Ultrastructural Features Research Articles

Correlative light-electron microscopy methods to characterize the ultrastructural features of the replicative and dormant liver stages of Plasmodium parasites

BackgroundThe infection of the liver by Plasmodium parasites is an obligatory step leading to malaria disease. Following hepatocyte invasion, parasites differentiate into replicative liver stage schizonts and, in the case of Plasmodium species causing relapsing malaria, into hypnozoites that can lie dormant for extended periods of time before activating. The liver stages of Plasmodium remain elusive because of technical challenges, including low infection rate. This has been hindering experimentations with well-established technologies, such as electron microscopy. A deeper understanding of hypnozoite biology could prove essential in the development of radical cure therapeutics against malaria.ResultsThe liver stages of the rodent parasite Plasmodium berghei, causing non-relapsing malaria, and the simian parasite Plasmodium cynomolgi, causing relapsing malaria, were characterized in human Huh7 cells or primary non-human primate hepatocytes using Correlative Light-Electron Microscopy (CLEM). Specifically, CLEM approaches that rely on GFP-expressing parasites (GFP-CLEM) or on an immunofluorescence assay (IFA-CLEM) were used for imaging liver stages. The results from P. berghei showed that host and parasite organelles can be identified and imaged at high resolution using both CLEM approaches. While IFA-CLEM was associated with more pronounced extraction of cellular content, samples’ features were generally well preserved. Using IFA-CLEM, a collection of micrographs was acquired for P. cynomolgi liver stage schizonts and hypnozoites, demonstrating the potential of this approach for characterizing the liver stages of Plasmodium species causing relapsing malaria.ConclusionsA CLEM approach that does not rely on parasites expressing genetically encoded tags was developed, therefore suitable for imaging the liver stages of Plasmodium species that lack established protocols to perform genetic engineering. This study also provides a dataset that characterizes the ultrastructural features of liver stage schizonts and hypnozoites from the simian parasite species P. cynomolgi.Graphical

Ultrastructural features of tumor-associated mast cells in parasympathetic paragangliomas (chemodectomas) of the neck.

The mechanisms of the pathogenesis of neck paraganglioma (PGL) and the possible role of mast cells (MCs) in its development and metastasis are still poorly understood. We analyzed MCs' morphologic characterization, activation, and the properties of their cytoplasmic/released granules in PGLs, using light and transmission electron microscopy. Paragangliomas showed a large tumor-associated MC population both in the connective tissue layers of the tumor and between the tumor cells. Notably, MCs were presented by a high expression of specific proteases, size variation, polymorphism, and variable ultrastructural phenotype of granules. A massive number of granules were released surrounding the degranulated MCs while the integrity of MC membrane was maintained. Granules were electron-dense with or without a membrane, ranging from 0.2 to 0.8 μm in diameter. MC plasmalemma was not found at the site of MC-collagen fibrils contact, whereas the secretome and fibrils were directly contacted. We observed direct and mediator-based interactions between MCs and paraganglioma cells. The latter preserved their membrane integrity when MC granules were not in proximity. The effects of the MC secretome on the paraganglioma microenvironment demonstrated its pathogenetic role in tumor progression and allow its application to new diagnostic criteria and the development of protocols for personalized therapy. RESEARCH HIGHLIGHTS: Ultrastructural analysis reveals novel regulatory effects of mast cells via diverse secretory pathways on the pathogenesis of parasympathetic paraganglioma, including fibrous extracellular matrix remodeling and mediator-based interactions between MCs and cells of the tumor microenvironment.

