First Week Of Exposure Research Articles

PET imaging of dopamine transporters and D2/D3 receptors in female monkeys: effects of chronic cocaine self-administration.

Brain imaging studies using positron emission tomography (PET) have shown that long-term cocaine use is associated with lower levels of dopamine (DA) D2/D3 receptors (D2/D3R); less consistent are the effects on DA transporter (DAT) availability. However, most studies have been conducted in male subjects (humans, monkeys, rodents). In this study, we used PET imaging in nine drug-naïve female cynomolgus monkeys to determine if baseline measures of DAT, with [18F]FECNT, and D2/D3R availability, with [11C]raclopride, in the caudate nucleus, putamen and ventral striatum were associated with rates of cocaine self-administration and if these measures changed during long-term (~13 months) cocaine self-administration and following time-off (3-9 months) from cocaine. Cocaine (0.2 mg/kg/injection) and 1.0 g food pellets were available under a multiplefixed-interval (FI) 3-min schedule of reinforcement. In contrast to what has been observed in male monkeys, baseline D2/D3R availability was positively correlated with rates of cocaine self-administration only during the first week of exposure; DAT availability did not correlate with cocaine self-administration. D2/D3R availability decreased ~20% following cumulative intakes of 100 and 1000 mg/kg cocaine; DAT availability did not significantly change. These reductions in D2/D3R availability did not recover over 9 months of time-off from cocaine. To determine if these reductions were reversible, three monkeys were implanted with osmotic pumps that delivered raclopride for 30 days.We found that chronic treatment with the D2/D3R antagonist raclopride increased D2/D3R availability in the ventral striatum but not in the other regions when compared to baseline levels. Over 13 months of self-administration, tolerance did not develop to the rate-decreasing effects of self-administered cocaine on food-reinforced responding, but number of injections and cocaine intake significantly increased over the 13 months. These data extend previous findings to female monkeys and suggest sex differences in the relationship between D2/D3R availability related to vulnerability and long-term cocaine use.

A rare occurrence of Anaplasma-associated peritonitis.

Anaplasmosis or human granulocytic anaplasmosis is a tick-borne illness caused by the bacteria, Anaplasma phagocytophilum, resulting from an infected tick bite. Examination of a blood smear within the first week of exposure may show microcolonies of anaplasmae (morulae) in the cytoplasm of neutrophils that are highly suggestive of anaplasmosis but not definitive. We present the first case describing Anaplasma-related peritonitis and morulae in peritoneal fluid granulocytes in a peritoneal dialysis patient who developed anaplasmosis.

Symbiodiniaceae in and ex hospite have differential physiological responses under different heat stress scenarios

ABSTRACT Extreme seawater temperatures are linked to increasingly frequent cnidarian bleaching, a breakdown of the symbiosis between host and endosymbiotic dinoflagellates. This can be driven by several anthropogenic stressors, of which seawater warming is a major and frequent one. It remains unclear whether this is caused by intrinsic properties of the host or exclusively by the symbiont. This study investigates the response to elevated temperatures of dinoflagellate symbionts in and ex hospite, particularly to find out whether thermal tolerance differs between endosymbionts and free-living micro-algae. Maximum quantum yield of photosystem II (Fv/Fm ) and symbiont cell density were measured in seven different cnidarian species and five cultures of isolated endosymbionts subjected to temperatures of 26°C (control), 30°C and 34°C for 21 days. Isolated dinoflagellate cells showed a susceptibility to elevated temperatures of 30°C, evidenced by a decrease in photochemical efficiency and cell density of the cultures, as well as a progressive disintegration of cellular structures and loss of pigmentation of all but two cultures during the first week of exposure. Bleaching of coral holobionts at 30°C could be explained by reduced density of algae cells in host tissue. This effect was particularly evident in soft corals. Exposure to 34°C resulted in drastic bleaching of stony coral species, anemones and jellyfish, and even the death of soft corals. Data from this study show different responses to elevated thermal conditions across several species and different genera of symbionts and emphasize the important role of dinoflagellate symbionts in the holobiont response to elevated seawater temperatures.

