A single-cell 3D dynamic volume control system for chondrocytes
In articular cartilage, zone-specific cellular morphology is a typical characteristic of cartilage tissue, which is related with chondrocyte function, inflammation and osteoarthritis (OA). Chondrocyte hypertrophic phenotype is a criticle physiological process which indicates a hallmark of chondrocyte terminal differentiation and bone formation. Thus, developing a cell culture system for dynamic regulation of single chondrocyte volume at a three-dimensional (3D) level is particularly necessary for understanding how physical cues of matrix microenvironment regulate chondrocyte fate and the degeneration of articular cartilage. Here, based on the soft lithography techniques, we have constructed well-defined single-cell 3D dynamic volume control system to recapitulate the physiological matrix microenvironment of single chondrocyte niche. The results of finite element analysis indicated that the stress and strain distribution in the cell culture region is homogeneous during the stretching process. Additionally, 3D dynamic volume expansion and compression of single cells in physiological or hyperphysiological can be realized in this cell culture system. Our device for single-cell 3D dynamic culture provides a microphysiological culture system for chondrocytes to explore the mechanisms of cartilage hypertrophy, as well as develops a new paradigm for functional cartilage tissue engineering and regenerative medicine.
A HABA dye-based colorimetric assay to detect unoccupied biotin binding sites in an avidin-containing fusion protein
Avidin-biotin binding, the most robust non-covalent protein-ligand interaction occurring in nature, has wide-ranging applications in biotechnology. A frequent challenge in these applications is accurately determining the number of unoccupied biotin binding sites in avidin-containing fusion proteins. We delineate a novel assay protocol in miniaturized format to quantify available biotin binding sites based on the affinity of the anionic dye 4'-hydroxyazobenzene-2-carboxylic acid for biotin binding sites within avidin. We apply this assay as a quality control assay to evaluate the number of available biotin binding sites in different fusion protein production batches. This method offers a streamlined alternative to fluorescence-based assays commonly employed to assess biotin binding, is less time-consuming than other methods and is applicable to diverse fusion proteins.
Prioritizing privacy and presentation of supportable hypothesis testing in forensic genetic genealogy investigations
Investigative leads are not generated by traditional forensic DNA testing, if the source of the forensic evidence or a 1st degree relative of unidentified human remains is not in the DNA database. In such cases, forensic genetic genealogy (FGG) can provide valuable leads. However, FGG generated genetic data contain private and sensitive information. Therefore, it is essential to deploy approaches that minimize unnecessary disclosure of these data to mitigate potential risks to individual privacy. We recommend protective practices that need not impact effective reporting of relationship identifications. Examples include performing one-to-one comparisons of DNA profiles of third-party samples and evidence samples offline with an "air gap" to the internet and shielding the specific shared single nucleotide polymorphisms (SNP) states and locations by binning adjacent SNPs in forensic reports. Such approaches reduce risk of unwanted access to or reverse engineering of third-party individuals' genetic data and can give these donors greater confidence to support use of their DNA profiles in FGG investigation.
pJoseph2: a family of plasmids as positive controls for bacterial protein expression, transfections, and western blots
Epitope tagging represents a powerful strategy for expedited identification, isolation, and characterization of proteins in molecular biological studies, including protein-protein interactions. We aimed to improve the reproducibility of epitope-tagged protein expression and detection by developing a range of plasmids as positive controls. The pJoseph2 family of expression plasmids functions in diverse cellular environments and cell types to enable the evaluation of transfection efficiency and antibody staining for epitope detection. The expressed green fluorescent proteins harbor five unique epitope tags, and their efficient expression in , Schneider's line 2 cells, and human SKOV3 and HEK293T cells was demonstrated by fluorescence microscopy and western blotting. The pJoseph2 plasmids provide versatile and valuable positive controls for numerous experimental applications.
A simple and rapid assay for identification of direct inhibitors of O-methylguanine-DNA methyltransferase
O-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that is overexpressed in certain tumors and is associated with resistance to the DNA alkylating agent temozolomide. MGMT inhibitors show potential in combating temozolomide resistance, but current assays for MGMT enzyme activity and inhibition, primarily oligonucleotide-based and fluorescent probe-based, are laborious and costly. The clinical relevance of temozolomide therapy calls for more convenient methodologies to study MGMT inhibition. Here, we extended the application of SNAP-Capture magnetic beads to develop a novel MGMT inhibition assay that demonstrated efficacy not only with known MGMT inhibitors, but also with the aldehyde dehydrogenase inhibitor, disulfiram. The assay uses standard fluorescence microscopy as a simple and reliable detection method, and is translationally applicable in drug discovery programs.
Functionalized primer initiated signal cycles and personal glucose meter for sensitive and portable miRNA analysis
MicroRNA (miRNA) has garnered considerable attention due to its diagnostic capabilities, such as in hypoxic cognitive impairment and cancers. However, the existing miRNA detection methods are commonly criticized for the drawbacks of low sensitivity and false-positive detection derived from interfering molecules. Here, we provide a novel, sensitive and portable method for miRNA detection by combining target identification based cyclization of padlocks, immobilized primer-based signal amplification and a personal glucose meter. The proposed method exhibits several advantages, including precise identification of specific sites, exceptional sensitivity and instrument-free feature. These attributes hold great promise for the diagnosis and clinical investigation of various diseases, such as cancer and hypoxic cognitive impairment, enabling a deeper understanding of their pathological and physiological aspects.
