such as herbivory, on native recruitment is also not well understood in semiarid plant communities. We investigated the effects of facilitation and herbivory on native seedling germination, growth, and survival in the restoration of degraded coastal sage scrub (CSS) habitat. Native shrub seedlings (Artemisia californica and Salvia mellifera) were planted, and native annual species (Amsinckia intermedia, Deinandra fasciculata, Phacelia distans, and Pseudognaphalium californicum) were sown in three Shrub Type treatments (live shrub, dead shrub, and exposed areas), with a nested Cage treatment (no cage and cage) in each Shrub Type treatment. Annual species grew equally well in all Shrub Type treatments; shrub seedlings grew largest in exposed areas. While there was little evidence of facilitation for all species tested, there were strong positive effects of caging on growth and establishment of all species. Caging palatable native species or planting species with anti‐herbivory traits around target plants may be more strategic approaches compared to using nurse plants in restoring degraded CSS after extended drought.     

Oxidative stress,erythrocyte ageing and plasma non-protein-bound iron in diabetic patients

Increased oxidative stress and decreased life span of erythrocytes (RBCs) are repeatedly reported in diabetes. In the aim to elucidate the mechanism of the latter, i.e. the events leading to erythrocyte ageing, this study determined in RBCs from diabetic patients iron release in a free desferrioxamine-chelatable form (DCI), methemoglobin (MetHb) formation, binding of autologous IgG to membrane proteins and in plasma non-protein-bound iron (NPBI), F₂-Isoprostanes (F₂-IsoPs) and advanced oxidation protein products (AOPP). DCI and MetHb were higher in diabetic RBCs than in controls and autologous IgG binding occurred in a much higher percentage of diabetic patients than controls. A significant correlation between DCI and IgG binding was found in diabetic RBCs. Plasma NPBI, esterified F₂-IsoPs and AOPP were higher in diabetic patients and a significant correlation was found between plasma NPBI and intra-erythrocyte DCI. The increased DCI and autologous IgG binding appear to be important factors in the accelerated removal of RBCs from the blood stream in diabetes and the increase in plasma NPBI could play an important role in the increased oxidative stress.     

Lipid and protein oxidation in hepatic homogenates and cell membranes exposed to bile acids

Cholestasis occurs in a variety of hepatic diseases and causes damage due to accumulation of bile acids in the liver. The aim was to investigate the effect of several bile acids, i.e. chenodeoxycholic, taurochenodeoxycholic, deoxycholic, taurodeoxycholic, ursodeoxycholic, lithocholic and taurolithocholic (TLC), in inducing oxidative damage. Hepatic tissue of male Sprague-Dawley rats was incubated with or without 1 mM of each bile acid, with or without 0.1 mM FeCl₃ and 0.1 mM ascorbic acid for the purpose of generating free radicals. Several bile acids increased lipid and protein oxidation, with TLC being the most pro-oxidative (657% and 175% in homogenates and 350% and 311% in membranes, respectively). TLC also enhanced iron-induced oxidative stress to lipids (21% in homogenates and 29% in membranes) and to proteins (74% in membranes). This enhancement was dose- and time-dependent and was reduced by melatonin. These results suggest that bile acids differentially mediate hepatic oxidative stress and may be involved in the physiopathology of cholestasis.     

Flavodoxin overexpression confers tolerance to oxidative stress in beneficial soil bacteria and improves survival in the presence of the herbicides paraquat and atrazine

Aim

To determine whether expression of a cyanobacterial flavodoxin in soil bacteria of agronomic interest confers protection against the widely used herbicides paraquat and atrazine.

Methods and Results

The model bacterium Escherichia coli, the symbiotic nitrogen‐fixing bacterium Ensifer meliloti and the plant growth‐promoting rhizobacterium Pseudomonas fluorescens Aur6 were transformed with expression vectors containing the flavodoxin gene of Anabaena variabilis. Expression of the cyanobacterial protein was confirmed by Western blot. Bacterial tolerance to oxidative stress was tested in solid medium supplemented with hydrogen peroxide, paraquat or atrazine. In all three bacterial strains, flavodoxin expression enhanced tolerance to the oxidative stress provoked by hydrogen peroxide and by the reactive oxygen species‐inducing herbicides, witnessed by the enhanced survival of the transformed bacteria in the presence of these oxidizing agents.

Conclusions

Flavodoxin overexpression in beneficial soil bacteria confers tolerance to oxidative stress and improves their survival in the presence of the herbicides paraquat and atrazine. Flavodoxin could be considered as a general antioxidant resource to face oxidative challenges in different micro‐organisms.

Significance and Impact of the study

The use of plant growth‐promoting rhizobacteria or nitrogen‐fixing bacteria with enhanced tolerance to oxidative stress in contaminated soils is of significant agronomic interest. The enhanced tolerance of flavodoxin‐expressing bacteria to atrazine and paraquat points to potential applications in herbicide‐treated soils.     

Proteomic Analysis of Specific Proteins in the Root of Salt-Tolerant Barley

Comparative two-dimensional electrophoresis showed six proteins, which were significantly produced in the root of salt-tolerant barley. These proteins were identified as stress/defense-related proteins that do not scavenge reactive oxygen species directly, suggesting that salt-tolerant barley develops not only an antioxidative system, but also physical and biochemical changes to cope with salt stress.