Ten Approaches That Improve Immunostaining: A Review of the Latest Advances for the Optimization of Immunofluorescence

Immunocytochemical detection of proteins within cellular structures inaccessible to specific antibodies

Immunocytochemistry and immunohistochemistry are among the most widely used and valuable methods for localizing and quantifying proteins in cells and tissues. However, these methods have several limitations, and they are still being improved. A notable problem in this area is the restricted accessibility of some dense intracellular structures, such as nucleoli, to specific antibodies. This reduced accessibility led to peripheral staining of the nucleoli even in cases of relatively homogeneous distribution of the antigen within the nucleoli. This review aims to elucidate the factors impeding antibody accessibility to the internal regions of the nucleolus in somatic cells and nucleolus-like bodies in oocytes and to explore the methods used to circumvent this limitation.

Association of eosinophil major basic protein with intraocular lens dislocation in atopic dermatitis

The study aimed to investigate whether eosinophil major basic protein (MBP), which is linked to cataract formation due to lens epithelial cell (LEC) damage in atopic dermatitis (AD), is associated with intraocular lens (IOL) dislocation. This retrospective observational study was conducted at a Medical University Hospital and included 22 eyes (10 AD, 12 non-AD [NAD]) that underwent IOL explantation and fixation. Surgeries were conducted to extract the intraocular lens capsule for morphological evaluations. Quantitative analysis of the MBP staining was conducted using the staining area ratio (SAR) gap. MBP staining was negative in all cases for both the lens capsule and LEC. The SAR gap in Soemmering's ring was significantly higher in the AD group (14.3 ± 8.7%) than in the NAD group (1.1 ± 1.1%) (p = 0.0037). In contrast, the SAR gap for fibrous metaplasia showed no significant difference between the AD (8.3 ± 13.2%) and NAD (6.5 ± 12.3%) groups (p = 0.75). Six cases of fibrous metaplasia, including those in the NAD group, showed SAR gaps equal to or greater than those in the positive control group, with five classified as low-density fibrosis (LDF). While Soemmering's rings in AD cases demonstrated greater MBP immunoreactivity than NAD controls, both groups exhibited MBP-positive fibrous metaplasia specimens.

Enhancing throughput and robustness of the fibroblast to myofibroblast transition assay

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive age-related lung disease with an average survival of 3-5 years post-diagnosis if left untreated. It is characterized by lung fibrosis, inflammation, and destruction of lung architecture, leading to worsening respiratory symptoms and physiological impairment, ultimately culminating in progressive respiratory failure. The development of novel therapeutics for the treatment of IPF represents a significant unmet medical need. Fibroblast to myofibroblast transition (FMT) in response to fibrogenic mediators such as transforming growth factor beta 1 (TGF-β1) has been identified as a key cellular phenotype driving the formation of myofibroblasts and lung fibrosis in IPF. Establishing a robust and high-throughput in vitro human FMT assay is crucial for uncovering new disease targets and for efficiently screening compounds for the advancement of novel therapeutics aimed at targeting myofibroblast activity. However, creating a robust FMT assay suitable for high-throughput drug screening has proven challenging due to the requisite level of automation. In this study, we focus on evaluating different automation approaches for liquid exchange and compound dosing in the human FMT assay. A semi-automated assay, capable of screening a large number of compounds that inhibit TGF-β1-induced FMT in both Normal Human Lung Fibroblasts (NHLF) and IPF-patient derived Disease Human Lung Fibroblasts (IPF-DHLF), has been successfully developed and optimized. We demonstrate that the optimized FMT assay using liquid handling automation exhibits great assay reproducibility, shows good assay translation using human lung fibroblasts from normal healthy versus IPF-patients, and demonstrates acceptable human primary donor variability. This allows for the standardization of comparisons of compound anti-fibrotic potency across IPF projects.

3D Histology visualizing hypoxia-induced upregulation of N-terminal cysteine using de novo fluorophore generation

Our research group developed a novel fluorescence staining strategy based on the DNFC targeting N-Cys in proteins. By treating biological samples with non-fluorogenic citrate and coupling reagents, we achieved strong cyan fluorescence, enabling effective visualization of N-Cys proteins in cells and tissues. The DNFC reaction occurs specifically on N-Cys residues, making it highly ideal for monitoring protein processing events, particularly within the Arg/N-degron pathway. Under hypoxic conditions, DNFC fluorescence is significantly enhanced, likely due to the increased presence of N-Cys-containing proteins. Using immunoassays and mass spectrometry, we identified Class 2 actin as a target protein under hypoxia, emphasizing the utility of 3D histopathology for analyzing actin's spatial distribution. Furthermore, we have identified a novel finding indicating a significant presence of RGS5 in red blood cells (RBCs), a discovery that has not been previously reported. Our fluorescence imaging studies, conducted across various cell types, animal tissues, and human clinical samples suggest that DNFC staining, when combined with tissue-clearing techniques, enables detailed 3D imaging of N-Cys proteins and may offer a means to assess molecular responses to hypoxia within tissues. This study highlights the potential of DNFC as a valuable tool for imaging and quantitative analysis of N-proteomes and providing a foundation for 3D histopathology in hypoxia-related disease research.

Anatomy, histology and ultrastructure of the adult human olfactory peduncle: Blood vessel and corpora amylacea assessment

The mammalian olfactory system is responsible for processing environmental chemical stimuli and comprises several structures, including the olfactory epithelium, olfactory bulb, olfactory peduncle (OP), and olfactory cortices. Despite the critical role played by the OP in the conduction of olfactory information, it has remained understudied. In this work, optical, confocal, and electron microscopy were employed to examine the anatomy, histology, and ultrastructure of six human OP specimens (ages 37-84 years). Three concentric layers were identified in coronal sections: the external layer (EL), the axonal layer (AL), and the internal layer (IL). Immunohistochemistry revealed the distribution of neurons and glial cells throughout the OP. Two neuronal morphologies were observed: granule cells and larger pyramidal cells, the latter associated with projection neurons of the anterior olfactory nucleus. Astrocytes were uniformly distributed with a more radial morphology in the EL. Oligodendrocytes were mainly located in the AL. Blood vessels (BVs) were evenly distributed along the OP, with a mean luminal area of 82.9 µm² and a density of 1.26 %, with a significant increase in the IL. Corpora amylacea (CA) were abundant, with an average size of 49.3 µm² and a density of 3.23 %. CA clustered near BVs, particularly at tissue edges, with both size and density increasing with age. Notably, CA showed strong associations with astrocytes. This study provides the first detailed qualitative and quantitative data on the internal organization of the human OP, which may contribute to a better understanding of the pathophysiology of some neuropathological disorders.

Naringenin attenuates early hepatocarcinogenesis induced by a MASH model

INTRODUCTION AND OBJECTIVES

Nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome plays a critical role in the progression of metabolic dysfunction-associated steatohepatitis (MASH). Here, we investigated the effects of naringenin (NAR) on early hepatocellular carcinoma (HCC) experimentally induced in a rat MASH model and whether the NLRP3 inflammasome/pyroptosis pathway was involved.

MATERIALS AND METHODS

The animals were fed a hepatopathogenic diet for 16 weeks and carbon tetrachloride (400 mg/kg, i.p.) and diethylnitrosamine (40 mg/kg, i.p.) were injected once a week. NAR was administered at 100 mg/kg p.o. The effects of NAR on the MASHHCC protocol were evaluated using biochemical, histological, in silico, and molecular biological approaches.

