Investigating the mechanisms underlying phytoprotection by plant growth‐promoting rhizobacteria in Spartina densiflora under metal stress

• Pollution of coasts by toxic metals and metalloids is a worldwide problem for which phytoremediation using halophytes and associated microbiomes is becoming relevant. Metal(loid) excess is a constraint for plant establishment and development, and plant growth promoting rhizobacteria (PGPR) mitigate plant stress under these conditions. However, mechanisms underlying this effect remain elusive. The effect of toxic metal(loid)s on activity and gene expression of ROS‐scavenging enzymes in roots of the halophyte Spartina densiflora grown on real polluted sediments in a greenhouse experiment was investigated.
• Sediments of the metal‐polluted joint estuary of Tinto and Odiel rivers and control, unpollutred samples from the Piedras estuary were collected and submitted to ICP‐OES. Seeds of S. densiflora were collected from the polluted Odiel marshes and grown in polluted and unpolluted sediments. Rhizophere biofilm‐forming bacteria were selected based on metal tolerance and inoculated to S. densiflora and grown for 4 months. Fresh or frozen harvested plants were used for enzyme assays and gene expression studies, respectively.
• Metal excess induced SOD (five‐fold increase), whereas CAT and ascorbate peroxidase displayed minor induction (twofold). A twofold increase of TBARs indicated membrane damage. Our results showed that metal‐resistant PGPR (P. agglomerans RSO6 and RSO7 and B. aryabhattai RSO25) contributed to alleviate metal stress, as deduced from lower levels of all antioxidant enzymes to levels below those of non‐exposed plants. The oxidative stress index (OSI) decreased between 50 and 75% upon inoculation.
• The results also evidenced the important role of PAL, involved in secondary metabolism and/or lignin synthesis, as a pathway for metal stress management in this halophyte upon inoculation with appropriate PGPR, since the different inoculation treatments enhanced PAL expression between 3.75‐ and five‐fold. Our data confirm, at the molecular level, the role of PGPR in alleviating metal stress in S. densiflora and evidence the difficulty of working with halophytes for which little genetic information is available.

     

Post-Operative Hypertension after Total Knee Arthroplasty and the Effects on Transfusion Rates

Transfusions are a cause of significant patient morbidity as well as expense. Anesthesia literature has examined controlled intraoperative hypotension as a means for reducing blood loss and transfusions. Our hypothesis is that inversely increased blood pressure post-operatively would then lead to increased blood loss and transfusions.We examined 105 consecutive patients who underwent TKA. We found a significant odds ratio of 1.123 for pre-operative hematocrit. For post-operative blood pressure, we calculated an insignificant odds ratio of 1.007, proving no relationship between post-operative blood pressure and transfusions.This is the first study to examine increased post-operative blood pressure''s contribution to transfusion rates. Although we confirmed that low pre-operative hematocrit contributes to increased transfusions, we did not find a relationship between post-operative blood pressure and transfusions.     

Subsarcolemmal and intermyofibrillar mitochondria proteome differences disclose functional specializations in skeletal muscle

Skeletal muscle is a highly specialized tissue that contains two distinct mitochondria subpopulations, the subsarcolemmal (SS) and the intermyofibrillar (IMF) mitochondria. Although it is established that these mitochondrial subpopulations differ functionally in several ways, limited information exists about the proteomic differences underlying these functional differences. Therefore, the objective of this study was to biochemically characterize the SS and IMF mitochondria isolated from rat red gastrocnemius skeletal muscle. We separated the two mitochondrial subpopulations from skeletal muscle using a refined method that provides an excellent division of these unique mitochondrial subpopulations. Using proteomics of mitochondria and its subfractions (intermembrane space, matrix and inner membrane), a total of 325 distinct proteins were identified, most of which belong to the functional clusters of oxidative phosphorylation, metabolism and signal transduction. Although more gel spots were observed in SS mitochondria, 38 of the identified proteins were differentially expressed between the SS and IMF subpopulations. Compared to the SS mitochondrial, IMF mitochondria expressed a higher level of proteins associated with oxidative phosphorylation. This observation, coupled with the finding of a higher respiratory chain complex activity in IMF mitochondria, suggests a specialization of IMF mitochondria toward energy production for contractile activity.     

Studies on Oxidative Fermentation. Part XII

Two substances besides rubiginol, of positive ferric chloride reaction were isolated from a shaking culture of Gluconoacetobacter liquefaciens, using glucose as the substrate. One of them was found to be a new γ-pyrone derivative and the composition was concluded to be 3,5-dihydroxy-l,4-pyrone-2-carboxylic acid. The other substance was found to be comenic acid. Assumptions were made with regard to the mechanism of the formation of these γ-pyrone derivatives from glucose.     

