内含子是真核生物中普遍存在的一种非编码序列，但其功能和代价一直存在争议。近来越来越多的研究表明内含子的存在及内含子的拼接可以在转录，转录后加工，mRNA转运甚至蛋白质的翻译等各个水平上促进基因的表达，但关于内含子和mRNA稳定性的关系并没有一个一致的结论。我们系统分析了人、酵母、拟南芥基因组中内含子有无、个数等和mRNA稳定性的关系，发现在人类基因组中有内含子的基因的mRNA比没有内含子的基因的mRNA更稳定。我们还进一步控制了mRNA长度、基因功能、富含AU序列元件等影响mRNA稳定性的因素来检测内含子有无和mRNA稳定性的关系，我们发现仍然是有内含子的基因的mRNA更稳定。拟南芥中94个mRNA最不稳定的基因中没有内含子的基因占36.2%，而基因组中的其他基因没有内含子的占19.8%。94个最不稳定的基因中有内含子的基因的内含子个数也明显少于基因组中注释的其他有内含子的基因。控制mRNA长度后人类基因组mRNA稳定性和内含子个数存在显著的正相关。但在芽殖酵母中，三组稳定性数据得到相反的结论。负责内含子拼接的核糖核蛋白复合体（mRNPs）的组成蛋白在内含子拼接时会聚集或结合到外显子-外显子结合处，我们推测它们可以作为mRNA稳定性的信号，或者就是简单地作为绝缘体，防止内源或外源的RNA与mRNA结合引发的mRNA的降解，从而起到增加mRNA稳定性的作用。我们还发现在人类基因中GC含量和mRNA稳定性也存在很强的相关性。

Introns are widespread noncoding sequences in eukaryotic genomes, their cost and benefit to the host are still not well established. Recently, introns were found to enhance almost every steps of gene expression, including initial transcription of the gene, editing and polyadenylation of the pre-mRNA, and nuclear export, translation, except increasing mRNA stability. By analyzing the genome-wide data of mRNA stability published previously, we found that human intron-containing genes have more stable mRNAs than intronless genes. We further tested the relationship between intron presence and human mRNA stability after controlling other biological characters, such as gene function, AU rich motif, our results are still robust. The Arabidopsis thaliana genes with the most unstable mRNAs have fewer introns than other genes in the genome. Furthermore, we found mRNA stability is positively correlated with intron number in human intron-containing genes. But in yeast Saccharomyces cerevisiae, two different datasets on mRNA half-life gave conflicting results. The components of messenger ribonucleoprotein particles recruited during intron splicing may be retained in cytoplasmic mRNPs and act as signals of mRNA stability or simply insulators to avoid mRNA degradation. We also found that GC contents are significant positively correlated with mRNA stability in human, suggesting that GC content is an important biological characters that can influence mRNA stability.