RESULTS

NAR significantly mitigated liver damage, as evidenced by the reduction in liver damage markers. It also reduced steatosis and inflammation, as determined by decreased lipid accumulation and sterol regulatory element-binding protein 1C, interleukins 1-beta and 18, and nuclear factor kappa B levels, and also increased peroxisome proliferator-activated receptor gamma levels. NAR inhibits the formation of NLRP3, including the recruitment of caspase-1 and gasdermin D proteins, and reduces the levels of transforming growth factor-beta, alpha-smooth muscle actin, and hepatic collagen 1, thereby diminishing extracellular matrix synthesis. Furthermore, gamma-glutamyl transpeptidase activity, glutathione S-transferase pi 1, and the proliferation marker KI67 were considerably reduced.

CONCLUSIONS

Our findings show that NAR has the potential to inhibit early HCC induced in the context of MASH, thereby suggesting that NAR could be used for MASH treatment in humans.

Revolutionizing Biomedical Research: Unveiling the Power of Microphysiological Systems with Advanced Assays, Integrated Sensor Technologies, and Real-Time Monitoring

The limitation of animal models to imitate a therapeutic response in humans is a key problem that challenges their use in fundamental research. Organ-on-a-chip (OOC) devices, also called microphysiological systems (MPS), are devices containing a lining of living cells grown under dynamic flow to recapitulate the important features of human physiology and pathophysiology with high precision. Recent advances in microfabrication and tissue engineering techniques have led to the wide adoption of OOC in next-generation experimental platforms. This review presents a comprehensive analysis of the OOC systems, categorizing them by flow types (single-pass and multipass), operational mechanisms (pumpless and pump-driven), and configurations (single-organ and multiorgan systems), along with their respective advantages and limitations. Furthermore, it explores the integration of qualitative and quantitative assay techniques, providing a comparative evaluation of systems with and without sensor integration. This review aims to fill essential knowledge gaps, driving the progress of the development of OOC systems and paving the way for breakthroughs in biomedical research, pharmaceutical innovation, and tissue engineering.

Principles and Design of Molecular Tools for Sensing and Perturbing Cell Surface Receptor Activity

Cell-surface receptors are vital for controlling numerous cellular processes with their dysregulation being linked to disease states. Therefore, it is necessary to develop tools to study receptors and the signaling pathways they control. This Review broadly describes molecular approaches that enable 1) the visualization of receptors to determine their localization and distribution; 2) sensing receptor activation with permanent readouts as well as readouts in real time; and 3) perturbing receptor activity and mimicking receptor-controlled processes to learn more about these processes. Together, these tools have provided valuable insight into fundamental receptor biology and helped to characterize therapeutics that target receptors.

Development of Immunostaining Protocols for 3D Visualization of Pericytes in Human Retinal Flatmounts

Vascular pericytes are widely present across the human body and crucial in regulating vascular flow, permeability, and homeostasis. In the human retina, pericytes are important for forming and maintaining the blood-retinal barrier, as well as for autoregulation of blood flow. Pericyte loss has been implicated in various pathological conditions. Visualization of pericytes by immunofluorescence (IF) staining provides valuable information on pericyte number, morphology, location, and on expression of anatomic and functional markers. However, species-specific differences in pericyte marker expression exist. In this study, we aimed to develop a novel IF co-staining protocol to detect the pericyte markers NG2, PDGFRβ, αSMA, CD13, and RFC1 in human retinal flatmounts. Unlike retinal sections, retinal flatmounts enable 3D visualization of pericyte distribution across the entire vascular network. Key optimizations included tailoring the fixation method, blocking buffer composition and antibody solvent, as well as using jasplakinolide to enhance αSMA detection. Our protocol successfully enabled double staining of NG2 and PDGFRβ, as well as αSMA and PDGFRβ, whereas CD13 and RFC1 expression was not detectable in human retinal flatmounts. This novel 3D IF protocol enhances in situ visualization of human retinal pericytes, enabling accurate studies of their role in vascular health and disease to aid targeted therapy development.

A Review on Perception of Binding Kinetics in Affinity Biosensors: Challenges and Opportunities

There are challenges associated with design and development of affinity biosensors due to the complicated multiphysics nature of the system. Understanding the binding interaction between target molecules and immobilized receptors and its kinetics is a crucial step to develop robust and reliable biosensor technologies. Evaluation of binding kinetics in biosensors becomes more important and challenging for clinical samples with a complex matrix. Despite drastic advancements in biosensor technologies, having a practical perception of the binding kinetics has remained a critical bottleneck due to limited fundamental understanding. This Review aims to provide a comprehensive discussion on concepts and advances developed so far for the perception of binding kinetics in affinity biosensors. Here, modeling approaches and measurement techniques are presented to characterize the binding interactions in biosensor technologies, while the effect of fouling and secondary factors in the binding interactions will be discussed in the concept of kinetics. This Review will investigate the existing research gaps and potential opportunities in the perception of binding kinetics and challenges to develop robust and reliable biosensors.

Unveiling the native architecture of adult cardiac tissue using the 3D-NaissI method

Accurately imaging adult cardiac tissue in its native state is essential for regenerative medicine and understanding heart disease. Current fluorescence methods encounter challenges with tissue fixation. Here, we introduce the 3D-NaissI (3D-Native Tissue Imaging) method, which enables rapid, cost-effective imaging of fresh cardiac tissue samples in their closest native state, and has been extended to other tissues. We validated the efficacy of 3D-NaissI in preserving cardiac tissue integrity using small biopsies under hypothermic conditions in phosphate-buffered saline, offering unparalleled resolution in confocal microscopy for imaging fluorescent small molecules and antibodies. Compared to conventional histology, 3D-NaissI preserves cardiac tissue architecture and native protein epitopes, facilitating the use of a wide range of commercial antibodies without unmasking strategies. We successfully identified specific cardiac protein expression patterns in cardiomyocytes (CMs) from rodents and humans, including for the first time ACE2 localization in the lateral membrane/T-Tubules and SGTL2 in the sarcoplasmic reticulum. These findings shed light on COVID-19-related cardiac complications and suggest novel explanations for therapeutic benefits of iSGLT2 in HFpEF patients. Additionally, we challenge the notion of "connexin-43 lateralization" in heart pathology, suggesting it may be an artifact of cardiac fixation, as 3D-NaissI clearly revealed native connexin-43 expression at the lateral membrane of healthy CMs. We also discovered previously undocumented periodic ring-like 3D structures formed by pericytes that cover the lateral surfaces of CMs. These structures, positive for laminin-2, delineate a specific spatial architecture of laminin-2 receptors on the CM surface, underscoring the pivotal role of pericytes in CM function. Lastly, 3D-NaissI facilitates the mapping of native human protein expression in fresh cardiac autopsies, offering insights into both pathological and non-pathological contexts. Therefore, 3D-NaissI provides unparalleled insights into native cardiac tissue biology and holds the promise of advancing our understanding of physiology and pathophysiology, surpassing standard histology in both resolution and accuracy.