Exploring the histogenesis of STK11 adnexal tumour using electron microscopy

STK11 adnexal tumour is a recently described female genital tract tumour, usually identified in a paratubal location, often associated with Peutz-Jeghers syndrome (PJS) and with STK11 gene alterations identified in most of the cases. Morphologically, this tumour is composed of cells arranged in a variety of patterns, including cords, trabeculae, tubules and cystic and acinar structures. The cells are only moderately pleomorphic and mitotic activity is variable. As tumour cells express epithelial, sex cord stromal and mesothelial markers, STK11 adnexal tumour may be of sex cord stromal, epithelial or mesothelial origin; a Wolffian origin has also been suggested. We report the ultrastructural features of two STK11 adnexal tumours and compare their ultrastructural features with those of other sex cord stromal tumours, a granulosa cell tumour cell line, as well as the known ultrastructural features of epithelial, mesothelial and Wolffian cells. On ultrastructural examination, two STK11 adnexal tumours showed an admixture of elongated cells with regular elongated nuclei and polygonal cells with nuclei showing markedly irregular outlines and prominent nucleoli. Extracellular collagen fibres were identified. These are common ultrastructural features of sex cord stromal tumours, principally sex cord tumour with annular tubules; no ultrastructural features of epithelial, mesothelial or Wolffian cells were found. These findings in conjunction with the shared clinical and genetic association with PJS and shared molecular changes in STK11 gene suggest that STK11 adnexal tumour represents a poorly differentiated sex cord tumour.

New Insights on the Male and Female Reproductive Organs of Centrorhynchus globocaudatus (Acanthocephala), Intestinal Parasite of Birds of Prey.

Acanthocephalans are dioecious parasites that gain sexual maturity in the alimentary canal of their definitive hosts (gnathostome vertebrates). This initial survey by light and transmission electron microscopy was conducted on the functional organization of the ovarian balls and uterine bell in mature females and on Saefftigen's pouch and the copulatory bursa in males. We studied these structures via the example of Centrorhynchus globocaudatus (Palaeacanthocephala) in Falco tinnunculus and Buteo buteo, from the Province of Ferrara (Northern Italy). Our study confirms that the ovarian balls have surface microvilli and consist of a multinucleate supporting syncytium and a cellular region with oogonial syncytium, single germ cells, zygotes, and shelled eggs. Germ cells are embedded in the supporting syncytium. The ultrastructural features of these components and data on fertilization, shell formation, and release from the ovarian ball, alongside insights into the likely egg sorting function of the uterine bell, are provided. We also present light and electron microscopy observations of Saefftigen's pouch and a suggestion regarding its hydrostatic functioning in the eversion of the copulatory bursa.

Histochemical, metabolic and ultrastructural changes in leaf patelliform nectaries explain extrafloral nectar synthesis and secretion in Clerodendrum chinense.

Extrafloral nectaries are nectar-secreting structures present on vegetative parts of plants which provide indirect defences against herbivore attack. Extrafloral nectaries in Clerodendrum chinense are patelliform-shaped specialized trichomatous structures. However, a complete understanding of patelliform extrafloral nectaries in general, and of C. chinense in particular, has not yet been established to provide fundamental insight into the cellular physiological machinery involved in nectar biosynthesis and secretory processes. We studied temporal changes in the morphological, anatomical and ultrastructural features in the architectures of extrafloral nectaries. We also compared metabolite profiles of extrafloral nectar, nectary tissue, non-nectary tissue and phloem sap. Further, both in situ histolocalization and normal in vitro activities of enzymes related to sugar metabolism were examined. Four distinct tissue regions in the nectar gland were revealed from histochemical characterization, among which the middle nectariferous tissue was found to be the metabolically active region, while the intermediate layer was found to be lipid-rich. Ultrastructural study showed the presence of a large number of mitochondria along with starch-bearing chloroplasts in the nectariferous region. However, starch depletion was noted with progressive maturation of nectaries. Metabolite analysis revealed compositional differences among nectar, phloem sap, nectary and non-nectary tissue. Invertase activity was higher in secretory stages and localized in nectariferous tissue and adjacent region. Our study suggests extrafloral nectar secretion in C. chinense to be both eccrine and merocrine in nature. A distinct intermediate lipid-rich layer that separates the epidermis from nectary parenchyma was revealed, which possibly acts as a barrier to water flow in nectar. This study also revealed a distinction between nectar and phloem sap, and starch could act as a nectar precursor, as evidenced from enzymatic and ultrastructural studies. Thus, our findings on changing architecture of extrafloral nectaries with temporal secretion revealed a cell physiological process involved in nectar biosynthesis and secretion.

