Facchin Lucilla, Burgess Harold A, Siddiqi Mahmud, Granato Michael, Halpern Marnie E
Department of Embryology, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA.
Philos Trans R Soc Lond B Biol Sci. 2009 Apr 12;364(1519):1021-32. doi: 10.1098/rstb.2008.0234.
As in many fishes, amphibians and reptiles, the epithalamus of the zebrafish, Danio rerio, develops with pronounced left-right (L-R) asymmetry. For example, in more than 95 per cent of zebrafish larvae, the parapineal, an accessory to the pineal organ, forms on the left side of the brain and the adjacent left habenular nucleus is larger than the right. Disruption of Nodal signalling affects this bias, producing equal numbers of larvae with the parapineal on the left or the right side and corresponding habenular reversals. Pre-selection of live larvae using fluorescent transgenic reporters provides a useful substrate for studying the effects of neuroanatomical asymmetry on behaviour. Previous studies had suggested that epithalamic directionality is correlated with lateralized behaviours such as L-R eye preference. We find that the randomization of epithalamic asymmetry, through perturbation of the nodal-related gene southpaw, does not alter a variety of motor behaviours, including responses to lateralized stimuli. However, we discovered significant deficits in swimming initiation and in the total distance navigated by larvae with parapineal reversals. We discuss these findings with respect to previous studies and recent work linking the habenular region with control of the motivation/reward pathway of the vertebrate brain.
与许多鱼类、两栖动物和爬行动物一样，斑马鱼（Danio rerio）的上丘脑在发育过程中表现出明显的左右不对称性。例如，在超过95%的斑马鱼幼虫中，松果体附属器官副松果体在大脑左侧形成，相邻的左侧缰核比右侧的更大。Nodal信号通路的破坏会影响这种偏向性，产生副松果体在左侧或右侧的幼虫数量相等，且相应的缰核发生反转。使用荧光转基因报告基因对活幼虫进行预筛选，为研究神经解剖学不对称性对行为的影响提供了有用的基础。先前的研究表明，上丘脑的方向性与诸如左右眼偏好等偏侧行为相关。我们发现，通过干扰与Nodal相关的基因southpaw使上丘脑不对称性随机化，并不会改变包括对偏侧刺激的反应在内的多种运动行为。然而，我们发现副松果体反转的幼虫在游泳启动和游动的总距离方面存在显著缺陷。我们结合先前的研究以及最近将缰核区域与脊椎动物大脑动机/奖励通路控制联系起来的工作，对这些发现进行了讨论。