Brief guide to immunostaining

Immunostaining is an essential biological technique that determines the localization and level of target antigen molecules using antibodies within cells or tissues. Here, we present a brief guide to immunostaining, including the principles, methods, and different types of immunostaining. This manuscript will also provide common challenges and optimization strategies. This work will be useful for researchers with basic knowledge in immunostaining.

Characterizing Nanoparticle Isolated by Yam Bean (Pachyrhizus erosus) as a Potential Agent for Nanocosmetics: An in vitro and in vivo Approaches

BACKGROUND

This study investigated the potential of Plant-Derived Exosome-Like Nanoparticles (PDENs) as cosmeceutical nanocarriers for treating skin problems, such as scar removal, face rejuvenation, anti-aging, and anti-pigmentation.

OBJECTIVES

Researchers isolated PDENs from Yam Bean ((Pachyrhizus erosus) using PEG-based precipitation, gradual filtration, and various centrifugations at low temperatures. Followed by in vitro and in vivo studies using HDF cells and Zebrafish.

METHODS

The morphology of the YB-PDENs was determined using TEM analysis, they had a spherical shape with diameters of 236,83 ± 9,27 nm according to PSA. The study found that YB-PDENs were stable in aquabidest at 4°C for one month of storage and had ~-26,5 mV of Zeta Potential. The concentration of YB-PDENs was measured using the BCA Assay, and internalization of YB-PDENs to HDF cells was observed using a Confocal Laser Scanning Microscope labelled with PKH67.

RESULTS

As for cytotoxicity, after 24 and 72 hours of incubation with YB-PDENs, the viability of HDF cells remained more than 80%. The study also examined cell migration using the Scratch Assay and found that at 2,5 μg/mL, YB-PDENs had better migration results than other concentrations. Immunocytochemistry showed that collagen expression was higher after 14 days of incubation with YBPDENs, and melanocytes in zebrafish decreased at each concentration compared with controls.

CONCLUSION

In conclusion, this study is the first to extract and describe PDEN s from Yam Bean ((Pachyrhizus erosus), with YB-PDENs having a promising anti-melanogenic effect in skin treatment. This study highlights the potential of YB-PDENs as a promising alternative to depigmentation and skin whitening treatments.

Protocol for whole-mount preparation, clearing, and visualization of the adult zebrafish spinal cord structures

The vascular repair, a pivotal element of the spinal cord (SC) injury response, has been notably neglected in zebrafish research. Here, we detail the extraction and dissection of whole-mount zebrafish SCs and the optimized whole-mount immunofluorescence staining and clearing protocols for the visualization of SC structures, such as the vascular network. Additional downstream applications of these samples, from gelatin embedding to cryosectioning and tissue staining, can be done after clearing reversion and are also described in this work. For complete details on the use and execution of this protocol, please refer to Ribeiro et al.1.

A systematic review on global zoonotic virus-associated mortality events in marine mammals

Marine mammals play a critical role as sentinels for tracking the spread of zoonotic diseases, with viruses being the primary causative factor behind infectious disease induced mortality events. A systematic review was conducted to document marine mammal mortality events attributed to zoonotic viral infections in published literature across the globe. This rigorous search strategy yielded 2883 studies with 88 meeting inclusion criteria. The studies spanned from 1989 to 2023, with a peak in publications observed in 2020. Most of the included studies were retrospective, providing valuable insights into historical trends. The United States (U.S.) reported the highest number of mortality events followed by Spain, Italy, Brazil and the United Kingdom. Harbor seals were the most impacted species, particularly in regions like Anholt, Denmark and the New England Coast, U.S. Analysis revealed six main viruses responsible for mortality events, with Morbillivirus causing the highest proportion of deaths. Notably, the occurrence of these viral events varied geographically, with distinct patterns observed in different regions. Immunohistochemistry emerged as the most employed detection method. This study underscores the importance of global surveillance efforts in understanding and mitigating the impact of viral infections on marine mammal populations, thereby emphasizing the necessity of collaborative One Health approaches to address emerging threats at the human-animal-environment interface. Additionally, the potential transfer of zoonotic viruses to aquatic organisms used in food production, such as fish and shellfish, highlights the broader implications for food safety, food security and public health.

High-fat and high-carbohydrate diets worsen the mouse brain susceptibility to damage produced by enterohemorrhagic Escherichia coli Shiga toxin 2

Background

Nutrition quality could be one of the reasons why, in the face of a Shiga toxin-producing enterohemorrhagic Escherichia coli outbreak, some patients experience more profound deleterious effects than others, including unfortunate deaths. Thus, the aim of this study was to determine whether high-fat and/or high-carbohydrate diets could negatively modulate the deleterious action of Shiga toxin 2 on ventral anterior and ventral lateral thalamic nuclei and the internal capsule, the neurological centers responsible for motor activity.

Methods

Mice were fed a regular, high-fat, high-carbohydrate diet or a combination of both previous to the intravenous administration of Shiga toxin 2 or vehicle. Four days after intravenous administration, mice were subjected to behavioral tests and then sacrificed for histological and immunofluorescence assays to determine alterations in the neurovascular unit at the cellular and functional levels. Statistical analysis was performed using one-way analysis of variance followed by Bonferroni post hoc test. The criterion for significance was p = 0.0001 for all experiments.

Results

The high-fat and the high-carbohydrate diets significantly heightened the deleterious effect of Stx2, while the combination of both diets yielded the worst results, including endothelial glycocalyx and oligodendrocyte alterations, astrocyte and microglial reactivity, neurodegeneration, and motor and sensitivity impairment.

Conclusions

In view of the results presented here, poor nutrition could negatively influence patients affected by Stx2 at a neurological level. Systemic effects, however, cannot be ruled out.

Determination of DNA content as quality control in decellularized tissues: challenges and pitfalls

Decellularized organs and tissues are emerging within the field of regenerative medicine to meet the growing demand for organ and tissue transplantation. Quality control of these acellular matrices prior to transplantation is of paramount importance to ensure the absence of an adverse reaction. In particular, thorough evaluation of the DNA content is essential but also poses technical challenges. Therefore, in this study, we compared different methods for quantitative and qualitative evaluation of DNA content in native and decellularized skeletal muscle tissue to identify strengths and weaknesses for each. Histological analysis revealed that Feulgen staining is more sensitive and robust than the commonly used hematoxylin-eosin and 4',6-diamidino-2-phenylindole staining for detection of remaining nuclear material. Furthermore, gel electrophoresis allowed to identify the quality and length of remaining DNA fragments. The results of the quantitative analysis indicated that direct measurement of DNA content in tissue lysates is preferred over silica-based extraction methods, since the latter resulted in the loss of small DNA fragments during extraction. Moreover, a weight loss correction factor should be implemented to take into account the impact of the decellularization on the extracellular matrix. With regard to the detection method, the results revealed that a fluorescence-based approach is more accurate than the use of UV/VIS absorbance. Through combination of the proposed methods, it should be possible to achieve a more standardized evaluation of novel acellular matrices in terms of DNA content and to enhance the predictability of clinical success.

