Modulation of physiological performance by temperature and salinity in the sugar kelp Saccharina latissima

The sugar kelp Saccharina latissima experiences a wide range of environmental conditions along its geographical and vertical distribution range. Temperature and salinity are two critical drivers influencing growth, photosynthesis and biochemical composition. Moreover, interactive effects might modify the results described for single effects. In shallow water coastal systems, exposure to rising temperatures and low salinity are expected as consequence of global warming, increased precipitation and coastal run‐off. To understand the acclimation mechanisms of S. latissima to changes in temperature and salinity and their interactions, we performed a mechanistic laboratory experiment in which juvenile sporophytes from Brittany, France were exposed to a combination of three temperatures (0, 8 and 15°C) and two salinity levels (20 and 30 psu (practical salinity units)). After a temperature acclimation of 7 days, sporophytes were exposed to low salinity (20 psu) for a period of 11 days. Growth, and maximal quantum yield of photosystem II (Fv/Fm), pigments, mannitol content and C:N ratio were measured over time. We report for the first time in S. latissima a fivefold increase in the osmolyte mannitol in response to low temperature (0°C) compared to 8 and 15°C that may have ecological and economic implications. Low temperatures significantly affected all parameters, mostly in a negative way. Chlorophyll a, the accessory pigment pool, growth and Fv/Fm were significantly lower at 0°C, while the de‐epoxidation state of the xanthophyll cycle was increased at both 0 and 8°C compared to 15°C. Mannitol content and growth decreased with decreased salinity; in contrast, pigment content and Fv/Fm were to a large extent irresponsive to salinity. In comparison to S. latissima originating from an Arctic population, despite some reported differences, this study reveals a remarkably similar impact of temperature and salinity variation, reflecting the large degree of adaptability in this species.     

Chronic Nicotine Treatment Impacts the Regulation of Opioid and Non-opioid Peptides in the Rat Dorsal Striatum

The chronic use of nicotine, the main psychoactive ingredient of tobacco smoking, alters diverse physiological processes and consequently generates physical dependence. To understand the impact of chronic nicotine on neuropeptides, which are potential molecules associated with dependence, we conducted qualitative and quantitative neuropeptidomics on the rat dorsal striatum, an important brain region implicated in the preoccupation/craving phase of drug dependence. We used extensive LC-FT-MS/MS analyses for neuropeptide identification and LC-FT-MS in conjunction with stable isotope addition for relative quantification. The treatment with chronic nicotine for 3 months led to moderate changes in the levels of endogenous dorsal striatum peptides. Five enkephalin opioid peptides were up-regulated, although no change was observed for dynorphin peptides. Specially, nicotine altered levels of nine non-opioid peptides derived from precursors, including somatostatin and cerebellin, which potentially modulate neurotransmitter release and energy metabolism. This broad but selective impact on the multiple peptidergic systems suggests that apart from the opioid peptides, several other peptidergic systems are involved in the preoccupation/craving phase of drug dependence. Our finding permits future evaluation of the neurochemical circuits modulated by chronic nicotine exposure and provides a number of novel molecules that could serve as potential therapeutic targets for treating drug dependence.Nicotine is the main psychoactive ingredient of tobacco (1). By acting on the nicotinic acetylcholine receptors located in diverse brain areas, nicotine generates psychoactive effects such as euphoria, reduced stress, increased energy, and enhanced cognitive functions (2). Chronic nicotine use alters various aspects of neurochemical transmission and has a strong impact on diverse physiological processes (2), resulting in drug-seeking and drug-taking behaviors for normal smokers and for a considerable number of patients suffering from schizophrenia and Alzheimer disease, who use nicotine for self-medication (3, 4). The dorsal striatum (DS)¹ is one of the key brain regions that has been associated with neural regulation during chronic nicotine exposure (5). In particular, the DS is involved in habit formation during the preoccupation/craving (later) phase of nicotine dependence characterized by compulsive drug-taking (6). Behavioral changes associated with nicotine dependence have been linked to small molecule neurotransmitter systems, including the glutamate and dopamine system in the DS (7). The DS is also known to contain diverse neuropeptides, many of which are probably critical mediators of physiological processes that are associated with nicotine, such as the regulation of reinforcement and energy metabolism. However, neuropeptides have not been extensively investigated in the DS during long periods of nicotine administration.Immunoassay studies have shown that neuropeptides, including substance P, neuropeptide Y, and opioid peptides, including the enkephalins, are expressed by inhibitory neurons (8), which make up a large majority of the neurons in the DS (9). Many of these inhibitory GABAergic neurons express nicotinic cholinergic receptors (10), suggesting that nicotine administration may regulate their activity, leading to variations in the release of neuropeptides, as well as the inhibitory neurotransmitter GABA. Previous investigations of peptide regulation during chronic nicotine administration in the striatum have exclusively focused on the class of opioid peptides, which are thought to play an important role in the control of diverse physiological processes, including reward processing, nociception, and regulation of emotions (11, 12). Available studies have focused on the analysis of three opioid peptides, their precursors, or receptors as follows: met-enkephalin, dynorphin, and β-endorphin, using conventional techniques like immunoassays (13, 14). There is considerable variability in reported changes of peptide levels in the striatum during chronic nicotine administration. For example, when animals are treated with 1 mg/kg free base nicotine (daily for 14 days), met-enkephalin increased in the striatum (15). By contrast, met-enkephalin is reduced in the striatum when rats are treated with 0.3 mg/kg nicotine (three times/day for 14 days) (16). A number of factors might contribute to this observed variability, including the exact dosing, daily frequency, time span of administration, and delivery method of nicotine. Furthermore, as individual studies have each so far generally examined a single opioid peptide, there is currently little reliable information about peptide co-regulation, even for these well studied opioid peptides. In addition to these opioid peptides, the DS expresses peptides from other peptide families, which are also potential targets under the regulation of chronic nicotine treatment. So far, however, there is no information available about changes of these non-opioid peptides during chronic nicotine administration.In this study, our aim was to use a neuropeptidomics approach (17) to provide a comprehensive characterization of dorsal striatal neuropeptides after long term nicotine chronic treatment in adult rats using oral administration. The main advantage of this approach is that it allows the simultaneous monitoring of many peptides from the same brain tissue derived from a single drug protocol. We used a combination of a robust sample preparation method (18), high accuracy LC-MS analysis (19, 20), and the use of multiple synthetic internal standards (21) to compare peptide levels in the DS between chronic nicotine and control animals. Our peptidome analysis determined 14 peptides exhibiting significant changes following chronic nicotine administration. Among these peptides were members of the opioid family that had previously been associated with nicotine dependence, as well as a number of newly identified peptides, including members of the secretogranin, cholecystokinin, and somatostatin families. This greatly expands the present scope of peptide involvement in drug dependence in the dorsal striatum.     