Cassava for the future: embryogenic liquid cultures suitable for new biotech techniques
Cassava, a crop of importance for subsistence farming in Africa, Asia, and Latin America, has the potential to benefit from global economic integration as a versatile industrial resource. Enhancing cassava productivity is not just a matter of agricultural competitiveness but a crucial step toward ensuring many communities' food security and livelihoods. Given its high performance in marginal environments, where climate change poses threats, ensuring food security and livelihoods relies on rapidly adapting cassava. This study aimed to develop a protocol that swiftly transitions cassava embryogenic short-period liquid suspension cultures, facilitating the regeneration of genetically stable plants. The resulting protocol, with its potential to be a foundational component in future technologies employing various genome editing or genetic modification techniques, holds promise for the advancement of cassava biotechnology.
Novel buffer for long-term preservation of DNA in biological material at room temperature
The collection and preservation of biological material before DNA analysis is critical for inter alia biomedical research, medical diagnostics, forensics and biodiversity conservation. In this study, we evaluate an in-house formulated buffer called the Forensic DNA Laboratory-buffer (FDL-buffer) for preservation of biological material for long term at room temperature. Human saliva stored in the buffer for 8 years, human blood stored for 3 years and delicate animal tissues from the jellyfish comb jelly sp., stored for 4 and 6 years respectively consistently produced high-quality DNA. FDL-buffer exhibited compatibility with standard organic, salting out and spin-column extraction methods, making it versatile and applicable to a wide range of applications, including automation.
Modular probe-based colorimetric miRNA detection polymerase/endonuclease assisted chain displacement
Methods for sequence-specific microRNA (miRNA) analysis are crucial for miRNA research and guiding nursing strategies. We have devised a colorimetric technique for detecting miRNA using a dumbbell probe-based polymerase/endonuclease assisted chain displacement, along with silver ions (Ag) aptamer assisted color reaction. The suggested approach enables precise measurement of miRNA-21 within the concentration range of 100 fM-5 nM, with a low detection limit of 45.32 fM. Additionally, it exhibits exceptional capability in distinguishing variations at the level of individual nucleotides. Furthermore, the detection technique may be utilized to precisely measure the amount of miRNA-21 in serum samples, demonstrating a high level of concordance with the findings obtained from a commercially available miRNA detection kit.
Sampling and analysis methods of air-borne microorganisms in hospital air: a review
Pathogenic microorganisms can spread in the air as bioaerosols. When the human body is exposed to different bioaerosols, various infectious diseases may occur. As indoor diagnosis and treatment environments, hospitals are relatively closed and have a large flow rate of people. This indoor environment contains complex aerosol components; therefore, effective sampling and detection of microbial elements are essential in airborne pathogen monitoring. This article reviews the sampling and detection of different kinds of microorganisms in bioaerosols from indoor diagnostic and therapeutic settings, with a particular focus on microbial activity. This provides deeper insights into bioaerosols in diagnostic and therapeutic settings.
When is an SNP not an SNP?
Genomic duplications are important sources of structural change and gene innovation. In humans, the most recent and highly identical sequences (>90% homology, >1 kb long) are known as segmental duplications (SDs). Single-nucleotide variants or single-nucleotide polymorphisms within SDs have not been systematically assessed due to limitations around mapping short-read sequencing data. Single-nucleotide variant rs62486260 was flagged in a study of familial renal stone disease but it was unclear whether it was real or an artifact resulting from the presence of a SD. We describe and wet-lab approaches to investigate this, using segment-specific long-PCR assays, followed by short PCR for Sanger sequencing. Our conclusion was that rs62486260 is an artifact. Our approach can be generalized to deal with other such situations.
An automatic classification method of testicular histopathology based on SC-YOLO framework
The pathological diagnosis and treatment of azoospermia depend on precise identification of spermatogenic cells. Traditional methods are time-consuming and highly subjective due to complexity of Johnsen score, posing challenges for accurately diagnosing azoospermia. Here, we introduce a novel SC-YOLO framework for automating the classification of spermatogenic cells that integrates S3Ghost module, CoordAtt module and DCNv2 module, effectively capturing texture and shape features of spermatogenic cells while reducing model parameters. Furthermore, we propose a simplified Johnsen score criteria to expedite the diagnostic process. Our SC-YOLO framework presents the higher efficiency and accuracy of deep learning technology in spermatogenic cell recognition. Future research endeavors will focus on optimizing the model's performance and exploring its potential for clinical applications.
