Light Microscopy Research Articles

Modulated illumination microscopy: Application perspectives in nuclear nanostructure analysis.

The structure of the cell nucleus of higher organisms has become a major topic of advanced light microscopy. So far, a variety of methods have been applied, including confocal laser scanning fluorescence microscopy, 4Pi, STED and localisation microscopy approaches, as well as different types of patterned illumination microscopy, modulated either laterally (in the object plane) or axially (along the optical axis). Based on our experience, we discuss here some application perspectives of Modulated Illumination Microscopy (MIM) and its combination with single-molecule localisation microscopy (SMLM). For example, spatially modulated illumination microscopy/SMI (illumination modulation along the optical axis) has been used to determine the axial extension (size) of small, optically isolated fluorescent objects between ≤ 200nm and ≥ 40nm diameter with a precision down to the few nm range; it also allows the axial positioning of such structures down to the 1nm scale; combined with laterally structured illumination/SIM, a 3D localisation precision of ≤1nm is expected using fluorescence yields typical for SMLM applications. Together with the nanosizing capability of SMI, this can be used to analyse macromolecular nuclear complexes with a resolution approaching that of cryoelectron microscopy.

Expanding the Mesozoic Record of Early Brachyceran Fly Larvae, including New Larval Forms with Chimera-Type Morphologies.

Diptera are one of the four megadiverse groups of holometabolan insects. Flies perform numerous ecological functions, especially in their larval stages. We can assume that this was already the case in the past; however, fly larvae remain rare in most deposits. Here we report new dipteran larvae preserved in Cretaceous (about 99 Ma) Kachin amber from Myanmar and, even older, Jurassic (about 165 Ma) compression fossils from China. Through light microscopy and micro-CT scanning we explore their peculiar morphology and discuss their possible phylogenetic affinities. Several larvae seem to represent the lineage of Stratiomyomorpha. A few others present characters unique to Xylophagidae (awl-flies), as well as to Athericidae (water sniper-flies), resulting in a chimeric morphology. Understanding the exact relationships of most of these specimens with a particular lineage remains challenging, since they differ considerably from any other known dipteran larvae and present some unique traits. Additionally, we report new specimens of Qiyia jurassica Chen et al., 2014, supposedly parasitic larvae, most likely representatives of Athericidae. These new findings offer valuable insights into the evolution of the early diversification of the brachyceran flies and underscore the importance of immature stages in understanding the evolutionary history and ecology of flies.

Microanatomy of the human tunnel of Corti structures and cochlear partition-tonotopic variations and transcellular signaling.

Auditory sensitivity and frequency resolution depend on the optimal transfer of sound-induced vibrations from the basilar membrane (BM) to the inner hair cells (IHCs), the principal auditory receptors. There remains a paucity of information on how this is accomplished along the frequency range in the human cochlea. Most of the current knowledge is derived either from animal experiments or human tissue processed after death, offering limited structural preservation and optical resolution. In our study, we analyzed the cytoarchitecture of the human cochlear partition at different frequency locations using high-resolution microscopy of uniquely preserved normal human tissue. The results may have clinical implications and increase our understanding of how frequency-dependent acoustic vibrations are carried to human IHCs. A 1-micron-thick plastic-embedded section (mid-modiolar) from a normal human cochlea uniquely preserved at lateral skull base surgery was analyzed using light and transmission electron microscopy (LM, TEM). Frequency locations were estimated using synchrotron radiation phase-contrast imaging (SR-PCI). Archival human tissue prepared for scanning electron microscopy (SEM) and super-resolution structured illumination microscopy (SR-SIM) were also used and compared in this study. Microscopy demonstrated great variations in the dimension and architecture of the human cochlear partition along the frequency range. Pillar cell geometry was closely regulated and depended on the reticular lamina slope and tympanic lip angle. A type II collagen-expressing lamina extended medially from the tympanic lip under the inner sulcus, here named "accessory basilar membrane." It was linked to the tympanic lip and inner pillar foot, and it may contribute to the overall compliance of the cochlear partition. Based on the findings, we speculate on the remarkable microanatomic inflections and geometric relationships which relay different sound-induced vibrations to the IHCs, including their relevance for the evolution of human speech reception and electric stimulation with auditory implants. The inner pillar transcellular microtubule/actin system's role of directly converting vibration energy to the IHC cuticular plate and ciliary bundle is highlighted.

