Suzuki N
Noto Marine Laboratory, Kanazawa University, Ishikawa, Japan.
Zoolog Sci. 1995 Oct;12(5):607-10. doi: 10.2108/zsj.12.607.
Cyclostomes have been regarded as having no ultimobranchial gland. However, cells producing immunoreactive calcitonin (CT) were recently found in cyclostome brains. In the present study, we examined using biochemical and biological methods whether there is a CT-like substance in the plasma of the hagfish, Eptatretus burgeri. Hagfish plasma was first subjected to reverse-phase high-performance liquid chromatography (RP-HPLC) and then separated into twenty fractions. The presence of immunoreactive CT in each fraction was then investigated by Western blotting with salmon CT antiserum. Two fractions (36-39% CH3CN; 39-42% CH3CN) showed positive immunoreactivity. Hypocalcemic and hypophosphatemic activities were detected by a rat bioassay only in the former fraction (36-39% CH3CN). The molecular weight (MW) of the CT-like substance in this fraction was 3.5 kDa, which is equal to that of genuine CT. Furthermore, when hagfish plasma was examined by enzyme-linked immunosorbent assay using anti-salmon CT, the dilution curve of the plasma paralleled the standard curve of salmon CT. The CT-like substance detected here was present at a high concentration (14 ng/ml) in the plasma. From the results of the present study, the CT-like substance present in hagfish plasma appears to be very similar to salmon CT.
圆口纲动物一直被认为没有后鳃腺。然而，最近在圆口纲动物的大脑中发现了产生免疫反应性降钙素（CT）的细胞。在本研究中，我们使用生化和生物学方法研究了太平洋盲鳗（Eptatretus burgeri）血浆中是否存在类CT物质。首先将太平洋盲鳗血浆进行反相高效液相色谱（RP-HPLC），然后分离成20个组分。然后用鲑鱼CT抗血清通过蛋白质免疫印迹法研究每个组分中免疫反应性CT的存在情况。两个组分（36 - 39% 乙腈；39 - 42% 乙腈）显示出阳性免疫反应性。仅在前一个组分（36 - 39% 乙腈）中通过大鼠生物测定法检测到了降血钙和降血磷活性。该组分中类CT物质的分子量（MW）为3.5 kDa，与真正的CT相等。此外，当使用抗鲑鱼CT的酶联免疫吸附测定法检测太平洋盲鳗血浆时，血浆的稀释曲线与鲑鱼CT的标准曲线平行。这里检测到的类CT物质在血浆中的浓度很高（14 ng/ml）。根据本研究的结果，太平洋盲鳗血浆中存在的类CT物质似乎与鲑鱼CT非常相似。
