4龄中华鲟垂体的EST分析

表达序列标签 (Expressed sequence tag, EST) 是鉴定基因表达规律和发现新基因的一种有效的分子生物学手段。为了能在中华鲟(Acipenser sinensis Gray) 中发现与生长和生殖内分泌调控相关的基因，我们构建了中华鲟垂体的SMART cDNA质粒文库。垂体是调节生长和生殖内分泌的重要器官。在本研究中，通过测序筛选得到了944个EST克隆，将所得EST 与 GenBank 数据库中的序列进行比对， 结果表明，802 (84.96%) 个克隆可以找到同源序列，共代表461个基因, 其中含132个已知功能基因；而 142 (15.04%) 个克隆不能找到同源序列。研究发现，在所有基因中，阿黑皮素原基因 (Proopiomelanocortin, POMC) 是出现次数最高的基因，占总EST数的10.17%， 显示出其在垂体中的重要地位。我们还发现了7个未知功能的基因并重点研究了其在心脏、肝脏、脾脏、肾脏、肌肉、精巢、卵巢和垂体等组织中的表达特异性。结果发现，4个基因：EG009334、EG009337、EG009338 和 EG009340为垂体特异性表达或垂体和卵巢特异性表达。对这些基因进一步的功能研究将有利于我们更好地了解中华鲟生长和生殖内分泌调控的分子机制。

Expressed sequence tag analysis of a 4 year-old Chinese sturgeon pituitary

Expressed sequence tag (EST) analysis is an efficient tool for gene discovery and for profiling gene expression. In order to isolate specific functional genes involved in reproduction and endocrine regulation and to reveal their evolutionary mechanisms in Chinese sturgeon (Acipenser sinensis Gray), a chondrostean fish with a history of 140 million years, we constructed its pituitary cDNA library from a 4 year-old male. A total of 944 random clones were sequenced and compared with sequences in GenBank database. Among all the 944 EST clones, 802 (84.96%) clones were identified as 461 known genes, and additional 142 (15.04%) as unknown genes. Functional categorization indicated that the most abundantly expressed functional gene was the proopiomelanocortin (POMC), which accounted for almost 10.17% of the overall expression, indicating its important function in the pituitary. Interestingly, the expression patterns of 7 unknown genes were analyzed in various tissues, such as heart, liver, spleen, kidney, muscle, testes, ovary and pituitary. Three different categories of expression patterns were observed from them. Several unknown ESTs, such as EG009334, EG009337, EG009338 and EG009340, were detected to be pituitary-specific, or pituitary and ovary-specific genes. Further studies on their functions will be very useful for better understanding the mechanisms of sturgeon reproduction biology and endocrinology.