Application of the DNA-specific stain methyl green in the fluorescent labeling of embryos

Glutaraldehyde-enhanced autofluorescence as a general tool for 3D morphological imaging

Routine histochemical techniques are capable of producing vast amount of information from diverse sample types, but these techniques are limited in their ability to generate 3D information. Autofluorescence imaging can be used to analyse samples in 3D but it suffers from weak/low signal intensities. Here, we describe a simple chemical treatment with glutaraldehyde to enhance autofluorescence for 3D fluorescence imaging and to generate detailed morphological images on whole-mount samples. This methodology is straightforward and cost-effective to implement, suitable for a wide range of organisms and sample types. Furthermore, it can be readily integrated with standard confocal and fluorescence microscopes for analysis. This approach has the potential to facilitate the analysis of biological 3D structures and research in developmental biology, including studies on model and non-model organisms.

Exploring the cytotoxicity on human lung cancer cells and DNA binding stratagem of camptothecin functionalised silver nanoparticles through multi-spectroscopic, and calorimetric approach

The influence of nanoparticles inside the human body and their interactions with biological macromolecules need to be explored/studied prior to specific applications. The objective of this study is to find the potential of camptothecin functionalised silver nanoparticles (CMT-AgNPs) in biomedical applications. This article primarily investigates the binding stratagem of CMT-AgNPs with calf thymus DNA (ctDNA) through a series of spectroscopic and calorimetric methods and then analyses the anticancer activity and cytotoxicity of CMT-AgNPs. The nanoparticles were synthesized using a simple one pot method and characterized using UV-Visible, fourier transform infrared (FTIR) spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). The average size of CMT-AgNPs is 10 ± 2 nm. A group of experimental techniques such as UV-Visible spectrophotometry, fluorescence dye displacement assay, circular dichroism (CD) and viscosity analysis unravelled the typical groove binding mode of CMT-AgNPs with ctDNA. The CD measurement evidenced the minor conformational alterations of double helical structure of ctDNA in the presence of CMT-AgNPs. The information deduced from the isothermal titration calorimetry (ITC) experiment is that the binding was exothermic and spontaneous in nature. Moreover, all the thermodynamic binding parameters were extracted from the ITC data. The binding constants obtained from UV absorption experiments, fluorescence dye displacement studies and ITC were consistently in the order of 10⁴ Mol^-1. All these results validated the formation of CMT-AgNPs-ctDNA complex and the results unambiguously confirm the typical groove binding mode of CMT-AgNPs. An exhaustive in vitro MTT assay by CMT-AgNPs and CMT against A549, HT29, HeLa and L929 cell lines revealed the capability of CMT-AgNPs as a potential anticancer agent.

Cell–Fibronectin Interactions and Actomyosin Contractility Regulate the Segmentation Clock and Spatio-Temporal Somite Cleft Formation during Chick Embryo Somitogenesis

Fibronectin is essential for somite formation in the vertebrate embryo. Fibronectin matrix assembly starts as cells emerge from the primitive streak and ingress in the unsegmented presomitic mesoderm (PSM). PSM cells undergo cyclic waves of segmentation clock gene expression, followed by Notch-dependent upregulation of meso1 in the rostral PSM which induces somite cleft formation. However, the relevance of the fibronectin matrix for these molecular processes remains unknown. Here, we assessed the role of the PSM fibronectin matrix in the spatio-temporal regulation of chick embryo somitogenesis by perturbing (1) extracellular fibronectin matrix assembly, (2) integrin–fibronectin binding, (3) Rho-associated protein kinase (ROCK) activity and (4) non-muscle myosin II (NM II) function. We found that integrin–fibronectin engagement and NM II activity are required for cell polarization in the nascent somite. All treatments resulted in defective somitic clefts and significantly perturbed meso1 and segmentation clock gene expression in the PSM. Importantly, inhibition of actomyosin-mediated contractility increased the period of hairy1/hes4 oscillations from 90 to 120 min. Together, our work strongly suggests that the fibronectin–integrin–ROCK–NM II axis regulates segmentation clock dynamics and dictates the spatio-temporal localization of somitic clefts.

Removal of eDNA from fabrics using a novel laundry DNase revealed using high-resolution imaging

Washed textiles can remain malodorous and dingy due to the recalcitrance of soils. Recent work has found that 'invisible' soils such as microbial extracellular DNA (eDNA) play a key role in the adhesion of extracellular polymeric substances that form matrixes contributing to these undesirable characteristics. Here we report the application of an immunostaining method to illustrate the cleaning mechanism of a nuclease (DNase I) acting upon eDNA. Extending previous work that established a key role for eDNA in anchoring these soil matrixes, this work provides new insights into the presence and effective removal of eDNA deposited on fabrics using high-resolution in-situ imaging. Using a monoclonal antibody specific to Z-DNA, we showed that when fabrics are washed with DNase I, the incidence of microbial eDNA is reduced. As well as a quantitative reduction in microbial eDNA, the deep cleaning benefits of this enzyme are shown using confocal microscopy and imaging analysis of T-shirt fibers. To the best of our knowledge, this is the first time the use of a molecular probe has been leveraged for fabric and homecare-related R&D to visualize eDNA and evaluate its removal from textiles by a new-to-laundry DNase enzyme. The approaches described in the current work also have scope for re-application to identify further cleaning technology.