Phospholipids and lipid droplets

Lipid droplets are ubiquitous cellular organelles that allow cells to store large amounts of neutral lipids for membrane synthesis and energy supply in times of starvation. Compared to other cellular organelles, lipid droplets are structurally unique as they are made of a hydrophobic core of neutral lipids and are separated to the cytosol only by a surrounding phospholipid monolayer. This phospholipid monolayer consists of over a hundred different phospholipid molecular species of which phosphatidylcholine is the most abundant lipid class. However, lipid droplets lack some indispensable activities of the phosphatidylcholine biogenic pathways suggesting that they partially depend on other organelles for phosphatidylcholine synthesis.     

Body masses,functional responses and predator–prey stability

The stability of ecological communities depends strongly on quantitative characteristics of population interactions (type‐II vs. type‐III functional responses) and the distribution of body masses across species. Until now, these two aspects have almost exclusively been treated separately leaving a substantial gap in our general understanding of food webs. We analysed a large data set of arthropod feeding rates and found that all functional‐response parameters depend on the body masses of predator and prey. Thus, we propose generalised functional responses which predict gradual shifts from type‐II predation of small predators on equally sized prey to type‐III functional‐responses of large predators on small prey. Models including these generalised functional responses predict population dynamics and persistence only depending on predator and prey body masses, and we show that these predictions are strongly supported by empirical data on forest soil food webs. These results help unravelling systematic relationships between quantitative population interactions and large‐scale community patterns.     

Modulation of respiratory dendritic cells during Klebsiella pneumonia infection

Background

Klebsiella pneumoniae is a leading cause of severe hospital-acquired respiratory tract infections and death but little is known regarding the modulation of respiratory dendritic cell (DC) subsets. Plasmacytoid DC (pDC) are specialized type 1 interferon producing cells and considered to be classical mediators of antiviral immunity.

Method

By using multiparameter flow cytometry analysis we have analysed the modulation of respiratory DC subsets after intratracheal Klebsiella pneumonia infection.

