To determine the temperature preference for juvenile Westslope Cutthroat Trout, we conducted an experiment using an automated shuttlebox design (Loligo® Systems), whereby fish regulated ambient ...temperature by freely moving between cooling and warming chambers. The duration of the acclimation and experimental periods and effect of photoperiod were also evaluated, guiding future thermal preference experiments.
Abstract
Temperature preference for various fishes has often been used as a proxy of optimal temperature for growth and metabolism due to the ease of obtaining preferred temperature zones in laboratory experiments. Several laboratory designs and methods have been proposed to examine preferred temperature zones, however, differences between them (i.e. thermal gradients vs. static temperatures in chambers and duration of acclimation/experimental periods) have led to varying measurements, precluding comparisons between experiments, species and/or life-stages. Juvenile Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi), a species listed as threatened in Alberta and of special concern in British Columbia, were tested in an automated shuttlebox experimental design (Loligo® Systems) to determine average and ranges of temperature preference (Tpref) and occupied temperatures. Previous lab studies suggested that Westslope Cutthroat Trout (WCT) prefer temperatures around 15°C, however, we found that average daytime Tpref for lab-reared juvenile WCT was substantially higher at 18.6°C, with occupied temperatures ranging between 11.9°C and 26.0°C throughout the duration of trials. This seems to indicate that despite constant lab-rearing conditions of 12°C, juvenile WCT may tolerate and even prefer warmer water temperatures. The duration of the acclimation period (1h, 12 h and 24 h) did not have an effect on Tpref, however, Tpref differed significantly for variable trial durations (12 h, 24 h and 36 h). A closer look at thermal trends throughout trials revealed that photoperiod significantly influenced Tpref, as nighttime temperature preference reached consistently 26°C. Collectively, these results suggest that shuttlebox experiments on WCT need to take into account the photoperiod, as behaviour may drive Tpref more so than the duration of acclimation periods.
The possibility of calculating useful microbial community diversity indices from environmental polar lipid fatty acid and 16S rDNA PCR-DGGE data was investigated. First, the behavior of the species ...richness, Shannon’s, and Simpson’s diversity indices were determined on polar lipid fatty acid profiles of 115 pure cultures, communities constructed from those profiles with different numbers of species, and constructed communities with different distributions of species. Differences in the species richness of these artificial communities was detected by all three diversity indices, but they were insensitive to the evenness of the distribution of species. Second, data from a field experiment with substrate addition to soil was used to compare the methods developed for lipid- and DNA-based diversity indices. Very good agreement was found between indices calculated from environmental polar lipid fatty acid profiles and denaturing gradient gel electrophoresis profiles from matched samples (Pearson’s correlation coefficient
r=0.95–0.96). A method for data pre-treatment for diversity calculations is described.
The manufacture of fine particles of two steroid drugsprogesterone and medroxyprogesterone acetatehas been investigated through the rapid expansion of supercritical solutions (RESS). The motivation ...was the production of particles with improved characteristics for use in the pharmaceutical industry. Solubility data for each drug in supercritical CO2 were measured prior to performing the RESS experiments as these data are essential for accurate experimental design. The solubility data were measured using a dynamic apparatus at pressures between 100 and 240 bar and at 313.1 and 333.1 K. Particles were manufactured by expanding a solution of supercritical CO2 saturated with drug through a micronozzle to pressures of 50 bar or less. A sufficient amount of particles was manufactured to allow particle characterization tests to be completed. Particle size, particle size distribution, and specific surface area were used as assessment measures to compare the product samples obtained in different experimental conditions. The RESS technique produced particles that were significantly smaller than existing samples manufactured using jet-milling.
