Wargelius Anna, Fjelldal Per Gunnar, Nordgarden Ulla, Hansen Tom
Institute of Marine Research, Bergen, Norway.
J Exp Biol. 2009 Mar;212(Pt 5):656-61. doi: 10.1242/jeb.024000.
In order to study the effects of photoperiod on fish bone, Atlantic salmon (Salmo salar L.) were exposed to two light regimes (natural and continuous light) from January until June. During the experimental period, several parameters related to the inorganic (minerals) and organic (osteoid) phases were measured. Changes in the organic phase were related to mechanical strength (yield-load) and the expression of the genes sonic hedgehog (shh) and collagen type I alpha 2 (col I). Co-variation between yield-load and the expression of both shh and col I were detected in both groups. It was also shown that fish on the continuous light regime had delayed activation of osteoid incorporation. Mineralization properties were measured with stiffness, mineral incorporation per day and expression of alkaline phosphatase (alp) and matrix Gla protein (mgp). Stiffness, mineral incorporation and gene expression followed the same trend in both light groups in late spring, whereas an increase in the expression of mgp and alp was detected in April, followed by significantly higher stiffness at last sampling in both light groups. These results indicate that constant light affects mineralization and delays osteoid incorporation in Atlantic salmon during the spring. However, in this experiment light treatment did not promote the development of vertebral deformities. Our results also suggest that shh can be used as a marker of osteoblast proliferation and col I a marker of osteoid incorporation, and that both alp and mgp expression could be associated with a rapid increase in mineralization in Atlantic salmon vertebrae.
为了研究光周期对鱼骨的影响，从1月到6月，将大西洋鲑（Salmo salar L.）暴露于两种光照条件下（自然光和持续光照）。在实验期间，测量了与无机（矿物质）和有机（类骨质）相相关的几个参数。有机相的变化与机械强度（屈服载荷）以及音猬因子（shh）和I型胶原蛋白α2（col I）基因的表达有关。在两组中均检测到屈服载荷与shh和col I表达之间的协变。还表明，处于持续光照条件下的鱼延迟了类骨质掺入的激活。用硬度、每日矿物质掺入量以及碱性磷酸酶（alp）和基质Gla蛋白（mgp）的表达来测量矿化特性。在晚春，两个光照组的硬度、矿物质掺入和基因表达都呈现相同的趋势，而在4月检测到mgp和alp的表达增加，随后在最后一次采样时两个光照组的硬度均显著更高。这些结果表明，持续光照会影响矿化并延迟春季大西洋鲑的类骨质掺入。然而，在本实验中，光照处理并未促进脊柱畸形的发展。我们的结果还表明，shh可作为成骨细胞增殖的标志物，col I可作为类骨质掺入的标志物，并且alp和mgp的表达都可能与大西洋鲑椎骨矿化的快速增加有关。
