Light Microscopy Research Articles

Strategies for selecting and managing equipment in a light microscopy facility.

Light microscopy facilities vary in the number of imaging systems and the scope of technologies they support. Each facility must craftan identity through the selection of equipment and development of staff in order to serve the needs of its local research environment. The process of crafting a light microscopy facility can be compared to curation of an art exhibition: great care should be given to the selection and placement of each object in order to make a coherent statement. Lay Description: Light microscopy facilities vary in the number of imaging systems and the scope of technologies they support. Each facility must develop an identity through the selection of equipment and development of staff in order to serve the needs of its local research environment. The process of crafting a light microscopy facility can be compared to curation of an art exhibition: great care should be given to the selection and placement of each object in order to make a coherent statement.

Wavy grain in sycamore maple (Acer pseudoplatanus) — a structural analysis of xylem and phloem

Summary Wavy grain (fiddle back) in trees has attracted the interest of both science and industry due to its aesthetic and economic importance. As the underlying causes of this particular structural feature in trees remain uncertain, this study investigates the possibility of non-invasively detecting wavy grain patterns within tree bark tissue of sycamore maple (Acer pseudoplatanus). Wavy grain, characterized by alternating light and dark stripes on the wood surface, is highly valued in the production of musical instruments. This research explores the potential of employing transmission light microscopy and microcomputer tomography (μCT) to examine the internal structure of phloem tissue to inspect whether the wavy grain structure found in the xylem continues in the bark. The investigation of phloem tissue proved challenging due to its irregular cellular arrangement. Nonetheless, slight phloem fibre deviations were observed in individual trees. However, no definite connection was found between the periodic oscillations of the xylem fibre tissue and the structure of the phloem in a given area. Variability in wavy grain expression among the xylem of the trees posed an additional challenge, with amplitudes and wavelengths differing across specimens. The application of μCT offered advantages over traditional sample preparation, enabling the study of the anatomical structure across larger areas and multiple depths without altering the specimen. This study sheds light on the potential of employing advanced imaging techniques to detect wavy grain patterns, providing insights that could benefit industries reliant on high-quality wood, such as musical instrument crafting and forestry.

Ultrastructural and immunohistochemical evaluation of hyperplastic soft tissues surrounding dental implants in fibular jaws

In reconstructive surgery, complications post-fibula free flap (FFF) reconstruction, notably peri-implant hyperplasia, are significant yet understudied. This study analyzed peri-implant hyperplastic tissue surrounding FFF, alongside peri-implantitis and foreign body granulation (FBG) tissues from patients treated at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. Using light microscopy, pseudoepitheliomatous hyperplasia, anucleate and pyknotic prickle cells, and excessive collagen deposition were observed in FFF hyperplastic tissue. Ultrastructural analyses revealed abnormal structures, including hemidesmosome dilation, bacterial invasion, and endoplasmic reticulum (ER) swelling. In immunohistochemical analysis, unfolded protein-response markers ATF6, PERK, XBP1, inflammatory marker NFκB, necroptosis marker MLKL, apoptosis marker GADD153, autophagy marker LC3, epithelial–mesenchymal transition, and angiogenesis markers were expressed variably in hyperplastic tissue surrounding FFF implants, peri-implantitis, and FBG tissues. NFκB expression was higher in peri-implantitis and FBG tissues compared to hyperplastic tissue surrounding FFF implants. PERK expression exceeded XBP1 significantly in FFF hyperplastic tissue, while expression levels of PERK, XBP1, and ATF6 were not significantly different in peri-implantitis and FBG tissues. These findings provide valuable insights into the interconnected roles of ER stress, necroptosis, apoptosis, and angiogenesis in the pathogenesis of oral pathologies, offering a foundation for innovative strategies in dental implant rehabilitation management and prevention.

A methodology for phase characterization in pellet feed using digital microscopy and deep learning

This work proposes a new method for characterizing pellet feed, employing Deep Learning (DL) and Convolutional Neural Networks (CNNs). The main minerals in the composition of the studied pellet feed are hematite, magnetite, goethite, and quartz. Over time, several characterization methodologies have been developed that use Digital Microscopy and Image Analysis tools. The greatest difficulties in this characterization lie in differentiating the textures of hematite particles, the different shapes of their crystals, or discriminating between quartz and resin in reflected light optical microscopy images. This work proposes a mineral characterization methodology based on the Mask R-CNN algorithm. The goal is to perform instance segmentation, that is, to identify, classify, and segment objects in the images. Two DL models were combined: the BF Model performs instance segmentation for the compact, porous, martite, and goethite classes in images obtained in Bright Field mode, and the CPOL Model uses images acquired in Circularly Polarized Light to segment the monocrystalline, polycrystalline, and martite classes. An F1-score of around 80% was obtained for the BF Model and around 90% for the CPOL Model. The results were promising and can be improved as the training image database increases.