Comparison of commercially available DNA and RNA extraction kits for wildlife feces collected from the environment
Wildlife fecal samples were collected across two Air Force installations to evaluate the effectiveness of commercially available DNA and RNA extraction kits. Four DNA kits, two DNA/RNA kits and one RNA only kit were used. Sample extracts were evaluated on nucleic acid concentration, TapeStation DNA or RNA Integrity Number values and presence of PCR inhibitors. For the DNA kits, PFP produced higher concentrations compared with PLM and RPM, while MWFM gave higher DNA Integrity Number values when compared with RPM. No PCR inhibition was detected. For the RNA kits, RPM gave higher concentrations compared with MWTV and no differences were seen in RNA Integrity Number values. PCR inhibition was observed in all RNA samples, with MWTV exhibiting higher inhibition compared with RPM.
Dual-mode detection of glucose based on pistol-like DNAzyme-mediated exonuclease-assisted signal cycle
Detecting glucose accurately and sensitively from clinical samples like tears and saliva is still difficult. We have created a sensor that can detect glucose with high sensitivity and accuracy by combining the use of glucose oxidase (GOx) to catalyze glucose, a pistol-like DNAzyme (PLDz) to transform the signal, gold nanoparticles (AuNPs) to enhance the optical properties and the exonuclease-III (Exo-III) to amplify the signal. As a result, the proposed method exhibits a low detection limit of 7.5 pM and a wide detection range covering seven orders of magnitude. The suggested dual-mode strategy provides a sensitive, precise and specific detection method for glucose. Another advantage is that the dual-mode technique significantly improves the precision and consistency of the measurements, demonstrating its immense potential for use in biomedical research and clinical diagnostics.
Mito-kaede photoactivation and chase experiment for mitophagy: optimizing flux measurement via fluid exchange system
Modulating autophagy and mitophagy, vital cellular quality control systems, offer therapeutic potential for critical illnesses. However, limited drug screening options hinder progress. We present a novel assay using the photoswitchable fluorescent reporter, mito-Kaede, to quantify mitophagy flux. Mito-Kaede's superior UV-induced photoconversion and brightness post-conversion make it ideal for prolonged mitochondrial dynamics tracking. Its specificity in responding to mitophagy, confirmed by parkin-knockout cells, adds value. When coupled with a custom fluid exchange system, enabling efficient medium changes, precise mitophagy observations become feasible. This mitophagy assay, alongside our methodological insights, can decipher mitophagy's role in pathology and supports drug screening efforts.
The environmental impact of AI in the lab: a double-edged sword?
Computational tools, particularly AI, are becoming more ubiquitous in scientific research; but what impact do they have on the environment?[Formula: see text].
Simple and sensitive detection of in neonatal infection based on a both-end blocked peroxidase-mimicking DNAzyme
Developing a simple and highly sensitive approach for () detection is crucial, as it is closely associated with various disorders, such as newborn infections. Nevertheless, few of techniques have the capability to accurately identify with a high level of sensitivity and significantly improved stability. The employment of the both-end blocked peroxidase-mimicking DNAzyme significantly diminished the interferences from background signals, so conferring the approach with a high degree of selectivity and reproducibility. The proposed method is demonstrated with exceptional discernment capacity in differentiating interfering microorganisms. The simplicity, elevated sensitivity and high discerning capability make the method a highly promising alternative instrument for pathogenic bacteria detection.
Adipocyte ABCA1 expression analysis using flow cytometry
Adipocyte characterization and assessing membrane proteins using flow cytometry has been proven to be challenging as adipocytes are fragile, especially in subjects with high BMI. We overcame these challenges through a protocol optimizing tissue digestion time by reducing intermediate steps to minimize adipocyte friction and breakage. We avoided requirement for specialized instrument configuration and used a modified gating strategy to prevent inclusion of lipid droplets during analysis. Up to 90% of the cell population were available in the gating area. We checked the expression level of ABCA1, a membrane protein reaffirming adipocyte selection. In summary, this protocol requires lesser tissue sample improving feasibility and cost efficiency. Thus, our flow cytometry method is an improvement for studying adipocyte membrane characteristics.
A standardized protocol for sample preparation for scanning electron microscopy to visualize extrachromosomal DNA
Extrachromosomal DNA (ecDNA) are circular DNA structures associated with cancer and drug resistance. One specific type, double minute (DM) chromosomes, has been studied since the 1960s using imaging techniques like cytogenetics and fluorescence microscopy. Specialized techniques such as atomic force microscopy (AFM) and scanning electron microscopy (SEM) offer micro to nano-scale visualization, but current sample preparation methods may not optimally preserve ecDNA structure. Our study introduces a systematic protocol using SEM for high-resolution ecDNA visualization. We have optimized the end-to-end procedure, providing a standardized approach to explore the circular architecture of ecDNA and address the urgent need for better understanding in cancer research.
Artificial intelligence: help or hindrance in solving the reproducibility crisis?
Science is in the midst of a reproducibility crisis and the integration of artificial intelligence into scientific research has only compounded the problem; yet could the technology hold the solution to its own problems?[Formula: see text].
Mapping the spread of antibiotic resistance genes in the coastal microbiome
StandfirstCoastal environments are becoming increasingly exposed to antibiotics through anthropogenic inputs. But how could emerging metagenomic techniques be used to map the spread of antibiotic resistance genes in the coastal microbiome?[Formula: see text].