Effects of turbidity, temperature and predation cue on the stress response of juvenile delta smelt.

The San Francisco Estuary (SFE) is one of the most degraded ecosystems in the United States, and organisms that inhabit it are exposed to a suite of environmental stressors. The delta smelt (Hypomesus transpacificus), a small semi-anadromous fish endemic to the SFE and considered an indicator species, is close to extinction in the wild. The goal of this study was to investigate how environmental alterations to the SFE, such as reductions in turbidities, higher temperatures and increased prevalence of invasive predators affect the physiology and stress response of juvenile delta smelt. Juvenile delta smelt were exposed to two temperatures (17 and 21°C) and two turbidities (1-2 and 10-11 NTU) for 2 weeks. After the first week of exposure, delta smelt were exposed to a largemouth bass (Micropterus salmoides) predator cue at the same time every day for 7 days. Fish were measured and sampled on the first (acute) and final (chronic) day of exposures to predator cues and later analyzed for whole-body cortisol, glucose, lactate, and protein. Length and mass measurements were used to calculate condition factor of fish in each treatment. Turbidity had the greatest effect on juvenile delta smelt and resulted in reduced cortisol, increased glucose and lactate, and greater condition factor. Elevated temperatures reduced available energy in delta smelt, indicated by lower glucose and total protein, whereas predator cue exposure had negligible effects on their stress response. This is the first study to show reduced cortisol in juvenile delta smelt held in turbid conditions and adds to the growing data that suggest this species performs best in moderate temperatures and turbidities. Multistressor experiments are necessary to understand the capacity of delta smelt to respond to the multivariate and dynamic changes in their natural environment, and results from this study should be considered for management-based conservation efforts.

Juvenile exposure and adult risk assessment with single versus repeated exposure of melphalan in the germ cells of male SD rat: Deciphering the molecular mechanisms

Melphalan significantly contributes to the increase in childhood cancer survival rate. It acts as a gonadotoxic agent and leads to testes damage, dysbalance in gonadal hormones, and impairment in the germ cell proliferation. Therefore, it might be a potent threat to male fertility in individuals who have undergone melphalan treatment during childhood cancer. However, the molecular mechanisms of melphalan-induced gonadal damage are not yet fully explored and they need to be investigated to determine the benefit-risk profile. In the present study, juvenile male SD rats were subjected to single and intermittent cycles of melphalan exposure in a dose-dependent (0.375, 0.75 and 1.5 mg/kg) manner. Methods of end-points evaluations were quantification of micronuclei formation in peripheral blood, sperm count, sperm motility and head morphology, sperm and testicular DNA damage, histological studies in testes, oxidative/nitrosative stress parameters. A single cycle of exposure at high dose (1.5 mg/kg) produced significant effect on micronuclei formation only after the first week of exposure, whereas failed to produce significant effect at the end of the sixth week. Intermittent cycles of exposure at the dose of 1.5 mg/kg produced significant alterations in all the parameters (micronuclei in peripheral blood, testes and epididymides weight and length, MDA, GSH and nitrite levels, sperm count and motility, sperm head morphology, testicular and sperm DNA damage, protein expression in testes and histological parameters). So, time of exposure as well as the amount of exposure (total dosage administered) is critical in determining the magnitude of the damage in germ cell risk assessment.

Hematological and Ventilatory Responses to a 3900 M Altitude Sojourn in an Elite Wheelchair-marathoner

