Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Q: Polycomb gene silencing requires histone methyltransferase activity of Polycomb repressive complex 2 (PRC2), which methylates lysine 27 of histone H3. Information on how PRC2 works is limited by lack of structural data on the catalytic subunit, Enhancer of zeste (E(Z)), and the paucity of E(z) mutant alleles that alter its SET domain. Here we analyze missense alleles of Drosophila E(z), selected for molecular study because of their dominant genetic effects. Four missense alleles identify key E(Z) SET domain residues, and a fifth is located in the adjacent CXC domain. Analysis of mutant PRC2 complexes in vitro, and H3-K27 methylation in vivo, shows that each SET domain mutation disrupts PRC2 histone methyltransferase. Based on known SET domain structures, the mutations likely affect either the lysine-substrate binding pocket, the binding site for the adenosylmethionine methyl donor, or a critical tyrosine predicted to interact with the substrate lysine epsilon-amino group. In contrast, the CXC mutant retains catalytic activity, Lys-27 specificity, and trimethylation capacity. Deletion analysis also reveals a functional requirement for a conserved E(Z) domain N-terminal to CXC and SET. These results identify critical SET domain residues needed for PRC2 enzyme function, and they also emphasize functional inputs from outside the SET domain.

A: What is the characteristic domain of histone methyltransferases?
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Q: A study was carried out on 200 patients of ages 20-40 years suffering from acute viral hepatitis. Sera were tested for markers of hepatitis B (HBsAg, and IgM anti-HBc) and hepatitis A (IgM-anti-HAV) by the ELISA technique. Sera negative for the markers of both viruses: Hepatitis A (HAV) and Hepatitis B (HBV) were subsequently tested for IGM Heterophil antibodies against Epstein-Barr virus (EBV) by the Monospot slide test to diagnose acute infectious mononucleosis and tested for anti-CMV (IgM) by ELISA technique for the diagnosis of acute Cytomegalovirus (CMV) infection. Non-A, non-B hepatitis (NANB) was diagnosed by exclusion. The results of the study showed that 133 (66.5%) patients had evidence of HBV infection, while only 9(4.5%) were diagnosed as HAV infection. EBV and CMV were the possible etiological agents of acute viral hepatitis in (3.5%) and 1%) respectively. Accordingly the Non-A, non-B hepatitis in this study amounts to (24.5%) of the acute viral hepatitis.

A: Which virus can be diagnosed with the monospot test?
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Q: My Friend Rabbit is a children's picture book written and illustrated by Eric Rohmann.

A:
Who is the illustrator of My Friend Rabbit?
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