Population genomics, life-history tactics, and mixed-stock subsistence fisheries in the northernmost American Atlantic salmon populations.

While Atlantic salmon (Salmo salar) of the northernmost American populations is alimentary, economically, and culturally important for Ungava Inuit communities (Nunavik, Canada) and might play a key role in the persistence of the species in a global warming context, many mysteries remain about those remote and atypical populations. Thus, our first aim was to document the genomic structure of the Nunavik populations. The second objective was to determine whether salmon only migrating to the estuary without reaching the sea, apparently unique to those populations, represent distinct populations from the typical anadromous salmons and subsequently explore the genetic basis of migratory life-history tactics in the species. Finally, the third goal was to quantify the contribution of each genetically distinct population and life-history tactic in the mixed-stock subsistence fishery of the Koksoak R. estuary. We used Genotyping-by-Sequencing to genotype 14,061 single nucleotide polymorphisms in the genome of 248 individuals from 8 source populations and 280 individuals from the Koksoak estuary mixed-stock fishery. Life-history tactics were identified by a visual assessment of scales. Results show a hierarchical structure mainly influenced by isolation-by-distance with 7 populations out of the 8 studied rivers. While no obvious structure was detected between marine and estuarine salmon within the population, we have identified genomic regions putatively associated with those migration tactics. Finally, all salmon captured in the Koksoak estuary originated from the Koksoak drainage and mostly from 2 tributaries, but no inter-annual variation in the contribution of these tributaries was found. Our results indicate, however, that both marine and estuarine salmon contribute substantially to estuarine fisheries and that there is inter-annual variation in this contribution. These findings provide crucial information for the conservation of salmon populations in a rapidly changing ecosystem, as well as for fishery management to improve the food security of Inuit communities.

Effect of physical exertion on the biological monitoring of exposure to various solvents following exposure by inhalation in human volunteers: II. n-Hexane.

This study evaluated the impact of physical exertion on two n-hexane (HEX) exposure indicators in human volunteers exposed under controlled conditions in an inhalation chamber. A group of four volunteers (two women, two men) were exposed to HEX (50 ppm; 176 mg/m(3)) according to several scenarios involving several periods when volunteers performed either aerobic (AERO), muscular (MUSC), or both AERO/MUSC types of exercise. The target intensities for 30-min exercise periods separated by 15-min rest periods were the following: REST, 50W AERO [time-weighted average intensity including resting period (TWAI): 38W], 50W AERO/MUSC (TWAI: 34W), 100W AERO/MUSC (TWAI: 63W), and 100W AERO (TWAI: 71W) for 7 hr (two 3-hr exposure periods separated by 1 hr without exposure) and 50W MUSC for 3 hr (TWAI: 31W). Alveolar air and urine samples were collected at different time intervals before, during, and after exposure to measure unchanged HEX in expired air (HEX-A) and urinary 2,5-hexanedione (2,5-HD). HEX-A levels during exposures involving AERO activities (TWAI: 38W and 71W) were significantly enhanced (approximately +14%) compared with exposure at rest. MUSC or AERO/MUSC exercises were also associated with higher HEX-A levels but only at some sampling times. In contrast, end-of-exposure (7 hr) urinary 2,5-HD (mean +/- SD) was not modified by physical exertion: 4.14 +/- 1.51 micromol/L (REST), 4.02 +/- 1.52 micromol/L (TWAI 34W), 4.25 +/- 1.53 micromol/L (TWAI 38W), 3.73 +/- 2.09 micromol/L (TWAI 63W), 3.6 +/- 1.34 micromol/L (TWAI 71W) even though a downward trend was observed. Overall, this study showed that HEX kinetics is practically insensitive to moderate variations in workload intensity; only HEX-A levels increased slightly, and urinary 2,5-HD levels remained unchanged despite the fact that all types of physical exercise increased the pulmonary ventilation rate.

Effect of physical exertion on the biological monitoring of exposure of various solvents following exposure by inhalation in human volunteers: I. Toluene.

Physical exertion (work load) has been recognized as one of several factors that can influence the kinetics of xenobiotics within the human body. This study was undertaken to evaluate the impact of physical exertion on two exposure indicators of toluene (TOL) in human volunteers exposed under controlled conditions in an inhalation chamber. A group of four volunteers (one woman, three men) were exposed to TOL (50 ppm) according to the following scenarios involving several periods during which volunteers were asked to perform either aerobic (AERO), muscular (MUSC), or both (AERO/MUSC) types of physical exercise (exercise bicycle, treadmills, pulleys). The target intensities (W) for each exercising period of 30 min--interspaced with 15 min at rest--were the following: REST, 50 W AERO (time-weighted average intensity [TWAI]: 46 watts); 50 W AERO/MUSC (TWAI: 38 watts) and 100 W AERO (TWAI: 71 watts) for 7 hours and 50 W MUSC for 3 hours (TWAI: 29 watts). Alveolar air and urine samples were collected at different time intervals before, during, and after exposure for the measurement of unchanged TOL in expired air (TOL-A) and urinary o-cresol (o-CR). Overall, the results showed that TOL-A measured during and after all scenarios involving physical activities were higher (approximately 1.4-2.0 fold) compared with exposures at rest. All scenarios involving physical exertion also resulted in increased end-of-exposure urinary o-CR (mean +/- SD): 0.9 +/- 0.1 mg/L (REST) vs. 2.0 +/- 0.1 mg/L (TWAI 46 watts). However, exposure at a TWAI of 71 watts did not further increase o-CR excretion (1.7 +/- 0.2 mg/L). This study confirms the significant effect of work load on TOL kinetics and showed that o-CR excretion increased proportionally with work load expressed as TWAI or with the estimated mean pulmonary ventilation during the period of exposure. This study also shows that exposure to TOL (50 ppm) involving a work load of around 50 W (light intensity) or lower is likely to produce urinary o-CR values that clearly exceed the current biological exposure index value for TOL.