Anatomical Limitations in Adventitious Root Formation Revealed by Magnetic Resonance Imaging, Infrared Spectroscopy, and Histology of Rose Genotypes with Contrasting Rooting Phenotypes.

Adventitious root (AR) formation is one of the most important developmental processes in vegetative propagation. Although genotypic differences in rooting ability of rose are well known, the causing factors are not well understood. The rooting of two contrasting genotypes, 'Herzogin Friederike' and 'Mariatheresia', was compared following a multiscale approach. Using magnetic resonance imaging, we noninvasively monitored the inner structure of stem cuttings during initiation and progression of AR formation for the first time. Spatially resolved Fourier-transform infrared spectroscopy characterised the chemical composition of the tissues involved in AR formation. The results were validated through light microscopy and complemented by immunolabeling. The outcome demonstrated similarity of both genotypes in root primordia formation, which however, did not result in root protrusion through the shoot cortex in the difficult-to-root genotype 'Mariatheresia'. The biochemical composition of the contrasting genotypes highlighted main differences in cell wall-associated components. Further spectroscopic analysis of 15 contrasting rose genotypes confirmed the biochemical differences between easy- and difficult-to-root groups. Collectively, data indicates, that not the lack of root primordia limits AR formation in these rose genotypes, but the firmness of the outer stem tissue and/or cell wall modifications that pose a mechanical barrier and prevent root extension and protrusion.

Salt Tolerance Assessment in Triticum Aestivum and Triticum Durum.

Salt stress is a multicomponent phenomenon; it includes many processes that directly or indirectly affect the plant. Attempts have been made to comprehensively consider the processes of salt stress in plants Triticum aestivum (variety Orenburgskaya 22) and Triticum durum (variety Zolotaya). The study used methods of light and fluorescence microscopy, methods of immunofluorodetection, expression of DNA methyltransferase genes, genes of the ion transporter and superoxide dismutase families, as well as biochemical determination of total antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) reagent. According to morphometric indicators, the Orenburgskaya 22 variety showed greater tolerance to the action of 150 mM NaCl than the Zolotaya variety. The level of expression of genes of the HKT ion transporter family in the Orenburgskaya 22 variety is higher than in the Zolotaya variety. It was found that the expression of the DNA methyltransferase gene DRM2.1, which post-translationally methylates cytosine residues, is 22.3 times higher in Zolotaya compared to Orenburg 22 when exposed to salt. The accumulation of toxic ions is accompanied by an increase in reactive oxygen species (ROS) and increased damage to root tissue, especially in the Zolotaya variety. Using fluorescence microscopy using the Carboxy-H2DFF marker in the Orenburgskaya 22 variety at high NaCl concentrations, the highest fluorescence intensity was determined in the cap zone; in the Zolotaya variety-in the zones of the cap and root meristem. Excess ROS is more successfully removed in the Orenburgskaya 22 variety, which has a higher level of antioxidant activity (AOA), as well as the level of expression of the Cu/ZnSOD and MnSOD superoxide dismutase genes. Using programmed cell death (PCD) markers based on the release of cytochrome c from mitochondria into the cytoplasm, DNA breakage and the release of phosphatidylserine from mitochondria, the degree of damage to root cells was assessed in both wheat varieties. It has been proven that wheat cell death occurs through the mitochondrial pathway. It was noted that the salt-sensitive variety Zolotaya had a significant number of necrotic cells. Based on the data obtained, it was concluded that the Orenburgskaya 22 variety exhibits greater resistance to salinity than the Zolotaya variety. These data may be of practical importance for enhancing protective mechanisms under abiotic stress.

From Blur to Brilliance: The Ascendance of Advanced Microscopy in Neuronal Cell Biology.