Adaptable mesocosm facility to study oil spill impacts on corals

Although numerous studies have been carried out on the impacts of oil spills on coral physiology, most have relied on laboratory assays. This scarcity is partly explained by the difficulty of reproducing realistic conditions in a laboratory setting or of performing experiments with toxic compounds in the field. Mesocosm systems provide the opportunity to carry out such studies with safe handling of contaminants while reproducing natural conditions required by living organisms. The mesocosm design is crucial and can lead to the development of innovative technologies to mitigate environmental impacts. Therefore, this study aimed to develop a mesocosm system for studies simulating oil spills with several key advantages, including true replication and the use of gravity to control flow‐through that reduces reliance on pumps that can clog thereby decreasing errors and costs. This adaptable system can be configured to (a) have continuous flow‐through; (b) operate as an open or closed system; (c) be fed by gravity; (d) have separate mesocosm sections that can be used for individual and simultaneous experiments; and (e) simulate the migration of oil from ocean oil spills to the nearby reefs. The mesocosm performance was assessed with two experiments using the hydrocoral Millepora alcicornis and different configurations to simulate two magnitudes of oil spills. With few exceptions, physical and chemical parameters remained stable within replicates and within treatments throughout the experiments. Physical and chemical parameters that expressed change during the experiment were still within the range of natural conditions observed in Brazilian marine environments. The photosynthetic potential (F_v/F_m) of the algae associated with M. alcicornis decreased in response to an 1% crude‐oil contamination, suggesting a successful delivery of the toxic contaminant to the targeted replicates. This mesocosm is customizable and adjustable for several types of experiments and proved to be effective for studies of oil spills.     

Cytochemistry and freeze-fracture of membranes isolated from the electrocyte of Electrophorus electricus (L.)

Summary Membranes were isolated from the main electric organ of Electrophorus electricus and studied by means of cytochemistry and freezefracture. The membrane fractions consisted of vesicles inside-in as determined by localization of anionic sites using colloidal iron and cationized ferritin particles. The anionic sites were not homogeneously distributed on the surface of the vesicle. Freeze-fracture showed the presence of intramembranous particles associated with either protoplasmic (P) or extracellular (E) faces of the membrane. Regions of the membrane without particles were observed. The results are discussed in relation to the existence of association between intramembranous particles and membrane receptors.For all correspondence     

Inosine triphosphatase allele frequency and association with ribavirin-induced anaemia in Brazilian patients receiving antiviral therapy for chronic hepatitis C

Inosine triphosphatase (ITPA) single nucleotide polymorphisms (SNPs) are stronglyassociated with protection against ribavirin (RBV)-induced anaemia in European,American and Asian patients; however, there is a paucity of data for Brazilianpatients. The aim of this study was to evaluate the ITPA SNP (rs7270101/rs1127354)frequency in healthy and hepatitis C virus (HCV)-infected patients from Brazil andthe association with the development of severe anaemia during antiviral therapy. ITPASNPs were determined in 200 HCV infected patients and 100 healthy individuals bysequencing. Biochemical parameters and haemoglobin (Hb) levels were analysed in 97patients who underwent antiviral therapy. A combination of AArs7270101+CCrs1127354(100% ITPase activity) was observed in 236/300 individuals. Anaemia was observed in87.5% and 86.2% of treated patients with AA (rs7270101) and CC genotypes (rs1127354),respectively. Men with AA (rs7270101) showed a considerable reduction in Hb at week12 compared to those with AC/CC (p = 0.1475). In women, there was no influence ofgenotype (p = 0.5295). For rs1127354, men with the CC genotype also showed a suddenreduction in Hb compared to those with AC. Allelic distribution of rs7270101 andrs1127354 shows high rates of the genotypes AA and CC, respectively, suggesting thatthe study population had a great propensity for developing RBV-induced anaemia. Aprogressive Hb reduction during treatment was observed; however, this reduction wasgreater in men at week 12 than in women.     

Variations in plasma melatonin levels of the rainbow trout (Oncorhynchus mykiss) under various light and temperature conditions

Daily variations in plasma melatonin levels in the rainbow trout Oncorhynchus mykiss were studied under various light and temperature conditions. Plasma melatonin levels were higher at mid-dark than those at mid-light under light-dark (LD) cycles. An acute exposure to darkness (2 hr) during the light phase significantly elevated the plasma melatonin to the level that is comparable with those at mid-dark, while an acute exposure to a light pulse (2 hr) during the dark phase significantly suppressed melatonin to the level that is comparable with those at mid-light. Plasma melatonin kept constantly high and low levels under constant darkness and constant light, respectively. No circadian rhythm was seen under both conditions. When the fish were subjected to simulative seasonal conditions (simulative (S)-spring: under LD 13.1:10.9 at 13 degrees C; S-summer: under LD 14.3:9.7 at 16.5 degrees C; S-autumn: under LD 11.3:12.7 at 13 degrees C; S-winter: under LD 10.1:13.9 at 9 degrees C), melatonin levels during the dark phase were significantly higher than those during the light phase irrespective of simulative seasons. The peak melatonin level in each simulative season significantly correlated with temperature but not with the length of the dark phase employed. In addition, the peak melatonin level in S-autumn was significantly higher than those in S-spring although water temperature was the same under these conditions. These results indicate that the melatonin rhythm in the trout plasma is not regulated by an endogenous circadian clock but by combination of photoperiod and water temperature.     

Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)

Background

Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation.

Methodology/Principal Findings

The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO₂ levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO₂ concentrations (± SE) (716±12 and 1036±14 µatm CO₂) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 µatm CO₂). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO₂, although self-righting times were generally twice as fast as those observed in the absence of the crab.

Conclusions and Significance

These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO₂ levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.