Behavior of barnacle larvae during surface exploration studied by stereoscopy

Marine biofouling is a global problem with a negative impact on several industrial and maritime branches, causing immense costs. Alongside with the economic consequences of colonization of surfaces, the environmental aspects should not be underestimated. Because of the predominant use of heavy-metal based antifouling coatings in the last decades, the most prominent component of which is tributyltin, TBT, several unacceptable environmental `side effects' on non-targeted species have emerged. This led to a global ban of the use of TBT-containing coatings in 2008. Since then, the research efforts focus on the development of surfaces which solely rely on physicochemical properties to mitigate the undesired accumulation of biomass. For identification of surface properties which influence and guide settlement, a better understanding of the colonization mechanisms of the target organisms is required. The purpose of this work was the investigation of the exploratory behaviour of barnacle larvae (cyprids) of Balanus amphitrite. This species was selected because it is widely spread in several geographic regions and contributes significantly to biofouling pressure. To enable the extraction of three-dimensional swimming trajectories, a stereoscopic setup was developed. It was utilized to quantify the pre-settlement behaviour of cyprids on surfaces with different wettability, hydration or charge. The analysis of the data allowed the identification of basic reoccurring patterns in the motion of cyprids, i.e. spiraling, swimming, sinking, rotating and walking. A detailed evaluation of the distribution of these patterns revealed that swimming was most frequently observed, followed by sinking which seemed to be its counterpart. Furthermore, it could be shown that most surface contacts emerged after sinking, while an active swimming towards the substrate was seldom observed. In addition, the general distribution of cyprids in the water column demonstrated that there was a clear preference for interfacial regions, and that the main occurrence of cyprids concentrated in three distinct zones above surfaces - the lower, bulk and upper swimming region, denoting the distance of the larvae from the substrate. It was revealed that the settlement preferences of cyprids were reflected in the motility parameters of exploration, i.e. linearity of the locomotion, mean velocity, swimming depth and extent of explored area. Once on a surface, cyprids initiate a close surface inspection, involving bipedal walking. The quantification of this mode of movement showed that the step duration and step velocity correlated with the attractiveness of the surface for settlement. Moreover, an analysis of the complete exploration process - from swimming via close surface inspection to interface interactions, confirmed literature reports that the number of surface touchdowns and the amount of organic deposit left behind were guided by the attractiveness of the substrate for biofouling. In addition to this organic deposit, macromolecules and other compounds accumulate on surfaces, immediately after these have been placed in an aquatic environment. The influence of this `conditioning' film on the exploratory behaviour was investigated and it was proven to cover the initial chemical end groups of different substrates. This masking process provoked cyprids to explore non-attractive conditioned surfaces in the same manner as attractive ones. Except on model surfaces, the exploratory behaviour was also investigated on commercially available hydrogel-based coatings and it was found that the motility of cyprids started to decrease gradually immediately after surface contact and after 4h it completely stopped, which was contributed to mortality of the organisms caused by the paints. Finally, the stereoscopic setup was modified to allow measurements in situ, underwater. The results of the field experiments at two test sites are discussed with respect to the applicability of the system for measurements in the natural environment and its capability to reveal colonization dynamics of marine organisms

Characterization of Metabolic, Diffusion, and Perfusion Properties in GBM: Contrast-Enhancing versus Non-Enhancing Tumor.

BackgroundAlthough the contrast-enhancing (CE) lesion on T1-weighted MR images is widely used as a surrogate for glioblastoma (GBM), there are also non-enhancing regions of infiltrative tumor within the T2-weighted lesion, which elude radiologic detection. Because non-enhancing GBM (Enh-) challenges clinical patient management as latent disease, this study sought to characterize ex vivo metabolic profiles from Enh- and CE GBM (Enh+) samples, alongside histological and in vivo MR parameters, to assist in defining criteria for estimating total tumor burden.MethodsFifty-six patients with newly diagnosed GBM received a multi-parametric pre-surgical MR examination. Targets for obtaining image-guided tissue samples were defined based on in vivo parameters that were suspicious for tumor. The actual location from where tissue samples were obtained was recorded, and half of each sample was analyzed for histopathology while the other half was scanned using HR-MAS spectroscopy.ResultsThe Enh+ and Enh- tumor samples demonstrated comparable mitotic activity, but also significant heterogeneity in microvascular morphology. Ex vivo spectroscopic parameters indicated similar levels of total choline and N-acetylaspartate between these contrast-based radiographic subtypes of GBM, and characteristic differences in the levels of myo-inositol, creatine/phosphocreatine, and phosphoethanolamine. Analysis of in vivo parameters at the sample locations were consistent with histological and ex vivo metabolic data.ConclusionsThe similarity between ex vivo levels of choline and NAA, and between in vivo levels of choline, NAA and nADC in Enh+ and Enh- tumor, indicate that these parameters can be used in defining non-invasive metrics of total tumor burden for patients with GBM

Swimming behavior of Pseudomonas aeruginosa studied by holographic 3D tracking.