Evidence for glia-mediated, age-dependent remodeling of myelin at the axon initial segment.

Due to its proximity to the axon initial segment (AIS), the paranode of the first myelin segment can influence the threshold for action potentials and how a neuron participates in a neuronal circuit. Using serial section electron microscopy, we examined its three-dimensional (3D) organization in the ventral horn of the mouse spinal cord. The myelin loops of postnatal day 18 mice resemble those at the node of Ranvier. However, in 3-month-old mice, 13 of 22 para-AIS showed 4 types of alteration: (A) A cytoplasmic foot process, with ultrastructural characteristics of an astrocyte, was interposed between the axolemma and the myelin loops. (B) A thin extension of the inner tongue was present between the foot process and axolemma. (C) The foot process was absent. The inner tongue extension was a broad lamella from which a thin extension reached beyond the loops and spiraled around axon. (D) One set of loops was adjacent to the axon, and another was further back and underlain by compact myelin. We suggest that (A)-(C) are steps in a progression toward (D). In this progression, a glial process displaces the original loops, the inner tongue reactivates and extends beneath the foot process, then wraps around the axon to form a new set of loops. This is the first study of the 3D organization of myelin at the AIS and provides evidence for glia-mediated age-dependent remodeling at this critical region.

Thin film structural color is widespread in slime molds (Myxomycetes, Amoebozoa).

Brilliant colors in nature arise from the interference of light with periodic nanostructures resulting in structural color. While such biological photonic structures have long attracted interest in insects and plants, they are little known in other groups of organisms. Unexpected in the kingdom of Amoebozoa, which assembles unicellular organisms, structural colors were observed in myxomycetes, an evolutionary group of amoebae forming macroscopic, fungal-like structures. Previous work related the sparkling appearance of Diachea leucopodia to thin film interference. Using optical and ultrastructural characterization, we here investigated the occurrence of structural color across 22 species representing two major evolutionary clades of myxomycetes including 14 genera. All investigated species showed thin film interference at the peridium, producing colors with hues distributed throughout the visible range that were altered by pigmentary absorption. A white reflective layer of densely packed calcium-rich shells is observed in a compound peridium in Metatrichia vesparium, whose formation and function are still unknown. These results raise interesting questions on the biological relevance of thin film structural colors in myxomycetes, suggesting they may be a by-product of their reproductive cycle.

Comparative histological and ultrastructural features of the tongue of the mallard domestic duck, Anas platyrhynchos f. domestica, Anatidae (Linnaeus, 1758) in different two age stages (post-hatching [P2] and adult female) captured from Egypt.

The domestic duck is classified as a specialist filter-feeder bird living in the water. These birds also use grazing and pecking as terrestrial feeding methods. The tongues of domestic ducks, similar to those of other Anseriformes, exhibit numerous types and shapes of mechanical papillae that serve a number of purposes when collecting food. The current study attempts to describe the morphological characteristics of the tongue as well as the mechanical papillae's development. In addition, the study aims to determine whether the papillae observed post-hatching (P2) exhibit similar morphology to those found in adult female avian species, as well as to investigate the readiness of the tongue to fulfill its feeding function following hatching. The comprehensive examination of lingual mucosa is examined about the structural modifications necessary for this variety of feeding activities. In this study, the tongues of nine young (P2) and adult female were used. The tongue had three distinct parts: the apex, which had a lingual nail on its ventral surface; the body, which exhibits numerous small and large conical papillae on its lateral sides and a lingual prominence in the caudal region; and the root, which is covered with numerous conical papillae of varying sizes. Conical, filiform, and hair-like mechanical papillae, the three types of food filtration apparatus, are present in both stages. The intraoral transfer involves several structures, including the median groove, lingual combs, and the rostral border of the lingual prominence. The rostral border of the lingual prominence is characterized by distinct rows of conical papillae. The histological analysis demonstrated the presence of both keratinized and nonkeratinized epithelium on different tongue regions. The lingual salivary glands in the rostral and caudal lingual salivary glands exhibit a pronounced periodic acid-Schiff-positive reaction. Additionally, the yellow adipose tissue and sensory receptors, namely the Grandry and Herbst corpuscles, which collectively form the bill-tongue organ that monitors the movement of food. These results conclude the presence of microstructural species-specific alterations in specific tongue areas of domestic ducks' lingual mucosa. These modifications are formed by the filtering mechanism and terrestrial feeding mechanisms, such as grazing or pecking. Following hatching, the tongue of the domestic duck undergoes significant development, primarily in preparation for grazing activities. The anatomical and histological structure of the young (P2) tongue exhibited similarities to that of the adult female domestic duck while also displaying certain variations that could potentially be attributed to the bird's habitat and mode of feeding. RESEARCH HIGHLIGHTS: The results of this study concluded that the domestic duck exhibit a complex tongue structure characterized by the arrangement and morphology of its mechanical papillae, the presence of the lingual prominence with distinctive shape and the lingual comb. These features are believed to be adaptations that enable the duck to actively and efficiently filter food particles from water, serving as its primary feeding mechanism. Additionally, the tongue of domestic ducks is specifically adapted to facilitate various terrestrial activities, such as grazing and pecking. This adaptation is achieved through the presence of conical papillae and a lingual nail. These investigations facilitate our comprehension of both the anatomical and histological characteristics of the domestic duck tongue, as well as enhance our understanding of bird adaptations to various feeding mechanisms.