The intricate network of the brain's neurons and synapses poses unparalleled challenges for research, distinct from other biological studies. This is particularly true when dissecting how neurons and their functional units work at a cell biological level. While traditional microscopy has been foundational, it was unable to reveal the deeper complexities of neural interactions. However, an imaging renaissance has transformed our capabilities. Advancements in light and electron microscopy, combined with correlative imaging, now achieve unprecedented resolutions, uncovering the most nuanced neural structures. Maximizing these tools requires more than just technical proficiency. It is crucial to align research aims, allocate resources wisely, and analyze data effectively. At the heart of this evolution is interdisciplinary collaboration, where various experts come together to translate detailed imagery into significant biological insights. This review navigates the latest developments in microscopy, underscoring both the promise of and prerequisites for bending this powerful tool set to understanding neuronal cell biology.

A brief history of the Feulgen reaction.

One hundred years ago, Robert Feulgen published a landmark paper in which he described the first method to stain DNA in cells and tissues. Although a century has passed since the discovery by Feulgen and Rossenbeck, the chemical reaction still exerts an important influence in current histochemical studies. Its contribution in diverse fields, spanning from biomedicine to plant biology, has paved the way for the most significant studies that constitute our current knowledge. The possibility to specifically explore the DNA in cell nuclei while quantifying its content makes it a contemporary and timeless method. Indeed, many histocytochemical studies following the 1924 paper have led to a deep understanding of genome organization in general as well as several specific mechanisms (e.g. DNA duplication or tumour pathology) that, nowadays, constitute some of the most fundamental pillars in biological investigations. In this review, we discuss the chemistry and application of the Feulgen reaction to both light and electron microscopy.

An On-Farm Workflow for Predictive Management of Paralytic Shellfish Toxin-Producing Harmful Algal Blooms for the Aquaculture Industry.

Paralytic shellfish toxins (PSTs) produced by marine dinoflagellates significantly impact shellfish industries worldwide. Early detection on-farm and with minimal training would allow additional time for management decisions to minimize economic losses. Here, we describe and test a standardized workflow based on the detection of sxtA4, an initial gene in the biosynthesis of PSTs. The workflow is simple and inexpensive and does not require a specialized laboratory. It consists of (1) water collection and filtration using a custom gravity sampler, (2) buffer selection for sample preservation and cell lysis for DNA, and (3) an assay based on a region of sxtA, DinoDtec lyophilized quantitative polymerase chain reaction (qPCR) assay. Water samples spiked with Alexandrium catenella showed a cell recovery of >90% when compared to light microscopy counts. The performance of the lysis method (90.3% efficient), Longmire's buffer, and the DinoDtec qPCR assay (tested across a range of Alexandrium species (90.7-106.9% efficiency; r2 > 0.99)) was found to be specific, sensitive, and efficient. We tested the application of this workflow weekly from May 2016 to 30th October 2017 to compare the relationship between sxtA4 copies L-1 in seawater and PSTs in mussel tissue (Mytilus galloprovincialis) on-farm and spatially (across multiple sites), effectively demonstrating an ∼2 week early warning of two A. catenella HABs (r = 0.95). Our tool provides an early, accurate, and efficient method for the identification of PST risk in shellfish aquaculture.

The impact of temperature on increased airborne pollen and earlier onset of the pollen season in Trentino, Northern Italy

The impact of climate change on ecosystems can be assessed through pollen dispersion data, which acts as a proxy for the plant flowering stage. The aim of this study is to verify if changes occurred in the season and concentration of airborne pollen in Trentino (Northern Italy), and to evaluate if temperature (T), precipitation (P), and/or land use influenced such changes in the period 1989–2018. Airborne pollen, sampled by a Hirst-type trap, was analyzed by light microscopy, and pollen concentrations were obtained. Twenty-four taxa, covering 95% of the local pollen spectrum, were considered for this study. A significant upward trend in annual pollen integral (APIn) is the main outcome over the study period. The increase in APIn is more evident when analyzing the data in three decadic blocks, both for all the considered taxa (+ 58%) and for Arboreal Pollen (AP; + 155%). Considering both the annual data and the decadic blocks, APIn shows a significant positive trend for Cupressaceae/Taxaceae, Ulmus, Populus, Salix, Ostrya, Quercus, Olea (AP), and Plantago, Cannabaceae, Ambrosia (non-arboreal pollen, NAP); a significantly earlier start of the Main Pollen Season (MPS) is proved for Rumex and Poaceae. APIn for 24 taxa shows a significant positive correlation with annual T min (< 0.005) and T mean (< 0.001), both of which showing a significant increase, and a negative correlation (< 0.025) with the number of frost days. From a human health perspective, higher temperatures, driven by climate changes, lead to higher concentrations of allergenic airborne pollen, turning into a higher risk for allergy sufferers.