We present a determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| using the decay B → Dℓνℓ (ℓ = e,μ) based on 711 fb–1 of e+e– → Υ(4S) data recorded by the Belle ...detector and containing 772 × 106 BB¯ pairs. Here, one B meson in the event is fully reconstructed in a hadronic decay mode, while the other, on the signal side, is partially reconstructed from a charged lepton and either a D+ or D0 meson in a total of 23 hadronic decay modes. The isospin-averaged branching fraction of the decay B → Dℓνℓ is found to be B(B0 → D–ℓ+νℓ) = (2.31 ± 0.03(stat) ± 0.11(syst))%. Analyzing the differential decay rate as a function of the hadronic recoil with the parametrization of Caprini, Lellouch, and Neubert and using the form-factor prediction G(1) = 1.0541 ± 0.0083 calculated by FNAL/MILC, we obtain ηEW|Vcb| = (40.12 ± 1.34) × 10–3, where ηEW is the electroweak correction factor. Alternatively, assuming the model-independent form-factor parametrization of Boyd, Grinstein, and Lebed and using lattice QCD data from the FNAL/MILC and HPQCD collaborations, we find ηEW|Vcb| = (41.10 ± 1.14) × 10–3.
The antipredator behaviour of prey organisms is shaped by a series of threat-sensitive trade-offs between the benefits associated with successful predator avoidance and a suite of other ...fitness-related behaviours such as foraging, mating and territorial defence. Recent research has shown that the overall intensity of antipredator response and the pattern of threat-sensitive trade-offs are influenced by current conditions, including variability in predation risk over a period of days to weeks. In this study, we tested the hypothesis that long-term predation pressure will likewise have shaped the nature of the threat-sensitive antipredator behaviour of wild-caught Trinidadian guppies (Poecilia reticulata). Female guppies were collected from two populations that have evolved under high- and low-predation pressure, respectively, in the Aripo River, Northern Mountain Range, Trinidad. Under laboratory conditions, we exposed shoals of three guppies to varying concentrations of conspecific damage-released chemical alarm cues. Lower Aripo (high-predation) guppies exhibited the strongest antipredator response when exposed to the highest alarm cue concentration and a graded decline in response intensity with decreasing concentrations of alarm cue. Upper Aripo (low-predation) guppies, however, exhibited a nongraded (hypersensitive) response pattern. Our results suggest that long-term predation pressure shapes not only the overall intensity of antipredator responses of Trinidadian guppies but also their threat-sensitive behavioural response patterns.
Breathlessness remains a challenging symptom, common to a multitude of malignant and non-malignant diseases, for which there are limited effective therapies once disease control is optimized. The ...American Thoracic Society (ATS) statement on dyspnoea reports that: (i) progress in dyspnoea management has not matched progress in elucidating underlying mechanisms; (ii) there is a critical need for interdisciplinary translational research to connect dyspnoea mechanisms with treatments; and (iii) there is a need to validate dyspnoea measures as patient-reported outcomes for clinical trials. Research into the many dimensions of breathlessness and its significance to patients and their carers has increased in recent years. This meeting is convened yearly to bring together researchers across various disciplines including respiratory medicine, anaesthetics, medical humanities, engineering, and palliative care, to further understanding of the symptom, discuss new techniques and advances in research, and pave the way forward for future studies and interventions. The presentations generated much vibrant discussion amongst the multidisciplinary attendees and highlighted areas where care for breathless patients could be improved. This is a positive time for breathlessness research, with several ATS research priorities being addressed and it is clear that further studies and ensuing interventions are on the horizon.
