Left-handed DNA-PAINT for improved super-resolution imaging in the nucleus.

DNA point accumulation in nanoscale topography (DNA-PAINT) increases the resolution and multiplexing capabilities of super-resolution imaging, but cellular DNA interferes with DNA-DNA hybridization between target and probe in the nucleus. Here, we introduce left-handed DNA (L-DNA) oligomers that do not hybridize to natural right-handed DNA (R-DNA) and demonstrate that L-DNA-PAINT has the same specificity and multiplexing capability as R-DNA-PAINT, but improves the imaging of nuclear targets by substantially reducing background signal.

Imaging Mass Spectrometry and Proteome Analysis of Marek's Disease Virus-Induced Tumors.

The highly oncogenic alphaherpesvirus Marek's disease virus (MDV) causes immense economic losses in the poultry industry. MDV induces a variety of symptoms in infected chickens, including neurological disorders and immunosuppression. Most notably, MDV induces transformation of lymphocytes, leading to T cell lymphomas in visceral organs with a mortality of up to 100%. While several factors involved in MDV tumorigenesis have been identified, the transformation process and tumor composition remain poorly understood. Here we developed an imaging mass spectrometry (IMS) approach that allows sensitive visualization of MDV-induced lymphoma with a specific mass profile and precise differentiation from the surrounding tissue. To identify potential tumor markers in tumors derived from a very virulent wild-type virus and a telomerase RNA-deficient mutant, we performed laser capture microdissection (LCM) and thereby obtained tumor samples with no or minimal contamination from surrounding nontumor tissue. The proteomes of the LCM samples were subsequently analyzed by quantitative mass spectrometry based on stable isotope labeling. Several proteins, like interferon gamma-inducible protein 30 and a 70-kDa heat shock protein, were identified that are differentially expressed in tumor tissue compared to surrounding tissue and naive T cells. Taken together, our results demonstrate for the first time that MDV-induced tumors can be visualized using IMS, and we identified potential MDV tumor markers by analyzing the proteomes of virus-induced tumors.IMPORTANCE Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that infects chickens and causes the most frequent clinically diagnosed cancer in the animal kingdom. Not only is MDV an important pathogen that threatens the poultry industry but it is also used as a natural virus-host model for herpesvirus-induced tumor formation. In order to visualize MDV-induced lymphoma and to identify potential biomarkers in an unbiased approach, we performed imaging mass spectrometry (IMS) and noncontact laser capture microdissection. This study provides a first description of the visualization of MDV-induced tumors by IMS that could be applied also for diagnostic purposes. In addition, we identified and validated potential biomarkers for MDV-induced tumors that could provide the basis for future research on pathogenesis and tumorigenesis of this malignancy.

Elimination half-life of intravenously administered equine cardiac troponin I in healthy ponies.

REASONS FOR PERFORMING STUDY: To date, no information is available on the true biological elimination half-life (T(1/2) ) of cardiac troponin I (cTnI) in the equine species. Such data are required to better evaluate the optimal time to acquire the cTnI sample following acute myocardial injury. OBJECTIVE: To determine the T(1/2) of equine cTnI. METHODS: Four healthy ponies received i.v. injections of recombinant equine cTnI. Plasma cTnI concentrations were measured with a point-of-care cTnI analyser at multiple time points after injection. Standard pharmacokinetic analysis was performed to establish the T(1/2) of cTnI. RESULTS: The average T(1/2) of cTnI was determined to be 0.47 h using a single rate elimination model. CONCLUSION: The elimination of recombinant equine cTnI following i.v. administration is very rapid. Establishing the T(1/2 ) of troponin provides critical information in understanding the clinical application of this cardiac biomarker in equine practice.