Results

Data indicate that pDCs and MoDC were markedly elevated in the post acute pneumonia phase when compared to mock-infected controls. Analysis of draining mediastinal lymph nodes revealed a rapid increase of activated CD103⁺ DC, CD11b⁺ DC and MoDC within 48 h post infection. Lung pDC identification during bacterial pneumonia was confirmed by extended phenotyping for 120G8, mPDCA-1 and Siglec-H expression and by demonstration of high Interferon-alpha producing capacity after cell sorting. Cytokine expression analysis of ex vivo-sorted respiratory DC subpopulations from infected animals revealed elevated Interferon-alpha in pDC, elevated IFN-gamma, IL-4 and IL-13 in CD103⁺ DC and IL-19 and IL-12p35 in CD11b⁺ DC subsets in comparison to CD11c⁺ MHC-class II^low cells indicating distinct functional roles. Antigen-specific naive CD4⁺ T cell stimulatory capacity of purified respiratory DC subsets was analysed in a model system with purified ovalbumin T cell receptor transgenic naive CD4⁺ responder T cells and respiratory DC subsets, pulsed with ovalbumin and matured with Klebsiella pneumoniae lysate. CD103⁺ DC and CD11b⁺ DC subsets represented the most potent naive CD4⁺ T helper cell activators.

Conclusion

These results provide novel insight into the activation of respiratory DC subsets during Klebsiella pneumonia infection. The detection of increased respiratory pDC numbers in bacterial pneumonia may indicate possible novel pDC functions with respect to lung repair and regeneration.     

Bacterial Viability and Physical Properties of Antibacterially Modified Experimental Dental Resin Composites

Purpose

To investigate the antibacterial effect and the effect on the material properties of a novel delivery system with Irgasan as active agent and methacrylated polymerizable Irgasan when added to experimental dental resin composites.

Materials and Methods

A delivery system based on novel polymeric hollow beads, loaded with Irgasan and methacrylated polymerizable Irgasan as active agents were used to manufacture three commonly formulated experimental resin composites. The non-modified resin was used as standard (ST). Material A contained the delivery system providing 4 % (m/m) Irgasan, material B contained 4 % (m/m) methacrylated Irgasan and material C 8 % (m/m) methacrylated Irgasan. Flexural strength (FS), flexural modulus (FM), water sorption (WS), solubility (SL), surface roughness R_a, polymerization shrinkage, contact angle Θ, total surface free energy γ_S and its apolar γ_S ^LW, polar γ_S ^AB, Lewis acid γ_S ⁺and base γ_S ^- term as well as bacterial viability were determined. Significance was p < 0.05.

Results

The materials A to C were not unacceptably influenced by the modifications and achieved the minimum values for FS, WS and SL as requested by EN ISO 4049 and did not differ from ST what was also found for R_a. Only A had lower FM than ST. Θ of A and C was higher and γ_S ^AB of A and B was lower than of ST. Materials A to C had higher γ_S ⁺ than ST. The antibacterial effect of materials A to C was significantly increased when compared with ST meaning that significantly less vital cells were found.

Conclusion

Dental resin composites with small quantities of a novel antibacterially doped delivery system or with an antibacterial monomer provided acceptable physical properties and good antibacterial effectiveness. The sorption material being part of the delivery system can be used as a vehicle for any other active agent.     

Will an Unsupervised Self-Testing Strategy for HIV Work in Health Care Workers of South Africa? A Cross Sectional Pilot Feasibility Study

Background

In South Africa, stigma, discrimination, social visibility and fear of loss of confidentiality impede health facility-based HIV testing. With 50% of adults having ever tested for HIV in their lifetime, private, alternative testing options are urgently needed. Non-invasive, oral self-tests offer a potential for a confidential, unsupervised HIV self-testing option, but global data are limited.

Methods

A pilot cross-sectional study was conducted from January to June 2012 in health care workers based at the University of Cape Town, South Africa. An innovative, unsupervised, self-testing strategy was evaluated for feasibility; defined as completion of self-testing process (i.e., self test conduct, interpretation and linkage). An oral point-of-care HIV test, an Internet and paper-based self-test HIV applications, and mobile phones were synergized to create an unsupervised strategy. Self-tests were additionally confirmed with rapid tests on site and laboratory tests. Of 270 health care workers (18 years and above, of unknown HIV status approached), 251 consented for participation.

Findings

Overall, about 91% participants rated a positive experience with the strategy. Of 251 participants, 126 evaluated the Internet and 125 the paper-based application successfully; completion rate of 99.2%. All sero-positives were linked to treatment (completion rate:100% (95% CI, 66.0–100). About half of sero-negatives were offered counselling on mobile phones; completion rate: 44.6% (95% CI, 38.0–51.0). A majority of participants (78.1%) were females, aged 18–24 years (61.4%). Nine participants were found sero-positive after confirmatory tests (prevalence 3.6% 95% CI, 1.8–6.9). Six of nine positive self-tests were accurately interpreted; sensitivity: 66.7% (95% CI, 30.9–91.0); specificity:100% (95% CI, 98.1–100).

