Application Of Light Microscopy Research Articles

Ultrastructure and functional morphology of the appendages in the reef-building sedentary polychaete Sabellaria alveolata (Annelida, Sedentaria, Sabellida)

BackgroundThe sedentary polychaete Sabellaria alveolata, the sandcastle or honeycomb worm, possesses four different kinds of appendages besides the parapodia: opercular papillae, tentacular filaments, palps, and branchiae. It exhibits a highly specialized anterior end, the operculum, formed by the prostomium, peristomium, and two anterior segments. The operculum comprises opercular papillae, tentacular filaments, and palps. Paired branchiae are present from the second thoracic chaetiger onwards on the posteriorly following segments except for the last ones. Ultrastructural data on these appendages are either scanty, incomplete, or even lacking in Sabellariidae. In order to analyze their functional morphology, to bridge the data gap, and providing data for future phylogenetic and evolutionary analyses, we investigated the appendages of S. alveolata by applying light microscopy, confocal laser scanning microscopy, scanning, and transmission electron microscopy.ResultsIn S. alveolata the entire body is covered by a thin cuticle characterized by the absence of layers of parallel collagen fibers with no differentiation between the various body regions including the branchiae. The opercular papillae bear numerous tufts of receptor cells and lack motile cilia. The tentacular filaments show a distinctive pattern of motile cilia. Their most conspicuous morphological feature is a cell-free cartilaginous endoskeletal structure enclosed by ECM. Besides musculature the filaments include a single coelomic cavity but blood vessels are absent. The palps are ciliated and possess two coelomic cavities and a single blind-ending internal blood vessel. Besides external ciliation and receptor cells, the coelomate branchiae are highly vascularized and equipped with numerous blood spaces extending deep between the epidermal cells resulting in low diffusion distances.ConclusionsAll appendages, including the branchiae, bear receptor cells and, as such, are sensory. The opercular papillae resemble typical parapodial cirri. In contrast, the tentacular filaments have a triple function: sensing, collecting and transporting particles. A similarity to branchiae can be excluded. The palps are typical grooved palps. A revised classification of polychaete branchiae is suggested; thereby, the branchiae of S. alveolata belong to the most common type comprising coelom, musculature, and blood vessels. The results indicate that diffusion distances between blood and environment have been underestimated in many cases.

Microscopic analysis of shape-shiftable oligo (ε-caprolactone) — based particles

ABSTRACTSpherical particles are routinely monitored and described by hydrodynamic diameters determined, e.g., by light scattering techniques. Non-spherical particles such as prolate ellipsoids require alternative techniques to characterize particle size as well as particle shape. In this study, oligo(ε-caprolactone) (oCL) based micronetwork (MN) particles with a shape-shifting function based on their shape-memory capability were programmed from spherical to prolate ellipsoidal shape aided by incorporation and stretching in a water-soluble phantom matrix. By applying light microscopy with automated contour detection and aspect ratio analysis, differences in characteristic aspect ratio distributions of non-crosslinked microparticles (MPs) and crosslinked MNs were detected when the degrees of phantom elongation (30-290%) are increased. The thermally induced shape recovery of programmed MNs starts in the body rather than from the tips of ellipsoids, which may be explained based on local differences in micronetwork deformation. By this approach, fascinating intermediate particle shapes with round bodies and two opposite sharp tips can be obtained, which could be of interest, e.g., in valves or other technical devices, in which the tips allow to temporarily encage the switchable particle in the desired position.

PO 8503 EPIDEMIOLOGY, CO-INFECTIONS AND HAEMATOLOGICAL FEATURES OF SCHISTOSOMIASIS IN SCHOOL-AGED CHILDREN LIVING IN LAMBARÉNÉ, GABON

BackgroundSchistosomiasis is a highly prevalent parasitic infection in Central Africa, where co-endemicity with other parasitic infections is common, and schistosomiasis outcomes can be affected by those other infections. Therefore, proper schistosomiasis control needs epidemiological data accounting for co-infections, too. In this present study, our objective was to determine the epidemiological situation around schistosomiasis in Lambaréné.MethodsA cross-sectional study was conducted among school-aged children living in Lambaréné. Urine filtration exam was performed for the detection of Schistosoma eggs. Kato-Katz and stool culture (Coproculture and Harada-Mori) techniques were used for the detection of soil-transmitted helminths. Detection of Plasmodium spp. and blood microfilariae was performed applying light microscopy. Risk factors for schistosomiasis and factors associated with schistosomiasis were investigated; haematology parameters evaluated.ResultsA total of 614 school children with available schistosomiasis status were included in the analysis. Mean age was 10.9 (SD=2.7) years, with a 0.95 boy-to-girl sex ratio. The prevalence of schistosomiasis was 26%. No risk factors except human-water contact were associated with schistosomiasis. Only Trichuris trichiura co-infection was associated with an increased odd (aOR=2.3, p-value=0.048) to be infected with schistosomiasis. Full blood counts showed a decrease of haemoglobin level and increase of WBC and platelet levels among the schistosoma-infected children. Haematuria was found associated with schistosomiasis (aOR=14.5, p-value<0.001) and was suitable to predict the disease.ConclusionThe prevalence of schistosomiasis is moderate in Lambaréné where human-water contact remains the main risk factor and praziquantel is available for treatment. Trichuriasis is associated with increased risk to be infected. Children with schistosomiasis exhibit a distinct full blood count profile and haematuria is found to be more suitable to predict infection. However, it is desirable to implement comprehensive approaches beyond chemotherapy for schistosomiasis control in this area as recommended by WHO.