The functional role of locus coeruleus microglia in the female stress response

Neuropsychiatric disorders that result from stress exposure are highly associated with central inflammation. Our previous work established that females selectively exhibit heightened proinflammatory cytokine production within the noradrenergic locus coeruleus (LC) along with a hypervigilant behavioral phenotype in response to witnessing social stress, and ablation of microglia using pharmacological techniques prevents this behavioral response. These studies were designed to further investigate the impact of stress-induced neuroimmune signaling on the long-term behavioral and neuronal consequences of social stress exposure in females using chemogenetics. We first characterized the use of an AAV-CD68-Gi-DREADD virus targeted to microglia within the LC and confirmed viral transduction, selectivity, and efficacy. Clozapine-n-oxide (CNO) was used for the suppression of microglial reactivity during acute and chronic exposure to vicarious/witness social defeat in female rats. Chemogenetic-mediated inhibition of microglial reactivity during stress blunted the neuroimmune response to stress and prevented both acute and long-term hypervigilant behavioral responses. Further, a history of microglial suppression during stress prevented the heightened LC activity typically observed in response to stress cues. These studies are among the first to use a chemogenetic approach to inhibit microglia within the female brain in vivo and establish LC inflammation as a key mechanism underlying the behavioral and neuronal responses to social stress in females.

Improved DiOlistic labelling technique for neurons in situ: Detailed visualisation of dendritic spines and concurrent histochemical-detection in fixed tissue

DiOlistic labelling is a robust, unbiased ballistic method that utilises lipophilic dyes to morphologically label neurons. While its efficacy on freshly dissected tissue specimens is well-documented, applying DiOlistic labelling to stored, fixed brain tissue and its use in polychromatic multi-marker studies poses significant technical challenges. Here, we present an improved, step-by-step protocol for DiOlistic labelling of dendrites and dendritic spines in fixed mouse tissue. Our protocol encompasses the five key stages: Tissue Preparation, Dye Bullet Preparation, DiOlistic Labelling, Confocal Imaging, and Image Analysis. This method ensures reliable and consistent labelling of dendritic spines in fixed mouse tissue, combined with increased throughput of samples and multi-parameter staining and visualisation of tissue, thereby offering a valuable approach for neuroscientific research.

Detection of TurboID fusion proteins by fluorescent streptavidin outcompetes antibody signals and visualises targets not accessible to antibodies

Immunofluorescence localises proteins via fluorophore-labelled antibodies. However, some proteins evade detection due to antibody-accessibility issues or because they are naturally low abundant or antigen density is reduced by the imaging method. Here, we show that the fusion of the target protein to the biotin ligase TurboID and subsequent detection of biotinylation by fluorescent streptavidin offers an 'all in one' solution to these restrictions. For all proteins tested, the streptavidin signal was significantly stronger than an antibody signal, markedly improving the sensitivity of expansion microscopy and correlative light and electron microscopy. Importantly, proteins within phase-separated regions, such as the central channel of the nuclear pores, the nucleolus, or RNA granules, were readily detected with streptavidin, while most antibodies failed. When TurboID is used in tandem with an HA epitope tag, co-probing with streptavidin and anti-HA can map antibody-accessibility and we created such a map for the trypanosome nuclear pore. Lastly, we show that streptavidin imaging resolves dynamic, temporally, and spatially distinct sub-complexes and, in specific cases, reveals a history of dynamic protein interaction. In conclusion, streptavidin imaging has major advantages for the detection of lowly abundant or inaccessible proteins and in addition, provides information on protein interactions and biophysical environment.

Making Multiplexed Imaging Flexible: Combining Essential Markers With Established Antibody Panels

Multiplexed immunofluorescence (IF) can be achieved using different commercially available platforms, often making use of conjugated antibodies detected in iterative cycles. A growing portfolio of pre-conjugated antibodies is offered by the providers, as well as the possibility for in-house conjugation. For many conjugation methods and kits, there are limitations in which antibodies can be used, and conjugation results are sometimes irreproducible. The conjugation process can limit or slow down the progress of studies requiring conjugation of essential markers needed for a given project. Here, we demonstrate a protocol combining manual indirect immunofluorescence (IF) of primary antibodies, followed by antibody elution and staining with multiplexed panels of commercially pre-conjugated antibodies on the PhenoCycler platform. We present detailed protocols for applying the workflow on fresh frozen and formalin fixed paraffin embedded tissue sections. We also provide a ready to use workflow for coregistration of the images and demonstrate this for two examples.

Illuminating the Cryptococcus neoformans species complex: unveiling intracellular structures with fluorescent-protein-based markers

Cryptococcus neoformans is a fungal pathogen of the top critical priority recognized by the World Health Organization. This clinically important fungus also serves as a eukaryotic model organism. A variety of resources have been generated to facilitate investigation of the C. neoformans species complex, including congenic pairs, well-annotated genomes, genetic editing tools, and gene deletion sets. Here, we generated a set of strains with all major organelles fluorescently marked. We tested short organelle-specific targeting sequences and successfully labeled the following organelles by fusing the targeting sequences with a fluorescence protein: the plasma membrane, the nucleus, the peroxisome, and the mitochondrion. We used native cryptococcal Golgi and late endosomal proteins fused with a fluorescent protein to label these two organelles. These fluorescence markers were verified via colocalization using organelle-specific dyes. All the constructs for the fluorescent protein tags were integrated in an intergenic safe haven region. These organelle-marked strains were examined for growth and various phenotypes. We demonstrated that these tagged strains could be employed to track cryptococcal interaction with the host in phagocytosis assays. These strains also allowed us to discover remarkable differences in the dynamics of proteins targeted to different organelles during sexual reproduction. Additionally, we revealed that "dormant" spores transcribed and synthesized their own proteins and trafficked the proteins to the appropriate subcellular compartments, demonstrating that spores are metabolically active. We anticipate that these newly generated fluorescent markers will greatly facilitate further investigation of cryptococcal biology and pathogenesis.

Advanced Immunolabeling Method for Optical Volumetric Imaging Reveals Dystrophic Neurites of Dopaminergic Neurons in Alzheimer's Disease Mouse Brain

Optical brain clearing combined with immunolabeling is valuable for analyzing molecular tissue structures, including complex synaptic connectivity. However, the presence of aberrant lipid deposition due to aging and brain disorders poses a challenge for achieving antibody penetration throughout the entire brain volume. Herein, we present an efficient brain-wide immunolabeling method, the immuno-active clearing technique (iACT). The treatment of brain tissues with a zwitterionic detergent, specifically SB3-12, significantly enhanced tissue permeability by effectively mitigating lipid barriers. Notably, Quadrol treatment further refines the methodology by effectively eliminating residual detergents from cleared brain tissues, subsequently amplifying volumetric fluorescence signals. Employing iACT, we uncover disrupted axonal projections within the mesolimbic dopaminergic (DA) circuits in 5xFAD mice. Subsequent characterization of DA neural circuits in 5xFAD mice revealed proximal axonal swelling and misrouting of distal axonal compartments in proximity to amyloid-beta plaques. Importantly, these structural anomalies in DA axons correlate with a marked reduction in DA release within the nucleus accumbens. Collectively, our findings highlight the efficacy of optical volumetric imaging with iACT in resolving intricate structural alterations in deep brain neural circuits. Furthermore, we unveil the compromised integrity of DA pathways, contributing to the underlying neuropathology of Alzheimer's disease. The iACT technique thus holds significant promise as a valuable asset for advancing our understanding of complex neurodegenerative disorders and may pave the way for targeted therapeutic interventions.