The impact of biomembranes and their dynamics on organismic aging: insights from a fungal aging model.

Biomembranes fulfill several essential functions. They delimitate cells and control the exchange of compounds between cells and the environment. They generate specialized cellular reaction spaces, house functional units such as the respiratory chain (RC), and are involved in content trafficking. Biomembranes are dynamic and able to adjust their properties to changing conditions and requirements. An example is the inner mitochondrial membrane (IMM), which houses the RC involved in the formation of adenosine triphosphate (ATP) and the superoxide anion as a reactive oxygen species (ROS). The IMM forms a characteristic ultrastructure that can adapt to changing physiological situations. In the fungal aging model Podospora anserina, characteristic age-related changes of the mitochondrial ultrastructure occur. More recently, the impact of membranes on aging was extended to membranes involved in autophagy, an important pathway involved in cellular quality control (QC). Moreover, the effect of oleic acid on the lifespan was linked to basic biochemical processes and the function of membranes, providing perspectives for the elucidation of the mechanistic effects of this nutritional component, which positively affects human health and aging.

Restrain-stress-induced Biochemical and Transmission Electron Microscopic Changes in Albino Rat’s Brain

Restrained-stress in adult male albino rats for 24 hours in continuity resulted in increased lipid peroxidation (maximum 37.03% in cerebellum) and 8-fold increase (statistically significant p<0.001in brainstem) of fluorescent pigment intensity. Greater affinity of darkly stained luxol-fast positive Purkinje neurons suggests decreased metabolic activity as a result of stress. TEM revealed an increase in the incidence of pleomorphic electrodense bodies in neurons of different brain parts. In cerebellum, dense bodies even exhibited fingerprint pattern due to engulfment of damaged cytomembranes subsequent to increased lipid peroxidation. The electronluscent vacuoles located either at or near the periphery or inside the electrondense bodies, were likely to represent the digested material consequent upon the action of action of hydrolytic enzymes. The increase in the number of coated and smooth vesicles and abundance of microtubules in the cytoplasm of neurons of stressed rats exhibited ultrastructural features in support of their being involved in the transfer of membranes and membrane-associated molecules in the intracellular compartments. Increase in GERL-like profiles could also be detected in cingulate cortex, hypothalamus, and cerebellum after 24 hours restrain of rats. Interestingly, GERL displayed continuity with different cellular organelles in cerebellum of stressed rats. These findings supported the concept advocated by Paavola that GERL’s lytic enzymes engulf membranes and trapped lysosomes thus producing aggregate type inclusions of electrodense bodies.

Chemical and Ultrastructural Characterization of Dentin Treated with Remineralizing Dentifrices.