An Update on the Use of Artificial Intelligence in Digital Pathology for Oral Epithelial Dysplasia Research.

Oral epithelial dysplasia (OED) is a precancerous histopathological finding which is considered the most important prognostic indicator for determining the risk of malignant transformation into oral squamous cell carcinoma (OSCC). The gold standard for diagnosis and grading of OED is through histopathological examination, which is subject to inter- and intra-observer variability, impacting accurate diagnosis and prognosis. The aim of this review article is to examine the current advances in digital pathology for artificial intelligence (AI) applications used for OED diagnosis. We included studies that used AI for diagnosis, grading, or prognosis of OED on histopathology images or intraoral clinical images. Studies utilizing imaging modalities other than routine light microscopy (e.g., scanning electron microscopy), or immunohistochemistry-stained histology slides, or immunofluorescence were excluded from the study. Studies not focusing on oral dysplasia grading and diagnosis, e.g., to discriminate OSCC from normal epithelial tissue were also excluded. A total of 24studies were included in this review. Nineteen studies utilized deep learning (DL) convolutional neural networks for histopathological OED analysis, and 4 used machine learning (ML) models. Studies were summarized by AI method, main study outcomes, predictive value for malignant transformation, strengths, and limitations. ML/DL studies for OED grading and prediction of malignant transformation are emerging as promising adjunctive tools in the field of digital pathology. These adjunctive objective tools can ultimately aid the pathologist in more accurate diagnosis and prognosis prediction. However, further supportive studies that focus on generalization, explainable decisions, and prognosis prediction are needed.

Glomerular Diameter Measurements on Light Microscopy: A New Parameter Available to Pathologists and its Utility in IgA Nephropathy

Background: With the availability of whole slide digital scanners, fairly accurate glomerular diameter (GD) measurements are now possible on light microscopy. The value of these measurements in prognosis and diagnosis of immunoglobulin A nephropathy (IgAN) have not been studied widely. IgAN is a major cause of end-stage renal disease (ESRD) worldwide, and its progression is currently assessed using Oxford scores, serum creatinine, and 24-h urinary protein. We aimed to correlate the mean and maximum GDs with serum creatinine, 24-h urinary protein, and Oxford scores in patients with IgAN. Materials and Methods: One hundred biopsies of IgAN with a minimum of eight viable glomeruli were collected along with data of their 24-h proteinuria, serum creatinine, and Oxford scores. The slides were scanned using the Philips IntelliSite Pathology Solution-Ultra Fast Scanner. Mean GD of each glomerulus was calculated as the mean of two measurements, that is, the maximal diameter of the glomerulus and the maximal chord perpendicular to the maximal diameter. Maximum GD was also recorded for each case. The Spearman rho/Pearson R correlation coefficient was used to make this correlation. P-values <0.05 were considered statistically significant. Results: The mean age of the patients was 34.67 ± 12.03 years, and they showed a male preponderance. The overall mean GD was 151.82 ± 28.69 µm, and maximum GD was 205.40 ± 32.76 µm. No statistically significant correlation was observed between the mean or maximum GD and the 24-h proteinuria, serum creatinine levels, and Oxford scores. Conclusion: GD in IgAN does not correlate with proteinuria, serum creatinine, or Oxford scores.

Scale morphology variability in cyprinid fishes and its significance in taxonomy using light and scanning electron microscopy: A case study of the genus Garra Hamilton, 1822 (Teleostei: Cyprinidae).

