Domestication-induced reduction in eye size revealed in multiple common garden experiments: The case of Atlantic salmon (Salmo salar L.)

Domestication leads to changes in traits that are under directional selection in breeding programmes, though unintentional changes in nonproduction traits can also arise. In offspring of escaping fish and any hybrid progeny, such unintentionally altered traits may reduce fitness in the wild. Atlantic salmon breeding programmes were established in the early 1970s, resulting in genetic changes in multiple traits. However, the impact of domestication on eye size has not been studied. We measured body size corrected eye size in 4000 salmon from six common garden experiments conducted under artificial and natural conditions, in freshwater and saltwater environments, in two countries. Within these common gardens, offspring of domesticated and wild parents were crossed to produce 11 strains, with varying genetic backgrounds (wild, domesticated, F1 hybrids, F2 hybrids and backcrosses). Size-adjusted eye size was influenced by both genetic and environmental factors. Domesticated fish reared under artificial conditions had smaller adjusted eye size when compared to wild fish reared under identical conditions, in both the freshwater and marine environments, and in both Irish and Norwegian experiments. However, in parr that had been introduced into a river environment shortly after hatching and sampled at the end of their first summer, differences in adjusted eye size observed among genetic groups were of a reduced magnitude and were nonsignificant in 2-year-old sea migrating smolts sampled in the river immediately prior to sea entry. Collectively, our findings could suggest that where natural selection is present, individuals with reduced eye size are maladapted and consequently have reduced fitness, building on our understanding of the mechanisms that underlie a well-documented reduction in the fitness of the progeny of domesticated salmon, including hybrid progeny, in the wild

Studies on the biology of juvenile European eels (Anguilla anguilla L.) in Irish rivers

Over the past three decades recruitment of European eel (Anguilla anguilla L.) to inland waters has declined by more than 95%. The causes of this decline are still unclear although a number of factors are thought to have a contributory effect including pollution, habitat loss, climatic changes in the ocean, overfishing and the spread of non-indigenous parasites and disease. In this study, undertaken from 2008 to 2010, the abundance, timing and seasonal duration of eel recruitment was investigated on the Shannon, Erne and Lee river systems, where the natural connectivity of these rivers is interrupted by hydroelectric dams and regulating weirs. Catches of juvenile eels at fixed traps downstream of these structures were monitored and the length, weight and age of eels sampled were analysed. Total catch varied between years at each site and were generally low. The timing of the migration showed considerable interannual variability as well as differences between sites. Mean eel length was greater for eels trapped further upstream from the tidal limit of estuaries. At the Parteen regulating weir on the River Shannon variation in the juvenile eel catch was analysed in relation to environmental factors using multiple regression appropriate to time series data. Factors included in the regression model which explained a statistically significant portion of the variation in juvenile eel catch were: day length, flow, water temperature, moon fullness and year. An exceptional peak in the eel catch was recorded in August 2008 following very heavy rainfall. The catch recorded during August 2008 accounted for 51% of the total catch for the period 2008 to 2010. Juvenile eels sampled at fixed traps were examined for the presence of Anguillicoloides crassus, an introduced Asian parasitic nematode of eels that can affect swimbladder function. Investigations on the infection levels in yellow and silver eels are frequently reported but there is a paucity of information regarding infection of juvenile eels. Prevalence and intensity of infection was determined. Relationships between host length and condition and the infection intensity were also investigated. Juvenile eels sampled from the River Lee (N = 73) were found to be uninfected. Prevalence recorded for a sample from the Erne (N = 44) was 14% and mean intensity of infection was 1.0. On the River Shannon, samples (N = 498) were collected at the Ardnacrusha dam and Parteen regulating weir during 2008, 2009 and 2010. At Ardnacrusha elvers were more frequent in the trap catch and mean prevalence ranged from 23-66% with mean intensity ranging from 1.35 to 1.94. At Parteen, where larger juvenile eels are predominant in the trap catch, mean prevalence ranged from 59-66% and mean intensity ranged from 1.90 to 2.00. There was no significant correlation between the number of Anguillicoloides present and the condition factor of the eels sampled. Anguillicoloides infection of migrating juvenile eels used for stocking represents a mechanism of dispersal for the parasite to upstream habitat. Measures to mitigate the effect of hydroelectric dams and regulating weirs on juvenile eel migration include implementation of trap and transport programmes. Evaluation of trap efficiency is a necessary step in improving the effectiveness of these programmes. In this study the size selectivity of traps with different substrate types was investigated at the Parteen regulating weir. Brush substrates of varying densities were shown to facilitate the capture of a wider size range of migrating eels. The importance of the location of a trap to its effectiveness was also demonstrated. Mark and recapture experiments were conducted at the Parteen regulating weir using visible implant elastomer (VIE) marking. Recapture rates of marked eels (N=1814) ranged from 0-16.25% and varied depending on release location. This low and variable recapture rate reflects the variable tendency to migrate exhibited by juvenile eels and the importance of the location of a trap to its effectiveness. Juvenile eels entering the trap at the Parteen regulating weir were monitored by closed-circuit video over three consecutive 24 hour periods. A pronounced diel pattern in activity was observed with 98% of juvenile eels entering the trap between dusk and dawn