The aim of this study is to investigate dentin chemical and ultrastructural changes upon exposure to remineralizing dentifrices. Dentin disks were obtained from permanent human molars and treated for 7 days with the dentifrices: (1) C group-control (no dentifrice); (2) S group-Sensodyne Repair & Protect; (3) D group-Dentalclean Daily Regenerating Gel; and (4) DB group-D group + Dentalclean regenerating booster. Afterwards, samples were submitted to an additional 7 days of toothbrushing associated with daily acidic challenge. Samples were imaged and analyzed (days 1, 7, and 14) for Young's modulus by atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). SEM and AFM revealed precipitate deposition on dentin surfaces in groups S, D, and DB, formed as early as day 1. Surface elemental analysis showed a Si increase on all brushed surfaces. Similar surface morphology was maintained after the acidic challenge period. Bright-field TEM/SAED revealed the formation of nanocrystalline hydroxyapatite inside the dentin tubules of groups S, D, and DB after day 7. Group C presented a gradual reduction of Young's modulus from days-1-14, whereas all remaining groups had increased values. All evaluated dentifrices led to successful formation of hydroxyapatite and increased dentin stiffness.

Enamel and dentin of human teeth. Fatigue strength

The article provides a brief overview of the studies regarding changes in the structure and composition of teeth after eruption. The factors of degenerative changes in tooth structures and their relationship with non-carious lesions have been analyzed. The study makes emphasis on the tooth durability and the factors influencing tissue fatigue, explaining increased tissue wear due to local factors. Understanding mechanisms of metabolism of teeth hard tissues is the key to the stability of restorative treatments and occurrence of non-carious tooth lesions. The evolution of views on this problem is noteworthy. The literature review reveals the initial predominance of mechanical actions, abrasion, and mineralization. It is later complemented by a detailed analysis of the influence of destructive stresses and deformation due to mechanical factors. All the leading works of the 2000s are dedicated to analyzing the ultrastructural features of enamel that affect its mechanical characteristics and can explain both the characteristics of the shape and intensity of mechanical tooth wear during the functioning of the stomatognathic system, as well as the durability of the performed restorations. The literature review covers 74 sources over the past 15 years.

Effects of saline-fresh water rotation irrigation on photosynthetic characteristics and leaf ultrastructure of tomato plants in a greenhouse

To reveal the mechanisms of saline-fresh water rotation irrigation that affect the leaf ultrastructure and photosynthetic characteristics of tomato plants and to optimize the strategy of saline water irrigation of greenhouse tomatoes, a two-season tomato experiment with four treatments of saline-fresh water rotation irrigation was conducted in a greenhouse in southern Xinjiang. The four treatments consisted of rotation irrigation with four times saline-fresh water (W1), rotation irrigation with two times saline water and two times fresh water (W2), rotation irrigation with two times fresh water, four times saline water, and two times fresh water (W3), and freshwater irrigation as a control (CK). The three rotation patterns had the same amount of saline water and fresh water, but the rotational interval was different. The results indicated that the saline-alkali stress introduced by saline water significantly reduced the gas exchange parameters of tomato leaves and water use efficiency at the leaf scale, and both stomatal and non-stomatal factors played a key role in limiting leaf gas exchange. The chloroplast granular lamellae structure was disrupted in tomato leaves treated with W1 and W2. Compared with CK, W1 and W2 decreased leaf chlorophyll content by 4.59% and 10.89%, net photosynthetic rate by 26.82% and 40.11%, and yield by 60.62% and 67.63%, respectively. In contrast, W3 presented a relatively intact mesophyll cell structure and relatively high chlorophyll content and photosynthetic efficiency. In W3 treatment, no significant differences were found in the number of fruits per plant (only increased by 8.16% and the yield by 4.03%), while with better quality compared with CK. The results suggested that tomato growth and yield were neither poor nor detrimental when rotated with saline water during the flowering and fruiting stage-fruit expansion stage and freshwater irrigation during other growth stages. W3 can be used as a saline-fresh water rotation pattern for tomato production in greenhouses in arid and saline areas.

Immunohistochemical and ultrastructural characterization of the inner ear epithelial cells of splitnose rockfish (Sebastes diploproa).

