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During the maternal-to-zygotic transition (MZT), maternal RNAs are actively degraded and replaced by newly synthesized zygotic transcripts in a highly coordinated manner. However, it remains largely unknown how maternal mRNA decay is triggered in early vertebrate embryos. Here, through genome-wide profiling of RNA abundance and 3' modification, we show that uridylation is induced at the onset of maternal mRNA clearance. The temporal control of uridylation is conserved in vertebrates. When the homologs of terminal uridylyltransferases TUT4 and TUT7 (TUT4/7) are depleted in zebrafish and Xenopus, maternal mRNA clearance is significantly delayed, leading to developmental defects during gastrulation. Short-tailed mRNAs are selectively uridylated by TUT4/7, with the highly uridylated transcripts degraded faster during the MZT than those with unmodified poly(A) tails. Our study demonstrates that uridylation plays a crucial role in timely mRNA degradation, thereby allowing the progression of early development.

This study examines the risk features of hotel real estate investment trust (REIT) firms. In particular, it investigates the systematic and unsystematic risk of hotel REIT stocks and the determinants of their systematic risk, or beta. Using the financial data of 19 U.S. hotel REIT firms from 1993 through 1999, the authors found that 84% of the firms'total risk was contributed by firm-specific, unsystematic risk. Systematic risk correlated positively with debt leverage and growth but negatively with firm size. These findings suggest that growth via mergers and acquisitions and less reliance on debt financing may help lower systematic risk and enhance hotel REITs'value.

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