This case study aimed to report blood markers and resting respiratory rate (RR) oscillations at sea level, during a 5-wk 3900 m altitude sojourn, and after returning to sea level in a 36-year-old professional wheelchair marathoner. Outcome measures plasma erythropoietin (EPO) concentration, hemoglobin, reticulocytes count, erythrocytes and hematocrit as well as RR were measured upon wakening 7-weeks pre-altitude, 7-days pre-altitude, 35 hours after arrival to altitude, on days 8, 15, 21, 28 and 35 at altitude, 6 and 16 days after returning to sea level. EPO increased up to 259 % (31.6 U l-1) 35 hours upon arrival at altitude and decreased below pre-altitude level (12.2 U l-1) on the 21st day of the camp (8.7 U l-1), reaching the lowest values 16 days after returning from altitude (1.9 U l-1). All blood parameters, except for reticulocytes, increased (range: +17.9 to +23.8%) after 35 days of altitude exposure. Compared to pre-altitude, RR increased during the first week of exposure to hypoxic conditions and remained elevated throughout the camp until the fifth week (5.1±0.4 vs. 9.1±1.6 and 6.6±0.8 breaths min-1; Cohen´s d = +3.4 and +2.4, respectively). A 5-wk high-altitude sojourn triggered polycythemia and elevations in RR (as indicators of effective hypoxic acclimatization) in a professional wheelchair-marathoner.

Ozone as eustress for enhancing secondary metabolites and bioactive properties in Salvia officinalis

Eliciting plants consists in the application of chemical, physical, and biological factors that induce stressful conditions, and so trigger defense mechanisms and the production of bioactive compounds and phytochemicals. In this study, the phenolic and volatile organic compound (VOCs) profiles of sage leaves under a chronic ozone (O3) exposure (120 ppb 5 h day−1 for 36 consecutive days) were investigated, elucidating also their antioxidant activity. The composition, yield, and antioxidant capacity of essential oils (EOs) obtained from sage leaves were also evaluated. Ozone exposure resulted in an overall increase of phenolic compounds. In terms of VOCs, O3 mainly reduced monoterpene emissions, while increased the production of sesquiterpenes (in both leaves and EOs). These O3-induced accumulations were triggered during the first weeks of exposure, whereas they disappeared at the last time of analysis, suggesting that sage plants lost their ability (or interest) in activating secondary metabolism under high doses of O3. The antioxidant capacity of all tested extracts resulted increased by O3 exposure. These outcomes support our speculation that the application of O3 for a limited period (i.e., a maximum of four weeks, at the investigated concentration) may become an effective biotechnological tool to improve the quality of sage leaf extracts.

Looking for the LOAEL or NOAEL Concentration of Nickel-Oxide Nanoparticles in a Long-Term Inhalation Exposure of Rats.

Rats were exposed to nickel oxide nano-aerosol at a concentration of 2.4 ± 0.4 µg/m3 in a “nose only” inhalation setup for 4 h at a time, 5 times a week, during an overall period of 2 weeks to 6 months. Based on the majority of the effects assessed, this kind of exposure may be considered as close to LOAEL (lowest observed adverse effect level), or even to NOAEL (no observed adverse effect level). At the same time, the experiment revealed genotoxic and allergic effects as early as in the first weeks of exposure, suggesting that these effects may have no threshold at all.

Morphology and kinetics of susceptible and resistant Biomphalaria alexandrina hemocytes during the first week of exposure to Schistosoma mansoni miracidia

Background: Few studies concerning Biomphalaria alexandrina (B. alexandrina) snail hemocytes’subpopulations, and their relation to the compatibility with Schistosoma mansoni (S. mansoni)’ miracidiawere performed. Manipulation of parasite development inside these snails could be applied as a controlmeasure against schistosomiasis.Objectives: Knowing that the snail hemocytes temporarily bind to the parasites, allowing the developmentof cercariae that are infective to the definitive host. This study aimed at studying the morphology andkinetics of diverse hemocytes of susceptible and resistant B. alexandrina and their participation in thesnail early immune response after challenge by S. mansoni.Material and Methods: Giemsa stained hemocytes were characterized using light microscopy. Total anddifferential hemocyte counts (THC and DHC) were calculated in the hemolymph of two groups composedof 60 susceptible and 60 resistant snails. Each group was further subdivided as 12 control pre-exposuresnails (PE) and 48 post-exposure snails (PO) to S. mansoni at different time points (6 h, 1, 3 and 7 days).THC and DHC counts were recorded by a snail hemogram.Results: Results revealed that granulocytes constituted the most common population all through theexperiment with the large dense-granulated granulocytes subpopulation being the largest-sized cellsdetected. The highly reactive subpopulations that increased in number upon exposure to S. mansoni werethe few-granulated and the large-granulated granulocytes, suggesting their possible participation in earlyparasite destruction.Conclusion: The resulting hemograms helped determine the participation of hemocyte populations andsubpopulations in the defense against S. mansoni, aiding in understanding snail compatibility patterns.Further studies to propagate transgenic B. alexandrina snails abundant in large granular granulocytesutilizing (gene editing) CRISPR-Cas9 technique are recommended. This would be required to spreadschistosome resistance traits in snail populations, thus, contributing to reduced schistosomiasistransmission in the long run.