Blood-Catalyzed Polymerization Creates Conductive Polymer in Live Zebrafish

Conducting polymers are of great interest in bioimaging, bio-interfaces, and bioelectronics for their biocompatibility and the unique combination of optical, electrical, and mechanical properties. They are typically prepared outside through traditional organic synthesis and delivered into the biological systems. The ability to call for the polymerization ingredients available inside the living systems to generate conducting polymers in vivo will offer new venues in future biomedical applications. This study is the first report of in vivo synthesis of an n-doped conducting polymer (n-PBDF) within live zebrafish embryos, achieved through whole blood catalyzed polymerization of 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (BDF). Prior to this, the efficacy of such a polymerization was rigorously established through a sequence of in vitro experiments involving Hemin, Hemoproteins (Hemoglobin, Myoglobin, and Cytochrome C), red blood cells, and the whole blood. Ultimately, in cellulo formed n-PBDF within cultured primary neurons demonstrated enhanced bio-interfaces and led to more effective light-induced neural activation than the prefabricated polymer. This underscores the potential advantages of synthesizing conducting polymers directly in living systems for biomedical applications.

Protocol for whole-mount immunofluorescence staining of ECM gel-embedded innervated pancreatic organoids

The mandatory usage of extracellular matrix (ECM) gels in 3D cultures limits antibody penetration and increases background, while the removal of ECM gel causes disruption of morphology and sample loss. These factors pose challenges to effective immune labeling-based staining. Here, we present a protocol for whole-mount immunofluorescence staining of gel-embedded pancreatic organoids. We describe steps for sample fixation, blocking, and antibody incubation. We detail procedures for washing antibodies and mounting.

Medicinal plant extracts interfere in gastric cancer stem cells fluorescence-based assays

Fluorescence is used in various biological assays due to its high sensitivity, versatility, and precision. In recent years, studies using medicinal plant extracts have increased. However, fluorescence-based assays could be biased by plant metabolites autofluorescence. To address this issue, this study investigated the interference caused by methanolic extracts and chloroform fractions of three medicinal plants in three fluorescence-based assays on gastric cancer stem cells(CSC): resazurin reduction, confocal microscopy, and flow cytometry. CSC were isolated based on CD44 surface marker, incubated with methanolic extracts and chloroform fractions of Buddleja incana, Dracontium spruceanum, Piper aduncum. Resazurin assay evidenced that CSC exposed to extracts and fractions from the three plants showed significant differences in relative fluorescence units (RFU) levels (p < 0.001) compared to the unexposed groups after a 3-hour incubation. In addition, DMSO-treated CSC exposed to extracts and fractions had significantly lower fluorescence levels than living ones, but higher than extracts and fractions without cells. In confocal microscopy, cancer stem cells exposed to extracts and fractions of B. incana and P. aduncum were observed in the same emission spectra of the CSC markers. In flow cytometry, CSC exposed to extracts and fractions without any fluorescent dyes were detected in the double positive quadrants for CSC markers (CD44+/CD133 + ). Among the three plants, D. spruceanum exhibited the least interference. These results show that methanolic extracts and chloroform fractions contain autofluorescent metabolites that interfere with fluorescence-based assays. These results highlight the importance of a prior evaluation for possible fluorescence interference to avoid interpretation biases in fluorescence assays.

Immunological and molecular diagnostic techniques in fish health: present and future prospectus

Fish health management is critical to aquaculture and fisheries as it directly affects sustainability and productivity. Fish disease diagnosis has taken a massive stride because of advances in immunological and molecular diagnostic tools which provide a sensitive, quick, and accurate means of identifying diseases. This review presents an overview of the main molecular and immunological diagnostic methods for determining the health of fish. The immunological techniques help to diagnose different fish diseases by detecting specific antigens and antibodies. The application of immunological techniques to vaccine development is also examined in this review. The genetic identification of pathogens is made possible by molecular diagnostic techniques that enable the precise identification of bacterial, viral, and parasitic organisms in addition to evaluating host reactions and genetic variation associated with resistance to disease. The combination of molecular and immunological methods has resulted in the creation of novel techniques for thorough evaluation of fish health. These developments improve treatment measures, pathogen identification and provide new information about the variables affecting fish health, such as genetic predispositions and environmental stresses. In the framework of sustainable fish farming and fisheries management, this paper focuses on the importance of these diagnostic techniques that play a crucial role in protecting fish populations and the aquatic habitats. This review also examines the present and potential future directions in immunological and molecular diagnostic techniques in fish health.

De novo reconstruction of a functional in vivo-like equine endometrium using collagen-based tissue engineering

To better understand molecular aspects of equine endometrial function, there is a need for advanced in vitro culture systems that more closely imitate the intricate 3-dimensional (3D) in vivo endometrial structure than current techniques. However, development of a 3D in vitro model of this complex tissue is challenging. This study aimed to develop an in vitro 3D endometrial tissue (3D-ET) with an epithelial cell phenotype optimized by treatment with a Rho-associated protein kinase (ROCK) inhibitor. Equine endometrial epithelial (eECs) and mesenchymal stromal (eMSCs) cells were isolated separately, and eECs cultured in various concentrations of Rock inhibitor (0, 5, 10 µmol) in epithelial medium (EC-medium) containing 10% knock-out serum replacement (KSR). The optimal concentration of Rock inhibitor for enhancing eEC proliferation and viability was 10 µM. However, 10 µM Rock inhibitor in the 10% KSR EC-medium was able to maintain mucin1 (Muc1) gene expression for only a short period. In contrast, fetal bovine serum (FBS) was able to maintain Muc1 gene expression for longer culture durations. An in vitro 3D-ET was successfully constructed using a collagen-based scaffold to support the eECs and eMSCs. The 3D-ET closely mimicked in vivo endometrium by displaying gland-like eEC-derived structures positive for the endometrial gland marker, Fork headbox A2 (FOXA2), and by mimicking the 3D morphology of the stromal compartment. In addition, the 3D-ET expressed the secretory protein MUC1 on its glandular epithelial surface and responded to LPS challenge by upregulating the expression of the interleukin-6 (IL6) and prostaglandin F synthase (PGFS) genes (P < 0.01), along with an increase in their secretory products, IL-6 (P < 0.01) and prostaglandin F2alpha (PGF2α) (P < 0.001) respectively. In the future, this culture system can be used to study both normal physiology and pathological processes of the equine endometrium.

Diagnosis of bovine viral diarrhea virus: an overview of currently available methods

Bovine viral diarrhea virus (BVDV) is the causative agent of bovine viral diarrhea (BVD), which results in significant economic losses in the global cattle industry. Fortunately, various diagnostic methods available for BVDV have been established. They include etiological methods, such as virus isolation (VI); serological methods, such as enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), and immunohistochemistry (IHC); molecular methods, such as reverse transcription-polymerase chain reaction (RT-PCR), real-time PCR, digital droplet PCR (ddPCR), loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), and CRISPR-Cas system; and biosensors. This review summarizes the current diagnostic methods for BVDV, discussing their advantages and disadvantages, and proposes future perspectives for the diagnosis of BVDV, with the intention of providing valuable guidance for effective diagnosis and control of BVD disease.