To evaluate scale morphological variability (shape, size, topological macro- and microstructures, ornamentation patterns) of cyprinid fishes, nine species of the genus Garra were selected and their scales from five different body regions were studied by using light and scanning electron microscopy. The scales of the examined species were thin with a central or antero-centrally positioned focus, with no cteni in the posterior part. In addition to these typical characteristics, some morphological variation was observed in the overall shape (irregular round, true oval, round-triangular, irregular pentagonal, hexagonal, irregular hexagonal, pentagonal, ovoid), and the focus shape. These variations were mainly dependent on the fish lengths and the flank region. Morphological analysis clustered the examined species into two distinct groups. Group I consisted of G. amirhosseini and G. gymnothorax, while Group II has three subgroups, which include G. persica and G. mondica (subgroup I), G. meymehensis, G. rossica, G. nudiventris, G. hormuzensis (subgroup II), and G. rufa (subgroup III). The grouping of the studied Garra species based on the current scale morphological characters and the molecular data was only consistent for G. rossica and G. nudiventris. In addition, in the phylogenetic tree, G. persica, G. mondica, G. amirhosseini, and G. hormuzensis formed a distinct clade. However, these species did not represent close relationships in the dendrogram obtained from the scale morphology. A possible explanation why the grouping of the studied Garra species based on their scale morphological characters does not match their phylogenetic relationships is that most of the scale morphological traits vary depending on the fish size and the location of the scales on the flank. Therefore, except for some traits, that is, central or antero-centrally positioned focus, having no cteni, a specific sectioned form so called "tetra-sectioned" type, the other examined variables are not useful enough to be used in the taxonomic study of the examined cyprinid fishes. Therefore, scale morphological characters should be used carefully for taxonomic purposes. RESEARCH HIGHLIGHTS: Shape, size, topological macro- and microstructures, and ornamentation patterns of nine species of the genus Garra were studied by using light and scanning electron microscopy. The scales were thin with a central or antero-centrally positioned focus, with no cteni in the posterior part. Morphological variation was observed in the overall shape (irregular round, true oval, round-triangular, irregular pentagonal, hexagonal, irregular hexagonal, pentagonal, and ovoid), and the focus shape. The grouping of Garra species based on the current scale morphological characters and the molecular data was only consistent for G. rossica and G. nudiventris.

Mitochondrial calcium overload contributes to cannabinoid‐induced paraptosis in hormone‐responsive breast cancer cells

AbstractStudies have shown that natural products can induce paraptosis in tumour cell lines. Paraptosis is characterized by cytoplasmic vacuolation arising from the endoplasmic reticulum (ER) and mitochondria. The mechanism of paraptosis is unclear; however, dysregulation of Ca2+ homeostasis is believed to affect paraptosis induction. This study investigated the mechanism of cell death induced by a phytocannabinoid ratio in the MCF7 breast cancer cell line. The crystal violet assay was used to detect changes in viability and morphology changes were investigated using light and transmission electron microscopy. Various inhibitors, fluorescent staining with high‐content screening, and Western blot analysis were used to investigate different cell death mechanisms. The phytocannabinoid ratio induced significant cell death and cytoplasmic vacuolation in MCF7 cells; however, no apoptosis, necrosis, autophagy, or ferroptosis was detected. Vacuolation induced by phytocannabinoid treatment was inhibited by cycloheximide, suggesting paraptosis induction. The mechanism of paraptosis induction was investigated, and it was found that treatment (1) induced ER dilation and mitochondrial swelling, (2) induced significant ER stress and mitochondrial Ca2+ overload and dysfunction, which appeared to be mediated by the voltage‐dependent anion channel, and (3) significantly impaired all mitochondrial metabolic pathways. The data demonstrated that paraptosis induced by the cannabinoid ratio was mediated by Ca2+ flux from the ER to the mitochondria. These findings highlight a novel mechanism of cannabinoid‐induced cell death and emphasize the anti‐cancer potential of cannabinoid ratios, which exhibited enhanced effects compared to individual cannabinoids.

Metallographic Etching of Al–Mg–Zn–(Cu) Crossover Alloys

Various alloys demand customized etchants due to their diverse chemical compositions, particularly in the realm of aluminum alloys. Consequently, in this study, a technique is proposed for metallographic visualization of small grain structures within Al–Mg–Zn–(Cu) crossover alloys. In this method, a thermal pretreatment combined with an etching process is relied on. In the study, it is primarily sought to comprehend how grain‐boundary precipitation affects etchability, addressing the complexities of characterizing these alloys. The demonstrated approach facilitates the swift assessment of grain sizes <10 μm using light optical microscopy. Exploring the etchability of Al–Mg–Zn–(Cu) crossover alloys across a standard heat‐treatment pathway identifies the optimal treatment and suitable etchant for grain visualization. Through process refinement, a reduction in processing time is achieved by employing a single‐step preheat treatment lasting 20 min at 180 °C post solution annealing. Transmission electron microscope analysis reveals continuous occupancy of the grain boundary with T‐phase as the key factor influencing the alloy's etchability. Grain size assessment involves line intercept counting and equivalent circle diameter measurement for precise characterization.