Critical revision of Physarales and Reticulariales (Myxomycetes) at the Natural History Museum London (BM)

Light and scanning electron microscopy were applied to re-assess diagnostic characters of type specimens and critical specimens of Diachea radiata, D. splendens, D. subsessilis, Diderma arboreum, Didymium. laxifilum, D. leoninum var. effusum, D. trachysporum, D. trochus, Physarum bitectum, P. straminipes, Reticularia intermedia, R. jurana, R. liceoides, R. lobata and Wilczekia evelinae in the order Physarales and Reticulariales (Myxomycetes) from the collections at the Natural History Museum London (BM). The results were used to discuss published data and the type status for specimens studied.

Mesomorphism and Tribotechnical Characteristics of Lubricant Compositions with Mesogenic Additives Carboxylates Cu(II)

The purpose of the work is to characterize the lubricants based on Llitol-24 and synthetic solidol with additives copper(II) carboxylates when using them in friction nodes in loading conditions and temperature. The lubricant compositions with additives copper(II) carboxylates based on synthetic solidol and Litol-24 form the columnar mesophases depending on thermodynamical conditions and concentration of additives.Methods. We study the lubricant compositions with dielectric spectroscopy and и polarization light microscopy. The studies lubricant compositions are tested on the frictional machines by preceding authors, which performed their synthesis and numerical estimations for their geometry parameters. It is shown, that the columnar mesophase formed by the compositions with copper(II) carboxylates simulates favourable tribological conditions for lubrication (reduction of the friction coefficient at the appointed range of additive concentrations and reduction of wear) and unlike to crystalline phases, shows orientation effects at the surface of interacting surfaces of machine elements and devices. These factsmotivate the study of influence of physicochemical properties and composition on mesomorphism of considered lubricant compositions.Results. In our measurements, we found the main dielectric characteristics of two kinds of the lubricant compositions: dielectric constant and dielectric loss, electroconductivity, dissipation factor, the Arrhenius functions are plotted, and the activation energies of the lubricant compositions we study are calculated. The microphotogram for textures of the lubricant compositions depending on temperature and concentrations are received. The differences in mesomorphic properties of the lubricant compositions with additives Cu(II) valerate and isovalerate are confirmed.The conclusion of the work is that the composition of the lubricant is optimized by the choice of additive concentration, the length of the mesogenic chain of the copper(II) carboxylate molecule and its conformation.

Mutation mapping of a variegated EMS tomato reveals an FtsH-like protein precursor potentially causing patches of four phenotype classes in the leaves with distinctive internal morphology

BackgroundLeaf variegation is an intriguing phenomenon observed in many plant species. However, questions remain on its mechanisms causing patterns of different colours. In this study, we describe a tomato plant detected in an M2 population of EMS mutagenised seeds, showing variegated leaves with sectors of dark green (DG), medium green (MG), light green (LG) hues, and white (WH). Cells and tissues of these classes, along with wild-type tomato plants, were studied by light, fluorescence, and transmission electron microscopy. We also measured chlorophyll a/b and carotene and quantified the variegation patterns with a machine-learning image analysis tool. We compared the genomes of pooled plants with wild-type-like and mutant phenotypes in a segregating F2 population to reveal candidate genes responsible for the variegation.ResultsA genetic test demonstrated a recessive nuclear mutation caused the variegated phenotype. Cross-sections displayed distinct anatomy of four-leaf phenotypes, suggesting a stepwise mesophyll degradation. DG sectors showed large spongy layers, MG presented intercellular spaces in palisade layers, and LG displayed deformed palisade cells. Electron photomicrographs of those mesophyll cells demonstrated a gradual breakdown of the chloroplasts. Chlorophyll a/b and carotene were proportionally reduced in the sectors with reduced green pigments, whereas white sectors have hardly any of these pigments. The colour segmentation system based on machine-learning image analysis was able to convert leaf variegation patterns into binary images for quantitative measurements. The bulk segregant analysis of pooled wild-type-like and variegated progeny enabled the identification of SNP and InDels via bioinformatic analysis. The mutation mapping bioinformatic pipeline revealed a region with three candidate genes in chromosome 4, of which the FtsH-like protein precursor (LOC100037730) carries an SNP that we consider the causal variegated phenotype mutation. Phylogenetic analysis shows the candidate is evolutionary closest to the Arabidopsis VAR1. The synonymous mutation created by the SNP generated a miRNA binding site, potentially disrupting the photoprotection mechanism and thylakoid development, resulting in leaf variegation.ConclusionWe described the histology, anatomy, physiology, and image analysis of four classes of cell layers and chloroplast degradation in a tomato plant with a variegated phenotype. The genomics and bioinformatics pipeline revealed a VAR1-related FtsH mutant, the first of its kind in tomato variegation phenotypes. The miRNA binding site of the mutated SNP opens the way to future studies on its epigenetic mechanism underlying the variegation.