Protective Effect of Curcumin on D-Galactose-Induced Senescence and Oxidative Stress in LLC-PK1 and HK-2 Cells

D-galactose has been widely used as an inducer of cellular senescence and pathophysiological processes related to aging because it induces oxidative stress. On the other hand, the consumption of antioxidants such as curcumin can be an effective strategy to prevent phenotypes related to the enhanced production of reactive oxygen species (ROS), such as aging and senescence. This study aimed to evaluate the potential protective effect of curcumin on senescence and oxidative stress and endoplasmic reticulum stress induced by D-galactose treatment in Lilly Laboratories Culture-Porcine Kidney 1 (LLC-PK1) and human kidney 2 (HK-2) proximal tubule cell lines from pig and human, respectively. For senescence induction, cells were treated with 300 mM D-galactose for 120 h and, to evaluate the protective effect of the antioxidant, cells were treated with 5 µM curcumin for 24 h and subsequently treated with curcumin + D-galactose for 120 h. In LLC-PK1 cells, curcumin treatment decreased by 20% the number of cells positive for senescence-associated (SA)-β-D-galactosidase staining and by 25% the expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and increased by 40% lamin B1 expression. In HK-2 cells, curcumin treatment increased by 60% the expression of proliferating cell nuclear antigen (PCNA, 50% Klotho levels, and 175% catalase activity. In both cell lines, this antioxidant decreased the production of ROS (20% decrease for LLC-PK1 and 10 to 20% for HK-2). These data suggest that curcumin treatment has a moderate protective effect on D-galactose-induced senescence in LLC-PK1 and HK-2 cells.

Decellularized tissue exhibits large differences of extracellular matrix properties dependent on decellularization method: novel insights from a standardized characterization on skeletal muscle

Decellularized matrices are an attractive choice of scaffold in regenerative medicine as they can provide the necessary extracellular matrix (ECM) components, signals and mechanical properties. Various detergent-based protocols have already been proposed for decellularization of skeletal muscle tissue. However, a proper comparison is difficult due to differences in species, muscle origin and sample sizes. Moreover, a thorough evaluation of the remaining acellular matrix is often lacking. We compared an in-house developed decellularization protocol to four previously published methods in a standardized manner. Porcine skeletal muscle samples with uniform thickness were subjected to in-depth histological, ultrastructural, biochemical and biomechanical analysis. In addition, 2D and three-dimensional cytocompatibility experiments were performed. We found that the decellularization methods had a differential effect on the properties of the resulting acellular matrices. Sodium deoxycholate combined with deoxyribonuclease I was not an effective method for decellularizing thick skeletal muscle tissue. Triton X-100 in combination with trypsin, on the other hand, removed nuclear material but not cytoplasmic proteins at low concentrations. Moreover, it led to significant alterations in the biomechanical properties. Finally, sodium dodecyl sulphate (SDS) seemed most promising, resulting in a drastic decrease in DNA content without major effects on the ECM composition and biomechanical properties. Moreover, cell attachment and metabolic activity were also found to be the highest on samples decellularized with SDS. Through a newly proposed standardized analysis, we provide a comprehensive understanding of the impact of different decellularizing agents on the structure and composition of skeletal muscle. Evaluation of nuclear content as well as ECM composition, biomechanical properties and cell growth are important parameters to assess. SDS comes forward as a detergent with the best balance between all measured parameters and holds the most promise for decellularization of skeletal muscle tissue.

Inhibition of SIRT7 overcomes sorafenib acquired resistance by suppressing ERK1/2 phosphorylation via the DDX3X-mediated NLRP3 inflammasome in hepatocellular carcinoma

AIMS

Sirtuin 7 (SIRT7) plays an important role in tumor development, and has been characterized as a potent regulator of cellular stress. However, the effect of SIRT7 on sorafenib acquired resistance remains unclear and a possible anti-tumor mechanism beyond this process in HCC has not been clarified. We examined the therapeutic potential of SIRT7 and determined whether it functions synergistically with sorafenib to overcome chemoresistance.

METHODS

Cancer Genome Atlas-liver HCC data and unbiased gene set enrichment analyses were used to identify SIRT7 as a potential effector molecule in sorafenib acquired resistance. Two types of SIRT7 chemical inhibitors were developed to evaluate its therapeutic properties when synergized with sorafenib. Mass spectrometry was performed to discover a direct target of SIRT7, DDX3X, and DDX3X deacetylation levels and protein stability were explored. Moreover, an in vivo xenograft model was used to confirm anti-tumor effect of SIRT7 and DDX3X chemical inhibitors combined with sorafenib.

RESULTS

SIRT7 inhibition mediated DDX3X depletion can re-sensitize acquired sorafenib resistance by disrupting NLRP3 inflammasome assembly, finally suppressing hyperactive ERK1/2 signaling in response to NLRP3 inflammasome-mediated IL-1β inhibition.

CONCLUSIONS

SIRT7 is responsible for sorafenib acquired resistance, and its inhibition would be beneficial when combined with sorafenib by suppressing hyperactive pro-cell survival ERK1/2 signaling.

tANCHOR cell-based ELISA approach as a surrogate for antigen-coated plates to monitor specific IgG directed to the SARS-CoV-2 receptor-binding domain

Enzyme-linked immunosorbent assay (ELISA) systems use plates coated with peptides or expressed and purified proteins to monitor immunoglobulins derived from patient serum. However, there is currently no easy, flexible, and fast adaptive ELISA-based system for testing antibodies directed against new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. In this study, we utilized the tANCHOR protein display system that provides a cell surface decorated with the receptor-binding domain (RBD) to monitor specific antibodies derived from SARS-CoV-2 convalescent and vaccinated individuals directed against it. To test sera from vaccinees or convalescent individuals, only the RBD coding sequence needs to be cloned in the tANCHOR vector system and transfected into HeLa cells. Time-consuming protein expression, isolation, and purification followed by coating assay plates are not necessary. With this technique, the immune evasion of new SARS-CoV-2 variants from current vaccination regimes can be examined quickly and reliably.

Flow Cytometric and Immunohistochemical Follow-Up of Spermatogonial Lineage Commitment

Flow cytometry and immunohistochemistry techniques both determine the target protein by immunolabeling. Flow cytometric analysis quantifies total number of fluorescent labeled cells and qualify sup-populations according to size and granularity. Immunohistochemistry is able to map immune-labeled cells and extracellular matrix components under light and electron microscope by enzyme or fluorescent molecules. Real-time identification, in-time classification, and final plotting of spermatogonial lineage are of crucial importance for monitoring the fertility potential of spermatogonial stem cell microenvironment and predicting progress of spermatogenesis. Here we define the evaluation of mouse male germ cell microenvironment at single cell and whole tissue section levels by using flow cytometric and immunohistochemical approaches.

Polyvalent passive vaccine candidates from egg yolk antibodies (IgY) of important outer membrane proteins (PF1380 and ExbB) of Pseudomonas fluorescens in fish

Polyvalent antibodies can resist multiple bacterial species, and immunoglobulin Y (IgY) antibody can be economically prepared in large quantities from egg yolk; further, IgY polyvalent antibodies have application value in aquaculture. The outer membrane proteins (OMPs) PF1380 and ExbB of Pseudomonas fluorescens were expressed and purified, and the corresponding IgY antibodies were prepared. PF1380, ExbB, and the corresponding IgY antibodies could activate the innate immune responses of chicken and Carassius auratus. The passive immunization to C. auratus showed that the IgY antibodies of PF1380 and ExbB had an immune protection rate, down-regulated the expression of antioxidant-related factors (MDA, SOD, GSH-Px, and CAT) to reduce the antioxidant reaction, down-regulated the expression of inflammation-related genes (IL-6, IL-8, TNF-α, and IL-1β) to reduce the inflammatory reaction, maintained the integrity of visceral tissue structure, and reduced apoptosis and damage of tissue cells in relation to P. fluorescens and Aeromonas hydrophila infections. Thus, the IgY antibodies of PF1380 and ExbB could be considered as passive polyvalent vaccine candidates in aquaculture.