Interpretation

Our unsupervised self-testing strategy was feasible to operationalize in health care workers in South Africa. Linkages were successfully operationalized with mobile phones in all sero-positives and about half of the sero-negatives sought post-test counselling. Controlled trials and implementation research studies are needed before a scale-up is considered.     

A Phase 1b Randomized,Controlled, Double-Blinded Dosage-Escalation Trial to Evaluate the Safety,Reactogenicity and Immunogenicity of an Adenovirus Type 35 Based Circumsporozoite Malaria Vaccine in Burkinabe Healthy Adults 18 to 45 Years of Age

Background

Ad35.CS.01 is a pre-erythrocytic malaria candidate vaccine. It is a codon optimized nucleotide sequence representing the P. falciparum circumsporozoite (CS) surface antigen inserted in a replication deficient Adenovirus 35 backbone. A Phase 1a trial has been conducted in the USA in naïve adults and showed that the vaccine was safe. The aim of this study is to assess the safety and immunogenicity of ascending dosages in sub Saharan Africa.

Methods

A double blind, randomized, controlled, dose escalation, phase Ib trial was conducted in a rural area of Balonghin, the Saponé health district (Burkina Faso). Forty-eight healthy adults aged 18-45 years were randomized into 4 cohorts of 12 to receive three vaccine doses (day 0, 28 and 84) of 10⁹, 10¹⁰, 5X10¹⁰, 10¹¹ vp of Ad35.CS.01 or normal saline by intra muscular injection. Subjects were monitored carefully during the 14 days following each vaccination for non serious adverse events. Severe and serious adverse events were collected throughout the participant study duration (12 months from the first vaccination). Humoral and cellular immune responses were measured on study days 0, 28, 56, 84, 112 and 140.

Results

Of the forty-eight subjects enrolled, forty-four (91.7%) received all three scheduled vaccine doses. Local reactions, all of mild severity, occurred in thirteen (27.1%) subjects. Severe (grade 3) laboratory abnormalities occurred in five (10.4%) subjects. One serious adverse event was reported and attributed to infection judged unrelated to vaccine. The vaccine induced both antibody titers and CD8 T cells producing IFNγ and TNFα with specificity to CS while eliciting modest neutralizing antibody responses against Ad35.

Conclusion

Study vaccine Ad35.CS.01 at four different dose levels was well-tolerated and modestly immunogenic in this population. These results suggest that Ad35.CS.01 should be further investigated for preliminary efficacy in human challenge models and as part of heterologous prime-boost vaccination strategies.

Trial Registration

ClinicalTrials.gov NCT01018459 http://clinicaltrials.gov/ct2/show/NCT01018459     

Methane-Carbon Flow into the Benthic Food Web at Cold Seeps – A Case Study from the Costa Rica Subduction Zone

Cold seep ecosystems can support enormous biomasses of free-living and symbiotic chemoautotrophic organisms that get their energy from the oxidation of methane or sulfide. Most of this biomass derives from animals that are associated with bacterial symbionts, which are able to metabolize the chemical resources provided by the seeping fluids. Often these systems also harbor dense accumulations of non-symbiotic megafauna, which can be relevant in exporting chemosynthetically fixed carbon from seeps to the surrounding deep sea. Here we investigated the carbon sources of lithodid crabs (Paralomis sp.) feeding on thiotrophic bacterial mats at an active mud volcano at the Costa Rica subduction zone. To evaluate the dietary carbon source of the crabs, we compared the microbial community in stomach contents with surface sediments covered by microbial mats. The stomach content analyses revealed a dominance of epsilonproteobacterial 16S rRNA gene sequences related to the free-living and epibiotic sulfur oxidiser Sulfurovum sp. We also found Sulfurovum sp. as well as members of the genera Arcobacter and Sulfurimonas in mat-covered surface sediments where Epsilonproteobacteria were highly abundant constituting 10% of total cells. Furthermore, we detected substantial amounts of bacterial fatty acids such as i-C15∶0 and C17∶1ω6c with stable carbon isotope compositions as low as −53‰ in the stomach and muscle tissue. These results indicate that the white microbial mats at Mound 12 are comprised of Epsilonproteobacteria and that microbial mat-derived carbon provides an important contribution to the crab''s nutrition. In addition, our lipid analyses also suggest that the crabs feed on other ¹³C-depleted organic matter sources, possibly symbiotic megafauna as well as on photosynthetic carbon sources such as sedimentary detritus.