instruction:
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
question:
Context: In our initial attempt to identify differentiation markers for ocular surface epithelia, we observed a unique staining pattern by a commercial anti-Galphaq antibody. We further isolate and characterize the protein reactive with this anti-Galphaq antibody in human ocular surface epithelia.', 'Human donor corneoscleral buttons were sectioned and stained with a battery of commercial antibodies against Galpha proteins. Western blot analysis of cell lysates of corneal epithelial cells and HEK 293 cells transfected with Galphaq cDNA was used to determine the identity of the protein reactive with the anti-Galphaq antibody (E-17). Comparisons were made with another anti-Galphaq antibody (G4415) and an anti-cytokeratin 12C (J7) antibody. The isolated proteins reactive with E17 and J7 were then analyzed with two dimensional isoelectric focusing. Polypeptide sequences were identified using matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) after in-gel protein digestion.', 'The E-17 anti-Galphaq antibody preferentially stained the entire corneal epithelia and the suprabasal layers of the limbus with complete absence of staining in the basal limbus and conjunctiva. Western blot analysis of corneal epithelial cells showed that E-17 antibody identified a protein with a molecular weight of 55 kDa. However, the antibody did not react with the purported antigen, Galphaq protein (42 kDa) produced by Galphaq cDNA. Another anti-Galphaq antibody (G4415) did not react with the 55 kDa protein but did react with the 42 kDa Galphaq protein. Further comparison of the E-17 antibody with the J7 antibody revealed that both recognized the 55 kDa band in one and two dimensional analysis. MALDI-TOF MS analysis confirmed that the 55 kDa protein of interest was actually cytokeratin 12 (CK12), rather than Galphaq protein.\Question: Is cytokeratin 12 in human ocular surface epithelia the antigen reactive with a commercial anti-Galpha q antibody?
answer:
The commercial E-17 anti-Galphaq antibody did not react with Galphaq protein, its purported antigen. Instead, it recognized a 55 kDa protein, which was characterized to be cytokeratin 12 by isoelectric focusing and peptide fingerprinting with mass spectrometry. Based on its reactivity with CK12, this commercial E-17 can be used as a differentiation marker to study ocular surface epithelia.


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Context: Enterovirus infections are major etiological factors in myocarditis and dilated cardiomyopathy. Using an experimental murine model of this disease, previous studies have shown that myocarditis susceptibility depends upon activation of T lymphocytes expressing the gamma delta T cell receptor (TcR), and that only mouse strains which accumulate gamma delta T cells in the myocardium show apoptosis of myocytes or evidence of dilated cardiomyopathy-like disease. The objective of the present studies is to demonstrate that gamma delta T cells directly induce greater Fas-dependent apoptosis of cultured myocytes than T cells expressing the alpha beta TcR.', 'Bl.Tg.E alpha mice were infected for 7 days with coxsackievirus B3 (CVB3). Hearts were removed and were either formalin-fixed, sectioned and stained with hematoxylin and eosin for inflammation, and using TdT-TUNEL for apoptosis, or were minced and collagenase digested for isolation of gamma delta+ and alpha beta+ T cells using immunomagnetic bead separation. Neonatal cultures of cardiac myocytes were isolated from mice less than 2 days old by collagenase and pancreatin digestion, and were either untreated or infected with virus. Levels of Fas (CD95) were measured using FITC-conjugated hamster anti-mouse Fas monoclonal antibody and flow cytometry. Susceptibility of myocytes to Fas-dependent killing was measured by 51Cr-release by labeled myocytes incubated for 4 h on either 3T3-mock or 3T3-FasL transfected cell monolayers. Killing by T cells was also measured in a 4 h 51Cr-release assay. Fas-dependent and perforin-dependent cytotoxicity was determined by specific blocking using either Fas-Fc or concanamycin A.', 'Virally infected myocyte cultures showed significantly enhanced Fas expression compared to uninfected cells, with maximal upregulation of Fas occurring 18-24 h after virus infection. Both infected and uninfected myocytes were selectively killed by FasL-transfected 3T3 cells but not by mock control cells. Approximately 38% of CD3+ lymphocytes isolated from the heart express the gamma delta TcR with the remainder expressing the alpha beta TcR. Both gamma delta+ and alpha beta+ T cells lysed myocyte targets. Blocking studies indicate that gamma delta+ T cells induced predominantly Fas-mediated killing, while alpha beta+ cell produced more perforin-mediated death, although these effectors were capable of Fas-dependent killing as well.\Question: Do t cells expressing the gamma delta T cell receptor induce apoptosis in cardiac myocytes?
answer:
These studies demonstrate that T cells expressing the gamma delta TcR are more effective mediators of myocyte apoptosis than alpha beta+ T cells in vitro and suggests that these effectors may be primarily responsible for myocardial injury associated with dilated cardiomyopathy-like signs during coxsackievirus B3-induced myocarditis.


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Context: The blasticidin S resistance gene (bsr) is a selectable marker used for gene transfer experiments. The bsr gene encodes for blasticidin S (BS) deaminase, which has a specific activity upon BS. Therefore, its expression is supposed to be harmless in cells. The work reported on herein consisted of experiments to verify a possible toxicity of bsr on mammalian cells, which include several cell lines and primary cultures.', 'Murine keratinocyte BALB/MK and human primary keratinocyte cells transduced with the retroviral vector LBmSN, which has an improved expression system of bsr, namely bsrm, died in five days after the transduction. Meanwhile the control vector LBSN, which expresses bsr, did not provoke cell death. The lethal activity of bsrm was observed only in human keratinocytes and BALB/MK cells among the cell types tested here. Death appears to be mediated by a factor, which is secreted by the BALB/MK transduced cells.\Question: Is over expression of the selectable marker blasticidin S deaminase gene toxic to human keratinocytes and murine BALB/MK cells?
answer:

By our study we demonstrated that the expression of bsrm gene is toxic to human keratinocytes and BALB/MK cells. It is likely over expression of BS deaminase gene is responsible for the death.