A three-year large scale study on the risk of honey bee colony exposure to blooming sunflowers grown from seeds treated with thiamethoxam and clothianidin neonicotinoids

Despite the restriction of the use of neonicotinoids in the EU, including thiamethoxam and clothianidin, the debate over their risk on honey bees has not been fully settled. This study presents results of a three-year study working with 180 honey bee colonies in ten replicates. Colonies were sorted into three treatments (60 colonies per treatment) exposed to sunflower blooms grown from seeds treated with thiamethoxam, clothianidin and a non-treated control. Each colony was assessed at six moments: one before to exposition to sunflower, two during the exposition (short-time risk), two after exposition (medium-time risk) and one after wintering (long-time risk). The health and development of the colonies were assessed by monitoring adult bee population, brood development, status of the queen, food reserves and survival. No significant difference among treatments when raw data was considered. However, when evolution from initial status of the colony was evaluated, a significant difference was observed from the first week of exposure to sunflower blooms. In this period, the number of adult bees and the amount of brood were slightly lower in the bee hives exposed to neonicotinoids, although such differences disappeared in subsequent evaluations. The concentration of residues in samples of beebread and adult bees was at the level of ng·g−1. Magnitude of the effect of the treatment factor on the variability of colony health and development related parameters was low. The most important factor was the hive, followed by the replicate and year, and to a lesser extent the initial strength of the colonies.

Persistence of the antifungal capacity of a fraction of Jacquinia macrocarpa plant against Fusarium verticillioides after continuous exposure.

This study aimed to determine the ability of Fusarium verticillioides in developing mechanisms to counteract the antifungal effect of a fraction from Jacquinia macrocarpa plant extract (JmAF), as well as the morphological and physiological changes that occur during its exposure. The fungus was exposed to JmAF during consecutive periods. A culture sample was taken weekly to determine radial growth, spore germination and size, and fungal β-1,3-glucanase activity. The results showed that, in the beginning, the radial growth decreased by 85.8%, and spore germination was delayed. As the exposure continued, the fungus showed a recovery, to some extent, in its original characteristics. However, the radial growth of the fungus continued to be inhibited (42.9%) throughout the experiment (7weeks). The β-1,3-glucanase activity also was inhibited by 36.4% during the first week of exposure to JmAF. However, the activity was recovered after 7weeks of exposure.

Analysis of the Effectiveness and Efficiency of the VA Solution on Offshore Pipelines and Ship Materials

