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Preparation of fluorescent in situ hybridisation probes without the need for optimisation of fragmentation
摘要： DNA-fluorescence in situ hybridisation (DNA-FISH) allows visualisation of chromosome organisation and fluorescently labelled DNA fragments that are often produced from rearrangement. FISH probes are pools of short template plasmids that contain large genomic inserts. For effective sample penetration and target hybridisation it is critical that probe fragments are between 200 and 500bp. Production of these short probes requires significant optimisation and can be confounded access to expensive sonication equipment or inherent sequence features that influence enzymatic fragmentation or amplification. Here we demonstrate that effective FISH probes can be prepared without the need for optimisation of fragmentation using a cocktail of two the 4bp recognition sequence restriction enzymes CviQI and AluI.
关键词： Cancer,Fluorescence in situ hybridization,Translocation,FISH,Probe
更新于2025-09-23 15:23:52
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LITESEC-T3SS - Light-controlled protein delivery into eukaryotic cells with high spatial and temporal resolution
摘要： Many bacteria employ a type III secretion system (T3SS) injectisome to translocate proteins into eukaryotic host cells. Although the T3SS can efficiently export heterologous cargo proteins, a lack of target cell specificity currently limits its application in biotechnology and healthcare. In this study, we exploit the dynamic nature of the T3SS to govern its activity. Using optogenetic interaction switches to control the availability of the dynamic cytosolic T3SS component SctQ, T3SS-dependent effector secretion can be regulated by light. The resulting system, LITESEC-T3SS (Light-induced translocation of effectors through sequestration of endogenous components of the T3SS), allows rapid, specific, and reversible activation or deactivation of the T3SS upon illumination. We demonstrate the light-regulated translocation of heterologous reporter proteins, and induction of apoptosis in cultured eukaryotic cells. LITESEC-T3SS constitutes a new method to control protein secretion and translocation into eukaryotic host cells with unparalleled spatial and temporal resolution.
关键词： protein translocation,eukaryotic cells,optogenetics,type III secretion system,LITESEC-T3SS
更新于2025-09-23 15:21:01
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Detail investigation of toxicity, bioaccumulation, and translocation of Cd-based quantum dots and Cd salt in white mustard
摘要： In this study, a model crop plant white mustard (Sinapis alba L.) was treated with an aqueous dispersion of silica-coated CdTe quantum dots (CdTe/SiO2 QDs) in a 72-hours short-term toxicity test. The toxicity was established via measurements of (i) the root length and (ii) the chlorophyll fluorescence. These results were compared to two other sources of cadmium, free Cd ions (CdCl2) and prime un-shell nanoparticles CdTe QDs. Tested compounds were applied in concentrations representing 20 and 200 μM Cd. The uptake and translocation of Cd were investigated using inductively coupled plasma optical emission spectrometry (ICP-OES) and the spatial Cd distribution was investigated in detail applying laser induced breakdown spectroscopy (LIBS). The LIBS maps with a lateral resolution of 100 μm were constructed for the whole plants, and maps with a lateral resolution of 25 μm (micro-LIBS arrangement) were used to analyse only the most interesting parts of plants with Cd presence (e.g. root tips or a part crossing the root into the above-ground part). Our results show that the bioaccumulation patterns and spatial distribution of Cd in CdTe/SiO2 QDs-treated plants differ from the plants of positive control and CdTe QDs. Fluorescence microscopy photographs revealed that CdTe/SiO2 became adsorbed onto the plant surface in comparison to CdTe QDs. Further, a physico-chemical characterization of QDs before and after the test exposure showed only minor changes in the nanoparticle diameters and no tendencies of QDs for agglomeration or aggregation during the exposure.
关键词： nanoparticles,cadmium,laser-induced breakdown spectroscopy,Sinapis alba L.,uptake,translocation
更新于2025-09-23 15:19:57
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[Methods in Molecular Biology] FOXO Transcription Factors Volume 1890 (Methods and Protocols) || Immunofluorescence Analysis by Confocal Microscopy for Detecting Endogenous FOXO
摘要： Cancer cells are known to inactivate tumor suppressor proteins by triggering their anomalous subcellular location. It has been well established that the aberrant location of FOXO proteins is linked to tumor formation, progression of the same, or resistance to anti-neoplastic treatment. Furthermore, the abnormal location of FOXO has also been considered a potential biomarker for diabetic complications or longevity in different organisms. Here, we describe the immunodetection of endogenous FOXO by confocal microscopy, which can be used as a chemical tool to quantify FOXO expression levels, its cellular location, and even its active/inactive forms with relevant antibodies.
关键词： Immunodetection,Nuclear translocation,FOXO proteins,Confocal microscopy,Biomarker
更新于2025-09-10 09:29:36
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Photoactivation mechanism, timing of protein secondary structure dynamics and carotenoid translocation in the Orange Carotenoid Protein
摘要： The Orange Carotenoid Protein (OCP) is a two-domain photoactive protein that noncovalently binds an echinenone (ECN) carotenoid and mediates photoprotection in cyanobacteria. In the dark, OCP assumes an orange, inactive state known as OCPO; blue light illumination results in the red active state, known as OCPR. The OCPR state is characterized by large-scale structural changes that involve dissociation and separation of C-terminal and N-terminal domains accompanied by carotenoid translocation into the N-terminal domain. The mechanistic and dynamic-structural relations between photon absorption and formation of the OCPR state have remained largely unknown. Here, we employ a combination of time-resolved UV-visible and (polarized) mid-infrared spectroscopy to assess the electronic and structural dynamics of the carotenoid and the protein secondary structure, from femtoseconds to 0.5 milliseconds. We identify a hereto unidentified carotenoid excited state in OCP, the so-called S* state, which we propose to play a key role in breaking conserved hydrogen-bond interactions between carotenoid and aromatic amino acids in the binding pocket. We arrive at a comprehensive reaction model where the hydrogen-bond rupture with conserved aromatic side chains at the carotenoid β1-ring in picoseconds occurs at a low yield of <1 %, whereby the β1-ring retains a trans configuration with respect to the conjugated π-electron chain. This event initiates structural changes at the N-terminal domain in 1 μs, which allow the carotenoid to translocate into the N-terminal domain in 10 μs. We identified infrared signatures of helical elements that dock on the C-terminal domain β-sheet in the dark and unfold in the light to allow domain separation. These helical elements do not move within the experimental range of 0.5 ms, indicating that domain separation occurs on longer timescales, lagging carotenoid translocation by at least 2 decades of time.
关键词： protein secondary structure dynamics,photoactivation mechanism,Orange Carotenoid Protein,time-resolved spectroscopy,carotenoid translocation
更新于2025-09-09 09:28:46