Human iPSC-derived neurons with reliable synapses and large presynaptic action potentials

Understanding the function of the human brain requires determining basic properties of synaptic transmission in human neurons. One of the most fundamental parameters controlling neurotransmitter release is the presynaptic action potential, but its amplitude and duration remain controversial. Presynaptic action potentials have so far been measured with high temporal resolution only in a limited number of vertebrate but not in human neurons. To uncover properties of human presynaptic action potentials, we exploited recently developed tools to generate human glutamatergic neurons by transient expression of Neurogenin 2 (Ngn2) in pluripotent stem cells. During maturation for 3 to 9 weeks of culturing in different established media, the proportion of cells with multiple axon initial segments decreased, while the amount of axonal tau protein and neuronal excitability increased. Super-resolution microscopy revealed the alignment of the pre- and postsynaptic proteins, Bassoon and Homer. Synaptic transmission was surprisingly reliable at frequencies of 20, 50, and 100 Hz. The synchronicity of synaptic transmission during high-frequency transmission increased during 9 weeks of neuronal maturation. To analyze the mechanisms of synchronous high-frequency glutamate release, we developed direct presynaptic patch-clamp recordings from human neurons. The presynaptic action potentials had large overshoots to ∼25 mV and short durations of ∼0.5 ms. Our findings show that Ngn2-induced neurons represent an elegant model system allowing for functional, structural, and molecular analyses of glutamatergic synaptic transmission with high spatio-temporal resolution in human neurons. Furthermore, our data predict that glutamatergic transmission is mediated by large and rapid presynaptic action potentials in the human brain.Significance statementPresynaptic physiology remains poorly understood despite its relevance to neurological and psychiatric diseases. Studying presynaptic functions in human iPSC-derived neurons offers the important advantage of characterizing molecular mechanisms of neurotransmitter release in neurons derived from diseased patients. As a first step towards this goal, we established direct presynaptic whole-cell patch-clamp recordings from human glutamatergic neurons induced by transient Neurogenin 2 overexpression. We furthermore analyzed the structure of the synapses with super-resolution light microscopy and the synaptic short-term plasticity during high-frequency transmission. Our findings show that synchronous high-frequency transmission is mediated by rapid and large presynaptic action potentials in human neurons, similar to small conventional nerve terminals of rodent neurons.

An insight into viscosity and conductivity in the formulation of co-axial electrospun Carica papaya leaf extract

Objective: This research aimed to investigate the application of the coaxial electrospun method for the production of natural extracts (papaya leaf extract) fibre films. This was achieved through utilising different polymers and with a focus on the conductivity and the viscosity of polymer solutions as critical parameters to generate successful fibres.Significance: Electrospinning is a promising trending manufacturing method for incorporating thermolabile herbal extracts using coaxial electrospun features. However, the complexity of the electrospinning process and the feasibility of the product required precise scrutiny.Methods: The electrospinning solution parameters (conductivity and viscosity) were evaluated by employing various ratios of Eudragit L100 (EL100) and Eudragit L100-55 (EL100-55) pre-spinning polymeric blend solutions. The electrospinning process and ambient parameters were optimised. Following that, the in-silico physicochemical properties of phytochemical marker, rutin, were illustrated using SwissADME web tool. Both freeze-dried Carica papaya leaf extract and its produced films were characterised using Scanning Electron Microscopy (SEM), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), polarised light microscopy, and X-ray Powder Diffraction (XRPD).Results: The optimal values of conductivity (≈40–44 × 10−4 S/m) and viscosity (≈32–42 × 10−3 Pa·s) were determined for producing evenly distributed and small fibre diameters in SEM images. These parameters significance was highlighted in acquiring and maintaining adequate tangential stress for fibre elongation, which would consequently affect the morphology and diameter of the fibres formed.Conclusion: In conclusion, the solution, process, and ambient parameters are significant in developing natural extracts into films via electrospinning technology, and this includes the promising Carica papaya leaf extract films produced by coaxial electrospinning.