Topological Defects in Tactoid Nematic Phase

The purpose research of the work is to illustrate the role of point surface topological defects in nematics in phase transitions using the example of inorganic sols of vanadium pentoxide in water V2O5/H2O.Methods. Basing on the measurements on polarization light microscopy and theoretically, in frames of the Landau-de Gennes model and the Kibble-Zurek model for defects, the influence of point topological defects at the surface of nematic colloid of lyotropic liquid crystals, in particular, in inorganic sols of the V2O5/H2O system, on their critical thermodynamic, electric, optical, elastic and mechanical properties is estimated. For the system V2O5/H2O, we study the developed models of nematic colloid phases with non-trivial topology composed of spindle-shaped particles, in which their topological defects are classified; geometrical parameters of nematic particles in dynamics and evolution depending on physicochemical conditions, phase stability criteria, conditions for coalescence of particles, including, under external magnetic field, and also, experimental observations confirmed the proposed theories and models, are considered.Results. With a glance of coalescence regime, the critical size of a colloid particle of the system V2O5/H2O, ~ 10 nm in the long axis direction, in which the value of magnetic energy equals to the sum of elastic and surface energy of acolloid particle, is estimated.Conclusion. We confirmed, that the prerequisite of sol particle coalescence in the system V2O5/H2O in the magnetic field is annihilation of the point topological defects at their poles, the geometrical criterion of tactoid coalescence in magnetic field is established basing on the different theories of their surface defects.

Morphological changes in the testicle in "Sertoli cell only" syndrome in men with non-obstructive azoospermia

BACKGROUND: The relevance of morphological studying of testicular biopsies in infertile men is explained by the small amount of information and research in this area, which is associated with limited indications for obtaining a lifetime biopsy in this disease.&#x0D; AIM: To evaluate morphological changes in the testicle in Sertoli cell-only syndrome (SCOS).&#x0D; MATERIALS AND METHODS: Using staining of sections with hematoxylin and eosin, toluidine blue, a morphological assessment of convoluted seminal tubules with SCOS was performed using light microscopy in 9 men with non-obstructive azoospermia.&#x0D; RESULTS: Mature Sertoli cells were found in 48.2% of convoluted seminal tubules, Sertoli cells with signs of dystrophy were in 33.6% of seminal tubules, Sertoli cells with signs of apoptosis were found in 18.2% of seminal tubules. The average number of Sertoli cells in one convoluted seminal tubule was 15.4±6.1. The diameter of the convoluted seminal tubule was on average 33.8±9.6 microns. The thickness of the shell of the convoluted seminal tubule in SCOS was on average 0.63 ± 0.18 microns. The number of mast cells in the testicular interstitium was on average 8.5±0.3 per 1 mm2. The relationship between the thickness of the shell of the convoluted seminal tubule and the number of Sertoli cells was strong and inverse (r=-0.87). The relationship between the thickness of the membrane of the convoluted seminal tubule and the number of mast cells in the testicular interstitium was strong and direct (r=0.83).&#x0D; CONCLUSIONS: SCOS occurs in 47.3% of patients with non-obstructive azoospermia. An increase in the thickness of the shell of the convoluted seminal tubule contributes to a violation of the architectonics of the hematotesticular barrier. This study showed that mast cells have a direct effect on the wall thickness of the convoluted seminal tubule, which demonstrates the possible pathological effect of these cells on the permeability of the hematotesticular barrier and impaired spermatogenesis.