A Survey of the Hadamard Maximal Determinant Problem

In a celebrated paper of 1893, Hadamard established the maximal determinant theorem, which establishes an upper bound on the determinant of a matrix with complex entries of norm at most $1$. His paper concludes with the suggestion that mathematicians study the maximum value of the determinant of an $n \times n$ matrix with entries in $\{ \pm 1\}$. This is the Hadamard maximal determinant problem. This survey provides complete proofs of the major results obtained thus far. We focus equally on upper bounds for the determinant (achieved largely via the study of the Gram matrices), and constructive lower bounds (achieved largely via quadratic residues in finite fields and concepts from design theory). To provide an impression of the historical development of the subject, we have attempted to modernise many of the original proofs, while maintaining the underlying ideas. Thus some of the proofs have the flavour of determinant theory, and some appear in print in English for the first time. We survey constructions of matrices in order $n \equiv 3 \mod 4$, giving asymptotic analysis which has not previously appeared in the literature. We prove that there exists an infinite family of matrices achieving at least $0.48$ of the maximal determinant bound. Previously the best known constant for a result of this type was $0.34$.Comment: 28 pages, minor modification

Repeatability of two-dimensional chemical shift imaging multivoxel proton magnetic resonance spectroscopy for measuring human cerebral choline-containing compounds

AIM To investigate the repeatability of proton magnetic resonance spectroscopy in the in vivo measurement of human cerebral levels of choline-containing compounds (Cho). METHODS Two consecutive scans were carried out in six healthy resting subjects at a magnetic field strength of 1.5 T. On each occasion, neurospectroscopy data were collected from 64 voxels using the same 2D chemical shift imaging (CSI) sequence. The data were analyzed in the same way, using the same software, to obtain the values for each voxel of the ratio of Cho to creatine. The Wilcoxon related-samples signed-rank test, coefficient of variation (CV), repeatability coefficient (RC), and intraclass correlation coefficient (ICC) were used to assess the repeatability. RESULTS The CV ranged from 2.75% to 33.99%, while theminimum RC was 5.68%. There was excellent reproducibility, as judged by significant ICC values, in 26 voxels. Just three voxels showed significant differences according to the Wilcoxon related-samples signed-rank test. CONCLUSION It is therefore concluded that when CSI multivoxel proton neurospectroscopy is used to measure cerebral choline-containing compounds at 1.5 T, the reproducibility is highly acceptable

Objective Assessment of Patient Inhaler User Technique Using an Audio-Based Classification Approach

Abstract Many patients make critical user technique errors when using pressurised metered dose inhalers (pMDIs) which reduce the clinical efficacy of respiratory medication. Such critical errors include poor actuation coordination (poor timing of medication release during inhalation) and inhaling too fast (peak inspiratory flow rate over 90 L/min). Here, we present a novel audio-based method that objectively assesses patient pMDI user technique. The Inhaler Compliance Assessment device was employed to record inhaler audio signals from 62 respiratory patients as they used a pMDI with an In-Check Flo-Tone device attached to the inhaler mouthpiece. Using a quadratic discriminant analysis approach, the audio-based method generated a total frame-by-frame accuracy of 88.2% in classifying sound events (actuation, inhalation and exhalation). The audio-based method estimated the peak inspiratory flow rate and volume of inhalations with an accuracy of 88.2% and 83.94% respectively. It was detected that 89% of patients made at least one critical user technique error even after tuition from an expert clinical reviewer. This method provides a more clinically accurate assessment of patient inhaler user technique than standard checklist methods

Domestication-induced reduction in eye size revealed in multiple common garden experiments: The case of Atlantic salmon (Salmo salar L.)

Domestication leads to changes in traits that are under directional selection in breeding programmes, though unintentional changes in nonproduction traits can also arise. In offspring of escaping fish and any hybrid progeny, such unintentionally altered traits may reduce fitness in the wild. Atlantic salmon breeding programmes were established in the early 1970s, resulting in genetic changes in multiple traits. However, the impact of domestication on eye size has not been studied. We measured body size corrected eye size in 4000 salmon from six common garden experiments conducted under artificial and natural conditions, in freshwater and saltwater environments, in two countries. Within these common gardens, offspring of domesticated and wild parents were crossed to produce 11 strains, with varying genetic backgrounds (wild, domesticated, F1 hybrids, F2 hybrids and backcrosses). Size-adjusted eye size was influenced by both genetic and environmental factors. Domesticated fish reared under artificial conditions had smaller adjusted eye size when compared to wild fish reared under identical conditions, in both the freshwater and marine environments, and in both Irish and Norwegian experiments. However, in parr that had been introduced into a river environment shortly after hatching and sampled at the end of their first summer, differences in adjusted eye size observed among genetic groups were of a reduced magnitude and were nonsignificant in 2-year-old sea migrating smolts sampled in the river immediately prior to sea entry. Collectively, our findings could suggest that where natural selection is present, individuals with reduced eye size are maladapted and consequently have reduced fitness, building on our understanding of the mechanisms that underlie a well-documented reduction in the fitness of the progeny of domesticated salmon, including hybrid progeny, in the wild