Molecular characterization uncovering a novel genus of tapering-filamentous cyanobacteria from Thailand: Phayaothrix lacustris gen. & sp. nov. (Nostocales, Cyanophyta)

In this study, novel Calothrix-like strains NUACC09 and NUACC10 were isolated from the surfaces of rocks in Phayao Lake, Thailand. Morphological, molecular and ecological comparisons were investigated to characterize the taxonomic status of these novel strains. Under the light microscope, morphological studies indicated that these two strains were morphologically similar to Calothrix but could be differentiated by production of a non-hyaline hair at the terminal end, a low degree of tapering, twisted or loop-forming filaments, a knotted growth form, intertwined trichomes and presenting more than one trichome within the single sheath. In the 16S rRNA and rbcLX gene phylogenetic tree analyses, our strains formed a monophyletic clade with former freshwater/terrestrial Calothrix-like taxa separating distantly from other Calothrix-like genera. Furthermore, low 16S rRNA gene sequence similarity (<94.9%) to the closely related genera and species delimitation analyses (PTP/bPTP, GMYC, ABGD and ASAP methods) indicated that this clade should be considered as a different cyanobacterial lineage. The phylogenetic tree and secondary structures (D1–D1′, V2, Box-B and V3 helix) based on 16S–23S rRNA ITS regions suggested that multiple species might be contained in this clade. Therefore, here, Phayaothrix was proposed as a novel cyanobacterial genus with Phayaothrix lacustris sp. nov. as the type species following the International Code of Nomenclature for algae, fungi and plants.

Comparative study of the reptilian cornea's microstructure

BackgroundThe cornea of various vertebrate is considered a major part in the glop, which acts as a powerful lens, providing a sharp retinal image, and meantime acts as an excellent defensor for other corneal layers.ResultsThe four reptilian families [Scincidae (Chalcides ocellatus); Chamaeleontidae (Chameleon chameleon); Cheloniidae (Chelonia mydas) and Testudiniae (Testudo kleinmanni)] investigated in the current study were gathered across Egypt. After being taken out of the orbit, the cornea under inquiry was ready for light, specific stain and scanning electron microscopy. The epithelium, stroma, and endothelium are the three corneal layers that are common to all four species of reptiles. All other species lack Bowmen's and Descemet's membranes, with the exception of C. ocellatus and T. kleinmanni. The latter layers of Chalcides ocellatus display a strong affinity for Periodic Acid Schiff stain. Epithelial cells with a variety of forms, from hexagonal to atypical polygonal cells, cover the outer corneal surface. These epithelial cells are coated in short microplicae, microvilli, and microholes of varied diameters. There are a few blebs scattered around their surface.ConclusionThe current study concluded that various habitats have various significant effects on the cornea's microstructure characteristics and its physiological trends to accommodate different environmental surroundings.

Setting up a light microscopy core facility: Facility design.

The successful operation of a light microscopy core facility depends also on the initial setup of its infrastructure. This article covers the aspects of location selection and room planning and what environmental factors need to be considered. These include light, temperature, vibrations as well as the basic installations needed for microscope operation.

Carbomer Hydrogels with Microencapsulated α-Tocopherol: Focus on the Biocompatibility of the Microcapsules, Topical Application Attributes, and In Vitro Release Study

The microencapsulation of α-tocopherol based on the complex coacervation of low-molecular-weight chitosan (LMWC) and sodium lauryl ether sulphate (SLES) without harmful crosslinkers can provide biocompatible carriers that protect it from photodegradation and air oxidation. In this study, the influence of the microcapsule wall composition on carrier performance, compatibility with a high-water-content vehicle for topical application, and release of α-tocopherol were investigated. Although the absence of aldehyde crosslinkers decreased the encapsulation efficiency of α-tocopherol (~70%), the variation in the LMWC/SLES mass ratio (2:1 or 1:1) had no significant effect on the moisture content and microcapsule size. The prepared microcapsule-loaded carbomer hydrogels were soft semisolids with pseudoplastic flow behavior. The integrity of microcapsules embedded in the hydrogel was confirmed by light microscopy. The microcapsules reduced the pH, apparent viscosity, and hysteresis area of the hydrogels, while increasing their spreading ability on a flat inert surface and dispersion rate in artificial sweat. The in vitro release of α-tocopherol from crosslinker-free microcapsule-loaded hydrogels was diffusion-controlled. The release profile was influenced by the LMWC/SLES mass ratio, apparent viscosity, type of synthetic membrane, and acceptor medium composition. Better data quality for the model-independent analysis was achieved when a cellulose nitrate membrane and ethyl alcohol 60% w/w as acceptor medium were used.