Sphaerocrystals in seeds of Euphorbia subgenus Esula (Euphorbiaceae): morphology, occurrence, and relationship with phylogeny

Abstract The term ‘sphaerocrystals’ (also sphaerites) in classic plant morphology was usually applied to spherical bodies visible in polarized light with a characteristic ‘Maltese cross’ and consisting of both inorganic and organic compounds. Initially sphaerocrystals were found in algal cells but were later also discovered in various organs of vascular plants (including seeds). Several authors noticed spherical particles on the seed surface and in testa cells of some Euphorbia species but a comprehensive study of this character in the genus (including the morphological origin of such particles) has not been carried out. We studied 72 species belonging to all 21 sections of Euphorbia subgenus Esula for presence of spherical particles on seed surface and in the testa using scanning, transmission, confocal laser electron microscopy, and light microscopy; histochemical and element analyses were also involved. We found that these particles have the same morphological features (including the demonstration of ‘Maltese cross’ in polarized light) as the ‘classic’ sphaerocrystals. We have recorded sphaerocrystals in 53 sampled species belonging to 20 sections of Euphorbia subgenus Esula; they are localized mostly in mesotesta cells and in some species are exuded onto the seed surface where they are often aggregated into clusters. Sphaerocrystals were absent in the sampled species (with one exception) of one of the major clades of the subgenus, formed by E. sect. Helioscopia and E. sect. Holophyllum. The absence of sphaerocrystals in this early divergent lineage of E. subgen. Esula may be related with adaptation of species of this lineage to more mesic habitats.

Evaluation of 3D-Printed Solid Microneedles Coated with Electrosprayed Polymeric Nanoparticles for Simultaneous Delivery of Rivastigmine and N-Acetyl Cysteine.

In the current study, coated microneedle arrays were fabricated by means of digital light processing (DLP) printing. Three different shapes were designed, printed, and coated with PLGA particles containing two different actives. Rivastigmine (RIV) and N-acetyl-cysteine (NAC) were coformulated via electrohydrodynamic atomization (EHDA), and they were incorporated into the PLGA particles. The two actives are administered as a combined therapy for Alzheimer's disease. The printed arrays were evaluated regarding their ability to penetrate skin and their mechanical properties. Optical microscopy and scanning electron microscopy (SEM) were employed to further characterize the microneedle structure. Confocal laser microscopy studies were conducted to construct 3D imaging of the coating and to simulate the diffusion of the particles through artificial skin samples. Permeation studies were performed to investigate the transport of the drugs across human skin ex vivo. Subsequently, a series of tape strippings were performed in an attempt to examine the deposition of the APIs on and within the skin. Light microscopy and histological studies revealed no drastic effects on the membrane integrity of the stratum corneum. Finally, the cytocompatibility of the microneedles and their precursors was evaluated by measuring cell viability (MTT assay and live/dead staining) and membrane damages followed by LDH release.

The smart apple-based foil: The role of pectin-glycerol-lipid interactions on thermoresponsive mechanism

In this article, fully biodegradable films based on high methylated (HM) apple pectin, glycerol, and margarine were made. The influence of different crosslinking agents on the structure and functional properties of the obtained films was investigated. Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TG), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS) and polarized light microscopy (POM) analyses showed the key importance of the crosslinking agent on the chemical interactions between the individual components of system. A series of phase transitions related to the melting of lipid fractions have been observed, which occur in a cascade with increasing temperature. Thermomechanical analysis (TMA) indicated that the obtained samples show a rapid change in dimensions as a function of temperature. Measurements of the impedance spectroscopy demonstrated that foil’s electrical parameters change as a function of temperature. Both shape and conductivity changes are related to processes occurring in the pectin-glycerol-lipid system. It was found that the pectin glass transition, lower critical solution temperature (LCST) and lipid melting had the most pronounced effect on the operational properties. Taking into account the obtained results, the developed apple foils may have potential applications as thermosensitive smart materials for example in active packaging as sensing materials.