Scaling of an antibody validation procedure enables quantification of antibody performance in major research applications

Antibodies are critical reagents to detect and characterize proteins. It is commonly understood that many commercial antibodies do not recognize their intended targets, but information on the scope of the problem remains largely anecdotal, and as such, feasibility of the goal of at least one potent and specific antibody targeting each protein in a proteome cannot be assessed. Focusing on antibodies for human proteins, we have scaled a standardized characterization approach using parental and knockout cell lines (Laflamme et al., 2019) to assess the performance of 614 commercial antibodies for 65 neuroscience-related proteins. Side-by-side comparisons of all antibodies against each target, obtained from multiple commercial partners, have demonstrated that: (i) more than 50% of all antibodies failed in one or more applications, (ii) yet, ~50-75% of the protein set was covered by at least one high-performing antibody, depending on application, suggesting that coverage of human proteins by commercial antibodies is significant; and (iii) recombinant antibodies performed better than monoclonal or polyclonal antibodies. The hundreds of underperforming antibodies identified in this study were found to have been used in a large number of published articles, which should raise alarm. Encouragingly, more than half of the underperforming commercial antibodies were reassessed by the manufacturers, and many had alterations to their recommended usage or were removed from the market. This first study helps demonstrate the scale of the antibody specificity problem but also suggests an efficient strategy toward achieving coverage of the human proteome; mine the existing commercial antibody repertoire, and use the data to focus new renewable antibody generation efforts.

Protocol for enrichment, purification, and cytocentrifugation of mouse liver endothelial cells

Liver endothelial cells (LECs) are critical in maintaining liver homeostasis. To understand the mechanistic processes occurring in these cells, high-quality isolation protocols must be in place. Here, we present a protocol for LEC enrichment, subsequent LEC purification using fluorescence-assisted cell sorting, and cytocentrifugation of sorted LECs for imaging. We describe steps for isolation of LEC-enriched population from mouse livers, immunolabeling and sorting, and cytospin and immunostaining. We then mention procedures for downstream analysis. For complete details on the use and execution of this protocol, please refer to Drzewiecki et al. (2021).1.

Progress in etiological diagnosis of viral meningitis

In recent years, with the rapid development of molecular biology techniques such as polymerase chain reaction and molecular biochip, the etiological diagnosis of viral encephalitis has a very big step forward. At present, the etiological examination of viral meningitis mainly includes virus isolation, serological detection and molecular biological nucleic acid detection. This article reviews the progress in etiological diagnosis of viral meningitis.

The Utility of Mitochondrial Detection Methods Applied as an Additional Tool for the Differentiation of Renal Cell Tumors

The precise differentiation of renal cell tumors (RCTs) is sometimes hard to achieve using standard imaging and histopathological methods, especially for those with eosinophilic features. It has been suggested that the vast overabundance of mitochondria, as a well-known hallmark of eosinophilic cytoplasm, and could be a characteristic of distinct tumor types with opposing clinical outcomes. Thus, we intended to explore the associations between mitochondrial distribution patterns in different RCTs, including 43 cell renal cell carcinomas (ccRCCs), 15 papillary renal cell carcinomas (pRCCs), 20 chromophobe renal cell carcinomas (chRCCs), and 18 renal oncocytomas (ROs). Tumor samples were stained with two anti-mitochondrial antibodies (mitochondrial antibody Ab-2, clone MTC02; prohibitin, II-14-10, MA5-12858), applying immunohistochemistry and immunofluorescence to define mitochondrial distribution patterns (coarse scanty, moderate granular, and diffuse granular). Our results revealed significantly different expression patterns among the investigated RCTs (p < 0.001). The majority of ccRCCs exhibited coarse scanty mitochondrial staining, while all chRCCs had moderate granular expression. Nevertheless, all ROs, all pRCCs, and two cases of ccRCC presenting with higher nuclear grade and eosinophilic cytoplasm had diffuse granular mitochondrial expression. Moreover, with increased distribution of mitochondria, the intensity of staining was higher (p < 0.001). Here we present a strategy that utilizes fast and easy mitochondrial detection to differentiate RO from chRCC, as well as other eosinophilic variants of RCC with high accuracy.

A novel immunohistochemical protocol for paraffin embedded tissue sections using free-floating techniques

Immunohistochemistry (IHC) is a well-established and widely used protocol used to visualize tissue architecture, protein expression and localization. Free-floating methods for IHC employ tissue sections that are cut from a cryostat or vibratome. The limitations of these tissue sections are tissue fragility, poor morphology, and the need to use sections of 20-50 μm. In addition, there is a void of information regarding the use of free floating immunohistochemical techniques on paraffin embedded tissue. To address this, we developed a free-float IHC protocol with paraffin embedded tissue (PFFP) that saves time, resources, and tissues. PFFP localized GFAP, olfactory marker protein, tyrosine hydroxylase, and Nestin expression in mouse hippocampal, olfactory bulb, striatum, and cortical tissue. Successful localization of these antigens was achieved using PFFP with and without antigen retrieval, with subsequent chromogenic DAB (3,3'-diaminobenzidine) development and immunofluorescence detection methods. The application of the PFFP in combination with methodologies of in situ hybridization, protein/protein interactions, laser capture dissection, and pathological diagnosis expands the versatility of paraffin embedded tissues.

TARTESSUS: A Customized Electrospun Drug Delivery System Loaded with Irinotecan for Local and Sustained Chemotherapy Release in Pancreatic Cancer

Post-surgical chemotherapy in pancreatic cancer has notorious side effects due to the high dose required. Multiple devices have been designed to tackle this aspect and achieve a delayed drug release. This study aimed to explore the controlled and sustained local delivery of a reduced drug dose from an irinotecan-loaded electrospun nanofiber membrane (named TARTESSUS) that can be placed on the patients' tissue after tumor resection surgery. The drug delivery system formulation was made of polycaprolactone (PCL). The mechanical properties and the release kinetics of the drug were adjusted by the electrospinning parameters and by the polymer ratio between 10 w.t.% and 14 w.t.% of PCL in formic acid:acetic acid:chloroform (47.5:47.5:5). The irinotecan release analysis was performed and three different release periods were obtained, depending on the concentration of the polymer in the dissolution. The TARTESSUS device was tested in 2D and 3D cell cultures and it demonstrated a decrease in cell viability in 2D culture between 72 h and day 7 from the start of treatment. In 3D culture, a decrease in viability was seen between 72 h, day 7 (p < 0.001), day 10 (p < 0.001), 14 (p < 0.001), and day 17 (p = 0.003) as well as a decrease in proliferation between 72 h and day 10 (p = 0.030) and a reduction in spheroid size during days 10 (p = 0.001), 14 (p < 0.001), and 17 (p < 0.001). In conclusion, TARTESSUS showed a successful encapsulation of a chemotherapeutic drug and a sustained and delayed release with an adjustable releasing period to optimize the therapeutic effect in pancreatic cancer treatment.

