Kasik J W, Rice E J
Department of Pediatrics, Metrohealth Medical Center, Case Western Reserve University, Cleveland, Ohio 44109, USA.
Placenta. 1995 Jan;16(1):67-74. doi: 10.1016/0143-4004(95)90082-9.
To identify genes that exhibit increased expression in the placenta during late pregnancy, the technique of differential cDNA library screening was used to isolate a clone subsequently identified as the 3' untranslated region of the mouse selenoprotein p gene. Random primed radiolabelled cDNA probes were constructed from this clone and these probes were used to conduct Northern hybridizations against total RNA purified from mouse placenta, liver (maternal and fetal) and uterus collected sequentially during the latter third of pregnancy. Signal is present in the placenta and beginning 4 days before birth, the level of message increases, reaching maximal levels at term. The level of expression in the placenta at maximum is approximately 25 per cent of that observed in adult liver. In liver obtained from pregnant females, the level of message is increased compared to nonpregnant adults, but returns to normal shortly after birth. Message is also found in the fetal liver beginning at 4 days before birth and exhibits a pattern of expression similar to the placenta. The similarity of expression observed in fetal liver and placenta suggests a coordinated regulation of expression of this gene in these tissues. There is a minimal amount of signal present in the uterus and the expression does not appear to vary. We speculate that selenoprotein p may play a role in the transplacental transport of selenium to the fetus during late pregnancy.
为了确定在妊娠晚期胎盘内表达增加的基因，采用差异cDNA文库筛选技术分离出一个克隆，随后鉴定为小鼠硒蛋白p基因的3'非翻译区。从该克隆构建随机引物放射性标记的cDNA探针，并用这些探针与在妊娠后期依次收集的小鼠胎盘、肝脏（母体和胎儿）及子宫中纯化的总RNA进行Northern杂交。胎盘中有信号，且在出生前4天开始，信号水平升高，足月时达到最高水平。胎盘最高表达水平约为成年肝脏中观察到的表达水平的25%。在怀孕雌性的肝脏中，信号水平相较于未怀孕的成年动物有所升高，但在出生后不久恢复正常。在出生前4天开始，胎儿肝脏中也能检测到信号，且呈现出与胎盘相似的表达模式。胎儿肝脏和胎盘表达的相似性表明该基因在这些组织中的表达受到协同调控。子宫中存在极少量信号，且表达似乎没有变化。我们推测，硒蛋白p可能在妊娠晚期将硒经胎盘转运至胎儿的过程中发挥作用。