Toxic effects of aniline in liver, gills and kidney of freshwater fish Channa punctatus after acute exposure

Aniline (C6H5NH2) is one of the hazardous aromatic amine where an amino group -NH2) is connected to phenyl ring (C6H5). Based on the evaluation of the 96-hour LC50 of aniline, two sublethal concentrations (4.19 mg/l and 8.39 mg/l) were selected for acute exposure tests in freshwater fish Channa punctatus. The liver, gills and kidney of fish being the principal sites of xenobiotic material accumulation, respiration, biotransformation, and excretion are the focus of the present study. Throughout the exposure time, the comet assay revealed increased tail length and tail DNA percentage indicating maximum damage to liver, gills and kidney of treated group after 96 h. After acute exposure, there was a significant (p ≤ 0.05) increase in the enzymatic activity of glutathione-S-transferase (GST) and acetylcholinesterase (AChE), whereas decline in superoxide dismutase (SOD) and catalase (CAT) activity was observed. Meanwhile, levels of malondialdehyde (MDA) increased over the exposure period for both concentrations. After 96 h of exposure, degree of tissue change (DTC) was evaluated in liver, gill and kidney of aniline exposed fish. Additionally, light microscopy revealed multiple abnormalities in liver, gills and kidney of all the treated groups. Significant changes were observed in the levels of biochemical markers viz., glucose, triglyceride, cholesterol, aspartate transaminase, alanine transaminase and urea following a 96-hour exposure to aniline. Studies using ATR-FTIR and transmission electron microscopy (TEM) revealed changes in biomolecules and structural abnormalities in several tissues of the aniline-exposed groups in comparison to the control group respectively.

Multimodal imaging analysis in silver fir reveals coordination in cellulose and lignin deposition.

Despite lignin being a key component of wood, the dynamics of tracheid lignification are generally overlooked in xylogenesis studies, which hampers our understanding of environmental drivers and blurs the interpretation of isotopic and anatomical signals stored in tree rings. Here, we analyzed cell wall formation in silver fir (Abies alba Mill.) tracheids to determine if cell wall lignification lags behind secondary wall deposition. For this purpose, we applied a multimodal imaging approach combining transmitted light microscopy (TLM), confocal laser scanning microscopy (CLSM), and confocal Raman microspectroscopy (RMS) on anatomical sections of wood microcores collected in northeast France on 11 dates during the 2010 growing season. Wood autofluorescence after laser excitation at 405 nm and 488 nm associated with the RMS scattering of lignin and cellulose, respectively, which allowed identification of lignifying cells (cells showing lignified and non-lignified wall fractions at the same time) in CLSM images. The number of lignifying cells in CLSM images mirrored the number of wall-thickening birefringent cells in polarized TLM images, revealing highly synchronized kinetics for wall thickening and lignification (similar timings and durations at the cell level). CLSM images and RMS chemical maps revealed a substantial incorporation of lignin into the wall at early stages of secondary wall deposition. Our results show that most of the cellulose and lignin contained in the cell wall undergo concurrent periods of deposition. This suggests a strong synchronization between cellulose and lignin-related features in conifer tree-ring records, as they originated over highly overlapped time frames.

Mechanical Properties of the AlCu4Mg1 Alloy Joint Manufactured by Underwater Friction Stir Welding.

The manuscript presents the results of butt joining of 3-millimeter-thick AlCu4Mg1 alloy sheets using the FSW (friction stir welding) and UWFSW (underwater friction stir welding) methods. The aim of the research is to verify the influence of the water environment on the FSW friction welding process. The article checked three sets of joint parameters. The parameters differed in tool rotation speed and feed rate. The same sets of parameters were used for the FSW and UWFSW fusion techniques. With the supplied devices, metallographic sections are cross-sectioned, and the power supplies are subjected to a light microscope. Microhardness tests and the influence of the heat-affected zone were carried out. A monotonic test was performed. A monotonic test is available, extended with a visual correlation test. The obtained cracked fracture surfaces were examined using a scanning microscope. An analysis of the microfractographic cracking process was carried out. The obtained results did not show any improvement in the strength properties of the obtained joints made using the UWFSW technique when using a scanning microscope.