Chronological Changes in the Histology of Infection-Related Glomerulonephritis in Renal Allograft: A Case Report

We report the histological changes over time for a patient with infection-related glomerulonephritis (IRGN) that developed in a transplanted kidney. A 47-year-old man had undergone renal transplantation 3 years ago for end-stage kidney disease (ESKD). After several episodes of acute rejection, the patient was in a stable CKD condition. The abrupt development of severe microscopic hematuria and renal dysfunction was observed approximately 2 weeks after the onset of a phlegmon in his right leg. An allograft biopsy showed prominent glomerular endocapillary proliferation on light microscopy, granular C3 deposition on immunofluorescent microscopy, and subepithelial electron-dense deposits on electron microscopy, suggesting IRGN accompanied by moderate interstitial fibrosis and tubular atrophy (IFTA). Positive glomerular staining for nephritis-associated plasmin receptor (NAPlr) and plasmin activity, which are biomarkers of bacterial IRGN, supported the diagnosis. Although the infection was completely cured with antibiotic therapy, renal dysfunction persisted. A re-biopsy of the allograft 2 months later revealed resolution of the glomerular endocapillary proliferation and negative staining for NAPlr/plasmin activity, with worsening IFTA. We showed, for the first time, the chronological changes in infiltrating cells and histological markers of IRGN in transplanted kidneys. Glomerular changes, including NAPlr/plasmin activity staining, almost disappeared after the cessation of infection, while interstitial changes continuously progressed, contributing to ESKD progression.

Pancreatic and hepatic histopathology of high-fat diet fed streptozotocin-induced Wistar rat model of type 2 diabetes mellitus

In search of new fangled therapeutic agents against type 2 diabetes mellitus (T2DM), an appropriate preclinical disease model is important to ensure the success of subsequent clinical trials. There is an increasing trend in the use of high-fat diet (HFD) fed streptozotocin (STZ)-induced rodent models in investigating novel therapeutic agents against T2DM. Though several studies have been conducted on the development of the aforementioned model they were mainly focused on biochemical characteristics. Only limited studies have focused on histopathological changes which is the gold standard in investigating the treatment-related changes of novel therapeutic agents. Therefore, the present study aimed at assessing the histopathological changes of the pancreas and liver, the two main organs involved in glucose homeostasis, in a newly developed HFD-fed STZ-induced Wistar rat model. For this study, Wistar rats were induced with T2DM by intraperitoneal injection of STZ (30, 40, and 50 mg/kg) which was given after feeding the rats with an HFD consisting of 60% calories from fat for four weeks duration. Diabetic rats were sacrificed after maintaining for further four weeks. The liver and pancreas were excised and hematoxylin and eosin-stained sections were observed using a light microscope. The major histopathological changes in the pancreas of HFD-fed STZ-induced diabetic rats were loss of pancreatic islets, pancreatic islet hypertrophy, and mild fatty change in the exocrine pancreas. In contrast, the liver did not show any degree of fatty change, but the majority showed prominent hydropic degeneration in the hepatocytes. In conclusion, prominent alterations were well noted in the pancreatic and liver tissues of the Wistar rats fed with HFD, followed by STZ (50 mg/kg), and the established model could be useful in investigating and elucidating antidiabetic mechanisms of novel pharmaceutical agents.