The analysis of the effectiveness and efficiency of Vernomia amydalina (VA) solution as an inhibitor on offshore pipeline and Ship materials (Steel) was carried out with the preparation of the specimen and the VA solution. The specimens were kept in a workable state and the VA Solution (inhibitor) prepared from 1200 g of bitter leaf was plucked, weighed and crushed separately. 600 cl of water was added to each of the crushed leaves. The mixture was put in a filter cloth and squeezed with hand to filter out the active concentration ingredients responsible for corrosion inhibition, which produced a 2 M concentration of VA extract solution. After the experiment was carried out the specimen was air-dried and weighed to determine the corrosion rate and weight loss. This was followed by the determination of the inhibitor efficiency at the different hours and at different percentage/concentration of the VA solution on the specimen. Results were obtained for different hours and at different percentage (0%, 5%, 10%, 15%, 20% and 25% inhibitor)/concentration of the VA solution and graphs plotted. It was observed that at the first week of exposure to corrosive medium there was a substantial reduction in weight of coupons but over the next three weeks there was a gradual decline in weight loss and the corrosion rate reduced evenly. It can be said that the percentage of inhibitor to corrosive medium is insufficient. From the graphs plotted, the inhibitor efficiency is considered high when the concentration of the VA solution is high, which implies a right percentage of inhibitor needs to be administered to obtain good efficiency of the solution. Hence as the weeks go by it was clear that the inhibitor was gradually losing its effectiveness. This means that inhibitors need to be added at regular intervals to sustain the effectiveness of the inhibitor. It is also of vital interest to apply the right concentration of inhibitor since CR increases at high concentrations and temperature. This process did not take into consideration moving water.

Impacts of polystyrene microplastics on Daphnia magna: A laboratory and a mesocosm study

Most research into microplastics (MPs) in freshwaters has concentrated on measurements under controlled conditions without any link to the natural environment. Here we studied the effects of a 15 μm polystyrene MP on Daphnia magna survival, growth, and reproduction in the laboratory. We also exposed fifteen 25 L freshwater mesocosms to a high concentration of the same MPs. Five were controls seeded with five species found in all ponds (mosquito, water flea, midge, spire shell and water mite), five identical but treated with 15 μm polystyrene MPs and five seeded with only mosquitoes and water fleas. The laboratory chronic toxicity test for both adults and neonate Daphnia magna revealed that effects were more related to the availability of food rather than the toxicity of MPs. In the mesocosms most of the MPs settled in the sediment after the first week of exposure. After four weeks the D. magna population decreased significantly in the MP mesocosms compared to the control mesocosms, although it subsequently recovered. There was no impact on other organisms added to the mesocosms, other than a difference in timing of lesser water boatman (Corixa punctata) colonisation, which colonised the control mesocosms in week 4 and the treated 4 weeks later. The detrivorous, sediment sifting, mayfly Leptophlebia marginata appeared in mesocosms in the fourth week of sampling and with significantly higher numbers in the MP treated mesocosm. Their activity had no significant impact on MPs in the water column, although numbers did increase above zero. The significant decline of D. magna suggests that their effect in a natural situation is unpredictable where environmental conditions and invertebrate communities may add additional stresses.

Acute Respiratory Failure Secondary to ACE Inhibitor–Induced Angioedema after Five Years of Lisinopril Therapy

Angiotensin-converting enzyme (ACE) inhibitors are amongst the commonest prescribed medications in the United States and considered to be the leading causes of drug induced angioedema. High bradykinin levels stimulate vasodilation and increased vascular permeability of the post-capillary venules and allow for plasma extravasation into the submucosal tissue, leading to angioedema. Usually, the angioedema occurs within the first week of exposure to therapy, but cases occurring after years of stable ACE inhibitor usage are not uncommon. Here, we present a 43-year-old Caucasian female who developed acute respiratory failure requiring mechanical ventilation secondary to ACEi–induced angioedema after five years of Lisinopril usage. This case will help to increase physicians’ awareness that this potentially fatal complication can still occur after years of ACE inhibitor usage.

Hematological Adaptations to Prolonged Heat Acclimation in Endurance-Trained Males.