Comparative analysis of nucleomorphometric parameters in methyl green-pyronin-stained sections of oral epithelial dysplasia, oral submucous fibrosis and oral squamous cell carcinoma

Context:

The diagnosis and grading of epithelial dysplasia is based on a combination of architectural and cytological changes. A gradual increase in quantitative DNA aberrations has been found to correlate with increasing degree of dysplasia in oral mucous membranes.

Aims:

The aim of this study is to assess nuclear parameters in potentially malignant and malignant lesions of the oral cavity and to assess cytomorphometric changes in the nucleus and nucleolus in oral epithelial dysplasia (OED), oral submucous fibrosis (OSMF), oral squamous cell carcinoma (OSCC) and normal oral mucosa using methyl green-pyronin staining to determine its suitability for detecting potentially malignant lesions and the stage of carcinogenesis.

Methods:

Forty-five archival sections of OED, OSMF and OSCC and 5 cases of normal oral mucosa as the control group were stained according to methyl green-pyronin-staining protocol. Cytomorphometric parameters such as nuclear diameter, nucleolar diameter, number of nucleoli and cytoplasmic RNA were assessed.

Statistical Analysis Used:

The study was subjected to statistical analysis to evaluate the association between morphometric parameters using analysis of variance test, followed by Bonferroni's post hoc analysis.

Results:

A progressive increase in the nuclear parameters as well as cytoplasmic RNA content was observed between normal mucosa through dysplasia and OSMF to OSCC.

Conclusion:

This study serves as an effective diagnostic aid in assessing nuclear parameters in potentially malignant and malignant epithelial lesions affecting oral cavity.

Visualizing mesoderm and neural crest cell dynamics during chick head morphogenesis

Vertebrate head morphogenesis involves carefully-orchestrated tissue growth and cell movements of the mesoderm and neural crest to form the distinct craniofacial pattern. To better understand structural birth defects, it is important that we characterize the dynamics of these processes and learn how they rely on each other. Here we examine this question during chick head morphogenesis using time-lapse imaging, computational modeling, and experiments. We find that head mesodermal cells in culture move in random directions as individuals and move faster in the presence of neural crest cells. In vivo, mesodermal cells migrate in a directed manner and maintain neighbor relationships; neural crest cells travel through the mesoderm at a faster speed. The mesoderm grows with a non-uniform spatio-temporal profile determined by BrdU labeling during the period of faster and more-directed neural crest collective migration through this domain. We use computer simulations to probe the robustness of neural crest stream formation by varying the spatio-temporal growth profile of the mesoderm. We follow this with experimental manipulations that either stop mesoderm growth or prevent neural crest migration and observe changes in the non-manipulated cell population, implying a dynamic feedback between tissue growth and neural crest cell signaling to confer robustness to the system. Overall, we present a novel descriptive analysis of mesoderm and neural crest cell dynamics that reveals the coordination and co-dependence of these two cell populations during head morphogenesis.

Loss- and Gain-of-function Approach to Investigate Early Cell Fate Determinants in Preimplantation Mouse Embryos

Gene silencing and overexpression techniques are instrumental for the identification of genes involved in embryonic development. Direct target gene modification in preimplantation embryos provides a means to study the underlying mechanisms of genes implicated in, for instance, cellular differentiation into the trophectoderm (TE) and the inner cell mass (ICM). Here, we describe a protocol that examines the role of neogenin as an authentic receptor for initial cell fate determination in preimplantation mouse embryos. First, we discuss the experimental manipulations that were used to produce gain and loss of neogenin function by microinjecting neogenin cDNA and shRNA; the effectiveness of this approach was confirmed by a strong correlation between the pair-wise expression levels of either red fluorescent protein (RFP) or green fluorescent protein (GFP) and the immunocytochemical quantification of neogenin expression. Secondly, overexpression of neogenin in preimplantation mouse embryos leads to normal ICM development while neogenin knockdown causes the ICM to develop abnormally, implying that neogenin could be a receptor that relays extracellular cues to drive blastomeres to early cell fates. Given the success of this detailed protocol in investigating the function of a novel embryonic developmental stage-specific receptor, we propose that it has the potential to aid in exploration and identification of other stage-specific genes during embryogenesis.