南极鱼类DNA条形码及分子系统进化研究

本文采用COI基因兼并引物对15种36个南极鱼类DNA进行扩增测序,并结合Gen Bank已有序列进行联配分析,对南极鱼2科22属43种共97条COI基因片段(539 bp)进行序列比较和系统发生关系研究,探索了DNA条形码技术在辅助鱼类物种鉴定和分类中的适应性与可行性。结果分析表明,43种南极鱼科和鳄冰鱼科的鱼类COI基因的平均碱基组成为T:31.9%、G:18.3%、A:22.2%和C:27.6%,具有明显的碱基偏倚性。南极鱼类的种间平均距离为0.157,种内平均遗传距离为0.002,种间平均遗传距离是种内平均距离的79倍;系统分析结果显示,除南极小带腭鱼(Cryodraco antarcticus)和罗斯海小带腭鱼(Cryodraco atkinsoni)外,其余的鱼类皆能够形成独立的分支,且与形态学分支一致。由此可见,DNA条形码对南极鱼亚目鳄冰鱼科和南极鱼科鱼类能够进行有效的物种鉴定,基于COI基因所建的NJ(neighbor-joining)树对物种分类具有较为准确的辨识力。系统发生关系表明,DNA条形码可以对除南极小带腭鱼(Cryodraco antarcticus)和罗斯海小带腭鱼(Cryodraco atkinsoni)外的南极鱼物种进行鉴定,不仅可以作为形态学的辅助手段为南极鱼分类系统的必要补充和佐证,并且可以用于探讨南极鱼类近缘种的系统发育关系。     

In vivo calcitropic effect of some vitamin D compounds in the marine Antarctic teleost,Pagothenia bernacchii

The Antarctic notothenioid, Pagothenia bernacchii, were found to have plasma total and free calcium levels, plasma inorganic phosphate and whole body calcium efflux rates which were similar to those seen in other teleosts. But total bone calcium was lower than reported for other teleosts. A single injection of vitamin D₃ (5 ng g^–1 fish) increased plasma total and plasma free calcium and these increases were associated with an increase in whole body calcium efflux and bone calcification. Conversely, the same treatment with 1,25-(OH)₂-D₃ reduced plasma free calcium. This seco-steroid also increased the specific activity of ⁴⁵Ca in bone at 40h post-injection but did not significantly effect total bone calcium, plasma total calcium or whole body calcium efflux. 25-OH-D₃ at the same dose had no effect on any of the parameters tested and none of the seco-steroids tested had any effect on plasma total inorganic phosphate. These data show that both D₃ and 1,25-(OH)₃-D₃ can have calcitropic effects in this marine teleost and that these two forms of vitamin D can exert different effects within the same species.