Heat acclimation is associated with plasma volume (PV) expansion that occurs within the first week of exposure. However, prolonged effects on hemoglobin mass (Hbmass) are unclear as intervention periods in previous studies have not allowed sufficient time for erythropoiesis to manifest. Therefore, Hbmass, intravascular volumes, and blood volume (BV)-regulating hormones were assessed with 5½ weeks of exercise-heat acclimation (HEAT) or matched training in cold conditions (CON) in 21 male cyclists [(mean ± SD) age: 38 ± 9 years, body weight: 80.4 ± 7.9 kg, VO2peak: 59.1 ± 5.2 ml/min/kg]. HEAT (n = 12) consisted of 1 h cycling at 60% VO2peak in 40°C for 5 days/week in addition to regular training, whereas CON (n = 9) trained exclusively in cold conditions (<15°C). Before and after the intervention, Hbmass and intravascular volumes were assessed by carbon monoxide rebreathing, while reticulocyte count and BV-regulating hormones were measured before, after 2 weeks and post intervention. Total training volume during the intervention was similar (p = 0.282) between HEAT (509 ± 173 min/week) and CON (576 ± 143 min/week). PV increased (p = 0.004) in both groups, by 303 ± 345 ml in HEAT and 188 ± 286 ml in CON. There was also a main effect of time (p = 0.038) for Hbmass with +34 ± 36 g in HEAT and +2 ± 33 g in CON and a tendency toward a higher increase in Hbmass in HEAT compared to CON (time × group interaction: p = 0.061). The Hbmass changes were weakly correlated to alterations in PV (r = 0.493, p = 0.023). Reticulocyte count and BV-regulating hormones remained unchanged for both groups. In conclusion, Hbmass was slightly increased following prolonged training in the heat and although the mechanistic link remains to be revealed, the increase could represent a compensatory response in erythropoiesis secondary to PV expansion.

Impact of Adolescent Intermittent Ethanol on Noradrenergic Development

In clinical populations, adolescent alcohol drinking has been shown to increase stress sensitivity and the likelihood of developing alcohol use disorders (AUDs) in adulthood. These findings suggest pathways mediating stress‐relating behaviors are impacted by developmental exposure to alcohol, contributing to a greater risk for alcoholism and potentially stress‐induced relapse following treatment. Animal models indicate tyrosine hydroxylase (TH) neurons in the A2 region of the nucleus of the tractus solitarius (NTS) contribute to stress‐induced relapse through enhanced norepinephrine signaling, subsequently increasing neuronal activity in the bed nucleus of the stria terminalus (BNST). Previous research suggests NTS TH expression undergoes developmental changes during adolescence that may make this neuronal population susceptible to modulation by alcohol during this age. We hypothesized adolescent intermittent ethanol (AIE) exposure in mice, a standard preclinical model of adolescent binge drinking, will impact NTS TH neuron development, ultimately altering the NTS‐BNST circuitry resulting in a higher risk of AUDs in adulthood. NTS TH mRNA expression in male and female C57Bl6/J mice exposed to AIE (postnatal day [PND] 28–42) or used as air controls was quantified via qRT‐PCR at different time points (PND29, PND36, PND43, PND49, PND70). Immunohistochemistry methods were implemented to determine the impact of AIE on NTS TH neuronal activity following an ethanol challenge in adulthood (PND70). Results showed a significant increase in TH mRNA in males one day after beginning AIE (PND29) relative to air controls, while females exhibited the greatest TH expression after their first week of exposure to ethanol (PND36). In both sexes, heightened TH mRNA expression occurred earlier than expected during normal development. Surprisingly, compared to adult ethanol naïve mice, AIE decreased the ability of ethanol at doses of 2g/kg and 4g/kg to alter NTS TH neuron cFos expression at PND70 compared to control. Together, these findings suggest an enhancement of NTS TH activity early in development and reduction of ethanol sensitivity in adulthood. Studies are in progress to further delineate the mechanisms by which AIE reduces adult ethanol sensitivity and how this may alter stress‐related behaviors.Support or Funding InformationAA22937AA017823This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effects of combined brief etomidate anesthesia and postnatal stress on amygdala expression of Cl− cotransporters and corticotropin-releasing hormone and alcohol intake in adult rats

