In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

Q: Genetic and environmental factors will influence the growth of an RNA virus, but their relative contributions are challenging to resolve because standard culture methods mask how virus particles interact with individual host cells. Here, single particles of vesicular stomatitis virus, a prototype RNA virus, were used to infect individual BHK cells. Infected cells produced 50 to 8000 progeny virus particles, but these differences were lost upon subsequent culture, suggesting the diversity of yields reflected cell-to-cell differences rather than viral genetic variation. Cells infected at different phases of their cell cycle produced from 1400 (early S) to 8700 (G 2 M) infectious virus particles, coinciding with the middle-to-upper range of the observed distribution. Fluctuations in virus and cell compositions and noisy gene expression may also contribute to the broad distribution of virus yields. These findings take a step toward quantifying how environmental variation can impact the fitness distribution of an RNA virus.

A: Growth of an RNA virus in single cells reveals a broad fitness distribution
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Q: Npl4 is likely to be the most upstream factor recognizing Lys48-linked polyubiquitylated substrates in the proteasomal degradation pathway in yeast. Along with Ufd1, Npl4 forms a heterodimer (UN), and functions as a cofactor for the Cdc48 ATPase. Here, we report the crystal structures of yeast Npl4 in complex with Lys48-linked diubiquitin and with the Npl4binding motif of Ufd1. The distal and proximal ubiquitin moieties of Lys48-linked diubiquitin primarily interact with the C-terminal helix and N-terminal loop of the Npl4 C-terminal domain (CTD), respectively. Mutational analysis suggests that the CTD contributes to linkage selectivity and initial binding of ubiquitin chains. Ufd1 occupies a hydrophobic groove of the Mpr1/Pad1 N-terminal (MPN) domain of Npl4, which corresponds to the catalytic groove of the MPN domain of JAB1/MPN/Mov34 metalloenzyme (JAMM)-family deubiquitylating enzyme. This study provides important structural insights into the polyubiquitin chain recognition by the Cdc48-UN complex and its assembly.

A: Structural insights into ubiquitin recognition and Ufd1 interaction of Npl4
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Q: The indirect immunoperoxidase (IIP) assay was compared with the reverse transcription-polymerase chain reaction (RT-PCR) for detection of 793/B serotype of infectious bronchitis virus in tissues samples collected from experimentally infected chickens. This technique was optimized in specific pathogen-free (SPF)-embryonated chicken eggs and broiler chickens inoculated with the Iranian IR/773/2001 strain of 793/B serotype The trachea, lung, kidney, and cecal tonsil tissue samples from experimentally infected chicken embryos and chickens were collected in order to prepare tissue sections in IIP assay and to detect in RT-PCR. The sensitivity and specificity values of IIP assay were, respectively, 83 and 84 %, and the positive and negative prediction values were 71 and 91 % when compared with RT-PCR.

A:
Detection of 793/B serotype of infectious bronchitis virus in tissue sample by indirect immunoperoxidase assay
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