Microstructure, tensile strength, and hardness of AA5024 modified with ZrH4 additions produced by laser powder bed fusion

This work investigates the effect of ZrH4 additions on a commercial AA5024 aluminum alloy produced via Laser Powder Bed Fusion (L-PBF) where pre-mixed powders of AA5024 and ZrH4 were used. The microstructure was characterized using light and scanning electron microscopy assisted by energy-dispersive X-ray spectroscopy, and electron backscattered diffraction. The mechanical properties were evaluated by hardness and tensile measurements. The ZrH4 additions modify the microstructure. Regions without particles originate the large and elongated grains, while regions with undissolved ZrH4 or formed particles during solidification originate a fine equiaxed microstructure. The fine-grained region is typically located at the boundary of the melt pools, while the coarse-grained region is formed within the melt pools. There is substantial grain refinement with additions higher than 2.0 wt% ZrH4, nearly eliminating the coarse-grained region. The grain size does not differ in the fine-grained region for the different ZrH4, cross-sections (perpendicular or along the printing direction), or printing parameters. The 〈110〉 crystallographic fiber texture is identified, and a few particular texture components are more pronounced, such as the Cube {001} 〈100〉, the rotated Cube {001} 〈110〉, the Goss {011} 〈001〉, and Z {111} < 110>. Low texture index values are obtained in the fine-grained region, indicating the highly isotropic microstructure. The hardness and tensile strength increase with the increase in ZrH4 content for the as-built condition. A saturation in tensile strength is reached after 1.0 wt% ZrH4 additions.

Partial Alleviation of Homologous Superinfection Exclusion of SeMNPV Latently Infected Cells by G1 Phase Infection and G2/M Phase Arrest

Viral infection can regulate the cell cycle, thereby promoting viral replication. Hijacking and altering the cell cycle are important for the virus to establish and maintain a latent infection. Previously, Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV)-latently infected P8-Se301-C1 cells, which grew more slowly than Se301 cells and interfered with homologous SeMNNPV superinfection, were established. However, the effects of latent and superinfection with baculoviruses on cell cycle progression remain unknown. In this study, the cell cycle profiles of P8-Se301-C1 cells and SeMNPV or Autographa californica multiple nucleopolyhedrovirus (AcMNPV)-infected P8-Se301-C1 cells were characterized by flow cytometry. The results showed that replication-related genes MCM4, PCNA, and BAF were down-regulated (p &lt; 0.05) in P8-Se301-C1 cells, and the S phase of P8-Se301-C1 cells was longer than that of Se301 cells. P8-Se301-C1 cells infected with SeMNPV did not arrest in the G2/M phase or affect the expression of Cyclin B and cyclin-dependent kinase 1 (CDK1). Furthermore, when P8-Se301-C1 cells were infected with SeMNPV after synchronized treatment with hydroxyurea and nocodazole, light microscopy and qRT-PCR analysis showed that, compared with unsynchronized cells and S and G2/M phase cells, SeMNPV-infected P8-Se301-C1 cells in G1 phase induced G2/M phase arrest, and the amount of virus adsorption and intracellular viral DNA replication were significantly increased (p &lt; 0.05). In addition, budded virus (BV) production and occlusion body (OB)-containing cells were both increased at 120 h post-infection (p &lt; 0.05). The expression of Cyclin B and CDK1 was significantly down-regulated at 48 h post-infection (p &lt; 0.05). Finally, the arrest of SeMNPV-infected G1 phase cells in the G2/M phase increased BV production (p &lt; 0.05) and the number of OB-containing cells. In conclusion, G1 phase infection and G2/M arrest are favorable to SeMNPV proliferation in P8-Se301-C1 cells, thereby alleviating the homologous superinfection exclusion. The results contribute to a better understanding of the relationship between baculoviruses and insect cell cycle progression and regulation.

Spore morphology of Schizaea species (Schizaeaceae) from America

The Schizaeaceae family consists of only two genera, Actinostachys Wall and Schizaea Sm. These genera are mainly found in the tropical regions of the Old and New World with a few of them growing in temperate areas. The spores of the following Schizaea species from America were studied: Schizaea elegans (Vahl) Sw., S. fistulosa Labill., S. fluminensis Miers ex J.W. Sturm, S. incurvata Schkuhr, S. poeppigiana J.W. Sturm, S. pusilla Pursh, S. sprucei Hook. and S. stricta Lellinger. The study was performed with light microscope (LM) and scanning electron microscope (SEM). The spores are monolete of 33.6–99.4 μm in equatorial diameter and 21–65.8 μm in polar diameter. The ornamentation of the spores is verrucate, verrucate-tuberculate, rugate or reticulate. The most abundant morphology is the verrucate ornamentation. The exospore and the perispore form the ornamentation of the spores. In most of the species analyzed abundant spheroids, variable in size were observed irregularly distributed on the spore surface, even on the laesura. This study describes and illustrates the spores of some species for the first time. The results are discussed with a recent phylogeny of the genus.