Anterior sense organs in Sabellaria alveolata (Annelida, Sedentaria, Spionida) with special reference to ultrastructure of photoreceptor elements presumably involved in shadow reflex

The reef-building sedentary polychaete, Sabellaria alveolata, is well known for its specialized anterior end, the operculum, which is exposed to the environment during vital activities, such as feeding or as it seals its tube when the animal withdraws. This region represents the most important sensory structure in Sabellariidae. It comprises two lobes, tentacular filaments, protective chaetae (paleae), a median organ, and a median ridge, and bears various pigmented spots. Worms swiftly withdraw into tubes triggered by abrupt light change (shadow reflex). We suspected that the pigmented spots were photoreceptive and responsible for the shadow response. To test this hypothesis, the median organ and median ridge of S. alveolata were investigated by applying light microscopy, confocal laser scanning microscopy, scanning, and transmission electron microscopy. Besides unciliated supportive cells, these organs consist of numerous multiciliated and glandular cells on their ventral surfaces. The multiciliated cells are of two types: epidermal supportive and receptor cells. The median organ is innervated directly from the brain by two longitudinal basiepithelial nerves. The presence of multiciliated cells and mucocytes suggests that the organ is sensory, involved in both feeding and tube-building behavior. Furthermore, we found two pairs of eyespots on the lateral posterior part of the median ridge, situated close to the neurite bundles anterior to the brain. These eyes are simple in structure and resemble larval-type eyes. They are composed of only two cells each, one rhabdomeric photoreceptor cell and one pigmented supportive cell. The pigmented eyes on the median ridge are clearly involved in photoreception and very likely involved in shadow reflex.

Development of semisolid self-microemulsifying drug delivery systems (SMEDDSs) filled in hard capsules for oral delivery of aciclovir

The study aimed to develop semisolid self-microemulsifying drug delivery systems (SMEDDSs) as carriers for oral delivery of aciclovir in hard hydroxypropylmethyl cellulose (HPMC) capsules. Six self-dispersing systems (SD1-SD6) were prepared by loading aciclovir into the semisolid formulations consisting of medium chain length triglycerides (lipid), macrogolglycerol hydroxystearate (surfactant), polyglyceryl-3-dioleate (cosurfactant), glycerol (hydrophilic cosolvent), and macrogol 8000 (viscosity modifier). Their characterization was performed in order to identify the semisolid system with rheological behaviour suitable for filling in hard HPMC capsules and fast dispersibility in acidic and alkaline aqueous media with formation of oil-in-water microemulsions. The optimal SMEDDS was loaded with aciclovir at two levels (2% and 33.33%) and morphology and aqueous dispersibility of the obtained systems were examined by applying light microscopy and photon correlation spectroscopy (PCS), respectively. The assessment of diffusivity of aciclovir from the SMEDDSs by using an enhancer cell model, showed that it was increased at a higher drug loading. Differential scanning calorimetry (DSC) analysis indicated that the SMEDDSs were semisolids at temperatures up to 50°C and physically stable and compatible with HPMC capsules for 3 months storage at 25°C and 4°C. The results of in vitro release study revealed that the designed solid dosage form based on the semisolid SMEDDS loaded with the therapeutic dose of 200mg, may control partitioning of the solubilized drug from in situ formed oil-in-water microemulsion carrier into the sorrounding aqueous media, and hence decrease the risk for precipitation of the drug.

Novel ESPI Measurement Prototype for Analyzing Biological Samples from Cell Culture Technique

An essential part of cell cultivation via cell culture technology is the determination and monitoring of culture parameters. Such parameters refer to the vitality or mutual mutations of the cell culture, while the actual number of living cells in each batch indicates the correct growth rate rather than stagnation or an overgrowth of the cell culture. Today such parameters are determined by applying light microscopy methods or by staining specific constituents of the cells. Commonly such methods are a stressful procedure for the studied cells. Most applied dyes are toxic over a certain period of time and thus they are used in low concentrations only when necessary. Within this work a new kind of measurement device prototype was designed to address these problems. This device is based on the Electronic Speckle Pattern Interferometry (ESPI). ESPI is an optical high-resolution method combined with a photonic analysis system capable of analyzing cellular deformations and oscillations. In this approach the combination of a greatly modified microscope together with ESPI method is presented. The apparatus allows the determination of cellular deformation (i) at very high magnifications, (ii) with high lateral resolution. Furthermore the system studies (iii) contact free, (iv) in vitro cells, in a non-invasive and non-destructive way. A co-developed cultivation system allows monitoring the culture parameters in real time minimizing the stress for the cell culture. Since no additional substances are needed, the presented prototype is automated to a large extent and can be operated by a special control-and regulation system (CRS) based on a microcontroller development board (Arduino Mega).