The inner ear of teleost fish regulates the ionic and acid-base chemistry and secretes protein matrix into the endolymph to facilitate otolith biomineralization, which is used to maintain vestibular and auditory functions. The otolith is biomineralized in a concentric ring pattern corresponding to seasonal growth, and this calcium carbonate (CaCO3) polycrystal has become a vital aging and life-history tool for fishery managers, ecologists, and conservation biologists. Moreover, biomineralization patterns are sensitive to environmental variability including climate change, thereby threatening the accuracy and relevance of otolith-reliant toolkits. However, the cellular biology of the inner ear is poorly characterized, which is a hurdle for a mechanistic understanding of the underlying processes. This study provides a systematic characterization of the cell types in the inner ear of splitnose rockfish (Sebastes diploproa). Scanning electron microscopy revealed the apical morphologies of six inner ear cell types. In addition, immunostaining and confocal microscopy characterized the expression and subcellular localization of the proteins Na+-K+-ATPase, carbonic anhydrase, V-type H+-ATPase, Na+-K+-2Cl--cotransporter, otolith matrix protein 1, and otolin-1 in six inner ear cell types bordering the endolymph. This fundamental cytological characterization of the rockfish inner ear epithelium illustrates the intricate physiological processes involved in otolith biomineralization and highlights how greater mechanistic understanding is necessary to predict their multistressor responses to future climate change.

A new species of Craspedostauros (Bacillariophyceae) from the west coast of Sweden, with taxonomic and ecological notes on Craspedostauros laevissimus

Abstract Since its separation from Stauroneis in 1999, several new species of Craspedostauros were discovered in a variety of habitats and geographic locations, adding morphological and phylogenetic data to the investigations of the genus. In a survey of littoral diatoms of Sweden, both on the west and east coasts, two epiphytic stauros-bearing species were encountered and assigned to Craspedostauros following the characteristic features of this genus, including the possession of a stauros narrower than the central area and cribrate areolae. One species is described as new to science; Craspedostauros lateralis sp. nov., and the other is of uncertain identity but bears morphological similarity to C. laevissimus. Caspedostauros lateralis is a marine epiphytic species found in the west coast of Sweden, off Gothenburg city. Based on light and electron microscopy, a detailed description of the morphological and ultrastructural features of these species is given and a comparison of the distinguishing characters with allied species is discussed. Some ecological data and the occurrence of associated species on the host macrophyte are provided.

The genetic framework of primary ciliary dyskinesia assessed by soft computing analysis.

International guidelines disagree on how best to diagnose primary ciliary dyskinesia (PCD), not least because many tests rely on pattern recognition. We hypothesized that quantitative distribution of ciliary ultrastructural and motion abnormalities would detect most frequent PCD-causing groups of genes by soft computing analysis. Archived data on transmission electron microscopy and high-speed video analysis from 212 PCD patients were re-examined to quantitate distribution of ultrastructural (10 parameters) and functional ciliary features (4 beat pattern and 2 frequency parameters). The correlation between ultrastructural and motion features was evaluated by blinded clustering analysis of the first two principal components, obtained from ultrastructural variables for each patient. Soft computing was applied to ultrastructure to predict ciliary beat frequency (CBF) and motion patterns by a regression model. Another model classified the patients into the five most frequent PCD-causing gene groups, from their ultrastructure, CBF and beat patterns. The patients were subdivided into six clusters with similar values to homologous ultrastructural phenotype, motion patterns, and CBF, except for clusters 1 and 4, attributable to normal ultrastructure. The regression model confirmed the ability to predict functional ciliary features from ultrastructural parameters. The genetic classification model identified most of the different groups of genes, starting from all quantitative parameters. Applying soft computing methodologies to PCD diagnostic tests optimizes their value by moving from pattern recognition to quantification. The approach may also be useful to evaluate atypical PCD, and novel genetic abnormalities of unclear disease-producing potential in the future.