Effect of porosity on the release kinetics of propafenone-loaded PEG-g-PLA nanoparticles.

Nanoparticle preparation by the emulsification-solvent evaporation method is a complex phenomenon. Various formulation factors can affect the internal structure and release of drug from nanoparticles (NPs). The aim of the present study is to optimize NPs of PEG-g-PLA polymer and study the effect of various factors on the porosity as well as release profile of drug-loaded NPs. Propafenone hydrochloride (Prop.HCl), a model drug, was encapsulated in NPs using different amounts of triethylamine (TEA) and initial drug loading levels. NPs were also prepared without TEA by using propafenone base (Prop). All the formulations were characterized for surface morphology, size and size distribution, encapsulation efficiency, thermal analysis, porosimetry and in vitro release studies. Encapsulation efficiency of Prop ranged between 10% and 43% and was dependent on initial drug loading as well as amount of TEA added. Porosity studies revealed different pore size distribution (PSD) for formulations with and without TEA. Formulations with higher drug loading showed greater volume contribution of small pores, higher fractal dimension suggesting more complex pore structure and slower drug release, probably due to decrease in the effective diffusion coefficient of Prop. Results suggest that formulation factors play an important role affecting the porosity and release rate of NPs. Also, fractal dimension could be one of the most important factors in determining the release behavior of NPs.

AFM study of a new carrier based on PLA and salen copolymers for gene therapy.

The aim of this study was to synthesize novel biodegradable charged polymers to be used in DNA complexation for genetic delivery in different diseases. A new copolymer of PLA and complexed Schiff bases was synthesized in a several steps. This copolymer will be used as a nanocarrier. Also, AFM comparative studies in tapping mode were performed; on cationic copolymer and on PLA-Schiff base copolymer, on non-oriented and oriented film and on the DNA-cationic complex. The results indicated a difference in the topology and on phase picture of AFM film with or without cationic charge.

Neuromotor effects of acute ethanol inhalation exposure in humans: a preliminary study.

Ethanol (ETOH) is added to unleaded gasoline to decrease environmental levels of carbon monoxide from automobiles emissions. Therefore, addition of ETOH in reformulated fuel will most likely increase and the involuntarily human exposure to this chemical will also increase. This preliminary study was undertaken to evaluate the possible neuromotor effects resulting from acute ETOH exposure by inhalation in humans. Five healthy non-smoking adult males, with no history of alcohol abuse, were exposed by inhalation, in a dynamic, controlled-environment exposure chamber, to various concentrations of ETOH (0, 250, 500 and 1,000 ppm in air) for six hours. Reaction time, body sway, hand tremor and rapid alternating movements were measured before and after each exposure session by using the CATSYS 7.0 system and a diadochokinesimeter. The concentrations of ETOH in blood and in alveolar air were also measured. ETOH was not detected in blood nor in alveolar air when volunteers were exposed to 250 and 500 ppm, but at the end of exposure to 1,000 ppm, blood and alveolar air concentrations were 0.443 mg/100ml and 253.1 ppm, respectively. The neuromotor tests did not show conclusively significant differences between the exposed and non-exposed conditions. In conclusion, this study suggests that acute exposure to ethanol at 1,000 ppm or lower or to concentrations that could be encountered upon refueling is not likely to cause any significant neuromotor alterations in healthy males.

Metabolism and toxicity of trichloroethylene in epididymis and testis.

The widespread occupational exposure to trichloroethylene (TCE) led us to test the hypothesis that TCE causes toxicity in the male reproductive system. We also investigated mechanisms mediating the potential cytotoxic response. Mice were exposed to TCE (1000 ppm) by inhalation for 6 h/day for 5 days/week for a total of 19 days. Exposure after the first week was interspersed by a "weekend." To estimate internal exposure, we measured the TCE metabolites, trichloroacetic acid (TCA) and trichloroethanol (TCOH), in urine at Days 4, 9, 14, and 19. Urinary excretion of TCOH was significantly higher than TCA; levels of TCOH and TCA significantly increased by the second and third week, respectively. Cytochrome P450 2E1 (CYP2E1), an enzyme involved in TCE metabolism, was localized in the epididymal epithelium and testicular Leydig cells, and was found at higher levels in the former than the latter. Immunoblotting confirmed that CYP2E1 protein was present in greater amounts in epididymis than in testis. p-Nitrophenol hydroxylation, a CYP2E1 catalytic activity, was also higher in the epididymis than in the testis. Chloral, a major TCE metabolite, was generated in microsomal incubations at significantly higher levels in epididymis than in testis. Antibody inhibition of CYP2E1 reduced chloral formation, which was more pronounced in epididymis than in testis. After 4 weeks of TCE exposure, damage to the epididymis was manifested as sloughing of epithelial cells. These results indicated that TCE is metabolized in the male reproductive tract, leading to adverse effects that are more severe in the epididymis than in the testis.