Early life stressors, including general anesthesia, can have adverse effects on adult neural and behavioral outcomes, such as disruptions in inhibitory signaling, stress responsivity and increased risk of psychiatric disorders. Here we used a rat model to determine the effects of combined exposure to etomidate (ET) neonatal anesthesia and maternal separation on adult amygdala expression of genes for corticotropin-releasing hormone (Crh) and the chloride co-transporters Nkcc1 and Kcc2, as well as ethanol intake. Male and female Sprague-Dawley rats were subjected to 2 h of ET anesthesia on postnatal days (P) 4, 5, or 6 followed by maternal separation for 3 h on P10 (ET + SEP). During the P91-P120 period rats had daily 2 h access to three 0.05% saccharin solutions containing 0%, 5%, or 10% ethanol, followed by gene expression analyses. The ET + SEP group had increased Crh mRNA levels and Nkcc1/Kcc2 mRNA ratios in the amygdala, with greater increases in Nkcc1/Kcc2 mRNA ratios in males. A moderate increase in 5% ethanol intake was evident in the ET + SEP males, but not females, after calculation of the ratio of alcohol intake between the last week and first week of exposure. In contrast, control males tended to decrease alcohol consumption during the same period. A brief exposure to ET combined with a subsequent episode of stress early in life induced significant alterations in expression of amygdala Crh, Nkcc1 and Kcc2 with greater changes in the Cl− transporter expression in males. The possibility of increased alcohol intake in the exposed males requires further confirmation using different alcohol intake paradigms.

Bioaccumulation of Polycyclic Aromatic Hydrocarbons (PAHs) by the Marine Clam, Mactra veneriformis, Chronically Exposed to Oil-Suspended Particulate Matter Aggregates.

Dispersion and biodegradation of petroleum hydrocarbons are significantly enhanced by formation of oil-suspended particulate matter aggregates (OSAs), but little is known about their adverse effects on benthic invertebrates or microbes. In this study, we investigated: (1) bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) by the marine bivalve, Mactra veneriformis and (2) changes in composition and relative abundances of microbes, during 50-d of an OSAs feeding experiment. Total concentrations of PAHs increased more rapidly during the first week of exposure, peaked at Day 30, then gradually declined to the end of experiment. While bioaccumulation of PAHs by clams varied among the 20 target compounds, two major groups of PAHs were identified by cluster analysis. One group including 3-methylphenanthrene, 1,6-dimethylphenanthrene, 1,2,6,9-tetramethylphenanthrene, and benzo[ a]anthracene showed a fairly constant rate of accumulation, while the second group including 2-methyldibenzothiophene, 2,4-dimethyldibenzothiophene, 2,4,7-trimethyldibenzothiophene, 3-methylchrysene, 6-ethylchrysene, and 1,3,6-trimethylchrysene exhibited a bell-shaped pattern. Bioaccumulation of PAHs by clams was dependent on changes in abundance of Gammaproteobacteria, indicating active degradations of hydrocarbons by selected species. Six key species included: Porticoccus litoralis, Porticoccus hydrocarbonoclasticus, Cycloclasticus spirillensus, Alcanivorax borkumensis, Alcanivorax dieselolei, and Alkalimarinus sediminis. These results are the first to demonstrate interactions of OSAs and macrofauna/microbe in oil cleanup operations.

Neurodegenerative diseases are a function of matrix breakdown: how to rebuild extracellular matrix and intracellular matrix.

Neurodegenerative diseases are a function of matrix breakdown: how to rebuild extracellular matrix and intracellular matrix.

Stress profile influences learning approach in a marine fish.

The spatial learning skills of high and low stress juvenile mulloway (Argyrosomus japonicus) were tested in a dichotomous choice apparatus. Groups of fish were formed based on background blood cortisol levels and required to learn the location of a food reward hidden in one of two compartments. Low stress fish characterised by low background levels of the stress hormone cortisol had higher activity levels and entered both rewarded and unrewarded rooms frequently. Within the first week of exposure, however, their preference for the rewarded room increased, indicative of learning. Fish that had high background levels of cortisol, in contrast, showed low levels of activity but when they chose between the two rooms they chose the rewarded room most often but showed less improvement over time. After 12 days in the apparatus, both low and high stress fish had similar ratios of rewarded vs unrewarded room entrances. Our results suggest that proactive coping styles may increase exposure to novel contexts and thus favour faster learning but at the cost of reduced initial accuracy.