89 research outputs found
ARTICLE Population, sex, and ontogenetic differences in the procurrent rays of the caudal fin in threespine sticklebacks (Gasterosteus aculeatus)
Abstract: The procurrent rays occur at the leading edge of the caudal fin in bony fishes and are taxonomically variable and possibly important to caudal motion. Using radiographs, as well as stained and cleared specimens, of threespine sticklebacks (Gasterosteus aculeatus L., 1758) from lakes on Haida Gwaii, British Columbia, we examined the extent of individual and population variabilities in these rays. Among 1113 fish from Drizzle Lake, 53% of individuals were dorsoventrally asymmetric in number of rays of which 95% had greater number of rays on the dorsal lobe. On 274 fish, we also quantified dorsal to ventral (D/V) ratios of the width of the most posterior procurrent rays and found ontogenetic shifts with symmetrical D/V ratios in subadults shifting to significant dorsal biases on the larger fish (60-90 mm standard length (SL)). Males have proportionally greater dorsal bias than females of equivalent size in both number and width of procurrent rays. We examined D/V width ratios in 105 stained and cleared specimens from 13 additional allopatric lake populations on Haida Gwaii. Eight populations were symmetrical for width of dorsal and ventral rays, while three populations were ventrally biased and two populations were dorsally biased. D/V ratios were best predicted by positive associations with adult body size and negative associations with total number of gill rakers. Key words: asymmetry, caudal peduncle, Gasterosteus, Haida Gwaii, homocercal tail, intraspecific variation, procurrent rays, stickleback. Résumé : Les rayons procurrents qui se trouvent à la bordure externe de la nageoire caudale chez les poissons osseux présentent des variations taxinomiques et pourraient jouer un rôle important dans le mouvement de la queue. En utilisant des radiographies ainsi que de spécimens colorés et dépigmentés d'épinoches à trois épines (Gasterosteus aculeatus L., 1758) provenant de lacs de l'archipel Haida Gwaii (Colombie-Britannique), nous avons examiné l'ampleur des variabilités de ces rayons à l'échelle individuelle et des populations. Sur 1113 poissons du lac Drizzle, 53 % des individus présentaient une asymétrie dorsoventrale du nombre de rayons, 95 % de ce nombre comptant plus de rayons dans le lobe dorsal que dans le lobe ventral. Nous avons également quantifié les rapports de la largeur dorsale à de la largeur ventrale (D/V) des rayons procurrents les plus postérieurs de 274 poissons et noté des changements ontogénétiques consistant au passage de rapports D/V symétriques chez les subadultes à des biais dorsaux significatifs chez les poissons plus grands (60-90 mm longueur standard (LS)). Les mâles présentent un biais dorsal proportionnellement plus important que les femelles de taille équivalente, tant sur le plan du nombre que de la largeur des rayons procurrents. Nous avons examiné les rapports D/V de la largeur de 105 spécimens colorés et dépigmentés de 13 autres populations de lacs allopatriques d'Haida Gwaii. Huit populations présentaient une symétrie sur le plan de la largeur des rayons dorsaux et ventraux, alors que trois populations présentaient un biais ventral et deux populations présentaient un biais dorsal. Des associations positives avec la taille du corps pour les adultes et négatives avec le nombre total de branchicténies prédisaient le mieux les rapports D/V. [Traduit par la Rédaction
Multi-Modal Neuroimaging Analysis and Visualization Tool (MMVT)
Sophisticated visualization tools are essential for the presentation and
exploration of human neuroimaging data. While two-dimensional orthogonal views
of neuroimaging data are conventionally used to display activity and
statistical analysis, three-dimensional (3D) representation is useful for
showing the spatial distribution of a functional network, as well as its
temporal evolution. For these purposes, there is currently no open-source, 3D
neuroimaging tool that can simultaneously visualize desired combinations of
MRI, CT, EEG, MEG, fMRI, PET, and intracranial EEG (i.e., ECoG, depth
electrodes, and DBS). Here we present the Multi-Modal Visualization Tool
(MMVT), which is designed for researchers to interact with their neuroimaging
functional and anatomical data through simultaneous visualization of these
existing imaging modalities. MMVT contains two separate modules: The first is
an add-on to the open-source, 3D-rendering program Blender. It is an
interactive graphical interface that enables users to simultaneously visualize
multi-modality functional and statistical data on cortical and subcortical
surfaces as well as MEEG sensors and intracranial electrodes. This tool also
enables highly accurate 3D visualization of neuroanatomy, including the
location of invasive electrodes relative to brain structures. The second module
includes complete stand-alone pre-processing pipelines, from raw data to
statistical maps. Each of the modules and module features can be integrated,
separate from the tool, into existing data pipelines. This gives the tool a
distinct advantage in both clinical and research domains as each has highly
specialized visual and processing needs. MMVT leverages open-source software to
build a comprehensive tool for data visualization and exploration.Comment: 29 pages, 10 figure
Canalization of Gene Expression and Domain Shifts in the Drosophila Blastoderm by Dynamical Attractors
The variation in the expression patterns of the gap genes in the blastoderm of
the fruit fly Drosophila melanogaster reduces over time as a
result of cross regulation between these genes, a fact that we have demonstrated
in an accompanying article in PLoS Biology (see Manu et al.,
doi:10.1371/journal.pbio.1000049). This biologically essential process is an
example of the phenomenon known as canalization. It has been suggested that the
developmental trajectory of a wild-type organism is inherently stable, and that
canalization is a manifestation of this property. Although the role of gap genes
in the canalization process was established by correctly predicting the response
of the system to particular perturbations, the stability of the developmental