Male reproductive toxicity of polystyrene microplastics: Study on the endoplasmic reticulum stress signaling pathway

Microplastics (MPs) have raised health concerns in public for its potential reproductive toxicity. In this study, we subjected the Kunming mice to 0.01, 0.1 and 1.0 mg/day polystyrene MPs (10 μm, PS-MPs) for 35 days, aiming to investigate the relevant male reproductive toxicity and latent molecular mechanism. The results showed the decreased sperm counts and motility, while the elevated sperm abnormality in PS-MPs-exposed mice. Testicular H&E staining displayed the vacuolization, atrophy, and even shedding of germ cells in seminiferous tubule. And the testosterone content in serum also decreased with PS-MPs treatment. Moreover, molecular analysis indicated that PS-MPs upregulated the expression trait factors for ERS (e.g., immunoglobulin-binding protein [BIP], inositol-requiring protein 1α [IRE1α], X-box-binding protein 1 splicing [XBP1s], Jun kinase [JNK], and the transcription of CCAAT/enhancer-binding protein (C/EBP) homologous protein [CHOP]) and downstream apoptotic modulator (e.g., Caspase-12, -9, and -3) in the testis. The steroidogenic acute regulatory protein (StAR), the testosterone synthetic initiator, was also downregulated. With the supplementation of ERS inhibitor, the MPs-induced testicular damage and decreased testosterone were improved to almost normal level. Overall, this study suggested that PS-MPs generate reproductive toxicity possibly via activating ERS and apoptosis signaling pathway.

Fast and Multiplexed Super Resolution Imaging of Fixed and Immunostained Cells with DNA-PAINT-ERS

Recent advances in super resolution microscopy have enabled imaging at the 10-20 nm scale on a light microscope, providing unprecedented details of native biological structures and processes in intact and hydrated samples. Of the existing strategies, DNA points accumulation in imaging nanoscale topography (DNA-PAINT) affords convenient multiplexing, an important feature in interrogating complex biological systems. A practical limitation of DNA-PAINT, however, has been the slow imaging speed. In its original form, DNA-PAINT imaging of each target takes tens of minutes to hours to complete. To address this challenge, several improved implementations have been introduced. These include DNA-PAINT-ERS (where E = ethylene carbonate; R = repeat sequence; S = spacer), a set of strategies that leads to both accelerated DNA-PAINT imaging speed and improved image quality. With DNA-PAINT-ERS, imaging of typical cellular targets such as microtubules takes only 5-10 min. Importantly, DNA-PAINT-ERS also facilitates multiplexing and can be easily integrated into current workflows for fluorescence staining of biological samples. Here, we provide a detailed, step-by-step guide for fast and multiplexed DNA-PAINT-ERS imaging of fixed and immunostained cells grown on glass substrates as adherent monolayers. The protocol should be readily extended to biological samples of a different format (for example tissue sections) or staining mechanisms (for example using nanobodies). © 2022 Wiley Periodicals LLC. Basic Protocol 1: Preparation of probes for DNA-PAINT-ERS Basic Protocol 2: Sample preparation for imaging membrane targets with DNA-PAINT-ERS in fixed cells Alternate Protocol: Immunostaining of extracted U2OS cells Basic Protocol 3: Super resolution image acquisition and analysis.

A practical reference for studying meiosis in the model ciliate Tetrahymena thermophila

Meiosis is a critical cell division program that produces haploid gametes for sexual reproduction. Abnormalities in meiosis are often causes of infertility and birth defects (e.g., Down syndrome). Most organisms use a highly specialized zipper-like protein complex, the synaptonemal complex (SC), to guide and stabilize pairing of homologous chromosomes in meiosis. Although the SC is critical for meiosis in many eukaryotes, there are organisms that perform meiosis without a functional SC. However, such SC-less meiosis is poorly characterized. To understand the features of SC-less meiosis and its adaptive significance, the ciliated protozoan Tetrahymena was selected as a model. Meiosis research in Tetrahymena has revealed intriguing aspects of the regulatory programs utilized in its SC-less meiosis, yet additional efforts are needed for obtaining an in-depth comprehension of mechanisms that are associated with the absence of SC. Here, aiming at promoting a wider application of Tetrahymena for meiosis research, we introduce basic concepts and core techniques for studying meiosis in Tetrahymena and then suggest future directions for expanding the current Tetrahymena meiosis research toolbox. These methodologies could be adopted for dissecting meiosis in poorly characterized ciliates that might reveal novel features. Such data will hopefully provide insights into the function of the SC and the evolution of meiosis from a unique perspective.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-022-00149-8.

Quantifying Intracellular Viral Pathogen: Specimen Preparation, Visualization and Quantification of Multiple Immunofluorescent Signals in Fixed Human Airway Epithelium Cultured at Air-Liquid Interface

Infection control and aggressive antibiotic therapy play an important role in the management of airway infections in individuals with cystic fibrosis (CF). The responses of airway epithelial cells to pathogens are likely to contribute to the pathobiology of CF lung disease. Primary airway epithelial cells obtained from individuals with CF, cultured and differentiated at air-liquid interface (ALI), effectively mimic the structure and function of the in vivo airway epithelium. With the recent respiratory viral pandemics, ALI cultures were extensively used to model respiratory infections in vitro to facilitate physiologically relevant respiratory research. Immunofluorescence staining and imaging were used as an effective tool to provide a fundamental understanding of host–pathogen interactions and for exploring the therapeutic potential of novel or repurposed drugs. Therefore, we described an optimized quantitative fluorescence microscopy assay for the wholemount staining and imaging of epithelial cell markers to identify distinct cell populations and pathogen-specific targets in ALI cultures of human airway epithelial cells grown on permeable support insert membranes. We present a detailed methodology using a graphical user interface (GUI) package to quantify the detected signals on a tiled whole membrane. Our method provided an imaging strategy of the entire membrane, overcoming the common issue of undersampling and enabling unbiased quantitative analysis.

Glyoxal Fixation Is Optimal for Immunostaining of Brain Vessels, Pericytes and Blood-Brain Barrier Proteins

Brain vascular staining is very important for understanding cerebrovascular pathologies. 4% paraformaldehyde is considered the gold standard fixation technique for immunohistochemistry and it revolutionized the examination of proteins in fixed tissues. However, this fixation technique produces inconsistent immunohistochemical staining results due to antigen masking. Here, we test a new fixation protocol using 3% glyoxal and demonstrate that this method improves the staining of the brain vasculature, pericytes, and tight junction proteins compared to 4% paraformaldehyde. Use of this new fixation technique will provide more detailed information about vascular protein expressions, their distributions, and colocalizations with other proteins at the molecular level in the brain vasculature.

Comment on Piña et al. Ten Approaches That Improve Immunostaining: A Review of the Latest Advances for the Optimization of Immunofluorescence. Int. J. Mol. Sci. 2022, 23, 1426

With great interest, I have read the article "Ten Approaches That Improve Immunostaining: A Review of the Latest Advances for the Optimization of Immunofluorescence" written by Piña et al. [...].