Holographic 3D tracking was applied to record and analyze the swimming behavior of Pseudomonas aeruginosa. The obtained trajectories allow to qualitatively and quantitatively analyze the free swimming behavior of the bacterium. This can be classified into five distinct swimming patterns. In addition to the previously reported smooth and oscillatory swimming motions, three additional patterns are distinguished. We show that Pseudomonas aeruginosa performs helical movements which were so far only described for larger microorganisms. Occurrence of the swimming patterns was determined and transitions between the patterns were analyzed

Characterization of Metabolic, Diffusion, and Perfusion Properties in GBM: Contrast-Enhancing versus Non-Enhancing Tumor

BACKGROUND: Although the contrast-enhancing (CE) lesion on T1-weighted MR images is widely used as a surrogate for glioblastoma (GBM), there are also non-enhancing regions of infiltrative tumor within the T2-weighted lesion, which elude radiologic detection. Because non-enhancing GBM (Enh−) challenges clinical patient management as latent disease, this study sought to characterize ex vivo metabolic profiles from Enh− and CE GBM (Enh+) samples, alongside histological and in vivo MR parameters, to assist in defining criteria for estimating total tumor burden. Methods: Fifty-six patients with newly diagnosed GBM received a multi-parametric pre-surgical MR examination. Targets for obtaining image-guided tissue samples were defined based on in vivo parameters that were suspicious for tumor. The actual location from where tissue samples were obtained was recorded, and half of each sample was analyzed for histopathology while the other half was scanned using HR-MAS spectroscopy. Results: The Enh+ and Enh− tumor samples demonstrated comparable mitotic activity, but also significant heterogeneity in microvascular morphology. Ex vivo spectroscopic parameters indicated similar levels of total choline and N-acetylaspartate between these contrast-based radiographic subtypes of GBM, and characteristic differences in the levels of myo-inositol, creatine/phosphocreatine, and phosphoethanolamine. Analysis of in vivo parameters at the sample locations were consistent with histological and ex vivo metabolic data. CONCLUSIONS: The similarity between ex vivo levels of choline and NAA, and between in vivo levels of choline, NAA and nADC in Enh+ and Enh− tumor, indicate that these parameters can be used in defining non-invasive metrics of total tumor burden for patients with GBM

Characterization of Metabolic, Diffusion, and Perfusion Properties in GBM: Contrast-Enhancing versus Non-Enhancing Tumor.

BackgroundAlthough the contrast-enhancing (CE) lesion on T1-weighted MR images is widely used as a surrogate for glioblastoma (GBM), there are also non-enhancing regions of infiltrative tumor within the T2-weighted lesion, which elude radiologic detection. Because non-enhancing GBM (Enh-) challenges clinical patient management as latent disease, this study sought to characterize ex vivo metabolic profiles from Enh- and CE GBM (Enh+) samples, alongside histological and in vivo MR parameters, to assist in defining criteria for estimating total tumor burden.MethodsFifty-six patients with newly diagnosed GBM received a multi-parametric pre-surgical MR examination. Targets for obtaining image-guided tissue samples were defined based on in vivo parameters that were suspicious for tumor. The actual location from where tissue samples were obtained was recorded, and half of each sample was analyzed for histopathology while the other half was scanned using HR-MAS spectroscopy.ResultsThe Enh+ and Enh- tumor samples demonstrated comparable mitotic activity, but also significant heterogeneity in microvascular morphology. Ex vivo spectroscopic parameters indicated similar levels of total choline and N-acetylaspartate between these contrast-based radiographic subtypes of GBM, and characteristic differences in the levels of myo-inositol, creatine/phosphocreatine, and phosphoethanolamine. Analysis of in vivo parameters at the sample locations were consistent with histological and ex vivo metabolic data.ConclusionsThe similarity between ex vivo levels of choline and NAA, and between in vivo levels of choline, NAA and nADC in Enh+ and Enh- tumor, indicate that these parameters can be used in defining non-invasive metrics of total tumor burden for patients with GBM

3D trajectories of <i>P. aeruginosa</i> with transitions between different motion patterns.

<p>(A) Trajectory with a duration of 110 s with switching between the meander and the oscillation pattern. a) and b) illustrate extracted segments of the meander and the oscillation pattern in two different viewing directions indicated by the black arrows. (B) Trajectory with a duration of 130 s with switching between the three different patterns pseudohelix, helix and twisting. The individual segments of each pattern are illustrated in a), b) and c).</p

Turning angles of the hair-pin-like pattern.

<p>(A) Illustration for the calculation of the turning angles α. The angle is calculated from three consecutive displacement vectors and describes the deviation from a linear motion. (B) Calculated turning angles α (blue) and z-coordinate of the positions (green) of the hair-pin-like pattern in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087765#pone-0087765-g007" target="_blank">Figures 7A–B</a>.</p

Representation of <i>P.aeruginosa</i> trajectories showing different swimming patterns.

<p>(A) 3D representation of trajectories of <i>P. aeruginosa</i>. The optical path and thus the real space orientation of the 3D cubus is illustrated. (B) xy-projection of trajectories of <i>P. aeruginosa</i> as viewed along the optical path. In some trajectories loops can be observed which are marked with black arrows. (C) Schematical representation of 5 different swimming patterns observed for <i>P. aeruginosa</i> after tracking of 35 individual bacteria. The different patterns are termed (1) meander, (2) oscillation, (3) helix, (4) pseudohelix and (5) twisting. (D) Probability to observe the classified swimming patterns meander, oscillation, helix, pseudohelix and twisting within a trajectory. Values represent the average over 35 trajectories with the corresponding standard error.</p

Segments of helical swimming patterns.

<p>(A) and (B) 3D representation and view along the helical axis of a right-handed helical segment with 4 loops. (C) and (D) 3D representation and view along the helical axis of a left-handed helix with 3 loops. The start and the end points of the segments are labeled by triangles and rectangles respectively. The blue dots represent the unsmoothed data points, the red line shows the resulting trajectory after smoothing the data with local polynomial regression fitting.</p