Selenite (IV) and selenate (VI) uptake and accumulation capacity of Lemna minor L. from an aquatic medium

ABSTRACT The uptake of sodium selenite (Se(IV)) and sodium selenate (Se(VI)) from aqueous medium by Lemna minor L. and the influence of different Se concentrations on its growth, morphological and ultrastructural characteristics were studied. L. minor was grown at different concentrations (1, 3, 5 and 10 mg L−1) of Se(IV) and Se(IV). The Se(IV) concentration in the plant tissue ranged between 77.7 (± 4.3) to 453 (± 0) mg kg−1 DW. The Se(VI) concentration in plant tissues ranged between 117 (± 11) to 417 (± 2) mg kg−1 DW. The highest bioconcentration factor for Se(VI) was 127 (± 7) at 3 mg/L, with a Se removal efficiency of 44%. For Se(IV), the highest bioconcentration factor was 77.7 (± 4.3) at 1 mg L−1, which had a Se removal efficiency of 23%. Growth of L. minor was suppressed at 10 mg L−1 Se in both forms. The addition of Se promoted the formation of starch granules in L. minor which occupied a chloroplast area of 74% for Se(IV) and 77% for Se(VI). The efficient uptake of both Se forms by L. minor indicates the potential application of this species for phytoremediation of Se laden wastewaters and its use as an alternative feedstock in biofuel production.

Enhancing pre-clinical research with simplified intestinal cell line models

Two-dimensional culture remains widely employed to determine the bioavailability of orally delivered drugs. To gain more knowledge about drug uptake mechanisms and risk assessment for the patient after oral drug admission, intestinal in vitro models demonstrating a closer similarity to the in vivo situation are needed. In particular, Caco-2 cell-based Transwell® models show advantages as they are reproducible, cost-efficient, and standardized. However, cellular complexity is impaired and cell function is strongly modified as important transporters in the apical membrane are missing. To overcome these limitations, primary organoid-based human small intestinal tissue models were developed recently but the application of these cultures in pre-clinical research still represents an enormous challenge, as culture setup is complex as well as time- and cost-intensive. To overcome these hurdles, we demonstrate the establishment of primary organoid-derived intestinal cell lines by immortalization. Besides exhibiting cellular diversity of the organoid, these immortalized cell lines enable a standardized and more cost-efficient culture. Further, our cell line-based Transwell®-like models display an organ-specific epithelial barrier integrity, ultrastructural features and representative transport functions. Altogether, our novel model systems are cost-efficient with close similarity to the in vivo situation, therefore favoring their use in bioavailability studies in the context of pre-clinical screenings.

Modelling and prevention of postoperative adhesions in gynaecological and pelvic surgery in experiment: morphological and ultrastructural features

Modelling and prevention of postoperative adhesions in gynaecological and pelvic surgery in experiment: morphological and ultrastructural features

Implications of Histological and Ultrastructural Characteristics on the Chemical and Mechanical Properties of Hypomineralised Enamel and Clinical Consequences.

Molar incisor hypomineralisation (MIH) is a qualitative type of enamel defect, which occurs due to a failure in the biomineralisation process of the enamel organic matrix during amelogenesis. The tooth enamel affected by MIH shows changes in its chemical, structural, and mechanical properties, leading to different clinical repercussions. The color of MIH opacities varies from opaque white to yellow/brown, and elemental analyses of these lesions show a lower calcium and phosphate content, minerals that are more abundant in sound enamel. Furthermore, the incorporation of other molecules occurs, such as carbonate, a component that provides a greater degree of solubility, thus making hypomineralised enamel more susceptible to posteruptive fractures. At a structural level, the layer of hydroxyapatite crystals appears to be disorganized, with morphological changes, implying a greater degree of porosity in the structure. The increase in porosity of the structure may be associated with dental hypersensitivity, a common clinical repercussion among patients with MIH. Among the mechanical properties, a decrease in hardness and modulus of elasticity occurs, and this also makes the enamel more fragile. Deficiency in biomineralisation can be caused by changes in the function of ameloblasts or by failures at the intercellular junction that result in lower activity of proteases such as MMP-20 and KLK4. The increase in proteins in the organic matrix of enamel impairs the growth and incorporation of minerals into the hydroxyapatite crystals, so that the enamel becomes hypomineralised and has larger organic content, thus having an impact on its properties. These changes present in the enamel with MIH help to explain the clinical repercussions caused by this condition.