Digestibility and muscle retention of astaxanthin in Atlantic salmon, Salmo salar, fed diets with the red yeast Phaffia rhodozyma in comparison with synthetic formulated astaxanthin

To elucidate whether astaxanthin plasma concentration, deposition and retention in the muscle (% of ingested dose) and apparent digestibility coefficients (ADC) were influenced by astaxanthin source, triplicate groups of size-graded (initial average weight of 0.69 kg) Atlantic salmon ( Salmo salar), individually labelled with PIT-tags were fed two different experimental diets (6 tanks, each containing 20 fish) for 86 days. Two experimental extruded feeds (7.3 mm) were supplemented with approximately 40 mg astaxanthin from the red yeast Phaffia rhodozyma (Ecotone™) or Lucantin ® Pink (LP), respectively. Technical tests applying light microscopy (LM) compared to scanning electron microscopy (SEM) were used to obtain information on visible structural changes of the P. rhodozyma cells during feed processing and digestion. The fish increased its weight by 74% irrespective of dietary treatment. The specific growth rate was 0.64% day − 1 for the experiment, corresponding to a thermal growth coefficient of 2.15. The feed conversion ratios ranged from 0.96 to 0.98. The final total carotenoid concentration of the muscle was significantly higher ( P < 0.05) in salmon fed the diet supplemented with P. rhodozyma (2.56 mg kg − 1 ) compared to salmon fed the diet supplemented with LP (1.96 mg kg − 1 ). The total concentrations of the astaxanthin metabolite idoxanthin were similar in the two treatments, but the composition of the 3′,4′- cis and 3′,4′- trans glycolic isomers was significantly ( P < 0.05) affected by treatment (idoxanthin 3′,4′- cis-to 3′,4′- trans glycolic isomer ratio 0.3 to 1.20 for salmon fed the diets supplemented with P. rhodozyma and LP, respectively). The highest retention of dietary astaxanthin was found in the muscle of salmon fed the diet supplemented with P. rhodozyma cells (6.3%), and it was 86% higher than for salmon fed the synthetic control astaxanthin. This was reflected by the astaxanthin ADC which was about 64 to 68% in salmon fed the diet supplemented with P. rhodozyma and 38 to 42% in the salmon fed the synthetic control ( P < 0.05). Plasma and muscle carotenoid concentrations correlated poorly ( R 2 = 0.0007), and indicated that plasma concentration of carotenoids is a relatively weak indicator of muscle concentration for salmon fed diets with similar concentrations of astaxanthin. Microscopy tests revealed that the identification of P. rhodozyma cells in complex matrices was more reliable when LM was used compared to SEM. The extruded feed supplemented with Ecotone™ contained isolated P. rhodozyma cells and was free of cell clusters. Some empty cells could be detected. Semi-quantitative analysis by LM revealed that the number of cells was 2.3- to 4.6-fold higher in faeces samples than in the feed. In the faeces various amounts of astaxanthin were observed in the cells. The majority of cells with little or no astaxanthin showed clearly visible lesions or ruptures in the cell wall. It is concluded that Ecotone™ represents a more effective astaxanthin source for pigmentation of Atlantic salmon muscle than LP, but microscopic analysis revealed a potential for further improvement.

The kinetics of the nitriding of Fe–7Cr alloys; the role of the nitriding potential

The nitriding behaviour of the Fe–7Cr alloy was studied at 580°C in a gas mixture of ammonia and hydrogen. The nitriding potential was varied from 0.03 to 0.818 atm−1/2. Microstructural analysis of the nitrided specimens was performed by applying light microscopy, hardness measurements, X-ray diffraction, and electron probe microanalysis. The nitrided zone is composed of both regions with finely dispersed small chromium nitride (CrN) precipitates (continuous precipitates) in ferrite (α–Fe) grains and, mainly near the surface, regions where the precipitates have discontinuously coarsened leading to a lamellar CrN/α–Fe morphology. The nitrogen content within the nitrided zone is larger than expected on the basis of the chromium content and the solubility of nitrogen in (stress free) ferrite: excess nitrogen occurs. The hardness maximum in the nitrided zone and the nitriding depth increases with increasing nitriding potential as long as no iron nitride layer develops at the surface of the specimens. To describe the evolution of the nitrogen concentration depth profile of the nitrided layers, a numerical model was applied that has as important (fit) parameters: the surface nitrogen content, the solubility product of chromium and nitrogen dissolved in the ferrite matrix, and a parameter defining the composition of the precipitated chromium nitride. The nitriding depth depends roughly linearly on the square root of the nitriding potential. Analysis of the concentration depth profile data demonstrated that the amount of excess nitrogen considerably influences the nitriding kinetics.