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Histone variants, present in various cell types and tissues, are known to exhibit different functions. For example, histone H3.3 and H2A.Z are both involved in gene expression regulation, whereas H2A.X is a specific variant that responds to DNA double-strand breaks. In this study, we characterized H4G, a novel hominidae-specific histone H4 variant. We found that H4G is expressed in a variety of human cell lines and exhibit tumor-stage dependent overexpression in tissues from breast cancer patients. We found that H4G localized primarily to the nucleoli of the cell nucleus. This localization was controlled by the interaction of the alpha-helix 3 of the histone fold motif with a histone chaperone, nucleophosmin 1. In addition, we found that modulating H4G expression affects rRNA expression levels, protein synthesis rates and cell-cycle progression. Our data suggest that H4G expression alters nucleolar chromatin in a way that enhances rDNA transcription in breast cancer tissues.

In this letter, a series of inverse continuous modes for implementing highly efficient broadband power amplifiers (PAs) are proposed. These series of inverse continuous modes are extended from continuous Class-F −1 mode. A broadband PA, which operates across 2.4-3.9 GHz, is designed based on the series of inverse continuous modes (SICMs). The experimental results show that this power amplifier achieve drain efficiency of 62.2%-74.7% in the whole interesting band. The average output power of this designed PA is 11.9 W with average drain efficiency of 68.1%.Index Terms-Broadband, class-F −1 , high efficiency, power amplifier, series of inverse continuous modes.

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