trajectory remains to be investigated. For many years, it has been speculated
that stability against perturbations during development can be described by
dynamical systems having attracting sets that drive reductions of volume in
phase space. In this paper, we show that both the reduction in variability of
gap gene expression as well as shifts in the position of posterior gap gene
domains are the result of the actions of attractors in the gap gene dynamical
system. Two biologically distinct dynamical regions exist in the early embryo,
separated by a bifurcation at 53% egg length. In the anterior region,
reduction in variation occurs because of stability induced by point attractors,
while in the posterior, the stability of the developmental trajectory arises
from a one-dimensional attracting manifold. This manifold also controls a
previously characterized anterior shift of posterior region gap domains. Our
analysis shows that the complex phenomena of canalization and pattern formation
in the Drosophila blastoderm can be understood in terms of the
qualitative features of the dynamical system. The result confirms the idea that
attractors are important for developmental stability and shows a richer variety
of dynamical attractors in developmental systems than has been previously
recognized
Reactive oxygen species and male reproductive hormones
Reports of the increasing incidence of male infertility paired with decreasing semen quality have triggered studies
on the effects of lifestyle and environmental factors on the male reproductive potential. There are numerous exogenous
and endogenous factors that are able to induce excessive production of reactive oxygen species (ROS) beyond that of
cellular antioxidant capacity, thus causing oxidative stress. In turn, oxidative stress negatively affects male reproductive
functions and may induce infertility either directly or indirectly by affecting the hypothalamus-pituitary-gonadal (HPG)
axis and/or disrupting its crosstalk with other hormonal axes. This review discusses the important exogenous and
endogenous factors leading to the generation of ROS in different parts of the male reproductive tract. It also highlights
the negative impact of oxidative stress on the regulation and cross-talk between the reproductive hormones. It further
describes the mechanism of ROS-induced derangement of male reproductive hormonal profiles that could ultimately
lead to male infertility. An understanding of the disruptive effects of ROS on male reproductive hormones would
encourage further investigations directed towards the prevention of ROS-mediated hormonal imbalances, which in turn
could help in the management of male infertility
Nonstructural Carbohydrate and Digestibility Patterns in Temperate Pastures and Canopy Management Implications
Comparative efficacy and safety of remifentanil and fentanyl in 'fast track' coronary artery bypass graft surgery: a randomized, double-blind study.
Establishing the Signal above the Noise: Accounting for an Environmental Background in the Detection and Quantification of Salmonid Environmental DNA
A current challenge for environmental DNA (eDNA) applications is how to account for an environmental (or false-positive) background in surveys. We performed two controlled experiments in the Goldstream Hatchery in British Columbia using a validated coho salmon (Oncorhynchus kisutch) eDNA assay (eONKI4). In the density experiment at high copy number, eDNA in 2 L water samples was measured from four 10 kL tanks containing 1 to 65 juvenile coho salmon. At these densities, we obtained a strong positive 1:1 relationship between predicted copy number/L and coho salmon biomass (g/L). The dilution experiment simulated a situation where fish leave a pool environment, and water from upstream continues to flow through at rates of 141–159 L/min. Here, three coho salmon were placed in four 10 kL tanks, removed after nine days, and the amount of remaining eDNA was measured at times coinciding with dilutions of 20, 40, 80, 160, and 1000 kL. The dilution experiment demonstrates a novel method using Binomial–Poisson distributions to detect target species eDNA at low copy number in the presence of an environmental background. This includes determination of the limit of blank with background (LOB-B) with a controlled false positive rate, and limit of detection with background (LOD-B) with a controlled false negative rate, which provides a statistically robust “Detect” or “No Detect” assessment for eDNA surveys
Analysis of Radiative Heat Transfer in Inhomogeneous Nonisothermal Media Using Neural Networks
Establishing the Signal above the Noise: Accounting for an Environmental Background in the Detection and Quantification of Salmonid Environmental DNA
A current challenge for environmental DNA (eDNA) applications is how to account for an environmental (or false-positive) background in surveys. We performed two controlled experiments in the Goldstream Hatchery in British Columbia using a validated coho salmon (Oncorhynchus kisutch) eDNA assay (eONKI4). In the density experiment at high copy number, eDNA in 2 L water samples was measured from four 10 kL tanks containing 1 to 65 juvenile coho salmon. At these densities, we obtained a strong positive 1:1 relationship between predicted copy number/L and coho salmon biomass (g/L). The dilution experiment simulated a situation where fish leave a pool environment, and water from upstream continues to flow through at rates of 141–159 L/min. Here, three coho salmon were placed in four 10 kL tanks, removed after nine days, and the amount of remaining eDNA was measured at times coinciding with dilutions of 20, 40, 80, 160, and 1000 kL. The dilution experiment demonstrates a novel method using Binomial–Poisson distributions to detect target species eDNA at low copy number in the presence of an environmental background. This includes determination of the limit of blank with background (LOB-B) with a controlled false positive rate, and limit of detection with background (LOD-B) with a controlled false negative rate, which provides a statistically robust “Detect” or “No Detect” assessment for eDNA surveys
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