Community attributes result from processes operating at various spatial scales. The hierarchic organisation of rivers and the prevailing hypotheses about the variables that affect fish communities ...make lotic ecosystems particularly suitable to study processes taking place across spatial scales. The general goal of this study was to investigate how river flow regime and local habitat properties explain and predict fish community attributes in unregulated and regulated rivers. Our objectives were: (1) to identify the hydrological indices that best describe the flow regimes of river segments subjected to different regulation types (unregulated, run-of-the-river, storage, and peaking), and; (2) to estimate the relative importance of hydrological indices (river scale), and water depth, water velocity, and substrate composition (local scale) in explaining and predicting local fish community attributes (species richness, total density, and total biomass). We surveyed 880 sites (~300 m
2
) in 25 rivers (14 unregulated and 11 regulated) located in six physiographic regions of Canada. Based on a discriminant function analysis, nine hydrological indices were selected to represent river flow regime. Models of fish community attributes were developed using linear mixed-models (LMM) by nesting sites within rivers and regions. A few hydrological indices along with habitat properties predicted fish community attributes at the site scale (0.43< cross-validation
R
C
V
2
<
0.66
). Specific hydrological indices and local habitat properties can be managed to preserve fish community attributes in regulated rivers. Combining variables associated with different scales in a LMM was a powerful and efficient way to model fish community attributes and produced reliable predictive models.
Physiological status of microbial mats of the Ebro Delta (Tarragona, Spain) based on the extraction of lipids considered "signature lipid biomarkers" (SLB) from the cell membranes and walls of ...microorganisms has been analyzed. Data from a day-night cycle show significant differences in viable cells countings (PLFA cells counts) ranging from$1.5\times 10^{10}$to 5.0× 1010cells g-1of sediment. Minimum values were observed at 18:00 and 6:00, when physicochemical conditions change drastically. The diversity of the microbial community was assessed by GC/MS analysis of phospholipid fatty acids (PLFA). The ratio of PLFA, representative of Gram-negative bacteria, comprises 47.8% of the total PLFA of the microbial mat community. The remaining PLFA was representative of Gram-positive (10.0%), anaerobic (5.7%), and eukaryotic microorganisms (5.7%), and other common lipids. Two different approaches were used as a comparative study to assess the physiological status of the microbial mats. Two parameters (cyclopropane fatty acids/ω7c monoenoic fatty acids, and measurement of the trans/cis monoenoic PLFA ratio) showed a minimum at midnight, suggesting the highest microbial activity. Higher values were observed at 18:00 and 6:00, coinciding with lower PLFA cell counts.
The solubility of naproxen ((S)-6-methoxy- alpha -methyl-2-naphthaleneacetic acid) in supercritical CO sub(2) was determined at 313.1, 323.1, and 333.1 K. The influence of six polar cosolvents, ethyl ...acetate, acetone, methanol, ethanol, 1-propanol, and 2-propanol, was studied at concentrations of 1.75, 3.5, and 5.25 mol%. The solubility enhancement with these cosolvents is considerable, and the cosolvent effect increases in the order ethyl acetate, acetone, methanol, ethanol, 2-propanol, 1-propanol. A nonlinear increase in solubility is observed with an increase in cosolvent concentration. The use of the Peng-Robinson and Soave-Redlich-Kwong equations of state to correlate these ternary systems requires the use of negative binary interaction parameters indicating strong interactions between naproxen and the cosolvents. The cosolvent effects cannot be explained by any one physical property of the cosolvents but appear to be influenced by hydrogen bonding ability as determined from solvatochromic parameters as well as the relative distance from the CO sub(2)-cosolvent binary critical point.
Biofilms in the drinking water distribution system can protect pathogens from disinfection and provide the inocula for periodic infestations. Assessing these biofilms can be difficult, as the plate ...counts of pelagic bacteria may bear little relationship to the biofilm load. Culturing the water at the outlet most often does not reflect the biofilm composition. Herein we show that analysis of polar lipid fatty acids recovered from biofilms on devices possessing a large surface area provides quantitative analysis of the viable biomass, community composition, and nutritional status that is independent of the recovery and culturability. Analysis of the polar lipid fatty acids indicated the biofilm contained a stressed and predominantly Gram-negative bacterial community. The composition was not significantly different whether collected in the summer or winter. Oxirane (epoxide) fatty acids were detected in the polar lipids of the biofilm, indicating exposure to chlorine and loss of viability within the biofilm. Tests with monocultures of
Escherichia coli and
Sphingomonas paucimobilis exposed to chlorine resulted in oxirane fatty acid generation and rendered them nonculturable.
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